NO179442B - Process for making silicon carbide powder - Google Patents
Process for making silicon carbide powder Download PDFInfo
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- NO179442B NO179442B NO913515A NO913515A NO179442B NO 179442 B NO179442 B NO 179442B NO 913515 A NO913515 A NO 913515A NO 913515 A NO913515 A NO 913515A NO 179442 B NO179442 B NO 179442B
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- Prior art keywords
- silicon dioxide
- silicon carbide
- soot
- acid
- carbon
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- 238000000034 method Methods 0.000 title claims description 24
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims description 16
- 230000008569 process Effects 0.000 title description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 47
- 235000012239 silicon dioxide Nutrition 0.000 claims description 24
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 19
- 239000000377 silicon dioxide Substances 0.000 claims description 18
- 229910052799 carbon Inorganic materials 0.000 claims description 17
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 17
- 239000004071 soot Substances 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 12
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 10
- -1 hexafluorosilicic acid Chemical compound 0.000 claims description 7
- 238000000227 grinding Methods 0.000 claims description 6
- 229910021529 ammonia Inorganic materials 0.000 claims description 5
- 239000006004 Quartz sand Substances 0.000 claims description 4
- 239000002253 acid Substances 0.000 claims description 4
- 239000006229 carbon black Substances 0.000 claims description 4
- 238000001694 spray drying Methods 0.000 claims description 3
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims description 2
- 229910021486 amorphous silicon dioxide Inorganic materials 0.000 claims 1
- 150000002736 metal compounds Chemical class 0.000 claims 1
- 239000011541 reaction mixture Substances 0.000 claims 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 239000000047 product Substances 0.000 description 6
- IRPGOXJVTQTAAN-UHFFFAOYSA-N 2,2,3,3,3-pentafluoropropanal Chemical compound FC(F)(F)C(F)(F)C=O IRPGOXJVTQTAAN-UHFFFAOYSA-N 0.000 description 4
- KLZUFWVZNOTSEM-UHFFFAOYSA-K Aluminum fluoride Inorganic materials F[Al](F)F KLZUFWVZNOTSEM-UHFFFAOYSA-K 0.000 description 4
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 4
- 229910052731 fluorine Inorganic materials 0.000 description 4
- 239000011737 fluorine Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 238000010422 painting Methods 0.000 description 4
- 239000000725 suspension Substances 0.000 description 4
- 239000000654 additive Substances 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 3
- 125000005624 silicic acid group Chemical class 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 238000000815 Acheson method Methods 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 239000002518 antifoaming agent Substances 0.000 description 2
- 239000007900 aqueous suspension Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000012065 filter cake Substances 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002667 nucleating agent Substances 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 239000002006 petroleum coke Substances 0.000 description 2
- 229920002635 polyurethane Polymers 0.000 description 2
- 239000004814 polyurethane Substances 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910003638 H2SiF6 Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 239000000806 elastomer Substances 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000007591 painting process Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000001698 pyrogenic effect Effects 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- ZEFWRWWINDLIIV-UHFFFAOYSA-N tetrafluorosilane;dihydrofluoride Chemical compound F.F.F[Si](F)(F)F ZEFWRWWINDLIIV-UHFFFAOYSA-N 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- GPRLSGONYQIRFK-MNYXATJNSA-N triton Chemical compound [3H+] GPRLSGONYQIRFK-MNYXATJNSA-N 0.000 description 1
- 230000007306 turnover Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Classifications
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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
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
- C01B33/186—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof from or via fluosilicic acid or salts thereof by a wet process
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/90—Carbides
- C01B32/914—Carbides of single elements
- C01B32/956—Silicon carbide
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/90—Carbides
- C01B32/914—Carbides of single elements
- C01B32/956—Silicon carbide
- C01B32/963—Preparation from compounds containing silicon
- C01B32/97—Preparation from SiO or SiO2
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Description
Foreliggende oppfinnelse angår en fremgangsmåte for fremstilling av p-silisiumkarbid av kiselsyre og karbon. The present invention relates to a method for producing p-silicon carbide from silicic acid and carbon.
