Bioactivity and Electrochemical Corrosion Properties of Plasma Sprayed Hydroxyapatite – Lanthanum Oxide Composite Coatings in SBF Solution

Bioactivity and electrochemical corrosion properties of plasma sprayed hydroxyapatite – Lanthanum oxide composite coatings in SBF solution

Akira Kobayashi ^(1*),S. Yugeswaran ⁽¹⁾ and B. Subramanian ^{(1, 2)}

⁽¹⁾Joining & Welding Research Institute, Osaka University, Osaka 567-0047, Japan

⁽²⁾CSIR- Central Electrochemical Research Institute, Karaikudi-630 006, India

Hydroxyapatite (HAp) can be coated onto metal implants as a ceramic biocompatible coating to bridge the growth between implants and human tissue. Bioceramic composite, formed by a bioactive ceramic such as HAp and rare earth oxide like lanthanum oxide (La₂O₃) were deposited on titanium substrates via gas tunnel type plasma spray technique under the optimized spraying conditions at 15 kW power level and 200 lpm of Ar flow rate. These coatings were characterized using XRD, Field Emission Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy. Increase in hardness was observed for the composite coatings.The in vitro bioactivity of all coated samples was tested in conventional Simulated Body Fluid (SBF) solution. The potentiodynamic polarization and impedance measurements showed that these HAp-La₂O₃ composite coatings on steel exhibited superior corrosion resistance compared to the single layer of hydroxyl apatite and the bare titanium substrate in SBF solution. Following the soaking in SBF solution, the onset of biological apatite formation on the surface of the samples was detected. Bactericidal effect against bacteria indicated high antimicrobial resistant activity of these samples. Also,the composite coatings showed good cytocompatibility with cell lines used.

Keywords: Reactive spraying, Gas tunnel type plasma jet, Simulated body

fluid, Cytocompatability