高矽含鉬球墨鑄鐵鋁塗層於熱浸鍍鋁的成長

Growth of Aluminide Coating on High Silicon Ductile Iron Alloyed with Molybdenum during Hot-dip Aluminizing

本研究採用高矽含鉬球墨鑄鐵於700℃進行熱浸鍍純鋁，探討矽和富鉬碳化物對鋁塗層的成長行為影響。實驗結果顯示，試片熱浸鋁後之塗層由外而內分別為外鋁層、鐵鋁介金屬層與夾雜在鐵鋁介金屬層和底材間的積矽層。積矽層的生成與鑄鐵本身的富鉬碳化物及層狀波來體皆會減緩鐵鋁介金屬層的成長。隨著熱浸時間增加，積矽層及富鉬碳化物各別會以矽顆粒及分解含鉬碳化物流出底材，導致外鋁層具有較大之厚度。

In this study, high silicon ductile iron alloyed with molybdenum was aluminized by hot-dipping into a pure aluminum bath at 700 ℃. The effect of silicon and Mo-rich carbides in the steel substrate on the growth behavior of aluminide coating was studied. The results showed that the aluminide coating consisted of three layers, Al outer layer, Fe-Al intermetallic layer and Si pile-up layer, from the coating surface to the substrate. The formation of Si pile-up layers after hot-dipping and the existences of Mo-rich carbides and laminated pearlite in the substrate have the same effect of reducing the growth of Fe-Al intermetallic layer. As the hot-dipping time increased, the Si pile-up layers and Mo-rich carbides decomposed into Si particles and Mo carbides and then flowed out from the steel substrate. This resulted in the Al outer layers possessed the larger thickness.