EP3366385A1 - Sable de moulage comprenant des nanoparticules de graphite et moule fabriqué à partir d'un tel sable de moulage - Google Patents

Sable de moulage comprenant des nanoparticules de graphite et moule fabriqué à partir d'un tel sable de moulage Download PDF

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Publication number
EP3366385A1
EP3366385A1 EP17305219.2A EP17305219A EP3366385A1 EP 3366385 A1 EP3366385 A1 EP 3366385A1 EP 17305219 A EP17305219 A EP 17305219A EP 3366385 A1 EP3366385 A1 EP 3366385A1
Authority
EP
European Patent Office
Prior art keywords
molding sand
binder
comprised
radical initiator
sand
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.)
Withdrawn
Application number
EP17305219.2A
Other languages
German (de)
English (en)
Inventor
Katarzyna PIWOWAR
Jan MOCEK
Marcin MYSZKA
Jerzy ZYCH
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.)
Safran Transmission Systems SAS
Original Assignee
Safran Transmission Systems SAS
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 Safran Transmission Systems SAS filed Critical Safran Transmission Systems SAS
Priority to EP17305219.2A priority Critical patent/EP3366385A1/fr
Publication of EP3366385A1 publication Critical patent/EP3366385A1/fr
Withdrawn legal-status Critical Current

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    • 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
    • B22C1/188—Alkali metal silicates
    • 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

