Characterization of Polyorganosilazane-Derived Hybrid Coatings for the Corrosion Protection of Mild Steel in Chloride Solution

Abstract

Polysilazane (PSZ) have been used for many years as precursors for the development of ceramic materials. Recently, hydrocarbon-substituted polysilazane, which is called organopolysilazane (OPSZ), has been proposed as possible alternative to silanes for the corrosion protection of metals by the sol gel route. In this work, polymethyl(hydro)/polydimethylsilazane-derived coatings were deposited on low-carbon steel for corrosion protection purposes. The effect of the OPSZ precursor concentration (10–40 v/v %) in butyl-acetate on the final properties of the coatings was investigated. Coatings in the thickness range of 1 to 3.5 µm were obtained. The experimental results showed that the concentration of OPSZ in the solvent affects the structural properties as well as the dry film thickness of the hybrid layer. In particular, the network arrangement seems to be influenced by the dilution of the OPSZ precursors solution. The electrochemical characterization revealed that a minimum thickness of about 2 to 3 µm is needed to provide the mild steel substrate with enhanced corrosion protection properties compared to the bare substrate. Comparing the obtained results with literature data, it seems that OPSZs are a potential alternative to coatings derived from organisilicon precursors.