Study On Sintering Of Titanium And Diamond - Cemented Carbide Composite By Microwave Heating Diamond

Diamond-cemented carbide composites combines the high hardness, high wear resistance of diamond and high heat resistance, high toughness of cemented carbide, are used widely in drilling, cutting, grinding and so on. It has important theoretical and practical value for the research of preparing diamond-cemented carbide composites by new technology. In addition, high interfacial energy exists between diamond and metal matrix, resulting in the poor interface binding. To plate strong carbide-forming elements onto diamond surface is a good way to improve the interfacial bonding strength between diamond and metal matrix. Microwave heating has the advantages of clean, high efficiency, energy saving, environmental protection and so on, and has been widely used in the material preparation field. In this paper, microwave heating was applied in the diamond surface titanium plating and diamond-cemented carbide composites sintering, and several researches in the following areas were carried out.(1) The research on plating titanium on diamond surface by microwave heating was carried out. The morphology, coating structure, coating thickness, binding properties between coating and diamond matrix, heat resistance properties of Ti-coated diamond were measured and analyzed. The results show that a uniform, continuous, and compact coating was obtained by microwave heating method. The phase of TiC was formed, with the increase of temperature, the content of TiC and Ti was increased, and the coating thickness also increased gradually. The interfacial bonding ability between coating and diamond first increased with temperature increasing, and then decreased. The better coating temperature was 760 ℃, and the better ratio of diamond to titanium hydride was 1:0.6. The thermal stability of Ti-coated diamond was improved.(2) A comparative study of sintering diamond-cemented carbide composites by microwave heating and conventional heating was carried out. The results show that microwave sintering could shorten the sintering time, improve the sintering efficiency. Compared with conventional sintered samples, the microstructure of the microwave sintered samples were more uniform, sintering better, burning lighter, and combining better with matrix. When the mass fraction of the matrix components Co, Ni, WC, Cu were 70%,10%,5% and 15% respectively, adding diamond of 25 vol%, and sintering at 1000℃ for 1h, the hardness of microwave sintered samples was 75.33 (HRA), relative density was 95.85%, which was higher than the hardness (69.58) and relative density (87.28%) of conventional sinteried sample.(3) The research on sintering un-coated/Ti-coated diamond-cemented carbide composites by microwave hot pressing method was carried out. The microstructure, density, hardness and bending strength of the materials were measured and analyzed. Studying on the influence of sintering temperature, holding time, sintering pressure on the microstructure and properties of the materials, the results show that diamond particles distributed in the matrix uniformly, and Ti-coated diamond combinated with matrix better than un-coated diamond. The density and hardness of composites increased with temperature and holding time increasing, finally became flattening. Flexural strength of the composites first increased with temperature and holding time increasing, then decreased, and increased gradually with the sintering pressure increasing. Comprehensive analysis, the suitable sintering process parameters are sintering temperature of 1050 ℃, holding time of 4min, sintering pressure of 40MPa.