Study On Brazing Of SiC_p/Al Composites

The brazing technology of SiCP/ZL101composites in air furnace and argonfurnace were tested by using Al802, N0927and HL2three kinds of Zn-Al flux-coredbrazing filler metals. The brazing technology parameters were optimized. Effect ofparameters of brazing of SiC_p/ZL101composites on the joint shear strength has beenstudied. Moreover, the brazing behaviors of SiC_p/ZL101composites surfacemodification were made a primary research. The microstructure, phase, micro-hardnessof joint region, and the microstructure and composition of fracture have been analyzedby using the equipment of microscope, SEM, XRD, micro-hardness and electronicuniversal testing machine.SiC_p/ZL101composites can be connected by using three kinds of Zn-Al flux-coredbrazing filler metals under the two kinds of experimental conditions. First, the jointshear strength increases with the rising of the brazing temperature and the holding time,then reaches the maximum, after that, the joint shear strength decreases with thetemperature and holding time continuously increase. The micro-hardness of joint isslightly below that of the matrix metal. The results show that the brazing filler metal ofN0927is more suitable for brazing of SiCP/ZL101composites in air furnace, when thetemperature of455℃and25min holding time, the maximum value66.93MPa of brazedjoint shear strength can be attained.The structure of brazed joint is dense. No brazing defects such as gas holes andcrack can be found by microstructure observation. The XRD phase analysis demonstratethat the welding seams have (Al), β(Zn), ZnO and Al2O3phases in air furnace, thewelding seams have only β(Zn) and (Al) two phases in argon furnace. SEM photosshow that the most of lap joints fracture are tough, and located in base material nearbrazing seam. The most butt joints fracture also are tough, failure mechanism for buttjoints is mainly ductility destruction of filler metal.The brazing behaviors of SiC_p/ZL101composites after surface modification in airfurnace were tested. The results show that using brazing filler metal of N0927, at thetemperature of460℃and25min holding time, the value100.05MPa of brazed jointshear strength can be attained, by contrast, the value of brazed joint shear strengthincreases about50%.