Mechanical characterization of alumina coatings on C35 steel

摘要

C355 steel substrates were alumina-coated via thermal plasma spraying. Before coating, the steel surface was either sandblasted, or pre-oxidized in CO2. The pre-oxidized samples exhibited coatings adhesions of 82 +/- 7 MPa, and only 45 +/- 4 MPa for the sandblasted ones. This good result was attributed to the "crystallographic bonding", which is characterized by the structural continuity of the chain: steel/alpha-Fe/wilstite/magnetite/gamma-Al2O3. The adhesion measurements were obtained utilizing the new technique of the "silver print test" that consists in the painting of a part of the samples surface before coating. The rupture of the coatings occurred at the surface of the substrate, or inside the wilstite layer. (C) 2015 Elsevier B.V. All rights reserved.