EP1259341A2 - Method for production of an oxidation inhibiting titanium casting mould - Google Patents

Method for production of an oxidation inhibiting titanium casting mould

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Publication number
EP1259341A2
EP1259341A2 EP01919141A EP01919141A EP1259341A2 EP 1259341 A2 EP1259341 A2 EP 1259341A2 EP 01919141 A EP01919141 A EP 01919141A EP 01919141 A EP01919141 A EP 01919141A EP 1259341 A2 EP1259341 A2 EP 1259341A2
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EP
European Patent Office
Prior art keywords
mold
investment
weight
temperature
furnace
Prior art date
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Application number
EP01919141A
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German (de)
French (fr)
Other versions
EP1259341B1 (en
Inventor
Sandor Cser
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Individual
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Individual
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Priority to DK01919141T priority Critical patent/DK1259341T3/en
Publication of EP1259341A2 publication Critical patent/EP1259341A2/en
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Publication of EP1259341B1 publication Critical patent/EP1259341B1/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C7/00—Patterns; Manufacture thereof so far as not provided for in other classes
    • B22C7/02—Lost patterns
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/02—Sand moulds or like moulds for shaped castings
    • B22C9/04—Use of lost patterns
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/12—Treating moulds or cores, e.g. drying, hardening

Definitions

  • the invention relates to various processes for the production of lost molds for titanium casting.
  • Workpieces made of cast titanium are increasingly used in technology due to the excellent material properties and the relatively low price of titanium.
  • titanium is also increasingly used in the field of dental technology applications.
  • the procedure for producing a mold for titanium casting is basically known.
  • a model of the workpiece to be cast must be modeled.
  • a specially suitable wax is preferably used, since it can be easily modeled and later in a simple manner after being embedded in the investment material
  • a casting channel made of wax wire is molded onto the model, whereby depending on the size of the models, several models can be connected to one another for a mold.
  • the model is then fastened in a muffle ring or a muffle, whereby various aids such as cast rings and / or cast funnel formers can be used.
  • the embedding Mix the mass and pour it into the muffle so that the model is enclosed as a lost core and the desired shape m of the embedding mass is negatively molded.
  • the embedding mass is heated in a kiln according to a specified temperature-time profile and then cooled again.
  • the embedding mass hardens and the meltable material of the model is burned out of the mold.
  • the liquid titanium can be poured into the mold immediately, so that the desired titanium casting is obtained
  • the object of the present invention is therefore to propose methods for producing a lost mold for titanium casting, which allow the production of titanium casting workpieces with a lower surface oxidation.
  • This object is achieved by methods according to claims 1 to 9
  • Commercially available investment materials for titanium casting consist of a mixture of different oxides, with aluminum oxide (Al 2 O 3 ) and magnesium oxide (MgO) in particular being present in larger proportions.
  • the investment contains at least one further oxidizable component, which in many cases consists of zirconium.
  • the zirconium is said to keep oxygen away from the titanium melt.
  • this effect is only insufficiently achieved since the zirconium is contaminated with oxygen as soon as the mold is fired.
  • the methods according to the invention are based on the common basic idea of at least limiting the contamination of the zirconium, in particular with oxygen, during the curing of the investment.
  • the result of this is that as much unused zirconium is available during the titanium casting and a larger amount of oxygen can be bound to the zirconium in the contact area between the titanium surface and the surface of the mold cavity. This can reduce the amount of oxygen that is available for the oxidation of the titanium.
  • a first possibility for producing the mold is if the mold is hardened under a protective gas atmosphere, so that in particular the oxidation of the oxidizable component of the investment is at least reduced.
  • the furnace can be flushed with argon when the investment is hardening.
  • protective gas can be introduced into the interior of the mold so that the mold cavity is flushed with protective gas.
  • the same effect of reducing the oxidation of the investment during curing can also be achieved if the curing of the Mold takes place in an atmosphere with reduced gas density.
  • a negative pressure or vacuum can be built up in the furnace when the bed material hardens. Due to the reduced gas density in the furnace interior, fewer oxygen atoms are available for oxidation, so that oxidation processes are reduced overall
  • the relative degree of oxidation of the embedding composition ie the ratio of the Oxidized bed material to a proportion of the oxidized bed material largely depends on the temperature at which the bed material is exposed to a certain gas density for how long.High temperatures, high gas densities and a long exposure time result in high degrees of oxidation as a result of reducing the exposure time of high temperatures to the bed material the oxidation of the oxidizable constituents of the bed material can thus be reduced
  • the holding time during which the temperature in the furnace interior is kept largely constant after reaching a maximum temperature (for example 850 ° C), must be adapted to the amount of bed material used. Due to the high temperature in the interior of the furnace, there is a problem during the holding time Low gas density in the furnace interior, that the oxidation of the bed mass is relatively low during this time. By cooling the furnace interior after the end of the holding time, the gas density in the furnace interior rises again strongly.
  • the shape is therefore after reaching and maintaining a maximum temperature, ie after the holding time has passed to the maximum temperature. actively cooled to reduce the cooling time.
  • the cooling should be just strong enough to prevent the mold from tearing due to excessive temperature stress.
  • Cooling room-warm air is supplied from the ambient atmosphere. This can be achieved, for example, by not simply switching off the oven after the end of the holding time and slowly cooling the mold in the closed interior of the oven, but instead opening the oven after switching off the heating and thereby exchanging the atmosphere in the interior of the oven with the warm ambient temperature , Of course, other aids such as fans, which ensure a forced flow, can also be used to reinforce the cooling with the ambient air.
  • a further reduction in the oxidation of the investment can be achieved if the mold is cooled by supplying protective gas to the process-relevant area of the mold. By purging with the cooler shielding gas, the mold is cooled on the one hand and oxidation processes are avoided by displacing atmospheric oxygen.
  • Another possibility to have a positive influence on the degree of oxidation of the investment material is to heat the kiln with a heating rate of at least 7 ° C per minute or faster when the mold hardens until the maximum temperature is reached. Since heating is normally only at 6 ° C per minute, the result is This measure means that the maximum temperature is reached more quickly, which in turn reduces the dwell time of the investment material during the heating phase in the heated furnace.
  • the casting object is first modeled and fastened to a casting funnel former in a muffle ring or the like by means of casting channels made of a suitable material, for example wax.
  • the investment material is then mixed with a prescribed amount of mixing liquid, for example water, and poured into the muffle, the cast object being completely enclosed and the desired shape thereby negatively reflected in the investment material.
