Research on Micro-hole Drilling of SiCf/SiC CMCs Via Ultrasonic Vibration Based on Prefabricated Holes
SiCf/SiC ceramic matrix composites are typical hard and brittle difficult-to-machine materials.To solve the problems of machining micro-holes(<1 mm)in SiCf/SiC ceramic matrix composites,improve the machining accuracy and quality,pulse laser is first used to prefabricate SiCf/SiC micro-holes,and then ultrasonic vibration assisted drilling experiments of Φ0.5 mm micro-holes in SiCf/SiC ceramic matrix composites are carried out under different prefabricated hole sizes and machining parameters to determine the appropriate laser prefabricated hole size and ultrasonic vibration assisted drilling parameter domain.The results show that the defects such as large heat-affected zone and micro-cracks in pulse laser processing of prefabricated holes can significantly affect the quality of the inlet and outlet of micro-holes drilled by the subsequent ultrasonic-assisted drilling,the prefabricated hole size is recommended to be Φ0.3 mm.When using ultrasonic vibration assisted drilling,selecting a spindle speed of 11 000～15 000 r/min and a feed rate of 2～10 mm/min can obtain SiCf/SiC ceramic matrix composites micro-holes with good machining quality.
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