Research on Ultrasonic-laser Machining Underwater and Its Mechanism for Silicon Nitride Ceramics

Ceramic material has the advantages of high strength, high hardness, high temperature resistance, corrosion resistance, wear resistance and so on, but also has the disadvantage of difficult processing. The thermal model of the underwater laser material removal and the hydrolysis reaction of silicon nitride are studied. Laser etching experiments on silicon nitride under different conditions and different parameters are applied by the combined device of water assisted ultrasonic-laser machining. The depth and surface quality of grooves etched are investigated by the image instrument and the electron microscope, and the composition of the product is detected by the spectrometer in order to discover the mechanism of laser combined processing. Results show that in the process of water are assisted laser machining of silicon nitride, due to the cooling effect of water reduces the effective energy of material removal, and etching depth becomes small. However, surface quality is greatly improved with water, because the zone of action of laser temperature increased hydrolysis of silicon nitride and the water jet flow away silica product. In the approach of water is assisted by ultrasonic-laser machining, ultrasonic vibration increases water convection and particle motion near the material surface, then corrosion rate is improved.