Effect of SiC Nanowires on Microstructures and Properties of Ni-Cr-P Filler Metal and Ni-Cr-P/Q235 Brazed Joints

SiC nanowires with excellent high temperature strength, high thermal conductivity, high wear resistance, and high corrosion resistance were adopted as additive into the Ni-Cr-P filler metal. The microstructures and properties of filler metal/brazed joints were studied. Results show that the microstructure of filler metal is composed of Ni(Cr) solid solution, Ni3P intermetallic compound phase, and Ni(Cr) +Ni3P eutectic structure. A small amount of SiC nanowire can refine the matrix microstructure and improve the shear strength of brazed joints by 29.6%. The addition of SiC nanowire can increase the melting temperature of filler metal by about 4 degrees C and significantly enhance the wettability of filler metals on steel substrate by 12.5%. However, excessive addition of SiC nanowire can significantly coarsen the matrix microstructure, reduce the wettability of filler metal, and decrease the shear strength of brazed joints. Among the Ni-Cr-P filler metals with different SiC contents, Ni-Cr-P-0.1SiC filler metal/brazed joint shows the obvious superiority.