纳米级金刚石微粉复合镀层的摩擦磨损特性研究

Using nano-size materials to produce wear resistance layers on the surface of parts is an advance technology. This technology is paid greatly attention by the advanced countries, and is enthusiastically studied. With the development of nano materials, the nano diamond can be largely produced by the explosion ways. The production are the mixture of diamond, non-crystalline carbon and graphite. About 20~30% of the mixture are diamond, their diameter are less than 10nm. After acid picking, the purity of the nano diamond powder is more than 90%. The grain sizes of diamonds are about 4~6nm. This technology provides an important foundation for the use of nano diamond..At before, because the limited of materials, the micron-size diamond, carborundum and nitrorundum are used in the complex plating. It is very difficult to implement the technology. There are three reasons.(1) the assembling of grains, (2) the sinking of grains, (3) the peeling off of the plating layers. In this project, the special complex plating equipment and diamond powder are imported from Russian. We plate (melt) Cr (Ni) nano diamond complex plating layers on the surface of six types materials and machine parts. The layers are carefully studied by the electronic microscope, metalloscope, nano hardometer, X-ray and various of wear testers.The aim of the research project is to study the mechanical performance of the nano diamond complex plating layers and the variations with the change of the temperature and load, and got the ultimate load of peeling off of the plating layers and the inoculation temperature. We also study the environment factors (load, temperature, lubricating condition) effect on the wear resistance of the nano diamond complex plating layers, determine the limits of application, the best technical parameters and practice effectiveness, and used as the foundation for deeply study and practice application..In the project, by complex plating and vacuum melting, produced Cr (Ni) nano diamond complex plating layers on the surfaces of high-speed steels, mould steels, high carbon steels, bearing steels and medium carbon steels, study the microstructures, test the friction characters under the lubricant condition, non- lubricant condition and abrasive wear condition. And study the effective of nano diamond powder on the microstructures and friction characters of Cr plating layers. There are followings..(1).The nano diamond can improve the density of coring, and increase the speed of plating. With increasing of plating time, the effective is more obvious. Under the experiment conditions, the speed of plating increased 2~3 times.(2).The nano diamond can refine the grain size. In ordinary Cr plating layers, the grains are bigger and arranged in lines along the polishing traces of the specimen surface. When adding the nano diamond into the electrolytic, the density of coring is increased, the grain size of plating layers is smaller, and arranged with no regularity.(3).When the solubility of nano diamond is less than 1%, the diamond can combined well with the Ni based self-fluxing alloys. When the solubility is more than 1%, the diamond will assembled. When the solubility is more than 2%, it can not be sintered..(4).The nano diamond can increase the hardness of plating layers. When added the nano diamond in the layers, the hardness changed with the different content of nano diamond. It is the hardest, when the content is 1%, the hardness increased one time than the ordinary Cr plating layers, the hardness is 9724.84Mpa. When plating Cr nano diamond complex layers on the surfaces of 45# steels which hardness are 36~38HRC, the microhardness of plating layers increase from 500Hv to 700Hv; . When plating Cr nano diamond complex layers on the surfaces of high-speed steels and 7Cr7Mo2V2Si steel which hardness are more than 58HRC, the microhardness of plating layers increase to 1000Hv ~ 11500Hv. The microhardness of ordinary Cr plating layers on W18Cr4V steel is 657Hv, and the microhardness of complex plating layers increase to 1000Hv. The microhardness o

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