本研究藉由電鍍法,在7075-T6鋁合金表面經陽極處理後,沉積電鍍鎳-奈米二氧化鈦複合鍍層,分析鍍膜的結構與機械性質,並探討電鍍鎳-奈米二氧化鈦複合鍍層在3.5%NaCl溶液中之耐腐蝕與耐磨耗腐蝕性。 實驗中使用7075-T6鋁合金原基材經陽極處理,陽極處理操作條件分別為鍍液溫度(50℃~55℃)、陽極電位(-0.75V、-1V、-1.25V、-1.5V)、陽極處理時間1800秒,再於電鍍鎳液中添加奈米二氧化鈦(濃度為1g/L、10g/L),進行電鍍鎳-奈米二氧化鈦30分鐘。然後以掃描式電子顯微鏡(SEM)及X光能量散射分析儀(EDS) 、維克氏微硬度試驗機(Hv)等,觀察鍍膜表面的形態、鍍層的元素成份分析、量測表面硬度。使用以塊對環(Block-on-ring)摩擦方式在3.5%NaCl中進行磨耗腐蝕試驗,也在3.5%NaCl溶液中進行腐蝕性質試驗,包括:浸漬試驗與電化學動態極化法。 研究結果顯示7075-T6鋁合金表面經陽極處理後硬度值增加,而試片經陽極處理後,發現在電鍍鎳液中能有效的增加鍍層表面晶粒均勻附著及硬度值、表面粗糙度大為降低。電鍍鎳層因加入奈米二氧化鈦,尤其在高濃度(10g/L)時,更能增加鍍膜之耐腐蝕與耐磨耗腐蝕性,適當的陽極處理將能有效提升電鍍鎳-奈米二氧化鈦複合鍍層的沉積效率、光滑度、緻密性與附著性,因而對於表面硬度、耐腐蝕與耐磨耗腐蝕性等均有顯著的改進效果。
This study used electroplating process to prepare Ni/nano-TiO2 composite coating on 7075-T6 aluminum alloy surface after various anodizing treatments (anodizing potentials: -0.75V、-1V、-1.25V、-1.5V; anodizing time:1800s) to obtain a medium layer, then performing the electroplating in 30 min by adding 1 g/L and 10 g/L TiO2 (15nm) to nickel plating solution. The surface morphology, element composition and surface hardness of the coatings were analyzed by using SEM, EDS and Vicker’s hardness tester. The corrosion and wear-corrosion resistance of electroplating Ni/nano-TiO2 composite coating in 3.5% NaCl solution was evaluated, also discussing with the related micro-structural analysis results. Experimental results indicated that electroplating Ni/nano-TiO2 composite coating has high hardness, good corrosion resistance, particularly owing to the anodizing treatment of aluminum alloy. The anodizing treatment of 7075-T6 aluminum alloy substrate efficiently improved the adhesion, surface morphology and hardness of the electroplated Ni/nano-TiO2 composite coating. The optimal anodizing condition was at anodizing potential of -1V, time of 1800s. The incorporation of TiO2 at high concentration of 10 g/L significantly increased the corrosion and wear-corrosion resistance of Ni/nano-TiO2 composite coating in 3.5 wt.% NaCl solution.