Plasma-sprayed self-sealing ceramic coatings: Materials chemistry and high temperature protective properties

The principal theoretical and experimental data relating to the structure and the protective action of self-sealing ceramic coatings (SSCCs) used to prevent non-aqueous corrosion phenomena (T ? 900 K) on metallic surfaces in chemically aggressive environments (oxidation, carburization, nitridation, sulphidation, attack by molten metals etc.) are reviewed. The plasma spray process used to deposit SSCCs is described and some of their properties are summarized. The results obtained in an investigation of the protective efficiency of SSCCs on Incoloy 825 and titanium substrates, which are particularly susceptible to metal dusting and oxidation-nitridation corrosion phenomena, are reported. It is hoped that the work described in this paper will stimulate new approaches to the development and characterization of these novel protective coatings as it is necessary to optimize the prevention of non-aqueous corrosion in many applications.