  • the muffle with the cast funnel former is pressurized in a pressure pot in order to further compact the investment.
  • the investment is cured for at least 30 minutes at room temperature and then the casting funnel former is removed.
  • the muffle is then placed in a cold furnace and the furnace is heated up to a temperature of 850 ° C at a rate of at least 7 ° C per minute.
  • This holding temperature is then kept constant for about 30 minutes.
  • the furnace is then switched off and the interior of the furnace is cooled by opening the furnace door for approx. 15 minutes.
  • the mold is placed on the edge of the furnace opening or on the furnace flap to increase the cooling. Again, the mold is left to cool for about 15 minutes at this point.
  • the mold is then placed outside the furnace and again left to stand until the desired temperature for the casting process is reached. This completes the method according to the invention for producing the titanium casting mold
  • the liquid titanium is poured into the mold cavity, for example at approximately 150 ° C., before the mold has completely cooled.
  • the proposed method can also be carried out if individual or several of the above-mentioned method parameters are modified or omitted entirely.
  • the individual method steps are carried out automatically in a suitable device. This saves personnel costs and increases the reproducibility of the results.
  • a particularly suitable formulation of the investment consists of 0 to 1% Si 2 O 2 , 0 to 1% TiO 2 , 10 to 40% Al 2 O 3 , 0 to 2% Fe 2 O 3 , 0 to 1% MnO , 40 to 80% MgO, 2 to 10% CaO, 0 to 2% Na 2 O, 0 to 1% K 2 O, 0 to 1% P 2 O 5 and 0 to 5% Zr.
  • the proportion of the individual components can be varied within the range limits, which are given in percent by weight. Additional components can also be added, and individual components can be replaced by other substances with similar properties.
  • the methods according to the invention can be used for the production of any type of molds which are intended for titanium casting. It is particularly advantageous to use the method according to the invention for the production of molds for dental cast titanium, since particularly high demands are made on the quality of the castings to be produced in this technical field of application.
  • 1 shows the course of the temperature or gas density over time in a manufacturing method according to the invention in comparison with a conventional manufacturing method; 2 shows the course of the increase in the relative degree of oxidation of an embedding compound during the hardening process
  • FIG. 1 the temperature or the relative gas density over time is plotted during the hardening of the bed material in the kiln.
  • Graph 1 shows the temperature profile in a combustion method known from the prior art.
  • Graph 2 shows the associated profile of the Relative gas density in the furnace over time In comparison, graphs 3 and 4 show the temperature curve or the curve of the relative gas density over time, as can be measured in a method according to the invention.
  • the holding temperature of 850 ° C is reached faster by using a higher heating rate than with the conventional method
  • the duration of the holding time, during which the holding temperature of 850 ° C is kept constant in the oven, is only reduced by a few minutes.
  • the main difference between the two graphs 1 and 3 is that in the invention Process the temperature curve after the end of the holding time by active cooling, for example by opening the oven door, is brought back to room temperature in a relatively short time, so that oxidation processes are largely suppressed.In contrast to this, the temperature in the conventional process according to Graph 1 only drops very much slowly
  • the graphs for the relative gas density 2 and 4 show that the relative gas density is inversely proportional to the temperature in the furnace. As soon as the temperature at the holding temperature reaches its maximum, the relative gas density reaches its minimum at approx. 25% only with If the temperature in the furnace drops, the relative gas density rises again, the relative gas density according to graph 4 in the method according to the invention increasing very much faster, since the temperature in the furnace falls more sharply 1 that the oxidation of the bed material can be reduced overall by reducing the duration of exposure to atmospheric oxygen at high temperatures
  • FIG. 2 shows a diagram in which the relative degree of oxidation of the embedding mass is entered over time during the hardening process.
  • Graph 5 conventional method
  • Graph 6 method according to the invention
  • the relative degree of oxidation rises very high.
  • the casting temperature in the bed material is 150 in the process according to the invention ° C already reached after approx. V. to 2 hours depending on the amount, so there The relative degree of oxidation at this point in time only reached about 25% compared to 100% with conventional curing

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Dental Prosthetics (AREA)
  • Mold Materials And Core Materials (AREA)
  • Dental Preparations (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Continuous Casting (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Adornments (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)

Abstract

A method for producing a lost mold for titanium casting from a curable embedding compound. The embedding compound contains at least one oxidizable ingredient, such as zirconium. A model of an object to be cast is prepared from a material which can be melted out of the embedding compound. A mold is shaped by embedding the model in the embedding compound. The mold is cured and the embedding compound melted out by heating and holding the mold at a maximum temperature for a period of time. The mold is actively cooled to reduce the cooling time. Preferred embedding compound compositions and time-temperature profiles are disclosed.

Description

Verfahren zur Herstellung einer oxidationshemmenden Titangussform Process for producing an antioxidant titanium casting mold
Die Erfindung betrifft verschiedene Verfahren zur Herstellung von verlorenen Formen für den Titanguss. Werkstücke aus Titanguss werden überall in der Technik aufgrund der hervorragenden Werkstoffeigenschaften und des relativ geringen Preises von Titan zunehmend eingesetzt. Insbesondere auch im Bereich der zahntechnischen Anwendungen findet Titan immer größere Verwendung.The invention relates to various processes for the production of lost molds for titanium casting. Workpieces made of cast titanium are increasingly used in technology due to the excellent material properties and the relatively low price of titanium. In particular, titanium is also increasingly used in the field of dental technology applications.
