鋁–鎂合金表面無電鍍鎳–奈米二氧化鈦與無電鍍鎳–奈米碳管的腐蝕性質

Corrosion Properties of Ni/nano-TiO2 and Ni/nano-CNT Composite Coatings Prepared by Electroless Plating on Al-Mg Alloys

本研究以無電鍍法，在無電鍍鎳液加入不同濃度（1 g/L、10 g/L）的奈米二氧化鈦（15 nm）及奈米碳管（5 nm）共同鍍析於5083鋁鎂合金基材表面上，以探討無電鍍鎳／奈米二氧化鈦與無電鍍鎳／奈米碳管複合鍍層於3.5 wt.% NaCl溶液下的耐腐蝕性。首先利用掃描式電子顯微鏡和X光能量散射分析儀，分析複合鍍膜表面形態與元素成分，再以原子力顯微鏡與奈米硬度量測系統觀察表面結構與量測表面硬度。以電化學動態極化法與浸漬腐蝕試驗量測分析鍍膜的耐腐蝕性。實驗結果顯示無電鍍鎳／奈米二氧化鈦及無電鍍鎳／奈米碳管濃度複合鍍層呈現均勻而緻密，都可改善鋁鎂合金的耐腐蝕性，也優於無電鍍鎳磷層，而在高濃度（10g/L）時奈米碳管的添加又比奈米二氧化鈦對於耐腐蝕性呈現較佳的改善效果。

The purpose of this study is to evaluate the corrosion resistance of electrolessly plated Ni/nano-TiO2 and Ni/CNT nano-composite coatings on AA5083 alloys in a 3.5 wt.% NaCl solution. The nano-composite coatings were prepared by electroless plating in which the nano- TiO2 (15 nm) and carbon nanotube (CNT, 5 nm) particles were added into the Ni plating solution with a low and a high concentrations of 1 g/L and 10 g/L for comparison. The corrosion properties of the nano-composite coatings were examined by potentiodynamic polarization and immersion corrosion tests. The experimental results indicated that both Ni/nano-TiO2 and Ni/CNT nanocomposite coatings exhibited a uniform and compact surface morphology, a high corrosion prevention ability for the AA5083 Al-Mg alloy substrate, and a superior corrosion resistance to the electroless Ni-P coating. The corrosion resistance of the nano-composite coatings was enhanced significantly when a high concentration of 10 g/L nano-TiO2 and CNT was introduced. In addition, the CNT added coating exhibited a superior corrosion characteristic as compared with that of the nano-TiO2 co-deposited one.