Transparent hot-pressed alumina

Peelen, J.G.J.

doi:10.1016/0390-5519(79)90032-2

Cited by 13 publications

(2 citation statements)

References 17 publications

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“…Increasing the bulk density and reducing the grain size in the alumina ceramics improve not only their mechanical properties such as hardness, 1,2 wear resistance 3,4 and fracture strength 5 but also the transmittance of visible light. [6][7][8][9][10][11][12][13][14][15][16] Most of the efforts are using a simultaneous pressure application during sintering such as hot pressing, 1,[17][18][19] hot isostatic pressing 5,12,16,20 or pulsed electric current sintering (PECS). [6][7][8][9][10][11]21,22,23,24 Transparent Al 2 O 3 polycrystals are promising candidates for such applications as electromagnetic windows, electronic components, transparent armour, jewellery and envelope of high pressure metal halide lamps.…”

Section: Introductionmentioning

confidence: 99%

“…[6][7][8][9][10][11]21,22,23,24 Transparent Al 2 O 3 polycrystals are promising candidates for such applications as electromagnetic windows, electronic components, transparent armour, jewellery and envelope of high pressure metal halide lamps. 25 Fine grained transparent Al 2 O 3 polycrystals have attracted much attention 2,[6][7][8][9][10][11][12][13][14][15][16][17][18][19]20,22,24,[26][27][28][29][30][31][32][33][34] due to their superior optical properties and excellent mechanical properties, even at high temperatures. These ceramics are prepared by pressure sintering techniques at low temperatures ranging from 1150 to 1400uC.…”

Section: Introductionmentioning

confidence: 99%

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Two-step pulsed electric current sintering of transparent Al₂O₃ceramics

Nanko¹,

Dang²

2013

Advances in Applied Ceramics

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Fully densified Al 2 O 3 ceramics with fine grain size were obtained by pulsed electric current sintering through a two-step heating profile (referred to as TS-PECS). Highly transparent Al 2 O 3 polycrystals with fine grain size (400 nm) were successfully fabricated by the TS-PECS process, namely, sintering at 1000uC for 1 h and followed at 1200uC for 20 min under uniaxial pressure of 100 MPa. Effects of the first step temperature and heating rate were discussed for bulk density, grain size and transparency. The temperature in the first step strongly affects densification and grain growth of Al 2 O 3 . On the other hand, heating rate, even of 100 K min 21 , in TS-PECS does not give significant influences on densification and grain growth of Al 2 O 3 . Inline transmittance at 640 nm in wavelength normalised to 1 mm in thickness is increased by decreasing heating rate even in TS-PECS.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Two-step pulsed electric current sintering of transparent Al₂O₃ceramics

Nanko¹,

Dang²

2013

Advances in Applied Ceramics

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Preparation of High-Purity Glasses and Advanced Ceramics Via EPD of Nanopowders

Clasen

2011

Nanostructure Science and Technology

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For the preparation of advanced materials via a powder technological route the shaping process is most important after the synthesis of the powder. Therefore high production rates and the formation of a homogeneous compact are generally desirable. Furthermore, a high green density is necessary to reduce shrinkage during drying and sintering. This is of special importance for near net shaping or microstructuring. For coatings an even thickness with a good coverage of the edges is an additional specification that has to be fulfilled. The typical shaping processes for fine or advanced ceramics with particle sizes in the µm or even sub-µm region are slip casting, forming of high-viscous masses, and dry pressing. The decreasing of particles size leads to the area of nanoparticles with sizes less than 100 nm. These nanopowders show higher sintering activity leading to a decrease of sintering temperature. Thus smaller final grain sizes can be achieved or even quantum size effects can be observed. For glasses new perspectives are opened with nanopowders. Due to the reduction of processing temperatures nanosized glass powders can be completely sintered to transparent glasses via viscous flow below the crystallization temperature. Thus no crucibles are needed any more and high-purity glasses can be prepared. For coatings on substrates with limited temperature stability glazes and enamels can be applied without additional low melting components. Theses fluxes generally reduce the chemical stability of the coating.As these nanopowders tend to aggregate due to the increased influence of van der Waals attraction forces, these nanopowders have to be dispersed perfectly. For that suspensions are most suited and the formation of aerosols (dust of nanopowders) is prevented, which might be hazardous. In electrostatically stabilized suspensions the dispersed particles show a surface charge, which can be directly used for moving this particles in an applied external electric field leading to an electrophoretic deposition (EPD) [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. But it should be kept in mind that the electrostatical as well as

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