Joining of High Chromium White Cast Irons to Ceramics by Using Active Filler Metal and Aluminum

Effects of reaction layer and brazing temperature on the shear strength of high chromium white cast irons/Al2O3, Si3N4, SiC joints are studied using active filler metal and aluminum. The microstructures and reaction layer in the joints are investigated by scanning electron microscopy and X-ray diffraction. Shear strength of about 180-200 MPa was obtained at high chromium cast irons-Al2O3 and Si3N4 joints brazed at 1123-1173K for 15 min, though the shear strength decreased to 150-160 MPa at 1073K for 15 min. In the case of high chromium white cast irons-SiC joint brazed at 1173-1373K for 5 min, shear strength of about 30-50 MPa. was obtained. Reaction products TiO or TiN were formed in the interface between active filler metal and Al2O3, Si3N4, two compounds (Al3Fe, Al4C3) were formed in the high chromium cast irons-SiC joint brazed with aluminum filler metal. These reaction layer should influence the shear strength of high chromium cast irons-ceramic joints.