Thermoelectric member and manufacturing the same

Abstract

As a technical means for achieving the technical problem described above, according to one aspect of the present invention, the thermoelectric member is in the form of a column having a polygonal cross-section, and the surface extending in the longitudinal direction of the column has a root mean square deviation (RMS) value of surface roughness of 1 μm or less.

Description

Technology Field

[0001] The present invention relates to a thermoelectric element and a method for manufacturing the same, and more specifically, to a thermoelectric element having an easy manufacturing process and excellent element performance, and a method for manufacturing the same. Background Technology

[0002] Thermoelectric devices are devices utilizing thermoelectric materials that possess thermoelectric properties, which are a reversible energy conversion phenomenon between heat and electricity. There are thermoelectric devices utilizing the Seebeck effect to generate electricity from heat, and thermoelectric devices utilizing the Peltier effect to perform cooling or heating by converting electricity into heat.

[0003] A thermoelectric element consists of thermoelectric components classified into n-type and p-type and electrodes connected to both ends of the thermoelectric components. Specifically, the n-type thermoelectric component and the p-type thermoelectric component are interconnected through electrodes to form a pn element.

[0004] Thermoelectric devices utilizing the Peltier effect utilize the characteristic that heat is generated or absorbed at the junction of thermoelectric devices as an externally applied current passes through a pn element formed by a p-type thermoelectric device and an n-type thermoelectric device, and thermoelectric devices utilizing the Seebeck effect utilize the electromotive force resulting from the movement of electrons or holes induced by the temperature difference between the two ends of the junction. Therefore, in order to maximize the thermoelectric effect of the thermoelectric device, it is required to bond the thermoelectric device to the substrate of the thermoelectric device with the largest possible surface area.

[0005] Accordingly, the thermoelectric element has a structure in which p-type and n-type thermoelectric elements are arranged in a columnar form on a substrate, and each thermoelectric element is interconnected by electrode pieces.

[0006] In this case, p-type and n-type thermoelectric elements must be processed into a column shape. A common method involves manufacturing the thermoelectric material in the form of a plate or ingot and then processing it into a column shape.

[0007] However, in order to process a thermoelectric element in the form of a plate or ingot into a column shape, a cutting process of the plate or ingot is involved. During the cutting process, a significant amount of impact is applied to the thermoelectric element, which can induce numerous defects within the thermoelectric element and lead to failure of some thermoelectric elements. Furthermore, defects within the thermoelectric element hinder the movement of electrons or holes, which can reduce the thermoelectric effect and cause problems that degrade the performance of the thermoelectric element.

[0008] Accordingly, there is a need for technological development regarding thermoelectric components with excellent thermoelectric performance by minimizing the defect rate occurring during the manufacturing process and minimizing defects in the thermoelectric components.

[0009] Meanwhile, the aforementioned background technology is technical information that the inventor possessed for the derivation of the present invention or acquired during the process of deriving the present invention, and it cannot be considered as prior art disclosed to the general public prior to the filing of the present invention. Prior art literature

[0010] Korean Patent Publication No. 2021-0133944 “Method for manufacturing a thermoelectric element, thermoelectric element manufactured thereby, and thermoelectric module” The problem to be solved

[0011] One embodiment of the present invention aims to provide a thermoelectric member with excellent thermoelectric performance.

[0012] Another embodiment of the present invention aims to provide a method for manufacturing a thermoelectric member that minimizes the defect rate and is easy to manufacture. means of solving the problem

[0013] As a technical means for achieving the technical problem described above, according to one aspect of the present invention, the thermoelectric member is in the form of a column having a polygonal cross-section, and the surface extending in the longitudinal direction of the column has a root mean square deviation (RMS) value of surface roughness of 1 μm or less.

[0014] According to another aspect of the present invention, when the thermoelectric member is an n-type thermoelectric member, the root mean square deviation value of the surface roughness of the surface may be 0.8 μm or less.

[0015] According to another aspect of the present invention, when the thermoelectric element is a p-type thermoelectric element, the root mean square deviation value of the surface roughness of the surface may be 1 μm or less.

[0016] According to another aspect of the present invention, the arithmetic mean deviation (Ra) of the surface roughness of the surface of the thermoelectric member may be 0.8 μm or less.

[0017] According to another aspect of the present invention, when the thermoelectric element is an n-type thermoelectric element, the arithmetic mean deviation of the surface roughness of the surface may be 0.7 μm or less.

[0018] According to another aspect of the present invention, when the thermoelectric element is a p-type thermoelectric element, the arithmetic mean deviation of the surface roughness of the surface may be 0.8 μm or less.

[0019] According to another aspect of the present invention, the height difference between the maximum peak and the minimum valley of the surface roughness profile of the surface of the thermoelectric member may be 6 μm or less.

[0020] According to another aspect of the present invention, when the thermoelectric element is an n-type thermoelectric element, the height difference between the maximum apex and the minimum trough of the surface roughness profile of the surface may be 4 μm or less.

[0021] According to another aspect of the present invention, when the thermoelectric element is a p-type thermoelectric element, the height difference between the maximum apex and the minimum trough of the surface roughness profile of the surface may be 6 μm or less.

[0022] According to another aspect of the present invention, the number of linear feet extending in a direction inclined at 45° or more from the longitudinal direction of the column on the surface of the thermoelectric member may be zero.

[0023] According to another aspect of the present invention, the corners of the cross-section of the thermoelectric member may have a round shape.

