USA as Represented by Secretary of the Navy

James A Zaykoski

Inna G Talmy

Mark M Opeka

Curtis A Martin

Eric J Wuchina

William A Ferrando

Jon Williams Cofield

Adrienne H Smith

Jennifer K Ashkenazi

An inventive method is provided for synthesizing an intermetallic compound. According to exemplary inventive practice, two metallic elements are weighed out in quantities corresponding to their molecular weights in an intermetallic compound of interest. The two metallic elements are mixed together to produce a metallic mixture in powder form. According to many inventive embodiments, a ball-mill device is implemented to thoroughly or intimately mix the two metallic elements into a fine powder. The powdered metallic mixture is exothermically reacted to produce an at least substantially pure intermetallic compound in powder form. According to many inventive embodiments, the exothermic reaction is brought about in a vacuous or inert-gaseous (e.g., helium) environment through electrification of a tungsten wire filament that is completely embedded in the powdered metallic mixture.

Synthesis of an intermetallic compound powder

Inventive manufacture of CrB&#x2014;AlOcomposites is based on pressureless sintering. According to typical inventive practice, CrBpowder and AlOpowder are mixed together in selected volumetric proportions so that the volume of the CrBdoes not exceed 50% of the overall volume of the CrB&#x2014;AlOmixture. The CrB&#x2014;AlOmixture is shaped into a green body. The green body is pressureless sintered in a non-oxidizing atmosphere at a firing temperature in the approximate range between 1600&#xb0; C. and 2050&#xb0; C. The present invention succeeds in preparing, via pressureless sintering, a proportionality-associated range of compositions in the CrB&#x2014;AlOsystem, which is a potentially 'advanced' ceramic system. A typical inventively fabricated CrB&#x2014;AlOcomposite is inventively configured in a complex shape, and has 'advanced' material (e.g., mechanical) properties that are favorable for a contemplated application. Inventive manufacture of ceramic-ceramic composites is thus dually attributed, and uncommonly so, with complex shape-ability and advanced capability.

Pressureless sintering-based method for making a two-phase ceramic composite body

The crystal structure of three compositions of matter has been determined to be iso-structural with FeB ortho-rhombic (space group Pnma). The crystalline structures are: TiTaB, ZrTaB and HfTaB. A process for preparing ceramics is disclosed. Molded ceramics including the compositions of matter are useful for applications such as rocket nozzles, leading edges on hypersonic missiles, engine parts and other applications requiring a structural component to operate at temperatures of 1600&#xb0; C. to 2400&#xb0; C.

High strength Zr (Hf or Ti)-Ta-B ceramics

There is provided a ceramic coating of zirconium diboride, silicon carbide, zirconium phosphate and silicon phosphate, that protects carbon-based materials from oxidation in high temperature oxidizing environments. The coating is applied at room temperature with a brush, roller, squeegee, doctor blade, spray gun, etc., and cured at room temperature. The cured material forms a hard, protective ceramic shell. The coating can be applied to various carbon based materials including, but not limited to, amorphous carbon foam, graphitic foam, monolithic graphite, and carbon-carbon composites. Alternative compositions of the coating can be the partial or complete substitution of hafnium diboride for zirconium diboride. Additional modifications of the coating can be accomplished by partial substitution of the borides or silicides of Ti, Ta, Cr, Nb, Ti, V, Re, for zirconium diboride.

Oxidation resistant coating for carbon

Ceramic composites of silicon carbide (SiC) grains and boron carbide (B.s4 C) grains which are uniformly coated with SiC are produced by reacting stoichiometric mixtures of silicon boride (SiB.sub.4, SiB.sub.6) and carbon (graphite or carbon black) in situ.

Boron carbide/silicon carbide ceramics

A method of preventing thermite reactions during the high temperature incineration (slag temperature greater than 1200.degree. C.) of waste material streams containing aluminum and iron (steel) by mixing a low melting SiO.sub.2 containing material such as water glass or a mixture of sand with NaHCO.sub.3 or Na.sub.2 CO.sub.3 with the waste material.

Method of suppressing thermite reactions in plasma arc waste destruction

Boron carbride/silicon carbide ceramics

A glass which contains (1) an alkaline earth oxide that is BaO, SrO, or mures thereof, (2) Al.sub.2 O.sub.3, and (3) SiO.sub.2. The glass is useful as a sintering aid in the preparation of monoclinic BaO.Al.sub.2 O.sub.3.2SiO.sub.2 or monoclinic SrO.Al.sub.2 O.sub.3.2SiO.sub.2 ceramic structures.

Sintering aids for producing BaO.Al.sub.2 O.sub.3.2SiO.sub.2 and

A composite with a reinforcing material that is Al.sub.2 O.sub.3, SiC, or xtures thereof in a matrix that is a ceramic material based on a solid solution of CrB.sub.2 and NbB.sub.2.

CrB.sub.2 -NbB.sub.2 /Al.sub.2 0.sub.3 and CrB.sub.2 -NbB.sub.2 /SiC

A Si.sub.3 N.sub.4 reinforced aluminosilicate ceramic composite made of

Method of producing Sl.sub.3 N.sub.4 reinforced monoclinic

Ceramic materials based on solid solutions of chromium diboride (CrB.sub.2) nd niobium diboride (NbB.sub.2).

Growing community of inventors

Beltsville, MD, United States of America

James A Zaykoski