Characterization of Ceria Stabilized Zirconia Coatings on Metal Substrates
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CHARACTERIZATION
OF CERIA STABILIZED ZIRCONIA COATINGS ON METAL SUBSTRATES
ROSA DI MAGGIO*, PAOLO SCARDI* and ANDREA TOMASIO *Department of Materials Engineering,University of Trento,Italy; oInstitute for Scientific and Thecnologic Research,Trento,Italy.
ABSTRACT In this study ceria stabilized zirconia was used to obtain an uniform and adherent film on iron and 304 S.S.. Coatings were prepared by dipping in solutions of organometallic precursors of zirconium and cerium. Structure and morphology of samples were investigated using SEM and XRD techniques before and after of coated air thermal treatments. The oxidation behaviour in samples was followed through thermogravimetrical analysis in a The preliminary range of temperature from 773 K to 1123 K. high for the samples coated and pretreated in results show, vacuum at 923 K, a good decrease in oxidation rate. INTRODUCTION Until now material research has focused on the use of coating processes to provide materials with superior properties resistance i.e. chemical durability, alkali resistance, heat is suitable for The sol-gel technique against oxidation. producing oxide powders but also for forming thin oxide films on various substrates at low temperature with good homogeneity [1]. The dip-coating technique has been extensively studied as regards silica-based coatings and zirconia coating on glass In the recent years a few reports concerning sol-gel [2,3]. films on metal substrates were available in the literature[4,5]. to show the role of the The purpose of the present work is 18% mol CeO 2 chemical and morphological parameters of the stabilized-ZrO2 films in improving the heat resistance of iron and 304 S.S. against oxidation. EXPERIMENTAL PROCEDURE available analytical were commercially All chemicals dip-coating was The solution for reagent-grade products. prepared adding the proper amount of zirconium tetra-n-butoxide (III)-2-4and cerium (containing 50% of n-butyl alcohol) pentanedionate in the molar ratio of 82:18 to anhydrous ethyl concentration of 0.3 mol/L. The alcohol to reach the total it at room temperature until solution obtained was stirred Substrates were and was utilized immediately aftei. clarified sheets 20x10x2 mm . Before coating, pure iron and 304 S.S. samples were grinded on 1000 emery paper and then degreased by produced acetone. The coatings were ultrasonically in withdrawing the substrates from the solutions at a constant rate (0.5 cm/s) and dried at 353 K for one h ur. The• the specimens were heat treated in vacuum at 653 K (10-T or 101% torr). The heat resistence of the coated sheets against oxidation 24h heat gain during measuring the weight was evaluated treatment in air at 753 K for iron and 1123 K for stainless steel specimens. The oxidation data were collected by a Mettler surface thermobalance TAI. Before and after heat treatment the Mat. Res. Soc. Symp. Proc. Vol. 180. @1990 Materials Research Society
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Scansion Electron coatings were observed using a Cambridge Microscope whereas the structural characterization of the films and
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