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Article

Novel Porous Phosphorus–Calcium–Magnesium Coatings on Titanium with Copper or Zinc Obtained by DC Plasma Electrolytic Oxidation: Fabrication and Characterization

by
Krzysztof Rokosz
1,*,
Tadeusz Hryniewicz
1,
Sofia Gaiaschi
2,
Patrick Chapon
2,
Steinar Raaen
3,
Dalibor Matýsek
4,
Łukasz Dudek
1 and
Kornel Pietrzak
1
1
Division of BioEngineering and Surface Electrochemistry, Department of Engineering and Informatics Systems, Koszalin University of Technology, Racławicka 15-17, PL 75-620 Koszalin, Poland
2
HORIBA FRANCE S.A.S., Avenue de la Vauve, Passage Jobin Yvon, 91120 Palaiseau, France
3
Department of Physics, Norwegian University of Science and Technology (NTNU), Realfagbygget E3-124 Høgskoleringen 5, 7491 NO Trondheim, Norway
4
Institute of Geological Engineering, Faculty of Mining and Geology, VŠB—Technical University of Ostrava, 708 33 Ostrava, Czech Republic
*
Author to whom correspondence should be addressed.
Materials 2018, 11(9), 1680; https://doi.org/10.3390/ma11091680
Received: 2 August 2018 / Revised: 4 September 2018 / Accepted: 7 September 2018 / Published: 11 September 2018
(This article belongs to the Special Issue Metals Functionalization via Plasma Electrolytic Oxidation)
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Versions Notes

Abstract

:
In this paper, the characteristics of new porous coatings fabricated at three voltages in electrolytes based on H3PO4 with calcium nitrate tetrahydrate, magnesium nitrate hexahydrate, and copper(II) nitrate trihydrate are presented. The SEM, energy dispersive spectroscopy (EDS), glow discharge optical emission spectroscopy (GDOES), X-ray photoelectron spectroscopy (XPS), and XRD techniques for coating identification were used. It was found that the higher the plasma electrolytic oxidation (PEO) (micro arc oxidation (MAO)) voltage, the thicker the porous coating with higher amounts of built-in elements coming from the electrolyte and more amorphous phase with signals from crystalline Ca(H2PO4)2∙H2O and/or Ti(HPO4)2∙H2O. Additionally, the external parts of the obtained porous coatings formed on titanium consisted mainly of Ti4+, Ca2+, Mg2+ and PO43−, HPO42−, H2PO4−, P2O74− as well as Zn2+ or copper Cu+/Cu2+. The surface should be characterized by high biocompatibility, due to the presence of structures based on calcium and phosphates, and have bactericidal properties, due to the presence of zinc and copper ions. Furthermore, the addition of magnesium ions should accelerate the healing of postoperative wounds, which could lead to faster patient recovery.

Graphical Abstract

1. Introduction

The phenomenon of luminescence occurring on the surface of metals during the galvanic process was first observed by Sluginov in 1880 [1], and the information was published for the first time by Braun in 1898 [2]. In 1929, Dufford showed that during the electrolysis of metals such as aluminum, zinc, silver, tantalum, tungsten, magnesium, cerium, antimony, and mercury in selected electrolytes, the phenomenon of luminescence was observed [3]. In addition, he noticed that this phenomenon was not observed with lead, iron, copper, nickel, molybdenum, tin, and platinum. Such luminescence phenomenon was developed, inter alia, by McNeill, Gruss, Yerokhin, and Nie [4,5]. In addition, Yerokhin at al. proposed a definition of that process, that it is “an electrolytic treatment of anodically polarized metal surfaces carried out above the dielectric breakdown voltage of the growing oxide film”, as well as an explanation of the formation of porous coatings [5,6]. According to this theory, during small voltage polarization, the passive layer is forming, which may be dissolved with the voltage increase. Further increases of voltage result in film repassivation and growth of a new porous oxide film. In the next step of voltage increase, the electric field strength in the oxide film reaches a critical value, after which the film is broken through due to impact or tunneling ionization (here, luminescent sparks are observed). A further increase of voltage results in the following: thermal ionization, larger arc discharges, film fusing and alloying with electrolyte elements, microdischarges penetrating through to the substrate, powerful arcs, destructive effects, and thermal cracking of the coating. It should be also pointed out that on the same plasma electrolytic oxidation (PEO) treated surface, more than one of the described processes may occur concurrently [5]. Over the years, the phenomenon of galvanic luminescence occurring during the anodic polarization of selected metals and electrolytes has been defined as microplasma oxidation, anode spark electrolysis, plasma electrolytic anode treatment, plasma electrolytic oxidation, or micro arc oxidation [7]. Systematic studies proposed coating growth [8,9,10] and discharging [11,12,13,14] behaviors as well as electrolyte influence on the ignition of plasma electrolytic oxidation processes [15]. Meanwhile, Curran and Clyne described the thermophysical properties of plasma electrolytic oxidation [16] and the porosity of PEO coatings [17]. Other authors studied oxygen evolution during PEO [18] and the effects of electrical parameters on that process [19] as well as phase formation in ceramic PEO coatings [20,21] and their corrosion resistance [22]. The PEO process has been performed by researchers under different conditions, i.e., DC [23,24], AC [25,26], and pulse [27,28] currents, which result in different surface morphology [29,30] and chemical composition [31,32] as well as mechanical [33,34] and electrochemical properties [35,36]. For the most frequently treated materials by PEO processes, aluminum [37,38,39,40] and its alloys [40,41,42,43,44], magnesium [45] and its alloys [46,47,48,49,50,51,52,53,54], titanium [55,56,57,58,59,60] and its alloys [61,62,63,64,65,66,67], zirconium [68,69,70,71,72,73,74,75,76,77] and its alloys [78,79], tantalum [80,81,82,83], niobium [84,85,86,87,88], and hafnium [89] should be included. In the present paper, PEO coatings obtained on titanium in novel electrolytes, which have never been used or described in the literature until now, are presented (Table 1). These electrolytes are based on orthophosphoric acid and three different nitrates.
It should also be pointed out that in hydroxyapatite-like structures it is possible to substitute the Ca2+ ions for Ca2+, Mg2+, Cu2+, and Zn2+, as well as OH– for Cu+, which will be used in the fabrication of novel PEO coatings. The porous calcium–phosphate coatings obtained on titanium [117,118,119] and enriched with biocompatible magnesium, which causes faster wound healing [120,121,122,123,124,125], as well as antibacterial zinc [126,127,128,129,130,131,132] and copper [133,134,135,136], may be used as biomaterial, which will be fully accepted by the tissue environment.
However, without results inter alia presented in those papers, it is not possible to predict the real possibility of that substitution during plasma treatment in electrolyte in which the ions are present, as well as the thickness and porosity of the PEO coatings. Therefore, in the present paper, the results of x-ray photoelectron spectroscopy (XPS) (10 top nanometers) will be helpful in explaining the oxidation states of those chemical elements as well as chemical composition for all volumes, thicknesses, and pore shapes of obtained coatings by energy dispersive spectroscopy (EDS), XRD, glow discharge optical emission spectroscopy (GDOES), and SEM.

2. Materials and Methods

Porous coatings obtained on titanium samples (10 × 10 × 2 mm) by PEO treatment in electrolyte (constant volume of 500 mL for each experiment) containing phosphoric acid (85% w/w) with the addition of calcium nitrate tetrahydrate Ca(NO3)2·4H2O, magnesium nitrate hexahydrate Mg(NO3)2·6H2O, and copper(II) nitrate trihydrate Cu(NO3)2·3H2O in weight ratios of 1:1:1 (Table 2) at 3 voltages, 500 V (PEO time: 3 min), 575 V (PEO times: 1, 3, 5 min), and 600 V (PEO time: 3 min), using a PWR 1600H power supply (KIKUSUI Electronics Corp., Yokohama, Kanagawa, Japan) were fabricated. For their characterization, the complementary measurement methods SEM, EDS, GDOES, XPS, and XRD [137,138,139,140,141] were used. Descriptions of the setups are presented in Table 3 and are detailed in reference [24].

