EP1043094B1 - Procédé de fabrication de pièces coulée - Google Patents

Procédé de fabrication de pièces coulée Download PDF

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Publication number
EP1043094B1
EP1043094B1 EP99107009A EP99107009A EP1043094B1 EP 1043094 B1 EP1043094 B1 EP 1043094B1 EP 99107009 A EP99107009 A EP 99107009A EP 99107009 A EP99107009 A EP 99107009A EP 1043094 B1 EP1043094 B1 EP 1043094B1
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EP
European Patent Office
Prior art keywords
process according
silica sol
binder
expansion
sio
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
EP99107009A
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German (de)
English (en)
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EP1043094A1 (fr
Inventor
Norbert Prof. Dr.-Ing Nowack
Günter Grill
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shera-Werkstofftechnologie & Cokg GmbH
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Shera-Werkstofftechnologie & Cokg GmbH
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Priority to DE59914938T priority Critical patent/DE59914938D1/de
Priority to EP99107009A priority patent/EP1043094B1/fr
Publication of EP1043094A1 publication Critical patent/EP1043094A1/fr
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Publication of EP1043094B1 publication Critical patent/EP1043094B1/fr
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Classifications

    • 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
    • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
    • B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
    • 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
    • B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
    • B22C1/18—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents
    • B22C1/186—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents contaming ammonium or metal silicates, silica sols

