JP2012204757A - Method and device for manufacturing stacked body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a stacked body excellent in orientation properties of crystal orientation and having high density, and in particular, to improve mechanical strength of the stacked body and improve thermoelectric properties when applied to a manufacturing method of a thermoelectric semiconductor material.SOLUTION: A molten material is supplied from a cooling surface vertical direction toward a cooling surface, and the molten material is rapidly solidified layer by layer by being pushed to the cooling surface by an accelerating force of the molted material. Thereby, a C surface of a crystal gain stands up along a thickness direction of the layer, and a stacked body with a crystal structure in which an interlayer interface exists is manufactured.

Description

  The present invention relates to a method and an apparatus for manufacturing a laminated body of crystal structure materials, such as thermoelectric semiconductor materials, piezoelectric elements, magnetic materials, superconducting materials, etc., that require crystal orientations to be aligned in a certain direction.

Thermoelectric semiconductor materials are used as materials for thermoelectric elements (thermoelectric modules).

  As the thermoelectric semiconductor material, a material having a large figure of merit Z (= α 2 / ρκ) represented by a Seebeck coefficient α, a specific resistance ρ, and a thermal conductivity κ, which are constants specific to the substance, is used in the use temperature range.

  This type of thermoelectric semiconductor material has anisotropy in thermoelectric performance due to its crystal structure. That is, the figure of merit Z differs depending on the crystal orientation. Therefore, a single crystal material is used by energizing a crystal orientation with a large thermoelectric performance. In general, anisotropic crystals have a cleavage property and weak material strength. Therefore, a practical material is not a single crystal, but a polycrystalline material that is solidified unidirectionally by the Bridgman method or the like and oriented in a crystal orientation with high thermoelectric performance. used.

  However, although the polycrystalline material is not so much as a single crystal, the material strength is fragile, and there is a problem that the device is easily cracked or chipped during processing.

  That is, for example, a polycrystalline material generally used as an electronic cooling element is a Bi2Te3 thermoelectric material which is a mixed crystal system of bismuth telluride (Bi2Te3), antimony telluride (Sb2Te3), and bismuth selenide (Bi2Se3). This Bi2Te3-based thermoelectric material has a hexagonal crystal structure, in which a layer made of Bi and a layer made of Te are stacked perpendicular to the hexagonal C-axis. Due to this crystal structure, it has an electrical and thermal anisotropy, and the thermoelectric performance is better in the C-plane direction than in the C-axis direction. Therefore, by using the unidirectional solidification method, the growth direction of the crystal is controlled in a good orientation (C-plane direction) with good thermoelectric performance to produce a molten material and used as a thermoelectric element. However, at the portion where the Te layers in the crystal structure are stacked, the Te atoms are remarkably cleaved because the mutual Te atoms are Van der Waals bonds. For this reason, there is a problem that the strength is weak and cracking or chipping occurs in the slicing process for obtaining the thermoelectric element from the crystal material, the yield rate is extremely deteriorated, and the durability as the thermoelectric element (thermoelectric module) is lowered. There is.

  Moreover, in order to use as a thermoelectric element (thermoelectric module), predetermined | prescribed thickness (predetermined height) is required. For this reason, mechanical strength of a certain level or higher is required for products manufactured to a predetermined thickness (predetermined height).

  As described above, thermoelectric semiconductor materials need to have a crystal orientation orientated to improve thermoelectric performance and to ensure mechanical strength of a certain level or more in a product manufactured to a predetermined thickness (predetermined height). It becomes.

  In Patent Document 1, a thin powder of a material obtained by a quenching roll method is charged so as to be laminated in a mold, and is pressed and sintered in a laminating direction by a hot press to join thin powders together. Then, the laminated body is solidified and further pressed by plastic working such as hot pressing or upset forging in a direction perpendicular to the laminating direction, thereby adjusting the orientation of the crystal orientation and producing a thermoelectric semiconductor material having a laminated structure. The invention is described.

  In Patent Document 2, a thin powder of a material obtained by the rapid cooling roll method is laminated and pressure-sintered in the laminating direction by hot pressing to solidify the laminate, and further in a direction perpendicular to the laminating direction. Further, there is described an invention in which a thermoelectric semiconductor material having a laminated structure is manufactured by adjusting the orientation of crystal orientation by pressurizing and pressing with a hot press.

Patent Document 3 describes a centrifugal casting method. That is, an invention is described in which a molten metal and a ceramic are mixed with a molten metal that is a casting material, the mixed molten metal is poured into a rotating mold, and the mixed molten metal is solidified under a centrifugal force.

Japanese Patent Laid-Open No. 2003-37302 JP 2000-166113 A Japanese Patent Laid-Open No. 1-150455

  In Patent Documents 1 and 2, a laminated body of thin powders of materials obtained by a quenching roll method is hardened by hot pressing. In the rapid cooling roll method, the material in contact with the surface of the cooling roll is cooled outward from the center of the roll. For this reason, solidification of the material occurs in the film thickness direction, and a thin powder is obtained in which the C-plane of crystal grains stands in the film thickness direction. If this thin powder is laminated in the film thickness direction, a highly anisotropic thermoelectric element in which the C-plane of crystal grains stands up in the lamination direction can be obtained.

  However, in practice, when hot pressing is performed to harden the laminated body, the crystal grains in the laminated body are inclined or shifted, and the orientation of the crystal grains is worse than that of the original thin powder. . For this reason, even if hot pressing or plastic working is performed to adjust the orientation of the crystal orientation, the original thin powder orientation cannot be recovered.

  For this reason, development of a method that can increase the orientation of crystal orientation while increasing the density of the material and ensuring the mechanical strength of the laminated body of a predetermined thickness without adding mechanical deformation to the material by hot pressing or plastic working Is desired.

  This invention is made | formed in view of such a situation, and makes it a solution subject to be able to manufacture to a high-density laminated body excellent in the orientation of a crystal orientation. In particular, when applied to a method for producing a thermoelectric semiconductor material, it is an object of the present invention to improve thermoelectric performance while improving the mechanical strength of the laminate.

  In addition, the invention described in Patent Document 3 is an invention in which casting is performed in a place where centrifugal force is applied, and is not laminated in layers.

The first invention is
From the vertical direction of the cooling surface, the molten material is supplied toward the cooling surface, and the molten material is rapidly cooled and solidified while pressing the molten material against the cooling surface by the accelerating force of the molten material. A method for producing a laminate in which a laminate having a crystal structure in which the C-plane of crystal grains rises and an interlayer interface exists is produced.

The second invention is the first invention,
The cooling surface is an inner peripheral surface of the rotating body, and the acceleration force is a centrifugal force of the rotating body.

The third invention is the second invention,
A molten material is injected toward a mold formed on the inner peripheral surface of the rotating body.

The fourth invention is
A mold formed on the inner peripheral surface of the rotating body;
A rotational speed adjusting means for adjusting the rotational speed of the rotating body;
Heating means for melting the material;
Injection means for injecting a molten material toward the mold;
Cooling means for cooling the mold;
An apparatus for manufacturing a laminate comprising: a control means for controlling the rotation speed adjusting means or / and the heating means or / and the spraying means or / and the cooling means so that the molten material is laminated on the mold. It is characterized by that.

A fifth invention is the first invention,
By adjusting the cooling rate for each layer of the molten material, the orientation ratio of the C-plane of the crystal grains is adjusted.

The sixth invention is the second invention, the third invention,
By adjusting the number of rotations of the rotating body, the thickness of each layer of the laminated body is adjusted.

A seventh invention is the fourth invention,
By controlling the rotation speed adjusting means or / and the heating means or / and the injection means or / and the cooling means, the cooling rate for each layer of the molten material is adjusted.

In an eighth aspect based on the fourth aspect,
The thickness of each layered product is adjusted by controlling the rotation speed adjusting means and / or the jetting means.

The ninth invention is the first invention, the second invention, the third invention, the fifth invention, the sixth invention,
The material is a thermoelectric semiconductor material.

The tenth invention is the fourth invention, the seventh invention, the eighth invention,
The material is a thermoelectric semiconductor material.

