| Polycrystalline Diamond (PCD) as a substitute for diamond, has solved a lot of problems, such as the rare number of natural diamond, expensive problems, so that the application of diamond tools extended to many fields, and more attention has been paid.PCD has series of advantages of single crystal, but there are still shortcomings in the heat resistance, oxidation resistance, chemical inertness and so on. If the diamond surface coated with a layer of metal, the diamond can be a good infiltration of the metal or alloy, Under HPHT, chemical reaction will exsit between diamond and coating metal or alloy elements, to form a chemical combination of the polycrystalline and make a great improved in the heat resistance, oxidation resistance and so on , so that the life and performance of tools improve.Diamond coating has been applied in the tool, most studies on the diamond coating is the interface between the diamond and metal, but the synthesis of diamond body material has been reported rarely, therefore, it is significance to study on the preparation of body materials with metal-coated diamond.In this paper, as a guide to solvent theory, in the 4.9~5.8GPa, 1200~1500℃temperature conditions, using nickel-based alloys as sintering catalyst, the Diamond-TiC composite superhard materials were successfully sintered through the re-growth of diamond powder particles. According to density test, wear test and scanning electron microscopy (SEM),the influence of the various factors on the growth of Diamond-TiC composite superhard materials were researched.The synthesis temperature, synthesis time, the powder particle size and the role of catalyst in the synthesis have also studied. The main results were as below:①The density of Diamond-TiC composite superhard materials increased with the pressure improving, and have better dense; the average density of 400 mesh Diamond-TiC composite superhard materials is 3.731g/cm3, slightly higher than normal PCD; in the experimental pressure range, the wear of Diamond-TiC composite superhard materials increase with the rise of pressure.②When the sintering temperature is too low, the surface layer of titanium is not melting, the diamond powder bonded together by metal; while the temperature is too high, graphitization of diamond occures. Both of them affect the wear resistance of Diamond-TiC composite superhard materials, so the synthesis temperature should be strictly controlled.③The time of prepare Diamond-TiC composite superhard materials is longer than normal PCD. If the time is too short, titanium layer is not fully melted, and if the time is too long, it is easily lead to the production of graphite, both made the wear ratio of Diamond-TiC composite superhard materials decreases.④By preparation of 1600 mesh and 400 mesh Diamond-TiC composite superhard materials, we found that the smaller the powder particle size, the higher the wear resistance of sintered samples; the average density of 1600 mesh Diamond-TiC composite superhard materials is 3.805g/cm3, a little more than 400 mesh powder samples; the smaller the powder particle size, the slower the infiltration rate.⑤In the absence of metal catalyst additive case, under lab environment, D-D sintering can not be realized. And on the basis of the above, according to X-ray diffraction (XRD) and Raman spectroscopy (Raman) , we have a further study about Diamond-TiC composite superhard materials.The result show that NiMnCo,TixCy and TiMnC diffraction peaks are existed in the XRD of Diamond-TiC composite superhard materials and surface residual stress are a little bigger in Diamond-TiC composite superhard materials than that in normal one on the basis of Raman spectra. XRD diffraction shows that two processes occour during sintering under HPHT. There is a certain residual stress in the surface of Diamond-TiC composite superhard materials, and the stress values is higher in the center than in the edge. when 30min, in the edges of the samples appeared the characteristic peaks of graphite.
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