EP1363862A1 - Method and composition for making ceramic articles - Google Patents

Method and composition for making ceramic articles

Info

Publication number
EP1363862A1
EP1363862A1 EP02711118A EP02711118A EP1363862A1 EP 1363862 A1 EP1363862 A1 EP 1363862A1 EP 02711118 A EP02711118 A EP 02711118A EP 02711118 A EP02711118 A EP 02711118A EP 1363862 A1 EP1363862 A1 EP 1363862A1
Authority
EP
European Patent Office
Prior art keywords
composition
plasticiser
ceramic
parts
flaws
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Withdrawn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
EP02711118A
Other languages
German (de)
French (fr)
Inventor
John Michael Gallimore
Edward c/o Dyson Ceramic Systems SHAW
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.)
Dyson Industries Ltd
Original Assignee
Dyson Industries 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 Dyson Industries Ltd filed Critical Dyson Industries Ltd
Publication of EP1363862A1 publication Critical patent/EP1363862A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/16—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay
    • C04B35/18—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay rich in aluminium oxide
    • C04B35/195—Alkaline earth aluminosilicates, e.g. cordierite or anorthite
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
    • C04B35/632—Organic additives

Definitions

  • the invention relates to a ceramic composition and a method for producing ceramic articles using the composition.
  • a shape is moulded from a ceramic composition and the shape is dried and fired to form the article.
  • Flaws are usually present in ceramic articles after firing of the ceramic composition. These flaws may be holes or cracks formed during removal of the organic ingredients in the composition, or by the presence of aggregations of ceramic particles in the finished shape.
  • flaws having a diameter greater than 500 microns are known. These large flaws are a major cause of weakness in conventionally produced ceramic articles.
  • Viscous polymer processing is a process for mixing ceramic compositions using very high shears to input high energy into the mixture.
  • Articles produced using NPP process have smaller and fewer flaws and are stronger than articles produced by conventional ceramic production methods. This process enables thinner and lighter weight articles to be produced.
  • a method of producing a shaped ceramic article from a composition comprising a ceramic material, an organic binder and a plasticiser, the method comprising the steps of:
  • proportion of the plasticiser is selected to reduce the size and frequency of flaws in the finished ceramic article.
  • the content of the plasticiser should be controlled within a relative narrow range. We prefer to have from about 1.5 parts by weight relative to 100 parts by weight of the dry ingredients to about 2.5, say 1.8 parts.
  • compositions for use in the method described above comprising a ceramic material, an organic polymer binder, and a plasticiser, wherein the proportions of the plasticiser are selected to reduce the size and frequency of flaws in the finished ceramic article.
  • Suitable plasticisers include glycerol, glycerine, polyethyleneglycol and ethyleneglycol.
  • the plasticiser is glycerol. It is convenient to add the glycerol as an aqueous
  • the composition may be mixed using any known method of high shear mixing under a vacuum, for example, using a high shear mixer or by extrusion of the composition through a small diameter die.
  • the composition is mixed under high shear using suitable blades.
  • the mixed composition is preferably shaped by extruding the composition to the required shape, or by roll-milling the composition to form a sheet which is then formed into the required article.
  • the ceramic material may be any solid inorganic material.
  • the ingredients of a composition may be selected to form a cordierite.
  • the proportion of ceramic material present in the composition is at least 50% by weight.
  • the proportion of ceramic particles present in the composition should be about 60 to about 70%.
  • the binder is preferably an organic binder preferably a polymer such as polyvinyl alcohol and the like.
  • the formed ceramic article will typically have a mean flaw size of less than 20 microns.
  • the mean maximum flaw size of the fired ceramic article is measured by polishing the surface of the article and using an electron microscope to measure the diameter of twenty flaws at the widest point of the defect, and taking the average of these measurements.
  • a dry mixture was prepared by mixing 55 parts of grog, 25 parts of ball clay and 20 parts of powdered magnesium carbonate. 100 parts of ceramic powders prepared as above were mixed with 5 parts of polyvinyl alcohol. 18 parts of a 10% aqueous solution of glycerol was added to the dry mix and the whole was mixed at high shear using a z- blade high shear mixer while the apparatus is comiected to a vacuum pump to evacuate the system. The resultant mixture having a paste like consistency, was then passed tlirough a twin roll mill to form a sheet. The sheet was then dried to remove water from the composition and then transferred to a kiln and fired. During the firing process the organics, i.e. PNA and glycerol, are burnt off and the particles of ceramic are sintered to form a cordierite article.
  • the selection of the content of the glycerol and the high shear mixing of the composition resulted in the following beneficial results:
  • composition was very easy to work, for example, it mixed well, was relatively plastic and did not tear during roll milling;

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Compositions Of Oxide Ceramics (AREA)

Abstract

The proportion of plasticiser in a composition comprising a ceramic material and an organic binder and the plasticiser is selected to reduce the size of frequencies of the flaws in the ceramic article when it is later fired.

