WO2019127174A1 - Hot-press sintering apparatus, block thermoelectric material of micro-nano porous structure, and manufacturing method therefor - Google Patents

Hot-press sintering apparatus, block thermoelectric material of micro-nano porous structure, and manufacturing method therefor Download PDF

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Publication number
WO2019127174A1
WO2019127174A1 PCT/CN2017/119210 CN2017119210W WO2019127174A1 WO 2019127174 A1 WO2019127174 A1 WO 2019127174A1 CN 2017119210 W CN2017119210 W CN 2017119210W WO 2019127174 A1 WO2019127174 A1 WO 2019127174A1
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pressing head
mold
thermoelectric material
sintering
thermoelectric
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PCT/CN2017/119210
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French (fr)
Chinese (zh)
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常斯轶
陈晓曦
李珊
王浩
陈进
赵怀周
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中国科学院物理研究所
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Priority to PCT/CN2017/119210 priority Critical patent/WO2019127174A1/en
Publication of WO2019127174A1 publication Critical patent/WO2019127174A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/11—Making porous workpieces or articles
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects

Definitions

  • the invention belongs to the field of thermoelectric materials.
  • the present invention relates to a method of preparing a hot press sintering apparatus, a bulk thermoelectric material of a micro/nano porous structure, and a bulk thermoelectric material of a micro/nano porous structure.
  • thermoelectric material is a functional material capable of directly converting thermal energy and electric energy into each other, and has the advantages of light weight, small volume, simple structure, no noise, zero discharge, and long service life. This has brought hope to solve the problems of energy crisis and increasingly serious environmental pollution, as well as the development of green energy-saving new energy materials. Thermoelectric materials have therefore received great attention from all countries in the world.
  • thermoelectric materials have achieved low efficiency (thermoelectric merit ZT ⁇ 1) from traditional single scale and simple components to multi-scale and complex components and Defective types of high-performance thermoelectric materials are transformed, and thermoelectric properties (thermoelectric merit ZT) have gradually increased over the past decade, and the ZT peaks of some material systems have approached or reached a level of about 2.5.
  • thermoelectric figure of merit ZT avg or holographic ZT value
  • thermoelectric conversion efficiency In order to improve the thermoelectric conversion efficiency of materials, it is necessary to decouple the electroacoustic transport in the thermoelectric figure of merit to realize the so-called "electronic crystal, phononic glass” material, which is also the difficulty and core of thermoelectric materials research.
  • the electrical control of materials is closely related to the electronic structure near the Fermi surface. Under the slight temperature (or energy) disturbance, the higher the carrier concentration that is excited to participate in transport, the better the thermoelectric transport. In the lattice, the high-frequency and medium- and low-frequency phonons are scattered by multi-scale crystal structure defects such as point defects, dislocations, grain boundary density and superlattice effect to reduce the thermal conductivity of the material.
  • thermoelectric material preparation method generally adopts the following means to generate pores: (1) making pores of materials by means of an auxiliary agent such as an etchant and a pore-assisting agent; (2) placing a thermoelectric material matrix and a nanotube The porous material is composited to produce pores; and (3) the internal components of the material are volatilized by long-time annealing to produce pores.
  • an auxiliary agent such as an etchant and a pore-assisting agent
  • Chinese Patent Application No. 200910092656.X discloses a preparation method of a lanthanide nanoporous thermoelectric material.
  • the method disclosed in Chinese Patent Application No. 200910092656.X requires the use of a pore-enhancing agent to form pores, and the method has complicated operation steps and can only be applied to a lanthanide thermoelectric material system, and cannot be widely applied.
  • thermoelectric material of a micro/nano porous structure a bulk thermoelectric material of a micro/nano porous structure in view of limitations and disadvantages of the prior art.
  • the present invention provides a hot press sintering apparatus, the apparatus comprising an upper electrode, a lower electrode, a water-cooled vacuum chamber, and a mold set, wherein the mold set includes a mold body, an upper pressing head, and a lower pressing head, The mold body has a through hole in a height direction, and a sum of heights of the upper pressing head and the lower pressing head is smaller than a height of the mold body;
  • the mold set is placed in the water-cooled vacuum chamber, and the upper electrode and the lower electrode press the upper pressing head and the lower pressing head into the through hole of the mold body until the upper pressing The head and the lower pressing head are respectively flush with the upper end surface and the lower end surface of the mold main body, and a sample chamber for accommodating the sample is formed in the through hole of the mold main body.
  • the hot press sintering device provided by the present invention can be used to prepare a bulk thermoelectric material of a multi-scale micro-nano porous structure.
  • the inventors of the present application unexpectedly found that the height of the upper indenter and the lower indenter can be made smaller than the height of the mold main body by setting the heights of the upper indenter and the lower indenter, and further in the hot press sintering apparatus.
  • the upper and lower electrodes press the upper and lower rams into the through holes of the mold body and form a sample chamber in the through holes, and the upper and lower electrodes directly or indirectly contact the mold.
  • the upper and lower pressing heads cannot continue to move into the through hole, so that the thickness (ie, volume) of the sample is effectively controlled, thereby obtaining The desired density of the sample.
  • the hot press sintering apparatus is a hot isostatic pressing apparatus, a direct current electric heating apparatus, or a discharge plasma sintering apparatus.
  • the hot press sintering device is a discharge plasma sintering device including an upper electrode, a lower electrode, a water-cooled vacuum chamber, and a mold set, wherein the mold set includes a mold body and an upper portion a pressure head, a lower pressing head, an upper insulating layer and a lower insulating layer, the mold body has a through hole in a height direction, and a sum of heights of the upper pressing head and the lower pressing head is smaller than the upper insulating layer and the The sum of the heights of the mold body and the lower insulating layer;
  • the mold set is placed in the water-cooled vacuum chamber, and the upper insulating layer and the lower insulating layer are respectively placed on an upper end surface and a lower end surface of the mold body, and the upper electrode and the lower electrode are The upper pressing head and the lower pressing head are pressed into the through hole of the mold body until the upper pressing head and the lower pressing head are flush with the upper insulating layer and the lower insulating layer, respectively, A sample chamber containing the sample is formed in the through hole of the mold body.
  • the spark plasma sintering apparatus provided by the present invention is particularly useful for preparing a bulk thermoelectric material of a multi-scale micro/nano porous structure.
  • the inventors of the present application unexpectedly found that the heights of the upper and lower rams can be made smaller than the upper insulating layer, the mold main body, and the lower insulating layer by setting the heights of the upper ram and the lower ram. The sum of the heights, and further, when the discharge plasma sintering device is operated, the upper and lower electrodes press the upper and lower pressing heads into the through holes of the mold body and form the sample chamber in the through holes under heating and pressurization.
  • the upper and lower pressing heads cannot continue to move into the through hole, so that the sample
  • the thickness i.e., volume
  • the current density of the sample does not change, ensuring sufficient sintering of the sample, and a sample with better performance can be obtained.
  • a device according to the present invention, wherein the upper indenter, the lower indenter, and the mold body may be made of metal, alloy or graphite.
  • suitable metals include, but are not limited to, iron, aluminum, and copper.
  • suitable alloys include, but are not limited to, aluminum alloys, stainless steel, and tungsten carbide alloys.
  • the upper indenter and the lower indenter are graphite rods
  • the mold body is a graphite mold body.
  • a device wherein the upper insulating layer and the lower insulating layer are quartz wool.
  • the invention selects quartz cotton as the insulating layer, and can not only insulate the upper and lower electrodes from the upper and lower end faces of the main body of the mold, but also can play the role of heat preservation, and is advantageous for preparing samples with better performance.
  • the apparatus may include two graphite sheets disposed between the upper indenter and the upper insulating layer and between the lower indenter and the lower insulating layer, respectively.
  • the upper electrode and the upper insulating layer and the lower electrode Indirect contact with the lower insulating layer.
  • the device wherein the device may also be provided without a graphite plate.
  • the upper electrode and the lower electrode press the upper indenter and the lower indenter into the through hole of the mold body, the upper electrode and the upper insulating layer and the lower electrode Directly in contact with the lower insulating layer.
  • the device may further comprise a hot press sintering device such as other components used in conventional spark plasma sintering.
  • the other components include, but are not limited to, a power source and a direct current generator or a pulse current generator.
  • the present invention provides a method for preparing a bulk thermoelectric material having a multi-scale micro-nano porous structure, the method comprising: sintering a raw material powder by using a hot-press sintering device provided by the present invention, such as a spark plasma sintering device, Thereby, a bulk thermoelectric material having a multi-scale micro/nano porous structure is obtained.
  • a hot-press sintering device provided by the present invention, such as a spark plasma sintering device
  • the density of the bulk thermoelectric material is controlled by adjusting the amount of raw material powder added and/or changing the height of the upper and/or lower ram.
  • the thermoelectric material has a density of 60% to 100%. In some embodiments, the thermoelectric material has a density of from 70% to 95%, in some embodiments from 70% to 90%, and in some embodiments from 80% to 90%.
  • thermoelectric material is an n-type Mn doped Mg 3 Sb 2 material, a half-Heusler alloy thermoelectric material such as a FeNbSb-based material, and a Bi 2 Te 3 -based material. Or MgSiSn based materials.
  • a suitable n-type Mn doped Mg 3 Sb 2 material has a chemical formula of Mg 3.2-x Mn x Sb 1.5-y Bi 0.5 Te y , wherein 0.0125 ⁇ x ⁇ 0.1, and 0.01 ⁇ y ⁇ 0.05;
  • suitable half-Heusler alloy thermoelectric materials include, but are not limited to, Hf 0.25 Zr 0.75 NiSn 0.99 Sb 0.01 , and in some embodiments, suitable Bi 2 Te 3 based materials Examples include, but are not limited to, Bi 0.5 Sb 1.5 Te 3 .
  • the thermoelectric material is Mg 3.175 Mn 0.025 Sb 1.98 Bi 0.5 Te 0.02 .
  • the raw material powder has a particle diameter ranging from 10 nm to 100 ⁇ m, preferably from 100 nm to 10 ⁇ m.
  • the feedstock powder has a particle size ranging from 200 nanometers to 10 micrometers, in some embodiments from 200 to 600 nanometers, and in some embodiments from 100 to 300 nanometers.
  • the raw material powder may be a mixture of solid elemental powders containing respective elements of a thermoelectric material, or may be a pre-sintered powder of a thermoelectric material.
  • the raw material powder is a mixture of solid elemental powders of corresponding elements of a thermoelectric material, and the solid elemental powder of the corresponding element is formulated in a stoichiometric ratio.
  • the feedstock powder is a pre-sintered powder of a thermoelectric material.
  • the pre-sintered powder can be obtained by forming a block by a method known in the art such as a conventional discharge plasma sintering method and an arc melting method, followed by grinding.
  • a method according to the present invention comprising: assembling a mold set and simultaneously filling a raw material powder into a through hole of the mold main body, placing the assembled mold set into a water-cooled vacuum chamber, using an upper electrode and a lower electrode holder The mold set is tightened and then sintered, for example, by plasma sintering.
  • sintering such as spark plasma sintering
  • the water-cooled vacuum chamber has a vacuum of 5 Pa or less
  • sintering, such as spark plasma sintering is performed at atmospheric pressure. of.
  • the pressure of the sintering such as spark plasma sintering is 5 to 120 MPa, for example, 40 to 60 MPa.
  • the sintering for example, spark plasma sintering, is carried out at a temperature of from 100 to 2000 ° C, for example from 450 to 900 ° C, preferably for a period of from 1 to 120 minutes, for example from 5 to 20 minutes.
