Powder metallurgical production of a thermoelectric component
The invention relates to a method for producing a thermoelectric component or at least a semifinished version thereof, in which at least one thermoelectric active material in dry powder form is introduced into at least some of the holes of a perforated template. It addresses the problem of specifying a method which can be conducted in a particularly economically viable manner. The problem is solved by virtue of the active material remaining in the holes of the template, and the template filled with active material becoming a constituent of the thermoelectric component produced.
1. A method for producing a thermoelectric component or at least a semifinished version thereof, comprising:
injecting a dry powder of a first thermoelectric active material into a first portion of holes of a perforated template; and
injecting a dry powder of a second thermoelectric active material into a second portion of holes of the perforated template;
wherein
Seebeck coefficients of the first and second thermoelectric materials are different,
the active material remains in the holes and the template filled with the active material becomes a constituent of the thermoelectric component.
2. The method according to claim 1 ,
wherein
the active material is bismuth telluride, and
a median particle size (d 50) of a particle size distribution of the bismuth telluride is from 1 to 100 μm determined by laser diffraction.
3. The method according to claim 1 ,
wherein
the template consists of a thermally and electrically insulating material.
4. The method according to claim 3 ,
wherein
the template is a nonmetallic material, which is selected from the group consisting of polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), polyphenylsulphone (PPSU), polyphenylene sulphide (PPS), fumed silica, precipitated silica, metal oxides, and polyimide.
5. The method according to claim 3 ,
wherein
the template is a composite material comprising inorganic raw materials and binders,
the binder is silicone or silicone resin, and
the inorganic raw materials is selected from the group consisting of mica, perlite, phlogopite, and muscovite.
6. The method according to claim 1 ,
wherein
a thickness of the template is from 0.1 to 10 mm.
7. The method according to claim 1 ,
wherein
the holes of the perforated template extend essentially parallel to a surface normal of the template.
8. The method according to claim 1 ,
wherein
the holes have a circular or elliptical or polygonal cross section.
9. The method according to
wherein
a ratio of an equivalent diameter of the holes to a thickness of the template is from 0.1 to 10.
10. The method according to claim 1 ,
wherein
the method is conducted in at least one of an inert and a reducing atmosphere.
11. The method according to claim 10 ,
wherein
the atmosphere comprises 95% to 99.5% by volume of N 2 and 0.5% to 5% by volume of H 2 .
12. The method according to claim 1 , further comprising
supporting the template during the injection of the active material with a backing sheet which covers the ends of at least the holes that are to be injected at that time with active material.
13. The method according to claim 12 ,
wherein
the template is pressed against the backing sheet by a hold-down device during the injection of the active material, in such a way that the template is held between the hold-down device and backing sheet.
14. The method according to claim 1 ,
wherein
in a first operation, the first and second active materials are introduced from tubes which extend coaxially with the holes to be filled into the holes to be filled, and in a second operation the active material introduced into the holes is compressed with a ram which extends coaxially to the filled hole.
15. The method according to claim 14 ,
wherein
a cross-sectional area of the tubes which extend coaxially with the holes and/or a cross-sectional area of the ram corresponds essentially to the cross-sectional area of the hole.
16. The method according to claim 14 ,
wherein
a die is placed onto the template, and
a foil of barrier material is placed onto the die,
the ram punches a disc out of the foil at a cutting edge of the die, and
the disc is pressed onto the active material as barrier layer.
17. The method according to claim 1 , further comprising:
subjecting the active material compressed in the holes to a sintering operation; and
forming, electrical contacts between the active materials sintered in the holes at least on one side of the template.
18. The method according to claim 17 ,
wherein
the active material compressed in the holes is compacted by current sintering to form thermolegs.
19. The method according to claim 1 , further comprising:
applying a diffusion barrier to the active materials; and
optionally applying a contact layer to the diffusion barrier.
20. The method according to claim 1 , wherein
the dry powder active material comprises a pulverulent additive, and
the active material is compressed together with a pulverulent additive.