JP2001019562A - Sintered flat plate and its burning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a burning method for producing a sintered ceramic plate having high flatness at a low cost without causing defects such as crack. SOLUTION: Flat ceramic plates 1 for burning are placed on setters 5 assembled in the form of shelves with supporting posts 3 and burned to obtain a sintered material. In the above process for burning a flat sintered plate, the post 3 has a thickness thicker than the thickness of the burning object 1 before burning, the upper surface of the burning object 1 is maintained in a state free from contact with the lower surface of the setter 5 above the object during the burning process before almost finishing the burning shrinkage of the object and the thickness of the post is decreased after almost finishing the burning shrinkage of the object by the high-temperature deformation of the post 3 by its own weight to bring the upper surface of the burning object into contact with the lower surface of the setter 5 above the burning object 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a firing method for manufacturing a flat plate sintered body requiring high flatness, such as a flat ceramic substrate used for mounting electronic components.

[0002]

2. Description of the Related Art A flat sintered body of ceramics such as a flat ceramic substrate used for mounting electronic components is required to have high flatness from the viewpoint of apparent strength and the like.
In general, when a flat molded body of ceramics is fired, warpage occurs due to molding distortion, so conventionally, when trying to obtain a flat sintered body requiring high flatness as described above, grinding is performed after firing. The warpage was corrected. Further, as another method, a method is known in which a body to be fired (molded body) is sandwiched between flat plates such as setters and fired to prevent the occurrence of warpage during firing.

[0003]

However, the method of correcting the warpage by performing a grinding process after firing has a problem that the manufacturing cost is increased. In the method in which the object to be fired is sandwiched between setters or the like and firing is performed, since the shrinkage of the object to be fired during firing is hindered by the setter or the like sandwiching the object, cracks occur in the process of densification. And the yield is poor.

The present invention has been made in view of such conventional circumstances, and an object of the present invention is to provide a flat sintered body of ceramics having high flatness to cause defects such as cracks. It is an object of the present invention to provide a sintering method which can be obtained without any cost.

[0005]

Means for Solving the Problems According to the present invention, a flat plate-shaped object to be fired is placed on a setter set up on a shelf via a column and fired by mounting the plate-shaped object to be fired on the setter. A method of firing a sintered body, wherein the support has a thickness larger than the thickness of the fired body before firing, and the firing is performed until the firing shrinkage of the fired body is substantially completed in a firing process. The upper surface of the body and the lower surface of the setter above it are kept in a non-contact state, and after the firing contraction of the fired body is almost finished, the strut itself is deformed at a high temperature by the weight pressure applied thereto to reduce the thickness. Thereby, there is provided a firing method (first firing method) of the flat plate sintered body, wherein the upper surface of the object to be fired is brought into contact with the lower surface of the setter thereabove.

Further, according to the present invention, there is provided a flat sintered body obtained by placing a flat plate-shaped body to be fired made of ceramics on a setter arranged on a shelf via a support and firing the sintered body. A firing method, wherein the pillars have a thickness substantially equal to the thickness of the object to be fired before firing, and start firing shrinkage at a higher temperature than the object to be fired,
In the firing process, from the start of firing contraction of the object to be fired to the end of firing contraction substantially, the delay in firing shrinkage of the columns with respect to the object to be fired causes the upper surface of the object to be fired and the setter thereabove. The lower surface is kept in a non-contact state, and after the firing shrinkage of the fired body is substantially completed, the support pillar shrinks to a thickness equal to or less than the thickness of the fired body, thereby the upper surface of the fired body and its upper surface. A sintering method (second sintering method) for a flat plate sintered body, wherein a lower surface of an upper setter is brought into contact with the lower surface of the setter is provided.

Further, according to the present invention, there is provided a plate-shaped sintered body obtained by placing a plate-shaped body to be fired made of ceramics on a setter arranged on a shelf via a support and firing the sintered body. In a firing method, the support has a thickness larger than the thickness of the object to be fired before firing, and the shrinkage of firing is larger than that of the object to be fired. From the start of shrinkage to the end of firing shrinkage, the column has a thickness greater than that of the object to be fired, so that the upper surface of the object to be fired and the lower surface of the setter thereabove are in a non-contact state. Keeping, after the firing contraction of the fired object is substantially completed, the support pillar shrinks to a thickness equal to or less than the thickness of the fired object, so that the upper surface of the fired object and the lower surface of the setter thereabove. Make contact A method for firing a flat plate sintered body (third firing method) is provided.

Further, according to the present invention, there is provided a flat plate sintered body obtained by any one of the above-described firing methods. In the sintering process by the above-described sintering method, the flat plate sintered body may be subjected to compression deformation in the thickness direction due to high-temperature deformation, and the warpage generated during firing shrinkage may be corrected.

