RESIDUAL-STRESS IN PARTIALLY-STABILIZED-ZIRCONIA TBCS - EXPERIMENTAL-MEASUREMENT AND MODELING

The residual stress field in 7wt% yttria partially stabilised zirconia (Y-PSZ) plasma sprayed (300-mu m thick) coatings on Al substrates was studied by means of two different techniques: X-ray residual stress a nalysis (XRSA), and elongation and curvature measurement after substra te removal (CD), Results were considerably improved with respect to co nventional XRSA, by using a synchrotron radiation source and specifica lly designed high resolution optics: an extended beam penetration, ach ieved by using different wavelengths down to 0.94 Angstrom allowed the determination of the strain field in the outer similar to 50 mu m of the ceramic. XRSA (surface) and CD (volume averaged) strain data were analysed by a mechanical model of the coated component capable of inte rgrating the results of both techniques. The procedure, designed to ap propriately consider the different nature of the information coming fr om the two measurement techniques, permitted us to study the residual stress distribution through the entire Y-PSZ coating thickness. In par ticular, it pointed out the presence of a considerable stress gradient in the surface region of the ceramic. (C) 1997 Elsevier Science S.A.