Hi-z Technology, Inc.

Hi-z Corporation

Ga Technologies, Inc.

Other

The United States of America As Represented by the United States

General Atomic Company

Hi-2 Technology, Inc.

Norbert B Elsner

John Claude Bass

Saeid Ghamaty

Daniel T Allen

John H Norman

George H Reynolds

Frederick Arlen Leavitt

Saied Ghamaty

Fred Leavitt

Ian Sidney R Clark

Stanley Zalkind

Anthony Donaldson

Fredrick A Leavitt

Clyde H Shearer

Charles C Morris

Frederick A Leavitt

John W Mccoy

A super-lattice thermoelectric device. The device is comprised of p-legs and n-legs, each leg being comprised of a large number of very thin alternating layers of two materials with differing electron band gaps. The n-legs in the device are comprised of alternating layers of Si and SiC. The p-legs are comprised of alternating layers of BC and BC. In preferred embodiments the layers are about 100 angstroms thick. Thermoelectric modules made according to the present invention are useful for both cooling applications as well as electric power generation. This preferred embodiment is a thermoelectric 10&#xd7;10 egg crate type module about 6 cm&#xd7;6 cm&#xd7;0.76 cm designed to produce 70 Watts with a temperature difference of 300 degrees C. with a module efficiency of about 30 percent. The module has 98 active thermoelectric legs, with each leg having more than 3 million super-lattice layers.

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A super-lattice thermoelectric device. The device includes p-legs and n-legs, each leg having a large number of alternating layers of two materials with differing electron band gaps. The n-legs in the device are comprised of alternating layers of silicon and silicon germanium. The p-legs includes alternating layers of BC and BC. In preferred embodiments the layers are about 100 angstroms thick. Applicants have fabricated and tested a first Si/SiGe (n-leg) and BC/BC (p-leg) quantum well thermocouple. Each leg was only 11 microns thick on a 5 micron Si substrate. Nevertheless, in actual tests the thermocouple operated with an amazing efficiency of 14 percent with a Tof 250 degrees C. Thermoelectric modules made according to the present invention are useful for both cooling applications as well as electric power generation. This preferred embodiment is a thermoelectric 10&#xd7;10 egg crate type module about 6 cm&#xd7;6 cm&#xd7;0.76 cm designed to produce 70 Watts with a temperature difference of 300 degrees C with a module efficiency of about 30 percent.

Thermoelectric module with Si/SiGe and B4C/B9C super-lattice legs

A superlattice thermoelectric device. The device includes p-legs and n-legs, each leg includes a large number of at least two different very thin alternating layers of elements. The n-legs in the device includes alternating layers of silicon and silicon carbide. In preferred embodiments p-legs include a superlatice of B-C layers, with alternating layers of different stoichiometric forms of B-C. This preferred embodiment is designed to produce 20 Watts with a temperature difference of 300 degrees C. with a module efficiency of about 30 percent. The module is about 1 cm thick with a cross section area of about 7 cm and has about 10,000 sets of n and p legs each set of legs being about 55 microns thick and having about 5,000 very thin layers (each layer about 10 nm thick).

Thermoelectric device with Si/SiC superlattice N-legs

A low-cost thermoelectric module utilizing a greatly reduced quantity of thermoelectric material as compared to similar prior art thermoelectric modules. An egg crate design containing thermoelectric elements is utilized in the present invention. However, the walls of the egg crate in the parts of the module separating the thermoelectric elements are made thick so that the total cross sectional area of the elements is less than 75 percent of the total module cross sectional area. The spaces above and below the elements are filled with a high heat and electric conducting material such as aluminum. This produces funnel-shaped conductors funneling heat and electric current into and out of each of the thermoelectric elements. The payoff to this approach is that the heat flux through the hot and cold module surfaces can be maintained while producing the same power output with about half the thermoelectric material or less. Avoiding any significant increase in heat flux through the module surface means avoiding increases in temperature drops normally encountered at the module surfaces.

Thermoelectric module with funneled heat flux

A powder injection molding and infiltration process. A powder of a skeleton material having a relatively high melting point is mixed with a composite binder to form a mold mixture. The composite binder is comprised of at least two binder materials. The mold mixture is molded into a desired shape in a mold device to produce a molded part. The composite binder is then removed to produce voids in the molded part and the voids are filled by infiltrating an infiltrant comprised of an infiltrant material having a relatively low melting point to produce a composite molded part. In a preferred embodiment the skeleton material is TiB,and the infiltrant material is aluminum and the composite binder is comprised of a plastic and a wax. In this embodiment the wax portion of the composite binder is removed using a solvent and the plastic is removed during the infiltration step. The resulting composite part has a TiB,skeleton with voids substantially filled with aluminum. This process is especially useful for making light and strong parts with complex shapes such as golf club heads, tools, cutting implements, thermal management products, rocket motor components and bicycle parts. In another preferred embodiment, a golf club head is comprised of three parts: an non-sintered TiB,part for the body of the head, a sintered TiB,part for the striking surface of the head, and a heavy tungsten part to provide weight for the head. In this embodiment, the aluminum infiltrant substantially fills the voids in all three parts to create a golf club head with optimum characteristics.

