EP0535854A1 - Moules - Google Patents

Moules Download PDF

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Publication number
EP0535854A1
EP0535854A1 EP92308671A EP92308671A EP0535854A1 EP 0535854 A1 EP0535854 A1 EP 0535854A1 EP 92308671 A EP92308671 A EP 92308671A EP 92308671 A EP92308671 A EP 92308671A EP 0535854 A1 EP0535854 A1 EP 0535854A1
Authority
EP
European Patent Office
Prior art keywords
metal
tool
mould
ceramic
composition
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.)
Ceased
Application number
EP92308671A
Other languages
German (de)
English (en)
Inventor
Carl Siviter
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.)
Foseco International Ltd
Original Assignee
Foseco International Ltd
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 Foseco International Ltd filed Critical Foseco International Ltd
Publication of EP0535854A1 publication Critical patent/EP0535854A1/fr
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B1/00—Producing shaped prefabricated articles from the material
    • B28B1/007—Producing shaped prefabricated articles from the material by freezing the material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B1/00—Producing shaped prefabricated articles from the material
    • B28B1/26—Producing shaped prefabricated articles from the material by slip-casting, i.e. by casting a suspension or dispersion of the material in a liquid-absorbent or porous mould, the liquid being allowed to soak into or pass through the walls of the mould; Moulds therefor ; specially for manufacturing articles starting from a ceramic slip; Moulds therefor
    • B28B1/261—Moulds therefor
    • B28B1/262—Mould materials; Manufacture of moulds or parts thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B7/00—Moulds; Cores; Mandrels
    • B28B7/34—Moulds, cores, or mandrels of special material, e.g. destructible materials
    • B28B7/346—Manufacture of moulds

