Sintering of α-Al2O3-seeded nanocrystalline γ-Al2O3 powders

Nordahl, Christopher S.; Messing, Gary L.

doi:10.1016/s0955-2219(01)00285-0

Cited by 94 publications

(48 citation statements)

References 22 publications

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“…1 On the other hand, the PA-S-Ca(800) powders, which were calcined at 800ºC and have a comparable α-alumina fraction, sintered to >99% relative density at 1400ºC. This suggests that the PA-S-Ca powders have higher sinterability than the commercial δ/α-alumina powder because the α-alumina nanoparticles in the former case was finer.…”

Section: Fabrication Of Fine-grained Alumina Ceramicsmentioning

confidence: 99%

Densification of Ca-doped alumina nanopowders prepared by a new sol–gel route with seeding

Odaka

Yamaguchi

Fujita³

et al. 2008

Journal of the European Ceramic Society

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This paper demonstrates that the Ca-doped alumina nanopowders prepared by a new sol-gel route using polyhydoxoaluminum (PHA) and CaCl 2 solutions under α-alumina seeding represent a viable option for producing fine-grained ceramics. Appropriate conditions for producing Ca-doped alumina nanopowders suitable for low-temperature finer-grained densification were 0.10 mol% Ca-doping, 5 mass% α-alumina seeding and a calcination temperature of 900˚C. These conditions led to the formation of new nano-sized alumina powders, which consisted of ~80 nm α-alumina particles and γ-alumina nanoparticles. Using these Ca-doped nanopowders, fully densified alumina ceramics with a uniform microstructure composed of fine grains with an average grain size of 0.66 μm could be obtained at 1375˚C.Clearly, the Ca-doped nanopowders obtained here through the proposed sol-gel route are very suitable for fabricating dense, fine-grained alumina ceramics because an undoped sample with 5 mass% seeds led to a microstructure with an average grain size of 1.39 μm at 1375˚C.

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Section: Fabrication Of Fine-grained Alumina Ceramicsmentioning

confidence: 99%

Densification of Ca-doped alumina nanopowders prepared by a new sol–gel route with seeding

Odaka

Yamaguchi

Fujita³

et al. 2008

Journal of the European Ceramic Society

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“…Meanwhile, the compound effect of pressure and filtration in PFMS process constrained the shrinkage of coating in three-dimensional directions and thus micro-cracks were avoided as well as the adherence for composite coating was improved. Furthermore, nano sized a-Al 2 O 3 can decrease the phase transition and crystallization temperature of aluminium oxide sol [21,22] whilst the microwave energy can also lower the phase transformation temperature needed to form a-Al 2 O 3 [23].…”

Section: Discussionmentioning

confidence: 99%

Al2O3/YSZ Composite Coatings Prepared by a Novel Sol–Gel Process and Their High-Temperature Oxidation Resistance

Ren

Wang

2010

Oxid Met

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In this study, a novel sol-gel process has been utilized to fabricate Al 2 O 3 /YSZ (6 wt% yttria partially stabilized zirconia) composite coatings on Ni-based superalloy. The green coatings were obtained by electrophoretic deposition (EPD) in a suspension containing aluminium oxide sol, nano-Al 2 O 3 and micro-YSZ particles, and then treated by so-called pressure filtration microwave sintering (PFMS) process. The as-sintered composite coatings were dense, uniform and crack-free and the phases mainly present a-Al 2 O 3 , m-ZrO 2 and t-ZrO 2 as aluminium oxide sol content decreasing. The cyclic oxidation tests at 1000°C for 200 h demonstrate that both of high-temperature oxidation and spallation resistance for the coated samples were remarkably improved. These beneficial effects could be attributed to the special microstructure that micro-YSZ particles embedded in nano/ submicron Al 2 O 3 matrix. Meanwhile, the mechanisms of the inhibition of the oxygen diffusion and thermal match are further discussed.

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“…11), 12) In order to lower the sintering temperature of Al 2 ceramics and the derived samples sintered at 1350°C had good dielectric properties of ¾ r = 11.6 and Q © f = 11,456 GHz. 15) Huang and co-workers found that nanoparticles can also reduce the sintering temperature significantly and also promote the Q © f value of ¡-Al 2 O 3 ceramics to 500,000 GHz.…”

Section: ¹5mentioning

confidence: 99%

Sintering behavior and dielectric properties of Al2O3 ceramics with CaMgSi2O6 addition

Wang

Feng

Yang

et al. 2012

J. Ceram. Soc. Japan

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Sintering of α-Al2O3-seeded nanocrystalline γ-Al2O3 powders

Cited by 94 publications

References 22 publications

Densification of Ca-doped alumina nanopowders prepared by a new sol–gel route with seeding

Densification of Ca-doped alumina nanopowders prepared by a new sol–gel route with seeding

Al2O3/YSZ Composite Coatings Prepared by a Novel Sol–Gel Process and Their High-Temperature Oxidation Resistance

Sintering behavior and dielectric properties of Al<sub>2</sub>O<sub>3</sub> ceramics with CaMgSi<sub>2</sub>O<sub>6</sub> addition

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