WO1991014659A1 - Process for manufacturing fibrous magnesium oxide - Google Patents

Process for manufacturing fibrous magnesium oxide Download PDF

Info

Publication number
WO1991014659A1
WO1991014659A1 PCT/AT1991/000041 AT9100041W WO9114659A1 WO 1991014659 A1 WO1991014659 A1 WO 1991014659A1 AT 9100041 W AT9100041 W AT 9100041W WO 9114659 A1 WO9114659 A1 WO 9114659A1
Authority
WO
WIPO (PCT)
Prior art keywords
magnesium oxide
magnesium
fibrous
calcined
fibrous magnesium
Prior art date
Application number
PCT/AT1991/000041
Other languages
German (de)
French (fr)
Inventor
Andreas Meier
Michael Grill
Original Assignee
Veitscher Magnesitwerke-Actien-Gesellschaft
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Veitscher Magnesitwerke-Actien-Gesellschaft filed Critical Veitscher Magnesitwerke-Actien-Gesellschaft
Priority to JP3506244A priority Critical patent/JPH0723216B2/en
Priority to KR1019910701362A priority patent/KR920701045A/en
Publication of WO1991014659A1 publication Critical patent/WO1991014659A1/en
Priority to NO91914560A priority patent/NO914560L/en

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F5/00—Compounds of magnesium
    • C01F5/02—Magnesia
    • C01F5/06—Magnesia by thermal decomposition of magnesium compounds
    • C01F5/08—Magnesia by thermal decomposition of magnesium compounds by calcining magnesium hydroxide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F5/00—Compounds of magnesium
    • C01F5/02—Magnesia
    • C01F5/06—Magnesia by thermal decomposition of magnesium compounds
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2/00—Lime, magnesia or dolomite
    • C04B2/10—Preheating, burning calcining or cooling
    • C04B2/102—Preheating, burning calcining or cooling of magnesia, e.g. dead burning
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/03—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite
    • C04B35/04—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite based on magnesium oxide
    • C04B35/053—Fine ceramics
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/62227—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres
    • C04B35/62231—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres based on oxide ceramics
    • C04B35/62263—Fibres based on magnesium oxide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like

