Papers by Author: Alicia Salazar

Abstract: It has been generally accepted that a nanostructured material exhibits better properties than conventional ones. Nanostructured ceramic coatings fabricated by plasma spray have been developed for a wide variety of applications where a surface protection is required. Alumina - titania coatings are usually used as protective layers in many industrial applications requiring a high wear resistance during dry sliding contact. In this work, nanostructured and conventional Al2O3 – 13% TiO2 coatings deposited via atmospheric plasma spray were compared. Mechanical characterization was carried out using depth sensing indentation to determine hardness and Young´s modulus of the coatings. Size independent properties can be determined after considering geometrical factors such as tip rounding and indenter deformation. Nanostructured coatings show slightly better mechanical properties than conventional coatings.

Abstract: This paper analyses the degradation of a ceramic top coating 70%ZrO2 – 30%CaO deposited onto a stainless steel AISI 304 by thermal spray, using Ni-6%Al-5%Mo as overlay coating. These thermal barrier coatings were heat treated for 48, 120 and 288 h at 800 °C to evaluate the degradation of these materials by isothermal oxidation. The microstructure evolution during oxidation was analysed by environmental scanning electron microscopy, transmission electron microscopy and X ray microanalysis. A thermally grown oxide layer was observed between the overlay coating and the ceramic top coating after oxidation. This layer was formed by a mixed Al, Ni and Mo oxides.