A novel fine-grained orthorhombic ZrO2ceramic stabilized with 12 mol% Ta doping was fabricated by spark-plasma sintering from home-made powders, and its high-temperature mechanical properties evaluated for the first time by compressive creep tests in both Ar and air. It was found that the high-temperature plasticity of the ceramic deformed in Ar, under which the Ta-doped orthorhombic ZrO2is a black suboxide with abundant oxygen vacancies in its crystal structure, is controlled by grain boundary sliding (stress exponent ∼2, and activation energy ∼780–800 kJ/mol). However, the high-temperature plasticity of the ceramic deformed in air, under which the Ta-doped orthorhombic ZrO2is a white oxide due to the elimination in situ of oxygen vacancies, is controlled by recovery creep (stress exponent ∼3, and activation energy ∼750 kJ/mol). It was also observed that black Ta-doped orthorhombic ZrO2is more creep resistant than its white counterpart with the same grain size, and that the former deforms as the more conventional Y2O3-stabilized ZrO2does.

High-temperature compressive creep of novel fine-grained orthorhombic ZrO2ceramics stabilized with 12 mol% Ta doping

Sponchia, Gabriele;Riello, Pietro;Benedetti, Alvise;
2018-01-01

Abstract

A novel fine-grained orthorhombic ZrO2ceramic stabilized with 12 mol% Ta doping was fabricated by spark-plasma sintering from home-made powders, and its high-temperature mechanical properties evaluated for the first time by compressive creep tests in both Ar and air. It was found that the high-temperature plasticity of the ceramic deformed in Ar, under which the Ta-doped orthorhombic ZrO2is a black suboxide with abundant oxygen vacancies in its crystal structure, is controlled by grain boundary sliding (stress exponent ∼2, and activation energy ∼780–800 kJ/mol). However, the high-temperature plasticity of the ceramic deformed in air, under which the Ta-doped orthorhombic ZrO2is a white oxide due to the elimination in situ of oxygen vacancies, is controlled by recovery creep (stress exponent ∼3, and activation energy ∼750 kJ/mol). It was also observed that black Ta-doped orthorhombic ZrO2is more creep resistant than its white counterpart with the same grain size, and that the former deforms as the more conventional Y2O3-stabilized ZrO2does.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10278/3698814
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