High Temperature Thermal Insulation System for Millimeter Wave Sintering of B4C

Hoshizuki, H.; Mitsudo, S.; Saji, T.; Matsuura, Kiyotaka; Idehara, T.; Glyavin, M. Yu.; Eremeev, A. G.; Honda, Toru; Iwai, Yoshiro; Nishi, Hiroshi; Kitano, Akihiro; Ishibashi, J.

doi:10.1007/s10762-005-0030-z

Cited by 26 publications

(13 citation statements)

References 5 publications

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“…Additionally, the time evolution of the density, porosity, and the crystallization of silica aerogel observed in the microwave process is similar to the one observed in the conventional process [9], but during the microwave treatment, this evolution occurs at temperatures approximately 200°C lower. A successful use of millimeter wave heating to sinter materials such as boron carbide [10,11], alumina [12], and silicon nitride [13,14] has been reported recently. It has been found that the irradiation by millimeter waves enables very high heating rates to be achieved and reduces the time for grain growth.…”

Section: Introductionmentioning

confidence: 99%

Rapid Sintering of Silica Xerogel Ceramic Derived from Sago Waste Ash Using Sub-millimeter Wave Heating with a 300 GHz CW Gyrotron

Aripin

Mitsudo

Sudiana

et al. 2011

J Infrared Milli Terahz Waves

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In this paper, we present and discuss experimental results from a microwave sintering of a silica-glass ceramic, produced from a silica xerogel extracted from a sago waste ash. As a radiation source for the microwave heating a sub-millimeter wave gyrotron (Gyrotron FU CW I) with an output frequency of 300 GHz has been used. The powders of silica xerogel have been dry pressed and then sintered at temperatures ranging from 300°C to 1500°C. The influence of the sintering temperature on the technological properties such as porosity and bulk density was studied in detail. Furthermore, X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy have been used in order to study the structure of the produced silica glass-ceramics. It has been found that the silica xerogel crystallizes at a temperature of 800°C, which is about 200°C lower than the one observed in the conventional process. The silica xerogel samples sintered by their irradiation with a sub-millimeter wave at 900°C for 18 minutes are fully crystallized into a silica glassceramic with a density of about 2.2 g/cm 3 and cristobalite as a major crystalline phase. The results obtained in this study allow one to conclude that the microwave sintering with sub-millimeter waves is an appropriate technological process for production of silica glass-ceramics from a silica xerogel and is characterized with such advantages as shorter times of the thermal cycle, lower sintering temperatures and higher quality of the final product.

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Section: Introductionmentioning

confidence: 99%

Rapid Sintering of Silica Xerogel Ceramic Derived from Sago Waste Ash Using Sub-millimeter Wave Heating with a 300 GHz CW Gyrotron

Aripin

Mitsudo

Sudiana

et al. 2011

J Infrared Milli Terahz Waves

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“…The same requirement is imposed also by many other technologies that utilize gyrotrons as sources of powerful sub-THz and THz waves, for example, materials treatment (e.g. sintering of advanced ceramics, development of new functional materials) [23]- [25], biological and medical applications [26]- [28], just to name a few. Additional features demanded by some of the above-mentioned applications are frequency and amplitude modulation and stabilization, as well as frequency tunability.…”

Section: Introductionmentioning

confidence: 99%

High Purity Mode CW Gyrotron Covering the Subterahertz to Terahertz Range Using a 20 T Superconducting Magnet

Idehara

Ogawa

Wágner

et al. 2018

IEEE Trans. Electron Devices

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Abstract-In this paper, we present the current status and both the ongoing investigation and the continuous improvements to the operational performance of a unique gyrotron, which is built using a 20 T superconducting magnet and holds a world record of 10 W THz wave generation at the highest frequency (1.08 THz) in continuous wave (CW) operation. Additionally, it has demonstrated highpurity single-mode generation on a sequence of modes that cover a wide range from sub-THz to THz frequencies at both fundamental and second-harmonic resonances of the electron cyclotron frequency. As an illustration, the measurements of the observed radiation patterns of eight output modes radiated from a currently used resonant cavity with a linear up-taper are presented and compared with the corresponding patterns simulated by scattering matrix calculations. A new design of an optimized cavity with a nonlinear up-taper, which improves further the mode purity of the generated output radiation has been proposed and is currently being implemented as a replacement of the existing resonator. The overall operational performance and the output characteristics of this gyrotron (called FU CW III in accordance with the nomenclature adopted at FIR UF Center) make it a versatile and appropriate source of coherent CW radiation for many novel applications in the fields of high-power THz science and technologies.

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“…The 30 GHz processing has high potential application in the field of thermal barrier coating, joining of high temperature superconductor ceramic coatings to metal substrates, surface transient heating of metal alloys, heating of powdered metal, etc. [3][4][5][6]. Reduction of the sintering time with higher heating rate in 30 GHz processing reduces grain growth in the joint zone with higher mechanical strength of the joint [7].…”

Section: Introductionmentioning

confidence: 99%

“…The growing interest in the nanostructured materials for their great potential for various applications has also made 30 GHz sintering a very important area of study [4,8]. A successful use of millimetre wave heating to sinter materials, such as boron carbide, alumina, silicon nitride, zinc oxide, and copper powder, has been reported [5,9]. However, most of the reported studies do not provide detailed explanation of the observed heating patterns of metal powders, and there is also not much information available to interpret the mechanism of microwave hearting of these powders.…”

Section: Introductionmentioning

confidence: 99%

Multiphysics Model of Iron Powder Compacts for Efficient Microwave Processing

Devi¹,

Akhtar²,

Datta³

2017

PIER M

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Abstract-A generalized multiphysics model using COMSOL Multiphysics software for optimizing the sintering process of iron powders having various green densities is developed. The modeling is facilitated by designing a 30 GHz multimode applicator, where the test sample is placed for the microwave processing. The effective dielectric and magnetic properties of the resultant metal powder compact is estimated using the effective electromagnetic model considering the idea of core-shell particle approach followed by the Lichtenecker's mixture formula. A theoretical approach relating the penetration depth, proper impedance matching and volume fraction of different density powder compacts is also discussed here. From the study, it is clear that the effective dielectric and magnetic properties contribute to the microwave sintering process of metal powders.

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High Temperature Thermal Insulation System for Millimeter Wave Sintering of B4C

Cited by 26 publications

References 5 publications

Rapid Sintering of Silica Xerogel Ceramic Derived from Sago Waste Ash Using Sub-millimeter Wave Heating with a 300 GHz CW Gyrotron

Rapid Sintering of Silica Xerogel Ceramic Derived from Sago Waste Ash Using Sub-millimeter Wave Heating with a 300 GHz CW Gyrotron

High Purity Mode CW Gyrotron Covering the Subterahertz to Terahertz Range Using a 20 T Superconducting Magnet

Multiphysics Model of Iron Powder Compacts for Efficient Microwave Processing

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