Improvement in the Specific Strength by Arranging Closed Pores in Fully Densified Zirconia Ceramics

Kishimoto, Akira; Hanao, Masaaki; Hayashi, Hidetaka

doi:10.1002/adem.200800259

Cited by 15 publications

(12 citation statements)

References 29 publications

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“…In this simple method, few percent (generally below 10 wt%) of foaming agent was coated or mixed with the target composition, pressed and sintered for extended periods (eg, 8 hours) at elevated temperatures. While the process does not yield with highly porous samples (ϕ T was generally below 40%), yttria‐stabilized zirconia (3YSZ and 8YSZ), alumina (with superplasticity‐facilitating dispersoids; 3YSZ, 0YZ or spinel) and titania‐based closed porosity ceramics were produced . Similarly, recycled materials (eg, granite scrap and fired clay tailings) were used with SiC to cause gas generation and form closed porosity ceramic foams .…”

Section: Processing Strategiesmentioning

confidence: 99%

“…While the process does not yield with highly porous samples (ϕ T was generally below 40%), yttria-stabilized zirconia (3YSZ and 8YSZ), alumina (with superplasticity-facilitating dispersoids; 3YSZ, 0YZ or spinel) and titania-based closed porosity ceramics were produced. [72][73][74][75][76][77][78][79][80] Similarly, recycled materials (eg, granite scrap and fired clay tailings) were used with SiC to cause gas generation and form closed porosity ceramic foams. 81 In a different technique, closed porosity aluminum oxynitride (AlON) (ϕ C = 80%) foams were made by combustion synthesis in between 2165°C and 2650°C for a very short time (10 seconds).…”

Section: Chemical Blowing Agentsmentioning

confidence: 99%

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Closed porosity ceramics and glasses

2020

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In the last three decades, considerable effort has been devoted to obtain both open and closed porosity ceramics & glasses in order to benefit from unique combination of properties such as mechanical strength, thermal and chemical stability at low‐relative density. Most of these investigations were directed to the production and the analysis of the properties for open porosity materials, and regrettably quite a few compositions and manufacturing methods were documented for closed porosity ceramics & glasses in the scientific literature so far. This review focuses on the processing strategies, the properties and the applications of closed porosity ceramics & glasses with total porosity higher than 25%. The ones below such level are intentionally left out and the paper is set out to demonstrate the porous components with deliberately generated closed pores/cells. The processing strategies are categorized into five different groups, namely sacrificial templating, high‐temperature bonding of hollow structures, casting, direct foaming, and emulsions. The principles underlying these methods are given, with particular emphasis on the critical issues that affect the pore characteristics, mechanical, thermal and electrical properties of the produced components.

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Section: Processing Strategiesmentioning

confidence: 99%

Section: Chemical Blowing Agentsmentioning

confidence: 99%

Closed porosity ceramics and glasses

2020

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“…17) Moreover, the reduction in strength is minimized compared to conventional porous ceramics. 15), 18) Since this method requires superplasticity with a proper deformation rate and limit, highly porous ceramics cannot be fabricated using commercial alumina powder without an additive. Therefore, we added 3 mol % yttria-stabilized zirconia (3YSZ) to facilitate the superplasticity of the alumina.…”

Section: )9)mentioning

confidence: 99%

Alumina based low permittivity substrate utilizing superplastically foaming method

Wakiyama

Hayashi

Kishimoto

2010

J. Ceram. Soc. Japan

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Alumina based closed pore dominated substrates have been fabricated by using superplastically foaming method developed by our group. Co-dispersing of magnesium aluminate spinel (Spinel) and zirconia without dopant (0YZ) provided adequate superplastisity to alumina matrix, while individual dispersion of spinel or zirconia resulted in only small deformation. The dielectric constant of superplastically foamed alumina decreased monotonically with porosity. Introduced pores were all closed nature at least up to 30% of porosity, at that porosity the permittivity became half as that of full dense one. Effect of the sweating water or ambient humidity has been proved to be identical to those of full dense one, which is favorable for semiconductor substrate.

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“…Furthermore, the fully densified matrix should give rise to favorable mechanical properties. 21) With the aim of fabricating a high-frequency dielectric substrate, we investigated methods to fabricate a porous aluminabased substrate containing only closed pores, insensitive to ambient humidity. We also conducted preliminary examination of the material's mechanical strength.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of closed-pore inclusive low-permittivity substrates insensitive to ambient humidity

Wakiyama

Waku

Hayashi

et al. 2009

J. Ceram. Soc. Japan

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With the aim to reduce the permittivity of a dielectric substrate, closed pores have been introduced into alumina based ceramics by our innovated superplastisically foaming method. Affect of the ambient humidity on the dielectric constant was compared to those for conventional porous ceramics as well as full densified one. In the dry atmosphere, the dielectric constant (k) decreased with the porosity similar to the conventional porous ceramics. Affect of the ambient humidity on the dielectric property was almost identical to that of fully densified one. The degradation of mechanical strength depended on the pore size introduced.

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Improvement in the Specific Strength by Arranging Closed Pores in Fully Densified Zirconia Ceramics

Cited by 15 publications

References 29 publications

Closed porosity ceramics and glasses

Closed porosity ceramics and glasses

Alumina based low permittivity substrate utilizing superplastically foaming method

Fabrication of closed-pore inclusive low-permittivity substrates insensitive to ambient humidity

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