HUE034559T2

HUE034559T2 - Ceramic plate for kiln car bodies and fireproof linings

Info

Publication number: HUE034559T2
Application number: HUE11785419A
Authority: HU
Inventors: Erhard Winkler
Original assignee: Saint Gobain Ind Roedental Gmbh
Priority date: 2010-12-09
Filing date: 2011-11-21
Publication date: 2018-02-28
Also published as: DE102010061134A1; EP2649395A1; EP2649395B1; WO2012076319A1

Description

Ceramic Plate for Kiln Car Bodies sad Fireproof Linings

The invention relates So a ceramic plate tor kiln car bodies and Sire proof linings according to the generic portion of claim i and a method for its production according to the generic portion of claim 12. in order to be able to produce fired ware, in particular ceramic products, they must be tired in a kiln. For introduction into and removal from the kiln, tbc ceramic products are supported on an apparatus that can serve for transport of the products. For this, appropriate kiln cars are known which include kiln car bodies made of supporting arrangements. The corresponding mountings or support systems for the fire«! ware are formed from a plurality of supports and support -carriers, such as stringers, transverse beams, and/or plates and are generally referred to as kiln furniture. Usingkiin ears, the fired ware is then introduced into the kiln and removed from the ktln after firing. T he process cycles-can also be automated with such, kiln cars.

Ceramic piates for kiln cars are known, for example, from BP-A 0 002 193., JP-A 03 233 887, or BP»A 2 251 628. 1rs the kiin, the kiin furniture is exposed to high firing temperatures and must withstand them. Consequently, the kiln furniture is made of a ceramic· material, e.g., based on AWT,, muliite, RSi€, SiStC, or NSiC, The selection of the respective material depends on the respective operating conditions. The ceramic materials are, as a ride, filled into plaster models in a viscous state and dty therein. Tire drying of the ceramic materials is associated with a shrinking process thereof.

The kiln tuniiture must sometimes bear heavy loads, which necessitates high stability of the kiln furniture. Moreover, already in its production process, for example, during a sintering process following the drying process, the kiln furniture should be relatively unbreakable and bend resistant.

During use of the kiin furniture as intended, targe temperature gradients can occur within the kiln furniture. Hence, the kiln furniture expands differently in different regions, which can resuit in thermal stresses and, consequently, in cracks in dm corresponding kiin lurniture. 'these cracks negatively affect the stability and bearing capacity of this kiin furniture. This is especially true for areally extensive, plate-shaped kdn furniture. Consequently, the object of the present invention, is to provide a ceramic plate tor kiin car bodies and fireproof linings that at least partially avoids the disadvantages of the aforementioned prior art. In particular, a ceramic plate should be made available which is very stable already during it* production process. The ceramic plate should be usable throughout the entire high and low temperature range of the kiln as a kitti car body and a fireproof lining, without the ceramic {date being damaged by the formation of cracks, for example, in the production process or during use as intended. At the same time, a method for production of a centime plate that ensures these properties of the ceramic plate and is, at the same time, simple to perform should be made available,

The object is accomplished by a ceramic plate with the characteristics of claim I and a method with the characteristics of claim 12, with advantageous embodiments being the subject matter of the dependent claims. Consequently, the ceramic piete according to the invention comprises a ceramic plate with a beam-like hollow chamber reinforcement on a lower face of the ceramic plate. The beam-like hollow chamber re i it forcement extends parallel to a substantially smooth upper face of the ceramic plate. One side of the beam-like hollow chamber reinforcement is formed by Che ceramic plate. The beam-like hollow chamber reinforcement contributes, due to its beam torra, to particularly high stability of the ceramic plate. The beam-like hollow chamber reinforcement reinforces the ceramic plate due to its hollow space, without tire thickness of the ceramic material varying substantially. Moreover, Site air for drying the ceramic plate can circulate freely via the hoi tow space. This resuits in uniform drying of the material of the ceramic plate during the production process.

The ceramic plaie according to the invention is advantageously produced in a combined casting process that comprises a solid casting process and a hollow casting process.in the combined method, a piaster mold that includes the outer shape of the ceramic plate and the beam-like hollow chamber reinforcement is tilled with a ceramic slurry. The plaster mold draws moisture from the ceramic slurry such that it solidifies, the solidification process begins at the interlace with the plaster mold and coni tones farther within the ceramic slnfry, The ceramic slurry remains in the piaster mold: until the slurry has completely solidified in the; region of the ceramic plate. Then, the remaining liquid slurry is removed. Solidified slutiiy having a wall thickness that corresponds, for example, to from 55% to 90%of thd thlebieSS pf the ceramic plate remains in the regidtr oftbe feeam-like hollow chamber reinforcement, in the following process step, the pldsler mold is removed ásd the ceramic blank is tired.

