高温熔融玻璃介质中耐热不锈钢腐蚀行为

Corrosion behavior of heat-resistant stainless steel in high temperature molten glass

核工业发展及核能的不断开发促使人们开始大力研究绿色环保且安全的核废料处理技术。利用金属容器填装玻璃固化核废料并进行填埋是目前国际上主流的核废料处理技术之一。然而,高温熔融玻璃对金属容器表面产生的高温腐蚀成为加速容器失效的重要原因。因此,深入理解金属在高温熔融玻璃介质中的腐蚀行为是保障核废料安全处理的关键之一。本研究选用S30815耐热不锈钢作为研究对象,深入分析S30815耐热不锈钢在1100℃熔融玻璃中保温不同时间后材料表面腐蚀形态、成分及物相结构。研究结果表明,熔融玻璃首先沿晶界向内腐蚀,然后逐步替代金属材料占据晶界位置并进一步向晶内扩渗,形成腐蚀坑。耐热不锈钢中的Cr,Si元素在腐蚀过程中向熔融玻璃扩渗并导致金属表层元素含量下降,最终促使金属表面由奥氏体转变为马氏体。熔融玻璃对耐热不锈钢的腐蚀属于碱性溶解,金属表面无法形成连续稳定的氧化膜,因此,随着保温时间延长腐蚀将会不断进行。

The development of the nuclear industry and nuclear energy have prompted studies focusing on disposal of nuclear waste in a green and safe way.The use of metal containers to fill glass solidified nuclear waste and then landfill is currently the dominant way in waste disposal.However,the high temperature corrosion caused by the high temperature molten glass on the surface of the metal container becomes an important factor accelerating the failure of the container.Therefore,an in-depth understanding of the corrosion behavior of metals in high temperature molten glass is necessary to ensure the safety of disposal of nuclear waste.The S30815 heat-resistant stainless steel was selected as the research object,and the corrosion morphology,composition and phase structure of the S30815 heat-resistant stainless steel kept in 1100℃molten glass for different time were deeply analyzed.The results show that the molten glass corrodes inward along the grain boundary into the matrix and molten glass gradually replaces the steel by occupying the grain boundary and further penetrates the grains to form corrosion pits.Cr and Si elements in the heat-resistant stainless steel diffuse into the molten glass during corrosion,resulting in a decrease of content at the surface,and finally promote the transformation of metal surface from austenite to martensite.The corrosion of heat-resistant stainless steel by molten glass is alkaline dissolution.A continuous and stable oxide film cannot be formed on the surface,which means the corrosion will continue with the extension of holding time.