Zone-specific temperature distribution, densification trajectory and grain-growth kinetics of microwave-hybrid-sintered and conventionally sintered Al<sub>2</sub>O<sub>3</sub> slip casts

Khalid, Muhammad Waqas; Kim, Young Il; Haq, Muhammad Aneeq; Kim, InYeong; Lee, Dongju; Kim, Bum Sung; Lee, Bin

doi:10.1080/21870764.2022.2049997

Cited by 3 publications

(5 citation statements)

References 47 publications

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“…In another work, Khalid et al 17 . mentioned an estimated activation energy of 134.60 ± 1.4 kJ/mol for grain growth in conventionally sintered Al 2 O 3 slip cast, whereas an estimated activation energy of 106.15 ± 0.7 kJ/mol was calculated for grain growth in microwave‐hybrid‐sintered Al 2 O 3 slip cast.…”

Section: Resultsmentioning

confidence: 99%

“…In the presence of a susceptor material, such as SiC used in this work, the sample heats up from the surface by absorbing heat from the susceptor, relatively flattening the parabolic temperature‐distribution curve along the sample. Hence, the temperature difference between the surface and center is significantly reduced 17,48 . It is suggested that a low heating rate with 1 h holding at the sintering temperature helped in relatively homogenizing the microstructure and densification at the center and surface of the sample.…”

Section: Resultsmentioning

confidence: 99%

“…In another work, Khalid et al 17 mentioned an estimated activation energy of 134.60 ± 1.4 kJ/mol for grain growth in conventionally sintered Al 2 O 3 slip cast, whereas an estimated activation energy of 106.15 ± 0.7 kJ/mol was calculated for grain growth in microwave-hybrid-sintered Al 2 O 3 slip cast. Similarly, they calculated an estimated grain-growth rate of (18.75 ± 0.11) × 10 −21 m 3 /s for the conventionally sintered Al 2 O 3 slip cast, whereas the graingrowth rate increased to (49.77 ± 0.13) × 10 −21 m 3 /s when the sample was sintered with microwaves.…”

Section: F I G U R E 6 X-ray Diffraction (Xrd) Analysis Of (A) Cs a (...mentioning

confidence: 99%

“…surface and center is significantly reduced. 17,48 It is suggested that a low heating rate with 1 h holding at the sintering temperature helped in relatively homogenizing the microstructure and densification at the center and surface of the sample. Additionally, it is suggested that hybrid heating reduced the temperature gradients, further homogenizing the microstructure throughout the sample.…”

Section: F I G U R E 6 X-ray Diffraction (Xrd) Analysis Of (A) Cs a (...mentioning

confidence: 99%

“…Microwave hybrid sintering, another sintering method used to consolidate ceramic green bodies, has previously been seen as an alternative to the conventional sintering of Al 2 O 3 and Al 2 O 3 /ZrO 2 with lower energy and time consumption and temperature shifts toward lower readings. [17][18][19][20] However, no significant research has been conducted on the microwave hybrid sintering of green Al 2 O 3 and Al 2 O 3 /ZrO 2 tape casts. Therefore, it is necessary to investigate whether microwave hybrid sintering can enhance the mechanical properties of Al 2 O 3 and Al 2 O 3 /ZrO 2 laminated structures.…”

Section: Introductionmentioning

confidence: 99%

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Microwave hybrid and conventional sintering of Al₂O₃ and Al₂O₃/ZrO₂ multilayers fabricated by aqueous tape casting

et al. 2023

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In this study, microwave hybrid sintering and conventional sintering of Al2O3‐ and Al2O3/ZrO2‐laminated structures fabricated via aqueous tape casting were investigated. A combination of process temperature control rings and thermocouples was used to measure the sample surface temperatures more accurately. Microwave hybrid sintering caused higher densification and resulted in higher hardness in Al2O3 and Al2O3/ZrO2 than in their conventionally sintered counterparts. The flexural strength of microwave‐hybrid‐sintered Al2O3/ZrO2 was 70.9% higher than that of the conventionally sintered composite, despite a lower sintering temperature. The fracture toughness of the microwave‐hybrid‐sintered Al2O3 increased remarkably by 107.8% despite a decrease in the relative density when only 3 wt.% t‐ZrO2 was added. The fracture toughness of the microwave‐hybrid‐sintered Al2O3/ZrO2 was significantly higher (247.7%) than that of the conventionally sintered composite. A higher particle coordination and voids elimination due to the tape casting and the lamination processes, the microwave effect, the stress‐induced martensitic phase transformation, and the grain refinement phenomenon are regarded as the main reasons for the mentioned outcomes.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: F I G U R E 6 X-ray Diffraction (Xrd) Analysis Of (A) Cs a (...mentioning

confidence: 99%

Section: F I G U R E 6 X-ray Diffraction (Xrd) Analysis Of (A) Cs a (...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Microwave hybrid and conventional sintering of Al₂O₃ and Al₂O₃/ZrO₂ multilayers fabricated by aqueous tape casting

et al. 2023

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Magnetic Supraparticles Capable of Recording High‐Temperature Events

