Gaseous boronizing pretreatment for the deposition of nanocrystalline diamond films on cemented carbide substrates

A simple and efficient method-vacuum heat treatment gaseous boronizing was proposed to pretreat the YG6X cemented carbides for maintaining its toughness and strength of the pretreated cemented carbide, and promising for mass production. After this pretreatment, the substrate surface remained clean, and the nanocrystalline diamond (NCD) films were deposited on the pretreated cemented carbide by hot filament chemical vapor deposition (HFCVD) with methane, hydrogen and argon as reaction gases. The morphology, structure, roughness and film-substrate adhesion strength of the cemented carbide substrate and the diamond films were analyzed by x-ray diffraction (XRD), scanning electron microscopy (SEM), micro-Raman spectroscopy and adhesion performance test. The results show that this method of gaseous boronizing is stable and feasible. The boride layer with high temperature stability can be formed. The microhardness of the cemented carbide surface after boronizing treatment was increased by 18% compared with that of the original untreated one. The comprehensive treatment of the alkali etching followed by boronizing is more effective to improve the film-substrate adhesion performance than the two-step chemical etching pretreatment.