本論文藉由雙極脈衝模式下，探討鋁合金7075在鋯酸鹽基電解質中，其電漿電解質氧化(plasma electrolytic oxidation, PEO)正負電流比與電荷比對電漿放電中弱工作現象與其PEO鍍層特性的關係。根據文獻中所描述電流比小於1會產生弱工作現象，本論文以電流比IR=1電荷比CR=1為原點，實驗參數能畫分出四個象限，將針對正負電流IR範圍=[0.53~1.5]，以及陰極工作週期使CR範圍=[0.45~2.00]，進行實驗研究。
在本實驗電流比IR=0.92 電荷比CR=1.2陽極電流密度6.92、10.16與15.24A/dm2處理時間45分鐘；IR=0.92 CR=0.85陽極電流密度5.08與10.16A/dm2處理時間75分鐘，以及電流比IR=0.79電荷比CR=1.2陽極電流密度6.92A/dm2處理時間45分鐘；IR=0.79 CR=0.85陽極電流密度5.08A/dm2處理時間75分鐘，皆未在實驗時間內產生弱工作現象。而電流比IR=0.79 電荷比CR=1.2陽極電流密度6.92A/dm2處理時間45分鐘，陽極電流密度提高至10.16與15.24 A/dm2以及IR=0.79 CR=0.85陽極電流密度5.08A/dm2處理時間75分鐘，陽極電流密度提高至10.16A/dm2 ，在實驗時間內能產生弱工作現象。
文獻中提到電流比小於1，會產生弱工作現象。本研究探討第二象限(IR<1,CR>1)[IR=0.53~0.7 , CR=1.2~2.0]與第三象限(IR<1,CR<1) [IR=0.53~0.7 , CR=0.45~0.85]結果發現在相同電流比條件下，CR值越大，越早發生弱工作現象。同樣在第二及三象限中，在相同電荷比條件下，不同電流比影響弱工作現象發生的時間，電流比越小弱工作現象越早發生。其原因在於低電流比在PEO過程中還原反應產生之氫氣較多，氫氣會破壞膜層之絕緣性，而使得弱工作現象提早發生。
至於第一象限(IR>1，CR>1)其電壓行為，傳統PEO製程，具有高電壓、強微弧放電、高放電強度等特性。電壓於一分鐘至三分鐘期間與第四象限(IR>1，CR<1)一樣，平均呈現停滯現象。電壓升不上去，代表膜層呈現導通的狀態，膜層所需之介電層不夠；若持續通以電壓，累積電荷，膜層之電壓便開始上升。至於第四象限其參數沒有在特定的範圍內出現暫態電壓下降，可能原因為氧化膜中不定時出現缺陷所導致。在第四象限內出現的電壓下降現象，雖然聲光消失，但此現象極為短暫；且電壓會再度回升到原本之電壓，此現象有別於soft regime現象，稱之為暫態電壓下降現象。
第二象限與第三象限在相同電流比條件下，電荷比越大，弱工作現象越早發生；其陰極工作時間較短，產生較少氫氣擴散至膜層，所形成的缺陷和氧空缺較少，微觀結構顯示膜層較緻密。在相同電流及頻率下，其陰極瞬時電流密度較高，局部能量較大，造成化學反應較多，破壞膜層之絕緣性阻抗下降。在定電流模式下，根據歐姆定律V=IR，使得陽極電壓下降，伴隨著聲光消失，較早產生弱工作現象。電荷比變化說明了陰陽極放電速率影響電漿發生時，膜層形成的導電行為的變化；在弱工作現象形成的膜層的微觀結構顯示出孔洞較小的塗層，為氧化層向內生長的行為；而在傳統PEO製程(arcing regime)形成的膜層可以看到較大的孔洞，由較劇烈之放電現象造成之。
而第四象限膜層微觀結構，暫態電壓下降，能填補膜層向外生長之強微弧放電、高放電強度所產生的大孔洞，整體而言此象限膜層較第一象限(傳統PEO製程)膜層緻密。

In this thesis, the bipolar pulse mode is used to investigate soft regime of the aluminum alloy 7075 in the zirconate-based electrolyte using plasma electrolytic oxidation (PEO) the relationship between coating characteristics and different current ratios and charge ratios in plasma discharge was studied. According to the description in the literature that the current ratio less than 1 may produce soft regime, here we take current ratio IR=1 and charge ratio CR=1 as the origin to investigate the role of IR and CR.The experimental parameters can be drawn into four quadrants, and the range of current IR = [0.53~1.5], and adjusting the cathode duty cycle to make CR = [0.45~2.00] were carried out to perform experimental research.