According to the first invention, as shown in FIG. 11, the molten material is supplied from the vertical direction of the cooling surface toward the cooling surface, and the molten material is further pressed against the cooling surface by the acceleration force of the molten material. Each of these is rapidly solidified to produce a laminate 100 having a crystal structure in which the C-plane of the crystal grain 110 stands up along the thickness direction of the layer and an interlayer interface exists.

  In the second invention, the laminate 100 is manufactured on the assumption that the cooling surface is the inner peripheral surface of the rotating body 10 and the acceleration force is the centrifugal force of the rotating body 10.

  In 3rd invention, the laminated body 100 is manufactured by inject | pouring molten material toward the metal mold | die 11 formed in the internal peripheral surface of the rotary body 10. FIG.

  In the fourth invention, the mold 11 formed on the inner peripheral surface of the rotating body 10, the rotating speed adjusting means 20 for adjusting the rotating speed of the rotating body 10, the heating means 30 for melting the material, and the molten material as the metal Injection means 40 for injecting toward the mold 11, cooling means 50 for cooling the mold 11, rotation speed adjusting means 20 or / and heating means 30 or / and injection means so that the molten material is laminated on the mold 11. The laminated body 100 is manufactured by a manufacturing apparatus provided with the control means 60 which controls 40 or / and the cooling means 50. FIG.

That is, as shown in FIG. 11A, when the molten material is ejected from the injection port 43 of the nozzle 41 while rotating the mold 11, the molten material is landed on the mold 11 (cooling surface). Then, a centrifugal force corresponding to the mass of the molten material acts on the molten material, and the molten material is pressed against the mold 11 (cooling surface). Since the mold 11 is rotating, the layers are further overlapped when the injection of the molten material is continued. As a result, the mass of the material landed on the mold 11 increases, so that a larger centrifugal force acts, and the material is pressed with a larger force to increase the density of the laminate 100 (density improvement effect).

  As shown in FIG. 11 (b), when one layer of molten material has landed on the mold 11, heat flows in a direction from the material toward the mold 11. That is, since the molten material is high temperature and the mold 11 serving as a cooling surface is low temperature, a temperature gradient is generated in the thickness direction of the material layer, and a heat flow toward the mold 11 is formed. At the moment when the molten material lands on the mold 11, a heat flow toward the mold 11 is formed in the direction perpendicular to the normal direction of the inner peripheral surface of the rotating body 10. As a result, the material gradually solidifies vertically upward from the mold contact surface, and rapidly solidifies. With the start of solidification, crystal growth starts in the layer thickness direction from the mold contact surface, and crystal grains 110 with the C-plane standing in the layer thickness direction grow. Until one crystal growth is completed, the rotator 10 rotates, and one more layer is sprayed onto that one. Therefore, in the upper layer as well, heat flows in the same direction as the thickness of the layer. Similarly, the material solidifies in the direction vertically upward from the mold contact surface, and crystal growth is caused by the thickness of the layer. Get up in the direction. An interlayer interface is formed between the layers. In the same manner, the material is rapidly solidified for each layer, and the laminate 100 is aligned in the crystal orientation in the height direction of the laminate 100. In this way, the C-plane of the crystal grain 110 stands up along the thickness direction of the layer, and the laminated body 100 having a crystal structure in which an interlayer interface exists is produced (orientation rate improving effect).

According to the present invention, the laminated body 100 having a predetermined thickness is generated while improving the density and the orientation ratio. Therefore, as shown in the manufacturing process shown in FIG. 8B, the comparative example shown in FIG. The milling process, hot pressing process, plastic working process, and slicing process that are necessary in the manufacturing process can be omitted.

As described above, according to the manufacturing method and the manufacturing apparatus of the present invention, the number of steps can be reduced compared to the comparative example manufacturing process, the time required for all the steps can be shortened, and the production efficiency can be improved. Can do. In addition, since the laminated body 100 is generated by improving the density and the orientation ratio without applying mechanical deformation to the material by hot pressing or plastic working, the orientation ratio of the crystal orientation is manufactured by the comparative example manufacturing process. Greatly improved compared to products.

Further, the structure and performance of the laminate 100 can be controlled as follows.

  By adjusting the cooling rate for each layer of the molten material, the orientation ratio of the C plane of the crystal grains 110 can be adjusted (fifth invention).

  By adjusting the rotation speed of the rotating body 10, the thickness of each layer can be adjusted (sixth invention).

  By controlling the rotation speed adjusting means 20 or / and the heating means 30 or / and the injection means 40 or / and the cooling means 50, the cooling rate of each molten material can be adjusted (seventh invention).

  By controlling the rotation speed adjustment means 20 and / or the injection means 40, the thickness of each layer can be adjusted (eighth invention).

  In the ninth and tenth inventions, the laminate 100 used for the thermoelectric element is manufactured on the assumption that the material is a thermoelectric semiconductor material.

FIG. 1 is a diagram illustrating a configuration of a laminated body manufacturing apparatus according to an embodiment. FIG. 1A is a cross-sectional view of the apparatus, and FIG. 1B is a cross-sectional view of FIG. FIG. FIG. 2 is a diagram illustrating the configuration of the ejection unit and the heating unit. FIG. 3 is a diagram showing a configuration example different from the apparatus of FIG. FIGS. 4A and 4B are diagrams illustrating a configuration example of a mold. 5A and 5B are diagrams illustrating a configuration example of a mold. 6A and 6B are diagrams illustrating a configuration example of a mold. 7A and 7B are diagrams illustrating a configuration example of a mold. FIG. 8A is a diagram showing a thermoelectric element manufacturing process (comparative example manufacturing process) listed as a comparative example, and FIG. 8B shows a thermoelectric element manufacturing process (example manufacturing process) of the embodiment. FIG. FIG. 9 is a diagram schematically showing the crystal structure of the thermoelectric semiconductor material of the embodiment. FIG. 10 is a diagram schematically showing the crystal structure of the laminate produced in the centrifugal quenching step. FIG. 11 is a schematic diagram for explaining the mechanism by which the laminate 100 is generated in the centrifugal quenching process. FIG. 12 is a diagram for explaining the pressure heat treatment. FIG. 13 is a diagram illustrating a lapping process, a plating process, and a dicing process. FIG. 14 is a photograph showing a structure in a cross section of the laminate observed with a microscope. FIG. 15 is a photograph showing the structure when the cross section of the laminate is observed with a microscope. FIG. 16 is a photograph showing the structure when the cross section of the laminate is observed with a microscope. FIG. 17 is a photograph showing an image when the cross section of the laminate is observed with a microscope. FIG. 18 is a diagram illustrating a measurement result obtained by the electron backscattering method. FIG. 19 is a diagram showing a measurement result by an X-ray diffraction method different from the electron backscattering method. FIG. 20 is a diagram showing the results of measuring the crystal growth orientation. FIG. 21 is a diagram showing the results of measuring the crystal growth orientation. FIG. 22 shows the results of measuring the crystal growth orientation.

Hereinafter, embodiments of a method for manufacturing a laminate and a manufacturing apparatus according to the present invention will be described with reference to the drawings.

  In the present embodiment, a laminated body made of a thermoelectric semiconductor material is assumed unless otherwise specified. However, the present invention is applied to a method and an apparatus for manufacturing a laminated body of crystal structure materials that require a crystal orientation in a certain direction such as a piezoelectric element, a magnetic material, and a superconducting material in addition to a thermoelectric semiconductor material. Can do.

  The thermoelectric semiconductor material of the embodiment includes at least one element selected from the group consisting of Bi and Sb, at least one element selected from the group consisting of Te and Se, and I, Cl, Hg, Br, A material having a composition containing at least one element selected from the group consisting of Ag, Cu, Ce, La, and Yb. For example, it is represented by the following chemical formula.

-Bi2Te3-XSe + 0.02-0.1Wt% BiBr3 (X = 0.3-0.6)
Bi2Te3-XSeX + 0.05 to 0.08 Wt% CeBr3 (X = 0.3 to 0.6)
・ Bi0.4Sb1.6Tey (Y = 3-3.02)
FIG. 1 shows a configuration of a laminate manufacturing apparatus according to an embodiment. 1A is a cross-sectional view of the apparatus, and FIG. 1B is a view of FIG.

