将P92耐热钢、304不锈钢、316L不锈钢以及TMS75镍基合金以挂片方式浸泡在超临界NaCl水溶液中进行腐蚀试验, 通过分析氧化层的形貌、物相和成分, 对其腐蚀行为进行了对比研究。结果表明: P92耐热钢的腐蚀速率最大, 为20.37 mm·a-1, 304和316L不锈钢的腐蚀速率分别为6.27, 2.74 mm·a-1, TMS75镍基合金的腐蚀速率最小, 为0.67 mm·a-1; P92耐热钢表面氧化层存在大块状氧化皮, 顶部存在320 μm左右的氧化层; 304不锈钢和316L不锈钢表面氧化层中存在少量的氧化皮, 侧面不存在氧化层顶部存在很薄的氧化层; TMS75镍基合金的表面氧化层平整致密, 侧面氧化层厚约为180 μm, 顶面氧化层厚约为120 μm; 所有试样的氧化层中均存在穿插于氧化层中的针状NaCl, 它使P92耐热钢、304不锈钢和316L不锈钢的氧化层变得疏松、易脱落, 但对TMS75镍基合金的氧化层影响较小。

P92 heat resistant steel, 304 and 316L stainless steels, and TMS75 nickel-based alloy were immerged in supercritical NaCl aqueous solution through the coupon test, and the corrosion behaviors of them were analyzed by morphology, phase and chemical compositions of the corresponding oxide films. The results show that P92 heat resistant steel had the maximum corrosion rate of 20.37 mm·a-1, while the corrosion rates of 304 and 316L stainless steels were 6.27 mm·a-1 and 2.74 mm·a-1, respectively. In contrast, TMS75 nickel-based alloy had the minimum corrosion rate of 0.67 mm·a-1. Some big block oxide scales were observed on the oxide film surface of P92 heat resistant steel, and an oxide layer with a thickness of 320 μm was found on the top of it. There were a small amount of oxide scales on the surfaces of 304 and 316L stainless steels, no oxide film was found at the side of them and very thin oxide film existed on the top of them. The oxide film on TMS75 nickel-based alloy surface was smooth and compact, and the oxide film with the thickness of 180 μm and 120 μm existed both on the side and top of it, respectively. All the oxide films on the samples included acicular NaCl which interspersed in the oxide films, and thus made P92 heat resistant steel, 304 and 316L stainless steels become loose and easy to fall away from the metal substrates. However, the acicular NaCl had little influence on the oxide film on TMS75 nickel-based alloy surface.