Effects of heat treatment on the microstructure of amorphous boron carbide coating deposited on graphite substrates by chemical vapor deposition |
| |
| Authors: | Siwei Li Bin Zeng Zude Feng Yongsheng Liu Wenbin Yang laifei Cheng Litong Zhang |
| |
| Affiliation: | 1. Fujian Key Laboratory of Advanced Materials, College of Materials, Xiamen University, Xiamen, 361005, China;2. National Key Laboratory of Thermostructure Composite Materials, Northwestern Polytechnical University, Xi''an 710072, China;1. State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China;2. Shandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209, China;1. State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China;2. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China;3. State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China;1. R&D Centre for Low-Cost Plasma and Nanotechnology Surface Modification, Masaryk University, Kotlá?ská 267/2, 611 37 Brno, Czech Republic;2. Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská dolina, 842 4 Bratislava, Slovakia;3. ASTRaL team, Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli, Finland;1. Department of Materials Engineering, Isfahan University of Technology, P.O. Box 84156-83111, Isfahan, Iran;2. Department of Mechanical Engineering, K.N.Toosi University of Technology, P.O. Box 19395-1999, Tehran, Iran;3. Department of Material and Metallurgy Engineering, Iran University of Industries and Mines (IUIM), Tehran, Iran |
| |
| Abstract: | A two-layer boron carbide coating is deposited on a graphite substrate by chemical vapor deposition from a CH4/BCl3/H2 precursor mixture at a low temperature of 950 °C and a reduced pressure of 10 KPa. Coated substrates are annealed at 1600 °C, 1700 °C, 1800 °C, 1900 °C and 2000 °C in high purity argon for 2 h, respectively. Structural evolution of the coatings is explored by electron microscopy and spectroscopy. Results demonstrate that the as-deposited coating is composed of pyrolytic carbon and amorphous boron carbide. A composition gradient of B and C is induced in each deposition. After annealing, B4C crystallites precipitate out of the amorphous boron carbide and grow to several hundreds nanometers by receiving B and C from boron-doped pyrolytic carbon. Energy-dispersive spectroscopy proves that the crystallization is controlled by element diffusion activated by high temperature annealing, after that a larger concentration gradient of B and C is induced in the coating. Quantified Raman spectrum identifies a graphitization enhancement of pyrolytic carbon. Transmission electron microscopy exhibits an epitaxial growth of B4C at layer/layer interface of the annealed coatings. Mechanism concerning the structural evolution on the basis of the experimental results is proposed. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
