| CVD diamond has the advantages of high hardness,high wear resistance and low friction coefficient.It is widely used in the preparation of coated tools to improve their cutting performance.The micro texture of the tool surface can contain the wear debris and reduce the friction coefficient of the tool to a certain extent.With the continuous development of laser micro texture technology and the large-scale application of diamond coated tools in industrial production,in order to improve the tribological performance of diamond coated tools,the technology of diamond coating texture treatment emerges as the times require.In order to improve the friction and wear properties of CVD diamond coated tools,the mechanism of synergistic wear reduction of laser surface microtexture and graphite of diamond coating on cemented carbide substrate was studied.The research results of this paper have high theoretical significance and practical value for expanding the application scope of diamond coating and improving the service life and machining accuracy of diamond coated tools.The main research contents are as follows:(1)Based on the literature at home and abroad,the research progress of friction and wear properties of CVD diamond coating and the research status of anti-wear texture on tool surface are reviewed.The mechanism of friction and wear of CVD diamond coating was analyzed,and the method of reducing friction by laser surface microtexture and graphite was proposed.(2)The formation mechanism of laser-induced micro texture on the surface of diamond coated tools was studied.The temperature field simulation model of nanosecond laser etching diamond coating was established,and the graphitization threshold and gasification threshold of diamond coating were calculated according to the model.The relationship between the crystal structure of diamond and graphite and their physical properties was analyzed.The mechanism of friction reduction and lubrication of graphite was studied.(3)The optimization design of surface micro texture parameters of diamond coating.Based on the theory of bionic tribology,micro textures with different morphologies(diamond,hexagon and concentric circle)were prepared on the surface of diamond coating by the method of coating before texture.The effects of texture morphology,area density and texture depth on the graphitization degree of diamond coating were analyzed.The results show that the graphitization degree of diamond coating is the highest in concentric microtexture,followed by hexagonal microtexture,and the lowest in rhombic microtexture;with the increase of microtexture surface density,the graphitization degree of diamond coating increases;texture depth has little effect on the graphitization degree of diamond coating,and the deeper the texture depth is,the more graphitization degree increases slowly.(4)Through the experimental study on the friction and wear of the micro textured diamond coating,the mechanism of synergistic friction reduction between the micro texture and graphite on the surface of the coating is revealed.The results show that the graphite layer on the micro textured surface can significantly improve the dry friction performance of the friction surface.The graphitization of the micro texture surface can make the friction coefficient decrease rapidly and stabilize at the initial stage of friction,and the friction coefficient of the stabilized diamond coating decreases with the increase of graphitization degree.The wear degree of diamond coating is affected by many mechanisms.The micro texture can store the abrasive particles and effectively reduce the abrasive wear.However,the graphite layer produced by laser irradiation and friction heat will increase the adhesion wear degree of diamond coating.The graphitization degree of micro texture is the main factor affecting the wear degree of diamond coating.The higher the graphitization degree of micro texture is,the greater the wear degree of diamond coating is.Figure [63] table [11] reference [112]... |
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