Microstructures of laser bonded SiC ceramics with Zr interlayers

Abstract

SiC plates were bonded using a laser beam scanning method. As an interlayer material, a Zr sheet 0.4mm in thickness was used. Joining was performed at room temperature in air under atmospheric pressure. The interfacial microstructures along with their atomic compositions of the Zr/SiC reaction zone were analyzed. In the Zr side, diffused Si formed ZrSi2, Zr5Si3Cx, and Zr4Si phases. Carbide transformation was observed (Zr+C→ZrCx) near the Zr/SiC interface. No crystallographic orientation relationship was found in most of the grains; however, a boundary of ZrSi2 [100] parallel to Zr5Si3Cx[011¯1] was found in the observation. In the SiC side, penetrated Zr was found at up to 120μm from the Zr/SiC interface. The diffused Zr formed a silicon-rich metastable phase of ZrSiy (y>3.3).