Interface adhesion and shear strength of ZrB₂-SiC ultra-high temperature ceramic brazed with novel amorphous brazing flux

Two pieces of ZrB₂-SiC ultra-high temperature ceramic (UHTC), were jointed by blazing with a novel flux of amorphous Cu_39.37Ti_32.19Zr_19.38Ni_9.06(at%) foil. The impact of the blazing conditions, including the brazing temperature and time, thickness and contents of reaction layer, on the microstructures, interface adhesion, shear strength, and wettability was investigated with X-ray diffraction, scanning electron microscopy and conventional mechanical probes. The results show that at a given brazing temperature, the brazing time and reaction layer thickness significantly affect the brazing. For example, as the brazing time increased, the shear strength at the joint decreased, accompanied by emerging cracks; blazed at 1183 K for 30 min, the highest shear strength at the interface reached 160 MPa, depending strongly on the reaction layer thickness; and the liquid brazing-flux displayed excellent wettability on ZrB₂-SiC surfaces. In addition, the activation energy Q and growth rate of the reaction layer were theoretically evaluated to understand the blazing mechanism.