| LU Yuan-hang,LUO Fang,HU Xiao-dong,JIANG Rong-jie,SHEN Yi-zhou.Effect of Scanning Distance on Nano SiC Oxidation Resistant Coating Prepared by Laser[J],51(9):395-403 |
| Effect of Scanning Distance on Nano SiC Oxidation Resistant Coating Prepared by Laser |
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| DOI：10.16490/j.cnki.issn.1001-3660.2022.09.042 |
| KeyWord:laser preparation scanning distance SiC coating oxidation resistance |
| Author | Institution |
| LU Yuan-hang |
Hangzhou Chunjiang Valve Corporation, Hangzhou , China;Zhejiang Chunjiang Intelligent Valve Research Institute, Hangzhou , China |
| LUO Fang |
Hangzhou Chunjiang Valve Corporation, Hangzhou , China;Zhejiang Chunjiang Intelligent Valve Research Institute, Hangzhou , China;Zhijiang College, Zhejiang University of Technology, Hangzhou , China;Zhejiang High End Laser Manufacturing Equipment Collaborative Innovation Center, Hangzhou , China |
| HU Xiao-dong |
Zhejiang High End Laser Manufacturing Equipment Collaborative Innovation Center, Hangzhou , China |
| JIANG Rong-jie |
Zhijiang College, Zhejiang University of Technology, Hangzhou , China |
| SHEN Yi-zhou |
Zhijiang College, Zhejiang University of Technology, Hangzhou , China |
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| Abstract: |
| SiC has good physical and chemical compatibility with graphite, which makes it one of the main materials in the research of graphite anti-oxidation coating. Therefore, in order to study the quality and performance of SiC coating on the surface of graphite substrate, this paper proposes a rapid preparation process of high temperature oxidation resistant nano-SiC coating on graphite substrate by laser irradiation, and obtains the best process parameters of preparation of oxidation resistant coating and the method of enhancing oxidation resistance effect by additives through experimental optimization design. In this paper, a 500 W fiber laser with galvanometer was used to convert the micro-SiC coating into nano-SiC coating in an Ar atmosphere protected reaction chamber. The SiC coating was successfully prepared on the surface of graphite substrate. CCD response surface method was used to design the laser power, laser scanning path spacing and laser scanning speed as three factors and three levels experiment. According to the experimental results of high temperature oxidation at 700 ℃ for 1 h, the appropriate laser process parameters were preliminarily determined. The laser power and laser scanning speed determine the laser energy density. The experimental results show that the oxidation weight loss rate of the coating is related to the laser energy density and laser scanning channel spacing. When the laser power is 200 W, the channel spacing is 0.08 mm and the laser scanning speed is 30 mm/s, the oxidation weight loss rate of the coating sample is the lowest. SEM, XRD and TEM were used to analyze the relationship between laser energy density, channel spacing and micro morphology, phase composition and crystal structure of the coating. The results show that the coating is nano-SiC coating. When the laser energy density is 55.56 J/mm2 and the scanning spacing is 0.08 mm, the coating has good surface morphology and no obvious defects. The coating is mainly composed of α-SiC and β-SiC nanocrystals with good crystallinity. When the laser energy density is 55.56 J/mm2, the coating is mainly composed of single crystal structure; when the laser energy density is 83.33 J/mm2, polycrystalline and single crystal structure coexist; when the laser energy density is 111.11 J/mm2, the coating is mainly composed of polycrystalline structure. Through constant temperature oxidation experiments at 650 ℃ and 800 ℃ and 600-850 ℃ The relationship between the laser energy density, the laser scanning path spacing and the oxidation resistance of the coating was studied, and the experimental results were compared with the uncoated graphite samples. It was proved that the prepared nano SiC coating could effectively inhibit the oxidation of graphite matrix in high temperature aerobic environment. At the same time, the failure mechanism of the coating samples in high temperature oxidation was analyzed, and the oxidation experimental results were verified by linear fitting of Arrhenius formula. The results show that the oxidation resistance of the coating is the best when the laser energy density is 55.56 J/mm2 and the scanning distance is 0.08 mm. |
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