This application relates to tetrahedrite material. In one example, the tetrahedrite material can be used in a thermoelectric device. It would be recognized that the invention has a far broader range of applicability.
Tetrahedrite is a material that has been known for a long time in the mining industry as a naturally occurring mineral, but has only recently been appreciated for its thermoelectric properties, e.g., for use as a P-type thermoelectric material. Exemplary tetrahedrite materials that are known in the art include compounds of the formula (Cu,Ag)12-xMx(Sb,As,Te)4(S,Se)13, where M is a transition metal, or a suitable combination of transition metals, where x is between 0 and 2. Exemplary transition metals for use in tetrahedrite materials include any suitable combination of one or more of Zn, Fe, Mn, Hg, Co, Cd, and Ni, such as a combination of Zn and Ni.
For further details on exemplary tetrahedrite materials and exemplary methods of making such materials, see the following references, the entire contents of each of which are incorporated by reference herein:
International Publication No. WO 2014/008414, published Jan. 9, 2014 and entitled “THERMOELECTRIC MATERIALS BASED ON TETRAHEDRITE STRUCTURE FOR THERMOELECTRIC DEVICES;”
International Publication No. WO 2015/003157, published Jan. 8, 2015 and entitled “THERMOELECTRIC MATERIALS BASED ON TETRAHEDRITE STRUCTURE FOR THERMOELECTRIC DEVICES;”
Lu et al., “High performance thermoelectricity in earth-abundant compounds based on natural mineral tetrahedrites,” Advanced Energy Materials 3: 342-348 (2013);
Lu et al., “Natural mineral tetrahedrite as a direct source of thermoelectric materials,” Physical Chemistry Chemical Physics 15: 5762-5766 (2013); and
Lu et al., “Increasing the thermoelectric figure of merit of tetrahedrites by co-doping with nickel and zinc,” Chemistry of Materials 27: 408-413 (2015).
This application relates to tetrahedrite material. In one example, the tetrahedrite material can be used in a thermoelectric device. It would be recognized that the invention has a far broader range of applicability.
Under one aspect, a structure includes a tetrahedrite substrate; a first contact metal layer disposed over and in direct contact with the tetrahedrite substrate; and a second contact metal layer disposed over the first contact metal layer.
In some embodiments, the first contact metal layer includes a material selected from the group consisting of a refractory metal, a refractory metal alloyed with Ti or W, a stable sulfide, a stable sulfide alloyed with Ti or W, a stable refractory metal nitride, and a stable refractory metal carbide. The refractory metal can be selected from the group consisting of Mo, Nb, Ta, W, Re, Ti, V, Cr, Zr, Hf, Ru, Rh, Os, and Ir. The stable refractory metal nitride can be selected from the group consisting of TiN and TaN. The stable refractory metal carbide can be selected from the group consisting of TiC and WC. The stable sulfide can include La2S3.
In some embodiments, the second contact metal layer includes a noble metal. Additionally, or alternatively, the second contact metal layer can include a material selected from the group consisting of Au, Ag, Ni, Ni/Au, and Ni/Ag.
In some embodiments, the structure further includes a diffusion barrier metal layer disposed between the first contact metal layer and the second contact metal layer. The diffusion barrier metal layer can include a material selected from the group consisting of a refractory metal, a refractory metal alloyed with Ti or W, a stable sulfide, a stable nitride, a stable sulfide alloyed with Ti or W, and a stable nitride alloyed with Ti or W. The refractory metal can be selected from the group consisting of Mo, Nb, Ta, W, Re, Ti, V, Cr, Zr, Hf, Ru, Rh, Os, and Ir. The diffusion barrier metal layer can include a material selected from the group consisting of TiB2, Ni, and MCrAlY where M is Co, Ni, or Fe. Additionally, or alternatively, the first contact metal layer and diffusion barrier metal layer can be deposited in alternating layers.
In some embodiments, the structure can include a braze or solder in direct contact with the second contact metal layer.