Silisiumkarbid har i mange tiår i det vesentlige vært ufor-andret fremstilt ifølge Acheson-fremgangsmåten av silisiumdioksyd i form av kvartssand og karbon i form av petroleumkoks i elektrisk motstandsovn ved temperaturer over 2000°C. Det pro-dukt som oppnås på denne måte er i grove stykker, og må alt etter anvendelsesformål knuses i større eller mindre grad. For anvendelse som sinterpulver for fremstilling av silisiumkarbid-keramikk, som er en anvendelse med stadig større betydning, er det nødvendig med ekstremt fin maling, noe som krever mye energi og anvendelse av kostbare apparater. Ytterligere ulemper med Acheson-fremgangsmåten er begrunnet i at de nødvendige ovner må være svært store for å muliggjøre økonomisk lønnsomt arbeide, og utbyttet for en ovnsbehandling ligger bare i størrelsesorden 20%, slik at en stor del av det tilførte materiale må resirku-leres. Acheson-fremgangsmåten gir dessuten den heksagonale høy-temperatur-modifikasjon av silisiumkarbidet, som oftest betegnet som oc-modifikasjon, mens den for visse anvendelser foretrukne kubiske lavtemperatur-modifikasjon, vanligvis betegnet som P-modifikasjon, ikke er tilgjengelig ved hjelp av denne fremgangsmåte. For many decades, silicon carbide has essentially been produced unchanged according to the Acheson method from silicon dioxide in the form of quartz sand and carbon in the form of petroleum coke in an electric resistance furnace at temperatures above 2000°C. The product obtained in this way is in rough pieces, and must be crushed to a greater or lesser extent depending on the intended use. For application as a sinter powder for the production of silicon carbide ceramics, which is an application of increasing importance, extremely fine paint is required, which requires a lot of energy and the use of expensive apparatus. Further disadvantages of the Acheson method are based on the fact that the necessary furnaces must be very large to enable economically profitable work, and the yield for a furnace treatment is only in the order of 20%, so that a large part of the added material must be recycled. The Acheson process also provides the hexagonal high-temperature modification of the silicon carbide, most commonly referred to as oc-modification, while the low-temperature cubic modification, commonly referred to as P-modification, preferred for certain applications, is not available by this process.
For fremstilling av p-silisiumkarbid er likeledes fremgangsmåter som tar utgangspunkt i silisiumdioksyd og karbon kjente. Reaktantene må for dette formål være findelte og grundig blandet. Reaksjonstemperaturen ligger vanligvis under 1800°C, idet reaksjonshastigheten forhøyes ved tilsetning av findelt 3-Sic som kimdanner og/eller metaller eller metalloksyder, og produktets kornstørrelse minskes. Som silisiumdioksyd ble så vel finmalt kvarts som også utfelte kiselsyrer eller pyrogen kiselsyre anvendt. Som karbon ble eksempelvis petroleumkoks eller sot anvendt. Finmalingen av kvarts er imidlertid svært energi-krevende og partikkelstørrelser under 1 jjm, som er ønskelig for fremstillingen av silisiumkarbid, kan bare oppnås med høye kostnader. Ved anvendelse av utfelte kiselsyrer, slik de f.eks. er beskrevet i US-patent nr. 4 377 563, eller pyrogen kiselsyre, vanskeliggjør derimot de spesifikke egenskaper for disse produkter den tekniske gjennomføring, fordi disse produkter på grunn av den utpregede fortykningsvirkning bare med dårlig resultat kan bearbeides i vandige suspensjoner. For blanding, desagglomerering eller spraytørking er imidlertid dannelsen av suspensjoner med høyt faststoffinnhold og lav viskositet ønskelig eller nødvendig. En ytterligere ulempe ved de pyrogene kiselsyrer er den relativt høye pris. For the production of p-silicon carbide, methods based on silicon dioxide and carbon are also known. For this purpose, the reactants must be finely divided and thoroughly mixed. The reaction temperature is usually below 1800°C, as the reaction rate is increased by the addition of finely divided 3-Sic as nucleating agent and/or metals or metal oxides, and the grain size of the product is reduced. Finely ground quartz as well as precipitated silicic acids or fumed silicic acid were used as silicon dioxide. For example, petroleum coke or carbon black was used as carbon. However, the fine grinding of quartz is very energy-demanding and particle sizes below 1 jjm, which are desirable for the production of silicon carbide, can only be achieved at high costs. When using precipitated silicic acids, as they e.g. is described in US patent no. 4,377,563, or fumed silicic acid, on the other hand, the specific properties of these products make technical implementation difficult, because these products can only be processed in aqueous suspensions with poor results due to the pronounced thickening effect. However, for mixing, deagglomeration or spray drying, the formation of high solids and low viscosity suspensions is desirable or necessary. A further disadvantage of the pyrogenic silicic acids is the relatively high price.
