Effect of deposition parameters on morphology and composition of chemical vapor deposited ZrC coatings

ZrC coatings were prepared by chemical vapor deposition (CVD) using the ZrCl₄-Ar-CH₄-H₂ system. The effects of the substrate species, deposition temperature and input concentration ratio of CH₄ to ZrCl₄ (C/Zr) on the morphology, composition and phase of the coatings as well as the deposition mechanism of ZrC were studied. The experimental results show that the morphology of the ZrC coatings is insensitive to the substrate species. The morphologies and compositions of the ZrC coatings are significantly influenced by the deposition temperature and the input C/Zr ratio. The morphology of ZrC coating changes from a platelet structure to a fine-grained polycrystalline structure as the temperature increases from 1100°C to 1350°C. As the input C/Zr ratio decreases from 8.5 to 3.5, the coatings morphology changes from a porous structure to a cauliflower structure and then to a glassy structure. The carbon content of the ZrC coatings increases with the temperature and the input C/Zr ratio.