飞秒激光加工SiC/SiC复合材料厚板的孔型特征研究

Hole shape characteristics in femtosecond laser drilling of SiC/SiC composite thick plate

为了探究飞秒激光加工SiC/SiC复合材料厚板的孔型特征,采用光束同心圆填充扫描方式对厚度为4mm的SiC/SiC复合材料进行制孔实验,分析了飞秒激光加工参数对入口直径、孔深、锥度等孔型特征的影响规律和影响机理。结果表明,脉冲能量、重复频率、线重合度以及扫描速率对小孔入口直径影响较小,但对孔深和锥度影响较大;上述实验参数与光束扫描面积内的能量密度密切相关,小孔锥度随能量密度增大而减小,小孔深度则反之;当采用最大脉冲能量130μJ、最大重复频率100kHz、最小扫描速率100mm/s、最大线重合度77%以及最小进给量0.1mm时,小孔锥度达到最小值12.38°;上层材料对光束的遮挡以及排屑困难导致深孔加工锥度不易控制。该研究可以为今后SiC/SiC超快激光制孔应用提供参考。

In order to evaluate the hole shape characteristics in femtosecond laser drilling of SiC/SiC composite, an experimental study has been conducted on 4 mm thick specimen using beam concentric scanning mode. The effect of process parameters on entry diameter, hole depth, and hole taper has been analyzed. The results show that pulse energy, pulse frequency, line overlap ratio, and scanning speed have almost no influence on entry diameter. However, these factors significantly affect hole depth and hole taper. The pulse energy, pulse frequency, line overlap ratio, and scanning speed markedly influence energy density per unit area that during scanning of the laser beam. Higher energy density results in lower hole taper and greater hole depth. The experiment reached a minimum taper angle of 12.38° using the maximum pulse energy 130μJ, maximum repetition frequency 100 kHz, minimum scanning speed 100 mm/s, maximum line overlap 77% and minimum feed distance 0.1 mm. It is concluded that the taper angle can hardly be controlled because the upper material will shelter part of the laser beam and there is difficulty to evacuate chips. This study can provide a reference for the future application of ultra-short pulse laser drilling of SiC/SiC composites.