Definitions

  • the invention relates to a process for the production of fibrous magnesium oxide, in which a material present in the form of needle-shaped particles and containing magnesium and water of crystallization is converted into the fibrous magnesium oxide by calcination.
  • Magnesium oxide has a very high melting point and has good chemical resistance to basic systems and furthermore has good electrical insulation ability and also a relatively good thermal conductivity. As a result of these properties, it is widely used in various fields, in particular as a material for refractory bodies or stones which are used in the iron and steel industry and as a filler for synthetic resins which can increase the thermal conductivity of the synthetic resin material.
  • the magnesium oxide usually consists of particles of granular shape, ie of particles which, like cubes and spheres, have approximately the same dimensions in different directions.
  • Fibrous magnesium oxide is also known, ie a magnesium oxide, the particles of which have an elongated shape, the length of these particles relating to their largest mean transverse dimension being at least 10: 1, the cross-sectional area of the particles being less than 0.05 mm 2 and the particle width is less than 0.25 mm (see also ASTM D 3878).
  • Such fibrous magnesium oxide particles have a comparatively high strength and, as a result, bodies or stones which consist of magnesium oxide and are used, for example, to form refractory linings, and in particular bodies made of plastics which contain magnesium oxide as a filler significantly higher strength can be achieved than when using the usual magnesium oxide with granular particles.
  • the known processes for the production of fibrous magnesium oxide have a number of disadvantages, such as, for example, low performance, the production costs being burdened at the same time by a large expenditure of energy, and a relatively complicated process procedure for intermediates which result from slow-running reactions. stand, and the additional serious disadvantage that the conversion of these intermediates to the fibrous Magnesium ⁇ oxide corrosive or toxic gases, the disposal of which is difficult and burdens the process costs.
  • One such known method provides for the deposition of magnesium oxide from the vapor phase, in which magnesium metal vapor is first reacted with oxygen to form magnesium oxide, and when the magnesium oxide is deposited, fibrous magnesium oxide particles are formed from the vapor phase. This method has a relatively low performance and requires a large amount of energy.
  • Another known process provides for the intermediate product to be made from acicular basic magnesium compounds in which a mono- to tetravalent anion is present and which contain water of crystallization, and to convert this intermediate product to fibrous magnesium oxide by calcining, or to initially produce magnesium hydroxide from such an intermediate product and from this to form the fibrous magnesium oxide.
  • the production of the basic magnesium compounds mentioned is cumbersome and corrosive or toxic gases are released when the latter are calcined, as a result of which the process is further complicated with regard to the necessary disposal of these gases.
  • the process of the type mentioned at the outset is characterized in that one or more magnesium neutral carbonates containing water of crystallization, which correspond to the formula MgC0 3 .xH 2 0, where 1 ⁇ x ⁇ 5, in particular magnesium carbonate trihydrate, are used as the material to be calcined.
  • Magnesium-neutral carbonates containing water of crystallization are relatively easily accessible, for example by precipitation of magnesium salt solutions with ammonia and carbon dioxide. oxide, ammonium carbonate or ammonium bicarbonate, or by carbonizing precipitated magnesium hydroxide.
  • magnesium carbonate trihydrate in the form of acicular crystals can be precipitated simply and quickly from an aqueous solution, the size of the crystals being able to be influenced by the choice of the temperature in the reactor. These are temperatures which are only slightly above the ambient temperature and do not cause any special structural measures or energy expenditure.
  • the magnesium neutral carbonates containing water of crystallization can be calcined in a simple manner with largely maintaining the particle shape to give fibrous magnesium oxide. This calcining process does not produce any toxic or corrosive products.
  • the calcining temperature can be selected within wide limits, and good results can be achieved at calcining temperatures between 350 and 2000 ° C. Calcination temperatures between 800 and 1600 ° C. are preferably used. Depending on the equipment used for the calcination, very short calcination times, e.g. a few seconds, up to long calcining times of a few hours. It is advantageous if the material to be calcined is dried in a vacuum or partially dewatered at a temperature below 100 ° C. before calcining.
  • the particles of the fibrous magnesium oxide produced by the process according to the invention have a high strength, and higher strength values can be achieved than they are present with particles of fibrous magnesium oxide which has been produced in a known manner from basic magnesium compounds. If fibrous magnesium oxide, which has been produced by the process according to the invention, is used as a filler for synthetic resins, a considerable increase in the strength values of the filled plastic can be achieved even with relatively small amounts of filler. aims to be.
  • Example 1 500 ml of distilled water were placed in a thermostatted stirring vessel, 500 ml of a magnesium chloride solution with 298 g / 1 MgCl 2 were added and the mixture was heated to 35 ° C. The solution was mixed vigorously with the aid of a stirrer and 213 g of a 25% strength ammonia solution were added dropwise over a period of 30 minutes and 35 l of CO 2 were introduced into the solution. The reaction mixture was kept at a temperature of 40 ° C. using a heat exchanger. After the reaction was complete, the suspension was filtered, the filter cake was washed with water and the product obtained was dried in vacuo at low temperatures of less than 40 ° C. The product was identified as nesquehonite, MgC0 3 .3H 2 0, with acicular crystal habit.
  • the product produced in this way was calcined at 1100 ° C. for 3 hours, fibrous magnesium oxide being obtained. Similar to the Nesquehonit primary fibers used, the synthesized fibers had a length of approximately 150 ⁇ m and an average diameter of approximately 5 ⁇ m. The product was identified as magnesium oxide by means of X-ray diffractometry.
  • Example 2 The procedure was analogous to Example 1, but the filter cake obtained after the reaction and filtration of the suspension had been washed and washed with water was dried in vacuo at a temperature of 70 ° C. for 2 h.
  • the chemical analysis showed that a magnesium neutral carbonate with the product composition MgC0 3 .2.4H 2 0 had formed.
  • Scanning electron micrographs showed that the product thus obtained was composed of fibers with a length of approximately 150 ⁇ m and an average diameter of approximately 5 ⁇ m.
  • the product manufactured in this way was treated with a Heating rate of 3 ° C / min brought to a temperature of 850 ° C and cooled uncontrolled after a holding time of 1 h.
  • a fibrous substance with fiber lengths of approximately 150 ⁇ m and average fiber diameters of approximately 5 ⁇ m was obtained.
  • X-ray diffractometric images confirmed that the material was magnesium oxide.
  • Example 3 The product from Example 1, identified as nesquehonite, MgC0 3 .3H 2 0, with acicular crystal halus was brought to a temperature of 1600 ° C. at a heating rate of 5 ° C./min a holding time of 1 h cooled in an uncontrolled manner.
  • the fibrous product could be identified as magnesium oxide by X-ray diffractometric images. Similar to the nesquehonite used, the fiber lengths were 50-150 ⁇ m, with average fiber diameters of 2-5 ⁇ m.
  • Example 4 The magnesium neutral carbonate from Example 2 with the product composition MgC0 3 .2.4H 2 0 was brought to a temperature of 400 ° C at a heating rate of 10 ° C / min. After a holding time of 3 hours, fibrous magnesium oxide was obtained. The fibers synthesized did not differ morphologically from the magnesium neutral carbonate used and showed fiber lengths of up to 150 ⁇ m and average fiber diameter of about 3-5 ⁇ m. X-ray diffractometric images confirmed that the material was magnesium oxide.
  • EXAMPLE 5 Use of the MgO Fibers to Increase the Strengths of Composites:
  • the results of the tests are summarized in Table I. It can be seen that with the MgO fibers according to the invention there is a significant increase in the bending strength of the composite materials even with the small amounts added.
  • the intrinsic strength of the MgO fibers according to the invention is calculated on the basis of the mixing rule and assuming an isotropic distribution of the fibers in the matrix.
  • Epoxy resin MgO-62 according to the invention

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Ceramic Engineering (AREA)
  • Structural Engineering (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Paper (AREA)

Abstract

In a process for manufacturing fibrous magnesium oxide, one or more magnesium neutral carbonates containing water of crystallization, in particular magnesium carbonate trihydrate, are separated in the form of needle-shaped particles from an aqueous solution, dried and then calcined to fibrous magnesium oxide, the particle shape being retained.

