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US20070181285A1 - Die for producing a casting and method for making the die - Google Patents

Die for producing a casting and method for making the die Download PDF

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Publication number
US20070181285A1
US20070181285A1 US11/670,489 US67048907A US2007181285A1 US 20070181285 A1 US20070181285 A1 US 20070181285A1 US 67048907 A US67048907 A US 67048907A US 2007181285 A1 US2007181285 A1 US 2007181285A1
Authority
US
United States
Prior art keywords
layer area
casting mould
casting
minimum
front layer
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.)
Abandoned
Application number
US11/670,489
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English (en)
Inventor
Gunter Hubner
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.)
Access eV
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Assigned to ACCESS E.V. reassignment ACCESS E.V. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HUBNER, GUNTER
Publication of US20070181285A1 publication Critical patent/US20070181285A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22CFOUNDRY MOULDING
    • B22C9/00Moulds or cores; Moulding processes
    • B22C9/02Sand moulds or like moulds for shaped castings
    • B22C9/04Use of lost patterns

Definitions

  • the invention concerns a die for producing a casting, particularly a component for a motor or other engine, from a reactive non-ferrous molten metal charge using a casting mould, and a method for manufacturing the die and the use of the die to produce a component.
  • casting moulds includes their employment for producing castings of the widest range of types.
  • a molten charge of a casting material is introduced into a cavity of the casting mould.
  • the casting material then solidifies, giving the casting an external shape which corresponds to that of the casting mould.
  • the casting is subsequently removed from the casting mould.
  • thin-walled casting moulds known as ceramic shell moulds in the lost wax casting process, are frequently used.
  • ⁇ -titanium aluminides ⁇ -TiAl
  • nickel aluminides nickel-based alloys
  • TiAl alloys are distinguished by better creep properties and lower susceptibility to oxidation.
  • DE 103 46 953 A1 discloses a die for producing castings and a process for manufacturing the die.
  • the known casting mould is particularly suitable for handling TiAl alloys.
  • the casting mould is manufactured using the slurry dipping and sand coating process.
  • a wax blank in the shape of the casting to be made is prepared, repeatedly coated with a slurry, sand coated and then dried and cured. Finally, the wax blank is removed from the casting mould thus formed.
  • a slurry consisting of water, yttrium oxide, magnesium oxide and calcium oxide is used to produce the known casting mould. In this way, a casting mould is obtained in which at least one surface coming into contact with the reactive non-ferrous molten charge consists of yttrium oxide, magnesium oxide and calcium oxide.
  • the antifoaming agent is primarily intended to prevent bubbles from forming on the surface of the slurry, which could cause defects in the production of the casting mould. Acids and bases can also be added. Complicated, time-consuming tests are usually necessary to create a slurry system suitable for the purposes of specific applications.
  • Casting moulds/ceramic shell moulds for handling intermetallic compounds, particularly those of reactive TiAl alloys, are known in which the surfaces of the casting mould/ceramic shell mould facing the front are made of AI 2 O 3 /Y 2 O 3 (G. W. Dickhues: Feingusstechnologie für intermetallische ⁇ -TiAI-Legtechniken [Lost wax casting for intermetallic ⁇ -TiAl alloys], Erasmus 5 [Series 5]: Grund- und Maschinenstoffe [Primary matter and materials], no. 369, VDI-Verlag GmbH, 1994).
  • the casting moulds known as ceramic shell moulds based on the Al 2 O 3 /Y 2 O 3 or Al 2 O 3 system are also made by dipping and sand coating within the scope of the known dipping process.
  • Dickhues represents an attempt to produce SiO 2 -free ceramic shell moulds, as earlier lost wax casting methods used slurries which contained not only various ceramic filler systems but also primarily binders in the form of aqueous or alcoholic SiO 2 dispersions (silicic acid brine or ethyl silicate).
  • SiO 2 can be reduced by reactive molten charges, such as alloys based on TiAl or NiAl in ceramic shell moulds containing SiO 2 .
  • the consequence is considerable oxygen absorption by the molten charge, which may entail drastic losses of strength by the material.
  • the interaction between the molten charge and the ceramic shell mould may entail pronounced erosion, which may cause the ceramic shell mould/casting mould to be destroyed, the molten charge to absorb ceramic particles and/or poor surface quality of the casting.