Description

METHOD AND COMPOSITION FOR MAKING CERAMIC ARTICLES
The invention relates to a ceramic composition and a method for producing ceramic articles using the composition.
In use, a shape is moulded from a ceramic composition and the shape is dried and fired to form the article. Flaws are usually present in ceramic articles after firing of the ceramic composition. These flaws may be holes or cracks formed during removal of the organic ingredients in the composition, or by the presence of aggregations of ceramic particles in the finished shape. In conventional ceramic production processes flaws having a diameter greater than 500 microns are known. These large flaws are a major cause of weakness in conventionally produced ceramic articles.
Viscous polymer processing (NPP) is a process for mixing ceramic compositions using very high shears to input high energy into the mixture. Articles produced using NPP process have smaller and fewer flaws and are stronger than articles produced by conventional ceramic production methods. This process enables thinner and lighter weight articles to be produced.
It has now been found that by mixing the ceramic composition under high shear and vacuum, and by adjusting the proportions of a selected ingredient in the composition, stronger and thinner articles can be produced having smaller flaws. According to the invention in one aspect there is provided a method of producing a shaped ceramic article from a composition comprising a ceramic material, an organic binder and a plasticiser, the method comprising the steps of:
mixing the composition under high shear and under a vacuum; shaping the composition; drying the composition, and firing the composition,
wherein the proportion of the plasticiser is selected to reduce the size and frequency of flaws in the finished ceramic article.
The content of the plasticiser should be controlled within a relative narrow range. We prefer to have from about 1.5 parts by weight relative to 100 parts by weight of the dry ingredients to about 2.5, say 1.8 parts.
According to the invention in a second aspect there is provided a composition for use in the method described above, the composition comprising a ceramic material, an organic polymer binder, and a plasticiser, wherein the proportions of the plasticiser are selected to reduce the size and frequency of flaws in the finished ceramic article.
According to the invention in a third aspect there is provided a ceramic article made according to the method described above. Suitable plasticisers include glycerol, glycerine, polyethyleneglycol and ethyleneglycol. Preferably the plasticiser is glycerol. It is convenient to add the glycerol as an aqueous
solution.
By using high shear mixing of the composition under a vacuum, and by selecting the proportion of the glycerol in the composition we have found that we can produce articles in a normal drying and firing time, and significantly reduce the size and frequency of flaws in the article.
The composition may be mixed using any known method of high shear mixing under a vacuum, for example, using a high shear mixer or by extrusion of the composition through a small diameter die. Preferably the composition is mixed under high shear using suitable blades.
The mixed composition is preferably shaped by extruding the composition to the required shape, or by roll-milling the composition to form a sheet which is then formed into the required article.
The ceramic material may be any solid inorganic material. Preferably the ingredients of a composition may be selected to form a cordierite.
Preferably the proportion of ceramic material present in the composition is at least 50% by weight. Ideally the proportion of ceramic particles present in the composition should be about 60 to about 70%. The binder is preferably an organic binder preferably a polymer such as polyvinyl alcohol and the like.
The formed ceramic article will typically have a mean flaw size of less than 20 microns. The mean maximum flaw size of the fired ceramic article is measured by polishing the surface of the article and using an electron microscope to measure the diameter of twenty flaws at the widest point of the defect, and taking the average of these measurements.
In order that the invention may be well understood it will now be described by way of illustration only with reference to the following examples in which all proportions are stated in parts by weight.
Example 1
A dry mixture was prepared by mixing 55 parts of grog, 25 parts of ball clay and 20 parts of powdered magnesium carbonate. 100 parts of ceramic powders prepared as above were mixed with 5 parts of polyvinyl alcohol. 18 parts of a 10% aqueous solution of glycerol was added to the dry mix and the whole was mixed at high shear using a z- blade high shear mixer while the apparatus is comiected to a vacuum pump to evacuate the system. The resultant mixture having a paste like consistency, was then passed tlirough a twin roll mill to form a sheet. The sheet was then dried to remove water from the composition and then transferred to a kiln and fired. During the firing process the organics, i.e. PNA and glycerol, are burnt off and the particles of ceramic are sintered to form a cordierite article. The selection of the content of the glycerol and the high shear mixing of the composition resulted in the following beneficial results:
1. the composition was very easy to work, for example, it mixed well, was relatively plastic and did not tear during roll milling;
2. the mean maximum flaw diameter was reduced to less than 20 microns;
3. the tensile and flexural strength of the finished article were high.