Det var derfor foreliggende oppfinnelses oppgave å tilveie-bringe en fremgangsmåte for fremstilling av P-silisiumkarbid som har utgangspunkt i et rimelig silisiumdioksyd med gunstig par-tikkelstørrelse og gode bearbeidingsegenskaper. Ifølge oppfinnelsen løses denne oppgave ifølge fremgangsmåten i patentkrav 1. It was therefore the task of the present invention to provide a method for the production of P-silicon carbide which is based on a reasonable silicon dioxide with a favorable particle size and good processing properties. According to the invention, this task is solved according to the method in patent claim 1.
Det ble funnet at det amorfe silisiumdioksyd som oppstår ved fremstilling av aluminiumfluorid fra heksafluor-kiselsyre og aluminiumhydroksyd ifølge reaksjonsligningen It was found that the amorphous silica resulting from the preparation of aluminum fluoride from hexafluorosilicic acid and aluminum hydroxide according to the reaction equation
H2SiF6 + 2A1(0H)3 2A1F3 + Si02<+> 4H20 H2SiF6 + 2A1(0H)3 2A1F3 + Si02<+> 4H20
ikke bare har en gunstig partikkelstørrelse som muliggjør en hurtig omsetning med karbon, men også danner vandige suspensjoner med faststoffinnhold inntil over 40 vekt% ved lav viskositet. not only has a favorable particle size which enables a rapid reaction with carbon, but also forms aqueous suspensions with a solids content of up to over 40% by weight at low viscosity.
Silisiumdioksydet utgjør et avfallsprodukt ved den indu-strielle aluminiumfluorid-produksjon, og er derfor svært rimelig og tilgjengelig i store mengder. Utvinningen i laboratoriemåle-stokk er eksempelvis beskrevet i US-patent nr. 4 693 878 (eksempel 1) . Silicon dioxide is a waste product of industrial aluminum fluoride production, and is therefore very affordable and available in large quantities. The extraction in a laboratory measuring stick is described, for example, in US patent no. 4,693,878 (example 1).
For fremstilling av p-silisiumkarbid er det hensiktsmessig å vaske silisiumdioksydet med syre for å minske innholdet av aluminium til uskadelige verdier, for på denne måte å gjøre en etterfølgende syrebehandling av silisiumkarbidet for dette formål unødvendig. Som vaskevæske kan den heksafluor-kiselsyre som likevel trenges for aluminiumfluorid-fremstillingen anvendes; det kan imidlertid også anvendes andre syrer, som eksempelvis saltsyre. Spesielle tiltak for videre reduksjon av fluorinnholdet er ikke nødvendig, fordi fluor unnviker ved de temperaturer som er nødvendige for silisiumkarbid-fremstillingen; det kan imidlertid være fordelaktig å fjerne fluor allerede før den videre omsetning, slik. det er beskrevet i US-patent nr. 4 693 878. For the production of p-silicon carbide, it is appropriate to wash the silicon dioxide with acid to reduce the aluminum content to harmless values, in this way making a subsequent acid treatment of the silicon carbide for this purpose unnecessary. As a washing liquid, the hexafluorosilicic acid which is nevertheless needed for the production of aluminum fluoride can be used; however, other acids can also be used, such as, for example, hydrochloric acid. Special measures for further reduction of the fluorine content are not necessary, because fluorine escapes at the temperatures necessary for silicon carbide production; however, it may be advantageous to remove fluorine already before the further turnover, like this. it is described in US Patent No. 4,693,878.
