Firing kiln and process for producing porous ceramic member therewith

TECHNICAL FIELD

This application uses the priority right of Japanese Patent Application No. 2004-228649 of August 4, 2004 and PCT Application No. JP2005 / 001264 of January 28, 2005.

The present invention relates to a firing furnace used for producing a honeycomb structured body or the like made of ceramics, a ceramic material or the like, as well as a method for producing a porous ceramic using a firing furnace.

Many different honeycomb filters have been proposed for purifying exhaust gases and catalyst support elements that are used to purify gases produced by combustion engines mounted on vehicles such as buses, trucks, construction machinery and the like.

When it comes to honeycomb filters cleaning exhaust gases and similar components, they use a honeycomb structured body in the form of a non-oxide porous ceramic body made of a material such as silicon carbide, which has extraordinary heat resistance.

Patent document 1 and patent document 2, for example, disclose conventional baking furnaces used to manufacture non-oxide ceramic elements of this type.

The baking furnace used to manufacture such non-oxide ceramic elements is equipped with a heater or similar element placed in the furnace and a thermal insulation layer, which is mainly made of carbon.

Patent document 1: JP-A 2001-48657.

Patent document 2: JP-A 63-302291.

Patent documents US 4, 850, 576 and DE 86 17 516 disclose a plant for firing materials comprising an insulated work space located inside a container in which materials are placed. In the corners and edges of the working space insulation are embedded graphite elements reinforced with carbon fiber, thanks to which gas tightness and better thermal insulation performance during the firing process are achieved.

PROBLEMS SOLVED BY THE INVENTION

In the case of the production of a porous ceramic element made of silicon carbide using the above-mentioned firing furnace, the formed body after the degreasing process is heated and fired at temperatures in the order of 1400 ° C or higher, which causes release to the atmosphere inside the firing furnace , gases containing silicon carbide, silicon, silicon oxide and similar compounds, these gases react with carbon elements inside the firing furnace, converting this material to silicon carbide and similar compounds.

After the transformation of carbon elements into silicon carbide, the surface layer of the heat insulating layer made of silicon carbide changes, which changes the physical properties of the internal layer made of carbon such as the coefficient of thermal expansion, which causes the phenomenon of warping of the heat insulating layer. In addition, oxygen remaining inside the furnace as well as oxygen and similar substances produced by the shaped body tend to react with carbon causing, in addition to conversion into silicon carbide or a similar substance, corrosion of the heat insulating layer.

In the event of warping and corrosion of the thermal insulation layer, its effectiveness is reduced. It is also possible to separate the heat-insulating layer, which prevents the use of a baking furnace. As a result of these phenomena, it is necessary to replace the thermal insulation layer. Replacing the thermal insulation layer is expensive, which creates a problem of high manufacturing costs.

If the thermal insulation properties of the baking furnace are reduced, even if it is not yet necessary to replace the thermal insulation layer, it is no longer possible to maintain an efficient heating process, which results in high firing costs.

The present invention aims to solve the problems described above by providing a baking furnace in which there is no warping and corrosion of the thermal insulation layer, which eliminates the need for frequent replacement of the elements forming the thermal insulation layer, resulting in excellent durability of the thermal insulation layer and high heating efficiency. as well as a method for producing a porous ceramic element using such a baking furnace.

DISCLOSURE OF ELEMENTS OF THE INVENTION ALLOWING SOLVING PROBLEMS

A first aspect of the present invention relates to a firing furnace comprising: a muffle shaped to provide space for the shaped body to be fired; an element constituting a heat generator placed on and / or around the muffle; and a heat-insulating layer with a muffle and heat generator inside. Near the corner parts of the inner surface of the thermal insulation layer is placed a sheet made of carbon material, which is attached to the inner surface of the thermal insulation layer using a connecting element.

In a firing furnace according to the first aspect of the present invention, a sheet made of carbon material can be placed on the lower inner and upper inner surface of the thermal insulation layer, it can be placed on the lateral inner surfaces of the thermal insulation layer, or it can be placed on all inner surfaces of the thermal insulation layer. Preferably, the sheet made of carbon material is made in the form of a graphite sheet, carbon fiber composite (C / C composite) or carbon fabric.

In a preferred solution, the connecting elements are arranged with a density ranging from 2 to 100 pcs / m² per unit of area.

The heat-insulating layer can be attached to the fastening element covering the heat-insulating layer, which is placed on the periphery of the heat-insulating layer by means of a connecting element.

In the baking furnace according to the second aspect of the present invention, the connecting elements are preferably arranged with a density ranging from 4 to 200 pcs / m² per unit of area.

The heat-insulating layer can be divided into many heat-insulating layers, with reinforcing elements that connect and strengthen the divided heat-insulating layers.

In the firing furnace according to the first aspect of the present invention, the heat generator element is preferably in the form of a heater or muffle.

A second aspect of the present invention relates to a method for producing a porous ceramic member by firing a shaped body to obtain a porous ceramic member, the method comprising using the baking furnace of the present invention (claim 13).

EFFECTS OF USING THE INVENTION

In the case of a conventional baking furnace, the part prone to warping due to the transformation of carbon elements into silicon carbide is located mainly in the corner part of the thermal insulation layer. In the firing furnace according to the first aspect of the present invention, due to the proximity to the corner parts of the inner surface of the heat insulating layer of the sheet made of carbon material, the corner part of the heat insulating layer is protected, less susceptible to reacting with other substances and protected against warping and corrosion . In this way, it is possible to eliminate the need for frequent replacement of the elements forming the heat-insulating layer, and, consequently, to obtain a firing furnace with excellent durability and high heating efficiency.

In a firing furnace according to the first aspect of the present invention, the heat insulating layer may be attached to the fastening-shielding element of the heat insulating layer, which is arranged on the periphery of the heat insulating layer by means of a connecting element. In this case, there is no warping of the thermal insulation layer, thanks to which it is possible to obtain a baking furnace with excellent durability.

In the firing furnace according to the first aspect of the present invention, it is possible to use a reinforcing element that connects and strengthens the thermal insulation layers, whereby the thermal insulation layers are well attached to each other. In this case, there is no warping of the thermal insulation layer, as well as almost no flaking of the thermal insulation layer due to corrosion or similar phenomena, which eliminates the need for frequent replacement of the elements forming the thermal insulation layer, and consequently obtaining a firing furnace with excellent durability and high efficiency heating.

As described above, Patent Document 2 proposes a firing furnace for sintering non-oxide ceramic materials in which a sheet extending this element made of multilayer thin graphite elements having an ash content of less than 0.3% by weight is placed inside the thermal insulation element. As shown in the section on the essence of the invention, such a baking furnace is used to produce ceramic materials containing silicon nitride and has a structure comprising a sheet made by laminating thin graphite elements placed inside the thermal insulation element, which eliminates the deposition of impurities, and say more specific, the body made of silicon nitride has no skeleton shape due to reaction with carbon from carbon fibers adhering to the body made of silicon nitride and sintered with it. Scaling of carbon fibers has also been eliminated.

The baking furnace of the present invention is suitable for producing a non-oxide ceramic material such as a porous ceramic body made of silicon carbide or the like during manufacture which does not use sintering aids. When producing a porous ceramic body made of silicon carbide or similar material without using a sintering aid, the problems described above cannot occur. For this reason, the baking furnace described in Patent Document 2 is completely different from the baking furnace of the present invention. Even if the firing furnace of the present invention is used to produce a porous ceramic material such as oxide ceramic, non-silicon carbide ceramic, nitride ceramic or similar material, it is also possible to avoid warping of the heat insulating layer due to a change in its physical properties such as coefficient of thermal expansion and the like.