Definitions

  • the invention relates to a method for producing cast pieces, in particular filigree precision castings in the medical field, in which a consisting of a ceramic investment material mold is selectively expanded before filling a casting material to compensate for occurring during cooling from the molten state volume contraction of the casting material, said Investment of a quartz-free oxide ceramic mixture, a binder and serving as a mixing liquid silica sol is formed with the addition of an organic carboxylic acid.
  • the casting molds used for this purpose consist of a ceramic investment material, which is obtained by means of a wax model corresponding to the body part to be reconstructed. This is done by mixing a slurry consisting of a ceramic mixture and a binder with a mixing liquid and applying it to the wax model. After the slurry is set at room temperature after a short time, the solid mold formed in this way is heated to a temperature at which the wax of the wax model flows out without residue. To the required casting parameters, such as the Edge stability of the mold, to reach the mold is preheated to temperatures of up to 1000 ° C before the introduction of the casting material.
  • the casting process is characterized by a volume contraction of the casting material.
  • a shrinkage occurs, which passes into a shrinkage during solidification.
  • the overall expansion of the embedding compound is composed of a setting expansion during the setting of the slurry and a thermal expansion during heating of the casting mold.
  • a high thermal expansion can be achieved when quartz-containing investments are used. This is due to the thermal conversion behavior of silica modifications.
  • quartz-containing investment materials are characterized by high expansion values of up to 2%, which often make a setting expansion unnecessary, but in addition to a harmful formation of fine dusts with a particle size of ⁇ 10 microns to the disadvantage of a likewise uneven cooling behavior.
  • a disadvantage of quartz-containing investment materials is also a relatively low softening temperature, which cause at high casting temperatures, such as those required when casting, for example, titanium alloys, slagging reactions that bring pass inaccuracies with it.
  • a quartz-containing Gusseinbettmasse for producing molds for alloy parts is known.
  • a molten metal alloy can be cast into a mold made from the cast investment. After cooling and hardening of the alloy, the mold is removed and the alloy casting removed.
  • the fit of the tooth replacement part produced by casting therefore depends decisively on the casting mold and in particular on the surface quality of the casting mold.
  • the investment material hardens, the chemical reactions that occur can result in "efflorescence" that adversely affects the usability of the casting mold. Practical experience has shown that blooming occurs particularly when the setting of the investment materials is completed, but these are not yet dry due to the formation of moisture caused by setting. It is therefore proposed a quartz-containing Gusseinbettmasse that is mixed with a water-soluble acid to reduce such efflorescence.
  • quartz-free ceramic investment materials which are less hazardous to health and less susceptible to alpha-case formation, have an almost constant thermal expansion behavior. Due to a up to about 900 ° C, that is, up to the preheating temperature of the mold, small expansion coefficient, can be achieved with quartz-free investment materials, however, only a small thermal expansion of 0.5% maximum. To compensate for the occurring during cooling volume contraction of the casting material therefore high values for the setting expansion are required.
  • the invention has for its object to provide a method for the production of Gußwerk GmbH, with which a comparatively simple control of the occurring during setting expansion of a quartz-free investment material can be achieved.
  • This object is achieved in a method for the preparation of Gußwerk Westernen with the above frameworkon features according to the invention characterized in that the occurring during the setting expansion of the embedding material by varying the content of colloidal amorphous silica (SiO 2) in the silica sol is controlled in dependence on the used castable is targeted by the addition of colloidal, amorphous silica (SiO 2 ).
  • the invention takes the surprising finding of its own that it is sufficient to set a sufficiently large setting expansion in quartz-free investment materials to vary the content of silica (SiO 2 ) in serving as a mixing fluid silica corresponding to the respective casting materials.
  • the reason for the achievable setting expansion values is primarily the interaction of the organic carboxylic acid with the silica sol.
  • Silica sol as an aqueous anionic solution of colloidal, amorphous silica (SiO 2 ) with a pH above 10, has negatively charged and, as a result, mutually repulsive SiO 2 particles, which sufficiently stabilize the silica sol and give it a relatively low viscosity.
  • the carboxylic acid lowers the pH of the silica sol and results in an acid-base reaction which precipitates silica gel according to the following equation: ⁇ Si-O - (Sol) + H + ⁇ ⁇ Si-OH (Gel) with ⁇ Si-O - : silicate anion on the surface of a SiO 2 particle and ⁇ Si-OH: Undissociated silica on the surface of a SiO 2 particle.
  • the silicon dioxide (SiO 2 ) content in the silica sol is varied between 30% by weight and 40% by weight in order to set a certain expansion of the embedding compound.
  • 30% silica sol leads to a setting expansion of 0.8%
  • a proportion of silicon dioxide (SiO 2 ) in the silica sol of 40% by weight a setting expansion of 6% can be achieved.
  • the variation of the silica content in the above interval thus allows sufficiently large setting expansion values for most of the cast materials.
  • silica sol in which the silicon dioxide piadicles have a BET surface area of 50 m 2 / g to 350 m 2 / g.
  • the quartz-free oxide ceramic mixture of oxides is preferably composed of aluminum silicates, zirconium silicate and stable silicates of the alkaline earth metals, as well as magnesium oxide (MgO) and corundum ( ⁇ -Al 2 O 3 ).
