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Gio vin hng dn: Chu Vit H Sinh vin thc hin: Bch Th Ngc ViLp: L 46C NO21VT LIU IN MICH 18NI DUNG TRNH BYI. Khi nimII. Phn loiIII. c im, tnh cht1. Tnh cht ht m ca in mi2. Tnh cht c hc ca in mi3. Tnh cht nhit ca in mi4. Tnh cht ha hc ca in mi-s gi ha5. Tnh chu tc ng ca bc x nng lng cao6. S nh thng in miIV. ng dng ca vt liu in mi2Vng dnVng ha tr33II. PHN LOI1. Phn theo trng thi: Vt liu cch in c phn loi theo cc dng: Kh, lng, rn. Ngoi ra cn c vt liu ho rn. 2. Phn theo bn cht ho hc: +Vt liu cch in v c v hu c. Cht hu c: Nhng hp cht cha cc bon, H2, O2, N2... Cht v c: xi mng, mica, si thu tinh...+ Cch in hu c c tnh c hc ni bt l tnh do, n hi tuy nhin chng c bn nhit thp.+ Cch in v c thng gin, khng c tnh do v n hi. Ch to phc tp nhng c bn nhit cao.

43. Phn loi theo kh nng chu nhitVt liu c phn thnh cc cp Y, A, E, B, F, H, C. Vic phn cp theo nhit lm vic ln nht cho php c ngha thc tin quan trng.

Phn cpNhit lam vic ln nht cho phepCp YCp ACp ECp BCp FCp HCp C90105120130155180>1805Cp Y: bao gm cc vt liu si gc xenlulo v t( vi, si, giy, g,..) cha c ngm tm trong vt liu cch in lng.Cp A: l cc vt liu cp Y c ngm tm( giy vi, vi tm, nha poolyamit)Cc loi Y, A, E gm ch yu l vt liu thun ty hu c: 1 s vt liu cch in hu c( cao su, polystyrol) c bn chu nng cn thp hn loi Y khng c a vo phn loi.VD: vi loi Y gm cc vt liu gc xenlul v t nu chng khng c ngm tm; nhng nu chng c ngm tm chng s thuc loi A.Cc loi c bn chu nng cao hn cha thnh phn v c nhiu hn.VD: loi C gm cc vt liu v c thun ty, khng c TP kt dnh hoc tm xy nhm, mica

5III. C IM, TNH CHTTnh ht ma. m ca khng kh a - m tuyt i: m [g H2O / m3] c nh gi bng khi lng (gram) ca hi nc cha trong 1 dn v th tch khng kh (m3). 1 nhit nht nh no , m khng vt qu 1 tr s nht nh m mmax : m bo ho.b - m tng i:

iu kin chun ca kh hu: t0 = 200C, P = 760mmHg, m = 11g/m3, = 65%b. m ca vt liuCc vt liu in mi vi mc nhiu hay t u ht m tc l c kh nng ht vo trong n hi m t mi trng xung quanh v thm m tc l c kh nng cho hi nc xuyn qua.

6 m tuyt ing vi mi nhit xc nh, khng kh khng th cha 1 lng nc ln v vy n s ri xung di dng sng- m tng iiu kin bnh thng ca khng kh c ly bng m (60-70%) nhit (20 5)0C.6c. Tnh thm m L kh nng cho hi nc i qua ca vt liu cch in. thm m ca vt liu:m: Lng hi m (microgam)t: Thi gian (gi)S: Din tch mt phng (cm2)h: Chiu dy lp vt liu cch in (cm)P1, P2: p sut 2 pha ca vt liu (mmHg): thm m ca vt liu ang xt

(Ring c thu tinh, gm nung k v kim loi l c thm m thc t = 0).

772. Tnh cht c hc bn t, nn, un: Ph thuc vo din tch tit din ca vt liu. V d: si thu tinh: ng knh si gim bn ca vt liu tng; Khi ng knh gim xung cn 0,01mm th n t ngang bn ca dy ng. bn ca vt liu cn ph thuc vo nhit , khi nhit tng th bn gim.b. Tnh gin: Biu th bng di va p: Vi: A - nng lng b gy mu vt c tit din S (kg.cm) S - din tch mu vt (cm2)

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[kg.cm/cm2]- Tnh gin l kh nng b ph hy ca vt liu m khng b bin dng. gin ph thuc vo cu trc ca in mi 8c. cngBiu th kh nng ca b mt vt liu chng li cc bin dng gy bi lc nn truyn t vt liu c kch thc b hn

Vi: D - ng knh vin bi thp h - ln P - lc nnd. nhti vi vt liu cch in th lng hoc na lng nh du, sn th nht l mt c tnh c hc quan trng.

