Control interfacial microstructure and improve mechanical properties of TC4-SiO2f/SiO2 joint by AgCuTi with Cu foam as interlayer

Brazing SiO2f/SiO2 ceramics to TC4 is often associated with the problems of excessive Ti from the dissolution of TC4 and high residual stress, which results in low-strength joints. To overcome these problems, here we put forward an effective method by introducing Cu foam as interlayer to obtain high strength joints of SiO2f/SiO2-TC4. The effect of Cu foam on the microstructure and mechanical properties of brazed joints was investigated. Cu foam can consume Ti from TC4 and inhibit forming too many brittle compounds at the SiO2f/SiO2 side. Furthermore, Cu foam can react with Ti, forming the dispersed homogeneous distribution of fine-grained Ti-Cu compounds in the brazing seam, due to its unique 3D porous structure. The formation and distribution of fine-grained Ti-Cu compounds at the brazing seam could significantly help to reduce the residual stress and reinforce the mechanical properties of the joint. Maximum shear strength of 59.6 MPa is approached. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.