  • Such oxide ceramic mixtures are of high thermal and chemical stability, are generally high-melting and have a low thermal expansion coefficient. Compared to quartz-containing investments, they are much more stable and, in particular, more suitable for investment casting of titanium (Ti) or zirconium (Zr) based metal alloys. Moreover, the risk of slagging is comparatively low.
  • the embedding composition according to the invention advantageously has a proportion of oxides of high thermal and chemical stability of 96 wt .-% to 30 wt .-%, a proportion of corundum ( ⁇ -Al 2 O 3 ) of trace to 40 wt .-% and a proportion on magnesium oxide (MgO) of 4 wt .-% to 30 wt .-% to.
  • a phosphate binder based on magnesium oxide (MgO) and monoammonium phosphate (NH 4 H 2 PO 4 ) is used as the binder.
  • the component P 2 O 5 is unstable to liquid metals, but passes at a temperature of about 1400 ° C in the thermochemically stable compound Mg 2 P 2 O 7 .
  • the relatively low proportion of monoammonium phosphate (NH 4 H 2 PO 4 ) in the investment ensures that the P 2 O 5 content is less than 3% hereinafter. This is especially important when a titanium (Ti) based casting material is used because titanium (Ti) or titanium alloys are highly reducing.
  • the triangular diagram according to Fig. 1 lets recognize the composition of the oxide ceramic mixture of an investment material.
  • the corners of the equilateral triangle correspond to the pure components corundum ( ⁇ -Al 2 O 3 ), magnesium oxide (MgO) and oxides of high thermal and chemical stability, such as aluminum silicates, a ternary system.
  • the binary edge systems are found, while points within the triangle represent the ternary mixture.
  • Constant mass content lines w of one component are parallel to the triangle sides facing the respective corner of the pure component, and cut off the respective mass fractions on the edge scales.
  • the diagram in Fig. 2 shows the relationship between the size of the occurring when setting a quartz-free investment material expansion ⁇ A and the content w of silica (SiO 2 ) in a serving as a mixing silica sol. It can be seen that with a content w of silicon dioxide (SiO 2 ) of 30 wt.%, A setting expansion of about 0.8% occurs, while with a content w of silicon dioxide (SiO 2 ) of 40 wt Be achieved curing expansion of nearly 6%.
  • the setting expansion ⁇ A is understood as meaning the change in length ⁇ L of a particle of the embedding compound after setting in relation to the initial length L 0 of the particle in a coordinate direction.
  • Such an embedding compound can be processed in the mushy state to form a casting mold, wherein after about 10 minutes, the setting reaction occurs at room temperature. After about 1 h, when the mold is completely set and firm, the in Fig. 2 for different contents w of silicon dioxide (SiO 2 ) in the setting solution ⁇ A shown in the silica sol serving as mixing liquid.
  • SiO 2 silicon dioxide
  • temperature range up to 900 ° C such investment has a low, almost linear thermal expansion ⁇ th of 0.35%.
  • the investment material is particularly suitable for applications in the medical field, in particular in dental technology, for example for the production of implants.
  • NEM non-precious metal alloys
  • dental alloys based on cobalt, chromium and molybdenum, cobalt, chromium and tungsten or nickel, chromium and molybdenum, which replace expensive precious metal alloys setting expansion values of 2.8% are generally to 3.5%, which can be achieved with the above investment with a 36% to 38% silica sol.
  • the setting expansion values must be between 2.3% and 3.8%.
  • a silica sol whose content w of silicon dioxide (SiO 2 ) is between 34% by weight and 36% by weight is suitable for this purpose.
  • the embedding compound described above is characterized in that the main constituents of the oxide ceramic mixture are refractory oxides, namely mullite and zirconium silicate (ZrSiO 4 ).
  • refractory oxides namely mullite and zirconium silicate (ZrSiO 4 ).
  • ZrSiO 4 zirconium silicate
  • zirconium (IV) oxide) zirconium (IV) oxide
  • the likewise refractory corundum ( ⁇ -Al 2 O 3 ) is present, which is relatively coarse-grained at a grain fraction of more than 100 microns and therefore forms predetermined breaking points in the matrix of the investment.
  • the zirconium silicate has a fine grain fraction of less than 40 microns and thus serves to improve the surface
  • the setting reaction likewise occurs after about 10 minutes at room temperature. After about 1 h, the finished casting mold is completely set and a setting expansion ⁇ A of about 2.5% occurs.
  • Glass ceramics which are used to produce biocompatible implants, for example as a substitute for tooth parts, cartilage or small bone parts in the jaw or ear area, are generally based on the semi-crystalline basic system SiO 2 -Al 2 O 3 -MgO-CaO-K 2 O / Na 2 O. / NaF / P 2 O 5 .
  • the glass ceramic is usually pressed at temperatures of about 900 ° C in the mold. Precisely fitting precision parts can therefore be produced because the volume contraction that occurs when the glass ceramic cools is compensated for by the setting expansion of the investment material forming the casting mold.
  • the investment materials described above are particularly suitable for a titanium investment casting, in which the use temperature of the casting mold, however, should be in about 500 ° C to prevent the formation of an alpha-case shape.
  • the above investments are characterized by their use in a process for producing castings in which the expansion occurring during setting is controlled in a simple manner. Simple handling is ensured not least by the fact that the organic acid required to achieve high setting expansion values either already contained in the investment material before the mixing with the silica sol, or is added only during the mixing process together with the silica sol in solid or already dissolved form.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Dental Preparations (AREA)
  • Dental Prosthetics (AREA)
  • Mold Materials And Core Materials (AREA)

