本研究於低碳鋼表面以電鍍方式鍍鎳層後進行熱浸鍍純鋁後，於750 ℃靜滯空氣進行恆溫氧化、熱循環實驗與氯化鈉高溫腐蝕實驗。探討鎳鋁化塗層之相變化過程、動力學、氯化鈉高溫腐蝕與空氣氧化之差異，並與低碳鋼熱浸鍍純鋁比較兩者鍍層之抗氧化性及熱循環之行為，同時探討低碳鋼熱浸鍍純鋁，鋁化層中AlN的生成原因。
　　實驗結果顯示，預鍍鎳低碳鋼熱浸鋁化塗層，由表面至基材分別為純鋁塗層、NiAl3、Ni2Al3、NiAl、Ni3Al與純鎳層。經短時間擴散後，純鋁塗層與NiAl3轉變為Ni2Al3，經120小時擴散，大部份Ni2Al3變為NiAl相。鎳鋁化層中的鎳鋁交互擴散，在NiAl比Ni3Al有較低的活化能障，造成其成長速率較高。預鍍鎳低碳鋼熱浸鍍鋁低碳鋼熱浸鍍純鋁相比，在高溫空氣環境具有較優異的抗氧化性與受熱循環後之表現。
　　預鍍鎳低碳鋼熱浸鋁經氯化鈉高溫腐蝕，由於氯化鈉與鎳、鋁之反應速率不同，較多量的鋁被消耗，表面主要由NiAl相組成。低碳鋼熱浸鋁化層在高溫空氣氧化時，大氣中的氮會進Fe2Al5，當Fe2Al5轉變成為B2結構的FeAl相，由於溶解度的降低，針狀AlN析出於FeAl相中。

The purpose of this study is to investigate the nickel-plating effects under various Ni-Al and Fe-Al layers on phase transformation, corrosion kinetics, and thermal-cycling oxidation behavior of hot-dipping low-carbon steel at 750 ℃ in dry air with and without NaCl deposits. The results will compare to those of the same steel directly hot-dipped Al (without Ni-plating), and discuss the possible reasons to form AlN in the substrate after air oxidation.
The results showed that the Ni-Al layers formed from top coating to the substrate consisted of NiAl3, Ni2Al3, NiAl, Ni3Al, and pure-nickel layers. The NiAl3, layer was transferred into the Ni2Al3 layer after an initial inter-diffusion reason about 20 min, while most the Ni2Al3 phase was transferred into the NiAl phase after a 120-hr exposure. Due to the lower activation energies to grow both NiAl and Ni3Al phases, their growth rates were much faster than those of other Ni-Al phases. It was found that the steel with nickel-plating treatment exhibited an excellent oxidation and thermal-cycling resistance with respect to that of the free nickel-plating steel.
In addition, the surface of the nickel-plating steel became mostly NiAl phase after hot corrosion at 750 ℃ when mostly Al was preferential consumed under a reaction with NaCl. Besides, the AlN precipitates formed on the Ni-plating steel after the oxidation in dry air. Very likely, the observed AlN was due mostly to reducing the nitrogen solubility in the substrate when the Fe2Al5 phase transferred into FeAl, which in turn caused inward diffusion of nitrogen into the substrate and reacted with Al to form AlN.

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