DE2616775B2 - Method of increasing the strength of alumina - Google Patents

Method of increasing the strength of alumina

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Publication number
DE2616775B2
DE2616775B2 DE2616775A DE2616775A DE2616775B2 DE 2616775 B2 DE2616775 B2 DE 2616775B2 DE 2616775 A DE2616775 A DE 2616775A DE 2616775 A DE2616775 A DE 2616775A DE 2616775 B2 DE2616775 B2 DE 2616775B2
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Germany
Prior art keywords
strength
increasing
oil
emulsion
alumina
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DE2616775A
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German (de)
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DE2616775A1 (en
Inventor
Rudolf Dipl.-Ing. 8501 Heroldsberg Stolz
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Individual
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Priority to DE2616775A priority Critical patent/DE2616775B2/en
Publication of DE2616775A1 publication Critical patent/DE2616775A1/en
Publication of DE2616775B2 publication Critical patent/DE2616775B2/en
Withdrawn legal-status Critical Current

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    • 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
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/02—Inorganic materials
    • A61L27/04—Metals or alloys
    • A61L27/047—Other specific metals or alloys not covered by A61L27/042 - A61L27/045 or A61L27/06
    • 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
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/021—After-treatment of oxides or hydroxides
    • 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
    • C04B35/10—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 aluminium oxide
    • 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
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
    • C04B41/46—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with organic materials
    • C04B41/47—Oils, fats or waxes natural resins
    • 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
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
    • C04B41/81—Coating or impregnation
    • C04B41/82—Coating or impregnation with organic materials

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Epidemiology (AREA)
  • Geology (AREA)
  • Dermatology (AREA)
  • Medicinal Chemistry (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Transplantation (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Materials For Medical Uses (AREA)

Description

ilfe eines spezifiDie im folgenden näher beschriebene Erfindung bezieht sich auf ein Verfahren zur Erhöhung der F/»C t ICrL·*»! t \Jr\T\ Δ liirriiniiimnvifJ w-r The invention described in more detail below relates to a method for increasing the F / »C t ICrL · *»! t \ Jr \ T \ Δ liirriiniiimnvifJ wr

sehen Abschreckungsverfahrens.see deterrent proceedings.

Den Ausführungen in der deutschen Patentschrift 8 42 467 kann entnommen werden, daß es bereits bekannt ist, bei gemischtkristallinen Werkstoffen (Steatit plus Siliciumkarbid) eine Steigerung der Festigkeit durch Abschreckung zu erreichen. Diese vorbekannten Arbeiten beziehen sich aber ausdrücklich nur auf gemischtkristalline keramische Werkstoffe, da dort verschiedene Kristallarten unter Volumenzunahme innere Spannungen hervorrufen und eine Festigkeitserhöhung bewirken.The statements in German Patent 8 42 467 can be seen that it is already is known, in mixed crystalline materials (steatite plus silicon carbide) an increase in Achieving strength through quenching. However, these previously known works relate expressly only on mixed crystalline ceramic materials, as there are different types of crystals with an increase in volume cause internal tension and increase strength.

Bei der vorliegenden Erfindung handelt es sich dagegen um die Härtung von oxidkeramischen Stoffen, in erster Linie um Aluminiumoxid. Bei diesen Materialien kommt während des gesamten Herstellungsprozesses nur eine einzige Kristallart vor. Dabei besteht der Mechanismus zur Erhöhung der Festigkeit aus einem ganz anderen Verlauf, als wie er in der Patentschrift 8 42 467 beschrieben ist.The present invention, on the other hand, concerns the hardening of oxide ceramic materials, primarily about aluminum oxide. These materials come into play throughout the manufacturing process only a single type of crystal. The mechanism for increasing the strength consists of one completely different course than that described in patent specification 8 42 467.

Betrachtet man während eines Abschreckungsvorganges einer zylinderförmigen Aluminiumoxidprobe Mantel und Kern der Probe in ihrem zeitlichen Abkühlverhalten, so ist leicht einzusehen, daß der Mantel schneller abkühlt als der Kern. Die dadurch bedingte, örtlich verschiedene Volumenkontraktion ruft in der ersten Abkühlphase im Kern Druckspannungen, im Mantel Zugspannungen hervor, wobei im noch heißen Kern die Warmstreckgrenze erreicht wird und ein ausgeprägtes Fließen auftritt. Im Laufe der Abkühlung erkaltet auch der Kern. Die Spannungen kehren sich nun in ihrem Vorzeichen um, da der innere Kern im noch heißen Zustand durch einen Fließvorgang dem Druck ausgewichen war; der sofort abgekühlte Mantel konnte jedoch nicht fließen. Das heißt mit anderen Worten, daß die zuletzt im Kern abkühlenden Werkstoffteilchen durch die schon erkalteten Mantelzonen am Kontrahieren behindert werden.Looking at a cylindrical aluminum oxide sample during a quenching process The sheath and core of the sample in terms of their cooling behavior over time, it is easy to see that the Coat cools faster than the core. The locally different volume contraction caused by this calls In the first cooling phase compressive stresses in the core, tensile stresses emerge in the cladding, whereby im still hot core, the hot yield point is reached and pronounced flow occurs. During the Cooling down also cools the core. The tensions are now reversed in their sign, since the inner one The core had evaded the pressure by a flowing process while it was still hot; the one that cooled down immediately Coat could not flow, however. In other words, the last to cool down in the core Material particles are prevented from contracting by the jacket zones that have already cooled down.

