Effect Of Brazing Alloying Elements On Microstructure And Property Of Brazing Diamond

Diamond has high hardness, good wear resistance, good thermal stability, excellent thermalconductivity. High-temperature brazing diamond, diamond and some transition elements (such asCr, Ti, W and so on) reacted chemical reactions to produce carbides, and diamond, brazing alloyand matrix achieved a combination of chemical and metallurgical solid through the effect of thecarbide layer. That is to say, the interaction of dissolution, infiltration, diffusion and chemicalcombination between the three of them, therefore, they can fundamentally increase the retentionthat matrix and the filler alloy for the diamond abrasive. The brazed diamond tools has thefollowing characteristics: the largest protrusion value of diamond up to2/3of the particle size,abrasive dust have a capacity of a large space, high cutting efficiency and long tool life and so on,and they are applied extensively in geological survey and stone grinding processing industries.However, nickel-base brazing diamond tools of the market that commonly used are abrasiveprotrusion difficult problem in the process of machining. The paper used Ni-Cr alloy with Cupowder, Ni-Cr alloy add Cu-P-Sn alloy and CuNiSnTi powder brazing diamond in vacuum, andanalysis the effect of brazing alloying elements on microstructure and property of brazing diamondand the performance of brazing alloy, and discusses to reduce the thermal damage of diamond andthe way to improve the self sharpening of brazing layer.The research work in the paper are as follows:1. Brazing diamond in vacuum with Ni-Cr alloy add5%Copper power, and the brazingtemperature was1050℃and keep warm5minutes can be achieved metallurgical bondingbetween brazing alloy and diamond. And flaky carbide Cr3C2and strip carbide Cr7C3generated onthe surface of diamond, and the number of carbide decreased compared with brazing diamond withNi-Cr alloy at1050℃. It forms transition layer of diamond/carbide/solder alloy at the interfacebetween diamond and brazing layer. The matrix of the brazing layer microstructure is γ-Ni solid solution, and compound uniformly distributes on the matrix. The hardness of brazing layer in therange of600～750HV0.3g, it reduced by about20%compared with the hardness of brazing layer ofbrazing diamond with Ni-Cr alloy, it forms gradient transition at the interface between brazinglayer and steel matrix.2. Ni-Cr alloy with5%Cu-P-Sn alloy power was used to brazing diamond in vacuum, andflaky carbide Cr3C2and columnar carbide Cr7C3generated on the surface of diamond at thetemperature of1040℃for5minutes. There was a certain orientation relationship between thegrowth of carbide Cr3C2and the atom arrangement of diamond surface, formed chemical andmetallurgical bond between diamond and brazing alloy. The brazing temperature reduced by10℃compared with brazing diamond with Ni-Cr alloy, and decreased the thermal damage of diamond.The microstructure of brazing layer changed little, and the hardness of brazing layer compared tothe hardness of Ni-Cr alloy brazing diamond reduced.3. Cu70Ni5Sn15Ti10was used to brazing diamond in vacuum at the temperature of1050℃for5minutes, and it is carbide TiC generated on the surface of diamond, and it forms transitionlayer of diamond/TiC/brazing alloy at the interface between diamond and brazing layer. Themicrostructure of brazing layer is a large amount of α-Cu solid solution, Cu-Sn eutectic andcompound distributes on the matrix. The brazing layer hardness of brazing diamond in vacuumwith Cu70Ni5Sn15Ti10in the range of130～180HV0.1g, it is an obvious increase that comparedwith the brazing layer hardness of brazing diamond with CuSn25Ti13alloy.