Definitions

  • the invention generally relates to the field of foundry, particularly to the foundry of aluminum alloy cast pieces, more specifically of pieces serving as components of turbomachines such as aircraft turbojet engines.
  • turbojet engines are made of cast aluminum alloys, due to their good mechanical performances, resistance to thermal fatigue and lightness.
  • AGB accessory gear box
  • AGB accessory gear box
  • components e.g. an electric generator or a starter and driven by an input shaft of the turbomachine.
  • AlSi7Mg aluminum alloy
  • the surrounding is ordinarily casted within a mold made of a material (called molding sand) the main component of which is sand (typically silica sand), and further including a binding agent (or binder) together with a radical initiator - or curing agent - which gives the material its mechanical strength.
  • molding sand a material
  • sand typically silica sand
  • binding agent or binder
  • the solidification rate depends in turn of the thermal conductibility of the mold, i.e. its capability to evacuate calories from the liquid alloy.
  • chillers which have the exact shape of the cast piece. Those chillers are commonly made of metal. It is also known, however, to make those chillers out of graphite powder mixed with a binder (such as sodium silicate or a thermosetting resin) and hardened through carbon dioxide, see e.g. French patent FR 2 138 358 (Messier).
  • a binder such as sodium silicate or a thermosetting resin
  • That document does not state the thickness needed for the chiller to efficiently evacuate the calories and hence promote the increase of the solidification rate of the cast piece.
  • a first objective of the invention is to enhance mechanical performances of the cast pieces, particularly pieces made from aluminum alloy, and more specifically pieces serving as components in turbomachines.
  • a second objective of the invention is to provide a material intended for the manufacturing of a casting mold which promotes a greater solidification rate of the cast alloy.
  • a third objective of the invention is to provide a method for preparing such a material, which is simple to implement.
  • a molding sand comprising:
  • a casting mold made of a molding sand as disclosed hereinbefore.
  • a method of manufacturing a cast piece in an aluminum alloy comprising a step of casting the alloy within such a mold.
  • a casting mold 1 is shown on FIG.1 to FIG.3 .
  • This mold 1 comprises a hollow molding cavity 2 made as a print from a piece 3 to be made by the casting, within the cavity 2, of a metal alloy 4, e.g. an aluminum alloy.
  • the alloy 4 is an aluminum alloy from the EN AC-4000 series (according to European standard EN 1780-1), i.e. having silica as main additive element.
  • the alloy is, for example, AlSi7Mg, including 7% silica and less than 1% magnesium. Such alloy is most appropriate for the casting of components of a turbomachine (and more specifically a turbojet engine).
  • the mold 1 comprises several (two here) blocks 1A, 1B each having embossings 2A, 2B (either hollow or protruding) which, whenever the blocks 1A, 1B are side by side ( FIG.1, FIG.2 ), together define the molding cavity 2.
  • the mold 1 is made of a molding sand 5 comprising:
  • each block 1A, 1B is made of the same molding sand 5.
  • the sand 6 used for the matrix is a quartz sand; it is preferably made of grains of quartz the size of which is comprised between 200 and 300 ⁇ m.
  • the binder 7 comprises sodium or potassium silicate together with graphite particles of nanometric size.
  • a particle of nanometric size is a particle the size of which is lower than 100 nm, according to ISO/TS 80004-2:2015 standard.
  • the size of the graphite nanoparticles is comprised between 500 nm and 800 nm.
  • the mass proportion of binder 7, with respect to the matrix is preferably comprised between 2.5% and 5%.
  • the radical initiator 8 is a chemical which is characterized by its capability to form free radicals, i.e. molecules in which the outer shell electrons have not formed bonds yet and hence give those molecules a great chemical reactivity.
  • the radical initiator 8 is here initially chosen (i.e. before it is in contact with the binder 7, with which it is to react) among the following compounds:
  • the mass proportion of radical initiator 8, with respect of the sodium or potassium silicate, is preferably comprised between 10% and 15%.
  • the preparation of the molding sand 5 comprises three phases.
  • a first phase consists of preparing the binder 7.
  • water glass 9 is mixed with colloidal graphite 10.
  • Water glass is a common name for a sodium or potassium silicate solution.
  • the proportion of the colloidal graphite 10 with respect to water glass 9 is preferably comprised between 5% and 20%.
  • the water glass 9 and the colloidal graphite solution 10 are poured into a mixer 11. Mixing the water glass 9 and the colloidal graphite solution 10 within the mixer 11 produces the binder 7.
  • a second phase which may be conducted before, during or after the first phase, consists of mixing the radical initiator 8 with the matrix (i.e. the quartz sand 6 ).
  • the radical initiator 8 and the quartz sand 6 are poured into a mixer 12 in which they are mixed to form a primary mixture 13.
  • the mass proportion of the radical initiator 8 is measured with respect to the liquid glass 9. More precisely, the mass proportion of radical initiator 8, with respect to the water glass 9, is preferably comprised between 10% and 15%.
  • This phase is based upon the assertion that the radical initiator 8 is under liquid form (which is the case with acetic acid, carbonic acid and ester acid).
  • a third phase comprises adding the binder 7 resulting from the first phase to the primary mixture 13, and mixing the resulting mixture - which is the molding sand 5 in a pasty form.
  • the mixing may be achieved in the mixer 12 used to obtain the primary mixture 13, or in a different mixer 14 ( FIG.4 is merely schematic and covers both cases).
  • the time of mixing the pasty molding sand 5 is preferably of about 2 min.
  • the pasty (i.e. not hardened yet) molding sand 5 may then be given the shape of the mold 1 - and more specifically the shape of each mold block 1A, 1B.
  • the radical initiator 8 fulfills its curing agent function after this shaping, whereby strength of the molding sand 5 forming each mold block 1A, 1B is sufficient to allow the latter to maintain its shape.
  • the binder 7 resulting from the first step is directly mixed with pure quartz sand 6, under carbon dioxide atmosphere, which then plays the role of curing agent while the binder 7 and sand 6 are mixed in mixer 13 or 14.
  • Manufacturing the cast piece 3 comprises a step of assembling various mold blocks 1A, 1B to form the molding cavity 2 ( FIG.1 ), and a step of casting the alloy 4, which has previously been molten, in the molding cavity 2 ( FIG.2 ).
  • AlSi7Mg is molten at about 800°C.
  • the molding sand 5 forming the mold 1 absorbs and diffuses the calories at a rate greater than that of a conventional molding sand, which gives the alloy 4 a cooling rate greater than the known cooling rates (with equal shape), as shown by FIG.5 on which there is drawn:
  • Each curve C, C' has a global similar shape, and comprises a first section S1, S1' (where S1 , for the first curve C, is comprised between 0 and about 70s, whereas S1', for the second curve C', is comprised between 0 and about 130s).
  • the first section S1, S1' corresponds to the liquid form of the alloy, in which the variation of temperature is nonlinear.
  • Each curve C, C' also comprises a second section S2, S2' (where S2, for the first curve C, extends from about 70s, whereas S2', for the second curve C', extends from about 130s).
  • the second section S2, S2' corresponds to the solid form of the alloy, in which variation of temperature is globally linear.
  • the temperature (of about 550°C) corresponding to the junction between section S1 (respectively S1' ) and the second section S2 (respectively S2' ) is the solidification temperature of the alloy (referred to as TS ).
  • the manufacturing time (and hence the production rate) with a mold 1 according to the invention is shorter.
  • the lowered cooling rate gives the piece 3 a crystal structure of better quality, due to thinner crystal grains, as depicted on:
  • the alloy solidified in the mold 1 according to the invention has a greater hardness, and hence a greater mechanical strength.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
EP17305219.2A 2017-02-28 2017-02-28 Sable de moulage comprenant des nanoparticules de graphite et moule fabriqué à partir d'un tel sable de moulage Withdrawn EP3366385A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP17305219.2A EP3366385A1 (fr) 2017-02-28 2017-02-28 Sable de moulage comprenant des nanoparticules de graphite et moule fabriqué à partir d'un tel sable de moulage