  • the temperature rise rate of the sintering such as discharge plasma sintering is 5 to 100 ° C / min, preferably 20 to 60 ° C / min, more preferably 50 to 60 ° C / min.
  • the present invention also provides a multi-scale micro-nano porous structure bulk thermoelectric material having a chemical formula of Mg 3.2-x Mn x Sb 1.5-y Bi 0.5 Te y , wherein 0.0125 ⁇ x ⁇ 0.1, and 0.01 ⁇ y ⁇ 0.05.
  • thermoelectric material has the chemical formula Mg 3.175 Mn 0.025 Sb 1.98 Bi 0.5 Te 0.02 .
  • the thermoelectric material has a density of 60% to 100%. In some embodiments, the thermoelectric material has a density of from 70% to 95%, in some embodiments from 70% to 90%, and in some embodiments from 80% to 90%.
  • thermoelectric material comprising a continuous phase (also referred to as “host phase”) and a dispersed phase (also referred to as “precipitate phase”) dispersed in the continuous phase.
  • thermoelectric material according to the present invention wherein the chemical form of the continuous phase is Mg 3.175 Mn 0.025 Sb 1.98-z Bi z Te 0.02 , wherein 0 ⁇ z ⁇ 0.5 in the continuous phase, and the dispersed phase is ⁇ -Mg 3 Bi 2 .
  • the expression " ⁇ -Mg 3 Bi 2 " means that the dispersed phase composition is Mg 3 Bi 2 , the crystal structure thereof is a cubic crystal system, and the space group is la-206.
  • thermoelectric material has pore structures of various scales on a nanometer scale and a micrometer scale.
  • the apparatus provided by the present invention achieves effective control of the thickness (volume) of the sample by adjusting the heights of the upper and lower indenters and, if necessary, the upper and lower insulating layers, thereby enabling efficient preparation of low-density thermoelectric materials.
  • the apparatus provided by the present invention can be improved by a conventional hot press sintering apparatus such as a spark plasma sintering apparatus, which is low in cost and easy to implement.
  • the device provided by the invention has no special requirements on the material of the mold set, and has wide application prospects.
  • the method provided by the invention is simple in operation, time-saving and efficient, does not require an auxiliary agent to form micro-nano holes, and can accurately control the density of materials, and can efficiently prepare high-efficiency and energy-saving multi-scale micro-nano porous structure thermoelectric materials. .
  • the method of the invention can be used for preparing a plurality of different thermoelectric material systems, and has universality, and the thermoelectric properties of the multi-scale micro-nano porous structure prepared by the method of the invention are greatly improved, and the existing thermoelectricity is broken.
  • the performance bottleneck of materials is of great significance to the development and application of thermoelectric materials and has important economic benefits. It will also promote the development of other related fields.
  • thermoelectric figure ZT of existing thermoelectric material systems can be greatly improved, and the application fields of rich thermoelectric materials can be broadened.
  • the introduction of micro-nano porous structure does not affect the mechanical properties of the material, and can significantly save material costs by about 20%.
  • FIG. 1 is a schematic structural view of a device according to an embodiment of the present invention.
  • FIG. 2 is a schematic structural view of a device according to another embodiment of the present invention.
  • Figure 3 is an SEM image of a sample of Example 1 of the present application.
  • Figure 4 is an SEM image of a sample of Example 1 of the present application.
  • Figure 5 is an SEM image of a sample of Example 2 of the present application.
  • Figure 6 is an SEM image of a sample of Example 2 of the present application.
  • Figure 7 is an SEM image of a sample of Example 3 of the present application.
  • Figure 8 is an SEM image of a sample of Example 3 of the present application.
  • 1-upper electrode 2-water-cooled vacuum chamber, 3-upper insulation layer, 4-upper head, 5-sample chamber, 6-lower head, 7-lower electrode, 8-die body, 9-pulse current Generator, 10-under insulating layer, and 11-graphite plate.
  • thermoelectric figure of merit and the engineering thermoelectric figure of merit are indicators for measuring the thermoelectric properties of materials.
  • the formula for calculating the thermoelectric figure of merit ZT is:
  • S is the Seebeck coefficient
  • ⁇ is the electrical conductivity
  • T is the absolute temperature
  • K is the thermal conductivity.
  • the thermal conductivity is obtained by multiplying the thermal diffusivity, density and specific heat capacity of the sample.
  • the Seebeck coefficient and resistivity are tested by the German LINSEIS LSR-3 instrument, and the thermal diffusivity is tested by the German LINSEIS LFA 1000 Laser Flash device.
  • thermoelectric conversion efficiency ⁇ is calculated as:
  • ⁇ T is the temperature difference between the hot ends of the cold end
  • T cold is the cold end temperature
  • T hot is the hot end temperature
  • ZT avg is the average ZT value
  • thermoelectric figure of merit (ZT) eng can be calculated according to the thermoelectric figure of merit.
  • the formula is:
  • the sample was ground with two thousand mesh sandpaper until the surface was almost flat, and then polished with a 1 ⁇ m polishing paste under a solvent (water or glycerol) in a polishing machine until the surface of the sample was bright and the surface of the sample was under an optical microscope. There are basically no scratches, and then a scanning electron microscope is used for the observation test.
  • a solvent water or glycerol
  • Density is calculated by measuring the ratio of density to theoretical density, which can be calculated from the theoretical density, which is also available on the Springer Materials website at http://materials.springer.com/.
  • the apparatus includes an upper electrode 1, a lower electrode 7, a water-cooled vacuum chamber 2, and a mold set.
  • the mold set includes a mold main body 8, an upper pressing head 4, and a lower pressing head 6, and the mold main body 8 has a through hole in a height direction, and a sum of heights of the upper pressing head 4 and the lower pressing head 6 is smaller than a height of the mold main body 8.
  • a die set is placed in the water-cooled vacuum chamber 2, and the upper electrode 1 and the lower electrode 7 press the upper ram 4 and the lower ram 6 into the through holes of the mold body 8 up to the upper ram 4 and the lower ram 6
  • the upper end surface and the lower end surface of the mold main body 8 are respectively flush, and a sample chamber 5 for accommodating a sample is formed in the through hole of the mold main body 8.
  • the upper ram 4 and the lower ram 6 cannot continue to move into the through hole, so that the sample chamber 5 (thickness (i.e., volume) of the sample) is effectively controlled, thereby obtaining a sample of desired density.
  • the upper ram 4 and the lower ram 6 are graphite rods, and the mold body 8 is a graphite mold body.
  • the raw material powder is filled into the inner cavity of the mold main body 8 and the upper indenter 4 and the lower indenter 6 are mounted, and the assembled mold set is placed in the water-cooling vacuum chamber 2, and the upper electrode 1 and the lower electrode 7 are used. Clamp the mold set, set the pressure and temperature control program and start sintering. After the sintering is finished, the sample will naturally cool with the furnace.
  • the apparatus includes an upper electrode 1, a lower electrode 7, a water-cooled vacuum chamber 2, two graphite plates 11, a mold set, a power source (not shown), and a pulse current generator 9.
  • the mold set includes a mold main body 8, an upper pressing head 4, a lower pressing head 6, an upper insulating layer 3, and a lower insulating layer 10.
  • the mold main body 8 has a through hole in a height direction, and a sum of heights of the upper pressing head 4 and the lower pressing head 6. It is smaller than the sum of the heights of the upper insulating layer 3, the mold main body 8, and the lower insulating layer 10.
  • a mold set is placed in the water-cooled vacuum chamber 2, and an upper insulating layer 3 and a lower insulating layer 4 are respectively placed on the upper end surface and the lower end surface of the mold main body 8, and the upper electrode 1 and the lower electrode 7 are placed on the upper pressing head 4 and
  • the lower ram 6 is pressed into the through hole of the mold main body 8 until the upper ram 4 and the lower ram 6 are flush with the upper insulating layer 3 and the lower insulating layer 10, respectively, and the sample chamber 5 accommodating the sample is formed in the through hole of the mold main body 8. .
  • the upper ram 4 and the lower ram 6 cannot continue to move into the through hole, so that the sample chamber 5 (thickness (i.e., volume) of the sample) is effectively controlled, thereby obtaining a sample of desired density.
  • the upper indenter 4 and the lower indenter 6 are graphite rods, and the mold main body 8 is a graphite mold main body, and the upper insulating layer 3 and the lower insulating layer 10 are quartz wool.
  • the raw material powder is filled into the inner cavity of the mold main body 8 and the upper indenter 4 and the lower indenter 6 are mounted, and the assembled mold set is placed in the water-cooling vacuum chamber 2, and the upper electrode 1 and the lower electrode 7 are used. Clamp the mold set, evacuate to 5Pa or less, set the pressure and temperature control program, turn on the pulse current device 9 and start sintering. After the sintering is finished, the sample is naturally cooled with the furnace.
  • This example is intended to illustrate the Zintl phase thermoelectric material Mg 3.175 Mn 0.025 Sb 1.98 Bi 0.5 Te 0.02 and its preparation.
  • the elemental particles of each element were ball milled for 12 hours according to stoichiometry to form a powder with a particle size of 200 nm to 10 ⁇ m, which was used in the FDS-4000 discharge plasma sintering furnace jointly developed by Shenzhen University and Thinking Special Power Equipment Co., Ltd.
  • the conventional discharge plasma sintering method sinters the powder into a dense block (this process is one-time sintering), and the sintering conditions are as follows: a vacuum of 5 Pa, a pressure of 50 MPa, a heating rate of 50 ° C / min, a sintering temperature of 600 ° C, and a holding time of 5 minute.
  • the sintered bulk material is ball milled for 4 hours to form a raw material powder having a particle diameter of 200 nm to 10 ⁇ m, and this powder is subjected to secondary sintering in the apparatus shown in Fig. 2, thereby obtaining a multi-scale micro-nanoporous.
  • the degree of vacuum is 5 Pa
  • the pressure is 50 MPa
  • the heating rate is 50 ° C / min
  • the sintering temperature is 800 ° C
  • the holding time is 5 minutes.
  • the sample is naturally cooled with the furnace to obtain a multi-scale micro-nano hole ( A sample of the porous structure.
  • Figures 3 and 4 show representative SEM images of different magnifications of the Example 1 samples.
  • the SEM results show that the sample of Example 1 has a multi-scale micro-nano pore (porous) structure.
  • the densification of the sample of Example 1 was 85%.
  • the crystal structure of the sample was calibrated by transmission electron microscopy and compared with the ICDD standard database. It was found that the sample prepared in Example 1 included a continuous phase and a dispersed phase dispersed in the continuous phase, and the continuous phase was Mg 3.175 Mn 0.025 Sb 1.98-z Bi z Te 0.02 , wherein z varies between 0 and 0.5, and the dispersed phase is ⁇ -Mg 3 Bi 2 .
  • thermoelectric figure of merit ZT and the engineering thermoelectric figure of merit (ZT) eng of the sintered bulk material and the secondary sintered bulk thermoelectric material were measured separately.
  • the results show that the thermal conductivity decreases from 1Wm -1 k -1 to 0.69Wm -1 k -1 at room temperature, while the lower the thermal conductivity for thermoelectric materials, the better the thermoelectric performance.
  • the power factor at room temperature is 1149 ⁇ Wm -1 K -2 is increased to 2267 ⁇ Wm -1 K -2 (the power factor is the product of the square of the Seebeck coefficient and the conductivity).