Description

Verfahren zur Herstellung von faserförmigem Magnesiumoxid Process for the production of fibrous magnesium oxide
Die Erfindung bezieht sich auf ein Verfahren zur Herstel¬ lung von faserförmigem Magnesiumoxid, bei dem ein in Form na¬ deiförmiger Teilchen vorliegendes, Magnesium und Kristallwasser enthaltendes Material durch Calcinieren in das faserförmige Magnesiumoxid umgewandelt wird.The invention relates to a process for the production of fibrous magnesium oxide, in which a material present in the form of needle-shaped particles and containing magnesium and water of crystallization is converted into the fibrous magnesium oxide by calcination.
Magnesiumoxid weist einen sehr hohen Schmelzpunkt auf und besitzt eine gute chemische Beständigkeit gegenüber basischen Systemen und hat weiter eine gute elektrische Isolationsfähig¬ keit und auch eine verhältnismäßig gute Wärmeleitfähigkeit. Durch diese Eigenschaften findet es auf verschiedenen Gebieten verbreitet Anwendung, insbesondere als Material für feuerfeste Körper bzw. Steine, welche in der Hüttenindustrie verwendet werden, und als Füllstoff für Kunstharze, der die Wärmeleit¬ fähigkeit des Kunstharzmaterials erhöhen kann. Das Magnesium¬ oxid besteht üblicherweise aus Teilchen von körniger Form, d.h. aus Teilchen, welche ähnlich wie Würfel und Kugeln in verschie¬ denen Richtungen annähernd gleiche Abmessungen aufweisen. Es ist auch faserförmiges Magnesiumoxid bekannt, d.h. ein Magne¬ siumoxid, dessen Teilchen längliche Form haben, wobei sich die Länge dieser Teilchen zu ihrer größten mittleren Querabmessung mindestens wie 10 : 1 verhält, wobei die Querschnittsfläche der Teilchen kleiner als 0,05 mm2 und die Teilchenbreite kleiner als 0,25 mm ist (siehe auch ASTM D 3878). Solche faserförmigen Magnesiumoxidteilchen haben eine verhältnismäßig große Festig¬ keit und es kann dadurch bei Körpern bzw. Steinen, welche aus Magnesiumoxid bestehen und z.B. zur Bildung feuerfester Aus¬ kleidungen dienen, und insbesondere bei Körpern aus Kunststof¬ fen, welche Magnesiumoxid als Füllstoff enthalten, eine deut¬ lich höhere Festigkeit erzielt werden als beim Einsatz des üb¬ lichen Magnesiumoxids mit körnigen Teilchen.Magnesium oxide has a very high melting point and has good chemical resistance to basic systems and furthermore has good electrical insulation ability and also a relatively good thermal conductivity. As a result of these properties, it is widely used in various fields, in particular as a material for refractory bodies or stones which are used in the iron and steel industry and as a filler for synthetic resins which can increase the thermal conductivity of the synthetic resin material. The magnesium oxide usually consists of particles of granular shape, ie of particles which, like cubes and spheres, have approximately the same dimensions in different directions. Fibrous magnesium oxide is also known, ie a magnesium oxide, the particles of which have an elongated shape, the length of these particles relating to their largest mean transverse dimension being at least 10: 1, the cross-sectional area of the particles being less than 0.05 mm 2 and the particle width is less than 0.25 mm (see also ASTM D 3878). Such fibrous magnesium oxide particles have a comparatively high strength and, as a result, bodies or stones which consist of magnesium oxide and are used, for example, to form refractory linings, and in particular bodies made of plastics which contain magnesium oxide as a filler significantly higher strength can be achieved than when using the usual magnesium oxide with granular particles.
Die bekannten Verfahren zur Herstellung von faserförmigem Magnesiumoxid haben eine Reihe von Nachteilen, wie z.B. eine geringe Leistungsfähigkeit, wobei gleichzeitig die Gestehungs¬ kosten durch einen großen Energieaufwand belastet sind, und eine verhältnismäßig komplizierte Verfahrensführung über Zwi¬ schenprodukte, die durch langsam ablaufende Reaktionen ent- stehen, und den zusätzlichen gravierenden Nachteil, daß bei der Umsetzung dieser Zwischenprodukte zum faserförmigen Magnesium¬ oxid korrosive oder toxische Gase entstehen, deren Entsorgung schwierig ist und die Verfahrenskosten belastet. Ein solches bekanntes Verfahren sieht ein Niederschlagen von Magnesiumoxid aus der Dampfphase vor, wobei vorausgehend Magnesiummetalldampf mit Sauerstoff zur Reaktion gebracht wird, um Magnesiumoxid zu bilden, und beim Niederschlagen des Magnesiumoxids aus der Dampfphase faserförmige Magnesiumoxidteilchen gebildet werden. Dieses Verfahren hat eine verhältnismäßig geringe Leistungs¬ fähigkeit und erfordert einen großen Energieaufwand. Ein ande¬ res bekanntes Verfahren sieht vor, als Zwischenprodukt nadei¬ förmige basische Magnesiumverbindungen, in denen ein ein- bis vierwertiges Anion vorliegt und die Kristallwasser enthalten, herzustellen und dieses Zwischenprodukt durch Calcinieren zu faserförmigem Magnesiumoxid umzuwandeln, oder zunächst aus einem solchen Zwischenprodukt Magnesiumhydroxid herzustellen und aus diesem das faserförmige Magnesiumoxid zu bilden. Die Herstellung der genannten basischen Magnesiumverbindungen ist umständlich und es werden beim Calcinieren derselben korrosive oder toxische Gase freigesetzt, wodurch das Verfahren eine wei¬ tere Komplizierung im Hinblick auf die notwendige Entsorgung dieser Gase erfährt.The known processes for the production of fibrous magnesium oxide have a number of disadvantages, such as, for example, low performance, the production costs being burdened at the same time by a large expenditure