WO2010055615A1 - Silicium haute qualité et matière de conversion thermoélectrique - Google Patents

Silicium haute qualité et matière de conversion thermoélectrique Download PDF

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WO2010055615A1
WO2010055615A1 PCT/JP2009/005569 JP2009005569W WO2010055615A1 WO 2010055615 A1 WO2010055615 A1 WO 2010055615A1 JP 2009005569 W JP2009005569 W JP 2009005569W WO 2010055615 A1 WO2010055615 A1 WO 2010055615A1
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silicon
waste
silicon waste
thermoelectric conversion
conversion material
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PCT/JP2009/005569
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English (en)
Japanese (ja)
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林正裕
大島建司
玄場公規
安野拓也
坂本直道
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株式会社林商会
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Publication of WO2010055615A1 publication Critical patent/WO2010055615A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/037—Purification
    • 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
    • H10N10/01—Manufacture or treatment
    • 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
    • H10N10/80—Constructional details
    • H10N10/85—Thermoelectric active materials
    • H10N10/851—Thermoelectric active materials comprising inorganic compositions
    • H10N10/855—Thermoelectric active materials comprising inorganic compositions comprising compounds containing boron, carbon, oxygen or nitrogen
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to high-purity silicon, and more particularly to high-purity silicon produced by reusing silicon waste generated from the production process of silicon wafers.
  • the present invention also relates to a thermoelectric conversion material, and more particularly to a thermoelectric conversion material produced by reusing silicon waste generated from a production process of a silicon wafer.
  • the silicon single crystal of the semiconductor substrate raw material is manufactured through processes of silica reduction, conversion to monosilane, hydrogen reduction, single crystal silicon pulling process, and consumes a lot of energy. Furthermore, the silicon chip as the semiconductor substrate is silicon The single crystal is obtained by slicing a single crystal as a silicon wafer through wrapping and polishing steps, and finally dicing. The yield from the silicon single crystal to the silicon chip is only 30%, and the remaining 70 % Is treated as waste as silicon sludge.
  • Patent Document 1 in a method for producing silicon for solar cells, silicon waste generated in the semiconductor industry is used as a starting material, and this is first melted, and then has a through-hole at the bottom, and a silicon compound. Filtration is carried out with a filtration device filled with a substance mainly composed of a silicon compound as a filter material in a filtration container composed of the substance as a main component, then subjected to an oxidation treatment after the filtration treatment, and then subjected to a decompression treatment, A method for producing silicon for solar cells, characterized by unidirectional solidification, is disclosed.
  • silicon sludge waste is deposited in a landfill or burned in an incinerator, but if sludge is deposited in a landfill, there is a risk that oil and glycol will leach into the soil, It has become an environmental problem.
  • incineration in an incinerator converts silicon powder in silicon sludge into contaminated silicon dioxide and deposits it in the soil.
  • silicon powder waste is accompanied by environmental pollution, an increase in cost for environmental measures is a problem.
  • the concern about environmental pollution from silicon powder waste is expected to increase further in the future. Therefore, there is a particular need for a method for easily and safely reusing a large amount of silicon sludge waste while reducing environmental measures costs.
  • Patent Document 1 since the invention disclosed in Patent Document 1 must be subjected to a filtration treatment, the filtration treatment requires time and cost, and is not accompanied by profitability as industrial reuse.
  • silicon waste can be reused easily and inexpensively to obtain high-purity silicon, it can greatly contribute to the reuse of silicon sludge in consideration of environmental measures.
  • thermoelectric conversion material from a mixture of silicon and iron using the melting method.
  • the metal formed by the melting method is used.
  • the semiconductor phase ( ⁇ phase) of the Fe—Si-based thermoelectric conversion material can be obtained by further heat-treating the phases ( ⁇ phase, ⁇ phase) for a longer time.
  • the dissolution method requires time and cost, and is not accompanied by profitability as industrial reuse.
  • thermoelectric conversion material if silicon waste can be reused easily and inexpensively to obtain a thermoelectric conversion material, it can greatly contribute to the reuse of silicon sludge in consideration of environmental measures.