In some embodiments, the first contact metal layer includes a material selected from the group consisting of Ti, Ta, Cr, W, Nb, TiN, Mo, CrNi, and TaN.
The second contact metal layer can include a material selected from the group consisting of Ag, Ni, Ni/Au, and Ni/Ag.
In some embodiments, the structure further includes a diffusion barrier metal layer disposed between the first contact metal layer and the second contact metal layer. The diffusion barrier metal layer can include a material selected from the group consisting of Ti, Ta, Cr, W, Nb, TiN, TaN, CrNi, and Mo. Additionally, or alternatively, the first contact metal layer and diffusion barrier metal layer can be deposited in alternating layers.
In some embodiments, the structure can include a braze or solder in direct contact with the second contact metal layer.
In some embodiments, the first contact metal layer includes a material selected from the group consisting of TiW, TiB2, Y, and MCrAlY where M is Co, Ni, or Fe.
In some embodiments, the second contact metal layer includes a material selected from the group consisting of Ni, Ag, and Au.
In some embodiments, the structure further includes a diffusion barrier metal layer disposed between the first contact metal layer and the second contact metal layer. The diffusion barrier metal layer can include a material selected from the group consisting of Ni, Ti, and W. Additionally, or alternatively, the first contact metal layer and diffusion barrier metal layer can be deposited in alternating layers.
In some embodiments, the structure can include a braze or solder in direct contact with the second contact metal layer.
Under another aspect, a thermoelectric device includes any of such structures.
Under another aspect, a method includes providing a tetrahedrite substrate; disposing a first contact metal layer over and in direct contact with the tetrahedrite substrate; and disposing a second contact metal layer over the first contact metal layer.
In some embodiments, at least one of the first contact metal layer and the second contact metal layer is disposed using physical vapor deposition or chemical vapor deposition. The physical vapor deposition can include sputtering or cathodic arc physical vapor deposition.
In some embodiments, said providing and disposing steps include co-sintering the first contact metal layer and the second contact metal layer in powder form with tetrahedrite powder.
In some embodiments, said providing and disposing steps include co-sintering thin foils of the first contact metal layer and the second contact metal layer with tetrahedrite powder.
In some embodiments, the first contact metal layer includes a material selected from the group consisting of a refractory metal, a refractory metal alloyed with Ti or W, a stable sulfide, a stable sulfide alloyed with Ti or W, a stable refractory metal nitride, and a stable refractory metal carbide. The refractory metal can be selected from the group consisting of Mo, Nb, Ta, W, Re, Ti, V, Cr, Zr, Hf, Ru, Rh, Os, and Ir. The stable refractory metal nitride can be selected from the group consisting of TiN and TaN. The stable refractory metal carbide can be selected from the group consisting of TiC and WC. The stable sulfide can include La2S3.
In some embodiments, the second contact metal layer includes a noble metal. In some embodiments, the second contact metal layer includes a material selected from the group consisting of Au, Ag, Ni, Ni/Au, and Ni/Ag.
In some embodiments, the method further includes disposing a diffusion barrier metal layer between the first contact metal layer and the second contact metal layer. In some embodiments, the diffusion barrier metal layer includes a material selected from the group consisting of a refractory metal, a refractory metal alloyed with Ti or W, a stable sulfide, a stable nitride, a stable sulfide alloyed with Ti or W, and a stable nitride alloyed with Ti or W. In some embodiments, the refractory metal is selected from the group consisting of Mo, Nb, Ta, W, Re, Ti, V, Cr, Zr, Hf, Ru, Rh, Os, and Ir. In some embodiments, the diffusion barrier metal layer includes a material selected from the group consisting of TiB2, Ni, and MCrAlY where M is Co, Ni, or Fe. Additionally, or alternatively, the first contact metal layer and diffusion barrier metal layer can be deposited in alternating layers.
In some embodiments, the method further includes disposing a braze or solder in direct contact with the second contact metal layer.
