NO178999B - Process for reducing carbon pollutants in finely divided ceramic powders - Google Patents
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- NO178999B NO178999B NO901302A NO901302A NO178999B NO 178999 B NO178999 B NO 178999B NO 901302 A NO901302 A NO 901302A NO 901302 A NO901302 A NO 901302A NO 178999 B NO178999 B NO 178999B
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- 239000000843 powder Substances 0.000 title claims description 42
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims description 41
- 229910052799 carbon Inorganic materials 0.000 title claims description 40
- 238000000034 method Methods 0.000 title claims description 32
- 239000000919 ceramic Substances 0.000 title claims description 21
- 239000003344 environmental pollutant Substances 0.000 title description 2
- 231100000719 pollutant Toxicity 0.000 title description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 23
- 239000000203 mixture Substances 0.000 claims description 11
- 229910010293 ceramic material Inorganic materials 0.000 claims description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 9
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 8
- 239000011521 glass Substances 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 150000002739 metals Chemical class 0.000 claims description 5
- 150000004767 nitrides Chemical class 0.000 claims description 5
- 229910000069 nitrogen hydride Inorganic materials 0.000 claims description 5
- 238000007669 thermal treatment Methods 0.000 claims description 5
- 239000001257 hydrogen Substances 0.000 claims description 4
- 229910052739 hydrogen Inorganic materials 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 4
- 239000011261 inert gas Substances 0.000 claims description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 3
- 150000001247 metal acetylides Chemical class 0.000 claims description 3
- 229910052752 metalloid Inorganic materials 0.000 claims description 3
- 150000002738 metalloids Chemical class 0.000 claims description 3
- 238000011282 treatment Methods 0.000 claims description 3
- QYEXBYZXHDUPRC-UHFFFAOYSA-N B#[Ti]#B Chemical compound B#[Ti]#B QYEXBYZXHDUPRC-UHFFFAOYSA-N 0.000 claims description 2
- 229910033181 TiB2 Inorganic materials 0.000 claims description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 2
- 229910008322 ZrN Inorganic materials 0.000 claims description 2
- 229910052718 tin Inorganic materials 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
- 229910044991 metal oxide Inorganic materials 0.000 claims 1
- 150000004706 metal oxides Chemical class 0.000 claims 1
- 239000006069 physical mixture Substances 0.000 claims 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 9
- 230000003647 oxidation Effects 0.000 description 9
- 238000007254 oxidation reaction Methods 0.000 description 9
- 239000001301 oxygen Substances 0.000 description 9
- 229910052760 oxygen Inorganic materials 0.000 description 9
- 239000000126 substance Substances 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 238000005245 sintering Methods 0.000 description 6
- 229910021529 ammonia Inorganic materials 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 229910010271 silicon carbide Inorganic materials 0.000 description 5
- 230000001590 oxidative effect Effects 0.000 description 4
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 4
- 238000011109 contamination Methods 0.000 description 3
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000005121 nitriding Methods 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 238000007873 sieving Methods 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 150000004678 hydrides Chemical class 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910001510 metal chloride Inorganic materials 0.000 description 1
- 229910052987 metal hydride Inorganic materials 0.000 description 1
- 229910052756 noble gas Inorganic materials 0.000 description 1
- 150000002835 noble gases Chemical class 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 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
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
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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
- C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
- C01B13/14—Methods for preparing oxides or hydroxides in general
- C01B13/16—Purification
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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
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
- C01B21/0615—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with transition metals other than titanium, zirconium or hafnium
- C01B21/062—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with transition metals other than titanium, zirconium or hafnium with chromium, molybdenum or tungsten
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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
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
- C01B21/068—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with silicon
- C01B21/0685—Preparation by carboreductive nitridation
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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
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
- C01B21/072—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with aluminium
- C01B21/0726—Preparation by carboreductive nitridation
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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
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/082—Compounds containing nitrogen and non-metals and optionally metals
- C01B21/0828—Carbonitrides or oxycarbonitrides of metals, boron or silicon
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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
- C01B32/00—Carbon; Compounds thereof
- C01B32/90—Carbides
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- 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
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- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B35/00—Boron; Compounds thereof
- C01B35/02—Boron; Borides
- C01B35/04—Metal borides
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- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
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- C01P2006/80—Compositional purity
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- Organic Chemistry (AREA)
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- Crystallography & Structural Chemistry (AREA)
- Ceramic Products (AREA)
- Compositions Of Oxide Ceramics (AREA)
- Carbon And Carbon Compounds (AREA)
Description
Foreliggende oppfinnelse vedrører en fremgangsmåte for reduksjon av karbonforurensninger i finfordelte pulvere av keramisk materiale eller blandinger av pulvere av keramiske materialer med elementært karbon. The present invention relates to a method for reducing carbon pollution in finely divided powders of ceramic material or mixtures of powders of ceramic materials with elemental carbon.