  • the present invention has been made to solve the conventional problems, and an object of the present invention is to provide high-purity silicon produced using silicon waste. Moreover, an object of this invention is to provide the thermoelectric conversion material produced
  • the high-purity silicon of the present invention is produced by sintering silicon waste at a high density in a non-oxidizing atmosphere by a discharge plasma sintering method.
  • the silicon waste is sintered at a sintering temperature of about 900 ° C. or higher.
  • the silicon temperature of the silicon waste can be efficiently increased by setting the sintering temperature to about 900 ° C. or higher.
  • the silicon waste is sintered at a sintering temperature of about 900 ° C.
  • the silicon purity of the silicon waste can be increased more efficiently by setting the sintering temperature to about 900 ° C.
  • the silicon waste is sintered with a holding time of about 1800 seconds or more.
  • the silicon purity of the silicon waste can be increased efficiently by setting the holding time to about 1800 ° C. or higher.
  • the high-purity silicon of the present invention is produced by dissolving the silicon waste sintered by the discharge plasma sintering method in a vacuum or a non-oxidizing atmosphere.
  • the high-purity silicon of the present invention is produced by dissolving the silicon waste at a melting temperature of 1800 ° C. or higher.
  • the impurities are vaporized and the impurities in the silicon waste can be removed.
  • the high-purity silicon of the present invention is produced by dissolving the silicon waste under a reduced pressure of 1.3 ⁇ 10 ⁇ 1 Pa or less.
  • the impurities are vaporized and the impurities in the silicon waste can be removed.
  • the high-purity silicon of the present invention is produced by melting the silicon waste with either a melting furnace or a discharge plasma sintering apparatus.
  • the high-purity silicon of the present invention is produced when the silicon waste contains SiO and SiC.
  • the reduction action of silicon oxide can be promoted by the reaction between SiO and SiC resulting in the redox action.
  • the high-purity silicon of the present invention is produced by mixing and dissolving a C-based material or a Ca-based material in the silicon waste.
  • the reduction action of silicon oxide can be promoted by using a system substance or a Ca system substance as a reducing agent.
  • the high-purity silicon of the present invention is produced by spraying an inert gas on the surface of the dissolved silicon waste.
  • slag is concentrated near the surface of the silicon waste by blowing an inert gas onto the surface of the dissolved silicon waste, so that high-purity silicon is produced by separating this slag portion. can do.
  • the high-purity silicon of the present invention is produced by cooling the dissolved silicon waste and performing an annealing treatment in a hydrogen atmosphere.
  • thermoelectric conversion material according to the present invention is characterized by being produced by mixing silicon waste with an Fe component and sintering in a non-oxidizing atmosphere by a discharge plasma sintering method.
  • thermoelectric conversion material is generated by rapidly heating, holding a temperature for a short time, and rapidly cooling a mixture of silicon and Fe by a discharge plasma sintering method, and silicon waste is used.
  • a thermoelectric conversion material can be obtained simply and inexpensively.
  • thermoelectric conversion material according to the present invention is characterized in that the silicon waste is a silicon waste in which silicon is highly purified by sintering in a non-oxidizing atmosphere by a discharge plasma sintering method.
  • thermoelectric conversion material Since there is no need to reduce silicon waste with a reducing agent, a thermoelectric conversion material can be obtained simply and inexpensively.
  • the mixture of the silicon waste and the Fe component is a mixture obtained by solidifying the silicon waste with an aggregating agent containing Fe.
  • thermoelectric conversion material by using Fe contained in the flocculant as a part of the thermoelectric conversion material, silicon waste aggregated by the flocculant can be used as it is, and a process of separately mixing an iron component Therefore, a thermoelectric conversion material can be obtained at low cost.
  • thermoelectric conversion material according to the present invention is characterized in that the aggregating agent containing Fe is iron chloride, iron sulfide, or a combination thereof.
  • Fe contained in the flocculant can be used as a part of the thermoelectric conversion material.
  • thermoelectric conversion material an Al component is mixed with the silicon waste, and the mixture of the silicon waste and the Al component is a mixture obtained by solidifying the silicon waste with a flocculant containing Al. It is characterized by that.
