Method for filling ceramic molded body and method for producing ceramic sintered body

Abstract

According to an embodiment, a method for filling a heat treatment container with a plurality of ceramic molded bodies having a curved surface part includes a placing step, a moving step, and a filling step. In the placing step, a plurality of ceramic molded bodies are placed on a filling device. In the moving step, the filling device on which the plurality of ceramic molded bodies are placed is moved over the heat treatment container until the bottom surface of the filling device reaches a height of 100 mm or less with reference to the bottom surface of the heat treatment container. In the filling step, the heat treatment container is filled with the plurality of ceramic molded bodies from the filling device.

Description

Method for filling ceramic molded body and method for manufacturing ceramic sintered body

[0001] The embodiments described below generally relate to a method for filling a ceramic compact and a method for producing a ceramic sintered body.

[0002] Ceramic sintered bodies are used in wear-resistant members and substrates for semiconductor devices. Examples of wear-resistant members include bearing balls, rollers, and engine parts. Examples of ceramic sintered bodies include silicon nitride sintered bodies, aluminum nitride sintered bodies, aluminum oxide sintered bodies, and zirconium oxide sintered bodies. For example, Japanese Patent No. 7402177 (Patent Document 1) discloses a wear-resistant member made of a silicon nitride sintered body. The silicon nitride sintered body of Patent Document 1 has excellent mechanical strength and wear resistance.

[0003] A ceramic sintered body is manufactured by mixing ceramic powder, which serves as the base material, with sintering aid powder, molding, degreasing, and sintering. The degreasing process is carried out at approximately 400°C to 800°C. The sintering process is carried out at approximately 1500°C to 2000°C. In this way, the degreasing and sintering processes are heat treatment processes that involve heating.

[0004] In the heat treatment process, the ceramic formed body (including the degreased ceramic body) is placed in a heat treatment container. The use of a heat treatment container makes it possible to treat a large amount of ceramic formed bodies. For example, in Japanese Patent Laid-Open No. 2005-226101 (Patent Document 2), ceramic balls are laid in a heat treatment container and the ceramic formed body is placed therein. In the heat treatment container as in Patent Document 2, an operator had to manually fill the ceramic formed body. For this reason, this method was not necessarily suitable for mass production.

[0005] Japanese Patent No. 7402177 Japanese Patent Laid-Open No. 2005-226101

[0006] Conventionally, the method of filling a heat treatment vessel with ceramic molded bodies has mainly been manual work by an operator, but manual work has the drawback of damaging the ceramic molded bodies while filling the heat treatment vessel.

[0007] One of the problems to be solved by the embodiments is to provide a method for filling a ceramic molded body and a method for manufacturing a ceramic sintered body that can improve the yield and mass productivity of the sintered body.

[0008] According to an embodiment, a method for filling a heat treatment vessel with a plurality of ceramic molded bodies having curved surfaces includes a placing step, a moving step, and a filling step. In the placing step, the plurality of ceramic molded bodies are placed on a filling device. In the moving step, the filling device on which the plurality of ceramic molded bodies are placed is moved above the heat treatment vessel until the bottom of the filling device is at a height of 100 mm or less relative to the bottom of the heat treatment vessel. In the filling step, the plurality of ceramic molded bodies are filled from the filling device into the heat treatment vessel.

[0009] 1 is a side view showing an example of a ceramic molded body having a curved surface portion, a filling device, and a heat treatment container used in the method for filling a ceramic molded body according to an embodiment; FIG. 2 is an external view showing a first example of a ceramic molded body having a curved surface portion used in the method for filling a ceramic molded body according to an embodiment; FIG. 3 is an external view showing a second example of a ceramic molded body having a curved surface portion used in the method for filling a ceramic molded body according to an embodiment; FIG. 4 is an external perspective view showing a third example of a ceramic molded body having a curved surface portion used in the method for filling a ceramic molded body according to an embodiment; FIG. 5 is a side view showing an example of a ceramic molded body having a curved surface portion, a filling device, a belt conveyor, and a filling device used in the method for filling a ceramic molded body according to an embodiment; FIG. 6 is a side view showing an example of an operation example of the filling device used in the method for filling a ceramic molded body according to an embodiment; FIG. 7 is a side view showing an example of an operation example of the filling device used in the method for filling a ceramic molded body according to an embodiment; FIG. 8 is a diagram showing an example of a process flow included in a method for producing a ceramic sintered body according to an embodiment; Embodiment

