Raytheon Company

Edward A Maguire, Jr

Richard L Gentilman

Thomas M Hartnett

Leonard E Dolhert

Albert E Paladino

Dennis W Readey

An article of manufacture is provided comprising a polycrystalline cubic aluminum oxynitride having a density of at least 98% of theoretical density, and being transparent to electromagnetic radiation in the wavelength range from 0.3 to 5 micrometers with an in-line transmission of at least 20% in this range. A method of preparing the optically transparent aluminum oxynitride is also provided comprising the steps of forming a green body of substantially homogeneous aluminum oxynitride powder and pressureless sintering said green body in a nitrogen atmosphere and in the presence of predetermined additives which enhance the sintering process. Preferred additives are boron and yttrium in elemental or compound form.

Transparent aluminum oxynitride and method of manufacture

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.

Method of producing aluminum oxynitride having improved optical

Aluminum oxynitride having improved optical characteristics and method

A method of forging spinel into complex shapes in which a spinel plate is placed in a mold while the spinel plate is heated, in an atmosphere of helium, to a temperature below its melting point and above its solid two phases transition point that allows plastic deformation to take place. Forging stresses well above the yield point of the spinel are applied to the plate by the mold to reduce the forging time.

Method of forging spinel domes

A group of dielectric compounds and mixtures of dielectric compounds with useful properties at microwave frequencies is disclosed. The dielectric materials are temperature compensated, have relatively high dielectric constants, and comprise the group of BaTi.sub.4 O.sub.9, and mixtures of Li.sub.2 TiO.sub.3 and Li.sub.4 Ti.sub.5 O.sub.12, MgTi.sub.2 O.sub.5 and TiO.sub.2, Zn.sub.2 TiO.sub.4 and TiO.sub.2, and BaTi.sub.4 O.sub.9 and TiO.sub.2.

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Ashland, MA, United States of America

Edward A Maguire, Jr