Synthesis of Hydroxyapatite Coatings on Titanium Substrates by Plasma Electrolytic Oxidation
Main Article Content
Abstract
In this study, hydroxyapatite (HA) coatings were synthesized on titanium substrates using the plasma electrolytic oxidation (PEO) technique to enhance corrosion resistance and improve the biocompatibility of implant materials. The experiments were conducted in an electrolyte containing calcium acetate hydrate and sodium dihydrogen phosphate monohydrate under a constant voltage of 500 V, with treatment durations of 1, 3, 5, and 7 minutes. The surface morphology and structural characteristics of the coatings were analyzed using various characterization techniques. X-ray diffraction (XRD) results revealed the distinct formation of hydroxyapatite phases when the treatment duration reached 7 minutes. Scanning electron microscopy (SEM) observations showed a uniformly porous surface morphology while energy-dispersive X-ray spectroscopy (EDS) confirmed the presence of calcium and phosphorus elements. Furthermore, corrosion performance evaluated in simulated body fluid (SBF) using Tafel polarization curves demonstrated that the PEO-coated samples exhibited significantly higher corrosion potentials and polarization resistance than bare titanium, indicating superior surface protection. In vitro cell culture experiments using BHK cells for 48 h and 72 h confirmed good cell attachment and proliferation on the HA-coated surfaces. These results demonstrate that hydroxyapatite coatings prepared by the plasma electrolytic oxidation method hold great potential for biomedical implant applications.
Keywords:
Plasma electrolytic oxidation (PEO), titanium, hydroxyapatite, coating, biomedical.
References
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[30] D. Wei, Y. Zhou, D. Jia, Y. Wang, Structure of Calcium Titanate/Titania Bioceramic Composite Coatings on Titanium Alloy and Apatite Deposition on Their Surfaces in A Simulated Body Fluid, Surface and Coatings Technology, Vol. 201, No. 21, 2007, pp. 8715-8722, https://doi.org/10.1016/j.surfcoat.2007.04.124.
[31] A. Yerokhin, E. V. Parfenov, A. Matthews, In situ Impedance Spectroscopy of The Plasma Electrolytic Oxidation Process for Deposition of Ca- and P-Containing Coatings on Ti, Surface and Coatings Technology, Vol. 301, 2016, pp. 54-62, https://doi.org/10.1016/j.surfcoat.2016.02.035.
[32] J. Sun, Y. Han, X. Huang, Hydroxyapatite Coatings Prepared by Micro-Arc Oxidation in Ca- and P-Containing Electrolyte, Surface and Coatings Technology, Vol. 201, No. 9-11, 2007, pp. 5655-5658, https://doi.org/10.1016/j.surfcoat.2006.07.052.
[33] T. T. An et al., Corrosion Resistance of Zinc-Doped Hydroxyapatite Coating on Titanium Substrate Using Plasma Electrolytic Oxidation for Biomedical Applications, J. of Materi Eng and Perform, Vol. 34, No. 8, 2025,
pp. 6743-6754, https://doi.org/10.1007/s11665-024-09636-8.
[34] V. Karageorgiou, D. Kaplan, Porosity of 3D Biomaterial Scaffolds and Osteogenesis, Biomaterials, Vol. 26,
No. 27, 2005, pp. 5474-5491, https://doi.org/10.1016/j.biomaterials.2005.02.002.
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[38] M. Montazeri, C. Dehghanian, M. Shokouhfar, A. Baradaran, 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, Applied Surface Science, Vol. 257, No. 16, 2011, pp. 7268-7275, https://doi.org/10.1016/j.apsusc.2011.03.103.
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[2] M. Geetha, A. K. Singh, R. Asokamani, A. K. Gogia, Ti Based Biomaterials, The Ultimate Choice for Orthopaedic Implants - A Review, Progress in Materials Science, Vol. 54, No. 3, 2009, pp. 397-425, https://doi.org/10.1016/j.pmatsci.2008.06.004.
[3] M. Long, H. J. Rack, Titanium Alloys in Total Joint Replacement - A Materials Science Perspective, Biomaterials, Vol. 19, No. 18, 1998, pp. 1621-1639, https://doi.org/10.1016/S0142-9612(97)00146-4.
