Trial Fabrication and Properties of Ceramic Coatings for Fusion Reactor

在核聚变反应堆液包用陶瓷涂层中，批量生产、与液态金属的相容性以及作为氚渗透屏障和绝缘屏障的功能是重要的考虑因素。在本研究中，我们选择了一些陶瓷涂层的候选材料，用这些材料制备了涂层，并研究了它们的特性，从而建立了用于聚变反应堆液体包层的陶瓷涂层的制备技术。结果总结如下：(1)陶瓷涂层材料的选择：对于Li17-Pb83，基于热化学分析和块体材料腐蚀试验，Al_2O_3、MgO、Y_2O_3被提名为候选材料，其中Al_2O_3和Y_2O_3的电绝缘性能较好，被选为首选候选材料。另一方面，对于金属锂，除了Y_2O_3外，没有发现耐腐蚀的氧化物，并选择AlN作为候选材料。(2)陶瓷涂层材料在聚变反应堆环境下的性能变化：我们用液态金属进行腐蚀试验后，测量了由此选择的材料的电学性能。由于形成非化学计量化合物，Y_2O_3被锂还原成导电的。在高温照射下，涂层的电阻率会因辐射感应传导而下降。(3)陶瓷涂层的试制及实用性评价：在此基础上，采用不同的方法制备了Al_2O_3、Y_2O_3、AIN陶瓷涂层，并对其性能进行了测试。关于等离子喷涂方法，生成率足够高，但如何去除内部毛孔是一个重要的问题。对于浸渍法，如何有效地对试样进行硝化是一个重要的问题，特别是在AlN涂层的情况下。在溅射法中，对衬底进行处理是必要的。最后得出目前最理想的涂覆方法是Al_2O_3浸涂法。另一方面，对于金属锂，则是通过溅射或CVD方法形成的AlN层或通过浸涂法或溅射形成的Al层。少

In ceramic coating for fusion reactor liquid blankets, there are some important factors such as mass-production, compatibility with liquid metal and function as a tritium permeation barrier and an insulating barrier. In this study, we selected some candidate materials for ceramic coating, produced coatings experimentally from those materials, and investigated their characteristics so that we might establish the fabrication technique of ceramic coating for fusion reactor liquid blankets. The results are summarized as follows.(1) Material selection for ceramic coating : For Li17-Pb83, Al_2O_3, MgO, Y_2O_3 were nominated for candidate material based on thermochemical analysis and the corrosion test using bulk materials, and Al_2O_3 and Y_2O_3 were selected as the primary candidate materials because their electric insulation property was superior among them. For metallic lithium, on the other hand, no corrosion resistant oxides were found except Y_2O_3, and AlN was selected as a candidate … More material after nitrides were also examined.(2) Property change of ceramic coating materials in the fusion reactor environment : We measured electrical properties of the materials that were thus selected after corrosion test with the liquid metals. Y_2O_3 was reduced by lithium to become electrically conductive due to the formation of a nonstoichiometric compound. It was also concluded that the electrical resistivity of coatings may deteriorate due to radiation induced conduction under irradiation at high temperature.(3) Trial fabrication of ceramic coatings and assessment about their utility : Based on the results mentioned above, we prepared ceramic coatings of Al_2O_3, Y_2O_3, AIN by some methods and measured their properties. About the plasma spraying method, generation rate was enough high, but how you can remove inside pores is an important problem. About the dip coating method, how you can effectively nitrify the specimens is an important problem, in particular in case of AlN coating. In the sputtering method, it was concluded that the treatment of substrate is necessary.Finally, it was concluded that the most desirable method for coating at present is the dip coating method of Al_2O_3 for Li17-Pb83. For metallic lithium, on the other hand, it is AlN layer formation by sputtering or the CVD method Al layer formed by the dip coating method or sputtering. Less