Session BB9.6

4:45 PM BB9.6
QUANTITATIVE STUDIES OF THE THREE VOID SYSTEMS IN PLASMA-SPRAY DEPOSITS BY ANISOTROPIC MULTIPLE SMALL-ANGLE NEUTRON SCATTERING. Andrew J. Allen, Gabrielle G. Long, Jan Ilavsky*, National Institute of Standards and Technology, Materials Science and Engineering Laboratory, Gaithersburg, MD, *Current address: Institute of Plasma Physics, Prague, CZECH REPUBLIC.

In plasma-sprayed ceramic deposits, three void component morphologies can be identified: intra-splat cracks, inter-splat planar pores, and a broad size distribution of globular pores or bubbles. Small-angle neutron scattering (SANS) Porod studies have made an important contribution in characterizing the anisotropies in the surface area distributions of the intra-splat cracks and inter-splat pores, but there is a need to quantify the relative volume fractions and mean sizes of all three void systems, as well as the orientation distributions of the cracks and inter-splat pores, since these are major factors in determining the mechanical and thermal properties of the coatings. Multiple SANS (MSANS) measurements of neutron beam-broadening, as a function of wavelength, can provide much of this additional information. The dependence of MSANS on the microstructural anisotropy is different to that of Porod scattering, and while the globular pores contribute only slightly to the overall surface area (without orientational dependence), they represent a significant volume fraction that has a strong effect on the MSANS broadening. Quantitative results will be presented for the microstructural evolution during heat treatment for two yttria-stabilized zirconia thick-deposit systems sprayed using different feedstock materials.