In some embodiments, the first contact metal layer includes a material selected from the group consisting of Ti, Ta, Cr, W, Nb, TiN, Mo, CrNi, and TaN.
In some embodiments, the second contact metal layer includes a material selected from the group consisting of Ag, Ni, Ni/Au, and Ni/Ag.
In some embodiments, the method further includes disposing a diffusion barrier metal layer between the first contact metal layer and the second contact metal layer.
In some embodiments, the diffusion barrier metal layer includes a material selected from the group consisting of Ti, Ta, Cr, W, Nb, TiN, TaN, CrNi, and Mo. Additionally, or alternatively, the first contact metal layer and diffusion barrier metal layer can be deposited in alternating layers.
In some embodiments, the method further includes disposing a braze or solder in direct contact with the second contact metal layer.
In some embodiments, the first contact metal layer includes a material selected from the group consisting of TiW, TiB2, Y, and MCrAlY where M is Co, Ni, or Fe.
In some embodiments, the second contact metal layer includes a material selected from the group consisting of Ni, Ag, and Au.
In some embodiments, the method further includes disposing a diffusion barrier metal layer between the first contact metal layer and the second contact metal layer. The diffusion barrier metal layer can include a material selected from the group consisting of Ni, Ti, and W. Additionally, or alternatively, the first contact metal layer and diffusion barrier metal layer can be deposited in alternating layers.
In some embodiments, the method further includes disposing a braze or solder in direct contact with the second contact metal layer.
Under another aspect, a method of making a thermoelectric device includes any of such methods.
This application relates to tetrahedrite material. In one example, the tetrahedrite material can be used in a thermoelectric device. It would be recognized that the invention has a far broader range of applicability.
Tetrahedrite is a material that has been known for a long time in the mining industry as a naturally occurring mineral, but has only recently been appreciated for its thermoelectric properties. Because this material has only recently been used as a thermoelectric material, it is believed that all previous work has focused on improving its thermoelectric properties and that no work had been done prior to this invention on making electrical and thermal contact to the tetrahedrite. It is believed that prior to this invention it was not possible to actually use tetrahedrite in a thermoelectric system because it could not be electrically connected and/or would not survive heating to operation temperatures for more than a few hours. Embodiments of the invention described here facilitates or enables electrical and thermal contact to the tetrahedrite, even at operating temperatures for long periods of time, thus making the tetrahedrite commercially viable.
Making electrical contact to the tetrahedrite is believed not to be obvious because most metals fail to make contact to tetrahedrite due to one or more of several issues. Without wishing to be bound by any theory, it is believed that in one exemplary failure mode, certain metals react with the tetrahedrite and disappear into the material, destroying the thermoelectric properties by forming undesirable phases. Without wishing to be bound by any theory, it is believed that in another exemplary failure mode, certain metals can react with sulfur or antimony in the tetrahedrite to form a sulfur or antimony deficient region of tetrahedrite as well as a metal sulfide or metal antimonide layer. Without wishing to be bound by any theory, it is believed that certain metal sulfide or certain metal antimonide layers are detrimental since they are most often non-conductive, as it can be difficult to control the composition and/or phase and achieve a conductive sulfide or antimonide, and they can also cause adhesion problems since sulfides and antimonides tend to be chalky and/or brittle in consistency and/or can cause scaling and/or flaking. Without wishing to be bound by any theory, it is believed that in a third exemplary failure mode, certain metal layers do not adhere to the tetrahedrite surface. Without wishing to be bound by any theory, because of any combination of these three failure modes and potential difficulty in predicting which metals may succumb to these failures, choosing the first contact metal layer is believed to be non obvious.
An exemplary use or purpose of the present invention is to create contact with tetrahedrite material such that electrical (ohmic), thermal, and mechanical/metallurgical connection to the thermoelectric (TE) material (tetrahedrite material) between the material and a package or connector (shunt) can be achieved, as well as to create a diffusion barrier to inhibit or prevent the tetrahedrite from reacting with elements in the solder or braze or joining or connector (shunt) material.
