The improvement of the self-healing ability of MoSi2 coatings at 900–1200?°C by introducing SiB6 |
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| Affiliation: | 1. State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Fiber Reinforced Light Composite Materials, Carbon/Carbon Composites Research Center, Northwestern Polytechnical University, Xi’an, Shaanxi, 710072, PR China;2. Xi’an Aerospace Chemical Propulsion Factory, Xi’an, 710025, PR China;1. Shaanxi Province Key Laboratory of Fiber Reinforced Light Composites Materials, Northwestern Polytechnical University, Xi''an, Shaanxi 710072, PR China;2. Science and Technology on Combustion, Internal Flow and Thermo-Structure Laboratory, Northwestern Polytechnical University, Xi''an, Shaanxi 710072, PR China;1. School of Materials Science and Engineering, Key Lab of Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072, PR China;2. Research & Development Center of China Academy of Launch Vehicle Technology, Beijing 100076, PR China;1. School of Materials Science and Engineering, Central South University, Changsha, Hunan, 410083, China;2. Center for Mineral Materials, School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, Hunan, China;3. Key Laboratory of Non-ferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha, 410083, China;4. Department of Materials Engineering, Rensselaer Polytechnic Institute, Troy, New York, 12180, USA |
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| Abstract: | The brittleness of MoSi2 ceramic and the thermal mismatch between MoSi2 coating and C / C composite lead to brittle cracking of the coating at 900?1200 °C. This problem has been overcome in this studyby introducing submicron-SiB6 into the coating. The pre-fabricated cracks and a kinetics model of hot-pressed SiB6-MoSi2 ceramic could quantitatively predict the glass growth and crack healing. As expected, enhancing temperature and SiB6 content increased the growth rate of the borosilicate glass and the crack healing ability of MoSi2 ceramic, which was ascribed to the lower oxidation activation energy and larger specific surface area of submicron-SiB6. For the plasma sprayed coating, SiB6 with submicron structure was benefit for cracking inhibition and formation of borosilicate glass during oxidation, reducing the oxygen permeability and the consumption of inner coating. Hence, the 15 % SiB6-MoSi2 coatings raised the protection times to 84 and 120 h at 900 and 1200 °C respectively, presenting favorable oxidation protective performance. |
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| Keywords: | Borosilicate glass Self-healing Oxidation resistance |
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