Tungsten Copper Contact HIP Process (2/2)

Before HIP process, tungsten powder mixed with a certain amount of copper, cold isostatic pressing, low temperature pre-sintered to give semi-finished copper by infiltration. It uses argon (Ar) as pressure transmission medium, temperature control (tungsten-rhenium thermocouple measurement), pressure, dwell time and other relevant parameters, before and after the HIP process copper tungsten contact material hardness, density, bending strength and conductivity of comparative measurements. The density uses conventional Archimedes drainage method; the hardness uses Rockwell hardness HRB and refers to Brinell hardness HB; flexural strength is measured by GB electrical contact material basic performance; electrical conductivity is measured by eddy current conductivity tester.

The experimental result shows that HIP densification mechanism of tungsten copper contacts is similar to the cast alloy, which removes internal defects by deformation - closed - diffusion under high temperature and high pressure and achieves completely densification. Therefore, it requires after-infiltrated material should have good closure, all internal defects, osteoporosis and so can not in communication with the outer surface. If all the defects can not be guaranteed enclosed inside the blank in the process of infiltration, the density after HIP process changes little, even no change. In addition, HIP treatment effect is also related to the content of copper. When the HIP temperature reaches a temperature close to the melting point of copper, its surface will be leaking copper beads phenomenon. Overall, HIP process can promote tungsten copper contact completely densification, which remarkably improves the mechanical and physical properties, and effectively solves dispersion and reliability.

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