Microwave sintering of ZrO{sub 2}-12 mol% CeO{sub 2}

Janney,; Jackson, Mitchell L.; Kimrey, H.D.

doi:10.2172/10182655

Cited by 4 publications

(4 citation statements)

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“…It can be seen that the latter displayed consistently higher densification, as would be expected because of the higher fraction of vacancies in the crystal structure, and that the densification enhancement arising from the use of microwaves was also more pronounced in this higher ionic conductivity and more microwave absorbing grade of partially stabilized zirconia. These results are in good agreement with those reported by Janney et al 24 . who found that 12 mol% CeO 2 ‐doped zirconia displayed a much lower densification enhancement during microwave sintering than 8 mol% Y 2 O 3 ‐doped ZrO 2 , the latter having a higher ionic conductivity by a factor of ∼100, 25 though it should be noted that again separate microwave and conventional furnaces were used.…”

Section: Resultssupporting

confidence: 92%

Evidence for the Microwave Effect During Hybrid Sintering

Wang¹,

Binner²,

Vaidhyanathan³

et al. 2006

J American Ceramic Society

139

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A microwave/conventional hybrid furnace has been used to sinter three ceramics with different microwave absorption characteristics under pure conventional and a range of microwave/conventional hybrid heating regimes. The precursor powder particle size was also varied for each material. In each case it was ensured that every sample within a series had an identical thermal history in terms of its temperature/time profile. An increase in both the onset of densification and the final density achieved was observed with an increasing fraction of microwave energy used during sintering, the effect being greatest for the materials that absorbed microwaves most readily. Twenty‐three percent greater densification was observed for submicron zinc oxide powder, the material with the largest microwave absorption capability, when sintered using hybrid heating involving 1 kW of microwave power compared with pure conventional power under otherwise identical conditions. For the ceramic with the lowest microwave absorption characteristic, alumina, the increase in densification was extremely small; partially stabilized zirconia, a moderate microwave absorber, was intermediate between the two. Temperature gradients within the samples, a potential cause of the effect, were assessed using two different approaches and found to be too small to explain the results. Hence, it is believed that clear evidence has been found to support the existence of a genuine “microwave effect.”

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Section: Resultssupporting

confidence: 92%

Evidence for the Microwave Effect During Hybrid Sintering

Wang¹,

Binner²,

Vaidhyanathan³

et al. 2006

J American Ceramic Society

139

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show abstract

“…Finally there is a growing body of literature that suggests that sintering with microwaves results in enhanced mass transfer rates compared to conventional thermal sintering as a result of nonthermal microwave effects. Enhanced mass transfer has been observed experimentally [3][4][5][6] and postulated from theory and modeling [7][8][9][10][11]. We attribute the rapid development of high thermal conductivity in our AlN [12] and AlN-TiB 2 composites [13] to such non-thermal effects.…”

Section: Introductionmentioning

confidence: 55%

Microwave Processing of Ceramics

Lloyd

Carmel

Wilson

et al. 2006

Advances in Science and Technology

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Microwave (MW) processing is advantageous for processing ceramics with tailored microstructures. Its combination of volumetric heating, a wide range of controlled heating rates, atmosphere control and the ability to reach very high temperatures allows processing of 'difficult' materials like high thermal conductivity AlN and AlN composites and microstructure control in more readily sintered ceramics such as ZnO. MW sintering promotes development of thermal conductivity in AlN (225 W/mK) and its composites (up to 150W/mK inAlN-TiB2 and up to 129 W/mK in AlN-SiC when solid solution is avoided). In ZnO, heating rate controls sintered grain size. Increasing the heating rate from 5°C/min. to 4900°C decreases grain size from ~10 μm (comparable to conventional sintering of the same powder) to nearly the starting particle size (~ 1μm). Microstructural uniformity increases with sintering rate since ultra-rapid MW sintering minimizes the development of thermal gradients due to heat loss.

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“…Overall, the improvement in densification for fiber-reinforced HAp, sintered by microwave heating at 1100°C, was ~4-12% in comparison with the conventionally heated controls. Lower sintering temperatures and enhanced densification at a given temperature have already been reported for microwave heating of ceramics (in comparison with conventional heating) [30][31][32][33][34][35][36][37][38][39][40][41][42]. The mechanisms and reasons for the enhanced sintering of ceramics by microwave heating are attributed to the following mechanisms [43]: a) High Diffusion Rate.…”

Section: Resultsmentioning

confidence: 95%

Microwave Sintering of ZrO<sub>2</sub> Fiber-Reinforced Hydroxyapatite Matrix Composites

Ehsani

Ruys

Sorrell

2012

JBBTE

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PSZ (ZrO2Fiber)-reinforced HAp was sintered using conventional and microwave hybrid heating. Microwave heating cycles were ~50 times faster than conventional sintering cycles and enabled the use of reduced densification temperatures and soak times by as much as ~100°C and 55 min, respectively. However, although there was a significant improvement in densification levels attainable before decomposition, the improvements were insufficient to produce near-fully or fully dense samples. However, the promising gains made suggest that microwave hot pressing would be a suitable area for future work. Keywords: Hydroxyapatite, microwave sintering, fibre-reinforced ceramics, bioceramics, zirconia fibre

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Microwave sintering of ZrO{sub 2}-12 mol% CeO{sub 2}

Cited by 4 publications

References 0 publications

Evidence for the Microwave Effect During Hybrid Sintering

Evidence for the Microwave Effect During Hybrid Sintering

Microwave Processing of Ceramics

Microwave Sintering of ZrO<sub>2</sub> Fiber-Reinforced Hydroxyapatite Matrix Composites

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