添加過錳酸鉀對電漿電解氧化法製備氧化鋁膜之影響

Effects of KMnO4-added Electrolytes on Alumina Coatings Prepared by Plasma Electrolytic Oxidation

本研究主要是將6061-T6鋁合金置於0.1 M鋁酸鈉與不同濃度的過錳酸鉀（0.8 mM-3 mM）溶液中，利用電漿電解氧化法，於鋁合金上製備氧化鋁膜。電流密度固定為10 A/dm2，當過錳酸鉀濃度在0.8 mM- 3 mM時，火花放電會產生延遲的現象。反應後的試片呈現黃色外觀，由X光繞射之分析結果顯示，氧化鋁膜之結晶相主要為α-Al2O3和γ-Al2O3。當添加0.8 mM過錳酸鉀時，膜厚與粗糙度會隨著處理時間的增加而增加，當反應時間為60分鐘時，膜厚可達51μm，且具有較高的腐蝕電位與極化阻抗，可用做防腐蝕膜層材料之應用。

The object of this work is to synthesize alumina coatings by plasma electrolytic oxidation (PEO) on 6061-T6 Al alloys. Electrolytes (0.1M NaAlO2) with small amounts of KMnO4 ranging form 0.8 to 3.0 mM were employed during PEO at a constant current density of 10 A/dm2. With the added KMnO4 of 0.8-3.0 mM, the onset of spark discharge was delayed. The coatings revealed yellow color. X-ray diffraction results showed the obtained coatings consisted mainly of α-Al2O3 and γ-Al2O3 phases. As the concentration of the added KMnO4 was raised to above 0.8 mM, the thickness and roughness of the coatings increased rapidly with time. The coatings prepared by PEO with 0.8 mM added KMnO4 for 60 minute reached 51 μm and exhibited excellent corrosion resistance in terms of potential, as well as impedance. The coatings may be applied to corrosion protection applications.