Finfordelte keramiske pulvere er på grunn av deres høye sinteraktivitet intressante som utgangsstoffer for fremstilling av formgitte keramiske gjenstander, hvorved et stort antall anvendelser er omfattet både innenfor konstruksjons-keramiske materialer og også innenfor bio- og elektrokera-mikk. Ved mange av disse anvendelsene er høy renhet for de keramiske materialene nødvendig for å sikre de påkrevde fysikalske eller kjemiske egenskapene. Due to their high sintering activity, finely divided ceramic powders are interesting as starting materials for the production of shaped ceramic objects, whereby a large number of applications are included both within construction ceramic materials and also within bio- and electroceramics. In many of these applications, high purity of the ceramic materials is necessary to ensure the required physical or chemical properties.
Ved de ikke-oksydiske keramiske materialene er, ved siden av metalliske forurensninger, innhold av karbon og oksygen av sentral betydning. Følgelig er det beskrevet at sintringsevnen tydelig avtar med økende karboninnhold i Si3N4~pulveret (H. Hausner, R. Petsch, "Keramische Komponenten fur Fahrzeug-Gasturbinen III", statusseminar etter oppdrag av Bundes-ministerium fur Forschung und Technologie, 44-54, Springer-verlag, Berlin, 1989). Også høytemperatur-oksydasjons-bestandigheten for S13N4-materialer påvirkes i negativ retning, og reduseres sterkt ved karbonforurensninger (H. Knoch, G. E. Gatzer, Journal of the American Ceramic Society 62 (11-12), 634-635, 1979). In the case of the non-oxidative ceramic materials, next to metallic impurities, the content of carbon and oxygen is of central importance. Consequently, it has been described that the sintering ability clearly decreases with increasing carbon content in the Si3N4 powder (H. Hausner, R. Petsch, "Keramische Komponenten fur Fahrzeug-Gasturbinen III", status seminar commissioned by the Bundes-ministerium fur Forschung und Technologie, 44-54, Springer Verlag, Berlin, 1989). The high-temperature oxidation resistance of S13N4 materials is also adversely affected, and greatly reduced by carbon impurities (H. Knoch, G. E. Gatzer, Journal of the American Ceramic Society 62 (11-12), 634-635, 1979).
For fremstillingen av slike keramiske materialer kan de anvendte sinterpulverne fremstilles ved forskjellige kjemiske fremgangsmåter. Ved teknisk relevante fremgangsmåter går man for det meste ut fra metallene eller deres oksyder. Ved disse prosessene kan en karbonforurensning av produktet ikke unngås. Ved karbonforurensning av de metalliske råstoffene, anvendelsen av karbon eller karbonholdige materialer for reduksjon av oksydene, f.eks. ved karbotermisk nitridering eller karborering, anvendelsen av karbonholdige bindemidler eller via forurensninger fra atmosfæren, som f.eks. i de anvendte høytemperaturovnene med grafitt-varmeelementer eller ved anvendelsen av grafitt-oppvarmingsbeholdere, Innføres karbon i det keramiske pulveret. For the production of such ceramic materials, the sinter powders used can be produced by various chemical methods. For technically relevant methods, the starting point is mostly the metals or their oxides. During these processes, carbon contamination of the product cannot be avoided. In the case of carbon contamination of the metallic raw materials, the use of carbon or carbon-containing materials to reduce the oxides, e.g. by carbothermic nitriding or carboring, the use of carbon-containing binders or via pollutants from the atmosphere, such as e.g. in the used high-temperature furnaces with graphite heating elements or when using graphite heating containers, Carbon is introduced into the ceramic powder.