Definitions

  • This invention relates to moulds and particularly to porous moulds as, for example, are used in the manufacture of pottery and ceramic articles by methods such as roller moulding and slip casting.
  • moulds used in slip casting and the manufacture of pottery articles are made of porous material e.g. Plaster of Paris.
  • This material has many advantages; it is relatively inexpensive, easy to form to simple or intricate shapes and has the required degree of porosity. However, its use does entail certain disadvantages.
  • Plaster of Paris pottery moulds are not particularly durable and, depending on the intricacy of the pattern and the quality of the product, may only last for as few as 40 moulding cycles before having to be scrapped. The material cannot be reprocessed.
  • Another serious disadvantage is that Plaster of Paris moulds cannot withstand temperatures in excess of about 55°C at normal humidity. Thus, drying times for the moulded product are longer than would be necessary if a higher temperature could be withstood without damage to the mould.
  • ceramic moulds be made by immersing a suitably shaped pattern into a slurry of the ceramic composition, freeze-gelling the slurry and then firing the frozen shaped body so produced to obtain the desired mould.
  • moulds produced by this means have, in principle, advantages over the above-mentioned Plaster of Paris moulds, it has not hitherto proved possible in practice to adapt this freeze-gelling technique to the reliable commercial production of a variety of mould patterns, particularly where intricate shapes are required.
  • conventional metal patterns have been proposed for use in such freeze-forming processes, it has proved difficult to achieve the high degree of uniformity, particularly of thickness, that is essential to achieve uniformity of heat transference in the freezing process. This is particularly important where complex three-dimensional patterns are required.
  • the present invention aims to provide an improved mould which overcomes the above-mentioned disadvantages associated with Plaster of Paris and provides a ceramic mould of improved quality.
  • the invention provides a method of making a porous mould in which a replica of the required mould is flame-sprayed with metal to form a metal tool, the metal tool is charged with a freeze-gellable ceramic sol composition, the temperature of the metal tool is lowered at a cooling rate sufficient to irreversibly gel the sol composition, the monolith so formed then being demoulded and fired.
  • the ceramic monolith will be allowed to thaw and dry before it is fired to give the desired ceramic mould product.
  • the sol used is preferably a silica sol.
  • the sol may have filler materials added to it to improve the strength of the product and to reduce shrinkage associated with drying and firing. Any suitable fillers may be used as desired. It will be appreciated that fillers should be chosen that are not chemically reactive with the freeze sensitive sol so as to avoid localised gelling without freezing.
  • the silica sol preferably contains from about 30% to 50% by weight, of silica, although amounts outside that range may be found to be satisfactory.
  • the colloidal particles in the sol are usually from 1 nanometer to 1 micron in size but preferably 2 nanometers to 100 nanometers.
  • the sols may be stabilised by means of sodium or ammonium ions, for example.
  • the replica of the desired shape may be of any suitable material, e.g. metal, wood or Plaster of Paris. Simple or very intricate shapes can be formed as the desired replica and these shapes are then accurately reproduced in metal by the spraying process.
  • the metal tool so formed is of extremely uniform thickness and provides excellent, uniform heat-transference in the subsequent freeze-gelling process.
  • the metal tool does not have the shrinkage problem associated with cast forms and so can be made to much finer tolerances.
  • the invention provides a metal pattern tool for a porous ceramic mould, the pattern tool being a flame-sprayed metal reproduction of the contours of a replica of the desired porous ceramic mould.
  • mould products can be produced of wall thickness of greater uniformity than conventionally obtained.
  • the sprayed metal is preferably an alloy primarily consisting of tin and zinc but other metals and alloys, e.g. zinc, aluminium copper or brass may be used, if desired.
  • Electric arc flame spraying is the preferred technique. Electric arc spraying is cooler than an alternative such as oxy-acetylene spraying and so there is less chance of the metal deposition damaging the replica of e.g. Plaster of Paris.
  • the finished porous mould is formed completely of the freeze-gelled ceramic sol composition, whereas, if desired, the freeze-gelled ceramic sol composition may be used as a surface coating backed with a porous and permeable base of, e.g. Plaster of Paris, to produce a composite article.
  • the freeze-gelled ceramic sol composition may be used as a surface coating backed with a porous and permeable base of, e.g. Plaster of Paris, to produce a composite article.
  • Moulds of the invention can be subjected to much higher temperature cycles in use, e.g. up to 1000°C and so cycle times can be considerably reduced.
  • the moulds are also stronger than corresponding Plaster of Paris moulds, they last longer and they enable stocks to be reduced.
  • the rate at which the ceramic sol composition is cooled is important in producing an irreversible-gelled monolithic product.
  • the net rate of cooling will depend on various aspects of the system used. For example, the temperature may have to be as low as - 80°C or lower to effect the desired cooling rate to the ceramic sol composition. Other temperatures may also produce the desired cooling rate dependent on the heat transfer characteristics of the system. Clearly, water-based sols may start to freeze at about 0°C but sols based on other fluids may start to freeze at different temperatures. The skilled man of the art will readily be able to choose temperatures and cooling rates most suited to the particular circumstances.
