| It has been identified that the surface texture can improve tribological property. At present, it has been widely applied to many fields such as cylinder, journal bearing, and mechanical seal. Therefore, the processing of surface texturing with low cost, high efficiency and accuracy has become a research topic.Various techniques about surface texturing are employed. Compared to the other processing methods, electrochemical machining (ECM) is popular for its advantages in many applications such as its regardless of material hardness and no heat affected layer. ECM is a process of the anodic electrochemical dissolution of the metallic materials in an electrolytic medium utilizing the electrochemical reaction. Due to the tiny size of metal ion, ECM has a tremendous potential in the micro-manufacturing field.To fabricate well-defined surface texture in tens of microns to hundreds of microns, electrochemical micromachining of surface texturing is presented. According to the relative position of the tool cathode, the new technology can be classified as through movable mask electrochemical machining and electrochemical pattern transfer, and relative research has been carried out. The dissertation consists of several sections:(1) Through movable mask electrochemical machining of surface texturing is proposed. Compared with the traditional through mask electrochemical machining(TMEMM), the modified TMEMM can reduce cost,improve machining efficiency and flexibility .(2) The model of current distribution between the anode and cathode through the electrochemical machining process is build. Finite Element Method is then used to solve the model. The machining localization is analyzed and numerical simulation is carried out for better understanding the process and obtaining good processing parameters.(3) The key factors influencing the electrochemical machining of surface texturing process through movable mask have been studied experimentally. The experimental system of electrochemical machining is developed. The effects of the dimension of the movable mask and the machining parameters such as current density and the machining time on the surface texturing are investigated experimentally. The appearance of the surface texturing on different anode material surfaces are generated.(4) The auxiliary anode is consisted in the mask of the modified TMEMM to improve the localization of the surface texture. Numerical simulation of the current density in the interelectrode gap is verified the proposed method theoretically and the effect of the auxiliary anode on the machining localization on the aluminum-alloy surface is investigated experimentally. The experimental results indicate that the machining localization is significantly improved by the auxiliary anode successfully.(5) The key factors influencing the electrochemical pattern transfer of surface texturing have been studied theoretically and experimentally. The parameters of UV lithography process have been studied to pattern SU-8 photoresist spincoated on the cathode surface. Using optimized process parameters, some SU-8 moulds with good definition and topography, fewer defects and excellent adhesion to the metal substrate have been generated successfully. The mathematical model in the interelectrode gap is carried out and the influence of different interelectrode gaps on the electric field distribution is analyzed by the finite element method. The effects of the interelectrode gap and the pulse power parameters on the etch factor of the micro-dimple are investigated.(6) To verify the effect of surface texturing on the piston/piston ring samples, the friction tests are carried out using a reciprocating friction tester. According to the contact between the piston/piston rings and cylinder liner, friction tests are carried out for a variety of surface texture with different density and dimensions. The results of friction experiments show that the friction coefficient of the surface with appropriate surface texture is obviously lower than that smooth surface. |
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