Metallization of diamond surface by laser brazing with Ni-Cr alloy filler

In order to study the types and formation mechanism of metallization products on diamond abrasive surface by laser brazing, the first-principle density functional theory was used to calculate the common carbides. Laser brazing experiments of diamond abrasives were carried out by means of Ni-Cr alloy filler metal and optical fiber laser heat source. The structure and mechanical properties of Cr₃C₂ and Cr₇C₃ carbides, as well as surface microstructures and carbide species of diamond abrasives, were obtained. The results show that both Cr₃C₂ and Cr₇C₃ are metallic, and the latter is tougher. The thickness of metallurgical reaction layer between diamond abrasives and Ni-Cr alloy brazing filler metal obtained by laser brazing is about 4μm. The surface carbides of diamond abrasives are mainly Cr₃C₂. The surface carbides of diamond abrasives obtained by ultrasonic-assisted laser brazing are Cr₃C₂ and Cr₇C₃. Ultrasound high frequency vibration can promote interfacial reaction, and then produce Cr₇C₃ with low carbon content. The research results have guiding significance for the development of laser brazing diamond technology.