Wolf,

Sauer,

Hurle

et al. 2024

Adv Funct Materials

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Superparamagnetic iron oxide nanoparticles (SPIONs) are prone to oxidation at elevated temperatures (>300 °C) and lose their magnetizability upon transition from magnetite/maghemite (γ‐Fe2O3 / Fe3O4) to hematite (α‐Fe2O3). Silica (SiO2) shells can effectively prevent this undesired effect up to ≈1000 °C. Herein, the study shows how to utilize SPIONs with varying SiO2 shell thickness and thus, different oxidation susceptibility, and how to combine them in micrometers sized assemblies – so‐called supraparticles (SPs), to create a structurally emerging magnetic temperature recording functionality. The desired oxidation of non or weakly‐protected SPIONs within SPs upon temperature events reduces dipole–dipole interactions of well‐protected SPIONs in the confined SP entity. The resulting change of magnetic interactions therefore contains information on the thermal history of the SP, which can be spectrally read out via magnetic particle spectroscopy within seconds. Their working range can be tuned from 400 to 1000 °C on two independent structural hierarchy levels, namely the SiO2 shell thickness and the freely selectable ratios of different building blocks in the SP. The application of such SPs as particulate additives for magnetic recording of high‐temperature events, especially relevant in metal, alloy, and ceramic processing, representing a yet unexplored and optically‐independent option for bulk temperature recording is proposed.

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Sintering behavior of alumina by microwave hybrid sintering

Waqas,

Lee

2024

Ceramist

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Microwave sintering is considered an ideal sintering process due to its rapid heating rate, low energy consumption, and uniform temperature distribution between the interior and surface. However, the difficulty of using a dilatometer and the lack of systematic research have hindered the investigation of activation energy and grain growth kinetics during microwave sintering. In this study, we examined the internal heating mechanism of microwave hybrid sintering, its sintering behavior, and its applicability to commercial processes such as tape casting. The results demonstrated that microwave hybrid sintering reduces the activation energy for both shrinkage and grain growth, confirming the presence of the "microwave effect." This study underscores the potential of microwave hybrid sintering for commercial applications, especially for large ceramic components.

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Zone-specific temperature distribution, densification trajectory and grain-growth kinetics of microwave-hybrid-sintered and conventionally sintered Al₂O₃ slip casts

Cited by 3 publications

References 47 publications

Microwave hybrid and conventional sintering of Al₂O₃ and Al₂O₃/ZrO₂ multilayers fabricated by aqueous tape casting

Microwave hybrid and conventional sintering of Al₂O₃ and Al₂O₃/ZrO₂ multilayers fabricated by aqueous tape casting

Magnetic Supraparticles Capable of Recording High‐Temperature Events

Sintering behavior of alumina by microwave hybrid sintering

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Zone-specific temperature distribution, densification trajectory and grain-growth kinetics of microwave-hybrid-sintered and conventionally sintered Al2O3 slip casts

Cited by 3 publications

References 47 publications

Microwave hybrid and conventional sintering of Al2O3 and Al2O3/ZrO2 multilayers fabricated by aqueous tape casting

Microwave hybrid and conventional sintering of Al2O3 and Al2O3/ZrO2 multilayers fabricated by aqueous tape casting

Magnetic Supraparticles Capable of Recording High‐Temperature Events

Sintering behavior of alumina by microwave hybrid sintering

Contact Info

Product

Resources

About

Zone-specific temperature distribution, densification trajectory and grain-growth kinetics of microwave-hybrid-sintered and conventionally sintered Al₂O₃ slip casts

Microwave hybrid and conventional sintering of Al₂O₃ and Al₂O₃/ZrO₂ multilayers fabricated by aqueous tape casting

Microwave hybrid and conventional sintering of Al₂O₃ and Al₂O₃/ZrO₂ multilayers fabricated by aqueous tape casting