In the present invention, “the firing shrinkage of the object to be fired is almost finished” refers to a state in which the firing shrinkage of the object to be fired reaches 70% of the firing shrinkage in the entire firing process. And

[0010]

First, a first firing method will be described. FIG. 1 shows a state before firing starts in which a fired body (molded body) 1 is placed on a setter 5 assembled on a shelf via a column 3. The object 1 to be fired in the present invention is:
It is a flat molded body obtained by molding a ceramic powder such as silicon nitride, aluminum nitride, or silicon carbide by a molding method such as a press molding method or a doctor blade method. The support 3 is usually a molded body, but may be a sintered body that undergoes a very large high-temperature deformation at the firing temperature of the body 1 to be fired. A plurality of columns 3 are arranged at predetermined intervals near the outer periphery of the setter, and the object 1 to be fired is placed on the setter 5 inside them. When a plurality of objects to be fired are placed on one setter, they are arranged in parallel so that they do not overlap.

Before firing, the column 3 has a thickness T larger than the thickness t of the object 1 to be fired, and the interval between the setters 5 is set so that the upper surface of the object 1 and the lower surface of the setter located above the object 1 do not come into contact with each other. keeping. The components assembled in such a manner are placed in a furnace and fired, and when firing proceeds sufficiently,
The post 3 after sintering does not shrink anymore, but undergoes high-temperature deformation (creep deformation) due to its supporting weight pressure.

In this high-temperature deformation, the columns 3 are usually crushed in the vertical direction (thickness direction) and the thickness thereof is reduced. Therefore, as the high-temperature deformation progresses, the interval between the setters 5 gradually decreases. Eventually, as shown in FIG. 2, the lower surface of the setter 5a supported by the column 3 comes into contact with the upper surface of the fired object 1, and the fired object 1 is brought into contact with the setter 5b on which it is mounted and the upper surface thereof. The state is sandwiched between the setters 5a in contact with each other.

In the first firing method, the upper surface of the fired object 1 and the lower surface of the setter above the fired object 1 are kept in a non-contact state until firing shrinkage (densification) of the fired object 1 is almost completed.
After the firing contraction of the fired body 1 is almost completed, the upper surface of the fired body 1 and the lower surface of the setter 5a above the fired body 1 are brought into contact with each other by the high-temperature deformation of the columns 3 as described above. Therefore, in the first firing method, the load of the setter is not applied until the firing shrinkage is substantially completed, and the firing shrinkage is prevented by the setter as in the above-described conventional method. Does not occur.

After the firing target 1 has substantially finished firing shrinkage, the firing target 1 is exposed to a higher temperature while being sandwiched between the setter 5b on which the firing target 1 is placed and the setter 5a thereabove. By doing so, the warpage generated in the process of firing shrinkage is corrected, and a flat sintered body without warpage is obtained.

The contact timing between the upper surface of the object to be fired and the lower surface of the setter due to the high-temperature deformation of the support is controlled by appropriately setting the material, dimensions, the number of the support, the surface pressure applied by the support, and the like. be able to. In order to adjust the surface pressure of the support to a desired value, a weight may be placed on the setter as needed.

Next, the second firing method will be described. In the second firing method, similarly to the first firing method, the upper surface of the fired object and the lower surface of the setter above the fired object are brought into contact with each other after the fired object has almost finished firing shrinkage, thereby correcting warpage. However, as a method for that, instead of using the high-temperature deformation of the columns, the firing shrinkage of the columns is used.

In other words, in the second firing method, before firing, the post has a thickness substantially equal to the thickness of the object to be fired, and shrinks as in the case of the object to be fired. A material that shrinks at a high temperature and starts firing shrinkage with a time difference with respect to the object to be fired in the firing process is used.

When the support is interposed between the setters and sintering is performed, during firing, the object to be fired first starts firing shrinkage at a lower temperature than the support. Since the columns have not yet started firing shrinkage at the time of the start of firing shrinkage of the fired body, at this stage, the upper surface of the fired body and the lower surface of the setter thereabove are in a non-contact state. As firing proceeds further, the support starts shrinking and shrinking later than the object to be fired, and eventually contracts to a thickness equal to or less than the thickness of the object to be fired.
Then, the shrinkage of the pillars brings the upper surface of the fired body, which has almost completely finished shrinking in advance, into contact with the lower surface of the setter thereabove.

