Abstract
Effect of low-temperature degradation of 3Y-TZP ceramics (polycrystalline zirconia stabilized by 3mol% of yttria) on dry sliding wear behaviour and contact damage resistance has been studied applying scratch testing technique. Scratching by sharp (Vickers) and blunt (spherical) indenters was performed. Friction properties and damage mechanisms have been investigated for various degrees of hydrothermal ageing, i.e. for different grain sizes and crystallography, and for different thickness of the degraded surface layer. The 10 hours degradation did not lower the scratch resistance but lead to intensified fine debris production. The contact damage micromechanisms corresponding to various degrees of degradation have been studied in detail by interferometry and microscopy. The onset of plastic damage, catastrophic cracking, grain pull-out, spalling and chipping due to the degraded layer debonding have been identified. It was shown that 60 hours long ageing significantly degraded the surface damage resistance of the material. The critical load leading to such material’s surface layer destruction was found to be around 80 N.

Key words
ceramics, biomaterials, oxides, wear, grain growth

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