铬酸钠对铀钛合金在氯化钠溶液中的缓蚀作用

Corrosion Inhibition of Sodium Chromate for Uranium-Titanium Alloy in Sodium Chloride Solution

采用失重法和电化学方法研究了铬酸钠对铀钛合金在200 mg/L氯化钠溶液中的缓蚀作用,并用X射线光电子能谱(XPS)和激光共聚焦显微镜分析铀钛合金表面氧化物成分和形貌。结果表明,铬酸钠属于阳极型钝化剂,缓蚀效率随浓度的增加而增大。但溶液温度对铬酸钠的缓蚀效率影响较大,溶液温度高于45℃时,加入100 mg/L的铬酸钠对铀钛合金具有加速腐蚀作用。XPS分析表明,铀钛合金表面形成的钝化膜中铀的氧化物存在两种形式,最外层为UO2+x,内层为UO2;加入铬酸钠后,钝化膜最外层含有UO2+x和多种铬化合物,厚度小于3 nm。

The inhibition effect of sodium chromate （Na2CrO4） on uranium-titanium （U-Ti） alloy in 200 mg/L NaCl solution was evaluated with the weight-loss method and the electrochemical method. The feature of the oxide film formed on the U-Ti alloy sample surface was analyzed with X-ray photoelectron spectroscopy （XPS） and laser confocal microscope. The results show that Na2CrO4 is anodic inhibitor for U-Ti alloy and the inhibition efficiency increases with its concentration increasing. The efficiency is influenced greatly by the temperature of corrosion solution. The corrosion rate of U-Ti alloy sample is greater in 100 mg/L Na2CrO4 solution than in uninhibited solution when the solution temperature is higher than 45 ℃. The XPS analysis indicates that there are two types of uranium oxide in the passive film of U-Ti alloy surface. UO2＋x is in the outer layer in the film while UO2 in the inner layer. The outer layer of passive film includes UO2＋x and some chromium compounds when Na2CrO4 is added into NaC1 solution, and the thickness of the outer layer is less than 3 nm.