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP17305219.2A EP3366385A1 (fr) 2017-02-28 2017-02-28 Sable de moulage comprenant des nanoparticules de graphite et moule fabriqué à partir d'un tel sable de moulage

Publications (1)

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EP3366385A1 true EP3366385A1 (fr) 2018-08-29

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EP17305219.2A Withdrawn EP3366385A1 (fr) 2017-02-28 2017-02-28 Sable de moulage comprenant des nanoparticules de graphite et moule fabriqué à partir d'un tel sable de moulage

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EP (1) EP3366385A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2138358A1 (en) 1971-05-24 1973-01-05 Messier Fa High thermal conductivity powder - for use in casting of aluminium alloy or magnesium articles
WO2012175883A1 (fr) 2011-06-22 2012-12-27 Snecma Ventilation de relais d'accessoires, turboreacteur comportant un tel relais
CN104057017A (zh) * 2014-05-28 2014-09-24 安徽鑫润新型材料有限公司 一种大型铸件用型砂及其制备方法
CN105414465A (zh) * 2015-11-23 2016-03-23 合肥李诺新材料贸易有限公司 一种泵阀铸件用高活性复合改性水玻璃砂及其制备方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2138358A1 (en) 1971-05-24 1973-01-05 Messier Fa High thermal conductivity powder - for use in casting of aluminium alloy or magnesium articles
WO2012175883A1 (fr) 2011-06-22 2012-12-27 Snecma Ventilation de relais d'accessoires, turboreacteur comportant un tel relais
CN104057017A (zh) * 2014-05-28 2014-09-24 安徽鑫润新型材料有限公司 一种大型铸件用型砂及其制备方法
CN105414465A (zh) * 2015-11-23 2016-03-23 合肥李诺新材料贸易有限公司 一种泵阀铸件用高活性复合改性水玻璃砂及其制备方法

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
"Microwaves in Nanoparticle Synthesis", 24 April 2013, WILEY-VCH VERLAG GMBH & CO. KGAA, Weinheim, Germany, ISBN: 978-3-52-733197-0, article SATOSHI HORIKOSHI ET AL: "Introduction to Nanoparticles", pages: 1 - 24, XP055198443, DOI: 10.1002/9783527648122.ch1 *
"Nanotechnologies - Vocabulary - Part 2: Nano-objects", ISO TS 80004-2:2015, IEC, 3, RUE DE VAREMBÉ, PO BOX 131, CH-1211 GENEVA 20, SWITZERLAND, 4 January 2015 (2015-01-04), pages 1 - 10, XP082006389 *
J. ZYCH ET AL: "Thermal Conductivity of Moulding Sand with Chemical Binders, Attempts of its Increasing", ARCHIVES OF METALLURGY AND MATERIALS, vol. 60, no. 1, 1 January 2015 (2015-01-01), Poland, XP055393704, ISSN: 1733-3490, DOI: 10.1515/amm-2015-0058 *

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