稀土对镍铜合金铸铁耐烧碱腐蚀性能的影响

Effect of RE on Soda Corrosion Resistance of Ni-Cu Alloy Cast Iron

针对天然碱制碱工业中设备的腐蚀问题,研制出4种成分的稀土镍铜合金铸铁,进行金相组织分析,利用自制的动态腐蚀试验装置模拟碱腐蚀条件,测试其腐蚀速度,并对耐碱腐蚀性能进行评价。借助扫描电镜对镍铜合金铸铁的表面腐蚀形貌和微区成分分析,详细地讨论了稀土在铸铁中的作用与耐蚀机理。结果表明:稀土镍铜合金铸铁在高温浓烧碱液中宏观上属于全面腐蚀,微观上存在不同程度的镍、铜元素富集。加入适量的稀土,可以减小合金铸铁在烧碱液中的腐蚀速度,有效的改善合金铸铁的耐碱腐蚀性能。但是稀土加入过量会造成合金铸铁的耐碱腐蚀性能的下降。

Four types of RE-Ni-Cu cast iron were developed to solve the corrosion problem in caustic soda industry. The corrosion rate was tested by the self-made dynamic corrosion experiment equipment which simulated the soda corrosion condition on the basis of organic analyzing. RE＇s action and corrosion resistant mechanism were discussed through analyzing surface corrosion appearance and components by SEM. The results showed that RE-Ni-Cu cast iron is general corroded macroscopically in the dense caustic soda at high temperature and there is Ni-Cu enrichment microcosmically. The corrosion rate of Ni-Cu cast iron can be reduced by addition of RE and the soda corrosion resistance can also be improved effectively. However, the property will decrease if RE is added excessively.