In the methods for producing a porous ceramic material according to the second aspect of the present invention by firing the shaped body, any firing furnace according to the first aspect of the invention is used to obtain the porous ceramic member, whereby the firing process can be carried out under stable conditions. It is therefore possible to produce highly reproducible under identical conditions porous ceramic materials with excellent properties, while eliminating product contamination by contaminations resulting from warping and corrosion of the thermal insulation layer.

THE BEST WAY TO IMPLEMENT THE INVENTION

The baking furnace according to the first aspect of the present invention comprises: a muffle shaped to provide space for the shaped body to be fired; an element constituting a heat generator placed on and / or around the muffle; and a heat-insulating layer with a muffle and heat generator inside. Near the corner parts of the inner surface of the thermal insulation layer is placed a sheet made of carbon material.

In one embodiment of the first aspect of the present invention, the baking furnace may include: a muffle shaped to provide space for the shaped body to be fired; an element constituting a heat generator placed on and / or around the muffle; and a heat-insulating layer with a muffle and heat generator inside. The heat-insulating layer is in this solution attached to the fastening element shielding the heat-insulating layer, which is located on the periphery of the heat-insulating layer by means of a connecting element.

One variant of the first aspect of the present invention does not have the limitation associated with attaching the heat insulating layer to the fastening element covering the heat insulating layer, which is located on the periphery of the heat insulating layer using the connecting element. In contrast, another variant of the first aspect of the present invention has no limitation associated with the placement of a sheet made of carbon material near the corner parts of the inner surface of the heat insulating layer. Thus, respective variants of the first aspect of the present invention differ from each other in relation to these issues. However, the other elements are made in the same way, so the description given relates to a baking furnace according to both variants of the first aspect of the present invention.

Fig. 1 is a schematic cross-sectional view of a baking furnace according to the first aspect of the present invention, and Fig. 2 is a schematic perspective view of the heat insulating layer forming the firing furnace of Fig. 1. Fig. 2 does not show the covering element of the heat insulating layer 19 .

The baking furnace 10 comprises: a muffle 11 shaped to provide space for the shaped body to be fired;

a heater 12 constituting a heat generator located around the muffle 11; and a thermal insulation layer 13 (13X, 13Y), in which the muffle 11 and the heat generator are inside

12. Outside, there is a metal wall of the furnace 14 separating the furnace from the ambient atmosphere. The furnace wall 14 may be a cooling jacket. In other words, the wall of the furnace 14 can be in the form of a metal element and can have a double structure, inside which there is water, whereby the temperature of the furnace wall 14 is kept in a predetermined range.

The entire floor part of the muffle 11 is supported by a supporting element (not shown here), thanks to which it is possible to move the base (cart) 8, on which the multi-layered body of firing handles 15, in which shaped bodies 9 to be burned are placed, is placed. upper and lower parts of the muffle 11 have heaters 12 made of graphite or similar material.

Heaters are connected to an external power source (not shown here) through terminals 18.

Outside the heater 12 is placed a heat insulating layer 13 (13X, 13Y) comprising three layers, namely carbon elements 13a, 13b and ceramic fibers 13c, which are laminated sequentially in the order shown from the inside. On the inner end parts of the upper and lower 13X thermal insulation layer (near the corner parts) there is a sheet made of carbon material 16. The heat-insulating layer 13, on which the sheet made of carbon material 16 is placed, is attached to the fastening-shielding element of the heat-insulating layer located on the periphery of the insulation layer 13 using carbon screws 17a and nuts 17b, which are connecting elements.

In the device shown in Fig. 1, the left end of the sheet made of carbon material 16 on the left side and the right end of the sheet made of carbon material 16 on the right side are in contact with the thermal insulation layers 13Y located on the right and left side surfaces. This is the preferred solution used in the present invention, however, the ends of the sheet made of carbon material 16 can be placed a short distance from the heat-insulating layers 13Y.

The inner surface of the thermal insulation layer 13 is covered by a sheet made of carbon material 16 for the following reasons. In particular for the production of a porous ceramic element made of silicon carbide, because the carbon element 13a on the inner surface is made mainly of carbon fibers, the inner surface close to the shaped body is transformed into silicon carbide due to the action of gases produced during firing silicon carbide, silicon, gaseous SiO and similar substances. After the transformation of carbon into silicon carbide, the silicon carbide surface layer and the carbon inner layer of the carbon element 13a forming the thermal insulation layer 13 have differing physical properties such as coefficient of thermal expansion and the like, which causes the thermal insulation layer to warp. In order to eliminate warping (reaction) in the thermal insulation layer due to the reactions described above, the inner surface of the thermal insulation layer is therefore covered by a sheet made of carbon material 16.

As shown in fig. 1, the inner surface of the thermal insulation layer is covered by a sheet made of carbon material 16, the sheet made of carbon material 16 is attached to the surface of the thermal insulation layer 13 using screws 17a and nuts 17b, and the thermal insulation layer 13 is tightly attached (thermal insulation layer 13 attached is for the fastening-shielding element of the heat-insulating layer 19), thus, it is possible to eliminate the transformation of the carbon element 13a into silicon carbide due to the occurring reactions, and thus also to eliminate warping and other mechanical deformations of the carbon element 13a.

A sheet made of carbon material 16 can be attached to the inner surface of the heat insulating layer 13 using glue or a similar solution. As shown in Fig. 1, however, it is possible to more effectively eliminate warping of the heat insulating layer 13 by tightly attaching the heat insulating layer 13 using connecting elements 17 (screws 17a and nuts 17b).

In the production of porous ceramic elements such as oxide ceramic materials, carbon ceramic materials other than silicon carbide, nitride ceramic materials or similar materials using the furnace of the structure described above, it is also possible to avoid warping of the thermal insulation layer due to changes in its physical properties such as coefficient of thermal expansion and the like.

In the case of the baking furnace 10 shown in Fig. 1, the thermal insulation layers 13X placed on the lower and upper parts are not extended to the end parts, so that the four corner parts of the thermal insulation layer parts 13 are formed by the thermal insulation layers 13Y, which are located on the right and left lateral surface. Thus, the end parts (corner parts) of the 13Y thermal insulation layers placed on the right and left side surfaces are protected by the 13X thermal insulation layers on the upper and lower parts. As a result, the heat insulating layer 13Y located on the right and left surfaces is less likely to warp by adopting a convex shape outwardly through the central part. If such arrangement of elements is left, the 13X thermal insulation layer placed on the lower and upper surface is, however, more exposed to warping and the central part to take a convex shape directed outwards.

The end parts (near the corner parts) of the heat insulating layer 13 located on the lower and upper surfaces are therefore firmly attached using sheets made of carbon material 16 and connecting elements 17, so that warping can be avoided.

The firing furnace 10 is a furnace intended for continuous operation, in which the firing handles 15 are gradually heated to a high temperature while moving through the furnace, and when the maximum temperature is reached, the temperature is gradually lowered. For this reason, the preferred length of the oven is usually, for example, 10 m or more. The depth (length in the longitudinal direction) of the heat insulating layer 13 is therefore significantly greater compared to the dimensions of the cross-section shown in Fig. 1.

As seen in Fig. 2, sheets made of carbon material 16 are placed on the inner surfaces of the two ends of the upper and lower thermal insulation layer 13 in the form of stripes. The length of the furnace is large enough that sheets made of carbon material 16 also have an elongated shape of stripes arranged in the longitudinal direction of the furnace. The sheet made of carbon material 16 may be made in the form of a long and thin sheet made of carbon material 16 extending from the inlet to the outlet, or it may be in the form of a plurality of sheets made of carbon material 16.