  The apparatus of the embodiment mainly includes a mold 11 formed on the inner peripheral surface of the rotating body 10, a rotation speed adjusting means 20 for adjusting the rotation speed of the rotating body 10, a heating means 30 for melting the material, Injecting means 40 for injecting the molten material toward the mold 11, cooling means 50 for cooling the mold 11, rotation speed adjusting means 20 and / or heating means 30 or so that the molten material is laminated on the mold 11 And / or a control means 60 for controlling the injection means 40 or / and the cooling means 50.

  In the vacuum chamber 1, a rotating body 10, a heating unit 30, and an injection unit 40 are provided.

  The vacuum chamber 1 is provided for processing in an atmosphere that does not oxidize the material.

  The rotating body 10 is formed in a ring shape and is made of a material having good thermal conductivity (for example, copper).

  The rotating body 10 is connected to a cylindrical drum 12 so that heat can be transferred. The drum 12 is hollow inside, and a cooling water channel 12a is formed.

  The output shaft 20a of the rotation speed adjusting means 20 is connected to the rotation shaft 21a of the drum 12 so that rotational power can be transmitted. The rotating body 10 and the mold 11 on the inner peripheral surface thereof may be integrally formed of the same material, or may be formed separately. Various shapes of the mold 11 will be described later.

  The rotational speed adjusting means 20 includes a rotary actuator such as an electric motor or a hydraulic motor. When the rotational speed adjusting means 20 is driven, the rotational force is transferred from the output shaft 20a to the drum 12 via the rotational shaft 21a. , The drum 12 rotates, and accordingly, the rotating body 10 and the inner mold 11 rotate about the center of the rotating shaft 21a.

  The rotation speed adjustment means 20 is controlled by the rotation speed control unit 62 of the control means 60. The rotation speed control unit 62 can control the rotation speed (unit: rpm) of the mold 11.

The cooling means 50 includes a cooling water pump (not shown), a cooling water tank, a heat exchanger, cooling water circulation paths 51A and 51B, and a cooling water path 12a in the drum 12. The cooling water circulation paths 51A and 51B communicate with the cooling water path 12a in the drum 12. The cooling water in the cooling water tank is sucked up by the cooling water pump and passes through the cooling water circulation path 51A. The cooling water is spread and filled in the cooling water channel 12a. The cooling water that has passed through the cooling water passage 12a in the drum 12 is sent to the heat exchanger via the cooling water circulation passage 51B for heat exchange, and then returned to the cooling water tank.

  When the drum 12 is cooled, the heat of the rotating body 10 and the mold 11 connected thereto is taken away. Therefore, the mold 11 is cooled, and the inner peripheral surface of the rotating body 10 becomes a cooling surface.

  However, if the drum 12 and the mold 11 (the rotator 10) are separated, a thermal resistance exists between the drum 12 and the mold 11, and thus the mold 11 may not be efficiently cooled. For this reason, the mold 11 (rotating body 10) and the drum 12 are integrally formed, or the function of the drum 12 is provided in the mold 11 (rotating body 10) to eliminate the need for the drum 12, thereby increasing the cooling efficiency. May be. In this case, the cooling efficiency may be further improved by providing a cooling water channel inside the mold 11 and directly cooling the mold 11.

  The cooling unit 50 is controlled by the cooling control unit 65 of the control unit 60. For example, the cooling means 50 is provided with means for adjusting the amount of cooling water supplied to the heat exchanger, and is controlled by the cooling control unit 65 to control the cooling temperature of the cooling surface of the mold 11, that is, the rotating body 10. can do.

  The ejection means 40 is configured including a nozzle 41. The heating means 30 includes a heater 31. The heater 31 is configured as a winding heater wound around the nozzle 41.

  The structure of the injection means 40 and the heating means 30 is shown in detail in FIG.

  That is, the heater 31 is housed inside the housing 42. The heater 31 is divided into a heater 31 </ b> A at the upper side of the housing 42 in the drawing and a heater 31 </ b> B at the lower side of the housing 42 in the drawing. Independent power supply lines 32A and 32B are connected to the heaters 31A and 31B, respectively, and power is applied individually. For this reason, the heating amount of the heaters 31A and 31B can be individually controlled.

  The wall of the housing 42 functions as a heat insulating member that insulates the heat generated by the heater 31 so as not to escape outside. Inside the heater 42, a nozzle 41 made of a quartz tube is inserted inside the heater 31.

  In the nozzle 41, a solidified thermoelectric semiconductor material is supplied and stored. When electric power is supplied to the heater 31, the nozzle 41 is heated, and the thermoelectric semiconductor material in the nozzle 41 is brought into a molten state suitable for injection.

An injection port 43 for injecting the thermoelectric semiconductor material toward the mold 11 is formed at the tip of the nozzle 41. The shape of the ejection port 43 can be an arbitrary shape such as a circular or rectangular slit according to the purpose. The casing 42 is formed with a window 44 for allowing the material injected from the injection port 43 to pass toward the mold 11. The injection angle α with respect to the mold 11 can be freely changed in the range of 30 ° to 90 ° by adjusting the posture of the housing 42 as described later.
As described above, the heater 31 is divided into two parts in order to melt the material without evaporating it, and to raise the temperature at or near the injection port 43 to a temperature suitable for ejecting the molten material. is there. Here, if the heater 31 is composed of a single winding heater, local temperature unevenness occurs, the material partially evaporates and deviates from the original composition weighed, and the desired composition cannot be obtained. In some cases, the molten material may not reach a temperature suitable for injection near the injection port 43. Therefore, in order to avoid such a situation, it is desirable that the heater 31 is composed of a plurality of winding heaters divided into at least two parts, and is provided around the nozzle 41 along the vertical direction of the nozzle. Thereby, the temperature for melting the material can be controlled by the heater above the nozzle 41, and the temperature for ejecting the material can be controlled by the heater below the nozzle 41.

  A thermocouple 33 is provided in the nozzle 41 for monitoring the temperature at the tip of the nozzle 41, that is, the temperature of the molten material near the injection port 43. The temperature (signal) detected by the thermocouple 33 is used as a feedback signal in a control system that controls the temperature of the molten material near the injection port 43 to a target temperature. An electric signal line 34 is electrically connected to the thermocouple 33.

A tube 35 for protecting the thermocouple 33 and preventing adhesion with the material is provided in the nozzle 41.

  The casing 42 is provided with thermocouples 36A and 36B for monitoring the temperatures of the heaters 31A and 31B which are divided into two. The temperature (signal) detected by the thermocouples 36A and 36B is used as a feedback signal in a control system that controls the voltage applied to the heaters 31A and 31B, that is, the heating amount to a target value. Electrical signal lines 37A and 37B are electrically connected to the thermocouples 36A and 36B, respectively.

  Pipes 38A and 38B for taking out the power supply lines 32A and 32B and the electric signal lines 37A and 37B to the outside for each of the heaters 31A and 31B are connected to the casing 42. The power supply lines 32A and 32B and the electric signal lines 37A and 37B are electrically connected to the control means 60.

  A seal member 45 for vacuum-sealing the inside of the nozzle 41 is attached to the upper surface of the housing 42 in the drawing. The seal member 45 is formed with holes for communicating the inside of the nozzle 41 with the external pressurization pipe 46, the decompression pipe 47, and the thermocouple extraction pipe 48.

  The pressurizing pipe 46 is connected to an argon gas supply source (not shown), and is supplied with argon gas having a pressure capable of pressurizing the inside of the nozzle 41 and jetting the material. An inert gas other than argon gas may be used. The decompression pipe 47 is connected to a vacuum pump (not shown), and is evacuated to a pressure at which the inside of the nozzle 41 can be decompressed to stop the material injection.

  An electric signal line 34 is inserted into the thermocouple extraction pipe 48 and is electrically connected to an external control device 60.

  As shown in FIG. 1, the position and posture of the housing 42 can be adjusted by a position / posture adjusting means 49. That is, by operating the position / posture adjusting means 49, the position of the housing 42 in the height direction H of the mold 11, the position of the mold 11 in the width direction W, and the posture of the tilt direction G with respect to the mold 11 are changed. Can do.

