Brazing technology of ceramic-Kovar alloy for high-temperature service

In view of the brazing challenge of ceramics and Kovar alloys under high-temperature service conditions, gold-nickel brazing filler metal with superior high-temperature resistance, which replaced the silver-copper-titanium brazing filler metal used in traditional studies, was adopted for the brazing of alumina ceramics and Kovar alloys. In addition, the effects of different brazing temperatures on the shear strength of alumina ceramic-Kovar alloy brazed joints were investigated, and the correlation among brazing temperature, joint microstructure, and shear fracture position was analyzed. The results show that when the brazing temperature is 1 000 ℃, and the holding time is 10 min, the shear strength of the brazed joint reaches a maximum of 124.8 MPa. At 450 ℃, the shear strength of the joint decreases to 38.5% of its room-temperature strength, and at 550 ℃, its shear strength remains above 35 MPa, which is approximately 21.5% lower than that at 450 ℃. The research results provided an important theoretical basis and process parameter reference for the engineering application of ceramic-metal joining technology in high-temperature environments.