of energy, and a relatively complicated process procedure for intermediates which result from slow-running reactions. stand, and the additional serious disadvantage that the conversion of these intermediates to the fibrous Magnesium¬ oxide corrosive or toxic gases, the disposal of which is difficult and burdens the process costs. One such known method provides for the deposition of magnesium oxide from the vapor phase, in which magnesium metal vapor is first reacted with oxygen to form magnesium oxide, and when the magnesium oxide is deposited, fibrous magnesium oxide particles are formed from the vapor phase. This method has a relatively low performance and requires a large amount of energy. Another known process provides for the intermediate product to be made from acicular basic magnesium compounds in which a mono- to tetravalent anion is present and which contain water of crystallization, and to convert this intermediate product to fibrous magnesium oxide by calcining, or to initially produce magnesium hydroxide from such an intermediate product and from this to form the fibrous magnesium oxide. The production of the basic magnesium compounds mentioned is cumbersome and corrosive or toxic gases are released when the latter are calcined, as a result of which the process is further complicated with regard to the necessary disposal of these gases.
Es ist ein Ziel der vorliegenden Erfindung, ein Verfahren eingangs erwähnter Art zu schaffen, welches möglichst einfach und mit geringem Kostenaufwand durchgeführt werden kann, wel¬ ches mengenmäßig leistungsfähig ist und welches hinsichtlich der beim Verfahren anfallenden Nebenprodukte keine größeren Probleme verursacht.It is an object of the present invention to provide a method of the type mentioned at the outset which can be carried out as simply and at low cost as possible, which is efficient in terms of quantity and which does not cause any major problems with regard to the by-products obtained in the process.
Das erfindungsgemäße Verfahren eingangs erwähnter Art ist dadurch gekennzeichnet, daß als zu calcinierendes Material ein oder mehrere kristallwasserhaltige Magnesiumneutralcarbonate, welche der Formel MgC03.xH20 entsprechen, wobei 1 ≤ x ≤ 5 ist, insbesonsondere Magnesiumcarbonat-Trihydrat, verwendet werden.The process of the type mentioned at the outset is characterized in that one or more magnesium neutral carbonates containing water of crystallization, which correspond to the formula MgC0 3 .xH 2 0, where 1 ≤ x ≤ 5, in particular magnesium carbonate trihydrate, are used as the material to be calcined.
Durch dieses Verfahren kann der vorstehend angeführten Zielsetzung gut entsprochen werden. Kristallwasserhaltige Ma¬ gnesiumneutralcarbonate, insbesondere Magnesiumcarbonat-Tri¬ hydrat, sind verhältnismäßig einfach zugänglich, z.B. durch Fällung von Magnesiumsalzlösungen mit Ammoniak und Kohlendi- oxid, Ammoniumcarbonat bzw. Ammoniumhydrogencarbonat, oder durch Carbonisieren von gefälltem Magnesiumhydroxid. Es kann so z.B. Magnesiumcarbonat-Trihydrat in Form von nadeiförmigen Kristallen aus einer wässerigen Lösung einfach und schnell aus¬ gefällt werden, wobei die Größe der Kristalle durch Wahl der im Reaktor vorliegenden Temperatur beeinflußt werden kann. Es han¬ delt sich dabei um Temperaturen, welche nur wenig über der Um¬ gebungstemperatur liegen und keinerlei bauliche Sondermaßnahmen oder energetischen Aufwand verursachen.The above objective can be met well by this method. Magnesium-neutral carbonates containing water of crystallization, in particular magnesium carbonate trihydrate, are relatively easily accessible, for example by precipitation of magnesium salt solutions with ammonia and carbon dioxide. oxide, ammonium carbonate or ammonium bicarbonate, or by carbonizing precipitated magnesium hydroxide. For example, magnesium carbonate trihydrate in the form of acicular crystals can be precipitated simply and quickly from an aqueous solution, the size of the crystals being able to be influenced by the choice of the temperature in the reactor. These are temperatures which are only slightly above the ambient temperature and do not cause any special structural measures or energy expenditure.
Die kristallwasserhaltigen Magnesiumneutralcarbonate können auf einfache Weise unter weitgehender Erhaltung der Teilchen¬ form zu faserförmigem Magnesiumoxid calciniert werden. Es ent¬ stehen bei diesem Calciniervorgang keinerlei toxische oder kor¬ rosiv wirkende Produkte. Die Calciniertemperatur kann in weiten Grenzen gewählt werden, wobei gute Ergebnisse bei Calciniertem- peraturen zwischen 350 und 2000°C erzielt werden können. Bevor¬ zugt kommen Calciniertemperaturen zwischen 800 und 1600°C zur Anwendung. Je nach der zur Calcinierung verwendeten Einrichtung kann mit sehr kurzen Calcinierzeiten, von z.B. einigen Sekun¬ den, bis zu langen Calcinierzeiten von einigen Stunden gearbei¬ tet werden. Es ist günstig, wenn das zu calcinierende Material vor dem Calcinieren bei einer unter 100°C liegenden Temperatur im Vakuum getrocknet bzw. teilweise entwässert wird.The magnesium neutral carbonates containing water of crystallization can be calcined in a simple manner with largely maintaining the particle shape to give fibrous magnesium oxide. This calcining process does not produce any toxic or corrosive products. The calcining temperature can be selected within wide limits, and good results can be achieved at calcining temperatures between 350 and 2000 ° C. Calcination temperatures between 800 and 1600 ° C. are preferably used. Depending on the equipment used for the calcination, very short calcination times, e.g. a few seconds, up to long calcining times of a few hours. It is advantageous if the material to be calcined is dried in a vacuum or partially dewatered at a temperature below 100 ° C. before calcining.
