University of California

The United States of America As Represented by the United States

Other

The United States of America As Represented by the Department of Energy

Zuhair A Munir

Danny C Halverson

Joseph B Holt

Donald D Kingman

Stephen D Dunmead

Umberto Anselmi-Tamburini

Beverly Y Lum

Ronald G Musket

David W Brown

Kazuo Yamazaki

John J Petrovic

Javier E Garay

Subhash H Risbud

Sangtae Kim

Weinong Lai

Karl H Ewald

Maryam Eslamloo-Grami

In-Jin Shon

Benjamin J McCoy

Wei Nong Lai

Frederic Charlot

Eric Gaffet

Joseph N Woolman

Jörg F Löffler

Troy B Holland

Manfred Martin

The present invention provides a proton conducting thin film having a dense nanometric ceramic material with a relative density of at least about 90% and a grain size of less than about 30 nm, wherein the proton conducting thin film is capable of operating at temperatures of less than about 100&#xb0; C. in the presence of water vapor. The present invention also provides an electrochemical device using the proton conducting thin film, and a method of making the proton conducting thin film.

Low-temperature protonic conduction for hydrogen-related energy applications employing nanostructured functional oxides

A method for preparing highly dense functional oxides with crystallite size in the range of 10-20 nm. Using a high pressure modification of a the Spark Plasma Sintering (SPS) technique, rapid thermal cycles (&#x3c;10 min) coupled with very rapid pressure increase up to 1 GPa can be obtained allowing high degree of compaction and very limited grain growth. This combination of techniques was employed to produce the finest-grained ceramics ever prepared in bulk form in the case of fully stabilized zirconia and Sm-doped Ceria.

Preparation of dense nanostructured functional oxide materials with fine crystallite size by field activation sintering

Metallic glasses of superior mechanical and magnetic properties are manufactured by annealing the glasses under the influence of an electric current to convert the glass to a composite that includes crystallites, preferably nanocrystallites, dispersed through an amorphous matrix.

Metallic glasses with crystalline dispersions formed by electric currents

Alloys of transition metal suicides that contain one or more alloying elements are fabricated by a two-stage process involving mechanical activation as the first stage and densification and field-activated reaction as the second stage. Mechanical activation, preferably performed by high-energy planetary milling, results in the incorporation of atoms of the alloying element(s) into the crystal lattice of the transition metal, while the densification and field-activated reaction, preferably performed by spark plasma sintering, result in the formation of the alloyed transition metal silicide. Among the many advantages of the process are its ability to accommodate materials that are incompatible in other alloying methods.

Microalloying of transition metal silicides by mechanical activation and field-activated reaction

Solid reaction products with a dense nanocrystalline structure are formed from reactant particles with diameters in the nano-scale range by compacting the particles into a green body, then passing an electric current through the body causing Joule heating sufficient to initiate the reaction to form the reaction product while simultaneously applying pressure to the reacting body to density it to a density approaching the theoretical density of the pure product. Surprisingly, this process results in a reaction product that retains the nanocrystalline structure of the starting materials, despite the fact that a reaction has occurred and the materials have been subjected to highly stringent conditions of electric current, heat and pressure.

One-step synthesis and consolidation of nanophase materials

A method through which we can synthesize Functionally Graded Materials (FGM). Such materials are made so that their composition changes gradually from one point to another, such as in the example of gradient index (GRIN) optical components. A novel aspect of our method is the imposition of a centrifugal force during the combustion synthesis of composite materials for structural, optical, or electronic applications, with the result that the composition and the particle size of the metallic (or ceramic) component changes continuously and across the thickness of the product. We have prepared such FGM as ZrO.sub.2 +Ni, ZrO.sub.2 +Cu and Al.sub.2 O.sub.3 +Cu.

Centrifugal synthesis and processing of functionally graded materials

A method for preparing a highly dense product from a powdered mixture of reactants, whereby simultaneous application of a high current and pressure enables synthesis and densification of a variety of high temperature materials. The combination of field-activated combustion synthesis and the application of mechanical pressure was employed to produce dense MoSi.sub.2.

