本研究針對AZ91D鎂合金，使用鋯酸鹽基電解液漿料在定電流使用直流雙極脈衝模式下，進行電漿電解質氧化(Plasma Electrolytic Oxidation,PEO)實驗，控制電弧區(Arcing regime)及弱工作(火花區)(Soft sparking)影響之電性參數，及發生弱工作區對鍍鋯之影響機制，再回顧弱工作區及鋯酸鹽基氧化鋯的論文，可得知弱工作區的發生，建立各項電性參數[包含電流密度J(A/dm2)[J+=4.094/J-=-2.862(A/dm2)J+=5.434/J-=-4.71(A/dm2)]、正負電荷比Q+/Q-(Charge Ratio, CR)[0.58~0.92，以及正負電流比I+/I-(Current Ratio, IR)[0.88;1.15;1.43]等，探討其對氧化層生成速率、抗蝕特性與機械性質的影響。亦即藉由調控 PEO 過程中放電行為，運用軟火花(soft sparking)的成膜機制與電弧區的成相特徵，鍍製出緻密且抗蝕特性良好的氧化膜。選用的改良型鋯酸鹽漿料擬添加具備自我調適能力的奈米氧化鋯。為達到金屬/氧化物界面匹配，擬以電解質添加奈米顆粒鍍膜，並設計適當電性參數使中間層Mg2Zr5O12鎂鋯螢石相變厚；並藉由穿透式電子顯微鏡(TEM)等微觀分析手法，鑑別PEO氧化層相結構及形成機制，解析奈米氧化鋯顆粒如何與低溫相MgO反應並提升鎂合金機械強度與抗腐蝕能力。
實驗結果顯示，不同電流比、電荷比皆可得到不同的電弧區、弱工作區行為，在IR0.88時，陰極電流I-大於陽極電流I+，CR愈高，富氫環境下，亦即正電量固定時，負電量越小，氫氣量將受到負電量變化影響，改變氧化膜因氫被導通的速率，越快達成弱工作區條件；IR1.15時，陽極電流大於陰極電流，負電量大於正電量，負電量愈大，亦即CR0.58、0.75、0.92越快達成弱工作區條件。弱工作區將隨著CR值愈低，發生時間愈早。IR1.43時，正電量大於負電量，負電量愈大，弱工作區將提早發生。IR0.88時，雖於富氫環境，但因沒有能量產生燒結，故不會有二次起弧。IR1.15、1.43會有二次電壓的起伏，由斜率判定與電場強度之轟擊能量有關，可發現IR1.15的二次電弧區因電漿強度上升緩慢，對比於IR1.43因電漿強度較高，致使二次起弧斜率驟升，高能量使鍍膜速率增快。由此驗證氧化膜被導通後吸附的氧化鋯含量會增厚。經實驗時間45分鐘後， IR0.88，因負電量提高，無論CR如何改變，含鋯氧化膜平均厚度均為15μm；IR1.15，負電量提高，當CR降低，含鋯氧化膜平均厚度約為50μm增加到70μm； IR1.43，負電量變小，若CR提高，含鋯氧化膜平均厚度由34μm增長到91μm。但不同條件下總體厚度均可達到100μm。
為了比較基底電解液(氟鋯酸鉀)及添加奈米氧化鋯顆粒電解液，使用EDS、XRD及TEM分析電弧區及弱工作區的成相，在相同電性參數IR1.43、CR0.92，可由XRD及EDS確定了鋯成分的提升由原子百分比4.4%提升到19.2%，Mg2Zr5O12鎂鋯螢石相強度提升，TEM驗證於PEO高溫液態時，不穩定MgO將因短程有序，高能態會與奈米氧化鋯反應，形成穩定的Mg2Zr5O12化合物，將改善MgO結構強度不佳的問題，抗腐蝕能力將達到Rp1.535*107(Ω-cm2)，硬度提升至6.4(GPa)。
綜合所述，兩組電解液於實驗時間45分鐘，控制電弧區及弱工作區時間，可改變氧化及還原層厚度，電漿強度高，因添加奈米氧化鋯顆粒，燒結後高溫相Mg2Zr5O12強度將顯著提升，避免絕緣氧化層導通將是吾人將探討的重點，將抗腐蝕性及機械性質最好的IR1.43、CR0.92用TEM觀察在高溫時PEO於電弧區的反應會以奈米氧化鋯包覆MgO，改善結構不佳的問題。
控制電弧區及弱工作區調整氫及氧的含量，避免絕緣氧化層形成導通，膜層導電性上升，氧化膜層性質將下降，即使因斜率驟升，產生弧光是微米等級將燒結新的氧化膜覆蓋住已被導通之氧化膜，結果所示，有Soft Regime含氫缺陷之氧化膜，形成導通路徑，使膜層特性下降，於鋯酸鹽漿料應避免進入電壓崩潰。

The present study focuses on conducting Plasma Electrolytic Oxidation (PEO) experiments on AZ91D magnesium alloy using zirconia-based electrolyte plasma. The experiments are carried out under direct current bipolar pulse mode, specifically targeting the effects of the arc regime and soft sparking on the electrical parameters and the formation of zirconia coating. The aim is to investigate the mechanisms behind the occurrence of soft sparking and its influence on the electrical properties, oxidation rate, corrosion resistance, and mechanical properties of the coating. In this study, we seek to optimize the PEO process by controlling the discharge behavior, utilizing the soft sparking mechanism, and observing the phase characteristics in the arc regime. By implementing a two-step PEO treatment with different electrical parameters, we intend to obtain a dense and corrosion-resistant oxide coating that incorporates