As described above, also in the second firing method, the load of the setter is not applied to the object to be fired from the start of the firing shrinkage to the end of the firing shrinkage. Thus, cracks are not generated by preventing shrinkage during firing. After the fired body has almost finished firing shrinkage, the fired body is exposed to a higher temperature while being sandwiched between the setter on which the fired body is placed and the setter thereabove. The warpage that has occurred during the process is corrected, and a flat sintered body without warpage is obtained.
The temperature at which the support starts firing shrinkage and the firing shrinkage amount are as follows:
It can be controlled by the material of the support, the molding method, and the like.

Subsequently, a third firing method will be described. In the third firing method, similarly to the first firing method, the upper surface of the object to be fired and the lower surface of the setter thereabove are brought into contact with each other after the object to be fired substantially completes shrinkage, thereby correcting warpage. As a method for that, instead of utilizing the high-temperature deformation of the columns, the firing shrinkage of the columns is used in the same manner as in the second firing method. However, while the second firing method utilizes a time difference between firing shrinkage start times of the object to be fired and the pillars, the third firing method includes:
The difference in firing shrinkage between the object to be fired and the column is utilized.

That is, in the third firing method, before firing, the support pillar has a thickness larger than the thickness of the object to be fired and shrinks in firing in the same manner as the object to be fired. Use a material with large shrinkage.

When sintering is performed with such a support interposed between the setters, although the support shrinks more than the object to be fired, its initial thickness is larger than the thickness of the object to be fired. Maintains the interval between the setters so that the thickness of the columns exceeds the thickness of the object to be fired, and the upper surface of the object to be fired does not contact the lower surface of the setter located above the object. As firing proceeds further, firing shrinkage of the struts progresses, and the struts eventually shrink to a thickness equal to or less than the thickness of the object to be fired. Then, due to the contraction of the pillars, the upper surface of the fired object whose firing shrinkage is almost completed is brought into contact with the lower surface of the setter thereabove.

As described above, also in the third firing method, the load of the setter is not applied to the object to be fired from the start of firing shrinkage until the firing shrinkage is substantially completed, and the setter is set as in the above-described conventional method. Thus, cracks are not generated by preventing shrinkage during firing. After the fired body has almost finished firing shrinkage, the fired body is exposed to a higher temperature while being sandwiched between the setter on which the fired body is placed and the setter thereabove. The warpage that has occurred during the process is corrected, and a flat sintered body without warpage is obtained.
In addition, the magnitude of the firing shrinkage of the support can be controlled by the material of the support, the molding method, and the like.

The flat plate sintered body obtained by the first to third firing methods has no warpage or cracks as described above,
High flatness without post-processing.

[0025]

EXAMPLES Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1 92 parts by weight of a commercially available silicon nitride powder having a specific surface area of 11 g / cm ² , 5 parts by weight of a commercially available Y ₂ O ₃ powder, and 3 parts by weight of a commercially available MgO powder were mixed with an aqueous solvent. After mixing and grinding with a wet attritor for 4 hours, an appropriate amount of an organic binder was mixed and dried and granulated with a spray drier to obtain a molding powder. This powder was filled into a molding press, and 15
60mm x 50mm by uniaxial pressing at 0MPa
A silicon nitride molded body (a body to be fired) having a thickness of 0.8 mm was produced. Separately from the above-mentioned molded product, a silicon nitride molded product (support) having a thickness of 10 mm × 10 mm × 1.0 mm was similarly produced by press molding using the same molding powder.

On a commercially available boron nitride (BN) setter (first BN setter) having a diameter of 230 mm, a thickness of 5 mm and a flatness of 40 μm, the above-mentioned 60 mm × 50 mm × 0.
Ten pieces of 8 mm thick compacts were laid in parallel so as not to overlap, and the outer circumference on this BN setter was 10 mm x 10 mm.
Twelve columns having a thickness of 1.0 mm were arranged in parallel on a concentric circle. Next, a second BN setter having the same dimensions as the first BN setter and having one surface processed to a flatness of 40 microns is prepared, and the surface processed to a flatness of 40 microns is directed toward the support and the molded body. Installed above. This second B
A silicon nitride sintered body made of the same silicon nitride powder as that used for the compact was installed as a weight on the N-setter, and the surface pressure of the support was adjusted to 0.016 MPa (160 gf / cm ² ). Set to. At this time, 60 mm × 50 mm × 0.
The 8 mm thick compact did not contact the second BN setter.

Next, the above-mentioned constituent was placed in a carbon furnace, and heated to 1900 ° C. in an atmosphere of 1 MPa of nitrogen and baked for 6 hours. When the component was taken out after cooling, the column was deformed at a high temperature and collapsed in a circular shape, and the second BN setter was in contact with not only the column deformed at a high temperature arranged on the outer periphery but also before firing. It was in contact with the molded body that had not been placed inside.

