铝合金组织结构对其耐蚀性能影响的研究

发布时间：2018-02-24 21:54

本文关键词： 铝合金品粒晶界 EBSD NMT 超疏水耐蚀性　出处：《北方工业大学》2016年硕士论文　论文类型：学位论文

【摘要】：随着社会的不断进步,技术的不断发展与创新,对铝合金的耐蚀性也提出了更高的要求,铝合金的腐蚀与防护是一个贯穿时代发展的问题,对于铝合金腐蚀机制的深入研究及腐蚀防护措施的改进都是当下亟待解决的问题。本文合金的选择为铸造铝合金A356,对A356铝合金进行复合微合金化,进行T6热处理,改善其组织结构,对试样进行电化学实验来检测其耐蚀性,参照GB 7998-87进行了腐蚀实验,对腐蚀程度分级,通过电子背散射衍射(EBSD)实验,对晶粒大小、晶界类型、晶界特性进行了研究,探究晶粒晶界影响铝合金的耐蚀性能的机制。研究发现：随着元素比例的变化,晶粒的大小,晶界中特殊晶界的尺寸,比例以及晶界的取向差角都发生了明显改变,当元素比例达到0.15%La,0.3%Y时,晶粒细化最为明显,∑3晶界所占比例最高,小角度晶界所占比例明显提高,耐腐蚀性显著提高。对A356铝合金进行表面磷化处理：35g/L的KMnO4溶液+130g/L的K2HPO3溶液+磷酸；转速调至500r/min,溶液的温度选择45℃,溶液pH值调整至4,转化时间为20min；制成磷化膜后在硫酸、铜盐、酒精组成的混合溶液中,保持温度40℃,进行电沉积40min后制备出超疏水膜层。对膜层的表面形貌以及截面形貌进行了观察以及耐蚀性检测,再经NMT技术检测了膜层表面Cl-的流速与浓度,从Cr的内流外流情况检测样品的耐蚀性。结果发现离子外流越明显,合金表面的耐蚀性越强。本文制备了不同元素比例的Al-Si-Mg合金试样。通过对样品中Mg2Si相形貌的观察以及能谱扫描,检测了样品中实际元素比例及含量。我们发现Mg2Si相的形态及分布与铝合金的耐蚀性能的改善密切相关,且Mg2Si数量越多分布越密集,耐蚀性越好。
[Abstract]:With the development of society, the continuous development and innovation of technology, the corrosion resistance of Aluminum Alloy also put forward higher requirements for corrosion and protection of Aluminum Alloy is an era through the development, improvement and Research on corrosion protection measures of corrosion mechanism of Aluminum Alloy are the current problems to be solved. In this paper, the selection of cast alloy Aluminum Alloy A356 composite micro alloying of A356 Aluminum Alloy, T6 heat treatment, improve the organizational structure, electrochemical experiments were performed to detect the corrosion resistance of the sample, according to the GB 7998-87 corrosion experiment, the corrosion degree of the electron backscatter diffraction (EBSD) experiments the grain size, grain boundary, grain boundary types, characteristics of the mechanism of corrosion resistance of the grain boundaries on Aluminum Alloy. The study found that: with the changes of element ratio, grain size, grain boundary in special Grain size, proportion and grain boundary misorientation angles were changed when the element ratio reached 0.15%La, 0.3%Y, grain refinement was the most obvious, 3 Sigma GB accounted for the highest proportion of small angle grain boundary are obviously improved, the corrosion resistance is improved significantly. The A356 Aluminum Alloy surface phosphating treatment: KMnO4 +130g/L 35g/L solution K2HPO3 solution + phosphate; speed to 45 DEG 500r/min, select the solution temperature, the pH value of the solution was adjusted to 4 and the conversion time is 20min; made of phosphating film in sulfuric acid, copper salt, mixed solution of alcohol composition, keep the temperature at 40 degrees, the electrodeposition was carried out after 40min preparation of superhydrophobic the surface morphology of the film. The film and the cross section morphology was observed and the corrosion resistance detection by NMT technique to detect the velocity and concentration of coating on the surface of Cl-, the exodus of samples from the corrosion resistance of Cr. Results The ion efflux increased, the corrosion resistance of the alloy surface stronger. Al-Si-Mg alloy samples with different ratio of elements was fabricated in this paper. Through the observation of the samples in the Mg2Si morphology and energy spectrum scanning, the ratio and amount of actual elements in samples tested. We found that the corrosion resistance of the morphology and distribution of Mg2Si phase and Aluminum Alloy. Closely related to the improvement of Mg2Si, and the more the number of more intensive distribution, better corrosion resistance.

【学位授予单位】：北方工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG146.21

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