Influence of Y sub 2 O sub 3 distribution on the rate of tetragonal to monoclinic phase transformation of yttria-stabilized zirconia during hydrothermal aging

摘要

Tetragonal to monoclinic phase transformation of yttria-stabilized zirconia, namely plasma-sprayed coatings and sintered bodies containing 4-8 mass% Y sub 2 O sub 3 during hydrothermal aging was investigated with respect to Y sub 2 O sub 3 distribution using 1 mu m phi area from electron probe microanalysis (EPMA) and 20 nm phi area from transmission electron microscopy (TEM) analysis. Phase transformation at 473K was prevented only in plasma-sprayed coating having >6.7 mass% Y sub 2 O sub 3 in 20 nm phi microscopic area. Furthermore, it was confirmed influence of Y sub 2 O sub 3 distribution on the rate constants of this phase transformation was observed at 368K.