[0024] As a technical means for achieving the aforementioned technical problem, according to another aspect of the present invention, a method for manufacturing a thermoelectric member comprises the steps of: introducing a thermoelectric material into the inlet of an extrusion nozzle having an inlet and an outlet, wherein the cross-section of the inlet is circular and the cross-section of the outlet is polygonal; and pressurizing the thermoelectric material to form a columnar thermoelectric member having the polygonal cross-section.

[0025] According to another aspect of the present invention, the inlet of the extrusion nozzle may include a decreasing tapered region in which the diameter of the inlet decreases from the starting point of the inlet toward the outlet, and the outlet of the extrusion nozzle may include an increasing tapered region in which the diameter of the outlet increases from the starting point of the outlet toward the end point where the thermoelectric semiconductor is discharged.

[0026] According to another aspect of the present invention, the outlet of the extrusion nozzle may further include a land area having the same diameter and extending a predetermined distance from the starting point of the outlet.

[0027] According to another aspect of the present invention, the step of forming the column-shaped thermoelectric member having the polygonal cross-section may include forming the thermoelectric member such that the root mean square deviation (RMS) value of the surface roughness of the surface extending in the longitudinal direction of the column is 1 μm or less. Effects of the invention

[0028] According to any one of the means for solving the problem of the present invention described above, the thermoelectric member of the present invention is in the form of a column having a polygonal cross-section, so the contact area with the electrode can be maximized, and thereby the thermoelectric effect can be maximized.

[0029] According to any one of the means for solving the problem of the present invention described above, the thermoelectric member of the present invention has a root mean square deviation value of the surface roughness of the side extending in the longitudinal direction of the thermoelectric member of 1 μm or less, so defects that hinder the movement of electrons or holes can be minimized, and as a result, the electrical conductivity of the thermoelectric member is improved and the thermoelectric characteristics of the thermoelectric member can be improved.

[0030] According to any one of the means for solving the problem of the present invention described above, the thermoelectric member of the present invention has zero linear pits extending in a direction inclined at 45° or more from the longitudinal direction of the column, so defects that can hinder the movement of carriers in the longitudinal direction of the column, which is the main direction of movement of electrons and holes, can be minimized. Accordingly, the thermoelectric characteristics of the thermoelectric member can be further improved.

[0031] According to any one of the means for solving the problem of the present invention described above, the method for manufacturing a thermoelectric member of the present invention forms a columnar thermoelectric member through an extrusion nozzle, so a thermoelectric member with excellent surface roughness characteristics can be easily manufactured in a single process. Accordingly, there is an advantage in that a thermoelectric member with excellent thermoelectric properties can be easily manufactured.

[0032] According to any one of the means for solving the problem of the present invention described above, the method for manufacturing a thermoelectric member of the present invention forms the thermoelectric member through an extrusion nozzle having a circular inlet cross-section and a polygonal outlet cross-section, so the problem of the thermoelectric material accumulating in the extrusion nozzle can be minimized, and the defect rate of the thermoelectric member resulting therefrom can be minimized.

[0033] According to any one of the means for solving the problem of the present invention described above, the method for manufacturing a thermoelectric member of the present invention forms the thermoelectric member through an extrusion nozzle including an inlet including a decreasing taper region and an outlet including an increasing taper region, so that the thermoelectric material can be extruded with uniform pressure during the manufacturing process of the thermoelectric member, thereby minimizing the occurrence of internal cracks, and the problem of the thermoelectric member bending due to uneven shear stress during the discharge process of the thermoelectric member can be minimized.

[0034] According to any one of the means for solving the problem of the present invention described above, the method for manufacturing a thermoelectric member of the present invention forms the thermoelectric member through an extrusion nozzle having an outlet that is spaced apart by a predetermined distance and has a land area of ​​the same diameter, so that cracks and defects caused by uneven stress can be minimized when manufacturing a thermoelectric member having a polygonal cross-section.

[0035] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing

[0036] FIG. 1 is a partially cutaway perspective view illustrating an example of a thermoelectric module including a thermoelectric member according to an embodiment of the present invention. FIG. 2 is a perspective view for explaining a thermoelectric member according to one embodiment of the present invention. Figure 3 shows surface imaging and surface roughness analysis result images for area A of Figure 2. FIG. 4 is a flowchart illustrating a method for manufacturing a thermoelectric member according to one embodiment of the present invention. Figure 5 is a conceptual diagram illustrating each step of the method for manufacturing the thermoelectric element of Figure 4. Figure 6 is a plan view of the extrusion nozzle viewed in the direction VI of Figure 5. FIG. 7 is a comparative analysis image of the surface roughness of a thermoelectric member according to one embodiment of the present invention and a thermoelectric member according to a comparative example. FIG. 8 is a graph of the electrical conductivity of a thermoelectric member according to one embodiment of the present invention and a thermoelectric member according to comparative examples. FIG. 9 is a graph of the Seebeck coefficient of a thermoelectric member according to one embodiment of the present invention and a thermoelectric member according to comparative examples. FIG. 10 is a graph of the output factor of a thermoelectric member according to one embodiment of the present invention and a thermoelectric member according to comparative examples. Specific details for implementing the invention

[0037] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0038] Throughout the specification, when a part is described as being "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other members or elements interposed between them. Furthermore, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0039] The present invention will be described in detail below with reference to the attached drawings.

[0040] FIG. 1 is a partially cutaway perspective view illustrating an example of a thermoelectric module including a thermoelectric member according to an embodiment of the present invention.

[0041] Referring to FIG. 1, the present invention relates to a thermoelectric module (100), wherein the thermoelectric module (100) of the present invention can be used in an energy device utilizing waste heat using the Seebeck effect or in an electric heating and cooling device using the Peltier effect.