3. Results

Figure 1 shows the surface morphologies of coating surfaces formed on titanium at 500 V, 575 V, and 650 V in two different electrolytes based on phosphoric acid. Two solutions were used: Electrolyte 1, containing H3PO4 with the addition of calcium nitrate tetrahydrate Ca(NO3)2·4H2O, magnesium nitrate hexahydrate Mg(NO3)2·6H2O, and zinc nitrate hexahydrate Zn(NO3)2·6H2O; and Electrolyte 2, with additions of calcium nitrate tetrahydrate Ca(NO3)2·4H2O, magnesium nitrate hexahydrate Mg(NO3)2·6H2O, and copper(II) nitrate trihydrate Cu(NO3)2·3H2O. It should be pointed out that all the obtained coatings were porous and had a well-developed surface.
In Figure 2 and Table 4, the EDS semiquantitative results for samples obtained in Electrolyte 1 are presented as Ca/P, Mg/P, Zn/P, and M/P ratios. The Ca/P ratios were equal to 0.051 ± 0.003 natural units (n.u.), 0.063 ± 0.003 n.u., and 0.069 ± 0.003 n.u. for 500, 575, and 650 V, respectively. The Mg/P ratios were equal to 0.051 ± 0.004 n.u. (500 V), 0.058 ± 0.003 n.u. (575 V), and 0.060 ± 0.006 n.u. (650 V). The Zn/P ratios for 500, 575, and 650 V were equal to 0.052 ± 0.004 n.u., 0.065 ± 0.005 n.u., and 0.071 ± 0.010 n.u., respectively. The M/P ratios were equal to 0.153 ± 0.008, 0.187 ± 0.006, and 0.200 ± 0.020 for 500, 575, and 650 V, respectively.
Figure 3 and Table 5 present the EDS semiquantitative results for samples obtained in Electrolyte 2 as Ca/P, Mg/P, Cu/P, and M/P. The Ca/P ratios were equal to 0.062 ± 0.003 n.u., 0.068 ± 0.004 n.u., and 0.071 ± 0.003 n.u. for 500, 575, and 650 V, respectively. The Mg/P ratios were equal to 0.058 ± 0.002 n.u., 0.059 ± 0.003 n.u., and 0.064 ± 0.003 n.u. for 500, 575, and 650 V, respectively. The Cu/P ratios for samples obtained at 500, 575, and 650 V were equal to 0.039 ± 0.003 n.u., 0.048 ± 0.002 n.u., and 0.062 ± 0.005 n.u., respectively. The M/P ratios for samples obtained at 500, 575, and 650 V were equal to 0.158 ± 0.006 n.u., 0.175 ± 0.006 n.u., and 0.197 ± 0.004 n.u., respectively.
The diffraction data of PEO coatings formed in Electrolytes 1 and 2 at three voltages are presented in Figure 4. For both electrolytes, similar phenomena were observed, i.e., for samples oxidized at 500 and 575 V, only signal from titanium as metal matrix was detected, while for 650 V other crystalline phases, such as Ca(H2PO4)2∙H2O and Ti(HPO4)2∙H2O for samples obtained in Electrolyte 1 and Ca(H2PO4)2∙H2O for samples obtained in Electrolyte 2, were recorded. It was also found that voltage growth in PEO coatings caused amorphous phase accretion as well.
GDOES data of PEO coatings formed in Electrolyte 1 at 500, 575, and 650 V are presented in Figure 5. The top and porous sublayers, which are enriched in Zn, P, and O and depleted in Ca, Mg, and Ti, have thicknesses of about 200, 300, and 500 s of sputtering time for 500, 575, and 650 V, respectively, while the thickness of the second (semiporous) one, which was enriched in calcium, magnesium, zinc, phosphorus, and oxygen and depleted in titanium, was in the range of 700 s (500 V) up to 2000 s (650 V) of sputtering time. On the other hand, the thicknesses of the third (transition) sublayers, in which a decrease of all signals, except titanium, was observed, increased from 800 s (500 V) up to 2000 s (650 V) of sputtering time. In Figure 6, the GDOES results of PEO coatings formed in Electrolyte 2 at the same three voltages are presented.
The top and porous sublayers, which are enriched in P and O and depleted in Ca, Mg, Cu, and Ti, have thicknesses related to sputtering times equal to about 100, 300, and 600 s for 500, 575, and 650 V, respectively, while the thickness of the second (semiporous) layer, which is enriched in Ca, Mg, Cu, P, and O and depleted in Ti, is in the range of 600 s (500 V) up to 1900 s (650 V) of sputtering time. Here, the thicknesses of the transition sublayers are in the range from 600 s (500 V) up to 1500 s (650 V) of sputtering time. The part of C, N, and O signals may originate in the first top sublayers from contamination (from air and cleaning compounds). In addition, the H signals maxima, which are always placed in third-transition sublayers, is the end of the coating porosity. It should also be noted that the accretion of voltage caused an increase in coating thickness. In Figure 7 and Figure 8, the XPS spectra of PEO coatings formed in Electrolytes 1 and 2 are presented. Based on the obtained results, it can be concluded that the top external 10 nm layers of the PEO coating consist mainly of phosphorus, oxygen, nitrogen, titanium, calcium, magnesium, and zinc (Electrolyte 1) or copper (Electrolyte 2). The bindings of C with O and N with O can be interpreted as contaminants (cleaning process and adsorbed air). The phosphorus (P 2p) and oxygen (O 1s) spectra were in the range of 133.6–134 eV and 531.3–531.5 eV, respectively, which can be interpreted as the groups PO43−, HPO42−, H2PO4−, and P2O74−. The Cu 2p spectra maxima (331.1–932.9 eV and 934.5–935.8 eV) and Auger Cu LMM (566–567.2 eV) suggest the presence of Cu+ and Cu2+, while Ca2+ is proved by the binding energy (BE) in the range of 347.4−347.7 eV. The BE of Zn 2p (1021.9–1022.4 eV) and Zn LMM (497.9–501.5 eV) proves the existence of Zn2+, while BE in the range of 89.1–92.8 eV (Mg 2s) and 306.2–306.9 eV (Mg KLL) indicates the existence of Mg2+. The BE of titanium Ti 2p3/is in the range of 459.9−460.2 eV, which means that titanium is on the fourth oxidation state (Ti4+). Based on the quantitative XPS of the top 10 nm of PEO coatings obtained in Electrolytes 1 and 2 at three voltages, two ratios, Ca:Mg:Zn and Ca:Mg:Zn, were found. The Ca:Mg:Zn ratios are equal to 8:32:1 n.u. (500 V), 8:28:1 n.u. (575 V), and 14:45:1 n.u. (650 V), while the Ca:Mg:Zn ratios are equal to 5:5:1 n.u. (500 V), 4:7:1 n.u. (575 V), and 6:5:1 n.u. (650 V). (Ca + Mg + Zn)/P and (Ca + Mg + Cu)/P have their maxima equal to 0.48 n.u. and 0.21 n.u., respectively, at 575 V. The same trend was observed for single Me/P ratios, where M ∈ {Ca, Mg, Zn, Cu}, i.e., the maxima were recorded for PEO coatings obtained at 575 V.

4. Discussion

In this paper, the characteristics of new porous coatings fabricated at 500, 575, and 650 V in electrolytes based on H3PO4 and Mg(NO3)2·6H2O, Ca(NO3)2·4H2O with Cu(NO3)2·3H2O, and Zn(NO3)2·6H2O were presented. Information on the chemical composition of the PEO coatings was obtained by use of the XPS method (for the first 10 nm) and EDS and XRD (for the whole volume of the coatings). Based on EDS results, which were recorded for the whole volume of the coatings, it was found that increased PEO voltage results in an increase of the average metal-to-phosphorus ratios (Ca/P, Mg/P, Zn/P, and Cu/P), while XPS analysis of 10 nm showed that the maxima of those ratios are achieved for the values of the central voltage (575 V), which indicates that the coatings are layered, as proven by GDOES elemental profiles. All the PEO coatings can be divided into three sublayers: (i) external porous layer, enriched in P, O, and Zn (Electrolyte 1) and depleted in Ca, Mg, and Cu (Electrolyte 2) and Ti, but also the most contaminated (CO2, C2H5OH); (ii) semiporous layer, enriched in Ca, Mg, P, O, and Zn (Electrolyte 1) or Cu (Electrolyte 2), and depleted in Ti; (iii) transition layer, in which the titanium signal increases and depletion of all other elements (P, O, Ca, Mg, Zn, and Cu) is detected. On the basis of these XPS data, it was possible to conclude that the extreme surface of the coatings most likely consists of titanium (Ti4+), calcium (Ca2+), magnesium (Mg2+), and oxygen with PO43−, HPO42−, H2PO4−, and P2O74− as well as Zn2+ or Cu+/Cu2+. Furthermore, the XRD analysis suggests that increasing voltage results in amorphization of the coatings, with the detection of crystalline phases such as Ca(H2PO4)2∙H2O and/or Ti(HPO4)2∙H2O.
It was also observed that using zinc ions as a bactericidal element instead of the copper ions in PEO coatings obtained on titanium substrate results in a drastic increase of magnesium incorporated into the obtained structure, combined with a slight increase of calcium ions. The results presented in this paper may be used to design biocompatible and bactericidal coatings due to the creation hydroxyapatite-like structures, in which the Ca2+ may be replaced by others, i.e., Mg2+, Zn2+, Cu2+, and the hydroxy group (OH−) by Cu+ ions. It should be pointed out that while magnesium accelerates the healing of postoperative wounds, the structure composed of calcium and phosphorus is bone-like. Therefore, zinc or copper added in controlled quantities would perform antibacterial functions, which, together with magnesium, would allow faster healing of postoperative wounds.

5. Conclusions

  • It is possible to obtain porous calcium–magnesium–phosphate coatings enriched with copper or zinc.
  • The higher the voltage of PEO treatment, the thicker the porous coatings.
  • The higher the voltage of PEO treatment, the higher the amount of built-in elements coming from the electrolyte and more amorphous phase in coatings.
  • The top 10 nm layer of the studied coatings consist mainly of Ti4+, Ca2+, Mg2+ and PO43−, HPO42−, H2PO4.

Author Contributions

K.R. and T.H. conceived and designed the experiments; K.R., S.G., P.C., Ł.D., S.R., D.M., and W.M. performed the experiments; K.R., K.P., and Ł.D. analyzed the data; K.R., K.P., and Ł.D. contributed reagents, materials, and analysis tools; K.R. wrote the paper.

Funding

This work was supported by a grant from OPUS 11 of the National Science Centre, Poland, with registration number 2016/21/B/ST8/01952, titled “Development of models of new porous coatings obtained on titanium by Plasma Electrolytic Oxidation in electrolytes containing phosphoric acid with addition of calcium, magnesium, copper and zinc nitrates”.