The ceramic plate according to tin* invention has a large flat area on winch even large fired ware can be reliably supported. Prior art firing plate racks are usually constructed from a large number of small plates, wherein tire individual plates can have* due to different thermal expansion and material tolerances, a slight angular tilt and, hence, a certain unevenness in the rack surface. The unevenness Jp $t$ $$&. serfage: m*,. tu tmfltv'orable cases, resuit in damage to the fired ware during the firing operation.

Due to fite itsn bond between the ceramic plate and the beam-like hollow chamber reinforcement according to the invention, the ceramic plate is mote rigid and is deformed less under load than with prior art ceramic plates. Due to the ceramic: bond between the ceramic plate and five beam like hollow chamber reinforcement according to the invention, heal is dissipated belter, tesuhmg in. lower thermal stresses and improved thermal shock resistance.

The ceramu plate according to the invention preferably contains high temperature resistant ceramic materials, preferably silicon carbide and particularly preferably nitride-bonded silicon carbide (NSÍC) or synthetic sintered mullite.

Nitride-bonder! silicon carbide is nitrided from silicon carbide and silicon metal powder in a nitrogen atmosphere at: roughly 1400 :'€ and then oxidized if need be depending on the application. Workpieces made of nitride-bonded silicon carbide are poorly wettable by nonferrous metal melts. Workpieces made of nitride-bonded silicon carbide have high shape and surface resistance as well as high flexural strength. Workpieces made of nitride-bonded silicon carbide are, due to their high temperature resistance, ideally suitable as kiln furniture for temperatures to i 5ÖÖ °€.

Mullite contains aluminum oxide and silicon oxide. Synthetically sintered mullite has relatively high strength with comparatively low thermal expansion, resulting in excellent temperature shock resistance. It is suifabie as kiln furniture for temperatures to roughly 1700 CC.

The high stability of-the ceramic plate accord ing to the production process is supported in that the beam-dike hollow chamber reinforcement comprises multiple, hollow beams that intersect, which enclose at least a quadrillerai Tor example, a rhombus or a rectangle, in particular a square, and whose hollow spaces form a common hollow space. The hollow beams can also enclose at least a. triangle or a hexagon. In use, ceramic plates usually sustain damage at those places where the temperature gradients are the greatest. The temperature gradients can be kept small by ensuring the most even heat distribution {wssible within the ceramic plate. The common hollow space of the beam-like hollow chamber reinforcement of the ceramic plate according to the invention enables uniform hot air distribution* resulting in lower thermal stresses and in unproved lemperature shock resistance of the ceramic plate,

Since the occurrence of temperature gradients cannot regularly be avoided, slits or grooves are preferably introduced to Increase the elasticity of the ceramic plate, preferably by introduction of at least one recess in the ceramic plate of In the lower face of the ceramic plate. The recess is, for example, a sin or a groove. Which are [sic] preferably designed in a crisscross pattern. Such a slit extends all the way through the entire ceramic plate, whereas the groove is only introduced to a given depth into the surface of the ceramic plate. The groove can be introduced on the upper face and or the lower face, preferably on the lower lace of the ceramic plate. The recess prevents stresses within the ceramic plate from becoming so great that unwanted cracks develop. The recess and, optionally, other recesses are preferably introduced in the ceramic plate in the unbred state and have, for example, a width of 0.2 mm to 0.8 nan and/or a length of 5 cm to 15 cm. The length of the recess Is preferably from 20% to 80% of the Inside width of the area delimited by hollow beams. T he elasticity of the plate and, hence, also the thermal shock resistance can be influenced by providing, Ibf St least one or as many as ail quadrilaterals, a cross-shaped slit or a cross-shaped groove that at least partially overlaps the diagonals of the corresponding quadrilateral in a projection onto the corresponding quadrilateral, The cross-shaped slits arid grooves are preferably milled into the unbred ceramic blank.

The invention is explained in detail with reference to drawings and an example. The drawings are provided for illustration ami in no way restrict the content of the invention.

