MODELING OF THE ANISOTROPIC ELASTIC PROPERTIES OF PLASMA-SPRAYED COATINGS IN RELATION TO THEIR MICROSTRUCTURE

摘要

The transversely isotropic elastic moduli of plasma-sprayed coatings are calculated in terms of microstructural parameters. The dominant features of the porous space are identified as strongly oblate pores, that tend to be either parallel or normal to the substrate. "Irregularities" in the porous space geome- try-the scatter in pore orientations and the difference between pore aspect ratios of the two pore sys- tems-are shown to have a pronounced effect on the effective moduli. They may be responsible for the "inverse" anisotropy (Young's modulus in the direction normal to the substrate being higher than the one in the transverse direction) and for the relatively high values of Poisson's ratio in the plane of isotropy. The analysis utilizes results of Kachanov et al. (Appl. Mech. Rev., l994, 47, 151) on materials with pores of diverse shapes and orientations.