High temperature corrosion of hot-dip aluminized steel in Ar/1%SO₂ gas

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• 作者：Muhammad Ali Abro ; Dong Bok Lee
• 关键词：metals ; surface modification ; oxidation ; scanning electron microscopy (SEM) ; Al hot ; dipping
• 刊名：Metals and Materials International
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：23
• 期：1
• 页码：92-97
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Metallic Materials; Operating Procedures, Materials Treatment; Magnetism, Magnetic Materials; Engineering Thermodynamics, Heat and Mass Transfer; Characterization and Evaluation of Materials; Continuu
• 出版者：The Korean Institute of Metals and Materials
• ISSN：2005-4149
• 卷排序：23

文摘

Carbon steels were hot-dip aluminized in Al or Al-1at%Si baths, and corroded in Ar/1%SO₂ gas at 700-800 °C for up to 50 h. The aluminized layers consisted of not only an outer Al(Fe) topcoat that had interdispersed needle-like Al₃Fe particles but also an inner Al-Fe alloy layer that consisted of an outer Al₃Fe layer and an inner Al₅Fe₂ layer. The Si addition in the bath made the Al(Fe) topcoat thin and nonuniform, smoothened the tongue-like interface between the Al-Fe alloy layer and the substrate, and increased the microhardness of the aluminized layer. The aluminized steels exhibited good corrosion resistance by forming thin α-Al₂O₃ scales, along with a minor amount of iron oxides on the surface. The interdiffusion that occurred during heating made the aluminized layer thick and diffuse, resulting in the formation of Al₅Fe₂, AlFe and AlFe₃ layers. It also smoothened the tongue-like interface, and decreased the microhardness of the aluminized layer. The non-aluminized steel formed thick, nonadherent, nonprotective (Fe₃O₄, FeS)-mixed scales.