Der Mantel steht daher nach dem Erkalten unter Druckspannungen und der Kern unter Zugspannungen. Diese Druckspannungen in der Oberfläche erhöhen die Festigkeit im Werkstoff, da sie verhindern, daß sich an der Oberfläche ein Anriß bildet. Dieser Mechanismus wurde experimentell nachgeprüft, das heißt, die verbliebenen Oberflächenspannungen wurden nach der Methode der Röntgenpeakverschiebung bestimmt.After cooling, the jacket is therefore under compressive stresses and the core under tensile stresses. These compressive stresses in the surface increase the strength in the material because they prevent it from adhering the surface forms a crack. This mechanism has been verified experimentally, that is, the The remaining surface tensions were determined by the X-ray peak shift method.

Kirchner (Journal of Applied Physics, Vol. 42, Nr. 10, Sept. 71; H. P. K i r c h η e r, R. E. W a I k e r und D. R. Platts, »Strengthening Aluminia by Quenching in various Media«) hat verschiedene Abschreckmedien geprüft, beispielsweise Preßluft, Heliumgas, Kohlendioxidgas, Siliconöle, Motoröle. Kerosen und Wasser. Dabei stellte sich heraus, daß Siliconöl eine Festigkeitssteigerung von über 100% hervorruft, Gase eine vergleichsweise geringere. Bei Wasser gingen alle Proben während des Abschreckvorganges zu Bruch.Kirchner (Journal of Applied Physics, Vol. 42, No. 10, Sept. 71; H. P. K i r c h η e r, R. E. W a I k e r and D. R. Platts, “Strengthening Aluminia by Quenching in various media «) has tested various quenching media, for example compressed air, helium gas, carbon dioxide gas, Silicone oils, motor oils. Kerosene and water. It turned out that silicone oil causes an increase in strength of over 100%, gases one comparatively lower. In the case of water, all samples broke during the quenching process.

Die von Kirchner angegebenen Versuche wurden nachvollzogen, wobei sich ein großer Nachteil herausstellte: Schon während der Abschreckversuche gingen 60—70% der Proben durch Schockwirkung zu Bruch und konnten nicht auf ihre Festigkeit geprüft werden.The attempts indicated by Kirchner were understood, whereby a big disadvantage turned out: Already during the deterrent attempts went 60-70% of the samples broke due to shock and could not be tested for their strength.

Daraus ergibt sich, daß die wirtschaftlicht Nutzung der betreffenden Materialien für die Herstellung von Schaltern, Isolatoren und sonstigen elektrotechnischen Bauelementen allein von einem Abschreckmedium abhängt, das dem Werkstoff cmc große resiigkeiiserhöhurig vermittelt, ihn aber nicht durch thermische Schockwirkung zu Bruch gehen läßt.It follows that the economical use of the materials concerned for the manufacture of Switches, insulators and other electrotechnical components solely from a quenching medium depends on the resiigkeiiserhöhurig the material cmc mediated, but does not allow it to break due to the thermal shock effect.

Die wirtschaftliche Nutzung drückt sich zum einen in Materialersparnis, zum anderen durch Energieersparnis aus. Dies kann jedoch nur gewährleistet werden, wenn wahrend des Abschreckvorganges möglichst wenig Material zu Bruch geht.The economic use is expressed on the one hand in material savings and on the other hand in energy savings the end. However, this can only be guaranteed if as little as possible during the quenching process Material breaks.

Das erfindungsgemäße Verfahren zur Erhöhung der Festigkeit von Aluminiumoxid wird folgendermaßen gehandhabt:The method of the present invention for increasing the strength of alumina is as follows handled:

Kant- und Rundproben werden in einem Temperaturbereich von 800—17000C in einem Ofen in oxydierender Atmosphäre erhitzt und beim Erreichen der jeweils gewünschten Temperatur in das wassergekühlte Abschreckmedium fallen gelassen.Edging and circular samples are heated in a temperature range of 800-1700 0 C in an oven in an oxidizing atmosphere and dropped upon reaching the respective desired temperature in the water-cooled quench.

