Reaction–diffusion bonding of CVD SiC using CrAl thin coating layer

Abstract

A new reaction-diffusion bonding method using a CrAl thin coating interlayer was proposed for joining chemical vapor deposition (CVD) SiC. The 180 nm CrAl-coated CVD SiC plates were joined under high-temperature heat treatment and 0.1 MPa external pressure for 4 h. Partially direct joining at 1700 °C and direct joining of a large portion of the joint at 1800 °C were achieved with the remaining CrSi 2 particles around the joint and some carbon phases in the joint. A thin CrAl layer reacted with and diffused into SiC during the joining process. Grain boundary migration in the direct joining area was observed via the transmission electron microscopy microstructure analysis. The joining shear strength of the specimen bonded at 1800 °C is very high (82.5 MPa) despite some weak carbon phase in the joint. The proposed joining method could potentially be applied to the joining of the SiC cladding and end-cap.