Pretreatment effect of the pure titanium surface on hybrid coating adhesion based on tetraethoxysilane and methyltriethoxysilane

Hybrid coatings based on silicon alkoxide precursors are one of the options for coating metal surface biomaterials such as pure titanium (Ti). However, the nature and the metal surface preparation, before the coating application, are of fundamental importance for perfecting the coating/surface adhesion. In this study, three different pretreatments were used for the Ti surface: Kroll, Piranha and NaOH. After the pretreatment, the coating was applied by the dip-coating process, using the sol–gel method from the silicon alkoxide precursors, tetraethoxysilane and methyltriethoxysilane. The results of thermogravimetric analysis showed that the tested coatings had excellent thermal stability. The pretreatment with NaOH solution increased the surface roughness of the Ti, thus modifying its surface energy and increasing its wettability. Field emission scanning electron microscopy showed a homogeneous coating with good adhesion of the hybrid coating to the Ti surface, and higher layer thickness on the surface treated with NaOH. In addition, its electrochemical performance was better than the surfaces pretreated with acids.