Microstructure of in situ MoSi2/SiC Nanocomposite Coating Formedon Mo Substrate by Displacement Reaction

• Published in: Metals and materials international 2005, 11(6), , pp.457-463
• Main Authors: 도정만, 홍경태, 금동화, 김경호, Jin-Kook Yoon
• Format: Article
• Language: Korean
• Subjects: 재료공학
• ISSN: 1598-9623; 2005-4149

The microstructure of an in-situ MoSi2/β-SiC nanocomposite coating formed by the solid-state displacement reactions of Si deposited by chemical vapor deposition (CVD) with Mo-carbide layers at 1100oC, which had previously been formed on the surface of a Mo substrate by a CVD process, was investigated. The Mo-carbide layers formed by the simultaneous CVD of Mo and carbon at 900oC for 5 h using a gas mixture of C2H4- MoCl5-Ar consisted of two layers, an inner layer of Mo2C and an outer layer of MoC. While the monolithic MoSi2 coating showed a typical columnar microstructure perpendicular to the Mo substrate, the MoSi2/β-SiC nanocomposite coating formed by the solid-state displacement reactions between the Mo-carbide layers and Si was composed of equiaxed MoSi2 grains with an average size of 150-500 nm and β-SiC particles with an average size of 80-105 nm. The β-SiC particles exhibited an oblate-spheroidal shape and were located mostly at the grain boundaries of MoSi2. The volume percentage of β-SiC particles ranged from 18.5 to 29.2 % with respect to the carbon concentration in Mo-carbide layers. KCI Citation Count: 6