  • thermoelectric conversion material since the Al contained in the flocculant is used as a substitution metal element when generating the p-type thermoelectric conversion material, a separate Al doping process is not required. Aggregated silicon waste can be used as it is, and a thermoelectric conversion material can be obtained at low cost.
  • thermoelectric conversion material according to the present invention is characterized in that the aggregating agent containing Al is aluminum oxide, aluminum sulfide, polyaluminum chloride, or a combination thereof.
  • Al contained in the flocculant can be used as a part of the thermoelectric conversion material.
  • thermoelectric conversion material according to the present invention is characterized in that the silicon waste is generated from a production process of a silicon wafer.
  • the silicon waste is generated by a cleaning process, and is a silicon waste mainly composed of pure water and Si.
  • thermoelectric conversion material high-purity silicon waste can be used as it is, and silicon waste can be reused easily and inexpensively to obtain a thermoelectric conversion material.
  • the silicon waste is a silicon waste solid-liquid separated by centrifugation, squeezing separation, sedimentation separation, floating separation, or a combination thereof.
  • thermoelectric conversion material can be obtained.
  • thermoelectric conversion material according to the present invention is characterized in that the non-oxidizing atmosphere is any one of vacuum, nitrogen gas, argon gas, hydrogen gas, or a mixed gas thereof.
  • thermoelectric conversion material by sintering in a non-oxidizing atmosphere, an oxidation reaction can be prevented in the process of forming the Fe—Si based thermoelectric conversion material, and a suitable thermoelectric conversion material can be obtained.
  • thermoelectric conversion material according to the present invention is characterized in that the sintering is performed at a pressure of 10 to 100 MPa and a heating / sintering temperature of 500 to 2000 ° C.
  • thermoelectric conversion material a non-equilibrium phase having a high figure of merit as a thermoelectric conversion material is formed, and ⁇ -FeSi 2 having a ⁇ phase is generated.
  • thermoelectric conversion material The method for producing a thermoelectric conversion material according to the present invention is characterized in that it is produced by mixing silicon waste with an Fe component and sintering it in a non-oxidizing atmosphere by a discharge plasma sintering method.
  • thermoelectric conversion material is generated by rapidly heating, holding a temperature for a short time, and rapidly cooling a mixture of silicon and Fe by a discharge plasma sintering method, and silicon waste is used.
  • a thermoelectric conversion material can be obtained simply and inexpensively.
  • silicon waste is dissolved in a vacuum or non-oxidizing atmosphere to remove impurities in silicon waste, reduce silicon oxide, and reuse silicon waste easily and inexpensively.
  • the high-purity silicon can be produced.
  • thermoelectric conversion material is produced by rapid heating, holding temperature for a short time, and quenching a mixture of silicon and Fe by a discharge plasma sintering method, and silicon waste is By using it, a thermoelectric conversion material can be obtained simply and inexpensively.
  • FIG. 1 is a basic configuration diagram of a discharge plasma sintering apparatus used in this example. The sintering process by the discharge plasma sintering apparatus used in this example is shown.
  • the high-purity silicon according to the embodiment of the present invention is produced by discharge plasma sintering (SPS) and melting silicon waste in a vacuum or non-oxidizing atmosphere.
  • SPS discharge plasma sintering
  • the spark plasma sintering method is a method in which an on-off DC pulse voltage / current is applied to a green compact, and a sintered body is produced by a discharge phenomenon that occurs between the powder particles.
  • metals, ceramics, etc. can be sintered at high density.
  • Sintering is mainly performed by heat generation using graphite as a resistor, but the pulse electric field promotes the movement / diffusion of ions, vacancies and dislocations. Can be sintered.
  • sintering by the discharge plasma sintering method a uniform high-quality sintered body can be easily obtained with uniform pressure by dispersion of discharge points.
  • Silicon waste may be sintered by a discharge plasma sintering method without separating the liquid fraction from the solid fraction. Further, silicon waste may be sintered by a discharge plasma sintering method without using a sintering aid.
  • the present inventor uses a discharge plasma sintering apparatus and a melting furnace to treat silicon waste mainly composed of SiO or SiO 2 at a high temperature in a vacuum or a non-oxidizing atmosphere, thereby converting high-purity silicon from silicon waste.
