Abstract

GONZALEZ, ANDRÉS et al. MICROSTRUCTURE AND PHASES ANALYSES OF ZIRCONIA-ALUMINA (ZrO₂-Al₂O₃) COATINGS PRODUCED BY THERMAL SPRAY. Dyna rev.fac.nac.minas [online]. 2010, vol.77, n.162, pp.151-160. ISSN 0012-7353.

Those coatings used as thermal barriers are designed to protect materials exposed to high temperatures, typically consist of a ceramic top layer, which normally is made of zirconia (ZrO₂). The study of the microstructure in coatings produced by thermal spray is always a necessary and intermediate step in processing and achieving excellent properties for a particular application. For this reason, the objective of the work was to analyze the microstructure and the phases found in zirconia-alumina coatings produced by flame spray. The results show that for short time in the flame, rapid solidification and interdiffusion zirconia - alumina of the ceramic powder during the coating formation induces two types of lamellas in its top layer: one is constituted by lamellas with different gray shades caused by small variations in the composition of tetragonal zirconia and amorphous alumina in solid solution, and the other structure consists for lamellas with a granular morphology constituted by monoclinic zirconia precipitated in an alumina matrix.

Keywords : Flame spray; zirconia-alumina coatings; microstructure; phases; barrier thermal coatings.

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