Paper Title
Characterisation of the Structure of WC–CO Composite Support Layer of Diamond Coatings

The selective cobalt etching which followed the tungsten carbide etching as the chemical pre-treatment of cobalt sintered tungsten carbide hardmetals before CVD diamond deposition was tested. The time dependence of the Co etching and the thickness of the Co-etched layer as the function of treating time were determined by two different methods: a) based on the determination of the mass of dissolved Co and b) by the GD-OES depth profiling of the etched hardmetal surface. The adhesion test, generally used for the classification of the goodness of the coatings, was applied for the characterisation of the treated surface. The method was found applicable for the classification of the treated layers as well. The optimisation of the etched cobalt layer thickness and structure can provide the possibility of the better fixation of the diamond coating on WC– Co composites. Keywords - Diamond deposition, Co-depleted layer, adhesion, Co dissolution, WC-Co composite