Anti-Corrosion Coatings Based on Nb₂O₅ - a Comparison Between two Coatings Technology: Thermal Spray Coating and Epoxy Paint

Abstract

Niobium pentoxide (Nb₂O₅) has gained prominence as an anti-corrosive pigment. The performance of anti-corrosive coatings based on Nb₂O₅ was tested in an environment with an acid atmosphere and at high temperatures. For comparison, SAE 1020 carbon steel samples were coated with two anti-corrosive coatings based on Nb₂O₅: applied by thermal spray and epoxy paint. The samples were partially immersed in the laboratory for 720 h and 1440 h in a 40% (v/v) H₂SO₄ at 25°C, 60°C, and 80°C. An in-situ evaluation was carried out of chemical industry installations over 4383 h in microclimates with the presence of corrosive agents at temperatures up to 70°C. The results obtained showed that the Nb₂O₅ coatings applied by thermal spray offer better anti-corrosive performance under immersive conditions. In contrast, under conditions submitted to steam, both the Nb₂O₅ coatings applied by thermal spraying and epoxy-Nb₂O₅ paint show excellent anti-corrosive behavior.

Keywords:
Niobium pentoxide; thermal spray; epoxy paint; anti-corrosive coating; high temperatures; sulfuric acid