本論文將探討脈衝波型對6061鋁合金進行微弧氧化鍍製ZrO2/Al2O3複合陶瓷膜之影響與機制探討，在調配好之鹼性含氟鋯酸鉀澄清電解液中以固定脈衝頻率1000 Hz、定電壓模式+400 V/-100 V下鍍製一小時，改變占空比及各占空比下之脈衝波型，對膜層之表面形貌、斷面結構、電流變化、膜層成相、成膜機制與機械性質進行討論，本論文中的正、負脈衝比例以脈衝波型中正、負脈衝面積表示，計算方法為(V+ * T+on)/(V- * T-on)。
在占空比50%與30%中改變脈衝波型發現，當正、負脈衝的比例較小時，膜層呈現火山孔形貌的緻密膜層，且膜層中含有較多氧化鋯與氧化鋁相，而在比例較大時呈現表面多微小細孔之多孔膜，膜層則多為氧化鋁相，可知在占空比50%與30%可透過脈衝波型的調整來控制膜層形態。在占空比10%與70%時，則受限於鍍膜能量過小及過大，導致膜層為表面多微小細孔之多孔膜，膜層中也以氧化鋁為主。根據電流變化發現，陰極電流會牽制陽極電流的變化，當T-on時間較長時，陰極電流越大，到了實驗後期會影響陽極電流，使其產生小區間(0.2~0.4 A)不穩定的跳動現象，當有此現象發生時有助於膜層緻密化。
本論文使用非對稱雙極脈衝定電壓模式，在脈衝中T+on階段扮演熔融基材擊穿膜層的角色，T-on階段則不僅消除試片表面的電荷累積，同時會吸引電解液中陽離子(Zr4+)過來燒結堆積，從斷面的元素線掃描發現，膜外層多為電解液中元素的相(富鋯)，膜內層多為基材元素的相(富鋁)，搭配XRD的相成分分析可知其為氧化鋯與氧化鋁，但是微弧氧化製程中伴隨高溫高能量的電漿反應，在迅速冷卻的情況下，使原本不易與氧化鋯作用的鋁固溶進入其晶格當中，因此，此處的氧化鋯形成t相的鋁鋯氧結構。
整體來說，若要鍍製對基材保護性佳的緻密膜層，可選擇占空比50%中正、負脈衝比例較小者，其平均硬度值可達1000 Hv以上，最高可到1400 Hv，腐蝕阻抗可到108，比起鋁合金基材提升了105倍，若要生醫方面的應用，如細胞培養與催化作用，則可選擇占空比30%中正、負比例較大者，其膜層表面佈滿< 1 μm的細孔。

In this study, asymmetric bipolar pulse with constant voltage (V+ = +400 V, V- = -100 V) and 1000 Hz pulse frequency were used to produce ZrO2/Al2O3 ceramic coatings on 6061 aluminium substrate using microarc discharge oxidation (MDO) for one hour. The electrolytes contain NaOH, NaAlO2, K2ZrF6, and (NaPO3)6. The concentration of electrolyte composition have to be adjusted in order to avoid Zr(OH)4 white particles precipitation in different working conditions. Characterization were done using SEM, XRD, variation of current, Raman spectrometer, and mechanical properties measurement, showed that the pulse wave form has great influence on the coatings morphology, microstructure, and phase structure. The experiment results explains the mechanism of coatings. Ratio of positive and negative pulses calculated as (V+ * T+on) / (V- * T-on).
Variation of duty ratio of 50% and 30%, shows that when the ratio of positive and negative pulse smaller, the oxide coatings shows volcanic morphology and denser. The coatings also contain more zirconia oxide and aluminum oxide phase. On the contrary, when the larger ratio of positive and negative pulse, produces coatings with full of tiny pores on the surface and porous layer which mainly consist of alumina phase. Duty ratio of 50% and 30% can change the film morphology by pulse adjustment. Duty ratio of 10% and 70%, the coating energy is too small and too large. Therefore, microporous surface were formed because of this. The coatings mainly consist of alumina phase. From the current variation experiment, it is found that the cathode current can influence the anode current. When longer T-on was applied, the cathode current was increased. At later stage the anode current produce inter-cell (0.2~0.4 A) unstable chattering, which helps the film densification.