Es ist weiter beim erfindungsgemäßen Verfahren vorzugsweise vorgesehen, daß beim Calcinieren das Aufheizen des zu calcinie- renden Materials mit einer unter 10°C/min liegenden Rate vorge¬ nommen wird. Es wird so ein schonender Ablauf des Calciniervor- ganges erzielt, der die Umwandlung der Magnesiumneutralcarbo¬ nate in faserförmiges Magnesiumoxid begünstigt.It is further preferably provided in the method according to the invention that during calcining the material to be calcined is heated at a rate below 10 ° C./min. A gentle course of the calcination process is thus achieved, which favors the conversion of the magnesium neutral carbonates into fibrous magnesium oxide.
Die Teilchen des durch das erfindungsgemäße Verfahren her¬ gestellten faserförmigen Magnesiumoxids haben eine hohe Festig¬ keit, wobei höhere Festigkeitswerte erzielt werden können als sie bei Teilchen von faserförmigem Magnesiumoxid, das auf be¬ kannte Weise aus basischen Magnesiumverbindungen hergestellt worden ist, vorliegen. Es kann so beim Einsatz von faserförmi¬ gem Magnesiumoxid, welches durch das erfindungsgemäße Verfahren hergestellt worden ist, als Füllstoff von Kunstharzen schon bei verhältnismäßig geringen Mengen an Füllstoff eine beträchtliche Erhöhung der Festigkeitswerte des gefüllten Kunststoffes er- zielt werden.The particles of the fibrous magnesium oxide produced by the process according to the invention have a high strength, and higher strength values can be achieved than they are present with particles of fibrous magnesium oxide which has been produced in a known manner from basic magnesium compounds. If fibrous magnesium oxide, which has been produced by the process according to the invention, is used as a filler for synthetic resins, a considerable increase in the strength values of the filled plastic can be achieved even with relatively small amounts of filler. aims to be.
Die Erfindung wird nun an Hand von Beispielen weiter erläu¬ tert.The invention will now be further explained using examples.
B e i s p i e l 1: In einem thermostatisierbaren Rührgefäß wurden 500 ml destilliertes Wasser vorgelegt, 500 ml einer Ma¬ gnesiumchloridlösung mit 298 g/1 MgCl2 zugegeben und die Mi¬ schung auf 35°C erwärmt. Die Lösung wurde mit Hilfe eines Rüh¬ rers intensiv gemischt und über einen Zeitraum von 30 min wur¬ den 213 g einer 25 %igen Ammoniaklösung zugetropft sowie 35 1 C02 in die Lösung eingebracht. Das Reaktionsgemisch wurde mit Hilfe eines Wärmeaustauschers auf einer Temperatur von 40°C ge¬ halten. Nach vollständiger Reaktion wurde die Suspension fil¬ triert, der Filterkuchen mit Wasser gewaschen und das erhaltene Produkt bei niedrigen Temperaturen von weniger als 40°C im Va¬ kuum getrocknet. Das Produkt wurde als Nesquehonit, MgC03.3H20, mit nadeiförmigem Kristallhabitus identifiziert.Example 1: 500 ml of distilled water were placed in a thermostatted stirring vessel, 500 ml of a magnesium chloride solution with 298 g / 1 MgCl 2 were added and the mixture was heated to 35 ° C. The solution was mixed vigorously with the aid of a stirrer and 213 g of a 25% strength ammonia solution were added dropwise over a period of 30 minutes and 35 l of CO 2 were introduced into the solution. The reaction mixture was kept at a temperature of 40 ° C. using a heat exchanger. After the reaction was complete, the suspension was filtered, the filter cake was washed with water and the product obtained was dried in vacuo at low temperatures of less than 40 ° C. The product was identified as nesquehonite, MgC0 3 .3H 2 0, with acicular crystal habit.
Rasterelektronenmikroskopische Aufnahmen ergaben, daß die Nesquehonit-Nadeln eine Länge von etwa 150 μm und einen durch¬ schnittlichen Durchmesser von etwa 5 μm besaßen.Scanning electron micrographs showed that the nesquehonite needles had a length of approximately 150 μm and an average diameter of approximately 5 μm.
Das auf diese Weise hergestellte Produkt wurde bei 1100°C 3 h calciniert, wobei faserförmiges Magnesiumoxid erhalten wur¬ de. Die synthetisierten Fasern wiesen ähnlich den eingesetzten Nesquehonit-Primärfasern eine Länge von etwa 150 μm und einen mittleren Durchmesser von etwa 5 μm auf. Das Produkt konnte mittels Röntgen-diffraktometrie als Magnesiumoxid identifiziert werden.The product produced in this way was calcined at 1100 ° C. for 3 hours, fibrous magnesium oxide being obtained. Similar to the Nesquehonit primary fibers used, the synthesized fibers had a length of approximately 150 μm and an average diameter of approximately 5 μm. The product was identified as magnesium oxide by means of X-ray diffractometry.
B e i s p i e l 2 : Es wurde analog Beispiel 1 vorgegangen, wobei aber der nach vollständiger Reaktion und Filtration der Suspension erhaltene, mit Wasser gewaschene Filterkuchen bei einer Temperatur von 70°C 2 h im Vakuum getrocknet wurde. Die chemische Analyse ergab, daß sich ein Magnesiumneutralcarbonat mit der Produktzusammensetzung MgC03.2,4H20 gebildet hatte. Rasterelektronenmikroskopische Aufnahmen zeigten, daß das so erhaltene Produkt aus Fasern mit einer Länge von etwa 150 μm und einem durchschnittlichen Durchmesser von etwa 5 μm zusam¬ mengesetzt war.Example 2: The procedure was analogous to Example 1, but the filter cake obtained after the reaction and filtration of the suspension had been washed and washed with water was dried in vacuo at a temperature of 70 ° C. for 2 h. The chemical analysis showed that a magnesium neutral carbonate with the product composition MgC0 3 .2.4H 2 0 had formed. Scanning electron micrographs showed that the product thus obtained was composed of fibers with a length of approximately 150 μm and an average diameter of approximately 5 μm.
