WO1995034795A1 - Procede et appareil de cuisson de feuilles de ceramique - Google Patents

Procede et appareil de cuisson de feuilles de ceramique Download PDF

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Publication number
WO1995034795A1
WO1995034795A1 PCT/GB1995/001377 GB9501377W WO9534795A1 WO 1995034795 A1 WO1995034795 A1 WO 1995034795A1 GB 9501377 W GB9501377 W GB 9501377W WO 9534795 A1 WO9534795 A1 WO 9534795A1
Authority
WO
WIPO (PCT)
Prior art keywords
sheets
holder
accordance
setting
ceramic
Prior art date
Application number
PCT/GB1995/001377
Other languages
English (en)
Inventor
Fiona Catherine Ruth Wroe
William Jones
Original Assignee
Ea Technology Limited
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 Ea Technology Limited filed Critical Ea Technology Limited
Publication of WO1995034795A1 publication Critical patent/WO1995034795A1/fr

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B28WORKING CEMENT, CLAY, OR STONE
    • B28BSHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B11/00Apparatus or processes for treating or working the shaped or preshaped articles
    • B28B11/24Apparatus or processes for treating or working the shaped or preshaped articles for curing, setting or hardening
    • B28B11/243Setting, e.g. drying, dehydrating or firing ceramic articles
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10Sintering only
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27FURNACES; KILNS; OVENS; RETORTS
    • F27DDETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D5/00Supports, screens, or the like for the charge within the furnace