These compacts are sintered to about 50 mm × 4
It was a flat sintered body having a thickness of 0 mm × 0.7 mm. These one
No cracks were observed in any of the 0 plate sintered bodies, but the plate was deformed so that the four corners slightly protruded, and slightly deformed at a high temperature in the thickness direction. When the flatness of these ten plate sintered bodies was measured, it was 55 microns at the maximum.

Further, these were subjected to sand blasting to have a surface roughness Ra of 0.8 μm and the outer periphery thereof was polished.
The flatness remained almost unchanged after the sandblasting. When the apparent three-point bending strength of these was measured at a span of 30 mm, the average value of ten pieces was 680 MPa.
Met. Table 1 shows the results.

(Comparative Example 1) A test was conducted in the same manner as in Example 1 except that the thickness of the column was 1.2 mm, and the temperature was raised to 1900 ° C and the firing was interrupted at the same time. When the components were taken out after cooling, the pillars were sintered, but there was almost no collapse due to high-temperature deformation, and the second BN setter was in contact with only the pillars arranged on the outer periphery, and the molded body placed inside Had little contact with him. The internal compact was sintered to form a flat plate sintered body. These flat plate sintered bodies had a large warp in appearance, and had a maximum flatness of 200 microns. The average value of the apparent three-point bending strength was 460 MPa. Table 1 shows the results.

(Example 2) As in Example 1, except that the surface pressure of the column was adjusted to 0.010 MPa by adjusting the weight of the silicon nitride sintered body (weight) placed on the second setter. The test was performed. When the component was taken out after cooling, the second BN setter was in contact with not only the high-temperature deformed struts arranged on the outer periphery but also the molded body arranged inside, which was not in contact before firing. The inner compact was sintered into a flat plate sintered body, and no crack was observed in any of these ten flat plate sintered bodies. The maximum flatness of these flat plate sintered bodies was 75 microns. The average value of the apparent three-point bending strength was 658 MPa. Table 1 shows the results.

(Example 3) The thickness of the column was set to 1.2 mm, and the surface pressure of the column was reduced to 0 by adjusting the weight of the silicon nitride sintered body (weight) installed on the second BN setter. .030
The test was performed in the same manner as in Example 1 except that the pressure was changed to MPa. When the components were taken out after cooling, the second BN setter was not only the high-temperature deformed struts arranged on the outer periphery, but also
Before the firing, the molded body disposed inside, which was not in contact, was also in contact. The inner compact was sintered into a flat plate sintered body, and no crack was observed in any of these ten flat plate sintered bodies. The maximum flatness of these flat plate sintered bodies was 40 microns. The average value of the apparent three-point bending strength was 700 MPa. Table 1 shows the results.

(Embodiment 4) Both surfaces of the second BN setter were processed to a flatness of 40 μm, and
10 silicon nitride molded bodies having a thickness of 60 mm x 50 mm x 0.8 mm are further laid in parallel on the upper surface of the setter so as not to overlap with each other, and the outer periphery of the second BN setter is 10 mm x 10 mm.
A third BN setter, in which eight columns each having a thickness of 1.0 mm are arranged in parallel on a concentric circle and having the same dimensions as the first BN setter and having one surface processed to have a flatness of 40 microns, is prepared.
The surface processed to a micron is placed on the support with the support and the molded body facing the support, and the surface pressure of the support between the first and second BN setters is 0.016 MPa, and the pressure between the second and third BN setters. The test was performed in the same manner as in Example 1 except that the surface pressure of the support was adjusted to 0.015 MPa.

When the above-mentioned components were taken out after cooling, the columns between the first and second BN setters and the columns between the second and third BN setters were all deformed at a high temperature and collapsed into a circle, and Both the second and third BN setters were in contact with not only the high-temperature deformed struts arranged on the outer periphery but also the molded bodies arranged inside which were not in contact before firing.
The inner compact was sintered into a flat plate sintered body, and no crack was observed in any of these 20 flat plate sintered bodies. The maximum flatness of these plate sintered bodies was 50 microns. In addition, the three-point bending strength of those obtained by sandblasting them to a surface roughness Ra of 0.8 μm and polishing the outer periphery was measured.
The average value of the sheets was 690 MPa. Table 1 shows the results.

(Comparative Example 2) A second BN setter was directly mounted on ten molded bodies without setting up columns,
The test was performed in the same manner as in Example 1 except that no weight was set on the upper surface of the second BN setter. When the component was taken out after cooling, the molded body was sintered to be a flat plate sintered body, but cracks running vertically in the center were observed in three out of ten sheets. The remaining seven had a flatness of at most 65 microns. The apparent three-point bending strength of these seven sheets was 680 MPa. Table 1 shows the results.

