Research the characteristics of copper powder and nickel powder in diamond sintering


Sintered diamond grinding wheel almost use bronze and other metal as binder, made of high temperature sintering method, high combination strength, good formability, high temperature resistant, thermal conductivity, good wear resistance, long service life, can bear larger load. Because of the grinding wheel sintering process inevitably exist shrinkage and deformation, so it must be shaping grinding wheel before used, but shaping grinding wheel is difficult. Currently produce wheel rolling shaping method is not only time-consuming, but the particle shedding a lot in dressing process of diamond, wheel dressing itself consumption is very large, plastic precision is low.

Relationship between density and hardness of the sintered body and sintering time and sintering temperature, copper and nickel powder compacts were sintered at different sintering temperature, density of the sintered with longer holding time show a downward trend; under the condition of the same holding time, density of the sintered body decrease with the increase of sintering temperature. Copper nickel powder compacts were sintered at different sintering temperature and holding time, on the diamond mechanical strength, saw blade, sintering temperature, sintering pressure, saw blade sharpness has direct or indirect influence, so it is necessary to study deeply on copper and nickel powders during sintering body and the state.

The interface of sintered body migration model solid materials’ basic factors under high temperature sintering is experimental study of atomic copper powder and nickel powder sintering phase interface and performance can be moved from one position to another position of diffusion in solids, and by the diffusion process control. Interface diffusion is a basic interface process, it includes diffusion, along the surface and interface through the interface atomic diffusion and interfacial mobile and other relevant material transfer and interface. Copper and nickel powder sintering is essentially the interface diffusion and migration process. Movement is an important basis for all kinds of interface changes, changes in alpha phase (solid solution) is in fact the process of the formation of growth interface migration.

The interface migration of metal mixed powder compacts during sintering is actually the result of adjacent grains of atomic motion, the interface migration and atomic movement with opposite direction, the same speed. In the diffusion process, only the nickel atoms into the copper, copper atoms hardly into the nickel, copper particles “eat” nickel particles, particle surface to the nickel particles direction grew up, through further diffusion of atoms, eventually resulting in uniform solid solution, is the vacancy diffusion mechanism. Sinter phase interface migration model and performance discussion, sintered copper powder and nickel powder meet the four conditions of diffusion, namely①the temperature should be high enough; ②the time should be long enough; ③the diffusion of atoms should be solution; ④diffusion should have driving force. That with the increase of sintering temperature, holding time, density and hardness of the sintering body showed a rising trend.

Use the method of solid phase sintering study the performance of copper powder and nickel powder sintering and phase interface migration relationship, draws the following conclusion: solid state sintering of copper and nickel powder, with the increase of the sintering temperature, holding time, the density and hardness decreased. In the sintering of copper powder and nickel powder diffusion process, only the nickel into copper, copper is hardly into the nickel. This is the main reason of sintered density and hardness decreased with the increase of sintering temperature, holding time and the increase of nickel content.