Das auf diese Weise hergestellte Produkt wurde mit einer Aufheizrate von 3° C/min auf eine Temperatur von 850° C gebracht und nach einer Haltezeit von 1 h ungeregelt abgekühlt. Dabei wurde eine faserförmige Substanz mit Faserlängen von ca. 150 μm und mittleren Faserdurchmessern von etwa 5 μm erhalten. Rönt- gendiffraktometrische Aufnahmen bestätigten, daß es sich bei dem Material um Magnesiumoxid handelte.The product manufactured in this way was treated with a Heating rate of 3 ° C / min brought to a temperature of 850 ° C and cooled uncontrolled after a holding time of 1 h. A fibrous substance with fiber lengths of approximately 150 μm and average fiber diameters of approximately 5 μm was obtained. X-ray diffractometric images confirmed that the material was magnesium oxide.
B e i s p i e l 3: Das als Nesquehonit, MgC03.3H20, identifi¬ zierte Produkt aus dem Beispiel 1 mit nadeiförmigem Kristallha¬ bitus wurde mit einer Aufheizrate von 5°C/min auf eine Tempera¬ tur von 1600° C gebracht und nach einer Haltezeit von 1 h unge¬ regelt abgekühlt. Das faserförmige Produkt konnte durch rönt- gendiffraktometrische Aufnahmen als Magnesiumoxid identifiziert werden. Ähnlich dem eingesetzten Nesquehonit betrugen die Fa¬ serlängen 50-150 μm, bei mittleren Faserdurchmessern von 2-5 μm.Example 3: The product from Example 1, identified as nesquehonite, MgC0 3 .3H 2 0, with acicular crystal halus was brought to a temperature of 1600 ° C. at a heating rate of 5 ° C./min a holding time of 1 h cooled in an uncontrolled manner. The fibrous product could be identified as magnesium oxide by X-ray diffractometric images. Similar to the nesquehonite used, the fiber lengths were 50-150 μm, with average fiber diameters of 2-5 μm.
B e i s p i e l 4: Das aus Beispiel 2 stammende Magnesiumneu¬ tralcarbonat mit der Produktzusammensetzung MgC03.2,4H20 wurde bei einer Aufheizrate von 10°C/min auf eine Temperatur von 400° C gebracht. Nach einer Haltezeit von 3 h wurde faserförmi- ges Magnesiumoxid erhalten. Die synthetisierten Fasern unter¬ schieden sich morphologisch nicht vom eingesetzten Magnesium¬ neutralcarbonat und zeigten Faserlängen von bis zu 150 μm und durchschnittliche Faserdurchmesser von etwa 3-5 μm. Röntgen- diffraktometrische Aufnahmen bestätigten, daß es sich bei dem Material um Magnesiumoxid handelte.Example 4: The magnesium neutral carbonate from Example 2 with the product composition MgC0 3 .2.4H 2 0 was brought to a temperature of 400 ° C at a heating rate of 10 ° C / min. After a holding time of 3 hours, fibrous magnesium oxide was obtained. The fibers synthesized did not differ morphologically from the magnesium neutral carbonate used and showed fiber lengths of up to 150 μm and average fiber diameter of about 3-5 μm. X-ray diffractometric images confirmed that the material was magnesium oxide.
B e i s p i e l 5: Einsatz der MgO-Fasern zur Erhöhung der Festigkeiten von Verbundwerkstoffen: Die gemäß Beispiel 1 er¬ haltenen MgO-Fasern wurden ebenso wie Siliziumcarbid-Whisker und kommerziell erhältliches Magnesiumoxid bei Zusatzmengen von 4 Vol.% in ein Epoxidharz eingebettet und an Prüfkörpern die Biegebruchfestigkeit ermittelt. Die Ergebnisse der Untersuchun¬ gen sind in Tabelle I zusammengefaßt. Es zeigt sich, daß mit den erfindungsgemäßen MgO-Fasern bereits bei den geringen Zu¬ satzmengen eine signifikante Erhöhung der Biegebruchfestigkeit der Verbundwerkstoffe eintritt. Vergleicht man die Biegebruch¬ festigkeiten der Verbundwerkstoffe untereinander bzw. mit dem reinen Epoxidharz, so errechnet sich unter Zugrundelegung der Mischungsregel und der Annahme einer isotropen Verteilung der Fasern in der Matrix eine Eigenfestigkeit der erfindungsgemäßen MgO-Fasern von etwa 7000 bis 8000 MPa.EXAMPLE 5 Use of the MgO Fibers to Increase the Strengths of Composites: The MgO fibers obtained according to Example 1, like silicon carbide whiskers and commercially available magnesium oxide, were embedded in an epoxy resin with addition amounts of 4% by volume and on test specimens the bending strength is determined. The results of the tests are summarized in Table I. It can be seen that with the MgO fibers according to the invention there is a significant increase in the bending strength of the composite materials even with the small amounts added. If one compares the flexural strengths of the composite materials with one another or with that pure epoxy resin, the intrinsic strength of the MgO fibers according to the invention of about 7000 to 8000 MPa is calculated on the basis of the mixing rule and assuming an isotropic distribution of the fibers in the matrix.
T a b e l l e IT a b e l l e I
Festigkeiten von Verbundwerkstoffen mit 4 Vol.% FüllstoffStrengths of composite materials with 4 vol.% Filler
Matrix Verstärkungskomponente Biegebruchfestigkeit MPaMatrix reinforcement component bending strength MPa
Epoxidharz - 44Epoxy resin - 44
Epoxidharz Siliziumcarbid-Whisker 84Epoxy resin silicon carbide whisker 84
Epoxidharz erfindungsgemäße MgO- 62Epoxy resin MgO-62 according to the invention
FasernFibers
Epoxidharz kommerzielles MgO 49 Epoxy resin commercial MgO 49

