AZ31镁合金在含NaCl和Na_2SO_4薄层液膜下的腐蚀行为  

Research on corrosion behavior of AZ31 magnesium alloys in thin electrolyte layers with NaCl and Na_2SO_4

作　　者：梁成浩[1] 郑润芬[2] 黄乃宝[1] 

机构地区：[1]大连海事大学交通运输装备与海洋工程学院,大连116026 [2]大庆油田建设设计院,黑龙江大庆163712

出　　处：《材料科学与工艺》2013年第6期34-40,共7页Materials Science and Technology

基　　金：国家高技术研究发展计划资助项目(2009AA05Z120)

摘　　要：为研究大气污染物对镁合金腐蚀的影响规律,采用室内模拟暴露实验,分析AZ31镁合金含有NaCl和Na2SO4的薄层液膜下的电化学腐蚀行为.结果表明:AZ31镁合金表面沉积NaCl和Na2SO4薄液层中的腐蚀动力学符合幂函数规律,说明NaCl和Na2SO4对AZ31镁合金腐蚀有加速作用;AZ31镁合金在NaCl薄层液膜下,阳极极化电流密度增大,R f和R ct值降低,促进了阴极去极化历程,增强了阳极活性溶解,加剧镁合金的阳极溶解;而在Na2SO4薄层液膜下,R f和R ct值增大,击穿电位与腐蚀电位的差值(ΔE)减小,这是由于难溶的硫酸盐和Mg(OH)2覆盖在AZ31镁合金表面,使金属溶解和离子扩散速率降低,导致阳极过程阻滞.To study the effects of atmospheric pollutants on the corrosion of magnesium alloys ,the electrochemical corrosion behavior of extruded AZ31 magnesium alloy in thin electrolyte layers with NaC1 or NazSO4 was studied by indoor atmospheric exposure test. The results indicated that the corrosion kinetics of AZ31 magnesium alloy in thin electrolyte layers accorded with a power function. It revealed that NaC1 and Na2SO4 could quicken the alloy＇s corrosion. In the thin electrolyte layers with NaC1, the result of potentiodynamic polarization showed that with the thinning of electrolyte layers, the alloy＇s polarization current density at more positive polarized potential increased. The consequence of AC Impedance showed that the value of Rf and Re, decreased. All these accelerated cathodic depolarization process, enhanced anodic activity and aggravated the dissolution of magnesium alloy. In the thin electrolyte layers with Na2SO4, the value of the value of Rf and Rc~ increased and the difference between breakdown and corrosion potential decreased with the thickness of thin electrolyte layers lessening. These was caused by the deposition of insoluble sulfate and Mg （OH）2 on the surface. The droop of metal dissolution and ionic diffusion blocked the anode process.

关 键 词：AZ31镁合金 薄层膜液 大气腐蚀 电化学腐蚀 腐蚀动力学 

分 类 号：TG172.3[金属学及工艺—金属表面处理]