Die Vorgehensweise zur Herstellung einer Form für den Titanguss ist dabei grundsätzlich bekannt. Zunächst muss ein Modell des später zu gießenden Werkstücks ausmodelliert werden. Dazu wird vorzugsweise ein speziell geeignetes Wachs verwendet, da dieses gut modellierbar ist und später nach dem Einbetten in die Einbettmasse in einfacher Art undThe procedure for producing a mold for titanium casting is basically known. First, a model of the workpiece to be cast must be modeled. For this purpose, a specially suitable wax is preferably used, since it can be easily modeled and later in a simple manner after being embedded in the investment material
Weise ausgebrannt werden kann. Nach dem Ausmodellieren wird an dem Modell ein Gusskanal aus Wachsdraht angeformt, wobei dabei j e nach Größe der Modelle mehrere Modelle für eine Form miteinander verbunden werden können. Danach wird das Modell in einem Muffelring bzw. einer Muffel befestigt, wobei verschiedene Hilfsmittel wie Gussringe und/oder Gusstrichterformer verwendet werden können. Danach wird die Einbett- masse angerührt und in die Muffel eingefüllt, so dass das Modell als verlorener Kern umschlossen wird und die gew nschte Form m der Embettmasse negativ abformt Danach wird die Einbettmasse m einem Brennofen gemäß einem vorgegebenen Temperatur-Zeit-Profil aufgeheizt und wieder abgekühlt Dabei härtet die Embettmasse aus und der ausschmelzbare Werkstoff des Modells wird aus der Form ausgebrannt Nachdem die Form ausreichend abgekühlt ist, kann sofort das flussige Titan m die Form eingegossen werden, so dass im Ergebnis das gewünschte Titangussteil erhalten wirdWay can be burned out. After modeling, a casting channel made of wax wire is molded onto the model, whereby depending on the size of the models, several models can be connected to one another for a mold. The model is then fastened in a muffle ring or a muffle, whereby various aids such as cast rings and / or cast funnel formers can be used. Then the embedding Mix the mass and pour it into the muffle so that the model is enclosed as a lost core and the desired shape m of the embedding mass is negatively molded.Then the embedding mass is heated in a kiln according to a specified temperature-time profile and then cooled again. The embedding mass hardens and the meltable material of the model is burned out of the mold. After the mold has cooled sufficiently, the liquid titanium can be poured into the mold immediately, so that the desired titanium casting is obtained
Eine der größten Nachteile des Werkstoffs Titan stellt seine relativ hohe Oxidationsneigung dar Beim Gießen von Titan neigt dieser Werkstoff dazu, an der Oberflache eine Oxidationsschicht zu bilden, die für die meisten Anwendungsfalle anschließend aufwandig entfernt werden muss Durch die Oberflachenoxidation wird die Maßhaltigkeit der Werkstucke verschlechtert Außerdem steigen aufgrund des Aufwandes für die Entfernung der Oxidationsschicht die Herstellungskosten an Zur Vermeidung bzw Reduzierung der Oxidation des Titans beim Gießen sind eine Vielzahl von Maßnahmen bekannt, die darauf abzielen, den Gießvorgang selbst in einer Art und Weise zu beeinflussen, so dass die Oxidation vermindert wird Beispielsweise ist bekannt, das flussige Titan unter Schutzgasatmosphare in die Form einzufüllenOne of the biggest disadvantages of the material titanium is its relatively high tendency to oxidize. When casting titanium, this material tends to form an oxidation layer on the surface, which for most applications has to be removed afterwards. The surface oxidation deteriorates the dimensional accuracy of the workpieces increase the manufacturing costs due to the effort to remove the oxidation layer To avoid or reduce the oxidation of the titanium during casting, a variety of measures are known which aim to influence the casting process itself in such a way that the oxidation is reduced For example, it is known to fill the liquid titanium into the mold under a protective gas atmosphere
Versuche haben aber gezeigt, dass die Oberflachenoxidation des Titans maßgeblich davon abhangt, in welcher Art und Weise die Form beim Ausharten der Einbettmasse verarbeitet wirdHowever, tests have shown that the surface oxidation of the titanium largely depends on the manner in which the mold is processed when the investment material hardens
Aufgabe der vorliegenden Erfindung ist es deshalb, Verfahren zur Herstellung einer verlorenen Form für den Titanguss vorzuschlagen, die die Herstellung von Titangusswerkstucken mit geringerer Oberflachenoxidation erlauben Diese Aufgabe wird durch Verfahren gemäß der Ansprüche 1 bis 9 gelost Handelsübliche Einbettmassen für den Titanguss bestehen aus einer Mischung verschiedener Oxide, wobei vor allem Aluminiumoxid (Al2O3) und Magnesiumoxid (MgO) in größeren Anteilen enthalten sind. Daneben enthält die Einbettmasse zumindest einen weiteren noch oxidierbaren Bestandteil, der in vielen Fällen aus Zirconium besteht.The object of the present invention is therefore to propose methods for producing a lost mold for titanium casting, which allow the production of titanium casting workpieces with a lower surface oxidation. This object is achieved by methods according to claims 1 to 9 Commercially available investment materials for titanium casting consist of a mixture of different oxides, with aluminum oxide (Al 2 O 3 ) and magnesium oxide (MgO) in particular being present in larger proportions. In addition, the investment contains at least one further oxidizable component, which in many cases consists of zirconium.
Bei den bekannten Verfahren soll das Zirconium Sauerstoff von der Titanschmelze fernhalten. Dieser Effekt wird aber nur unzureichend erreicht, da das Zirconium bereits beim Brennen der Form mit Sauerstoff kontaminiert wird.In the known processes, the zirconium is said to keep oxygen away from the titanium melt. However, this effect is only insufficiently achieved since the zirconium is contaminated with oxygen as soon as the mold is fired.
Die erfindungsgemäßen Verfahren beruhen auf dem gemeinsamen Grundgedanken, die Kontamination des Zirconiums, insbesondere mit Sauerstoff, während des Aushärtens der Einbettmasse zumindest einzuschränken. Dadurch wird erreicht, dass während des Titangusses möglichst viel unverbrauchtes Zirconium zur Verfügung steht und dadurch eine größere Menge von Sauerstoff im Kontaktbereich zwischen der Titanoberfläche und der Oberfläche des Formnests an das Zirconium gebunden werden kann. Die Menge des Sauerstoffes, die damit zur Oxidation des Titans zur Verfügung steht, kann dadurch reduziert werden.The methods according to the invention are based on the common basic idea of at least limiting the contamination of the zirconium, in particular with oxygen, during the curing of the investment. The result of this is that as much unused zirconium is available during the titanium casting and a larger amount of oxygen can be bound to the zirconium in the contact area between the titanium surface and the surface of the mold cavity. This can reduce the amount of oxygen that is available for the oxidation of the titanium.
Eine erste Möglichkeit zur Herstellung der Form ist es, wenn das Aus- härten der Form unter Schutzgasatmosphäre erfolgt, so dass insbesondere die Oxidation des oxidierbaren Bestandteils der Einbettmasse zumindest reduziert wird. Dazu kann beispielsweise der Ofen beim Härten der Einbettmasse mit Argon gespült werden. Selbstverständlich sind auch alle anderen Arten von Schutzgasen denkbar. Dabei ist darauf zu achten, dass im wesentlichen die gesamte Oberfläche des Formnests ausreichend mit Schutzgas versorgt wird. Dazu kann beispielsweise Schutzgas in das Innere der Form eingeleitet werden, so dass das Formnest mit Schutzgas gespült wird.A first possibility for producing the mold is if the mold is hardened under a protective gas atmosphere, so that in particular the oxidation of the oxidizable component of the investment is at least reduced. For this purpose, for example, the furnace can be flushed with argon when the investment is hardening. Of course, all other types of protective gases are also conceivable. It must be ensured that essentially the entire surface of the mold cavity is adequately supplied with protective gas. For example, protective gas can be introduced into the interior of the mold so that the mold cavity is flushed with protective gas.