They depict: 1· ig. i a perspective view of a lower face of a ceramic plate, big. 2 a perspective view of an upper face of the ceramic plate, big. 3 the upper face of the ceramic plate, big. 4 a .section through she ceramic plate of big, 3, and Fig, § a. detail 7. of she ceramic plate of Fig. 3. F lernen Is of the same design or function are labeled with the same reference characters throughout the figures. Fig. I depicts a perspective view of a lower face 4 of a ceramic plate 2 for kiln car bodies and fireproof linings. Situated ott the lower face 4 of the ceramic plate 2 is a beam-like hollow chamber reinforcement 6. "t he bearn-iike hollow chamber reinforcement 6 comprises a plurality of hollow beauts 8. One side of the hollow beams 8 is formed by the ceramic plate 2. The remaining sides of the hollow béants 8 have, for example, a U-profile. The hollow beams 8 are designed and arranged relative to one another such that they form a common hollow space 10 and that they enclose one or a plurality of quadrilaterals, such as rhombuses or rectangles, preferably squares. The diagonals of the quadrilaterals formed by the hollow beams 8 run parallel to the outer edges of the ..ceramic plate 2, The ceramic plate 2 and the hollow beams::8 contain, Ibr example, silicon carbide or nitride-bonded silicon carbide such as the matériái Advancer®! of the company Saínt-Gobain IndnstrieKeramik Redental

GmbH, Germany, with a silicon carbide contend of roughly 68%. Further examples of'suitable materials based on silicon carbide or nitrogen-bonded silicon carbide are ArmaSicon RTH®, Silit SKD®, or Crystae® of the company Saint-Gobain IndusnieKeramik Rödental GmbH, Germany. The ceramic plate 2 is produced, for example, in a combined casting process that comprises a solid easting process and a hollow casting process.

Fig, 2 depicts a perspective view of a substantially smooth upper face 12 of the ceramic plate 2. In the region of recesses, preferably cross-shaped silts !4, the smooth upper face 12 is interrupted. The cross-shaped slits 14 are preferably arranged relative to the hollow beams 8 such Shat in a projection wit ton each quadrilateral formed by the hollow beams 8, there is precise!} one moss-shaped sht 14, which is readily discernible in Fig. 3, which depicts the upper face ! 2 of the ceramic plate 2 and depicts as dashed lines the hidden lines of the hollow beams 8. The slits 14 extend through the entire ceramic plate 2. As an alternative to the slits 14, grooves that extend only partially through the ceramic plate 2 are provided as recesses.

The hollow beams 8 contribute to reinforcement and, hence, to high stability of the ceramic plate 2. The U-profiles of the hollow beams 8 contribute to particularly good stability and statics. The thickness d of the material of the ceramic plate 2 is, in the region of the beam-like hollow chamber reinforcement 6, in particular on the walls of the beam-like hollow chamber reinforcement, approx, constant, see Fig. 4, The constant thickness of the wails is from 6 mm to 10 mm. The constant, thickness of the walls results in the uniform drying of the ceramic plate 2 during production. By this means, the stability of the. ceramic plate 2 is already increased during production, which facilitates the handling of the ceramic plate 2 during process steps associated with drying.

The higher stability provides lower susceptibility to breakage and lower flexibility of the ceramic· plate 2, The hollow space 1(1 supports uniform drying, since air for drying can flow around the ceramic plate 2 to he dried uniformly from all sides via the hollow space if).

During the production and 1 he use of the ceramic plate 2 in a high-temperature kiln, large temperature gradients regularly occur within the ceramic plate 2. The high temperature gradients cause material stresses within the ceramic plate 2. So that the material of the ceramic plate 2 does not crack with these loads, the slits 14, by means of which excessively high thermal stress is avoided, are preferably provided. The slits Í4 serve to increase the elasticity of the ceramic plate 2. It is particularly advantageous to implement the slits 14 in a crisscross pattern, since the greatest stresses are expected in the center of the ceramic plate 2. or in the center of indi v id «at modules of t lie k 1 In ftn-n ittire 2, it is further advantageous for the width a of the cross-shaped slits 14 to be from 0.2 mm to 0.8 nun, see Fig. 5. This width corresponds to the typical width of a cutting toss on separation of the individual modules. The cross-shaped slits 14 are preferably introduced into the ceramic plate 2 in the urtfired state. The format of the ceramic plate 2 and/or individual modules is in the width h from 1).8 m to i .5 m and in the length 1 from 0.6 m to 3 m.