Conflicts of Interest

The authors declare no conflict of interest.

Nomenclature

PEOPlasma electrolytic oxidation
MAOMicro arc oxidation
SEMScanning electron microscopy
EDSEnergy dispersive spectroscopy
GDOESGlow discharge optical emission spectroscopy
XPSX-ray photoelectron spectroscopy
XRDX-ray powder diffraction
x ¯ Mean
σStandard deviation
Q1First quartile
Q2Second quartile (median)
Q3Third quartile
MMetal (here M = Ca + Mg + Zn or M = Ca+ Mg + Cu)
BEBinding energy
fFrequency
DCDirect current
ACAlternating current
n.u.no unit

References

  1. Sluginov, N. On luminous phenomen, observed in liquids during electrolysis. Russ. Phys. Chem. Soc. 1880, 12, 193–203. [Google Scholar]
  2. Braun, F. Ueber Lichtemission an einige Electroden in Electrolyten. Annalen der Physik und Chemie 1898, 65, 361–364. [Google Scholar] [CrossRef]
  3. Dufford, R.T. Luminescence Associated with Electrolysis. J. Opt. Soc. Am. 1929, 18, 17–28. [Google Scholar] [CrossRef]
  4. McNeill, W.; Gruss, L.L. Anodic Spark Reaction Processes and Articles. U.S. Patent US3293158, 17 September 1963. [Google Scholar]
  5. Yerokhin, A.L.; Nie, X.; Leyland, A.; Matthews, A.; Dowey, S.J. Plasma electrolysis for surface engineering. Surf. Coat. Technol. 1999, 122, 73–93. [Google Scholar] [CrossRef]
  6. Yerokhin, A.; Parfenov, E.V.; Matthews, A. In situ impedance spectroscopy of the plasma electrolytic oxidation process for deposition of Ca- and P-containing coatings on Ti. Surf. Coat. Technol. 2016, 301, 54–62. [Google Scholar] [CrossRef]
  7. Aliasghari, S. Plasma Electrolytic Oxidation of Titanium. Ph.D. Thesis, The University of Manchester, Manchester, UK, 2014; p. 223. [Google Scholar]
  8. Hussein, R.O.; Northwood, D.O.; Nie, X. Coating growth behavior during the plasma electrolytic oxidation process. J. Vac. Sci. Technol. A 2010, 28, 766–773. [Google Scholar] [CrossRef]
  9. Hussein, R.O.; Nie, X.; Northwood, D.O. An investigation of ceramic coating growth mechanisms in plasma electrolytic oxidation (PEO) processing. Electrochim. Acta 2013, 112, 111–119. [Google Scholar] [CrossRef]
  10. Monfort, F.; Berkani, A.; Matykina, E.; Skeldon, P.; Thompson, G.E.; Habazaki, H.; Shimizu, K. A tracer study of oxide growth during spark anodizing of aluminum. J. Electrochem. Soc. 2005, 152, C382–C387. [Google Scholar] [CrossRef]
  11. Hussein, R.O.; Nie, X.; Northwood, D.O.; Yerokhin, A.; Matthews, A. Spectroscopic study of electrolytic plasma and discharging behaviour during the plasma electrolytic oxidation (PEO) process. J. Phys. D Appl. Phys. 2010, 43, 105203–105215. [Google Scholar] [CrossRef]
  12. Dunleavy, C.S.; Golosnoy, I.O.; Curran, J.A.; Clyne, T.W. Characterisation of discharge events during plasma electrolytic oxidation. Surf. Coat. Technol. 2009, 203, 3410–3419. [Google Scholar] [CrossRef][Green Version]
  13. Yerokhin, A.L.; Snizhko, L.O.; Gurevina, N.L.; Leyland, A.; Pilkington, A.; Matthews, A. Discharge characterization in plasma electrolytic oxidation of aluminium. J. Phys. D Appl. Phys. 2003, 36, 2110–2120. [Google Scholar] [CrossRef]
  14. Nominé, A.; Troughton, S.C.; Nominé, A.V.; Henrion, G.; Clyne, T.W. High speed video evidence for localised discharge cascades during plasma electrolytic oxidation. Surf. Coat. Technol. 2015, 269, 125–130. [Google Scholar] [CrossRef]
  15. Simchen, F.; Sieber, M.; Lampke, T. Electrolyte influence on ignition of plasma electrolytic oxidation processes on light metals. Surf. Coat. Technol. 2017, 315, 205–213. [Google Scholar] [CrossRef]
  16. Curran, A.; Clyne, T.W. Thermo-physical properties of plasma electrolytic oxide coatings on aluminium. Surf. Coat. Technol. 2005, 199, 168–179. [Google Scholar] [CrossRef]
  17. Curran, J.A.; Clyne, T.W. Porosity in plasma electrolytic oxide coatings. Acta Mater. 2006, 54, 1985–1993. [Google Scholar] [CrossRef]
  18. Snizhko, L.O.; Yerokhin, A.L.; Gurevina, N.L.; Patalakha, V.A.; Matthews, A. Excessive oxygen evolution during plasma electrolytic oxidation of aluminium. Thin Solid Films 2007, 516, 460–464. [Google Scholar] [CrossRef]
  19. Martin, J.; Melhem, A.; Shchedrina, I.; Duchanoy, T.; Nominè, A.; Henrion, G.; Czerwiec, T.; Belmonte, T. Effects of electrical parameters on plasma electrolytic oxidation of aluminium. Surf. Coat. Technol. 2013, 221, 70–76. [Google Scholar] [CrossRef]
  20. Yerokhin, A.L.; Lyubimov, V.V.; Ashitkov, R.V. Phase formation in ceramic coatings during plasma electrolytic oxidation of aluminium alloys. Ceram. Int. 1998, 24, 1–6. [Google Scholar] [CrossRef]
  21. Tillous, K.; Toll-Duchanoy, T.; Bauer-Grosse, E.; Hericher, L.; Geandier, G. Microstructure and phase composition of microarc oxidation surface layers formed on aluminium and its alloys 2214-T6 and 7050-T74. Surf. Coat. Technol. 2009, 203, 2969–2973. [Google Scholar] [CrossRef]
  22. Liu, C.; Liu, P.; Huang, Z.; Yan, Q.; Guo, R.; Li, D.; Jiang, G.; Shen, D. The correlation between the coating structure and the corrosion behavior of the plasma electrolytic oxidation coating on aluminum. Surf. Coat. Technol. 2016, 286, 223–230. [Google Scholar] [CrossRef]
  23. Hariprasad, S.; Ashfaq, M.; Arunnellaiappan, T.; Harilal, M.; Rameshbabu, N. Role of electrolyte additives on in-vitro corrosion behavior of DC plasma electrolytic oxidization coatings formed on CP-Ti. Surf. Coat. Technol. 2016, 292, 20–29. [Google Scholar]
  24. Rokosz, K.; Hryniewicz, T.; Kacalak, W.; Tandecka, K.; Raaen, S.; Gaiaschi, S.; Chapon, P.; Malorny, W.; Matýsek, D.; Dudek, Ł.; et al. Characterization of Porous Phosphate Coatings Enriched with Calcium, Magnesium, Zinc and Copper Created on CP Titanium Grade 2 by Plasma Electrolytic Oxidation. Metals 2018, 8, 411. [Google Scholar] [CrossRef]
  25. Matykina, E.; Arrabal, R.; Skeldon, P.; Thompson, G.E. Investigation of the growth processes of coatings formed by AC plasma electrolytic oxidation of aluminium. Surf. Coat. Technol. 2009, 54, 6767–6778. [Google Scholar] [CrossRef]
  26. Matykina, E.; Arrabal, R.; Skeldon, P.; Thompson, G.E. Incorporation of zirconia nanoparticles into coatings formed on aluminium by AC plasma electrolytic oxidation. J. Appl. Electrochem. 2008, 38, 1375–1383. [Google Scholar] [CrossRef]
  27. Dehnavi, V.; Luan, B.L.; Liu, X.Y.; Shoesmith, D.W.; Rohani, S. Correlation between plasma electrolytic oxidation treatment stages and coating microstructure on aluminum under unipolar pulsed DC mode. Surf. Coat. Technol. 2015, 269, 91–99. [Google Scholar] [CrossRef]
  28. Fatkullin, A.R.; Parfenov, E.V.; Yerokhin, A.; Lazarev, D.M.; Matthews, A. Effect of positive and negative pulse voltages on surface properties and equivalent circuit of the plasma electrolytic oxidation process. Surf. Coat. Technol. 2015, 284, 427–437. [Google Scholar] [CrossRef]
  29. Krzakala, A.; Kazek-Kesik, A.; Simka, W. Application of plasma electrolytic oxidation to bioactive surface formation on titanium and its alloys. RSC Adv. 2013, 3, 19725–19743. [Google Scholar] [CrossRef]
  30. Rokosz, K.; Hryniewicz, T.; Raaen, S. Development of Plasma Electrolytic Oxidation for improved Ti6Al4V biomaterial surface properties. Int. J. Adv. Manuf. Technol. 2016, 85, 2425–2437. [Google Scholar] [CrossRef]
  31. Rokosz, K.; Hryniewicz, T.; Matysek, D.; Raaen, S.; Valíček, J.; Dudek, Ł.; Harničárová, M. SEM, EDS and XPS analysis of the coatings obtained on titanium after plasma electrolytic oxidation in electrolytes containing copper nitrate. Materials 2016, 9, 318. [Google Scholar] [CrossRef] [PubMed]
  32. Rokosz, K.; Hryniewicz, T.; Raaen, S.; Chapon, P. Development of copper-enriched porous coatings on ternary Ti-Nb-Zr alloy by Plasma Electrolytic Oxidation. Int. J. Adv. Manuf. Technol. 2017, 89, 2953–2965. [Google Scholar] [CrossRef]
  33. Wang, S.; Zhao, Q.; Liu, D.; Du, N. Microstructure and elevated temperature tribological behavior of TiO2/Al2O3 composite ceramic coating formed by microarc oxidation of Ti6Al4V alloy. Surf. Coat. Technol. 2015, 272, 343–349. [Google Scholar] [CrossRef]
  34. Ma, C.; Zhang, M.; Yuan, Y.; Jing, X.; Bai, X. Tribological behavior of plasma electrolytic oxidation coatings on the surface of Mg–8Li–1Al alloy. Tribol. Int. 2012, 47, 62–68. [Google Scholar] [CrossRef]
