USA As Represented by Secretary of the Navy

California Institute of Technology

James A Wollmershauser

Boris N Feigelson

Edward P Gorzkowski, Iii

Kedar Manandhar

Alan G Jacobs

Benjamin L Greenberg

Dana A Kazerooni

Kevin P Anderson

John Drazin

Francis J Kub

Richard Robert Hofer

Bryan William McEnerney

Katherine T Faber

Celia S Chari

Aspects disclosed herein include graphite and hexagonal boron nitride bimaterials, methods of making these bimaterials, and electric propulsion devices or thrusters with these bimaterials. Aspects disclosed herein include electric propulsion devices comprising: at least one portion comprising or formed of a monolithic bimaterial; wherein the monolithic bimaterial comprises a graphite material and a hexagonal boron nitride material; and wherein the graphite material and hexagonal boron nitride material are monolithically integrated in the bimaterial.

Graphite/hexagonal boron nitride bimaterials for electric propulsion

Thermoelectric (TE) nanocomposite material that includes at least one component consisting of nanocrystals. A TE nanocomposite material in accordance with the present invention can include, but is not limited to, multiple nanocrystalline structures, nanocrystal networks or partial networks, or multi-component materials, with some components forming connected interpenetrating networks including nanocrystalline networks. The TE nanocomposite material can be in the form of a bulk solid having semiconductor nanocrystallites that form an electrically conductive network within the material. In other embodiments, the TE nanocomposite material can be a nanocomposite thermoelectric material having one network of p-type or n-type semiconductor domains and a low thermal conductivity semiconductor or dielectric network or domains separating the p-type or n-type domains that provides efficient phonon scattering to reduce thermal conductivity while maintaining the electrical properties of the p-type or n-type semiconductor.

Thermoelectric nanocomposite materials

A thermionic dispenser cathode having a refractory metal matrix with scandium and barium compounds in contact with the metal matrix and methods for forming the same. The invention utilizes atomic layer deposition (ALD) to form a nanoscale, uniform, conformal distribution of a scandium compound on tungsten surfaces and further utilizes in situ high pressure consolidation/impregnation to enhance impregnation of a BaO&#x2014;CaO&#x2014;AlObased emissive mixture into the scandate-coated tungsten matrix or to sinter a tungsten/scandate/barium composite structure. The result is a tungsten-scandate thermionic cathode having improved emission.

Thermionic tungsten/scandate cathodes and method of making the same

A new Enhanced High Pressure Sintering (EHPS) method for making three-dimensional fully dense nanostructures and nano-heterostructures formed from nanoparticle powders, and three-dimensional fully dense nanostructures and nano-heterostructures formed using that method. A nanoparticle powder is placed into a reaction chamber and is treated at an elevated temperature under a gas flow to produce a cleaned powder. The cleaned powder is formed into a low density green compact which is then sintered at a temperature below conventional sintering temperatures to produce a fully dense bulk material having a retained nanostructure or nano-heterostructure corresponding to the nanostructure of the constituent nanoparticles. All steps are performed without exposing the nanoparticle powder to the ambient.

Bulk monolithic nano-heterostructures and method of making the same

A process for producing metastable nanocrystalline alpha-alumina (&#x3b1;-AlO) having particle sizes smaller than 12 nm. Starting crystallites of &#x3b1;-AlOhaving a particle size larger than 12 nm, typically on the order of about 50 nm, are ball-milled at low temperatures to produce a nanocrystalline &#x3b1;-AlOpowder having a particle size of less than 12 nm, i.e., below the theoretical room temperature thermodynamic size limit at which &#x3b1;-AlOchanges phase to &#x3b3;-AlO, wherein the powder remains in the &#x3b1;-AlOphase at all times.

Nanocrystalline alpha alumina and method for making the same

A method for making transparent nanocomposite ceramics and other solid bulk materials from nanoparticle powders and transparent nanocomposite ceramics and other solid bulk materials formed using that method. A nanoparticle powder is placed into a reaction chamber and is treated to produce a clean surface powder. The clean surface powder is coated with a second material by means of p-ALD to produce core/shell or core multi shell nanoparticles having a coating or coatings of a other material surrounding the nanoparticle. The core/shell nanoparticles are cleaned and formed into green compact which is sintered to produce a transparent nanocomposite ceramic or other solid bulk material consisting of nanoparticles or core/shell nanoparticles uniformly embedded in a matrix of a different material, particularly in a matrix of a different ceramic material, formed by outer shell of initial core/shell. All steps are performed without exposing the material to the ambient.

Growing community of inventors

Alexandria, VA, United States of America

James A Wollmershauser