Synthesis and electrophoretic deposition of TiO2-SiO2 composite nanoparticles on stainless steel substrate

Abstract

Titanium dioxide-silica composite nanoparticles were synthesized through a verified Stöber sol-gel method. The resultant nanoparticles, which consisted of titanium dioxide cores (35.54 ± 4.4 nm length rods) surrounded by ultrafine silica particles (3.22 ± 0.63 nm spheres) forming a thin shell, were electrophoretically deposited on an anodized stainless steel substrate to enhance its biological response in simulated body fluid (SBF). The presence of silica shell on TiO2 cores increased the surface roughness of the resultant composite particles and eliminated the cracks observed in the TiO2 coating due to the higher cohesion between the particles. The tape test results confirmed the higher adhesion of TiO2-SiO2 coating to the substrate. After 7 days of immersion in SBF solution, the silica shell resulted in a significantly higher Ca-P cluster formation on the TiO2-SiO2 coating compared to the TiO2 coating, which was almost free of Ca-P deposit. As the cracks were eliminated on the surface of the TiO2-SiO2 coating, the barrier performance of this coating was enhanced compared to the TiO2 coating in a phosphate-buffered saline solution.