Corrosion of flame-assisted CVD silica-coated steel sheet

Thin silica coatings (15–60 nm) were deposited as barrier coatings on carbon steel by a flame assisted chemical vapor deposition (CVD) process. The silica-coated steel showed good corrosion properties in cyclic humidity testing (bare) and salt spray testing (painted). Electrochemical analysis was performed to investigate the corrosion mechanism. The study suggests that the corrosion starts at pin-holes and proceeds then further under galvanic coupling with the surrounding regions. We find that the corrosion rate is reduced by a factor 10 or more with respect to uncoated steel, depending on the testing conditions and type of silica coating.

► Decrease of corrosion of steel sheet up to a factor of more than 30 by very thin silica-coating. ► Silica-coated steel that may be used as ready-to-paint product (no oil, no other pre-treatment). ► Detailed investigation of corrosion process.