  Further, as shown in FIG. 3, the position / posture adjusting means 49 may include an XYZ stage. In the apparatus of FIG. 3, a gripping device 70 is provided for gripping and taking out the laminated body generated by the mold 11. The laminate produced by the mold 11 is a thin ring-shaped thermoelectric semiconductor material. The gripping portion 71 of the gripping device 70 has a surface made of a flexible material such as rubber and operates so as to spread in the diameter direction of the circle by a three-way chuck. The gripping device 70 can be moved to an arbitrary position by the XYZ stage 70a. Therefore, by driving the XYZ stage 70 a, the gripping portion 71 of the gripping device 70 is inserted into the rotating body 10, and the gripping portion 71 is pushed and expanded in the direction of the contact surface of the mold 11. Grasped. Then, the XYZ stage 70a is driven, the gripping device 70 is returned to the original position, and the gripping portion 71 is contracted in the center direction of the ring of the stack, so that the stack is separated and a predetermined place Can be placed.

  The heating unit 30 is controlled by the temperature control unit 63 of the control unit 60. That is, based on the detected temperature of the thermocouple 33, the temperature of the molten material in the vicinity of the injection port 43 is controlled to become the target temperature. Further, the applied voltage (heating amount) of the heaters 31A and 31B is controlled based on the detected temperatures of the thermocouples 36A and 36B.

  The injection unit 40 is controlled by the injection control unit 64 of the control unit 60. That is, by supplying argon gas into the nozzle 41 from an argon gas supply source (not shown) through the pressurizing pipe 46, the inside of the nozzle 41 is brought to a positive pressure, and the molten material is injected from the injection port 43 toward the mold 11. Can be made. Further, the injection of the molten material from the injection port 43 can be stopped by operating the vacuum pump to make the inside of the nozzle 41 have a negative pressure via the pressure reducing pipe 47. Argon gas may be continuously supplied, and the supply may be stopped after completion of the laminated body and evacuated (hereinafter referred to as continuous injection), and a pressurized state (material injection) and a reduced pressure state (material injection stopped) are predetermined. The laminated body may be completed by repeating the width and a predetermined pattern (hereinafter, intermittent injection). The width and pattern of the pressure state (material injection) and the pressure reduction state (material injection stop) are programmed in advance. For example, the molten material can be injected with a width and pattern of “injection for 1 second and stop injection for 1 second”.

  The position / posture adjusting means 49 may be manually controlled or automatically controlled. In the case of automatic control, the position / posture adjustment means 49 is controlled by the position / posture control unit 69 of the control means 60. Thereby, the injection angle α with respect to the mold 11 can be automatically controlled to a desired angle. Moreover, the height of the injection port 43 with respect to the mold 11 can be automatically controlled to a desired height. This is because it may be necessary to adjust the height of the injection port 43 depending on the stacking height of the stacked body. Further, the position of the injection port 43 in the width direction W with respect to the mold 11 can be automatically controlled to a desired width direction position.

  The internal pressure of the vacuum chamber 1 is controlled by the internal pressure control unit 66 of the control means 60. That is, before heating the nozzle 41 with the heaters 31A and 31B, the inside of the vacuum chamber 1 is evacuated to reduce the pressure so that almost no air is present, and an inert gas such as argon gas or nitrogen gas is supplied. And the inside of the vacuum chamber 1 is made into the state of about atmospheric pressure (normal pressure). Then, the nozzle 41 is heated by the heaters 31A and 31B to inject the molten material.

  Next, a configuration example of the mold 11 will be described.

  The configuration of the mold 11 is related to the product quality of the laminate, and will be described below while incorporating the production mechanism of the laminate.

  When the molten material is ejected from the ejection port 43 of the nozzle 41 while rotating the mold 11, the material layers are sequentially stacked on the mold 11.

  The thermoelectric performance changes according to the injection angle α with respect to the mold 11 (depending on whether the injection is performed perpendicularly or obliquely to the surface). When the spray angle α is an angle close to 90 °, sputtering occurs and a powdery material is reattached, so that a beautiful film cannot be formed and the orientation of crystal orientation is deteriorated. Therefore, it is important to land the material without causing the mold 11 to sputter the spray angle α as close to 0 ° as possible. Actually, the inner peripheral surface of the rotator 10 has a curvature, and it is difficult to make it incident at an injection angle of 0 ° parallel to the surface having the curvature. Therefore, it is ideal that the material is incident as smoothly as possible on the mold 11.

  The shape of the mold 11 can be a circular shape having the same depth if the inner peripheral surface of the rotating body 10 has a circular shape when viewed from the axial direction of the rotating shaft 21a. If the inner peripheral surface of the rotating body 10 has a polygonal shape having a depth when viewed from the axial direction of the rotating shaft 21a, the polygonal shape having the same depth can be obtained. In this case, a recess may be formed on the inner peripheral surface of the rotator 10, and the inner peripheral surface of the rotator 10 may be a flat surface. Even when the concave portion is formed on the inner peripheral surface of the rotating body 10, the concave portion may be formed continuously and integrally along the circumferential direction, or formed so that a plurality of concave portions are arranged along the circumferential direction. May be.

  4, 5, 6, and 7 exemplify a configuration example of the mold 11. 4 (a), FIG. 5 (a), FIG. 6 (a), and FIG. 7 (a) are cross-sectional views of the rotator 10 as seen from the same side as FIG. 1 (a). b), FIG. 5B, FIG. 6B, and FIG. 7B are the same arrow A views as FIG. 1B.

  FIG. 4 shows a mold 11 which is formed in a circular shape corresponding to the inner peripheral surface of the rotating body 10 and is configured so that the inner peripheral surface of the rotating body 10 is a flat surface.

FIG. 5 shows a mold that is formed in a circular shape corresponding to the inner peripheral surface of the rotating body 10, and in which concave portions are formed continuously and integrally along the circumferential direction of the inner peripheral surface of the rotating body 10. 11.

FIG. 6 shows a mold 11 formed in a polygonal shape along the inner peripheral surface of the rotating body 10.

FIG. 7 shows a mold 11 that is formed in a polygonal shape along the inner peripheral surface of the rotating body 10 and is configured by arranging a plurality of concave portions along the circumferential direction of the inner peripheral surface of the rotating body 10. .

In the mold 11 shown in FIGS. 4, 5, and 6, a laminated body integrated in a ring shape can be generated.
In the mold 11 shown in FIG. 7, a plurality of laminated bodies are generated corresponding to the plurality of recesses. However, in the metal mold 11 shown in FIG. 7, since there is a convex portion between adjacent concave portions, the injected material hits the convex portion, and sputtering is likely to occur. For this reason, it is desirable to prevent the sputtering by minimizing or eliminating the convex portion.

  In the mold 11 shown in FIG. 5, the width of the concave portion is narrower than the width of the inner peripheral surface of the rotating body 10, and the lateral width of the stacked body is defined by the width of the concave portion.

  In the mold 11 shown in FIGS. 4, 6, and 7, the lateral width of the laminated body is defined by the lateral width of the inner peripheral surface of the rotating body 10. However, depending on the ability of the nozzle 41, the laminated body is not generated in a large area that is full of the lateral width of the inner peripheral surface of the rotating body 10, and the lateral width of the laminated body is the injection range of the material injected from the nozzle 41. Limited by. The injection range (horizontal width of the laminate) is determined by the number of rotations of the rotating body 10 and the injection speed (argon gas pressure). For this reason, the nozzle 41 may be changed in the lateral width direction of the inner peripheral surface of the rotating body 10 in order to make the injection width of the material desired. That is, the lateral width of the multilayer body can be controlled to a desired lateral width by generating the multilayer body while sequentially shifting the position of the injection port 43 in the lateral width direction W with respect to the mold 11 by the position / posture adjusting means 49. .

  Further, the ejection port 43 of the nozzle 41 may be a rectangular slit, and the ejection range in the lateral width direction may be defined by the slit width, so that the lateral width of the stacked body may be a desired lateral width. Further, by providing a plurality of fixed nozzles 41 in the lateral width direction of the inner peripheral surface of the rotating body 10, the spray range in the lateral width direction may be defined, and the lateral width of the stacked body may be set to a desired lateral width.

  Next, a thermoelectric element manufacturing process (hereinafter referred to as an example manufacturing process) in the present embodiment will be described with reference to FIG.