[0037]

[Table 1]

Example 5 95 parts by weight of a commercially available aluminum nitride powder having an average particle size of 0.8 μm and a commercially available Y ₂ O ₃
An appropriate amount of an acrylic organic binder and a plasticizer were added to 5 parts by weight of the powder, and the mixture was ball-milled with a toluene solvent using a monoball to prepare a slurry. Further, the slurry was 0.5 mm thick and 0.1 mm thick by a doctor blade method.
A 7 mm thick green tape was produced. By punching after drying, 60mm x 50mm from 0.5mm thick green tape
A molded body (a body to be fired) having a thickness of 0.5 mm × 0.5 mm was produced. Similarly, 10 mm from a 0.7 mm thick green tape
A molded body (support) having a thickness of 10 mm x 0.7 mm was produced.

A 60 mm × 50 mm × 0.5 mm thick molded body is arranged in parallel on a commercially available BN setter (first BN setter) having a diameter of 230 mm, a thickness of 5 mm and a flatness of 40 μm, without overlapping. 10 sheets on the BN
On the outer periphery of the setter, twelve columns of 10 mm × 10 mm × 0.7 mm were arranged in parallel on a concentric circle. Next, a second BN setter having the same dimensions as the first BN setter and having one surface processed to a flatness of 40 microns is prepared, and the surface processed to a flatness of 40 microns is directed toward the support and the molded body. Installed above. On this second BN setter, a BN sintered body is installed as a weight, and the surface pressure of the column is set to 0.
It was set to be 020 MPa. At this time, 60mm
The molded body having a thickness of 50 mm x 0.5 mm was not in contact with the second BN setter.

Next, the above-mentioned constituent was placed in a carbon furnace, and heated to 1800 ° C. in an atmosphere of nitrogen of 0.1 MPa and baked for 4 hours. When the component was taken out after cooling, the column was deformed at a high temperature and collapsed in a circular shape, and the second BN setter was in contact with not only the column deformed at a high temperature arranged on the outer periphery but also before firing. It was in contact with the molded body that had not been placed inside.

These compacts are sintered to about 45 mm × 3
It was a 5 mm x 0.3 mm thick plate sintered body. These one
No cracks were observed in any of the 0 plate sintered bodies, but the plate was deformed so that the four corners slightly protruded, and slightly deformed at a high temperature in the thickness direction. When the flatness of these ten plate sintered bodies was measured, it was 50 microns at the maximum.

Further, these were subjected to a sandblast treatment to a surface roughness Ra of 0.8 μm, and the outer periphery was polished.
The flatness remained almost unchanged after the sandblasting. When the apparent three-point bending strength was measured for these, the average value of ten sheets was 260 MPa. Table 2 shows the results.

Example 6 A 10 mm × 10 mm × 1.0 mm thickness used in Example 1 was used in place of a 10 mm × 10 mm × 0.7 mm aluminum nitride formed body (post) manufactured by a doctor blade method and punching. And the firing atmosphere was 1 MPa of nitrogen.
A test was conducted in the same manner as in Example 5, except that the temperature was raised to 1900 ° C. and firing was performed for 4 hours. When the component was taken out after cooling, the column was deformed at a high temperature and collapsed into a circle, and the second BN
The setter was in contact with not only the high-temperature deformed struts arranged on the outer periphery, but also the molded bodies arranged inside which were not in contact before firing.

These compacts are sintered to about 45 mm × 3
It is a 5mm x 0.3mm thick plate sintered body.
No crack was observed in any of the zero plate sintered bodies. When the flatness of these ten flat plate sintered bodies was measured, it was at most 75 microns.

Further, these were subjected to sand blast treatment to make the surface roughness Ra 0.8 μm, and the outer periphery was polished.
The flatness remained almost unchanged after the sandblasting. When the apparent three-point bending strength was measured for these, the average value of the ten sheets was 240 MPa. Table 2 shows the results.

Example 7 95 parts by weight of a commercially available aluminum nitride powder having an average particle diameter of 0.8 μm and a commercially available Y ₂ O ₃
5 parts by weight of the powder and an appropriate amount of an acrylic organic binder and a plasticizer were added, and the mixture was ball-milled with a zirconia ball in a toluene solvent for 24 hours to prepare a slurry.
Further, the slurry was added to the slurry by a doctor blade method.
A 7 mm thick green tape was produced. By punching after drying, from this green tape 60 mm x 50 mm x 0.7
A molded body (a body to be fired) having a thickness of mm was produced.

