Brazing of silicon nitride ceramic composite to steel using SiC-particle-reinforced active brazing alloy

Silicon carbide particles have been introduced as reinforcements in a commercially available active metal braze filler alloy (Incusil ABA, Wesgo Metals) used for the joining of ceramic-to-metal. The effect of particle reinforcement of the braze filler on the flexural strength of ceramic to metal joints has been investigated at room temperature and at elevated temperatures. An average four point flexural strength of nearly 400 MPa is achieved at room temperature when using Incusil ABA + 30 vol.% SiC (sandwich foil system) compared to 330 MPa with Incusil ABA alone. At a test temperature of 250 °C relaxation of residual stresses in the joints results in an average flexural strength of approximately 520 MPa when using Incusil ABA + 10 vol.% SiC. These values compare with an average room temperature flexural strength of nearly 800 MPa for the ceramic composite. The reaction products of the braze alloy at the joint interface were identified by SEM.