The University of Texas System

David L Bourell

Harris L Marcus

Joseph Jefferson Beaman, Jr

Joel W Barlow

Carl Robert Deckard

Arumugam Manthiram

Richard H Crawford

Deborah A Hagen

Neal K Vail

Udaykumar Lakshminarayan

Desiderio Kovar

Wendy L Weiss

Joseph L Beaman

James R Tobin

Balasubramanian Badrinarayan

Douglas W Freitag

Various implementations include systems and methods for simultaneously applying an electric field and localized energy from an energy source to ceramic particles on a layer by layer basis to form a ceramic workpiece using additive manufacturing. The workpiece may be freely removed from the unsintered ceramic particles. In some implementations, the workpiece is partially densified when removed from the unsintered ceramic particles, but it may be heated until fully densified. According to some implementations, these systems and methods remove or reduce the need for binders and reduce manufacturing time.

Systems and methods for additive manufacturing of ceramics

A mold useful for injection molding, comprising: a porous network of metal and oxidized metal and a cured epoxy resin dispersed in the porous network. The mold can be prepared by a process comprising the sequential steps of (a) forming a mixture of a metal powder and a polymer binder; (b) heating the mixture at a temperature in the range from about 100.degree. C. to about 300.degree. C. to remove a majority of the polymer binder from the mixture; (c) heating the mixture resulting from step (b) at a temperature greater than about 300.degree. C. and less than the melting point of the metal in the presence of oxygen to oxidize at least a portion of the metal to form a self-adhering porous network of metal and oxidized metal; (d) contacting the self-adhering porous network with an epoxy resin to fill at least a portion of the porous network with epoxy resin; and (e) curing the body resulting from step (d) to form the mold. The shape of the mold can be performed by selective laser sintering of the mixture.

Mold useful for injection molding of plastics, and methods of production

A method of fabricating a fully-dense three-dimensional metal article is disclosed. According to a first embodiment of the invention, the interior portion of the article is formed by way of selective laser sintering, in a cross-section of a layer of powder. After formation of the layer of powder, the laser is directed to form a gas-impervious skin around the interior portion of the article in that layer. The process is repeated, until the article is completed. The article surrounded by the skin is then subjected to hot isostatic pressing to densify the article; the skin, which serves as the 'can' for the hot isostatic pressing, may or may not be removed from the article, as desired. According to a second embodiment of the invention, the can is formed first by way of laser generation, and is then filled with the metal powder, prior to hot isostatic pressing.

Laser-directed fabrication of full-density metal articles using hot

A method of fabricating three-dimensional objects in a layerwise fashion, and having high structural strength and high density, is disclosed. Methods are disclosed by which nanocomposite powders of ceramic-ceramic systems, ceramic-metal systems, ceramic-polymer systems, and metal-polymer systems are produced. Disclosed examples utilize solution chemistry approaches, such as sol-gel processing, by way of which a gel is produced which is then fired and milled to form a powder suitable for selective laser sintering, where a laser fuses selected portions of layers of the powders according to a computer-aided-design data base. The ultraheterogeneity of the powder results in larger surface area and grain boundaries of the constituents, which enhances the solid state diffusion mechanism, and thus reduces the time and temperature required for sintering to occur. In addition, the higher stored metastable energy of the nanocomposite powder is believed to enhance densification during solid-phase sintering. Objects of high density of complex shape may thus be obtained directly from CAD data base design representations.

Selective laser sintering using nanocomposite materials

A method and apparatus for selectively sintering a layer of powder to produce a part comprising a plurality of sintered layers. The apparatus includes a computer controlling a laser to direct the laser energy onto the powder to produce a sintered mass. The computer either determines or is programmed with the boundaries of the desired cross-sectional regions of the part. For each cross-section, the aim of the laser beam is scanned over a layer of powder and the beam is switched on to sinter only the powder within the boundaries of the cross-section. Powder is applied and successive layers sintered until a completed part is formed. Preferably, the powder comprises a plurality of materials having different dissociation or bonding temperatures. The powder preferably comprises blended or coated materials.

Multiple material systems for selective beam sintering

A method and apparatus for selectively sintering a layer of powder to produce a part comprising a plurality of sintered layers. The apparatus includes a computer controlling a laser to direct the laser energy onto each layer of the powder to produce a sintered mass corresponding to a cross-section of the part. For each cross-section, the aim of the laser beam is scanned over a layer of powder and the beam is switched on to sinter only the powder within the boundaries of the cross-section. Powder is applied and successive layers sintered until a completed part is formed. Also disclosed is a method of forming a part by interaction of material in the powder layer with reactants in the surrounding atmosphere, at locations of the powder irradiated by the energy, or laser, beam. The reaction may be nitridation, oxidation or carburization of the powder, with the product being a chemical compound of one or more constituents in the powder with one or more gases in the atmosphere. Alternatively, reduction of the powder may be so enabled by the energy beam so that a metallic phase product is formed at the irradiated locations. Particular benefits of the invention include the densification of the material of the part as a result of the reaction, and the ability to form high temperature materials by way of a relatively low temperature process.

Method of producing parts by selective beam interaction of powder with

A method and apparatus for selectively sintering a layer of powder to produce a part comprising a plurality of sintered layers. The apparatus includes a computer controlling a laser to direct the laser energy onto the powder to produce a sintered mass. The computer either determines or is programmed with the boundaries of the desired cross-sectional regions of the part. For each cross-section, the aim of the laser beam is scanned over a layer of powder and the beam is switched on to sinter only the powder within the boundaries of the cross-section. Powder is applied and successive layers sintered until a completed part is formed. Preferably, the powder comprises a plurality of materials having different dissociation or bonding temperatures. The powder preferably comprises blended or coated materials, including precursor materials which are formed into a mass at the irradiated locations, and which either react due to the laser thermal energy or in a later heat treatment to form a compound with properties different than the precursors. Examples are disclosed wherein a compound is formed which has a significantly higher melting point than that of one or more of the precursor powders.

Selective laser sintering of parts by compound formation of precursor

A method and apparatus for selectively sintering a layer of powder to produce a part comprising a plurality of sintered layers. The apparatus includes a computer controlling a laser to direct the laser energy onto the powder to produce a sintered mass. The computer either determines or is programmed with the boundaries of the desired cross-sectional regions of the part. For each cross-section, the aim of the laser beam is scanned over a layer of powder and the beam is switched onto sinter only the powder within the boundaries of the cross-section. Powder is applied and successive layers sintered until a completed part is formed. Preferably, the powder comprises a plurality of materials having different dissociation or bonding temperatures. The powder preferably comprises blended or coated materials.

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Austin, TX, United States of America

David L Bourell