Definitions

  • the present invention relates to an apparatus and method for use in the firing of one or more ceramic sheets from a green state to a sintered state.
  • Ceramic sheets which contain a ploymer as a binder in the green (unfired) state and which comprise, for example, a polymer/stabilized Zirconia powder mixture or a polymer/Lanthanum Chromate powder mixture find many uses in modern industry once they have been sintered and the binder removed.
  • thin polymer based ceramic sheets of this type may be used in the manufacture of solid oxide fuel cells during which they might typically undergo a silk screen printing process before then being co-fired to form a single cell having an interconnect. To this end it is desirable for the ceramic sheets to exhibit a high degree of flatness, excellent surface contact and a good mechanical strength.
  • the sheet 10 is placed in its green state on a bottom setter 12 and both the bottom setter and the ceramic sheet are then placed within a furnace 14.
  • the furnace 14 may include one or more radiant heating elements 16 or else may be coupled to a microwave source.
  • the furnace 14 may comprise both radiant heating elements 16 and a microwave source 18.
  • a refractory holder for use in retaining one or more ceramic sheets during the firing of the sheets from a green state to a sintered state, the holder comprising a first member having a first setting surface; a second member having a second setting surface, the second setting surface being opposed and spaced parallel to the first setting surface so as to define therebetween a volume for the receipt of said one or more ceramic sheets; spacing means to retain the first and second setting surfaces in said spaced relationship; and holding means to hold the first and second members against any forces applied by the or each of the sheets during firing.
  • the spacing means may be formed integrally with one or both of said first and second members.
  • one or both of the first and second setting surfaces may be recessed within their respective members so as to thereby define an upstanding peripheral wall portion, the or each peripheral wall portion serving to define said spacing means.
  • the volume defined between said first and second setting surfaces for the receipt of said one or more ceramic sheets may be fully enclosed.
  • the volume defined between said first and second setting surfaces for the receipt of said one or more ceramic sheets mav be oversized with respect to the or each of the sheets to be fired in the plane of that sheet .
  • the distance between the first and second setting surfaces may be substantially equal to the thickness of the sheet or, where more then one sheet is retained within the holder, the combined thickness of all of the sheets and their associated separators, when the or each of the sheets is in its green state.
  • first and second members may comprise a first portion having a first surface flatness and a second portion having a second surface flatness, said second portion having a greater surface flatness than said first portion and defining the setting surface of said respective first or second member.
  • the second portion may be formed of high density alumina.
  • the holder may be adapted for use in a furnace capable of generating a radiant heat flux and the first and second setting surfaces may be arranged so as to support the or each of the sheets substantially perpendicularly to said flux.
  • the first and second setting surfaces may be disposed substantially horizontally and said holding means may comprise a weight applied to the upper of the two members.
  • said holding means may comprise a clamp.
  • the holder may be adapted to retain two or more ceramic sheets and to support the sheets at a predetermined angle to the vertical.
  • said predetermined angle may be selected such that a constant pressure is applied across the thickness of at least one of the sheets, said constant pressure including a component due to the weight of a sheet adjacent said at least one of the sheets and being such as to allow sufficient freedom of movement for said at least one of the sheets to shrink during firing without tearing.
  • the holder may comprise third and fourth setting surfaces arranged transversely of said first and second setting surfaces.
  • a method of firing one or more ceramic sheets from a green state to a sintered state comprising the steps of locating the or each of the sheets between two opposed, parallel spaced setting surfaces which are retained in said spaced relationship by spacing means, supplying heating energy to the or each of the sheets in order to fire said sheets, and holding said setting surfaces against any forces applied by the or each of the sheets during the firing process.
  • Figure 3 is a cross-sectional schematic view of a holder in accordance with a first embodiment of the present invention
  • Figure 4 is a cross-sectional schematic view of a holder in accordance with a second embodiment of the present invention.
  • Figure 5 is a cross-sectional schematic view of a holder in accordance with a third embodiment of the present invention.
  • Figure 6 is a cross-sectional schematic view of a holder in accordance with a fourth embodiment of the present invention,*
  • Figure 7 is a cross-sectional schematic view of a holder in accordance with a fifth embodiment of the present invention.
  • Figure 8 is a cross-sectional schematic view of a holder in accordance with a sixth embodiment of the present invention.
  • Figure 9 is a cross-sectional schematic view of a holder in accordance with a seventh embodiment of the present invention.
  • a refractory holder 20 comprising a bottom setter 12 and a top setter 22.
  • the bottom setter 12 is provided in an upper surface 24 with a recessed portion 26.
  • the recessed portion 26 is located centrally of the bottom setter 12 and so defines both a first setting surface 28 and an upstanding peripheral wall 30.
  • the top setter 22 is supported by the peripheral wall 30 such that a lower surface of the top setter 32 defines with the recessed portion 26 an enclosed volume 34 for the receipt of a ceramic sheet 10.
  • the height of the peripheral wall 30 is such that the distance between the first setting surface 28 and the second setting surface defined by the lower surface 32 of the top setter 22 is substantially equal to the thickness of the ceramic sheet 10 when the sheet is in its green state.
  • the holder 20 can exert a slight pressure across the thickness of the sheet 10 at the start of the firing process although clearly, as the firing process continues and the sheet shrinks this pressure will be reduced until such time as the thickness of the sheet is less than the height of the peripheral wall 30 whereupon the pressure will have been reduced to zero.
  • What this initial pressure does enable however, is for the ceramic sheet 10 to take up the flatness of the first and second setting surfaces 28 and 32. For this reason these two surfaces are preferably machined to a flatness of 40 microns or less.
  • the limited distance between the first and second setting surfaces 28 and 32 also serves to restrain the ceramic sheet 10 from buckling, curling or corrugating out of the plane of the sheet .
  • a holding weight 36 may be provided on an upper surface 38 of the top setter 22.
  • the recessed portion 26 is preferably oversized with respect to the ceramic sheet in the plane of the sheet. In this way the holder 20 provides the ceramic sheet 10 with sufficient freedom of movement to contract during the firing process in the plane of the sheet without giving rise to additional stresses along which the sheet may subsequently rear.
  • the holder 20 may find use in a variety of furnaces .
  • the holder 20 is placed within a furnace 14 which includes both a plurality of radiant heating elements 16 and a microwave source 18.
  • the furnace 14 may equally be provided with only one of these heating means or else be provided with convective heating means.
  • the furnace 14 is adapted so as to raise the temperature of the ceramic sheet 10 to a minimum sintering temperature consistent with achieving the required density and grain size.