  35. Rokosz, K.; Hryniewicz, T.; Gaiaschi, S.; Chapon, P.; Raaen, S.; Pietrzak, S.; Malorny, W.; Fernandes, J.S. Characterization of Porous Phosphate Coatings Enriched with Magnesium or Zinc on CP Titanium Grade 2 under DC Plasma Electrolytic Oxidation. Metals 2018, 8, 112. [Google Scholar] [CrossRef]
  36. Sowa, M.; Simka, W. Effect of DC Plasma Electrolytic Oxidation on Surface Characteristics and Corrosion Resistance of Zirconium. Materials 2018, 11, 723. [Google Scholar] [CrossRef] [PubMed]
  37. Liu, C.; He, D.; Yan, Q.; Huang, Z.; Liu, P.; Li, D.; Jiang, G.; Ma, H.; Nash, P.; Shen, D. An investigation of the coating/substrate interface of plasma electrolytic oxidation coated aluminum. Surf. Coat. Technol. 2015, 280, 86–91. [Google Scholar] [CrossRef]
  38. Gu, W.; Lv, G.; Chen, H.; Chen, G.; Feng, W.; Yang, S. Characterisation of ceramic coatings produced by plasma electrolytic oxidation of aluminum alloy. Mater. Sci. Eng. A 2007, 447, 158–162. [Google Scholar] [CrossRef]
  39. Zhu, L.; Guo, Z.; Zhang, Y.; Li, Z.; Sui, M. A mechanism for the growth of a plasma electrolytic oxide coating on Al. Electrochim. Acta 2016, 208, 296–303. [Google Scholar] [CrossRef]
  40. Tillous, E.K.; Toll-Duchanoy, T.; Bauer-Grosse, E. Microstructure and 3D microtomographic characterization of porosity of MAO surface layers formed on aluminium and 2214-T6 alloy. Surf. Coat. Technol. 2009, 203, 1850–1855. [Google Scholar] [CrossRef]
  41. Li, Q.; Liu, C.; Yang, W.; Liang, J. Growth mechanism and adhesion of PEO coatings on 2024 Al alloy. Surf. Eng. 2017, 33, 760–766. [Google Scholar] [CrossRef]
  42. Wang, Z.; Wu, L.; Qi, Y.; Cai, W.; Jiang, Z. Self-lubricating Al2O3/PTFE composite coating formation on surface of aluminium alloy. Surf. Coat. Technol. 2010, 204, 3315–3318. [Google Scholar] [CrossRef]
  43. Li, W.; Qian, Z.; Liu, X.; Zhu, L.; Liu, H. Investigation of micro-arc oxidation coating growth patterns of aluminum alloy by two-step oxidation method. Appl. Surf. Sci. 2015, 356, 581–586. [Google Scholar] [CrossRef]
  44. Zhang, X.M.; Chen, D.F.; Gong, X.Z.; Yang, S.Q.; Tian, X.B. Modulation effects of K2ZrF6 additive on microstructure and heat resistance of micro-arc oxide coatings fabricated on LY12 aluminum alloy. J. Inorg. Mater. 2010, 25, 865–870. [Google Scholar] [CrossRef]
  45. Yang, J.; Lu, X.; Blawert, C.; Di, S.; Zheludkevich, M.L. Microstructure and corrosion behavior of Ca/P coatings prepared on magnesium by plasma electrolytic oxidation. Surf. Coat. Technol. 2017, 319, 359–369. [Google Scholar] [CrossRef]
  46. Lu, X.; Blawert, C.; Huang, Y.; Ovri, H.; Zheludkevich, M.L.; Kainer, K.U. Plasma electrolytic oxidation coatings on Mg alloy with addition of SiO2 particles. Electrochim. Acta 2016, 187, 20–33. [Google Scholar] [CrossRef]
  47. Lu, X.; Blawert, C.; Kainer, K.U.; Zheludkevich, M.L. Investigation of the formation mechanisms of plasma electrolytic oxidation coatings on Mg alloy AM50 using particles. Electrochim. Acta 2016, 196, 680–691. [Google Scholar] [CrossRef]
  48. Ma, H.; Li, D.; Liu, C.; Huang, Z.; He, D.; Yan, Q.; Liu, P.; Nash, P.; Shen, D.J. An investigation of (NaPO3)6 effects and mechanisms during micro-arc oxidation of AZ31 magnesium alloy. Surf. Coat. Technol. 2015, 266, 151–159. [Google Scholar] [CrossRef]
  49. Ezhilselvi, V.; Nithin, J.; Balaraju, J.N.; Subramanian, S. The influence of current density on the morphology and corrosion properties of MAO coatings on AZ31B magnesium alloy. Surf. Coat. Technol. 2016, 288, 221–229. [Google Scholar] [CrossRef]
  50. Sobrinho, P.H.; Savguira, Y.; Ni, Q.; Thorpe, S.J. Statistical analysis of the voltage-time response produced during PEO coating of AZ31B magnesium alloy. Surf. Coat. Technol. 2017, 315, 530–545. [Google Scholar] [CrossRef]
  51. Lu, X.; Sah, S.P.; Scharnagl, N.; Störmer, M.; Starykevich, M.; Mohedano, M.; Blawert, C.; Zheludkevich, M.L.; Kainer, K.U. Degradation behavior of PEO coating on AM50 magnesium alloy produced from electrolytes with clay particle addition. Surf. Coat. Technol. 2015, 269, 155–169. [Google Scholar] [CrossRef]
  52. Pezzato, L.; Brunelli, K.; Gross, S.; Magrini, M.; Dabalà, M. Effect of process parameters of plasma electrolytic oxidation on microstructure and corrosion properties of magnesium alloys. J. Appl. Electrochem. 2014, 44, 867–879. [Google Scholar] [CrossRef]
  53. Zhang, R.F.; Zhang, S.F.; Xiang, J.H.; Zhang, L.H.; Zhang, Y.Q.; Guo, S.B. Influence of sodium silicate concentration on properties of micro arc oxidation coatings formed on AZ91HP magnesium alloys. Surf. Coat. Technol. 2012, 206, 5072–5079. [Google Scholar] [CrossRef]
  54. Cao, F.H.; Lin, L.Y.; Zhang, Z.; Zhang, J.Q.; Cao, C.N. Environmental friendly plasma electrolytic oxidation of AM60 magnesium alloy and its corrosion resistance. Trans. Nonferrous Met. Soc. China 2008, 18, 240–247. [Google Scholar] [CrossRef]
  55. Tang, H.; Xin, T.Z.; Sun, Q.; Yi, C.G.; Jiang, Z.H.; Wang, F.P. Influence of FeSO4 concentration on thermal emissivity of coatings formed on titanium alloy by micro-arc oxidation. Appl. Surf. Sci. 2011, 257, 10839–10844. [Google Scholar] [CrossRef]
  56. Shokouhfar, M.; Allahkaram, S.R. Formation mechanism and surface characterization of ceramic composite coatings on pure titanium prepared by micro-arc oxidation in electrolytes containing nanoparticles. Surf. Coat. Technol. 2016, 291, 396–405. [Google Scholar] [CrossRef]
  57. Rokosz, K.; Hryniewicz, T.; Dudek, Ł.; Matysek, D.; Valíček, J.; Harničárová, M. SEM and EDS analysis of surface layer formed on titanium after plasma electrolytic oxidation in H3PO4 with the addition of Cu(NO3)2. J. Nanosci. Nanotechnol. 2016, 16, 7814–7817. [Google Scholar] [CrossRef]
  58. Liu, S.M.; Yang, X.J.; Cui, Z.D.; Zhu, S.L.; Wei, Q. One-step synthesis of petal-like apatite/titania composite coating on a titanium by micro-arc treating. Mater. Lett. 2011, 65, 1041–1044. [Google Scholar] [CrossRef]
  59. Yan, Y.Y.; Sun, J.F.; Han, Y.; Li, D.C.; Cui, K. Microstructure and bioactivity of Ca, P and Sr doped TiO2 coating formed on porous titanium by micro-arc oxidation. Surf. Coat. Technol. 2010, 205, 1702–1713. [Google Scholar] [CrossRef]
  60. Rokosz, K.; Hryniewicz, T.; Gaiaschi, S.; Chapon, P.; Raaen, S.; Pietrzak, K.; Malorny, W. Characterisation of calcium- and phosphorus-enriched porous coatings on CP Titanium Grade 2 fabricated by plasma electrolytic oxidation. Metals 2017, 7, 354. [Google Scholar] [CrossRef]
  61. Tang, H.; Sun, Q.; Xin, T.Z.; Yi, C.G.; Jiang, Z.H.; Wang, F.P. Influence of Co(CH3COO)2 concentration on thermal emissivity of coatings formed on titanium alloy by micro-arc oxidation. Curr. Appl. Phys. 2012, 12, 284–290. [Google Scholar] [CrossRef]
  62. Rudnev, V.S.; Yarovaya, T.P.; Egorkin, V.S.; Sinebryukov, S.L.; Gnedenkov, S.V. Properties of coatings formed on titanium by plasma electrolytic oxidation in a phosphate-borate electrolyte. Russ. J. Appl. Chem. 2010, 83, 664–670. [Google Scholar] [CrossRef]
  63. Xu, Y.J.; Yao, Z.P.; Jia, F.Z.; Wang, Y.L.; Jiang, Z.H.; Bu, H.T. Preparation of PEO ceramic coating on Ti alloy and its high temperature oxidation resistance. Curr. Appl. Phys. 2010, 10, 698–702. [Google Scholar] [CrossRef]
  64. Qiao, L.P.; Lou, J.; Zhang, S.F.; Qu, B.; Chang, W.H.; Zhang, R.F. The entrance mechanism of calcium and phosphorus elements into micro arc oxidation coatings developed on Ti6Al4V alloy. Surf. Coat. Technol. 2016, 285, 187–196. [Google Scholar] [CrossRef]
  65. Wang, Y.H.; Liu, Z.G.; Ouyang, J.H.; Wang, Y.M.; Zhou, Y. Influence of electrolyte compositions on structure and high-temperature oxidation resistance of microarc oxidation coatings formed on Ti2AlNb alloy. J. Alloys Compd. 2015, 647, 431–437. [Google Scholar] [CrossRef]
  66. Karbowniczek, J.; Muhaffel, F.; Cempura, G.; Cimenoglu, H.; Filemonowicz, A.C. Influence of electrolyte composition on microstructure, adhesion and bioactivity of micro-arc oxidation coatings produced on biomedical Ti6Al7Nb alloy. Surf. Coat. Technol. 2017, 321, 97–107. [Google Scholar] [CrossRef]
  67. Montazeri, M.; Dehghanian, C.; Shokouhfar, M.; Baradaran, A. Investigation of the voltage and time effects on the formation of hydroxyapatite-containing titania prepared by plasma electrolytic oxidation on Ti-6Al-4V alloy and its corrosion behavior. Appl. Surf. Sci. 2011, 257, 7268–7275. [Google Scholar] [CrossRef]
