目的 研究激光的扫描间距对纳米SiC涂层形貌、生长机理和抗氧化涂层的影响。方法 以不同扫描间距的激光辐照制备SiC纳米涂层。分别利用体视显微镜、扫描电镜(SEM)和激光共聚焦显微镜分析涂层表面、截面的三维形貌，研究扫描间距对涂层形貌的影响，探究微米SiC颗粒转变为纳米SiC颗粒的演变及生长机理。用热失重法(TGA)研究试样高温抗氧化性能，包括试样的氧化失重率随温度变化和650、800 ℃两种温度下的恒温抗氧化性能对比分析，并用阿伦尼乌斯线性拟合进行了验证。结果 激光能够促使预置于石墨基体上的微米SiC颗粒在Ar保护下的密闭反应室中转变为纳米SiC颗粒，且涂层主要由结晶度良好的α–SiC、β–SiC纳米晶颗粒组成。当扫描间距为0.08 mm时，形成的涂层表面较为平滑均匀，粗糙度较小，最高处与最低处的高度差仅为135.829 μm，且此间距下，试验活化能值Ea=11.014×10⁴ J/mol最大，抗氧化性能最好。其次试样在600~850 ℃范围内，试样氧化失重率较低，小于8%，其氧化失重率与氧化时间呈现出较好的一次线性的拟合度。结论 激光辐照制备的SiC纳米涂层的形貌、生长机理、高温抗氧化性能随着扫描间距的不同而产生较大变化，表明在激光扫描间距为0.08 mm的条件下所制备的试样涂层表面具有较高的活化能，验证了此参数下制备的涂层的高温抗氧化性能最好，且能够在高温环境中有效降低石墨的氧化失重率。

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.