USA As Represented by Secretary of the Navy

Bryan Sadowski

Jasbinder Singh Sanghera

Guillermo R Villalobos

Ishwar Dayal Aggarwal

Shyam S Bayya

Woohong Kim

Michael Hunt

Jesse A Frantz

Jason D Myers

Colin C Baker

Robel Y Bekele

Benjamin Rock

Alex E Moser

Robert E Miklos

The present invention provides a method for making a high strength, small grain size ceramic having a transgranular fracture mode by rapid densification of a green body and subsequent cooling of the densified ceramic. The ceramic may include dislocations, defects, dopants, and/or secondary phases that are formed as a result of the process and resulting in stress fields capable of redirecting or arresting cracks within the material. This ceramic can maintain transparency from ultraviolet to mid-wave infrared.

High strength ceramics with novel fracture mode

The present invention provides a method for making a high strength, small grain size ceramic having a trans-granular fracture mode by rapid densification of a green body and subsequent cooling of the densified ceramic. The ceramic may include dislocations, defects, dopants, and/or secondary phases that are formed as a result of the process and resulting in stress fields capable of redirecting or arresting cracks within the material. This ceramic can maintain transparency from ultraviolet to mid-wave infrared.

A &#x3b2;-SiC coating made by the method of mixing SiOwith carbon and heating the mixture in vacuum wherein the carbon is oxidized to CO gas and reduces the SiOto SiO gas and reacting a carbon material, comprising stainless steel with a carbon coating, with the SiO gas at a temperature in the range of 1300 to 1600&#xb0; C. resulting in a SiC coating on the stainless steel.

In situ grown SiC coatings on carbon materials

A transparent composite armor is made of tens to hundreds or even thousands of thin layers of material each with a thickness of 10-500 &#x3bc;m. An appropriate amount of impedance mismatch between the layers causes some reflection at each interface but limit the amplitude of the resulting tensile wave below the tensile strength of the constituent materials. The result is an improvement in ballistic performance and that will result is a significant impact in reducing size, weight, and volume of the armor.

Shockwave controlled ballistic protection

A method of purifying a spinel powder includes contacting a spinel powder with an acid solution to form an acid-washed spinel composition and contacting the acid-washed spinel composition with a basic solution to form a purified composition. The purified powder is suited to formation of low-absorption shaped bodies, such as windows for high intensity laser devices.

Low absorption spinel formed by acidic and basic treatments

A method of containing molten aluminum using non-wetting materials comprising depositing MgAlO, or one selected from an oxide, AlO, nitride, AlN, BN, carbide, and SiC, onto a crucible. An apparatus for containment of molten aluminum using non-wetting materials comprising a layer of MgAlO, or one selected from an oxide, AlO, nitride, AlN, BN, carbide, and SiC, deposited onto a crucible.

Manufacturing a crucible for containment using non-wetting materials

A method of forming a &#x3b2;-SiC material or coating by mixing SiOwith carbon and heating the mixture in vacuum wherein the carbon is oxidized to CO gas and reduces the SiOto SiO gas and reacting a carbon material with the SiO gas at a temperature in the range of 1300 to 1600&#xb0; C. resulting in a SiC material or a SiC coating on a substrate. Also disclosed is the related SiC material or coating prepared by this method.

Situ grown SiC coatings on carbon materials

Method of Making particles including a YAG core and a coating of sintering aid deposited thereon. The particles and agglomerates thereof maybe formed as a powder. The coated YAG-containing particles are well-suited to production of polycrystalline YAG-containing ceramics. The coated YAG-containing particles may be fabricated using a novel fabrication method which avoids the need for formation of a homogeneous powder mixture of YAG and sintering aid. The mixture may be sprayed into a drying column and dried to produce coated particles. Alternatively, the YAG particles and sintering aid or sintering aid precursor solution may be separately introduced to the drying column and dried to form coated YAG-containing particles.

Sintering aid coated YAG powders and agglomerates and methods for making

Containment of molten aluminum using non-wetting materials

A transparent polycrystalline ceramic having scattering and absorption loss less than 0.2/cm over a region comprising more than 95% of the originally densified shape and a process for fabricating the same by hot pressing. The ceramic can be any suitable ceramic such as yttria (YO) or scandia (ScO) and can have a doping level of from 0 to 20% and a grain size of greater than 30 &#x3bc;m, although the grains can also be smaller than 30 &#x3bc;m. Ceramic nanoparticles can be coated with a sintering aid to minimize direct contact of adjacent ceramic powder particles and then baked at high temperatures to remove impurities from the coated particles. The thus-coated particles can then be densified by hot pressing into the final ceramic product. The invention further provides a transparent polycrystalline ceramic solid-state laser material and a laser using the hot pressed polycrystalline ceramic.

Hot-pressed transparent ceramics and ceramic lasers

A transparent polycrystalline ceramic having scattering and absorption loss less than 0.2/cm over a region comprising more than 95% of the originally densified shape and further provides a process for fabricating the same by hot pressing. The ceramic can be any suitable ceramic such as yttria (YO) or scandia (ScO) and can have a doping level of from 0 to 20% and a grain size of greater than 30 &#x3bc;m, although the grains can also be smaller than 30 &#x3bc;m. In a process for making a transparent polycrystalline ceramic in accordance with the present invention, ceramic nanoparticles can be coated with a sintering aid to minimize direct contact of adjacent ceramic powder particles and then baked at high temperatures to remove impurities from the coated particles. The thus-coated particles can then be densified by hot pressing into the final ceramic product. The invention further provides a transparent polycrystalline ceramic solid-state laser material and a laser using the hot pressed polycrystalline ceramic.

An embodiment of the invention includes a particle. The particle includes a first yttria core; and a fluoride salt coating on the first yttria core. The coating is sufficiently continuous to prevent a large number of sites where a second yttria core may come into contact with the first yttria core. Optionally, the particle has been heated in an oxidizing atmosphere to a temperature in the range of about 400&#xb0; C. to about 750&#xb0; C. Optionally, the particle is substantially free of at least one of carbon-containing species and water. Optionally, the fluoride salt is lithium fluoride. Optionally, the fluoride salt is aluminum fluoride.

Growing community of inventors

Falls Church, VA, United States of America

Bryan Sadowski