Simultaneous synthesis and densification by field-activated combustion

A method of combustion synthesis is provided wherein a relatively low field or voltage is applied to a precursor material prior to ignition. The field is at a voltage level effective to energize the material such that a combustion wave is propagated in a controlled manner through the material and without substantial Joule heating prior to ignition of the material, but below voltage levels necessary to initiate combustion. The precursor material, typically comprising a mixture of components which contain stoichiometric amounts of the elements in the desired final product in powder form, is compressed to form a compact having a desired relative density. This compact is subjected to an electric field or voltage at a suitable energy level to achieve the desired energizing of the material. The thus-treated compact is then ignited at a suitable location by, e.g., radiative energy applied from an ignition means. Once ignition occurs, the applied electric field serves to sustain the propagation of the combustion wave in a positive manner.

Field-assisted combustion synthesis

Transition metal carbonitrides (in particular, titanium carbonitride, TiC.sub.0.5 N.sub.0.5) are synthesized by a self-propagating reaction between the metal (e.g., titanium) and carbon in a nitrogen atmosphere. Complete conversion to the carbonitride phase is achieved with the addition of TiN as diluent and with a nitrogen pressure .gtoreq.0.6 MPa. Thermodynamic phase-stability calculations and experimental characterizations of quenched samples provided revealed that the mechanism of formation of the carbonitride is a two-step process. The first step involves the formation of the nonstoichiometric carbide, TiC.sub.0.5, and is followed by the formation of the product by the incorporation of nitrogen in the defect-structure carbide.

Synthesis of transition metal carbonitrides

A process is disclosed for forming a substantially pure monocrystalline layer of an implantable element in a monocrystalline substrate material by (a) selecting an implantable element and a monocrystalline substrate material to be implanted which, at the temperatures to be used, have limited mutual solubility in one another and do not form any intermediate phases with one another; (b) implanting a sufficient amount of the implantable element in the substrate material to permit formation of the desired substantially pure layer of the implantable element in the substrate material; and (c) annealing the implanted substrate material to form the desired layer. The annealing step may not be required if the desired layer was formed during the implantation. Also disclosed is an article made by the process.

Process for forming one or more substantially pure layers in substrate

A self-sustaining combustion synthesis process for producing hard, tough, lightweight, low exothermic potential product (LEPP)/high exothermic potential product (HEPP) composites is based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the LEPP and HEPP reactants. For lightweight products the composition must be relatively rich in the LEPP component. LEPP rich composites are obtained by varying the initial temperature of the reactants. The product is hard, porous material whose toughness can be enhanced by filling the pores with aluminum or other metal phases using a liquid metal infiltration process. The process can be extended to the formation of other composites having a low exothermic component.

Combustion synthesis of low exothermic component rich composites

A process is disclosed for forming a substantially pure layer of an implantable element in a substrate material by (a) selecting an implantable element and a substrate material to be implanted which, at the temperatures to be used, have limited mutual solubility in one another and do not form any intermediate phases with one another; (b) implanting a sufficient amount of the implantable element in the substrate material to permit formation of the desired substantially pure layer of the implantable element in the substrate material; and (c) annealing the implanted substrate material to form the desired layer. The annealing step may not be required if the desired layer was formed during the implantation.

Dense, finely grained composite materials comprising one or more ceramic phase or phase and one or more metallic and/or intermetallic phase or phases are produced by combustion synthesis. Spherical ceramic grains are homogeneously dispersed within the matrix. Methods are provided, which include the step of applying mechanical pressure during or immediately after ignition, by which the microstructures in the resulting composites can be controllably selected.

Dense, finely, grained composite materials

Grained composite materials prepared by combustion synthesis under

A self-sustaining combustion synthesis process for producing hard, tough, lightweight B.sub.4 C/TiB.sub.2 composites is based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the B.sub.4 C and TiB.sub.2 reactants. For lightweight products the composition must be relatively rich in the B.sub.4 C component. B.sub.4 C-rich composites are obtained by varying the initial temperature of the reactants. The product is hard, porous material whose toughness can be enhanced by filling the pores with aluminum or other metal phases using a liquid metal infiltration process. The process can be extended to the formation of other composites having a low exothermic component.

Growing community of inventors

Davis, CA, United States of America

Zuhair A Munir