Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5438895 | Ceramics International | 2017 | 31 Pages |
Abstract
Zirconium carbide (ZrC) coatings were deposited on graphite substrates by chemical vapor deposition from the Zr-Br2-C3H6-H2-Ar system. The influence of total pressure on the growth of ZrC was investigated in the range of 5-60Â kPa. As the total pressure increased, the deposition rate increased evidently, and the preferential orientation of ZrC coatings changed from the (200) plane to the (220) plane. The growth mechanism changed from a mass transport reaction to a surface reaction at the total pressure of 20-40Â kPa. At the total pressure below 20Â kPa, the deposition was dominated by crystal growth, so the coatings were composed of well-faceted pyramidal-shaped crystals growing along the <001> direction. At the total pressure above 60Â kPa, the growth of ZrC coatings was controlled by the nucleation mechanism, so the coatings were cluster-like crystals rapidly growing along the <110> direction. In addition, low pressure was conducive to the formation of near-stoichiometric ZrC without free carbon. These variations of ZrC coatings can mainly be attributed to gas supersaturation and remarkably changed transport diffusion coefficients with increasing total pressure.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Xin Ma, Si'an Chen, Min Mei, Yong Li, Haifeng Hu, Xinbo He, Guangde Li, Xuanhui Qu,