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核电站服役的高温高压水回路中闭塞区的流动不充分,可能产生异常水化学条件而导致材料服役性能弱化.本文利用国产核级304不锈钢制备了一种简单的模拟闭塞区样品,放入含有Ni~(2+)的高温含氧水中浸泡并对生成的氧化膜进行表征.结果表明:闭塞区从外到内氧化膜外层中的尖晶石结构相的比例逐渐减小,而赤铁矿结构相的比例逐渐增大,模表层的Ni含量逐渐降低.分析表明,Ni~(2+)浓度会显著影响核级不锈钢的氧化行为,闭塞结构会在一定程度上阻碍本体溶液中的Ni~(2+)向闭塞区内扩散,使Ni~(2+)沿闭塞区深度方向形成浓度梯度.导致氧化膜的生长特征沿梯度方向发生明显变化.
In the high temperature and pressure water circuit that the nuclear power station is in service, the flow in the occluded area is not enough, which may result in the abnormal chemical conditions of the water, which will weaken the service performance of the material.In this paper, a simple simulated occlusion zone sample was prepared by using the domestic nuclear grade 304 stainless steel, ~ (2+) in high temperature oxygen-containing water and characterize the formed oxide film.The results show that the proportion of spinel structure phase in the outer layer of the occluded area gradually decreases, while the hematite The proportion of Ni and Ni in the surface layer gradually decreased, and the content of Ni in the surface layer gradually decreased.The results showed that the Ni 2+ concentration significantly affected the oxidation behavior of the core stainless steel, and the occlusion structure would hinder the Ni ~ (2+) diffuses into the occlusion zone, which leads to the concentration gradient of Ni 2+ along the depth of the occlusion zone, resulting in the obvious change of the growth characteristics of the oxide film along the gradient direction.