Improved Low‐Temperature Environmental Degradation of Yttria‐Stabilized Tetragonal Zirconia Polycrystals by Surface Encapsulation

Abstract

An encapsulating layer was deposited on the surface of tetragonal zirconia polycrystals doped with 3 mol% of yttria (3Y‐TZP), to prevent low‐temperature environmental degradation (aging) of the material. The layer, which was composed of silica and zircon, was formed on the surface by exposing the specimens next to a bed of silicon carbide powder in a flowing hydrogen atmosphere that contained ∼0.1% water vapor at 1450°C. The layer was ∼0.5 µm thick and is expected to be under strong residual compressive stress. This encapsulation process remarkably improved the low‐temperature degradation of the material. The strength of the specimens also was improved by this process.