Powder injection molding and infiltration process

A combustion heat powered portable electronic device. At least one thermoelectric module is sandwiched between a hot block heated by a combustion heat source and a cold-side heat sink and provides electric power to a portable electronic device from the temperature difference. An electric circuit provides power for purposes of operating the portable electronic device either directly or indirectly by charging a rechargeable battery which in turn provides power to the electronic device. In a preferred embodiment the combustion heat source is a catalytic combustion unit. The hot block and/or cold side heat sink can be integrated into a single unit with the thermoelectric module. In a preferred embodiment the cold side heat sink is cooled by fins cooled by air driven by a forced air fan powered by the thermoelectric module.

Combustion heat powered portable electronic device

A miniature thermoelectric module for generating electric power from low power heat sources in the range of a fraction of a Watt to a few Watts. The module comprises an array of thermoelectric elements, each element having a cross section of less than 0.001 square inch and a length of at least 0.25 inch. The elements are separated from each other with a polyimide insulator sheet in a checkerboard array. In a preferred embodiment, the modules are fabricated by hot pressing a stack of alternating plates of p and n doped thin plates all separated by thin sheets of a polyimide insulator material to produce a pressed stack of p and n doped layers. The stack is then sliced to produce layered plates which are then stacked with insulating polyimide layers positioned between the layered plates to produce the checkerboard array of p and n thermoelectric elements. Contacts are applied to electrically connect all of the elements. In a preferred embodiment, the contacts are applied by first sputtering a thin layer of gold, then welding gold tabs, and then blasting away the excess sputtered gold. In one preferred embodiment, the contacts connect all of the elements in series. In another preferred embodiment, the elements are connected in a series-parallel circuit. In a preferred embodiment, the module is utilized in a generation unit with a 1-Watt radioactive heat source to produce about 40 mW of electric power at 5.5 Volts which is converted to 12 Volts with a DC to DC converter.

Miniature milliwatt electric power generator

Thermoelectric elements for use in a thermoelectric device. The thermoelectric elements have a very large number of alternating layers of semiconductor material deposited on a very thin organic substrate. The layers of semiconductor material alternate between barrier semiconductor material and conducting semiconductor material creating quantum wells within the thin layers of conducting semiconductor material. The conducting semiconductor material is doped to create conducting properties. The substrate preferably should be very thin, a very good thermal and electrical insulator with good thermal stability and strong and flexible.

Quantum well thermoelectric material on organic substrate

Thermoelectric elements for use in a thermoelectric device. The thermoelectric elements have a very large number of alternating layers of semiconductor material deposited on a very thin flexible substrate. The layers of semiconductor material alternate between barrier semiconductor material and conducting semiconductor material creating quantum wells within the thin layers of conducting semiconductor material. The conducting semiconductor material is doped to create conducting properties. The substrate preferably should be very thin, a very good thermal and electrical insulator with good thermal stability and strong and flexible. In a preferred embodiment, the thin organic substrate is a thin polyimide film (specifically Kapton.RTM.) coated with an even thinner film of crystalline silicon. The substrate is about 0.3 mills (127 microns) thick. The crystalline silicon layer is about 0.1 micron thick. This embodiment includes on each side of the thin Kapton.RTM. substrate about 3,000 alternating layers of silicon and silicon-germanium, each layer being about 100 .ANG. and the total thickness of the layers being about 30 microns. Preferably, the silicon layer is applied in an amorphous form and heated to about 350.degree. C. to 375.degree. C. to crystallize it. In other preferred embodiments, the substrate material is thin films of other organic materials or thin films of inorganic materials such as silicon.

Quantum well thermoelectric material on thin flexible substrate

A thermoelectric module having a gapless insulating eggcrate providing insulated spaces for a large number of p-type and n-type thermoelectric elements. The absence of gaps in the walls of the spaces virtually eliminates the possibility of interwall shorts between the elements. Electrical connections on both the hot and cold sides of the module electrically connect the elements in series or in parallel as desired. Usually, most or all of the elements will be connected in series. In a preferred embodiment, the gapless eggcrate is formed from a high temperature plastic. In a preferred embodiment, two lead wires are added before adding the hot and cold side electrical connections. In this embodiment, electrical connections on the hot and cold sides comprise a thin layer of molybdenum and a coating of aluminum over the molybdenum. The surfaces are ground down to expose the insulating eggcrate walls except where connections between the elements are desired. In this preferred embodiment a seal is then applied over both the hot and cold surfaces. The seal preferably is comprised of a very thin electrically insulating layer and over this electrically insulating layer a thin metal layer is provided.

