Microwave Penetration Depth in Materials with Non-zero Magnetic Susceptibility

Peng, Zhiwei; Hwang, Jiann‐Yang; Mouris, Joe; Hutcheon, R. M.; Huang, Xiaodi

doi:10.2355/isijinternational.50.1590

Cited by 135 publications

(66 citation statements)

References 30 publications

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“…8) The main components of the measurement system include a resistive heating furnace and a cylindrical TM0n0 resonant mode cavity. The system measures the differences (frequency shift and change of quality factors) in the microwave cavity response between a cavity with an empty sample-holder and the same cavity with a sample-holder plus the sample at each specified temperature.…”

Section: Methodsmentioning

confidence: 99%

“…The details about this technique and apparatus used for the measurements can be found in the published literature. 8,9) As for the permittivity test, Fe2O3 powders were first uniaxially pressed at ~207 MPa in a die lined with tungsten carbide to form pellets with a diameter of ~3.62 mm having a total stacked length (height) of 12.97 mm. The bulk density (room temperature) of the sample was 2.79 g cm -3 .…”

Section: Methodsmentioning

confidence: 99%

“…[5][6][7] Peng et al investigated the effect of temperature on the microwave absorption capabilities of magnetite concentrate and ferrous oxide (Fe0.925O) covering a broad range from room temperature to above 1 000°C through the permittivity and permeability measurements using the cavity perturbation technique. 8,9) These studies showed that the investigated parameters closely depend upon microwave frequency and temperature. Meanwhile, the effect of temperature is comparatively stronger than that of frequency for iron oxides, especially above 500°C.…”

Section: Introductionmentioning

confidence: 95%

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Microwave Permittivity, Permeability, and Absorption Capability of Ferric Oxide

et al. 2012

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The permittivity and permeability measurements of ferric oxide (Fe2O3) were carried out over a broad temperature range from 24°C to above 1 000°C at 915 and 2 450 MHz. The real part and imaginary part of complex relative permittivity (εr' and εr") of ferric oxide slightly increase with temperature below 450°C, above which εr' increases significantly while εr" presents a broad dielectric loss peak between 450 and 1 000°C. Contrary to εr' and εr", the real part and imaginary part of complex relative permeability (μr' and μr") remain relatively invariable (1 and 0, respectively) until 700°C. The μr' values subsequently exhibit a decreasing tendency due to the increased electrical conductivity at higher temperatures while the μr" values stay negligible as temperature increases. The results demonstrate that the dielectric loss is the primary factor contributing to microwave absorption of Fe2O3. The calculation of microwave penetration depth shows that Fe2O3 undergoes a transition from a microwave transparent material to a good microwave absorber with increasing temperature.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

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Microwave Permittivity, Permeability, and Absorption Capability of Ferric Oxide

et al. 2012

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“…The loss tangent indicates absorption of MW for the MW frequency; a minimal difference between the mixture and filtered water exist. Considering that the electrical property of dry soil is ε r ′: 2.55 and the loss tangent is 0.034 measured by the cavity perturbation method [6,19], the absorption of water is dominant in the deposited sand because the filtered water is the same as the deposited sand in terms of the loss tangent. Their absorption probably decreases with temperature increasing considering that the loss tangent of water indicates the same tendency [21].…”

Section: Resultsmentioning

confidence: 99%

Water Vaporization from Deposited Sand by Microwave Cavity Resonator

Yokawa¹,

Mutou²,

Tsubaki³

et al. 2017

J Civil Environ Eng

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In this study, water-soil moisture heating behavior, water vapor rates, and the effect of soil-aggregating agent permittivity under a 2.45-GHz microwave cavity resonator were investigated. The conducted experiments indicated different orders of magnitude than the drying furnace process in the water evaporation rate; moreover, the water vapor rate increased in accordance with the microwave power. The microwave absorption properties indicated that microwave selectively heated water into vaporized moisture, and the vaporization conformed to an energy balance between water evaporative latent heat and microwave power. Furthermore, soil-aggregating agents showed minimal effects on the vapor rate at low microwave power, whereas sand deposited with an aggregating agent indicated a higher vapor rate than that without an agent at a high microwave power. When sufficient energy was supplied to moisture, water transfer was dominant in the vaporization process. In this case, the soil-aggregating agents significantly affected the efficiency of the vaporization process.

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“…It is one of the most important parameters of the microwave heating [14,15] described by the following equation [16]:…”

Section: Microwave Heatingmentioning

confidence: 99%

The Impact of Microwave Penetration Depth on the Process of Heating the Moulding Sand with Sodium Silicate

Nowak¹

2017

Archives of Foundry Engineering

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This paper presents the impact of microwave penetration depth on the process of heating the moulding sand with sodium silicate. For each material it is affected by: the wavelength in vacuum and the real and imaginary components of the relative complex electrical permittivity ε r for a selected measurement frequency. Since the components are not constant values and they change depending on the electrical parameters of materials and the frequency of the electromagnetic wave, it is indispensable to carry out laboratory measurements to determine them. Moreover, the electrical parameters of materials are also affected by: temperature, packing degree, humidity and conductivity. The measurements of the dielectric properties of moulding sand with sodium silicate was carried out using the perturbation method on a stand of waveguide resonance cavity. The real and imaginary components of the relative complex electrical permittivity was determined for moulding sand at various contents of sodium silicate and at various packing degrees of the samples. On the basis of the results the microwave penetration depth of moulding sand with sodium silicate was established. Relative literature contains no such data that would be essential to predicting an effective process of microwave heating of moulding sand with sodium silicate. Both the packing degree and the amount of sodium silicate in moulding sand turned out to affect the penetration depth, which directly translates into microwave power density distribution in the process of microwave heating of moulding sand with sodium silicate.

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Microwave Penetration Depth in Materials with Non-zero Magnetic Susceptibility

Cited by 135 publications

References 30 publications

Microwave Permittivity, Permeability, and Absorption Capability of Ferric Oxide

Microwave Permittivity, Permeability, and Absorption Capability of Ferric Oxide

Water Vaporization from Deposited Sand by Microwave Cavity Resonator

The Impact of Microwave Penetration Depth on the Process of Heating the Moulding Sand with Sodium Silicate

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