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AssigneesKoninklijke Philips Electronics N.V., Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
InventorsMichel Paul Barbara Van Bruggen, Rolf Theo Anton Apetz, Theo Arnold Kop, Andreas Krell, Thomas Hutzler
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The present invention relates to highly dense translucent and transparent aluminium oxide components for applications, e.g. in the lighting industry, where a fine crystal size has to be obtained and stabilized for use at temperatures of 800° C. or more. Disclosed are high-strength polycrystalline alumina products which include 0.001-0.5 weight-% ZrO2 stabilizing a fine crystal size <2 μm or, preferably, <1 μm if used at temperatures of 800° C. or more. The microstructure exhibits an extremely high relative density enabling a high real in-line transmission >30% measured over an angular aperture of at most 0.5° at a sample thickness of 0.8 mm and with a monochromatic wavelength of light λ, preferably, of 645 nm.
Polycrystalline alumina components optionally containing MgO in a concentration of at most 0.3 wt-%, wherein the alumina contains a concentration from 0.1 to 0.5 wt-% inclusive ZrO2 as an additive and has an average crystal size ≦2μm, a relative density higher than 99.95%, with a real in-line transmission RIT ≧30% measured over an angular aperture of at most 0.5° at a sample thickness of 0.8 mm and with a monochromatic wavelength of light λ, and wherein the ZrO2 additive has an average particle size of at most 100 nm.
Polycrystalline alumina components comprising alumina which contains ZrO2 in a concentration between 0.1 to 0.5 wt-% inclusive as an additive, wherein the alumina has an average crystal size ≦2 μm, and has a relative density higher than 99.95%, and wherein the additive has an average particle size of at most 100 nm.
Dependencies are inferred from the claim text.