Der gleiche Effekt der Reduzierung der Oxidation der Einbettmasse während des Aushärtens lässt sich auch erzielen, wenn das Aushärten der Form in einer Atmosphäre mit reduzierter Gasdichte erfolgt Dazu kann in dem Ofen beim Ausharten der Embettmasse ein Unterdruck bzw em Vakuum aufgebaut werden Durch die verringerte Gasdichte im Ofeninnenraum stehen weniger Sauerstoffatome zur Oxidation zur Verfugung, so dass Oxidationsvorgange insgesamt verringert werdenThe same effect of reducing the oxidation of the investment during curing can also be achieved if the curing of the Mold takes place in an atmosphere with reduced gas density. For this purpose, a negative pressure or vacuum can be built up in the furnace when the bed material hardens. Due to the reduced gas density in the furnace interior, fewer oxygen atoms are available for oxidation, so that oxidation processes are reduced overall
Sowohl das Harten der Embettmasse unter Schutzgasatmosphare als auch mit reduzierter Gasdichte erfordert einen gewissen zusatzlichen geratetechnischen Aufwand Sehr gute Ergebnisse bei der Reduktion der Oxidation der Titanoberflache sind j edoch auch ohne diesen zusatzlichen Aufwand beim Formherstellen möglich Der relative Oxidationsgrad der Embettmasse, d h das Verhältnis der nicht oxidierten Embettmasse zum Anteil der oxidierten Embettmasse hangt maßgeblich davon ab, bei welcher Temperatur die Embettmasse für wie lange einer bestimmten Gasdichte ausgesetzt wird Hohe Temperaturen, hohe Gasdichten und eine lange Einwirkdauer fuhren im Ergebnis zu hohen Oxidationsgraden Durch Reduzierung der Einwirkdauer von hohen Temperaturen auf die Embettmasse kann also die Oxidation der oxidierbaren Bestandteile der Embettmasse verringert werdenBoth the hardening of the embedding material under a protective gas atmosphere and with a reduced gas density requires a certain additional expenditure in terms of technical equipment.However, very good results in reducing the oxidation of the titanium surface are also possible without this additional outlay during the production of the mold. The relative degree of oxidation of the embedding composition, ie the ratio of the Oxidized bed material to a proportion of the oxidized bed material largely depends on the temperature at which the bed material is exposed to a certain gas density for how long.High temperatures, high gas densities and a long exposure time result in high degrees of oxidation as a result of reducing the exposure time of high temperatures to the bed material the oxidation of the oxidizable constituents of the bed material can thus be reduced
Dabei ist darauf hinzuweisen, dass die Haltezeit, wahrend der nach Erreichung einer Maximaltemperatur (beispielsweise 850°C) die Temperatur im Ofeninnenraum weitgehend konstant gehalten wird, an die Menge der verwendeten Embettmasse anzupassen ist Aufgrund der hohen Temperatur im Ofeninnenraum herrscht wahrend der Haltezeit eine so geringe Gasdichte im Ofeninnenraum, dass die Oxidation der Embettmas- se wahrend dieser Zeit verhältnismäßig gering ist Durch das Abkühlen des Ofeninnenraums nach Ende der Haltezeit steigt die Gasdichte im Ofeninnenraum wieder stark an Der Hauptanteil der Oxidation erfolgt deshalb wahrend des Abkuhlens der Form, da in dieser Verfahrensphase sowohl ausreichend hohe Temperaturen für die Oxidation der Einbettmas- se und ausreichend hohe Gasdichten zur Versorgung mit Luftsauerstoff im Ofeninneren vorhanden sind Nach einer weiteren erfindungsgemäßen Verfahrensvariante wird deshalb die Form nach Erreichen und Halten einer Maximaltemperatur, d. h. nachdem die Haltezeit auf Maximaltemperatur durchlaufen ist. aktiv gekühlt, um die Abkühlzeit zu reduzieren. Dabei sollte die Kühlung gerade so stark sein, dass ein Reißen der Form durch zu große Temperaturbeanspruchung ausgeschlossen ist.It should be noted that the holding time, during which the temperature in the furnace interior is kept largely constant after reaching a maximum temperature (for example 850 ° C), must be adapted to the amount of bed material used. Due to the high temperature in the interior of the furnace, there is a problem during the holding time Low gas density in the furnace interior, that the oxidation of the bed mass is relatively low during this time. By cooling the furnace interior after the end of the holding time, the gas density in the furnace interior rises again strongly. The main part of the oxidation therefore takes place during the cooling of the mold, because in this The process phase has both sufficiently high temperatures for the oxidation of the investment and sufficiently high gas densities for the supply of atmospheric oxygen inside the furnace According to a further variant of the method according to the invention, the shape is therefore after reaching and maintaining a maximum temperature, ie after the holding time has passed to the maximum temperature. actively cooled to reduce the cooling time. The cooling should be just strong enough to prevent the mold from tearing due to excessive temperature stress.
Da das Maß der zulässigen Kühlung durch die maximale Temperatur- beanspruchbarkeit und durch die Menge der ausgehärteten Einbettmasse begrenzt wird, sind spezielle Kühlmittel in aller Regel nicht erforderlich. Vielmehr ist es bereits in der Regel ausreichend, wenn der Form zurSince the extent of the permissible cooling is limited by the maximum temperature resistance and the amount of hardened investment, special coolants are generally not required. Rather, it is usually sufficient if the shape is
Kühlung raumwarme Luft aus der Umgebungsatmosphäre zugeführt wird. Dies kann beispielsweise dadurch erreicht werden, dass der Ofen nach Ende der Haltezeit nicht einfach nur abgeschaltet wird und die Form im geschlossenen Ofeninnenraum langsam abkühlt, sondern statt dessen der Ofen nach Abschalten der Heizung geöffnet und dadurch die Atmosphäre im Ofeninnenraum mit der raumwarmen Umgebungstemperatur ausgetauscht wird. Zur Verstärkung der Kühlung mit der Umgebungsluft können selbstverständlich auch weitere Hilfsmittel, wie beispielsweise Ventilatoren, die für eine Zwangsströmung sorgen, eingesetzt werden.Cooling room-warm air is supplied from the ambient atmosphere. This can be achieved, for example, by not simply switching off the oven after the end of the holding time and slowly cooling the mold in the closed interior of the oven, but instead opening the oven after switching off the heating and thereby exchanging the atmosphere in the interior of the oven with the warm ambient temperature , Of course, other aids such as fans, which ensure a forced flow, can also be used to reinforce the cooling with the ambient air.