Fremgangsmåter hvorved de keramiske pulverne fremstilles fra høyrene forbindelser som metallkloridene eller hydridene kan riktignok føre til de ønskede karbonfattige produktene. Imidlertid innføres karbon på mange måter også ved disse fremgangsmåtene i de videre bearbeidelsestrinnene for fremstilling av keramiske sinterpulvere, som maling for deagglomerering eller innblanding av sinteradditiver eller ved sikting for fjernelse av grovkorn. Følgelig kles apparaturen med organiske polymerer for å redusere metalliske forurensninger ved maling, blanding og sikting, avrivning forurenser imidlertid produktet med karbonholdig materiale. I mange tilfeller anvendes organiske oppløsningsmidler for å forebygge tørragglomerater eller hydrolyse av det finfordelte pulveret. Ved spaltning av de organiske forbindelsene som foreligger som rester i pulveret danner det seg ved de etterfølgende høytemperaturprosessene uønskede karbonforurensninger . Methods by which the ceramic powders are produced from higher compounds such as the metal chlorides or hydrides can indeed lead to the desired low-carbon products. However, carbon is also introduced in many ways in these methods in the further processing steps for the production of ceramic sinter powders, such as grinding for deagglomeration or mixing of sintering additives or during sieving to remove coarse grains. Accordingly, the apparatus is coated with organic polymers to reduce metallic contamination during grinding, mixing and sieving, tear-off, however, contaminates the product with carbonaceous material. In many cases, organic solvents are used to prevent dry agglomerates or hydrolysis of the finely divided powder. When the organic compounds present as residues in the powder are decomposed, unwanted carbon pollution is formed in the subsequent high-temperature processes.
For å redusere karboninnholdet er det teknikkens stand å varmebehandle de keramiske pulverne som er forurenset med karbon i oksyderende atmosfære. Følgelig glødes A1N (US-A 2 962 359), Si3N4 (EP-B 15422) og SiC (EP-A 247907) ved temperaturer mellom 650 og 800°C i oksyderende atmosfære (luft, oksygen). In order to reduce the carbon content, it is state of the art to heat treat the ceramic powders that are contaminated with carbon in an oxidizing atmosphere. Accordingly, A1N (US-A 2 962 359), Si3N4 (EP-B 15422) and SiC (EP-A 247907) are annealed at temperatures between 650 and 800°C in an oxidizing atmosphere (air, oxygen).
Ved disse fremgangsmåtene må det imidlertid, spesielt ved høyrene pulvere av keramisk materiale, anvendes temperaturer over 600°C og lange behandlingstider for oksydasjon av karbonet for å oppnå lave karboninnhold, idet reaksjonen er kinetisk hemmet på grunn av de manglende tungmetallionene med deres katalytiske virkning på karbonforbrenningen. Ved ikke-oksydiske keramiske pulvere som nitrider, karbider og borider eller ved oksyder i lavere oksydasjonstrinn, består dessuten faren for en oksydasjon av pulveret. Med tiltagende finfordeling av pulveret, som for det meste er nødvendig for å oppnå ' en høy sintringsaktivitet, forøkes faren for oksydasjon. Selv ved et materiale som f.eks. silisiumnitrid, som er kjent som oksydasjonsbestandig, inntrer det ved høy finfordelthet ved glødning i luft allerede ved temperaturer under 1000°C en sterk økning av oksygeninnholdet. Ved amorfe pulvere eller ved mindre oksydasjonsbestandige pulvere, som f.eks. aluminiumnitrid, blir problemet stadig mer graverende. In these methods, however, especially with high-purity powders of ceramic material, temperatures above 600°C and long treatment times for oxidation of the carbon must be used to achieve low carbon contents, as the reaction is kinetically inhibited due to the missing heavy metal ions with their catalytic effect on the carbon combustion. With non-oxidizing ceramic powders such as nitrides, carbides and borides or with oxides in lower oxidation stages, there is also the danger of oxidation of the powder. With increasing fine distribution of the powder, which is mostly necessary to achieve a high sintering activity, the risk of oxidation increases. Even with a material such as e.g. silicon nitride, which is known to be oxidation-resistant, a strong increase in the oxygen content occurs at high fineness when annealing in air already at temperatures below 1000°C. In the case of amorphous powders or less oxidation-resistant powders, such as e.g. aluminum nitride, the problem becomes increasingly serious.
