Spark Plasma Sintering of SiAlON Ceramics Synthesized via Various Cations Charge Stabilizers and Their Effect on Thermal and Mechanical Characteristics

Oxygen-rich SiAlON ceramics doped with various nanosized metal oxide (MO) stabilizers were synthesized with a view to examine their effect on thermal and mechanical characteristics. The nanosized starting powder precursors comprising Si<sub>3</sub>N<sub>4</sub>, AlN, Al<su...

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Autores principales:	Muhammad Zulqarnain Falak, Bilal Anjum Ahmed, Hasan Aftab Saeed, Sajid Ullah Butt, Abbas Saeed Hakeem, Usman Ali Akbar
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	SiAlONs spark plasma sintering thermal and mechanical behavior rare earth alkaline earth Crystallography QD901-999
Acceso en línea:	https://doaj.org/article/4693becebb96418ea2cb03073e13c374
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spelling	oai:doaj.org-article:4693becebb96418ea2cb03073e13c3742021-11-25T17:19:08ZSpark Plasma Sintering of SiAlON Ceramics Synthesized via Various Cations Charge Stabilizers and Their Effect on Thermal and Mechanical Characteristics10.3390/cryst111113782073-4352https://doaj.org/article/4693becebb96418ea2cb03073e13c3742021-11-01T00:00:00Zhttps://www.mdpi.com/2073-4352/11/11/1378https://doaj.org/toc/2073-4352Oxygen-rich SiAlON ceramics doped with various nanosized metal oxide (MO) stabilizers were synthesized with a view to examine their effect on thermal and mechanical characteristics. The nanosized starting powder precursors comprising Si<sub>3</sub>N<sub>4</sub>, AlN, Al<sub>2</sub>O<sub>3</sub>, and SiO<sub>2</sub> along with oxides of Ba, Y, Mg, La, Nd, Eu, Dy, Er, and Yb as the MO charge stabilizer were employed in developing different SiAlON samples. Ultrasonic probe sonication was utilized to develop a homogenous mixture of initial powder precursors followed by spark plasma sintering (SPS) of the samples at the low temperature of 1500 °C coupled with 30 min of isothermal treatment. Sample compositions (according to general formula of alpha SiAlON: M<sub>m/v</sub><sup>v+</sup>Si<sub>12−(m+n)</sub>Al<sub>m+n</sub>O<sub>n</sub>N<sub>16−n</sub>) selected in the present study are represented by m value of 1.1 and n value of 1.6. The synthesized samples were evaluated for their physical behavior, microstructural and crystal structure evolution, and thermal and mechanical characteristics. More specifically, the sintered ceramics were examined by X-ray diffraction and electron microscopy to comprehend and relate the structural characteristics with the densification, thermal conductivity, hardness, and fracture toughness. The high reactivity of the nanopowders and the localized heating provided by SPS resulted in densified ceramics with relative densities in the range of 92–96%. Vickers hardness values were found to be in the range of 12.4–17.0 GPa and were seen to be profoundly influenced by the grain size of the alpha SiAlON (primary) phase. The fracture toughness of the samples was measured to be in the range of 4.1–6.2 MPa·m<sup>1/2</sup>. SiAlON samples synthesized using Er and Yb charge stabilizers were found to have the highest fracture toughness of 5.7 and 6.2 MPa·m<sup>1/2</sup>, primarily due to the relatively higher content of the elongated beta phase. While there was no obvious relationship between the thermal conductivity and the alpha SiAlON metal charge stabilizers, the values were seen to be influenced by the grain size of alpha phase where Dy-SiAlON had the lowest thermal conductivity of 5.79 W/m⋅K and Er-SiAlON showed the highest value of thermal conductivity (6.91 W/m⋅K). It was concluded that scientifically selected metal oxide charge stabilizers are beneficial in developing SiAlON ceramics with properties tailored according to specific applications.Muhammad Zulqarnain FalakBilal Anjum AhmedHasan Aftab SaeedSajid Ullah ButtAbbas Saeed HakeemUsman Ali AkbarMDPI AGarticleSiAlONsspark plasma sinteringthermal and mechanical behaviorrare earthalkaline earthCrystallographyQD901-999ENCrystals, Vol 11, Iss 1378, p 1378 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	SiAlONs spark plasma sintering thermal and mechanical behavior rare earth alkaline earth Crystallography QD901-999