In this experiment, IR=0.92 and CR=1.2 with anode current density 6.92,10.16 and 15.24A/dm2 and treatment time 45 minutes；IR=0.92 CR=0.85 with anode current density 5.08 and 10.16A/dm2 and treatment time 75 minutes；IR=0.79 CR=1.2 with anode current density 6.92A/dm2 and treatment time 45 minutes；IR=0.79 CR=0.85 with anode current density 5.08A/dm2 and treatment time 75 minutes do not show soft sparking. On the other hand, IR=0.79 CR=1.2 with anode current density 6.92A/dm2 and treatment time 45 minutes, as well IR=0.79 CR=0.85 with anode current density 5.08A/dm2 and treatment time 75 minutes, show no soft regime, but when IR=0.79 CR=1.2 with anode current density 6.92A/dm2 increased to 10.16 and 15.24A/ dm2 and treatment time 45 minutes ,as well IR=0.79 CR=0.85 with anode current density 5.08A/dm2 increased to 10.16A/ dm2 and treatment time 75 minutes, the specimens produce soft regime within the experimental time.
It is mentioned previous works show that when the current ratio is less than one, the specimens using PEO may produce soft regime. This study explores the second quadrant (IR<1, CR>1) [IR=0.53~0.7, CR=1.2~2.0] and the third quadrant (IR<1, CR<1) [IR=0.53~0.7, CR= 0.45~0.85] It was found that under the same current ratio conditions, the larger the CR value, the earlier soft regime occurred. Also in the second and third quadrants, under the same charge ratio conditions, different current ratios affect the time when soft regime occurs. The smaller the current ratio, the earlier soft regime occurs. The reason is that the low current ratio produces more hydrogen in the reduction reaction of the PEO process. The hydrogen will destroy the insulation of the film and make soft regime occur earlier.
As for the voltage behavior of the first quadrant (IR>1, CR>1), the traditional PEO process has the characteristics of high voltage, strong micro-arc discharge, and high discharge intensity. The voltage is the same as the fourth quadrant (IR>1, CR<1) during the period of one to three minutes. If the voltage does not rise, it means that the film is in a state of high leakage, and the dielectric layer required by the film is not enough; if the voltage is continuously applied to accumulate oxides, the voltage of the film will start to rise. As for the fourth quadrant, its parameters did not show a transient voltage drop within a specific range, which may be caused by irregularities in the oxide film. In the fourth quadrant, the voltage drop phenomenon, although the sound and light disappear, this phenomenon is extremely short-lived; and the voltage will rise back to the original voltage again. This phenomenon is different from the soft regime phenomenon and is called a transient voltage drop phenomenon.
The second quadrant and the third quadrant under the same current ratio conditions, the greater the charge ratio, the earlier soft sparking may occur; the cathode has a shorter working time, less hydrogen gas diffuses into the film, and fewer defects and oxygen vacancies are formed. The microstructure shows that the film is denser. Under the same current and frequency, the instantaneous current density of the cathode is higher, and the local energy is higher, which causes more chemical reactions and reduces the insulation resistance of the damaged film. In the constant current mode, according to Ohm's law V=IR, the anode voltage drops, accompanied by the disappearance of sound and light, and soft regime occurs earlier. The change in charge ratio shows that the discharge rate of cathode and anode affects the change of the conductive behavior of the film formation when the plasma occurs; the microstructure of the film formed in soft regime shows a coating with smaller holes, in the grown oxide layer, in contrast to that in the traditional PEO process (arcing regime),which shows larger pores, caused by the more intense discharge phenomenon.
The microstructure of the oxide layer, using parameters in the four quadrant , shows the transient voltage drops, which may reduce the large holes generated by the strong micro-arc discharge and high discharge intensity of the film layer. In overall, the film layer in this quadrant is denser than that produced in the first quadrant (traditional PEO process).

[1] W. Xue, X. Wu, X. Li, H. Tian, J. Alloys Comp. 425 (2006) 302–306.
[2] I.V. Lukiyanchuk, V.S. Rudnev, V.G. Kuryavyi, D.L. Boguta, S.B. Bulanova, P.S. Gordienko, Thin Solid Films 446 (2004) 54–60.
