Microstructure and growth behavior of Hf(Ta)C ceramic coating synthesized by low pressure chemical vapor deposition

Hf(Ta)C ceramic coating was synthesized on graphite by low pressure chemical vapor deposition with gaseous mixtures of hafnium halide, tantalum halide, methane, hydrogen and argon. The phase composition and microstructure of as-prepared coating were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM). The growth behavior of coating was also discussed. Results show that the as-prepared coating is composed of nano-sized Hf0.7Ta0.3C solid solution and rare of carbon. The Hf(Ta) C coating exhibits a nanocomposite structure with Hf0.7Ta0.3C grains embedding in amorphous carbon, which can be contributed to the rapid nucleation of Hf1-xTaxC, as well as the inhibition of carbon in the growth of Hf1-xTaxC grains. (C) 2017 Elsevier B.V. All rights reserved.