Eine weitere Reduktion der Oxidation der Einbettmasse lässt sich erreichen, wenn die Kühlung der Form durch Zufuhr von Schutzgas in den verfahrensrelevanten Bereich mit der Form erreicht wird. Durch die Umspülung mit dem kühleren Schutzgas wird die Form einerseits gekühlt und andererseits werden durch Verdrängung von Luftsauerstoff Oxidati- onsvorgänge vermieden.A further reduction in the oxidation of the investment can be achieved if the mold is cooled by supplying protective gas to the process-relevant area of the mold. By purging with the cooler shielding gas, the mold is cooled on the one hand and oxidation processes are avoided by displacing atmospheric oxygen.
Eine weitere Möglichkeit, positiv auf den Oxidationsgrad der Einbettmasse Einfluss zu nehmen, ist es, den Brennofen beim Aushärten der Form bis zum Erreichen der Maximaltemperatur mit einer Aufheizgeschwindigkeit von zumindest 7°C pro Minute oder schneller aufzuheizen. Da normalerweise nur mit lediglich 6°C pro Minute aufgeheizt wird, ergibt sich durch diese Maßnahme ein schnelleres Erreichen der Maximaltemperatur, wodurch wiederum im Ergebnis die Verweildauer der Einbettmasse schon während der Aufheizphase im aufgeheizten Ofen reduziert wird.Another possibility to have a positive influence on the degree of oxidation of the investment material is to heat the kiln with a heating rate of at least 7 ° C per minute or faster when the mold hardens until the maximum temperature is reached. Since heating is normally only at 6 ° C per minute, the result is This measure means that the maximum temperature is reached more quickly, which in turn reduces the dwell time of the investment material during the heating phase in the heated furnace.
Bei der Herstellung von Formen mit einem Gewicht zwischen 80g und 1000g, wie sie für den zahntechnischen Guss typisch sind, hat sich eine Verfahrensvariante als besonders vorteilhaft erwiesen, die durch folgende Verfahrensschritte gekennzeichnet ist:In the production of molds with a weight between 80g and 1000g, as are typical for dental casting, a process variant has proven to be particularly advantageous, which is characterized by the following process steps:
Das Gussobjekt wird zunächst ausmodelliert und mittels Gusskanälen aus geeignetem Material, beispielsweise Wachs, an einem Gusstrichterformer in einem Muffelring oder ähnlichem befestigt. Danach wird die Einbettmasse mit einer vorgeschriebenen Menge Anmischflüssigkeit, beispielsweise Wasser, angerührt und in die Muffel eingefüllt, wobei dabei das Gussobj ekt vollständig umschlossen wird und dadurch die gewünschte Form negativ in der Einbettmasse abbildet. Danach wird die Muffel mit Gusstrichterformer in einem Drucktopf mit Überdruck beaufschlagt, um dadurch die Einbettmasse weiter zu verdichten. Danach wird die Einbettmasse für mindestens 30 Minuten bei Raumtemperatur ausgehärtet und anschließend der Gusstrichterformer entfernt. Danach wird die Muffel in einem kalten Ofen eingebracht und der Ofen mit einer Aufheizgeschwin- digkeit von mindestens 7°C pro Minute bis auf eine Temperatur von 850°C aufgeheizt. Diese Haltetemperatur wird dann für ca. 30 Minuten konstant gehalten. Danach wird der Ofen ausgeschaltet und der Ofeninnenraum durch Öffnen der Ofentür für ca. 15 Minuten gekühlt. Danach wird die Form an den Rand der Ofenöffnung oder auf die Ofenklappe gestellt, um dadurch die Kühlung zu verstärken. Wiederum wird die Form an dieser Stelle für ca. 15 Minuten zur Kühlung stehen gelassen. Zur weiteren Verstärkung der Kühlung wird die Form anschließend außerhalb des Ofens abgestellt und wiederum stehen gelassen, bis die gewünschte Temperatur für den Gießvorgang erreicht ist. Damit ist das erfindungs- gemäße Verfahren zur Herstellung der Titangussform abgeschlossen und das flüssige Titan wird noch vor dem vollständigen Abkühlen der Form bei beispielsweise ca. 150°C in das Formnest eingefüllt.The casting object is first modeled and fastened to a casting funnel former in a muffle ring or the like by means of casting channels made of a suitable material, for example wax. The investment material is then mixed with a prescribed amount of mixing liquid, for example water, and poured into the muffle, the cast object being completely enclosed and the desired shape thereby negatively reflected in the investment material. Then the muffle with the cast funnel former is pressurized in a pressure pot in order to further compact the investment. Then the investment is cured for at least 30 minutes at room temperature and then the casting funnel former is removed. The muffle is then placed in a cold furnace and the furnace is heated up to a temperature of 850 ° C at a rate of at least 7 ° C per minute. This holding temperature is then kept constant for about 30 minutes. The furnace is then switched off and the interior of the furnace is cooled by opening the furnace door for approx. 15 minutes. Then the mold is placed on the edge of the furnace opening or on the furnace flap to increase the cooling. Again, the mold is left to cool for about 15 minutes at this point. To further increase cooling, the mold is then placed outside the furnace and again left to stand until the desired temperature for the casting process is reached. This completes the method according to the invention for producing the titanium casting mold The liquid titanium is poured into the mold cavity, for example at approximately 150 ° C., before the mold has completely cooled.
Selbstverständlich kann das vorgeschlagene Verfahren auch dann noch durchgeführt werden, wenn einzelne bzw. mehrere der oben genannten Verfahrensparameter modifiziert oder ganz weggelassen werden.Of course, the proposed method can also be carried out if individual or several of the above-mentioned method parameters are modified or omitted entirely.
Nach einer bevorzugten Ausführungsform des Verfahrens werden die einzelnen Verfahrensschritte automatisch in einer dafür geeigneten Vorrichtung ausgeführt. Dadurch lassen sich Personalkosten einsparen und die Reproduzierbarkeit der Ergebnisse erhöhen.According to a preferred embodiment of the method, the individual method steps are carried out automatically in a suitable device. This saves personnel costs and increases the reproducibility of the results.
