Evaluation and Optimization of Sol-Gel Coatings for Oil and Gas Applications

Corrosion is a major oilfield flow assurance problem with coatings being commonly used by industry as a barrier to electrochemically active species. In recent years, studies on sol-gel materials have drawn an increased interest, gaining more recognition as an alternative to conventional coatings due to many promising properties. In this project different sol-gel coatings were developed and studied in order to optimize their physicochemical properties with particular attention to their corrosion resistance. To evaluate the protective properties metal coupons (stainless steel and carbon steel) coated with inorganic/hybrid, organic and hybrid/composite coatings were subjected to a mildly corrosive environment at first. Then the focus of the second batch was on non-functionalised inorganic/hybrid coatings and other inorganic/hybrid coatings with the same sol-gel structure and composition but in addition doped with a titanium precursor. The doped coatings were prepared by hydrolysis of a titanium butoxide through the sol-gel process. The purpose of this batch was to evaluate the advantages of titanium butoxide and the influence of its concentration on its properties. In the final batch the focus was on the link between parameters such as curing process and solvent used during the sol-gel mechanism to the corrosion behaviour. The purpose was to investigate the effect of the solvent as well as the curing process on the anti-corrosion properties of the different coatings. Several methods, chemical and mechanical, were used throughout the project to identify and analyze the results obtained and improved the coatings. The EIS data could be linked to the corrosion progress while being compared to the evolution of spectra from FTIR data. The impedance spectroscopy also gave information on the water intake. The substrate proved to have an influence on the adhesion of the coating as opposition to the amount of precursor added. The doping with a titanium precursor led to coatings with improved anti-corrosion properties but only within a certain percentage range (between 0% and 6% but less than 10%). There seem to be a limit to the amount of titanium allowing the anti-corrosive properties to protect the substrate.