Microwave selective heating-enhanced reaction rates for mullite preparation from kaolinite

Zhang, Ziyuan; Qiao, Xiuchen; Yu, Jianguo

doi:10.1039/c3ra43767a

Cited by 22 publications

(17 citation statements)

References 31 publications

(28 reference statements)

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“…It was possible that alumina in albite may be little responsible for mullite formation (in this time range) because there was some of residual albite observed in the MWS sample. A similar result reported that microwave can enhance formation of mullite because a selective heating, and accelerated the nucleation and growth of mullite and changed the mullite formation route of kaolinite [33].…”

Section: Resultsmentioning

confidence: 53%

Impact of microwave processing on porcelain microstructure

Lerdprom

Zapata-Solvas

Jayaseelan

et al. 2017

Ceramics International

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Microstructural evolution on sintering of porcelain powder compacts using microwave radiation was compared with that in conventionally sintered samples. Using microwaves sintering temperature was reduced by ~ 75 °C and dwell time from 15 min to 5 min while retaining comparable physical properties i.e. apparent bulk density, water absorption to conventionally sintered porcelain. Porcelain powder absorbed microwave energy above 600 °C due to a rapid increase in its loss tangent. Mullite and glass were used as indicators of the microwave effect: mullite produced using microwaves had a nanofibre morphology with high aspect ratio (~32±3:1) believed associated with a vapour-liquid-solid (VLS) formation mechanism not previously reported. Microwaves also produced mullite with different chemistry having ~63 mol% alumina content compared to ~60 mol% alumina in conventional sintered porcelain. This was likely due to accelerated Al +3 diffusion in mullite under microwave radiation. Liquid glass was observed to form at relatively low temperature (~900-1000°C) using microwaves when compared to conventional sintering which promoted the porcelains ability to absorb them.

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Section: Resultsmentioning

confidence: 53%

Impact of microwave processing on porcelain microstructure

Lerdprom

Zapata-Solvas

Jayaseelan

et al. 2017

Ceramics International

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“…4c ).The intensified E-field was large enough to ionize air to melt copper. Based on the simulation results the same size of CFA cylinder and copper cylinder specimens were prepared and irradiated in the TE 103 single mode microwave applicator equipped with IR thermal imaging system that detects only the surface temperature of specimen 13 34 . When the specimens satisfied the E-field intensification requirements, large amount of fused phase formed in the gap of two CFA cylinder specimens ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The illustration of experimental apparatus was shown in previous investigation 34 . The waveguide (Extended Data Fig.…”

Section: Methodsmentioning

confidence: 99%

“…All the specimens were located in the center of a microwave transparent insulation carrier 34 , and then mounted at the center of cavity, where the H-field effect was negligible. During microwave irradiation, the sliding short circuit piston was first adjusted to the position with minimal output power for the best coupling and then held still for required time.…”

Section: Methodsmentioning

confidence: 99%

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The effect of electric field intensification at interparticle contacts in microwave sintering

Qiao

Xie

2016

Sci Rep

Self Cite

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The nature of microwave sintering cannot be explained in the past and has been generally called microwave effect. Here we show that the E-field intensification is the reason of microwave fast sintering of solid state inorganic compounds. The intensification degree varied with dielectric constant of compound, distance between two particles, angle between the direction of E-field and the normal to the surface at the adjacent point of two spheres. Ultra-high temperature caused by E-field intensification leads to fusing of solid materials at contact zone and enhances the mass transportation. The key to develop a microwave energy-saved sintering method is to control the distance between particles and uniformity of particles instead of the particle size.

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“…As known from XRD result, mullite, quartz and amorphous silica were the main phase of CFA. The microwave energy was adsorbed firstly by the amorphous silica due to the selective heating of microwave [19,43], since quartz is microwave transparent, and the microwave absorption capacity of amorphous silica is much better than those of mullite and Na 2 CO 3 [19,43]. …”

Section: Thermal Treatment Of Cfa-na 2 Co 3 Mixturementioning

confidence: 99%

S181 Extraction of Aluminum from Coal Fly Ash by Alkali Activation with Microwave Heating

Liu¹,

Peng²,

Zhang³

et al. 2016

JRST

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ABSTRACT:Recovering aluminum from coal fly ash (CFA) is a practical option for its value-added utilization. The alkali activation of CFA with Na 2 CO 3 was carried out using two heating methods: the conventional heating (CH) and microwave heating (MWH). Compared to CH, MWH enhanced the atomic diffusion and mass transportation in the CFA-Na 2 CO 3 mixture, accelerated the decomposition of mullite and the formation of the soluble Al-containing materials, thus greatly reducing the sintering temperature and dramatically shortening the activation reaction time. Under the moderate activation condition in MWH (700°C and 20 min), the aluminum extraction could reach 95.52% or more.

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Microwave selective heating-enhanced reaction rates for mullite preparation from kaolinite

Cited by 22 publications

References 31 publications

Impact of microwave processing on porcelain microstructure

Impact of microwave processing on porcelain microstructure

The effect of electric field intensification at interparticle contacts in microwave sintering

S181 Extraction of Aluminum from Coal Fly Ash by Alkali Activation with Microwave Heating

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