EP0020373B1 - Procede de fabrication et d'utilisation d'un moule a coquille en ceramique - Google Patents

Procede de fabrication et d'utilisation d'un moule a coquille en ceramique Download PDF

Info

Publication number
EP0020373B1
EP0020373B1 EP19790900983 EP79900983A EP0020373B1 EP 0020373 B1 EP0020373 B1 EP 0020373B1 EP 19790900983 EP19790900983 EP 19790900983 EP 79900983 A EP79900983 A EP 79900983A EP 0020373 B1 EP0020373 B1 EP 0020373B1
Authority
EP
European Patent Office
Prior art keywords
mold
barrier coating
graphite
hardened
applying
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
Application number
EP19790900983
Other languages
German (de)
English (en)
Other versions
EP0020373A1 (fr
EP0020373A4 (fr
Inventor
Richard C. Ostrowski
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.)
Caterpillar Inc
Original Assignee
Caterpillar Tractor Co
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 Caterpillar Tractor Co filed Critical Caterpillar Tractor Co
Priority to EP19790900983 priority Critical patent/EP0020373B1/fr
Publication of EP0020373A4 publication Critical patent/EP0020373A4/fr
Publication of EP0020373A1 publication Critical patent/EP0020373A1/fr
Application granted granted Critical
Publication of EP0020373B1 publication Critical patent/EP0020373B1/fr
Expired legal-status Critical Current

Links

Images

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
    • 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
    • B22C1/165—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 in the manufacture of multilayered shell moulds