[4] K. Fatehi, F. Moztarzadeh, M. S. Hashjin, M. Tahriri, M. Rezvannia, R. Ravarian, In vitro Biomimetic Deposition of Apatite on Alkaline and Heat Treated Ti6A14V Alloy Surface, Bull Mater Sci, Vol. 31, No. 2, 2008,
pp. 101-108, https://doi.org/10.1007/s12034-008-0018-0.
[5] R. Halouani, D. B. Assolant, E. Champion, A. Ababou, Microstructure and Related Mechanical Properties of Hot Pressed Hydroxyapatite Ceramics, J Mater Sci: Mater Med, Vol. 5, No. 8, 1994, pp. 563-568, https://doi.org/10.1007/BF00124890.
[6] M. Ł. Kuska, P. Krawczyk, A. Martyla, W. Hedzelek, B. D. Bobkowska, Hydroxyapatite Coating on Titanium Endosseous Implants for Improved Osseointegration: Physical and Chemical Considerations, Adv Clin Exp Med, Vol. 27, No. 8, 2018, pp. 1055-1059, https://doi.org/10.17219/acem/69084.
[7] S. Kozerski, L. Pawlowski, R. Jaworski, F. Roudet, F. Petit, Two Zones Microstructure of Suspension Plasma Sprayed Hydroxyapatite Coatings, Surface and Coatings Technology, Vol. 204, No. 9-10, 2010, pp. 1380-1387, https://doi.org/10.1016/j.surfcoat.2009.09.020.
[8] R. d’Haese, L. Pawlowski, M. Bigan, R. Jaworski, M. Martel, Phase Evolution of Hydroxapatite Coatings Suspension Plasma Sprayed Using Variable Parameters in Simulated Body Fluid, Surface and Coatings Technology, Vol. 204, No. 8, 2010, pp. 1236-1246, https://doi.org/10.1016/j.surfcoat.2009.10.022.
[9] J. Wang, C. Huang, Q. Wan, Y. Chen, Y. Chao, Characterization of Fluoridated Hydroxyapatite/Zirconia Nano-Composite Coating Deposited by A Modified Electrocodeposition Technique, Surface and Coatings Technology, Vol. 204, No. 16-17, 2010, pp. 2576-2582, https://doi.org/10.1016/j.surfcoat.2010.01.042.
[10] X. Yang, B. Zhang, J. Lu, J. Chen, X. Zhang, Z. Gu, Biomimetic Ca-P Coating on Pre-Calcified Ti Plates by Electrodeposition Method, Applied Surface Science, Vol. 256, No. 9, 2010, pp. 2700-2704, https://doi.org/10.1016/j.apsusc.2009.11.004.
[11] K. Cheng, S. Zhang, W. Weng, X. Zeng, The Interfacial Study of Sol-Gel-Derived Fluoridated Hydroxyapatite Coatings, Surface and Coatings Technology, Vol. 198, No. 1-3, 2005, pp. 242-246, https://doi.org/10.1016/j.surfcoat.2004.10.024.
[12] S. Zhang, Z. Xianting, W. Yongsheng, C. Kui, W. Wenjian, Adhesion Strength of Sol-Gel Derived Fluoridated Hydroxyapatite Coatings, Surface and Coatings Technology, Vol. 200, No. 22-23, 2006, pp. 6350-6354, https://doi.org/10.1016/j.surfcoat.2005.11.033.
[13] L. H. Long, L. D. Chen, S. Q. Bai, J. Chang, K. L. Lin, Preparation of Dense β-CaSiO3 Ceramic with High Mechanical Strength and HAp Formation Ability in Simulated Body Fluid, Journal of The European Ceramic Society, Vol. 26, No. 9, 2006, pp. 1701-1706, https://doi.org/10.1016/j.jeurceramsoc.2005.03.247.
[14] F. Liu, F. Wang, T. Shimizu, K. Igarashi, L. Zhao, Formation of Hydroxyapatite on Ti-6Al-4V Alloy by Microarc oxidation and Hydrothermal Treatment, Surface and Coatings Technology, Vol. 199, No. 2-3, 2005, pp. 220-224, https://doi.org/10.1016/j.surfcoat.2004.10.146.
[15] B. C. Wang, E. Chang, T. M. Lee, C. Y. Yang, Changes in Phases and Crystallinity of Plasma‐Sprayed Hydroxyapatite Coatings Under Heat Treatment: A Quantitative Study, J. Biomed. Mater. Res., Vol. 29, No. 12, 1995, pp. 1483-1492, https://doi.org/10.1002/jbm.820291204.