  • thermoelectric figure of merit ZT at room temperature is increased from 0.37 to 1.06, and the peak value of the thermoelectric figure ZT is raised from 1.6 to 2.14, the peak value of engineering thermoelectric figure of merit (ZT) eng increased from 0.82 to 1.29.
  • the thermoelectric figure of merit ZT and the engineering thermoelectric figure of merit (ZT) eng of the secondary sintered block thermoelectric materials are the highest values in the current material system, and are also the highest recorded values of the block thermoelectric materials in the field of thermoelectric materials.
  • This embodiment is for explaining a Half-Heusler alloy thermoelectric material Hf 0.25 Zr 0.75 NiSn 0.99 Sb 0.01 and its preparation.
  • each element element is subjected to arc melting to form an ingot according to stoichiometry, and then ball milling for 12 hours to form a powder having a particle diameter of 200 to 600 nm, and the powder is subjected to discharge plasma sintering in the apparatus shown in FIG.
  • the degree is 5 Pa
  • the pressure is 60 MPa
  • the heating rate is 40 ° C / min
  • the sintering temperature is 900 ° C
  • the holding time is 20 minutes.
  • the sample is naturally cooled with the furnace to obtain a sample having a multi-scale micro-nano pore (porous) structure.
  • Figures 5 and 6 show representative SEM images of different magnifications of the Example 2 samples.
  • the SEM results show that the sample of Example 2 has a multi-scale micro-nano pore (porous) structure.
  • the sample of Example 2 had a density of 93%.
  • a dense material of Hf 0.25 Zr 0.75 NiSn 0.99 Sb 0.0 1 was prepared as a reference sample by using FDS-4000 discharge plasma sintering furnace jointly developed by Shenzhen University and Thinking Power Equipment Co., Ltd. Specifically, first, each element element is subjected to arc melting to form an ingot according to stoichiometry, and then ball-milled for 12 hours to form a powder having a particle diameter of 200 to 600 nm, and then the powder is sintered into a dense block by a conventional discharge plasma sintering method.
  • the sintering conditions were as follows: a vacuum of 5 Pa, a pressure of 60 MPa, a heating rate of 40 ° C / min, a sintering temperature of 900 ° C, and a holding time of 20 minutes.
  • thermoelectric figure of merit ZT and the engineering thermoelectric figure of merit (ZT) eng of the reference sample and the sample of Example 2 were measured, respectively.
  • the results show that the peak value of the thermoelectric figure ZT is increased from 1 to 1.13, and the peak value of the engineering thermoelectric figure of merit (ZT) eng is increased from 0.68 to 0.74.
  • This example is intended to illustrate the Bi 2 Te 3 based material Bi 0.5 Sb 1.5 Te 3 and its preparation.
  • the elemental particles of each element were ball milled for 9 hours according to stoichiometry to form a powder having a particle diameter of 100 to 300 nm, and the powder was subjected to spark plasma sintering in a device shown in Fig. 2, and the degree of vacuum was 5 Pa, and the pressure was 50 MPa.
  • the heating rate was 70 ° C / min
  • the sintering temperature was 450 ° C
  • the holding time was 5 minutes.
  • the sample was naturally cooled with the furnace to obtain a sample having a multi-scale micro-nano pore (porous) structure.
  • Figures 7 and 8 show representative SEM images of different magnifications of the Example 3 samples.
  • the SEM results show that the sample of Example 3 has a multi-scale micro-nano pore (porous) structure.
  • the densification of the sample of Example 3 was 81%.
  • a dense material of Bi 0.5 Sb 1.5 Te 3 was prepared as a reference sample by using an FDS-4000 discharge plasma sintering furnace jointly developed by Shenzhen University and Thinking Power Equipment Co., Ltd. Specifically, first, the elemental particles of each element are ball milled for 9 hours according to stoichiometry to form a powder having a particle diameter of 100 to 300 nm, and then the powder is sintered into a dense block by a conventional discharge plasma sintering method, and the sintering conditions are as follows: the degree of vacuum is 5 Pa, pressure 50 MPa, heating rate 70 ° C / min, sintering temperature 450 ° C, holding time 5 minutes.
  • thermoelectric figure of merit and the engineering thermoelectric figure of merit (ZT) eng of the reference sample and the sample of Example 3 were measured.
  • the results show that the peak value of the thermoelectric figure ZT is increased from 1.22 to 1.34, and the peak value of the engineering thermoelectric figure of merit (ZT) eng is raised from 0.43 to 0.5.

Abstract

A hot-press sintering apparatus, a method for manufacturing a thermoelectric material by using the hot-press sintering apparatus, and a thermoelectric material having a multi-scale micro-nano porous structure. The hot-press sintering apparatus comprises an upper electrode (1), a lower electrode (7), a water-cooling vacuum chamber (2), and a mold set. The mold group comprises a mold body (8), an upper pressing head (4), and a lower pressing head (6). The mold body is provided with a through hole in a height direction; the sum of the heights of the upper pressing head and the lower pressing head is smaller than the height of the mold body; during operation, the mold set is provided in the water-cooling vacuum chamber, the upper electrode and the lower electrode press the upper pressing head and the lower pressing head into the through hole of the mold body until the upper pressing head and the lower pressing head are leveled with an upper end face and a lower end face of the mold body, and a sample chamber for holding a sample is provided inside the through hole of the mold body. The chemical formula of the thermoelectric material having the multi-scale micro-nano porous structure is Mg3.2-xMnxSb1.5-yBi0.5Tey, wherein 0.0125 ≤ x ≤ 0.1, and 0.01 ≤ y ≤ 0.05.

Description

热压烧结装置、微纳多孔结构的块体热电材料及其制法Hot-pressing sintering device, micro-nano porous structure block thermoelectric material and preparation method thereof 技术领域Technical field
本发明属于热电材料领域。具体地，本发明涉及一种热压烧结装置、微纳多孔结构的块体热电材料和微纳多孔结构的块体热电材料的制备方法。The invention belongs to the field of thermoelectric materials. In particular, the present invention relates to a method of preparing a hot press sintering apparatus, a bulk thermoelectric material of a micro/nano porous structure, and a bulk thermoelectric material of a micro/nano porous structure.
背景技术Background technique
热电材料是一种能够实现热能和电能直接相互转化的功能材料，具有质量轻、体积小、结构简单、无噪声、零排放以及使用寿命长等优点。这对解决能源危机和环境污染日益严峻等问题以及研发绿色环保的新能源材料带来了希望，热电材料也因此受到了世界各国的高度重视。The thermoelectric material is a functional material capable of directly converting thermal energy and electric energy into each other, and has the advantages of light weight, small volume, simple structure, no noise, zero discharge, and long service life. This has brought hope to solve the problems of energy crisis and increasingly serious environmental pollution, as well as the development of green energy-saving new energy materials. Thermoelectric materials have therefore received great attention from all countries in the world.
随着新材料的设计理念以及新工艺、技术的发展，热电材料已实现了从传统的具有单一尺度和简单组分的低效能(热电优值ZT≤1)向多尺度并具有复杂组分和缺陷类型的高性能热电材料转变，并且热电性能(热电优值ZT)近十几年来逐步攀升，某些材料体系的ZT峰值已接近或达到约2.5的水平。但是，由于绝大多数材料体系在所服役温区范围内的平均热电优值ZT avg(或者全息ZT值)仍然较低，尤其是材料在室温的ZT值普遍小于1，这直接导致热电器件转换效率低的问题，严重制约了热电能源转换技术的推广和应用。 With the design concept of new materials and the development of new processes and technologies, thermoelectric materials have achieved low efficiency (thermoelectric merit ZT ≤ 1) from traditional single scale and simple components to multi-scale and complex components and Defective types of high-performance thermoelectric materials are transformed, and thermoelectric properties (thermoelectric merit ZT) have gradually increased over the past decade, and the ZT peaks of some material systems have approached or reached a level of about 2.5. However, since the average thermoelectric figure of merit ZT avg (or holographic ZT value) of most material systems in the service temperature range is still low, especially the ZT value of the material at room temperature is generally less than 1, which directly leads to thermoelectric device conversion. The problem of low efficiency has seriously restricted the promotion and application of thermoelectric energy conversion technology.
想要提高材料的热电转换效率，就需要对热电优值中电声输运进行解耦，实现所谓的“电子晶体、声子玻璃”材料，这也是热电材料研究的难点与核心。材料电学方面的调控与费米面附近的电子结构密切相关，在微小的温度(或能量)扰动下，被激发参与输运的载流子浓度越高，越有利于热电输运。在晶格方面，通过多尺度晶体结构缺陷如点缺陷、位错、晶界密度以及超晶格效应，对高频和中、低频率声子进行散射，降低材料热导率。原因在于，载流子输运的平均自由程(λe)小于声子振动的平均自由程(λp)，多尺度晶体结构缺陷利用二者差异，实现电声输运的解耦，从而有效提高材料整体热电优值。In order to improve the thermoelectric conversion efficiency of materials, it is necessary to decouple the electroacoustic transport in the thermoelectric figure of merit to realize the so-called "electronic crystal, phononic glass" material, which is also the difficulty and core of thermoelectric materials research. The electrical control of materials is closely related to the electronic structure near the Fermi surface. Under the slight temperature (or energy) disturbance, the higher the carrier concentration that is excited to participate in transport, the better the thermoelectric transport. In the lattice, the high-frequency and medium- and low-frequency phonons are scattered by multi-scale crystal structure defects such as point defects, dislocations, grain boundary density and superlattice effect to reduce the thermal conductivity of the material. The reason is that the mean free path (λe) of carrier transport is smaller than the mean free path (λp) of phonon vibration, and the multi-scale crystal structure defects utilize the difference between the two to realize the decoupling of electroacoustic transport, thereby effectively improving the material. Overall thermoelectric figure of merit.
从热电输运理论分析，制备具有微纳尺度的多孔结构的热电材 料是提高热电材料性能的有效途径。现有的多尺度微纳多孔结构热电材料的制备方法通常采用以下手段来产生孔隙：(1)借助侵蚀剂、助孔剂等辅助物使材料产生孔隙；(2)将热电材料基体与纳米管等多孔材料复合产生孔隙；和(3)通过长时间退火使材料内部组分挥发产生孔隙。然而，这样的方法大多数存在普适性差和比较费时费力等缺陷。From the theoretical analysis of thermoelectric transport, the preparation of thermoelectric materials with micro-nano-scale porous structures is an effective way to improve the performance of thermoelectric materials. The existing multi-scale micro-nano porous structure thermoelectric material preparation method generally adopts the following means to generate pores: (1) making pores of materials by means of an auxiliary agent such as an etchant and a pore-assisting agent; (2) placing a thermoelectric material matrix and a nanotube The porous material is composited to produce pores; and (3) the internal components of the material are volatilized by long-time annealing to produce pores. However, most of such methods have disadvantages such as poor universality and time consuming and laborious.
例如，中国专利申请200910092656.X公开了一种铋碲系纳米多孔热电材料的制备方法。然而，中国专利申请200910092656.X所公开的方法需要使用助孔剂以形成孔洞，并且该方法操作步骤复杂，只能应用于铋碲系热电材料体系，不能广泛投入应用。For example, Chinese Patent Application No. 200910092656.X discloses a preparation method of a lanthanide nanoporous thermoelectric material. However, the method disclosed in Chinese Patent Application No. 200910092656.X requires the use of a pore-enhancing agent to form pores, and the method has complicated operation steps and can only be applied to a lanthanide thermoelectric material system, and cannot be widely applied.
