Electrochemical and biological characterization HA/Al 2 O 3 -YSZ nano-composite coatings using electrophoretic process Nayereh Askari, 1 Mardali Yousefpour , 1 Masoud Rajabi 2 1 Faculty of Materials and metallurgical Engineering, Semnan University, Semnan, Iran 2 Materials Engineering Department, Imam Khomeini International University (IKIU), Qazvin, Iran Received 3 July 2017; revised 14 February 2018; accepted 27 February 2018 Published online 00 Month 2018 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/jbm.a.36392 Abstract: In this research work, hydroxyapatite/alumina/YSZ bio nanocomposite coatings on titanium substrate were created by electrophoretic deposition (EPD) and reaction bonding process. By using the EPD process, uniform green form coatings containing HA, yttria-stabilized zirconia (YSZ), and aluminum particles were produced on titanium. After oxidation of aluminum at 6608C and sintering at 8508C, a dense and adherent HA/Al 2 O 3 /YSZ coating was produced. Scanning electron microscopy, X-ray diffractometric and mechanical tests were employed to investigate the morphologies, compositions, hardness, toughness and bond- ing strength of the coatings. The corrosion studies and cell culturing experiment were carried out and the results show that the HA/YSZ/Al 2 O 3 coatings are more bioactive and more resistance to corrosion than HA coatings. V C 2018 Wiley Periodi- cals, Inc. J Biomed Mater Res Part A: 00A:000–000, 2018. Key Words: Electrophoretic deposition, electrochemical, cell culture, YSZ, suspensions, hydroxyapatite How to cite this article: Askari N, Yousefpour M, Rajabi M. 2018. Electrochemical and biological characterization HA/Al 2 O 3 -YSZ nano-composite coatings using electrophoretic process. J Biomed Mater Res Part A 2015:00A:000–000. INTRODUCTION To reconstruct bioactive ceramics are generally utilized as coatings on metals and reconstruct skeletal muscle tissue. Among different Caps, HA [Ca 10 (PO 4 ) 6 (OH) 2 ] is widely used due to its osseous nature and suitability to strong bonding with host bone tissues. 1–3 Different coating methods have been utilized such as plasma spraying, dip coating, hot iso- static pressing, ion beam-assisted deposition, pulsed laser deposition, sol–gel technique and electrophoretic deposition (EPD). 4–13 Among of these methods, EPD has several bene- fits such as better control thickness and morphology of the coating, components with complex shapes are deposited uniform, higher deposition rate than other coating technics and cheap equipment required. 14–16 . However, deposited pure HA by the EPD method has defects that limit the appli- cations of this method. The main limitation is low sintering temperature that applied for this technique while full densi- fication coatings required high sintering temperature. 17 High temperature can cause destruction of the metal sub- strate and disintegration of HA coating. 18 Disintegration of the HA coating is unfavorable because it produces tri cal- cium phosphate phase that is biodegradable in vivo. Sinter- ing temperatures ideally should be below 10008C. 9,19 Furthermore, HA coatings are produced by the EPD which has little adhesive strength and due to large differences in physical and thermal properties between HA and Ti. 20,21 Coefficient of thermal expansion of HA is much more than that of titanium substrate. Thus, when sintered pieces make cold large thermal contraction mismatch would arise and lead to the formation of cracks. 22 To overcome this problem, HA-alumina composite coatings were utilized on Ti. 22,23 Reaction bonding of Al 2 O 3 was developed to produce near net-shape ceramics to overcome problems caused by the shrinkage during sintering. 24,25 Zirconia (ZrO 2 ) is a bio ceramic and is bio inert, which shows superior mechanical behavior and biocompatibility. Therefore, adding ZrO 2 into HAP improves the interfacial bonding strength of the Ti sub- strate and coating. 26–28 Zirconia is superior to alumina in terms of mechanical properties and bio compatibility. 29 Con- versions of zirconia from tetragonal to monoclinic phase induces the increase in its strength and fracture tough- ness. 30 In this research, hydroxyapatite/alumina/YSZ bio nanocomposite coating to improve the mechanical proper- ties and biocompatibility on titanium substrate was carried out by electrophoretic deposition and reaction bonding process. EXPERIMENTAL Materials For this study, HA nano powder was synthesized by chemi- cal precipitation method. 31 The synthesized nanoparticles were characterized by X-ray diffractometric (XRD) and scan- ning electron microscope (SEM) analysis (Fig. 1). 31 Al nano powder prepared with milling by satellite mill (Tajhiz Ceram Correspondence to: M. Yousefpour; e-mail: myousefpor@semnan.ac.ir Contract grant sponsor: Semnan University, IRAN Nanotechnology Initiative Council V C 2018 WILEY PERIODICALS, INC. 1