Ultrasonic Brazing of Alumina to Copper Using Zn-Al Filler(Materials, Metallurgy & Weldability)
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Ultrasonic brazing was applied to join alumina to copper using Zn-Al filler metals containing Al content up to 15 mass%. The intensity of ultrasound was 1kW and 18kHz. The joining mechanism was investigated by measuring the joining strength and analyzing the microstructure at interface of the joint. First, Al_2O_3 was metallized by applying ultrasound in Zn-Al filler bath. Then, the metallized Al_2O_3 was brazed with Cu using the same Zn-Al fillers. The increase in application time of ultrasound and metallizing temperature raises the joinig strength of Al_2O_3/Zn-Al/Cu joint. The joining strength of Al_2O_3/Cu joint exhibits the maximum at Al content of 5 mass% in Zn-Al filler, and lowers with further addition of Al content. The application of ultrasound during brazing accelerates the removal of bubbles and the reaction at the interface between alumina and filler metal. This gives rise to wetting of Zn-Al filler against alumina, and increasing the joinig strength of Al_2O_3/Cu joint.
- Trans. JWRI
Trans. JWRI 18(1), 75-79, 1989