BAI GIANGVAT LIEU DIEN

CHI/ONG 1 KHAI NIEM VE VAT L@U DIEN

Muc dich chuong nity nhac lai mot so kin thlic cc b:in da du9c hpc o phfi thong trung hpc c:in thie't ve can tao vat chat truoc khi nghien ciiu nhfing v:it lieu ky thuat dim cu th.1 . 1.KHAI NIEM VE VAT LIEU DIEN1 . 1. 1. KHAI NIEMVat lieu di n 1:i twit ca nhfing chat lieu dung d san suat cac thit b| su dung trong linh vuc nganh dien. Thuong duoc phan ra cac vat lieu theo dac diem, tinh ch:it va cfing dung cua no, thung la cac vat lieu dan dien, vat lieu cach dren, vat lieu ban dan vii v)at lies dan ttr.1 . 1 . 2.CAU TAO NGUYEN TU CUA VAT LIEUNguyen tu I:i ph:in tu cc ban nhat cua v:it chat. Mpi vat ch:it du ducic can tao tu nguyn tu vii phiin tu theo mo hinh nguyn tu ciia Bo.Nguyen tu dupc c:iu tao boi hat nh:in mang dren tich duong (gom proton p v:i notron n) va cac dim tu mang dien tich :im (electron, ky hi u la e) chuyn dong xung quanh hat nhan theo mot guy dao xac dinh.Nguyen tu : La ph:in nlio nhat cua mot phan tu co the tliam gia phan ring hoa hoc, nguyn tu gom co hat nhan v:i lip vo dim tir hinh 1. 1 mcocac- Vo hat nhan gfim cac electron chuyn dongxung quanh hat nhan theo quy dao xac dinh.Tuy theo mfrc nang luong in:i cac dien tu duiyc xe' H at1nann iop.

O diu kin binh thuo'ng, nguyn tu trung hfia 1 Z(+)hat nh:in- 1 Z()eKhoi lu9ng cua e r:it nho: e- 9, 1 . 10 ' (Kg)9e - I ,60 1 . 10 ' (C)

la:

Do dien tu co khfii luong rat nlio cho nn do linli hoat cua toc do chuyn dong kha cao. fi mot nhiet dfi nhat dinh, toc do chuyen dong ciia electron r:i t cao. Nu vi nguyn nhfin n:to do mfi t nguyn tf r b! >a t dren tu e thi no tree thanli ton (+), cfin nu nguyn tu n1i:in them e thi no tro thanli Ion (-).

2

VAT LIEU DIENuatr nenonguyen tu trungoa tro I anen tu tuo ay on (+) duoc gpi lit qua trinh Ion hoa.De co khai in ve nang luong cua dien tu xt trirfing hpp don gian cua nguyn the Hydro, ngiiyen tu nity du9c cau tao tu mot proton v:i mot dien lii e (hinh 1 .2).

Khi dien tu chuyn dong trn guy dao co ban kinli r bao quanh hat nhan, thi gi tia hat nhan va dien tu e co 2 luc:

va luc ly tarn:

Hinh I. 2. Mo h inh nguyn tit H

trong do:

in - khoi luong cfia dien tu,v - van toc d:ii cua chuyen dong tron

O trang thai trung hfia, hai luc nay b:in bang: f = f hay mv=(1 -3)

2trong do: T

-2r2rhay2r

(1 -4)

Biu thuc trn ch ting to

cua nguyn tir du tuong irng vfii

mot muc nang luwng nhat dinh va d di chuyn no toi guy dao xa hon phai cung cfip nang luong cho dien tu,... Nang lup'ng cua dien tu phu thuoc vao ban kinh quy dao cliuyn dong. Dien tu ngoai cung co muc nang luong thap nhat do do de bi but ra va tro thanh trang thai tu do. Nang luong cung cap cho dien tu e d no try' thanh trang thai tu do goi I:i nang luong Ion hoa (W,).De tacli mot dien tu tro' thanh trang thai tu do thi phai can mot nang luong W, ? W,. Klii W, < W, clii kicli thich dao dong trong mot khoang tlioi gian rat ngan, cac nguyn tir sau do lai tro ve trang thai ban dau.

VAT LIEU DIENang uong on oa cung cap c o nguyen tu co t e a nang uo'ng n et, nang lung dien trumg ho Mac do va chain, n;ing luong tia tu ngoai, tia cuc tim, phong xa.Nguoc lai voi qua trinh Ion hoa lit qua trinh ke't hpp: Nguyn tue - ton (-).Ion (*)e --- nguyn tu, ph:in tu trung 1ioa.

1.1.3. 3.CAU TAO PHAN TU' CUA VAT LIEUL:i ph:in nho nhat cua mot ch:it o trang thai tu do no mang day du cac dam dim, tinh chat cua chat do, trong phan tu cac nguyn tir lin kt vfii nhau bo'i lien kt 1ioa hoc.V:it chat duoc c:iu tao tu nguyn, phan tu hoac ion tlieo cac dang lien ket dust day:1.1.3.1. Lin kt diing ha tryLien kt n:iy dac tiirng boi su kien l:i mot so dien tu da tro th:inh chung cho cac nguyn tu tliam gia hinh thanh phan tu.L:iy cau triic cua ph:in tu clo lam vi du: phan tu nay gfim 2 nguyn tu clo va nhu da bit, nguyn tir clo co 17 din tu, trong do 7 dien tu w lip ngoai cung (dien tu hoa tri). Hai nguyn tu clo lien kt bn vfrng viii nhau bang cach su dung chung hat dien tu nhu tren hinh 1.3 . L6p vo ngo:ii chug cfia moi nguyn tu duoc bfi sung them mot dien tu ciia nguyen tir kia.

Hinh 1.3.

Ph:in tu lien ket dong hoa tri co the lit trung tinh hoa)c cuc tinh. Ph;in tu clo thuoc loai trung tinh vi cac trung t:im dien tich duwng v:i dien tich during triing nhau.Axit cloliydric HCI la vi du cua phan tu cuc tinh. Cac trung t:inn dien tich duong vii rim cach nhan mfit kho:ing v:i nhu vay ph;in ttr n;iy duoc xem nhu mot lung circ dien.Thy theo can trfic cac phan tu dfii xf rng hay khong doi xfrng ma chia cac ph;in tfi ra trim hat loai- Phan tu khfing phan cuc la ph:in tu in:i trong t:inn dien tich :im triing voi trong t:inn din tich duong4

ian tu p an cuc a p an tir ma tainien ticam cac trong taintentich during mot Shoring 1De dam trung cho su phan cue ngufii ta doing mo men lung circ

Trong do:q: I:i din tichI: co chiu q den *q va co do Ibn bang I( khoang cach gifra trpng trim dien tich duong va trong tarn dien tich him)1.1.3.2. Lin ket IonLien kt ion du9c xac lap bwi luc hut giua cac Ion (+) va Ion(-). Lien kt n:iy chi xay ra gifra cac nguyn tu cua cac nguyn to hoa hoc co tinh chat khac nhau.Dac trirng cho dang lien ke't kim loai I:i lin ke't giua cac kim loai va phi kim de tao thanh mufti, cu the la Halogen va kim loai kim goi la mufti Halogen ciia kim loai kim.Lien kt n;iy kha bn wing. Do vay nhiet do nong chiiy ciia cac ch;i t co lien ke't Ion rfit caoVi du: 1ien ke't giua Na vii Cl trong mufti NaCl la 1ien ke't ion ( vi Na co 1 electron top ngoai cung cho nn de nhu rig 1 electron tao th:Huh Na, Cl co 7 electron ci hip ngoai cung cho nn de nhan 1 electron tao thanh Cl , hai ion nay trai dan sC hut nhau va tao thanh phan tfr NaCl, muoi NaCl co tinh hut am

Khi khong k dn chuyn dong nliit th i cc hat (gom nguyn tv, plicin tu: hoac t vi tri done .s p xp theo mI trt Iti xc dinh hapthanh mang tinh th.

Hinh 1.4. Mang tinh the cc hnctia kim loai

Hinh 1 .4 la mang tinh the 1:ip phuong (cc ban) cua kim loai.Dang lien kt nay giai thich duoc nliiing tinh ch:it dac trung cua kim loai:

VAT LIEU DIENn nguyenoranuc ut g ua cac on am va cacen tu tao nen I n nguyn khoi, kim loai thucing o dang mang tinh the Tinh deo: do su dich chuyn v:i trirot ln nhau cua cac ion Do ton tai cac dien tir tu do nn kim loai thucing co anh kim, dan dien vadan nhiet cao.1.1.3.4. Lin k t Vn nDecVan:Tuong tu nhu lien kt kim loai nhung la lien kt yu, do v:iy nhit do nong chay thiip (Vi dq: paraphin).1.1.4. NHG KHUYET TAT TRONG CAU TAO VAT RANThuc te' cac mgng tinh the co ket ciiu dong de u hay khfi ng dong deu, tuy nhien trong ky thuat ngucii ta thucing sir dung cac nhiing vat lieuh co cau trtic dong du. Su pha hfiy cac kt cau du v:i tao nen cac khuyt tat trong vat ran thuong gap nhiu trong thuc t. Nhfing khuyt t:it co the duoc tao nn bang su ngau nhin liay co y trong qua trinh cfing nghe ch tao v:it lieu.Khuyt tat trong vat ran : La bat ky 1 hien tuong n:to lam cho trung tinh dien cfia mang tinh the m;it tinh chs ky.Cac dang khuyet tat trong v;it ran thuiig 1:i : tap chat, doan thing, khe ranh .. Khuyt tfit trong v:it dan thu'ng tao nhiing tinh chat vat ly dac biet, duoc ting dung trong ky thuat cac vat lieu v:i cac dung cu khac nhau

Lo trfi ngTinh th IQ tubingChva tap chfit

Chn nguyn tu

Dich chuyn

6

Tren hinh 1 .5 cho so dfi phan bo viing nang lupng cfia v a)t ran fi nhit dotuyt doi 0K.Moi mot dien tu deu co mot mfrc n:ing l trpiig nhat dinh. Cac dien ttr hoa tri cfia lip ngoiii ciing o nhit do 0K chung tap trung lai th;inh mot wing, goi l:i vilng hoa tri hay viing day (1).Cac dien tu ter do co mire n:ing lupng cao hon t:ip hpp lai thanh dai do goi la viing tu do hay viing dan (2).Gifia wing day va viing tip do co mot viing trong goi la viing cam (3).

Vung if do (vng dan)

Vu ng dy (vung ho tri)

Hinh I. 5. So do plin bo viing nng trang Pa va I run ' 0" K

VAT LIEU DIEN

to nongen tu tro t an trang

tuo tuy t eo muco nang nong

tu cao xufing th:ip.Dna vao ly thuyt phan wing nang luong, ngufii ta chia ra vat lieu ky thuat dien th:inh: vat lieu dan dien, v(at lieu cach dien vii vat cach dien (chart dien moi).Di vi va t liu cch din (hinh 1.6c): Vting dan (2) rfit nho.Vti ng cain (3) rong tcii muc fi diu kiln binh thucrng cac dien tu hoa tri tuy duoc cung cap them nang luong cua chuyn dong nhiet van klifi ng the di chuyn tfii vil ng dan (2) de trot thanh ter do.Nang luong AW cua wing (3) lain, AWpp = 1,5 : v:ii eVNhu v;iy trong die u kien binh thuong v a) t lieu co dien dan bang khfing (hoac nho khong dang k).

a) b)

dinh hoan toan. Chung co th chuyn doi tu va) t dan sang ban dan hoac cach dien hoac ngu9c lat... by thuoc vao nang luwng tac dong gi tia chung hay phu thuoc vao diu kiln tac dong cua moi trucrng. fi dieu kien n:iy co the la vat cach dien nhung o dien kin khac no lat tro thanh vat dan dien.Ngoai cach ph:in loai vat lieu new tren, dua v:to do tu th:inn p nguoi ta cfin phan loai vat lieu theo tu tinh.Nhfrng chat co do tii tham:p > 1 : gpi la va) t lien thuan tu.;i< 1 : goi la v:it lieu ngliich tu. J > 1 : gpi l;i vat lieu dan tu.

th thay dfi i nhat tac dong nang luong tu ben ngoai. Chiu rong v rig cam chat ban dan b (AW-0,5- 1,5eV), do do w nhiet do binh thug mot

VAT LIEU DIENguyen n an c u yeu cua vat eu gay nen tu t n a o cac en I c c uyen dong ngani theo gut dao kin tao ne n nhung dong dien vong. Cu the hon do I:i do sir quay cua cac dien tu xung quanh trpc cua chung spin dien du va st quay theo gut dao ciia cac dien tit trong nguyen tu.- Cac dien lii chuyn dong xung quanh hat nh:in tao ne n dong dien cc b:in inn no duoc dac trung boi mfimen tu M. Mone tu M tinh bang tich ciia dong dien cc ban vfii mot dien tich S ducic gicii han bcii dung n cci ban:M = i. SChiu vc to M dupc xac dinh theo quy tac van nutchai . hinh 1.7 va theo phuong thang goc vfii dien tich S.Mfimen tu cua vat the la kt qu:i tong hop cua tfit ca cac mfimen tu co' ban da nu trn. Ngo:ii cac mfimen gut dao da nu tren, cac dien tu naycon quay xung quanh cac truc cua no, do doHuh I. Bank dee when momen Gcon tao ne n cac momen gpi la mfimen Spin. Cac spin nity dong vat tro quan trpng trong viec tu hoa vat lien sat tu. Khi nhieI do du'i nhiet do curri, viec hinh th:inh cac dong xoay chiu nay co the nhin th;iy dapc bang m;it thum g, du9c gpi 1;i v(i ng tu tinh, v rig n;iy tro nn song song thang hang cung mfi t hucing. Nhu v:iy v:it lieu sat tu the hin chu yu su phan cue tu hoa tu phat khi khong co cac tii trucrng dat bn ngoai. Qtia trinh tu hoa cua vat lieu sat tu dufii tac ding cua tu trirong ngoai dan de'n I:inn t;ing nhung khu viJc inn momen tu ciia no tao goc nho nh;it vcri hufing cua tir truong, giam kich ct cac wing khac va sap xp thang hang cac mfimen tu tinh theo hung tu timing ben ngoai. Su bao hoa tu tinh s dat duoc khi nao su tang ln cua khu vuc dung tu lai v:i mfimen tu tinh cua t:it ca cac ph:in tinh the nlio nh:it duoc tu tinh 1ioa tuh sinh tro th:in1i cung hucing theo hucrng cua tu trircrng

tuoaoc I eo cannono mo rong I eonongnong c eonghia lit co lat theo hucrng tu hoa, hien ttrong do gpi 1:i hien tuong tu giao.