  FIG. 8A shows a manufacturing process of a thermoelectric element as a comparative example (hereinafter referred to as a comparative example manufacturing process). This manufacturing process is based on the inventions described in JP-A-10-178219 and JP-A-2000-124512.

First, a comparative example manufacturing process will be described.

(Weighing / Encapsulation process)
As an example of the composition, bismuth Bi, tellurium Te, and selenium Se, which are raw materials for thermoelectric semiconductor materials, are weighed to achieve a desired stoichiometric ratio, and further Ce and Br compounds for adjusting the carrier concentration are used. What is added in an appropriate amount is mixed and sealed in a glass tube 80.

(Dissolution / solidification process)
Next, the raw material mixture of the thermoelectric semiconductor material is put in the glass tube 80 and dissolved in the heater 81. Next, power supply to the heater 81 is cut off to solidify the raw material mixture. Next, the solidified raw material mixture is taken out from the glass tube 80.

(Milling process)
The solidified raw material mixture is placed in a crucible 83 above a disk 82 that rotates at high speed. Dissolve again until heated to 700-800 ° C by heating with a heater. As a result, the liquid droplet falls from the hole under the crucible 83 onto the disk 82. For this reason, the liquid droplets dropped on the disk 82 are pulverized and scattered to obtain a powdered raw material.

(Hot press process)
Next, the scattered and powdered raw material is collected and filled in the mold of the hot press device 84. The hot press device 84 is operated to pressurize the raw material and simultaneously heat around the raw material to harden the raw material. That is, pressure and sintering are performed simultaneously. In the pressure-sintered body immediately after the hot pressing step, although the density is high, the orientation of the crystal orientation is not uniform and is not uniform, and the thermoelectric performance is not good.

(Plastic processing process)
Next, plastic working is performed in order to align the crystal orientation. For example, extrusion molding is performed. A rectangular parallelepiped sintered body of the thermoelectric semiconductor material is placed in a die (extrusion die) 85, the punch is pushed down from above, and the sintered body in the die 85 is extruded from an extrusion port 86 with a reduced cross-sectional area and extruded. Get a molded product. The crystal orientation is reoriented by rotating the crystal grains by the extrusion molding process, and the crystal orientation is aligned.

(Heat treatment process)
Next, heat treatment is applied to improve the distortion of the extruded product. Depending on the product, heat treatment may be performed to change the electrical resistance. In addition, implementation without performing this heat treatment process is also possible.

(Slicing process)
Next, the extruded product is sliced into a wafer having a predetermined thickness.

(Plating process)
Next, in order to join an electrode to the thermoelectric element, the sliced wafer is plated.

(Dicing process)
Next, the wafer is diced to obtain a large number of fine rectangular parallelepiped thermoelectric elements 90.

(Assembly process)
Next, a thermoelectric module 91 is created using the obtained rectangular parallelepiped thermoelectric element 90. That is, the electrode 87 is bonded to the upper and lower substrates 88A and 88B. Then, the electrode 87 is joined to the thermoelectric element 90 so that the thermoelectric element 90 is sandwiched between the upper and lower substrates 88A and 88B. Thus, the thermoelectric elements 90 are arranged so as to spread two-dimensionally on the surfaces of the substrates 88A and 88B.

(Inspection process)
Next, a finished product of the thermoelectric module 91 is inspected.

  The thermoelectric element 90 obtained by the comparative example manufacturing process has a limit in the orientation ratio of crystal orientation. In addition, many processes are required, and the manufacturing time is long and the production efficiency is poor.

  On the other hand, in the example manufacturing process, the above-described weighing / enclosing step and dissolution / solidification step are the same as in the comparative example manufacturing process, but instead of the milling step, hot pressing step, and plastic working step. In addition, a centrifugal quenching step is performed to generate a laminate having a predetermined stacking height (predetermined thickness). Since the stacked body is generated at a predetermined stacking height (when the predetermined thickness is thin), a slicing step for slicing to a predetermined thickness is not necessary. When it is thick, a conventional process is required. However, since the laminated body is formed along the inner peripheral surface having the curvature of the rotating body 10, the upper surface of the laminated body is not necessarily flat. For this reason, the lapping process which grind | polishes and planarizes the upper surface of a laminated body is needed. In the lapping step, the laminated body is lapped using a lapping device 92. After the lapping process, a plating process, a dicing process, an assembly process, and an inspection process are performed as in the comparative example manufacturing process. However, in the centrifugal quenching process, the melted material is rapidly solidified to produce a laminate, and as such, there is a risk that distortion will accumulate and it will be easily broken. Therefore, heat treatment may be performed in a later step in order to remove distortion.

Hereinafter, the content of the same process as the comparative example manufacturing process is omitted as appropriate, and the example manufacturing process will be described with reference to FIG.

(Centrifuge quenching process)
In the centrifugal quenching process, the molten material is supplied to the cooled surface so as to be laminated in the direction perpendicular to the surface, and an acceleration force according to the weight of the molten material is applied to the cooling surface. As a result, a temperature gradient is generated in the thickness direction of the layer, and the molten material is rapidly solidified while pressing the cooling surface against the cooling surface, so that the C plane of the crystal grains rises along the thickness direction of the layer, and the interlayer interface This refers to a process for producing a laminated body having a crystal structure in which s.

  Specifically, the cooling surface is the inner peripheral surface of the rotating body 10, and the acceleration force is the centrifugal force of the rotating body 10. Moreover, a laminated body is produced | generated by inject | pouring molten material toward the metal mold | die 11 formed in the internal peripheral surface of the rotary body 10. FIG.

  Here we give definitions for the terms.

  The layer means a layer having a predetermined thickness formed for each operation such as one injection, one rotation, one reciprocation.

  An interlayer interface is a surface formed between layers and formed in a direction substantially perpendicular to the thickness direction of the layers.

  The intergranular interface is a surface between crystal grains in the same layer, and is a surface that is formed substantially perpendicular to the interlayer interface and substantially parallel to the thickness direction of the layer.

  FIG. 9 schematically shows the crystal structure of the thermoelectric semiconductor material of the embodiment. As shown in the figure, the crystal grain 110 is a hexagonal layered structure compound, which itself forms a single crystal. In the drawing, the hexagonal portion is the basal plane of the layered structure compound, which is a crystal plane called the C plane. The layered structure compound has a structure in which a large number of C-planes are stacked in the c-axis direction and spread in the a-axis direction. The carrier is most likely to flow in the direction parallel to the C-plane. Therefore, it can be said that the single crystal of the layered structure compound is the material having the highest electrical anisotropy.

  FIG. 10 schematically shows the crystal structure of the laminate 100 produced in the centrifugal quenching step.

The above-mentioned “layer”, “interlayer interface”, “intergranular interface”, “crystal grain 110”, and “C plane” are shown in the drawing.

  FIG. 10A is an external perspective view of the laminated body 100, in which a mold 11 serving as a cooling surface is located on the lower side in the figure, and the laminated body 100 is laminated with the passage of time toward the upper side in the figure. . 10B is an arrow A view of the side surface of the stacked body 100 shown in FIG. 10A, and FIG. 10C is an arrow view of the adjacent side surface of the stacked body 100 shown in FIG. FIG. In FIGS. 10B and 10C, hatched portions are portions where crystal grains 110 exist, and white portions indicate crystal grains 110 grown across the layers.

  FIG. 11 is a schematic diagram for explaining the mechanism by which the laminate 100 is generated in the centrifugal quenching process. Hereinafter, a description will be given with reference to FIG.

As shown in FIG. 11A, when the molten material is ejected from the injection port 43 of the nozzle 41 while rotating the mold 11, the molten material lands on the mold 11 (cooling surface). Then, a centrifugal force corresponding to the mass of the molten material acts on the molten material, and the molten material is pressed against the mold 11 (cooling surface). Since the mold 11 is rotating, the layers are further overlapped when the injection of the molten material is continued by continuous injection or intermittent injection as described above. As a result, the mass of the material landed on the mold 11 increases, so that a larger centrifugal force acts, and the material is pressed with a larger force to increase the density of the laminate 100 (density improvement effect).