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3. Tnh cht nhitTnh chu nng L kh nng vt liu in mi v cc chi tit chu ng khng b h hng trong khong thi gian ngn cng nh lu di di tc dng ca nhit cao v s thay i t ngt ca nhit . i vi in mi v c: bn chu nng c xc nh theo im bt u bin i tnh cht in. i vi in mi hu c: bn chu nng xc nh theo im bt u bin dng c hc ko hoc un.b. Tnh chu bng gi ( bn chu lnh) L kh nng cch in nhit thp, nhit thp tnh cch in tt hn nhit thng nhng in mi tr nn gin.c. dn nhit Tnh dn nhit ca in mi l mt trong nhng dng chuyn nhit t ni c nhit cao n ni c nhit thp hn dn n s cn bng nhit.

1010d. S gin n nhit ca in mi: c biu th bng h s gin n di L, n th hin chiu di ca vt s tng ln bao nhiu khi nhit tng ln l 10C. [-1] Nhng vt liu c h s gin n di theo nhit nh thng c bn chu nng cao v ngc li. in mi hu c c l rt cao so vi in mi v c. v vy cc chi tit ch to t in mi v c c kch thc n nh cao khi nhit thay i. H s gin n di theo nhit :

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Vt liul.106 (-1)Nhn xtThu tinh thch anhS cao tn0,554,5VcFenolfomandehit v cc cht do c n khcTm cht do clorua polivinylPolitylen25 - 7070100Hu c124. Tnh cht ho - s gi ha Tnh cht ca vt liu cch in trong thi gian vn hnh b gim st lin tc ta ni vt liu cch in b ha gi. Qu trnh ha gi thc cht l kt qu ca s bin i ho cht xy ra nhanh hay chm do iu kin vn hnh tc ng. Nhng yu t nh hng n s ha gi ca in mi: Nhit : tc ca phn ng ha hc tng vi nhit theo hm s m, s gim st tnh cht cch nhit gia tng rt mnh khi nhit tng.Nhng tc ng c hc trong qu trnh ch to, qu trnh vn hnh.Nhng tc dng ha hc tc ng ln vt liu cch in pht sinh t nhng vt liu cch in gn bn, t mi trng xung quanh, t vt liu in cc.

Nhng qu trnh ha hc ch yu gy nn s ha gi ca vt liu in mi:S xi ha: lm cho vt liu in mi sinh ra nhng cht mang tnh axit, lm suy gim tnh cht cch in v y nhanh qu trnh ha gi bng tc dng xc tc.S trng hp: lm gim tnh cht c hc, vt liu in mi tr nn gin,t thng s in b gim theo.S thy phn: nhng phn t nc lm cu trc phn t b lng lo.S bay hi: nhng sn phm lm mm hoc d bay hi th thot i s lm vt liu b gin, co ngt ,tnh cht c b suy gim .135. Tnh chu tc ng ca bc x nng lng caoKh nng chu tc ng ca bc x ht nhn, sng c nng lng cao ca vt liu in mi, kh nng ny c gi l bn bc x.6. S nh thng in mi Mi in mi nm trong in trng s mt thuc tnh cch in nu cng in trng vt qu tr s gii hn cho php gi l hin tng nh thng in mi hay cn gi l hin tng ph hu bn in ca n. Cng nh thng

Vi: Ut l in p nh thng (KV) Et l cng nh thng (KV/cm, KV/mm, V/m) h l chiu dy in mi (cm, mm)

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14a. in mi kh Thc t s nh thng cht kh thng xy ra tc thi. Khong thi gian chun b nh thng kh khi di khong kh bng 1 cm l 10-7 10-8s. nh thng cht kh ph thuc: hnh dng in cc v khong cch, in p t vo, thi gian tc ng, m khng kh, mc ng nht ca in trng, nhit v p sut ca kh.b. in mi rn Khi in p tng n 1 tr s no , th cnh mp ca in cc xut hin vng quang ri pht trin thnh nhng tia la in. Hin tng ny l phng in b mt. Cc yu t nh hng n phng in b mt: Tnh trng b mt ca in mi, nhit , p sut kh, m mi trng, thi gian tc ng ca in p, hnh dng ca in cc.c. in mi lng in mi lng iu kin bnh thng c bn in cao hn cht kh rt nhiu. Cc yu t nh hng n s nh thng in mi lng: tp cht, nhit , p sut, thi gian tc ng ca in p.

15IV. NG DNG CA VT LIU IN MIVt liu in mi lm vt liu cch in Chng dng ch to ra vt cch in bao quanh nhng b phn dn in trong cc thit b in v tch ri cc b phn c in th khc nhau, nhim v ca cch in l ch cho dng in i qua nhng con ng trong mch in c s quy nh.2. Vt liu in mi lm vt liu quang c ng dng rt nhiu nh: vt liu in mi c ch to lm vt liu quang t nh s sp xp cc lp vt liu in mi xen k nhau vi mt quy tc xc nh to nn nhng vt liu c tnh cht qy gi.Vt liu quang t c th iu khin nh sng nh s phn x, s khc x, s giao thoa, ng dng: si tinh th quang t, quang hc mng mng: mng phn x, mng truyn qua,

