Zhang Xuanhua, Chen Xiaoxiao, Chen Tao, Ma Guiying, Zhang Wenwu, Huang Lirong
School of Mechanical and Electrical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China.
Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Zhejiang Provincial Key Laboratory of Aero Engine Extreme Manufacturing Technology, Ningbo 315201, China.
Micromachines (Basel). 2022 Jul 15;13(7):1118. doi: 10.3390/mi13071118.
SiC ceramics have excellent comprehensive properties and are typical hard and brittle materials that are difficult to process and are widely used in many fields. Laser polishing technology has developed into a new surface processing technology, and femtosecond laser polishing has become an important method for the precision machining of hard and brittle materials. In this paper, SiC ceramics were ablated and polished by infrared femtosecond laser, the laser ablation threshold of SiC ceramics was calculated and the influence of pulse energy and defocus amount on the surface morphology, surface roughness, polishing depth and oxidation degree of femtosecond laser polishing of SiC ceramics were investigated. The results show that when the laser repetition frequency = 175 kHz, wavelength = 1064 nm and ablation time = 9 s, the laser ablation threshold of SiC ceramics is 0.355 J/cm. With the increase in pulse energy, the surface roughness first decreased and then increased, and the polishing depth showed an overall upward trend. The change of defocus amount will lead to the change of the laser spot diameter. With the increase of the defocus amount, the laser spot irradiated on the workpiece surface becomes larger, and the laser energy density decreases, which results in the decrease of the laser ablation ability and polishing depth and the increase of the polished surface roughness. Periodic nano-ripple structures appeared on the laser-induced surface. Through Energy Dispersive Spectrometer (EDS) elemental analysis, it was found that there was an oxidation phenomenon in SiC ceramics polished by femtosecond laser in an air environment, and the change of pulse energy and defocus amount had insignificant effects on the degree of oxidation.
碳化硅陶瓷具有优异的综合性能，是典型的难加工硬脆材料，在许多领域有着广泛应用。激光抛光技术已发展成为一种新型表面加工技术，飞秒激光抛光成为硬脆材料精密加工的重要方法。本文采用红外飞秒激光对碳化硅陶瓷进行烧蚀与抛光，计算了碳化硅陶瓷的激光烧蚀阈值，并研究了脉冲能量和离焦量对碳化硅陶瓷飞秒激光抛光表面形貌、表面粗糙度、抛光深度及氧化程度的影响。结果表明，当激光重复频率 = 175kHz、波长 = 1064nm、烧蚀时间 = 9s时，碳化硅陶瓷的激光烧蚀阈值为0.355J/cm²。随着脉冲能量的增加，表面粗糙度先减小后增大，抛光深度总体呈上升趋势。离焦量的变化会导致激光光斑直径改变。随着离焦量增加，照射在工件表面的激光光斑变大，激光能量密度降低，致使激光烧蚀能力和抛光深度减小，抛光表面粗糙度增大。激光作用表面出现周期性纳米波纹结构。通过能谱仪（EDS）元素分析发现，在空气环境中飞秒激光抛光的碳化硅陶瓷存在氧化现象，脉冲能量和离焦量的变化对氧化程度影响不显著。
