College Park, Maryland June 6 - 10 , 2004
T3-C5 (5:00 PM): Small-Angle Neutron Scattering: a Pioneering Tool to Comprehend Processing–Structure–Property Relationships in Thermal Barrier Coatings
A. Kulkarni (Dept. of Matls Sci and Eng, Univ. at Stony Brook, Stony Brook, NY 11794-2275)
Thermal barrier coatings (TBCs) are extensively applied on hot sections in gas turbine engines to provide protection against thermo-mechanical and hot corrosion environments. Critical properties of the TBCs are governed by the nature and architecture of the void microstructures, an enhanced understanding of which will lead to improvements in coating performance during service. These ceramic TBCs are presently deposited using plasma spray and electron beam physical vapor deposition (EB-PVD) processes, each producing distinctive microstructures. A multidisciplinary approach involving advanced neutron scattering and x-ray imaging techniques has been undertaken, in this joint NIST-SUNY Stony Brook program, to establish the salient processing–structure–property relationships in TBCs. Microstructure information on porosity, void orientation distribution, mean opening dimensions and internal surface areas is obtained and important connections are established with the measured deposit properties, such as thermal conductivity and elastic modulus. In particular, SANS has succeeded in a) establishing rational process-induced porosity-property correlations and b) quantifying the sintering kinetics and phase stability of TBCs during the high-temperature conditions encountered in service. The microstructural parameters determined by SANS studies have been assembled into a finite element model that shows promise for providing a truly predictive capability for determining coating properties and performance. SANS is increasingly recognized as a successful research tool in advanced TBC development.
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