The Dow Chemical Company

Omg Americas, Inc.

Daniel F Carroll

Stephen D Dunmead

Alan W Weimer

Glenn A Eisman

Donald R Beaman

Gene A Cochran

Kevin J Nilsen

David W Susnitzky

Kevin E Howard

John P Henley

Ellen M Dubensky

Hobart A Barker

Stephen A Anderson

Scott J Biskupski

Pat J DeLuca

Tom J Bunnelle

Joe F Repman

A pressable powder is formed by a method comprising &lsqb;I&rsqb; mixing, in essentially deoxygenated water, &lsqb;A&rsqb; a first powder selected from the group consisting of a transition metal carbide and transition metal with &lsqb;B&rsqb; an additional component selected from the group consisting of (i) a second powder comprised of a transition metal carbide, transition metal or mixture thereof; (ii) an organic binder and (iii) combination thereof and &lsqb;II&rsqb; drying the mixed mixture to form the pressable powder, wherein the second powder is chemically different than the first powder. The pressable powder may then be formed into a shaped part and subsequently densified into a densified part, such as a cemented tungsten carbide.

Method of preparing pressable powders of a transition metal carbide, iron group metal of mixtures thereof

A transition metal carbide (e.g., WC) is prepared by the following steps. A carbon-precursor mixture is formed by mixing a precursor comprised of (i) a transition metal oxide (e.g., WO.sub.x) and (ii) a material selected from the group consisting of: a transition metal (e.g., W); a transition metal carbide (e.g., WC) and a substoichiometric carbide (W.sub.2 C), in the presence of a source of carbon (e.g., carbon black) in an amount sufficient to form a reduced mixture comprised of the transition metal carbide and substoichiometric transition metal carbide, wherein the amount of the transition metal oxide and transition metal is essentially zero in said reduced mixture. The carbon-precursor mixture is heated in a reducing atmosphere (e.g., 5 percent hydrogen in argon) to a reducing temperature and for a time sufficient to produce the reduced mixture. The reduced mixture is milled in the presence of a source of carbon in an amount sufficient to carburize the substoichiometric transition metal carbide to form the transition metal upon heating in a reducing atmosphere. Finally, the milled reduced mixture is heated in a reducing atmosphere to a carburizing temperature that is greater than the reducing temperature for a time sufficient to carburize the substoichiometric transition metal carbide to form the transition metal carbide of this invention (e.g., WC).

Method to produce a transition metal carbide from a partially reduced

A pressable powder is formed by a method comprising mixing, in essentially deoxygenated water, a first powder selected from the group consisting of a transition metal carbide and transition metal with an additional component selected from the group consisting of (i) a second powder comprised of a transition metal carbide, transition metal or mixture thereof; (ii) an organic binder and (iii) combination thereof and drying the mixed mixture to form the pressable powder, wherein the second powder is chemically different than the first powder. The pressable powder may then be formed into a shaped part and subsequently densified into a densified part, such as a cemented tungsten carbide.

Method of preparing pressable powders of a transition metal carbide,

Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

Silicon nitride/silicon carbide composite densified materials prepared

A method for making a moisture-resistant aluminum nitride-containing powder which includes (a) coating a layer of silicate onto aluminum nitride-containing powder having aluminum nitride on at least a portion of its surface and (b) heat-treating the coated aluminum nitride-containing powder at a temperature of from 350.degree. to 1000.degree. C. for a period of time sufficient to cause the silicate to react with the surface aluminum nitride thereby forming a layer of Si--Al--O--N bonded to the surface aluminum nitride. The silicate has alkyl or alkoxyalkyl radicals attached thereto. The method yields a moisture-resistant aluminum nitride-containing powder having a layer of Si--Al--O--N reaction-bonded to the surface aluminum nitride.

Method of making moisture resistant aluminum nitride powder and powder

A multi-phase cemented ceramic article, method of making same, and the material thereof is disclosed which is useful for machining and forming of metals, including ferrous metals, titanium, aluminum and other metals. The article and its material preferably includes novel microstructures including platelets, a range of grain sizes which yields superior hardness and other characteristics, and a lower tungsten concentration within the binder phase than has been seen in the prior art. The preferred composition includes ultrafine WC, an ultrafine solid solution of (Ti, Ta, W)C, and a cobalt binder. Platelets are formed in-situ, eliminating the need to add them during manufacture for improving toughness.

Cemented ceramic article made from ultrafine solid solution powders,

Silicon carbide/silicon nitride composites are prepared by carbothermal reduction of crystalline silica powder, carbon powder and optionally crsytalline silicon nitride powder. The crystalline silicon carbide portion of the composite has a mean number diameter less than about 700 nanometers and contains nitrogen.

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Midland, MI, United States of America

Daniel F Carroll