1- Sat dac biet tinh khie'I2- Sat tinh khit (99,98% Fe)3- - Satthuat tinh khiet (99,92%Fe) 4- Pecmanloi (78%Ni)5- S- Niken6- Hpp kim Sat- Niken (26%Ni)Theo tu tinh nguoi ta ph:in v:it lieu thanh nghic tu, thuan tu va dan tu1. Nghich ID : lit nhung chat co do tu tham {i < 1 vii khfing phu thuoc v:to cuong do tu tracing ben ngoai . Loai n:iy gfim co Hydro, cac khi him, da socac kim loai nha : dong, ke"m, bac, v:ing,

VAT LIEU DIEN. mis fix a n King c at co o tu I ;i va cung ong p u I upc vao cung dfi tu trirong bn ngoai. Loai n:iy mcooxy, nito oxit, mufti sat, cac muoi coban va niken, kim loai kim, nhom, bach kim3. Chat din to : la cac chfit co 9 > I v:i phu thuoc v:to curing dfi tit trucingben ngoiii. Loai n:iyin co : sat, niken, coban, vii cac hpp kim ciia chfing

CAU HOI CH1/NG I1. Trinh bay cau tao nguyn tu, phan tu, ph:in biet ch:it trung tinh va ch:it cue tinh ?2. Trinh bay nguyn nhan gay ra nh ting khyt tat trong vat ran ?3. Ph:in loai vat lieu theo ly thuyet phan wing nang luong ciia v a)t ch:i t4. Tinh luc hut hucing tfim v:i luc hut ly tain mot nguyen tu biet me- 9,1. 10 ' (Kg)q, = 1,60 . 10 " (C), v = 1,26. 10m/s5. Tinh nang luong mot nguyn tir biet in,= 9, 1 . 10) q, = 1,601 10-' (C), v = 1,24. 10 m/s6. Trinh bay cach phan loai vat lieu dien ?

12

2. 1. KHAI NIEM VA TINH CHAT CUA VAT LIEU DAN DIEN2.1.1. Khai niem v vat lieu din dienVat lieu dan dien I:i vat chat ma o trang thai binh thuong co cac dien tich do. Nu dat chting vao trong mot dien trung, cac din tich st chuyn dong theo mot huong nh:i t dinh ciia trucrng vii tao thiinh dong dien. Ngucri ta gpi vatlieu co tinh dan dien.1. Vat lies co ttnh din din th: la vat chat ma su hoat dong cua cac dien

tich khfi ng lam bie'n dfi i thuc the da tao th:inh v:it lieu do. Vat

'n co tinh

n su bin

dfii hoa hoc. V:it dan co tinh dan Ion thong throng la cac dung

dich: dung dich axit, dung dich kim va cac dung dich muoi.Vat lieu dan dien co th ci th ran, long va trong mot so diu kin phiihop co the lit the khi ho a) c her.Vat lieu dan dien ci the ran gfim cac kim loai v:i hpp kim ciia chung (trong mfi t so' ttrimirinngg hhpppp ccoo tthh kkhhoonngg pphhaaii llaa kkiimm llooaaii hhooaacc hhoopp kkiimm))..V:it lieu dan dien o the long bao gom cac kim loai long va cac dung dich dien phan. Vi kim loai tliung nong chay o nhiet dfi rat cao trot thuy rig:in

og co neto nong c ay trongeuen neton

thuong chi co the diing vat lieu dan dien kim loai long I:i thiiy ngan.Cac chat w the khi ho a)c hoi co the trot nn dan dien nu chiu tic dong cua dien trucrng 16a.

Vfit lieu dan dien duoc phfin th:inh 2 loai: vat lieu co tinh dan dien tu v:i

di'mn va dong dien chay

-R

Trong do:R- Dien tro (CI)p- Dien try' sufit (Al mm/in)S- tiet dien da.y dan (mmz)1- Chiu d:ii day dan(in)2.2.2.2. Din din GDien dan G ciia mot day dan lit dat luong nghich diio cfia dien trcr R

R

(2.1 )

(2.2)

trong do:

rig : nhiet do phan tu mang dien. S : tit dien vat dan

(2.3)

vow toc do cliuyn dong trung binh cua dien tu duoi tac dung cuadien trufing E.e : dien tich cua phan tu mang din.

14

VAT LIEU DIENay vuuoc uyen cua p antu mangen vaotauoc dang tong goat ciia dinh luat om:

i = rig. e.u. E = yEvoi y = rig.e. u duoc got I:i dien dan sufit.2 2 2 4. Dten dansuat y

D;ii luong ngh|ch d:to ciia dien dan suii t y gpi I:i dien tro snort p

(2.4)

(2.5)

Voi mot v:it dan co tit dien S va do dai / khfing dfii thi p duoc xac dinh boi bieu thfrc:

= R

(2.6)

(2.7)

henhiett,' t 1 1 + ct(t - t NJ

(2.8)

n - la.s so thay

...,doi dien tro

suat theo

. . do (1 / C).

Qua nghin ct, ngufii ta thay: Cac kim loai tinh khit thi hgifing nhau v:i duoc lay bang:ct - 4. 10 (1 /C)Doi voi khoang chnh Inch nhiet do (I - t ) thi o trung binh la:

nhu

(2.9)

(2.1 0)

VAT LIEU DIEN

eangua ra n et o nong c ay

tro suat p vae so I ay oen tro

suat ct theo nhiet do ciia mfit

kim loai hay diing trong ky thu a( t dien.

Bang 2. 1 Vdc dc tinh vt Ij chu yu cua kim loai ( 20C) ding trongthuet dien

Kim loaiNhiet do nong chiiy (C)Dien tro' su:it (p) o 20C (Omni'/in)

Vang10630,0220 - 0,02400,00350 - 0,00398

Bac9610,0160 - 0,01650,00340 - 0,00429

Dong10830,0168 - 0,01820,00392 - 0,00445

Nhfim6570,0262 - 0,04000,003 50 - 0,00398

Vfinfram33800,0530 - 0,06120,00400 - 0,00520

Kim4200,0535 - 0,06300,003 50 - 0,004 19

Niken14550,0614 - 0,13800,00440 - 0,00692

Sat15350,0918 - 1,15000,00450 - 0,00657

Platin17700,0866 - 0,11600,00247 - 0,00398

Thic2320,1130 - 0,14300,00420 - 0,00465

Chi3270,2050 - 0,22200,00380 - 0,00480

Thiiy ngan-390,9520 - 0,95900,00090 - 0,00099

O g:in nhiet do 0'K (nhiet dfi tuyt dfii), dien tro suat cua kim loai tinh khit giam dot ngot, chfing the hin tinh siu dan. Ve phuong dien ly thuyt, ci nhit do 0K, kim loai co dien trot bang 0.Khi b] chay deo thi dien try suiit ciia kim loai t:ing. Nhtrng ne'u tie'n h:inh nding de cho no ke't tinh 1;ii thi dien tro su:i t co the gi:im (giiim do tac dung cfia sir bie'n dang I:inn cho kt cfiu ciia kim loai duoc chat ch v:i do su pha huy cac man oxit...).

P 'Po I kC)trong do: p : dien tro suat ban d:iu cua mau.

16

(2- 1 1)

VAT LIEU DIENo ung suat cci cuaul k: he so thay dfii cua dien tro su:it theo ap suat.dau (*) tuong Eng vfii bin dang do ko dau (-) tuong ung viii bin dang do nnSu thay dfii ctla p khi keo hoac nen la do su thay dfi i bin dfi dao dong ctla mang tinh the kim loai: khi keo thi p tang, khi nen thi p gi;im.

c. Cc yu to nh hvong khac. Tap chat phi kim co trong kim loai cling co the I:im p tang. Thuc nghiem cho thfiy dien tro sufit con chiu :inh hung cua trucing tu va anh hu'ng cua anh sang.

(2-12)B

xuc cua kim loai A va BHinh 2. 1. So do edu tae cup nhiet dinnil va o.B- mfit do dien tu trong kim loai A v:i BHieu dien the tie'p xfic cfia cac clap kim loai dao dong v;ii phan mufti den vai von, nu nhit do cua clap bang nhau, tong hi u din the trong mach kin bang khfi ng. Nhung khi mot phan tf r cfia cap co nhiet dfi la T, cfin cap kia I:i T thi trong trucrng h pp nity se" phat sinh suc nhiet dien dong(s. n.d.d)U = UU A (2-13)

Tir do ta co:

(2-14)

D ieu tnuc (2- o) cnung to s.n.a.a ia nam so cua men not ii ad

VAT LIEU DIEN

Su xuat hien hiu dien the tip xuc dong vai trfi quan trong o hien tirong;in mon dien hoa v:i dupc ung dung trong mot so khi cp do luong, da)c biet I:i frng dung de ch tao cac cap nhiet ngau diing de do nhiet dfi . B:ing the dien hoa cfia cac kim loai so voi Hydro bang 2.2Bng 2. 2 Bang tli din hoa cua cc kim loai so vo'i Hydr bang 2. 2

Kim loaiThe dien hoaKim loaiThe dien hoa

Veing1 ,500Thiec- 0, 1 00

Bac*0,081Chi- 0, 130

Dong*0,345Sat- 0,440

Hydrfi*0,000Km- 0,760

Sfrc nhiet dien dong sinh ra cfia hat kim loai khac nhan khi tie pa xucdu9c frng dung de ch tao clap nhiet ngau.Gia tri ciia suc nhiet dien dong tip xuc:

Trong do:

(2-15)

Eg suc nhit dien dong tip xtic tac ding giua2 thanh kim loai A va B luon dien tu lit do trong mot den vi ph:in khoi (1 cm) ciia

dl(2- 14)

dan:

= - (2- 15)

Gi tia cac tri so cua h so dan net dai theo nhiet do va nhiet do nong chay cua kim loai co quan he vent nhau theo ty Ie nhat dinh. Kim loai co gia tr( n, cao

nong ch;iy fi nhiet do thap, cfin lim loai co hebang 2.2

se kho nong ch:iy

Bang 2. 3

(g/cm)

C

zi 10, do '

n

Sat7,81535110,006

Niken8,91455130,0065

Coban8,7149212,50,006

Chi11,4327290,0037

Thic7,3232230,0044

Kim7,1420310.004

Cadmi8,632 1300,0042

2.2. TINH CHAT CHUNG CUA KIM LOAI VA HOP KIM2.2.1. Tarn quan trpng cua kim lo9i cua kim lo9i va h9p kimDe'n rig:iy nay, lo:ii nguoi da bi t duoc tren mot tram nguyn to hoa hoc, tat c:i cac nguye n to dupc chia I:inn hat loai : kim loai vii khfi ng kim loai trong do kim loai chie'm Hi 79 nguyn to. Kim loai chua nhie u nhiit trong vo trai d:it I:i nhom 7% sau do la sat 5%Trong ky thuat dien kim loai va hpp kim cua no la chat lieu khong the thiu, no daoc su ding phfi bien de situ seat cac thiet bi khi cudien.2.2.2. Tinh chat cua kim lo9i cua kim lo9i vii hpp kimn. Tinh r lull / howTinh chat ly hoc cua kim loai v:i hop kim la ve sangmat ngo:ii, tinh chay loang, tinh dan dai khi dot nong tinh dan nhiet, nhiet dung do dan dien, do th:inn tu ( tinh nliim tu) Ve sang cfia kim loai: Theo v sang be ngoiii cfia kim loai co the chia thiinh kim loai den va kim loai in:in. Kim loai den lit cac hpp kim ciia sat tuc I:i gang v:i thp, cfin kim loai mau la tat ca cac kim loai va hp'p kim cfin lai. Kim loai khfing trong suot, ngay ca nhung t:im kim loai duoc can dat rat mong cung khfing de clio anh sang xuyn qua no duoc, tuy vay kim loai lai co dfi phan chiu anh sang cr mat ngoai cua no, moi kim loai phan chiu anh sang theo mot mau sae anh sang ring ma ta quen goi la mau cua kim loai, thi dp dong co in:in do, thic mau trang bac, ke"m man xam v.v. . . Dfii khi tren in eat ngoiii cua thp co in:iu khac nhau nhu: vang, xanh, tim nhung mau do khfing phai l:i mau cua thp, ma la mau cua mat ngoai thep b( phtl mot l6p oxit, l'p nay tao19

VAT LIEU DIENnen o n et cat got n et o mo n et o ac n au op ox I nay co mau sac khac nhau. Chinh nhfi su bien in:in ciia be mat ngoiii ciia thpmii ta co the ph:in doan dupe nhiet do dfit nong cua thp khi nhiet luy n hay rn. Tinh nong chiiy: Kim loai co tinh ch;iy loang khi dfit nong vii dong da) c khi I:inn nguoi. Nhiet do kim ur g voi kim loai chuyn tu the da) c sang the long hoan toan gp i la dim nong ch:iy. Diem nong ch:iy co y nghia rat quan trong trong cong nghe dfi c, vi khi duc ta phai nan chay loang kim loai ra de rot vao d:iy kliufi n, trong cfing nghe diem nong chay cling co y nghia quan trong. Dim nong chay cua nhiu hpp kim lai khac diem nong chay cua timg kim loai tao nn hpp kim do. Tinh dan nhieI: I:i tinh chat truyen nhiet ciia kim loai khi bi dfi t nong hoac lam lanli, kim loai co tinh chat dan nhiet tfi t thi cang de dfi t nong nhanh va dong du, cling nhu c:ing de nguoi nhanh. Cac vfit co tinh dan nhiet km mufin dfit nong hoan toan phai m:it nhiu thcii gian va nu lam nguoi qua nhanh co the g:iy nn nfrt, vo. hoa sau khi duoc dat trong mot tu tracing. Sat v:i hau he't cac hop kim cua sat deu co tinh nhie m tu. Niken v:i Cfiban cling co tinh nhiem tu vii dupc gpi lit ch:it sat tu. Con It:iu ht cac kim loai khac khfi ng co tinh nhim tu.b. Tilt 11 c his Corr hocTinh chat hoa hpc biu thi kha n:ing cua kim loai v:i hop kim chong lai tac ding hoa hpc vii cac moi trung co hoat tinh khac nhan. Tinh ch:it hoa hpc cua kim loai v:i hpp kim biu the w hai dang: Tinh chfing an mon: L:i kha nang chfing lai su an mon cua hoi nuoc hay oxy cua klifing khi o nhiet do thuong hoac nhiet do cao. Tinh chiu axit. I:i kha nang chfing lai tac dung cua moi trung axitc. Tinh cl1rt c o lieThong thufing dam tinh cc duoc dac trirng bang giai han ben ko v:i do gian no d:ii tuong dfii khi dirt Al/I.Trn hinh 2.2 trinh bay hai dufing congcua dfiy dan I:im bang v:it dan bi keo: duing1ung voi d:iy san xuat bang cach ko nguoi, duong2 ung voi d:iy da duoc u, anh huong cua viec u dayI:inn giiim gioi han be n keo 1,5 2 Ian va tangdo gran dai tuong dfii khi dut len 1 5 20 1:in20