[3] G. Lv, W. Gu, H. Chen, W. Feng, M.L. Khosa, L. Li, E. Niu, G. Zhang, S.-Z. Yang, Appl. Surf. Sci. 253 (2006) 2947–2952.
[4] F. Jaspard-Mécuson , 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 (2007) 8677–8682
[5] A. Melhem, G. Henrion , T. Czerwiec, J.L. Briançon, T. Duchanoy, F. Brochard, T. Belmonte, “Changes induced by process parameters in oxide layers grown by the PEO process on Al alloys”, Surface & Coatings Technology 205 (2011) S133–S136
[6] W. Gębarowski, S. Pietrzyk, “Influence of the cathodic pulse on the formation and morphology of oxide coatings on aluminium produced by plasma electrolytic oxidation”, Archives of metallurgy and materials, 58 (2013) Pp241-245
[7] Amin Hakimizad , Keyvan Raeissi , Mohammad Ali Golozar , Xiaopeng Lu , Carsten Blawert , Mikhail L. Zheludkevich, “Influence of cathodic duty cycle on the properties of tungsten containing Al2O3/TiO2 PEO nano-composite coatings”, Surface & Coatings Technology 340 (2018) 210–221
[8] J. Martin, A. Nomin´e, F. Brochard, J.-L. Brianc¸on, C. No¨el, T. Belmonte, T. Czerwiec, G. Henrion, “Delay in micro-discharges appearance during PEO of Al: Evidence of a mechanism of charge accumulation at the electrolyte/oxide ”, interface Applied Surface Science 410 (2017) 29–41
[9] R. Ambat, Naing Naing Aung and W.zhou, "Evaluation of microstructural effects on corrosion behavior of AZ91D magnesium alloy", Corrosion Science, Vol.42(2000) p.1433
[10]W. McNiell, and G. F. Nordbloom, "Method of Making Cadmium Niobate", US Patent 2854390, September 30 (1958).
[11] G.A. Mardov and G.V. Markova, The formation method of anodic electrolytic condensation. SU52961(1976)
[12] P.K. Kurze and H.G. Schneider, Application fields of ANOF layers and composites. Cryst .Res. Technol.(1986) 21: p. 1603
[13]W.B. Xue, Z.W. Deng, R.Y.Chen, T.H. Zhang, H.Ma, ”Microstructure and properties of ceramic coatings produced on 2024 aluminum alloy by microarc oxidation”, Journal of Materials Science 36(2001)2615-2619
[14] Y.J. Oh, J.I. Mun, J.H. 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(2009) 141-148
[15]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 (2005) 139-142
[16]G.L.Yang, X.Y. Lee, Y.Z.Bai, H.F.Cui, Z.S.Jin, ”The effects of current density on the phase composition and microstructure properties of micro-arc oxidation coating”, Journal of Alloys and Compounds 345(2002) 196-200
[17] W. B. Xue, Z. W . Deng , R. Y. Chen, T. H. Zhang, H. Ma, Microstructure and properties of ceramic coatings produced on 2024 aluminum alloy by microarc oxidation, Journal of Materials Science 36 (2001) 2615–2619
[18] 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[13] (2004), 2085-2095.
[19] W. Xue, Z. Deng, R. Chen, T. Zhang. Growth Regularity of Ceramic Coatings Formed by Microarc Oxidation on Al-Cu-Mg alloy. Thin Solid Films, 372(2000) 114-117.
[20] G. Sundararajan and L. Rama, Mechanisms underlying the formation of thick alumina coatings through the MAO coating technology. Surf. Coat. Technol., 167(2-3) (2003) 269-277.
