OATAO - Open Archive Toulouse Archive Ouverte Open Access Week

Morphology and structure of YSZ powders: Comparison between xerogel and aerogel

Fenech, Justine and Viazzi, Céline and Bonino, Jean-Pierre and Ansart, Florence and Barnabé, Antoine Morphology and structure of YSZ powders: Comparison between xerogel and aerogel. (2009) Ceramics International, vol. 35 (n° 8). 3427-3433 . ISSN 0272-8842

[img] (Document in English)

PDF (Author's version) - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
846kB

Official URL: http://dx.doi.org/10.1016/j.ceramint.2009.06.014

Abstract

Yttria-stabilized zirconia (YSZ) fine powders were prepared via sol–gel route in order to shape thermal barrier coatings (TBCs) from these powders. The main objective is to develop new undirectional coatings to allow best thermo-mechanical accommodations compared to conventional processes. To reach this aim, powders have to be able first to be highly dispersed into a sol (non-agglomeration, high specific surface area, etc.) and second to crystallize in the required metastable phase t0. Two routes have been used to dry gels: the conventional way which consists of simple evaporation of the solvent is compared to drying in supercritical conditions. Both YSZ powders after calcination at 950 8C of xerogel (Ex-xero-YSZ powder) and aerogel (Ex-aero-YSZ powder) crystallize in the tetragonal form. N2 adsorption/desorption analysis of the Ex-xero-YSZ powder indicates an Sw of 2.8 m2/g. For the Ex-aero-YSZ powder, the Sw (26 m2/g) is much higher than of Ex-xero-YSZ, leading to a better sintering capability. This high Sw is correlated to the small crystallite size (26 nm) and the alveolar morphology of Ex-aero-YSZ powders compared to Exxero-powder (49 nm). By reducing particles size and increasing the Sw of the powders, supercritical drying appears as a promising way to prepare stable slurries or loaded sols from fine YSZ particles for TBC applications. Indeed, after preparing nanometric powders, they are dispersed into a sol before shaping on superalloys substrates. After thermal treatment at 950 8C for 2 h which corresponds to the working temperature of TBC, the final aim will be to prepare ceramic YSZ coatings.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at Ceramics International website : http://www.sciencedirect.com/science/journal/02728842
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Other partners > Saint-Gobain (FRANCE)
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
Laboratory name:
Statistics:download
Deposited By: Nihad Lahdifi
Deposited On:21 Jul 2010 13:59

Repository Staff Only: item control page