- Nham: dqc dung lam cac chi tiet tiep xuc cJ can lay di$n cua cac ph cJng ti$n v(m tai bang di$n.
d) Cat vait li~u kiml oi gom:
Cac dffic diem xem xet cua cac v$t li$u nguyen chat cho thay rang khong m(>t v$t li$u nao trong so d6 dap Cing d-qc day du cac yeu cau doi voi v$t li$u tiep diem.
Cac tfnh chat co ban cua v~t li$u tiep diem nh- tf nh dan di$n cao va tf nh ch!u ho quang cao, kh6ng the nh$n d- 9c 6 h9p kim giCfa cac v$t li$u c6 tf nh chat tr9i 6
cung cac d$c tfnh nh- v$y, vf dy nh- b9c va Wolfram, dong va Wolfram, bbi v1 cac cac v$t li$u nay khong the t90 nen d- 9c h9p kim.
Cac v$t li$u c6 tf nh chat mong muon noi tr9i d- <;Jc ket h<;Jp voi nhau qua ph- ong phap luy$n kim b9t (kim lo9i gom). Cac tfnh chat v$t ly cua v$t li$u thanh phan ben trong v$t li$u kim lo9i gom d- <;Jc dap ung. Vf dy nh- tfnh ch!u dlfng ho quang trong v$t li$u kim lo9i gom la do cac thanh phan wolfram ho$c Molipden chua trong d6. De nh$n di$n trb tiep xuc nho, thanh phan thu hai trong tiep diem c6 the la b9c ho$c dong. Thanh phan wolfram cang Ion th1 tfnh ch!u ho quang, d9 ben · co, tfnh chong han dfnh cang cao nh- ng dong thoi l9i lam tang di~n trb tiep xuc va giam tfnh dan di$n cua tiep diem. Thong th- ang cac kim lo9i gom c6 chua 50% ho$c Ion hon, wolfram d- 9c ung dyng trong cac thiet b! dong cat phy tai n$ng ne ho$c cat cac dong di$n ngan m9ch.
Tfnh chat va thanh phan cua m9t so lo9i kim lo9i gom th- ang g$p cua Nga d- <;IC cho trong (bang 3.13).
Bang 3.13: Tf nh chat va thanh phan cua m9t so lo9i kim lo9i gom. Ma hi$u v$t
Cac thanh phan chfnh Tn;mg I- <;Ing Dien trb 89 cung
lieu rieng kg/m3
suat µ.n.m Brinel
KMK-A 10 B9c 6xyt Cadmi 9700 0,030 45 - 75
KMK-A20 B9c 6xyt dong 9500 0,025 45 - 60
KMK-A31 Bae - Nikel 9500 0,032 60 - 80
MKM-A60 Bae - Wolfram - Nikel 13500 0,041 120 -160 MKM-A61 Bae - Wolfram - Nikel 15000 0,045 170-210
KMK-B20 Dong - Wolfram - 121-00 0,06 120 - 150
Nikel
KMK-B21 Dong - Wolfram - 13800 0,07 170 - 200
Nikel
Doi voi cac tiep diem cua khf cy di$n cao ap th- ang s11 dyng kim lo9i gom MKM -A60, MKM -A61, KMK- B20, KMK - B21.
Trong cac khf Cl:J di$n h9- ap th- ong ap dl:Jng V?t li$u: KMK - A 10, tll B9c va oxyt cadmium (CdO). 0ff}c diE~m cc:5 ban cua V?t li$u nay la SI/ phan huy cua CdO thanh Cd va 02 . Khf 02 nh?n d-qc d-di tac d9ng cua ho quang c6 tac dl:Jng lam giam nhi$t d9 cua tiep digm va d§y m9nh qua tr1nh khu' ion.
3.5.7. Hqp kim c6 niet1 trc:1 cao va ch u nhi~t: 1) Khati niem; 1) Khati niem;
Cac hqp kim di$n trb cao la nhilng hqp kim c6 di$n trb suat t- e5ng doi I6n nen c6 tfnh chat can trb dong di$-n cao gay slf toa nhi$t tren day di$n trb.
* 0ac tfnh:
- 0i$n trd suat t- e5ng doi I6n nen h9-n che d-gc chieu dai day dan.
- Ch!u nhi$t d9 cao (yeu to can thiet doi v6i di$n trb toa nhi$t). - C6 d9 ben ve cc:5 cao.
- H$ so nhi$t d9 thap. - Chong slf oxy hoa.