Dieses Medium hat Zimmertemperatur und besieht erfindungsgemäß aus einer Emulsion aus organischem oder anorganischem öl und V/asser oder aus öl und einer Flüssigkeit, die nur einen geringen Anteil an Wasser besitzt (beispielsweise wäßrige Lösungen aller Art wie Salzlösungen oder flüssig-flüssig Lösungen und Mischungen). Es kann auch Öl und Essigsäure, öl und Ameisensäure, öl und Tetrachlorkohlenstoff oder auch geschmolzenes Bleioxid verwendet werden. Die Anwesenheit von Feststoffen jeglicher Art beeinflußt die Wirkung der betreffenden Emulsion in keiner Weise.This medium has room temperature and, according to the invention, consists of an emulsion of organic or inorganic oil and water or from oil and a liquid that has only a small proportion of water (for example aqueous solutions of all Kind like salt solutions or liquid-liquid solutions and mixtures). It can also include oil and acetic acid, oil and Formic acid, oil and carbon tetrachloride or even molten lead oxide can be used. the The presence of solids of any kind does not affect the effect of the emulsion in question in any way.

Die so behandelten Aluminiumoxidproben wurden dann wie allgemein üblich auf einer B;^gemaschine auf ihre Biegefestigkeit untersucht.The aluminum oxide samples treated in this way were then, as is generally customary, on a B ; ^ machine examined for its flexural strength.

So wurden beispielsweise bei einer Abschrecktemperatur von I55O°C eine Biegefestigkeit von 883,78 MN/m2 erzielt, bei einer Ausgangsfestigkeit von 380.15 MN/m2, wobei bei einer Probenserie von 50 Proben keine einzige zu Bruch ging.For example, at a quenching temperature of 150 ° C., a flexural strength of 883.78 MN / m 2 was achieved, with an initial strength of 380.15 MN / m 2 , with not a single one breaking in a sample series of 50.

Durch den oben beschriebenen Abschreckvorgang in öligen Emulsionen findet neben der enormen Festigkeitssteigerung (132%) auch noch eine Diffusion von Kohlenstoff auf bzw. in die Probenoberflächc statt. Diese Diffusion entsteht aus dem sich z.ersetzcnden öl bei hohen Temperaturen und ist besonders für die biomedizinische Technik interessant.The above-described quenching process in oily emulsions results in an enormous increase in strength (132%) diffusion of carbon on or into the sample surface also took place. This diffusion arises from the decomposing oil at high temperatures and is of particular interest for biomedical engineering.

Claims (3)

Patentansprüche:Patent claims: 1. Verfahren zur Steigerung der Festigkeit von Formkörpern aus Aluminiumoxid durch Erhitzen in oxydierender Atmosphäre auf 800—1700°C und anschließendem Abschrecken in einem kühlenden Medium, dadurch gekennzeichnet, daß eine Emulsion aus öl und Wasser als Abschrekkungsmedium dient.1. Process for increasing the strength of molded bodies made of aluminum oxide by heating in oxidizing atmosphere to 800-1700 ° C and subsequent quenching in a cooling Medium, characterized in that an emulsion of oil and water is used as the deterrent medium serves. 2. Verfahren nach Anspruch I. dadurch gekennzeichnet, daß die Äbschreckungsemulsion aus öl und wäßrigen Lösungen jeglicher Art besteht.2. The method according to claim I. characterized in that the deterrent emulsion of oil and aqueous solutions of any kind. 3. Verfahren nach Anspruch I oder 2, dadurch gekennzeichnet, daß der jeweiligen Emulsion Feststoffe jeglicher Art beigemengt sind.3. The method according to claim I or 2, characterized in that the respective emulsion solids of any kind are added.
DE2616775A 1976-04-15 1976-04-15 Method of increasing the strength of alumina Withdrawn DE2616775B2 (en)

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DE2616775B2 true DE2616775B2 (en) 1978-12-14

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2463107A1 (en) * 1979-08-06 1981-02-20 Nippon Kokan Kk PROCESS FOR PREVENTING THE THERMAL BURST OF CERAMIC PRODUCTS

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2463107A1 (en) * 1979-08-06 1981-02-20 Nippon Kokan Kk PROCESS FOR PREVENTING THE THERMAL BURST OF CERAMIC PRODUCTS

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Publication number Publication date
DE2616775A1 (en) 1977-10-20

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