Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7921385 | Materials Chemistry and Physics | 2018 | 20 Pages |
Abstract
8%Yttria-Stabilized Zirconia (8YSZ) and Alumina (Al2O3) coatings were deposited on silicon (100) and stainless steel AISI 304 substrates as single layers and [8YSZ/Al2O3]n multilayer, via a multi-target r.f. (13.56â¯MHz) magnetron sputtering system, from 8mol% Y2O3-ZrO2 and aluminum (99.95%) targets under an Ar/O2 atmosphere at 300â¯Â°C. The effect of the Al2O3/8YSZ bilayers number (nâ¯=â¯1, 10, 30, 50 and 70) on the thermal cyclic response was studied. For this test, the coatings were heated and cooled in air flux during 12â¯h by cycles of 10â¯min at 1000â¯Â°C. After this process, the oxide scale at the surface of the coatings was studied by digital image analysis, X-ray diffraction, Scanning Electron Microscopy, and Energy Dispersive X-Ray Spectroscopy. It was found a phase transformation from tetragonal to monoclinic ZrO2, deriving in a volume expansion, which caused the coatings cracks formation. Also, a reduction of superficial degradation from 80.6% (for nâ¯=â¯1 bilayer) to 0.3% (for nâ¯=â¯70 bilayers) was observed. Moreover, it was evidenced that the iron oxides formed at the uncoated substrates, decreased by the increment of bilayers number. The intensity of high-temperature oxidation of [8YSZ/Al2O3]n coatings decreased with increasing the number of bilayers, which shows that O2 ions diffusion, through defects or vacancies in the lattice structure, has been limited.
Related Topics
Physical Sciences and Engineering
Materials Science
Electronic, Optical and Magnetic Materials
Authors
A. Escarraga, A. Toro, Y. Aguilar, J.C. Caicedo, G. Zambrano,