Another exemplary use or purpose of the present invention is to create ohmic (e.g., low-resistance ohmic) and thermal contact with tetrahedrite material such that electrical and thermal connection to the material can be achieved, as well as create a diffusion barrier to inhibit or prevent the tetrahedrite from reacting with elements in the solder or braze or connector (shunt) materials and vice versa. Additionally or alternatively, and in some circumstances just as importantly, another exemplary use or purpose is to enable long term high temperature operation without a change in electrical or thermal interface resistance.
In some embodiments, the present invention specifies a recipe for the metallization of tetrahedrite and enables the use of tetrahedrite as, for example, a thermoelectric material, optionally over long periods of time at high temperatures. By metallization of tetrahedrite, or metalized tetrahedrite, it is meant that one or more layers that include metal are disposed on the tetrahedrite so as to provide stable thermal and electrical contact to the tetrahedrite. Without wishing to be bound by any theory, it is believed that without embodiments of the present invention, tetrahedrite is not commercially useful (e.g., as a thermoelectric material) because electrical and thermal contact to the material is insufficient, e.g., would be insufficient and would degrade significantly over time. It is believed that power and efficiency from the associated device (without implementation of the present tetrahedrite metallization) would be minimal or insufficient and/or degrade over time.
Some embodiments of the present invention include, or are composed of, a multilayer metal structure in which the first layer is designed to contact tetrahedrite, an optional intermediate layer serves as a diffusion barrier, and the second layer contacts a braze/solder or other joining material. For example,
Illustratively, in some embodiments, first contact metal layer 102 includes a material selected from the group consisting of Ti, Ta, Cr, W, Nb, TiN, Mo, CrNi, and TaN, e.g., is or consists essentially of Ti, Ta, Cr, W, Nb, TiN, Mo, CrNi, or TaN. Illustratively, optional diffusion barrier metal layer 103 is disposed between the first contact metal layer and the second contact metal layer. Illustratively, diffusion barrier metal layer 103 includes a material selected from the group consisting of Ti, Ta, Cr, W, Nb, TiN, TaN, CrNi, and Mo, e.g., is or consists essentially of Ti, Ta, Cr, W, Nb, TiN, TaN, CrNi, or Mo. Illustratively, second contact metal layer 104 includes a material selected from the group consisting of Ag, Au, Ni, Ni/Au, and Ni/Ag, e.g., is or consists essentially of Ag or Au or Ni or Ni/Au of Ni/Ag or Ni/Au or Ni/Ag. In another embodiment, or in any embodiment using any suitable combination of any such materials or other materials, first contact metal layer 102 and diffusion barrier metal layer 103 are deposited in alternating layers in a manner such as described below with reference to
Illustratively, in some embodiments, first contact metal layer 102 is, consists essentially of, or includes a material selected from the group consisting of TiW, TiB2, Y, and MCrAlY where M is Co, Ni, or Fe, e.g., is TiW, TiB2, MCrAlY (where M is Co, Ni, or Fe) or Y. Illustratively, optional diffusion barrier metal layer 103 is disposed between first contact metal layer 102 and second contact metal layer 104. Illustratively, diffusion barrier metal layer 103 includes a material selected from the group consisting of Ni, Ti, and W, e.g., is or consists essentially of Ni, Ti, or W. Illustratively, second contact metal layer 104 includes a material selected from the group consisting of Ni, Ag, and Au, e.g., is or consists essentially of Ni, Ag, and/or Au. In another embodiment, or in any embodiment using any suitable combination of any such materials or other materials, first contact metal layer 102 and diffusion barrier metal layer 103 are deposited in alternating layers in a manner such as described below with reference to