I fremgangsmåten ifølge oppfinnelsen er det hensiktsmessig å anvende sot som karbonkilde, og fortrinnsvis gass-sot eller ovnssot. For fjerning av metallspor blir ovnssoten fortrinnsvis vasket, slik at det på denne måte ikke føres inn noen forurensninger i sluttproduktet. In the method according to the invention, it is appropriate to use soot as a carbon source, and preferably gas soot or furnace soot. To remove metal traces, the furnace soot is preferably washed, so that in this way no contaminants are introduced into the final product.
I en foretrukket utførelsesform av fremgangsmåten ifølge oppfinnelsen males, hhv. desagglomereres, det vaskede silisiumdioksyd først i en røreverks-kulemølle eller i en attritor. Som malevæske anvendes fortrinnsvis vann, og som malelegemer fortrinnsvis legemer av silisiumdioksyd, eksempelvis kuler av kvartsglass eller avrundet kvartssand. Som spesielt fordelaktig har en kvartssand som er kjent under navnet "Ottawasand", med en kornstørrelse på ca. 1 mm vist seg å være. In a preferred embodiment of the method according to the invention, paint, or is deagglomerated, the washed silica first in a mixer ball mill or in an attritor. Water is preferably used as the painting liquid, and bodies of silicon dioxide, for example spheres of quartz glass or rounded quartz sand, are preferably used as the painting bodies. As particularly advantageous, a quartz sand known under the name "Ottawasand" with a grain size of approx. 1 mm turned out to be.
For å unngå forurensninger på grunn av metallavslipinger, anvendes fortrinnsvis en røreverks-kulemølle, hhv. en attritor med elastomerkledning, eksempelvis av polyuretan. Ved denne maleprosess, hhv. desagglomereringsprosess, tilsettes allerede med fordel det P-silisiumkarbidpulver som er nødvendig for kimdannelse. Det er også på dette sted mulig å føre inn tilset-ninger, som eksempelvis sintringshjelpemidler for den senere anvendelse av silisiumkarbidet fremstilt ifølge oppfinnelsen. To avoid contamination due to metal scrapings, a mixer ball mill is preferably used, or an attritor with an elastomer coating, for example made of polyurethane. In this painting process, respectively deagglomeration process, the P-silicon carbide powder which is necessary for nucleation is already advantageously added. It is also possible at this point to introduce additives, such as, for example, sintering aids for the later use of the silicon carbide produced according to the invention.
Videre kan det for å lette male-, hhv. desagglomerings-prosessen, tilsettes vanlige hjelpestoffer, spesielt væskedan-nende stoffer og antiskummidler. Furthermore, to facilitate painting, or the deagglomeration process, common auxiliaries are added, especially liquid-forming substances and antifoam agents.
Karbonet, fortrinnsvis i form av gass-sot eller ovnssot, tilsettes med fordel likeledes røreverks-kulemøllen, hhv. attritoren, for å oppnå en optimal blanding. Deretter avvannes suspensjonen ifølge en av de kjente metoder og anbringes i en form som er egnet for omsetning til silisiumkarbid. The carbon, preferably in the form of gas soot or furnace soot, is advantageously also added to the mixer ball mill, respectively. the attritor, to achieve an optimal mixture. The suspension is then dewatered according to one of the known methods and placed in a form suitable for conversion to silicon carbide.
Fortrinnsvis gjennomføres awanningen ved spraytørking, hvoretter det eventuelt kan gjennomføres en granulering dersom det ønskes enda grovere agglomerater. Dewatering is preferably carried out by spray drying, after which a granulation can possibly be carried out if even coarser agglomerates are desired.