  • a discharge plasma sintering apparatus it has been found that high purity silicon can be produced by sintering silicon waste using a discharge plasma sintering apparatus.
  • high-purity silicon can be obtained efficiently by setting the sintering temperature to about 900 ° C. or higher (preferably about 900 ° C.). It was also found that high-purity silicon can be obtained efficiently by setting the holding time to 1800 seconds or longer.
  • the silicon waste sintered using the discharge plasma sintering is melted and processed at a high temperature, so that SiO is gasified and components containing Al, Mg, Ca, P, and B which are impurities It has been found that even higher purity silicon can be obtained by gasifying and removing the gasified impurities. And when the slag was isolate
  • FIG. 1 is a graph showing the relationship between sintering temperature and component concentration of silicon waste.
  • the horizontal axis represents the sintering temperature, and the vertical axis represents the component concentration in the silicon waste.
  • the silicon waste (silicon grinding sludge) was dehydrated and then sintered using a discharge plasma sintering apparatus.
  • the sintering temperatures are 900 ° C. (1173 K), 1000 ° C. (1273 K), 1100 ° C. (1373 K), and 1200 ° C. (1473 K), and the holding temperature is 1800 seconds (1800 s).
  • FIG. 1 it is clear that the silicon concentration is increased by about 20% by sintering silicon waste at a sintering temperature of about 900 ° C.
  • the silicon waste sintered by the discharge plasma sintering apparatus is melted and processed at a high temperature.
  • FIG. 2 is a graph showing the relationship between the heating temperature of silicon waste and the component concentration of impurity gas.
  • the horizontal axis represents the heating temperature
  • the vertical axis represents the component concentration of the impurity gas generated from the silicon waste.
  • SiO gas is generated when the heating temperature is about 1400 ° C., and a large amount of SiO gas is stably generated at 1800 ° C. or higher.
  • a gas amount due to Fe, Al, and Mg impurity elements is generated in addition to the SiO gas.
  • the heating temperature is 2400 ° C. or higher, all of impurity gases of SiO, Fe, Al, and Mg are stably generated in large quantities.
  • SiO, Fe, Al, and Mg impurity gases can be removed by dissolving silicon waste at a heating temperature (melting temperature) of 1800 ° C. or higher.
  • a heating temperature melting temperature
  • 2400 ° C. or higher a large amount of impurity gas can be removed.
  • impurities can be removed from the silicon waste, and high-purity silicon can be generated.
  • the silicon waste sintered by the discharge plasma sintering apparatus is melted using a vacuum induction melting furnace.
  • Vacuum induction melting furnaces used for casting special steels and non-ferrous metals are characterized by homogeneous melting by electromagnetic stirring, and can be melted in a reduced-pressure atmosphere or in vacuum using high-frequency induction heating and vacuum technology. It is.
  • a crucible is installed in a chamber of a vacuum induction melting furnace, and silicon wafer cutting waste is melted in this crucible.
  • the crucible is made of carbon.
  • the silicon wafer cutting waste is silicon waste containing SiO, but may contain SiC.
  • SiC is used for a grindstone for polishing a silicon wafer, and may be contained in cutting waste of the silicon wafer. In this case, SiC functions as a reducing agent that reduces SiO.
  • High temperature heat treatment of silicon waste is performed by making the inside of a vacuum induction melting furnace chamber a vacuum or a non-oxidizing atmosphere.
  • a vacuum or a non-oxidizing atmosphere By using a vacuum or a non-oxidizing atmosphere, the oxidation of silicon can be prevented and the reduction of silicon oxide can be promoted. Therefore, by treating silicon waste at high temperature in a vacuum or non-oxidizing atmosphere, impurities in the silicon waste can be removed and silicon oxide can be reduced efficiently, and silicon waste can be reused easily and inexpensively. High purity silicon can be produced.
  • the degree of vacuum may be 1.3 ⁇ 10 ⁇ 1 or less.
  • nitrogen gas, argon gas, hydrogen gas, or a mixed gas thereof may be used.
