鉻含量對熱浸鋁化鉻鉬鋼中介金屬相形成之影響

Effect of Chromium on the Formation of Intermetallic Phase in Hot-dipped Aluminide Cr-Mo Steel

鄭維仁(W. J. Cheng) ； 朱慶霖(Q. L. Zhu) ； 溫仕寶(S. P. Wen) ； 陳丁誌(D. J. Chen) ； 王朝正(C. J. Wang)

《防蝕工程》 26卷4期 (2012/12) Pp. 211-218

https://doi.org/10.6376/JCCE.201212.0211

摘要

本研究採用不同鉻含量之鉻鉬鋼熱浸於700℃之純鋁與鋁-10矽（wt.%）熔湯中180秒，目的為探討鋼料中鉻含量對鋁化層中介金屬相形成之影響。研究結果顯示，各鋁化層皆可分為外側純鋁或鋁矽塗層及內側介金屬層。熱浸純鋁介金屬層由外側少量FeAl3與內側主要Fe2Al5相組成。含0與2.25 wt.%鉻鋼料熱浸鋁-10矽的介金屬層是由外側τ5(H)-Al7Fe2Si相與內側FeAl3/τ1-(Al,Si)5Fe3/Fe2Al5相組成，其純鋁塗層中則含有少量的多邊形τ5(H)-Al7Fe2Si相與針狀τ6-Al4FeSi相。含5與9 wt.%鉻鋼料熱浸鋁-10 wt.%矽的介金屬層為單一τ5(H)-Al7Fe2Si相，其上方鋁矽塗層具有許多散布顆粒τ5(C)-Al7(Fe,Cr)2Si相與少量板狀τ4-Al3FeSi2及τ6-Al4FeSi相。隨鋼料鉻含量超過2.25 wt.%，鉻含量越高會加速鋼料於熱浸鋁-10矽過程中的溶解。此乃因為鋼料的鉻會促使5(C)-Al7(Fe,Cr)2Si相的形成，進而加速鋁矽熔湯與鋼料的反應。

關鍵字

鉻含量 ； 鉻鉬鋼 ； 熱浸鍍鋁 ； 介金屬相

並列摘要

Cr-Mo steels with different chromium contents were coated by hot-dipping into molten baths containing pure aluminum and Al-10 wt.% Si for 180 seconds. The effect of chromium content in the steels on the formation of the intermetallic phases in the aluminide coatings was studied. The results show that all the aluminide coatings can be distinguished into an outer pure aluminum or Al-Si topcoat and an inner intermetallic layer. The intermetallic layers, resulting from the steels hot-dipped in purr aluminum, have the same phase constitution, an outer minor FeAl3 and an inner major Fe2Al5. In the aluminide coatings on the steels with 0 and 2.25 wt.% chromium after hot-dipping in Al-10 wt.% Si, the intermetallic layers were composed of an layer of outerτ5(H)-Al7Fe2Si and an inner one of FeAl3/τ1-(Al,Si)5Fe3/Fe2Al5, while a small amount of polyhcdraI τ5(H)-Al7Fe2Si and plate-shaped τ6-Al4FeSi were observed in the Al-Si topcoats. In the aluminide coatings on the steels with 5 and 9 wt.% chromium after hot-dipping in Al-10 wt.% Si, the intermetallic layers were composed of only aτ5(H)-Al7Fe2Si phase. A large amount of scattered granular τ5(C)-Al7(Fe,Cr)2Si and a small amount of plate-shaped τ4-Al3FeSi2 and τ6-Al4FeSi were also found in the Al-Si topcoats. When the chromium content exceeded 2.25 wt.%, the amount of steel, which dissolved when samples were hot-dipped in Al-10 wt.% Si, increased. Also, the rate of dissolving went up as chromium content went up. The increase of dissolution is because the interdiffusion between steels and Al-10 wt.% Si bath was enhanced by the formation of scattered granular τ5(C)-Al7(Fe,Cr)2Si, which was stabilized by chromium.

並列關鍵字

Chromium content ； Cr-Mo steel ； Hot-dip aluminizing ； Intermetallic phase