Thermal Shock Behavior of the SiC-SiC Joints Joined with Na_2O-B_2O_3-SiO_2 Glass Solder

Water-quenching technique was used to evaluate the thermal shock behavior of the SiC-SiC joints joined with Na 2 O-B 2 O 3-SiO 2 glass solder.The microstructure of the side view of the interface and the fracture surface of the joints after quenching were analyzed.The influence of the quenching temperature and quenching cycles from 150℃ to cool water on the residual strength of the specimens were investigated.At the quenching temperature of 150℃,the residual strength of the joint decreased to(152±28) MPa due to the propagation of the microcracks in the interlayer caused by the thermal residual stress after one thermal cycle.At the quenching temperature from 150℃ to 320℃,the cracks seemed to be in subcritical state,and the residual strength was kept around 140 MPa.When the quenching temperature was increased to 420℃ or higher,the cracks propagation became more serious,and the strength decreased to(32±8) MPa rapidly.Moreover,the residual strength was hardly affected by the quenching cycles from 150℃ to cool water which meant that the joined specimens possesed good thermal shock resistance behavior at this temperature.