  68. Simka, W.; Sowa, M.; Socha, R.P.; Maciej, A.; Michalska, J. Anodic oxidation of zirconium in silicate solutions. Electrochim. Acta 2013, 104, 518–525. [Google Scholar] [CrossRef]
  69. Sowa, M.; Dercz, G.; Suchanek, K.; Simka, W. Investigation of anodic oxide coatings on zirconium after heat treatment. Appl. Surf. Sci. 2015, 346, 534–542. [Google Scholar] [CrossRef]
  70. Matykina, E.; Arrabal, R.; Skeldon, P.; Thompson, G.E.E.; Wang, P.; Wood, P. Plasma electrolytic oxidation of a zirconium alloy under AC conditions. Surf. Coat. Technol. 2010, 204, 2142–2151. [Google Scholar] [CrossRef]
  71. Cengiz, S.; Uzunoglu, A.; Stanciu, L.; Tarakci, M.; Gencer, Y. Direct fabrication of crystalline hydroxyapatite coating on zirconium by single-step plasma electrolytic oxidation process. Surf. Coat. Technol. 2016, 301, 74–79. [Google Scholar] [CrossRef]
  72. Fidan, S.; Muhaffel, F.; Riool, M.; Cempura, G.; de Boer, L.; Zaat, S.A.J.; Filemonowicz, A.C.; Cimenoglu, H. Fabrication of oxide layer on zirconium by micro-arc oxidation: Structural and antimicrobial characteristics. Mater. Sci. Eng. C 2017, 71, 565–569. [Google Scholar] [CrossRef] [PubMed]
  73. Cengiz, S.; Gencer, Y. The characterization of the oxide based coating synthesized on pure zirconium by plasma electrolytic oxidation. Surf. Coat. Technol. 2014, 242, 132–140. [Google Scholar] [CrossRef]
  74. Cengiz, S.; Azakli, Y.; Tarakci, M.; Stanciu, L.; Gencer, Y. Microarc oxidation discharge types and bio properties of the coating synthesized on zirconium. Mater. Sci. Eng. C 2017, 77, 374–383. [Google Scholar] [CrossRef] [PubMed]
  75. Ha, J.-Y.Y.; Tsutsumi, Y.; Doi, H.; Nomura, N.; Kim, K.-H.H.; Hanawa, T. Enhancement of calcium phosphate formation on zirconium by micro-arc oxidation and chemical treatments. Surf. Coat. Technol. 2011, 205, 4948–4955. [Google Scholar] [CrossRef]
  76. Sandhyarani, M.; Rameshbabu, N.; Venkateswarlu, K.; Rama Krishna, L. Fabrication, characterization and in-vitro evaluation of nanostructured zirconia/hydroxyapatite composite film on zirconium. Surf. Coat. Technol. 2014, 238, 58–67. [Google Scholar]
  77. Sandhyarani, M.; Prasadrao, T.; Rameshbabu, N. Role of electrolyte composition on structural, morphological and in-vitro biological properties of plasma electrolytic oxidation films formed on zirconium. Appl. Surf. Sci. 2014, 317, 198–209. [Google Scholar]
  78. Apelfeld, A.V.; Betsofen, S.Y.; Borisov, A.M.; Vladimirov, B.V.; Savushkina, S.V.; Knyazev, E.V. Stabilization of the high-temperature phases in ceramic coatings on zirconium alloy produced by plasma electrolytic oxidation. J. Phys. Conf. Ser. 2016, 748, 12019. [Google Scholar] [CrossRef][Green Version]
  79. Apelfeld, A.V.; Ashmarin, A.A.; Borisov, A.M.; Vinogradov, A.V.; Savushkina, S.V.; Shmytkova, E.A. Formation of zirconia tetragonal phase by plasma electrolytic oxidation of zirconium alloy in electrolyte comprising additives of yttria nanopowder. Surf. Coat. Technol. 2017, 328, 513–517. [Google Scholar] [CrossRef]
  80. Sowa, M.; Simka, W. Electrochemical Impedance and Polarization Corrosion Studies of Tantalum Surface Modified by DC Plasma Electrolytic Oxidation. Materials 2018, 11, 545. [Google Scholar] [CrossRef] [PubMed]
  81. Sowa, M.; Woszczak, M.; Kazek-Kęsik, A.; Dercz, G.; Korotin, D.M.; Zhidkov, I.S.; Kurmaev, E.Z.; Cholakh, S.O.; Basiaga, M.; Simka, W. Influence of process parameters on plasma electrolytic surface treatment of tantalum for biomedical applications. Appl. Surf. Sci. 2017, 407, 52–63. [Google Scholar] [CrossRef]
  82. Rokosz, K.; Hryniewicz, T.; Chapon, P.; Raaen, S.; Ricardo Zschommler Sandim, H. XPS and GDOES characterization of porous coating enriched with copper and calcium obtained on tantalum via plasma electrolytic oxidation. J. Spectrosc. 2016, 2016, 7093071. [Google Scholar] [CrossRef]
  83. Fattah-alhosseini, A.; Pourmahmoud, M. Passive and semiconducting properties assessment of commercially pure tantalum in Hank’s physiological solution. J. Mater. Eng. Perform. 2018, 27, 116–123. [Google Scholar] [CrossRef]
  84. Sowa, M.; Worek, J.; Dercz, G.; Korotin, D.M.; Kukharenko, A.I.; Kurmaev, E.Z.; Cholakh, S.O.; Basiaga, M.; Simka, W. Surface characterisation and corrosion behaviour of niobium treated in a Ca- and P-containing solution under sparking conditions. Electrochim. Acta 2016, 198, 91–103. [Google Scholar] [CrossRef]
  85. Sowa, M.; Simka, W. Electrochemical behavior of plasma electrolytically oxidized niobium in simulated physiological environment. Surf. Coat. Technol. 2018, 344, 21–131. [Google Scholar] [CrossRef]
  86. Rokosz, K.; Hryniewicz, T. Comparative SEM and EDX analysis of surface coatings created on niobium and titanium alloys after Plasma Electrolytic Oxidation (PEO). Tehnički Vjesnik-Technical Gazette 2017, 24, 465–472. [Google Scholar]
  87. Gomes, M.A.B.; Onofre, S.; Juanto, S.; Bulhões, L.O.S. Anodization of niobium in sulphuric acid media. J. Appl. Electrochem. 1991, 21, 1023–1026. [Google Scholar] [CrossRef]
  88. Pereira, B.L.; Lepienski, C.M.; Mazzaro, I.; Kuromoto, N.K. Apatite grown in niobium by two-step plasma electrolytic oxidation. Mater. Sci. Eng. C Mater. 2017, 77, 1235–1241. [Google Scholar] [CrossRef] [PubMed]
  89. Stojadinović, S.; Tadić, N.; Vasilic, R. Plasma electrolytic oxidation of hafnium. J. Refract. Met. Hard Mater. 2017, 69, 153–157. [Google Scholar] [CrossRef]
  90. Han, Y.; Hong, S.H.; Xu, K.W. Synthesis of nanocrystalline titania films by micro-arc oxidation. Mater. Lett. 2002, 56, 744–747. [Google Scholar] [CrossRef]
  91. Han, Y.; Xu, K. Photoexcited formation of bone apatite-like coatings on micro-arc oxidized titanium. J. Biomed. Mater. Res. 2004, 71A, 608–614. [Google Scholar] [CrossRef] [PubMed]
  92. Huang, P.; Xu, K.W.; Han, Y. Preparation and apatite layer formation of plasma electrolytic oxidation film on titanium for biomedical application. Mater. Lett. 2005, 59, 185–189. [Google Scholar] [CrossRef]
  93. Song, W.H.; Jun, Y.K.; Han, Y.; Hong, S.H.; Kim, H.E.; Heo, S.J.; Koak, J.Y. Biomimetic apatite coatings on micro-arc oxidized titania. Biomaterials 2004, 25, 3341–3349. [Google Scholar] [CrossRef] [PubMed]
  94. Zhang, Y.M.; Bataillon-Linez, P.; Huang, P.; Zhao, Y.M.; Han, Y.; Traisnel, M.; Xu, K.W.; Hildebrand, H.F. Surface analyses of micro-arc oxidized and hydrothermally treated titanium and effect on osteoblast behavior. J. Biomed. Mater. Res. 2003, 68, 383–391. [Google Scholar] [CrossRef] [PubMed]
  95. Li, L.H.; Kong, Y.M.; Kim, H.W.; Kim, Y.W.; Kim, H.E.; Heo, S.J.; Koak, J.Y. Improved biological performance of Ti implants due to surface modification by micro-arc oxidation. Biomaterials 2004, 25, 2867–2875. [Google Scholar] [CrossRef] [PubMed]
  96. Lee, S.H.; Kim, H.W.; Lee, E.J.; Li, L.H.; Kim, H.E. Hydroxyapatite–TiO2 hybrid coating on Ti implants. J. Biomater. Appl. 2006, 20, 194–208. [Google Scholar] [CrossRef] [PubMed]
  97. Han, Y.; Hong, S.H.; Xu, K.W. Structure and in vitro bioactivity of titania-based films by micro-arc oxidation. Surf. Coat. Technol. 2003, 168, 249–258. [Google Scholar] [CrossRef]
  98. Teh, T.H.; Berkani, A.; Mato, S.; Skeldon, P.; Thompson, G.E.; Habazaki, H.; Shimizu, K. Initial stages of plasma electrolytic oxidation of titanium. Corros. Sci. 2003, 45, 2757–2768. [Google Scholar] [CrossRef]
  99. Rudnev, V.S.; Vasilyeva, M.S.; Kondrikov, N.B.; Tyrina, L.M. Plasma-electrolytic formation, composition and catalytic activity of manganese oxide containing structures on titanium. Appl. Surf. Sci. 2005, 252, 1211–1220. [Google Scholar] [CrossRef]
  100. Ryu, H.S.; Song, W.H.; Hong, S.H. Biomimetic apatite induction on Ca-containing titania. Curr. Appl. Phys. 2005, 5, 512–515. [Google Scholar] [CrossRef]
  101. Chen, J.Z.; Shi, Y.L.; Wang, L.; Yan, F.Y.; Zhang, F.Y. Preparation and properties of hydroxyapatite-containing titania coating by micro-arc oxidation. Mater. Lett. 2006, 60, 2538–2543. [Google Scholar] [CrossRef]
  102. Matykina, E.; Montuori, M.; Gough, J.; Monfort, F.; Berkani, A.; Skeldon, P.; Thompson, G.E.; Habazaki, H. Spark anodising of titanium for biomedical applications. Trans. IMF 2006, 84, 125–133. [Google Scholar] [CrossRef]
  103. Han, I.H.; Choi, J.H.; Zhao, B.H.; Baik, H.K.; Lee, I.S. Effects of electrical wave form on pore size of micro-arc oxidized TiO2 film. Key Eng. Mater. 2006, 309–311, 375–378. [Google Scholar] [CrossRef]
