Micro-structure and performance of vacuum consumable arc melting copper chromium contact material

Copper-chromium contact material having 30% to 60 % chromium was prepared using vacuum consumable arc melting technique. The micro-structure and performance of the contact material was investigated. The arc-melted material was solidified into a fine-grained and uniform micro-structure. The type test at a 12 kV/31.5 kA grade showed that the vacuum interrupter made of the arc-melted material switched off a short circuit current 50 times successfully. A post-test examination showed that the arc-eroded surface of the contacts is flat macroscopically A remelted layer of 1.2 to 1.4 mm thickness was formed on the surface. The layer consists of refined Cr-rich dendrites and spheres and shows a brittle fracture morphology locally.