材料期刊网

用涂 Na_2SO_4盐膜法研究高温合金 B-1900在827℃和750℃于空气中的热腐蚀行为,测定其腐蚀动力学曲线,用 X -射线衍射和电子探针元素面扫描方法分析腐蚀产物的相组成和成份,还对其中的水溶性离子进行化学定量分析。实验结果表明,Na_2SO_4沉积能引起 B-1900合金在中等温度下的热腐蚀,且腐蚀行为是灾难性的。基于实验结果,提出了 B-1900合金在中温下的热腐蚀机理。认为 MoO_3(可能以 Mo_2O_7~(2-)和 Mo_3O_(10)~(2-)形式)参与电化阴极还原反应。MoO_3和 MoO_3~(2-)在熔盐层中的相对迁移将 O_2的还原移至熔盐/空气交界面进行,从而导致快速热腐蚀的发生。熔盐中的 Na_2SO_4与MoO_3反应生成的 SO_3导致了熔盐的高酸度和合金内硫化,进一步加剧了热腐蚀的进程

Hot corrosion behavior of Na)2SO_4 coated B-1900 alloy was studied in air at 827 and 750℃.Corrosion kinetics of the coated alloy was gravimetrically measured,and contents of water soluble ions in the reaction products were chemically analyzed.X-ray diffraction and EMP techniques were employed to determine the components and morphology of the corrosion product scale.The experimental results indicate that B-1900 alloy is subject to catastrophic oxidation when covered with Na)2SO_4,and that the hot corrosion is related to the formation of molten Na_2SO_4-Na_2MoO_4-MoO_3 salt on the alloy surface.On the basis of experimental results a corrosion mechanism is proposed for the Na_2SO_4 induced hot corrosion of B-1900 alloy at intermediate temperat- ures.MoO_3(probably as Mo_2O~(2-)_7or Mo_3O~(2-)_(10))is believed to take part in the reduction reaction.The countertransport of MoO_3 and MoO~(2-)_3in the meit carries the reduction reaction of oxygen to the scale (melt)/air interface,which is responsible for the rapid corrosion.The high acidity of the melt and internal sulfidation of the alloy caused by SO_3 resulting from the reaction of Na_2SO_4 with MoO_3 enhance rapid hot corrosion.