发明内容Summary of the invention
因此，本发明的目的是针对现有技术所存在的局限性和缺陷缺点，提供一种热压烧结装置、微纳多孔结构的块体热电材料以及一种微纳多孔结构的块体热电材料的制备方法，其中，所述块体热电材料具有多尺度微纳多孔结构。Accordingly, it is an object of the present invention to provide a hot press sintering apparatus, a bulk thermoelectric material of a micro/nano porous structure, and a bulk thermoelectric material of a micro/nano porous structure in view of limitations and disadvantages of the prior art. The preparation method, wherein the bulk thermoelectric material has a multi-scale micro/nano porous structure.
本发明的目的是通过以下技术方案实现的。The object of the present invention is achieved by the following technical solutions.
一方面，本发明提供了一种热压烧结装置，所述装置包括上电极、下电极、水冷真空室和模具组，其中，所述模具组包括模具主体、上压头和下压头，所述模具主体具有高度方向的通孔，以及所述上压头和所述下压头的高度之和小于所述模具主体的高度；In one aspect, the present invention provides a hot press sintering apparatus, the apparatus comprising an upper electrode, a lower electrode, a water-cooled vacuum chamber, and a mold set, wherein the mold set includes a mold body, an upper pressing head, and a lower pressing head, The mold body has a through hole in a height direction, and a sum of heights of the upper pressing head and the lower pressing head is smaller than a height of the mold body;
工作时，所述模具组置于所述水冷真空室内，所述上电极和所述下电极将所述上压头和所述下压头压入所述模具主体的通孔直至所述上压头和所述下压头分别与所述模具主体的上端面和下端面平齐，所述模具主体的通孔内形成容纳样品的样品室。In operation, the mold set is placed in the water-cooled vacuum chamber, and the upper electrode and the lower electrode press the upper pressing head and the lower pressing head into the through hole of the mold body until the upper pressing The head and the lower pressing head are respectively flush with the upper end surface and the lower end surface of the mold main body, and a sample chamber for accommodating the sample is formed in the through hole of the mold main body.
本发明提供的热压烧结装置可以用于制备多尺度微纳多孔结构的块体热电材料。特别地，本申请发明人出人预料地发现，可以通过设置上压头和下压头的高度，使上压头和下压头的高度之和小于模具主体的高度，进而在热压烧结装置工作时，在加热加压下，上电极和下电极将上压头和下压头压入模具主体的通孔中并在通孔中形成样品室，当上电极和下电极直接或间接接触模具主体(即上压头和下压头分别与模具主体的上端面和下端面平齐)时，上下 压头无法继续向通孔内移动，使得样品的厚度(即体积)得到有效控制，进而得到所期望致密度的样品。The hot press sintering device provided by the present invention can be used to prepare a bulk thermoelectric material of a multi-scale micro-nano porous structure. In particular, the inventors of the present application unexpectedly found that the height of the upper indenter and the lower indenter can be made smaller than the height of the mold main body by setting the heights of the upper indenter and the lower indenter, and further in the hot press sintering apparatus. In operation, under heating and pressurization, the upper and lower electrodes press the upper and lower rams into the through holes of the mold body and form a sample chamber in the through holes, and the upper and lower electrodes directly or indirectly contact the mold. When the main body (ie, the upper pressing head and the lower pressing head are flush with the upper end surface and the lower end surface of the mold main body, respectively), the upper and lower pressing heads cannot continue to move into the through hole, so that the thickness (ie, volume) of the sample is effectively controlled, thereby obtaining The desired density of the sample.
根据本发明提供的热压烧结装置，其中，所述热压烧结装置为热等静压装置、直流电热压装置或放电等离子烧结装置。According to the hot press sintering apparatus provided by the present invention, the hot press sintering apparatus is a hot isostatic pressing apparatus, a direct current electric heating apparatus, or a discharge plasma sintering apparatus.
在优选的实施方案中，所述热压烧结装置为放电等离子烧结装置，所述放电等离子烧结装置包括上电极、下电极、水冷真空室和模具组，其中，所述模具组包括模具主体、上压头、下压头、上绝缘层和下绝缘层，所述模具主体具有高度方向的通孔，以及所述上压头和所述下压头的高度之和小于所述上绝缘层、所述模具主体和所述下绝缘层的高度之和；In a preferred embodiment, the hot press sintering device is a discharge plasma sintering device including an upper electrode, a lower electrode, a water-cooled vacuum chamber, and a mold set, wherein the mold set includes a mold body and an upper portion a pressure head, a lower pressing head, an upper insulating layer and a lower insulating layer, the mold body has a through hole in a height direction, and a sum of heights of the upper pressing head and the lower pressing head is smaller than the upper insulating layer and the The sum of the heights of the mold body and the lower insulating layer;
工作时，所述模具组置于所述水冷真空室内，所述上绝缘层和所述下绝缘层分别置于所述模具主体的上端面和下端面，所述上电极和所述下电极将所述上压头和所述下压头压入所述模具主体的通孔直至所述上压头和所述下压头分别与所述上绝缘层和所述下绝缘层平齐，所述模具主体的通孔内形成容纳样品的样品室。In operation, the mold set is placed in the water-cooled vacuum chamber, and the upper insulating layer and the lower insulating layer are respectively placed on an upper end surface and a lower end surface of the mold body, and the upper electrode and the lower electrode are The upper pressing head and the lower pressing head are pressed into the through hole of the mold body until the upper pressing head and the lower pressing head are flush with the upper insulating layer and the lower insulating layer, respectively, A sample chamber containing the sample is formed in the through hole of the mold body.
本发明提供的放电等离子烧结装置特别用于制备多尺度微纳多孔结构的块体热电材料。特别地，本申请发明人出人预料地发现，可以通过设置上压头和下压头的高度，使上压头和下压头的高度之和小于上绝缘层、模具主体和下绝缘层的高度之和，进而在放电等离子烧结装置工作时，在加热加压下，上电极和下电极将上压头和下压头压入模具主体的通孔中并在通孔中形成样品室，当上电极和下电极直接或间接接触上、下绝缘层(即上压头和下压头分别与上绝缘层和下绝缘层平齐)时，上下压头无法继续向通孔内移动，使得样品的厚度(即体积)得到有效控制，进而得到所期望致密度的样品。同时，由于上、下绝缘层的存在，经过样品的电流密度不会发生变化，保证了样品的充分烧结，能够得到性能较好的样品。The spark plasma sintering apparatus provided by the present invention is particularly useful for preparing a bulk thermoelectric material of a multi-scale micro/nano porous structure. In particular, the inventors of the present application unexpectedly found that the heights of the upper and lower rams can be made smaller than the upper insulating layer, the mold main body, and the lower insulating layer by setting the heights of the upper ram and the lower ram. The sum of the heights, and further, when the discharge plasma sintering device is operated, the upper and lower electrodes press the upper and lower pressing heads into the through holes of the mold body and form the sample chamber in the through holes under heating and pressurization. When the upper electrode and the lower electrode directly or indirectly contact the upper and lower insulating layers (ie, the upper pressing head and the lower pressing head are flush with the upper insulating layer and the lower insulating layer, respectively), the upper and lower pressing heads cannot continue to move into the through hole, so that the sample The thickness (i.e., volume) is effectively controlled to provide a sample of the desired density. At the same time, due to the presence of the upper and lower insulating layers, the current density of the sample does not change, ensuring sufficient sintering of the sample, and a sample with better performance can be obtained.
根据本发明提供的装置，其中，所述上压头、所述下压头和所述模具主体可以由金属、合金或石墨制成。合适的金属的实例包括但不限于：铁、铝和铜。合适的合金的实例包括但不限于铝合金、不锈钢和碳化钨合金。A device according to the present invention, wherein the upper indenter, the lower indenter, and the mold body may be made of metal, alloy or graphite. Examples of suitable metals include, but are not limited to, iron, aluminum, and copper. Examples of suitable alloys include, but are not limited to, aluminum alloys, stainless steel, and tungsten carbide alloys.
在一些优选的实施方案中，所述上压头和所述下压头为石墨棒，所述模具主体为石墨模具主体。In some preferred embodiments, the upper indenter and the lower indenter are graphite rods, and the mold body is a graphite mold body.
根据本发明提供的装置，其中，所述上绝缘层和所述下绝缘层为石英棉。本发明选用石英棉作为绝缘层，既可以将上下电极与模具主体的上下端面很好地绝缘，又可以起到保温的作用，有利于制备性能较好的样品。A device according to the present invention, wherein the upper insulating layer and the lower insulating layer are quartz wool. The invention selects quartz cotton as the insulating layer, and can not only insulate the upper and lower electrodes from the upper and lower end faces of the main body of the mold, but also can play the role of heat preservation, and is advantageous for preparing samples with better performance.
根据本发明提供的装置，其中，所述装置可以包括2个石墨板，所述石墨板分别设置在上压头与上绝缘层之间和下压头与下绝缘层之间。这种情况下，所述上电极和所述下电极将所述上压头和所述下压头压入所述模具主体的通孔后，所述上电极与上绝缘层以及所述下电极与所述下绝缘层间接抵触。The apparatus according to the present invention, wherein the apparatus may include two graphite sheets disposed between the upper indenter and the upper insulating layer and between the lower indenter and the lower insulating layer, respectively. In this case, after the upper electrode and the lower electrode press the upper indenter and the lower indenter into the through hole of the mold body, the upper electrode and the upper insulating layer and the lower electrode Indirect contact with the lower insulating layer.
根据本发明提供的装置，其中，所述装置也可以不设置石墨板。这种情况下，所述上电极和所述下电极将所述上压头和所述下压头压入所述模具主体的通孔后，所述上电极与上绝缘层以及所述下电极与所述下绝缘层直接抵触。The device according to the invention, wherein the device may also be provided without a graphite plate. In this case, after the upper electrode and the lower electrode press the upper indenter and the lower indenter into the through hole of the mold body, the upper electrode and the upper insulating layer and the lower electrode Directly in contact with the lower insulating layer.
根据本发明提供的装置，其中，所述装置还可以包括热压烧结装置例如常规放电等离子烧结中所使用的其他部件。在一些实施方案中，所述其他部件包括但不限于：电源和直流电流发生器或脉冲电流发生器。A device according to the present invention, wherein the device may further comprise a hot press sintering device such as other components used in conventional spark plasma sintering. In some embodiments, the other components include, but are not limited to, a power source and a direct current generator or a pulse current generator.
另一方面，本发明提供了一种多尺度微纳多孔结构的块体热电材料的制备方法，所述方法包括：采用本发明提供的热压烧结装置例如放电等离子烧结装置对原料粉末进行烧结，从而得到多尺度微纳多孔结构的块体热电材料。In another aspect, the present invention provides a method for preparing a bulk thermoelectric material having a multi-scale micro-nano porous structure, the method comprising: sintering a raw material powder by using a hot-press sintering device provided by the present invention, such as a spark plasma sintering device, Thereby, a bulk thermoelectric material having a multi-scale micro/nano porous structure is obtained.
根据本发明提供的方法，其中，通过调节所加入的原料粉末的量和/或改变上压头和/或下压头的高度来控制块体热电材料的致密度。According to the method provided by the present invention, the density of the bulk thermoelectric material is controlled by adjusting the amount of raw material powder added and/or changing the height of the upper and/or lower ram.