Claims

1. A method of producing a shaped ceramic article from a composition comprising a ceramic material, an organic binder and a plasticiser, the method comprising the steps of :
• mixing the composition under high shear and vacuum;
• shaping the composition;
• drying the composition, and
• firing the composition,
wherein the proportion of plasticiser is selected to reduce the size and frequency of flaws in the ceramic article.
2. A method according to Claim 1 wherein the plasticiser is from 1.5 to 2.5 parts by weight where the dry material is 100 parts.
3. A method according to Claim 2 wherein the content of plasticiser is 1.8 parts by weight.
4. A method according to any preceding Claim wherein the plasticiser is one or more of glycerol, glycerine, polyethyleneglycol and ethyleneglycol.
5. A composition comprising a ceramic material, an organic binder and a plasticiser wherein the proportion of plasticiser is selected to reduce the size and frequency of flaws in the finished ceramic article.
6. A composition according to Claim 5 containing 1.5 to 2.5 parts by weight of plasticiser.
7. A composition according to Claim 6 containing 1.8 parts by weight of plasticiser.
8. A composition according to Claim 5 wherein the plasticiser is glycerol.
9. A composition according to any of Claims 5 to 8 wherein the binder is a polymer.
10. A composition according to Claim 9 wherein the binder is polyvinylalcohol.
EP02711118A 2001-02-19 2002-02-19 Method and composition for making ceramic articles Withdrawn EP1363862A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB0104028A GB2372250B (en) 2001-02-19 2001-02-19 Ceramic articles
GB0104028 2001-02-19
PCT/GB2002/000724 WO2002066399A1 (en) 2001-02-19 2002-02-19 Method and composition for making ceramic articles

Publications (1)

Publication Number Publication Date
EP1363862A1 true EP1363862A1 (en) 2003-11-26

Family

ID=9909023

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02711118A Withdrawn EP1363862A1 (en) 2001-02-19 2002-02-19 Method and composition for making ceramic articles

Country Status (3)

Country Link
EP (1) EP1363862A1 (en)
GB (1) GB2372250B (en)
WO (1) WO2002066399A1 (en)

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU682477A1 (en) * 1978-04-10 1979-08-30 Организация П/Я А-1695 Slip for making ceramic films
US5238627A (en) * 1988-06-01 1993-08-24 Ngk Insulators, Ltd. Method for producing ceramics sintered article and molding method and molding apparatus to be used therefor
DE68927185T2 (en) * 1988-06-01 1997-03-06 Ngk Insulators Ltd Molding process and device for manufacturing ceramic objects
US5279994A (en) * 1993-02-11 1994-01-18 W. R. Grace & Co.-Conn. Aqueous processing of green ceramic tapes
US5686506A (en) * 1995-04-04 1997-11-11 Borden Chemical, Inc. Mixtures of phenolic novolaks for use with refractory aggregate and methods for making same
JPH09208311A (en) * 1996-02-08 1997-08-12 Matsushita Electric Ind Co Ltd Production of piezoelectric ceramic
US5977230A (en) * 1998-01-13 1999-11-02 Planet Polymer Technologies, Inc. Powder and binder systems for use in metal and ceramic powder injection molding
RO115155B1 (en) * 1998-03-20 1999-11-30 Sc Subansamble Auto Sa Process for producing a monolithic ceramic base

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO02066399A1 *

Also Published As

Publication number Publication date
GB2372250A (en) 2002-08-21
GB0104028D0 (en) 2001-04-04
WO2002066399A1 (en) 2002-08-29
GB2372250B (en) 2003-08-13

Similar Documents

Publication Publication Date Title
EP1806175B1 (en) Method of Gel-casting a cemented carbide body
EP0038126B1 (en) Cementitious composition and cement product produced therefrom
JP2604592B2 (en) Molding method of metal, ceramic powder, etc. and composition therefor
EP0055035B1 (en) Cementitious composition and cementitious product of high flexural strength
JPH11165309A (en) Manufacture of ceramics using binder solidification
TWI430975B (en) Composition for ceramic extrusion-molded body and method for manufacturing a ceramic extrusion-molded body
EP1316538B1 (en) Method for producing a honeycomb structure
JP2843348B2 (en) Formation of complex high performance ceramic and metal shapes
EP0170396B1 (en) Method of manufacturing short inorganic fiber-reinforced metal composites
US4814302A (en) Stable slip-casting compositions having a base of powders containing finely divided aluminum nitride
JPH09118569A (en) Water-based mixture and production of body comprising the same
EP1363862A1 (en) Method and composition for making ceramic articles
JPH05194037A (en) Water extrusion of silicon nitride
JPH05339602A (en) Plastically deformable metallic mixture and its use
JPH04209747A (en) Ceramic material for single screw type extrusion forming
CN116020977B (en) Ceramic core with multi-layer wall structure and preparation method thereof
CN111377746B (en) Low-cost environment-friendly composite auxiliary agent for honeycomb ceramic molding and application method thereof
de Witte Printing material
CN106631099A (en) Preparation method of high-wet-blank-strength honeycomb ceramic
JP3283346B2 (en) Clay composition for extrusion molding
JP3317142B2 (en) Manufacturing method of ceramic sheet
JPH08133818A (en) Pressurized casting method of powder
GB2424610A (en) Forming method
CZ375298A3 (en) Hydrophobic / hydrophilic block copolymers as polymeric binding agents for producing ceramics
JPS6346026B2 (en)

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: 20030917

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR

AX Request for extension of the european patent

Extension state: AL LT LV MK RO SI

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

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20050901