Effect of SiC powder ratio on interfacial microstructure and mechanical property of CMC /superalloy brazing joint

To reduce the residual stress of SiC_f/SiC composite material (CMC) and superalloy brazing joints, and further improve the mechanical properties of the joints, different ratios of SiC powder and NiCoCrWMoTiHf fillers were mixed to obtain a series of intermediate layers, forming brazing joints with a gradient coefficient of thermal expansion. The analysis of interfacial microstructure of joints shows that when different proportions of SiC powder are added to the filler, there is no significant change in the phase composition of the brazing seam. As the amount of ceramic powder added increases, the precipitation of intermetallic compounds in the solidification zone of the filler increases, and they are mainly distributed on both sides of the filler area. When the mass percentage of SiC ceramics added is 20%, the width of the solidification zone of the filler reaches its maximum value, and a metallurgical bonding layer is formed between the solidification zone of the filler and the reaction layer area, which is beneficial for improving the mechanical properties of the joint. The shear test of 20%SiC ceramic brazing joints shows that the room temperature shear strength reaches 175 MPa, and the average shear strength reaches 120 MPa at 1 100 ℃, confirming the effectiveness of appropriate SiC powder ratio in improving the mechanical properties of brazing joints.