Improvement to the adhesion of polycrystalline diamond films on WC-Co cemented carbides through ion etching of loosely bound growth centers

Carbide cutting tools with CVD diamond coatings are one of the most promising combinations for machining applications because of their exceptional durability in the processing of hard-to-treat materials. In the current work, we investigated a new technique to increase diamond coating adhesion to WC-Co substrates, based on the principle of removing loosely bound nanodiamond growth centers (the cause of regions with low adhesion for the growing coating) from the substrate surface using ion etching. As a result, well-adherent coatings were obtained with a columnar microstructure and thickness up to 40 μm. We also investigated the evolution of density variation of the growth centers for various ion fluxes and exposure time. The difference in mechanisms of diamond coating delamination from substrates without ion etching pretreatment and after pretreatment was also examined. Comparative measurements of coating adhesion by the Rockwell adhesion testing methods and determinations of the self-detachment thickness were made. The relative simplicity, low energy consumption and high efficiency of this method make it attractive for both industrial and scientific applications.