Mechanism of Ultrasonic Irradiation on Joining of Alumina/Copper

摘要

Ultrasonic waves were applied during the brazing of alumina to copper using Zn-Al alloys as filler metal. The intensity of the ultrasonic wave was 1 kW and 18 kHz, the aim of this work being to study the mechanism of ultrasonic waves during the brazing of alumina and copper. The joining mechanism was investigated by measuring the joining strength and analyzing the microstructure at the interface of the joint. The effect of ultrasound was derived primarily from acoustic cavitations, impact and friction between filler and alumina ceramic. This was to improve the wetting between alumina and the filler, it meant that the percentage of wetted area on the alumina surface increased by increasing the application time of ultrasonic waves and this was reflected in improved joint strength. Another advantage of the ultrasonic method is that it can reduce the joining temperature and so reduce the thermal stress in the braze joint.