The Dow Chemical Company

Bijan Khazai

William G Moore

G Edwin Vrieland

Craig B Murchison

Ravi S Dixit

Stephen J Doktycz

Edwin D Weihl

A composition and method for producing boron carbide/titanium diboride composite ceramic powders is disclosed. The process comprises the ordered steps of (a) intimately mixing as reactants boron carbide and a titanium source, such that the average reactant particle size is less than about 20 microns and substantially all discrete reactant areas are less than about 50 microns, and (b) reacting the product of step (a) under conditions sufficient to produce a boron carbide/titanium diboride composite ceramic powder wherein at least a portion of the boron carbide particles form substrates to which at least a portion of the titanium diboride particles are attached. The method can be used to produce a composite ceramic powder having boron carbide and titanium diboride particles less than about 20 microns in diameter. This powder can then be densified using known densification techniques to form a densified part wherein the titanium diboride grains have an average size of less than about 20 microns in diameter and the boron carbide grains having an average size of less than about 50 microns.

Composition and method for producing boron carbide/titanium diboride

A process for preparing olefins and diolefins in high productivity which involves contacting an aliphatic hydrocarbon, such as butane, with a heterogeneous catalyst composition containing reactive oxygen under reaction conditions sufficient to produce a more highly unsaturated aliphatic hydrocarbon, such as 1,3-butadiene. The catalyst composition contains a glassy silica matrix of specified surface area and macro-porosity into which are encapsulated domains of a catalyst component containing oxides of magnesium and molybdenum. The catalyst has high crush strength and is useful in transport reactors.

Process of oxidizing aliphatic hydrocarbons employing a molybdate

A process for the production of olefins and diolefins, such as 1,3-butadiene, comprising contacting an aliphatic hydrocarbon, such as butane, with a heterogeneous catalyst composition containing reactive oxygen under reaction conditions such that a more highly unsaturated aliphatic hydrocarbon is selectively formed in a high productivity. The catalyst is a composition comprising (a) a support component of magnesia and alumina and/or magnesium aluminate spinel, and (b) a catalyst component of magnesia, an oxide of molybdenum, a Group IA metal oxide promoter, and optionally vanadium oxide. Catalysts of high surface area and high attrition resistance are claimed.

Metal boride powders can be produced with a predetermined particle size by controlling reaction conditions. The metal boride powder is produced by reacting a solid boron source, a metal source and a reductant under conditions sufficient to produce a metal boride powder with a particle size correlating to that of the solid boron source. The reaction is preferably stopped after the formation of products but before any apprecible crystal growth occurs.

Synthesis of refractory metal boride powders of predetermined particle

A mixture of reactants having a particle size of about 200 microns is heated to convert said mixture comprising a metal compound, carbon, and a boron source to a metal boride having an average particle size of about 0.05 to about 0.5 micron. Said metal compound is one which can be converted to the corresponding metal boride by reaction with carbon and a boron source under controlled conditions of time and temperature.

Process for producing metal borides using finely comminuted mixture of

A composition and method for producing boron carbide/titanium diboride composite ceramic powders is disclosed. The process comprises the ordered steps of (a) intimately mixing as reactants boron carbide and a titanium source, such that the average reactant particle size is less than about 20 microns and substantially all discrete reactant areas are less than about 50 microns, and (b) reacting the product of step (a) under conditions sufficient to produce a boron carbide/titanium diboride composite ceramic powder wherein at least a portion of the boron carbide particles form substrates to which at least a portion of the titanium diboride particles are attached. The method can be used to produce a composite ceramic powder having boron carbide and titanium diboride particles less than about 20 microns in diameter. This powder can then be densified using known densification techniques to form a densified part wherein the titanium diboride grains have an average size of less than about 20 microns in diameter and the boron carbide grains having an average size of less than about 50 microns. Because of the uniformity of dispersion that can result, the densified part shows a microstructure that is also very uniform in distribution of boron carbide and titanium diboride.

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Midland, MI, United States of America

Bijan Khazai