AGGRESSIVE CORROSION OF ADVANCED MATERIALS

用于汽轮机和锅炉的耐热合金在高温下容易遭受严重腐蚀。特别是，能量转换系统运行在含有O、S和C1及其化合物的混合气体环境中。为了阐明金属间化合物、高温合金、硅化物和铝化物等先进材料的腐蚀行为，我们组成了一个由北海道大学和澳大利亚新南威尔士大学组成的研究小组。在这两年里，我们举行了四次会议，讨论了黑川的硅化物氧化行为、Gleeson的TiAl金属间化合物的氧化和硫化、Young的钢和合金的渗碳、Sato的镍和铁基合金的氯化以及Narita的铝化物的硫化行为。其中之一是，人们普遍认为在相对简单的含氧或含硫环境中氧化或硫化是可以理解的，但在混合氧化剂环境中的腐蚀行为仍有许多悬而未决的问题。因此，除了热力学和动力学立场外，我们还需要进一步的研究。这次联合研究的主要成果是对自杀、铝化物和高温合金以及钢和合金等先进材料的腐蚀行为有了系统的了解。今后，这些知识可应用于喷气发动机和涡轮叶片的高温腐蚀问题，特别是氧化和硫化等内部腐蚀现象将得到控制。

Heat-resistant alloys used for turbines and boilers had tendency to suffer from severe corrosion at high temperatures. In particular, the energy conversion system is being operated in mixed gas environments containing O, S, and C1 as well as their compounds. In order to make elucidate aggressive corrosion of advanced materials such as intermettallies, super alloy, silicides and aluminide and so on, we made a research group between Hokkaido University and University of New South Wales In Australia. We had four meetings in these two years, and discussed about following topis : oxidation behavior of silicides by Kurokawa, oxidation and sulfidation of TiAl intermetallic compounds by Gleeson, Carburizing of steels and alloys by Young, Chlorination of Ni and Fe-based alloys by Sato, and Sulfidaiton behavior of aluminides by Narita.Through this joint research, we had many fruitful results. One of them is that oxidation or sulfidation in relative simple environments containing oxygen or sulfur is widely accepted to be understandable, however, there are still many unanswered questions of the corrosion behavior in mixed oxidant environments. Therefore, we need to go further investigation in order to make clear in addition to the thermodynamic and kinetic stand points.It is the chief fruit of this joint research that systematic understanding the aggressive corrosion of the advanced materials as suicide, aluminide and super alloy as well as steels and alloys were obtained. In future, the knowldges could be applied to corrosion problems of jet-engines and turbine blade at high temperature, and especially internal corrosions phenomena as oxidation and sulfidatlon will be controlled.