Wear resistance enhancement of bimodal-grained cemented carbide coating

A new type of bimodal-grained WC-Co cemented carbide coating was fabricated, using the raw materials consisting of the in situ synthesized nanoscale WC-Co composite powder as major component and a certain amount of ultra-coarse WC particles as addition. The effects of coarse WC particles on the microstructure, mechanical properties and wear behaviour of the coating were investigated. It was found that with a suitable addition of coarse WC particles, the coating has a decreased decarburization and significantly increased wear resistance, as compared with the coating without the addition. The coarse WC particles allow a certain degree of plastic deformation by dislocation gliding so that under wearing conditions some stress concentration can be released and their fractures are inhibited. A good combination of coarse WC particles and WC-Co nanocomposite facilitates high properties of the coating, with the former mainly bearing the load and resisting against penetration of the wear debris, and the latter providing high hardness and also plastic accommodation in the wearing process.