Illustratively, in some embodiments, first contact metal layer 102 includes a material selected from the group consisting of a refractory metal, a refractory metal alloyed with Ti or W, a stable sulfide, a stable sulfide alloyed with Ti or W, a stable refractory metal nitride, and a stable refractory metal carbide, e.g., is or consists essentially of a refractory metal, a refractory metal alloyed with Ti or W, a stable sulfide, a stable sulfide alloyed with Ti or W, a stable refractory metal nitride, or a stable refractory metal carbide. Illustratively, the alloys can have weight percents of Ti or Win the range of about 1-99%, or 2-50%, or 5-20%. In some embodiments, the refractory metal is selected from the group consisting of Mo, Nb, Ta, W, Re, Ti, V, Cr, Zr, Hf, Ru, Rh, Os, and Ir. In some embodiments, the stable refractory metal nitride is selected from the group consisting of TiN and TaN. In some embodiments, the stable refractory metal carbide is selected from the group consisting of TiC and WC. In some embodiments, the stable sulfide includes La2S3. Optionally, diffusion barrier metal layer 103 is disposed between the first contact metal layer and the second contact metal layer. Illustratively, diffusion barrier metal layer 103 can include a material selected from the group consisting of a refractory metal, a refractory metal alloyed with Ti or W, a stable sulfide, a stable nitride, a stable sulfide alloyed with Ti or W, and a stable nitride alloyed with Ti or W, e.g., is or consists essentially of a refractory metal, a refractory metal alloyed with Ti or W, a stable sulfide, a stable nitride, a stable sulfide alloyed with Ti or W, or a stable nitride alloyed with Ti or W. Illustratively, the refractory metal is selected from the group consisting of Mo, Nb, Ta, W, Re, Ti, V, Cr, Zr, Hf, Ru, Rh, Os, and Ir. Illustratively, diffusion barrier metal layer 103 is, consists essentially of, or includes a material selected from the group consisting of TiB2, Ni, and MCrAlY where M is Co, Ni, or Fe. Illustratively, second contact metal layer 104 includes a noble metal, e.g., is or consists essentially of a noble metal. Noble metals are those generally considered to be resistant to corrosion and oxidation in moist air, and include Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au, e.g., include Au, Ag, Pd, and Pt. In some embodiments, second contact metal layer 104 includes a material selected from the group consisting of Au, Ag, Ni, Ni/Au, and Ni/Ag, e.g., is or consists essentially of Au, Ag, Ni, Ni/Au, or Ni/Ag. In another embodiment, or in any embodiment using any suitable combination of any such materials or other materials, first contact metal layer 102 and diffusion barrier metal layer 103 are deposited in alternating layers in a manner such as described below with reference to
Other configurations suitably can be used. For example, as noted above, first contact metal layer 102 optionally can serve as a diffusion barrier.
In another example, as noted above, first contact metal layer 102 and diffusion barrier metal layer 103 can both be very thin and can be deposited in alternating layers for several or tens or hundreds of layers before adding second contact metal layer 104.
Any of the structures provided herein, e.g., such as described above with reference to
Thermoelectric device 20 can be configured to generate an electric current flowing between first electrode 21 and second electrode 24 through N-type thermoelectric material 24 based on the first and second electrodes being at different temperatures than one another. For example, first electrode 21 can be in thermal and electrical contact with N-type thermoelectric material 24, with structure 25, and with a first body, e.g., heat source 26. Second electrode 22 can be in thermal and electrical contact with N-type thermoelectric material 24, and with a second body, e.g., heat sink 27. Third electrode 23 can be in thermal and electrical contact with structure 25 and with the second body, e.g., heat sink 27. Accordingly, N-type thermoelectric material 24 and structure 25 can be configured electrically in series with one another, and thermally in parallel with one another between the first body, e.g., heat source 26, and the second body, e.g., heat sink 27. Note that heat source 26 and heat sink 27 can be, but need not necessarily be, considered to be part of thermoelectric device 20.