I de tilfellene hvor høye oksygeninnhold imidlertid ødelegger sintringsevnen, som f.eks. ved silisiumkarbid eller ønskede fysikalske egenskaper i aluminiumnitrid (J. Phys. Chem. Solids, bind 34 (1973) 321-335), må man følgelig gi avkall på en høy grad av finfordeling, eller man må akseptere et uønsket høyt karboninnhold, henholdsvis må i en ytterligere prosess det oksygenet som er innført ved fjerning av karbonet igjen reduseres. In those cases where high oxygen contents, however, destroy the sintering ability, such as e.g. in the case of silicon carbide or desired physical properties in aluminum nitride (J. Phys. Chem. Solids, vol. 34 (1973) 321-335), one must therefore give up a high degree of fine distribution, or one must accept an undesired high carbon content, respectively must in a further process the oxygen which has been introduced by removing the carbon is again reduced.
Oppgaven ved foreliggende oppfinnelse besto følgelig i å utvikle en fremgangsmåte for reduksjon av karboninnholdet i finfordelte pulvere av keramiske materialer som ikke oppviser de ulempene som er beheftet med fremgangsmåter ifølge den kjente teknikkens stand. The task of the present invention consequently consisted in developing a method for reducing the carbon content in finely divided powders of ceramic materials which does not exhibit the disadvantages that are associated with methods according to the state of the art.
Foreliggende oppfinnelse tilveiebringer følgelig en fremgangsmåte for reduksjon av karbonforurensninger i finfordelte pulvere av keramisk materiale innbefattende karbonoverskuddet inneholdt i keramiske pulvere fremstilt ved den karbotermiske fremgangsmåten, kjennetegnet ved at det keramiske pulveret eller blandingen av keramiske pulvere og karbon underkastes en termisk behandling i oksygen— og vanndampfri atmosfære inneholdende nitrogen og hydrogen og/eller nitrogen-hydrogen-forbindelser, ved en temperatur i området mellom 600°C og 1700°C. The present invention therefore provides a method for reducing carbon impurities in finely divided powders of ceramic material including the excess carbon contained in ceramic powders produced by the carbothermic method, characterized in that the ceramic powder or the mixture of ceramic powders and carbon is subjected to a thermal treatment in oxygen- and water vapor-free atmosphere containing nitrogen and hydrogen and/or nitrogen-hydrogen compounds, at a temperature in the range between 600°C and 1700°C.
Fortrinnsvis gjennomføres karbonfjernelsen i en atmosfære av ammoniakk-gass. Sammenlignet med nitrogen/hydrogen-blandinger kan fjernelsen av karbonet da gjennomføres ved vesentlig lavere temperaturer og ammoniakk er, sammenlignet med andre nitrogen-hydrogen-forbindelser, som f.eks. hydrazin, sikkerhetsteknisk mindre betenkelig og mer økonomisk. Preferably, the carbon removal is carried out in an atmosphere of ammonia gas. Compared to nitrogen/hydrogen mixtures, the removal of the carbon can then be carried out at significantly lower temperatures and ammonia is, compared to other nitrogen-hydrogen compounds, such as e.g. hydrazine, less dangerous from a safety point of view and more economical.
Ammoniakken kan av fremgangsmåtetekniske grunner som bærergass være tilsatt inertgasser som N2, H2, edelgasser eller blandinger av disse gassene. For technical reasons, the ammonia can be added as a carrier gas with inert gases such as N2, H2, noble gases or mixtures of these gases.
