MEVVA離子源植入Cr對被覆CrN鋼材腐蝕阻抗的電化學研究

Effect of MEVVA Implanted Cr on the Electrochemical Dehavior of CrN Coated Steel

使用陰極電弧法沉積CrN硬質膜為增強鋼材抗磨耗及抗腐蝕的能力的有效方法，金屬蒸氣真空電弧離子源（MEVVA），則常被用於材料表面改質。本研究用MEVVA植入Cr於AISI 4140 低碳合金鋼基材再以陰極電弧法被覆CrN膜（CrN／Cr／steel），與只被覆CrN膜（CrN／steel）的試片於0.1N HCl進行腐蝕測試，以了解MEVVA植入鉻離子對於鋼材被覆CrN鋼材腐蝕行為的影響。以TEM方法了解CrN的結構，並藉由電化學交流阻抗頻譜法（EIS）量測腐蝕阻抗。並使用等效電路分析阻抗圖譜，瞭解植入Cr對被覆CrN鋼材腐蝕機制之影響。採用一般物理氣相沉積法沉積CrN膜均易產生柱狀晶結構且產生一定數目的缺陷，在腐蝕環境中將成為腐蝕性物質腐蝕鋼材的途徑。以EPMA觀察腐蝕測試後的試片微結構，並與電化學分析的結果比較，得知MEVVA離子源植入Cr抑制鋼材腐蝕速率，因而降低了沉積CrN膜過程中的孔洞等缺陷造成對鋼材的抗時的影響，大幅增強被覆CrN鋼材腐蝕能力。

Cathodic arc plasma deposition of CrN coating has been explored and extensively applied to improve the wear and corrosion resistance of the steel. Metal vapor vacuum arc (MEVVA) source implantation coupled with the cathodic arc plasma is a very attractive process for surface modification in this study. The effect of the Cr implanted by MEVVA on the corrosion resistance of CrN/steel was evaluated. Two assemblies derived from AISI 4140 i.e. CrN/steel and CrN / Cr /steel were evaluated in an aerated 0.1N HCl solution. The crystal structure for the MEVVA implanted Cr and cathodic arc deposited CrN on steel were studied by TEM. The corrosion resistance for all assemblies was measured using electrochemical impedance spectroscopy (EIS), simulated by the equivalent circuit to interpret the effect of Cr-implanted on corrosion mechanism of CrN / Cr / steel. The corrosion products associated with the microstructures were examined by EPMA. The results indicated that the corrosion resistance of steel is significantly enhanced by MEVVA implanted Cr through the reduction of corrosive path on the outmost coating of CrN.