[16] I. M. O. Kangasniemi, C. C. P. M. Verheyen, E. A. Van Der Velde, K. De Groot, In vivo Tensile Testing of Fluorapatite and Hydroxylapatite Plasma‐Sprayed Coatings, J. Biomed. Mater. Res., Vol. 28, No. 5, 1994,
pp. 563-572, https://doi.org/10.1002/jbm.820280506.
[17] F. Liu, F. Wang, T. Shimizu, K. Igarashi, L. Zhao, Hydroxyapatite Formation on Oxide Films Containing Ca and P by Hydrothermal Treatment, Ceramics International, Vol. 32, No. 5, 2006, pp. 527-531, https://doi.org/10.1016/j.ceramint.2005.04.006.
[18] G. Li et al., Review of Micro-Arc Oxidation of Titanium Alloys: Mechanism, Properties and Applications, Journal of Alloys and Compounds, Vol. 948, 2023, pp. 169773, https://doi.org/10.1016/j.jallcom.2023.169773.
[19] A. L. Yerokhin, X. Nie, A. Leyland, A. Matthews, Characterisation of Oxide Films Produced by Plasma Electrolytic Oxidation of A Ti-6Al-4V Alloy, Surface and Coatings Technology, Vol. 130, No. 2-3, 2000, pp. 195-206, https://doi.org/10.1016/S0257-8972(00)00719-2.
[20] S. Durdu, Ö. F. Deniz, I. Kutbay, M. Usta, Characterization and Formation of Hydroxyapatite on Ti6Al4V Coated by Plasma Electrolytic Oxidation, Journal of Alloys and Compounds, Vol. 551, 2013, pp. 422-429, https://doi.org/10.1016/j.jallcom.2012.11.024.
[21] A. F. Alhosseini, R. Chaharmahali, M. K. Keshavarz, K. Babaei, Surface Characterization of Bioceramic Coatings on Zr and Its Alloys Using Plasma Electrolytic Oxidation (PEO): A Review, Surfaces and Interfaces, Vol. 25, 2021, pp. 101283, https://doi.org/10.1016/j.surfin.2021.101283.
[22] B. M. Kasprolewicz, A. Ossowska, Recent Advances in Electrochemically Surface Treated Titanium and Its Alloys for Biomedical Applications: A Review of Anodic and Plasma Electrolytic Oxidation Methods, Materials Today Communications, Vol. 34, 2023, pp. 105425, https://doi.org/10.1016/j.mtcomm.2023.105425.
[23] F. Hafili, R. Chaharmahali, K. Babaei, A. F. Alhosseini, Duty Cycle Influence on the Corrosion Behavior of Coatings Created by Plasma Electrolytic Oxidation on AZ31B Magnesium Alloy in Simulated Body Fluid, Corrosion Communications, Vol. 3, 2021, pp. 62-70, https://doi.org/10.1016/j.corcom.2021.09.005.
[24] E. Mohammadipour, M. Ghorbani, Characterization, Mechanical, Corrosion, and in vitro Apatite-Formation Ability Properties of Hydroxyapatite-Reduced Graphene Oxide Coatings on Ti6Al4V Alloy by Plasma Electrolytic Oxidation, Journal of Materials Research and Technology, Vol. 33, 2024, pp. 441-457, https://doi.org/10.1016/j.jmrt.2024.09.041.
[25] S. Durdu, K. Korkmaz, S. L. Aktuğ, A. Çakır, Characterization and Bioactivity of Hydroxyapatite-Based Coatings Formed on Steel by Electro-Spark Deposition and Micro-Arc Oxidation, Surface and Coatings Technology,
Vol. 326, 2017, pp. 111-120, https://doi.org/10.1016/j.surfcoat.2017.07.039.
[26] L. Li, H. Kim, S. Lee, Y. Kong, H. Kim, Biocompatibility of Titanium Implants Modified by Microarc Oxidation and Hydroxyapatite Coating, J Biomedical Materials Res, Vol. 73A, No. 1, 2005, pp. 48-54, https://doi.org/10.1002/jbm.a.30244.
