Morphology, abrasion and corrosion resistance study of the plasma electrolytic oxidation films formed on pure titanium by adding silane in the electrolyte

Abstract

Surface modification of pure Ti is performed with the addition of aminopropyl trimethoxy-silane (APS) in the anodic electrolyte to obtain plasma electrolytic oxidation (PEO) ceramic films at a median voltage of 200 V. The addition of silane in Na2SiO3 solution does not change the phase compositions of the PEO films while promoting the faster growth of both rutile and anatase, meanwhile smoother and thicker ceramic films with more regular pores on the outer layers are obtained as reflected by the X-ray diffraction spectra (XRD) and scanning electron microscopy (SEM) results, respectively. The wear resistance in dry friction condition of the PEO films with silane addition is improved as seen from their friction coefficient and abrasive track image; the increase in corrosion potential (Ecorr) and decrease in corrosion current density (Icorr) suggest the improvement of their resisting ability to corrosive media, attributing to the formation of compacter inner and outer layer films as supported by the electrochemical impedance spectroscopy. The results of attenuated total reflection-Fourier transform infrared spectra (ATR-FTIR) and X-ray photoelectron spectra (XPS) reveal that APS exists on the surfaces and among the defects of ceramic films by adsorption, self-condensation and/or chemical linkage (Ti–O–Si) as various states, therefore their existence and filling effects result in the improvement in their abrasive and corrosive resistances.