  • Freezing may be achieved by any convenient means, such as, for example, pumping a cooled liquid around the metal tool containing the sol composition or placing the tool in a cooled bath e.g. of alcohol cooled with pellets of solid carbon dioxide.
  • the sol composition will expand on freezing and so it will be appreciated that the tool design should accommodate this expansion. For example, this can be readily achieved by leaving at least a portion of the surface area of the freezing sol composition unenclosed by the tool.
  • the product is thawed after removal from the tool and the water-content may then be driven off, e.g. by drying in a conventional oven or by microwave heating.
  • the thawing and drying stages may be combined, if desired.
  • firing at elevated temperature sufficient to consolidate the product e.g. from 900°C to 1200°C, is carried out although it will be appreciated that, depending on the formulation used, temperatures well outside this range may prove suitable.
  • the metal tool formed by flame spraying may conveniently have a thickness of from, e.g. 0.5 to 4 mm, although for certain applications greater thicknesses may be found necessary.
  • a thickness of from, e.g. 0.5 to 4 mm although for certain applications greater thicknesses may be found necessary.
  • the thickness and the type of metal used will affect the heat transfer from the ceramic sol composition through the metal tool to the cooling liquid but the average skilled man of the art will readily be able to determine the optimum requirements for his particular circumstances and formulations.
  • a release coating may be applied to the metal tool or an ice-phobic coating, e.g. of a perfluoroalkoxy compound, may be applied.
  • a Plaster of Paris mould 10 of the desired final shape is used as the master on which to form the metal tool 12.
  • the mould 10 can be mounted in a suitable wooden pattern box (not shown) and its surface is varnished to seal its porosity prior to metal spraying.
  • a water-soluble release agent e.g. polyvinyl alcohol, is applied to the varnish-coated mould.
  • the surface of the mould is then dried and a tin/zinc alloy is sprayed over the mould surface to a uniform depth of from 1 to 3 mm to form a metal tool 12.
  • the metal tool or blank 12 is soaked in water to release it from the Plaster of Paris replica 10 and its inside, i.e. moulding, surface is cleaned and then treated with a release agent. Tool 12 is then filled to the desired depth with a slurry 17 of the desired ceramic sol composition and the filled metal tool 12 is lowered into a bath of cooled heat transfer fluid 18.
  • any expansion of the sol composition during the process is automatically catered for as only the exterior surfaces of the eventual mould product are confined by the metal tool.
  • Figure 4 illustrates another embodiment of the invention in which a porous ceramic mould is made in a two-part metal tool using a pumped refrigerated liquid to freeze-gel the sol composition.
  • the metal tool is made in two parts 20 and 22.
  • First part 20 which defines the desired product shape, i.e. the 'pattern' part, is made by flame spraying of metal on to a suitable former e.g. Plaster of Paris, (not shown).
  • Second part 22 is shaped such that the part defined by it will fit on to a roller mould machine.
  • part 22 may be a standard part that can be used with a variety of first or pattern parts. It can, therefore, conveniently be made by, for example, turning a metal ring in a lathe. It may also be formed hollow for the purpose described below.
  • Tool parts 20 and 22 together define the required shape of tool cavity 23.
  • Part 20 is sealingly attached to a backing tool 24 to define a chamber 28.
  • the hollow portion of part 22 provides a chamber 30.
  • 28 and 30 are chambers through which refrigerated liquid can be pumped.
  • Inlets 32 and 34 respectively and outlets 36 and 38 respectively are provided in chambers 28 and 30 for this purpose.
  • the mould cavity 23 is filled to the desired depth with a ceramic freeze-gellable sol composition and as the desired mould 40 starts to form, excess slurry is removed. Mould 40 is then stripped from the two-piece metal tool. It is then thawed, dried and fired.
  • any expansion of the sol composition during the process is automatically catered for by the open nature of the tooling.
  • the metal tool consists of a flame-sprayed metal shell 41 having the outline of the internal configuration of the desired cup mould 42.
  • the external outline of cup 42 is formed by hollow aluminium back former 44 whose face 46 defines the exterior surface of the desired cup mould 42.
  • a central hole 48 in the upper surface 50 of former 44 allows charging of the desired sol composition into the cup mould cavity defined between former 44 and metal tool 41 and also caters for any expansion of the sol composition on freezing.
  • Metal tool 41 is sealingly attached to a backing tool 52, which has inlet and outlet ports 54 and 56 respectively through which refrigerated liquid can be pumped.
  • former 44 has an inlet port 58 and outlet port 60 for the same purpose. It is also provided with a drain outlet 62.
  • cup mould 42 After freezing the sol composition the cup mould 42 is stripped from the tooling, thawed, dried and fired.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Dispersion Chemistry (AREA)
  • Compositions Of Oxide Ceramics (AREA)
EP92308671A 1991-10-04 1992-09-23 Moules Ceased EP0535854A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB919121089A GB9121089D0 (en) 1991-10-04 1991-10-04 Moulds
GB9121089 1991-10-04