VAT LIEU DIENeo suc en cc gioi ud- Trong da so truong hpp co the chiu duoc tac dang tin mon (co sfrc dekhang tot dfi i viii st an mon). De gia cong: can mong th:inh la, ko th;inh soi. De ufin, de him. Co khii nang tao th:inh hop kim tfi t. La kim loai him chi chim khoang 0,0 1% trong long datDong dung trong ky thu:it dien phai duoc tinh luyen bang dien phan, tap 'n trong dong dfi mot luring rat nho thi tinh dan dien cua no cung giam di dang k.Qua nghien cuu, nguoi ta thay rang: nu trong dong co 0,5% Zn, Ni hay Al thi dien dan suat cua no (y ) giam di 25% = 40% va nu trong dong co 0,5% Ba, As, P, Si thi co the giam de'n 55%.Vi vfiy de I:inn v:it dan, thuong chi dung dong dien phan chua tren 99,9%Cu. Dien try stint v cac yu to anh hmng dn dien tra splitDong dune tiu chuan hoa trn thi trirfing quoc t ci 20'C co:- p - 1,724 1.10 (II.cm)- y = 0,58.106 ( /f I.cm)- n = 0,00393 (1/C)Cac yu to anh hung den dien try suat :inh hu'ng cua cac tap chat anh liuong cua gia cfing cc khi :inh hu'ng cua qua trinh su ly nhietNhin chung cac anh huong tren du gi:inn dien dan suat cua dong.-Pharr loft: Dong khi ke'o nguoi duoc gpi I:i dong cung: no co suc bn cao, do gian d:ii nhfi, ran v:i d:in hfi i (khi ufin). Dong du9c nung nong rfii dedong niem: no it ran horn dong cung, suc be n cc gift km, do gran khi dut rat thin v:i co dien dan su:it y cao. Dong duoc sir dung trong cfing nghiep la loai dong tinh che', no duoc phan loai trn cc so cac tap ch:it co trong dong tuc I:i muc do tinh khit, bring 2.4Bang 2.422

VAT LIEU DIEN

tyhruundund

C 1%99,9599,9099,5099,00

Trong ky thuat ngu'i ta sir dung dong dien phan CuE va Cu9 de lam dfiy dandien. Tinh cht cc hoc vii cac yii to nh hwong: anh hucing cua chat thm vao : Cac kim loai them vao : Al, Zn, Ni, st lam tang sire bn cc khi. Do do nguoi ta su dung nhin hpp kim cua dong. tinh haong cfia gia cong cc khi:+/ cr trang thai ii nhiet ( mem) do be n dut khi ko: 6 - 22kG/cm'+/ Khi ko thanh sari (nguoi ): 6,- 45kG/cm'Vi vay, de de dang khi su dung nn gia nhit vat lieu dongLuu y: Vi suc bn cc khi cua dong giam khi nhiet do 77C tir 45kG/cm' xuong 35kG/cm' sau khoang thoi gian la 80 ngay, nn nhung quy dinh ve phuwng dien ky thuat phai lam sao cho gioi han nung nong binh thuong cua day dan tran sao cho nhit do cua chung khong vupt qua 70C. Cc dcc tinh ha hoc va sy d khdng diii vi sy tin mln: ci nhiet do thucrng , dong lit va) t lieu co suc de khang tot voi su an mon ( do Dong co dien hoa ton +0,340 so voi H I:i +0,000) Dong co kha nang de khang to I vent tac dong ctla nuoc va nhfrng khi thoi tie'I xau v:i co tao th:inh lp oxit dong co tac dung bao ve. Eng dyng: Dong cung dupc dung w nh ting noi can sic bn cc giai cao, chiu o dien, cac thanh dan w tu phan phoi, cac thanh cai cac @m bie'n ap, cac laoi dao chinh cfia cite dao, cac tiep diem ciia thie't bi biro ve.- Dong niem du9c dung o nhfrng noi can do cao nhu: ruot dan dien cap, thanh gop dien ap cao, day dan dien, day quan trong cac may dien.Bng2.5 Cc tinh chit vI Iy Iboa hoc ch into eta dong diii phan

Der vi do luongChi tieu

Kg/din8,90

Simm'/in

0,0 1748

0,0 1786

1/C0,00393

W/cm. grd3,92

0,938

aiet o nong cya o cm s.grCKKccaall//kkg..grrdd C1/do ( grd) CkG/mm' kG/mm'

V0,0918

- Nhiet luong rie ng trung binh cr 25C

- DDiiieeemmm soi o 760mm ccoott tthhiiiiy nngaann22332255

- He so gian no d:ii trung binh ' 20C16,42.10 6

- Nhiet do ke't tinh lai200

- Modun dan hfii, E13000

- Sue bn dirt khi ko

- Day niem2 1

- D:iy cung45

The dien 1ioa so voi H+0,34

2. Hpp kim chia dongHop kim trong do vat lieu dong la thanh phan cc b:in, co dac dim I:i stic ben cc khi Ibn, do cling cao, co dfi dat tfi t, in:iu dep v:i co tinh chat d nong chiiy.Hpp kim cua dong co the duc thanh cac dang binh phfrc tap; nguoi ta de d:ing gia cfing trn may cfing cu v:i co the phu len b mat ciia cac kim loai khac theo phuong ph:ip ma dien. Nhfing hpp kim chinh cua dong ducic str dung trong ky thuat dien I:i: Dong thanh, dong thau, cac hpp kim dung 1:inn dien tro.Ngoiii viec dung dong tinh khit de 1:im vat dan, ngucri ta con dung cac hop kim ciia dong voi cac chat khac nhu: thic, silic, phfi tpho, b rili, crfim, mangan, cadmi..., trong do dong chiem vi tri cc b:in, con cac ch:i t khac co ham luong thap. Can cii v:to luong va th:inh ph:in cac chat chfra trong dong, ngucri ta chia hpp kim cua dong th:inh cac dang chu yu nhu sau:- Ding thanh (ding d):

Dong thanh 1:i mot hop kim ciia dong, co the m mot tang caong do cung, suc bn va de nong ch;iy.Tuy theo cac vat lieu them v:to, ngucii ta phfin biet: o Dong thanh vo'i thic.o Dong thanh vo'i thic va kem.o Dong thanh vat nhom. o Dong thanh viii Brili.

' kim loai

khac de

Dong thanh du9c dung de ch tao cac chi tit dan dien trong cac may dien

v:i khi cu dien; d gia cfing cac chi tie'I nfi i v:i gifr day dan, cac cho he thong riot dfit,o dien, 24

c vit dat

Dan tinhDon vi do lufingChi tiu

-Trpng luong riengKg/dinf )cm.10"'cm '. |

1/CW/cm. grd cKcal/kg. grd 1 /do ( grd) ckG/mm'kG/mm'%7,2- 8,9

-Dien tro suat ci nhiet dfi 20'C1,92-11, 1

-Dien dan suat0,52-0,09

- He so thay dfii dien tro su:it theo nhiet

dfi0,004

- Nhiet dan suat

0,54- 0,43

900-1 200

0, 1 0

16,6.10

630-750

9000-13000

50 - 85

3-30

Bng2 . ... Cac dc tlnh cc cua dong tli anh- Nhom dine sit dung mongIhut din

Ky hieuMuc do clingSue ben khiKo:Kg/mm(toi thiu)Dodfindaitvong dfii Khi dut % (Hi thiu)Dp clingBrinell HP(toi thieu)Trpng luongringKg/cm

30158

1408,28,27,6

Dong than:Dong thau la mot hpp kim dong viii kem, trong do kem khfi ng virot qua 46%. fi nhiet dfi cao, sfrc ben ciia dong thau dfi i vent su an mon do oxyt hoa s giam. Toc do oxyt 1ioa cua dong thau cang nho (so viii dong tinh kliiet) khiIe phan tram cua kem cang lain.Ne'u Ie phan tram ctla km lin hon 25%, thi lop bao ve cua oxyt kem tao nen tren b mat ctla vat lieu cang nhanh khi nhiet do cang lean.Con ne'u ty Ie phan tram cfia ke'm nho thi trn be mat ciia vat lieu se' tao mot l'p mau hoi den giau oxyt dong. Tinh chat nay cua dong thau voi Ie 300C

VAT LIEU DIENeao ve cac ctet c ong a su an mon cuaongcoon ac neukhfing sfi dung mot ph trong phap biro ve n;io khac.De tang sfrc d khang doi viii sir an mon dien hoa, ngucri ta thung t:innthie'c hay trang ke"m khi dong thau con nongDong thau duoc diing trong ky thuat dien de gia cong cac chi tie't dan dong nhu fi cain dien, cac phich cam, dui den, cac dau nfii den he thong tip dat, cac oc, vit. .

2.4.2. Nhiim v h pji kim cfi a nhiim1. Nhfi m (AI) Dac tinh chting:Sau dong, nlifi m la vat lieu dan dien quan trong thfr hai duoc sir dung trong ky thuat dienLit kim loai mini tr;ing bac, rat niem, r;it it de khang khi va cham v:i xiiy xat, co trpng luwng ring nho ( nhe). Chim 7,5% trong vo trai dat ( nhin nhat trong cac kim loai) Co dien dan suat va nhiet dan cao, chi sau Ag va Cu Gia cfing d d:ing khi nong v:i khi nguoi Co suc bn dfii voi su an mon do co l6p oxit r:it mong tao ra khi tipxfic vfii khong khi.- Sfrc ben cc khi tuong dfii be- Lip oxit co dien dan Ibn nn khi kho khan cho viec tip xucBng2 .... Cc hong so vat I lioa hoc chinh cua dy din nhom( 99, 5)

D;ic tinhDer vi do luongChi tieu

-Trpng luong rieng o 20'CKg/din

inc J/cm. grd cKcal/kg. grd'c/do ( grd)2,7

-Dien tro suat o nhiet ao o'c2,94

..o-Dien dan suat o 20 C0,34

- H so thay doi dien tro suat theo nhiet

do o 20C0,004

- Nhiet dim suat2,1

- Nhiet do nong chay binh thump93

- Nhiet luong rieng trung binh o 25'C0,2259

- Diem soi o 760mm cot thuy nga- He so gran no diii trung binh 20-1 00C227023,81 .1 -6

630-750

oo un annSuc ben dut khi ke'oDo dan diii rie ng khi ko duthmmkG/mm'%-50 - 85-303

hring dn dien fro siifDim try suat cua nhom o 20C la 2,94 1. 10 (Cl.cm). HQ so thay doi dien tro su:it theo nhiet dfi o = 0,004- 0,0049 ( 1/C) tiiy thuoc vao miic do tinh khit, dien dan suat y = 0,34. 10(1/fl.cm)So sanh viii dfing, nhfim co tinh chfit cc va dien it thuan lot hon. Trpng luiyngnhe (trpng luong Al nho her Cu 3,5 1:in), tinh deo cao. So vat dong, nhom km lion ve cac mat dien va cc. Voi d:iy dan co cung tit dien v:i do dai thi day bang nhom co dien tro Ibn hon dong khoang 0,029 5/0,0 175 - 1,68 Ian. Do do nu co hat d:iy dan bring nhfim va dong co dien tro nhu nhau thi d:iy nhfim phiii co tie't dien 16a hon 1 ,669 I:in so vat day dong (hay ducrng kinhcua day nhom Ibn hon do vfii day dong la= 1,3 Ian).Vi way, ne'u bi r:ing buoc boi kich thuoc thi khong the thay dong bang nhfim duoc.Cac yu to anlt huong den dien tro su:it anh huong cua cac tap chat tinh huong cfia gia cong cc khi :inh hu'ng ciia qua trinh sir ly nhietNhin chung cac anlt huong trn du lam tang dien tro suat v:i thay dfii he soecianhm.

nhit do ci 20C

-Nhom tinh0,00050,00232,634,33.1 0"

khit0,340,12,7674,10. 10

- Al 99,5 %0,560,322,784,13.10 6

- AL 99,0%0,960,412,8354,10. 10

- Al 98,5 %

27

-Pharr loft:Nhfi m ding trong cong nghi p dupc phan loai trn cci st Ie phan tram cua kim loai tinh khit va tap chat. Nhfim duoc sir dung lam day dan dien trong ky thu:it dien thucing phai dam bao tinh khit, tfii thiu 99,5% Al, cac tap chfit khac nhu sat, silic Hi da I:i 0,45%, dong v:i km Hi da la 0,05%.fi nhiet dfi thu'ng, khi de trong khfing khi, nhfim s duoc boc mot lp mong, chac nit oxit, l6p n:iy co dien try' l'n va no ngan ngtra viec oxyt hoa tip tpc, do vay no dam bao la mot lip bao v tot doi vfii su an mon, ngay ca i trucin khi h:iu am unit v:i hay thay dfii. Song trong trung