[0042] The thermoelectric module (100) of the present invention comprises a first substrate (110), a first electrode (120) on the first substrate (110), a thermoelectric member (130) on the first electrode (120), a second electrode (140) on the thermoelectric member (130), and a second substrate (150) on the second electrode (140).

[0043] The first substrate (110) is a substrate for supporting the components of the thermoelectric module (100) and may be made of a material having sufficient mechanical strength, insulation, and thermal conductivity. In some embodiments, the first substrate (110) may be composed of a multilayer substrate composed of a material with excellent thermal conductivity and a material with excellent insulation.

[0044] The first electrode (120) is an electrode disposed on the first substrate (110) and is electrically connected to one end of the thermoelectric module (100). The first electrode (120) may be made of a metal material with excellent electrical conductivity.

[0045] The thermoelectric member (130) is a member disposed on the first electrode (120) and is formed in a columnar shape extending from the first substrate (110) toward the second substrate (150). In this case, the surface of the thermoelectric member (130) adjacent to the first substrate (110) may be referred to as the lower surface, and the surface adjacent to the second substrate (150) may be referred to as the upper surface.

[0046] The upper and lower surfaces of the heat transfer element (130) can be polygonal.

[0047] The thermoelectric element (130) may be composed of an n-type thermoelectric element (130) and a p-type thermoelectric element (130), and the n-type thermoelectric element (130) and the p-type thermoelectric element (130) may be arranged alternately in the form of an n×m matrix (wherein n and m are natural numbers).

[0048] The lower surfaces of adjacent thermoelectric members (130) can be electrically connected by a first electrode (120). Additionally, the upper surfaces of adjacent thermoelectric members (130) can be electrically connected by a second electrode (140). In this case, the thermoelectric member (130) connected by the first electrode (120) and the thermoelectric member (130) connected by the second electrode (130) may be different from each other. For example, the lower surface of the first thermoelectric member (130) and the lower surface of the adjacent second thermoelectric member (130) may be electrically connected by the first electrode (120), and the upper surface of the second thermoelectric member (130) may be electrically connected to the upper surface of the adjacent third thermoelectric member (130) through the second electrode (140). In this case, the first thermoelectric element (130), the second thermoelectric element (130), and the third thermoelectric element (130) can be connected in series through the first electrode (120) and the second electrode (130), and the thermoelectric element (130) can be connected in the order of pnp or npn to form a series-connected pn element.

[0049] The thermoelectric member (130) may be composed of a semiconductor material. For example, if the thermoelectric member (130) is an n-type thermoelectric member (130), it may be formed from a Bi-Te thermoelectric material including bismuth (Bi) and tellurium (Te) as main raw materials. If the thermoelectric member (130) is a p-type thermoelectric member (130), it may be formed from a Bi-Te thermoelectric material including at least one of antimony (Sb), nickel (Ni), aluminum (Al), copper (Cu), silver (Ag), lead (Pb), boron (B), gallium (Ga), Te, Bi, and indium (In). However, it is not limited to this, and the thermoelectric member (130) can be formed from various thermoelectric materials such as cobalt (Co)-Sb-based, Pb-Te-based, silicon (Si)-germanium (Ge)-based, iron (Fe)-Si-based, and Sb-Te-based materials.

[0050] The thermoelectric material (130) may further include various types of additives to improve thermoelectric performance in addition to the thermoelectric material described above.

[0051] Detailed features of the thermoelectric element (130) will be described later with reference to FIG. 2.

[0052] As described above, the second electrode (140) is disposed on the upper surface of the thermoelectric member (130) and is configured to electrically connect adjacent thermoelectric members (130) to each other.

[0053] The second substrate (150) is placed on the second electrode (140) and may be composed of a material having excellent mechanical strength, electrical insulation, and thermal conductivity, just like the first substrate (110).

[0054] In some embodiments, the thermoelectric module (100) may further include wiring (160). The wiring (160) is connected to at least one of the first electrode (120) and the second electrode (140) and is configured to apply current to the first electrode (120) or the second electrode (140). When the thermoelectric module (100) is a Peltier element, the current applied through the wiring (160) flows along a path formed through the first electrode (120), the thermoelectric element (130), and the second electrode (140), and induces a Peltier effect to generate or absorb heat at the contact area between the thermoelectric element (130) and the electrodes (120, 140). Meanwhile, when the thermoelectric module (100) is a Seebeck element, a flow of electrons or holes occurs in the thermoelectric member (130) due to the heat difference between the first substrate (110) or the second substrate (150), and as current is generated through the current path formed through the first electrode (120), the thermoelectric member (130), and the second electrode (140), electricity can be generated through the wiring (160).

[0055] The thermoelectric module (100) of the present invention is formed in a columnar shape having a polygonal cross-section and includes a thermoelectric member (130) having the characteristic that the root mean square deviation (RMS) value of the surface roughness of the surface extended in the longitudinal direction of the column is less than or equal to a specific value (1.2 μm). Through this, the thermoelectric module (100) of the present invention can have excellent thermoelectric characteristics. For a more detailed explanation thereof, refer to FIGS. 2 and FIGS. 3 together.

[0056] FIG. 2 is a perspective view for explaining a thermoelectric member according to an embodiment of the present invention. FIG. 3 is a surface image and surface roughness analysis result image for area A of FIG. 2.

[0057] Referring to FIG. 2, the thermoelectric member (130) has a polygonal cross-section (132). That is, the shape of the lower surface in contact with the first electrode (120) and the upper surface (132) in contact with the second electrode (140) may be polygonal. For convenience of explanation, both the upper surface (132) and the lower surface are defined as the cross-section (132) of the thermoelectric member (130). As shown in FIG. 2, the cross-section (132) of the thermoelectric member (130) may be rectangular. However, it is not limited thereto, and the cross-section (132) of the thermoelectric member (130) may be composed of various polygons other than rectangular.

