Hydrothermal and corrosive degradation of Y-TZP ceramics

The effects of hydrothermal ageing and corrosive degradation of commercial Y-TZPs have been investigated and the interrelationships between the two mechanisms established. The results clearly show that grain boundary impurities (such as a glassy grain boundary phase) significantly influence the hydrothermal ageing resistance and the Y-TZP susceptibility to acidic and basic attack. It has also been shown that a plasma synthesised zirconia base powder coated with yttria has excellent ageing and corrosion resistance compared to Y-TZPs manufactured using a coprecipitation technique. It has been confirmed that in the absence of an intergranular glassy phase the corrosive degradation of Y-TZP is primarily controlled by the presence of water, i.e. hydrothermal degradation.