7075铝合金不同晶粒度在3.5%NaCl溶液中耐腐蚀性能分析

Corrosion Resistance of 7075 Aluminium Alloy with Different Grain Sizes in 3.5%NaCl Solution

通过热处理方法制备了晶粒度53、78、94、125μm的4组7075铝合金试样。利用交流阻抗谱和极化曲线研究比较了不同晶粒尺寸的试样在3.5%NaCl溶液中中短期电化学腐蚀行为,同时,对腐蚀产物及腐蚀机理进行了分析。结果表明,在3.5%NaCl溶液中浸泡1 h时,细晶粒7075铝合金试样的腐蚀速率比粗晶粒试样的小;浸泡14 d后,晶粒尺寸最小的试样表面只出现了微量的腐蚀产物,表面依然较为光华平整,随着晶粒尺寸的增大,腐蚀界面产物明显增多,其主要腐蚀产物为Al_(2)O_(3),且存在少部分AlCl_(3)和ZnCl_(3);在整个浸泡试验过程中,细晶粒试样具有更优异的耐蚀性能。

Four groups of 7075 aluminum alloy samples with grain sizes of 53,7&94,125μm were prepared by heat treatment.The effect of grain size on the electrochemistry behavior of rebars in 3.5%NaCl solution were investigated using electrochemical impedance spectroscopy(EIS)and polarization curves.At the same time,the corrosion products were studied by XRD.The results show that,at first(soaked lh)the fine-grained sample has a lower corrosion rate than coarse-grained sample.After soaking for a long time(14 days),less corrosion products appeared on the surface of the sample with the smallest grain size,and the surface was still smooth and flat.With the increase of grain size,the corrosion products increase obviously,and the main corrosion products are Al_(2)O_(3),with a small part of AlCl_(3) and ZnCl_(3).In the whole soaking process,the fine grain samples show better corrosion resistance.