Nhfim du9c su ding trong cfing nghiep duoc phan loai tre n cc st ty Ie % ciia kim loai tinh khit va tap ch:it, bring 2.5Bang 2. 6

Ky hieuAB 1AB2A-00A-0A-1A-2A-3

Nhfim%99,9099,8599,7099,6099,5099,0098,00

28

VAT LIEU DIENeo tieu c uan nuoc ngoai I i n om uoc su ung trong y t uat e am aydan dien phiii co do tinh khie't > 99,5%- Tinh chit cc hoc v cc yu ID nh hug+ :inh hucrng ciia nhiing chat them veto: cac kim loai the m veto : Fe, Zn,Si, Mg. . ... se him thing sfrc ben cc khi+ anh huong cua gia cfing cc khi: khi gia cfing cc khi tinh chat cc cfia nhfim phu thuoc v:to tap chat: Nhfim tinh khie't thi 6, = 6kG/cm' khi co tap chat 0,5% thi 6, = 1kG/cm'- Gc dcc tinh ha hoc v sy d khng di v 'i sy in min:Nhom tic ding manh voi oxi, trong khong khi ngay w nhiet do thung nhfim duoc boc mot lip mong, chac nich oxit. Lop nay co dien tro cao va no nagun chin viec oxi hoa tie'p tic. Do way no diim biro se co mot top bao ve tot doi voi su ;in mon ngay cii trong dien kien moi trucrng khi h jaw rim not

dongSong trong trirong hop co ton tar trong khi quyen cac loai khi nhu CO, , NH, , 50 . . . . Va do :im not ton co the phat sinh an mon dien hoa, vi nlifi m co the dien hoa gan nliu it nhat so voi H (-1,34) va su tip xuc voi cac kim loai khac co dien hoa Ibn hon thi st nguy hai doi vfii nhom, vi du nhu Cu ( +0,34),

trong trirfing hpp nay st phat sinh dong dien tu nhom

cho nhom

Trong khfi ng khi co hoi nu'c, nn co cac ion H, OH , HCO , nen dong v:i nhom va dung dich dien tao th:inh 1 pin cuc duong I:i Cu cuc finn I:i Al, Cuc Al bi mon d:in vi Al chay vao dung dich do luc hoa hoc cua cac phan tu nuo'c. Cac dien tu tliua trong nlifim se chay sang cuc dong va khu dien th cua cac ion H, trong dung dich cac ion Al kt hpp OH tao thanh AI(OH) ,2A1 6e - 2A1",4H*6e = 3H ,2A16OH - 2 AI(OH)Vi th nhfi m bi an non kha manh- Eng dyng:Trong ky thuat dien, nhfi m duo'c su dung phfi bin de ch tao:o D:iy dan dien di tre n khong de truyen tart dien n;ing. o Ruot cap dien.o Cac thanh ghp v:i chi tit cho trang thit bi dien. o Dfiy quan trong cac may dien.o Cac la nhom d laindien, Hi dan tu may bin ap, cac roto cua dong cc dien,29

pp inn can ii cm:

VAT LIEU DIEN

Nhfim co nhiu hpp kim dting de duc va d keo day dan dien. Cac hpp kim chinh cua nhfi m dting de duc co the I:i nhfrng loai sau:Al-Zn-Cu, Al-Cu, Al-Cu-Ni, Al-Si, Al-Si-Cu, Al-Si-Mg, Al-Mg, Al-Mg-Mn.Mot hpp kim dupc dung pho bie'n de che tao d:iy dan I:i hpp kim "aldrey". Chung I:i hop kim ctla nhfim v'i (0,30,5)%Mg, (0,40,7)% Si, (0,2=0,3)% Fe. To hop lam cho hpp kim co tinh chat cci khi tot. Day dan bang hop kim loai "aldrey nhan ducic thong qua . c toi hpp kim (nung nong dn 500600C), ko no th;inh soi fi kich thuoc mong muon v:i 1:inn gi:i hoa nh;in tao bang nung nong 150200C. Sfrc be n cfia d:iy dan "aldrey" 1 grip kho:ing 2 lan so vat d:iy dan Al tinh khit. Vi vay, khi diing duty d:in "aldrey" co the tang khoang cach giiia cac cot cfia duong d:iy trn khfing, giam chi phi x:iy dung dang k.2.4.3. Chi va hpp kim cfia chiChi ducic tinh luyen tir cac mo co trong tu nhin nhu: Galen (PbS), Xezurit (PbCO ), Anglezit (PbSO,)...Co the thu duoc clii o muc do tinh kliit (9299,94%).Chi 1:i kim loai co mau tro sang, riit mm, co th non cong, dat mong de dang ho a)c cat bang dao cat cong nghi p, nhiet do nong chay th:ip.Chi co dien try' sufit cao p = 0,2Umm'/in v:i nhiet dan suat nhfi. No I:iv:it lieu bao ve tfi t nhat dfii vo'i su xuyn thung cua tia X (tia Rontgen).Mot lop chi day lmm ci 200=300kV co tae dung bao v nhu mot lip thp day 1 1 ,5mm hay mfit 1crp gach co chie u duty 1 I Omm.Chi v:i hop kim cua no duoc dung de I:inn lip vo bao ve o cap dien nhamchfing lai am not.Chi con dupc diing de ch tao cac ban cfc cua acquy, ding de lam day chay bao ve cac during day dan dien v:i cac thit bi dien.Chi dupc tinh luyen tu cac mo co trong tu nhin nhu: Galen (PbS), Xezurit (PbCO ), Anglezit (PbSO,)...Co the thu duoc clii o muc do tinh kliit (92-99,94%).Chi 1:i kim loai co mau tro sang, riit mm, co th non cong, dat mong de dang ho a)c cat bang dao cat cong nghi p, nhiet do nong chay th:ip.

VAT LIEU DIENcoen tro suat cao pmm m va n etan suat n oo a vat lieu bao ve tfit nhiit doi vat su xuyn thiing ciia tia X (tia Rontgen).Mot 16p chi d:iy l mm fi 200300kV co tac ding bao ve nhu mot lip thep d:iy 11,5mm hay mot lop gach co chiu day 110mm.Chi v:i hop kim ctla no duoc dung de lam lop vo bao ve ci cap dien nham chfing lai am not.Chi cfin duo'c dung de c1i tao cac ban cuc cua acquy, dung de lam day

Dgc tinhDoc v| do lungChi tieu

-Trong luong ring o 20'CKg/dmmcm.10 'cm '.10.l/'cJ/cm. grd cKcal/kg. grd/do ( grd) kG/ kG/mm v1 1.34

-Dien tro suat o nhiet dfi 20'C20,8

-Dien dan su:it o 20C0,048

- He so thay dfii dien tro su:it theo nhiet

dp fi 20C0,0042 8

- Nhiet dim suat0,35

- Nhiet do nong chiiy binh thucrng327,3

- Nhiet luong rieng trung binh o 25'C0,00309

- Dim soi ' 760mm cfi t thu n an1740

- He so gian no d:ii trung binh 20-100C29,3. 10

- Modun dan hfii, E1700

- Sue ben dirt khi k1,5

- The' dien hoa so voi H- 0,13

2.4.4. S5t vfl hpp kim ciia s5tTrong vo qua dat, sat la kim loai co nhiu thu hai, sau Al (khoang 5 o).Sat duoc san xuat tuong dfi i de dang nn gia thanh lia so voi cac kim loai khac. Trn cc s'Ie Cacbon chua trong sat in:i nguoi ta phan th:inh:- Garg. l:i sat chua ty Ie (1,7 4,5)% C Thp. la sat chua ty Ie (0,5 = 1,7)% C SSI ren. la sat chua ty Ie duoi 0,5% C

tat I netre

VAT LIEU DIENy I uat t uc te rat Iuoc su

Chi tieu

- He so thay doi dien trai suat theo nhiet

.l /'c J/cm. grd cKcal/kg. grdc/do ( grd)/G/ G/pv7,86

10

0,10

dp o 0-100C0,00657

- Nhiet dan suat0,75

- Nhiet do nong chay binh thump535

- Nhiet luong rieng trung binh o 20-100C

- Diem soi o 760mm cot thuy nga- He so gian no d:ii trung binh 20-100C27402 3. 10 6

- Do dan dai ring khi dirt50

- Modun dan hoi, E2 1070

- Sfrc ben dfrt khi ke'O22

- The dien hoa so voi H0,44

Thp du9c dung him v a) t dan thtrong dung loai thp co h:inn luongCacbon (0, 1 0 0, 19)%C, co gift han chiu ko (70 75)kg/mm', do gian khi dut (5 : 8)%, dien tro suat lain lion dong (6 = 7) 1:in.Nhuoc diem cfia thp la de bi an mon thong qua hien tuong ri ngay o nhiet dfi binh thucing va dac biet la ri r:it nhanh o nhiet do cao va o moi trirong him unit. De khac phuc hien tuong nay, be mat tip xuc cua sat thuong duoc phu mot lip vat lieu on dinh hon nhu Cadmi, Zn,....M:ic dii vay, no cling co mot so uu diem nfii troi so viii cac kim loai khac nn duoc su dung phfi bie'n 1;im va) t dan:O Thp co siic bn cc khi Ion gap 2 2,5 1:in so voi dong va do do d:iy dan thep co the dung ci nhiing khoang cfi I l'n, nhiing tuye'n vuot song rong...(co the sir dung vfii khoang cot tu 1500 = 1900m).U Su phong phu ciia thp trong qua) ng thien nhin vii gia th;inh ha tao cho day dan hoac thanh dan dien bang thp co gia thap hon nhin so voi bang dong hoac nhom.

32

VAT LIEU DIENo ve' nong ay an truyen ta en nang nguo ta su ung ay dan bang the'p nhieu ski ho a)c ben thanh chao hoac su dang chao thp-nhfim, vcri thp ducts trang km du9c da)t cr gi tia.De dung the'p 1;im thanh dan thuong I:i thp cacbon dat mong khi nong (C = 0,74%, Mn = 0,7 1%, S = 0,002%, Si - 0,25%, P = 0,03%) co dien trosuiit p = 0, 135 D mm'/in.Thep hay duoc dung lam day dan, thanh dan d b:to ve qua dien ap (chfing st) va cac trang thit bi baoNgoai ra, thp cfin duoc diing de ch tao cac dien tro phat nong viii nhietdp thich frng 300=500' C..2.4.5. Kem2.4.5. 1. San xuat v:i che' taoKe'm duoc thay trong tu nhie n dust dang hpp chat ZnS , cac bonnat ke"m (ZnCO ), Silicat( Zn SiO4), oxyt ZnO v.v.Cac phuong phap lay kem tu hpp chat I:i Phuong phap lay km bang cach lam khfi thong qua su s:in loc bang lucii o nhit do 850- 900'C va lam giam oxyt nhat su giup dfi cua cacbon w I 300- 1500C trong phonh dong kin de ngan can oxyt hoa. San do kCm thfi ducic tinh che' theo phuong phap khfi trong lo co ngon lfra ho a) c theo phuong phap dien phan dung dich sulfat ZnSO . Chung ta se thu duoc kem voi dfi tinh khie't 99.9% Phuong phap 1:iy km thong qua dien phan tit mo calci va co sunfat chiu dien phan nhu ZnSO, trong binh bang go boc chi.Theo tieu chuan mot so nufic kCm du9c pham loai tuy theo dac tinh cua kCm, mf rc do tap chat vv. ..v:i co nhiing loai sau: loai pham chat L, loai pham chfit O, vii loai pham ch:it Z su chiu th;inh cfia nhflng loai ke"m cac th;inh ph:im trn duoc gioi thieu bang 2. 7.

PhamchatKyhi uZn%(min)H:inn luong tap chat %(max)

PbCdFeAsSbCuSriTap chatkhac

LO ZZnLZnO ZnZ98,698,697,51,501,252,000,10,20,20,040,040,100,0050,0050,0100,0150,0150,0150,0050,050,050,0020,0020,05Con laiCfin lai Cfin lai

Giua cac tap ch:it trn, thi Pb tao cho ke"m de dat dat, con sat Fe lain cho ke"m

de

ke'm luyen kim dupc duc thiinh cac khoi co trpng luoiig 20 *

2kg. Kem duoc dung trong ky thuat dien cho cac p1i:in tu galvanic, phai co ti Ie ph;in tram tfii da 1 %Pb vii 0,02%Fe2.4.5.2. Hang so vat ly vii hoa Hang so vat ly cho trong bang 2.8.

