WC-Ni Composite Powders Prepared By Electroless Plating With Simplified Pretreatment And Its Sintering Characterization

As technology development, hard metals are facing new challenge in the application, which requires the higher hardness and higher strength. Sometimes, excellent oxidation resistance and corrosion resistance will be also necessary. While WC-Co alloys as a typical hard metals perform a poor oxidation resistance and corrosion resistance. A novel hard metal material with higher hardness, higher strength and special properties attracts the attention of scholars. Ni is one of the best candidate materials for Co which shows good wettability, good chemical stability, better plasticity, and lower cost. In this paper, WC-Ni composite are prepared by electroless plating assisted with a novel pretreatment and subsequent powder metallurgy. The effects of Ni contents on the microstructure and growth mechanism are discussed. Results show the WC powders perform a good activity with a novel pretreatment, after direct electroless plating of different composition; the Ni coating are all uniform and dense. When the Ni contents between0-3%in the WC-Ni alloys, the specimen shows a rapid promoting. As contents of Ni further increased, the specimen also shows an increasing trend but with a lower rate. The microhardness of WC-Ni alloys is decreasing with rising of the Ni contents. Comprehensive analysis shows WC-3%Ni posses the best properties. And the EDS scanning also reveals the WC-3%Ni alloys have the most uniform tissue distribution. The fracture morphologies of WC-Ni alloys indicate WC-0%Ni alloy is broken with intergranular fracture, while the WC-3%Ni alloy is broken with a mix of partial transgranular fracture of W grains and tearing of Ni plaiting. And the WC-9%Ni alloy shows complete transgranular fracture of W grains with thickening of the nickel layer which lead to a more difficult tensile deformation and tearing.