N-type thermoelectric material 24 can be considered to provide an N-type thermoelectric leg of device 20, and structure 25 can be considered to provide a P-type thermoelectric leg of device 20. Responsive to a temperature differential or gradient between the first body, e.g., heat source 26, and the second body, e.g., heat sink 27, electrons (e−) flow from first electrode 21 to second electrode 22 through first N-type thermoelectric material 24, and holes (h+) flow from first electrode 21 to third electrode 23 through structure 25, thus generating a current. In one illustrative example, N-type thermoelectric material 24 and structure 25 are connected electrically to each other and thermally to first body 26, e.g., heat source, via first electrode 21. As heat flows from first body 26 to second body 27, e.g., heat sink, through N-type thermoelectric material 24 and structure 25 in parallel, negative electrons travel from the hot to cold end of the N-type thermoelectric material 24 and positive holes travel from the hot to cold end of structure 25. An electrical potential or voltage between electrodes 28 and 29 is created by having each material leg in a temperature gradient with electric current flow created as the N-type thermoelectric material 24 and structure 25 are connected together electrically in series and thermally in parallel.
The current generated by device 20 can be utilized in any suitable manner. For example, second electrode 22 can be coupled to anode 28 via a suitable connection, e.g., an electrical conductor, and third electrode 23 can be coupled to cathode 29 via a suitable connection, e.g., an electrical conductor. Anode 28 and cathode 29 can be connected to any suitable electrical device so as to provide a voltage potential or current to such device. Exemplary electrical devices include batteries, capacitors, motors, and the like. For example,
Other types of thermoelectric devices suitably can include the present metalized tetrahedrite materials. For example,
Thermoelectric device 20″ can be configured to pump heat from first electrode 21″ to second electrode 24″ through N-type thermoelectric material 24″ based on a voltage applied between the first and second electrodes. For example, first electrode 21″ can be in thermal and electrical contact with N-type thermoelectric material 24″, with structure 25″, and with a first body 26″ from which heat is to be pumped. Second electrode 22″ can be in thermal and electrical contact with N-type thermoelectric material 24″, and with a second body 27″ to which heat is to be pumped. Third electrode 23″ can be in thermal and electrical contact with structure 25″ and with the second body 27″ to which heat is to be pumped. Accordingly, N-type thermoelectric material 24″ and structure 25″ can be configured electrically in series with one another, and thermally in parallel with one another between the first body 26″ from which heat is to be pumped, and the second body 27″ to which heat is to be pumped. Note that first body 26″ and second body 27″ can be, but need not necessarily be, considered to be part of thermoelectric device 20″.
In the exemplary embodiment illustrated in
As discussed above and as further emphasized here,
Structures such as described herein with reference to
Steps 301, 302, and 303 can be performed in any suitable order and using any suitable combination of techniques and materials. For example, in some embodiments, at least one of the first contact metal layer and the second contact metal layer is disposed using physical vapor deposition (PVD) or chemical vapor deposition (CVD); that is, one or both of steps 302 and steps 303 can be used to dispose one or both of the first contact metal layer and the second contact metal layer on a provided tetrahedrite substrate using PVD or CVD. Methods of providing tetrahedrite substrates (301) are known in the art. Illustratively, the physical vapor deposition can include sputtering or cathodic arc physical vapor deposition. Additionally, or alternatively, the physical vapor deposition can include evaporation. Other exemplary methods of disposing one or both of first contact metal layer and second contact metal layer on the tetrahedrite substrate include, but are not limited to, plating, cladding, and electro-deposition.
In some embodiments, the providing (301) and disposing (302, 303) steps include co-sintering the first contact metal layer and the second contact metal layer in powder form with tetrahedrite powder. For example, such an approach can involve co-sintering the above metals in powder form with tetrahedrite powder in the middle of a sandwich structure, in which case an additive might be mixed with the metal powder to lower the melting point of the metal. Illustratively, a powdered precursor of the tetrahedrite can be loaded into a sintering die, followed by a powdered precursor of the first contact metal layer and a powder precursor of the second contact metal layer. Punches then can be assembled to the sintering die and heat and/or a load can be applied to the die so as to form a structure including the tetrahedrite, the first contact metal layer, and the second contact metal layer. Optionally, before loading the powdered precursor of the tetrahedrite into the sintering die, a powder precursor of the second contact metal layer followed by a powdered precursor of the first contact metal layer can be disposed in the sintering die so as to provide a structure that includes first and second contact metal layers disposed on both sides of the tetrahedrite material.