By using asymmetric bipolar pulse constant voltage mode, the T+on stage plays a big role in the formation of molten substrate. The T-on stage not only eliminates charge accumulation on specimen surface, but also attract the electrolyte cation (Zr4+) into the oxide film by sintering. It has been discovered from the cross section element line scan that outer layer contains more elements from the electrolytes (zirconium-rich). On the other hand, inner layer contains more elements from the substrates (aluminum-rich). XRD analysis shows that the coatings contains ZrO2 and Al2O3 phases. During the micro-arc oxidation process, high-energy and high-temperature plasma were occurred. This phenomenon causes to rapid cooling which leads to the formation of tetragonal phase aluminium solid solution in zirconium oxide lattice.
In summary, these results show that protective dense layer was formed when smaller ratio of positive and negative in duty ratio 50% was applied. The average hardness value is 1000 Hv but the highest hardness value which has been obtained in this experiment is up to 1400 Hv. The corrosion impedance is about 108, which is 105 times better than substrate without coating. For the biomedical field application, such as cell culture and catalysis, the larger ratio of positive and negative in duty ratio 30% should be used to produce coatings surface with <1 μm pores.

[1]東青, 陳傳忠, 王德雲, 雷廷權, ”鋁及其合金的微弧氧化技術”, 中國表面工程, vol 18, no 6, 2005.
[2]Zhijiang Wang, Lina Wu, Wei Cai, Shan A, Zhaohua Jiang, ”Effect of fluoride on the structure and properties of microarc oxidation coating on aluminium alloy” Journal of Alloys and Compounds 505,188-193, 2010.
[3]X. Nie, A. Leyland, H.W. Song, A.L. Yerokhin, S.J. Dowey, A. Matthews, ”Thickness effects on the mechanical properties of micro-arc discharge oxide coatings on aluminium alloys” Surface and Coatings Technology 116-119, 1055-1060, 1999.
[4]Mehmet Tarakci, ”Plasma electrolytic oxidation coating of synthetic Al-Mg binary alloys” Materials Characterization 62, 1214-1221, 2011.
[5]L. Rama Krishna, A. Sudha Purnima, G. Sundararajan, ”A Comparative study of tribological behavior of microarc oxidation and hard-anodized coatings”, Wear 261, 1095-1101, 2006.
[6]劉文海, ”鋁合金表面處理技術發展動向(一)、(二)”, 金屬中心ITIS計畫, 2011.
[7]WenBin Xue, ZhiWei Deng, RuYi Chen, TongHe Zhang, Hui Ma, ”Microstructure and properties of ceramic coatings produced on 2024 aluminum alloy by microarc oxidation”, Journal of Materials Science 36, 2615-2619, 2001.
[8]John E. HATCH, ALUMINUM, 1984.
[9]Miao Jing-guo, Wu Run, Hao Kang-da, Chen Qiu-rong, Dong Xiang-yun, ”Effects of alloying elements on structure of plasma electrolytic oxidation ceramic coatings on aluminum alloys”, Applied Mechanics and Materials, vol 310, 85-89, 2013.
[10]K. Tillous, T. Toll-Duchanoy, E. Bauer-Grosse, L. Hericher, G. Geandier, ”Microstructure and phase composition of microarc oxidation surface layers formed on aluminium and its alloys 2214-T6 and 7050-T74”, Surface & Coatings Technology 203, 2969-2973, 2009.
[11]Yong-Jun Oh, Jung-Il Mun, Jung-Hwan Kim, ”Effects of alloying elements on microstructure and protective properties of Al2O3 coatings formed on aluminum alloy substrates by plasma electrolysis”, Surface & Coatings Technology 204, 141-148, 2009.
[12]香港利記集團科技及物流中心, ”各元素對鋁合金的作用”, 利保金屬檢測中心.
[13]曾國輝, 李九龍, ”鋁合金微弧氧化陶瓷膜層性質之研究”, 龍華科技大學學報, 二十二期, 2007.
[14]H. Y. Zheng, Y. K. Wang, B. S. Li, G. R. Han, ”The effects of Na2WO4 concentration on the properties of microarc oxidation coatings on aluminum alloy”, Materials Letters 59, 139-142, 2005.
[15]A. L. Yerokhin, X. Nie, A. Leyland, A. Matthews, S. J. Dowey, ”Plasma electrolysis for surface engineering”, Surface and Coatings Technology 122, 73-93, 1999.
[16]薛文斌, 鄧至威, 來永春, 陳如意, 張通和, ”有色金屬表面微弧氧化技術評述”, 金屬熱處理, 2000.
[17]徐榮, ”利用雙極脈衝電源微弧氧化法探討占空比和頻率對於7075-T6鋁合金表面氧化膜層之影響”, 大同大學碩士論文, 2009.
