Residual stress and fracture of laminated ceramic membranes

Bilayer laminated ceramic membranes were produced comprising a layer of gad olinia-doped ceria (CGO) 180 mu m thick and a layer of yttria-stabilized zi rconia (YSZ) 5 mu m thick. The residual stresses in the laminates at room t emperature were estimated from their curvature and the elastic constants of the individual layers. The fracture of the laminates was studied in biaxia l flexure at 25 and 800 degrees C. The mean failure stress in the CGO in th e laminates was much greater than in unlaminated CGO. This is due partly to an improved microstructure from the lamination process and partly to the r estraint of the compressively stressed YSZ. The combined effects of higher failure stress and residual stresses lead to the laminated membranes having higher apparent strength than single layer CGO membranes by Factors of bet ween 1.75 and 4.06. (C) 1999 Acta Metallurgica Inc. Published by Elsevier S cience Ltd. All rights reserved.