The firing furnace may include an area in which there is no heat insulating layer 13 in the longitudinal direction. In this case, in the area including the heat insulating layer 13, a sheet made of carbon material is placed on the inner surface of the heat insulating layer in the manner described above. In order to avoid the dispersion of SiO and similar substances produced by the shaped body towards the wall of the furnace, a sheet made of carbon material can also, as described above, be placed on parts of the walls not provided with a heat insulating layer 13.

In the case of the baking furnace 10 shown in Fig. 1, a sheet made of carbon material 16 is placed adjacent to the corner parts of the inner surface of the thermal insulation layer 13, however, the sheet made of carbon material can be on the upper and lower inner surface of the thermal insulation layer, it can also be placed on the inner side surfaces of the thermal insulation layers, or be placed on all internal surfaces of thermal insulation layers.

Figures 3-1 to Fig. 3-5 show schematic cross-sections of solutions in which sheets made of carbon material are placed on heat-insulating layers forming suitable kilns for firing, parts other than the heat-insulating layer and its edge fragments are not here shown. As it is visible in the drawings, the methods of making thermal insulation layers, as well as the shapes and methods of fixing sheets made of carbon material differ from each other.

For the thermal insulation layers 63 (63X, 63Y) shown in Fig. 31, the thermal insulation layers 63Y located on the right and left side surfaces are not extended to the upper and lower end portions, and the four corner parts of the thermal insulation layers 63 are formed by 63X thermal insulation layers on the upper and lower part. In this solution, the end parts (corner parts) of the 63X thermal insulation layers placed on the upper and lower parts are protected by 63Y thermal insulation layers located on the right and left side surfaces. As a result, the 63X thermal insulation layers on the top and bottom are less likely to warp by adopting a convex shape outwardly through the center. If this arrangement is left behind, the 63Y heat-insulating layers located on the right and left side surfaces are, however, more likely to warp and assume a convex shape outwardly through the center. However, due to the use of sheets made of carbon material 160 and connecting elements 17 (17a, 17b), the end parts (near the corner parts) of the 63Y heat-insulating layers located on the right and left side surfaces are firmly fixed, thus eliminating warping.

In the apparatus shown in Fig. 3-1, the upper end of a sheet made of carbon material 160 located on the upper surface and the lower end of a sheet made of carbon material 160 located on the lower surface are in contact with 63X thermal insulation layers on the upper and lower surface. This is the preferred solution used in the present invention, however, the ends of the sheet made of carbon material 160 can be placed a short distance from the 63X thermal insulation layers.

The heat-insulating layers 13 (13X, 13Y) shown in Figs. 3-2 are arranged in the same way as the heat-insulating layers 13 shown in Fig. 1, wherein the heat-insulating layers 13X placed on the upper and lower surfaces are not extended to the end portions. Sheets made of carbon material 160 having a shape similar to the letter L are placed here near the corner parts of the heat-insulating layers 13 and firmly fastened with the use of connecting elements 17 (17a, 17b), which eliminates the possibility of warping of the 13X heat-insulating layers located on the top and bottom surface. When using sheets made of carbon material 161 with the shape shown in Fig. 3-2, the heat-insulating layers may be made in the form of heat-insulating layers 63 (63X, 63Y) shown in Figs. 3-1, thereby eliminating the possibility of warping of the 63Y heat-insulating layers.

Since the thermal insulation layers 13 (13X, 13Y) shown in Figs. 3-3 are arranged in the same way as the thermal insulation layers 13 shown in Fig. 1, a description of the construction of the thermal insulation layers 13 will not be provided.

For these heat-insulating layers 13, carbon sheets 162 are attached over the entire surface of the heat-insulating layers 13X located on the top and bottom surfaces, with the left and right end portions (near the corner portions) of the carbon sheet 162 being firmly attached using the connecting elements 17 ( 17a, 17b), which eliminates the possibility of warping 13X thermal insulation layers located on the upper and lower surfaces.

The thermal insulation layers 63 (63X, 63Y) shown in Figs. 3-4 are arranged in the same way as the thermal insulation layers 63 shown in Fig. 1. For these heat-insulating layers 63, carbon sheets 163 are attached to the entire surface of 63Y heat-insulating layers located on the right and left side surfaces, with the upper and lower end portions (near the corner portions) of the carbon sheet 163 being firmly attached using connecting elements 17 (17a, 17b), which eliminates the possibility of warping 63Y thermal insulation layers located on the right and left side surfaces.

The thermal insulation layers 63 (63X, 63Y) shown in Figs. 3-5 are arranged in the same way as the thermal insulation layers 63 shown in Fig. 1. For these heat-insulating layers 63, carbon sheets 164 are attached to the entire surface of the heat-insulating layers 63 (63X, 63Y) located on the top and bottom surfaces, with the top and bottom end parts (near the corner parts) and the left and right horse parts Cowe (near the corner parts) of carbon sheet 164 are firmly fastened using connection elements 17 (17a, 17b), thanks to which the possibility of warping 63Y thermal insulation layers located on the right and left side surfaces has been eliminated.

As described above with respect to the placement of the carbon sheet, because warping can occur in parts of the heat insulating layers that are not widened to the end parts between the heat insulating layers, it is possible to eliminate warping and similar phenomena occurring in the heat insulating layers by placing carbon sheets and / or fastening elements at least near the corner parts of the thermal insulation layers, which are not extended to end parts. In this case, in order to reduce corrosion of the thermal insulation layers, a larger area of ​​the carbon sheet is better, and the carbon sheets can be placed on the entire upper and lower inner surface, on the entire left and right inner surface of the thermal insulation layers, or on all surfaces of the inner thermal insulation layers.

Sheets made of carbon material is a sheet material consisting mainly of carbon, the sheet material preferably being in the form of a graphite sheet, carbon fiber composite (C / C composite) or carbon fabric.

A graphite sheet is a sheet consisting mainly of graphite particles, its density preferably being in the range from 0.1 to 5 g / cm³. The graphite sheet preferably also has a thickness in the range from 0.05 to 5 mm.

In the case where the graphite sheet is placed in the corner parts of the inner surfaces of the heat insulating layers, as shown in Fig. 2, the width of one graphite sheet is preferably in the range from 5 to 50% of the width L (mm) of the upper and lower surface.

The carbon fiber composite (C / C composite) is a composite containing carbon particles and carbon fibers, whose bulk density is preferably in the range from 0.5 to 5 g / cm³. The C / C composite preferably also has a thickness in the range of 0.5 to 5 mm, while the width of the C / C composite is preferably in the range of 5 to 50% of the width L (mm) of the upper and lower surface of the thermal insulation layers, such as this is shown in figure 2.

Carbon fabric is a fabric made of carbon fibers in a papermaking process or by weaving. In the case of a product made in a papermaking process, carbon fibers are turned off using an inorganic bonding material or similar substance, and then shaped to form a sheet. The density of the carbon fabric is preferably in the range of 0.05 to 5 g / cm³, the thickness of the carbon fabric is preferably in the range of 0.1 to 5 mm, and the width of the carbon fabric is preferably in the range of 5 to 50% of the width L (mm) of the upper and lower surface of the heat insulating layers 13, as shown in Fig. .

2.

When connecting elements such as nuts and bolts are used, the density of the arrangement of the connecting elements per unit area is preferably in the range from 2 to 100 pcs / m².

In the case where the density of the arrangement of connecting elements is less than 2 pcs / m², it is not possible to accurately cover the surface of the thermal insulation layers by a sheet made of carbon material, which causes silicon and similar substances to penetrate through the thermal insulation layers, where they cause a reaction. And vice versa, if the density of the arrangement of connecting elements is greater than 100 pcs / m², a large number of connecting elements causes high costs of the device.

