金属铀在水气气氛中加速腐蚀的实验研究

Experimental Study on Accelerated Corrosion Uranium-water Vapor by Thermogravimetry

用热重法研究了铀在50～90℃和32%～86%湿度范围的水气气氛中的加速腐蚀,得到了该实验条件下铀的水气腐蚀特性,并对反应的动力学进行了讨论。结果表明:在不同温度、湿度条件下,铀在水气气氛中的腐蚀动力学过程表现为较为明显的3阶段,动力学过程最后为线性反应阶段,该阶段有一稳定的氧化反应速率常数。RH=74.7%时线性反应的活化能约为42.899kJ·mol-1。温度对反应速率的影响明显,温度升高,反应速率加快。

The experimental study on uranium corrosion was carried out over a range of 50-90°C and 32%-86% relative humidity by thermogravimetry (TG). The corrosion degree of uranium-water vapor reaction was evaluated by weighing sample weight gain at appropriate intervals. Under above experimental conditions, the characteristic of uranium corrosion was observed and its kinetics was also discussed. The results indicate that there are three stages in the uranium-water vapor oxidation reaction at various temperatures. First, there is an initial reaction stage followed by the corrosion rate tends to be slow down after the first corrosion stage. At the third stage, the corrosion reaction presents to be a linear reaction with a stable oxidation reaction rate constant. The dynamics curves on the rear part of linear reaction stage are fitted, and the activation energy deduced is about 42.899 kJ&middotmol-1 at RH = 74.7%. Uranium-water vapor reaction is faster at higher temperatures. The effect of relative humidity on the uranium-water reaction is about the same as that of temperature in the range of 70-90°C, but the further study on the effect of relative humidity below 60°C is necessary.