  As shown in FIG. 11 (b), when one layer of molten material has landed on the mold 11, heat flows in a direction from the material toward the mold 11. That is, since the molten material is high temperature and the mold 11 serving as a cooling surface is low temperature, a temperature gradient is generated in the thickness direction of the material layer, and a heat flow toward the mold 11 is formed. At the moment when the molten material lands on the mold 11, a heat flow toward the mold 11 is formed in the direction perpendicular to the normal direction of the inner peripheral surface of the rotating body 10. As a result, the material gradually solidifies vertically upward from the mold contact surface, and rapidly solidifies. With the start of solidification, crystal growth starts in the layer thickness direction from the mold contact surface, and crystal grains 110 with the C-plane standing in the layer thickness direction grow. The rotating body 10 is rotated while one crystal growth is completed or completed, and one more layer is sprayed on the one layer. Therefore, in the upper layer as well, heat flows in the same direction as the thickness of the layer. Similarly, the material solidifies in the direction vertically upward from the mold contact surface, and crystal growth is caused by the thickness of the layer. Get up in the direction. An interlayer interface is formed between the layers. In the same manner, the material is rapidly solidified for each layer, and the laminate 100 is aligned in the crystal orientation in the height direction of the laminate 100. In this way, the C-plane of the crystal grain 110 stands up along the thickness direction of the layer, and the laminated body 100 having a crystal structure in which an interlayer interface exists is produced (orientation rate improving effect).

However, as described above, it is desirable that the molten material be incident in a direction that is nearly parallel to the contact surface (an injection angle α is close to 0) in order to avoid sputtering. This is to prevent the material scattered by sputtering from adhering to a layer formed later and disturbing the crystal orientation. In the centrifugal quenching process of the present embodiment, the laminated body 100 having a predetermined thickness is generated while improving the density and the orientation ratio. Therefore, the milling process, the hot pressing process, and the plastic working that are necessary in the comparative example manufacturing process. The process and the slicing process can be omitted. Further, the weighed material is put into the nozzle 41, and it is encapsulated, dissolved and coagulated as it is, and if it shifts to the centrifugal quenching process, the two steps before the centrifugal quenching process (“Weighing / encapsulating process”, “Melting / coagulating process”) are performed. It is possible to save time by omitting the step “).

(Heat treatment process)
Since the rapid solidification may cause distortion or the composition may be non-uniform, heat treatment is performed to remove the distortion or make the composition uniform. As a heat treatment method, there are a normal pressure heat treatment method in which the laminated body 100 is put in an electric furnace at normal pressure and annealing, and a heat treatment method in which annealing is performed while applying pressure so that the aligned crystal grains 110 are not broken. .

FIG. 12 is a diagram for explaining the pressure heat treatment. That is, the laminated body 100 (FIG. 12A) whose C-planes are aligned in the vertical direction in the figure is inverted by 90 ° and placed in the mold of the press device 120 as shown in FIG. While heating, pressurize in the direction perpendicular to the a-axis. This is because, when pressed parallel to the a-axis, the crystal grains 110 are finely broken at the interlayer interface and the crystal orientations are dispersed, which may reduce the thermoelectric performance. Heat treatment under pressure is performed at a temperature of 350 ° C. to 500 ° C. for 10 minutes to 120 minutes, heat treatment without pressure is performed for 60 to 1200 minutes in an inert gas atmosphere, while annealing in an inert gas atmosphere A press is performed.

(Lapping process)
Next, the upper surface of the laminate 100 is polished as necessary.

  FIG. 13 is a diagram illustrating a lapping process, a plating process, and a dicing process. The mold 11 is formed in a polygonal shape along the inner peripheral surface of the rotating body 10 similarly to the mold 11 shown in FIG. 7, and a plurality of concave portions are arranged along the circumferential direction of the inner peripheral surface of the rotating body 10. This is a mold 11 configured as described above. However, the mold 11 is configured so that it can be taken out from the rotating body 10 by being divided for each recess (FIG. 13A).

  The divided mold 11 is taken out from the rotating body 10 (FIG. 13B) and fixed on the jig 121 so that the upper surface of the laminated body 100 is disposed upward (FIG. 13C). . Next, it grind | polishes so that the upper surface of the laminated body 100 may become flat. Or it cut | disconnects as needed (FIG.13 (d)). Next, using another jig 122, the upper surface (front surface) of the laminated body 100 is adhered and taken out from the mold 11, and the rear surface of the laminated body 100 is polished and dimensioned (FIG. 13 (e)). Then, the wafer of the laminated body 100 is acquired (FIG. 13F).

(Plating process)
As shown in FIG. 13G, the wafer of the laminate 100 is dipped in a plating solution and subjected to a plating process.

(Dicing process)
Next, the wafer of the laminated body 100 is diced (FIG. 13 (h)), and a large number of fine cuboid thermoelectric elements 90 are obtained (FIG. 13 (i)).

  Hereinafter, the assembly process and the inspection process are performed in the same manner as the comparative example manufacturing process.

  The above process is an example, and by interposing a process of another process in the centrifugal quenching process, an intermediate process can be appropriately omitted or the time required for the process can be shortened.

  For example, a rectangular parallelepiped shape that is the final form of the thermoelectric element 90 may be formed in the mold 11 using the mold 11 formed in a lattice shape. Thereby, a dicing process can be made unnecessary.

  In the centrifugal quenching step, a nozzle for injecting a plating solution may be prepared in addition to the nozzle 41 for injecting the molten material, and the plating layer may be formed on the thermoelectric element layer. Thereby, a plating process can be made unnecessary.

As described above, according to the manufacturing method of the present embodiment, the number of steps can be reduced as compared with the comparative example manufacturing process, the time required for all the steps can be shortened, and the production efficiency can be improved. . In addition, since the density and orientation ratio are improved in the centrifugal quenching process and the laminate 100 is generated, the orientation ratio of crystal orientation is extremely improved as compared with the product manufactured by the comparative example manufacturing process.

  The structural features of the laminate 100 will be described with reference to FIG.

  The laminated body 100 has the following structural features.

  The stacked body 100 has a polycrystalline structure composed of a single crystal layer (crystal grains 110) whose C-plane is erected along the thickness direction of the layers.

  Each layer is composed of a plurality of single crystals (crystal grains 110) whose a axes coincide with each other.

Single crystals (crystal grains 110, 110) adjacent to each other in the crystal growth direction have an a-axis coincidence and do not coincide with the c-axis, thereby forming an interlayer interface. That is, as schematically shown in an enlarged view in FIG. 10 (d), the crystal grains 110 and 110 in the upper layer and the lower layer are aligned with the a-axis and deviated from the c-axis (however, the C-plane stands upright). An interlayer interface is formed. When the a-axis is aligned and the c-axis is not aligned, or when the a-axis is aligned and there is a crystal defect between the c-axes, the upper-layer crystal grains 110 are formed on the lower-layer crystal grains 110. They are just on board and the crystals are not continuous. However, as will be described later, the c-axis is not shifted in every part between the layers, and the c-axis coincides in a part between the layers, and epitaxial growth is performed across the layers. It has become.

  As schematically shown in FIG. 10E, a part of single crystals (crystal grains 110, 110) adjacent to each other in the crystal growth direction have the same a-axis and the same c-axis across the layers. Thus, it is formed by epitaxial growth. In this part, crystals are continuous and do not constitute an interlayer interface.

  When the orientation ratio of the crystal orientation of all the crystal grains 110 constituting the laminate 100 was measured, it was confirmed that the C plane had an orientation ratio of 90% or more at ± 10 ° as will be described later.

From the above, according to the laminate 100 of the present embodiment, the following effects can be obtained.

  That is, the laminate 100 of the present embodiment has a layered structure with a high orientation ratio, a high density, and an interlayer interface. Due to these characteristics, the following effects can be obtained.

(Improvement of thermoelectric performance)
The C-plane stands up in the thickness direction of the laminate 100 and the a-axis is aligned with a very high orientation rate. For this reason, when energization is performed with the direction in which the a-axis is oriented as the energization direction, the electrical resistivity is extremely reduced, and high thermoelectric performance (thermoelectric characteristics) is obtained. In addition, since there is an epitaxially grown portion where the orientation of the crystal grains 110 is continuous so as to straddle between the layers, the electrical characteristics are further excellent.

