The formation of tungsten and tungsten carbides by CVD synthesis and the proposed mechanism of chemical transformations and crystallization processes

•Low temperature chemical vapor deposition of tungsten and tungsten carbides.•The high microhardness of tungsten coatings caused by carbon supersaturation.•The proposed mechanism of the synthesis of tungsten-carbon compounds. Tungsten (α-W and β-W modifications) and various tungsten carbides (W2C, WC1−x, WC) coatings were formed by chemical vapor deposition (CVD) in WF6, C3H8, H2 gas reactions. The structure of reaction products was studied by transmission electron microscopy and X-ray diffraction. The microhardness of coatings was determined by Vickers method. The mechanism of the CVD process is proposed to explain the formation of W or various (W-C) coatings and the variety of grain sizes in corresponding deposits.