Ejm-assisted Mechanical Grinding Method For Fabrication Of High-precision SiC Cutting Tools

In recent years,with the increasing demands of complex shapes and high-precision surfaces in optical lenses,microelectronic components,precision equipment,and precision medical devices,advanced ultra-precision machining(UPM)techniques are playing an increasingly important role.Due to the low chemical stability of single crystal diamond tools,which are generally used for UPM,there is serious tool wear when processing ferrous metals.In this study,single-crystal silicon carbide(SiC)material,which is extremely stable both mechanically and chemically,is proposed as a new type of tool material for ultra-precision machining.Aiming at the high precision machining of SiC and its application for ultra-precision cutting tools,a novel electrochemical jet-assisted grinding process is proposed to achieve low damage,high efficiency and high surface quality processing requirements of SiC.The specific contents of the research are as follows:First,the development of cutting tools and the characteristics of different tools were reviewed,based on which the new single-crystal SiC tools were proposed.The state-of-the-art research of SiC fabrication and tool sharpening approaches were analyzed,and a new method of electrochemical jet-assisted grinding(EJAG)method was proposed.To develop the EJAG method,the electrochemical characteristics of single-crystal SiC were first studied,and the difference in the polarization curve between SiCand metal was compared using a three-electrode system.Through an investigation into the anodic oxidation behavior of 4H-SiC with varying electrochemical conditions such as the ion type,ion concentration,and anode potential of the electrolyte,the optimal electrolyte conditions to achieve the highest oxidation rate were obtained.By analyzing the surface morphology and chemical bonds composition after oxidation,the mechanism of anodizing of single-crystal SiC was demonstrated.Next,the localized oxidation behavior of SiC by electrochemical jet was investigated.The differences in the resulting oxide films under different current densities were discussed.The effects of the jet parameters on the morphology and thickness of the oxide layer were studied through single-point and scanning experiments.Furthermore,based on the principle of the convolution method,the conditions for forming a uniform and dense large area oxide layer were summarized.The electrochemical jet-assisted grinding was developed,and a comparison study between EJAG and conventional grinding was carried out.Based on the grinding experiments,the effects of different polishing parameters were discussed.Furthermore,the orthogonal experiment method was used to investigate the influence of different parameters and the best machining parameter,and the material removal mechanism of the developed grinding process was proposed.Finally,Starting from the design of the tool,the tool fabrication is completed through the wire electrical discharge cutting of raw materials,mechanical grinding and electrochemical jet-assisted grinding of the tool surfaces.The surface quality of the resulting tool and the arc radius of the blade was measured,and the extreme sharpness of the SiC tool than can be achieved by different fabrication processes was investigated.The electrochemical jet-assisted grinding method proposed in this research can be applied not only to the fabrication of single-crystal silicon carbide tools but also to the grinding and polishing of other materials similar to the characteristics of singlecrystal silicon carbide.