Chemical incorporation of SiO2 into TiO2 layer by green plasma enhancer and quencher agents for synchronized improvements in the protective and bioactive properties

Abstract

This study explores the dynamic interaction between environmentally sustainable plasma enhancer and quencher agents during the incorporation of SiO2 into a TiO2 layer, with the primary objective of simultaneously augmenting protective and bioactive attributes. This enhancement is realized through the synergistic utilization of Tetraethyl orthosilicate (TE) and Stevia (ST) within a plasma-assisted oxidation process. To achieve this goal, Ti–6Al–4V alloy underwent oxidation in an electrolyte solution containing acetate-glycerophosphate, with the addition of TE and ST separately and in combination. TE, as a silicon oxide (SiO2) precursor, facilitates the creation of a calcium-rich, rough, porous layer by undergoing hydrolysis to generate silanol groups (Si–OH), which subsequently condense into silicon-oxygen-silicon (Si–O–Si) bonds, resulting in SiO2 formation. In contrast, ST acts as a plasma quencher, absorbing highly reactive plasma species during the oxidation process, reducing energy levels, and diminishing sparking intensity. The combination of TE and ST results in moderate sparking, balancing Stevia's quenching effect and TE's sparking influence. As a result, this coating exhibits enhanced corrosion resistance and bioactivity compared to using either ST or TE alone. The study highlights the potential of this synergistic approach for advanced TiO2-based coatings.