Publications (1)

Publication Number Publication Date
EP0535854A1 true EP0535854A1 (fr) 1993-04-07

Family

ID=10702401

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92308671A Ceased EP0535854A1 (fr) 1991-10-04 1992-09-23 Moules

Country Status (2)

Country Link
EP (1) EP0535854A1 (fr)
GB (1) GB9121089D0 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996003355A1 (fr) * 1994-07-22 1996-02-08 Forschungszentrum Karlsruhe Gmbh Procede de production de microstructures ceramiques
EP1671766A3 (fr) * 2004-12-17 2008-01-23 BEGO Bremer Goldschlägerei Wilh. Herbst GmbH & Co. KG Procédé de fabrication d'un creuset en céramique
GB2468953A (en) * 2009-03-20 2010-09-29 Horizon Composites Ltd Freeze-cast ceramic components
US20100294912A1 (en) * 2006-11-18 2010-11-25 Bentley Motors Limited Ceramic tool having a material applied to the surface
CN111107968A (zh) * 2017-09-26 2020-05-05 德尔塔阀门公司 用于陶瓷产品的水凝胶注模成型方法
CN113715139A (zh) * 2021-09-01 2021-11-30 中建八局发展建设有限公司 一种用于混凝土预制块的硅胶模具及制作方法及制作工艺

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB616172A (en) * 1946-05-03 1949-01-18 Ernest James Johnson Improvements in and relating to potters' moulds
GB1175838A (en) * 1966-04-29 1969-12-23 Norton Abrasives Ltd Improvements in Moulds for Casting
US3816572A (en) * 1971-08-26 1974-06-11 Nalco Chemical Co Ceramic articles
US4231982A (en) * 1975-05-20 1980-11-04 Ab Volvo Method for the production of tools for deep drawing, moulding, extruding and the like
WO1983002251A1 (fr) * 1981-12-23 1983-07-07 Drabert Soehne Dispositif pour le moulage d'objets en ceramique, son procede de realisation et d'utilisation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB616172A (en) * 1946-05-03 1949-01-18 Ernest James Johnson Improvements in and relating to potters' moulds
GB1175838A (en) * 1966-04-29 1969-12-23 Norton Abrasives Ltd Improvements in Moulds for Casting
US3816572A (en) * 1971-08-26 1974-06-11 Nalco Chemical Co Ceramic articles
US4231982A (en) * 1975-05-20 1980-11-04 Ab Volvo Method for the production of tools for deep drawing, moulding, extruding and the like
WO1983002251A1 (fr) * 1981-12-23 1983-07-07 Drabert Soehne Dispositif pour le moulage d'objets en ceramique, son procede de realisation et d'utilisation

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996003355A1 (fr) * 1994-07-22 1996-02-08 Forschungszentrum Karlsruhe Gmbh Procede de production de microstructures ceramiques
EP1671766A3 (fr) * 2004-12-17 2008-01-23 BEGO Bremer Goldschlägerei Wilh. Herbst GmbH & Co. KG Procédé de fabrication d'un creuset en céramique
US20100294912A1 (en) * 2006-11-18 2010-11-25 Bentley Motors Limited Ceramic tool having a material applied to the surface
GB2468953A (en) * 2009-03-20 2010-09-29 Horizon Composites Ltd Freeze-cast ceramic components
GB2468953B (en) * 2009-03-20 2014-08-06 Horizon Composites Ltd Freeze-cast components
CN111107968A (zh) * 2017-09-26 2020-05-05 德尔塔阀门公司 用于陶瓷产品的水凝胶注模成型方法
US20200391407A1 (en) * 2017-09-26 2020-12-17 Delta Faucet Company Aqueous gelcasting method for ceramic products
EP3687751A4 (fr) * 2017-09-26 2021-08-04 Delta Faucet Company Procédé de coulage en gel aqueux pour produits céramiques
US11851376B2 (en) * 2017-09-26 2023-12-26 Delta Faucet Company Aqueous gelcasting method for ceramic products
CN113715139A (zh) * 2021-09-01 2021-11-30 中建八局发展建设有限公司 一种用于混凝土预制块的硅胶模具及制作方法及制作工艺

Also Published As

Publication number Publication date
GB9121089D0 (en) 1991-11-13

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