Eine für das Verfahren besonders geeignete Formulierung der Einbettmasse besteht aus 0 bis 1 % Si2O2, 0 bis 1 % TiO2, 10 bis 40 % Al2O3, 0 bis 2 % Fe2O3, 0 bis 1 % MnO, 40 bis 80 % MgO, 2 bis 10 % CaO, 0 bis 2 % Na2O, 0 bis 1 % K2O, 0 bis 1 % P2O5 und 0 bis 5 % Zr. Der Anteil der einzelnen Bestandteile kann in den Bereichsgrenzen, die in Gewichtspro- zent angegeben sind variiert werden. Dabei können auch weitere Bestandteile hinzukommen und einzelne der Bestandteile durch andere Stoffe mit ähnlichen Eigenschaften substituiert werden.A particularly suitable formulation of the investment consists of 0 to 1% Si 2 O 2 , 0 to 1% TiO 2 , 10 to 40% Al 2 O 3 , 0 to 2% Fe 2 O 3 , 0 to 1% MnO , 40 to 80% MgO, 2 to 10% CaO, 0 to 2% Na 2 O, 0 to 1% K 2 O, 0 to 1% P 2 O 5 and 0 to 5% Zr. The proportion of the individual components can be varied within the range limits, which are given in percent by weight. Additional components can also be added, and individual components can be replaced by other substances with similar properties.
Die erfindungsgemäßen Verfahren können zur Herstellung jeglicher Art von Formen genutzt werden, die für den Titanguss bestimmt sind. Beson- ders vorteilhaft ist die Verwendung der erfindungsgemäßen Verfahren zur Herstellung von Formen für den zahntechnischen Titanguss, da in diesem technischen Anwendungsbereich besonders hohe Anforderungen an die Qualität der herzustellenden Gussstücke gestellt werden.The methods according to the invention can be used for the production of any type of molds which are intended for titanium casting. It is particularly advantageous to use the method according to the invention for the production of molds for dental cast titanium, since particularly high demands are made on the quality of the castings to be produced in this technical field of application.
Nachfolgend wird die Erfindung anhand zweier beispielhafter Diagramme näher erläutert. Es zeigen:The invention is explained in more detail below using two exemplary diagrams. Show it:
Fig. 1 den Verlauf der Temperatur bzw. Gasdichte über die Zeit bei einem erfindungsgemäßen Herstellungsverfahren im Vergleich zu einem konventionellen Herstellungsverfahren; Fig. 2 den Verlauf der Zunahme des relativen Oxidati- onsgrades einer Embettmasse wahrend des Aus- hartens1 shows the course of the temperature or gas density over time in a manufacturing method according to the invention in comparison with a conventional manufacturing method; 2 shows the course of the increase in the relative degree of oxidation of an embedding compound during the hardening process
In dem durch Fig. 1 dargestellten Diagramm ist die Temperatur bzw di e relative Gasdichte über die Zeit wahrend des Aushartens der Embettmasse im Brennofen eingetragen Graph 1 stellt dabei den Temperaturverlauf bei einem aus dem Stand der Technik bekannten Brennverfahren dar Graph 2 zeigt den zugehörigen Verlauf der relativen Gasdichte im Ofen über die Zeit Im Vergleich dazu zeigen die Graphen 3 und 4 den Tempe- raturverlauf bzw den Verlauf der relativen Gasdichte über der Zeit, wie er bei einem erfmdungsgemaßen Verfahren gemessen werden kann Man erkennt, dass bei dem erfmdungsgemaßen Verfahren die Haltetemperatur von 850°C durch Verwendung einer höheren Aufheizgeschwindigkeit schneller erreicht wird als bei dem konventionellen Verfahren Die Dauer der Haltezeit, wahrend der die Haltetemperatur von 850°C im Ofen konstant gehalten wird, ist lediglich um einige Minuten verkürzt Der Hauptunterschied zwischen den beiden Graphen 1 und 3 besteht darin, dass bei dem erfmdungsgemaßen Verfahren die Temperaturkur\ e nach Ende der Haltezeit durch aktive Kühlung, beispielsweise durch Offnen der Ofentür, in relativ kurzer Zeit bis auf Raumtemperatur zurückgefahren wird, so dass Oxidationsvorgange weitgehend unterdruckt werden Im Unterschied dazu fallt bei dem konventionellen Verfahren gemäß Graph 1 die Temperatur nur sehr langsam abIn the diagram represented by FIG. 1, the temperature or the relative gas density over time is plotted during the hardening of the bed material in the kiln. Graph 1 shows the temperature profile in a combustion method known from the prior art. Graph 2 shows the associated profile of the Relative gas density in the furnace over time In comparison, graphs 3 and 4 show the temperature curve or the curve of the relative gas density over time, as can be measured in a method according to the invention. It can be seen that in the method according to the invention the holding temperature of 850 ° C is reached faster by using a higher heating rate than with the conventional method The duration of the holding time, during which the holding temperature of 850 ° C is kept constant in the oven, is only reduced by a few minutes.The main difference between the two graphs 1 and 3 is that in the invention Process the temperature curve after the end of the holding time by active cooling, for example by opening the oven door, is brought back to room temperature in a relatively short time, so that oxidation processes are largely suppressed.In contrast to this, the temperature in the conventional process according to Graph 1 only drops very much slowly
Am Verlauf der Graphen für die relative Gasdichte 2 und 4 erkennt man, dass die relative Gasdichte sich umgekehrt proportional zur Temperatur im Ofen verhalt Sobald die Temperatur bei der Haltetemperatur ihr Maximum findet, erreicht die relatι\ e Gasdichte ihr Minimum bei ca 25% Erst mit Abfallen der Temperatur im Ofen steigt die relative Gasdichte wieder an, wobei die relative Gasdichte gemäß dem Graphen 4 beim erfmdungsgemaßen Verfahren sehr viel schneller ansteigt, da die Temperatur im Ofen starker fallt Insgesamt ist aus dem Diagramm von Fig. 1 erkennbar, dass beim erfmdungsgemaßen Verfahren die Oxidation der Embettmasse durch Verringerung der Einwirkdauer des Luftsauerstoffs bei hohen Temperaturen insgesamt reduziert werden kannThe graphs for the relative gas density 2 and 4 show that the relative gas density is inversely proportional to the temperature in the furnace. As soon as the temperature at the holding temperature reaches its maximum, the relative gas density reaches its minimum at approx. 25% only with If the temperature in the furnace drops, the relative gas density rises again, the relative gas density according to graph 4 in the method according to the invention increasing very much faster, since the temperature in the furnace falls more sharply 1 that the oxidation of the bed material can be reduced overall by reducing the duration of exposure to atmospheric oxygen at high temperatures
