Brazing of SiO2-BN modified with in situ synthesized CNTs to Ti6Al4V alloy by TiZrNiCu brazing alloy

Abstract

Brazing SiO2-BN ceramic to Ti6Al4V is often associated with the problem of brittle continuous phases and high residual stress at the reaction layer of SiO2-BN, inducing low joining strength. To overcome these problems, SiO2-BN ceramic modified with in situ synthesized carbon nanotubes (CNTs) were joined to Ti6Al4V by TiZrNiCu alloy. Results show that CNTs can improve the wettability of TiZrNiCu on SiO2-BN rapidly, and break the continuous reaction layer of SiO2-BN into fine sizes. Residual stress can also be reduced by low CTE of CNTs and fine size phases among reaction layer. The shear strength of SiO2-BN/Ti6Al4V joints with CNTs modified is 35.3 MPa at 970 °C for 10 min, which is 3 times higher than that of the joints without CNTs modified.