Micro-structuring silicon compound ceramics using nanosecond pulsed laser assisted by hydrothermal reaction

In the machining of silicon compound ceramic materials via laser beam, processing in water has been found to enhance machining quality, while processing in air has limitations such as the generation of a recast layer, heat affected zone, and thermal crack. However, few studies have investigated the effects of water on the ablation rate of silicon compound ceramics. In this research, the ablation behavior and machining principles of the laser beam machining of silicon compound ceramics in water are investigated. The research concluded that the increase in temperature induced by laser irradiation promotes hydrothermal reaction between the silicon compound ceramics and water. The hydrothermal reaction assists in the removal of the oxide layer at the machined area and enhances the efficiency of the process in water. The effects of water on ablation are confirmed for various machining parameters such as the flow rate of sprayed water on the workpiece and laser conditions. Finally, the various micro-structures were fabricated on the silicon compound ceramics to evaluate the processability.