In some embodiments, the providing (301) and disposing (302, 303) steps include co-sintering thin foils of the first contact metal layer and the second contact metal layer with tetrahedrite powder. For example, a non-limiting embodiment can take the form of co-sintering thin foils of the above metals with tetrahedrite powder in the middle. Illustratively, a powdered precursor of the tetrahedrite can be loaded into a sintering die, followed by a foil of the first contact metal layer and a foil of the second contact metal layer. Punches then can be assembled to the sintering die and heat and/or a load can be applied to the die so as to form a structure including the tetrahedrite, the first contact metal layer, and the second contact metal layer. Optionally, before loading the powdered precursor of the tetrahedrite into the sintering die, a foil of the second contact metal layer followed by a foil of the first contact metal layer can be disposed in the sintering die so as to provide a structure that includes first and second contact metal layers disposed on both sides of the tetrahedrite material.
Note that in some embodiments, surface preparation of metal foils and/or of TE materials (e.g., tetrahedrite) before deposition of metal potentially can be relevant, or a critical factor. For example, foils can be sanded or polished to achieve a desired surface roughness or remove oxides, or both. Additionally, or alternatively, foils can be rinsed in a solvent to dissolve oils prior to bonding or etched in acid to remove oxides of sulfides. In some embodiments, or another embodiment, particle size of the TE material (e.g., tetrahedrite) potentially can be relevant, or a critical factor. For example, the particle sizes of the thermoelectric material can be selected or optimized so as to suit the foil or powder with which it is being cosintered. For example, it can be useful that powders being cosintered have similar particle size as one another. In some embodiments, or another embodiment, density of the TE material (e.g., tetrahedrite) potentially can be relevant, or a critical factor. For example, it can be useful that the tetrahedrite and metal layers are sufficiently dense to function properly.
In some embodiments, process steps to attain metalized thermoelectric material are, or include:
Produce tetrahedrite powder→sinter powder into bulk material→polish bulk pellet→deposit metallization layer(s).
In some embodiments, for the “deposit metallization layer(s)” block, exemplary methods of deposition could be, or include, sputtering, cathodic arc physical vapor deposition (PVD), or any other PVD process. Metal thicknesses could range, for example, from 50 nanometers to 10 microns depending on how the metallic layers are organized.
Methods such as provided herein, e.g., such as described with reference to
As another example, the first contact metal layer can be, can consist essentially of, or can include a material selected from the group consisting of TiW, TiB2, Y, and MCrAlY where M is Co, Ni, or Fe. Additionally, or alternatively, the second contact metal layer can be, can consist essentially of, or can include a material selected from the group consisting of Ni, Ag, and Au. Additionally, or alternatively, the method can include disposing a diffusion barrier metal layer between the first contact metal layer and the second contact metal layer, e.g., in a manner such as described above. In some embodiments, the diffusion barrier metal layer can be, can consist essentially of, or can include a material selected from the group consisting of Ni, Ti, and W. Additionally, or alternatively, the first contact metal layer and diffusion barrier metal layer can be deposited in alternating layers, e.g., in a manner such as described above. Additionally, or alternatively, the method further can include disposing a braze or solder in direct contact with the second contact metal layer.
