Stabilization of the high-temperature phases in ceramic coatings on zirconium alloy produced by plasma electrolytic oxidation

Apelfeld, A. V.; Betsofen, S. Ya.; Борисов, А. М.; Vladimirov, B. V.; Савушкина, С. В.; Knyazev, E. V.

doi:10.1088/1742-6596/748/1/012019

Cited by 7 publications

(6 citation statements)

References 13 publications

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“…Furthermore, the observations of the plasma events on the treated surfaces were also similar. There is little data on the DC PEO U vs. t curves of zirconium or its alloys in the literature [ 32 , 38 ] apart from that belonging to the pulsed variant of the process [ 41 , 45 , 48 , 49 ]. The curve for the latter type of the treatment differs significantly in its shape and surface plasma events from the pure DC regime.…”

Section: Resultsmentioning

confidence: 99%

“…However, since 2007, many reports of PEO of Zircaloys [ 32 , 33 ] and other Zr alloys [ 34 , 35 , 36 ], as well as pure zirconium [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ], were to be found. Most of the studies were mainly concerned with the surface characterization of the coatings that were obtained in the silicate-based electrolytes [ 34 , 35 , 36 , 41 , 44 , 49 , 50 , 51 , 52 ]. Among the groups that were working on the synthesis of bioactive PEO films on Zr, only a few papers can be found on the treatments that were conducted in the electrolytes other than calcium acetate + calcium β-glycerophosphate systems [ 41 , 43 , 46 , 53 ].…”

Section: Introductionmentioning

confidence: 99%

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Effect of DC Plasma Electrolytic Oxidation on Surface Characteristics and Corrosion Resistance of Zirconium

Sowa

Simka

2018

Materials

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Zr is a valve metal, the biocompatibility of which is at least on par with Ti. Recently, numerous attempts of the formation of bioactive coatings on Zr by plasma electrolytic oxidation (PEO) in solutions that were based on calcium acetate and calcium β-glycerophosphate were made. In this study, the direct current (DC) PEO of commercially pure zirconium in the solutions that contained Ca(H2PO2)2, Ca(HCOO)2, and Mg(CH3COO)2 was investigated. The treatment was conducted at 75 mA/cm2 up to 200, 300, or 400 V. Five process stages were discerned. The treatment at higher voltages resulted in the formation of oxide layers that had Ca/P or (Mg+Ca)/P ratios that were close to that of hydroxyapatite (Ca/P = 1.67), determined by SEM/EDX. The corrosion resistance studies were performed using electrochemical impedance spectroscopy (EIS) and DC polarization methods. R(Q[R(QR)]) circuit model was used to fit the EIS data. In general, the coatings that were obtained at 200 V were the most corrosion resistant, however, they lacked the porous structure, which is typical for PEO coatings, and is sought after in the biomedical applications. The treatment at 400 V resulted in the formation of the coatings that were more corrosion resistant than those that were obtained at 300 V. This was determined mainly by the prevailing plasma regime at the given process voltage. The pitting resistance of Zr was also improved by the treatment, regardless of the applied process conditions.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of DC Plasma Electrolytic Oxidation on Surface Characteristics and Corrosion Resistance of Zirconium

Sowa

Simka

2018

Materials

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“…The c-ZrO 2 phase could be formed due to high current density (40 A/dm 2 ) and, consequently, higher temperatures in microdischarges operating during the PEO process. Increasing the current density leads to more intense incorporation of submicron Y 2 O 3 particles into the structure of the forming PEO coating and stabilization of high-temperature tetragonal t-ZrO 2 and cubic c-ZrO 2 phases of zirconia, as was shown in [35,36,41] for yttria nanoparticles.…”

Section: X-ray Phase Analysismentioning

confidence: 83%

“…Due to the low thermal conductivity of zirconia, increasing PEO coatings thickness leads to deterioration in heat removal from the zones of microdischarges functioning, especially in the middle layer. The local temperature in the layer increase provides the formation of high-temperature t-ZrO 2 and c-ZrO 2 phases [36,41]. This is facilitated by yttria, which forms a solid solution with zirconia and stabilizes its high-temperature phases.…”

