含草酸的硝酸溶液对锆合金的腐蚀行为

Corrosion Behavior of Zirconium Alloy in Nitric Acid Solution Containing Oxalic Acid

本工作模拟草酸钚沉淀母液蒸发浓缩工艺的运行条件,依据GB/T 4334.3-2000的实验要求,开展了含草酸的硝酸溶液对锆合金板材和焊件的腐蚀行为研究。采用称重法获得了腐蚀速率数据,采用扫描电镜观察金属表面的腐蚀形貌,并测定了腐蚀溶液中金属离子的浓度。结果表明:模拟实验条件下锆合金各腐蚀样品腐蚀速率均极低,测得的锆合金板材的最大平均腐蚀速率为0.0010 g/(m^(2)·h),焊件的最大平均腐蚀速率为0.0007 g/(m^(2)·h),硝酸浓度和温度变化不增加锆的腐蚀速率,腐蚀性能显著优于不锈钢。这些初步解释了法国后处理厂选择Zr-702为草酸钚沉淀母液蒸发浓缩设备材料的原因。

In this work,the process operation conditions of metal materials used in the evaporation and concentration process of the mother liquor after plutonium oxalate precipitation was simulated,and the corrosion behavior of zirconium alloy plate and its welded samples in the mixed oxalic-nitric acid was studied according to the requirements of GB/T 4334.3-2000.The corrosion rates were obtained by weighing method,the corrosion morphology of metal surface was observed by scanning electron microscope,and the concentrations of metal ions in the corrosion solutions were determined.The results show that the corrosion rates acquired by simulating corrosion tests are relatively low.The maximum corrosion rates of zirconium alloy are 0.0010 g/(m^(2)·h)for plate and 0.0007 g/(m^(2)·h)for weld,which are independent on the temperature and nitric acid concentration,and less than the values for stainless steel.Based on these results,we can understand why Zr-702 was selected as the material of evaporation and concentration equipment for the mother liquor of plutonium oxalate precipitation in the French reprocessing plant.