  • Dickhues uses acrylic acid ester as a binder for the slurry for the front layers of the casting mould.
  • the purpose of the invention is to create a die for producing a casting from a reactive molten charge using a casting mould and a method for manufacturing the die which facilitates reliable, reproducible production of the casting mould.
  • independent claim 26 refers to the use of a die to cast a casting.
  • a die is made for producing a casting; particularly a component for a motor or other engine, from a reactive non-ferrous molten metal charge using a casting mould; which die has a front layer area which comes into contact with the reactive non-ferrous molten metal charge and a back-up layer area mechanically stabilising the front layer area, the front layer area consisting of a minimum of one rare earth oxide and a minimum of one additional metal oxide, the minimum of one additional metal oxide being selected from the group of oxides of the following metals: titanium and nickel.
  • a method for manufacturing a die for the production of a casting, particularly a motor or other engine component, from a reactive non-ferrous molten metal charge includes the following steps: providing of a wax blank with an external shape which reproduces the casting to be made; formation of a casting mould which has a front layer area which comes into contact with the reactive non-ferrous molten metal charge and a back-up layer area mechanically stabilising the front layer area, the wax blank being coated at least once with a slurry; drying and curing the casting mould; removal of the wax blank from the casting mould and firing of the casting mould; the front layer area of the casting mould being formed as a layer consisting of a minimum of one rare earth oxide and a minimum of one additional metal oxide, the minimum of one additional metal oxide being selected from the group of oxides of the following metals: titanium and nickel.
  • the particular advantage over the state of the art is that the sintering temperature for the front layer area is reduced and thus achieves improved fusion and ultimately improved physical properties.
  • a purposeful embodiment of the invention anticipates the minimum of one rare earth oxide being yttrium oxide.
  • a metal oxide which is an oxide from the same metal comprised in the reactive non-ferrous molten metal charge to be used in the casting mould.
  • Such metal oxide may therefore be referred to as a metal oxide of the same species, namely the same metal.
  • a possible contamination of the non-ferrous molten metal charge by external or parasitic elements can be minimized or even completely avoided.
  • positive effect refers also to the casting produced using the die. The generation of undesired phases in the casting is avoided.
  • exactly one metal oxide of the same species is used in the front layer area.
  • a titanium oxide is used in the front layer area of the casting mould.
  • a nickel oxide in case of a reactive non-ferrous molten metal charge based on a nickel alloy.
  • a purposeful embodiment of the invention anticipates the yttrium oxide having purity in excess of 99.9%, avoiding problems which could occur due to the presence of impurities in the front layer area.
  • a purposeful further development of the invention may provide for the ratio by weight between the minimum of one rare earth oxide and the minimum of one metal oxide exceeding 10:1.
  • the front layer area and/or the back-up layer area are purposefully produced by the slurry dipping and sand coating process.
  • This method has the advantage over other methods for manufacturing casting moulds/ceramic shell moulds that even contours with the small dimensions of the wax blank casting reproducing the casting to be produced are coated reliably.
  • an advantageous further development of the invention provides for the casting mould in which the front layer area which comes into contact with the reactive non-ferrous molten metal charge contains less than 0.1% SiO 2 by weight. This avoids unwanted reactions between the material of the front layer area and the molten charge.
  • a preferred embodiment of the invention anticipates that the casting mould in the front layer area and the back-up layer area is openly porous, rendering the casting form gas-permeable.
  • a preferred embodiment of the invention provides for the casting mould in the back-up layer area having pores making up a volumetric proportion of between 20% and 40%.
  • a purposeful further development of the invention may provide for the casting mould having a surface roughness (Ra) better than 3.2 ⁇ m.
  • Such high-quality surfaces are particularly advantageous to fluidic applications in motor and other engine components.
  • Such an advantageous embodiment provides for the casting mould having a strength in excess of 13 MPa.
