α-alumina and spinel react into single-phase high-alumina spinel in <3 seconds during flash sintering

David Kok; Devinder Yadav; Emanuele Sortino; Scott J. McCormack; Kuo Pin Tseng; Waltraud M. Kriven; Rishi Raj; Martha L. Mecartney

doi:10.1111/jace.15927

α-alumina and spinel react into single-phase high-alumina spinel in <3 seconds during flash sintering

David Kok, Devinder Yadav, Emanuele Sortino, Scott J. McCormack, Kuo Pin Tseng, Waltraud M. Kriven, Rishi Raj, Martha L. Mecartney

Research output: Contribution to journal › Article › peer-review

Abstract

In situ X-ray diffraction measurements at the Advanced Photon Source show that α-Al ₂ O ₃ and MgAl ₂ O ₄ react nearly instantaneously and completely, and nearly completely to form single-phase high-alumina spinel during voltage-to-current type of flash sintering experiments. The initial sample was constituted from powders of α-Al ₂ O ₃ , MgAl ₂ O ₄ spinel, and cubic 8 mol% Y ₂ O ₃ -stabilized ZrO ₂ (8YSZ) mixed in equal volume fractions, the spinel to alumina molar ratio being 1:1. 5. Specimen temperature was measured by thermal expansion of the platinum standard. These measurements correlated well with a black-body radiation model, using appropriate values for the emissivity of the constituents. Temperatures of 1600-1736°C were reached during the flash, which promoted the formation of alumina-rich spinel. In a second set of experiments, the flash was induced in a current-rate method where the current flowing through the specimen is controlled and increased at a constant rate. In these experiments, we observed the formation of two different compositions of spinel, MgO•3Al ₂ O ₃ and MgO•1.5Al ₂ O ₃ , which evolved into a single composition of MgO•2.5Al ₂ O ₃ as the current continued to increase. In summary, flash sintering is an expedient way to create single-phase, alumina-rich spinel.

Original language	English (US)
Journal	Journal of the American Ceramic Society
Volume	102
Issue number	2
DOIs	https://doi.org/10.1111/jace.15927
State	Published - 2019

Keywords

Alumina
Composites
Field assisted sintering technology
Spinels
Zirconia: yttria stabilized

ASJC Scopus subject areas

Ceramics and Composites
Materials Chemistry

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α-alumina and spinel react into single-phase high-alumina spinel in <3 seconds during flash sintering. / Kok, David; Yadav, Devinder; Sortino, Emanuele; McCormack, Scott J.; Tseng, Kuo Pin; Kriven, Waltraud M.; Raj, Rishi; Mecartney, Martha L.

In: Journal of the American Ceramic Society, Vol. 102, No. 2, 2019.

Research output: Contribution to journal › Article › peer-review

@article{718bc41383304e73a0075ed61fc6d1d2,

title = "α-alumina and spinel react into single-phase high-alumina spinel in <3 seconds during flash sintering",

abstract = " In situ X-ray diffraction measurements at the Advanced Photon Source show that α-Al 2 O 3 and MgAl 2 O 4 react nearly instantaneously and completely, and nearly completely to form single-phase high-alumina spinel during voltage-to-current type of flash sintering experiments. The initial sample was constituted from powders of α-Al 2 O 3 , MgAl 2 O 4 spinel, and cubic 8 mol% Y 2 O 3 -stabilized ZrO 2 (8YSZ) mixed in equal volume fractions, the spinel to alumina molar ratio being 1:1. 5. Specimen temperature was measured by thermal expansion of the platinum standard. These measurements correlated well with a black-body radiation model, using appropriate values for the emissivity of the constituents. Temperatures of 1600-1736°C were reached during the flash, which promoted the formation of alumina-rich spinel. In a second set of experiments, the flash was induced in a current-rate method where the current flowing through the specimen is controlled and increased at a constant rate. In these experiments, we observed the formation of two different compositions of spinel, MgO•3Al 2 O 3 and MgO•1.5Al 2 O 3 , which evolved into a single composition of MgO•2.5Al 2 O 3 as the current continued to increase. In summary, flash sintering is an expedient way to create single-phase, alumina-rich spinel. ",

keywords = "Alumina, Composites, Field assisted sintering technology, Spinels, Zirconia: yttria stabilized",

author = "David Kok and Devinder Yadav and Emanuele Sortino and McCormack, {Scott J.} and Tseng, {Kuo Pin} and Kriven, {Waltraud M.} and Rishi Raj and Mecartney, {Martha L.}",