Claims (9)

  1. Procédé de fabrication de pièces coulées, notamment d'éléments de pièces moulées de précision filigranes dans le secteur médical, dans lequel on provoque une expansion adéquate d'un moule consistant dans une masse à inclusion céramique, avant de le remplir avec une matière de coulée, pour compenser une contraction volumétrique de matière de coulée se produisant lors du refroidissement à partir de l'état de fusion, la masse à inclusion consistant dans un mélange de céramique oxydée exempte de quartz (M1, M2), d'un agent liant et d'un gel de silice servant de liquide de mélange, en ajoutant un acide carboxylique organique,
    caractérisé en ce,
    qu'on commande de façon adéquate l'expansion(εA) de la masse à inclusion se produisant pendant la prise par variation de la teneur (SiO2) de dioxyde de silicium colloïdal amorphe dans le gel de silice en fonction de la matière de coulée utilisée en ajoutant du dioxyde de silicium (SiO2) colloïdal amorphe.
  2. Procédé selon la revendication 1, caractérisé en ce que pour régler une expansion déterminée (εA) de la masse à inclusion, on varie la teneur en dioxyde de silicium (SiO2) dans le gel de silice entre 30 % en poids et 40 % en poids.
  3. Procédé selon la revendication 2, caractérisé en ce qu'on mélange 100 g de mélange de céramique oxydée, d'agent liant et d'acide carboxylique avec de 15 ml à 40 ml de gel de silice.
  4. Procédé selon l'une quelconque des revendications 1 à 3, caractérisé en ce qu'on met en oeuvre un gel de silice avec des surfaces BET des particules d'oxyde de silicium de 50 m2/g à 350 m2/g.
  5. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce qu'on met en oeuvre en tant qu'acide carboxylique un acide dicarboxylique ou tricarboxylique, de préférence de l'acide oxalique, de l'acide malonique, de l'acide maléique, de l'acide tartrique, de l'acide citrique ou de l'acide malique.
  6. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le mélange de céramique oxydée exempte de quartz se compose de préférence de silicates d'aluminium, de silicates de zirconium et de silicates stables des métaux alcalinoterreux, ainsi que d'oxyde de magnésium (MgO) et de corindon (α-Al2-O3).
  7. Procédé selon la revendication 6, caractérisé par une part d'oxydes de 96 % en poids à 30 % en poids, par une part de corindon (α-Al2-O3) de la trace à 40 % en poids et par une part d'oxyde de magnésium (MgO) de 4 % en poids à 30 % en poids.
  8. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce qu'on met en oeuvre en tant qu'agent liant un liant phosphatique à base d'oxyde de magnésium (MgO) et de phosphate de monoammonium (NH4H2PO4).
  9. Procédé selon la revendication 8, caractérisé en ce qu'on choisit pour la part de phosphate de monoammonium (NH4H2PO4) dans l'agent liant de 5 % en poids à 15 % en poids, rapportés à la masse du mélange de céramique oxydée.
EP99107009A 1999-04-09 1999-04-09 Procédé de fabrication de pièces coulée Expired - Lifetime EP1043094B1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE59914938T DE59914938D1 (de) 1999-04-09 1999-04-09 Verfahren zur Herstellung von Gusswerkstücken
EP99107009A EP1043094B1 (fr) 1999-04-09 1999-04-09 Procédé de fabrication de pièces coulée

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP99107009A EP1043094B1 (fr) 1999-04-09 1999-04-09 Procédé de fabrication de pièces coulée

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EP1043094A1 EP1043094A1 (fr) 2000-10-11
EP1043094B1 true EP1043094B1 (fr) 2008-12-24