  • Such casting mould strengths are particularly suitable for centrifugal casting.
  • back-up layer area is formed in various grain sizes, using aluminium oxide.
  • a purposeful further development of the invention anticipates the back-up area being produced using a minimum of one slurry containing an aqueous binder with an SiO 2 content. In this way, the stronger binding effect of SiO 2 , which leads to increased strengths of the back-up layer and thus of the entire casting mould, can be used.
  • a further reduction in the sintering temperature is achieved by forming the front layer area by using a very fine-grained powder, particularly a powder consisting of nanoparticles, such as yttrium oxide nanopowder. It is known that the sintering temperature of nanopowders is up to several hundred K below the sintering temperature of microscale powders.
  • One embodiment of the invention provides using a mixture of the minimum of one rare earth oxide and oxides of the metals which principally occur in the molten charge, e.g. TiO 2 in the case of titanium alloys.
  • the die with the casting mould can be used to cast a casting by introducing a non-ferrous molten metal charge into the casting mould, cooling and solidifying the non-ferrous molten metal charge in the casting mould so that a casting is formed, and removing the casting from the casting mould.
  • the dependent claims for the method for manufacturing the die for producing a casting show advantages named in connection with the relevant properties in the dependent claims for the die for producing a casting.
  • At least two different slurries are used: one to produce a front layer (FS) area facing a later casting and another to create a mechanically-stabilising back-up layer area (BS).
  • the sand coating materials are adapted to the slurry.
  • the ceramic components of the slurry made from an aqueous solution for the front-layer area are Y 2 O 3 powder with grain sizes between 1 ⁇ m and 50 ⁇ m and purity better than 99.9% and TiO 2 with a grain size of less than 10 ⁇ m.
  • the aggregate proportion of ceramic substances is greater than 80% by weight.
  • the ratio of the proportions (Y 2 O 3 /TiO 2 ) is greater than 10:1.
  • the residual proportions of the slurry are water, a water-soluble SiO 2 -free binder and discretionary further additives usual in lost wax casting such as liquefiers, wetting agents and/or antifoaming agents.
  • the slurry is a mixture of the different components.
  • a further slurry is used for the back-up layer area, with a solid content of approximately 60%, consisting of aluminium oxide powder mixed with powders with three different grain sizes.
  • Other constituents are an aqueous binder containing SiO 2 on a basis of silicic acid, water, wetting agent and antifoaming agent.
  • a wax blank the external shape of which corresponds to an article to be produced later with the casting mould, is dipped in the slurry for the front layer to form the front layer area. After the slurry has drained, the dipped wax blank is sand-coated with Y 2 O 3 powders with purity better than 99.9% and a grain diameter from 50-250 ⁇ m. A low fine-grain proportion is advantageous. These stages in the process are repeated several times with interim drying of the layers until the desired front layer thickness has been obtained.
  • the wax blank bearing the formed front layer area is dipped in the additional slurry for the back-up layer area. It is subsequently dried and sand coated with a mixture of commercial
  • Al 2 O 3 powders with three different grain sizes from 10-250 ⁇ m are also repeated several times with interim drying of the layers until the desired back-up layer area thickness has been obtained.
  • the final drying of the green form takes place for about 48 hours at room temperature following the final immersion in the additional slurry for the back-up layer area.
  • Superheated steam in a steam autoclave is used for subsequent de-waxing of the wax blank from the green form.
  • the de-waxed casting mould/ceramic shell mould is fired in air using a specified temperature gradient.
  • the time curve is particularly characterized by a specified heating rate, at least one arrest point at a specific temperature below 800° C. and a maximum temperature below 1600° C. Cooling takes place slowly in a switched-off kiln. Cleaning of the ceramic shell mould follows, before it can be used for casting.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
US11/670,489 2006-02-03 2007-02-02 Die for producing a casting and method for making the die Abandoned US20070181285A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102006005057A DE102006005057A1 (de) 2006-02-03 2006-02-03 Werkzeug zum Herstellen eines Gußteils und Verfahren zum Herstellen des Werkzeugs
DE102006005057.6 2006-02-03