For å akselerere karbonfjernelsen er det hensiktsmessig å gjennomføre temperaturbehandlingen med ammoniakk ved forhøyet temperatur. For å forhindre en dekomponering av den termisk instabile ammoniakken til nitrogen og hydrogen, som er vesentlig mer inaktiv med tanke på en karbonfjernelse, innføres ved temperaturer over 1000°C ammoniakken fortrinnvis via innerrøret av to konsentrisk anordnede rør og ringspalten mellom rørene gjennomstrømmes med en inertgass. Inn-ledningsrøret avkjøles herved og en termisk dekomponering av ammoniakk-gassen forhindres i stor grad. In order to accelerate the carbon removal, it is appropriate to carry out the temperature treatment with ammonia at an elevated temperature. In order to prevent a decomposition of the thermally unstable ammonia into nitrogen and hydrogen, which is significantly more inactive in terms of carbon removal, at temperatures above 1000°C the ammonia is preferably introduced via the inner tube of two concentrically arranged tubes and the annular gap between the tubes is flowed through with an inert gas . The inlet pipe is thereby cooled and a thermal decomposition of the ammonia gas is largely prevented.
Den termiske behandlingen av keramiske pulvere foregår over et tidsrom på 0,15 til 200 timer og avhenger i stor grad av temperaturen, gassammensetningen, de anvendte materialene samt apparaturkonfigurasjonen. The thermal treatment of ceramic powders takes place over a period of 0.15 to 200 hours and largely depends on the temperature, the gas composition, the materials used and the equipment configuration.
Idet det ved fremgangsmåten ifølge oppfinnelsen ikke anvendes oksydasjonsmidler for fjernelse av karbon, kan finfordelte nitrider, karbider, karbonitrider, borider, suboksyder eller deres blandingsfaser av metaller eller metalloider i størst mulig grad befris for forstyrrende karbon, uten at et ytterligere fremgangsmåtetrinn for fjernelse av uønskede oksydasjonsprodukter er nødvendig. Som materialer kan bl.a. nevnes B4C, TiC, ZeC, WC, TiB2, Si3N4, TiN, ZrN, Cr2N, Ti(C,N) eller også A1N, BN og SIC. Since no oxidizing agents are used in the method according to the invention to remove carbon, finely divided nitrides, carbides, carbonitrides, borides, suboxides or their mixed phases of metals or metalloids can be freed from disturbing carbon to the greatest possible extent, without a further process step for removing unwanted oxidation products are required. As materials, i.a. are mentioned B4C, TiC, ZeC, WC, TiB2, Si3N4, TiN, ZrN, Cr2N, Ti(C,N) or also A1N, BN and SIC.
Fremgangsmåten kan også med fordel anvendes ved oksyda-sjonsfølsomme pulvere av nitridglass, oksynitridglass eller SIALON-glass av metaller eller metalloider. Anvendelsen av disse materialene blir, på grunn av deres interessante fysikalske egenskaper, diskutert i stadig større grad, f.eks. innenfor den keramiske forbindelsesteknikken eller som sinteradditiver. Det kan fremstilles finfordelt ved karbotermisk nitridering fra de tilsvarende oksydene, men oppstår imidlertid da forurenset med karbonpulver. The method can also be advantageously used with oxidation-sensitive powders of nitride glass, oxynitride glass or SIALON glass of metals or metalloids. The use of these materials is, due to their interesting physical properties, increasingly discussed, e.g. within the ceramic connection technique or as sintering additives. It can be produced in finely divided form by carbothermic nitriding from the corresponding oxides, but is then contaminated with carbon powder.
Oppfinnelsen belyses nærmere ved hjelp av de følgende eksemplene. The invention is explained in more detail with the help of the following examples.
De i eksemplene angitte karboninnholdene ble bestemt med en C-S-mat fra firma StrOhlein ved forbrenning i oksygenstrøm. The carbon contents stated in the examples were determined with a C-S mat from the company StrOhlein by combustion in an oxygen stream.
