Joining ZrB2-SiC composites using glass interlayers

A joining technique, based on the use of a glass powder as a bonding interlayer between two ceramic pieces, is tested for a ZrB2-SiC composite. At the bonding temperature, the glass melts, wets the ceramic and flows through the interface driven by the capillary pressure that builds up between the two contacting ceramic surfaces, promoting their adhesion. The behaviour of three glasses is compared: two in the system Ca-Al-Si-O (melting temperatures 1400 and 1210.C) and one in the system Y-Al-Si-O (melting temperature 1440.C). The ceramic-glass interfacial characteristics depend mainly on the temperature, on the composition of the glass and on the phenomena influencing the adhesion, such as the partial dissolution of the ceramic grains when the glass wets them. The 3-point flexural strength values of the joints obtained by the system that resulted with the more homogeneous interface are also reported.