Joining Strength and Microstructure of Sintered SiC/SiC Joints Prepared by Active Brazing Process

Abstract

Sintered SiC ceramics were brazed with itself by ternary Ag-Cu-Ti filler metal foil.Effects of brazing parameters such as temperature,holding time on joining strength,together with interface microstructure and reaction products were investigated.Experimental results indicate that joining strength has peak value with the increasing of brazing temperature and holding time,and the max four-point bending strength of SiC/SiC joints reaches 342MPa.The joining strength increases first with the increasing of brazing temperature and holding time due to thickening of the reaction layer,then decreases due to evaporation of the filler metal.A uniform compact reaction layer of about 1μm thickness is found at the interface between SiC and filler metal,which is formed by the reaction of active element Ti of filler metal and SiC substrate.TiC and Ti5Si3 are confirmed as the reactive products by XRD and EDX.