Rational method for the powder metallurgical production of thermoelectric components

Patent metadata

Field	Value
Publication number	US-11056633-B2
Application number	US-201716069310-A
Country	US
Kind code	B2
Filing date	Jan 6, 2017
Priority date	Jan 21, 2016
Publication date	Jul 6, 2021
Grant date	Jul 6, 2021

Abstract

A method can produce a thermoelectric component or at least a semifinished version of the thermoelectric component. The method includes: a) providing a substantially planar substrate; b) providing a pulverulent thermoelectrically active material; c) pressing the active material to form green bodies; d) inserting green bodies into through-holes of the substrate; e) arranging the substrate with the green bodies inserted therein between two substantially planar electrodes; f) contacting face ends of the green bodies with the electrodes; g) exposing the green bodies to an electric current flowing between the electrodes; h) exposing the green bodies to a pressure force acting between the electrodes; i) sintering the green bodies to form thermolegs; and k) levelling the substrate and the thermolegs accommodated therein by bringing them closer to the electrodes while maintaining the parallelity thereof.

First claim

The invention claimed is:

1. A method for production of a semifinished version of a thermoelectric component, the method comprising:
a) providing a substantially planar substrate comprising an electrically and thermally insulating substrate material, through which through-holes extend oriented substantially perpendicularly to the substrate plane;
b) providing a pulverulent thermoelectrically active material;
c) pressing the active material to form green bodies, wherein the pressing proceeds in a mould different from the substrate;
d) inserting the green bodies into the through-holes of the substrate in such a manner that, within each through-hole, along the axis thereof, one green body extends through the substrate;
e) arranging the substrate with the green bodies inserted therein between two substantially planar electrodes, in such a manner that both electrodes and the substrate are substantially orientated parallel to one another;
f) contacting face ends of the green bodies with the electrodes in such a manner that a connection is provided between the two electrodes via the green bodies, which connection transmits not only an electrical current but also a mechanical pressing force;
g) exposing the green bodies to an electric current flowing between the electrodes in such a manner that heat is evoked within the thermoelectric active material;
h) exposing the green bodies to a pressure force acting between the electrodes in such a manner that the thermoelectric active material comes under pressure;
i) sintering the green bodies to form thermolegs, with the action of pressure and heat; and
k) levelling the substrate and the thermolegs accommodated therein by bringing them closer to the electrodes while maintaining the parallelity thereof, in such a manner that each end face of said thermolegs finish flush with a planar surface of said substantially planar substrate,
wherein any axial offset of the green bodies in the substrate and also any sinter shrinkage are compensated for by selection of a size of said green bodies.

2. The method according to claim 1 , wherein
a plurality of substrates with inserted green bodies are combined to form a stack,
wherein the substrates extend within the stack in parallel to one another and in each case a substantially planar separation plate is laid between two substrates that are adjacent within the stack, which separation plate extends in parallel to the substrates and which produces an electrically conductive and force-transmitting connection between the green bodies of the adjacent substrates, and
wherein the entire stack is arranged between the two electrodes.

3. The method according to claim 2 ,
wherein the electrodes comprise graphite and/or the separation plate comprises graphite,
wherein the green bodies, for contacting, are exposed to a first pressing force in f), and,
then the green bodies under the action of the first pressing force in f) are exposed to electric current until the electrodes and/or the separation plate have achieved a temperature at which the electrodes and/or the separation plate have an increased load-bearing capacity which is above the first pressing force in f), and
wherein the green bodies are then exposed to a second pressing force in h), which is above the first pressing force in f) and below the increased load-bearing capacity.

4. The method according to claim 1 , wherein
a plurality of substrates having inserted green bodies are arranged individually or stacked in a plane between the two electrodes.

5. The method according to claim 1 , wherein,
in the pressing of the pulverulent active material, the active material is compacted to a first compressed density which corresponds to between 75% and 85% of the true density of the active material.

6. The method according to claim 1 , wherein
the green bodies are sintered to form the thermolegs at a temperature which corresponds to between 50% to 70% of the melting temperature of the active material.

7. The method according to claim 1 , wherein,
during the exposure of the green bodies to the pressing force acting between the electrodes, the green bodies are compacted to a compressed density which corresponds to between 90% and 97% of the true density of the active material.

8. The method according to claim 1 , wherein
the green bodies have a circular cylindrical shape.

9. The method according to claim 8 , wherein
the green bodies each have a chamfer at the end face.

10. The method according to claim 8 , wherein
the green bodies have a mean roughness value R a between 12 μm and 24 μm, as specified in DIN 4766 T2, on the lateral surface thereof.

11. The method according to claim 1 , further comprising:
clamping the green bodies into the through-holes by inserting conical green bodies, by inserting into tapered through-holes or by inserting a radial oversize of the green bodies compared with the through-holes.

12. The method according to claim 1 , wherein
the pulverulent thermoelectric active material is prepared dry in a tableting press,
wherein the mould in which the active material is pressed to form green bodies is arranged within the tableting press, and
wherein the green bodies are ejected randomly from the tableting press.

13. The method according to claim 12 , wherein
the green bodies, manually or by a conveying appliance, are taken up, isolated, and inserted in an ordered manner into the through-holes of the substrate.

14. The method according to claim 1 , wherein
the substrate material is a composite material comprising an inorganic raw material and a binder.

15. The method according to claim 14 , wherein
the composite material is made up as a laminate,
wherein the inorganic raw material is at least one material selected from the group consisting of mica, perlite, phlogopite, and muscovite, and
wherein the binder is silicone or a silicone resin or an epoxy resin.

16. A method for production of a thermoelectric component, comprising:
producing a semifinished version of a thermoelectric component according to claim 1 and combining thermolegs in pairs to form thermocouples.

Assignees

• Evonik Operations Gmbh

Inventors

• Hoch Sascha
• Kern Magdalena
• Stenner Patrik
• Busse Jens
• Giesseler Mareike
• Deis Wolfgang
• Rajic Zeljko

Classifications

• H10N10/01 Primary

  Manufacture or treatment · CPC title

• B22F3/14

  simultaneously · CPC title

• B22F2003/1051

  by electric discharge · CPC title

• B22F2302/45

  Others, including non-metals · CPC title

• B22F7/08

  with one or more parts not made from powder {(B22F7/062 takes precedence)} · CPC title