Similarly, 95 parts by weight of a commercially available aluminum nitride powder having an average particle size of 0.8 μm and a commercially available Y
_After adding an appropriate amount of an acrylic organic binder and a plasticizer to 5 parts by weight of ₂ O ₃ powder, a ball mill was mixed with a toluene solvent using a monoball to prepare a slurry. Further, a green tape having a thickness of 0.7 mm was prepared from the slurry by a doctor blade method. By punching after drying, a molded product (support) of 10 mm × 10 mm × 0.7 mm was produced from the green tape.

From the firing test conducted in advance, the former zirconia ball pulverized product was densified at 1650 ° C.
It has been found that the latter pulverized monoball does not densify unless it is at 1700 ° C. In other words, the former has the earlier firing shrinkage timing. This is presumed to be due to the fact that the aluminum nitride powder becomes finer by pulverizing with zirconia balls and that a small amount of zirconia mixes into the aluminum nitride powder to act as a sintering aid.

A 60 mm × 50 mm × 0.7 mm thick molded body is arranged in parallel on a commercially available BN setter (first BN setter) having a diameter of 230 mm, a thickness of 5 mm and a flatness of 40 μm, without overlapping. 10 sheets on the BN
On the outer periphery of the setter, twelve columns of 10 mm × 10 mm × 0.7 mm were arranged in parallel on a concentric circle. Next, a second BN setter having the same dimensions as the BN setter and having one surface processed to a flatness of 40 microns is prepared, and the surface processed to a flatness of 40 microns is placed on the support with the surface processed to the support and the molded body side. did. At this time, the second BN setter was in contact with both the formed body and the support, but the surface pressure of the support was 0.020MP, assuming that the load was applied only to the support.
A BN sintered body was set as a weight on the second BN setter so as to be a.

Next, the above-mentioned component was placed in a carbon furnace, and heated to 1800 ° C. in an atmosphere of 0.1 MPa of nitrogen and baked for 4 hours. When the component was taken out after cooling, both the support and the internal compact had the same thickness, and both were in contact with the second BN setter.

The molded body is sintered to about 45 mm × 35 mm ×
It was a 0.5 mm thick flat plate sintered body. No cracks were observed in any of these ten flat plate sintered bodies.
When the flatness of these ten plate sintered bodies was measured,
The maximum was 45 microns.

Further, these were subjected to sand blast treatment to make the surface roughness Ra 0.8 μm, and the outer periphery was polished.
The flatness remained almost unchanged after the sandblasting. When the apparent three-point bending strength was measured for these, the average value of ten sheets was 320 MPa. Table 2 shows the results.

(Comparative Example 3) A molded product having a thickness of 60 mm x 50 mm x 0.7 mm and a support having a size of 10 mm x 10 mm x 0.7 mm were produced by punching a green tape made from a slurry mixed with a ball mill using a monoball. Example 7
The test was performed in the same manner as in the above. When the component was taken out after cooling, both the support and the internal compact had the same thickness, and both were in contact with the second BN setter. Although the formed body was sintered to be a flat plate sintered body, cracks running vertically in the center were observed in four out of ten sheets. Remaining 6
The flatness of the sheet was at most 50 microns. The apparent three-point bending strength of these six sheets was 310 MPa. Table 2 shows the results.

(Comparative Example 4) A test was performed in the same manner as in Example 7 except that the second BN setter was directly mounted on the ten molded bodies without setting the columns. When the component was taken out after cooling, the molded body was sintered to be a flat plate sintered body, but cracks running vertically in the center were observed in three out of ten sheets. The flatness of the remaining seven sheets was at most 55 microns. The apparent three-point bending strength of these seven sheets was 320 MPa. Table 2 shows the results.

[0055]

[Table 2]

Example 8 91 parts by weight of a commercially available silicon carbide powder having a specific surface area of 15 g / cm ² , 5 parts by weight of a commercially available Al ₂ O ₃ powder, and 4 parts by weight of a commercially available Y ₂ O ₃ powder After mixing and grinding for 2 hours with a water solvent wet attritor, an appropriate amount of an organic binder was mixed and dried and granulated with a spray dryer to obtain a molding powder. This powder is filled into a molding press, and
Outer diameter 120mm by uniaxial pressing at 50MPa
X A 30 mm x 2 mm thick perforated disk-shaped molded product (subject to be fired) was prepared. Separately from the above-mentioned molded body, a silicon carbide molded body (support) having a thickness of 10 mm × 10 mm × 3 mm was similarly produced by press molding using the same molding powder.