[21] R.O. Hussein, X. Nie, D.O. Northwood,lectrochimica Acta, 112 (2013)111-119
[22] A.Nominé, J.Martin, C.Noël, I.V Bardin, V.L Kovalev, T. Belmonte, A.G Rakoch ,G. Henrion, “Optical characterisation of plasma micro-discharges during Plasma Electrolytic Oxidation on Magnesium”, ResearchGate(2015)
[23] A. Nominé, J. Martin, C. Noël, G. Henrion, T. Belmonte, I. V. Bardin, V. L. Kovalev, and A. G. Rakoch, “The evidence of cathodic micro-discharges during plasma electrolytic oxidation process”, Applied Physics Letters 104, (2014) 081603-1~081603-5
[24] A. Nominé, J. Martin, G. Henrion, T. Belmonte, “Effect of cathodic micro-discharges on oxide growth during Plasma Electrolytic Oxidation (PEO) ”, Surface & Coatings Technology 269 (2015) 131–137
[25] J .Martin , A. Nominé, V. Ntomprougkidis , S. Migot , S. Bruyère , F. Soldera , T. Belmonte, G. Henrion, “Formation of a metastable nanostructured mullite during Plasma Electrolytic Oxidation of aluminium in “soft” regime condition ”, Materials and Design 180 (2019) 107977
[26] J. Martin , A. Melhem , I. Shchedrina , T. Duchanoy , A. Nominé , G. Henrion , T. Czerwiec , T. Belmonte, “Effects of electrical parameters on plasma electrolytic oxidation of aluminium”, Surface & Coatings Technology 221 (2013) 70–76
[27] D.S. Tsai, C.C. Chou, Review of the soft sparking regime issues in plasma electrolytic oxidation, Metals 8 (2018) 105.
[28]盧品翰,“鎂合金AZ91以鋁酸鹽電解液電漿電解氧化(PEO)處理之研究”,2018
[29] R. Arrabal , E. Matykina, T. Hashimoto, P. Skeldon, G.E. Thompson,“Characterization of AC PEO coatings on magnesium alloys”, Surface & Coatings Technology 203 (2009) 2207–2220
[30] T.W. Clyne, S.C. Troughton, A review of recent work on discharge characteristics during plasma electrolytic oxidation of various metals, Int. Mater. Rev. 64 (2019)127–162.
[31]E. Matykina, R. Arrabal, P. Skeldon, G.E. Thompson, Investigation of the growth processes of coatings formed by AC plasma electrolytic oxidation of aluminium, Electrochim. Acta 54 (2009) 6767–6778.
[32]W. Gebarowski, S. Pietrzyk, Growth characteristics of the oxide layer on aluminium in the process of plasma electrolytic oxidation, Arch. Metall. Mater. 59 (2014)407–411.
[33] X. Lu, M. Mohedano, C. Blawert, E. Matykina, R. Arrabal, K.U. Kainer, M. Zheludkevich, Plasma electrolytic oxidation coatings with particle additions–a review, Surf. Coat. Technol. 307 (2016) 1165–1182.
[34] E. Matykina, R. Arrabal, B. Mingo, M. Mohedano, A. Pardo, M.C. Merino, In vitro corrosion performance of PEO coated Ti and Ti6Al4V used for dental and orthopaedic implants, Surf. Coat. Technol. 307 (2016) 1255–1264.
[35] W.K. Yeung, I.V. Sukhorukova, D.V. Shtansky, E.A. Levashov, I.Y. Zhitnyak, N.A.Gloushankova, P.V. Kiryukhantsev-Korneev, M.I. Petrzhik, A. Matthewsa, A. Yerokhin, RSC Adv. 6 (2016) 12688–12698.
[36] K. Wang, B.H. Koo, C.G. Lee, Y.J. Kim, S.H. Lee, E. Byon, Trans. Nonferrous Met. Soc. China 19 (2009) 866-870.
[37] R.O. Hussein, X. Nie, D.O. Northwood, An investigation of ceramic coating growth mechanisms in plasma electrolytic oxidation (PEO) processing, Electrochimica Acta 112 (2013) 111– 119.
[38] A L Yerokhin, L O Snizhko, N L Gurevina, A Leyland, A Pilkington and A Matthews, Discharge characterization in plasma electrolytic oxidation of aluminium, Applied Physics 36 (2003) 2110–2120
[39] J. Martin, K. Akoda, V. Ntomprougkidis, O. Ferry, A. Maizeray, A. Bastien,
P. Brenot, G. Ezo'o, G. Henrion,“Duplex surface treatment of metallic alloys combining cold-spray and plasma electrolytic oxidation technologies”, Surface & Coatings Technology 392 (2020) 125756
[40] M. Kodu, M. Aints, T. Avarmaa, V. Denks, E. Feldbach, R. Jaaniso, M. Kirm, A. Maaroos, J. Raud, “Hydrogen doping of MgO thin films prepared by pulsed laser deposition”, Applied Surface Science 257 (2011) 5328–5331