The Effects of High-Temperature- and High-Pressure-Water on the Low Temperature Degradation Behavior of Y-TZP

Low temperature degradation of Y-TZP materials

“…The former study measured the thickness of the degraded layer in a 2.0 mol % Y-TZP exposed for 1000h at 250 ~ in air, as approximately 100 gm. The difference in thickness and crack severity can be attributed to the presence of water vapour during the treatment used in the present study, because it has been shown that the presence of water enhances the t --* m transformation [5,[12][13][14]16]. The remaining Y-TZPs showed no signs of physical change.…”

“…This m-ZrO2 layer is approximately 100-150 ~tm deep around the entire bar. Other investigators [4,6,12,13,16,17] have also reported seeing these zones of transformation. The strengthlimiting flaw is still porosity related (Fig.…”

“…They ranged in thickness from 250 to 650gm. Schmauder and Schubert [9] and Yoshimura et al [13] have seen large cracks running parallel to the surface of the specimen. It is believed that the crack separates the transformed material from the untransformed material.…”

“…The hypotheses of Yoshimura et al [10,13] is similar in that it is also based on the formation of Zr-OH bonds but they suggest a four-step degradation process. The H20 is adsorbed onto the Y-TZP surface and dissociates forming Zr-OH bonds which creates stress sites.…”

Role of Oxide Additives in Stabilizing Zirconia for Coating Applications

“…This, coupled with the growth of pre-existing flaws, accelerates the transformation. The hypotheses of Yoshimura et al [30][31] is similar in that it is also based on the formation of Zr-OH bonds, but they suggest a four-step degradation process. The H 2 0 is absorbed onto the Y-TZP surface and dissociates, forming Zr-OH bonds which create stress sites.…”