根据本发明提供的方法，其中，所述热电材料的致密度为60％～100％。在一些实施方案中，所述热电材料的致密度为70％～95％，在一些实施方案中为70％～90％，以及在一些实施方案中为80％～90％。According to the method provided by the present invention, the thermoelectric material has a density of 60% to 100%. In some embodiments, the thermoelectric material has a density of from 70% to 95%, in some embodiments from 70% to 90%, and in some embodiments from 80% to 90%.
根据本发明提供的制备方法，其中，所述热电材料为n型Mn掺杂Mg 3Sb 2材料、诸如FeNbSb基材料的半赫斯勒(Half-Heusler)合金热电材料、Bi 2Te 3基材料或MgSiSn基材料。在一些实施方案中，合适的n型Mn掺杂Mg 3Sb 2材料的化学式为 Mg 3.2-xMn xSb 1.5-yBi 0.5Te y，其中0.0125≤x≤0.1，以及0.01≤y≤0.05；在一些实施方案中，合适的半赫斯勒(Half-Heusler)合金热电材料的实例包括但不限于Hf 0.25Zr 0.75NiSn 0.99Sb 0.01，以及在一些实施方案中，合适的Bi 2Te 3基材料的实例包括但不限于Bi 0.5Sb 1.5Te 3。在一些优选的实施方案中，所述热电材料为Mg 3.175Mn 0.025Sb 1.98Bi 0.5Te 0.02。 The preparation method according to the present invention, wherein the thermoelectric material is an n-type Mn doped Mg 3 Sb 2 material, a half-Heusler alloy thermoelectric material such as a FeNbSb-based material, and a Bi 2 Te 3 -based material. Or MgSiSn based materials. In some embodiments, a suitable n-type Mn doped Mg 3 Sb 2 material has a chemical formula of Mg 3.2-x Mn x Sb 1.5-y Bi 0.5 Te y , wherein 0.0125≤x≤0.1, and 0.01≤y≤0.05; In some embodiments, examples of suitable half-Heusler alloy thermoelectric materials include, but are not limited to, Hf 0.25 Zr 0.75 NiSn 0.99 Sb 0.01 , and in some embodiments, suitable Bi 2 Te 3 based materials Examples include, but are not limited to, Bi 0.5 Sb 1.5 Te 3 . In some preferred embodiments, the thermoelectric material is Mg 3.175 Mn 0.025 Sb 1.98 Bi 0.5 Te 0.02 .
根据本发明提供的方法，其中，所述原料粉末的粒径范围为10纳米～100微米，优选为100纳米～10微米。在一些实施方案中，所述原料粉末的粒径范围为200纳米～10微米，在一些实施方案中为200～600纳米，以及在一些实施方案中为100～300纳米。According to the method of the present invention, the raw material powder has a particle diameter ranging from 10 nm to 100 μm, preferably from 100 nm to 10 μm. In some embodiments, the feedstock powder has a particle size ranging from 200 nanometers to 10 micrometers, in some embodiments from 200 to 600 nanometers, and in some embodiments from 100 to 300 nanometers.
根据本发明提供的方法，其中，所述原料粉末可以是包含热电材料的相应元素的固体单质粉末的混合物，也可以是热电材料的预烧结粉末。According to the method of the present invention, the raw material powder may be a mixture of solid elemental powders containing respective elements of a thermoelectric material, or may be a pre-sintered powder of a thermoelectric material.
在一些实施方案中，所述原料粉末是热电材料的相应元素的固体单质粉末的混合物，相应元素的固体单质粉末按化学计量比配制。In some embodiments, the raw material powder is a mixture of solid elemental powders of corresponding elements of a thermoelectric material, and the solid elemental powder of the corresponding element is formulated in a stoichiometric ratio.
在一些实施方案中，所述原料粉末是热电材料的预烧结粉末。所述预烧结粉末可以通过本领域中已知的方法例如常规放电等离子烧结方法和电弧熔炼法制成块体以及随后研磨得到。In some embodiments, the feedstock powder is a pre-sintered powder of a thermoelectric material. The pre-sintered powder can be obtained by forming a block by a method known in the art such as a conventional discharge plasma sintering method and an arc melting method, followed by grinding.
根据本发明提供的方法，其中，所述方法包括：装配模具组以及同时向模具主体的通孔中装填原料粉末，将装配好的模具组放入水冷真空室中，用上电极和下电极夹紧模具组，然后进行烧结例如放电等离子烧结。A method according to the present invention, wherein the method comprises: assembling a mold set and simultaneously filling a raw material powder into a through hole of the mold main body, placing the assembled mold set into a water-cooled vacuum chamber, using an upper electrode and a lower electrode holder The mold set is tightened and then sintered, for example, by plasma sintering.
在一些实施方案中，烧结例如放电等离子烧结是在真空下进行的，例如所述水冷真空室的真空度为小于等于5Pa，以及在一些实施方案中，烧结例如放电等离子烧结是在常压下进行的。In some embodiments, sintering, such as spark plasma sintering, is performed under vacuum, for example, the water-cooled vacuum chamber has a vacuum of 5 Pa or less, and in some embodiments, sintering, such as spark plasma sintering, is performed at atmospheric pressure. of.
根据本发明提供的方法，其中，所述烧结例如放电等离子烧结的压力为5～120MPa，例如40～60MPa。According to the method provided by the present invention, the pressure of the sintering such as spark plasma sintering is 5 to 120 MPa, for example, 40 to 60 MPa.
根据本发明提供的方法，其中，所述烧结例如放电等离子烧结的温度为100～2000℃，例如450～900℃，优选地，时间为1～120分钟，例如5～20分钟。According to the method of the present invention, the sintering, for example, spark plasma sintering, is carried out at a temperature of from 100 to 2000 ° C, for example from 450 to 900 ° C, preferably for a period of from 1 to 120 minutes, for example from 5 to 20 minutes.
根据本发明提供的方法，其中，所述烧结例如放电等离子烧结 的升温速率为5～100℃/分钟，优选为20～60℃/分钟，更优选为50～60℃/分钟。According to the method of the present invention, the temperature rise rate of the sintering such as discharge plasma sintering is 5 to 100 ° C / min, preferably 20 to 60 ° C / min, more preferably 50 to 60 ° C / min.
又一方面，本发明还提供了一种多尺度微纳多孔结构的块体热电材料，其化学式为Mg 3.2-xMn xSb 1.5-yBi 0.5Te y，其中0.0125≤x≤0.1，以及0.01≤y≤0.05。 In still another aspect, the present invention also provides a multi-scale micro-nano porous structure bulk thermoelectric material having a chemical formula of Mg 3.2-x Mn x Sb 1.5-y Bi 0.5 Te y , wherein 0.0125≤x≤0.1, and 0.01 ≤ y ≤ 0.05.
在一些具体实施方案中，所述热电材料的化学式为Mg 3.175Mn 0.025Sb 1.98Bi 0.5Te 0.02。 In some embodiments, the thermoelectric material has the chemical formula Mg 3.175 Mn 0.025 Sb 1.98 Bi 0.5 Te 0.02 .
根据本发明提供的热电材料，其中，所述热电材料的致密度为60％～100％。在一些实施方案中，所述热电材料的致密度为70％～95％，在一些实施方案中为70％～90％，以及在一些实施方案中为80％～90％。According to the thermoelectric material provided by the present invention, the thermoelectric material has a density of 60% to 100%. In some embodiments, the thermoelectric material has a density of from 70% to 95%, in some embodiments from 70% to 90%, and in some embodiments from 80% to 90%.
根据本发明提供的热电材料，其中，所述热电材料包括连续相(也称为“主体物相”)以及分散在连续相中的分散相(也称为“析出物相”)。A thermoelectric material according to the present invention, wherein the thermoelectric material comprises a continuous phase (also referred to as "host phase") and a dispersed phase (also referred to as "precipitate phase") dispersed in the continuous phase.
根据本发明提供的热电材料，其中，所述连续相的化学式为Mg 3.175Mn 0.025Sb 1.98-zBi zTe 0.02，其中，所述连续相中0≤z≤0.5，以及所述分散相为β-Mg 3Bi 2。本发明中，表述“β-Mg 3Bi 2”是指分散相组成为Mg 3Bi 2，其晶体结构为立方晶系，空间群为la-206。 A thermoelectric material according to the present invention, wherein the chemical form of the continuous phase is Mg 3.175 Mn 0.025 Sb 1.98-z Bi z Te 0.02 , wherein 0 ≤ z ≤ 0.5 in the continuous phase, and the dispersed phase is β -Mg 3 Bi 2 . In the present invention, the expression "β-Mg 3 Bi 2 " means that the dispersed phase composition is Mg 3 Bi 2 , the crystal structure thereof is a cubic crystal system, and the space group is la-206.
本发明中术语“多尺度微纳多孔结构”主要是指热电材料具有纳米尺度和微米尺度的多种尺度的孔结构。The term "multi-scale micro-nano porous structure" in the present invention mainly means that the thermoelectric material has pore structures of various scales on a nanometer scale and a micrometer scale.
本发明具有以下优势：The invention has the following advantages:
1.本发明提供的装置通过调节上压头和下压头的高度以及必要时添加上、下绝缘层，实现了样品厚度(体积)的有效控制，从而能够高效地制备低密度热电材料。本发明提供的装置可以通过在传统的热压烧结装置例如放电等离子烧结装置的基础上进行改进制备，成本低，易于实现。另外，本发明提供的装置对模具组的材质没有特殊要求，具有广泛的应用前景。1. The apparatus provided by the present invention achieves effective control of the thickness (volume) of the sample by adjusting the heights of the upper and lower indenters and, if necessary, the upper and lower insulating layers, thereby enabling efficient preparation of low-density thermoelectric materials. The apparatus provided by the present invention can be improved by a conventional hot press sintering apparatus such as a spark plasma sintering apparatus, which is low in cost and easy to implement. In addition, the device provided by the invention has no special requirements on the material of the mold set, and has wide application prospects.
2.本发明提供的方法操作简单，省时高效，不需要辅助剂来形成微纳孔洞，而且可以精确控制材料的致密度，能够高效地批量制备高效能节约型多尺度微纳多孔结构热电材料。此外，本发明方法能够用于制备多种不同的热电材料体系，具有普适性，经本发明方法制备的多尺度微纳多孔结构的热电材料的热电性能有较大提升， 突破了现有热电材料的性能瓶颈，对热电材料的发展及应用具有重要意义并具有重要的经济效益，也将有力促进其他相关领域的发展。2. The method provided by the invention is simple in operation, time-saving and efficient, does not require an auxiliary agent to form micro-nano holes, and can accurately control the density of materials, and can efficiently prepare high-efficiency and energy-saving multi-scale micro-nano porous structure thermoelectric materials. . In addition, the method of the invention can be used for preparing a plurality of different thermoelectric material systems, and has universality, and the thermoelectric properties of the multi-scale micro-nano porous structure prepared by the method of the invention are greatly improved, and the existing thermoelectricity is broken. The performance bottleneck of materials is of great significance to the development and application of thermoelectric materials and has important economic benefits. It will also promote the development of other related fields.
3.制备多尺度微纳多孔结构的块体热电材料具有重要的科学意义和应用前景，是实现当前热电研究跨越式发展的最有可能途径。通过引入微纳多孔结构和对应的电、声作用新机制，可以大幅度提升现有热电材料体系的热电优值ZT，拓宽丰富热电材料的应用领域。引入微纳多孔结构并不影响材料力学性能，可显著节省材料成本20％左右。3. The preparation of multi-scale micro-nano porous structure block thermoelectric materials has important scientific significance and application prospects, and is the most likely way to realize the leap-forward development of current thermoelectric research. By introducing micro-nano porous structure and corresponding new mechanisms of electrical and acoustic effects, the thermoelectric figure ZT of existing thermoelectric material systems can be greatly improved, and the application fields of rich thermoelectric materials can be broadened. The introduction of micro-nano porous structure does not affect the mechanical properties of the material, and can significantly save material costs by about 20%.
