Polytitanosiloxane coatings derived from Ti(OC2H5)4-modified organosilane precursors

Abstract

Amorphous polytitanosiloxane (PTS) was formed by hydrolysis-polycondensation and hydrolysis-polycondensation-pyrolysis reactiomechanisms of precursor sol solutions consisting of monomeric organosilanes, Ti(OC2H5)4, methanol, water and hydrochloric acid, over the temperature range 100-500 °C. These reaction processes which are responsible for the assemblage of PTS networks were found to depend mainly on the species of organosilane used. The PTS was applied as a coating on aluminum substrates and the factors which play an important role in providing corrosion protection were investigated. Three major findings are as follows: (1) the addition of HCl, which was used as a hydrolysis accelerator for the organosilanes and Ti(OC2H5)4, acts to produce a clear sol solution, thereby aiding in the formation of smooth and uniform coating layers; (2) the organosilane to Ti(OC2H5)4 ratios are critical for the fabrication of PTS films; and (3) moderate densification of the Si-O-Ti bond in PTS networks is needed to produce a good film. © 1990.