Publications (1)

Publication Number Publication Date
US20070181285A1 true US20070181285A1 (en) 2007-08-09

Family

ID=37897761

Family Applications (1)

Application Number Title Priority Date Filing Date
US11/670,489 Abandoned US20070181285A1 (en) 2006-02-03 2007-02-02 Die for producing a casting and method for making the die

Country Status (3)

Country Link
US (1) US20070181285A1 (de)
EP (1) EP1826192A1 (de)
DE (1) DE102006005057A1 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102020108196B4 (de) 2020-03-25 2024-05-16 Technische Universität Bergakademie Freiberg Verfahren zur Herstellung einer keramischen, silikatfreien Feingussform für die Herstellung von Feingussteilen aus höherschmelzenden Metallen und Verwendung einer keramischen, silikatfreien Feingussform für die Herstellung von Feingussteilen aus höherschmelzenden Metallen

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4040845A (en) * 1976-03-04 1977-08-09 The Garrett Corporation Ceramic composition and crucibles and molds formed therefrom
US4131475A (en) * 1975-06-27 1978-12-26 General Electric Company Fabrication of shell investment molds
US5492957A (en) * 1991-04-04 1996-02-20 Shin-Etsu Chemical Co., Ltd. Face coat composition for casting mold and method for the preparation of casting mold having face coat layer
US5508242A (en) * 1990-05-11 1996-04-16 Rhone-Poulenc Chimie Yttrium oxide/titanium oxide ceramic compositions
US7229600B2 (en) * 2003-01-31 2007-06-12 Nanoproducts Corporation Nanoparticles of rare earth oxides

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3683086D1 (de) * 1985-06-06 1992-02-06 Remet Corp Giessen von reaktionsfaehigen metallen in keramische formen.
US4703806A (en) * 1986-07-11 1987-11-03 Howmet Turbine Components Corporation Ceramic shell mold facecoat and core coating systems for investment casting of reactive metals
US5407001A (en) * 1993-07-08 1995-04-18 Precision Castparts Corporation Yttria-zirconia slurries and mold facecoats for casting reactive metals
US5643844A (en) * 1994-09-27 1997-07-01 Precision Castparts Corporation Method for stabilizing ceramic suspensions
AT406673B (de) * 1998-03-04 2000-07-25 Treibacher Auermet Prod Gmbh Verwendung von metalloxiden zur bereitung keramischer formmassen
DE10346953A1 (de) * 2003-10-09 2005-05-04 Mtu Aero Engines Gmbh Werkzeug zum Herstellen von Gussbauteilen, Verfahren zum Herstellen des Werkzeugs und Verfahren zum Herstellen von Gussbauteilen

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4131475A (en) * 1975-06-27 1978-12-26 General Electric Company Fabrication of shell investment molds
US4040845A (en) * 1976-03-04 1977-08-09 The Garrett Corporation Ceramic composition and crucibles and molds formed therefrom
US5508242A (en) * 1990-05-11 1996-04-16 Rhone-Poulenc Chimie Yttrium oxide/titanium oxide ceramic compositions
US5492957A (en) * 1991-04-04 1996-02-20 Shin-Etsu Chemical Co., Ltd. Face coat composition for casting mold and method for the preparation of casting mold having face coat layer
US7229600B2 (en) * 2003-01-31 2007-06-12 Nanoproducts Corporation Nanoparticles of rare earth oxides

Also Published As

Publication number Publication date
DE102006005057A1 (de) 2007-08-16
EP1826192A1 (de) 2007-08-29

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Legal Events

Date Code Title Description
AS Assignment

Owner name: ACCESS E.V., GERMANY

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HUBNER, GUNTER;REEL/FRAME:019061/0019

Effective date: 20070305

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION