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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
The corrosion behavior of superalloy B-1900 in air at 827 ℃ and 750 ℃ was investigated by Na_2SO_4 salt film method. The corrosion kinetics curves were measured and the corrosion products were analyzed by X - ray diffraction and electron probe element surface scanning Phase composition and composition, but also one of the water-soluble ions for chemical quantitative analysis. The experimental results show that the deposition of Na_2SO_4 can cause hot corrosion of B-1900 alloy at moderate temperature, and the corrosion behavior is disastrous. Based on the experimental results, the hot corrosion mechanism of B-1900 alloy at middle temperature is proposed. It is considered that MoO_3 (probably in the form of Mo_2O_7 ~ (2-) and Mo_3O_ (10) ~ (2-)) is involved in the electrochemical cathodic reduction reaction. The relative migration of MoO_3 and MoO_3 ~ (2-) in the molten salt layer shifts the reduction of O_2 to the molten salt / air interface, resulting in rapid thermal corrosion. SO_3 produced by the reaction of Na_2SO_4 and MoO_3 in molten salt leads to high acidity and intra-alloy sulfidation of molten salt, further aggravating the process of hot corrosion