Definitions

  • This invention relates to the preparation of a ceramic shell mold useful for investment casting purposes, and particularly to a method of making a shell mold that will effectively reduce the amount of surface decarburization of a ferrous article formed in the shell mold.
  • Investment casting also referred to as the "lost wax" process, typically involves alternate applications of a ceramic coating composition and a stucco composition to an expendable pattern in order to provide a multi-layered shell mold.
  • the pattern is usually made of wax, plastic or similar material which is melted out to leave a correspondingly shaped internal cavity into which molten metal is poured.
  • U.S. Patent 3,153,826 discloses a method of making a ceramic shell mold including Step (a) alternately applying a coating composition including a ceramic powder and a binder, and then a stucco composition including granular refractory material to an expendable pattern a preselected number of times, drying the coating between applications, and forming a resultant multi-layered mold, Step (b) heating the multi-layered mold, removing the pattern, and forming a resultant hardened mold, and Step (c) applying a barrier coating.
  • the present invention is directed to overcoming one or more of the problems as set forth above.
  • a ceramic shell mold is made according to claim 1.
  • the sole figure is a diagrammatic and enlarged, fragmentary cross sectional view through a multi-layered shell mold having a barrier coating thereon in accordance with the present invention.
  • a preferred method of making a ceramic shell mold 6 comprises the steps of alternately applying a ceramic coating composition 8 and a stucco composition 10 to an expendable or thermally meltable pattern a pre-selected number of times, firing such multi-layered mold to remove the pattern and provide a hardened mold 12 having an internal casting cavity 14, and applying a barrier coating 16 including a ceramic powder, a binder and a preselected amount of graphite as is generally illustrated in the drawing.
  • the presence of any significant amount of graphite is preferably avoided in the multi-layered mold, particularly adjacent the casting cavity 14, and is preferably controlled to a range of about 13 to 17 Wt.% graphite of the total amount of the solid portion of the barrier coating 16.
  • the aforementioned ceramic coating composition 8 basically includes a ceramic powder and a binder.
  • the ceramic powder is selected from the group consisting essentially of fused silica, vitreous silica, crystalline silica, alumina silicate, alumina, magnesium silicate, zircon, zirconium silicate, and clay treated to remove impurities, and can be mixtures thereof.
  • the binder is selected from the group consisting essentially of colloidal silica sol, ethyl silicate, aluminum phosphate, and aqueous alkali metal silicate.
  • the stucco composition 10 basically includes conventional granular refractory materials such as zircon.
  • the multi-layered mold made by alternately applying the ceramic coating composition 8 and the stucco composition 10 a preselected number of times to the pattern is substantially free of graphite.
  • this term it is meant that less than 0.5 Wt.% graphite is present in the multi-layered mold before the barrier coating 16 is applied.
  • a preferred method of making the ceramic shell mold 6 includes the following steps:
  • a ferrous molten metal such as steel is poured into the casting cavity 14 of the ceramic shell mold 6.
  • the mold is maintained at a temperature of about 1000°C (1830°F), or slightly below, since the molten metal poured therein is about 1350 to 1700°C (2460 to 3100°F) and this minimizes the temperature differential therebetween.
  • drying Step (d) can be achieved under ambient air conditions for a period of about one-half to one hour, or alternatively the drying can be achieved in an oven or furnace at a temperature slightly above ambient temperature to reduce the holding time.
  • the temperature cannot be elevated too much because the pattern either can melt or can expand to the point of unduly stressing the relatively weak walls of the partially complete mold.
  • Step (f) One of the advantages of this method of investment casting is that it is easier to melt out and remove the pattern from the multi-layered mold because it has a thinner section during intermediate Step (f) than the equivalent strength prior art shell mold has at the time of pattern removal. I have also noted a consistently higher quality of the hardened molds 12 when compared with the thicker prior art molds. Furthermore, Step (g) can be achieved without the need for a reducing atmosphere because the multi-layered mold is substantially free of graphite at that stage.
  • zircon can be replaced by an equivalent amount of alumina silicate.
  • the barrier coating is preferably about 78 Wt% of dry materials including the aforementioned zircon or alumina silicate, fused silica, and graphite, and the remaining 22 Wt.% is substantially liquid binder including the colloidal silica sol.
  • the preferred proportions of the dry materials in the barrier coating 16 are about 75 parts zircon, 25 parts fused silica, and 11 to 25 parts graphite by weight.
  • Steps (h), (i), and (j) were achieved by repetitively dipping the hardened mold 12 while hot into an agitated thixotropic solution of the aforementioned ceramic and graphite materials for about four or five seconds and removing the mold to permit substantial gelling of the ceramic materials during periods of about 30 seconds therebetween in ambient air.
  • the fact that the mold is hot accelerates the gelling and tends to bridge the ceramic materials over any minor imperfections.
  • Such dipping was automatically accomplished by a known mechanical dipping apparatus provided with a suitable timing and counting control system, not shown.
  • test data indicates that the prior art ceramic shell mold with substantially no graphite therein exhibited an undesirably high level of decarburization, and the articles prepared in accordance with one aspect of the present invention exhibited a decreasing degree of decarburization as the proportion of graphite in the barrier coating 16 increased up to about 17 Wt.96.
  • the broad range of graphite in the barrier coating 16 is about 4 to 20 Wt.%, the preferred range is about 13 to 17 Wt.%, and the most desirable amount is about 15 Wt.%.
  • the problems of decarburization and surface blemishes of investment cast articles is more severe when the amount of carbon in the ferrous molten metal is reduced toward 0.1 Wt.96 carbon.
  • the method of the present invention is particularly useful for minimizing decarburization of steel articles with less than 1.5 Wt.% carbon.
  • Graphite is reactive to oxygen, and the reaction is accelerated as the temperature increases. In a crystalline material such as the shell mold, graphite will travel in the porous interstices thereof during heating.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Mold Materials And Core Materials (AREA)

Abstract

Un procede de fabrication d'un moule a coquille (6) consiste a appliquer alternativement une composition de revetement ceramique (8) et une composition de stuc (10) sur un modele expansible, le graphite etant sensiblement inexistant, et a appliquer par dessus un revetement formant barriere (16) comprenant une poudre ceramique, un liant, et une quantite predeterminee de graphite. La quantite de graphite se situe de preference dans une plage comprise entre 13 et 17% en poids dans le revetement barriere (16), pour reduire au minimum la decarburation d'un article ferreux forme dans la cavite d'un moule a coquille (6).

