Journal ArticleDOI
Grain Growth in Millimeter Wave Sintered Alumina Ceramics
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TLDR
In this paper, the millimeter wave (MMW) sintering of alumina ceramic had been performed and the results revealed that MMW sintered alumina has higher density than that of conventional method on all Sintering temperature and microstructure evaluation demonstrates that grain growth of MM wave annealed alumina is faster than in conventional annealing.Abstract:
The millimeter wave (MMW) sintering of alumina ceramic had been performed. The results revealed that MMW sintered alumina has higher density than that of conventional method on all sintering temperature. However microstructure evaluation demonstrates that grain growth of MM wave annealed alumina is faster than in conventional annealing. It indicates that MM wave enhanced mass transport and solid state reaction rates during sintering. The empirical observations of microwave enhancements have been broadly known as microwave effect. Even though no satisfactory theory existed to explain the effect but the presence the electromagnetic waves (EMW) during microwave heating is clearly the key. In this paper, microwave effect on grain growth of alumina ceramic is presented. Some effective and unique characteristics of the EMW sintering were also discussed as well.read more
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Journal ArticleDOI
Strong yellow emission of high-conductivity bulk ZnO single crystals irradiated with high-power gyrotron beam
Kosaku Kato,Hongsong Qiu,Eduard Khutoryan,Yoshinori Tatematsu,Masahiko Tani,Toshitaka Idehara,Yuusuke Yamaguchi,Masafumi Fukunari,Yuto Maeda,Kyoya Takayama,Yuki Minami,Melvin John F. Empizo,Takayuki Kurihara,Kohei Yamanoi,Toshihiko Shimizu,Keisuke Takano,Nobuhiko Sarukura,Tsuguo Fukuda,Masashi Yoshimura,Makoto Nakajima +19 more
TL;DR: In this article, the strong yellow emission of bulk ZnO single crystals irradiated with the high-power gyrotron beam was reported, with a peak of around 2'eV (600'nm) and a longer-wavelength tail.
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Development and Application of Gyrotrons at FIR UF
TL;DR: In this article, the authors present both the evolution and the current status of these radiation sources operating in a broad range from subterahertz to tera-hertz frequencies.
Journal ArticleDOI
Microwaves enhanced sintering mechanisms in alumina ceramic sintering experiments
TL;DR: Firihu et al. as mentioned in this paper analyzed microwave sintering of an oxide ceramic, a high purity -alumina, using a wide range of microwave frequencies up to sub238.
Journal ArticleDOI
Effect of initial green samples on mechanical properties of alumina ceramic
TL;DR: In this paper, the effect of initial green samples on the mechanical properties (micro hardness and fracture toughness) of alumina after sintering is considered, and the experimental results were taken from a series of investigations to study the effects of very high frequency microwave on properties of aluminina ceramics.
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Gyrotron-Based Technological Systems for Material Processing—Current Status and Prospects
TL;DR: In this article, the authors present the recent advancements and the current status of both the development of gyrotron-based technological systems and their utilization for processing of diverse advanced materials and their representative results obtained during the longstanding (more than 20 years since 1999) and fruitful collaboration between the Institute of Applied Physics of the Russian Academy of Sciences (IAP-RAS) and Research Center for Development of Far-Infrared Region, University of Fukui (FIR-UF).
References
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Journal ArticleDOI
Sintering Crystalline Solids. I. Intermediate and Final State Diffusion Models
TL;DR: In this paper, the pore and grain boundary structures in sintered powder compacts are presented to provide the basis for qualitative description of the important phases of the course of densification.
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Diffusion-Controlled Processes in Microwave-Fired Oxide Ceramics
Mark A. Janney,Hal D. Kimrey +1 more
TL;DR: In this paper, a review of the experimental work conducted at the Oak Ridge National Laboratory during the past four years on the processing of oxides in both 245 and 28 GHz microwave furnaces is presented.
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Densification and grain growth of alumina by microwave processing
TL;DR: In this paper, high pure submicron alumina powder compacts were sintered to a near theoretical density of 99.7% by 2.45 GHz microwave processing.
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Microwave heating of grain boundaries in ceramics
TL;DR: In this article, it has been suggested that enhanced sintering of ceramics by microwave heating may be the result of accelerated grainboundary diffusion caused by the grain boundaries being heated to temperatures significantly greater than the bulkspecimen temperature.
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Proposed model for the sintering of a dielectric in a microwave field
TL;DR: In this article, the authors present a model for the heating of ceramics, glasses, and composites using microwave energy and suggest some possible experiments that may be conducted to test the model.