Formation Mechanism and Properties of Thickness-Controllable Tungsten Coating on Diamond Surface by Salt Bath Plating

Abstract

The fabrication of porous diamond preforms is a key step for obtain diamond/metal copposites with high proporties by liquid infiltration. In order to prepare porous diamond preforms with high strength and excellent compatibility with liquid metal. The diamond metallization should be treated first usually.In this paper, the microstructure, composition, phase structure and bond strength of tungsten coating on diamond surface by using salt-bath method were observed and analyzed experimentally including scanning electron microscope (SEM), energy spectrometer analysis (EDS), X-ray diffraction (XRD). The results show that tungsten start to react with carbon atoms on the surface of diamond at 1100°C while a dense and completely covered coating can be obtained at the temperature of 1150°C with 10-120 minutes dwell time. With this process, the layer on diamond surface can be regulated in the range of 1.18 to 3.24μm. The phase structure of coating from outside to inside is W, W2C and WC phase, respectively. Thermal shock experiments also show that the coatings on diamond surface have excellent bond strength as well as high temperature resistance.