In Fig. 2 ist ein Diagramm dargestellt, bei dem der relative Oxidations- grad der Embettmasse über die Zeit wahrend des Aushartens eingetragen ist Graph 5 (konventionelles Verfahren) und Graph 6 (erfmdungsge- maßes Verfahren) zeigen dabei im Vergleich die unterschiedlichen erreichbaren relativen Oxidationsgrade bei konventionellem und erfin- dungsgemaßem Verfahren Dabei ist j eweils ein Temperatun erlauf zugrunde gelegt, wie er in Fig. 1 dargestellt ist Man erkennt, dass dei relative Oxidationsgrad beinahe proportional zur Dauer des Aushartens der Embettmasse ansteigt Da das konventionelle Verfahren erst nach 15 bis 17 Stunden eine Temperatur von ca 1 50°C in der Embettmasse erreicht, bei der das Titan dann in das Formnest eingefüllt w erden kann, steigt der relative Oxidationsgrad sehr hoch an Im Vergleich dazu w ird bei dem erfmdungsgemaßen Verfahren die Gießtemperatur in der Embettmasse von 150°C bereits nach ca V. bis 2 Stunden in Abhängigkeit von der Menge erreicht, so dass der relative Oxidationsgrad zu diesem Zeitpunkt erst bei ca 25% im Vergleich zu 100% bei konventionellem Ausharten erreichtFIG. 2 shows a diagram in which the relative degree of oxidation of the embedding mass is entered over time during the hardening process. Graph 5 (conventional method) and Graph 6 (method according to the invention) show in comparison the different achievable relative degrees of oxidation in the case of a conventional method according to the invention, in each case a temperature rise as shown in FIG. 1 is used as a basis. It can be seen that the relative degree of oxidation rises almost proportionally to the duration of the hardening of the bed material, since the conventional method only after 15 to 17 Hours reached a temperature of approx. 150 ° C in the bed material, at which the titanium can then be poured into the mold cavity, the relative degree of oxidation rises very high.Comparison with this, the casting temperature in the bed material is 150 in the process according to the invention ° C already reached after approx. V. to 2 hours depending on the amount, so there The relative degree of oxidation at this point in time only reached about 25% compared to 100% with conventional curing
Insgesamt ist festzustellen, dass durch die aktive Kühlung der Form bzw durch das schnellere Aufheizen eine signifikante Verringerung des relativen Oxidationsgrades erreicht werden kann, was wiederum eine Verringerung der Titanoxidation beim Eingießen des flussigen Titans das Formnest bewirkt Overall, it can be stated that a significant reduction in the relative degree of oxidation can be achieved by the active cooling of the mold or by the faster heating, which in turn causes a reduction in the titanium oxidation when the liquid titanium is poured into the mold cavity

Claims

Patentansprüche claims
1. Verfahren zur Herstellung einer verlorenen Form für den Titanguss aus einer aushärtbaren Einbettmasse, das zumindest einen oxidierbaren Bestandteil, insbesondere Zirconium, enthält, wobei zumindest folgende Verfahrensschritte ausgeführt werden: a) Urformung der Form durch Einbetten eines Modells aus ausschmelzbarem Werkstoff in die Einbettmasse; b) Aushärten der Einbettmasse und Ausschmelzen des Modellwerkstoffs durch Erhitzen und anschließendes Abkühlen der Form entsprechend einem vorgegebenen Temperatur-Zeit-Profil in einem Brennofen, dadurch g e k e n n z e i c h n e t, dass das Aushärten der Form unter Schutzgasatmosphäre erfolgt.1. A method for producing a lost mold for the titanium casting from a curable investment material which contains at least one oxidizable component, in particular zirconium, wherein at least the following process steps are carried out: a) original shaping of the mold by embedding a model made of meltable material in the investment material; b) Hardening the investment and melting out the model material by heating and then cooling the mold in accordance with a specified temperature-time profile in a furnace, thereby ensuring that the mold is hardened under a protective gas atmosphere.
2. Verfahren zur Herstellung einer verlorenen Form für den Titanguss aus einer aushärtbaren Einbettmasse, das zumindest einen oxidierbaren Bestandteil, insbesondere Zirconium, enthält, wobei zumindest folgende Verfahrensschritte ausgeführt werden: a) Urformung der Form durch Einbetten eines Modells aus ausschmelzbarem Werkstoff in die Einbettmasse; b) Aushärten der Einbettmasse und Ausschmelzen des Modellwerkstoffs durch Erhitzen und anschließendes Abkühlen der Form entsprechend einem vorgegebenen Temperatur-Zeit-Profil, dadurch g e k e n n z e i c h n e t, dass das Aushärten der Form in einer Atmosphäre mit reduzierter Gasdichte, insbesondere unter Unterdruck bzw. im Vakuum, erfolgt. 2. A method for producing a lost mold for the titanium casting from a curable investment material which contains at least one oxidizable component, in particular zirconium, wherein at least the following process steps are carried out: a) original shaping of the mold by embedding a model made of meltable material in the investment material; b) curing the investment and melting out the model material by heating and then cooling the mold according to a predetermined temperature-time profile, characterized in that the curing of the mold takes place in an atmosphere with reduced gas density, in particular under reduced pressure or in a vacuum.
3. Verfahren zur Herstellung einer verlorenen Form für den Titanguss aus einer aushärtbaren Einbettmasse, das zumindest einen oxidierbaren Bestandteil, insbesondere Zirconium, enthält, wobei zumindest folgende Verfahrensschritte ausgeführt werden: a) Urformung der Form durch Einbetten eines Modells aus ausschmelzbarem Werkstoff in die Einbettmasse; b) Aushärten der Einbettmasse und Ausschmelzen des Modellwerkstoffs durch Erhitzen und anschließendes Abkühlen der Form entsprechend einem vorgegebenen Temperatur-Zeit-Profil in einem Brenn- ofen, dadurch gek ennz e i chn et, dass die Form nach Erreichen und Halten einer Maximaltemperatur aktiv gekühlt wird, um die Abkühlzeit zu reduzieren.3. A method for producing a lost mold for the titanium casting from a curable investment material which contains at least one oxidizable component, in particular zirconium, wherein at least the following process steps are carried out: a) original shaping of the mold by embedding a model made of meltable material in the investment material; b) curing of the investment material and melting out of the model material by heating and then cooling the mold in accordance with a predetermined temperature-time profile in a furnace, characterized in that the mold is actively cooled after reaching and maintaining a maximum temperature, to reduce the cooling time.
