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123 results on '"Podzorova, L. I."'

18. Low-Temperature Aging of Al2O3–[ZrYb]O2 Composites Containing Strontium Hexaaluminate.

Author

Podzorova, L. I., Il'icheva, A. A., Pen'kova, O. I., Sirotinkin, V. P., Antonova, O. S., Baikin, A. S., and Kochanov, G. P.

Abstract

The effect of the hydrothermal treatment corresponding to accelerated low-temperature aging and simulating a prolonged exposure to a biological environment on the phase composition and bending strength of Al2O3–[ZrYb]O2 composites containing a variable amount of Al2O3 and including strontium hexaaluminate has been investigated. It has been shown that, after the hydrothermal action, the composites retain their bending strength ranging from 700 to 850 MPa, depending on composition. This indicates the preservation of the phase composition in the bulk of the materials. It has been determined that, in the surface layer of the samples, the zirconia monoclinic phase forms in an amount from 11 to 9%, related to the growing alumina content in the composites. Such amounts of the monoclinic zirconia phase formed is well below a limit value of 25% specified by the ISO 13356 2015 standard. The investigated composites can be promising for medical applications. [ABSTRACT FROM AUTHOR]

Published
2023
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22. Low-Temperature Aging of Al2O3–[ZrYb]O2Composites Containing Strontium Hexaaluminate

Author

Podzorova, L. I., Il’icheva, A. A., Pen’kova, O. I., Sirotinkin, V. P., Antonova, O. S., Baikin, A. S., and Kochanov, G. P.

Abstract

Abstract: The effect of the hydrothermal treatment corresponding to accelerated low-temperature aging and simulating a prolonged exposure to a biological environment on the phase composition and bending strength of Al2O3–[ZrYb]O2composites containing a variable amount of Al2O3and including strontium hexaaluminate has been investigated. It has been shown that, after the hydrothermal action, the composites retain their bending strength ranging from 700 to 850 MPa, depending on composition. This indicates the preservation of the phase composition in the bulk of the materials. It has been determined that, in the surface layer of the samples, the zirconia monoclinic phase forms in an amount from 11 to 9%, related to the growing alumina content in the composites. Such amounts of the monoclinic zirconia phase formed is well below a limit value of 25% specified by the ISO 13356 2015 standard. The investigated composites can be promising for medical applications.

Published
2023
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31. Composites of the Al2O3/Yb-TZP System Modified with Calcium, Strontium, and Barium Cations.

Author

Podzorova, L. I., Kutuzova, V. E., Il'ichyova, A. A., Pen'kova, O. I., Sirotinkin, V. P., Konovalov, A. A., Antonova, O. S., and Baikin, A. S.

Abstract

Abstract—The possibility of implementing two simultaneous strengthening mechanisms in a ceramic system of Al2O3 and ZrO2 is discussed, namely, a transformation mechanism due to the tetragonal form of zirconium dioxide and a dispersion one due to the in situ formation of hexaaluminates of alkaline earth elements. The concentrations of modifying additives of calcium, strontium, and barium oxides that yield the formation of corresponding hexaaluminates have been established. The influence of the formed phases on the microstructure and strength characteristics of the obtained composites is considered. The samples of composites containing strontium cations exhibit high strength characteristics, namely, the flexural strength of 700 MPa and critical stress intensity coefficient K1C up to 10 MPa m1/2, which is due to the effective combined influence of the transformation and dispersion-strengthening effects. [ABSTRACT FROM AUTHOR]

Published
2022
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49. Formation of Strontium Hexaaluminate in Alumina–Tetragonal Zirconia Systems Modified with Strontium Cations.

Author

Il'icheva, A. A., Podzorova, L. I., Sirotinkin, V. P., Antonova, O. S., Konovalov, A. A., Kutuzova, V. E., and Pen'kova, O. I.

Abstract

The effect of modifying strontium cations on the phase composition of the sol–gel synthesized matrix systems containing 20% of Al2O3 and 80% of a tetragonal zirconia polycrystals (TZP) solid solution stabilized by cerium [Ce-TZP] and ytterbium [Yb-TZP] cations is studied. The microstructure of the composites with a [Yb-TZP] matrix has a more fine-grained composition (200–500 nm) than the microstructure of the [Ce-TZP] matrix composites, whose grain sizes range within 800–1500 nm. Independently of the matrix solid solution type, modification promotes the formation of composites with a three-grain microstructure including long prismatic SrAl12O19 grains, which may perform dispersion strengthening in the composites. [ABSTRACT FROM AUTHOR]

Published
2020
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50. Al2O3-Based Ceramic Composites with a High Brittle Fracture Resistance.

Author

Podzorova, L. I., Il'icheva, A. A., Pen'kova, O. I., Antonova, O. S., Baikin, A. S., and Konovalov, A. A.

Subjects
BRITTLE fractures, FRACTURE toughness, DISPERSION strengthening, BENDING strength, SOLID solutions, CERAMIC-matrix composites
Abstract

We examine synthesis conditions of precursors to ZrO2–Al2O3–CeO2 powders modified with calcium cations. The precipitation procedure and the aging of reaction systems of precursors to the synthesized composites are shown to influence the morphology and particle size of the nanopowders and the evolution of the phase composition, microstructure, and mechanical characteristics of composites prepared from them. The composites offer a high brittle fracture resistance due to the combined effect of transformation and dispersion hardening owing to the presence of T-ZrO2-based solid solutions and calcium hexaaluminates (bending strength, up to 1000 MPa; fracture toughness KIc, up to 10.5 MPa m1/2). [ABSTRACT FROM AUTHOR]

Published
2019
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