附图的简要说明BRIEF DESCRIPTION OF THE DRAWINGS
以下，结合附图来详细说明本发明的实施方案，其中：Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, in which:
图1是根据本发明的一种实施方案的装置的结构示意图；1 is a schematic structural view of a device according to an embodiment of the present invention;
图2是根据本发明的另一种实施方案的装置的结构示意图；2 is a schematic structural view of a device according to another embodiment of the present invention;
图3是本申请实施例1样品的SEM图；Figure 3 is an SEM image of a sample of Example 1 of the present application;
图4是本申请实施例1样品的SEM图；Figure 4 is an SEM image of a sample of Example 1 of the present application;
图5是本申请实施例2样品的SEM图；Figure 5 is an SEM image of a sample of Example 2 of the present application;
图6是本申请实施例2样品的SEM图；Figure 6 is an SEM image of a sample of Example 2 of the present application;
图7是本申请实施例3样品的SEM图；Figure 7 is an SEM image of a sample of Example 3 of the present application;
图8是本申请实施例3样品的SEM图；Figure 8 is an SEM image of a sample of Example 3 of the present application;
其中，1-上电极，2-水冷真空室，3-上绝缘层，4-上压头，5-样品室，6-下压头，7-下电极，8-模具主体，9-脉冲电流发生器，10-下绝缘层，以及11-石墨板。Among them, 1-upper electrode, 2-water-cooled vacuum chamber, 3-upper insulation layer, 4-upper head, 5-sample chamber, 6-lower head, 7-lower electrode, 8-die body, 9-pulse current Generator, 10-under insulating layer, and 11-graphite plate.
实施发明的最佳方式The best way to implement the invention
下面结合具体实施方式对本发明进行进一步的详细描述，给出的实施例仅为了阐明本发明，而不是为了限制本发明的范围。The present invention is further described in detail with reference to the preferred embodiments thereof.
热电优值ZT和热电转换效率η计算方法Thermoelectric figure of merit ZT and calculation method of thermoelectric conversion efficiency η
热电优值和工程热电优值是衡量材料热电性能的指标，其中热电优值ZT计算公式为：The thermoelectric figure of merit and the engineering thermoelectric figure of merit are indicators for measuring the thermoelectric properties of materials. The formula for calculating the thermoelectric figure of merit ZT is:
ZT＝S 2σT/K ZT=S 2 σT/K
其中，S为塞贝克系数，σ为电导率，T为绝对温度，K为热导率。热导率又由样品的热扩散系数、密度以及比热容相乘得到，其中塞贝克系数及电阻率采用德国LINSEIS LSR-3仪器进行测试，热扩散系数采用德国LINSEIS LFA 1000 Laser Flash设备进行测试。Where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and K is the thermal conductivity. The thermal conductivity is obtained by multiplying the thermal diffusivity, density and specific heat capacity of the sample. The Seebeck coefficient and resistivity are tested by the German LINSEIS LSR-3 instrument, and the thermal diffusivity is tested by the German LINSEIS LFA 1000 Laser Flash device.
热电转换效率η计算公式为：The thermoelectric conversion efficiency η is calculated as:
Figure PCTCN2017119210-appb-000001
Figure PCTCN2017119210-appb-000001
其中ΔT为冷端热端之间温度差，T cold为冷端温度，T hot为热端温度，ZT avg为平均ZT值。 Where ΔT is the temperature difference between the hot ends of the cold end, T cold is the cold end temperature, T hot is the hot end temperature, and ZT avg is the average ZT value.
而工程热电优值(ZT) eng可根据热电优值计算得到，公式为： The engineering thermoelectric figure of merit (ZT) eng can be calculated according to the thermoelectric figure of merit. The formula is:
Figure PCTCN2017119210-appb-000002
Figure PCTCN2017119210-appb-000002
扫描电镜(SEM)Scanning electron microscope (SEM)
首先采用两千目的砂纸打磨样品至表面基本平整，接着在溶剂(水或丙三醇)的作用下使用1μm的抛光膏在抛光机对其进行抛光，直至样品表面光亮并在光学显微镜下样品表面基本没有划痕，然后使用扫描电镜进行观察测试。First, the sample was ground with two thousand mesh sandpaper until the surface was almost flat, and then polished with a 1 μm polishing paste under a solvent (water or glycerol) in a polishing machine until the surface of the sample was bright and the surface of the sample was under an optical microscope. There are basically no scratches, and then a scanning electron microscope is used for the observation test.
致密度Density
通过测量密度与理论密度的比值来计算致密度，其中理论密度可以计算得到，也可以由Springer Materials网站查阅得知，其网址为http://materials.springer.com/。Density is calculated by measuring the ratio of density to theoretical density, which can be calculated from the theoretical density, which is also available on the Springer Materials website at http://materials.springer.com/.
热压烧结装置Hot press sintering device
参照图1，其显示了根据本发明的热压烧结装置。所述装置包括上电极1、下电极7、水冷真空室2和模具组。Referring to Figure 1, there is shown a hot press sintering apparatus in accordance with the present invention. The apparatus includes an upper electrode 1, a lower electrode 7, a water-cooled vacuum chamber 2, and a mold set.
模具组包括模具主体8、上压头4和下压头6，模具主体8具有高度方向的通孔，上压头4和下压头6的高度之和小于模具主体8的高度。The mold set includes a mold main body 8, an upper pressing head 4, and a lower pressing head 6, and the mold main body 8 has a through hole in a height direction, and a sum of heights of the upper pressing head 4 and the lower pressing head 6 is smaller than a height of the mold main body 8.
工作时，模具组置于所述水冷真空室2内，上电极1和下电极7将上压头4和下压头6压入模具主体8的通孔直至上压头4和下压头6分别与模具主体8的上端面和下端面平齐，模具主体8的通孔内形成容纳样品的样品室5。同时上压头4和下压头6无法继续向通孔内移动，使得样品室5(样品的厚度(即体积))得到有效控制，进而得到期望致密度的样品。In operation, a die set is placed in the water-cooled vacuum chamber 2, and the upper electrode 1 and the lower electrode 7 press the upper ram 4 and the lower ram 6 into the through holes of the mold body 8 up to the upper ram 4 and the lower ram 6 The upper end surface and the lower end surface of the mold main body 8 are respectively flush, and a sample chamber 5 for accommodating a sample is formed in the through hole of the mold main body 8. At the same time, the upper ram 4 and the lower ram 6 cannot continue to move into the through hole, so that the sample chamber 5 (thickness (i.e., volume) of the sample) is effectively controlled, thereby obtaining a sample of desired density.
上压头4和下压头6为石墨棒，而模具主体8为石墨模具主体。The upper ram 4 and the lower ram 6 are graphite rods, and the mold body 8 is a graphite mold body.
使用时，将原料粉末填入模具主体8的内腔中并装好上压头4和下压头6，将装配好的模具组放入水冷真空室2中，用上电极1和下电极7夹紧模具组，设定压力及温控程序并开始烧结，烧结结束后使样品自然随炉冷却。In use, the raw material powder is filled into the inner cavity of the mold main body 8 and the upper indenter 4 and the lower indenter 6 are mounted, and the assembled mold set is placed in the water-cooling vacuum chamber 2, and the upper electrode 1 and the lower electrode 7 are used. Clamp the mold set, set the pressure and temperature control program and start sintering. After the sintering is finished, the sample will naturally cool with the furnace.
放电等离子烧结装置Discharge plasma sintering device
参照图2，其显示了根据本发明的放电等离子烧结装置。所述装置包括上电极1、下电极7、水冷真空室2、2个石墨板11、模具组、电源(未显示)和脉冲电流发生器9。Referring to Figure 2, there is shown a spark plasma sintering apparatus in accordance with the present invention. The apparatus includes an upper electrode 1, a lower electrode 7, a water-cooled vacuum chamber 2, two graphite plates 11, a mold set, a power source (not shown), and a pulse current generator 9.
模具组包括模具主体8、上压头4、下压头6、上绝缘层3和下绝缘层10，模具主体8具有高度方向的通孔，上压头4和下压头6的高度之和小于上绝缘层3、模具主体8和下绝缘层10的高度之和。The mold set includes a mold main body 8, an upper pressing head 4, a lower pressing head 6, an upper insulating layer 3, and a lower insulating layer 10. The mold main body 8 has a through hole in a height direction, and a sum of heights of the upper pressing head 4 and the lower pressing head 6. It is smaller than the sum of the heights of the upper insulating layer 3, the mold main body 8, and the lower insulating layer 10.
工作时，模具组置于所述水冷真空室2内，上绝缘层3和下绝缘层4分别置于模具主体8的上端面和下端面，上电极1和下电极7将上压头4和下压头6压入模具主体8的通孔直至上压头4和下压头6分别与上绝缘层3和下绝缘层10平齐，模具主体8的通孔内形成容纳样品的样品室5。同时上压头4和下压头6无法继续向通孔内移动，使得样品室5(样品的厚度(即体积))得到有效控制，进而得到期望致密度的样品。In operation, a mold set is placed in the water-cooled vacuum chamber 2, and an upper insulating layer 3 and a lower insulating layer 4 are respectively placed on the upper end surface and the lower end surface of the mold main body 8, and the upper electrode 1 and the lower electrode 7 are placed on the upper pressing head 4 and The lower ram 6 is pressed into the through hole of the mold main body 8 until the upper ram 4 and the lower ram 6 are flush with the upper insulating layer 3 and the lower insulating layer 10, respectively, and the sample chamber 5 accommodating the sample is formed in the through hole of the mold main body 8. . At the same time, the upper ram 4 and the lower ram 6 cannot continue to move into the through hole, so that the sample chamber 5 (thickness (i.e., volume) of the sample) is effectively controlled, thereby obtaining a sample of desired density.
上压头4和下压头6为石墨棒，而模具主体8为石墨模具主体，上绝缘层3和下绝缘层10为石英棉。The upper indenter 4 and the lower indenter 6 are graphite rods, and the mold main body 8 is a graphite mold main body, and the upper insulating layer 3 and the lower insulating layer 10 are quartz wool.
使用时，将原料粉末填入模具主体8的内腔中并装好上压头4和下压头6，将装配好的模具组放入水冷真空室2中，用上电极1和下电极7夹紧模具组，抽真空至小于等于5Pa，设定压力及温控程序，开启脉冲电流器9并开始烧结，烧结结束后使样品自然随炉冷却。In use, the raw material powder is filled into the inner cavity of the mold main body 8 and the upper indenter 4 and the lower indenter 6 are mounted, and the assembled mold set is placed in the water-cooling vacuum chamber 2, and the upper electrode 1 and the lower electrode 7 are used. Clamp the mold set, evacuate to 5Pa or less, set the pressure and temperature control program, turn on the pulse current device 9 and start sintering. After the sintering is finished, the sample is naturally cooled with the furnace.
实施例1Example 1
本实施例用于说明Zintl相热电材料Mg 3.175Mn 0.025Sb 1.98Bi 0.5Te 0.02及其制备。 This example is intended to illustrate the Zintl phase thermoelectric material Mg 3.175 Mn 0.025 Sb 1.98 Bi 0.5 Te 0.02 and its preparation.
