鋁鎂合金表面披覆環氧樹脂／奈米碳管複合塗層之耐磨耗腐蝕性質

Electrochemical Study on the Wear-corrosion properties of Al-Mg Alloy with Epoxy/Carbon Nano-tube Composite Coating

本研究嘗試添加奈米碳管粉末於環氧樹脂中，以增加樹脂的導電性、耐腐蝕與磨耗腐蝕性。將此複合塗層塗佈於5083鋁鎂合金基材，以塊對環（Block-on-ring）表面摩擦方式在3.5wt% NaCl水溶液中施加負荷100 g、轉速100 rpm、磨耗60分鐘。並在0.5 M H2SO4 + 2 ppm NaF腐蝕環境下以電化學極化量測評估其耐腐蝕行為。實驗結果顯示環氧樹脂／多壁奈米碳管複合塗層有優越的耐腐蝕性，在奈米碳管達8%時電阻率可減低至9.96×10-2Ω．cm，相對於5083鋁鎂合金具有優異的腐蝕與磨耗腐蝕保護性行為（腐蝕電流密度只有0.746μA．cm-2），並且隨著奈米碳管的增加而減少了磨耗損失，在奈米碳管達16%時摩擦係數（μ）僅有0.052左右，比類鑽薄膜之摩擦係數（大約0.1）還要低。

The purpose of the present study is to evaluate the effect of epoxy/carbon nano-tube composite coating adding with different concentrations (4 ~ 20%) of multiple-wall carbon nanotube on the electrical conductivity, corrosion and wear-corrosion properties of 5083 Al-Mg alloy. The wear-corrosion test was performed in 3.5 wt.% NaCl solution by a block-on ring friction manner, with applied normal load of 100 g and wear rotation speed of 100 rpm. The wear-corrosion testing time was 60 min. Electrochemical potentiodynamic polarization was conducted in solution of 0.5 M H2SO4 + 2 ppm NaF to evaluate the corrosion behavior of specimens. The experimental results indicated that epoxy/ carbon nano-tube (CNT) has an excellent corrosion resistance behavior with high corrosion potential and low corrosion current density (0 .746 μA．cm-2). The epoxy/carbon nano-tube composite coating also showed an excellent wearcorrosion resistance, and the wear loss decreased with increasing concentration of CNT. When the concentration of CNT reached to 16% the friction coefficient (μ) of epoxy/carbon nano-tube composite coating was reduced to about 0.052, which was lower than that of diamond-like carbon (DLC) film (about 0.1).