On a commercially available BN setter (first BN setter) having a diameter of 230 mm, a thickness of 5 mm and a flatness of 40 μm, a perforated disk-shaped molded article having an outer diameter of 120 mm × inner diameter of 30 mm × 2 mm And 12 columns of the 10 mm × 10 mm × 3 mm thickness were arranged in a concentric circle on the outer periphery of the BN setter. Next, a second B having the same dimensions as the BN setter and having one surface processed to a flatness of 40 microns.
An N setter was prepared and placed on the support with the surface processed to a flatness of 40 microns facing the support and the molded body.
On this second BN setter, a compact formed from the same silicon carbide powder as that used for the compact was installed as a weight, and the surface pressure of the support was set to 0.040 MPa. At this time, the perforated disk-shaped molded product was not in contact with the second BN setter.

Next, the above-mentioned constituent was placed in a carbon furnace, and heated to 2000 ° C. in an atmosphere of 1 MPa of argon and fired for 5 hours. When the component was taken out after cooling, the column was deformed at a high temperature and collapsed in a circular shape, and the second BN setter was in contact with not only the column deformed at a high temperature arranged on the outer periphery but also before firing. It was in contact with the molded body that had not been placed inside.

This compact was sintered to form a perforated disk-shaped sintered body having an outer diameter of 97 mm × an inner diameter of 19 mm × 1.5 mm. Although no cracks were observed in the perforated disk-shaped sintered body, the sintered body was slightly deformed in the inner and outer radial directions, and slightly deformed in the thickness direction at a high temperature. The flatness of the perforated disc-shaped flat plate was measured and found to be 70 microns.

Further, this was subjected to sand blasting to make the surface roughness Ra 0.8 μm, and the outer periphery and the inner periphery were polished. The flatness remained almost unchanged after the sandblasting. 40mm × 4mm ×
A test piece having a thickness of 1.4 mm was cut out, and the apparent three-point bending strength was measured. The average value of the ten pieces was 420 MPa. Table 3 shows the results.

(Comparative Example 5) A test was conducted in the same manner as in Example 8 except that the column was not provided, and the second BN setter was directly mounted on the perforated disk-shaped molded product. When the component was taken out after cooling, the compact was sintered to form a disc-shaped sintered body with holes, but cracks running so as to bisect the sintered body were observed. Table 3 shows the results.

Example 9 A commercially available silicon carbide spray-dried granulated powder containing an appropriate amount of boron and carbon as a sintering aid and containing 10% by weight of an organic binder was used as a molding powder. The temperature was raised to 2400 ° C and 5
The test was performed in the same manner as in Example 8, except that the firing was performed for an hour. When the component was taken out after cooling, the second BN setter was in contact with not only the high-temperature deformed struts arranged on the outer periphery but also the molded body arranged inside, which was not in contact before firing. The compact was sintered to form a disc-shaped sintered body with holes, and the flatness was 75 microns. Further, a test piece was cut out from this perforated disc-shaped sintered body in the same manner as in Example 8, and the apparent three-point bending strength was measured. The average value of the ten pieces was 410 MPa. Table 3 shows the results.

Example 10 Commercially available silicon carbide spray-dried granulated powder containing silicon carbide powder having a specific surface area of 15 g / cm ^2, an appropriate amount of boron and carbon as a sintering aid, and containing 10% by weight of an organic binder. Was used as a molding powder. This powder is filled in a molding press, and is uniaxially pressed at 100 MPa, and then cold isostatically molded (CIP) at 680 MPa to obtain an outer diameter of 115 mm and an inner diameter of 2 mm.
A 7 mm x 2 mm thick perforated disk-shaped molded body (a body to be fired) was produced. Separately from the above-mentioned molded body, the same molding powder was uniaxially pressed at 100 MPa, and the thickness was adjusted and processed to produce a silicon carbide molded body (support) having a thickness of 10 mm × 10 mm × 2.05 mm.

From the firing test conducted in advance, the density of the former CIP molded article cold-statically molded at 680 MPa is 1.87 g / cm ³ ,
After firing at 2300 ° C. for 5 hours, the linear shrinkage is 16.4%.
Has been found to cause firing shrinkage. In addition, the latter 1
The compact density of the uniaxial press-formed body which was uniaxially press-formed at 00 MPa was 1.63 g / cm ³ , and it was found that firing at 2300 ° C. for 5 hours caused firing shrinkage with a linear shrinkage of 20.0%. .

On a commercially available BN setter (first BN setter) having a diameter of 230 mm, a thickness of 5 mm and a flatness of 40 μm, a perforated disk-shaped molded body having an outer diameter of 115 mm × inner diameter of 27 mm × 2 mm On the BN setter and 12 columns of 10 mm x 10 mm x 2.05 mm thick
They were arranged on concentric circles in parallel. Next, a second BN setter having the same dimensions as the BN setter and having one surface processed to a flatness of 40 microns is prepared, and the surface processed to a flatness of 40 microns is placed on the support with the surface processed to the support and the molded body side. did. On this second BN setter, a compact formed from the same silicon carbide powder as that used for the compact was installed as a weight, and the surface pressure of the support was set to 0.040 MPa. At this time, the perforated disk-shaped molded product was not in contact with the second BN setter.

