电解液与电参数交互作用对镁合金微弧氧化膜结构和性能的影响

发布时间：2018-06-01 08:37

本文选题：镁合金 + 微弧氧化　；参考：《兰州理工大学》2017年硕士论文

【摘要】：本文在双极性脉冲电源模式下以AZ91D镁合金基体为研究对象,利用正交试验方案设计,研究了K2ZrF6、EDTA-Na、电压及它们之间的交互作用对镁合金试样在磷酸盐电解液体系下所制备的微弧氧化陶瓷膜层性能和结构的影响规律。通过TT260型测厚仪、点滴实验和电化学实验分别表征膜层的厚度、点滴实验耐蚀性和电化学测试耐蚀性,并利用SEM观察了膜层的表面以及截面形貌。研究结果表明,对于膜厚来说,电压的影响最大且非常显著,K2ZrF6和电压的交互作用的影响次之且显著,K2ZrF6、EDTA-Na及其交互作用和EDTA-Na与电压之间的交互作用的影响均不显著。对于点滴实验耐蚀性来说,电压影响最大,比K2ZrF6和EDTA-Na及各因素之间的交互作用的影响高出两个数量级,其中除了电压以外的因素都在一个数量级上,且电压、K2ZrF6和EDTA-Na及其之间的交互作用对点滴实验耐蚀性的影响都不显著。对电化学测试耐蚀性来讲,K2ZrF6、EDTA-Na及其之间交互作用的影响非常显著,电压的影响显著,EDTA-Na、K2ZrF6与电压的交互作用影响不显著,其中影响最大的因素为K2ZrF6,EDTA-Na次之,再是K2ZrF6和EDTA-Na的交互作用。随K2ZrF6浓度的变化,膜层厚度和点滴实验耐蚀性变化不大,但在高浓度的K2ZrF6时促使熔融物填充于放电微孔中,减小孔洞等缺陷,使得氯离子不易在膜层中迁移,进而使得电化学测试耐蚀性增加。EDTA-Na抑制了微弧氧化过程中的剧烈反应,且浓度越高抑制效果越明显,越有利于降低了微裂纹等缺陷的产生,进而增加了膜层的耐蚀性。随电压的升高,尽管膜层的微孔孔径略有增大,微裂纹数量略有增多,但显著增加了膜层的厚度,使点滴实验耐蚀性得到提高,也使得膜层电化学测试耐蚀性有所升高。K2ZrF6和电压的交互作用,虽然显著的增加了膜层的厚度,但也可能显著的增加了膜层微孔和微裂纹等缺陷出现的几率,使得对膜层的性能影响不显著。另外,K2ZrF6和EDTA-Na的交互作用,在抑制大弧放电产生的同时,又在一定程度上填充了微弧放电产生的微孔,明显降低了膜层表面孔隙率和缺陷,提高了膜层的电化学耐腐蚀性能,使得对电化学测试耐蚀性影响显著。
[Abstract]:In this paper, the AZ91D magnesium alloy matrix is used as the research object in the bipolar pulse power supply mode, and the orthogonal test scheme is used to design it. The effect of K _ 2ZrF _ 6 EDTA-Na, voltage and their interaction on the properties and structure of micro-arc oxidation ceramic coatings prepared by magnesium alloy samples in phosphate electrolyte system was studied. The thickness, corrosion resistance and corrosion resistance of the film were characterized by TT260 thickness meter, drip test and electrochemical experiment, respectively. The surface and cross-section morphology of the film were observed by SEM. The results show that for film thickness, the effect of voltage on the interaction between K _ 2ZrF _ 6 and voltage is the most significant, and the interaction between K _ 2ZrF _ 6 and voltage is not significant. The effect of voltage on corrosion resistance is two orders of magnitude higher than that of K2ZrF6, EDTA-Na and the interaction of various factors, except the voltage, all of which are in one order of magnitude. The effect of voltage K _ 2ZrF _ 6, EDTA-Na and their interaction on the corrosion resistance of droplet test was not significant. The effect of voltage on the corrosion resistance of K _ 2ZrF _ 6 / EDTA-Na and its interaction is very significant. The effect of voltage on the interaction between K _ 2ZrF _ 6 and voltage is not significant. The most important factor is K _ 2ZrF _ 6 EDTA-Na, and then the interaction between K2ZrF6 and EDTA-Na. With the change of K2ZrF6 concentration, the thickness of the film and the corrosion resistance of droplet experiments change little. However, when the concentration of K2ZrF6 is high, the melt is filled in the discharge micropore, and the defects such as pores are reduced, so that the chloride ions are not easy to migrate in the film. Thus, the corrosion resistance of electrochemical test increased. EDTA-Na inhibited the severe reaction in the process of micro-arc oxidation. The higher the concentration, the more obvious the inhibition effect was, the more favorable to reduce the production of microcracks and other defects, and then increased the corrosion resistance of the film. With the increase of voltage, although the pore diameter of the film increases slightly and the number of microcracks increases slightly, the thickness of the film increases significantly and the corrosion resistance of the film is improved. It also increased the corrosion resistance of the film. K2ZrF6 and the interaction of voltage, although significantly increased the thickness of the film, but also significantly increased the possibility of defects such as micropores and microcracks in the film. The effect on the performance of the film is not significant. In addition, the interaction of K _ 2ZrF _ 6 and EDTA-Na not only inhibits the generation of large arc discharge, but also fills the micropore produced by micro-arc discharge to some extent, which obviously reduces the surface porosity and defects of the film, and improves the electrochemical corrosion resistance of the film. The results show that the corrosion resistance of electrochemical test is significantly affected.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.45

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