  • the silicon waste is heated at a high temperature by setting the inside of the chamber of the vacuum induction melting furnace to a vacuum degree of 1.3 ⁇ 10 ⁇ 1 to 1.3 ⁇ 10 ⁇ 2 .
  • the heating temperature When the heating temperature is increased by a vacuum induction melting furnace, SiO gas begins to be generated at 1400-1500 ° C. And from about 1800 degreeC, the gas amount resulting from impurity elements, such as Fe, Al, and Ca, increases. Further, the impurity elements include P and B, and the amount of gas resulting from these impurities also increases.
  • the heating temperature is 1850 ° C. or higher. More preferably, the heating temperature is 2000 ° C. or higher.
  • silicon waste mainly composed of SiO or SiO 2 is treated at a high temperature in a vacuum or a non-oxidizing atmosphere to dissolve the silicon waste and produce high-purity silicon. Can do. This high purity silicon is useful as solar cell silicon.
  • a C-based substance or a Ca-based substance may be used as the reducing agent.
  • the reduction effect of silicon waste can be promoted by mixing and dissolving the C-based material or Ca-based material in the silicon waste.
  • the C-based material include carbon powder and silicon carbide.
  • the Ca-based material include calcium oxide, calcium chloride, and calcium carbonate.
  • an inert gas may be sprayed on the surface of the dissolved silicon waste.
  • an inert gas By blowing an inert gas on the surface of the dissolved silicon waste, the slag is concentrated near the surface of the silicon waste. Therefore, by separating this slag portion, higher purity silicon can be generated. .
  • the ingot in which the molten silicon is cooled may be annealed in a hydrogen atmosphere.
  • high-purity silicon can be generated by removing impurities (such as O and N) in silicon waste and reducing silicon oxide.
  • thermoelectric conversion material concerning the 2nd Embodiment of this invention is demonstrated in detail, this invention is not limited only to this embodiment.
  • a silicon waste material is mixed with an iron component, and sintered at a high density in a non-oxidizing atmosphere by a discharge plasma sintering (hereinafter abbreviated as SPS method) method, thereby obtaining a thermoelectric conversion material. Is generated.
  • SPS method discharge plasma sintering
  • the silicon waste is mixed with the iron component such that the Fe to Si elemental ratio is substantially 1: 1.8-3, more preferably the Fe to Si elemental ratio is substantially
  • the silicon waste is mixed with the iron component so as to be 1: 2.
  • a substitution metal element may be included in addition to Fe and Si.
  • the replacement metal element semiconductor properties are imparted by substituting a part of iron or silicon, and Mn, Cr, V, and Al for forming a p-type semiconductor, or an n-type semiconductor Co, Ni, Pt, etc. for When a substitution metal element is included, the element ratio of the substitution metal element is, for example, 0.5 to 10%.
  • the SPS method used in this embodiment is a method in which an on-off DC pulse voltage / current is applied to a green compact, and a sintered body is produced by a discharge phenomenon that occurs in the powder particle gap.
  • Metals, ceramics, and the like can be sintered at high density in a short time and at low temperatures. Sintering is mainly performed by heat generation using graphite as a resistor, but the pulse electric field promotes the movement / diffusion of ions, vacancies and dislocations. Can be sintered. Silicon waste cannot be sintered by conventional methods and has been deposited in landfills or burned in incinerators.
  • silicon waste which has conventionally been difficult to reuse, is sintered by the SPS method without separating the liquid fraction from the solid fraction, thereby obtaining a thermoelectric conversion material easily and inexpensively. be able to.
  • a uniform high-quality sintered body can be easily obtained with uniform pressure by dispersion of discharge points.
  • a sintering aid is not particularly required.
  • a non-oxidizing atmosphere that is any one of vacuum, nitrogen gas, argon gas, hydrogen gas, or a mixed gas thereof is used. This is because by using a non-oxidizing atmosphere, an oxidation reaction is prevented in the process of forming the Fe—Si thermoelectric conversion material, and a reduction reaction occurring in the sintering process is promoted. Due to the reducing action of the graphite part in the SPS method, silicon in silicon waste is highly purified, and a high-quality thermoelectric conversion material can be obtained. In addition, a reduction effect is accelerated
  • silicon waste whose silicon has been purified in advance is mixed with the iron component, and further in the non-oxidizing atmosphere by the SPS method. It may be sintered.