首先按照化学计量将各元素单质颗粒球磨12个小时，形成粒径为200纳米～10微米的粉末，在深圳大学与思维特电源设备有限公司共同研发的FDS-4000型放电等离子烧结炉中，采用常规放电等离子烧结方法将此粉末烧结成致密块体(此过程为一次烧结)，烧结条件如下：真空度为5Pa，压力为50MPa，升温速率50℃/分钟，烧结温度为600℃，保温时间5分钟。Firstly, the elemental particles of each element were ball milled for 12 hours according to stoichiometry to form a powder with a particle size of 200 nm to 10 μm, which was used in the FDS-4000 discharge plasma sintering furnace jointly developed by Shenzhen University and Thinking Special Power Equipment Co., Ltd. The conventional discharge plasma sintering method sinters the powder into a dense block (this process is one-time sintering), and the sintering conditions are as follows: a vacuum of 5 Pa, a pressure of 50 MPa, a heating rate of 50 ° C / min, a sintering temperature of 600 ° C, and a holding time of 5 minute.
然后将一次烧结的块体材料球磨4个小时，形成粒径为200纳米～10微米的原料粉末，将此粉末在图2所示的装置中进行二次烧结，从而得到具有多尺度微纳多孔结构的样品。二次烧结中，真空度为5Pa，压力为50MPa，升温速率50℃/分钟，烧结温度为800℃，保温时间5分钟，烧结结束后使样品自然随炉冷却，得到具有多尺度微纳孔洞(多孔)结构的样品。Then, the sintered bulk material is ball milled for 4 hours to form a raw material powder having a particle diameter of 200 nm to 10 μm, and this powder is subjected to secondary sintering in the apparatus shown in Fig. 2, thereby obtaining a multi-scale micro-nanoporous. Structure of the sample. In the secondary sintering, the degree of vacuum is 5 Pa, the pressure is 50 MPa, the heating rate is 50 ° C / min, the sintering temperature is 800 ° C, and the holding time is 5 minutes. After the sintering is finished, the sample is naturally cooled with the furnace to obtain a multi-scale micro-nano hole ( A sample of the porous structure.
图3和图4显示了实施例1样品不同放大倍数的代表性SEM图。SEM结果显示，实施例1样品具有多尺度的微纳级孔隙(多孔)结构。实施例1样品的致密度为85％。Figures 3 and 4 show representative SEM images of different magnifications of the Example 1 samples. The SEM results show that the sample of Example 1 has a multi-scale micro-nano pore (porous) structure. The densification of the sample of Example 1 was 85%.
采用透射电镜对样品的晶体结构进行标定并与ICDD标准数据库对照，发现实施例1制得的样品包括连续相以及分散在连续相中的分散相，连续相为Mg 3.175Mn 0.025Sb 1.98-zBi zTe 0.02，其中z在0～0.5之间变化，而分散相为β-Mg 3Bi 2。 The crystal structure of the sample was calibrated by transmission electron microscopy and compared with the ICDD standard database. It was found that the sample prepared in Example 1 included a continuous phase and a dispersed phase dispersed in the continuous phase, and the continuous phase was Mg 3.175 Mn 0.025 Sb 1.98-z Bi z Te 0.02 , wherein z varies between 0 and 0.5, and the dispersed phase is β-Mg 3 Bi 2 .
分别测量一次烧结的块体材料和二次烧结的块体热电材料(即实施例1样品)的热电优值ZT和工程热电优值(ZT) eng。结果显示，室温下热导率由1Wm -1k -1降低到0.69Wm -1k -1，而对于热电材料来说热导率越低对热电性能越有利，室温下功率因子由1149μWm -1K -2 提升至2267μWm -1K -2(功率因子为塞贝克系数的平方与电导率的乘积)，室温下的热电优值ZT由0.37提升至1.06，热电优值ZT的峰值从1.6提升至2.14，工程热电优值(ZT) eng的峰值从0.82提升至1.29。二次烧结的块体热电材料的热电优值ZT和工程热电优值(ZT) eng均为目前此材料体系中的最高值，也是目前热电材料领域块体热电材料的最高记录值。 The thermoelectric figure of merit ZT and the engineering thermoelectric figure of merit (ZT) eng of the sintered bulk material and the secondary sintered bulk thermoelectric material (ie, the sample of Example 1) were measured separately. The results show that the thermal conductivity decreases from 1Wm -1 k -1 to 0.69Wm -1 k -1 at room temperature, while the lower the thermal conductivity for thermoelectric materials, the better the thermoelectric performance. The power factor at room temperature is 1149μWm -1 K -2 is increased to 2267μWm -1 K -2 (the power factor is the product of the square of the Seebeck coefficient and the conductivity). The thermoelectric figure of merit ZT at room temperature is increased from 0.37 to 1.06, and the peak value of the thermoelectric figure ZT is raised from 1.6 to 2.14, the peak value of engineering thermoelectric figure of merit (ZT) eng increased from 0.82 to 1.29. The thermoelectric figure of merit ZT and the engineering thermoelectric figure of merit (ZT) eng of the secondary sintered block thermoelectric materials are the highest values in the current material system, and are also the highest recorded values of the block thermoelectric materials in the field of thermoelectric materials.
实施例2Example 2
本实施例用于说明Half-Heusler合金热电材料Hf 0.25Zr 0.75NiSn 0.99Sb 0.01及其制备。 This embodiment is for explaining a Half-Heusler alloy thermoelectric material Hf 0.25 Zr 0.75 NiSn 0.99 Sb 0.01 and its preparation.
首先按照化学计量将各元素单质经电弧熔炼制成铸锭，之后球磨12个小时形成粒径为200～600纳米的粉末，将这种粉末在图2所示的装置中进行放电等离子烧结，真空度为5Pa，压力为60MPa，升温速率40℃/分钟，烧结温度为900℃，保温时间20分钟，烧结结束后使样品随炉自然冷却，得到具有多尺度微纳孔隙(多孔)结构的样品。First, each element element is subjected to arc melting to form an ingot according to stoichiometry, and then ball milling for 12 hours to form a powder having a particle diameter of 200 to 600 nm, and the powder is subjected to discharge plasma sintering in the apparatus shown in FIG. The degree is 5 Pa, the pressure is 60 MPa, the heating rate is 40 ° C / min, the sintering temperature is 900 ° C, and the holding time is 20 minutes. After the sintering is finished, the sample is naturally cooled with the furnace to obtain a sample having a multi-scale micro-nano pore (porous) structure.
图5和图6显示了实施例2样品不同放大倍数的代表性SEM图。SEM结果显示，实施例2样品具有多尺度的微纳级孔隙(多孔)结构。实施例2样品的致密度为93％。Figures 5 and 6 show representative SEM images of different magnifications of the Example 2 samples. The SEM results show that the sample of Example 2 has a multi-scale micro-nano pore (porous) structure. The sample of Example 2 had a density of 93%.
另外，采用深圳大学与思维特电源设备有限公司共同研发的FDS-4000型放电等离子烧结炉制备Hf 0.25Zr 0.75NiSn 0.99Sb 0.01的致密材料作为参照样品。具体地，首先按照化学计量将各元素单质经电弧熔炼制成铸锭，之后球磨12个小时形成粒径为200～600纳米的粉末，然后采用常规放电等离子烧结方法将此粉末烧结成致密块体，烧结条件如下：真空度为5Pa，压力为60MPa，升温速率40℃/分钟，烧结温度为900℃，保温时间20分钟。 In addition, a dense material of Hf 0.25 Zr 0.75 NiSn 0.99 Sb 0.0 1 was prepared as a reference sample by using FDS-4000 discharge plasma sintering furnace jointly developed by Shenzhen University and Thinking Power Equipment Co., Ltd. Specifically, first, each element element is subjected to arc melting to form an ingot according to stoichiometry, and then ball-milled for 12 hours to form a powder having a particle diameter of 200 to 600 nm, and then the powder is sintered into a dense block by a conventional discharge plasma sintering method. The sintering conditions were as follows: a vacuum of 5 Pa, a pressure of 60 MPa, a heating rate of 40 ° C / min, a sintering temperature of 900 ° C, and a holding time of 20 minutes.
分别测量参照样品和实施例2样品的热电优值ZT和工程热电优值(ZT) eng。结果显示，热电优值ZT的峰值从1提升至1.13，工程热电优值(ZT) eng的峰值从0.68提升至0.74。 The thermoelectric figure of merit ZT and the engineering thermoelectric figure of merit (ZT) eng of the reference sample and the sample of Example 2 were measured, respectively. The results show that the peak value of the thermoelectric figure ZT is increased from 1 to 1.13, and the peak value of the engineering thermoelectric figure of merit (ZT) eng is increased from 0.68 to 0.74.
实施例3Example 3
本实施例用于说明Bi 2Te 3基材料Bi 0.5Sb 1.5Te 3及其制备。 This example is intended to illustrate the Bi 2 Te 3 based material Bi 0.5 Sb 1.5 Te 3 and its preparation.
首先按照化学计量将各元素单质颗粒球磨9小时，形成粒径为100～300纳米的粉末，将这种粉末在图2所示的装置中进行放电等离子烧结，真空度为5Pa，压力为50MPa，升温速率70℃/分钟，烧结温度为450℃，保温时间5分钟，烧结结束后使样品随炉自然冷却，得到具有多尺度微纳孔隙(多孔)结构的样品。First, the elemental particles of each element were ball milled for 9 hours according to stoichiometry to form a powder having a particle diameter of 100 to 300 nm, and the powder was subjected to spark plasma sintering in a device shown in Fig. 2, and the degree of vacuum was 5 Pa, and the pressure was 50 MPa. The heating rate was 70 ° C / min, the sintering temperature was 450 ° C, and the holding time was 5 minutes. After the sintering was completed, the sample was naturally cooled with the furnace to obtain a sample having a multi-scale micro-nano pore (porous) structure.
图7和图8显示了实施例3样品不同放大倍数的代表性SEM图。SEM结果显示，实施例3样品具有多尺度的微纳级孔隙(多孔)结构。实施例3样品的致密度为81％。Figures 7 and 8 show representative SEM images of different magnifications of the Example 3 samples. The SEM results show that the sample of Example 3 has a multi-scale micro-nano pore (porous) structure. The densification of the sample of Example 3 was 81%.
另外，采用深圳大学与思维特电源设备有限公司共同研发的FDS-4000型放电等离子烧结炉制备Bi 0.5Sb 1.5Te 3的致密材料作为参照样品。具体地，首先按照化学计量将各元素单质颗粒球磨9小时，形成粒径为100～300纳米的粉末，然后采用常规放电等离子烧结方法将此粉末烧结成致密块体，烧结条件如下：真空度为5Pa，压力为50MPa，升温速率70℃/分钟，烧结温度为450℃，保温时间5分钟。 In addition, a dense material of Bi 0.5 Sb 1.5 Te 3 was prepared as a reference sample by using an FDS-4000 discharge plasma sintering furnace jointly developed by Shenzhen University and Thinking Power Equipment Co., Ltd. Specifically, first, the elemental particles of each element are ball milled for 9 hours according to stoichiometry to form a powder having a particle diameter of 100 to 300 nm, and then the powder is sintered into a dense block by a conventional discharge plasma sintering method, and the sintering conditions are as follows: the degree of vacuum is 5 Pa, pressure 50 MPa, heating rate 70 ° C / min, sintering temperature 450 ° C, holding time 5 minutes.