Eksempel 1 Example 1
5,16 g av et AlN-pulver fremstilt ved karbotermisk fremgangsmåte, som var forurenset med karbon fra fremstillings-prosessen, med den kjemiske sammensetningen: Al: 41,7 % ; N: 21,3 $ >; C: 36,0 <K>; 0: 0,58 % 5.16 g of an AlN powder produced by the carbothermic process, which was contaminated with carbon from the production process, with the chemical composition: Al: 41.7%; N: $21.3 >; C: 36.0 <K>; 0: 0.58%
ble oppvarmet i et kvartsskip i 20 timer i en NH3~strøm på 200 l/t ved en temperatur på 1200°C. was heated in a quartz vessel for 20 hours in a NH3 flow of 200 l/h at a temperature of 1200°C.
Det ble oppnådd 3,3 g AlN-pulver med følgende kjemiske sammensetning: Al: 64 ,2 56; N: 33,2 % ; C: 0,085 4>; 0: 0,81 %. 3.3 g of AlN powder with the following chemical composition was obtained: Al: 64.2 56; N: 33.2%; C: 0.085 4>; 0: 0.81%.
Den spesifikke overflaten (BET) for produktet utgjorde 4,8 m<2>g_<1> (målt ved l-punkt-N2-fremgangsmåten). The specific surface area (BET) of the product was 4.8 m<2>g_<1> (measured by the 1-point N 2 method).
Eksempel 2 Example 2
1,46 g av et med 22,0 Sé karbon forurenset AlN-pulver med et oksygeninnhold på 0,81 % ble gassbehandlet ved 1200"C i et 1.46 g of a 22.0 Sé carbon contaminated AlN powder with an oxygen content of 0.81% was gas treated at 1200°C in a
kvartsskip i 2 timer med en NE^-strøm på 150 l/t. Gasstil-førselslansen med 8 mm innerdiameter nådde til umiddelbar nærhet av pulverblandingen. Ved avkjøling med nitrogengass ble temperaturen for gasstilførselslansen holdt på under 800°C. quartz vessel for 2 hours with a NE^ flow of 150 l/h. The gas supply lance with an inner diameter of 8 mm reached the immediate vicinity of the powder mixture. When cooling with nitrogen gas, the temperature of the gas supply lance was kept below 800°C.
Det ble oppnådd 1,13 g AlN-pulver med et karboninnhold på 0,16 56 og et oksygeninnhold på 0,68 %. Den spesifikke overflaten(BET) utgjorde 3,1 m<2>/g"<1> (målt ifølge l-punkt-N2-fremgangsmåten). 1.13 g of AlN powder was obtained with a carbon content of 0.16 56 and an oxygen content of 0.68%. The specific surface area (BET) was 3.1 m<2>/g"<1> (measured according to the 1-point N2 method).
Eksempel 3 Example 3
14,7 g av et ved den karbotermiske fremgangsmåten fremstilt karbonholdig Si3N4~pulver med den kjemiske sammensetningen Si: 17,4 %i N: 8,3 56; C: 73 % ; 0: 0,46 56 14.7 g of a carbonaceous Si3N4 ~ powder produced by the carbothermic process with the chemical composition Si: 17.4% in N: 8.3 56; C: 73%; 0: 0.46 56
ble ved 1250° C i 165 timer oppvarmet i en NH3/N2-strøm på 90/30 l/t. was heated at 1250° C for 165 hours in an NH3/N2 flow of 90/30 l/h.
Resten, 3,5 g, besto av 98 # alfa-Sis^ og 2 $6 beta-Sis^ med følgende kjemiske analyse: Si: 53 56; N: 38,9 56; C: 0,56 56; 0: 1,17 56. The residue, 3.5 g, consisted of 98 # alpha-Sis^ and 2 $6 beta-Sis^ with the following chemical analysis: Si: 53 56; N: 38.9 56; C: 0.56 56; 0: 1.17 56.
