Brazing of SiO2f/SiO2 composite to Invar using a graphene-modified Cu-23Ti braze filler

For the active brazing of ceramic/metal couples, formation of brittle intermetallics in the brazed seam is often a big issue that needs to be addressed. Herein, a novel vertical few-layer graphene (VFG) modified Cu-23Ti braze filler was developed to join the SiO2f/SiO2 composite and the Invar alloy. Microstructures of the wetting interfaces and the SiO2f/SiO2-Cu23Ti-Invar brazed joints with and without the VFG modification were put into comparison. Results show that the formation of intermetallics in the brazed seam are greatly suppressed and the joint strength improves by 2 times after using a VFG-modified Cu-23Ti braze filler. Typical microstructure of the SiO2f/SiO2-Invar joint brazed using a VFG-modified Cu-23Ti braze filler was characterized and the joint formation mechanism was proposed finally.