預鍍鎳對低碳鋼熱浸鋁化層其顯微結構與組成相之影響

Effect of Nickel Pre-plating on the Microstructure and Phase Constitution of a Hot-dipped Aluminide Coating on Mild Steels

鄭維仁(W. J. Cheng) ； 廖益樟(Y. J. Liao) ； 王朝正(C. J. Wang)

《防蝕工程》 25卷3期 (2011/09) Pp. 161-167

https://doi.org/10.6376/JCCE.201109.0161

摘要

本研究採用預鍍鎳之低碳鋼熱浸於670℃之純鋁鋁湯。藉由掃描式電子顯微鏡(scanning electron microscope, SEM)、X-ray繞射(X-ray diffraction, XRD)、能量分散光譜儀(energy dispersive X-ray spectroscopy, EDS)與電子背向繞射(electron backscatter diffraction, EBSD)技術，分析預鍍鎳對低碳鋼熱浸鋁化層其顯微結構與組成相之影響。研究結果顯示，低碳鋼上20μm之預鍍鎳層在經過熱浸5秒後將溶解爲12μm，並且在鎳層上方形成約5μm之連續Ni2Al3+NiAl3+(Fe, Ni)2Al9介金屬層與散布於純鋁塗層中的NiAl3相。當熱浸時間增加至60秒時，部分鎳鍍層被完全消耗完，使得Ni-Al相開始轉變爲FeAl3與(Fe, Ni)2Al9相。隨著熱浸時間持續增加，鋁化層將由外側少量的FeAl3與內側主要的Fe2Al5相組成。對照沒有預鍍鎳之低碳鋼熱浸鋁化層可以發現，在經過長時間熱浸後，預鍍鎳之介金屬層其組成相及厚度與無預鍍鎳之介金屬層相同。

關鍵字

預鍍鎳 ； 熱浸 ； 電子背向繞射 ； 鋁化層

並列摘要

A nickel pre-plated mild steel was coated by hot-dipping in a molten bath containing pure Al at 670℃. The effect of the pre-plated nickel layer on the microstructure and phase constitution of the aluminide layer was investigated using a combination of scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD). The results showed that the thickness of the nickel pre-plating layer was reduced from 20 μm to 12 μm due to dissolution after a hot-dipping of 5 seconds. Also, a continuous layer, composed of Ni2Al3+NiAl3+(Fe, Ni) 2Al9, formed above the nickel plating layer, while a small amount of NiAl3 phase scattered in the aluminium topcoat. In the aluminide layer after a hot-dipping of 60 seconds, a portion of the nickel plating layer was consumed, leading to phase transforms from Ni-Al to FeAl3 and (Fe, Ni) 2Al9. As the dipping time increased, the aluminide layer was composed of FeAl3 in a minor amount and Fe2Al5 in a major amount. In comparison with the mild steel hot-dipped with aluminide but without nickel pre-plating, the phase constitution and the thickness of the intermetallic layer with nickel pre-plating at a long dipping time were the same as those in the layer without nickel pre-plating.

並列關鍵字

Pre-nickel plating ； Hot-dipping ； EBSD ； Aluminide layer