  • a reduction action occurs in the graphite portion of the discharge plasma sintering apparatus, and a high-quality thermoelectric conversion material material can be obtained, and it is not necessary to reduce silicon waste with a reducing agent.
  • a conversion material can be obtained.
  • thermoelectric conversion material having a purity of 70% or more is obtained from oxidized silicon powder having a purity of about 40% by the SPS method, and this high-purity silicon waste and an iron component are mixed, By further sintering with, a high-quality thermoelectric conversion material can be obtained.
  • sintering is performed in a range where the pressure applied in the SPS method is 10 to 100 MPa and the heating / sintering temperature is 500 to 2000 ° C.
  • the pressurizing pressure and the heating / sintering temperature can be freely selected within a suitable range in order to obtain a high-quality thermoelectric conversion material.
  • the silicon wafer production process in the present embodiment includes, for example, a silicon wafer discarded as a nonconforming product in addition to silicon scrap generated by slicing, dicing, grinding and polishing of a silicon ingot or a silicon substrate.
  • the silicon waste is generated by the cleaning process, and may be silicon waste mainly composed of pure water and Si.
  • the cleaning waste liquid contains silicon particles or silicon pieces together with pure water. Conventionally, this cleaning waste liquid has been discarded.
  • this cleaning waste liquid can be used as silicon waste to obtain a low-cost thermoelectric conversion material. If cleaning waste liquid mainly composed of pure water and Si is used, high-purity silicon can be used as a raw material for thermoelectric conversion materials as it is.
  • the silicon waste may be a silicon waste obtained by solid-liquid separation of the slurry waste liquid or the like by centrifugal separation, squeezing separation, sedimentation separation, floating separation, or a combination thereof in addition to the washing waste water.
  • impurities such as glycol and oil are removed to extract silicon, and by using this silicon, a high-quality thermoelectric conversion material can be obtained.
  • the mixture of silicon waste and iron component may be a mixture obtained by solidifying silicon waste with a flocculant containing Fe as a component.
  • the flocculant containing Fe as a component may be any of iron chloride, iron sulfide, or a combination thereof.
  • the flocculant is iron chloride FeCl 2
  • the SiPS contained in the silicon waste reacts with FeCl 2 by rapid heating, holding the temperature for a short time, and quenching by the SPS method, and the non-equilibrium phase And ⁇ -FeSi 2 having a ⁇ phase is produced.
  • a thermoelectric conversion material improves, a thermoelectric conversion material can be obtained simply and inexpensively by utilizing silicon waste.
  • the Fe—Si system has crystal forms such as Fe 3 Si, Fe 2 Si, Fe 5 Si 3 , FeSi, ⁇ -FeSi 2 , and ⁇ -FeSi 2 depending on the composition ratio.
  • ⁇ -FeSi 2 that is stable in a low temperature region exhibits semiconductor characteristics with a forbidden band width of about 0.85 eV, and is suitable as a thermoelectric conversion material.
  • the flocculant FeCl 3 , FeCl 3 , FeS, Fe 2 S 3 , FeS 2 and the like are used in addition to FeCl 2 .
  • thermoelectric conversion material As described above, by using Fe contained in the flocculant as a raw material of the thermoelectric conversion material, silicon waste aggregated with the flocculant can be used as it is, and a process of separately mixing an iron component becomes unnecessary. Therefore, a thermoelectric conversion material can be obtained at low cost.
  • the solidified silicon waste may be sintered by the SPS method without separating the liquid fraction.
  • SiCl 4 is produced as a reaction byproduct.
  • SiCl 4 is a gas component, it does not stay or accumulate in the reaction region, and there is an advantage that the possibility of inhibiting the reaction is small.
  • the mixture of silicon waste and Al component is a mixture of silicon waste solidified with an aggregating agent containing Al.
  • the flocculant containing Al as a component may be any of aluminum oxide, aluminum sulfide, polyaluminum chloride, or a combination thereof.
