NiAl seal coating was prepared on the superalloy substrate by air plasma spraying method.The galvanic corrosion behavior in 5 ％ (mass fraction) NaCl solution was investigated for the NiAl seal coating and superalloy substrate.The measurement methods,which consisted of scanning electron microscopy (SEM),polarization curve and open circuit potential,were used to character the morphology and the corrosion behavior of the coating.The results indicated that the galvanic current density was about 2.1356μA/cm2.The NiAl coating with more negative corrosion potential served as the couple's anode and it had seriously corrosion,loosen and floccus corrosion products covered on the coating 's surface.In the as-sprayed NiAl seal coating,there existed many pores and oxides,and corrosion was easy to occur in the area lack of oxide coverage.While the oxides which on the edge of the coating were priority dissolved,and the corrosion products would block the pores and inhibit the corrosion process.The protection performance of the coating was weaken gradually with the extention of corrosion time.%采用空气等离子喷涂工艺在高温合金基体上制备了NiAl封严涂层.研究了NiAl涂层/高温合金在5％(质量分数)NaCl溶液中的电偶腐蚀行为,结合极化曲线、开路电位和SEM形貌检测,探讨封严涂层的腐蚀机理.结果表明,高温合金基体与NiAl涂层的电偶电流密度为2.1356,μA/cm2,电位较负的NiAl涂层作为电偶对的阳极,腐蚀更严重,腐蚀产物疏松呈絮状覆盖在涂层表面.等离子喷涂的NiAl涂层含有较多的孔隙和氧化物,腐蚀容易在缺少氧化物覆盖的区域发生.NiAl涂层边缘的氧化物也容易优先溶解,形成腐蚀产物膜,堵塞涂层微孔,抑制腐蚀的进行.随着腐蚀时间延长,NiAl涂层的防护性能逐渐减弱.
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