a) Vaa: lieu dung lam tiep niem coanonh:
Doi voi v$t li$u dung lam tiep diem co djnh ng- cJi ta sll' dl:Jng dong, nh6m, thep va kem.
- Dong: c6 d(> dan di$n va dan nhi$t cao, voi pham chat t- (Jng doi cung, cho phep tac d(>ng d6ng cat th- cJng xuyen. 8- qc dung cJ di$n ap nho, dieu ki$n lam vi$c b1nh th- cJng. De tang sue ben doi voi slj an mon cac tiep diem ng- cJi ta m9 niken ho$c tam thiec khi n6ng hay b9c b9c.
- Nham c6 d9 dan di$n va dan nhi$t t- (Jng doi Ion c6 sue ben c(J thap va c6 di$n trcJ suat Ion h(Jn dong, do v$y kh6ng dung cJ n(Ji c6 dong ngan m9ch Ion.
- Thep c6 t6n that Ion trong dong di$n xoay chieu nen d- qc sll' dl:Jng cJ n(Ji c6 c6ng suat be va di$n ap Ion. N6 bj an mon m9nh trong kh6ng khf am -ot.
b) Vaa lieu dung lam tiep niem call::
NhU'ng kim lo9i va hqp kim dung lam tiep diem cat gom: Rodi, platin, paladi, vang, b9c, vonfram, molipden, dong, niken ...
- Platin: c6 tfnh 6n dinh cao doi voi slj an mon trong kh6ng khf, kh6ng t9o mang 6xyt nen dam bao d- qc St/ 6n djnh di$n cua tiep diem, tuy nhien platin d(> mang 6xyt nen dam bao d- qc St/ 6n djnh di$n cua tiep diem, tuy nhien platin d(> cung thap nen mai mon nhanh ch6ng do d6 ft sU' dung platin tinh khiet. Hqp kim platin voi iridi c6 d(> cung cao va nhi$t d(> n6ng chay cao,suc ben tot doi voi St/ tac d9ng cua ho quang,d-(Jc dung che t90 cac tiep diem quan tr9ng c6 d(> chfnh xac cao va dong di$n nho.
- Palaai: c6 tfnh chat t- ong tlj nh- platin song n6 c6 sue ben tot h(Jn doi voi slf 6xyt hoa trong kh6ng khf. slf 6xyt hoa trong kh6ng khf.
- Roai: rat thong dl:Jng de lam cac tiep diem c6 yeu cau chfnh xac, n6 c6 d(> cung cao, nhi$t d(> n6ng chay va di$n dan suat cao, c6 sue ben doi voi slj an mon. cung cao, nhi$t d(> n6ng chay va di$n dan suat cao, c6 sue ben doi voi slj an mon.
- Vang: c6 d$c diem la sue ben kem, do v$y ft dung vang nguyen chat de lam tiep diem. tiep diem.
- 8 c: d- gc dung lam tiep diem v1 c6 d(> dan di$n va dan nhi$t, lop oxy h6a
be mfflt tU' b9c c6 di$n trc:J suat giong nh- b9c tinh,khiet nh- ng d(> ben ccJ khf kem va nhanh ch6ng bl pha huy khi tiep diem bl phat n6ng. Tiep diem b9c ben vCrng, yeu cau llfc ep tiep diem nho. M(>t dffic diem ccJ ban nCra cua b9c la c6 di$n trc:J tiep xuc Rtx nho. B9c bl an mon nhieu khi c6 slj xuat hi$n cua ho quang di$n. 0(> cCing thap cua b9c da h9n che Cing dL,mg n6 vao trong cac tiep diem dong, cat dong di$n Ion va c6 tan so thao tac cao.
Ng- ai ta dung hgp kim b9c voi dong c6 d(> cCing cao, hgp kim nay c6 d(> cCing va sCic ben doi voi slj mai mon ccJ khf, khong b! dfnh trong thai gian lam vi$c c6 tu6i th9 cao d- gc dung cJ cac tiep diem c6 ap suat can thiet.
- Molipaen: b! an mon Ion hcJn wonfam bl an mon m9nh cJ nhi$t d(> tren 600°C. Oxyt molipden t9o nen xop khong dan di$n nen khong dung molipden 600°C. Oxyt molipden t9o nen xop khong dan di$n nen khong dung molipden nguyen chat ma su dl}ng hgp kim wonfam voi molipden cJ nhCrng may cat di$n trong chan khong, trong khf trcJ.