The lower limit of the density of arrangement of connecting elements is preferably 4 pcs / m², and the upper limit of the density of arrangement of connecting elements is preferably 40 pcs / m².

Although the firing furnace 10 shown in Fig. 1 is a continuous furnace, the baking furnace of the present invention can be made as a batch furnace.

The ambient atmosphere inside the baking furnace 10 is preferably an inert gas atmosphere, and more preferably it is a noble gas atmosphere such as argon, nitrogen and the like.

As shown in fig. 1, a plurality of shaped bodies (shaped ceramic bodies) 9 used to manufacture porous ceramic elements are placed in the firing holder 15, and a plurality of firing holders 15 containing the shaped bodies 9 are placed on top of each other to obtain a multi-layered body, with the purpose of carrying out the firing process, the multilayer body is placed on the base (trolley) 8, which is placed in the baking furnace 10. The shaped bodies are subjected to a degreasing process here, which is intended to remove resinous compounds and similar substances.

In the firing furnace design 10 shown, the heaters 12 are located above and below the muffle 11 with a predetermined gap, the firing handle 15 being gradually heated to high temperature by the heaters 12 when moving through the furnace, and after reaching the maximum temperature the temperature is gradually lowered. The base 8, on which the multilayer body consisting of firing handles 15 is placed, is continuously moved from the inlet to the interior of the firing furnace 10, and after sintering, the firing handles 15, whose temperature is lowered, are removed from the outlet to produce a porous ceramic body.

In the firing furnace 10 shown in Figure 1, the heat-insulating layer 13, to which the inner surface, using bolts 17a and nuts 17b serving as connecting elements, is firmly attached a sheet made of carbon material 16, is also attached to the fixing-shielding element thermal insulation layer 19. However, due to the permanent attachment of the heat-insulating layer 13 to the fastening-shielding element of the heat-insulating layer 19 using connecting elements without using a sheet made of carbon material 16, it is also possible to eliminate warping of the heat-insulating layer 13.

The density of the arrangement of the connecting elements is preferably in the range from 4 to 200 pcs / m².

In the case where the density of the arrangement of connecting elements is less than 4 pcs / m², it is not possible to attach the heat-insulating layer 13 precisely, which causes a tendency to warp and other damage to the heat-insulating layer. And vice versa, if the density of the arrangement of connecting elements is greater than 200 pcs / m², a large number of connecting elements causes high costs of the device.

The lower limit of the density of arrangement of connecting elements is preferably 8 pcs / m², and the upper limit of the density of arrangement of connecting elements is preferably 80 pcs / m².

In one embodiment of the first aspect of the present invention, the baking furnace for making ceramic components includes a muffle shaped to provide space for the shaped body to be fired, a heat generator element located on and / or around the muffle, and a heat insulating layer in which the muffle and heat generator are inside. The thermal insulation layer in this solution is divided into many thermal insulation layers, whereby reinforcing elements are used that connect and strengthen the divided thermal insulation layers.

In the firing furnace of Fig. 1 according to the first aspect of the present invention, a sheet made of carbon material is placed near the corner parts of the inner surface of the heat insulating layer, thereby avoiding warping of the heat insulating layer. In the above variant of the first aspect of the present invention, however, the reinforcing element used to connect and reinforce the heat-insulating layers 13 is, however, arranged in such a way as to eliminate warping.

Fig. 4 is a schematic perspective view of part of the heat insulating layer. As shown in fig. 4, the U-shaped reinforcing element 21 can be placed on the lowest connecting part 13a connecting carbon elements, whereby the reinforcement of the heat-insulating layer is obtained, or the U-shaped reinforcing element 21 can be placed in the in such a way that it connects the lowest carbon element 13a to the carbon element 13b located outside the carbon element 13a.

In Fig. 4 there is no visible fastening element enabling the reinforcing element 21 to be permanently attached. However, as shown in Fig. 4, the reinforcing element 21 can be positioned in such a way that it covers it from above, it can be connected to it permanently attached by means of connecting elements (fasteners) such as screws, nuts or similar elements, or can be glued using inorganic glue or a similar solution.

Although this is not a limitation of the invention, the materials of which the reinforcing element 21 is made include carbon fiber composite (C / C composite), graphite and similar materials. The reinforcing element 21 may further have a U-shaped rectangular cross-section, an L-shaped cross-section or a plate-shaped. If an L-shaped or plate-shaped cross-section is used, the reinforcing element 21 must be permanently attached using connecting elements.

If a reinforcing element 21 is used, sheets made of carbon material should be placed at least near the corner parts of the inner surface of the heat insulating layer. In particular, when manufacturing a porous ceramic member made of silicon carbide, such a design allows the conversion of the carbon element 13a to silicon carbide due to the reactions that occur.

A sheet made of carbon material can be attached to the inner surface of the heat insulating layer 13 using glue or a similar solution, or it can be attached to the heat insulating layer 13 using screws 17a and nuts 17b serving as connecting elements (or it can be permanently attached to the fastening element - covering the thermal insulation layer).

In an embodiment of the first aspect of the present invention, in which only the reinforcing element is used, the density of the arrangement of the reinforcing elements on the surface unit is preferably in the range from 3 to 15 pcs / m².

The term area of ​​the thermal insulation layer refers to the area of ​​the main surface of the thermal insulation layer, and the reinforcing element is arranged in such a way as to cover at least part of the main surface of the thermal insulation layer. In this case, the dimensions of the reinforcing element covering part of the main surface of the thermal insulation layer are such that its length is in the range of 50 to 100 mm, and its width is in the range of 200 to 400 mm, such reinforcing elements are arranged maintaining the density described above.

In the case when the density of the arrangement of reinforcing elements on the surface unit of the thermal insulation layer is less than 3 pcs / m², it is not possible to attach the heat-insulating layer 13 precisely, which causes a tendency to warp and other damage to the heat-insulating layer. And vice versa, if the density of the arrangement of reinforcing elements is greater than 15 pcs / m², a large number of connecting elements causes too high costs of the device.

The upper limit of the density of the arrangement of reinforcing elements on the surface unit of the heat insulating layer is preferably 8 pcs / m². The sizes of the reinforcing element covering part of the main surface of the thermal insulation layer are selected in the same way as in the case described above.

In an embodiment of the first aspect of the present invention, in which the reinforcing elements are placed on an attached sheet made of carbon material for permanently fixing a sheet made of carbon material using reinforcing elements, the density of the arrangement of the reinforcing elements on the surface unit of the heat insulating layer is preferably in the range of 2 to 15 pcs./m².

In the case when the density of the arrangement of reinforcing elements on the unit of the surface of the thermal insulation layer is less than 2 pcs / m², it is not possible to attach the heat-insulating layer 13 precisely, which causes a tendency to warp and other damage to the heat-insulating layer. And vice versa if the density of reinforcing elements is greater than 15 pcs / m², a large number of connecting elements causes high costs of the device.

The upper limit of the density of the arrangement of reinforcing elements on the unit of the surface of the thermal insulation layer in a more preferred solution is 8 pcs / m².

The following description discusses a baking furnace that uses a heating system that generates heat by applying electrical current to a heater (heat generating body) serving as a heat generator, however, the firing furnaces according to the first to third aspects of the present invention may be adapted for use. induction heating system.

Fig. 5 is a schematic cross-section of a baking furnace according to the present invention in which an induction heating system is used.