  • the components of the flocculant Al 2 O 3 , Al 2 (SO 4 ) 3 , [Al 2 (OH n ) Cl 6-n ] m (1 ⁇ n ⁇ 5, m ⁇ 10) and the like are used.
  • thermoelectric conversion material By using Al contained in the flocculant as a replacement metal element when generating a p-type thermoelectric conversion material, a separate Al doping treatment is not required, and the flocculant is agglomerated by the flocculant.
  • the silicon waste can be used as it is, and a thermoelectric conversion material can be obtained at low cost.
  • FIG. 3 shows a basic configuration diagram of the discharge plasma sintering apparatus 10 used in this embodiment.
  • the discharge plasma sintering apparatus 10 applies a pulsed large current at a low voltage while pressing the sample set on the sintering die 9 with the upper punch 7 and the lower punch 8, and generates a discharge plasma generated by a spark discharge phenomenon. Use it for sintering.
  • SPS-520 manufactured by SPS Shintex Co., Ltd.
  • a graphite die having an inner diameter of about 20 mm and a height of 40 mm is used as the sintering die, and a carbon sheet having a thickness of 0.2 mm is used for peeling the sample from the sintering die.
  • the silicon waste recovered from the production process of the silicon wafer is mixed with the iron component so that the Fe to Si element ratio is 1: 2, without separating the liquid fraction from the solid fraction, It was accommodated in a sintered die as it was, pressurized with 40 MPa through a die punch, and further heated with a pulse current to 800 ° C., held for 5 minutes, then turned off and cooled.
  • the degree of vacuum in the sintering chamber during sintering was about 3 Pa.
  • thermoelectric conversion material according to the present invention is produced by performing rapid heating, short-time temperature holding, and rapid cooling on a mixture of silicon and Fe by a discharge plasma sintering method. By using waste, a thermoelectric conversion material can be obtained simply and inexpensively.

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  • Organic Chemistry (AREA)
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Abstract

L'invention porte sur un silicium haute qualité obtenu par élimination d'impuretés à partir de déchet de silicium et par réduction de l'oxyde de silicium afin de réutiliser facilement le déchet de silicium à un coût raisonnable. Le silicium haute qualité est produit par frittage à haute densité du déchet de silicium par le procédé de frittage par décharge plasma, dans une atmosphère non oxydante.
PCT/JP2009/005569 2008-11-12 2009-10-22 Silicium haute qualité et matière de conversion thermoélectrique WO2010055615A1 (fr)

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JP2013007102A (ja) * 2011-06-24 2013-01-10 Naoetsu Electronics Co Ltd 鉄シリコン合金の製造方法
JP2014111519A (ja) * 2012-11-12 2014-06-19 Panasonic Corp シリコンリサイクルシステム及びその方法
KR101448281B1 (ko) 2011-10-24 2014-10-13 (주)태원시스켐 알루미늄 합금용 실리콘 성형체 및 그 제조방법
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JP2013007102A (ja) * 2011-06-24 2013-01-10 Naoetsu Electronics Co Ltd 鉄シリコン合金の製造方法
KR101448281B1 (ko) 2011-10-24 2014-10-13 (주)태원시스켐 알루미늄 합금용 실리콘 성형체 및 그 제조방법
JP2014111519A (ja) * 2012-11-12 2014-06-19 Panasonic Corp シリコンリサイクルシステム及びその方法
DE102018200483B3 (de) * 2018-01-12 2019-03-21 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Thermoelektrisches Material und Verfahren zur Herstellung eines thermoelektrischen Materials sowie Verwendung dieses Materials in einem Thermogenerator
WO2019137953A2 (fr) 2018-01-12 2019-07-18 Leibniz-Institut Für Festkörper- Und Werkstoffforschung Dresden E.V. Matériau thermoélectrique et procédé de fabrication d'un matériau thermoélectrique
WO2019137953A3 (fr) * 2018-01-12 2019-11-28 Leibniz-Institut Für Festkörper- Und Werkstoffforschung Dresden E.V. Matériau thermoélectrique et procédé de fabrication d'un matériau thermoélectrique

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