Deposition and characterization of diamond coatings on WC-Co cutting tools with W/Al interlayer

A new double interlayer W/Al was developed for chemical vapor deposition (CVD) of diamond coatings on cemented WC-Co cutting tools to enhance diamond nucleation and adhesion. A thin layer of Al directly deposited on WC-Co is used to suppress the interfacial graphitization induced by Co and an additional thin layer of W is used to enhance diamond nucleation. The microstructure and adhesion of diamond coatings grown on the W/Al/WC-Co and, for comparison, on W/WC-Co as well as bare WC-Co were investigated. The results demonstrate that diamond coatings grown on W/Al are continuous and well adhesive. The advantage of the interlayer includes that nano-crystalline diamond can be achieved even under typical microcrystalline diamond growth conditions. In addition, the W/Al interlayer of overall 50–65 nm thickness would cause marginal lost of cutting edge sharpness and mechanical integrity of coated cutting tools.