Characterization of cerium-based conversion coatings for corrosion protection of AISI-1010 commercial carbon steel

The role of hydrogen peroxide in the formation of cerium conversion coatings by immersing AISI 1010 commercial carbon steel substrates into solutions containing various concentrations of CeCl₃ (0.1, 1, and 10 g L⁻¹) has been investigated as an alternative method for their protection against corrosion. The deposits prepared from the solutions with H₂O₂ consist of yellow thin and non-uniform coatings with agglomerates of small CeO₂ and Ce₂O₃ crystallites whose sizes increased over the metallic surface as the cerium concentration was increased. Cerium pre-treatments in the presence of H₂O₂ displayed layers that were rougher than those synthesized without H₂O₂. A comparison with the chromate conversion pre-treatment is also simultaneously carried out with the discussion of the possible reactions involved in the different stages of process. The coating obtained from the solution containing 0.1 g in 1,000 mL produced better corrosion resistance on the substrate than that observed for its counterparts due to the fact that the surface was more uniformly covered by the conversion coating. The addition of H₂O₂ to the cerate baths improves visible roughness, corrosion resistance of the conversion coatings and bond strength because hydrogen peroxide acts as an oxygen source during the formation of the coatings.