note = "Funding Information: National Science Foundation, Grant/Award Number: CMMI MEP 1662791; U.S. Department of Energy (DOE); Argonne National Laboratory, Grant/Award Number: DE-AC02-06CH11357; Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program; Army Research Office, Grant/Award Number: W911NF-16-1-0200 Funding Information: The authors gratefully acknowledge the assistance of Evguenia Karapetrova at Argonne National Lab, Beamline 33BMC where the in situ synchrotron experiments were performed. This material was based on work supported by the National Science Foundation under Grant No. CMMI MEP 1662791 and U.S. Department of Energy (DOE); Argonne National Laboratory, Grant/Award Number: DE‐ AC02‐06CH11357. DK acknowledges support from the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program. SEM work was performed at the UC Irvine Materials Research Institute (IMRI). The University of Colorado Boulder investigators gratefully acknowledge support from the Army Research Office, Grant/Award Number: W911NF‐16‐1‐0200.",

year = "2019",

doi = "10.1111/jace.15927",

language = "English (US)",

volume = "102",

journal = "Journal of the American Chemical Society",

issn = "0002-7863",

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T1 - α-alumina and spinel react into single-phase high-alumina spinel in <3 seconds during flash sintering

AU - Kok, David

AU - Yadav, Devinder

AU - Sortino, Emanuele

AU - McCormack, Scott J.

AU - Tseng, Kuo Pin

AU - Kriven, Waltraud M.

AU - Raj, Rishi

AU - Mecartney, Martha L.

N1 - Funding Information: National Science Foundation, Grant/Award Number: CMMI MEP 1662791; U.S. Department of Energy (DOE); Argonne National Laboratory, Grant/Award Number: DE-AC02-06CH11357; Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program; Army Research Office, Grant/Award Number: W911NF-16-1-0200 Funding Information: The authors gratefully acknowledge the assistance of Evguenia Karapetrova at Argonne National Lab, Beamline 33BMC where the in situ synchrotron experiments were performed. This material was based on work supported by the National Science Foundation under Grant No. CMMI MEP 1662791 and U.S. Department of Energy (DOE); Argonne National Laboratory, Grant/Award Number: DE‐ AC02‐06CH11357. DK acknowledges support from the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program. SEM work was performed at the UC Irvine Materials Research Institute (IMRI). The University of Colorado Boulder investigators gratefully acknowledge support from the Army Research Office, Grant/Award Number: W911NF‐16‐1‐0200.

PY - 2019

Y1 - 2019

N2 - In situ X-ray diffraction measurements at the Advanced Photon Source show that α-Al 2 O 3 and MgAl 2 O 4 react nearly instantaneously and completely, and nearly completely to form single-phase high-alumina spinel during voltage-to-current type of flash sintering experiments. The initial sample was constituted from powders of α-Al 2 O 3 , MgAl 2 O 4 spinel, and cubic 8 mol% Y 2 O 3 -stabilized ZrO 2 (8YSZ) mixed in equal volume fractions, the spinel to alumina molar ratio being 1:1. 5. Specimen temperature was measured by thermal expansion of the platinum standard. These measurements correlated well with a black-body radiation model, using appropriate values for the emissivity of the constituents. Temperatures of 1600-1736°C were reached during the flash, which promoted the formation of alumina-rich spinel. In a second set of experiments, the flash was induced in a current-rate method where the current flowing through the specimen is controlled and increased at a constant rate. In these experiments, we observed the formation of two different compositions of spinel, MgO•3Al 2 O 3 and MgO•1.5Al 2 O 3 , which evolved into a single composition of MgO•2.5Al 2 O 3 as the current continued to increase. In summary, flash sintering is an expedient way to create single-phase, alumina-rich spinel.

AB - In situ X-ray diffraction measurements at the Advanced Photon Source show that α-Al 2 O 3 and MgAl 2 O 4 react nearly instantaneously and completely, and nearly completely to form single-phase high-alumina spinel during voltage-to-current type of flash sintering experiments. The initial sample was constituted from powders of α-Al 2 O 3 , MgAl 2 O 4 spinel, and cubic 8 mol% Y 2 O 3 -stabilized ZrO 2 (8YSZ) mixed in equal volume fractions, the spinel to alumina molar ratio being 1:1. 5. Specimen temperature was measured by thermal expansion of the platinum standard. These measurements correlated well with a black-body radiation model, using appropriate values for the emissivity of the constituents. Temperatures of 1600-1736°C were reached during the flash, which promoted the formation of alumina-rich spinel. In a second set of experiments, the flash was induced in a current-rate method where the current flowing through the specimen is controlled and increased at a constant rate. In these experiments, we observed the formation of two different compositions of spinel, MgO•3Al 2 O 3 and MgO•1.5Al 2 O 3 , which evolved into a single composition of MgO•2.5Al 2 O 3 as the current continued to increase. In summary, flash sintering is an expedient way to create single-phase, alumina-rich spinel.

KW - Alumina

KW - Composites

KW - Field assisted sintering technology

KW - Spinels

KW - Zirconia: yttria stabilized

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