The hoifow beams 8 can enclose any rectangles, triangles, hexagons, or any shapes at all. The profile of the hollow beams 8 can deviate from the U-profile, as long as an approx, constant thickness of the material of the ceramic plate 2 is guaranteed. The profile of the hollow beams 8 can. for example, be V-shaped and have a triangular cross-section with the boundary formed by the ceramic piate (2). The profile of the holknv beams 8 can also be shaped such that a trapezoidal cross-section is formed. The shape-and number of the cross-shaped siiis 14 can deviate from: the shape and number depicted. Slits 14 that are not implemented in a crisscross

Claims

pattern can even be provided. Sifts 14 can even be completely dispensed with. The -arrangement of the cross* shaped slits 14 relative to the hollow beams 8 can be varied. The recesses, ín particular the cross shape and/or their particular arrangement relative to the hollow beams ti arc, independet»iof|fe8::;|>pp8N hollow chamber reinforcement 6, a separate aspect..ofthe invention·. last of Reference Characters 2 ceramic plate 4 lower face I beam-like hollow chamber reinforcement 8 hollow beam· 1(1 hollow space 12 upper lace 14 slit 16 halfsilt a width of the sift i 4 h width of the ceramic plate 2 d thickness of the ceramic plate 2 1 length of (he ceramic plaie 2 z detail KERÁMIALAP KEMENCËKOCS1-FELÈPÏTMÉNYEKHEZ ÉS TŰZÁLLÓ BÉLÉSEKHEZ Wtctàwlâîmi igétyponiak L Kerámialap ¢2} kerámialapot (2) magában foglaló es tifoîlô bélésekhez, ahol a kerámialap (2) alsó felületén (4) gerendaszerü üreges megerősítés (6) van kiképezve. amei| a kerámialap (2) felső felületével (12|: páfhoZamosáft fefíed, továbbá ahol á geréftdasxet'Ü Üreges megerősítés (b) egyik felületéi a kerámialap (2) képezi, ahol a gerendaszerü üreges mégerősités (6) legalább négy ürege» gerendát (81 tartalmaz, amelyek üregei egyetlen közös üreget ( Î0.! alkotnak, továbbá - az üreges gerendák (8) kereszteződön vannak elrendezve és legalább egy iárömszöget; négyszöget, hatszöget, négyzetet rombuszt vagy nyolcszöget zárnak köríti.
2, Az 1, igénypont szerinti kerámialap (2), ahol az Ürege» gerendák (8) keresztmetszetben derékszögííekj négyzetesekv bérpmszdg vagy trapéz alakúak. 3i.
Az L vagy a 2. igénypont szerinti kerámialap (2), ahol a:négyszög áílői a kerámialap p:) fciílsö: éléivel párhuzamosan vannak elrendezve.
4. Λζ 5-3. igénypontok bármelyike szerinti kerámialap (2). ahoi az üreges gerendák (8) falainak vastagsága a kerámialap (2) vastagságának 35*90%*fc.
5. Λ 4. igénypont szerinti kerámialap (2), ahol az üreges gerendák (8) falainak vastagsága 4-20 mm, előnyösen 6- ! 0 mm.
6. Λζ 1-5. igénypontok bármelyike szerinti kerámialap (2), ahol a kerámialap £2): léplábfe egy mélyedéssel rendelkezik.
7. A 6.. igénypont szerinti kerámialap (2), ahol a kerámialap (2) mélyedése a kerámialap (2) felületében 112} legalább egy hasítékkal (14) vagy legalább egy horonnyal rendelkezik,
8. A ?. igénypont szerinti kerámialap (2), ahol a hasíték (14) vagy a horony ketésM ajafea,
9. A 8. igénypont szerinti kerámialap (2), ahol az üreges gerendák (8) által körülzárt négyszögnek legalább egy kereszt alakó hasítéka (14) vagy kereszt alakú hornya yan.
10. A 6-9. igénypontok bármelyike szerinti kerámialap (2}, ahol a mélyedés 'Wfo előnyösen 0.2-0,8 mm.
11. A 6-í 0, igénypontok bármelyike szerinti kerámialap (2), ahol a mélyedés hossza az üreges gerendákkal (8) határolt felület belső szélességének 20-80%-a.
12. Eljárás az 1-11. igénypontok bármelyike szerinti kerámialap (2) gyártására:, ahol a kerámialapot (2) kombinált öntési eljárással állítjuk elő, amely egy tömör öntési eljárást és égy öreges öntési eljárást íbglá) mágábári,
13. A 12. igénypont szerinti eljárás, ahol legalább aj a kerámialap t'2) és a gerendaszefü üreges mègéfSsitës (6) külső álakjátiak fnegtblélő öreges gipszíormát készítünk ; b) az üreges gipszformát kerámiaiszappal megtöltjük; c) mihelyst a kerámiaiszap a kerámialap (2); tartományában megszilárdult, a kerámiaiszapot az üreges eipszformából eltávolítjuk.