Evolution of the void structure in plasma-sprayed YSZ deposits during heating

The evolution of the anisotropic void microstructure of plasma-sprayed yttr ia-stabilized zirconia (YSZ) deposits has been observed as a function of te mperature by small-angle neutron scattering. Scattering experiments were ca rried out in-situ, in a furnace between 600 and 1400 degrees C. The termina l slope (Porod scattering) of the scattering spectra was used to derive the specific surface area of the voids. For samples with sufficient scattering anisotropy, the two major void systems - intersplat (inter-lamellar) pores and intrasplat cracks - could be characterized separately. The pore and cr ack specific surface areas were found to depend on temperature differently. The specific surface area of the intrasplat cracks decreased markedly at t emperatures below 1000 degrees C, whereas the specific surface area of the intersplat pores began to decrease above 1000 degrees C. This indicates imp ortant differences in the sintering of these two void systems probably rela ted to their size and shape. Changes in the void surface were observed at t emperatures as low as 800 degrees C, a temperature comparable to, or less t han, the usual operational temperature for this material. (C) 1999 Publishe d by Elsevier Science S.A. All rights reserved.