研究了Ｆｅ－２０Ｃｒ－５Ａｌ和Ｆｅ－２０ＣｒＳＡｌ－０．５Ｙ合金在１２００℃ｌａｔｍＳＯ２气氛中热循环条件下的高温腐蚀行为，并与恒温腐蚀相比较．测定了腐蚀动力学曲线，观察腐蚀产物表面，横截面和脆断断口的形貌，并分析元素的分布，确定腐蚀产物相组成．结果表明，在５０００小时实验周期内，不含钇的合金遭受氧化／硫化腐蚀，腐蚀动力学呈直线规律．含钇合金只发生高温氧化反应，腐蚀动力学与恒温腐蚀时的差别不大，仍大体符合抛物线规律．加钇有效地抑制了Ａｌ３＋在α－Ａｌ２Ｏ３中的扩散，合金表面氧化膜依赖氧的传质而成长，发展出粘着性好的柱状晶，在交变热应力作用下不易开裂和剥落，显著提高了合金的耐蚀性．
High temperature corrosion behavior of Fe-20Cr-5Al and Fe-20Cr-SAl-0.5Y alloys under thermal cycling condition was studied in pure SO2 atmosphere at 1200 ℃, aug compared to that exhibited under isothermal condition. The corrosion kinatics of the alloys were measured. The morphologies of surfaces, cross sections and fractures of the corrosion product were examined, the elemed distribution in the corrosion scales was analyzed, and the components of the corrosion products were also identified. The results show that the yttrium-free alloy was subject to oxidation/sulfidation attack at a linear rate. In contrast,the yttrium-containing alloy underwent pure oxidation at a parabolic rate without sulfidation in the duration of 500 hrs. The yttrium doping, as a donor, in α-Al2O3 is believed to effectively block the bulk diffusion of Al3+ in the oxide scale due to a decrease in the Ali concentration. As a result, the oxide scale growth would rely entirely upon the oxygen diffusion down through the oxide grain boundaries, thus leading to the development of a fine, edhesive columnar Al2O3 layer with superior cracking and spallation resistance, even under thermal cycling condition. Consequently, the cyclic oxidation resistance of the alloy is remarkably improved.
参考文献
| [1] | 曹铁梁,潘辉英,董荷花,张允书．中国腐蚀与防护学报,1992,12:1162WoodGC,ScottFH．inHighTemperatureCorrosion,NACE-6,RappRA．ed．Houston:NACE,1983,p2773ButtBV,KvogerFA．J．Amer．Ceram．Soc,1975,58:4744EI-AlatMM．KroecrFA．Ibid．．1982．65:280 |
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