[0058] The corners of the cross-section (132) of the thermoelectric member (130) may have a rounded shape. As the corners of the cross-section (132) are rounded, the stress concentrated at the corners during the process of forming the thermoelectric member (130) can be relieved. In this case, the radius of curvature of the rounded portion can be appropriately selected according to the stress generated during the forming process of the thermoelectric member (130) and the characteristics of the thermoelectric material. A detailed explanation of this will be provided later.

[0059] The thermoelectric member (130) is extended in a columnar shape. For example, as shown in FIG. 2, it may be in the shape of a cuboid extended in the longitudinal direction (Y). However, it is not limited thereto, and the thermoelectric member (130) may be configured in various shapes depending on the shape of the cross-section.

[0060] The surface (131) (hereinafter referred to as the ‘side’) extending in the longitudinal direction (Y) of the thermoelectric member (130) has a root mean square deviation of surface roughness of 1.2 μm or less.

[0061] Here, “surface roughness” refers to the degree of fine irregularities present on the surface and signifies the geometric shape of the surface that occurs during the process of forming the thermoelectric member (130). That is, when the thermoelectric member (132) in FIG. 2 is cut in the II-II' direction, if one looks at the cut surface for area A, the cut surface for the side (131) of the thermoelectric member (132) may have an irregular structure as shown in the enlarged view of FIG. 2. Surface roughness refers to the degree of fine irregularities present on the side (131) of the thermoelectric member (132) and can be quantified by the standard ASME B46.1-1995 or ISO 4287-1997, etc.

[0062] The root mean square deviation refers to the integral value of the surface profile and is defined by the following [Equation 1].

[0063]

[0064] Here, R q is the root mean square deviation value of the surface roughness, where L is the length of the measured surface and r is the height value from the centerline of the surface profile.

[0065] The thermoelectric member (130) of the present invention has the characteristic that the root mean square deviation of the surface roughness for the side (131) is 1 μm or less, which means that the root mean square deviation of the surface roughness for the cut surface cut in the II-II' direction (i.e., width direction (X)) over the entire side (131) of FIG. 2 is 1 μm or less.

[0066] Specifically, when the thermoelectric member (130) of the present invention is an n-type thermoelectric member, the root mean square deviation of the surface roughness on the side (131) may be 0.8 μm or less, and preferably 0.76 μm or less.

[0067] When the thermoelectric member (130) of the present invention is a p-type thermoelectric member, the root mean square deviation of the surface roughness on the side (131) may be 1 μm or less, and preferably 0.97 μm or less.

[0068] In addition, the arithmetic mean deviation (R) of the surface roughness on the side (131) of the thermoelectric member (130) of the present invention a ) can be within 0.8μm. Here, the arithmetic mean deviation of surface roughness is defined by the following [Equation 2].

[0069]

[0070] Here, R a is the arithmetic mean deviation value of the surface roughness, where L is the length of the measured surface and r is the height value from the centerline of the surface profile.

[0071] Specifically, when the thermoelectric member (130) of the present invention is an n-type thermoelectric member (130), the arithmetic mean deviation value of the surface roughness may be 0.7 μm or less, and preferably 0.64 μm or less.

[0072] When the thermoelectric member (130) of the present invention is a p-type thermoelectric member (130), the arithmetic mean deviation value of the surface roughness may be 0.8 μm or less, and preferably 0.77 μm or less.

[0073] Additionally, the height difference (PV) between the maximum peak and the minimum valley of the surface roughness profile for the side (131) of the thermoelectric member (130) of the present invention may be 6 μm or less. Here, the maximum peak of the surface roughness profile refers to the highest point in the cross-section along the II-II' direction of the side (131) of the thermoelectric member (130), as shown in FIG. 2, and the minimum valley of the surface roughness profile refers to the lowest point.

[0074] Specifically, when the thermoelectric member (130) of the present invention is an n-type thermoelectric member (130), the difference between the maximum apex and minimum trough height of the surface roughness profile may be 4 μm or less, and preferably 3.44 μm or less.

[0075] When the thermoelectric member (130) of the present invention is a p-type thermoelectric member (130), the difference between the maximum peak and minimum valley height of the surface roughness profile may be 6 μm or less, and preferably 5.55 μm or less.

[0076] Meanwhile, the number of linear pits extending in a direction inclined at 45° or more from the longitudinal direction (Y) on the side (131) of the thermoelectric member (130) of the present invention may be zero. Here, a linear pit may refer to a linear defect carved out in a specific direction from the side (131) of the thermoelectric member (130). There may be almost no linear defects extending in a direction close to the width direction (X) of the thermoelectric member (130) on the side (131) of the thermoelectric member (130) of the present invention.

[0077] Referring to FIG. 3, the thermoelectric member (130) of the present invention, as described above, has a side surface (131) with a root mean square deviation of surface roughness of 1 μm or less and an arithmetic mean deviation of surface roughness of 0.8 μm or less, and has a height difference between the maximum apex and the minimum trough of the surface roughness profile for the side surface (131) of 6 μm or less, and thus the thermoelectric member (130) of the present invention can have excellent thermoelectric properties.

[0078] Specifically, if the measured values ​​for the surface roughness of the side (131) of the thermoelectric member (130) fall outside the range described above, it can be considered that there are multiple defects on the side (131) of the thermoelectric member (130), and as the movement of electrons or holes is hindered by surface defects, the electrical conductivity is reduced, and thus the thermoelectric performance may be reduced. However, since the thermoelectric member (130) of the present invention has surface roughness measured values ​​that are within the range described above, as shown in FIG. 3 (a), the surface of the side (131) may be smooth and the surface defects may be low. Accordingly, the thermoelectric member (130) of the present invention may have excellent thermoelectric performance. In particular, as shown in FIG. 3(b), since the average value of the surface roughness (e.g., root mean square deviation and arithmetic mean deviation) and the difference between the maximum peak and minimum valley height of the surface roughness profile are both small, the average number of defects is small and the depth of the defects can also be small. Accordingly, the total number of defects that hinder the movement of electrons or holes and the degree of defects are both small, so the thermoelectric member (130) of the present invention can have excellent thermoelectric performance.

[0079] Additionally, the thermoelectric member (130) of the present invention is characterized by having zero linear pits extending in a direction inclined at 45° or more from the longitudinal direction (Y) of the side (131), and most of the linear defects on the side (131) of the thermoelectric member (130) extend in the longitudinal direction (Y). As described above, the thermoelectric member (130) is formed in a columnar shape and arranged in the longitudinal direction (Y) between the first electrode (120) and the second electrode (140), so that electrons and holes flow along the longitudinal direction of the thermoelectric member (130). As most of the linear defects extend in the longitudinal direction (Y), defects in the width direction (X) that hinder the flow of electrons or holes are minimized, and accordingly, the electrical conductivity of the thermoelectric member (130) can be improved, and the thermoelectric performance of the thermoelectric member (130) can be further improved.

[0080] Meanwhile, since the cross-section (132) of the thermoelectric member (130) is configured as a polygon, the contact area with the first electrode (120) or the second electrode (140) may be larger than when the cross-section (132) is circular. In this case, as the contact area of ​​the thermoelectric member (130) increases, the thermoelectric module (100) can emit or absorb more heat, so the Peltier effect of the thermoelectric module (100) can be maximized. In addition, as the contact area of ​​the thermoelectric member (130) increases, the amount of heat that the thermoelectric member (130) can absorb increases, and as a result, the flow of electrons or holes generated from the thermoelectric member (130) can also increase, so the Seebeck effect of the thermoelectric module (100) can also be maximized.

[0081] In addition, since the corners of the cross-section (132) of the thermoelectric member (130) of the present invention are rounded, the problem of stress generated during the manufacturing process being concentrated at the corners can be minimized, and thereby the defect rate of the thermoelectric member (130) can be reduced. Refer to FIGS. 4 to 6 for a detailed explanation of this.

[0082] FIG. 4 is a flowchart illustrating a method for manufacturing a thermoelectric member according to an embodiment of the present invention. FIG. 5 is a conceptual diagram illustrating each step of the method for manufacturing a thermoelectric member of FIG. 4. FIG. 6 is a plan view of an extrusion nozzle viewed in the direction VI of FIG. 5.

[0083] The thermoelectric element of the present invention can be manufactured through extrusion, unlike conventional thermoelectric element manufacturing methods.

[0084] Specifically, referring to FIG. 4, first, a thermoelectric material is introduced into the inlet of the extrusion nozzle (S410).

[0085] Referring to FIG. 5, a thermoelectric material (570) is introduced into an injection tube (561) connected to the inlet (563i) of an extrusion nozzle (563). As described above, the thermoelectric material (570) may be various materials such as Bi-Te, Co-Sb, Pb-Te, Si-Ge, Fe-Si, and Sb-Te, and various types of additives may be introduced to improve thermoelectric performance. The thermoelectric material (570) may be introduced in the form of a powder, but is not limited thereto, and in some cases, may be introduced in the form of a molten liquid or a solution dissolved in a solvent.

[0086] In this case, the inlet (563i) of the extrusion nozzle (563) has a tapered shape so that the thermoelectric material (570) can be naturally extruded to the outlet (563o) of the extrusion nozzle (563). That is, the inlet (563i) of the extrusion nozzle (563) has a tapered shape in which the diameter of the inlet (563i) decreases from the starting point of the inlet (563i) toward the outlet (563o). In this case, the taper angle of the inlet (563i) has an appropriate angle so that the thermoelectric material (570) can be discharged to the outlet (563o) with sufficient pressure during the process of injecting the thermoelectric material (570). For example, the taper angle of the inlet (563i) may be 30° or more and 60° or less with respect to the extrusion direction of the thermoelectric material (570). If the taper angle is less than 30°, the diameter of the inlet (563i) becomes smaller, making it difficult to feed the thermoelectric material (570); if the taper angle exceeds 60°, the pressure required to extrude the thermoelectric material (570) may increase, and residual material may remain in the extrusion nozzle (563), causing the extrusion nozzle (563) to become clogged or increasing production costs due to the residual material.

[0087] Referring to FIG. 6, the cross-section of the inlet (563i) of the extrusion nozzle (563) may be circular. Since the cross-section of the inlet (563i) is circular, the angle of the decreasing taper of the inlet (563i) is the same on all sides of the inlet (563i), and the frictional force applied to the thermoelectric material (570) during extrusion becomes uniform in all directions, so the stress applied to the thermoelectric material (570) becomes uniform, and the occurrence of defects in the thermoelectric member (130) being molded can be minimized.

[0088] Afterwards, referring again to FIG. 4, the thermoelectric material is pressurized and extruded, thereby forming a thermoelectric member (S420).

[0089] Referring to FIG. 5, pressure is applied to the thermoelectric material (570), and as the thermoelectric material (570) is discharged through the outlet (563o) of the extrusion nozzle (563), it is formed into a thermoelectric member (130).

[0090] As illustrated in FIG. 6, the inlet (563i) of the extrusion nozzle (563) has a circular cross-section, while the outlet (563o) of the extrusion nozzle (563) has a polygonal cross-section. Accordingly, the cross-section of the extruded thermoelectric member (130) may be a polygon corresponding to the cross-section of the outlet (563o). Specifically, the outlet (563o) of the extrusion nozzle (563) may have a cross-section corresponding to the cross-section (132) of the thermoelectric member (130) placed in the thermoelectric module (130). In particular, the cross-sectional corners of the outlet (563o) of the extrusion nozzle (563) are rounded. In this case, the stress concentrated on the corner portions of the polygon during the process of extruding the thermoelectric material (570) is minimized, thereby minimizing cracks occurring at the corner portions of the thermoelectric member (130).

[0091] As illustrated in FIG. 5, the outlet (563o) of the extrusion nozzle (563) may have an increasing taper shape in which the diameter of the outlet (563o) increases from the starting point of the outlet (563o) toward the end point where the thermoelectric member (130) is discharged. In this case, the increasing taper angle of the outlet (563o) may be 20° or more and less than 90° with respect to the discharge direction of the thermoelectric member (130). If the increasing taper angle is less than 20°, some thermoelectric material (570) may accumulate at the outlet (563o), and a problem may occur in which the extrusion nozzle (563) becomes clogged. If the increasing taper angle is greater than 90°, shear stress may occur during the process of discharging the thermoelectric material (570), causing the thermoelectric member (130) to bend during extrusion or the thermoelectric member (130) to break in the middle of extrusion.

[0092] Meanwhile, the outlet (563o) of the extrusion nozzle (563) may include a land area (L) with the same diameter from the starting point to the ending point. That is, as shown in the enlarged view of FIG. 5, at least a straight section without a taper may be provided in at least a part of the outlet (563o). The aforementioned land area (L) may be placed only in the rounded corner portion of the polygonal-shaped outlet (563o).

[0093] The land area (L) is configured to compensate for the difference in stress (frictional force) that the thermoelectric material (570) receives along the inner surface of the extrusion nozzle (563) as the extrusion nozzle (563) changes from an inlet (563i) with a circular cross-section to an outlet (563o) with a polygonal cross-section. That is, if the inlet (563i) and the outlet (563o) of the extrusion nozzle (563) are both configured with the same shape, the thermoelectric material receives the same stress between the inlet (563i) and the outlet (563o) of the extrusion nozzle (563); however, since the cross-sectional shapes of the inlet (563i) and the outlet (563o) of the extrusion nozzle (563) of the present invention are different, the stress may vary locally during the process of extruding the thermoelectric material (570). In particular, a problem arises where stress weakens at the corners of a polygon, but the extrusion nozzle (563) of the present invention is provided with a land area (L) at the outlet (563o), so that the insufficient stress at the corners of the polygon can be compensated, and thus a thermoelectric member (130) with minimized surface defects can be easily manufactured.

[0094] In this case, the length of the land area (L) can be appropriately determined according to the radius of curvature of the round area of ​​the corner of the thermoelectric member (130).

[0095] As the thermoelectric material (570) receives a lot of pressure and heat while passing through the extrusion nozzle (563), the thermoelectric material (570) condenses and solidifies and is formed into a columnar thermoelectric member (130).

[0096] In some embodiments, a sintering step for sintering the thermoelectric element (130) may be additionally performed.

[0097] The method for manufacturing a thermoelectric member according to the present invention manufactures a thermoelectric member (130) by an extrusion method using an extrusion nozzle (563). In particular, the cross-section of the inlet (563i) of the extrusion nozzle (563) is circular, and the cross-section of the outlet (563o) of the extrusion nozzle (563) is polygonal, and the cross-section of the outlet (563o) of the extrusion nozzle (563) may be the same as the cross-section (132) of the thermoelectric member (130) placed in the thermoelectric module (100). Accordingly, a separate slicing process may be omitted to manufacture the thermoelectric member (130) in the method for manufacturing a thermoelectric member according to the present invention.

[0098] Specifically, conventional methods for manufacturing thermoelectric elements involve producing an intermediate material in the form of a plate or ingot and then cutting it to produce the thermoelectric element. However, according to conventional manufacturing methods, significant stress is applied to the thermoelectric element during the cutting process of the intermediate material, which can result in the final manufactured thermoelectric element having many defects. In particular, surface defects caused by processing tools are frequently induced on the longitudinal side of the thermoelectric element, and consequently, the surface of the thermoelectric element may have a rough surface.

[0099] However, since the method for manufacturing a thermoelectric member of the present invention is manufactured by extrusion through an extrusion nozzle (563) having a shape corresponding to the cross-section (132) of the thermoelectric member (130) to be placed in the thermoelectric module (100), there is no need to additionally cut the thermoelectric member (130), and the extruded thermoelectric member (130) can be cut in the width direction (X) and used immediately. Accordingly, surface defects caused by processing tools can be minimized, and the surface roughness of the side surface (131) of the thermoelectric member (130) can be excellent as described above.

[0100] In addition, since the conventional method for manufacturing a thermoelectric member involves cutting an intermediate material, residue remains after cutting, which causes a problem of high production costs for the thermoelectric member. However, the method for manufacturing a thermoelectric member according to the present invention allows the extruded thermoelectric member (130) to be used immediately, thereby minimizing the problem of residue generation and having the advantage of lowering the production cost of the thermoelectric member (130).

[0101] In addition, the method for manufacturing a thermoelectric member according to the present invention manufactures a thermoelectric member (130) using an extrusion nozzle (563) having an inlet (563i) with a circular cross-section and an outlet (563o) with a polygonal cross-section. Since the inlet (563i) is configured with a circular cross-section, the injection of the thermoelectric material (570) can be carried out uniformly over the entire area, and the problem of the thermoelectric material (570) accumulating in a specific area can be minimized. If the cross-sections of both the inlet (563i) and the outlet (563o) are polygonal, a relatively large gap may occur between the punch for extruding the extrusion material (570) and the extrusion nozzle (563) at the corners of the polygon, causing the thermoelectric material (570) to accumulate. However, since the extrusion nozzle (563) of the present invention has a polygonal cross-section only at the outlet (563o), the gap between the punch and the inlet (563i) of the extrusion nozzle (563) can be the same in all directions, and the problem of the thermoelectric material (570) accumulating in the gap between the punch and the extrusion nozzle (563) can be minimized. Accordingly, the defect rate of the thermoelectric member (130) can be reduced, and productivity can be improved.

[0102] In addition, since the method for manufacturing a thermoelectric member of the present invention is equipped with an increasing taper at the outlet (563o) of the extrusion nozzle (563) that increases the nozzle diameter, the problem of the thermoelectric material (570) accumulating and clogging at the outlet (563o) of the extrusion nozzle (563) is minimized, and the problem of the thermoelectric member (130) bending or breaking due to shear stress during the discharge process of the thermoelectric member (130) can be minimized.

[0103] In particular, the outlet (563o) of the extrusion nozzle (563) is provided with a land area (L), which is a straight area with the same nozzle diameter, and the non-uniformity of stress applied to the thermoelectric material (570) through the land area (L) can be compensated for. In particular, as the land area (L) is provided at the corner portion of the polygonal cross-section, the stress deficiency phenomenon occurring at the corner portion of the polygonal cross-section of the thermoelectric module (130) can be compensated for, and thus the shape of the thermoelectric module (130) can be uniform, thereby minimizing surface defects and allowing the thermoelectric module (130) having a uniform shape to be manufactured.

[0104] Hereinafter, the advantages of the thermoelectric element (130) and the method of manufacturing the same according to the present invention will be explained in more detail through examples.

[0106] (Manufacturing Example. Manufacture of a thermoelectric element)

[0107] First, the Bi-Te-based thermoelectric material is compacted into a Ø11.3 rod shape to form an intermediate material, and then 1.25×1.25 mm 2 n-type thermoelectric elements and p-type thermoelectric elements having a shape of 1.25 mm × 1.25 mm × 0.8 mm were each manufactured using an extrusion nozzle having a square cross-section (manufacturing example below).

[0108] (Comparative example. Acquisition of thermoelectric component)

[0109] Commercially available Bi-Te-based n-type and p-type thermoelectric elements were obtained as cuboidal shapes having dimensions of 1.25 mm × 1.25 mm × 0.8 mm. Specifically, a commercially available thermoelectric element from Company A in China (Comparative Example 1) and a commercially available thermoelectric element from Company R in Russia (hereinafter Comparative Example 2) were obtained. The aforementioned commercially available thermoelectric elements were manufactured using a slicing (cutting) method rather than an extrusion method.

[0110] (Experimental Example 1. Comparison of Surface Roughness)

[0111] First, the surface roughness of the thermoelectric element according to the manufacturing example and the thermoelectric elements according to Comparative Example 1 and Comparative Example 2 was measured. The surface roughness values ​​were measured as the root mean square deviation (RMS), arithmetic mean deviation (Ra), and the difference in height between the maximum cusp and the minimum trough (PV), respectively. Measurements were taken on all sides (i.e., four faces) of the rectangular prism, and the arithmetic mean of the measured values ​​was calculated. Meanwhile, the size of the measurement surface was 0.85 μm × 0.85 μm.

[0112] The results are as shown in [Table 1] below.

[0113] division Type Surface roughness (μm) PV RMS Ra Comparative Example 1 N 5.55 1.18 0.94 P 6.57 1.12 0.88 Comparative Example 2 N 7.77 2.50 2.16 P 10.73 2.02 1.65 Preparation Example N 3.44 0.76 0.64 P 5.55 0.97 0.77

[0114] As can be seen by referring to [Table 1] above, the thermoelectric members of the manufacturing examples prepared according to the embodiments of the present invention have a surface roughness root mean square deviation (RMS) of 1 μm or less for both n-type and p-type thermoelectric members. Specifically, the surface roughness root mean square deviation was measured as 0.76 μm for the n-type thermoelectric member and 0.97 μm for the p-type thermoelectric member. On the other hand, the thermoelectric members of Comparative Examples 1 and 2 have a surface roughness root mean square deviation (RMS) exceeding 1 μm for both n-type and p-type thermoelectric members.

[0115] In addition, it can be seen that the thermoelectric members of the manufacturing example have an arithmetic mean deviation (Ra) of surface roughness of 0.8 μm or less for both n-type and p-type, and the difference between the maximum cusp and minimum trough heights (PV) of the surface roughness profile is 6 μm or less. On the other hand, it can be seen that the thermoelectric members of Comparative Examples 1 and 2 have significantly high Ra values ​​of 0.94 μm and 2.16 μm, respectively, and also significantly high PV values ​​of 6.57 μm and 10.73 μm.

[0116] In particular, since the thermoelectric member of the manufacturing example is manufactured by an extrusion method, the side surface is smooth, and no linear pits extending in a direction inclined at more than 45° from the longitudinal direction of the column are observed, indicating that it has excellent surface characteristics. This can be understood in more detail through the experimental data in Fig. 7.