  104. Shokouhfar, M.; Dehghanian, C.; Montazeri, M.; Baradaran, A. Preparation of ceramic coating on Ti substrate by plasma electrolytic oxidation in different electrolytes and evaluation of its corrosion resistance: Part II. Appl. Surf. Sci. 2012, 258, 2416–2423. [Google Scholar] [CrossRef]
  105. Zhu, L.; Ye, X.; Tang, G.; Zhao, N.; Gong, Y.; Zhao, Y.; Zhao, J.; Zhang, X. Corrosion test, cell behavior test, and in vivo study of gradient TiO2 layers produced by compound electrochemical oxidation. J. Biomed. Mater. Res. A 2006, 78, 515–522. [Google Scholar] [CrossRef] [PubMed]
  106. Habazaki, H.; Onodera, T.; Fushimi, K.; Konno, H.; Toyotake, K. Spark anodizing of β-Ti alloy for wear-resistant coating. Surf. Coat. Technol. 2007, 201, 8730–8737. [Google Scholar] [CrossRef][Green Version]
  107. Kim, M.S.; Ryu, J.J.; Sung, Y.M. One-step approach for nano-crystalline hydroxyapatite coating on titanium via micro-arc oxidation. Electrochem. Commun. 2007, 9, 1886–1891. [Google Scholar] [CrossRef]
  108. Ragalevičius, R.; Stalnionis, G.; Niaura, G.; Jagminas, A. Micro-arc oxidation of Ti in a solution of sulfuric acid and Ti+3 salt. Appl. Surf. Sci. 2008, 254, 1608–1613. [Google Scholar] [CrossRef]
  109. Zhang, W.; Du, K.; Yan, C.; Wang, F. Preparation and characterization of a novel Si-incorporated ceramic film on pure titanium by plasma electrolytic oxidation. Appl. Surf. Sci. 2008, 254, 5216–5223. [Google Scholar] [CrossRef]
  110. Lebukhova, N.V.; Rudnev, V.S.; Kirichenko, E.A.; Chigrin, P.G.; Lukiyanchuk, I.V.; Yarovaya, T.P. Effect of the structure of the oxidized titanium surface on the particle size and properties of the deposited copper-molybdate catalyst. Prot. Met. Phys. Chem. Surf. 2016, 52, 1024–1030. [Google Scholar] [CrossRef]
  111. Terleeva, O.P.; Sharkeev, Y.P.; Slonova, A.I.; Mironov, I.V.; Legostaeva, E.V.; Khlusov, I.A.; Matykina, E.; Skeldon, P.; Thompson, G.E. Effect of microplasma modes and electrolyte composition on micro-arc oxidation coatings on titanium for medical applications. Surf. Coat. Technol. 2010, 205, 1723–1729. [Google Scholar] [CrossRef]
  112. Wang, Y.M.; Lei, T.Q.; Jiang, B.L.; Guo, L.X. Growth, microstructure and mechanical properties of microarc oxidation coatings on titanium alloy in phosphate-containing solution. Appl. Surf. Sci. 2004, 233, 258–267. [Google Scholar] [CrossRef]
  113. Tang, H.; Sun, Q.; Yi, C.G.; Jiang, Z.H.; Wang, F.P. High emissivity coatings on titanium alloy prepared by micro-arc oxidation for high temperature application. J. Mater. Sci. 2012, 47, 2162–2168. [Google Scholar] [CrossRef]
  114. Santos, A.D.; Araujo, J.R.; Landi, S.M.; Kuznetsov, A.; Granjeiro, J.M.; Sena, L.A.D.; Achete, C.A. A study of the physical, chemical and biological properties of TiO2 coatings produced by micro-arc oxidation in a Ca-P-based electrolyte. J. Mater. Sci. Mater. Med. 2014, 25, 1769–1780. [Google Scholar] [CrossRef] [PubMed]
  115. Li, Q.B.; Yang, W.B.; Liu, C.C.; Wang, D.A.; Liang, J. Correlations between the growth mechanism and properties of micro-arc oxidation coatings on titanium alloy: Effects of electrolytes. Surf. Coat. Technol. 2017, 316, 162–170. [Google Scholar] [CrossRef]
  116. Sharifi, H.; Aliofkhazraei, M.; Darband, G.; Rouhaghdam, A.S. Characterization of PEO nanocomposite coatings on titanium formed in electrolyte containing atenolol. Surf. Coat. Technol. 2016, 304, 438–449. [Google Scholar] [CrossRef]
  117. Zhu, X.L.; Chen, J.; Scheideler, L.; Reichl, R.; Geis-Gerstorfer, J. Effects of topography and composition of titanium surface oxides on osteoblast responses. Biomaterials 2004, 25, 4087–4103. [Google Scholar] [CrossRef] [PubMed]
  118. Geetha, M.; Singh, A.K.; Asokamani, R.; Gogia, A.K. Ti based biomaterials, the ultimate choice for orthopaedic implants—A review. Prog. Mater. Sci. 2009, 54, 397–425. [Google Scholar] [CrossRef]
  119. Jayaraman, M.; Meyer, U.; Bühner, M.; Joos, U.; Wiesmann, H.P. Influence of titanium surfaces on attachment of osteoblast-like cells in vitro. Biomaterials 2004, 25, 625–631. [Google Scholar] [CrossRef]
  120. Cai, Y.L.; Zhang, J.J.; Zhang, S.; Venkatraman, S.S.; Zeng, X.T.; Du, H.J.; Mondal, D. Osteoblastic cell response on fluoridated hydroxyapatite coatings: The effect of magnesium incorporation. Biomed. Mater. 2010, 5, 054114. [Google Scholar] [CrossRef] [PubMed]
  121. Piocha, D.; Zima, A.; Paszkiewicz, Z.; Slosarczyk, A. Physicochemical properties of the novel biphasic hydroxyapatite–magnesium phosphate biomaterial. Acta Bioeng. Biomech. 2013, 15, 53–63. [Google Scholar]
  122. Grigolato, R.; Pizzi, N.; Brotto, M.C.; Corrocher, G.; Desando, G.; Grigolo, B. Magnesium-enriched hydroxyapatite as bone filler in an ameloblastoma mandibular defect. Int. J. Clin. Exp. Med. 2015, 8, 281–288. [Google Scholar] [PubMed]
  123. Nygren, H.; Bigdeli, N.; Ilver, L.; Malmberg, P. Mg-corrosion, hydroxyapatite, and bone healing. Biointerphases 2017, 12, 02C407. [Google Scholar] [CrossRef] [PubMed]
  124. Laurencin, D.; Almora-Barrios, N.; de Leeuw, N.H.; Gervais, C.; Bonhomme, C.; Mauri, F.; Chrzanowski, W.; Knowles, J.C.; Newport, R.J.; Wong, A.; et al. Magnesium incorporation into hydroxyapatite. Biomaterials 2011, 32, 1826–1837. [Google Scholar] [CrossRef] [PubMed][Green Version]
  125. Farzadi, A.; Bakhshi, F.; Solati-Hashjin, M.; Asadi-Eydivand, M.; Abu Osman, A.A. Magnesium incorporated hydroxyapatite: Synthesis and structural properties characterization. Ceram. Int. 2014, 40, 6021–6029. [Google Scholar] [CrossRef]
  126. Hu, H.; Zhang, W.; Qiao, Y.; Jiang, X.; Liu, X.; Ding, C. Antibacterial activity and increased bone marrow stem cell functions of Zn-incorporated TiO2 coatings on titanium. Acta Biomater. 2012, 8, 904–915. [Google Scholar] [CrossRef] [PubMed]
  127. Zhang, X.; Wang, H.; Li, J.; He, X.; Hang, R.; Huang, X.; Tian, L.; Tang, B. Corrosion behavior of Zn-incorporated antibacterial TiO2 porous coating on titanium. Ceram. Int. 2016, 42, 17095–17100. [Google Scholar] [CrossRef]
  128. Zhang, L.; Gao, Q.; Han, Y. Zn and Ag co-doped anti-microbial TiO2 coatings on Ti by micro-arc oxidation. J. Mater. Sci. Technol. 2016, 32, 919–924. [Google Scholar] [CrossRef]
  129. Zhang, J.Y.; Ai, H.J.; Qi, M. Osteoblast growth on the surface of porous Zn-containing HA/TiO2 hybrid coatings on Ti substrate by MAO plus sol-gel methods. Surf. Coat. Technol. 2013, 228, S202–S205. [Google Scholar] [CrossRef]
  130. Zhao, B.H.; Zhang, W.; Wang, D.N.; Feng, W.; Liu, Y.; Lin, Z.; Du, K.Q.; Deng, C.F. Effect of Zn content on cytoactivity and bacteriostasis of micro-arc oxidation coatings on pure titanium. Surf. Coat. Technol. 2013, 228, S428–S432. [Google Scholar] [CrossRef]
  131. Jin, G.D.; Qin, H.; Cao, H.L.; Qian, S.; Zhao, Y.C.; Peng, X.C.; Zhang, X.L.; Liu, X.Y.; Chu, P.K. Synergistic effects of dual Zn/Ag ion implantation in osteogenic activity and antibacterial ability of titanium. Biomaterials 2014, 35, 7699–7713. [Google Scholar] [CrossRef] [PubMed]
  132. Huang, Y.; Zhang, X.J.; Mao, H.H.; Li, T.T.; Zhao, R.L.; Yan, Y.J.; Pang, X.F. Osteoblastic cell responses and antibacterial efficacy of Cu/Zn co-substitued hydroxyapatite coatings on pure titanium using electrodeposition method. RSC Adv. 2015, 5, 17076–17086. [Google Scholar] [CrossRef]
  133. Rokosz, K.; Hryniewicz, T.; Gaiaschi, S.; Chapon, P.; Raaen, S.; Malorny, W.; Matysek, W.; Pietrzak, K. Development of porous coatings enriched with magnesium and zinc obtained by DC Plasma Electrolytic Oxidation. Micromachines 2018, 9, 332. [Google Scholar] [CrossRef]
  134. Zhao, L.Z.; Chu, P.K.; Zhang, Y.M.; Wu, Z.F. Antibacterial coatings on titanium implants. J. Biomed. Mater. Res. Part B 2009, 91, 470–480. [Google Scholar] [CrossRef] [PubMed]
  135. Zhu, W.; Zhang, Z.; Gu, B.; Sun, J.; Zhu, L. Biological activity and antibacterial property of nano-structured TiO2 coating incorporated with Cu prepared by micro-arc oxidation. J. Mater. Sci. Technol. 2013, 29, 237–244. [Google Scholar] [CrossRef]
  136. Zhang, L.; Guo, J.; Huang, X.; Zhang, Y.; Han, Y. The dual function of Cu-doped TiO2 coatings on titanium for application in percutaneous implants. J. Mater. Chem. B 2016, 4, 3788–3800. [Google Scholar] [CrossRef]