Next, the above-mentioned constituent was placed in a carbon furnace, and heated to 2300 ° C. in an atmosphere of 1 MPa of argon and baked for 5 hours. When the component was taken out after cooling, the column was sintered, but almost no high-temperature deformation was observed. In addition, the second BN setter was in contact with the compact disposed inside which was not in contact before firing.

This compact was sintered to form a perforated disc-shaped sintered body having an outer diameter of 95 mm, an inner diameter of 17 mm and a thickness of 1.5 mm. Although no cracks were observed in the perforated disk-shaped sintered body, the sintered body was slightly deformed in the inner and outer radial directions, and slightly deformed in the thickness direction at a high temperature. The flatness of the perforated disc-shaped flat plate was measured and found to be 65 microns.

Further, this was subjected to sand blasting to make the surface roughness Ra 0.8 μm, and the outer and inner circumferences were polished. The flatness remained almost unchanged after the sandblasting. 40mm × 4mm ×
A test piece having a thickness of 1.4 mm was cut out, and the apparent three-point bending strength was measured. The average value of the ten pieces was 405 MPa. Table 3 shows the results.

[0069]

[Table 3]

[0070]

As described above, in the firing method of the present invention, the setter does not come into contact with the upper surface of the object to be fired until the firing shrinkage of the object to be fired is substantially completed after the shrinkage of the object to be fired. That is, since a load is not applied to the object to be fired, and the shrinkage of the object to be fired is almost completed, the warpage is corrected by pinching the upper and lower setters. Without
A flat plate sintered body without warpage or cracks can be obtained at low cost. Moreover, the flat plate sintered body obtained by the method of the present invention has no warpage or cracks as described above, and has a high flatness without post-processing.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a state before starting firing, in which an object to be fired (a molded body) is placed on a setter assembled on a shelf via a support.

FIG. 2 is an explanatory view showing a state in which a body to be fired is sandwiched by setters.

[Explanation of symbols]

 Reference numeral 1 denotes an object to be fired, 3 a support, and 5 a setter.

Claims (5)

[Claims] 1. A method for firing a flat plate sintered body, wherein a sintered body is obtained by placing a flat plate-shaped body to be fired made of ceramics on a setter arranged on a shelf via a column and firing the same. The support has a thickness greater than the thickness of the object to be fired before firing, and the upper surface of the object to be fired and the lower surface of the setter thereabove until firing shrinkage of the object to be fired is substantially completed in the firing process. Is kept in a non-contact state, and after the firing contraction of the fired body is almost completed, the strut itself is deformed at a high temperature by the weight pressure applied thereto to reduce its thickness, thereby reducing the thickness of the upper surface of the fired body. A method for firing a flat plate sintered body, comprising bringing a lower surface of a setter above the setter into a contact state. 2. A method for firing a flat sintered body, wherein a flat sintered body made of ceramics is placed on a setter set up on a shelf via a column and fired to obtain a sintered body, The support has a thickness substantially equal to the thickness of the object to be fired before firing, and starts firing shrinkage at a higher temperature than the object to be fired. From the start until the firing shrinkage is almost completed, the upper surface of the firing object and the lower surface of the setter thereabove are kept in a non-contact state due to the delay in firing shrinkage of the support with respect to the firing object. After the firing shrinkage of the body is substantially completed, the support pillar shrinks to a thickness equal to or less than the thickness of the fired body, thereby bringing the upper surface of the fired body into contact with the lower surface of the setter thereabove. It is characterized by Method for firing flat sintered body that. 3. A method for firing a flat sintered body, wherein a flat sintered body made of ceramics is placed on a setter arranged on a shelf via a support and fired to obtain a sintered body, The pillar has a thickness greater than the thickness of the object to be fired before firing, and has a larger firing shrinkage than the object to be fired, and after the firing shrinkage of the object to be fired starts in the firing process. Until the firing shrinkage is almost completed, the pillars have a thickness greater than that of the fired body, so that the upper surface of the fired body and the lower surface of the setter thereabove are kept in a non-contact state. After the firing shrinkage is substantially completed, by firing the shrinkage to a thickness equal to or less than the thickness of the fired body, the upper surface of the fired body is brought into contact with the lower surface of the setter thereabove. Characteristic flat plate A firing method of the sintered body. 4. A flat plate sintered body obtained by the firing method according to any one of claims 1 to 3. 5. The flat plate sintered body according to claim 4, wherein compression deformation is applied in a thickness direction by high-temperature deformation.