新型低硅铸造铝合金耐腐蚀行为研究

Corrosion Resistance Behaviors of New Low Silicon Cast Aluminum Alloy

采用浸泡腐蚀试验、电化学极化和交流阻抗谱测试等手段,并利用扫描电镜(SEM)和能谱(EDS)等分析方法,研究了汽车转向节用新型低硅铸造铝合金在3.5%NaCl腐蚀介质下的腐蚀行为和规律。结果表明,低硅铸造铝合金在3.5%NaCl腐蚀介质下,其耐蚀性能与传统A356铝合金相当,其腐蚀产物主要为Al(OH)3、AlCl3及Al2O3;另外,Si含量在3%至4%变化时,Si含量增加引起二次枝晶壁间距减小,耐蚀性能随Si含量增加而提高;同时Cr元素的加入,使得材料的局部腐蚀倾向降低,但腐蚀速率有所提高。

Corrosion behaviors of a new low-silicon cast aluminum alloy for automobile steering knuckle in 3.5% NaCl corrosion medium was studied by means of soaking corrosion test, electrochemical polarization, AC impedance spectroscopy, scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS). The results show that the corrosion resistance of the low-silicon cast aluminum alloy in 3.5% NaCl corrosion medium was comparable to that of traditional A356 aluminum alloy. The corrosion products were mainly Al(OH)3, AlCl3 and Al2O3. In addition, when the Si content increased from 3% to 4%, the secondary dendrite wall spacing decreased, the corrosion resistance increased, and the addition of Cr decreased the corrosion tendency of the alloy, but the corrosion rate increased.