高磷無電鍍鎳表面處理對7075-T6鋁合金機械與腐蝕性質之影響

Effects of Hgh-P Eectroless Nickel on Mechanical and Corrosion Properties of 7075-T6 Al-alloy

本研究以7075-T6鋁合金為基材，採用商用高磷含量無電鍍鎳方式，施以三種不同膜層厚度之表面處理，然後進一步分析與比較這些無電鍍鎳膜層的特性（結構、粗度、硬度、附著性等）及其拉伸、疲勞與腐蝕行為，以便了解高磷無電鍍鎳膜厚對7075-T6鋁合金機械性質（拉伸、疲勞強度）及耐蝕性的影響。實驗結果顯示隨著膜層厚度（3→7μm）的增加：（1）基材表面粗度及硬度會提高，但並不會影響其優異的附著性；（2）對抗拉強度有稍為提升約1.6%，但疲勞強度會下降達25%；（3）可增加在3.5 wt% NaCl溶液中之耐蝕性，且順序為3μm > 5μm > 7μm。

In this study, 7075-T6 Al-alloy was used as substrate to deposit ENi film with the different thicknesses by high-phosphor electroless nickel technology. And then film characteristics (such as structure, roughness, hardness and adhesion), tensile, fatigue and corrosive behaviors of the coated specimens were analyzed in order to understand the effect of ENi film thickness on the applied performance of 7075-T6 material. With the increase of film thickness from 3μm to 7μm, the results show as the follows: (1). Both the roughness and hardness properties of the substrate are raised, but the good adhesion of the film on the substrate has no deterioration. (2). It results in a slight raise about 1.6% in tensile strength; however, its fatigue strength is reduced up to 25%. (3). Corrosion resistance is evidently improved by ENi films in 3.5wt% NaCl aqueous medium, and they are in turn 3 μm-ENi > 5 μm-ENi > 7 μm-ENi.