Claims (13)

1. Procédé de fabrication d'une coquille de moulage en céramique comportant:
Etape (a) l'application alternée d'une composition de revêtement (8) comportant une poudre céramique et un liant, puis d'une composition de stuc (10) comportant une matière réfractaire granuleuse, sur un modèle non réutilisable, un nombre de fois prédéterminé, le séchage du revêtement entre les applications, et la formation d'un moule à couches multiples résultant,
Etape (b) le chauffage du moule à couches multiples, l'enlèvement du modèle, et la formation d'un moule durci résultant (12), et Etape (c) l'application d'un revêtement protecteur (16), caractérisé en ce que:
le moule à couches multiples de l'Etape (a) contient moins de 0,5% en poids de graphite; et
l'Etape (c) comporte l'application du revêtement protecteur (16) sur la surface extérieure du moule à couches multiples (12) tandis que le moule durci (12) se trouve à une température prédéterminée au-dessus de la température ambiante, ledit revêtement protecteur (16) comportant un mélange d'une poudre céramique, d'un liant, et d'une quantité prédéterminée de graphite en particules dans une proportion de 4 à 20% en poids de la partie solide du revêtement protecteur (16).
2. Procédé selon la revendication 1, dans lequel l'Etape (c) comporte l'application du revêtement protecteur (16) sur le moule durci (12) tandis que le moule durci est à une température de 200°C environ.
3. Procédé selon la revendication 1, dans lequel l'Etape (c) comporte le choix du mélange de revêtement protecteur sous la forme d'une solution thixotropique de zircon, de silice fondue, de graphite en particules et d'un sol de silice colloïdale.
4. Procédé selon la revendication 1, dans lequel l'Etape (c) comporte le choix du mélange de revêtement protecteur sous la forme d'une solution thixotropique de silicate d'alumine, de silice fondue, de graphite en particules et de silice colloïdale.
5. Procédé selon la revendication 1, comportant le maintien de ladite quantité prédéterminée de graphite en particules dans l'intervalle de 13 à 17% en poids de la partie solide du revêtement protecteur (16).
6. Procédé selon la revendication 1, comportant le choix de ladite quantité prédéterminée de graphite en particules à 15% en poids de la partie solide du revêtement protecteur (16).
7. Procédé selon la revendication 1, comportant le maintien de ladite quantité prédéterminée de graphite en particules à une granulométrie inférieure à 0,075 mm.
8. Procédé selon la revendication 1, comportant le maintien de ladite quantité prédéterminée de graphite en particules dans un intervalle de granulométrie AFS de 0,01 mm à 0,05 mm.
9. Procédé selon la revendication 1, dans lequel l'Etape (c) comporte une répétition des opérations de trempage du moule durci (12) dans une solution thixotropique agitée du revêtement protecteur (16), puis de retrait du moule de cette solution.
10. Procédé de moulage à cire perdue d'un objet ferreux dans une coquille de moulage (6) comprenant:
Etape (a): l'application d'une composition de revêtement (8) comportant une poudre céramique et un liant sur un modèle non réutilisable, ladite poudre céramique étant choisie dans le groupe qui se compose essentiellement de la silice fondue, de la silice vitreuse, de la silice cristalline, du silicate d'alumine, de l'alumine, du silicate de magnésium, du zircon, du silicate de zirconium, et de l'argile, et le liant étant choisi dans le groupe qui se compose essentiellement des sols de silice colloïdale, du silicate d'éthyle, du phosphate d'alumium, et des solutions aqueuses de silicates de métaux alcalins;
Etape (b): l'application d'une composition de stuc (10) comportant une matière réfractaire granuleuse;
Etape (c): la répétition alternée des étapes (a) et (b) un nombre de fois prédéterminé, et la formation d'un moule à couches multiples, ledit moule à couches multiples contenant moins de 0,5% en poids de graphite;
Etape (d): le chauffage du moule à couches multiples et la formation d'un moule durci (12) comportant une cavité interne (14);
Etape (e): l'application d'un revêtement protecteur (16) sur la surface extérieure (20) du moule durci (12) à un endroit situé à une certaine distance de la cavité interne (14) et tandis que le moule durci (12) est encore chaud, ledit revêtement protecteur (16) comportant une partie solide et étant formé d'un mélange d'une poudre céramique, d'un liant, et d'une quantité prédéterminée de graphite finement divisé, ladite quantité prédéterminée de graphite étant comprise dans l'intervalle de 4 à 20% en poids de la partie solide du revêtement protecteur (16);
Etape (f): le chauffage du moule durci (12) et du revêtement protecteur (16) et la formation d'une coquille de moulage chaude (6); et
Etape (g): la coulée d'un métal ferreux en fusion dans la cavité interne (14) de la coquille de moulage chaude (6).
11. Procédé selon la revendication 10, dans lequel l'étape (e) comporte le maintien de ladite quantité prédéterminée de graphite dans un intervalle de 13 à 17% en poids.
12. Procédé selon la revendication 10, dans lequel l'Etape (e) comporte le trempage, un nombre de fois prédéterminé, du moule durci chaud (12) dans une solution thixotropique pour appliquer le revêtement protecteur (16).
13. Procédé selon la revendication 12, dans lequel l'Etape (e) comporte le maintien du graphite finement divisé contenu dans la solution thixotropique dans un intervalle de granulométrie AFS de 0,01 mm à 0,05 mm.
EP19790900983 1978-12-04 1978-12-04 Procede de fabrication et d'utilisation d'un moule a coquille en ceramique Expired EP0020373B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP19790900983 EP0020373B1 (fr) 1978-12-04 1978-12-04 Procede de fabrication et d'utilisation d'un moule a coquille en ceramique