  In addition, since the thickness of the layer is less than submicron (0 comma several microns) and an interlayer interface exists, lattice thermal conduction scattering occurs at the interlayer interface, and the lattice thermal conductivity decreases. Thereby, the thermoelectric performance can be further improved.

  Further, the density is high, the electrical resistivity is reduced, and a further high thermoelectric performance is obtained.

(Improvement of mechanical strength)
The laminate 100 has a polycrystalline structure and has a high mechanical strength structurally.

The presence of the interlayer interface and the intergranular interface within the layer results in high mechanical strength.
Further, it has a high density, and a higher mechanical strength can be obtained and oxidation can be prevented.

In addition, since some crystal grains are epitaxially grown so as to straddle between layers, the epitaxially grown crystal grains act as a “wedge” that connects the layers, further increasing the mechanical strength. improves.

Thus, a mechanical strength of a certain level or more is ensured while having a predetermined thickness (predetermined height).

  Therefore, a thermoelectric element (thermoelectric module) excellent in thermoelectric performance and durability can be provided to the market, which is extremely useful industrially.

(Example)
The manufacturing method of the present invention was carried out, and it was confirmed that those skilled in the art could easily realize it. And the structure of the obtained laminated body 100 was observed and measured. As a result, the following was found.

The heating temperature of the material by the heater 31 needs to be at least the melting point temperature (580 ° C.) at which the material melts. However, the temperature near the melting point is not desirable because it causes difficulty in injection if there is a strong viscosity, and is a temperature (from 610 ° C.) raised to some extent (from 30 ° C.) above the melting point so that the material can be injected from the injection port 43. In addition, it is desirable to set the temperature to a temperature at which the material does not evaporate.

At a distance of 10 mm from the nozzle 41, the temperature of the molten material was detected by the thermocouple 33. When an experiment was conducted in the temperature range of 630 ° C. to 650 °, a good result was obtained in the performance of the laminate 100.

  When the experiment was performed with the number of revolutions of the rotating body 10 (drum 12 and mold 11) set to 960 rpm, good results were obtained for the performance of the laminate 100. However, it is considered that the optimum rotational speed varies depending on differences in the diameter of the rotating body 10 and the cooling performance of the cooling means 50.

  The injection pressure was set to 0.17 MPa. As the injection pressure increases, the performance tends to improve.

  When the molten material is injected by intermittent injection, the performance tends to improve as the ratio of ON / OFF (injection stop) ratio ON / OFF (unit: second) approaches 1/0 (continuous injection). When the on / off ratio is between 1/0 and 1/1, a good laminate 100 can be obtained.

  When the injection port 43 of the nozzle 41 is a round hole having a diameter of 0.5 mm, a rectangular slit having a corner of 1.0 × 0.5 and a corner of 1.0 × 0.3, a good result in the performance of the laminate 100 was gotten.

  The mold 11 had almost no difference in the performance of the laminate 100 regardless of whether it was polygonal or circular.

  It is considered that the structure and thermoelectric performance of the laminate 100 change depending on each parameter.

a) Relation to structure By increasing the cooling rate of each molten material, the interlayer interface tends to become clearer.

The cooling rate can be reduced by reducing the amount of molten material injected per unit area per unit time, or by increasing the rotational speed of the rotating body 10 (drum 12, mold 11), and intermittent injection. (Intermittent injection), or by increasing the off time during intermittent injection, or by lowering the temperature of the mold 11, thereby making the interlayer interface more clear. Specifically, the cooling rate can be increased by controlling the rotation speed adjusting means 20 or / and the heating means 30 or / and the injection means 40 or / and the cooling means 50.

  FIG. 14 is a photograph showing a structure in a cross section of the laminate 100 observed with a microscope.

  The cooling rate was increased in the order of FIG. 14 (a), FIG. 14 (b), and FIG. 14 (c). From these figures, it can be seen that the lower the surface temperature, the greater the temperature difference between the layers, indicating a higher degree of orientation and making the interlayer interface clearer.

  As the rotational speed of the rotating body 10 increases, the layer thickness tends to decrease.

b) Relationship with Thermoelectric Performance By increasing the cooling rate of each molten material, the crystal orientation is improved, the electrical resistivity is lowered, and the thermoelectric performance is improved.

  When the layer thickness is reduced to submicron (0 comma several microns) or less, the heat conduction at the interlayer interface is deteriorated (because heat is scattered at the interlayer interface), and the thermoelectric performance is improved. That is, the smaller the injection amount, the thinner the thickness. The higher the injection pressure, the more the material spreads in the lateral direction with respect to the contact surface, so that the thickness becomes thinner. The higher the rotational speed of the rotating body 10, the thinner the thickness. In the experiment, a layer having a thickness of 10 μm to 20 μm was obtained, and good results were obtained in the performance of the laminate 100.

  The density of the stacked body 100 varies depending on the centrifugal force of the rotating body 10. The centrifugal force varies depending on the rotation speed (rpm). Therefore, the density varies greatly depending on the rotation speed. However, if there is too much difference between the rotation speed (the number of rotations) and the injection speed, the material tends to splash and sputter on the contact surface with the mold 11. More desirably, the rotational speed component and the rotational speed component of the injection speed are the same, and the rotational speed may be increased in order to increase the density while maintaining the same. However, if the vertical component of the injection speed is increased, rebound will occur, which is considered to be limited.

  From the above, it is considered that the structure and performance of the laminate 100 can be controlled as follows.

  By adjusting the cooling rate for each layer of the molten material, the orientation ratio of the C plane of the crystal grains 110 can be adjusted.

  By controlling the rotation speed adjusting means 20 or / and the heating means 30 or / and the injection means 40 or / and the cooling means 50, the cooling rate for each layer of the molten material can be adjusted.

  The thickness of each layer can be adjusted by controlling the rotation speed adjusting means 20 and / or by controlling the injection means 40.

  15 and 16 show photographs of the crystal structure when the cross section of the laminate 100 is observed with a microscope. 15 and 16 are photographs taken to confirm that the laminate 100 has a laminated structure and a layered structure.

  FIG. 15 shows the crystal structure of the laminate 100 before heat treatment. FIG. 15 is a perspective view of the laminated body 100. In FIG. 15, a photograph of the crystal structure in the laminated body 100 is shown in FIG. 15A, and in FIG. The photograph of is shown in FIG.15 (b).

FIG. 16 shows the crystal structure of the laminate 100 after the heat treatment. 16 is a perspective view of the laminated body 100. In FIG. 16, a photograph of the crystal structure in the laminated body 100 is shown in FIG. 16A, and in FIG. The photograph is shown in FIG.

  From these photographs shown in FIG. 15 and FIG. 16, the laminated body 100 has a laminated structure in which each layer is clearly distinguished at an interlayer interface and overlapped over a plurality of layers regardless of the presence or absence of heat treatment in any part. It can be seen that it has a layered structure.

  In addition, the extrusion molded product obtained by the comparative example manufacturing process and the one manufactured by the method shown in the conventionally known patent document are “a layered structure in which each layer is clearly distinguished at an interlayer interface and overlapped over a plurality of layers, It is not observed as “structure”, and the product of the present invention can be clearly distinguished from conventional or existing products structurally.

  FIG. 17A is a microscopic image of a polished surface obtained by polishing a cross section of the laminate 100. FIG. 17B is a microscopic image of the etched surface obtained by etching the cross section of the stacked body 100, and shows an enlarged image of FIG. 17A. FIG. 17C is a microscopic image of a fractured surface of the laminate 100 and shows an enlarged image as compared with FIG.

  Although there is a slight difference in the clarity of the interlayer interface depending on the processing method, it can be seen that in any case, each layer is clearly distinguished at the interlayer interface and has a laminated structure or a layered structure in which a plurality of layers are overlapped. It can also be seen that the intergranular interface is clearly photographed. Further, it can be seen that some crystal grains 110 are epitaxially grown between the layers.

FIG. 18 is a diagram showing the measurement result of the crystal orientation distribution by the electron backscattering method.

  FIG. 18A is an image of an etched surface obtained by etching the cross section of the stacked body 100, and is an image obtained by an electron backscattering method. The orientation ratio of the crystal orientation in the part surrounded by the broken line in the figure was measured. FIG. 18B is an inverted pole figure of a portion surrounded by a broken line in FIG. It was confirmed that in most portions, the a axes of the crystal grains 110 were aligned along the stacking direction, and the C plane was erected perpendicular to the film thickness direction. It was also confirmed that some crystal grains 110 were epitaxially grown between the layers. In the figure, the same color (same tone) portion indicates a portion where the C plane is inclined in the same direction by the same angle. The portion of similar color (approximate gradation) indicates a portion inclined in the same angle from the reference axis in the vertical direction, although the direction in which the C plane is inclined is different.

  FIG. 18C is a graph showing a C-plane orientation distribution in which the orientation ratio of crystal orientation is quantified. The horizontal axis is the angle of the C plane, and the vertical axis is the frequency d value (0.0 to 1.0). From this C-plane orientation distribution graph, it can be seen how many percent the crystal axis is tilted from the reference axis. Here, the reference axis refers to an axial direction corresponding to the energization direction or heat flow direction of the thermoelectric element 90.

  The orientation distribution of the laminate 100 obtained in the centrifugal quenching process of the present embodiment is indicated by “centrifugal quenching”. For comparison, the orientation distribution of the extruded product obtained in the comparative example manufacturing process is indicated by “HE”, and the hot forging obtained by performing the hot forging step in the plastic working step of the comparative example manufacturing process ( The orientation distribution of the hot forge product is indicated by “HF”.

  As shown by “centrifugal quenching” in the figure, when the orientation ratio of the crystal orientation of all the crystal grains 110 constituting the laminate 100 was measured, it was confirmed that the C plane had an orientation ratio of 93% at ± 10 °. . “±” means “in all directions in which the C-plane is inclined”. That is, 93% of all the crystal grains 110 have a C plane within an arbitrary tilt direction of 10 °. The angle from the reference axis of “centrifugal quenching” at the d value, that is, the half value (0.5) of the frequency, was 6 °.

As shown by “HE”, the extruded product was confirmed to have an orientation rate of 87% at the C-plane of ± 10 °. The d value (the angle from the reference axis of “HE” at half the frequency (0.5)) was 12 °.

As indicated by “HF”, it was confirmed that the hot forged product had an orientation rate of 77% at C surface of ± 10 °. The d value (angle of “HF” from the reference axis at half the frequency (0.5)) was 21 °.

FIG. 19 shows a measurement result by an X-ray diffraction method different from the electron backscattering method.

  As shown in FIG. 19A, the change in the reflection intensity when the incident angle is changed by making X-rays incident on the surface of the sample of the laminate 100 obtained in the centrifugal quenching process of the present embodiment is shown in FIG. Measurements were made as shown in b). As a result, an orientation ratio of 91% was obtained.

  For comparison, as shown in FIG. 19 (c), the change in the reflection intensity when the incident angle is changed by making X-rays incident on the surface of the sample of the extruded product obtained in the comparative example manufacturing process is shown. Measurement was performed as shown in FIG. As a result, an orientation ratio of 68% was obtained.

As described above, it is confirmed that the laminate 100 of the present embodiment has an orientation rate of 90% or more at a C-plane of ± 10 °, and the orientation rate is much higher than that of an extruded product or a hot forged product. I understood it.

  20, 21, and 22 show the results of measuring the crystal growth orientation.

  FIG. 20 shows a place where electron beam diffraction performed for examining the crystal growth orientation was performed. A sample is the laminated body 100 before performing heat processing. FIG. 20A is an etching image of a cross section of the stacked body 100, and FIG. 20B is an enlarged image of FIG. FIG. 20B shows the evaluation position, which is in the layer (1) and in the vicinity of the interlayer interface (2).

  20C and 20D show the TEM observation results. As shown in FIG. 20 (c), each part B, C, D in the layer and part A near the interlayer interface were evaluated. FIG. 20 (d) is an enlarged view of FIG. 20 (c).

  21 (a), (b), (c), and (d) show the results of electron diffraction performed at the respective portions A, B, C, and D shown in FIG. 20 (c). From this electron beam diffraction result and FIG. 20, it can be seen how the crystal is oriented, that is, which axis is tilted in which direction.

  FIG. 22 is a table summarizing the crystal growth orientations of the portions A, B, C, and D based on FIG. That is, the growth orientations of the respective parts A, B, C, and D are the same at [−4 5 0], and the crystal zone axis [uvw] is the same at [25 20 2]. Therefore, it was found that the crystal grains 110 were aligned in the a-axis direction at each part in the layer, and the crystal grains 110 were grown so as to be aligned in the a-axis direction across the layers.

  In the above description, the laminated body 100 of the present invention has been described as being produced by being laminated by injecting a molten material toward the inner surface of the rotating body 10. However, any manufacturing method and manufacturing apparatus can be used as long as the laminate 100 similar to the present embodiment can be manufactured. For example, you may manufacture the laminated body 100 by the method of the following inkjet system and a metal jet system.

(Inkjet method)
The ink jet method has recently been technically established as a method for producing a three-dimensional object by warming a metal with an ink jet head and ejecting molten metal from the ink jet head in the form of droplets to deposit one layer at a time. This inkjet method can be applied when the laminated body 100 is produced using a metal material having a relatively low melting point.

(Metal jet method)
If the melting point of the material is low, the molten metal can be ejected simply by heating it with an inkjet head. However, if the melting point of the material exceeds 1000 ° C., the ink jet head does not function. Therefore, when the material metal is made a thin metal wire and the electrodes are brought close to both ends of the wire and discharged, the metal instantly melts. When dissolved, the metal is rounded by surface tension. As soon as it is rounded, argon gas is flowed and sprayed to inject a round ball-shaped molten metal. As a result, the molten metal reaches the contact surface. If the contact surface is cold, heat flows in a direction perpendicular to the contact surface, so that the metal is laminated and the crystal orientation is aligned.

  In any method, an acceleration of 100 G or more is applied to the molten material to form a single layer, scan the surface in the plane direction, form a surface, and laminate the layered structure 100. As a result, the same mechanical strength as that of the thermoelectric semiconductor material obtained by the centrifugal quenching process is ensured.

DESCRIPTION OF SYMBOLS 10 Rotating body, 11 Mold, 20 Rotational speed adjusting means, 30 Heating means, 40 Injection means, 50 Cooling means, 60 Control means, 90 Thermoelectric element, 100 Laminate, 110 Crystal grain

Claims (10)

From the vertical direction of the cooling surface, the molten material is supplied toward the cooling surface, and the molten material is rapidly cooled and solidified while pressing the molten material against the cooling surface by the accelerating force of the molten material. A method for producing a laminate, comprising producing a laminate having a crystal structure in which a C-plane of crystal grains rises along an interlayer interface. The method for manufacturing a laminated body according to claim 1, wherein the cooling surface is an inner peripheral surface of the rotating body, and the acceleration force is a centrifugal force of the rotating body. The method for producing a laminate according to claim 2, wherein the molten material is sprayed toward a mold formed on the inner peripheral surface of the rotating body. A mold formed on the inner peripheral surface of the rotating body;
A rotational speed adjusting means for adjusting the rotational speed of the rotating body;
Heating means for melting the material;
Injection means for injecting a molten material toward the mold;
Cooling means for cooling the mold;
And a control means for controlling the rotation speed adjusting means or / and the heating means or / and the spraying means or / and the cooling means so that the molten material is laminated on the mold. Manufacturing equipment. The method for producing a laminate according to claim 1, wherein the orientation rate of the C-plane of the crystal grains is adjusted by adjusting a cooling rate for each layer of the molten material. The method for manufacturing a laminate according to claim 2 or 3, wherein the thickness of each layer of the laminate is adjusted by adjusting the number of rotations of the rotor. 5. The production of a laminate according to claim 4, wherein the cooling rate for each layer of the molten material is adjusted by controlling the rotation speed adjusting means or / and the heating means or / and the injection means or / and the cooling means. apparatus. The apparatus for manufacturing a laminate according to claim 4, wherein the thickness of each layer of the laminate is adjusted by controlling the rotation speed adjusting means and / or the jetting means. The method for manufacturing a laminate according to any one of claims 1, 2, 3, 5, and 6, wherein the material is a thermoelectric semiconductor material. The material for manufacturing a laminate according to any one of claims 4, 7, and 8, wherein the material is a thermoelectric semiconductor material.