Firing furnace 30 includes a muffle 32 shaped in such a way that there is space for the shaped body to be burned and serving as a heat generator, a heat insulating layer 33 placed outside the muffle 32 and a coil 31 with many coils of wound wire, which is placed outside the heat-insulating layer 33. The heat-insulating layer 33 can in this solution be placed outside the coil 32.

On the inner, end parts (near the corner parts) of the upper and lower thermal insulation layer 33 there is a sheet made of carbon material 16, which is permanently attached to the surface of the thermal insulation layer 33 using screws 17a and nuts 17b made of carbon and serving as elements connection. The heat insulating layer 33 and the sheet made of carbon material 16 are further attached by means of connecting elements to the fastening-shielding element of the heat insulating layer 34.

As shown in Fig. 4, also in this firing furnace 30 a reinforcing element 21 can be used to connect and reinforce the heat insulating layer 33.

The entire floor part of the muffle 32 is supported by a supporting element (not shown here), whereby the multilayer body of the firing handles 36 in which the shaped bodies to be fired are placed can be moved.

The baking furnace 30 includes an induction heating system in which an alternating electric current is applied to the coil, so that 30 muffles (heat-generating body) located inside the firing furnace 32 generate eddy current, thanks to which the temperature of the muffle (heat-generating body) ) 32 increases to such an extent that it can be used as a heater.

If, moreover, the object to be heated is made of electrically conductive material, then the electric current is generated in this object, thereby generating heat itself.

In this embodiment, the muffle furnace 30 (heat-generating body) 32 made of carbon (graphite) is placed inside the coil 31, so that when the alternating current is supplied to the coil 32, an eddy current is generated, which generates heat through the muffle ( heat generating body) 32, and hence heating of the object to be heated, such as shaped body 9 or the like.

The ambient atmosphere inside the baking furnace 30 is preferably an inert gas atmosphere such as argon, nitrogen and the like.

As shown in fig. 5, a plurality of shaped ceramic bodies used to manufacture porous ceramic members are placed in a firing holder 13, and a plurality of firing holders containing shaped bodies 9 (shaped ceramic bodies) are stacked on top of each other to obtain a multi-layered body, for the firing process, the multilayer body is placed on a base 35, which is placed in the firing furnace 30. The shaped bodies 9 are subjected to a degreasing process here, which aims to remove resinous compounds and similar substances.

The baking furnace includes a muffle (heat-generating body) 32, which generates heat when electric current is applied to the coil 31, whereby the firing handle 15 is gradually heated to high temperature as it moves through the furnace, and when the maximum temperature is reached, the temperature is gradually lowered. The base 35, on which the multilayer body consisting of firing handles 15 is placed, is continuously moved from the inlet to the firing furnace 30, and after the temperature of the firing handles 15 has been lowered, they are removed from the outlet to produce a porous ceramic element .

If an induction heating system is used, a more effective heating process can be obtained because the muffle (heat-generating body) 32 can be placed near the object being heated.

In the firing furnace 30 shown in Fig. 5, the heat insulating layers 33X placed on the bottom and top are not extended to the corresponding end parts, so that the four corner parts of the heat insulating layer part 33 are formed by the heat insulating layers 33Y, which are located after left and right side. Thus, the end parts (corner parts) of the 33Y thermal insulation layers placed on the right and left are protected by the 33X thermal insulation layers on the upper and lower parts. As a result, the 33Y heat-insulating layers located on the right and left are less likely to warp by adopting a convex shape outwardly through the central part. However, if this arrangement is left in place, the 33X thermal insulation layers on the lower and upper surfaces are more likely to warp and the central part to take a convex shape outward. Thanks to the use of connecting elements, the end parts (near the corner parts) of the 33X thermal insulation layers placed on the lower and upper surfaces are therefore firmly attached, which makes it possible to eliminate warping.

Thus, if the four corner parts of the heat-insulating layers 33 are formed by the 33X heat-insulating layers on the lower and upper surfaces, the 33Y heat-insulating layers are more prone to warping, i.e. parts that are near the corner parts of the 33X heat-insulating layers located on the right and left side surfaces are preferably attached using connecting elements.

Also in the case of the thermal insulation layers 33 shown in Fig. 5, as well as in the case of the thermal insulation layers shown in Fig. 3-1 to 3-5, the carbon sheet can be placed on the entire inner surfaces of the thermal insulation layer, the carbon sheet can be placed on the entire part or one of the inner parts of the thermal insulation layers located on the right and left, a carbon sheet with a shape similar to the letter L can be placed in the corner parts of the thermal insulation layer, or the carbon sheet can be placed on the entire inner surface of the thermal insulation layer.

Regarding the ceramic materials manufactured using the firing furnaces of the first to third aspects of the invention, it is possible to list various ceramic materials, which list is not intended to limit the invention. One of them is a porous ceramic material that can be used as a filter or catalyst carrier. As for the materials from which the porous ceramic elements are made, they may be, for example, oxide ceramic materials such as cordierite, alumina, silicon dioxide, mullite, aluminum titanate or similar materials, carbide ceramics such as silicon carbide, zirconium carbide, titanium carbide, tantalum carbide, tungsten carbide and similar materials, nitride ceramic materials such as aluminum nitride, silicon nitride, boron nitride, titanium nitride and similar materials, silicon carbide and silicon composites and similar materials. It is desirable to use non-oxide ceramic materials such as carbide ceramics, nitride ceramic materials and similar materials having high heat resistance, excellent mechanical properties and excellent thermal conductivity, with silicon carbide being most preferably used from non-oxide ceramic materials.

With respect to the use of a porous ceramic material as described earlier, it is possible to use such material as a ceramic filter, catalyst carrier or the like used to clean exhaust gases from an internal combustion engine such as a diesel engine or the like.

Porous ceramic material intended for use as a ceramic filter or catalyst support is referred to herein as a honeycomb structured body.

The following is a description of a honeycomb structured body manufactured using the firing furnace described above, and a manufacturing method comprising a firing process.

The honeycomb structured body has a structure comprising a plurality of post-shaped porous ceramic elements having a large number of through-going openings that are arranged parallel to each other in the longitudinal direction in the direction of the walls separating the cells from each other, the porous ceramic elements being connected together using a layer of sealing material.

Fig. 6 is a schematic perspective view of one example embodiment of the honeycomb structured body.

Fig. 7 (a) is a perspective view that schematically shows the honeycomb structured body of Fig. 6, and Fig. 7 (b) is a cross-sectional view taken along the line BB of Fig. 7 (a ).

The honeycomb structured body 40 has a structure comprising a plurality of porous ceramic members 50 made of silicon carbide and joined together using a sealing material layer 43 to form a ceramic block 45, with a sealing material layer 44 formed on the perimeter of the ceramic block 45. The porous ceramic element 50 has a construction here comprising a large number of through-holes 51 which are arranged parallel to each other in the longitudinal direction in the direction of the walls separating the holes 53 from each other, so that it can act as a particle collecting filter.

In other words, as seen in Fig. 6 (b), each of the through holes 51 formed in the porous ceramic member 50 made of silicon carbide is sealed by means of a spigot 52 located at one of its ends on the inlet side or outlet, whereby the exhaust gases introduced through the opening 51 are released through another opening 51 after passing through each separation wall 53 that separates the openings 51 from each other. By passing the exhaust gas through the separation wall 53, the particles are retained by the separation wall 53, which ensures the cleaning of the exhaust gas.

Since this type of honeycomb structured body has excellent heat resistance and provides the possibility of easy regeneration, it is used in a variety of large-size vehicles and vehicles equipped with a diesel engine.

