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AssigneeRaytheon Company
InventorsThomas M. Hartnett, Richard L. Gentilman, Edward A. Maguire
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A method of preparing substantially homogeneous aluminum oxynitride powder is provided comprising the steps of reacting gamma aluminum oxide with carbon in the presence of nitrogen, and breaking down the resulting powder into particles in a predetermined size range. A method of preparing a durable optically transparent body from this powder is also provided comprising the steps of forming a green body of substantially homogeneous cubic aluminum oxynitride powder and sintering said green body in a nitrogen atmosphere and in the presence of predetermined additives which enhance the sintering process. Preferred additives are boron, in elemental or compound form, and at least one additional element selected from the group of yttrium and lanthanum or compounds thereof. The sintered polycrystalline cubic aluminum oxynitride has a density greater than 99% of theoretical density, an in-line transmission of at least 50% in the 0.3-5 micron range, and a resolving angle of 1 mrad or less.
A body of polycrystalline cubic aluminum oxynitride material having a density of at least 99% of theoretical density, a sample of said body having an in-line transmission of at least 50% in the wavelength range of 0.3-5 microns said sample having a thickness of 1.45 millimeters.
A body of polycrystalline doped cubic aluminum oxynitride material having a density of at least 99% of theoretical density, a sample of said body having an in-line transmissivity of at least 50% in the 0.3-5 micron wavelength range, said sample having a thickness of 1.45 millimeters.
A body of polycrystalline doped cubic aluminum oxynitride material having a density of at least 99% of theoretical density, a sample of said body having an in-line transmissivity of at least 50% to 80% in the 0.3-5 micron wavelength range, said sample having a thickness of 1.45 millimeters.
Dependencies are inferred from the claim text.