本研究是藉由無電鍍修飾AZ91D鎂合金表面生成具保護性的氧化鎂鍍層,並探討電解溶液對氧化鎂層之抗腐蝕性、結晶特性、組成成份、氧化鎂膜厚、硬度等性質。電解溶液中含有氫氧化鈉、矽酸鈉、磷酸、四硼酸鈉、檸檬酸鈉、二甲基乙醯胺。使用電子顯微鏡進行形貌分析、微氏硬度計、動態極化曲線(Tafel)分析氧化鎂層之抗蝕能力。抗腐蝕能力隨電位增加和極化時間減少而增加,氧化鎂膜厚和鍍層硬度也隨之增加,掃描電子顯微鏡發現電位降低和反應時間增加,容易造成表面結構鬆散,導致氧化鎂層無法穩定附著於鎂合金AZ91D。動態極化曲線分析,發現經無電鍍兩部處理後,可提高基材AZ91D鎂合金的抗腐蝕能力,說明抗腐蝕能力隨著電位的增加而增加。
MgO-silicon oxide film on AZ91D alloy was prepared in an alkaline silicate solution with additives (SiO2, NaOH and H3PO3) by plasma electrolytic oxidation (PEO). Additives in an alkaline solution inhibit spark intensity to form low breakdown voltage and smooth MgO-silicon oxide film on AZ91D alloy. Hence, the MgO-silicon on AZ91D alloy can improve corrosion resistance.MgO-silicon oxide film on AZ91D alloy, was prepared in the pre-treatment process of electroless method, have corrosion current density of 1.2 x 10-4 A/cm2 and long passive potential 4.2V. Moreover, the passive potential range increases with the increasing silicon atomic ratio in the MgO-film. Accordingly, silicon content in MgO-silsicon oxide film increases with the pre-treatment process of electroless method.