Dac tinhDon vi do lufingChi tieu

-Trpng luong rieng o 20 CKg/dinflcm.10"I 'cm '. |

J 4cJ/cm. grdcKcal/kg. grd|/do ( grd)cG/' kG/mm%v7, 14

-Dien tro suat o nhiet dfi 20'C5,92

-Dien dan suat o 20'C0,17

- He so thay dfii dien tro su:it theo nhiet

dfi o 20C0,00419

- Nhiet daft SUat fi 20'C1, 128

- Nhiet do nong chiiy binh thucrng419,5

- Nhiet luong rie ng trung binh cr 25C0,0946

- Dim soi ' 760mm cfi t thu n an907

- He so gian no d:ii trung binh 20-100' C39,5.10

- Nhiet do xu ly nhiet ( u)630-750

- Modun dan hoi, E13000

- Sue ben dirt khi k1 1,2 13,3

- Do dan dai ring khi ko dut35-45

- The' dien hoa so voi H- 0,76

2.4.5.2. D(ac tinhKem I:i kim loai co m:iu tro xam hot rig:i mau trang. No co tinh chie'u sang va sau mot thoi gian no tro nn mau mci duc do vi tac dung ciia khfing khi, khfi ng khi dtao cho kCm mot lip oxit bao v , sau do lip nay chuyn thanh kim cacbonnat, chinh top nay bao ve cho kem khfi ng bi an mon. Kem co c:iu triic tinh the, o nhiet do binh thuong it chiu dat mong, song nu nung nong w 100 - 150'C thi tinh dat mong tang 1en, vii do vay nguoi ta co the dat mong, ren v:i ko th:Huh so'i. o' nhiet dfi 200 250C thi kem tro nn don vi v:iy co the dap vo th:inh bot. o trang thai long, no chay de dang va co the rtot day vao kliufin de rang. No d bi tac dung ctla axit va chat kiem voi nhfrng chat do no tao34

- Dong mem8,9562645

1,60,47

- Nhfi in2,736820

- Magie 99,7%1,72 1,7201 00,44

- K:in 99,9%7, 116,220301,832,67

- Kem vfii 0,13 % Fe7,115,5- 15,81840-431,892,86

Kem vfii 6,4%A1 va6,81 6,824,647,91,822.54

0,21 % Cu

Tit bang 2. . . chung ta co nhan xt 1:i: D:iy dan bang km, o nhiet do binh thuong, tinh chat cc khi co the so sanh voi tinh chat cc khi ciia dong mem. Khi tang nhiet do, sire bn khi ko cua kem st giam rat nhin (cr 100" giam de'n 60- 70% trong khi do, sfrc be n khi kep cfia dong fi cang nhiet do se chi gi:inn den 9%, cfin nhfi m chi giiim 1 0%2.4.5.3. ring dpngNhiir g frng ding chinh ciia kem trong ky thuat dien lit . D:iy dan bang kem klii them thanh phan dong liay nhfim v:to, dfii luc duoc dung thay the cho day dan bang dong hay bang nhom.Day dan ZnAl- I ( bang 2...) cho ph:inn chat tot vi no khong tao nn duong nlit ne. Tuong tu nh tr way, d:iy dan vat 0, 13%Fe co the keo thiinh soi nho khi nguoi inn khong bi nf rt ne.- Cac thanh gop bang kem cho phep ap suat 20-50kG/cm Cac dien cuc dung cho cac phan tir galvani Cac la kem dung lam cau clii nong chay, san su:it tlieo phuong phap dienph;in( 99,95%)

Sfrc ben dirtkG/mmDo dan d:ii %Dien dan suatin/C1mm'

Zn 99,99Zn 99,901423601516,516,0

Zn Al- 1 Zn Al-4 Zn Al- 1020223030685016,716,918,6

2.4.6. Mot sfi kim lo9i va h pi kim khac2.4.5. 1. Wofram (W)Wofram (Tungsten) tim thay trong tu nhien duoi dang mo: Woframit (FeOMnO)WO , quang selit (CaOWO ), thong qua cac phan ung hoa hpc khac nhau, cac quang n:iy chuyn thanh Trioxyt Wofram (WO ) rfii dieu ch tu day duoc Wofram (W) thong qua dien phan o nhiet dfi cao 1050 l300'C.Wofram la mot kim loai co suc be n dut vii do cung rat cao, nhiet do nong ch;iy cao nhat trong so t:it cii cac kim loai dupc su ding trong ky thu a( t dien, dup'c che' tao thanh soi toc trong cac bong den dien set dfi t, ch tao cac dien tree phat nong cho cac lo dien,...Tuy nhin, de can tree su oxyt hoa day toc v:i sir bay hoi cua no, cac bong de n nung sang duoc thuc hien trong chan khfing hay voi moi truong khi tro (argon, nito), klii do co the I:inn viec o' 2300C.Wofram tinh khie't (99,5 99,8%) con daoc dung de che' tao cac tie'p diem dien co dong dien nlio. Dfii vo'i tip diem dien o cfing su:it lain (dong dien lin), nguoi ta dung hop kim cua Wofram voi bac hay Wofram voi dong

Chi tiu

- HQ so gian no dai trung binh 20-100' C

|/do ( grd)19,35,550, 18

0,004681,9933800,033850004,5.10

36

oo un ann Suc ben dut khi ke'o The' dien hoa so voi HhmmkG/mm' V-350- 0,58

2.4.5.2. Niken tNi)Niken con duoc goi I:i ken, ton tai duoi dang mo trong thin nhin:o Sulfua da kim loai: quang Milerit (NiS), Penlandit ((FeNi) Sg). o Silicat. Canarit (2NiO SiO .H;O), Gac-ni-erit (N iMgSiO )o Sulfua va Asenua - Nikelen: NiAs, NiAs .Qua hiing loat cac phan King nguoi ta co the che tao duoc Niken voi dotinh khit 99,9%.Niken la kim loai m:iu trang-xam tro, no khfi ng bi oxyt hoa trong khfing khi vii trong n troc o dieu kien binh thtrong (chi bi oxyt hoa fi nhiet do trn 500'C) la kim loai bn, de dat mong va vufit gian duoc ca khi nguoi va khi

che' tao cac tip diem dien l:im viec trong

i tru'nCacbua Hydro dfii voi

dong din nho va din ap Ibn (doi vfii cong suat Um, tip dim dung hop kim Ni-Ag) ; ch tao cac dien trcr phat nong, dn 900C ; dung d ma bao v cho nhflng chi tie't bang suit thep thong qua phuori g phap dien ph:in, diing de ch

Chi tiu

- He so thay dfii dien tro su:it theo nhiet

W/cm. grd8,9

8,69 u nhiet niem

0,0044- 0,0069

dp fi 20C

- Nhiet dan suat0,593

- Nhiet do nong chiiy binh thucrngc1453

- Nhiet luong rie ng trung binh cr 25'CKcal/kg. grd0, 1086

- Dim soi ' 760mm cfi t thuy ngaann'C3000

Modun dim hfi i, E Suc ben dut khi keo

The' dien hoa so voi HkG/mm' kG/mm'

2050040 fi nhiet mem 80 cung- 0,25

2.4.5.3. Bac (Ag)Bac duoc diu ch tu cac mo trong tu nhin: Acgentit (Ag S), Pira- Acgirit (Ag Sb S ), Kera-Acgerit [(AgC1)Ag Sb]... ngo:ii ra cfin tim th:iy Ag trong nuoc bien (0,001 mg/ Hit).Thong qua dien ph:in tinh che' co the thu duoc bac tinh khiet (99,80 =99,999)%.Bac lit kim loai co dien trcr suiit nho p - 0,01 6 hmm'/in nen dan dien tot nhiit trong tat ca cac kim loai. No co man tr:ing va chiu sang, chiu sang nay khfi ng bi mat di trong moi trirong khfi ng khi. O nhiet do binh thufing, tham chi cii ci nhiet dfi cao bac van khfing bi oxyt hoa do vfiy Ag duiyc lit v:to nhom kim loai guy.Trong thufit dien, bac duoc str dungU L:inn day'n, dfiy quan, tie'p diem trong ky thuat thu thanh, vfi tuye'n, lam day chay bao ve.U Hpp kim vat Mangan hay Niken du9c dting trim d:iy dan trong cac may do.O De ma cho cac kim loai khac, ngan oxyt lioa, de trang guong, trang

Chi tieu

- H so thay doi dien tro suat theo nhiet

1/'C10,5

1,6

0,0625

dp fi 20C0,0036-0,0041

- Nhiet dim suatW/cm. grd4,58

- Nhiet do nong chay binh thuong'C960,8

- Nhiet luong rieng trung binh o 25'CKcal/kg. grd0,0575

VAT LIEU DIEN

iem soi wmm cot t uy ngan1 /do ( grd)19,68.10 6

- He so gran no diii trung binh 20-1 00C

- Modun dan hfii, EkG/mm'8200

- Suc ben dirt khi keokG/mm

16 u nhiet mem

29 keo

- The' dien hoa so voi H0,808

2.4.5.4. 4. Vang (An)Vang ducic tim thay trong thin nhin dufii dang hat, la, bpi bot...bang cach dai theo phuong phap dac biet rfii chung cat, tinh luyen thong qua dien ph;in hoac thong qua ke't tua chpn l pc co the thu dupc v:ing tinh khie't (99,88 99,998%).Vang la kim loai co mau vang dac trung, sang r;rc. M:in sang nay khong bi mfit di trong khfi ng khi hay trong axit, khfing bi oxyt hoa ci nhiet do cao.Trong ky thuat dien, vang duoc su dung:De firm cac tie'p diem dien, thtrong duoi dang hpp kim: 70% Au *24%Ag + 6% Pt.De ma cac v:it lieu khac chfing an mon dien.Lam day dan (hop kim Au + 20% Cr), cac dien tro trong dien k, vi

-Dien dan suat20

i/cJ/cm. grd 'cKcal/kg. grdc|/d ( had)G/' kG/mm'19,29

2,20

0,045

- H so thay doi dien tro suat theo nhiet

do fi 20C0,00365

- Nhiet dan su:it3,12

- Nhiet do nong chay binh thump1063

- Nhiet luong ring trung binh ' 25'C0,031

- Diem soi o 760mm cot thuy nga2700

- He so gran no diii trung binh 20-1 00'C14,3.10

- Modun dan hfii, E7900

- Suc ben dirt khi ke14

2.4.5.5. Thic (Sn)Thie'c I:i kim loat co anh sang bac, suc be n dfii vat tinh huiig cfia moi truong, la kim loai rat mm (sau chi), de dat mong v:i de ufi n deo.Thie'c duoc dting trong ky thuat dien d che' tao dong thanh, l:inn l'p vfi i triron , de

Chi tieu

HQ so gian no dai trung binh 20-100C Modun dan hfii, E Sue ben dirt khi k Th dien hoa so voi H

|/do ( grd)kG/' kG/mm' v7,31 1,40,087

0,00440,16231,90,0548230027,03.T Q-611502,75- 0,10

2.4. 5. 7. Thuy ngan (Hg)Thuy ngan la kim loai duy nhat o th long va co th bay hwi trong diukien thuong.Thiiy ng;in tinh khie't co miiu trang bac, chie'u sang. O nhiet do 38,87C, no dong ran lai, tao thanh mot khfii tinh the de dat mong va vufit gian duoc. Thiiy ngan co suc be n dfii voi su tac dong ciia khong khi kho. Khi nung nong trong khong khi no b| oxyt hoa (cr nhiet do 350'C, no bi oxyt hoa rat d dang). Thuy ngan duoc sir dung trong cac de n chiu sang, den chinh luu, den chieu da)c biet ding trong y t, may chie'u, may in,... Ngoiii ra con dupc dung1:inn cac tie'p die m trong ky thu a) t do, trong Rule vii cac khi cp dien.40

Dac tinhDon v| do lungChi tieu

-Trpng luong rieng o 20 CKg/dinflcm. 10 fl 'cm '. 10

J 4c/cm. grdcKcal/kg. grd|/do ( grd)QG/'kG'

1 3,546

-Dien tro suat o nhiet dfi 20'C95,8

-Dien dan suat o 20'C0,010438

- He so thay dfii dien tro su:it theo nhiet0,90. 10

dfi o 20C

- Nhiet daft SUaL0, 103

- Nhiet do nong chiiy binh thucrng-38,87

- Nhiet luong rie ng trung binh cr 25C0,0332

- Dim soi ' 760mm cfi t thu n an356,95

- He so gian no d:ii trung binh 20-100' C18,2. 10"

- Modun dan hoi, E8200

- Suc bn dfrt khi ko16 II nhiet mem

29 ko

- The' dien hoa so voi H0,86

2.5.1. Hpp kim Manganin (86%Cu, 2%Ni, 12%Mn)Hpp kim Manganin lit hpp kim chs yeu dung trong thie't b| nung v:i dien try' mau (dien tree chinh xac). S' di dup'c dung l:im dien tree mau I:i b'i no khfing him sai lech ke't quit do luong o nhiing dong dien khac nhau ciing nhu fi nhfing nhiet do moi trtrong xung quanh khac nhan.

2.5.2. Hpp kim Constantan (O Cu, 40 O Ni)41

VAT LIEU DIENonstantanean vanrat ce soenoen tro suat o I eo nhiet do r:it nlio (Constantan voi nghia cua no la hang so), o co tri so am.Constantan duoc dung lam bin tro v:i phan tu nung nong, Constantan khfi ng daoc ding o nhiet do tren 450C vi luc do no se' bi oxyt hoa.Constantan ghp vo'i dong hay sat co sfrc nhiet dien dong 1o'n. Do la nhuoc diem khi ding dien trcr bang Constantan trong cac so do do. Do co su chnh lech nhiet dfi o cho tip xuc nn co suc nhiet dien dong xu:it hien, do la ngufi n sai so. Dac biet trong cac can do chi khong va so do phan dien ap.

Constantan duo'c dung nhiu lam cap nhiet

'u de

do nhiet dfi den

2.5.3. H pp kim Nikenin [(25-35)% Ni, (23)%Mn, 67%Cu]

Hop kim Nikenin re tien hon Constantan, de gia

n , co dien

nho hon v:i he so bie'n dfii ciia dien tro suat dfi i voi nhiet do l'n hon Constantan.Ngu'i ta thuong dung hpp kim Nikenin lam bin tro khoi dong v:i diuchinh.

2.5.5. Hpp kim C rfim - NhfimHp'p kim Crom - Nhfim la hpp kim rat r duoc dting d che' tao cac thit bi nung ton va lo dien ton dung trong cfing nghip.

Bang 2.6. Tong hpp hanh phan va cac tinh chat cc ban cua mot so hpp kim co dien try cao hay ding trong ky thu a( t dien.

