Development of Low-Alloy Steel for High Level Radioactive Waste Disposal Container

为研制用于高放废物地质处置的低合金钢容器，研制了一系列含少量合金元素的0.12%C钢，有效地抑制了Fe3O4的阴极反应，并测试了其耐蚀性。用离子束溅射法制备了Fe_3O_4和Mo_x(M：Cr，Mo，Si，Al，Ti，Cu，Ni，Nb)复合氧化物薄膜，并在模拟水溶液中研究了它们的阴极极化特性。结果表明，在Fe_3O_4中添加Cr2O_3、TiO_2、Al_2O_3和MoO_2能有效地抑制Fe_3O_4.2的还原溶解。采用真空感应熔炼法制备了一系列含合金元素(铬、钼、硅、铝、钛、铜、镍、Nb)的低合金钢，它们能有效地抑制Fe3O4的还原溶解，提高氢过电压。腐蚀试验在压缩膨润土中进行，暴露于膨润土-含0.5M-氯化钠的模拟水溶液中。在无Fe_3O_4膜的情况下，含0.5%铜、铝、铬或钛的钢具有较好的耐蚀性，而在有Fe_3O_4膜的情况下，含铜、含Nb或含钛的钢具有较高的耐蚀性。这表明在提高耐蚀性方面，铜是最有前途的合金元素。在膨润土-水的模拟溶液中，测定了低合金钢的阳极和阴极极化曲线。耐腐蚀性能优良的钢具有较高的氢过电压和较低的Fe3O4还原溶解速率。

In order to develop a low-alloy steel container for use in geological disposal of high-level radioactive wastes, a series of 0.12%C steels containing a small amount of alloying elements, which are effective in inhibiting cathodic reactions on Fe_3O_4, were prepared and their corrosion resistance was examined.1. A series of composite oxide films consisting of Fe_3O_4 and MO_x(M: Cr, Mo, Si, Al, Ti, Cu, Ni, Nb) were prepared by ion-beam-sputter deposition and their cathodic polarization characteristics were examined in a simulated solution of water in contact with bentonite (5.72mM-Na_2SO_4+7.99mM-NaHCO)_3 The results showed that the addition of Cr_2O_3, TiO_2, Al_2O_3 and MoO_2 to Fe_3O_4 is effective in suppressing reductive dissolution of Fe_3O_4.2. A series of low-alloy steels containing alloying elements (Cr, Mo, Si, Al, Ti, Cu, Ni, Nb), which are effective in inhibiting reductive dissolution of Fe_3O_4 and in increasing hydrogen overvoltage, were prepared by vacuum induction melting. The corrosion tests were performed in compressed bentonite exposed to the simulated solution of bentonite-contacting water containing 0.5M-NaCl. In the absence of Fe_3O_4film the steels containing 0.5% Cu, Al, Cr or Ti showed good corrosion resistance, while in the presence of Fe_3O_4film those containing Cu, Nb, or Ti exhibited high corrosion resistance. This suggests that Cu is the most promising alloying element for improving corrosion resistance.3. Anodic and cathodic polarization curves of the low-alloy steels developed in the present study were measured in the simulated solution of bentonite-contacting water. The steels having excellent corrosion resistance in the corrosion tests showed a high hydrogen overvoltage and a low reductive dissolution rate of Fe_3O_4.