Reaksjonen kan i prinsippet gjennomføres i enhver ovn som tillater de nødvendige temperaturer og oppholdstider. I labora-toriemålestokk kan dette være en digel- eller muffelovn, i indu-striell målestokk er eksempelvis sjaktovner, roterovner eller virvelsjiktovner egnede. Spesielt fordelaktig er roterovner, fordi de muliggjør en tilstrekkelig varmeoverføring uten hjelpe-medium. Reaksjonstemperaturene og oppholdstidene er kjent fra teknikken, og ligger eksempelvis ved 1500 - 1800<*>C og i størrel-sesorden 1 time. In principle, the reaction can be carried out in any oven that allows the necessary temperatures and residence times. On a laboratory scale, this can be a crucible or muffle furnace, on an industrial scale, for example, shaft furnaces, rotary furnaces or fluidized bed furnaces are suitable. Rotary kilns are particularly advantageous, because they enable sufficient heat transfer without an auxiliary medium. The reaction temperatures and residence times are known from the art, and are, for example, at 1500 - 1800<*>C and in the order of 1 hour.
Etter reaksjonen er det ofte nødvendig å fjerne overskuddet av karbon. For dette formål eksisterer det flere i og for seg kjente fremgangsmåter. After the reaction, it is often necessary to remove the excess carbon. For this purpose, there are several methods known per se.
Det er f.eks. mulig å forbrenne karbonet ved oppvarming i nærvær av oksygen, eller å omsette karbonet med hydrogen under trykk ved 600 - 1400°C under dannelse av metan. Fortrinnsvis fjernes karbonet ved behandling med ammoniakk ved 800 - 1400°C, spesielt foretrukket ved 1000 - 1200°C (F.K. van Dijen, J. Pluijmakers, J. Eur. Ceram. Soc. 5, 385 (1989) og den litteratur som der er sitert). It is e.g. possible to burn the carbon by heating in the presence of oxygen, or to react the carbon with hydrogen under pressure at 600 - 1400°C with the formation of methane. Preferably, the carbon is removed by treatment with ammonia at 800 - 1400°C, particularly preferably at 1000 - 1200°C (F.K. van Dijen, J. Pluijmakers, J. Eur. Ceram. Soc. 5, 385 (1989) and the literature which there is cited).
Ved fremgangsmåten ifølge oppfinnelsen gjennomføres behandlingen med ammoniakk fortrinnsvis i en virvelsjiktovn, fordi det i ovner av denne type er sikret en optimal vekselvirkning mellom gass og faststoff, samt god varmeovergang. In the method according to the invention, the treatment with ammonia is preferably carried out in a fluidized bed furnace, because in furnaces of this type an optimal interaction between gas and solid is ensured, as well as good heat transfer.
Etter fjerningen av det overskytende karbon, anvendes produktet videre som sådant, eller det underkastes enda en male- og desagglomereringsprosess. For dette anvendes igjen fortrinnsvis en røreverks-kulemølle eller en attritor. Som malelegemer anvendes fortrinnsvis silisiumkarbidkuler for ikke å bringe inn fremmede substanser på grunn av den uunngåelige abrasjon. Av samme grunn fores attritoren fortrinnsvis med plastmateriale eller (SiC)-keramikk. Som væske kan det anvendes såvel vann som en organisk væske, som f.eks. isopropanol eller heptan. Ved denne maling, hhv. desagglomerering, kan også til-setninger for den senere anvendelse av silisiumkarbidpulveret, f.eks. sintringsadditiver, tilsettes. After the removal of the excess carbon, the product is further used as such, or it is subjected to a further grinding and deagglomeration process. For this, again, a mixer ball mill or an attritor is preferably used. Silicon carbide balls are preferably used as grinding bodies in order not to introduce foreign substances due to the inevitable abrasion. For the same reason, the attritor is preferably lined with plastic material or (SiC) ceramics. Both water and an organic liquid, such as e.g. isopropanol or heptane. With this painting, respectively deagglomeration, additions for the later use of the silicon carbide powder, e.g. sintering additives, are added.
De følgende eksempler tydeliggjør gjennomføringen av fremgangsmåten ifølge oppfinnelsen. The following examples clarify the implementation of the method according to the invention.