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
PCT/US1978/000187 WO1980001146A1 (fr) 1978-12-04 1978-12-04 Procede de fabrication et d'utilisation d'une moule a coquille en ceramique
EP19790900983 EP0020373B1 (fr) 1978-12-04 1978-12-04 Procede de fabrication et d'utilisation d'un moule a coquille en ceramique

Publications (3)

Publication Number Publication Date
EP0020373A4 EP0020373A4 (fr) 1980-09-29
EP0020373A1 EP0020373A1 (fr) 1981-01-07
EP0020373B1 true EP0020373B1 (fr) 1983-06-08

Family

ID=22141288

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19790900983 Expired EP0020373B1 (fr) 1978-12-04 1978-12-04 Procede de fabrication et d'utilisation d'un moule a coquille en ceramique

Country Status (5)

Country Link
EP (1) EP0020373B1 (fr)
JP (1) JPS55500934A (fr)
CA (1) CA1119771A (fr)
DE (1) DE2862282D1 (fr)
WO (1) WO1980001146A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5617912A (en) * 1904-04-14 1997-04-08 Ballewski; Heinrich Process for preparing and using a ceramic shell as a casting mold with reducing properties

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2213762A (en) * 1987-12-22 1989-08-23 Steel Castings Res Manufacture of ceramic shell moulds
US8735734B2 (en) 2009-07-23 2014-05-27 Lexmark International, Inc. Z-directed delay line components for printed circuit boards
US9078374B2 (en) 2011-08-31 2015-07-07 Lexmark International, Inc. Screening process for manufacturing a Z-directed component for a printed circuit board
US8790520B2 (en) 2011-08-31 2014-07-29 Lexmark International, Inc. Die press process for manufacturing a Z-directed component for a printed circuit board
US8658245B2 (en) 2011-08-31 2014-02-25 Lexmark International, Inc. Spin coat process for manufacturing a Z-directed component for a printed circuit board
US9009954B2 (en) 2011-08-31 2015-04-21 Lexmark International, Inc. Process for manufacturing a Z-directed component for a printed circuit board using a sacrificial constraining material
US20130341078A1 (en) * 2012-06-20 2013-12-26 Keith Bryan Hardin Z-directed printed circuit board components having a removable end portion and methods therefor
US8943684B2 (en) 2011-08-31 2015-02-03 Lexmark International, Inc. Continuous extrusion process for manufacturing a Z-directed component for a printed circuit board
US8752280B2 (en) 2011-09-30 2014-06-17 Lexmark International, Inc. Extrusion process for manufacturing a Z-directed component for a printed circuit board
US8822840B2 (en) 2012-03-29 2014-09-02 Lexmark International, Inc. Z-directed printed circuit board components having conductive channels for controlling transmission line impedance
US8830692B2 (en) 2012-03-29 2014-09-09 Lexmark International, Inc. Ball grid array systems for surface mounting an integrated circuit using a Z-directed printed circuit board component
US8822838B2 (en) 2012-03-29 2014-09-02 Lexmark International, Inc. Z-directed printed circuit board components having conductive channels for reducing radiated emissions
US8912452B2 (en) 2012-03-29 2014-12-16 Lexmark International, Inc. Z-directed printed circuit board components having different dielectric regions

