Fe_3Al在1000℃1%SO_2+Ar中的灾难性腐蚀机制

MECHANISM ON CATASTROPHIC CORROSION OF Fe_3Al IN 1%SO_2+Ar AT 1000℃

研究了Fe_3Al在1％SO_2+Ar中1000℃时的腐蚀行为和机制。发现Fe_3Al在经过10～20min后发生失稳腐蚀。根据腐蚀层产物的结构及组成,从热力学和动力学角度对腐蚀机理进行了分析,表明在含硫混合气氛中形成的氧化膜中存在大量缺陷,基体/氧化膜界面严重贫铝,造成铁的硫化进而形成Fe-FeS共晶是发生灾难性腐蚀的主要原因。

Corrosion behavior and mechanism of Fe3Al in 1%SO2+Ar at 1000℃ were studied. It was shown that the alloy suffered catastrophic corrosion and orientated internal sulfidation although exhibiting quite good resistance to corrosion in the first 10-20min. Morphology, construction and composition of the scale on surface were investigated by SEM, EPMA and XRD. It was found that the upper scale formed in this atmosphere, which mainly consisted of FeS and Fe, had numerous defects. Mechanism of the catastrophic corrosion was discussed from the viewpoint of both thermodynamics and kinetics. It was proved that the main cause of the catastrophic corrosion occurrence was the formation of eutectic Fe-FeS by enrichment of Fe at base/scale and segregation of S through the scale full of defects .