42

Thanh phan % co trong hppTinh chat cc b:inNrCrASucnhietdien dpngin)/C)voiGioi hannhit do lain viec1220 42010-151-2100-200400,430,52-50,5400-50062=Nikenin7325350,420250Niken557151,5823n1 ,01 ,2lai304nlail ,2 1,50,000141200

Ten hpp

kimCM

iin

Mangani6

Constant6

an0

43

VAT LIEU DIENat ieu ung am ien tro c in xacung o n ung ung cu o nong dien v:i dien tro chuan. Loat n;iy co cac yeu chiu lit da) c tinh khong du9c thay doi theo thcri gian d no khong tao ra sai ' tron cac php do V:it lieu dung 1:inn bo bie'n try khai dong, loat nity co yeu cite: Ph;ii co sfrc ben trong qua trinh nung nong vii suc be n dfii vat su min mon. Vfit lieu duoc sir dung ' nhiing khi cu dien suot nong v:i dun nong, yeu cau phai co sfrc bn doi viii thai gian ko dai khi nhiet do cao.w j. Nliiing kim loai tinh khit it duoc diing lam bin tro vi: Dien tro su:it nho hon hop kim ciia chung, ci cfia h pp kim tinh khie't >> e cfia hpp kim, bi an mon w nhiet do cao.2.6.2. Hpp kim diing firm dien try2.6.2. 1 . Hpp kim dung 1:inn dien tro chinh xac va diing lam bfi bin tro Hpp kim loai Mangan, th:inh phan: 86% Cu, 2% Ni, 1 2% Mn Dac diem: co sfrc nhiet dien dong nhoKing ding: Ch tao cac dien tro chinh xac vi no khong 1;im sai lech ke't qua do lufing fi nhfrng nhiet do khac nhau va nhfmg dong dien khac nhau. Hpp kim loai Constantan, thiinh ph;in: 60% Cu, 40% Ni, D:ie diem: HQ so bin doi theo dien try suat rat nho ting dung: Dung I:inn bin tro v:i phan tu nung nong2.6.2.2. Hpp kim diing lam bin trfr sirfri nong va nung nong Hpp kim trn cci st Niken va CromTh;inh ph;in hpp kim dupc tao th;inh theo cach hoa tan ran Niken vii

Crom

Dac diem: co stic bn tfit ci nhiet do cao, dien tro suat lori v:i he so bie'n

dfi i theo dien tro su:it nho Ngo:ii ra cfin co cac loai hpp kimHop kim trn cci so Ni , Fe, Crom+ Hpp kim tren cc so Fe, Crom, AlDay lam dien trcr trn cc so Cacbua Silic , Fe, Crom2.7. VAT LIEU DQG LAM TIEP DIEM VA CO GOP2.7.1. Yu cau diii viii vat lieu lam tip dim Co sue bn co khi va do ran tot ( tuoi thp cao)

44

VAT LIEU DIEN

su bin dang cua vat lieu cang de dang va luondiem tip xuc cang ton,

- Dong va hpp kim cua no co phs chat cfrngn co the

46

thu a) t dupc che' tao bring nhieu cach de tao th:inh mot khfii lien he cheat cfiahat kim loat.2.8.2. Dliy din va thanh gp bang lining kim- Thp - Dong ' f =5000Hz tro o dong dien mot chiu dfii viii d:iy dan dong co during kinh 5mm la:

= 3,9

'n co theh :inh hucing de'n dien try' ' dong dien xoay chieu. Dieu n:iy s I:i bin phap tot de lam t:ing sire bn cc khi cua day dan, va lip dong ci bn ngoai cling st lit lip biro ve rat tfit dfi i vat su min mon.Do vay, nguoi ta da thuc hien day dan bang vat lieu luong kim thep- dong dfi i voi duong day thong tin lin lac co dung kinh l- 4mm. Day dan bang vfit

lieu luring kim loai trong mot' tracing hop

dung l:inn day dan dien trong

mach nlii thu o tan so 50Hz. Va duoc c1i tao thanh cac thanh gop trong cac trong cac trang thit bi dung de nfii.2.8.3. Dfiy dan lirfiiig kim - Dong- Nhii m

47

VAT LIEU DIENo pp nong in ong n om uoc tao ac et no ang cac tarn co mot meat hay c:i hat meat va ding trong cac c:in trfic phan chie'u, 1o sufii dien hoac cac chi tit dung de noi vv.Cac tain luong kim - dong nhfim duoc dung I:inn cac con riot d:iy dan dien , con nfii day dong vii day nhom. Do thii(an lit la co the de rang h:in dinh bang hop kim dinh chat dna tren vat lieu cc b:in I:i thie'c , vfit lieu lung kim nay co the dung de ch @o cac chi tit trong thit b| thu va phat thanh nhu lam cuon d:iy angten bo cam bin vv.

48

CHUONG 3VAT LIEU CACH D@N

3.1.2.2. Phan lo9i theo thanh phan ha hpcTheo thanh phan hoa hoc, nguo'i ta ph:in ra: v:it lieu cach dien hfiu cc vav:it lieu cach dien vfi cc.1. Vat lies cch dien him cc: chia th:inh hat nhom: nhom co ngufin gfic trongthien nhien v:i nhom nhan tao.Nhom co ngufin 'c tron tliin nhin sir dung cac lipp ch:it cc ban co trong thien nhien, hoac gin nguyn th:inh phan hoa hoc nhu: cao su, lua, phip, xenluloit,...49

qom n an tao t nonguoc

a n ua n an tao gom co n ua

pheno1, nhua amino, nhua polyeste, nhua epoxy, xilicon, polyetylen, vinyl, polyamit,

cfiatkfii, cac chatlng Lfing chay, cac in, su, thtly tinh, mica, amiang.

3.1.2.3. Pbfin lo9i theo tinb chiu nbietPhan loai theo tinh chiu nhiet la sir phan loai cc ban, phfi bin vat lieu cach dien dung trong ky thu a( t dien. Khi lua chpn vat lieu cach dien, dau tin can biet vat lieu co tinh chiu nhiet theo cap n:to. Nguoi ta da phfin vat lieu theo tinh chiu nhiet nhu bang 3.2.Bang 3.2

Capcach dienNhiet dficho php (C)Cac vat lieu cach dien chu ye'u

Y90Gray, vai set, lua, phip, cao su, gfi va cac vat lieutuong tu khong tain nhua, cac loai nhua polyetylen, PVC, polistinol, anil in, abomit

A105Gray, vat set, lua trong dfiu, nhua polyeste, cao sunhan tao, cac loat son cach dien co dan trim kho

E

120Nhua trang Polyvinylphocman, poliamit, epoxi. Giayp hoac vai p co nhua phendfocmandehit (goi chung lit Bakelit gray). Nhua Melaminfocmandehit co ch:it dong xenlulo. Vai co tarn tham Polyamit. Nhua Polyamit. Nhua Phnol-Phurphurol co don xenlulo.

B

Nhua Polyeste, amiang, mica, thuy tinh co chat don.San cach dien co dau lam kho ding w cac bo phan tip xuc vat khong khi. Son cach dien alkit, son cach dien tu nhua phenol. Nhua PhnolPliurol co chat don khoang, nhua epoxi, soi thliy tinh, nhua Melaminfocmandehit.

F155Sci amiang, soi thuy tinh co ch:it kt dinh

H180Xilicon, soi thuy tinh, mica co chat kt dinh

C> 180Micakhfi ngcochfitktdinh,thuytinh,su,

VAT LIEU DIEN

mo ya oty

ymono orto y n

3.6. TINH CHAT CHUNG CUA VAT LIEU CACH DIENKhi l tia chon, su dung vat lieu cach dien can ph:ii chu y den khfing nhfrng cac phfim chat cach dien cua no mfi cfin phai xem xt tinh on dinh cua nhfrng phfim chat nfiy duoi cac tac ding cc hpc, hoa ly hoc, tac ding ciia moi truong xung quanh ,...gpi chong Ta cac dien kin van h:inh tac dong den vat liu cfich din. Duoi tac dong cua diu kin van hfinh, tinh chat cua vat lieu cach dien bi giam sut lin tuc, nguoi ta goi do I:i sp /fio hoa vat lieu cach dien. Do vay, tuoi tho cua vat liu cfich din s rat khfic nhau trong nh5ng diu kin khac nhau.Bet the can phai nghien ciru ve tinh chat cc ly hoa, nhiet cua vat lieu cach dien d co th ngan can qiia trinh lao hoa, nang cao tuoi thp cua vfit lieu cach din.3.6.1. Tinh hfitCac vat lieu cach din voi muc do khac nhau du co th hut an (hut hoi nude ter moi trung khfing khi) va th:im him (cho hoi nuoc xuyen qua). i cuc tinh

(g/m). i nhiet dxac di.nh, dtuy I doi khong th

(3-12)

ii trang thai bao hoa cua hoi nuoc trong khfi ng khi Thuong cac :im ke' chi cho so lieu ve do am tuwng dfii ip % nen khi can xac dinh do am tuyet dfii se phiii tinh theo cfing thf rc:

i truong khfing khi (t) ne n m - I(p %, t).

52

VAT LIEU DIEN

op am cua vat ieu y a nong

nuoc trong moton vi trong nong

cua vat lieu.Khi da)t man va) t lieu cach dien trong moi tiuong khfing khi co do am ip% v:i nhieI dfi t ('C) thi sau mot thoi gian nhat dinh, do am ctla vat lieu se dat toi gioi han duoc got la do am can bang (y ).Nu mau vat lieu vfin khfi rao duoc dat trong moi tnrong klifing khi :im (va)t lieu co do am ban dim y < r.by thi v a) t lieu se" bi :im, nghia lit no hit her fim trong khfing khi khin cho do am s tang dan t'i tri so can bang v.b nhu duong 1 trn hinh 3.7 (vat lieu bi rig:inn am).

Ngvac lai, kh i inu vt liu da in trcim trong (co dc m ban

Hinh 3. 7

Dfii v'i vat lieu xfip, loai vat lieu co kh:i nang hut am rat manh, ngucii ta

dna ra dfi finn guy ucic. Do I:i tri diu kin khi h:iu c1iu:in. khi v:it lieu duoc dat trong khfing khi o

3. Tinh whim kmTinh tham :im la kha nang cho hoi am xuyn thau qua vat lieu cach dien. Khi vat lieu bi th:inn am tlii tinh nang cach din cua no giam: p1 (y1), st, tg6lm E3t .Nu vat lieu khfi ng tham nuoc se http thu trn be mat mot luong nucicho Mac heir nufic.Can cu vao goc bin dinh nufic 8 ciia gi pt nuoc tren be in eat phang ciia vfit lieu (hinh 3.6), nguoi ta chia vat lieu cach din hap phu tfi t v:i hap phu yu.8 < 90: vat lieu hap phu tfit (hinh 3.8a).

a) b)

Hinh 3.8

54

rong n eu tnrongpp t uc te vateu cacen con p a c u ta cc hpc, do do khi nghin ciiu v:it lieu cach dien can xt den tinh chat cc hpc cua

3.6.2. Tinh ha hpc cfia vat lieu cach dienTinh chiu nhiet cua v:it lieu cach din la kha nang chiu tac dung cua nhit do cao va st thay doi dot ngot cua nhiet do. Moi loai wit lieu cach dien chi chiu duoc mot nhiet do nh:i t dinh (tuc lit co do ben chiu nhiet do nh:it dinh). Do bn chiu nhiet duoc xac dinh tlieo nhiet do 1:im thay dfi i tinh nang cua wit lieu cach dien.Dfii voi vat lieu cach dien cc, dfi bn chiu nhiet duoc biu thi bang

VAT LIEU DIENo t e uyany t uaten quoc tentemat onaectrica Commission) da phan loai vat lieu cach dien theo nhiet do lamcho php (da nu o bang 3.2).

3. 1. HIEN TRONG DANH THUG DIEN MOI VA DO BEN CACH DIENMuc dich cuav:it lieu cach din trong ky thuat dien I:i de duy tri kha nang cach din cua chung trong din trirong. Boi v:iy, khi nghin corn vat lieu cach din khong th khong xt den anh huwng cua din moi trong

3.1.1. Khai niem v dien trirf mgS' di cac dien tich co tac dung luc tuong tac vent nhau vi dien tich tao ra trong khfi ng gian quanh no mot dien trircing.De dac trung cho su manh yu ciia dien trtrong, nguoi ta dna ra khai niem cufing do din trung E:(3-1)

D - c.ct.ED. la cam ring dien thuong goi la vc to dich chuyn dien tichE: l:i dien trung

56

(3-2)

mza ang so ienonct: hang so dien moi trong chain khong c =l /4H.9.1 i i QF/in)Trong chfin khfi ng - thuc tien- trong khfing khi

Cfin trong moi trirong co hang so din

i c thi

D = c.ct.E(3 -4)Khi ta dat gifra hai din cuc mot tain cach dien hinh 3.1 thi co su khac nhau gi tia dien truong trong khong khi va dien trufing trong trim cach din. Trong khfing khi so duong suc dien traong v:i so ducrng dich chuyn bang nhau, viitii cong thirc(3 -3) din trung la:

ACBHinh 3. I. Tann cach dien nam piiia din moi

(3-5)

i c dienh trircrng giam ty IQ nghicvoi c . Tren hinh 3. 1 cho thay vat c =3 so duong suc dien trung bang I /c= 1/3 so du'ng sfrc trong khfi ng khi. Din tich dich chuyn de'n be mat cfia cach din C, thi mfi t so dien tich b( gin lai, con lai so din tich tp do chuyen dong qua duoc cach din. So dien tich tir do nay tao ra din trung trong cach dien.Nu khe her Ed 1:i dien trirong trong khong khi theo cong thfrc(3. 3) ta co:D = . E = ECon trong cach dien C vo'i hang so dien moi e , tlii din truo'ng giam s Ian tuc lit E= Etc3.1.3. Dec dim dien mfii dat trong dien truougKhac vat kim loai vii cac chat din ph:in, trong dien moi khfi ng co cac hgt mang dien tu do. Su ph:in bo din tich :im vii dien tich duong trong phan tu thuong dfii xting, cac trpng tarn din tich duong va dien tich am trying nhau. Nguoi ta goi cac phan tu do I:i loai phan tu khfi ng phan cuc.