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU178952A (fr) *
GB672535A (en) * 1950-02-06 1952-05-21 Bristol Aeroplane Co Ltd Improvements in or relating to refractory moulds
US3126597A (en) * 1961-04-07 1964-03-31 Decarburization in casting of steel
US3153826A (en) * 1962-01-10 1964-10-27 Prec Metalsmiths Inc Precision casting molds and techniques
GB1132361A (en) * 1966-01-17 1968-10-30 Monsanto Chemicals Casting metals
GB1160090A (en) * 1967-07-18 1969-07-30 Adam Dunlop Moulds and Cores for Casting
US3656983A (en) * 1970-10-14 1972-04-18 Us Army Shell mold composition

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5617912A (en) * 1904-04-14 1997-04-08 Ballewski; Heinrich Process for preparing and using a ceramic shell as a casting mold with reducing properties

Also Published As

Publication number Publication date
DE2862282D1 (en) 1983-07-14
CA1119771A (fr) 1982-03-16
EP0020373A1 (fr) 1981-01-07
WO1980001146A1 (fr) 1980-06-12
EP0020373A4 (fr) 1980-09-29
JPS55500934A (fr) 1980-11-13

Similar Documents

Publication Publication Date Title
US2961751A (en) Ceramic metal casting process
EP0020373B1 (fr) Procede de fabrication et d'utilisation d'un moule a coquille en ceramique
US2948935A (en) Process of making refractory shell for casting metal
US4664172A (en) Method for production of investment shell mold for grain-oriented casting of super alloy
US3266106A (en) Graphite mold and fabrication method
US3196506A (en) Method of making a shell mold by lost wax process
US4284121A (en) Process and materials for making refractory cores
US4223716A (en) Method of making and using a ceramic shell mold
CN110340279A (zh) 大型铸件铸造方法
US3441078A (en) Method and apparatus for improving grain structures and soundness of castings
US3802902A (en) Method of making molds
PL188600B1 (pl) Sposób wytwarzania ceramicznej formy skorupowej do odlewania metodą traconego wosku
CA2539122C (fr) Composition de moulage et procede d'utilisation
US3153826A (en) Precision casting molds and techniques
EP0096985A1 (fr) Revêtement de creuset et procédé de fabrication ainsi que son utilisation
RU2314891C1 (ru) Способ изготовления форм для литья по выплавляемым моделям
EP0502580A1 (fr) Moule de coulée
US3583468A (en) Precision metal casting molds
US4995443A (en) Process for evaporative pattern casting
US3148422A (en) Production of shell moulds
CN113894251B (zh) 一种铸造用高惰性模壳及其制备方法和提高镁合金铸件精度的方法
US3389743A (en) Method of making resinous shell molds
US3420644A (en) Method for molding of glass and ceramic materials
JPH04333343A (ja) セラミックシェル鋳型の製造方法
US3815658A (en) Process for making a metallurgically slow reacting mold

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19800609

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE FR GB

RBV Designated contracting states (corrected)

Designated state(s): DE FR GB

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB

REF Corresponds to:

Ref document number: 2862282

Country of ref document: DE

Date of ref document: 19830714

ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19840911

Year of fee payment: 7

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19840915

Year of fee payment: 7

GBPC Gb: european patent ceased through non-payment of renewal fee
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19860829

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Effective date: 19860902

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19881118