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DE (1) DE59914938D1 (fr)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10321106A1 (de) * 2003-05-09 2004-12-23 Hydro Aluminium Deutschland Gmbh Formstoff, Formteil und Verfahren zur Herstellung von Formteilen für eine Gießform
DE102006012630B4 (de) * 2006-03-20 2010-04-08 Amann Girrbach Ag Dosiervorrichtung zum Mischen von mindestens einer pulverförmigern Substanz mit mindestens einer flüssigen Substanz
US20120270052A1 (en) 2009-11-27 2012-10-25 Basf Se Coating composition for foam particles
WO2012019988A1 (fr) 2010-08-09 2012-02-16 Basf Se Matériaux stables à hautes températures et à l'humidité présentant des propriétés d'isolation améliorées à base de mousses et de silicates dispersés
DE102010064142B4 (de) * 2010-12-23 2019-06-13 BEGO Bremer Goldschlägerei Wilh. Herbst GmbH & Co. KG Einbettmasse zur Verwendung in einem Verfahren zur Herstellung einer Dental-Restauration mittels CAD-Cast-Verfahren
DE102013109039A1 (de) 2012-08-22 2014-02-27 SHERA Werkstoff-Technologie GmbH & Co. KG Verfahren zur Herstellung von Präzisionsgussteilen für dentalmedizinische Anwendungen
DE102012113074A1 (de) * 2012-12-22 2014-07-10 Ask Chemicals Gmbh Formstoffmischungen enthaltend Metalloxide des Aluminiums und Zirkoniums in partikulärer Form
DE102012113073A1 (de) * 2012-12-22 2014-07-10 Ask Chemicals Gmbh Formstoffmischungen enthaltend Aluminiumoxide und/oder Aluminium/Silizium-Mischoxide in partikulärer Form
DE102013113560B3 (de) 2013-12-05 2015-05-28 SHERA Werkstoff-Technologie GmbH & Co. KG Keramische Einbettmasse und deren Verwendung sowie Verfahren zur Herstellung von Präzisionsgussteilen
CN108210101B (zh) * 2018-01-04 2020-11-10 北京圣爱吉友和义齿制作有限公司 一种义齿支架制作工艺

Citations (6)

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JPS579554A (en) * 1980-06-20 1982-01-19 Tokuyama Soda Co Ltd Mold material
US4591385A (en) * 1984-06-04 1986-05-27 Aremco Products, Inc. Die material and method of using same
US4814011A (en) * 1986-12-03 1989-03-21 G-C Dental Industrial Corp. Investments for dental casting
EP0417527A2 (fr) * 1989-09-14 1991-03-20 Krupp Medizintechnik GmbH Modèle et procédé pour la prévention de formation de dépôts provenant du revêtement sur les modèles et objets coulés
DE4210004A1 (de) * 1992-03-27 1993-09-30 Joachim Pajenkamp Verfahren und keramische Gußform zur Herstellung von dentalen Gußwerkstücken aus Titan und keramisierbare Zusammensetzung für die Herstellung einer keramischen Gußform zur Herstellung von dentalen Gußwerkstücken aus Titan
RU2061572C1 (ru) * 1992-12-21 1996-06-10 Александр Васильевич Климкин Самотвердеющая смесь для изготовления литейных форм и стержней

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US2209035A (en) * 1938-11-26 1940-07-23 Nobilium Products Inc Refractory investment
JPS6044061B2 (ja) * 1982-11-18 1985-10-01 大成歯科工業株式会社 精密鋳造用埋没材組成物
EP0916430B1 (fr) * 1997-11-14 2009-06-24 Shera-Werkstofftechnologie Gmbh Procédé pour le contrôle de l'expansion de matériau pour le moulage de précision

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS579554A (en) * 1980-06-20 1982-01-19 Tokuyama Soda Co Ltd Mold material
US4591385A (en) * 1984-06-04 1986-05-27 Aremco Products, Inc. Die material and method of using same
US4814011A (en) * 1986-12-03 1989-03-21 G-C Dental Industrial Corp. Investments for dental casting
EP0417527A2 (fr) * 1989-09-14 1991-03-20 Krupp Medizintechnik GmbH Modèle et procédé pour la prévention de formation de dépôts provenant du revêtement sur les modèles et objets coulés
DE4210004A1 (de) * 1992-03-27 1993-09-30 Joachim Pajenkamp Verfahren und keramische Gußform zur Herstellung von dentalen Gußwerkstücken aus Titan und keramisierbare Zusammensetzung für die Herstellung einer keramischen Gußform zur Herstellung von dentalen Gußwerkstücken aus Titan
RU2061572C1 (ru) * 1992-12-21 1996-06-10 Александр Васильевич Климкин Самотвердеющая смесь для изготовления литейных форм и стержней

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EP1043094A1 (fr) 2000-10-11
DE59914938D1 (de) 2009-02-05

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