钛合金微弧氧化膜层摩擦学特性研究

发布时间：2018-04-02 06:00

本文选题：钛合金　切入点：微弧氧化　出处：《北京理工大学》2015年硕士论文

【摘要】：钛合金由于比强度高、耐腐蚀、耐热等良好的综合性能和结构效益高而被广泛用于航空领域、航天、船舶、生物医疗等领域。但是钛合金的表面硬度较低、耐磨性较差,特别是钛合金与其它金属接触时很容易发生粘着磨损、微动磨损,从而发生接触腐蚀,这些都严重制约了其进一步应用。微弧氧化又称微等离子氧化,是在Ti、A1、Mg等金属及其合金的表面原位生长陶瓷膜的技术。利用电化学方法在该材料的表面产生火花放电现象,在热化学、等离子体化学和电化学的共同作用下,生成陶瓷膜层。本论文主要研究了硅酸盐-氟化钠、磷酸盐-柠檬酸钠和磷酸钠-偏铝酸钠复合体系三种电解液体系的配方优化,考察了电解液体系对微弧氧化膜层的色泽、均匀性、显微硬度、微观结构、摩擦学特性等性能的影响规律。筛选出最佳的电解液配方和电源输出工艺参数,在钛合金表面制备具有一定摩擦学特性的微弧氧化膜层。主要研究结果如下:(1)硅酸盐-氟化钠体系中制备的微弧氧化膜微观结构较均匀,随着终止电压的逐步增大,膜层表面生成一定厚度的疏松层,膜层与45#钢圆盘对磨时摩擦系数随着终止电压的增大先增大后减小,这与膜层的显微硬度随终止电压的增大先增大后减小的趋势是一致的。(2)磷酸盐-柠檬酸钠体系中制备的微弧氧化膜微观结构均匀性较差,微孔呈扁长结构,且分布不均匀,其与45#钢圆盘对磨时摩擦系数随着终止电压的增大先增大后减小,但其平均摩擦系数较大,在0.35~0.40之间。(3)磷酸钠-偏铝酸钠复合体系中制备的微弧氧化膜微观结构非常均匀,随着终止电压的逐步增大,由于磷酸钠-偏铝酸钠双重主盐的作用,膜层表面微孔分布较均匀,疏松层较薄,膜层与45#钢圆盘对磨时摩擦系数随着终止电压的增大先增大后减小,且其平均摩擦系数最小,在0.11~0.13之间。(4)三种电解液体系制备的微弧氧化膜层的摩擦系数均优于TC4钛合金的摩擦学性能,以膜层与45#钢圆盘对磨时摩擦系数作为衡量标准,磷酸钠-偏铝酸钠复合体系优于硅酸盐-氟化钠体系,磷酸盐-柠檬酸钠体系制备的膜层的摩擦系数最大,这与三种电解液体系条件下制备的膜层的显微硬度顺序是一致的。
[Abstract]:Titanium alloys are widely used in aeronautical, aerospace, marine, biomedical and other fields because of their high specific strength, corrosion resistance, heat resistance and high efficiency of structure and structure.However, the surface hardness and wear resistance of titanium alloy are low, especially the adhesion wear and fretting wear are easy to occur when the titanium alloy is in contact with other metals, which seriously restricts its further application.Micro-arc oxidation, also known as micro-plasma oxidation, is a technique for in-situ growth of ceramic films on the surfaces of metals such as TiA1mg and their alloys.The spark discharge phenomenon was produced on the surface of the material by electrochemical method, and the ceramic film was formed under the combined action of thermochemistry, plasma chemistry and electrochemistry.In this paper, the formula optimization of silicate sodium fluoride, phosphate sodium citrate and sodium phosphate sodium aluminate composite electrolyte system was studied, and the color and uniformity of the electrolyte system to the micro-arc oxide film were investigated.Effects of microhardness, microstructure, tribological properties and so on.The optimum electrolyte formula and power output process parameters were selected, and the micro-arc oxide film with certain tribological properties was prepared on the surface of titanium alloy.The main results are as follows: (1) the microstructure of the micro-arc oxide films prepared in the silicate-sodium fluoride system is more uniform, and with the increasing of the termination voltage, a certain thickness of loose layer is formed on the surface of the film.The friction coefficient increases first and then decreases with the increase of the stop voltage when the film layer is grinded against the 4x4 steel disc.This is consistent with the trend that the microhardness of the film increases first with the increase of the terminal voltage and then decreases. The microstructures of the micro-arc oxide films prepared in the phosphate-sodium citrate system are poor in homogeneity, and the micropores are flat and long, and the distribution is not uniform.The friction coefficient increases first and then decreases with the increase of the termination voltage, but its average friction coefficient is larger, and the microstructure of the micro-arc oxide film prepared in the composite system of 0.35 ~ 0.40% sodium phosphate and sodium metaluminate is very uniform.With the increasing of the termination voltage, due to the action of sodium phosphate and sodium aluminate, the distribution of micropores on the surface of the film is more uniform, and the loose layer is thinner.The friction coefficient increases first and then decreases with the increase of the termination voltage, and the average friction coefficient is the smallest.The friction coefficient of the three electrolyte systems was better than that of TC4 titanium alloy. The friction coefficient between the film and the 4steel disc was taken as the criterion.The composite system of sodium phosphate and sodium aluminate is superior to the system of silicate and sodium fluoride, and the friction coefficient of the film prepared by phosphate-sodium citrate system is the largest, which is consistent with the order of microhardness of the film prepared under three electrolyte systems.
【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG174.4

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