CVD Diamond Films on WC-Co with a Vanadium Carbide Thermal Diffusion Layer

CVD diamond film deposition on WC-Co substrate is the most likely application of diamond CVD technology towards large scale production, due to its suitability to aluminium alloys machining in the automotive and aerospace industry. Several film-substrate interfaces and surface modifications have been developed aiming higher levels of simultaneous diamond film-substrate adherence and substrate surface toughness, however the results are still far bellow industry requirements for widen scale application.

In this work a new interface is introduced in the CVD diamond films technology, which consists of a thermo-reactive deposited and diffused vanadium carbide layer, highly adequate to diamond films deposition on cemented carbide cutting and forming tools. This interface presents good diamond growth characteristics, thermal expansion coefficient similar to the substrate and, in addition, high hardness and mechanical strength. Diamond films quality and interface characteristics are evaluated by SEM images and linescan technique, X ray diffraction and Raman spectroscopy. A typical Raman shift of 4,1 cm⁻¹ is obtained observed, corresponding to a compressive residual stresses of 1,4 GPa applied from the substrate to the CVD diamond film through vanadium carbide interface.