铝在红沿河核电厂地区的初期大气腐蚀表征

Characterization on Early Atmospheric Corrosion of Aluminium in Hongyanhe Nuclear Power Plant

目的研究铝在辽宁红沿河核电厂地区的初期大气腐蚀行为。方法按GB/T 6464—1997,将制备好的试样在红沿河核电厂进行大气暴露试验,利用XRD,FTIR,SEM分析技术,对试验6个月和10个月的试样进行腐蚀产物观察与分析。结果铝在红沿河大气暴露腐蚀6个月和10个月样品表面均布满了点蚀坑、腐蚀产物及沉积物,腐蚀产物主要为Al2O3,Al OOH以及一些含氯和含硫的铝盐。腐蚀产物都较疏松,上下表面均有龟裂纹,相邻较近的点蚀坑已相互连接。随腐蚀时间延长,点蚀坑变深变大,朝地面点蚀坑深度已达上百微米。结论铝在红沿河核电厂大气环境中腐蚀以点蚀为主要特征,其腐蚀比普通大气环境中的严重,朝地面的腐蚀比朝天面严重,大气中氯离子及SO2参与铝的腐蚀过程并起促进作用。

Objective To study the characterization of early corrosion products of aluminium exposed to the atmosphere in the Hongyanhe nuclear power plant. Methods The samples were prepared and exposed to the atmosphere in Hongyanhe nuclear power plant according to the GB/T6464--1997. The corrosion products on the samples tested at 6 months and 10 months were observed and analyzed by means of SEM, XRD and FTIR techniques. Results There were corrosion pits and corrosion products and aggradations on the surface of the samples exposed for 6 and 10 months. The corrosion products were mainly Al2O3, AlOOH and aluminium salts containing chlorine and sulphur. The products were loosened with cracks on the upper and lower surfaces and pits near to each other were connected. The corrosion pits became larger and deeper over testing time, and the depth on the earthward （downward） surface reached up to hundreds of microns. Conclusion Corrosion of aluminium in the atmosphere in the Hongheyan nuclear power plant was mainly characterized by corrosion pits which was severer than in the normal atmosphere and the corrosion on the earthward surface was severer than on the upward surface. The synergic effect of SO2 and Cl played an important role in promoting corrosion process of aluminium.