As another example, the first contact metal layer can be, can consist essentially of, or can include a material selected from the group consisting of a refractory metal, a refractory metal alloyed with Ti or W, a stable sulfide, a stable sulfide alloyed with Ti or W, a stable refractory metal nitride, and a stable refractory metal carbide. In some embodiments, the refractory metal is selected from the group consisting of Mo, Nb, Ta, W, Re, Ti, V, Cr, Zr, Hf, Ru, Rh, Os, and Ir. In some embodiments, the stable refractory metal nitride is selected from the group consisting of TiN and TaN. In some embodiments, the stable refractory metal carbide is selected from the group consisting of TiC and WC. In some embodiments, the stable sulfide includes La2S3. Additionally, or alternatively, the second contact metal layer can be, can consist essentially of, or can include a noble metal. Additionally, or alternatively, the second contact metal layer can be, can consist essentially of, or can include a material selected from the group consisting of Au, Ag, Ni, Ni/Au, and Ni/Ag. Additionally, or alternatively, the method further can include disposing a diffusion barrier metal layer between the first contact metal layer and the second contact metal layer, e.g., in a manner such as described above. In some embodiments, the diffusion barrier metal layer be, can consist essentially of, or can include a material selected from the group consisting of a refractory metal, a refractory metal alloyed with Ti or W, a stable sulfide, a stable nitride, a stable sulfide alloyed with Ti or W, and a stable nitride alloyed with Ti or W. In some embodiments, the refractory metal is selected from the group consisting of Mo, Nb, Ta, W, Re, Ti, V, Cr, Zr, Hf, Ru, Rh, Os, and Ir. In some embodiments, the diffusion barrier metal layer includes a material selected from the group consisting of TiB2, Ni, and MCrAlY where M is Co, Ni, or Fe. Additionally, or alternatively, the first contact metal layer and diffusion barrier metal layer are deposited in alternating layers, e.g., in a manner such as described above. Additionally, or alternatively, the method further can include disposing a braze or solder in direct contact with the second contact metal layer.
Any of the methods provided herein can be included within a method of making a thermoelectric device, such as a thermoelectric device illustrated in any of
The following examples are intended to be purely illustrative, and not limiting of the present invention.
In a first non-limiting example, structure 100 illustrated in
The first through fourth examples were subjected to heating tests in which the resulting metallized tetrahedrite structures were heated to 250-400° C. for a length of time ranging from 1 hour to several hundred hours in vacuum or air. Experiments were conducted where metallized tetrahedrite structures were heated prior to soldering them to metal shunts to measure through-plane resistance as well as where the metallized tetrahedrite structures were bonded to metal parts prior to heating and resistance was measured before and after heating. A structure was considered to pass the heating test if the resistance of the structure was less than 10% higher than the resistance of non-metalized tetrahedrite. The first through fourth examples were considered to pass the heating test after 15 hours or more at 400° C. The following table lists metallization stacks that survived at least 15 hours at 400° C. in air:
According to some embodiments, a structure includes a tetrahedrite substrate; a first contact metal layer disposed over and in direct contact with the tetrahedrite substrate; and a second contact metal layer disposed over the first contact metal layer. In one example, the structure is described above with reference to
According to some embodiments, a thermoelectric device includes such a structure. In one example, the thermoelectric device is described above with reference to
According to some embodiments, a method includes providing a tetrahedrite substrate; disposing a first contact metal layer over and in direct contact with the tetrahedrite substrate; and disposing a second contact metal layer over the first contact metal layer. In one example, the method is described above with reference to
According to some embodiments, a method of making a thermoelectric device includes such a method. In one example, the method is described above with reference to
Although specific embodiments of the present invention have been described, it will be understood by those of skill in the art that there are other embodiments that are equivalent to the described embodiments. For example, various embodiments and/or examples of the present invention can be combined. Accordingly, it is to be understood that the invention is not to be limited by the specific illustrated embodiments, but only by the scope of the appended claims.
This application claims the benefit of the following applications, the entire contents of each of which are incorporated by reference herein: U.S. Provisional Patent Application No. 62/098,945, filed Dec. 31, 2014 and entitled “ELECTRICAL AND THERMAL CONTACTS FOR BULK TETRAHEDRITE;” AND U.S. Provisional Patent Application No. 62/208,954, filed Aug. 24, 2015 and entitled “ELECTRICAL AND THERMAL CONTACTS FOR BULK TETRAHEDRITE MATERIAL.”
Number | Date | Country | |
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62098945 | Dec 2014 | US | |
62208954 | Aug 2015 | US |