Fabrication of Ca and P containing niobium oxide ceramic coatings on niobium by PEO coupled EPD process

Abstract

Abstract Surface modification of niobium (Nb) to develop Ca and P containing niobium oxide (Nb2O5) ceramic coatings by plasma electrolytic oxidation (PEO) coupled with electrophoretic deposition (EPD) in a single step process is reported in the present study. Four coatings were obtained in silicate and phosphate electrolytes with and without the addition of hydroxyapatite (HA) nanoparticles. The phase composition, surface and cross-sectional morphology of the coatings were analysed. The corrosion resistance of the coated samples and niobium substrate was analysed using potentiodynamic polarisation (PDP) method in simulated body fluid (SBF) solution. The cell-viability and the live and dead cell morphology on the substrate and the coated samples were evaluated using L-929 cells. The adherence and growth of the L-929 cells were estimated by the direct contact assay. The surface modification by the PEO process enhanced the corrosion resistance of niobium in a fluid body environment. Among the coated samples, the PEO-EPD samples obtained in silicate electrolyte exhibited better corrosion resistance (6.02 × 10−7 mA/cm2), optimal surface properties, lower contact angle (47°), higher surface energy (50 mJ/m2), good adhesion strength (Lc = 18.1 N) and better cell viability.