Interdiffusion phenomena of zirconia-nitride layers in coated AISI 310 steel

B. J. GÓMEZ,; L. NACHEZ,; R. CARUSO,; A. DIAZ-PARRALEJOA. DÍAZ-PARRALEJO; J. FEUGEAS; O. DE SANCTIS

SURFACE AND COATINGS TECHNOLOGY

Elsevier

Lugar: Londres; Año: 2009

0257-8972

Duplex coatings on stainless steel AISI 310 were prepared by means of a doubleprocess consisting of a nitrogen/hydrogen plasma ion-nitriding treatment and amultilayer ZrO2-3 mole % Y2O3 coating grown by chemical solution deposition. Inthis paper we investigate the interdiffusion phenomena between the elements andthe deposited phases. The zirconia coating process the nitrided steel initiated strongdiffusion events. An outer layer consisting of oxides of iron and zirconium and aninner one of hematite are formed in the interface. A subsequent nitriding on the zirconiacoated nitraded steel shows interesting results concerning the effect of nitrogenin the reduction of hematite. A more restricted interdiffusion is obtained when theorder of performing the nitriding process and zirconia coating is reversed. The zirconiacoating retains nitrogen atoms, which are incorporated into the structure ofthe zirconia forming a substitutional solid solution, which prevents the penetrationof nitrogen into the substrate metal. Hydrogen, one of the components of the gasmixture, diffuses easily throughout the coating and acts as a reducing agent. Thelayer of zirconia works as a sieve, retaining nitrogen and allowing the passage ofhydrogen.