Raychem Limited

Karin M Kinsman

Ryan W Dupon

Amy S Chu

Linas Mazeika

Pawel Czubarow

Martha L McCrum

Anthony C Evans

Mark W Ellsworth

Christian Weber

Eugen L Kurjatko

Andrew P Washabaugh

A method of forming an article having a cermet layer on a porcelain substrate, via the steps of (a) providing a substrate made a porcelain comprising one or more crystalline oxide phases dispersed in a glassy matrix, the glassy matrix containing 0.25 to 45.0 weight % of a reducible metal oxide having a reduction potential of between -1.0 and +3.5 E.degree./V; and (b) heating the substrate in a reducing atmosphere to form on at least one surface of the substrate a layer of cermet comprising elemental metal which is a reduction product of the reducible metal oxide. The article may be used as a substrate for magnetic recording disks.

Magnetic disk comprising a substrate with a cermet layer on a porcelain

Calcined ceramic powder is made by blending a precursor powder with a form of carbon such as carbon black and heating the blend in an oxygenated atmosphere. The carbon acts as a separator, preventing coalescence of the percursor powder during the calcining process. The blend is characterized by the presence of interstitial spacing between the particles of the carbon powder and the precursor powder. The carbon is eventually oxidized to carbon dioxide and/or carbon monoxide and volatilizes as such, leaving behind the calcined ceramic powder. In a preferred embodiment, the heating is effected by microwave radiation. The carbon absorbs the microwave radiation, heating up the precursor powder and calcining it to form the ceramic powder. Once all the carbon has been oxidized, no more microwave radiation is absorbed, and the heating stops, making the process self-limiting.

Preparation of calcined ceramic powders

A method for making a high strength porcelain for use as an insulator or a structural ceramic, comprising: A) forming a mixture comprising alumina, clay and a fluxing material; B) forming the mixture into a shaped article; and C) firing the shaped article.

High strength porcelain and method therefor

A porcelain having 9 to 55% by weight of SiO.sub.2, 36 to 87% by weight of Al.sub.2 O.sub.3, 0 to 2.0% by weight of Fe.sub.2 O.sub.3, 0 to 1.0% by weight of TiO.sub.2, 0 to 0.5% by weight of CaO, 0 to 0.5% by weight of MgO, 1.0 to 4.0% by weight of K.sub.2 O and Na.sub.2 O combined, and 0.25 to 25.0% by weight of bismuth oxide is disclosed. The porcelain has unexpectedly high unglazed bending strength and may be used for dielectric and structural applications.

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San Mateo, CA, United States of America

Karin M Kinsman