电参数及其交互作用对纯铝微弧氧化膜结构和性能的影响

发布时间：2018-05-07 06:01

本文选题：正交试验 + 微弧氧化　；参考：《兰州理工大学》2016年硕士论文

【摘要】：本论文采用正交试验设计及相应的数据处理,研究了电参数及电参数之间的交互作用对纯铝基体在硅酸盐体系电解液中微弧氧化所得陶瓷膜层性能和结构的影响规律。通过TT260测厚仪,点滴耐蚀实验和电化学实验来分别表征微弧氧化膜层的膜厚、点滴耐蚀性及电化学腐蚀电流值三个性能指标;利用SEM、XRD等材料分析方法,观察了膜层的表面形貌和截面形貌,并检测了膜层的物相组成。研究结果表明,电压对膜层的厚度及点滴耐蚀性的影响最为显著,比频率和占空比及各电参数之间交互作用的影响高出两到三个数量级。频率次之,占空比对膜厚和点滴耐蚀性的影响不明显,所以在分别考虑膜厚和点滴耐蚀性时,得出的最佳电参数搭配只在占空比的优水平出现的差异是可以忽略的,而在综合考虑膜厚和点滴耐蚀性时得出的优方案和只考虑膜厚时得出的优方案一致,均为电压480 V、频率700 HZ、占空比30%。电压对腐蚀电流密度的影响略微显著,主要是由于腐蚀电流密度受到很多因素的综合影响,虽然在高电压时膜层较厚但是由于致密性下降,导致在电化学实验中氯离子会通过膜层中的击穿微孔和裂纹等缺陷迁移,表现为腐蚀电流密度较大,耐蚀性较差;而在低电压下膜层虽然较薄但有很好的致密性,阻碍了氯离子的迁移,导致腐蚀电流密度较小,耐蚀性好。所以在只考虑腐蚀电流密度及对膜厚和腐蚀电流密度综合分析时确定的优方案为电压340 V、频率2000 HZ、占空比20%。频率对膜厚、点滴耐蚀性及腐蚀电流密度的影响均不显著,但是对点滴耐蚀性和腐蚀电流密度的影响大于对膜厚的影响,这主要是由于频率影响微弧氧化膜层的致密性,致密性越高则点滴实验中的氢离子和电化学实验中的氯离子都不容易在膜层中迁移,表现为耐蚀性好。但是对于点滴实验,与氢离子发生反应的微弧氧化产物量的多少才是影响点滴耐蚀性好坏的主要原因,低频下膜层的生长速率要比高频下的要快,氧化产物也就多,所以在考虑点滴耐蚀性时电参数的最佳搭配中频率定为700 HZ,而在考虑电化学腐蚀电流密度时频率定为2000 HZ。占空比对膜层的性能影响都不显著,但对腐蚀电流值略有影响,主要是由于占空比越高膜层中的裂纹越多,电化学实验中氯离子的迁移越容易,腐蚀电流就会越大,所以在只考虑腐蚀电流时占空比选择低水平即20%,而在其它的最佳电参数搭配中选择高低水平的占空比均可。电压和频率、电压和占空比及频率和占空比之间的交互作用对膜层的厚度、点滴耐蚀性及电化学腐蚀电流密度的影响都不显著,但是略有影响。电压和频率的交互作用对腐蚀电流密度的影响比对膜厚和点滴耐蚀性的影响高出一个数量级,电压和占空比的交互作用对三个指标的影响在同一数量级上,频率和占空比对膜厚和腐蚀电流密度的影响在同一数量级,但比对点滴耐蚀性的影响高出一个数量级。
[Abstract]:In this paper, the influence of the interaction between electrical parameters and electrical parameters on the properties and structure of ceramic coatings of pure aluminum matrix in silicate electrolyte is studied by orthogonal experimental design and corresponding data processing. Microarc oxidation is characterized by TT260 thickness gauge, dot corrosion testing and electrochemical experiments. The film thickness, corrosion resistance and electrochemical corrosion current value are three performance indexes. Using SEM, XRD and other material analysis methods, the surface morphology and cross section morphology of the film are observed and the phase composition of the film is detected. The results show that the voltage has the most significant influence on the thickness of the film and the corrosion resistance of the droplets, and the specific frequency and the duty cycle. The influence of the interaction between the electrical parameters is two to three orders of magnitude higher. At the second of the frequency, the influence of the duty ratio on the film thickness and the corrosion resistance is not obvious. Therefore, when the film thickness and the drop corrosion resistance are considered, the difference between the optimal electrical parameters and the optimal level of the occupying ratio is negligible, while the film thickness is considered in a comprehensive way. The excellent scheme and the excellent scheme only considered when the film thickness is considered, are the voltage 480 V, the frequency 700 HZ, the duty ratio 30%. voltage has a slight influence on the corrosion current density, mainly because the corrosion current density is influenced by many factors, although the film is thicker but compactness at high voltage. In electrochemical experiments, the chloride ion will migrate through the breakdown of micropores and cracks in the membrane, which shows that the corrosion current density is larger and the corrosion resistance is poor, while the film is thinner but has a good compactness at low voltage, which hinders the migration of chlorine ions, the corrosion current density is small, and the corrosion resistance is good. So only the corrosion resistance is good. Considering the corrosion current density and the comprehensive analysis of the film thickness and corrosion current density, the optimal scheme is the voltage 340 V, the frequency 2000 HZ, the duty ratio 20%. frequency has no significant effect on the film thickness, the corrosion resistance and the corrosion current density, but the effect on the corrosion resistance and the corrosion current density is greater than that of the film thickness. This is mainly caused by the effect of the corrosion resistance and the corrosion current density. The higher the density of the microarc oxidation film and the higher the density, the hydrogen ions in the experiment and the chlorine ion in the electrochemical experiment are not easy to migrate in the film, and the corrosion resistance is good. However, the amount of the micro arc oxidation products which reacts with the hydrogen ions is the main influence on the corrosion resistance of the drops. For reasons, the growth rate of low frequency lower layer is faster than that at high frequency, and the oxidation product is more, so the optimum intermediate frequency ratio of the electrical parameters is 700 HZ when considering the corrosion resistance, while the effect of the frequency of 2000 HZ. on the electrochemical corrosion current density is not significant, but the corrosion current is a little bit. It is mainly due to the more cracks in the higher duty cycle, the easier the chloride ion transfer in the electrochemical experiment will be, the greater the corrosion current will be, so the choice of the duty ratio is 20% at low level when the corrosion current is considered, and the voltage and frequency, the voltage and the voltage can be selected in the other best electrical parameters collocation. The interaction between the duty ratio and the frequency and the duty ratio has no significant influence on the thickness of the film, the corrosion resistance and the electrochemical corrosion current density, but it has a slight influence. The influence of the interaction of voltage and frequency on the corrosion current density is an order of magnitude higher than the influence of the thickness and corrosion resistance of the film, voltage and duty cycle. The effect of interaction on the three indices at the same order of magnitude, the influence of frequency and duty ratio on the thickness of the film and the corrosion current density at the same order of magnitude, but more than one order of magnitude higher than that of the corrosion resistance.

【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG174.4

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