4. Verfahren nach Anspruch 3 dadurch g ek ennz e i chn e t, dass die Kühlung der Form durch vermehrte Zufuhr von raumwarmer Luft aus der Umgebungsatmosphäre in den Kontaktbereich mit der Form erreicht wird.4. The method according to claim 3, characterized in that the cooling of the mold is achieved by increasing the supply of room-warm air from the ambient atmosphere into the contact area with the mold.
5. Verfahren nach Anspruch 3 dadurch gekennze i chnet, dass die Kühlung der Form durch Zufuhr von Schutzgas in den Kontaktbereich mit der Form erreicht wird.5. The method according to claim 3, characterized in that the cooling of the mold is achieved by supplying protective gas into the contact area with the mold.
6. Verfahren nach einem der Ansprüche 3 bis 5, dadurch gekennz ei chn et, dass der Brennofen beim Aushärten der Form bis zum Erreichen der6. The method according to any one of claims 3 to 5, characterized gekennz ei chn et that the kiln when curing the mold until reaching the
Maximaltemperatur mit einer Aufheizgeschwindigkeit von zumindest 7°C/min oder schneller aufgeheizt wird. Maximum temperature is heated with a heating rate of at least 7 ° C / min or faster.
. Verfahren nach einem der Ansprüche 3 bis 6, dadurch g e k e n n z e i c h n e t, dass folgende Verfahrensschritte zur Herstellung einer Form mit einem Gewicht zwischen 80g und 1000g durchgeführt werden: a) Modell mit einem Gusstrichterformer in einem Muffelring befestigen, b) Einbettmasse mit vorgeschriebener Menge Anmischflüssigkeit anrühren, c) Einbettmasse in eine Muffel füllen, d) Muffel mit Gusstrichterformer bei Umgebungsbedingungen oder in einem Drucktopf mit Überdruck beaufschlagen, e) Einbettmasse mindestens 30 min. aushärten lassen und anschließend Gusstrichterformer entfernen, f) Muffel in kalten Ofen einbringen und Ofen mit mindestens 7°C/min bis auf eine Temperatur von 850°C (Haltetemperatur) aufheizen, g) Ofen bis zur vollständigen Durchwärmung der Gussform bei Haltetemperatur halten, h) Ofen ausschalten und Ofeninnenraum durch Öffnen der Ofentür für circa 15 min. kühlen, i) Form an den Rand der Ofenöffnung oder auf die Ofenklappe stellen und circa 15 min. zum Kühlen stehen lassen, j) Form außerhalb des Ofens abstellen und bis zum Erreichen der gewünschten Temperatur für den Gießvorgang stehen lassen., Method according to one of claims 3 to 6, characterized in that the following process steps for producing a mold with a weight between 80g and 1000g are carried out: a) fix the model with a cast funnel former in a muffle ring, b) mix investment material with the prescribed amount of mixing liquid, c ) Put investment in a muffle, d) Apply pressure to the muffle with a cast funnel former under ambient conditions or in a pressure pot, e) Investment material at least 30 min. Allow to harden and then remove the casting funnel former, f) Place the muffle in a cold furnace and heat the furnace to at least 7 ° C / min to a temperature of 850 ° C (holding temperature), g) Hold the furnace at holding temperature until the mold has completely warmed up, h ) Switch off the oven and open the oven interior by opening the oven door for approx. 15 min. cool, i) place the mold on the edge of the oven opening or on the oven hatch and leave for approx. 15 min. Leave to cool, j) place the mold outside the oven and let it stand for the casting process until the desired temperature is reached.
8. Verfahren nach einem der Ansprüche 1 bis 7, dadurch g e k e n n z e i c h n e t, dass das Verfahren im wesentlichen automatisch durchgeführt wird. 8. The method according to any one of claims 1 to 7, characterized in that the method is carried out essentially automatically.
. Verfahren nach einem der Ansprüche 1 bis 8, dadurch g e k e nn z e i c h n e t, dass die Einbettmasse zumindest Bestandteile in den nachfolgend angegebenen Anteilsgrenzen enthält: - 0 bis 1 Gew-% Si2O2 , Method according to one of claims 1 to 8, characterized in that the investment contains at least components within the proportion limits specified below: - 0 to 1% by weight Si 2 O 2
- 0 bis 1 Gew-% TiO2 - 0 to 1% by weight of TiO 2
- 10 bis 40 Gew-% Al2O3 - 10 to 40% by weight of Al 2 O 3
- 0 bis 2 Gew-% Fe2O3 - 0 to 2% by weight of Fe 2 O 3
- 0 bis 1 Gew-% MnO - 40 bis 80 Gew-% MgO- 0 to 1 wt% MnO - 40 to 80 wt% MgO
- 2 bis 10 Gew-% CaO- 2 to 10% by weight of CaO
- 0 bis 2 Gew-%o Na2O- 0 to 2% by weight o Na 2 O
- 0 bis 1 Gew-% K2O- 0 to 1% by weight of K 2 O
- 0 bis 1 Gew-% P2O5 und - 0 bis 5 Gew-% Zr.- 0 to 1% by weight of P 2 O 5 and - 0 to 5% by weight of Zr.
10. Verwendung eines Verfahrens nach den Ansprüchen 1 bis 9 zur Herstellung von Formen für den zahntechnischen Titanguss. 10. Use of a method according to claims 1 to 9 for the production of molds for dental titanium casting.
EP01919141A 2000-02-23 2001-02-23 Method for production of an oxidation inhibiting titanium casting mould Expired - Lifetime EP1259341B1 (en)

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EP1259341B1 (en) 2004-11-24
ES2233619T3 (en) 2005-06-16
WO2001062413A3 (en) 2002-03-21
WO2001062413A2 (en) 2001-08-30
PT1259341E (en) 2005-04-29
ATE283129T1 (en) 2004-12-15
JP2003523287A (en) 2003-08-05
DE10008384C2 (en) 2002-07-18
DE50104599D1 (en) 2004-12-30
DE10008384A1 (en) 2001-09-13
US6802358B2 (en) 2004-10-12
AU4635901A (en) 2001-09-03
US20030011093A1 (en) 2003-01-16

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