Hydrotermální koroze tetragonální ZrO2

Hydrothermal ageing of tetragonal zirconia ceramics

journal article - other

en

The effect of hydrothermal treatment on the phase stability, microstructure and mechanical properties of tetragonal zirconia ceramics stabilized with 3 mol% yttria was studied. At temperatures of 140-260C the tetragonal phase transformed into monoclinic zirconia. The degree of transformation increased with increasing temperature and time of ageing. Changes in the microstructure and mechanical properties were observed for the samples used at temperatures of 180C and higher. The thickness of transformed layer increased with increasing temperature and at 260C it reached a thickness of 170 mikrom after 10 hours. The changes in mechanical properties (hardness and fracture toughness) corresponded to the structural changes in the material caused by hydrothermal ageing. Temperatures of 180C and higher were critical for the mechanical and structural properties of the material.

Byl studován vliv hydrotermálních podmínek na fázovou stabilitu, mikrostrukturu a mechanické vlastnosti tetragonální ZrO2 keramiky stabilizované 3 mol% Y2O3. Při teplotách 140-260C došlo k transformaci tetragonální fáze na monoklinický ZrO2. Míra transformace rostla s rostoucí teplotou a dobou působení. Změna mikrostruktury a mechanických vlastností byla zaznamenána při teplotách 180C a vyšších. S rostoucí teplotou tloušťka transformované vrstvy rostla a při 260C dosáhla tloušťky 170 -956mikrom. Změna mechanických vlastností (tvrdosti a lomové houževnatosti) odpovídala strukturním změnám v materiálu způsobených hydrotermálním působením. Teploty 180C a vyšší byly pro mechanické a strukturní vlastnosti materiálu kritické.

The effect of hydrothermal treatment on the phase stability, microstructure and mechanical properties of tetragonal zirconia ceramics stabilized with 3 mol% yttria was studied. At temperatures of 140-260C the tetragonal phase transformed into monoclinic zirconia. The degree of transformation increased with increasing temperature and time of ageing. Changes in the microstructure and mechanical properties were observed for the samples used at temperatures of 180C and higher. The thickness of transformed layer increased with increasing temperature and at 260C it reached a thickness of 170 mikrom after 10 hours. The changes in mechanical properties (hardness and fracture toughness) corresponded to the structural changes in the material caused by hydrothermal ageing. Temperatures of 180C and higher were critical for the mechanical and structural properties of the material.

Zirconia, Hydrothermal ageing, Phase transformation, Mechanical properties

01.01.2004

0862-5468

Ceramics-Silikáty

48

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