ATZ composites with enhanced mechanical reliability and lifetime

Abstract

Tetragonal zirconia demonstrates very good mechanical properties in rapid tests but reveals the strength decrease over time typical for oxide materials. If the material is loaded for a long period of time, the subcritical crack propagation occurs. Introducing additional phases into the zirconia matrix can both limit the grain size growth and introduce residual stresses, which can retard or even stop the crack run. The base of this work is a composite from the family of alumina toughened zirconia (ATZ) ones with a dispersed small content of alumina (1.5 wt%). The matrix was obtained via common sintering of different zirconia powders with various yttria content, which resulted in the material of a very small grain size. Incorporating additional alumina (8.4 or 15.8 wt%) led to the independence of strength from the loading time. Other calculations were made in order to estimate the survival time of the material working under load.