Claims

P a t e n t a n s p r ü c h e Patent claims
1. Verfahren zur Herstellung von faserförmigem Magnesium¬ oxid, bei dem ein in Form nadeiförmiger Teilchen vorliegendes, Magnesium und Kristallwasser enthaltendes Material durch Calci¬ nieren in das faserförmige Magnesiumoxid umgewandelt wird, da¬ durch gekennzeichnet, daß als zu calcinierendes Material ein oder mehrere kristallwasserhaltige Magnesiumneutralcarbonate, welche der Formel MgC03.xH20 entsprechen, wobei 1 ≤ x ≤ 5 ist, insbesondere Magnesiumcarbonat-Trihydrat, verwendet werden.1. A process for the production of fibrous magnesium oxide, in which a material in the form of acicular particles containing magnesium and water of crystallization is converted into the fibrous magnesium oxide by calcining, characterized in that one or more water of crystallization is used as the material to be calcined Magnesium neutral carbonates, which correspond to the formula MgC0 3 .xH 2 0, where 1 ≤ x ≤ 5, in particular magnesium carbonate trihydrate.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das zu calcinierende Material bei einer unter 100°C liegenden Temperatur im Vakuum getrocknet bzw. teilweise entwässert wird.2. The method according to claim 1, characterized in that the material to be calcined is dried at a temperature below 100 ° C in a vacuum or partially dewatered.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeich¬ net, daß das Calcinieren bei einer zwischen 350 und 2000°C lie¬ genden Temperatur, vorzugsweise zwischen 800 und 1600°C, vorge¬ nommen wird.3. The method according to claim 1 or 2, characterized gekennzeich¬ net that the calcining at a lying between 350 and 2000 ° C lying temperature, preferably between 800 and 1600 ° C, vorge¬ is taken.
4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch ge¬ kennzeichnet, daß beim Calcinieren das Aufheizen des zu calci- nierenden Materials mit einer unter 10°C/min liegenden Rate vorgenommen wird. 4. The method according to any one of claims 1 to 3, characterized ge indicates that during calcining, the heating of the material to be calcined is carried out at a rate below 10 ° C / min.
PCT/AT1991/000041 1990-03-22 1991-03-07 Process for manufacturing fibrous magnesium oxide WO1991014659A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP3506244A JPH0723216B2 (en) 1990-03-22 1991-03-07 Method for producing fibrous magnesium oxide
KR1019910701362A KR920701045A (en) 1990-03-22 1991-03-07 Fibrous Magnesium Oxide Manufacturing Method
NO91914560A NO914560L (en) 1990-03-22 1991-11-21 PROCEDURE FOR THE PREPARATION OF FIBER-MAGNESIUM OXIDE

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ATA682/90 1990-03-22
AT0068290A AT393677B (en) 1990-03-22 1990-03-22 METHOD FOR PRODUCING FIBROUS MAGNESIUM OXIDE

Publications (1)

Publication Number Publication Date
WO1991014659A1 true WO1991014659A1 (en) 1991-10-03