Eksempel 1: Rensing av utganqsmaterialet Example 1: Purification of the starting material
a) S i1is iumdioksyd: a) S i1is ium dioxide:
Urent silisiumdioksydpulver fra aluminiumfluorid-produk-sjonen ble først omrørt ved 95°C i 4 timer med en fortynnet (0,6 vekt%) heksafluor-kiselsyre (6 1 på 1 kg silisiumdioksyd) og deretter filtert fra. Filterkaken ble vasket med avsaltet vann (10 1 på 1 kg silisiumdioksyd) og tørket. Aluminiuminnholdet ble ved denne behandling redusert fra 1,5 vekt% til 130 ppm og fluorinnholdet fra 4,5 vekt% til 3,3 vekt%. Pulverets spesifikke overflate utgjorde 3 m<2>/g, Impure silicon dioxide powder from aluminum fluoride production was first stirred at 95°C for 4 hours with a diluted (0.6% by weight) hexafluorosilicic acid (6 1 on 1 kg of silicon dioxide) and then filtered off. The filter cake was washed with desalted water (10 1 on 1 kg of silicon dioxide) and dried. The aluminum content was reduced by this treatment from 1.5% by weight to 130 ppm and the fluorine content from 4.5% by weight to 3.3% by weight. The specific surface area of the powder was 3 m<2>/g,
agglomeratstørrelsen <0,1 mm. the agglomerate size <0.1 mm.
b) Ovnssot: b) Furnace soot:
Ovnssot av vanlig handelstype (Elftex® 470) ble omrørt ved Oven soot of the usual commercial type (Elftex® 470) was stirred with wood
90°C i 60 minutter med en fortynnet (0,6 vekt%) vandig heksafluor-kiselsyre (6 1 på 1 kg sot) og deretter filtrert fra. Filterkaken ble vasket med avsaltet vann (5 1 på 1 kg sot) og tørket. Metallinnholdet kunne ved denne behandling senkes fra 2 000 ppm til 100 ppm. 90°C for 60 minutes with a dilute (0.6% by weight) aqueous hexafluorosilicic acid (6 L on 1 kg of carbon black) and then filtered off. The filter cake was washed with desalted water (5 l on 1 kg of soot) and dried. With this treatment, the metal content could be lowered from 2,000 ppm to 100 ppm.
Eksempel 2; Fremstilling av e- SiC Example 2; Production of e-SiC
10,5 kg vasket silisiumdioksyd fra eksempel 1 ble malt med 0,5 kg 3-SiC-pulver (som kimdanner), 0,5 kg Triton XD-100 (fly-tendegjøringsmiddel), 0,1 kg silikon-antiskummiddel og 0,4 kg polyvinylalkohol (bindemiddel), i 25 1 avsaltet vann i en røre-verks-kulemølle som var foret med polyuretan, med malemiddel Ottawasand (0,8 - 1,1 mm) i 20 minutter (effektiv maletid). 10.5 kg of washed silica from Example 1 was milled with 0.5 kg of 3-SiC powder (as nucleating agent), 0.5 kg of Triton XD-100 (flying agent), 0.1 kg of silicone antifoam and 0. 4 kg of polyvinyl alcohol (binder), in 25 l of desalted water in an agitator ball mill which was lined with polyurethane, with grinding agent Ottawasand (0.8 - 1.1 mm) for 20 minutes (effective grinding time).
Deretter ble det tilblandet 6,9 kg gass-sot (Printex® U) og malt videre i 15 minutter. Etter fraskilling av sanden gjennom en filterpatron, ble suspensjonen spraytørket, slik at det ble oppnådd et granulat med en midlere kornstørrelse på 0,4 mm og 2% restfuktighet. Granulatet ble fylt i en grafitt-digel med en diameter på 50 mm og oppvarmet i 60 minutter i argonatmosfære på 1700°C. Then 6.9 kg of gas-soot (Printex® U) was mixed in and ground further for 15 minutes. After separating the sand through a filter cartridge, the suspension was spray-dried, so that a granule with an average grain size of 0.4 mm and 2% residual moisture was obtained. The granulate was filled in a graphite crucible with a diameter of 50 mm and heated for 60 minutes in an argon atmosphere at 1700°C.
