Resistance of nanostructured titanium dioxide coatings to erosion corrosion

Abstract

Investigations were undertaken to determine the erosion corrosion resistance of nanostructured titanium dioxide coatings in 5 vol.-%–3·5 wt-% NaCl slurry at velocities ranging from 1 to 4 m s^–1 in a recirculating loop. Two types of nanopowders, spray dried and densified (AE 9342) and chemically precipitated and spray dried (AE 9303) were used. The results were compared with a conventional TiO₂ coated samples (SM 102). Specimen AE 9342 showed a higher resistance compared to AE 9303. No localised corrosion on the above specimen was observed. The erosion corrosion was caused by etching of intersplat boundaries. The erosion corrosion is dependent on surface topography. A homogeneous distribution of nanoagglomerates of unmelted, partially melted nanoparticles embedded in coatings, a large area of melted zone and porosity less than 1% enhances the erosion corrosion resistance of nanostructured titanium dioxide coatings.