spellingShingle	SiAlONs spark plasma sintering thermal and mechanical behavior rare earth alkaline earth Crystallography QD901-999 Muhammad Zulqarnain Falak Bilal Anjum Ahmed Hasan Aftab Saeed Sajid Ullah Butt Abbas Saeed Hakeem Usman Ali Akbar Spark Plasma Sintering of SiAlON Ceramics Synthesized via Various Cations Charge Stabilizers and Their Effect on Thermal and Mechanical Characteristics
description	Oxygen-rich SiAlON ceramics doped with various nanosized metal oxide (MO) stabilizers were synthesized with a view to examine their effect on thermal and mechanical characteristics. The nanosized starting powder precursors comprising Si<sub>3</sub>N<sub>4</sub>, AlN, Al<sub>2</sub>O<sub>3</sub>, and SiO<sub>2</sub> along with oxides of Ba, Y, Mg, La, Nd, Eu, Dy, Er, and Yb as the MO charge stabilizer were employed in developing different SiAlON samples. Ultrasonic probe sonication was utilized to develop a homogenous mixture of initial powder precursors followed by spark plasma sintering (SPS) of the samples at the low temperature of 1500 °C coupled with 30 min of isothermal treatment. Sample compositions (according to general formula of alpha SiAlON: M<sub>m/v</sub><sup>v+</sup>Si<sub>12−(m+n)</sub>Al<sub>m+n</sub>O<sub>n</sub>N<sub>16−n</sub>) selected in the present study are represented by m value of 1.1 and n value of 1.6. The synthesized samples were evaluated for their physical behavior, microstructural and crystal structure evolution, and thermal and mechanical characteristics. More specifically, the sintered ceramics were examined by X-ray diffraction and electron microscopy to comprehend and relate the structural characteristics with the densification, thermal conductivity, hardness, and fracture toughness. The high reactivity of the nanopowders and the localized heating provided by SPS resulted in densified ceramics with relative densities in the range of 92–96%. Vickers hardness values were found to be in the range of 12.4–17.0 GPa and were seen to be profoundly influenced by the grain size of the alpha SiAlON (primary) phase. The fracture toughness of the samples was measured to be in the range of 4.1–6.2 MPa·m<sup>1/2</sup>. SiAlON samples synthesized using Er and Yb charge stabilizers were found to have the highest fracture toughness of 5.7 and 6.2 MPa·m<sup>1/2</sup>, primarily due to the relatively higher content of the elongated beta phase. While there was no obvious relationship between the thermal conductivity and the alpha SiAlON metal charge stabilizers, the values were seen to be influenced by the grain size of alpha phase where Dy-SiAlON had the lowest thermal conductivity of 5.79 W/m⋅K and Er-SiAlON showed the highest value of thermal conductivity (6.91 W/m⋅K). It was concluded that scientifically selected metal oxide charge stabilizers are beneficial in developing SiAlON ceramics with properties tailored according to specific applications.
format	article
author	Muhammad Zulqarnain Falak Bilal Anjum Ahmed Hasan Aftab Saeed Sajid Ullah Butt Abbas Saeed Hakeem Usman Ali Akbar
author_facet	Muhammad Zulqarnain Falak Bilal Anjum Ahmed Hasan Aftab Saeed Sajid Ullah Butt Abbas Saeed Hakeem Usman Ali Akbar
author_sort	Muhammad Zulqarnain Falak
title	Spark Plasma Sintering of SiAlON Ceramics Synthesized via Various Cations Charge Stabilizers and Their Effect on Thermal and Mechanical Characteristics
title_short	Spark Plasma Sintering of SiAlON Ceramics Synthesized via Various Cations Charge Stabilizers and Their Effect on Thermal and Mechanical Characteristics
title_full	Spark Plasma Sintering of SiAlON Ceramics Synthesized via Various Cations Charge Stabilizers and Their Effect on Thermal and Mechanical Characteristics
title_fullStr	Spark Plasma Sintering of SiAlON Ceramics Synthesized via Various Cations Charge Stabilizers and Their Effect on Thermal and Mechanical Characteristics
title_full_unstemmed	Spark Plasma Sintering of SiAlON Ceramics Synthesized via Various Cations Charge Stabilizers and Their Effect on Thermal and Mechanical Characteristics
title_sort	spark plasma sintering of sialon ceramics synthesized via various cations charge stabilizers and their effect on thermal and mechanical characteristics
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/4693becebb96418ea2cb03073e13c374
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Spark Plasma Sintering of SiAlON Ceramics Synthesized via Various Cations Charge Stabilizers and Their Effect on Thermal and Mechanical Characteristics

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