University of California

Amiya K Mukherjee

Joshua D Kuntz

Guodong Zhan

Julin Wan

Matthew J Gasch

Subhash H Risbud

Charles E Lesher

Ren-Guan Duan

Rajiv S Mishra

Ceramic materials are converted to materials with anisotropic thermal properties, electrical properties, or both, by forming the ceramics into composites with carbon nanotubes dispersed therein and uniaxially compressing the composites in a direction in which a lower thermal or electrical conductivity is desired.

Anisotropic thermal and electrical applications of composites of ceramics and carbon nanotubes

High-density composites of alumina and titania with nano-sized grains are prepared from aluminum titanate without the need to use nano-sized powder as a starting material. The preparation is achieved by high-energy ball milling of the aluminum titanate followed by sintering at elevated temperature and pressure. The aluminum titanate can be prepared from micron-sized alumina and titania particles through plasma jet processing.

Preparation of nanocomposites of alumina and titania

Optical windows for protecting infrared sensing instruments are manufactured from nano-sized crystallites by compressing the crystallites into a continuous mass under high pressure in the presence of a pulsed electric current, preferably one produced by spark plasma sintering. The resulting materials have excellent optical and mechanical properties that make them favorable as replacements for the conventional single-crystal sapphire.

Polycrystalline optical window materials from nanoceramics

Composite materials containing silicon, titanium, carbon, and nitrogen, formed by spark plasma sintering of ceramic starting materials to a high relative density, demonstrate unusually high electrical conductivity as well as high-performance mechanical and chemical properties including hardness, fracture toughness, and corrosion resistance. This combination of electrical, mechanical, and chemical properties makes these composites useful as electrical conductors in applications where high-performance materials are needed due to exposure to extreme conditions such as high temperatures, mechanical stresses, and corrosive environments.

Electrically conductive Si-Ti-C-N ceramics

Densified composites of silicon nitride, silicon carbide, and boron nitride that exhibit high creep resistance are obtained by sintering a mixture of amorphous powders of silicon nitride, silicon carbide, and boron nitride in the presence of an electric field under high pressure. The grain size in the resulting composite is less than 100 nanometers for all components of the composite, and the composite exhibits high creep resistance.

Nanocomposites of silicon nitride, silicon carbide, and boron nitride

Densified composites of silicon nitride and silicon carbide that exhibit high creep resistance are obtained by mechanically activating a mixture of amorphous powders of silicon nitride and silicon carbide and sintering the mechanically activated mixture in the presence of an electric field under high pressure. The grain size in the resulting composite is less than 100 nanometers for all components of the composite, and the composite exhibits high creep resistance.

Method of forming silicon carbide and silicon nitride composite

Ceramic materials are converted to materials with anisotropic thermal properties by forming the ceramics into composites with carbon nanotubes dispersed therein and uniaxially compressing the composites in a direction in which a lower thermal conductivity is desired.

Anisotropic thermal applications of composites of ceramics and carbon nanotubes

A nano-sized powder of barium titanate is compacted and sintered by spark plasma sintering under conditions creating a high heating rate to achieve a densified material that demonstrates superior permittivity.

High-density barium titanate of high permittivity

Composite materials formed of a matrix of fused ceramic grains with single-wall carbon nanotubes dispersed throughout the matrix and a high relative density, notably that achieved by electric field-assisted sintering, demonstrate unusually high electrical conductivity in combination with high-performance mechanical properties including high fracture toughness. This combination of electrical and mechanical properties makes these composites useful as electrical conductors in applications where high-performance materials are needed due to exposure to extreme conditions such as high temperatures and mechanical stresses.

Ceramic materials reinforced with single-wall carbon nanotubes as electrical conductors

Composites of ceramic materials, notably alumina or metal oxides in general, with single-wall carbon nanotubes are consolidated by electric field-assisted sintering to achieve a fully dense material that has an unusually high fracture toughness compared to the ceramic alone, and also when compared to composites that contain multi-wall rather than single-wall carbon nanotubes, and when compared to composites that are sintered by methods that do not include exposure to an electric field.

Nanocrystalline ceramic materials reinforced with single-wall carbon nanotubes

Alumina composites of unusually high hardness and toughness are formed by combining alumina and diamond in nanocrystalline form, followed by sintering at high pressure.

Growing community of inventors

Davis, CA, United States of America

Amiya K Mukherjee