  137. Moulder, J.F.; Stickle, W.F.; Sobol, P.E.; Bomben, K.D. Handbook of X-ray Photoelectron Spectroscopy; Perkin-Elmer Corporation: Eden Prairie, MN, USA, 1992. [Google Scholar]
  138. Wagner, C.D.; Naumkin, A.V.; Kraut-Vass, A.; Allison, J.W.; Powell, C.J.; Rumble, J.R., Jr. NIST Standard Reference Database 20, Version 3.4. 2003. Available online: http://srdata.nist.gov/xps (accessed on 1 July 2018).
  139. Casa Software Ltd. CasaXPS: Processing Software for XPS, AES, SIMS and More. 2009. Available online: http://www.casaxps.com (accessed on 1 July 2018).
  140. Gaiaschi, S.; Richard, S.; Chapon, P.; Acher, O. Real-time measurement in glow discharge optical emission spectrometry via differential interferometric profiling. J. Anal. Atom. Spectrom. 2017, 32, 1798–1804. [Google Scholar] [CrossRef]
  141. Pulsed RF Glow Discharge Optical Emission Spectrometry—Ultra Fast Elemental Depth Profiling, HORIBA Scientific, Printed in France—©HORIBA Jobin Yvon. 2014, p. 7. Available online: http://www.horiba.com/scientific/products/atomic-emission-spectroscopy/glow-discharge/ (accessed on 1 July 2018).
Materials 11 01680 g001 550
Figure 1. Surface morphologies of surfaces after PEO processing.
Figure 1. Surface morphologies of surfaces after PEO processing.
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Materials 11 01680 g002 550
Figure 2. Atomic ratios (EDS) of coatings formed in Electrolyte 1.
Figure 2. Atomic ratios (EDS) of coatings formed in Electrolyte 1.
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Materials 11 01680 g003 550
Figure 3. Atomic ratios (EDS) of coatings formed in Electrolyte 2.
Figure 3. Atomic ratios (EDS) of coatings formed in Electrolyte 2.
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Materials 11 01680 g004 550
Figure 4. Diffractogram XRD results of PEO coatings obtained in (a) Electrolyte 1 and (b) Electrolyte 2.
Figure 4. Diffractogram XRD results of PEO coatings obtained in (a) Electrolyte 1 and (b) Electrolyte 2.
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Materials 11 01680 g005 550
Figure 5. GDEOS signals (black), first derivatives (red continuous line), and second derivatives (brown dashed line) for samples formed in Electrolyte 1.
Figure 5. GDEOS signals (black), first derivatives (red continuous line), and second derivatives (brown dashed line) for samples formed in Electrolyte 1.
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Materials 11 01680 g006 550
Figure 6. GDEOS signals (black), first derivatives (red continuous line), and second derivatives (brown dashed line) for samples formed in Electrolyte 2.
Figure 6. GDEOS signals (black), first derivatives (red continuous line), and second derivatives (brown dashed line) for samples formed in Electrolyte 2.
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Figure 7. XPS spectra for titanium samples after PEO treatment in Electrolyte 1.
Figure 7. XPS spectra for titanium samples after PEO treatment in Electrolyte 1.
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Figure 8. XPS spectra for titanium samples after PEO treatment in Electrolyte 2.
Figure 8. XPS spectra for titanium samples after PEO treatment in Electrolyte 2.
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Table
Table 1. Electrolytes and conditions of the plasma electrolytic oxidation (PEO) process.
Table 1. Electrolytes and conditions of the plasma electrolytic oxidation (PEO) process.
ElectrolytesVoltage Current DensityRef.
H2O, NaAlO2, Na3PO4·12H2O, KOH, NaCl100–900 mA·cm−2 (f = 50 Hz)[7]
H2O, Na3PO4·12H2O, KOH, Na2SO4, (HOCH2)3CNH2, (NH4)2HPO4, C2H7NO270 mA·cm−2 (f = 50 Hz)[23]
H3PO4, Ca(NO3)2·4H2O, Mg(NO3)2·6H2O, Cu(NO3)2·3H2O, Zn(NO3)2·6H2O500, 575, 650 V[24]
H3PO4, Cu(NO3)2·3H2O450 V[32]
H2O, Na2SiO3, (NaPO3)6, NaAlO2 microparticle80 mA·cm−2 (f = 300 Hz)[33]
H3PO4, Mg(NO3)2·6H2O, Zn(NO3)2·6H2O500–650 V[35]
H2O, Na3PO4, FeSO4350 V (f = 100 Hz)[55]
H2O, NaAlO2, KOH400 V (f = 2000 Hz)[56]
H2O, (CH3COO)2Ca·H2O, NaH2PO4·2H2O300, 390 V (f = 900 Hz)[58]
H2O, Ca(CH3COO)2,Sr(CH3COO)2400, 450 V (f = 100 Hz)[59]
H3PO4, Ca(NO3)2·4H2O500, 575, 650 V[60]
H2O, Na3PO4, Co(CH3COO)2350 V (f = 100 Hz)[61]
H2O, Na3PO4·12H2O, Na2B4O7·10H2O, Na3WO4·2H2O50 mA·cm−2[62]
H2O, Na2SiO3, Na2CO3, NaOH12 mA·cm−2 (f = 100 Hz)[63]
H2O, C6H18O24P6, KOH, EDTA-Na2, Ca(CH3COO)220, 50, 80 V[64]
H2O, NaAlO2, Na2SiO3, (NaPO3)6550 V[65]
H2O, Na2HPO4, C4H6O4Ca·H2O+400 V/−80 V (f = 250 Hz)[66]
H2O, C3H9O6P, C4H6O4Ca·H2O+400 V/−80 V (f = 250 Hz)[66]
H2O, Na2HPO4, C3H7CaO6P·H2O+400 V/−80 V (f = 250 Hz)[66]
H2O, (CH3COO)2Ca·H2O, NaH2PO4·H2O350–500 V (f = 1000 Hz)[67]
H2O, Ca(CH3COO)2·H2O300 V (f = 1000 Hz)[90]
H2O, (CH1COO)2Ca, C3H7Na2O6P250–400 V (f = 100 Hz)[91]
H2O, (CH3COO)2Ca·H2O, C3H7Na2O6P·5H2O450 V (f = 100 Hz)[92]
H2O, (CH3COO)2Ca·H2O, C3H7Na2O6P·5H2O250–500 V (f = 1000 Hz)[93,94]
H2O, Ca(CH3COO)2·H2O, CaC3H7O6P190–600 V (f = 660 Hz)[95,96]
H2O, (CH3COO)2Ca·H2O, C3H7Na2O6P·5H2O200–500 V (f = 900 Hz)[97]
H2O, Na4P2O7·10H2O and KOH, NaAlO20–300 V[98]
Na2B4O7·10H2O, (CH3COO)2Mn·4H2O450–500 V[99]
H2O, (CH3COO)2Ca·H2O230 V[100]
H2O, (CH3COO)2Ca·H2O, NaH2PO4·2H2O260–420 V[101]
H2O, CaHPO4, Ca(H2PO4)2, Na6P6O18, Ca(CH3COO)220, 100 mA·cm−2[102]
H2O, KOH290 V (f = 100–200 Hz)[103]
H2O, KOH350 V (f = 1000 Hz)[104]
H2O, (NaPO3)6, NaF, NaAlO2150–200 V[105]
H2O, K2Al2O4, Na3PO4, NaOH400 V[106]
H2O, CaCl2 and KH2PO4320–340 V[107]
H2O, H2SO4 and Ti2(SO4)31100 V[108]
H2O, Na2(EDTA), CaO, Ca(H2PO4)2, Na2SiO3·H2O 350 V (f = 200 Hz)[109]
H2O, Na2SiO3, NaOH280 V[110]
H2O, CaO, Na6P6O18, Na2H2EDTA⋅5.5H2O, KOHAC 0.5–2 mA·cm−2[111]
2O, (NaPO3)6, NaF, NaAlO260 mA·cm−2 (f = 100, 600 Hz)[112]
H2O, Na3PO4, FeSO4, Co(CH3COO)2, Ni(CH3COO)2, K2ZrF6350 V (f = 100 Hz)[113]
H2O, Ca(CH3COO)2·H2O, C3H7Na2O6P150 V[114]
H2O, Na2SiO3·9H2O, Na3PO4·12H2O, Na2SiO3·9H2O, Na3PO4·12H2O80 mA·cm−2 (f = 150 Hz)[115]
H2O, Na3PO4·12H2O, α-Al2O3 nanoparticles20 mA·cm−2[116]
Table
Table 2. Experimental plan and code sample names.
Table 2. Experimental plan and code sample names.
Sample NameVoltageElectrolyte TypeElectrolyte Composition
SaltsSalt Concentrations (g/L)
Ti_CaMgZn_500V500 VElectrolyte 1Ca(NO3)2·4H2O and Mg(NO3)2·6H2O & Zn(NO3)2·6H2O166.7 + 166.7 + 166.7
Ti_CaMgZn_575V575 V
Ti_CaMgZn_650V650 V
Ti_CaMgCu_500V500 VElectrolyte 2Ca(NO3)2·4H2O and Mg(NO3)2·6H2O & Cu(NO3)2·3H2O166.7 + 166.7 + 166.7
Ti_CaMgCu_575V575 V
Ti_CaMgCu_650V650 V
Table
Table 3. Setups of SEM, energy dispersive spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), glow discharge optical emission spectroscopy (GDEOS), and XRD equipment.
Table 3. Setups of SEM, energy dispersive spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), glow discharge optical emission spectroscopy (GDEOS), and XRD equipment.
TechniqueEquipmentManufacturer
SEMQuanta 650 FEIField Electron and Iron Company, Hillsboro, OR, USA
EDSNoran System SixEDS, Silicon Drift Detectors: Keith Thompson, Thermo Fisher Scientific, Madison, WI, USA
XPSSCIENCE SES 2002Scienta AB, Scienta Omicron, Uppsala, Sweden
GDOESGD Profiler 2HORIBA Scientific, Palaiseau, France
XRDBruker-AXS D8 AdvanceBruker Corporation, Billerica, MA, USA
Table
Table 4. Statistical description of EDS of coatings formed in Electrolyte 1. n.u., no units.
Table 4. Statistical description of EDS of coatings formed in Electrolyte 1. n.u., no units.
RatiosVoltage x ¯ σQ1Q2Q3
Ca/P
n.u.		500 V0.0510.0030.0500.0520.052
575 V0.0630.0030.0620.0640.065
650 V0.0690.0030.0680.0710.071
Mg/P
n.u.		500 V0.0510.0040.0490.0510.053
575 V0.0580.0030.0570.0600.060
650 V0.0600.0060.0570.0630.063
Zn/P
n.u.		500 V0.0520.0040.0500.0530.054
575 V0.0650.0050.0630.0680.068
650 V0.0710.0100.0650.0750.075
M/P
n.u.		500 V0.1530.0080.1490.1510.157
575 V0.1870.0060.1840.1880.190
650 V0.2000.0150.1920.1950.206
Table
Table 5. Statistical description of EDS of coatings formed in Electrolyte 2. n.u., no units.
Table 5. Statistical description of EDS of coatings formed in Electrolyte 2. n.u., no units.
RatiosVoltage x ¯ σQ1Q2Q3
Ca/P
n.u.		500 V0.0620.0030.0600.0610.062
575 V0.0680.0040.0660.0680.071
650 V0.0710.0030.0680.0720.073
Mg/P
n.u.		500 V0.0580.0020.0570.0570.059
575 V0.0590.0030.0560.0600.061
650 V0.0640.0030.0640.0640.066
Cu/P
n.u.		500 V0.0390.0030.0370.0400.040
575 V0.0480.0020.0470.0480.050
650 V0.0620.0050.0590.0610.063
M/P
n.u.		500 V0.1580.0060.1560.1560.159
575 V0.1750.0060.1720.1760.177
650 V0.1970.0040.1950.1960.197

