Preparation And Properties Of Diamond/metal Matrix Composite Blocks

With the design of composite and sintering process, the diamond/copper composite and diamond/nickel alloy composite were successfully prepared. The quality of composites was highly improved by redesigning the process. OM and SEM were used to observe the profile of the composite. XRD characterized the micro-structure of the matrix. The distribution of the diamond Particles and the interface was fully detected in sheared the matrix. The wear resistance test was carried with compact mill machine and thermal conductivity test was measured with laser thermal tester. Finally, the effect of interface on the wear resistance and thermal conductivity was deeply investigated.With the analysis of the test, it can be easily drawn that:1. The preparation of the diamond impregnated in copper was carried with processing of 650?, 0.1Pa vacuum and 50MPa pressure. While 50MPa was not adequate to densify the composite, the real density of matrix was much lower than that of ideal density. The copper had 78um diameter which contribute to reduce sinter temperature and fortify the diffusion of particle.2.The preparation of the diamond impregnated in nickel alloy was carried with processing of 850?,0.1 Pa vacuum and 50MPa pressure. The diamond particles bonded to the matrix well. There was macro segregation in the composite when 10wt% diamond particles added into the matrix.3.Sintered at 650?,850? and 950? respectively, the diamond particle had no thermal impair on compressive strength. No graphitization happened to diamond either.4. Both the copper and nickel were well-crystallized during the sintering process. The micro hardness of matrix was efficiently improved when 10?m diamond powder added into the metallic matrix.5.With 300MPa water pressure shearing the composite,52% raw diamond particles were pulled out from the copper matrix while only 25% metallic coated diamond particles were washed out. The metallic coating obviously made for the combination of diamond and matrix. Moreover, only 7% metallic coating diamond particles were off from nickel alloy, which meant that the combination was attributed to the strength of matrix either.6.10 wt% diamond particles impregnated nickel alloy bulk had 1/2 bottom area grinded, and the average abrasive ratio was 1:187.5 wt% diamond particles impregnated nickel alloy bulk had 3/4 bottom area grinded, and the average abrasive ratio was 1:170. Increasing diamond volume benefited the protection of matrix, reduced the grinding area and improved the abrasive ratio.7. Metallic coating process of diamond contributed to the combination of diamond and matrix. The well-bonded interface benefited the thermal conductivity of composite while the well-bonded interface was heterogeneous phase in the composite bulk which held back the transmission of heat. This could explain the thermal conductivity of composite with raw diamond was 136.757W/m·K while the one with coated diamond was 132.332 W/m·K. Raw diamond particles was much better thermal conductivity than that of coated diamond particles.