Family

ID=3497042

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AT1991/000041 WO1991014659A1 (en) 1990-03-22 1991-03-07 Process for manufacturing fibrous magnesium oxide

Country Status (9)

Country Link
EP (1) EP0473762A1 (en)
JP (1) JPH0723216B2 (en)
KR (1) KR920701045A (en)
AT (1) AT393677B (en)
AU (1) AU7546991A (en)
BR (1) BR9105100A (en)
CA (1) CA2056992A1 (en)
HU (1) HUT60223A (en)
WO (1) WO1991014659A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2418241B1 (en) 2010-08-12 2016-02-17 Bene_fit Systems GmbH & Co. KG Filling material for compound materials containing magnesium carbonate, method for its production and application
JP6284099B2 (en) * 2014-03-05 2018-02-28 国立研究開発法人産業技術総合研究所 Resin composition for dielectric and high frequency dielectric device

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3371993A (en) * 1964-12-21 1968-03-05 Corning Glass Works Method of making magnesium oxide fibers
EP0132610A1 (en) * 1983-06-27 1985-02-13 Kyowa Chemical Industry Co., Ltd. Fibrous magnesium oxide and process for production thereof

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63162560A (en) * 1986-12-25 1988-07-06 三菱マテリアル株式会社 Magnesia whisker reinforced inorganic material

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3371993A (en) * 1964-12-21 1968-03-05 Corning Glass Works Method of making magnesium oxide fibers
EP0132610A1 (en) * 1983-06-27 1985-02-13 Kyowa Chemical Industry Co., Ltd. Fibrous magnesium oxide and process for production thereof

Also Published As

Publication number Publication date
AU7546991A (en) 1991-10-21
ATA68290A (en) 1991-05-15
EP0473762A1 (en) 1992-03-11
AT393677B (en) 1991-11-25
HU914085D0 (en) 1992-07-28
JPH0723216B2 (en) 1995-03-15
HUT60223A (en) 1992-08-28
KR920701045A (en) 1992-08-11
JPH04503797A (en) 1992-07-09
BR9105100A (en) 1992-06-02
CA2056992A1 (en) 1991-09-23

Similar Documents

Publication Publication Date Title
DE3305057C2 (en) Process for making silicon carbide whiskers
DE19701771B4 (en) Method for producing hexagonal boron nitride powder
DE69634164T2 (en) Aluminum oxide particles with increased dispersibility and plasticity and process for their preparation
DE3633309A1 (en) STABILIZED METAL OXIDES
DE2613651C2 (en) Process for the production of prismatic and needle-shaped alpha hemihydrate plaster of paris
EP0394670B1 (en) Process for the preparation of dawsonite
EP0143363B1 (en) Calcite filling matter and process for its production
DE3006262A1 (en) TITANIC ACID METAL SALTS AND METHOD FOR THE PRODUCTION THEREOF
DE3937640A1 (en) ZIRCONDIOXIDE POWDER, METHOD FOR THE PRODUCTION THEREOF, ITS USE AND SINTER BODY MADE FROM IT
DE2906759A1 (en) MAGNESIUM HYDROXIDE WITH A HEXAGONAL CRYSTAL STRUCTURE AND THE METHOD FOR PRODUCING IT
DE1571354C3 (en) Manufacture of refractory bodies
DE3100554A1 (en) HIGH-PURITY SILICON NITRIDE AND METHOD FOR THE PRODUCTION THEREOF
DE2854722C2 (en) Process for the production of fibrous and / or spherical α-calcium sulfate hemihydrate
DE3213683A1 (en) METHOD FOR PRODUCING FERRITES FROM IRON (II) SULFATE
AT393677B (en) METHOD FOR PRODUCING FIBROUS MAGNESIUM OXIDE
DE3100942A1 (en) METHOD FOR PRODUCING CRYSTALLINE SODIUM SILICATES AND CRYSTALLIZED FORMS OF HYDRATED SILICON DIOXIDE AND THEIR USE
DE1592492B1 (en) Process for the production of ferromagnetic chromium dioxide
EP0421076A1 (en) Zirconium dioxide powder, process for its preparation, its use and sintered bodies prepared therefrom
DE2848452A1 (en) METHOD FOR MANUFACTURING SILICON CARBIDE POWDER
DE2708861C3 (en) Process for the production of a carbonate from aluminum and an alkali or alkaline earth metal l
DE3623734A1 (en) METHOD FOR PRODUCING MULLITE WITH A HIGH PURE PURITY
DE4322579C1 (en) Ternary element compounds in the system Al-B-P, process for their preparation and their use
DE1592492C (en) Process for the production of ferromagnetic chromium dioxide
DE102008040930B4 (en) Process for the preparation of doped vanadium oxide nanotubes
DE2141287A1 (en) Oxidation catalyst and process for its preparation

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AT AU BB BG BR CA CH DE DK ES FI GB HU JP KP KR LK LU MC MG MW NL NO PL RO SD SE SU US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE BF BJ CF CG CH CM DE DK ES FR GA GB GR IT LU ML MR NL SE SN TD TG

WWE Wipo information: entry into national phase

Ref document number: 1991906525

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: 2056992

Country of ref document: CA

WWP Wipo information: published in national office

Ref document number: 1991906525

Country of ref document: EP

WWW Wipo information: withdrawn in national office

Ref document number: 1991906525

Country of ref document: EP