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Rokosz, K.; Hryniewicz, T.; Gaiaschi, S.; Chapon, P.; Raaen, S.; Matýsek, D.; Dudek, Ł.; Pietrzak, K. Novel Porous Phosphorus–Calcium–Magnesium Coatings on Titanium with Copper or Zinc Obtained by DC Plasma Electrolytic Oxidation: Fabrication and Characterization. Materials 2018, 11, 1680. https://doi.org/10.3390/ma11091680

AMA Style

Rokosz K, Hryniewicz T, Gaiaschi S, Chapon P, Raaen S, Matýsek D, Dudek Ł, Pietrzak K. Novel Porous Phosphorus–Calcium–Magnesium Coatings on Titanium with Copper or Zinc Obtained by DC Plasma Electrolytic Oxidation: Fabrication and Characterization. Materials. 2018; 11(9):1680. https://doi.org/10.3390/ma11091680

Chicago/Turabian Style

Rokosz, Krzysztof, Tadeusz Hryniewicz, Sofia Gaiaschi, Patrick Chapon, Steinar Raaen, Dalibor Matýsek, Łukasz Dudek, and Kornel Pietrzak. 2018. "Novel Porous Phosphorus–Calcium–Magnesium Coatings on Titanium with Copper or Zinc Obtained by DC Plasma Electrolytic Oxidation: Fabrication and Characterization" Materials 11, no. 9: 1680. https://doi.org/10.3390/ma11091680

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