Oxidation behaviour at 1123 K of AISI 304-Ni/Al-Al2O3/TiO2 multilayer system deposited by flame spray

• Autores: Kudama Habib Ameen, J. J. Saura, M. S. Damra, Iván Cervera González, C. Ferrer
• Localización: Revista de metalurgia, ISSN 0034-8570, Vol. 47, Nº 2, 2011, págs. 126-137
• Idioma: español
• Títulos paralelos:
  • Oxidación a 1123 K de sistemas multicapa AISI 304-Ni/Al-Al2O3/TiO2 depositados por llama
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• Resumen

  • The oxidation behaviour of alumina/titania (97/3, 87/13 and 60/40) ceramic coatings using a Ni-Al coupling layer was studied in a thermobalance. Both layers were deposited on an AISI 304 stainless steel base metal by the flame spray technique. The coated steel was heated from room temperature to 1,123 K at 40 K min�1, oxidized in air for 50 h, and then cooled to room temperature at 40 K min�1. The mass gain was mainly attributed to the oxidation of Ni-Al coupling layer. Kinetic laws, DW·S�1 (mg.mm�2) vs. time (hours) were close to a parabolic plot for each sample. Surface composition of ceramic top layer and the cross section of multilayer system were analysed using a wide range of experimental techniques including Scanning Electron Microscopy (SEM), equipped with a link energy dispersive X-Ray spectroscopy (EDX) and X-Ray diffraction (XRD) before and after the oxidation process.

    Coatings 97/3 and 87/13 presented a stable structure after flame spray deposition and they did not evolve with the oxidation process, while most of the 60/40 coating changed to a metastable structure after deposition and to a more stable structure after oxidation with high micro-cracks content. SEM and EDX microanalysis of the cross-sections showed that significant oxidation and a weak intergranular precipitation had been produced in the coupling layer and on the stainless steel base metal, respectively.