A sealing material layer 43 sandwiched between the porous ceramic elements 50 serves as a bonding layer used to connect the porous ceramic elements 50 together, as well as a filter. As for the material from which the sealing material layer 43 is made, preferably a material similar to the material of which the porous ceramic member 50 is made is, but this is not a limitation of the invention.

A sealing material layer 44 formed around the periphery of the ceramic block 45 is used to eliminate the release of exhaust gas from the peripheral portion of the ceramic block 45 when the honeycomb structured body 40 is located in the exhaust system of an internal combustion engine. As for the material of which the sealing material layer 44 is made, preferably material similar to the material of which the porous ceramic member 50 is made is, but this is not a limitation of the invention.

As for the porous ceramic member 50, the end portions of the through holes do not necessarily have to be sealed, but if they are not sealed, the honeycomb structured body can be used as a catalyst carrier on which the exhaust gas purifying catalyst can be deposited. .

The porous ceramic element shown in Fig. 7 is mainly made of silicon carbide, but it can be made of a silicon-containing ceramic material formed by combining silicon metal with silicon carbide or a ceramic material combined with silicon and silicon compound. As described above, it can be made of carbide ceramics other than silicon carbide, nitride ceramics, or oxide ceramics. If necessary, it is possible to add metallic silicon to obtain a content in the range of 0 to 45% by weight of the total weight.

The average pore diameter of the porous ceramic member 50 is preferably in the range from 5 to 100 Pm. The average pore diameter smaller than 5 μm leads to easy clogging of the element by retained particles. Conversely, an average pore diameter exceeding 100 μm leads to the passage of particles through the pores, and thus the particles cannot be retained, which prevents the porous ceramic element from being used as a filter.

The porosity of the porous ceramic member 50 is preferably in the range of 40 to 80%, but this is not a limitation of the invention. If the porosity is less than 40%, the particles clog the porous ceramic member. Conversely, a porosity exceeding 80% reduces the strength of the pole-shaped body, so it can be easily broken.

Regarding the particle size of the ceramic material used to manufacture the porous ceramic element 50, particles with less tendency to shrink during the firing process are preferably used, preferably they can be, for example, particles prepared by combining 100 parts by weight of ceramic powder with an average particle diameter in the range from about 0.3 to about 50 μm with 5 to 65 parts by weight of ceramic powder with an average particle diameter in the range from about 0, 1 to about 1.0 μm, but this is not a limitation of the invention. By mixing in the above described ratio of ceramic powders with the above average particle diameters, it is possible to produce a pole-shaped body made of porous ceramic material.

As for the structural shape of the honeycomb structured body 40, it is not limited to the cylindrical shape shown in Fig. 1, but it can be any desired shape such as the shape of a pole with a flattened circle, i.e. a pole with an elliptical cross section , or the shape of a rectangular pole.

The honeycomb structured body 40 can be used as a catalyst carrier, in which case a catalyst (exhaust gas conversion catalyst) is used to convert the exhaust gas in this case on the honeycomb structured body.

By using the honeycomb structured body as a catalyst carrier, it is possible to effectively transform toxic components of exhaust gas, such as HC, CO, NOx and similar compounds, and HC and similar compounds arising from organic compounds, a small amount of which is contained in the structural body of honeycomb construction.

As for the exhaust gas catalyst, it can be, for example, a precious metal such as platinum, palladium, rhodium or similar material, but this is not a limitation of the invention. Each of these precious metals can be used separately or a combination of two or more of these materials can be used.

The following is a description of the method for manufacturing the honeycomb structured body.

In the described method of manufacturing a honeycomb structured body, a porous ceramic element 50 made of silicon carbide is used as a component, however, the choice of porous ceramic element material is not particularly limited.

More specifically, a multi-layer ceramic body is used to form the ceramic block 45 (see Fig. 6).

The multilayer ceramic body has a pole structure in which a plurality of pole-shaped porous ceramic elements 50 are joined together by means of a sealing material layer 43.

To produce a porous ceramic body made of silicon carbide, first, by adding a binder and dispersant solution to the silicon carbide powder, a mixture is prepared that is mixed using a powder mixer or similar device, kneaded using a kneader, and then formed by extrusion to obtain a pole-shaped body having substantially the same shape as shown in Fig. 7 porous ceramic element 50.

Regarding the particle size of the silicon carbide powder, preferably particles with a smaller tendency to shrink during the firing process are preferably used, which may preferably be, for example, silicon carbide powder prepared by combining 100 parts by weight of powder with an average particle diameter in the range of from about 0, 3 to about 50 μm with 5 to 65 parts by weight of powder with an average particle diameter in the range of from about 0.1 to about 1.0 μm, but this is not a limitation of the invention.

As for the binder mentioned above, it may be, for example, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyethylene glycol, phenol resin, epoxy resin or similar substances, but this is not a limitation of the invention.

The abovementioned binder is preferably used in an amount of from about 1 to about 10 parts by weight per 10 parts by weight of silicon carbide powder.

As for the dispersant solution, examples of such a substance include organic solvents such as benzene or similar substances, alcohols such as methanol or similar substances and water or similar substances, but this is not a limitation of the invention.

A suitable amount of the above-mentioned dispersant solution is added to the mixture so that the viscosity of the mixture is within a predetermined range.

The shaped body made of silicon carbide is then dried, and if required, the process of sealing the outlet holes is also carried out, so that the predetermined through holes are filled with plugs, after which the resulting shaped body is again subjected to the drying process.

Then the resulting shaped body made of silicon carbide is heated to a temperature of about 400 - 650 ° C in an atmosphere containing oxygen to degrease it, after which it is heated to a temperature of about 1400 - 1200 ° C in an atmosphere of an inert gas such as nitrogen, argon or the like gas to burn it, whereby the powdered ceramic material is sintered to produce a porous ceramic element made of silicon carbide.

When performing the firing process, any firing furnace according to the first aspect of the invention is used.

In other words, any of the following firing furnaces of the following are used: a firing furnace according to the first aspect of the invention comprising: a muffle shaped to provide space for the shaped body to be fired; an element constituting a heat generator placed on and / or around the muffle; and a heat insulating layer, in the interior of which there is a muffle and a heat generator, in which a sheet made of carbon material is placed near the corner parts of the inner surface of the heat insulating layer; a baking furnace according to a first aspect of the invention comprising: a muffle shaped to provide space for the shaped body to be fired; an element constituting a heat generator placed on and / or around the muffle; and a heat-insulating layer, in the interior of which there is a muffle and a heat generator, in which the heat-insulating layer is attached to the fastening-shielding element of the heat-insulating layer, which is located on the periphery of the heat-insulating layer using connecting elements; and a firing furnace according to a first aspect of the invention comprising: a muffle shaped to provide space for the shaped body to be fired; an element constituting a heat generator placed on and / or around the muffle; and a heat-insulating layer, in the interior of which there is a muffle and a heat generator, in which the heat-insulating layer is divided into many heat-insulating layers, where reinforcing elements are used that connect and strengthen the divided heat-insulating layers.

During the firing process, the temperatures described above are used, and thus SiO, Si and SiC contained in the shaped body made of silicon carbide are evaporated, which causes the thermal insulation layer to warp. However, because in the first aspect of the invention the part of the heat-insulating layer in which warping occurs is covered by a sheet made of carbon material, or because this part is firmly attached, the phenomenon of warping of the heat-insulating layer does not occur, so that one firing furnace can be used for a long time , which enables the production of a porous ceramic element under the same conditions and with high repeatability. Each of the baking furnaces according to the first aspect of the present invention may further be made as a continuous furnace, thus making it possible to carry out a continuous process for producing porous ceramic elements 50.