  • the two setters 12 and 22 are preferably formed of a material which is transparent to microwave energy.
  • the two setters 12 and 22 may be formed of a material which is susceptible to microwaves and which is capable of then radiating heat to the ceramic sheet 10. What is important however, is to avoid the generation of hot spots within either the ceramic sheet 10 or the two setters 12 and 22 which might lead to the start of a thermal runaway effect and the eventual destruction of the sheet.
  • the two setters 12 and 22 are preferably formed of a material which is capable of absorbing heat energy and transferring that heat energy to the ceramic sheet 10 in such a way as to produce an even temperature distribution across the sheet.
  • the sheet is protected during the firing process against localised regions of focused radiant heat energy that might otherwise lead to the generation of thermal stresses within the ceramic material.
  • Another advantage of providing a holder which defines a totally enclosed volume for the receipt of the ceramic sheet 10 is that where the furnace employs gas radiant or convection heating, the sheet is protected from the products of combustion.
  • the material must be capable cf withstanding the range of temperatures that are likely to be experienced within the furnace 14, whilst at the same time being capable of being machined to a high degree of flatness.
  • the setters 12 and 22 should also be formed of materials which minimise contamination and other adverse reactions between the setters and the ceramic sheet 10.
  • Two of the currently preferred materials for forming the two setters 12 and 22 and which satisfy the above criteria are Alumina thermal insulation board and Zircar thermal insulation board of varying densities.
  • FIG 4 there is shown a holder in accordance with a second embodiment of the present invention.
  • This embodiment includes many features which are common to that described with reference to Figure 3 and which have therefore been denoted by the same reference numerals and which will not now be further described.
  • the advantage of disposing the two setters 12 and 22 vertically rather than horizontally arises from the fact that in the illustrated furnace 14 the radiant heating elements 16 are also disposed vertically.
  • the holder 20 By so arranging the holder 20 such that the ceramic sheet 10 is disposed generally perpendicularly to the radiant heat flux, it is possible to provide the sheet with a more uniform temperature distribution since there is no one part of the sheet which is closer to a radiant heating element than any other part of the sheet . This in turn leads to a reduction in the thermal stresses generated within the sheet and to a diminishing of the tendency of the sheet to curl around its edges.
  • FIGS 5 and 6 there are shown two further holders each in accordance with a further embodiment of the present invention.
  • the two holders share many features in common with those described in relation to Figures 3 and 4 and which are therefore denoted by the same reference numerals.
  • the main difference between the two lies in the greater depth of the recessed portion 26 in the embodiment of Figure 5 and the consequently increased height of the upstanding peripheral wall 30. This increased height allows for the provision of a first ceramic plate 42 within the recessed portion 26.
  • the first setting surface 28 may be defined by an upper surface of the first ceramic plate 42 which, being separately formed from the rest of the bottom setter 12 may be machined to a higher degree of flatness.
  • the first ceramic plate 42 may be formed of high density alumina and have a flatness of the order of 5 microns.
  • a second ceramic plate 44 may be interposed between the upper surface of the bottom setter 24 and the lower surface of the top setter 32.
  • the second setting surface instead of being defined by the lower surface 32 of the top setter 22, is defined by a lower surface 46 of the second ceramic plate 44.
  • the embodiment shown in Figure 6 is similar to that described in relation to Figure 5 except that, as with the embodiment of Figure 4 , the two setters 12 and 14 are disposed generally vertically. In this way the embodiment of Figure 6 may enjoy not only the increased surface flatness of the embodiment of Figure 5, but also the improved temperature distribution of the embodiment of Figure 4.
  • FIG 7 there is shown a holder in accordance with yet a further embodiment of the present invention.
  • the holder has many features in common with those that have been previously described and which are therefore denoted by common reference numerals.
  • the embodiment of Figure 7 is similar to that illustrated in Figure 3, except that the embodiment in Figure 7 has been adapted so as to accommodate a plurality of ceramic sheets 10 which may be co-fired simultaneously. To this end the recessed portion 26 within the bottom setter 12 is made deeper thereby raising the height of the upstanding peripheral wall 30.
  • the embodiment of Figure 7 is again provided with a first setting surface 28 defined by an upper surface of a first ceramic plate 42 received within the recessed portion 26 and a second setting surface 46 defined by a lower surface of a second ceramic plate 44 interposed between the upper surface 24 of the bottom setter 12 and the lower surface 32 of the top setter 22.
  • the depth of the recessed portion 26 is such as to accommodate a stack of ceramic sheets 10 each of which is spaced from its neighbour by a separator 48 in the form of a plate of for example high density alumina or a layer of ceramic paper.
  • the embodiment of Figure 7 has the advantage that it enables a plurality of ceramic sheets 10 to be co-fired simultaneously, it suffers from the disadvantage that the initial pressure applied across the thickness of the ceramic sheets is not the same for each of the sheets within the stack. This arises because the applied pressure is due not only to the combined weight of the top setter 22 and the holding weight 36, but also to the weight of each of the ceramic sheets 10 and separators 48 disposed above the ceramic sheet in question. Thus, the pressure applied across the thickness of the bottom sheet within the stack is very much greater than that applied across the thickness of the top sheet. Accordingly, the lower sheets within the stack are more restricted in their freedom of movement and so when fired tend to suffer from additional stresses along which they can subsequently tear.
  • Figure 9 Another, and perhaps more elegant solution, is shown in Figure 9 in which the holder 20 is again adapted to contain a plurality of ceramic sheets 10 each of which is spaced from its neighbours by a separator 48.
  • the holder of Figure 9 is provided with a pair of side setters 50 and 52 in addition to the top and bottom setters 22 and 12.
  • the two side setters 50 and 52 are each provided with a respective setting surface 54 and 56 which, like the first and second setting surfaces previously described, are mutually opposed and extend substantially parallel to each other.
  • the setting surfaces 54 and 56 are both inclined to the vertical.
  • the ceramic sheets 10 contained within the holder 20 are also inclined to the vertical.
  • the pressure applied across the thickness of each of the sheets 10 includes a component which arises from the weight of its neighbours. Unlike the pressure applied by the ceramic clamp 40 in the embodiment of Figure 8, this component of pressure is present throughout the firing process. At the same time, it will be apparent that the size of the component is dependent upon the angle at which the setting surfaces 54 and 56 are inclined to the vertical. Thus by careful selection of this angle a sufficient pressure may be applied to the ceramic sheets 10 throughout the firing process to prevent the sheets from curling around their edges whilst at the same time providing sufficient freedom of movement to allow the sheets to shrink without generating the additional stresses along which the sheets might subsequently tear.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Ceramic Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Furnace Charging Or Discharging (AREA)