VAT LIEU DIEN

i at ten moi t uoc oaiong p an cuc trongten trirongindien trung se chuyen cac pham tu th;inh cac lufing cuc dien. Cac luong cuc dien dau duwng hufing v phia cfc am cua din trucrng, dau m hufing ve phia cuc duong ciia dien trtrong. Ke't quit 1;i trong dien moi hinh thiinh dien truong mii gpi lit din trucrng ph:in cuc E nguwc chie u vat din trucrng ngo:ii. Curing dfi din truong phfin cuc E nhfi hon curing dfi dien trirong ngo:ii E

nn cufing do din trung tong hpp E trong chat dieni co chiu

cung vfii

(3-6)

c -gpi lit hang so dien

i tuon dot ciia ch;i t dien moi

Hinh 3.2 Su phan cuc cua dien moi

Tuy nhien khi dien moi dat trong dien trung thi co nhung bien dfii cc b:in khi do dien moi chiu tac dung cua cuong do din tracing E dup'c xac dinh nhu sau:UU3-7

3-7 hTrong do: U I:i dien ap dat ln hat cuc dien moih la chiu day khfii dien moi

Hinh 3.3.Din moi kh i ditrong din iiw'ng

Dien moi trong dien trirong phu thufic v:to: Cuong do dien trtrong (m;inh, ye'u, xoay chiu , mot chiu) Thcii gian din moi nam trong din trung ( dai, ngan)

eu to mo trirong n iet oo am ap suat

VAT LIEU DIEN

Ve cc b:in duoi tac ding ciia dien tru rig co the xay ra bon hien tuong cc born sau: Su dan dien cfia dien moi Su ph:in cuc dien moi Ton hao dien moi- Phong thung dien moi3.1.4. Do bn c:icb dienTrong din moi co lan tap chat co kha nang tao ra mot so dien tu tu do. Trong diu kiln binh thung do dan dien cua dien moi rat thap, dong dien qua dien i oi la Khi curing dfi dien tnrong du 16n, luc tinh dien tac dung ln din tu, co the bfrt dien tu ra khoi moi lien ke't vent hat nhan tro th:inh dien tu tu do. Dfi dan din cua din moi tang ln. Dong dien qua dien moi tang ln dfi t ngot, dien moi tro th;inh v a( t dan. Do lit hien ttrong danh thiing cach dien.Cung do dien trtrong dim de g;iy ra hien tuong danh thiing dien cling Ion thi do ben cach dien clingtot. Vi the cung do danh thung ducic gpi la do bn cach dien.Cuong do danh thfing cfia dien moi phu thuoc veto trang thai cfia vat lieu cach dien nhu: dfi finn, nhiet do, tac dung ctia cac tia btic xa,De dam bao clio dien moi lam viec tfit, curing do dien trung dat vao ioi han gpi lit cung do cho php E, . Thong thuing chon tri so E, nhfi hon Eds tir hai de'n ba Ian:

i co the thung Uh va din ap cho php U, cua thit bi:

(3-10)

VAT LIEU DIENangneu en t ong soac trirngmot so vateu cacen I nong

Vi dii: Xac danh din ap cho phep vii dien ap danh thiing ciia mot- 0, 15 cm ap sat vao hai dien cfc, cho bit

binh E = 100 kV/cm. Ta co dien ap danh thung theo (3 -10): Uq = E , .d = 100. 0,15 = 15 kVDien ap cho php:U Uka t ' 5/3 '5 kVBang 3. 1

Vat lieuE kV/cmc

Gray tain dau100 2503,6

Klifing klii301

VaI son100 4003 : 4

Da hoa30 507 8

Paraphin200 2502 = 2,2

Polietylen5002,25

Cao su150 - 2003 = 610"= 10"

Thuy tinh100 1506 1010

Thuy tinh hfru cci400 500310" 10"

Vai thuy tinh300 4003 45.10"

Mica500 10005,45. 10 10"

Dau Xovon1505,35.10" 5. l0'

Dau bin ap50 = 1802 2,510"= 10'

Sir150 = 2005,510"= 10"

Ebonit600 8003 3,5

Cactfing cach dien80 1203 3,5

3.2. DIEN DAN DIEN MOI

60

- Din dantir : Thanh pham mang dien la cac dien tu tu do Dien dan ion : Th:inh ph:in mang din la cac ion duong va ion am Dien dan din ly : Thanh phan mang dien la cac nhom cac phfin tu tich dien, cac tap chat ton tai trong dien moi.3.3. PHAN CUC DIEN MOI3.3.1. Hien tu-Au g phfin cuc dien mfiiKhi dna mot thanh dien moi veto trong dien truong cfia mot v;it mang dien , thi tren cac meat gioi han cfia thanh din moi se xuat hien cac din tich trai dau. Mat dfii dien duiyc tich dien tr:ii dau , mat con lai tich dien ciing dauHien tuong tren thanh dien moi, khi da)t trong dien trirong co xuat hien cac din tich goi la hien tuong phan cuc din moi. Hien tuong nay trfi ng be ngoai giong nhu hin tuong dien trirong trong kim loai, nhimg ve ban chart thi khac h:in nhau. Trong hien tuwng pham cuc din moi, ta khong th t:ich ring cac dien tich de chi cfin lat mot loai dien tich. Tre n thanh dien moi dien tich xuat hien w dau thi st dinh hung w do, khfi ng dich chuyn ter do dupc, vi vay chung duoc goi l:i cac din tich lien kt.3.3.2. Phan tii ph:i n cuc v:i phan tii khfi ng ph:in cucMoi ph:in tu hay nguyn tir gfim co hat nhan mang dien tich duong cfin cac dien tu mang dien tich :im.Khi xt tuong tac cua moi electron vfii cac dien tich bn ngoai coi mot cachg:in dung nhe e dfrng ye n tai mot diem udio doTac dung ciia e trong phan tu tuong duong vent tac dung ciia mot din tich tong cong -q cua chung tar mot diem n:to do trong phfin tu, diem n:iy goi I:i trong tain cua din tich am.Tuong duong nhu v:iy, tac dung cua hat nh:in tuong duong voi tac dung cua

dien tich tong

chiing dat tai trong t:im cua dien tich duong.

61

VAT LIEU DIENan tu ong p an cuc a oatu co p an o cac e o xung xung quanh hat nh;in, tuc la t:inn dien tich duong trying voi t:im dien tich ;im, ph;in tu khfing phai 1:i lufing cuc dien co mo men dien cua no bang khong.Ph:in tu ph:in cuc lit loai ph:in ttr co phan bo cac e khfing dfii xung xung quanh hat nhan, tuc lit t:inn dien tich during khfi ng triing voi trim dien tich am, phan tu I:i luong cuc dien co mo men dien ciia no khac khfi ng.3.3.3. Pham eye dien mfii*/Tru rig hpp din moi cau tao boi phan tu ph:in cuc Khi chua dat dien moi trong din truong ngoai, do chuyn dong nhiet cac lufing circ phan tu cach din hon loan nn tong mo men dien cua luong cfc bang khfi ng. Khi dat din moi trong dien trirong ngoai, cac luring cuc phan tu trong din moi quay theo hu'ng din trir'ng ngo:ii, nn tong mo men din cfia lu'ng circ khac khfi ng*/ Truong hop din moi c:in tao boi ph:in tu khfing phan cuc i tron dien truong ngoiii, phan ttr din moi chua phiii l:i mot luring cuc ( vi tain cfia chung trii ng nhau) Khi d a)t dien moi trong din trtrong ngoiii, cac ph:in tu trong khfii dien moi tro thanh cac lung cuc din do su bin dang cua lip vo e cua phan tu ( su dich chuyn trong trim din tich m)*/ Trufing hop dien moi tinh the- Dien moi tinh the ion co mang tinh the ion 1:ip phuong, co the coi tinh thenhu mot (phan tu khong lo) cac mang ion am va duong triing nhau.- Duoi tac dung cfia dien tiu'ng cac mang ion duong dich chuyn theo chieu din tnrong, cac mang ion am dich chuyen tlieo chiu nguoc lai g:iy ra hien tuong p1i:in cuc din moi goi la phan cuc ion.Kt lua( n: Nhu vay phan cuc la qua trinh dich trong pham vi nho cua cac din tich r:ing buoc hoac st xoay hung cua cac ph:in tu luong cfc duoi tac ding ciia din truong ngoiii.

Trong chfit dien

i ton tai ray it cac dien tich tu do, con lai da so cac

dien tich co lin kt chat ch voi nhimg phfin tu ben canh goi l:i nhimg din tich rang bufic.Ducii tac dung cua din turning, cliung khfing the cach din xuyn suot

qua dieni de tao thanh dong dien, ma chi co th huong theo chiu din truong.

dich r:it it hoac xoay

62

VAT LIEU DIENac ang p an cuc c tin cua ienn Phan cuc dien tu : la dang phan cuc do su xe dich co gicri han cfia cac guy dao chuyn dong cua cac dien tu duoi tac ding cua E ngoai. Phan cuc ion: la dang ph;in cuc do su xe dich ciia cac ion 1ien ke't dust tac ding ciia E ngoiii. Phan circ lung circ : I:i dang phan cuc gay nn b'i su dinh hu'ng ciia cac lufing cuc ( cac phan tu co circ tinh) Ph:in cuc kt c:iu: la dang ph:in cuc dac trung cho dien moi co kt c:iu klifingdong nhat. Phan cfc tip phat: la dang phan circ dac trirng cho cac scnht dien ( dien moi sec nht co dac dim riot bat la phan cuc khi E ngo:ii bang khfi ng).

trucrng, ton hao dien i co the k t hoa hoc trong din moi, co the dan dn pha hfing cach din dan dn dien moi mat han kha nang cach din.Ton hao din moi co the dac trung boi su:it ton liao din moi, do la cong suat ton hao tinh trong mot don vi the tich cua dien moi.fi din ap xoay chiu, ngucii ta thu'ng dung goc ton hao din moi 6 v:i ting voi no la tg6. Goc ton hao dien moi la goc phti cua goc Inch pha ip gifra dong dien i v:i dien ap u trong dien moi.De den gian, ta xt ton hao dien moi cua chat dien moi gifra hai ban cfc cfia mot tp dien.Biet hang so dien moi la c,dupc noi vao mot dien ap xoay chiu U. Khi do: Dong dien tich din cho tu din If se horn hat th:inh phfin (hinh 3.2):

63

I .C.U,(A)(3-12)hayIz 2 H.C. U,(A)(3-13)ong t cen I uc susomso veen ap at vao tu mang tich chat dien dung co tr] so:.

I,

mong do

C. din dung cua tu (F)

f. In so dong din (Hz)U.- din p dt vao In (V) " goc, 2 f (rad!s)

trong do:

Hinh 3.4. Sa d ph be eta dong dienva dien ap trn in din

(3- 14)

= 'tg6hay ID - I, tg6 = or.C.U. tg6ICong suat ton hao dien moi:P - U.ID ' .C.U'.tg6(W)

(3- 15)

(3- 16)

nu thay: C = s.CCl: dien dung chia tu din voi chat dien moi la khfing khic: h:ing so dien moi tuwng drugvao (3- 10), ta duoc:

Voi:

P = to.c.C .U'.tg6 6: goc ton hao din mfii

(3- 17)

c. tg6: so ton hao.Tu (3-17) ta thay P thay dfii Ie thu a)n theo tg6.

64

VAT LIEU DIENu I ay o I an p an c ung to cac en xuong cap su I ay o cua Ip co the do din moi. bi am hoac co cac lip bi ngan mach, kich thucic hinh hoc thay doi). Thanh phan Ig dac trung cho ton hao cong su:i t trong dien moi do dong dien ro.De tinh ton hao din moi, co the sir dung so dfi thay the khac nhau ciia dien moi phu thuoc veto yu can vii muc dich tinh toan. Dung so do thay the' se cho php giai tich hoa mot cach don gian cac qua trinh xay ra trong dien moi (ton hao, ph:in cuc,...) vii con de mo hinh hoa chung tren cac mo hinh mach din.So dfi thay th gfim hat th:inh phan dien dung C v:i din try' R. Cac so dfi thay the can dupc chon sao cho thoa man diu kin n ssuuiiiitt ton hao cua so dfi thay the phai bang cfing suat ton liao trong din moi va goc lch pha cua chung cling phiii bong nhau o cung mot dien ap vii cung mfi t tan so.Mot so dfi thuong hay dung trong cac mo hinh mach dien la so dfi don giam d:iu song song ph;in tu R v:i C (hinh 3.5).

Xac dinh goc lech pha, goc ton hao dien moi*/ Tinh ton hao dien moi trong so do riot tip

Ve gi:in dfi vec to:IRsI

65

cu gian o vec to taot

Cong suiit ton hao din moi

*/ Tinh ton hao dien moi trong so do song song

VG gian do vc to:

U

UU

Vi vfiy trong hat so dfi ton hao dien moi deu phu thuoc tg6*/ Mfii quan he giiia liai so dfiDo hat so dfi den thay the' cho cang mot khfii din moi nen cho nen ton haodien moi v:i goc ton hao din moi trong hai sci do phai bang nhau

Ton hao din

i tron hai

nen

goc ton hao din moi bang nhau:

66

the C v:to ta co:

dd I:i khoang cach giiia hai ban cuc (in), S din tich be mat biin

cuc (in')U =E/d , E cung do dien truong trong khe he (V/m)

4c9. 10 d. f .E . S .d .ig 5

*/ Cac nguyn nhan gay ra tfi n hao din moi- Ton hao dien moi do phan cuc. Ton hao nay do hien tuong phan cuc gay ra, thuo'ng thay o cac ch:it co c:iu tao lung cuc v:i cau tao ion rang buoc khfing chat che. Ton that nay g:iy ra do su chuyn dong nhiet cua cac ion hoac cac phan tfr lufing cfc ducii tac dung cua dien truong, st ph:i huy trang thai n:iy lam mat in:it n:ing luong va 1:im cho dien moi bi nong ln. Ton hao do ph:in circ t:ing theo thin din ap d:it vao dien moi. Ton hao

Trong do: c - la hang so dien moif lit t:in so dien ap67

pa ien tro suat cuaoi ien moi Khi nhiet do tang thi ton hao dien moi c:ing thingP - Ph . e '

Trong do Ph I:i ton hao dien

do 20C,

n:iy ta phiii xem dien

i om hat dien moi ghe'p not tip nhau.

n - C', R'68

3.7. VAT LIEU CACH DIEN THE KHI Dien moi gan bang 1, I:i hang so Dien tro cach din rat tern Ton hao dien moi nhoCac khi cach dien thuong ding trong ky thu a( t dien lit: khong khi, sunfua haxaf1o(SF6 ), Hydrfi (H2), Nito fN2).