Many of the porous ceramic elements 50 thus produced are then joined together by means of a sealing material layer 43, after which they are processed to obtain a predetermined shape, and a sealing material layer 34 is made at their periphery, which completes the manufacturing process structural honeycomb structured body.

EXAMPLES (Example 1)

Powdered α-type silicon carbide with an average particle diameter of 10 μm (60% by weight) was wet mixed with powdered α-type silicon carbide and an average particle diameter of 0.5 μm (40% by weight), followed by up to 100 parts by weight of the resulting mixture 5 parts by weight of organic binder (methyl cellulose) and 10 parts by weight of water were added and kneaded to obtain a mixture. Then a small amount of plasticizer and glidant was added and kneaded, after which the resulting mixture was extrusion-molded to obtain a shaped intermediate.

Then, the aforementioned intermediate was dried using a microwave dryer or similar device to obtain a dried ceramic body, predetermined through holes were filled with paste of the same material as the intermediate, then, after re-drying using a dryer, the obtained product was defatted at 400 ° C and fired at 2200 ° C for 3 hours under argon at atmospheric pressure to obtain a porous ceramic element in the shape shown in Figure 4, which has the form of a body made of sintered 34mm silicon carbide ₂ x 34 mm x 300 mm, the number of through holes is 31 pcs / cm and the cell wall thickness is 0.3 mm.

During the firing process, a firing furnace was used, in which sheets made of carbon material (FGL-2535 (fabric) manufactured by Nippon Carbon Co., Ltd., density 0.16 g / cm were placed on the end inner parts of the upper and lower thermal insulation layer³) as shown in Fig. 1.

Then, the method described in the section "THE BEST METHOD OF IMPLEMENTING THE INVENTION" was carried out, i.e. many of the porous ceramic elements 50 made of silicon carbide shown in Fig. 6 joined together using a sealing material layer 43 to form a ceramic block 45, and on their periphery there is a layer of sealing material 34 to produce a honeycomb structured body 40.

The above-mentioned firing furnace was further used to carry out a continuous process of producing porous ceramic bodies lasting 1000 hours, during which the heat-insulating layers forming the firing furnace were observed for warping, but no warping of the heat-insulating layers was found.

The honeycomb structured body in which the porous ceramic elements produced in this way are used has properties that enable it to be used as a filter, while the honeycomb structured body in which the ceramic elements produced in the continuous process are used does not show any change in properties structural honeycomb structured body.

(Example 2)

The process is identical to Example 1, except that sheets made of carbon material placed on the end parts of the inner surfaces of the upper and lower heat-insulating layer forming the baking furnace were changed to DON-3000 (graphite foil manufactured by Donack Co., Ltd., density 0, 15 g / cm³), was used to manufacture porous ceramic elements, and the obtained porous ceramic elements were used to produce a honeycomb structured body. In this case, the processes for producing porous ceramic elements were repeated cyclically for 1000 hours in the same way as in Example 1, during which the heat-insulating layers forming the firing oven were observed for warping.

As in example 1, no warping of the thermal insulation layers was found.

The honeycomb structured body in which the porous ceramic elements produced in this way are used has properties that enable it to be used as a filter, while the honeycomb structured body in which the ceramic elements produced in the continuous process are used does not show any change in properties structural honeycomb structured body.

(Example 3)

The process is the same as in Example 1, except that on the end parts of the inner surface of the upper and lower heat-insulating layers forming the baking furnace, no sheets made of carbon material were placed, and the heat-insulating layers 13 were attached, used for the fastener-covering of the heat-insulating layer 19 with using screws 17a and nuts 17b serving as connecting elements, was used to manufacture porous ceramic elements, the obtained porous ceramic elements were used to produce a honeycomb structured body.

In this case, the process of producing porous ceramic elements was carried out continuously for 1000 hours, in the same way as in Example 1, with the thermal insulation layers forming the baking furnace observed for warping after 700 hours and 1000 hours. No warping of thermal insulation layers was found at any time.

The honeycomb structured body in which the porous ceramic elements produced in this way are used has properties that enable it to be used as a filter, while the honeycomb structured body in which the ceramic elements produced in the continuous process are used does not show any change in properties structural honeycomb structured body.

In this example, the density of the arrangement of connecting elements per unit area was 4 pcs / m².

(Example 4)

The process is identical to that in Example 1, except that on the end parts of the inner surfaces of the upper and lower thermal insulation layers forming the baking furnace, no sheets made of carbon material were placed, and the thermal insulation layers 13 were attached to the fastening element shielding the thermal insulation layer 19 using screws 17a and 17b nuts serving as connecting elements were used to manufacture porous ceramic elements, the resulting porous ceramic elements were used to produce a honeycomb structured body.

In this case, the process of producing porous ceramic elements was carried out continuously for 1000 hours, in the same way as in Example 1, with the thermal insulation layers forming the baking furnace observed for warping after 700 hours and 1000 hours. No warping of the thermal insulation layers was found at any time.

The honeycomb structured body in which the porous ceramic elements produced in this way are used has properties that enable it to be used as a filter, while the honeycomb structured body in which the ceramic elements produced in the continuous process are used does not show any change in properties structural honeycomb structured body.

In this example, the density of the arrangement of connecting elements per unit area was 100 pcs / m².

(Example 5)

The process is identical to Example 1, except that a reinforcing element 21 in the form of a composite material made of carbon fibers (C / C composite (K-200 manufactured by Kureha Chemical Industry Co., Ltd.) is attached to the connecting portion of the heat-insulating layers forming the baking furnace. , density 1.75 g / cm³), as shown in Fig. 4, was used to manufacture porous ceramic elements, and the obtained porous ceramic elements were used to produce a honeycomb structured body. In this case, the above-mentioned firing furnace was used to carry out a continuous process of producing porous ceramic elements in the same way as in Example 1, with the heat-insulating layers forming the firing furnace observed for warping.

No warping of thermal insulation layers.

The honeycomb structured body in which the porous ceramic elements produced in this way are used has properties that enable it to be used as a filter, while the honeycomb structured body in which the ceramic elements produced in the continuous process are used does not show any change in properties structural honeycomb structured body.

(Example 6)

The process is identical to Example 1, except that sheets made of 160 carbon material (FGL-2535 (fabric) manufactured by Nippon Carbon Co., Ltd were placed near the end parts of the inner surfaces of the 63Y thermal insulation layers on the right and left side surfaces. ., density 0.16 g / cm³), as shown in Fig. 3-1, while the heat insulating layers 63Y and sheets made of carbon material 160 were attached to the fastening element shielding the heat insulating layer 19 using connecting elements 17, were used to manufacture porous ceramic elements, the resulting porous elements ceramic was used to produce a honeycomb structured body. In this case, the above-mentioned firing furnace was used to manufacture porous ceramic elements continuously for 1000 hours, with the heat-insulating layers 63 forming the firing furnace observed for warping.

No warping of thermal insulation layers 63 was found.

The honeycomb structured body in which the porous ceramic elements produced in this way are used has properties that enable it to be used as a filter, while the honeycomb structured body in which the ceramic elements produced in the continuous process are used does not show any change in properties in a honeycomb structured body.

In this example, the density of the arrangement of connecting elements per unit area was 4 pcs / m².

(Example 7)

The process is identical to Example 1, except that during firing, sheets made of 161 "L" carbon material (FGL253C (fabric) manufactured by Nippon Carbon Co., Ltd. were placed at four corners of the inner surface of the heat insulating layer 13. 0.16 g / cm³), as shown in Figs. 3-2, while the heat insulating layer 13 and sheets made of carbon material 161 were attached to the fastening-shielding element of the heat insulating layer 19 using connecting elements 17, used to produce porous ceramic elements, the resulting porous ceramic elements were used to produce a honeycomb structured body. In this case, the above-mentioned firing furnace was used to manufacture porous ceramic elements continuously for 1000 hours, with the heat-insulating layers 13 forming the firing furnace observed for warping.

