Yttria-stabilized zirconia gels

Thin films and coatings can be fabricated by vapor deposition [i.e., chemical vapor deposition (CVD) and electrochemical vapor deposition (EVD)], sputtering, sol-gel processing, and electrophoretic depositionElectrochemical vapor deposition, a thin-film technique, is used to form thin ( 40 pm) layers of dense yttria-stabilized zirconia in the seal-less tubular solid oxide fuel celP ". Thin layers of stabilized zirconia are required in this application to keep the internal resistance and the operating temperature of the electrochemical device as low as possible. 

Kusakabe et al.83 proposed selective CO oxidation membrane concept to facilitate SMR reaction. Yttria-stabilized zirconia (YSZ) membrane was deposited on the surface of a porous alumina support tube by sol-gel procedure. This again was impregnated with Pt and Rh aqueous solution to produce a Pt- or Rh-loaded YSZ membrane. With addition of 02 in the feed, oxidation of CO can bring CO concentration to the level appropriate for PEMFC (<30ppm). 

Viazzi C., Bonino J. P., Ansart F. 2006. Synthesis by sol-gel route and characterization of yttria stabilized zirconia coatings for thermal barrier applications. Surface Coatings Technology 201, 3889-3893. 

Chervin C N, Clapsaddle B J, Chiu H W, Gash A E, Satcher Jr J H, Kauziarich S M (2006) Role of cyclic ether and solvent in a non-alkoxide sol-gel synthesis of yttria-stabilized zirconia nanoparticles. Chem Mater 18 4865 874... 

Chervin CN, Clapsaddle BJ, Chiu HW, Gash AE, Sateher JH, Kauzlarich SM (2005) Aerogel synthesis of yttria-stabilized zirconia by a non-alkoxide sol-gel route. Chem Mater 17 3345 3351. 

In the sol-gel method, the nature of the complexant (fuel) is also important The sintered density and the activation energies of compacts obtained from microwave-assisted gel-combined combustion process for a series of fuels (citric acid, urea, and glycine) showed different results. This was well evidenced by determining the crystal structure, particle size, specific surface area, and morphology of nanocrystalline 8mol% yttria-stabilized zirconia (YSZ) powders [23]. 

Srdic V.V., Omoijan R.P. Electrical conductivity of sol-gel derived yttria-stabilized zirconia. Ceram. Int. 2001 27 859-863... 

Barnardo, T., Hoydalsvik, K., Winter, R Martin, C.M., and Clark, G.F. (2009) In situ double anomalous small-angle X-ray scattering of the sintering and calcination of sol-gel prepared yttria-stabilized zirconia ceramics. /. Phys. Chem. C, 113, 10021-10028. 

Bourell D.L., Parimal, Kaisser W. Sol-gel synthesis of nanophase yttria-stabilized tetragonal zirconia and densification behavior below 1600 K. J. Am. CCTam. Soc. 1993 76 705-711 Boyle T.J., Clem P.G., Rodriguez M.A., Heagy M.D., Tuttle B.A. Neo-pentoxide precursor synthesis, solution preparation and electronic properties of (Ba,Sr)Ti02 thin films derived from a solution route. Sol-Gel Sci. Technol. 1999 16 47-55... 

The coatings all contain the stabilized cubic phase. No second phases, tetragonal zirconia or yttria oxide, were detected. With sol-gel processed YSZ, residual porosity was removed after firing at 900°C for 5 h (Okubo, 1996). This densification temperature is lower than in the solid-state preparation where zirconia powders are reacted with yttria powder. 

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