Optically transparent gamma-aluminum oxynitride powders and ceramic articles shaped therefrom
AssigneeElf Atochem S.A.
InventorsRoland Bachelard, Jean-Pierre Disson, Bruno Morlhon
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Abstract
Gamma-aluminum oxynitride ground powders, white in color and well suited for conversion into optically transparent ceramic shaped articles, 100% of the particles of which being less than 10 .mu.m in size and exhibiting a transmittance of at least 8%, are prepared by grinding particulate gamma-aluminum oxynitride agglomerates having a porosity of greater than 75%, such agglomerates themselves being produced by interreacting dry powdery admixture of aluminum nitride, alpha-alumina, and an alumina of high specific surface area or precursor thereof.
Claims26
In a process for the preparation of particulate gamma-aluminum oxynitride agglomerates, comprising reacting aluminum nitride with alpha-alumina, wherein the improvement comprises using a grinding facilitating amount of alumina of high specific surface area, or precursor thereof, in the reacting step to produce particulate gamma-aluminum oxynitride agglomerates suitable for conversion into optically transparent ceramic shaped articles.
In a process for the preparation of a gamma-aluminum oxynitride ground powder, comprising interreacting a dry powdery admixture of aluminum nitride with alpha-alumina, wherein the improvement comprises using a grinding facilitating amount of alumina of high specific surface area or precursor thereof, in the admixture, and grinding the powder thus obtained, to produce gamma-aluminum oxynitride ground powder suitable for conversion into optically transparent ceramic shaped articles.
Particulate gamma-aluminum oxynitride agglomerates, white in color, having a porosity of greater than 75%.
Gamma-aluminum oxynitride ground powder, white in color, 100% of the particles of which being less than 10 .mu.m in size and exhibiting a transmittance of at least 8% measured at 2,500 cm.sup.-1 on a KBr disc 0.9 mm in thickness and containing 3.33% of gamma-aluminum oxynitride.
Dependencies are inferred from the claim text.