Fabrication of Reliable Joints of Alumina Ceramics by Microwave-Assisted Reactive Brazing Technique

Abstract

Microwave-assisted reactive brazing technique was utilized for joining of alumina ceramics at 950°C and 1050°C for 20 min in argon atmosphere using .5Ti in mass%) paste as the braze alloy. Conventional heating technique was also employed for comparison purpose only. The microwave and conventionally brazed joints were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and Vickers microhardness measurement. X-ray diffraction data showed that the Ti-based compounds were formed at the substrate-filler alloy interfaces of the microwave and conventionally brazed joints. Scanning electron microscopy exhibited the formation of thicker reaction region in the case of joints microwave brazed at higher temperature. Energy dispersive X-ray analysis determined the elemental compositions across the joint cross-section. Vickers microhardness measurements indicated more reliable performance of the joints microwave brazed at lower temperature. Hermiticity of the microwave and conventionally brazed joints was evaluated by Helium leak test and found to be acceptable for actual applications.