Thermoelectric module with gapless eggcrate

A method for fabricating a thermoelectric module with thermoelectric elements installed in an gapless eggcrate. This gapless eggcrate provides insulated spaces for a large number of p-type and n-type thermoelectric elements. The absence of gaps in the walls of the spaces virtually eliminates the possibility of interwall shorts between the elements. Thermoelectric elements, both p-type and n-type, are inserted into the insulated spaces in the gapless eggcrate to provide the desired thermoelectric effects . Electrical connections are established on both the hot and cold sides of the module to connect the thermoelectric elements in series or parallel as desired. Normally, most or all of the elements will be connected in series. In a preferred embodiment the gapless eggcrate is formed from a high temperature plastic. P-type thermoelectric material is extruded and then sliced to form p-type thermoelectric elements, and n-type thermoelectric material is extruded and sliced to form n-type thermoelectric elements. The thermoelectric elements are loaded in the eggcrate in an arrangement to put them all in series when a metal spray is applied to the hot and cold sides. Two electrical leads are applied and electrical connections on both the hot and cold sides are provided using a metal thermal spray technique. A thin layer of molybdenum is sprayed on one of the surfaces and then a coating of aluminum is sprayed over the molybdenum. These steps are repeated for the other side. Then the surfaces are ground down to expose the insulating eggcrate walls except where connections between the elements are desired. A seal is then applied over both the hot and cold surfaces. The seal preferably is very thin electrically insulating layer and over this layer a layer of aluminum is provided.

Method for fabricating a thermoelectric module with gapless eggcrate

A composition having an empirical formula MB.sub.2-z +N, wherein 0&lt;z&lt;0.10 and M is selected from the group consisting of Zr, Hf and Ti, wherein N is selected from a group consisting of Cu, Au and Ag and wherein the MB.sub.2-z defines a ceramic matrix structure defining a volume with void spaces comprising at least 10 percent of the volume of the matrix structure and the N occupies at least 70 percent, by volume, of the void spaces. A preferred method of making the composition is a two step process: First, ZrB.sub.2 powder (which preferably is slightly enriched in Zr is vacuum hot pressed at a hot pressing temperature of about 2150 degrees C. to create a ceramic matrix having a density of about 68 percent. Second, the ceramic matrix is heated in a pool of copper at a vacuum and at an infiltration temperature of about 1700 degrees C. to permit copper from the pool to infiltrate the ceramic matrix.

Metal infiltrated ceramic electrical conductor

A thermoelectric element having a very large number of alternating layers of semiconductor material. The alternating layers all have the same crystalline structure. The inventors have demonstrated that materials produced in accordance with this invention provide figures of merit more than six times that of prior art thermoelectric materials. A preferred embodiment is a superlattice of Si, as a barrier material, and SiGe, as a conducting material, both of which have the same cubic structure. Another preferred embodiment is a superlattice of B--C alloys, the layers of which would be different stoichiometric forms of B--C but in all cases the crystalline structure would be alpha 0. In a preferred embodiment the layers are grown under conditions as to cause them to be strained at their operating temperature range in order to improve the thermoelectric properties.

Superlattice quantum well material

A multi-layer superlattice quantum well thermoelectric material using materials for the layers having the same crystalline structure. A preferred embodiment is a superlattice of Si and SiGe, both of which have a cubic structure. Another preferred embodiment is a superlattice of B-C alloys, the layers of which would be different stoichometric forms of B-C but in all cases the crystalline structure would be alpha rhombohedral.

Superlattice quantum well thermoelectric material

A process and related compositions for lowering the electrical resistivity of ZrB.sub.2 are described. In a preferred embodiment, ZrH.sub.2 or Zr powder is blended with the ZrB.sub.2 powder and the composite is vacuum hot pressed at 2100.degree. C. The elemental Zr so formed can be beneficial by gettering impurities such as oxygen, nitrogen, and carbon, and by altering the overall ZrB.sub.2 stoichiometry, e.g., to ZrB.sub.1.97. Excess Zr is present in the matrix as a finely dispersed material. A variety of dopant materials can also be used to alter the electrical, thermal, and mechanical properties. Samples exhibiting this Zr-rich second phase exhibit lower electrical resistivities, higher thermal conductivities, better thermal shock resistance.

Growing community of inventors

La Jolla, CA, United States of America

Norbert B Elsner