No warping of thermal insulation layers 13 was found.

The honeycomb structured body in which the porous ceramic elements produced in this way are used has properties that enable it to be used as a filter, while the honeycomb structured body in which the ceramic elements produced in the continuous process are used does not show any change in properties structural honeycomb structured body.

In this example, the density of the arrangement of connecting elements per unit area was 4 pcs / m².

(Example 8)

The process is identical to Example 1, except that during firing, sheets made of carbon material 162 (FGL-253C (fabric) manufactured by Nippon Carbon Co., Ltd., density 0, were placed on the entire inner surfaces of the upper and lower thermal insulation layer 13. 16 g / cm³), as shown in Figs. 3-3, while the heat-insulating layers 13 and sheets made of carbon material 162 were attached to the fastening-shielding element of the heat-insulating layer 19 by means of connecting elements 17, used to produce porous ceramic elements, and the resulting porous ceramic elements were used to produce a honeycomb structured body. In this case, the above-mentioned firing furnace was used to manufacture porous ceramic elements continuously for 1000 hours, with the heat-insulating layers 13 forming the firing furnace observed for warping.

No warping of thermal insulation layers 13 was found.

The honeycomb structured body in which the porous ceramic elements produced in this way are used has properties that enable it to be used as a filter, while the honeycomb structured body in which the ceramic elements produced in the continuous process are used does not show any change in properties structural honeycomb structured body.

In this example, the density of the arrangement of connecting elements per unit area was 4 pcs / m².

(Example 9)

The process is identical to that in Example 1, except that during firing on the entire inner surfaces of the 63Y heat-insulating layers on the right and left side surfaces, sheets made of carbon material 163 (FGL-253C (fabric) manufactured by Nippon Carbon Co. were placed, Ltd., density 0.16 g / cm³), as shown in Figs. 3-3, while the heat-insulating layers 63Y and sheets made of carbon material 163 were attached to the fastening-shielding element of the heat-insulating layer 19 using connecting elements 17, were used to manufacture porous ceramic elements, and the resulting porous ceramic elements were used to produce a honeycomb structured body. In this case, the above-mentioned firing furnace was used to manufacture porous ceramic elements continuously for 1000 hours, with 63Y thermal insulation layers forming the firing furnace observed for warping.

No warping of 63Y thermal insulation layers was found.

The honeycomb structured body in which the porous ceramic elements produced in this way are used has properties that enable it to be used as a filter, while the honeycomb structured body in which the ceramic elements produced in the continuous process are used does not show any change in properties structural honeycomb structured body.

In this example, the density of the arrangement of connecting elements per unit area was 4 pcs / m².

(Example 10)

The process is identical to Example 1, except that sheets made of carbon material 164 (FGL-253C (fabric) manufactured by Nippon Carbon Co., Ltd., density 0.16 g / cm were placed on the entire inner surfaces of the heat-insulating layers 13.³), as shown in Figs. 3-5, while the heat-insulating layers 13 and sheets made of carbon material 164 were attached to the fastening-shielding element of the heat-insulating layer 19 using connecting elements 17, used to produce porous ceramic elements, the resulting porous ceramic elements were used to produce a honeycomb structured body. In this case, the above-mentioned firing furnace was used to manufacture porous ceramic elements continuously for 1000 hours, with the heat-insulating layers 13 forming the firing furnace observed for warping.

No warping of thermal insulation layers 13 was found.

The honeycomb structured body in which the porous ceramic elements produced in this way are used has properties that enable it to be used as a filter, while the honeycomb structured body in which the ceramic elements produced in the continuous process are used does not show any change in properties structural honeycomb structured body.

In this example, the density of the arrangement of connecting elements per unit area was 4 pcs / m².

(Reference example 1)

The process is the same as in example 1, except that on the end parts of the inner surfaces of the upper and lower thermal insulation layers forming the baking furnace, no sheets made of carbon material were placed, and the thermal insulation layers 13 were attached to the fastening element shielding the thermal insulation layer 19 using screws 17a and nuts 17b serving as connecting elements, were used to manufacture porous ceramic elements, the resulting porous ceramic elements were used to produce a honeycomb structured body.

In this case, the process of producing porous ceramic elements was carried out continuously for 1000 hours, in the same way as in Example 1, with the thermal insulation layers forming the baking furnace observed for warping after 700 hours and 1000 hours. After 700 hours, no warping of the thermal insulation layers was observed, however, after 1000 hours, warping of the thermal insulation layers was observed.

The honeycomb structured body in which the porous ceramic elements produced in this way are used has the properties enabling it to be used as a filter, while the honeycomb structured body in which the ceramic elements produced in the continuous process are used does not show any change in properties in relation to this first honeycomb structural body.

In this example, the density of the arrangement of connecting elements per unit area was 2 pcs / m².

(Comparative example 1)

The process is identical to that in example 1, except that a conventional baking furnace was used, in which sheets made of carbon material were not placed on the end parts of the inner surface of the upper and lower thermal insulation layer, used to produce porous ceramic elements, and the resulting porous ceramic elements was used to produce a honeycomb structural body.

After 700 hours warping of the heat-insulating layer was observed, and after another 2,000 hours of continuous manufacturing process peeling of the heat-insulating layer occurred.

The above examples clearly indicate that the present invention can be advantageously used in a method for manufacturing a honeycomb structured body made of non-oxide ceramic materials.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic cross-section of one example of a baking furnace according to the first or second aspect of the present invention.

Fig. 2 is a schematic cross-sectional view of a portion of the heat insulating layer forming the firing furnace shown in Fig. 1

Figs. 3-1 to Figs. 3-5 are cross-sectional views showing schematically a configuration including carbon sheets arranged on the heat insulating layers forming the baking furnace.

Fig. 4 is a perspective view of a configuration including reinforcing elements attached to the heat insulating layers forming the firing furnace.

Fig. 5 is a schematic cross-sectional view of another embodiment of the baking furnace of the present invention.

Fig. 6 is a perspective view schematically showing a honeycomb structured body formed using silicon carbide porous ceramic elements.

Fig. 7 (a) is a perspective view schematically showing a porous ceramic member, and Fig. 7 (b) is a cross-sectional view taken along the line AA in Fig. 7 (a).

EXPLANATION OF THE SYMBOLS 8, 35

10, 30 11, 32

Basis

Shaped body Muffle firing furnace

<td colspan="2"> 12</td><td>Heater</td>

<td></td><td>13 (13X, 13Y), 33 (33X, 33Y), 63 (63X, 63Y)</td><td>Thermal insulation layers</td>

<td></td><td>13a, 13b</td><td>Carbon element</td>

<td></td><td>13c</td><td>Ceramic fiber</td>

<td> 5</td><td> 14</td><td>Oven wall</td>

<td></td><td> 15</td><td>Firing handle</td>

<td></td><td> 16</td><td>Sheet made of carbon material</td>

<td></td><td> 17</td><td>Connection element</td>

<td> 10</td><td>17a</td><td>Screw</td>

<td></td><td>17b</td><td>Nut</td>

<td></td><td> 19, 34</td><td>Fixing element - covering the thermal insulation layer</td>

<td></td><td> 21</td><td>Reinforcing element</td>

<td> 15</td><td> 31</td><td>Coil</td>

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EP 1 662 219

Z - 5458/08