Etter avkjølingen ble silisiumkarbidpulveret oppvarmet i en virvelsjikt-ovn med ammoniakk i 5 timer på 1100"C for å fjerne det resterende karbon. After cooling, the silicon carbide powder was heated in a fluidized bed furnace with ammonia for 5 hours at 1100°C to remove the remaining carbon.
Det på denne måte oppnådde silisiumkarbidpulver oppviste følgende egenskaper: The silicon carbide powder obtained in this way exhibited the following properties:
Eksempel 3 Example 3
En suspensjon av 10,5 g vasket silisiumdioksyd og de til-setninger som ble beskrevet i eksempel 2 ble malt i 15 1 avsaltet vann, som beskrevet i eksempel 2, i 20 minutter i en røreverks-kulemølle. Deretter ble 6,6 kg ovnssot (Elftex 470), vasket ifølge eksempel 1, og 10 1 avsaltet vann innblandet. De ytterligere trinn fant sted som beskrevet i eksempel 2. A suspension of 10.5 g of washed silicon dioxide and the additives described in Example 2 was ground in 15 l of desalted water, as described in Example 2, for 20 minutes in an agitator ball mill. Then 6.6 kg of oven soot (Elftex 470), washed according to example 1, and 10 1 of desalted water were mixed in. The further steps took place as described in Example 2.
Det på denne måte oppnådde silisiumkarbidpulver hadde følgende egenskaper: The silicon carbide powder obtained in this way had the following properties:
Claims (10)
Applications Claiming Priority (1)
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CH291990 | 1990-09-07 |
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NO913515D0 NO913515D0 (en) | 1991-09-06 |
NO913515L NO913515L (en) | 1992-03-09 |
NO179442B true NO179442B (en) | 1996-07-01 |
NO179442C NO179442C (en) | 1996-10-09 |
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NO913515A NO179442C (en) | 1990-09-07 | 1991-09-06 | Process for making silicon carbide powder |
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EP (1) | EP0476422B1 (en) |
JP (1) | JPH04270106A (en) |
CA (1) | CA2050705A1 (en) |
DE (1) | DE59102334D1 (en) |
ES (1) | ES2059003T3 (en) |
NO (1) | NO179442C (en) |
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KR960025373A (en) | 1994-12-12 | 1996-07-20 | 하라다 야스오 | High density magnetic recording media |
KR101940351B1 (en) * | 2011-08-24 | 2019-01-18 | 다이헤이요 세멘토 가부시키가이샤 | Silicon carbride powder and method for producing same |
KR20130085841A (en) * | 2012-01-20 | 2013-07-30 | 엘지이노텍 주식회사 | Silicon carbide powder and method for manufacturing the same |
DE102022102320A1 (en) | 2022-02-01 | 2023-08-03 | The Yellow SiC Holding GmbH | Device and method for the production of silicon carbide |
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US4693878A (en) * | 1986-06-11 | 1987-09-15 | Swiss Aluminium Ltd. | Process for the production of soluble alkali silicates |
NL8802117A (en) * | 1988-08-27 | 1990-03-16 | Stamicarbon | Method for preparing silicon-containing powders with a high level of purity |
NL8802116A (en) * | 1988-08-27 | 1990-03-16 | Stamicarbon | Method for removing free carbon and/or metal oxide from ceramic material |
-
1991
- 1991-09-03 EP EP91114866A patent/EP0476422B1/en not_active Expired - Lifetime
- 1991-09-03 ES ES91114866T patent/ES2059003T3/en not_active Expired - Lifetime
- 1991-09-03 DE DE59102334T patent/DE59102334D1/en not_active Expired - Fee Related
- 1991-09-04 JP JP3223929A patent/JPH04270106A/en active Pending
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NO179442C (en) | 1996-10-09 |
ES2059003T3 (en) | 1994-11-01 |
JPH04270106A (en) | 1992-09-25 |
NO913515L (en) | 1992-03-09 |
CA2050705A1 (en) | 1992-03-08 |
DE59102334D1 (en) | 1994-09-01 |
EP0476422A1 (en) | 1992-03-25 |
NO913515D0 (en) | 1991-09-06 |
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