Residual carbon in CuCr contact materials

The role of carbothermic reduction in making low oxygen CuCr contact materials with high oxygen Cr powder is summarized. Experimental results show that with the help of carbothermic reduction, the total oxygen in Cu50/Cr50 alloys made from high oxygen Cr powder (up to 5000 p.p.m.) is less than 100 p.p.m.. The influence of residual carbon in the CuCr alloys on their dielectric strength and antiwelding property is studied. It is concluded that: (1) carbothermic reduction is a very useful method to make low oxygen CuCr contact materials with high oxygen Cr powder; (2) the effect of carbothermic reduction depends mainly on sintering temperature and Cr particle size; (3) carbon exists as Cr₂₃C₆ carbide in CuCr; (4) 1.8-wt.% C in CuCr alloys will increase dielectric strength of the alloys at high temperature; (5) 1 .8-wt.% C in CuCr alloys will much improve the antiwelding property of the alloys