典型金属材料在硝酸熔盐环境中的腐蚀行为研究

Research on Corrosion Behavior of Typical Metal Materials in Molten Nitrate Salt Environment

通过熔盐浸泡实验研究了Q235碳钢、2.25Cr1Mo低合金钢、P91中合金钢、304和316不锈钢及Inconel617镍基合金在400℃硝酸熔盐(60%NaNO3+40%KNO3)中的静态腐蚀行为。通过测量试样腐蚀不同时间后的质量变化,得到了上述材料在高温熔盐环境中的腐蚀动力学曲线;利用扫描电镜(SEM)、X射线衍射仪(XRD)和能谱分析仪(EDS)对该材料在熔盐腐蚀过程中的腐蚀产物形貌、相结构和元素分布进行测试。结果表明,Q235碳钢的抗熔盐腐蚀能力极差,而Inconel 617镍基合金具有极强的抗熔盐腐蚀能力;同时,不同的腐蚀动力学曲线主要是由于材料表面氧化层结构不同;Q235钢表面氧化层主要由Fe2O3组成,不具有保护性;而含Cr合金材料表面会形成含有Cr的氧化物,具有较好的保护性;Inconel 617镍基合金由于表面形成了致密的Cr2O3和Ni O薄膜,所以具有极强的抗腐蚀能力。

The static corrosion behaviors of Q235 carbon steel, 2.25 Cr1 Mo low-alloy steel, P91 medium-alloy steel, 304 and 316 stainless steels and Inconel 617 alloy in nitrate molten salt(60% NaNO3+40% KNO3) environment at 400℃ were investigated by molten salt immersion experiments. The corrosion kinetic curves of the above materials in high temperature molten salt were obtained by measuring the weight changes of the specimens after corrosioning for different time. Moreover,scanning electron microscopy(SEM), X-ray diffractometer(XRD) and energy dispersive spectrometer(EDS) were used to analyze the morphologies, phase structures and elemental distribution of the corrosion products of the specimens in molten salt corrosion process. The results show that the corrosion resistance of Q235 steel to molten salt is the worst and that of Inconel617 Ni based alloy is the best. In addition, different corrosion kinetic curves are obtained because of different oxidation structures appearing on the surface of the materials. The surface oxide layer of Q235 steel is mainly composed of Fe2 O3, which does not have protection. The surface of Cr-containing alloys generates oxides with chromium, which has protection. Inconel617 nickel-based alloy has great corrosion resistance due to the formation of compact Cr2 O3 and Ni O film on its surface.