USA as Represented by Secretary of the Navy

Other

Inna G Talmy

James A Zaykoski

Deborah A Haught

Curtis A Martin

Mark M Opeka

Eric J Wuchina

Kurt P Scharnhorst

Anh H Le

Jon Williams Cofield

Jennifer K Ashkenazi

Adrienne H Smith

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

Monoclinic celsian (BaO.Al.sub.2 O.sub.3.2SiO.sub.2) is produced by heating a stoichiometric, powder mixture of BaCO.sub.3 (or BaC.sub.2 O.sub.4), Al.sub.2 O.sub.3, and SiO.sub.2 (preferably SiO.sub.2 gel) with monoclinic celsian seeds at from 1250.degree. C. to 1500.degree. C.

Method of preparing monoclinic BaO.A1.sub.2 O.sub.3.2SiO.sub.2

A ceramic material which is (1) ceramics based on monoclinic BaO.multidot.sub.2 O.sub.3 .multidot.2SiO.sub.2 ; (2) ceramics based on monoclinic SrO.multidot.Al.sub.2 O.sub.3 .multidot.2SiO.sub.2 ; or (3) ceramics based on monoclinic solid solution of BaO.multidot.Al.sub.2 O.sub.3 .multidot.2SiO.sub.2 and SrO.multidot.Al.sub.2 O.sub.3 .multidot.2SiO.sub.2.

Ceramic material

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

A ceramic electromagnetic window made of Si.sub.3 N.sub.4 particles which are bonded together by a metal phosphate binder that is an AlPO.sub.4 binder, a ZrP.sub.2 O.sub.7 binder, or mixtures thereof, wherein the Si.sub.3 N.sub.4 particles comprise from 55 to 85 volume percent of the ceramic material of the electromagnetic window with the metal phosphate binder comprising the remainder. By substituting Si.sub.3 N.sub.4 whiskers for some of the Si.sub.3 N.sub.4 particles a discontinuous fiber composite ceramic electromagnetic window is produced. The electromagnetic window may be a simple shape such as a flat or slightly curved sheet or a more complex shape such as a conical or spherical radome.

Electromagnetic window

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

CrB.sub.2 -NbB.sub.2 ceramics materials

Si.sub.3 N.sub.4 reinforced monoclinic BaO.Al.sub.2 O.sub.3

A ceramic material made from raw coal fly ash or raw municipal solid waste fly ash and (1) sodium tetraborate or (2) a mixture of sodium tetraborate and a calcium containing material that is triple superphosphate, lime, dolomitic lime, or mixtures thereof.

Growing community of inventors

Silver Spring, MD, United States of America

Inna G Talmy