Abstract

Un support réfractaire (20) sert à retenir une ou plusieurs feuilles de céramique (10) pendant leur transformation par cuisson de l'état vert à l'état fritté. Le support comprend un premier organe avec une première surface d'enfournement (12) et un deuxième organe avec une deuxième surface d'enfournement (22). La deuxième surface d'enfournement est opposée et parallèle à la première surface d'enfournement, les deux surfaces d'enfournement étant mutuellement espacées de manière à définir un volume intermédiaire de réception d'une ou plusieurs feuilles de céramique. Des éléments d'écartement maintiennent les première et deuxième surfaces d'enfournement écartées et des éléments de retenue (36) retiennent les premier et deuxième organes contre toute force appliquée par les feuilles ou par chaque feuille pendant la cuisson. L'invention concerne également un procédé de cuisson d'une ou plusieurs feuilles de céramique (10).
PCT/GB1995/001377 1994-06-14 1995-06-14 Procede et appareil de cuisson de feuilles de ceramique WO1995034795A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9411905A GB2290604A (en) 1994-06-14 1994-06-14 Apparatus and method for firing ceramic sheets
GB9411905.4 1994-06-14

Publications (1)

Publication Number Publication Date
WO1995034795A1 true WO1995034795A1 (fr) 1995-12-21

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ID=10756707

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1995/001377 WO1995034795A1 (fr) 1994-06-14 1995-06-14 Procede et appareil de cuisson de feuilles de ceramique

