Ultrasonic Brazing of Alumina to Copper Using Zn-Al-Cu Fillers(Materials, Metallugy & Weldability)
Ultasonic Brazing was applied to join to coopper using Zn-Al-Cu filler metals containing Al plus Cu content up to 30 mass% where the ratio of Al/Cu is fixed as 3/2. 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-Cu filler bath. Then, the metallized Al_2O_3 was brazed with Cu using the same fillers. The increase in application time of ultrasound and metallizing temperature raises the joinig strength of Al_2O_3/Zn-Al-Cu/Cu joint. The joining strength of Al_2O_3/Cu joint exhibits the maximum at Al+Cu content of 20 mass% in Zn-Al filler, and loweres with further addition of Al+Cu 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-Cu filler against alumina, and increasing the joining strength of Al_2O_3/Cu joint.
- Transactions of JWRI
Transactions of JWRI 20 (1), 91-96, 1991-06