[0117] FIG. 7 is a comparative analysis image of the surface roughness of a thermoelectric member according to one embodiment of the present invention and a thermoelectric member according to a comparative example.

[0118] Specifically, FIG. 7(a) is an image of the surface roughness measurement result for one side of the n-type thermoelectric element of Comparative Example 1, and FIG. 7(b) is an image of the surface roughness measurement result for one side of the n-type thermoelectric element of Manufacturing Example.

[0119] As can be seen by referring to FIG. 7(a), in the case of the n-type thermoelectric member of Comparative Example 1, a linear pit (SM) in the width direction extending at an angle of 45° or more in the longitudinal direction of the column is observed. This is believed to be because defects in the width direction are caused by sharp cutting tools during the process of cutting or slicing the intermediate material in the n-type thermoelectric member of Comparative Example 1.

[0120] On the other hand, as can be seen by referring to Fig. 7(b), in the case of the n-type thermoelectric member of the manufacturing example, the side surface is considerably smooth, and no linear pits in the width direction extending at an angle of 45° or more in the longitudinal direction of the column are observed. This is believed to be because the n-type thermoelectric member of the manufacturing example is manufactured by an extrusion method, thereby minimizing defects caused by cutting tools.

[0121] (Experimental Example 2. Comparison of Thermoelectric Properties)

[0122] The effect of the surface characteristics of the thermoelectric member according to Comparative Examples 1 and 2 and the thermoelectric member according to the Manufacturing Example on the thermoelectric characteristics was analyzed by comparing the thermoelectric characteristics of the thermoelectric member according to the Manufacturing Example.

[0123] Thermoelectric properties were measured using the ZEM-3 thermoelectric property evaluation device of Richstone Co., Ltd., and the electrical conductivity, power factor, and Seebeck coefficient of the thermoelectric material were measured at 300°C to 600°C in accordance with the JIS R 1650-1 standard.

[0124] FIG. 8 is a graph of the electrical conductivity of a thermoelectric member according to one embodiment of the present invention and a thermoelectric member according to comparative examples.

[0125] FIG. 9 is a graph of the Seebeck coefficient of a thermoelectric member according to one embodiment of the present invention and a thermoelectric member according to comparative examples.

[0126] FIG. 10 is a graph of the output factor of a thermoelectric member according to one embodiment of the present invention and a thermoelectric member according to comparative examples.

[0127] Referring to FIG. 8, it can be seen that the thermoelectric element of the manufacturing example has superior electrical conductivity compared to the thermoelectric elements of Comparative Example 1 and Comparative Example 2 at temperatures from 350°C to 600°C.

[0128] In addition, referring to FIG. 9, it can be seen that the thermoelectric element of the manufacturing example has a superior Seebeck coefficient compared to the thermoelectric elements of Comparative Example 1 and Comparative Example 2 at 300°C to 450°C.

[0129] In addition, referring to FIG. 10, it can be seen that the thermoelectric element of the manufacturing example has a superior output factor compared to the thermoelectric elements of Comparative Example 1 and Comparative Example 2 at 300°C to 450°C.

[0130] As a result, it can be seen that the thermoelectric element of the manufacturing example has superior electrical and thermoelectric properties compared to the thermoelectric elements of Comparative Example 1 and Comparative Example 2 at 350°C to 450°C. This is believed to be because the thermoelectric element of the manufacturing example has superior surface roughness characteristics compared to Comparative Example 1 and Comparative Example 2, thereby minimizing defects that hinder the movement of electrons or holes in the longitudinal direction of the thermoelectric element.

[0131] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0132] The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention. Explanation of the symbols

[0133] 100: Thermoelectric module 110: First substrate 120: First electrode 130: Thermoelectric element 131: Side view of the thermoelectric element 132: Cross-section of a thermoelectric element 140: Second electrode 150: Second substrate 160: Wiring 561: Infusion tube 563: Extrusion nozzle 563i: Inlet of the extrusion nozzle 563o: Extrusion nozzle exit 570: Thermoelectric materials

Claims

Claim 1 delete Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 delete Claim 10 delete Claim 11 delete Claim 12 A step of introducing a thermoelectric material into the inlet of an extrusion nozzle having an inlet and an outlet, wherein the cross-section of the inlet is circular, the cross-section of the outlet is polygonal, and the corners of the outlet are rounded; A method for manufacturing a thermoelectric member, comprising the step of pressurizing the thermoelectric material to form a column-shaped thermoelectric member having a polygonal cross-section, wherein, after the forming step, the side extending in the longitudinal direction of the column having the polygonal cross-section in the thermoelectric member has a surface roughness quantified by ASME B46.1-1995 or ISO 4287-1997 having the following characteristics, and in the step of feeding the thermoelectric material into the inlet of the extrusion nozzle, the outlet of the extrusion nozzle extends by a predetermined distance from the starting point of the outlet and further includes a land area having the same diameter, wherein the land area is disposed only at the corner of the outlet of the extrusion nozzle. having a surface roughness root mean square deviation (RMS) value of 1 μm or less, a surface roughness arithmetic mean deviation (Ra) value of 0.8 μm or less, and a maximum peak and minimum valley of a surface roughness profile of 6 μm or less. It has a height difference (PV) value. Claim 13 A method for manufacturing a thermoelectric member according to claim 12, wherein the inlet of the extrusion nozzle comprises a decreasing tapered region in which the diameter of the inlet decreases from the starting point of the inlet toward the outlet, and the outlet of the extrusion nozzle comprises an increasing tapered region in which the diameter of the outlet increases from the starting point of the outlet toward the end point where the thermoelectric member is discharged. Claim 14 delete Claim 15 delete

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