Section: Discussionmentioning

confidence: 99%

Study of Coatings Formed on Zirconium Alloy by Plasma Electrolytic Oxidation in Electrolyte with Submicron Yttria Powder Additives

Савушкина

Герасимов

Apelfeld

et al. 2021

Metals

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Coatings with thickness 40 to 150 μm were formed by plasma electrolytic oxidation (PEO) on the zirconium alloy Zr-1Nb (Zr-1% Nb) in the slurry electrolyte containing 9 g/L Na2SiO3 5H2O, 5 g/L Na(PH2O2) and 6 g/L submicron Y2O3 yttria powder during 60 min under the AC electrical mode at current densities 20; 30 and 40 A/dm2. The surface morphology, structure, composition, and corrosion-protective ability of the formed coatings have been analyzed. At PEO current density 30 A/dm2, a predominantly tetragonal phase of zirconia was formed in coatings. Increasing the PEO current density up to 40 A/dm2 promoted the formation of the coating surface layer containing submicron yttria particles. Electrochemical polarization studies in 0.5% LiOH solution showed that PEO coatings demonstrated high corrosion-protective ability. The dependence of the polarization currents on the PEO current density was found to be inconsequential.

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“…Phase analysis of the coating formed during 6 min of the treatment shows that it mainly consists of the tetragonal t-ZrO 2 phase with a small share of the monoclinic m-ZrO 2 (Table 3). Tetragonal t-ZrO 2 is a high-temperature phase that usually requires stabilization either with calcium, magnesium or yttrium oxides [30,31]. The diffraction peaks that belong to the substrate also appear in the diffractograms of the coated samples; however, their height is reduced because the X-ray electromagnetic wave when propagating in a solid dissipates following an exponential tendency characterized by a linear absorption coefficient of the material [32].…”

Section: Phase Composition Of the Peo Coatings As A Function Of The S...mentioning

confidence: 99%

Influence of PEO Electrolyzer Geometry on Current Density Distribution and Resultant Coating Properties on Zr-1Nb Alloy

Aubakirova¹,

Гундеров

Фаррахов³

et al. 2023

Materials

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This paper is devoted to the study of the current density distribution effect on plasma electrolytic oxidation process and resultant coatings on a Zr-1Nb alloy. The influence of the distance between the plates simultaneously placed into an electrolyzer was evaluated to assess the throwing power of the PEO process. The current density on the facing surfaces of the plates decreases when the distance between them shrinks. This current density has a notable impact on the resultant PEO coating in terms of the surface morphology parameters and electrochemically evaluated corrosion resistance. The influence of this effect is low on the stages of anodizing and spark discharges (60–120 s of the PEO), and significantly increases on the stage of microarc discharges (120–360 s of the PEO). The coating obtained with a smaller distance between the plates, while having the same coating thickness as the others, exhibits higher wear resistance. New correlations between the current density, diffusion coefficient, time constant of nucleation and the coating thickness in the middle of the facing samples were established; in addition, a correlation of the coating morphology in this area with the roughness parameters RPc, RSm was shown. This study contributes to the development of optimized PEO processes for the simultaneously coated several devices of complex shape, e.g., orthopedic implants.

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Stabilization of the high-temperature phases in ceramic coatings on zirconium alloy produced by plasma electrolytic oxidation

Cited by 7 publications

References 13 publications

Effect of DC Plasma Electrolytic Oxidation on Surface Characteristics and Corrosion Resistance of Zirconium

Effect of DC Plasma Electrolytic Oxidation on Surface Characteristics and Corrosion Resistance of Zirconium

Study of Coatings Formed on Zirconium Alloy by Plasma Electrolytic Oxidation in Electrolyte with Submicron Yttria Powder Additives

Influence of PEO Electrolyzer Geometry on Current Density Distribution and Resultant Coating Properties on Zr-1Nb Alloy

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