[18]Jun-Hua Wang, Mao-Hua Du, Fu-Zhu Han, Jing Yang, ”Effects of the ratio of anodic and cathodic currents on the characteristics of micro-arc oxidation ceramic coatings on Al alloys”, Applied Surface Science 292, 658-664, 2014.
[19]Yang Guangliang, Lu Xianyi, Bai Yizhen, Cui Haifeng, Jin Zengsun, ”The effects of current density on the phase composition and microstructure properties of micro-arc oxidation coating”, Journal of Alloys and Compounds 345, 196-200, 2002.
[20]L. O. Snizhko, A. L. Yerokhin, A. Pilkington, N. L. Gurevina, D. O. Misnyankin, A. Leyland, A. Matthews, ”Anodic processes in plasma electrolytic oxidation of aluminium in alkaline solutions”, Electrochimica Acta 49, 2085-2095, 2004.
[21]T. Mi, B. Jiang, Z. Liu, L. Fan, ”Plasma formation mechanism of microarc oxidation”, Electrochimica Acta 123, 369-377, 2014.
[22]陳麒元, ”利用微弧氧化法在6061鋁合金上鍍製ZrO2/Al2O3氧化膜之研究”, 國立台灣科技大學碩士論文, 2014.
[23]陳永錄, ”以微弧氧化法於AZ91D鎂合金上鍍製矽酸鹽及鋯酸鹽氧化膜之特性分析與腐蝕行為”, 國立台灣科技大學碩士論文, 2014.
[24]F. Mecuson, T. Czerwiec, T. Belmonte, L. Dujardin, A. Viola, G. Henrion, ”Diagnostics of an electrolytic microarc process for aluminium alloy oxidation”, Surface & Coatings Technology 200, 804-808, 2005.
[25]A. L. Yerokhin, A. Shatrov, V. Samsonov, P. Shashkov, A. Pilkington, A. Leyland, A. Matthews, ”Oxide ceramic coatings on aluminium alloys produced by a pulsed bipolar plasma electrolytic oxidation process”, Surface & Coatings Technology 199, 150-157, 2005.
[26]E. Matykina, R. Arrabal, D. J. Scurr, A. Baron, P. Skeldon, G. E. Thompson, ”Investigation of the mechanism of plasma electrolytic oxidation of aluminium using 18O tracer”, Corrosion Science 52, 1070–1076, 2010.
[27]Mohannad M. S. Al Bosta, Keng-Jeng Ma, Hsi-Hsin Chien, ”The effect of MAO processing time on surface properties and low temperature infrared emissivity of ceramic coating on aluminium 6061 alloy”, Infrared Physics & Technology 60, 323-334, 2013.
[28]Mingqi Tang, Weiping Li, Huicong Liu, Liqun Zhu, ”Preparation Al2O3/ZrO2 composite coating in an alkaline phosphate electrolyte containing K2ZrF6 on aluminum alloy by microarc oxidation”, Applied Surface Science 258, 5869-5875, 2012.
[29]P. Bala Srinivasan, J. Liang, C. Blawert, M. Stormer, W. Dietzel, ”Effect of current density on the microstructure and corrosion behavior of plasma electrolytic oxidation treated AM50 magnesium alloy”, Applied Surface Science 255, 4212-4218, 2009.
[30]Wei-Chao Gu, Guo-Hua Lv, Huan Chen, Guang-Liang Chen, Wen-Ran Feng, Si-Ze Yang, ”Characterisation of ceramic coatings produced by plasma electrolytic oxidation of aluminum alloy”, Materials Science and Engineering A 447, 158-162, 2007.
[31]Vahid Dehnavi, Xing Yang Liu, Ben Li Luan, David W. Shoesmith, Sohrab Rohani, ”Phase transformation in plasma electrolytic oxidation coatings on 6061 aluminum alloy”, Surface & Coatings Technology 251, 106-114, 2014.
[32]Kai WANG, Bon-Heun KOO, Chan-Gyu LEE, Young-Joo KIM, Sung-Hun LEE, Eungsun BYON, ”Effects of electrolytes variation on formation of oxide layers of 6061 Al alloys by plasma electrolytic oxidation”, Trans. Nonferrous Met. Soc. China 19, 866-870, 2009.
[33]Nitin P. Wasekar, A. Jyothirmayi, L.Rama Krishna, G. Sundararajan, ”Effect of Micro Arc Oxidation Coatings on Corrosion Resistance of 6061-Al Alloy”, Journal of Materials Engineering and Performance, Volume 17(5), 708-713, 2008.