Country Status (2)

Country Link
GB (1) GB2290604A (fr)
WO (1) WO1995034795A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998013317A2 (fr) * 1996-09-24 1998-04-02 Baker Hughes Incorporated Procede et dispositif pour infiltrer des composants preformes et des ensembles de composants
GB2326705A (en) * 1997-06-25 1998-12-30 Michael Sean Barron Glass sheet firing
US6073518A (en) * 1996-09-24 2000-06-13 Baker Hughes Incorporated Bit manufacturing method

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1206704B (de) * 1964-06-03 1965-12-09 Deutsche Edelstahlwerke Ag Sinterform zur Herstellung von Platten
US3761234A (en) * 1968-01-02 1973-09-25 American Optical Corp Method of making fiber optical multifibers and devices formed thereof
FR2243161A1 (fr) * 1973-09-10 1975-04-04 Hoya Glass Works Ltd
GB2093009A (en) * 1981-02-16 1982-08-25 Didier Werke Ag Moulded articles
US4586896A (en) * 1985-01-18 1986-05-06 Smith Robert S Flatbaking method and apparatus
EP0599371A1 (fr) * 1992-11-18 1994-06-01 Philips Composants Et Semiconducteurs Procédé et matériel de frittage de secteurs de ferrite
EP0633440A1 (fr) * 1993-07-02 1995-01-11 Abb Research Ltd. Procédé pour la préparation d'un support de frittage

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3213549A (en) * 1963-02-20 1965-10-26 Philip E Caron Steaming apparatus
GB1526178A (en) * 1977-04-06 1978-09-27 Lambert Ceramiques Sa Methods and devices for firing tiles
US4523907A (en) * 1981-03-11 1985-06-18 Haessler Andreas Holder and method of firing ceramic briquettes
GB8900769D0 (en) * 1989-01-13 1989-03-08 Spacesaver Signs Making flat plates

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1206704B (de) * 1964-06-03 1965-12-09 Deutsche Edelstahlwerke Ag Sinterform zur Herstellung von Platten
US3761234A (en) * 1968-01-02 1973-09-25 American Optical Corp Method of making fiber optical multifibers and devices formed thereof
FR2243161A1 (fr) * 1973-09-10 1975-04-04 Hoya Glass Works Ltd
GB2093009A (en) * 1981-02-16 1982-08-25 Didier Werke Ag Moulded articles
US4586896A (en) * 1985-01-18 1986-05-06 Smith Robert S Flatbaking method and apparatus
EP0599371A1 (fr) * 1992-11-18 1994-06-01 Philips Composants Et Semiconducteurs Procédé et matériel de frittage de secteurs de ferrite
EP0633440A1 (fr) * 1993-07-02 1995-01-11 Abb Research Ltd. Procédé pour la préparation d'un support de frittage

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6354362B1 (en) 1994-03-16 2002-03-12 Baker Hughes Incorporated Method and apparatus for infiltrating preformed components and component assemblies
US6581671B2 (en) 1994-03-16 2003-06-24 Baker Hughes Incorporated System for infiltrating preformed components and component assemblies
WO1998013317A2 (fr) * 1996-09-24 1998-04-02 Baker Hughes Incorporated Procede et dispositif pour infiltrer des composants preformes et des ensembles de composants
WO1998013317A3 (fr) * 1996-09-24 1998-09-17 Baker Hughes Inc Procede et dispositif pour infiltrer des composants preformes et des ensembles de composants
US6073518A (en) * 1996-09-24 2000-06-13 Baker Hughes Incorporated Bit manufacturing method
US6089123A (en) * 1996-09-24 2000-07-18 Baker Hughes Incorporated Structure for use in drilling a subterranean formation
GB2326705A (en) * 1997-06-25 1998-12-30 Michael Sean Barron Glass sheet firing
GB2326705B (en) * 1997-06-25 2001-02-14 Michael Sean Barron Improvements relating to glass sheet firing

Also Published As

Publication number Publication date
GB2290604A (en) 1996-01-03
GB9411905D0 (en) 1994-08-03

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