3.7.1. Khfing khiTrong so vat lieu cach dien fi the khi vfta neu, truoc tieu ph:ii ke de'n khong khi bcii no duoc str ding rii t rong r:ii de lam cach din trong cac thit bi dien, phfii hpp voi chfit cach dien ran v:i long, trong mot tracing hpp cach din chit yu (Vi du: du'ng day tai din trn khfi ng). Ne'u lay cung do cach dien cua khfi ng khi la don vi thi mot so loai khi duoc diing trong ky thuat dien cho o bring 3.3Bang 3.3

Tinh ch:itKhfig khiNCOCH

Ty trong0,971,520,07

He so thin nhiet11 ,031 , 131 ,51

Cung do cach dien11,000,900,60

Nh;in xt: Da so chat khi co cucrng do cach dien kem hon khong khi tuynhien chung van duiyc su dung nhiu: Vi du: N vi no khfing co oxi nen no khfi ng bi oxi hoa cac kim loai tie'p xuc vat no.Trong thuc t dien ap danh thfing ciia khfing khi duiyc xac d(nh nhu sau: Voi U xoay chiu co =50 Hz thi cfr 1cm khoang cach klifing khi chiu duoc 3,2 de'n 3,5Kv ( trng vcri truong h pp din trtrong r:it khfi ng dong nhat) nhu vay Shoring cach a chin thiet de khoi bi danh thfing lit

o >

3.7.2. Sunfu a haxaf lo (SF6 )

Ucm 3,2

(3-14)

SF6 cfin co ten got elegaz I:i chat khi nang hon khfi ng khi 5 lfin, hoa long o nhiet do -1 8C. fi trang thai binh thucrng, SF6 khong mii, khfing vi, khong doc, khfi ng an mon, khfing chay v:i rfit tro. Cuong do cach dien cfia no cao69

VAT LIEU DIENon cuongo cacen cuaongan coo onncao coanang dap tat hfi quang tfi t.No du9c diing firm moi trucrng cach din chit yu trong cac may cat cao ap, trung ap. Ngoai ra con duoc diing trong tu dien, cap din luc,Tuy nhin, khi su dung c:in cliu y: SF, la khi tu phuc hfii. Do la do khi hap thu cac dien tu tu do do ho quang tao ra lam ion hoa khi. Cac ion Hi hpp lai tao khi SF6. Khfi ng ph:ii tat c:i ion va nguyen tu tu do tai hpp lai, vi v:iy khi SF6 bi hfi quang tao nn cac siin phfim doc hat, thu'ng l:i sunfua.San nhieu lan thao tac khi co miii triing thfii, neu co mui n;iy chin tien hiinhcac bucic sau:Thao klii khoi thit bi.Mr cf ra, thong gio cuong buc.Tach cac s:in pham hfi quang (th ran) triroc khi dna v:to thit biCac siin pham hfi quang phiii chf ra trong thiing chat deo v:i dat trong thung kin de dam bao an toan.

3.7.3. Nittr (N )Nito doi khi duoc ding de thay khfi ng khi trong cac tp din khi do no co curing dfi cach dien gan khfing khi (Nu lay curing do cach din cua khfi ng khi la 1 tlii cua Nito ciing khoang g:in 1). Mat khac, vi no khfing chfra oxy O nn khfing co hien tuong oxyt hoa cac kim loai no tip xuc.

3.7.4. Hydro (H )Hydro I:i mot loat khi r;it nhe (ne'u l iiy ty trong cfia khfing khi la 1 thi ty trpng ciia H lit 0,07) lat co he so tan nhiet cao (nu khfing khi 1 thi H, lit 1,51) cho nen no duoc dung nhiu de lam mat cac may dien thay cho khfing khi. Do khfing co oxy nn no se lam chain duo'c toc do lao 1ioa vat lieu cach din lifru cc va khu duo'c su co chay cuon day khi co ngan mach o bn trong may dien. Khi lam vic trong moi truong H cach din, chfii than dupc cai thi n hon.Song khi dung H de cach dien chin phai bpc kin may dien lgi v;i phai gin cho ap suat ciia khi H lean hon ap sufit khi quyn de khfing cho khfing khi lot v:to tranh xay ra chay no.

3.7.5. Cac khi khacNgoai cac khi k trn nguoi ta con dung cac khi nhu Argon, Non, hoi thuy ngan, hari Natri, trong cac ding cp chan khfi ng. Chang han cac loai den din dung chieu sang trong ky the eat va dfii song sinh hoat.

3.8. VAT LIEU CACH DIEN O THE LONGTrong so vat lieu cach dien o the long, dau mo v:i cac loai dau khac co ngufin gfic tu dau mo duoc diing nliiu trong ky t1iu:it dien.D:iu mo dune khai thac trong thin nhin. Sau khi qua cac bi n phap lpc don gi:in de khii nu'c v:i biin rfii qua cac bien phap tinh luyen tuong dfii phtic tap s duoc loai dfiu tfi t duoc sir dung nhiu trong cfing nghiep.D:iu mo I:i hpp chat cua cac cacbua hydro (ham luong C khoang 8587% con H 1:i 1 1 14%), ngoai ra cfin co mot so hop chat khac cua oxy, lipp chat sunfua, hop chat N ito...).Trong d:iu mo co nhiu loai cacbua hydro, vi du parafin C,H+ loai cacbua khfing no C,H loai cacbua thom CMH ,.,.Hop chat cua oxy chu yu la cac loai axit, vi du axit naptenicC6H i COOH, cac ch:i t keo, hac in,... lam cho dan co mau sae va co can.Hpp ch;it sunfua co nhieu toai nhu ttr sunlit hydrogen (khi sunfiiro HTS) den bisunfit cao phan tu.Ngoai ra do qua trinh tinh luyen trong dfiu mo con co them mot sfi chat khac, vi du sunfit sodium (SO@a), cac hat cao lanh rat nho va chua loc duoc ht.Nhu vfiy, trong dau mo co nhiu thanh phan v:i h:im luong ciia moi th:inh ph;in khac nhau, vi the' tinh htm g ciia chung den tinh ch:it cfia d:iu cling khac nhau.Duoi day ta xeI mot so loat dau mo phfi bie'n thuong diing trong ky thuatdien.3.8.1. Din m:i y bin apDau may bien ap I:i hon hop cua cacbua liydrfi o the long, co mau sac khac nhau.Loai din nay dope dung trong cc my bin ap vat mvc dich.

VAT LIEU DIENap n cac o xop cua vat eu cac en so ap n cac oang trong giiia cac cufin d:iy, gifia cac cuon d:iy vii vo de I:inn tang kh:i nding cach dien cua wit lieu.Car thien dieu kien t;in nhiet do ton hao cong suiit trong cuon d:iy vii Hi may bie'n ap (dan t;in nhiet tot hon khong khi trung binh khoang 28 Ian).Ngoai ra, dau may bin ap con dupc dung trong cac may cat dien co dau, tu dien, cap din luc,- Dt1 u bin th c inn dim saw:+/ Do bn cach dien cao: khoang 160kV/cm vfii dau mii+/ H:ing so dien moi c - 2,2 =2,3 gan bang mot nfra dien moi chat ran+/ Sau khi danh thiing, kh;i nding cach dien khai nding cach dien ciia dim phu hfi i try' lai.+/ Co th xam nhap v:to cac khe ranh hep, vtra co tac dung cach dinvua co tac dung lain mat.+/ Co the sir dung lam moi truong dap tiit ho quang trong MCD ( maycat dau hien nay it dung)- Dti bin th c nhmpc dim salt:+/ Kh:i n;ing cach dien ciia dau bie'n dfi i ton khi dam bi ban, ski bfing, giay nucic, muoi than.Voi dfiu MBA sach, do ben cach dien: 20-25 kV/mm, nhung nu h:inn luongnufic trong dau tern hon 0,05% thi do bn cach dien chi con 4-5kV/mm.+/ Khi co nhiet do cao, dau co su thay dfii ve hoa hpc, su thay doi do litco han, do la sir hoa gia cua dau.+/ De no, de chay.- Dti bin th c cc ttnh cht sari:+/ Din try suat tin 10" 1 0" mcm i c - 2,2 +/ Nhiet do lam viec o ch do dai Iran 90- 95'C klifing bi hoa gia nhiu+/ Do bn cach din r:it caoQuy dinh enng d etch din v tn hao din m i cac cup din Up.Tiu chuan v cufing do cach dien cua dau may bin ap ci cac cap din ap cho o bring 3.4Bang 3.4Cap din apCuong do cach dien cuaCuong do cach dien cua dau

72

VAT LIEU DIEN

trong vanDe n 6 kV6 kV 35 kVTrn 35 kV16

Nuoc, khi am co :inh huiig nhie u den caong do cach dien ciia dau. Cang xiiu hon nua khi trong dfiu co cac soi vat, gifiy I:i cac vat lieu de hut am.Vi vay nu ke'I qua thi nghiem thap hon cac tri so nu o b:ing 3.3 thi cfin ph:ii thay the d:iu hoac loc va tai sinh.+/ Ton hao dien moi be:tg6 khfi ng duo'c vuot qua 0,003 khi o nhiet dfi 20C. tg6 khfi ng duoc vuot qua 0,025 khi ' nhiet do 70C.Do nhot ciing quan trong dfi i vcri kh:i nang lain mat cfia d:in bien the < 6,63E(Eng1er ) fi nhiet do 1:i 20 C ho a) c < 1,8 E fi nhiet do 50 C(3- 15)

- Co sir xiim nh:ip cua khfi ng khi long: am, oxi- Co nhit do cao Co tie xuc vviiiiii ccaacc kkiimm llooaaii:: DDoonng, ss:aitt, cchhii .Khi dau b| gia coi, d ding lai thi phai tai sinh no bang cacg lpc v:i hap thu nh:inn loai bo nucic va tap ch:it Viec loc du9c tin hanh trong cac truong hop: trucic khi cho dau moi vao TB hay khi ph:it hien trong dau co nuoc clan hay cac chi tieu ky thuat vuwt qua guy dinh. De lpc bo nude ngucri ta diing phuong pahp lpc ly tain de lpc bo can ngucri ta doing giay lpc, de lpc cac thanh phan khac nguoi ta dung cac chat hap thu nhu: Siliccagen kim, Siliccagen cao lanh. .

VAT LIEU DIEN

ac inten ap antg:d+/ Trircing hpp din tracing dong nhat ( hai din cuc phang hoac din cuc tru v:i din cuc phang)U 40.n + 25(k U)(3- 16)a: la khoang each dien circ voi a- 3- 40cm va ban kinh dien cuc hinh tru Ibn hon 25cm+/ Trirfing hpp din truong rat khong dong nhat ( gifra hai dien cuc

nhon)

(3- 17)

+/ Trucrng hop die'n trucrng khfing dong nhat ( die'n cuc nhpn va din cuc phang)

anhTrong qua trinh van h:inh, dau thucing bi xau di, pham chat cach dien cfia no giam. Do la su lao hoa cua d:iu. Khi dau bi lao hoa thuo'ng co mau Hi va da) c, dieu do lit do trong dam hinh thiinh nhiu keo, nhua, hac in...gpi chung 1;i bi nhie m born trong qua trinh van h:inh. Toc do lao hoa cfia dau tang nhanh

Khng khi xam nhap van du,Trong khfing khi chua nliiu ho'i nuoc v:i dau lai r:it nhay cam vo'i do :im. Mat khac, qua trinh lao hoa cua dau con lin quan den st oxyt hoa bfii oxy co trong khong khi.Nhit d cao.Dau co su thay doi ve hoa, su thay doi nay co hai va @o bpt trong dau, I:im cho dfi nh't gi:inn v:i lam nghet cac khe h' trong cuon day va trong cac bo phan cua may bin ap.Tip x c vi anh sang, incit so kim loai nhu Cu, Fe, Pb...va mot so hoa chat khac co tac dung nhu chat xuc tac cua su lao hoa dau khi dau tie'p xti c voi anh sang.

74

VAT LIEU DIENau a ao oa co I e I ay I e au mo oac muon su ung a can ph;ii tai sinh lgi no (tuc lit khf r cac s:in ph:inn do su gin cor cach dien sinh ra v:i khoi phuc tinh chart ban dau).Trong viec tai sinh d:iu, co the ding cac bien phap:Lpc bang xiphfing nhiet.Diing cac hon hpp hay cac chat hap thu de tai sinh nhu: hon hop axit sunfuaric-kim-caolanh, hon hpp axit sunfuaric-caolanh, hon hpp silicagen-kim, hon hop silicagen-caolanli.

1. Du X vn: Loai n;iy lit do su clo hoa cacbua, nghia I:i thay bit mot songuye n tu H bang ngiiyen tu Cl.D:iu Xfi von la do su clo hoa cacbua hydro diphanyl (C Hthay 5nguyn tu Cl dupc C H,Cl,).fi nhiet do binh thuong v:i Ian so thap, hang so dien moi cfia no c = 5 (nghia lit 16a hon dan mo Shoring 2 Ian) vii quan he vcri nhiet do on danh hon so voi dau mo khi dat trong dien tru'ng.Vi hanghon dau may bin ap nn dfiu Xfivfin thuong duiyc dung thay cho dau may bie'n ap de him dien moi trong cac j din. Luc do, the tich ciia tu co th giiim di 2 Ian ma cfing suat ph:in khang khfi ng dfi i.D:iu Xfi viii ciing co mot so nhuwc diem: do nhat ton, kho th:inn nhap veto cac khe, r:inh hep nn khong ding dupc trong cac may bin ap va dat hon dau mo nhieu.

2. DC u Xtn: Dan Xoton la dau Xovon dupc pha loang bang triclobenzen C6H Cl de co the sir ding duoc trong cac may bie'n ap. Song cling nhu diiu Xovon, no chiu nhiet do tot nhung khong dung trong cac may cat dien co dau vi khi bi huynh quang dfit chay sinh ra nhiu bfi hong an mon kim loai. Mat khac no rat doc hai doi voi con nguoi.

1. Dtim ty kho (dim gai)L:i loai d:iu ma duoi tac dung nhiet, anh sang va tip xuc viii klifi ng khi, no se chuyn sang trang thai ran co curing dfi cach dien cao va co the chiu duoc tac dung ctla dung moi. Sir khfi ctla no khfi ng ph:ii l:i do su bfic hot ciia dung moi ma I:i mot qua trinh phuc tap co lien quan den su hap thu mot luong oxy, vi the' trpng luong ctla no tang len khi khfi.Co the ding loat dau n;iy de ng;im tain cac cuon day trong cac may dienv:i thie'I bi dien.

2. DC u theu duLoai n:iy khfing phiii lit d:iu lit kho, no kho riit ch:inn ho a)c khong khfi ne n khong co gia cong hoa hpc. Thuong duoc diing d t:inn giay th dien.

76

noay g o teu mot so v