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脈衝電流對 6061 鋁合金電漿電解氧化鍍層之機械性質及耐蝕性影響研究 = Effects of pulsed currents on mechanical properties and corrosion behaviors of plasma electrolytic oxidation coatings on 6061 aluminum alloy / 王翔禾.

館藏資訊

摘要註

本研究利用電漿電解氧化(PEO)技術，於鹼性矽酸鈉水溶液中進行6061鋁合金表面改質處理，並探討不同陰極與陽極電流對PEO鍍層之耐蝕性的影響。利用XRD、SEM、EDS、刮痕試驗、pin-on-disk磨耗試驗及動電位極化曲線量測，來分析PEO鍍層的顯微組織、機械性質及耐蝕性。實驗結果顯示：PEO鍍層厚度隨著陰極與陽極電流提升明顯增加，陽極電流的提升可以使鍍層生長速度更快，陽極電流從1A提升至5A鍍層厚度從7.39µm提升至20.74µm，但透過刮痕試驗以及磨耗試驗發現，陽極電流的提升雖可以得到更厚的鍍層，但在機械性質方面較陰極電流提升來的差，陰極電流提升鍍層生長速度較慢，陰極電流1A提升至5A鍍層厚度從11.13µm提升至17.12µm，但鍍層緻密性較陽極電流提升來的好，在機械性質及耐腐蝕性皆顯示出良好的結果。同時探討不同製程階段 PEO鍍層之顯微結構、機械性質及耐蝕性。製程初期20秒時陽極化階段形成約0.5µm厚的緻密氧化層，當達到100秒時鍍層厚度提升至約2µm， 鍍層中可以發現微弧放電過程形成的氣孔洞。隨著製程時間的增加，鍍層的孔洞尺寸及密度明顯增加，而製程時間為300秒時，鍍層厚度增加至約7.4µm，可以發現鍍層出現U形凹孔。最後，製程時間達到600秒時，鍍層厚度增加至約16.8µm，先前出現U形凹孔會被熔融的氧化物所填補。刮痕試驗結果顯示，PEO鍍層的臨界附著力LC2值隨製程時間增加而增加，從製程初期6N提升到21N。動電位極化曲線量測結果顯示，不同製程階段PEO鍍層於3.5wt% NaCl水溶液中，以製程時間600秒的PEO鍍層具有最低的鈍態電流密度及相對寬廣的鈍化區，其鍍層耐蝕性最佳，然而， 製程時間為300秒的PEO鍍層由於出現U形凹孔導致其耐蝕性相較其他製程時間的鍍層來得差。. This study utilized plasma electrolytic oxidation (PEO) technique to modify the surface of 6061 aluminum alloy in a sodium silicate alkaline solution, and investigated the influence of different cathodic and anodic currents on the corrosion resistance of PEO coatings. Microstructural analysis, including XRD, SEM, EDS, scratch testing, pin-on-disk wear testing, and potentiodynamic polarization curve measurement, were conducted to analyze the microstructure, mechanical properties, and corrosion resistance of PEO coatings. The experimental results showed that the thickness of PEO coatings significantly increased with the increase of cathodic and anodic currents. Increasing the anodic current resulted in a faster coating growth rate, where the coating thickness increased from 7.39 µm to 20.74 µm when the anodic current was increased from 1A to 5A. However, scratch testing and wear testing revealed that although higher anodic currents led to thicker coatings, they exhibited inferior mechanical properties compared to coatings with higher cathodic currents. Increasing the cathodic current resulted in slower coating growth, where the coating thickness increased from 11.13 µm to 17.12 µm when the cathodic current was increased from 1A to 5A. However, coatings with higher cathodic currents showed better coating density, and exhibited good mechanical properties and corrosion resistance. Furthermore, the microstructure, mechanical properties, and corrosion resistance of PEO coatings at different process stages were investigated. During the initial 20 seconds of the process, an anodization stage formed a dense oxide layer of approximately 0.5 µm. By reaching 100 seconds, the coating thickness increased to approximately 2 µm, and pores formed due to micro-arc discharge were observed in the coating. With the increase in process time, the pore size and density of the coating significantly increased. At 300 seconds, the coating thickness increased to approximately 7.4 µm,

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