Title: Thermal expansion coefficient of a NiCoCrAlY-ZrO₂(Y₂O₃) coating by a digital image processing based dilatometer

Authors: M. Beghini, L. Bertini, F. Frendo

Addresses: Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione, University of Pisa, via Diotisalvi, 2, I-56126 PISA, Italy. Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione, University of Pisa, via Diotisalvi, 2, I-56126 PISA, Italy. Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione, University of Pisa, via Diotisalvi, 2, I-56126 PISA, Italy

Abstract: A procedure for thermal expansion coefficient measurement is presented. A quartz dilatometer and a digital image processing technique were employed to obtain an accurate measure of the elongation of a prismatic specimen placed in a tubular furnace. By testing several symmetrically coated specimens the thermal expansion coefficient of a NiCoCrAlY-ZrO₂(Y₂O₃) coating was obtained. The relationships for deducing the coefficient of the coating were derived by the multi-layer beam model and their sensitivity to experimental errors was discussed. Results were obtained in the range 20°C-950°C, both for the substrate and coating materials. An estimate of results accuracy is given, based on a Monte Carlo simulation of uncertainties.

Keywords: ceramic coatings; thermal expansion coefficient; image processing.

DOI: 10.1504/IJMPT.2000.001237

International Journal of Materials and Product Technology, 2000 Vol.15 No.1/2, pp.78-90

Published online: 01 Jul 2003 *

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