Application of niobium enriched ormosils as thermally stable coatings for aerospace aluminium alloys

The aim of this experimental research is to study the ability of niobium rich sol–gel coatings to withstand thermal stress, while remaining impermeable to corrosive agents for the protection of aluminium aerospace alloys. The coating material is developed via polymeric sol–gel synthesis employing 3-(trimethoxysilyl)propylmethacrylate (MAPTMS) and niobium ethoxide precursors as silicon and niobium sources, respectively. The beneficial effect of niobium inclusion within the coating was characterised spectroscopically, calorimetrically and electrochemically. The thermal cycling effects of the coating were studied using microscopic and accelerated test methods. Electrochemical tests showed that corrosion current of the niobium enriched material was 2 orders lower in magnitude than the equivalent MAPTMS coating. The neutral salt spray test results of the thermally stressed samples prove that inclusion of niobium nanoparticles within the silane matrix considerably improves the corrosion resistance performance.