滲鋁處理對商用鋼材之熱腐蝕行為影響

The Hot Corrosion Behavior of Aluminized Commercial Steels

本研究利用800℃，4小時的固體封匣滲鋁處理，在S20C低碳鋼（S20C）、SUS430不銹鋼（430SS）與鐵錳鋁合金鋼（FMA）試片表面分別擴散生成FeAl相鋁化層，部分鋁化試片並再經過1000℃預氧化1小時之前處理。三種鋁化試片在900℃的90 wt%Na2SO4與10 wt%NaCl混合熔鹽中分別進行6、12與48小時之恆溫熱腐蝕。由實驗結果發現，鋁化之S20C試片由於鋁化層之鋁元素快速向基材與向外擴散，使得表層鋁化層消失而無法有效抵抗混合熔鹽之嚴重侵蝕。而滲鋁處理可以大幅提高430SS與FMA試片的抗腐蝕性能，其腐蝕反應速率常數達到10-11 g2cm-4sec-1的等級。此外，滲鋁後再經過1000℃預氧化處理的430SS與FMA試片可在表面生成α型氧化鋁層，更能有效的抵擋混合熔鹽的侵蝕。

The hot corrosion behavior of three commercial steels, including low carbon S20C steel (S20C), SUS430 stainless steel (430SS) and Fe-Mn-Al alloys (FMA) with pack aluminization treatment in Al-Fe powder at 800℃ for 4 hrs was studied at 900℃ with 90 wt%Na2SO4 and 10 wt%NaCl deposit. Some specimens were pre-oxidized at 1000℃ for 1 hr. The hot corrosion tests were conducted in the mixture of molten salt at 900℃ for 6, 12 and 48 hrs. It is found that the hot corrosion resistance of the aluminized low carbon S20C steel was very poor due to the spallation of aluminizing layer and rapid inward and outward diffusion of aluminum in the aluminizing layer. Only limited weight loss was found for the aluminized 430 SS and FMA specimens after test. The parabolic rate constant of these two alloys was around 10-11 g2cm-4sec-1. The hot corrosion resistance of the aluminized and preoxidized specimens of 430SS and FMA alloy was even better due to the protective α-Al2O3 layer formed on the surface.