[27] V. S. Rudnev, V. P. Morozova, I. V. Lukiyanchuk, M. V. Adigamova, Calcium-Containing Biocompatible Oxide-Phosphate Coatings on Titanium, Russ J Appl Chem, Vol. 83, No. 4, 2010, pp. 671-679, https://doi.org/10.1134/S107042721004018X.
[28] W. H. Song, Y. K. Jun, Y. Han, S. H. Hong, Biomimetic Apatite Coatings on Micro-Arc Oxidized Titania, Biomaterials, Vol. 25, No. 17, 2004, pp. 3341-3349, https://doi.org/10.1016/j.biomaterials.2003.09.103.
[29] H. Cimenoglu, M. Gunyuz, G. T. Kose, M. Baydogan, F. Uğurlu, C. Sener, Micro-Arc Oxidation of Ti6Al4V and Ti6Al7Nb Alloys for Biomedical Applications, Materials Characterization, Vol. 62, No. 3, 2011, pp. 304-311, https://doi.org/10.1016/j.matchar.2011.01.002.
[30] D. Wei, Y. Zhou, D. Jia, Y. Wang, Structure of Calcium Titanate/Titania Bioceramic Composite Coatings on Titanium Alloy and Apatite Deposition on Their Surfaces in A Simulated Body Fluid, Surface and Coatings Technology, Vol. 201, No. 21, 2007, pp. 8715-8722, https://doi.org/10.1016/j.surfcoat.2007.04.124.
[31] A. Yerokhin, E. V. Parfenov, A. Matthews, In situ Impedance Spectroscopy of The Plasma Electrolytic Oxidation Process for Deposition of Ca- and P-Containing Coatings on Ti, Surface and Coatings Technology, Vol. 301, 2016, pp. 54-62, https://doi.org/10.1016/j.surfcoat.2016.02.035.
[32] J. Sun, Y. Han, X. Huang, Hydroxyapatite Coatings Prepared by Micro-Arc Oxidation in Ca- and P-Containing Electrolyte, Surface and Coatings Technology, Vol. 201, No. 9-11, 2007, pp. 5655-5658, https://doi.org/10.1016/j.surfcoat.2006.07.052.
[33] T. T. An et al., Corrosion Resistance of Zinc-Doped Hydroxyapatite Coating on Titanium Substrate Using Plasma Electrolytic Oxidation for Biomedical Applications, J. of Materi Eng and Perform, Vol. 34, No. 8, 2025,
pp. 6743-6754, https://doi.org/10.1007/s11665-024-09636-8.
[34] V. Karageorgiou, D. Kaplan, Porosity of 3D Biomaterial Scaffolds and Osteogenesis, Biomaterials, Vol. 26,
No. 27, 2005, pp. 5474-5491, https://doi.org/10.1016/j.biomaterials.2005.02.002.
[35] C. H. Huang, M. Yoshimura, Direct Ceramic Coating of Calcium Phosphate Doped with Strontium Via Reactive Growing Integration Layer Method on α-Ti Alloy, Sci Rep, Vol. 10, No. 1, 2020, pp. 10602, https://doi.org/10.1038/s41598-020-67332-8.
[36] S. Arun, S. G. Ahn, H. C. Choe, Surface Characteristics of HA-Coated and PEO-Treated Ti-6Al-4V Alloy in Solution Containing Ag Nanoparticles, Surfaces and Interfaces, Vol. 39, 2023, pp. 102932, https://doi.org/10.1016/j.surfin.2023.102932.
[37] E. Lokeshkumar et al., Development of TiO2-HA Coatings by PEO on Titanium Scaffolds Fabricated by Direct Ink Writing, Trans Indian Inst Met, Vol. 76, No. 2, 2023, pp. 511-518, https://doi.org/10.1007/s12666-022-02714-2.
[38] M. Montazeri, C. Dehghanian, M. Shokouhfar, A. Baradaran, 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, Applied Surface Science, Vol. 257, No. 16, 2011, pp. 7268-7275, https://doi.org/10.1016/j.apsusc.2011.03.103.
[39] L. Zhou, G. H. Lü, F. F. Mao, S. Z. Yang, Preparation of Biomedical Ag Incorporated Hydroxyapatite/Titania Coatings on Ti6Al4V Alloy by Plasma Electrolytic Oxidation, Chinese Phys. B, Vol. 23, No. 3, 2014, pp. 035205, https://doi.org/10.1088/1674-1056/23/3/035205.