Contact electrode material for vacuum interrupter and method of manufacturing the same

摘要

A novel contact electrode material for vacuum interrupters is disclosed, by which the chopping current value inherent in contact material can be reduced so that it is possible to stably interrupt small lagging current due to inductive loads without generating surge voltages. The material is equivalent or superior to the conventional Cu-0.5Bi material in large current interrupting capability and dielectric strength. The material consists essentially of copper, chromium, iron or molybdenum and chromium carbide or molybdenum carbide. The metallographical microstructure is such that copper is infiltrated into a porous matrix formed by mutually bonding chromium powder, iron or molybdenum powder and metal carbide powder in diffusion state. In its manufacturing process, firstly copper is placed onto a powder mixture of chromium, iron or molybdenum, and chromium carbide or molybdenum carbide, and then the copper and the powder mixture is heated within a nonoxidizing atmosphere at a first temperature lower than the copper melting point and thereafter again at a second temperature higher than the copper melting point.