Fabrication and use of Cu-Cr-diamond composites for the application in deep feed grinding of tungsten carbide

Abstract

Machining of tungsten carbide requires the use of highly wear resistant grinding tools, like metal bonded grinding tools. The abrasive layer of these grinding tools can be regarded as Metal-Matrix-Composites reinforced with diamond particles. Copper-Matrix-Composites already are being used as heat sink materials through their outstanding high thermal conductivity. In this work, Cu/Diamond composites with 50 vol% diamond have been fabricated through field assisted sintering and the application of these composites as grinding layers in a deep feed grinding process of tungsten carbide was investigated. Through addition of chromium powder as a carbide former on the surface of the diamond particles, the critical bond strength and therefore the diamond grain retention was significantly increased by +363%. The addition of 2 wt% chromium to the copper matrix also resulted in a +84% increase of thermal conductivity relatively to the chromium free Cu/Diamond composite. Grinding of tungsten carbide as a dynamic stress test showed that the increased grain retention and thermal conductivity resulted in a decrease in grinding layer wear. Further chromium addition to 8 wt% chromium resulted in a decrease in thermal conductivity and the formation of adhesive cloggings on the grinding wheel surface during grinding.