163. Phn loi v ng dng Vt liu in mi th kh Hng s in mi gn bng 1.in tr cch in rt ln ph thuc vo in p.H s tn hao ph thuc in p. bn cch in ph thuc nhiu vo p sut, cc thng s hnh hc ca in cc v thi gian tc ng ca in p.ng dng: khng kh, nit, SF6s dng trong t in, cp in, my ct, my bin p,

17 Vt liu in mi th lng - du bin th:Du bin thu im: c bn cch in cao, hng s in mi =2,3 tng ng vi mt na in mi rn, sau khi b nh thng kh nng cch in ca du phc hi tr li, va cch in va c tc dng lm mt, c th s dng lm mi trng dp tt h quang in my ct in.Nhc im: cc tnh nng in ca du bin i ln nu du b bn, nhy cm vi m, nhit cao c nhng thay i ha hc to bt trong du tnh nng cch in v lm mt u gim, d chy.Du cho tu in: dng tm cho tu giy nhm lm tng hng s in mi ca tu du, c tc dung lm tng in dung, gim kch thc v gim gi thnh ca tu.

18Du dng cho cp: Du c tm trong cp giy c tc dung lm mt v tng bn in ca cch in.Du tng hp: Nhm muc ch nng cao in dung trong tu in, s dung loi du c cc, c gi tr cao, vi th c th gim kch thc tu in. Nhiu loi du tng hp cn c tnh cht vt xa tnh cht ca du bin p. Mt s du tng hp thng dung c s dung trn thc t nh : du sovol, silic hu c, flo hu c.

19 Vt liu in mi th rn in mi hu c cao phn t gm : Nha cch inPolyetylen (C2H4)n: c bn c tt, chu c axit, kim , khi nhit tng bn c gim =>dng lm cht cch in cho dy cp in thoi, cp in lc.Polystirol (C6H8)n: c tnh cch in cao, tnh ht m thp, nhit thp rt gin, tnh chu nhit khng cao, km bn vi dung mi => dng lm in mi trong k thut siu cao tn, lm v bc cc cun dy , sn, hn hp cch in,Polyvinylclorua (C2H3Cl)n:rt bn vi nc, kim , axit long, xng du v ru =>dng lm cht cch in cho dy dn, v bc bo v cho cp, v bnh cquy,

20 Cht n hi - cao su cch inu im: n hi cao, c kh nng chu ko, cao su cch in thng thng c = 37 Nhc im: bn nhit thp(ha gi khi b nung nng), t chu c tc dng ca du m, xng, km bn i vi tc dng nh sng v cc tia t ngoi.

ng cch inGng tay cch in

in mi v c in mi v c l loi vt liu quan trng trong k thut in v v tuyn in. a s cc in mi c cc c tnh tt nh tnh chu nhit cao, khng ht m, bn c cao v n nh, chu c tc dng ca bc x nng lng. nghin cu c im,tnh cht ca vt liu v c chng ta i nghin cu cc loi vt liu chnh: thy tinh, vt liu cch in bng gm s,21 Thy tinhL nhng hp cht v nh hnh v l h phc hp ca nhiu loi oxit khc nhau: SiO2, Ba2O3, Tnh cht: bn nn ln hn bn ko, in dn b mt ph thuc nhiu vo tnh trng ca thy tinh, n tng ln khi mt ngoi thy tinh b nhim bn, thy tinh c bn in rt ln khi in p mt chiu trong in trng ng nht c th t 500kV/mm.ng dng: ch to cc chi tit nh v, in thoi, ngten (thy tinh nh v).Thy tinh bng n: lm bng n, thy tinh t in, in mi cho cc loi t,22Mt s hnh nh v vt liu thy tinh

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Thy tinh t inThy tinh bng n23 Vt liu gm - sGm thng: ch yu l , Al v khong ferpast, dng sn xut ra cc loi s cch in, cc sn phm lm ra phi c trng men v nung nng. Lp men thy tinh s ngn cho hi m thm vo cc l xp, tng in p chu phng in cho b mt, gim bt s r in theo b mt, loi b cc vt nt b mt nn bi v cc cht bn khc t c kh bm vo. ng dng: lm s ng dy, s trong trm, s dung cho thit b in t,Gm t in: c hng s in mi cao dng lm t in gm, gm xenhit BaO, . 24

Mt s hnh nh v vt liu gm s

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25B XUNG: Nhng hin tng xy ra trong in mi khi c t trong in trng

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1-Dng in o in p xoay chiu2-Dng in o in p mt chiu1. To ra dng in r2. To ra dng in phn ccNh vy khi t in mi trong in trng E, in p U, ta thy tr s dng in i trong in mi gm 2 thnh phn: I = Ir + Iphn ccIphn cc : in p 1 chiu th tn ti trong thi gian qu khi ng hay ngt mch, in p xoay chiu th tn ti trong sut thi gian t in p.Ir : tn ti trong sut thi gian t in p.3. Sinh ra tn hao in mi4. Nu cng in trng ln hn gii hn cho php ca in mi s gy nn hin tng phng in chc thng in mi5. Lm gi ho v gim tnh cch in ca in mi

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h

P

D

I(A)

Iphn cc

Ir

t(s)

2

1