the advantages of different phases. This includes enhancing the coating thickness and mechanical properties while reducing roughness, surface porosity, and discharge channels to improve the corrosion resistance. To achieve this, we will use an improved zirconia-based electrolyte, which will contain self-adjusting nano-zirconia particles and stress-induced phase-change improved zirconia. To ensure compatibility between the metal/oxide interface, we plan to add nano-particles during the electrolytic coating process and design appropriate electrolyte parameters to achieve a thicker intermediate Mg2Zr5O12 magnesium zirconate phase. Microscopic analysis techniques such as Transmission Electron Microscopy (TEM) will be employed to identify the oxide layer's phase structure and formation mechanism and analyze how the nano-zirconia particles strengthen the low-temperature MgO phase, ultimately enhancing the mechanical strength and corrosion resistance of the magnesium alloy. Experimental results indicate that different arc and soft sparking behaviors can be achieved under various current ratios (IR) and charge ratios (CR). The occurrence of soft sparking is influenced by the hydrogen concentration, which is affected by the negative charge amount. Additionally, a second voltage fluctuation is observed under IR1.15 and IR1.43, which relates to the plasma intensity and bombardment energy. Furthermore, the addition of nano-zirconia particles results in increased zirconia content, leading to the formation of the stable Mg2Zr5O12 phase, which improves the MgO structure's strength and enhances the corrosion resistance. In conclusion, our study demonstrates that by controlling the arc and soft sparking time during the 45-minute experimental period and optimizing the plasma intensity through the addition of nano-zirconia particles, we can achieve varying oxide and reduction layer thickness. The higher plasma intensity facilitates the reaction between nano-zirconia and the low-temperature MgO, resulting in the formation of the stable Mg2Zr5O12 phase and improving corrosion resistance and mechanical properties. The focus of our future investigation will be on studying the behavior of the insulating oxide layer during high-temperature PEO under IR1.43 and CR0.92, utilizing TEM analysis to understand the interaction between nano-zirconia and poorly structured MgO. Overall, this research aims to advance the understanding and optimization of the PEO process for AZ91D magnesium alloy, resulting in a high-performance oxide coating with enhanced corrosion resistance and mechanical strength

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