测量参照样品和实施例3样品的热电优值和工程热电优值(ZT) eng。结果显示，热电优值ZT的峰值从1.22提升至1.34，工程热电优值(ZT) eng的峰值从0.43提升至0.5。 The thermoelectric figure of merit and the engineering thermoelectric figure of merit (ZT) eng of the reference sample and the sample of Example 3 were measured. The results show that the peak value of the thermoelectric figure ZT is increased from 1.22 to 1.34, and the peak value of the engineering thermoelectric figure of merit (ZT) eng is raised from 0.43 to 0.5.

Claims (10)

  1. 一种热压烧结装置，所述装置包括上电极(1)、下电极(7)、水冷真空室(2)和模具组，其中，所述模具组包括模具主体(8)、上压头(4)和下压头(6)，所述模具主体(8)具有高度方向的通孔，以及所述上压头(4)和所述下压头(6)的高度之和小于所述模具主体(8)的高度；A hot press sintering apparatus comprising an upper electrode (1), a lower electrode (7), a water-cooled vacuum chamber (2) and a mold set, wherein the mold set comprises a mold body (8) and an upper pressing head ( 4) and a lower pressing head (6), the mold body (8) has a through hole in a height direction, and a sum of heights of the upper pressing head (4) and the lower pressing head (6) is smaller than the mold The height of the main body (8);
    工作时，所述模具组置于所述水冷真空室(2)内，所述上电极(1)和所述下电极(7)将所述上压头(4)和所述下压头(6)压入所述模具主体(8)的通孔直至所述上压头(4)和所述下压头(6)分别与所述模具主体(8)的上端面和下端面平齐，所述模具主体(8)的通孔内形成容纳样品的样品室(5)。In operation, the mold set is placed in the water-cooled vacuum chamber (2), and the upper electrode (1) and the lower electrode (7) press the upper pressing head (4) and the lower pressing head ( 6) pressing the through hole of the mold body (8) until the upper pressing head (4) and the lower pressing head (6) are flush with the upper end surface and the lower end surface of the mold main body (8), respectively. A sample chamber (5) containing a sample is formed in the through hole of the mold body (8).
  2. 根据权利要求1所述的热压烧结装置，其中，所述装置为放电等离子烧结装置，所述模具组包括模具主体(8)、上压头(4)、下压头(6)、上绝缘层(3)和下绝缘层(10)，所述模具主体(8)具有高度方向的通孔，以及所述上压头(4)和所述下压头(6)的高度之和小于所述上绝缘层(3)、所述模具主体(8)和所述下绝缘层(10)的高度之和；The hot press sintering apparatus according to claim 1, wherein said apparatus is a discharge plasma sintering apparatus, and said mold set comprises a mold main body (8), an upper pressing head (4), a lower pressing head (6), and an upper insulation. a layer (3) and a lower insulating layer (10), the mold body (8) has a through hole in a height direction, and a sum of heights of the upper pressing head (4) and the lower pressing head (6) is smaller than The sum of the heights of the insulating layer (3), the mold body (8) and the lower insulating layer (10);
    工作时，所述模具组置于所述水冷真空室(2)内，所述上绝缘层(3)和所述下绝缘层(10)分别置于所述模具主体(8)的上端面和下端面，所述上电极(1)和所述下电极(7)将所述上压头(4)和所述下压头(6)压入所述模具主体(8)的通孔直至所述上压头(4)和所述下压头(6)分别与所述上绝缘层(3)和所述下绝缘层(10)平齐，所述模具主体(8)的通孔内形成容纳样品的样品室(5)。In operation, the mold set is placed in the water-cooled vacuum chamber (2), and the upper insulating layer (3) and the lower insulating layer (10) are respectively placed on the upper end surface of the mold body (8) and a lower end surface, the upper electrode (1) and the lower electrode (7) press the upper pressing head (4) and the lower pressing head (6) into a through hole of the mold body (8) until The upper indenter (4) and the lower indenter (6) are flush with the upper insulating layer (3) and the lower insulating layer (10), respectively, and the through hole of the mold body (8) is formed. A sample chamber (5) containing the sample.
  3. 根据权利要求1或2所述的装置，其中，所述上压头(4)、所述下压头(6)和所述模具主体(8)由金属、合金或石墨制成；The device according to claim 1 or 2, wherein the upper indenter (4), the lower indenter (6) and the mold body (8) are made of metal, alloy or graphite;
    优选地，所述上压头(4)和所述下压头(6)为石墨棒，所述模具主体(8)为石墨模具主体；Preferably, the upper pressing head (4) and the lower pressing head (6) are graphite rods, and the mold body (8) is a graphite mold body;
    优选地，所述上绝缘层(3)和所述下绝缘层(10)为石英棉。Preferably, the upper insulating layer (3) and the lower insulating layer (10) are quartz wool.
  4. 一种多尺度微纳多孔结构的块体热电材料的制备方法，所述方法包括：采用权利要求1至3中任一项所述的热压烧结装置对原 料粉末进行烧结，从而得到多尺度微纳多孔结构的块体热电材料。A method for preparing a bulk thermoelectric material of a multi-scale micro-nano porous structure, the method comprising: sintering a raw material powder by using the hot-press sintering device according to any one of claims 1 to 3, thereby obtaining multi-scale micro A bulk porous thermoelectric material of nanoporous structure.
  5. 根据权利要求4所述的制备方法，其中，通过调节所加入的原料粉末的量和/或改变所述上压头和/或所述下压头的高度来控制块体热电材料的致密度；The production method according to claim 4, wherein the density of the bulk thermoelectric material is controlled by adjusting the amount of the raw material powder to be added and/or changing the height of the upper indenter and/or the lower indenter;
    优选地，所述热电材料的致密度为60％～100％，优选为70％～95％，进一步优选为70％～90％，最优选为80％～90％；Preferably, the thermoelectric material has a density of 60% to 100%, preferably 70% to 95%, further preferably 70% to 90%, and most preferably 80% to 90%;
    优选地，原料粉末的粒径范围为10纳米～100微米，优选为100纳米～10微米。Preferably, the raw material powder has a particle diameter ranging from 10 nm to 100 μm, preferably from 100 nm to 10 μm.
  6. 根据权利要求4或5所述的制备方法，其中，所述热电材料为n型Mn掺杂Mg 3Sb 2材料、诸如FeNbSb基材料的半赫斯勒(Half-Heusler)合金热电材料、Bi 2Te 3基材料或MgSiSn基材料； The production method according to claim 4 or 5, wherein the thermoelectric material is an n-type Mn doped Mg 3 Sb 2 material, a half-Heusler alloy thermoelectric material such as an FeNbSb-based material, Bi 2 a Te 3 based material or a MgSiSn based material;
    优选地，所述热电材料为Hf 0.25Zr 0.75NiSn 0.99Sb 0.01、Bi 0.5Sb 1.5Te 3或Mg 3.2-xMn xSb 1.5-yBi 0.5Te y，其中0.0125≤x≤0.1，以及0.01≤y≤0.05，优选为Mg 3.175Mn 0.025Sb 1.98Bi 0.5Te 0.02。 Preferably, the thermoelectric material is Hf 0.25 Zr 0.75 NiSn 0.99 Sb 0.01 , Bi 0.5 Sb 1.5 Te 3 or Mg 3.2-x Mn x Sb 1.5-y Bi 0.5 Te y , wherein 0.0125≤x≤0.1, and 0.01≤y ≤ 0.05, preferably Mg 3.175 Mn 0.025 Sb 1.98 Bi 0.5 Te 0.02 .
  7. 根据权利要求4至6中任一项所述的制备方法，其中，所述原料粉末是包含热电材料的相应元素的固体单质粉末的混合物或热电材料的预烧结粉末；The production method according to any one of claims 4 to 6, wherein the raw material powder is a mixture of solid elemental powders containing respective elements of a thermoelectric material or a pre-sintered powder of a thermoelectric material;
    所述原料粉末的粒径范围为10纳米～100微米，优选为100纳米～10微米。The raw material powder has a particle diameter ranging from 10 nm to 100 μm, preferably from 100 nm to 10 μm.
  8. 根据权利要求4至7中任一项所述的制备方法，其中，所述方法包括：装配模具组和同时向模具主体的通孔中装填原料粉末，将装配好的模具组放入水冷真空室中，用上电极和下电极夹紧模具组，然后进行烧结例如放电等离子烧结；The production method according to any one of claims 4 to 7, wherein the method comprises: assembling a mold set and simultaneously filling a raw material powder into a through hole of the mold main body, and placing the assembled mold set into a water-cooled vacuum chamber Medium, clamping the mold set with the upper electrode and the lower electrode, and then performing sintering, such as discharge plasma sintering;
    优选地，所述烧结例如放电等离子烧结是在真空下进行的，所述水冷真空室的真空度优选为小于等于5Pa；Preferably, the sintering, such as spark plasma sintering, is performed under vacuum, and the degree of vacuum of the water-cooled vacuum chamber is preferably 5 Pa or less;
    优选地，所述烧结例如放电等离子烧结的压力为5～120MPa，例如40～60MPa；Preferably, the sintering, such as discharge plasma sintering, has a pressure of 5 to 120 MPa, for example 40 to 60 MPa;
    优选地，所述烧结例如放电等离子烧结的温度为100～2000℃，例如450～900℃温度，时间优选为1～120分钟，例如5～20分钟；Preferably, the temperature of the sintering, for example, plasma sintering, is 100 to 2000 ° C, for example, 450 to 900 ° C, and the time is preferably 1 to 120 minutes, for example 5 to 20 minutes;
    优选地，所述烧结例如放电等离子烧结的升温速率为5～100℃/分钟，优选为20～60℃/分钟，更优选为50～60℃/分钟。Preferably, the sintering, for example, discharge plasma sintering, has a heating rate of 5 to 100 ° C / min, preferably 20 to 60 ° C / min, more preferably 50 to 60 ° C / min.
  9. 一种多尺度微纳多孔结构的块体热电材料，其化学式为 Mg 3.2-xMn xSb 1.5-yBi 0.5Te y，其中0.0125≤x≤0.1，以及0.01≤y≤0.05。 A multi-scale micro-nano porous structure block thermoelectric material having a chemical formula of Mg 3.2-x Mn x Sb 1.5-y Bi 0.5 Te y , wherein 0.0125≤x≤0.1, and 0.01≤y≤0.05.
  10. 根据权利要求9所述的热电材料，其中，所述热电材料的致密度为60％～100％，优选为70％～95％，进一步优选为70％～90％，最优选为80％～90％；The thermoelectric material according to claim 9, wherein said thermoelectric material has a density of from 60% to 100%, preferably from 70% to 95%, further preferably from 70% to 90%, most preferably from 80% to 90%. %;
    优选地，所述热电材料包括连续相以及分散在连续相中的分散相；Preferably, the thermoelectric material comprises a continuous phase and a dispersed phase dispersed in the continuous phase;
    更优选地，所述热电材料的化学式为Mg 3.175Mn 0.025Sb 1.98Bi 0.5Te 0.02； More preferably, the chemical formula of the thermoelectric material is Mg 3.175 Mn 0.025 Sb 1.98 Bi 0.5 Te 0.02 ;
    更优选地，所述连续相的化学式为Mg 3.175Mn 0.025Sb 1.98-zBi zTe 0.02，其中，所述连续相中0≤z≤0.5，以及所述分散相为β-Mg 3Bi 2。 More preferably, the chemical formula of the continuous phase is Mg 3.175 Mn 0.025 Sb 1.98-z Bi z Te 0.02 , wherein 0 ≤ z ≤ 0.5 in the continuous phase, and the dispersed phase is β-Mg 3 Bi 2 .
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