[34]Shi-Gang Xin, Li-Xin Song, Rong-Gen Zhao, Xing-Fang Hu, ”Composition and thermal properties of the coating containing mullite and alumina”, Materials Chemistry and Physics 97, 132-136, 2006.
[35]Babara Kazanski, Alexei Kossenko, Alex Lugovskoy, and Michael Zinigrand, ”Fluoride Influence on the Properties of Oxide Layer Produced by Plasma Electrolytic Oxidation”, Defect and Diffusion Forum Vols. 326-328, 498-503, 2012.
[36]V. Shoaei-Rad, M. R. Bayati, F. Golestani-Fard, H. R. Zargar, J. Javadpour, ”Fabrication of ZrO2-Al2O3 hybrid nano-porous layers through micro arc oxidation process”, Materials Letters 65, 1835-1838, 2011.
[37]E. Matykina, R. Arrabal, F. Monfort, P. Skeldon, G. E. Thompson, ”Incorporation of zirconia into coatings formed by DC plasma electrolytic oxidation of aluminium in nanoparticle suspensions”, Applied Surface Science 255, 2830-2839, 2008.
[38] E. Matykina, R. Arrabal, P. Skeldon, G. E. Thompson, ”Incorporation of zirconia nanoparticles into coatings formed on aluminium by AC plasma electrolytic oxidation”, J Appl Electrochem 38, 1375-1383, 2008.
[39]L. D. Hart,AULMINA CHEMICALS, 1990.
[40]Xin ShiGang, Le Jun, Song LiXin, ”The Composition and Hardness of the Coating Containing Zirconia Produced by Micro-Arc Oxidation on Aluminium Alloy”, Key Engineering Materials 512-515, 1082-1088, 2012.
[41]A. B. Rogov, A. I. Slonova, V. R. Shayapov, ”Peculiarities of iron-containing microplasma coating deposition on aluminum in homogeneous electrolyte”, Applied Surface Science 261, 647-652, 2012.
[42]Fanya Jin, Paul K. Chu, Honghui Tong, Jun Zhao, ”Improvement of surface porosity and properties of alumina films by incorporation of Fe micrograins in micro-arc oxidation”, Applied Surface Science 253, 863-868, 2006.
[43]Junming Li, Hui Cai, Bailing Jiang, ”Growth mechanism of black ceramic layers formed by microarc oxidation”, Surface & Coatings Technology 201, 8702-8708, 2007.
[44]Mingqi Tang, Weiping Li, Huicong Liu, Liqun Zhu, ”Influence of K2TiF6 in electrolyte on chatacteristics of the microarc oxidation coating on aluminum alloy”, Current Applied Physics 12, 1259-1265, 2012.
[45]Santosh Prasad Sah, Etsushi Tsuji, Yoshitaka Aoki, Hiroki Habazaki, ”Cathodic pulse breakdown of anodic films on aluminium in alkaline silicate electrolyte – Understanding the role of cathodic half – cycle in AC plasma electrolytic oxidation”, Corrosion Science 55, 90-96, 2012.
[46]翁海峰, 陳秋龍, 蔡珣, 鮑明東, ”脈衝占空比對純鋁微弧氧化膜的影響”, 表面技術, 第34卷, 第5期, 2005.
[47]Vahid Dehnavi, Ben Li Luan, David W. Shoesmith, Xing Yang Liu, Sohrab Rohani, ”Effect of duty cycle and applied current frequency on plasma electrolytic oxidation (PEO) coating growth behavior”, Surface & Coatings Technology 226, 100-107, 2013.
[48]J. Martin, A. Melhem, I. Shchedrina, T. Duchanoy, A. Nomine, G. Henrion, T. Czerwiec, T. Belmonte, ”Effect of electrical parameters on plasma electrolytic oxidation of aluminium”, Surface & Coatings Technology 221, 70-76, 2013.
[49]F. Jaspard-Mecuson, T. Czerwiec, G. Henrion, T. Belmonte, L. Dujardin, A. Viola, J. Beauvir, ”Tailored aluminium oxide layers by bipolar current adjustment in the Plasma Electrolytic Oxidation (PEO) process”, Surface & Coatings Technology 201, 8677-8682, 2007.
[50]李沛傑, ”以油酸分散膠體配合氣氛加熱製造奈米氧化鋯粉末之研究”, 2002.
[51]陳俊偉, ”固態氧化物燃料電池氧化鋯電解質之韌性與金屬雙極板抗氧化性研究”, 2005.