Influence of sintering parameters on the microstructure and mechanical properties of nanosized 3Y-TZP ceramics
Abstract The fracture toughness of 3Y-TZP ceramics obtained from a nanocrystalline powder with an optimized microstructure and highly transformable tetragonal grains was investigated. Samples of ZrO2-3 mol% Y2O3 were sintered at temperatures between 1250 and 1400 °C, with isothermal holding times of up to 16 h. Samples sintered at 1250 °C exhibited relative densities ranging between 92% and 98%, which increased with increasing isothermal duration, while samples sintered at 1300, 1350, or 1400 °C achieved densification higher than 98% for all isothermal treatments. Crystallographic analysis indicated the presence of a highly transformable ZrO2-tetragonal phase ( c / a √ 2 = 1 . 0148 - 1 . 0154 ) for all conditions studied. The average grain size ranged from 0.18±0.04 mm (1250 °C-0 h) to 0.64±0.08 mm (1400 °C-16 h), indicating activation energy of 141.3 kJ/mol for grain growth and a growth exponent of 2.8. Both Vickers hardness (1025 to 1300 HV) and fracture toughness (4.0 to 7.8 MPa.m1/2) increased with increasing sintering temperature and time due to increased densification, reduced porosity, and maintenance of potentially high fracture toughness by the t→m phase transformation.
| Main Authors: | , , , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Associação Brasileira de Cerâmica
2021
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| Online Access: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0366-69132021000100014 |
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| Summary: | Abstract The fracture toughness of 3Y-TZP ceramics obtained from a nanocrystalline powder with an optimized microstructure and highly transformable tetragonal grains was investigated. Samples of ZrO2-3 mol% Y2O3 were sintered at temperatures between 1250 and 1400 °C, with isothermal holding times of up to 16 h. Samples sintered at 1250 °C exhibited relative densities ranging between 92% and 98%, which increased with increasing isothermal duration, while samples sintered at 1300, 1350, or 1400 °C achieved densification higher than 98% for all isothermal treatments. Crystallographic analysis indicated the presence of a highly transformable ZrO2-tetragonal phase ( c / a √ 2 = 1 . 0148 - 1 . 0154 ) for all conditions studied. The average grain size ranged from 0.18±0.04 mm (1250 °C-0 h) to 0.64±0.08 mm (1400 °C-16 h), indicating activation energy of 141.3 kJ/mol for grain growth and a growth exponent of 2.8. Both Vickers hardness (1025 to 1300 HV) and fracture toughness (4.0 to 7.8 MPa.m1/2) increased with increasing sintering temperature and time due to increased densification, reduced porosity, and maintenance of potentially high fracture toughness by the t→m phase transformation. |
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