P91和Super304H钢表面涂覆NaCl在高温水蒸汽中的腐蚀行为

在海洋性大气中，沉积在金属构件表面的NaCl在高温环境中可能导致金属加速腐蚀。在600 °C NaCl和水蒸汽环境中，研究了P91钢和Super304H钢的腐蚀行为。采用XRD，SEM/EDS对腐蚀产物膜相组成和形貌进行了分析。结果表明，P91钢和Super304H钢均表现为失重，受到严重腐蚀。样品表面的腐蚀产物层中有大量裂纹和孔洞，导致腐蚀产物大量剥落。P91钢表面腐蚀产物主要由Fe₂O₃组成。Super304H钢由 (Fe，Cr，Ni)₃O₄和NiO组成。由于Cr₂O₃膜在NaCl和高温水蒸汽中受到严重破坏，两种合金均遭到严重腐蚀，含Cr量较高的Super304H钢比P91钢腐蚀更严重，且有明显的晶间腐蚀发生。

Corrosion Behavior of Coated P91 Steel and Super304H Steel Beneath NaCl Deposit in High Temperature Water Vapor

Corrosion behavior of P91 steel and Super304H steel was studied beneath a solid NaCl deposit in water vapor containing air at 600 °C. The microstructure and composition of the corrosion products were characterized by XRD, SEM and EDS. Results indicated that both of P91 steel and Super304H steel suffered from disastrous corrosion with significant mass loss. Many cracks and voids were observed in the corrosion product scale, which led to spallation of corrosion products on a large scale. The corrosion product on the surface of P91 steel was mainly composed of Fe₂O₃. However, the corrosion products of Super304H steel contained (Fe, Cr, Ni)₃O₄ and NiO. The two steels suffered from serious corrosion may be ascribed to that the protective Cr₂O₃ oxide scale became not sustainable under the synergistic effect of solid NaCl with water vapor and oxygen at high temperature. Super304H steel with high Cr content suffered from more serious corrosion than that of P91 steel. Meanwhile, obvious intergranular corrosion of Super304H occurred.