Eksempel 4 Example 4
11 g av et ved den karbotermiske fremgangsmåten fremstilt karbonholdig SiC/SiC3N4-kompositt-pulver med et karboninnhold på 70 56 og et oksygeninnhold på 0,5 % ble i 6 timer oppvarmet til 1200°C i en NH3/N2-strøm på 90/30 l/t. 11 g of a carbonaceous SiC/SiC3N4 composite powder produced by the carbothermic process with a carbon content of 70 56 and an oxygen content of 0.5% were heated for 6 hours to 1200°C in an NH3/N2 flow of 90/ 30 l/h.
Røntgendiffraksjonsanalyse av resten, 3,3 g, viste refleksene av beta-SiC, alfa-Si3N4 og beta-Sis^. Den kjemiske analysen av det lysegrå SiC/Si3N4-kompositt-pulveret ga: Si: 57,4 %; N: 28,4 % ; C: 8,6 % ; 0: 1,66 %. X-ray diffraction analysis of the residue, 3.3 g, showed the reflections of beta-SiC, alpha-Si3N4 and beta-Sis^. The chemical analysis of the light gray SiC/Si3N4 composite powder gave: Si: 57.4%; N: 28.4%; C: 8.6%; 0: 1.66%.
Claims (8)
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3910781A DE3910781A1 (en) | 1989-04-04 | 1989-04-04 | METHOD FOR PRODUCING LOW-CARBON, FINE-PART CERAMIC POWDER |
Publications (4)
| Publication Number | Publication Date |
|---|---|
| NO901302D0 NO901302D0 (en) | 1990-03-21 |
| NO901302L NO901302L (en) | 1990-10-05 |
| NO178999B true NO178999B (en) | 1996-04-09 |
| NO178999C NO178999C (en) | 1996-07-17 |
Family
ID=6377765
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| NO901302A NO178999C (en) | 1989-04-04 | 1990-03-21 | Process for reducing carbon pollutants in finely divided ceramic powders |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0391150B1 (en) |
| JP (1) | JPH02289457A (en) |
| DE (2) | DE3910781A1 (en) |
| NO (1) | NO178999C (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19646333C2 (en) * | 1996-11-09 | 1999-01-14 | Fraunhofer Ges Forschung | Process for the production of oxygen-containing hard materials and their use |
| CN107721429B (en) * | 2017-11-15 | 2020-02-21 | 中国科学院福建物质结构研究所 | Zirconium carbide-silicon carbide composite powder material and preparation method thereof |
| CN116217246B (en) * | 2023-02-27 | 2023-12-19 | 合肥水泥研究设计院有限公司 | An inorganic binder and a method for preparing an inorganic binder/TiC composite material |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1327707A (en) * | 1956-07-31 | 1963-05-24 | Pechiney Prod Chimiques Sa | Aluminum nitride manufacturing process |
| JPS55113603A (en) * | 1979-02-19 | 1980-09-02 | Toshiba Corp | Manufacture of alpha silicon nitride powder |
| FR2596745B1 (en) * | 1986-04-03 | 1991-06-07 | Atochem | POWDERS FOR CARBIDE AND METAL NITRIDE CERAMICS BY CARBOTHERMAL REDUCTION AND THEIR MANUFACTURING METHOD |
| ES2004407A6 (en) * | 1987-04-28 | 1989-01-01 | Union Explosivos Rio Tinto | A method for the production of beta'-sialon based ceramic powders. |
-
1989
- 1989-04-04 DE DE3910781A patent/DE3910781A1/en not_active Withdrawn
-
1990
- 1990-03-21 NO NO901302A patent/NO178999C/en unknown
- 1990-03-22 DE DE9090105410T patent/DE59001404D1/en not_active Expired - Fee Related
- 1990-03-22 EP EP90105410A patent/EP0391150B1/en not_active Expired - Lifetime
- 1990-03-29 JP JP2079080A patent/JPH02289457A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| NO901302L (en) | 1990-10-05 |
| NO178999C (en) | 1996-07-17 |
| DE3910781A1 (en) | 1990-10-11 |
| JPH02289457A (en) | 1990-11-29 |
| DE59001404D1 (en) | 1993-06-17 |
| EP0391150A1 (en) | 1990-10-10 |
| EP0391150B1 (en) | 1993-05-12 |
| NO901302D0 (en) | 1990-03-21 |
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