[0010] According to an embodiment, a method for filling a heat treatment vessel with a plurality of ceramic molded bodies having curved surfaces includes a placing step, a moving step, and a filling step. In the placing step, the plurality of ceramic molded bodies are placed on a filling device. In the moving step, the filling device on which the plurality of ceramic molded bodies are placed is moved above the heat treatment vessel until the bottom of the filling device is at a height of 100 mm or less relative to the bottom of the heat treatment vessel. In the filling step, the plurality of ceramic molded bodies are filled from the filling device into the heat treatment vessel.

[0011] FIG. 1 shows an example of a ceramic molded body having a curved surface and a filling device used in a ceramic molded body filling method according to an embodiment. In the figure, reference numeral 1 denotes a ceramic molded body having a curved surface (hereinafter simply referred to as "molded body"); reference numeral 2 denotes a heat treatment vessel; reference numeral 3 denotes a filling device (e.g., a mobile crane or a transport gondola); and reference numeral 4 denotes the height of the bottom of the filling device 3 relative to the bottom of the heat treatment vessel 2 (e.g., the inner bottom wall). FIG. 1(A) shows the state of the filling device 3 with multiple molded bodies 1 placed thereon; FIG. 1(B) shows the state of the filling device 3 immediately before filling with the multiple molded bodies 1; and FIG. 1(C) shows the state of the filling device 3 immediately after filling with the multiple molded bodies 1. In addition, FIGS. 2 to 4 each show an example of the molded body 1.

[0012] The molded body 1 is shown having a curved portion on all or part of its surface. FIG. 2 illustrates a ball-shaped molded body 1A as an example of a molded body 1 having a curved portion on its entire surface. FIG. 3 illustrates a molded body 1B having a ring-shaped band portion on the circumference of a sphere as an example of a molded body 1 having a curved portion on part of its surface. FIG. 4 illustrates a cylindrical molded body 1C as an example of a molded body 1 having a curved surface b on part of its surface. The ball-shaped molded body 1A shown in FIG. 2 is used as a bearing ball, media, check ball, etc. after sintering and polishing processes. The band-shaped molded body 1B shown in FIG. 3 is used as a base sphere after sintering processes. The base sphere is the one before being polished into a bearing ball, etc. The cylindrical molded body 1C shown in FIG. 4 is used as a roller, roller, etc. In addition to the shapes shown in FIGS. 2 to 4, examples of the molded body 1 include an ellipsoid, a cone, a solid having a partial sector shape, and a solid having a partial square shape.

[0013] First, a loading step ST3 (shown in FIG. 8) is performed in which multiple molded bodies 1 are loaded onto the filling device 3. Multiple molded bodies 1 are loaded onto the filling device 3. The number of molded bodies 1 loaded onto the filling device 3 may be two or more. If only one molded body 1 is loaded onto the filling device 3, the efficiency of loading the molded bodies 1 into the heat treatment container 2 decreases. The upper limit for the number of molded bodies 1 that can be loaded onto the filling device 3 is the maximum number that can be loaded into the storage section within the filling device 3. The state of the filling device 3 with multiple molded bodies 1 loaded thereon is shown in FIG. 1(A).

[0014] The placing step ST3 is preferably performed using a belt conveyor. An example of the placing step is shown in Figure 5. In the figure, reference numeral 1 denotes a compact, reference numeral 3 denotes a filling device, reference numeral 5 denotes a storage container, and reference numeral 6 denotes a belt conveyor.

[0015] A storage container 5 stores a plurality of molded bodies 1 before heat treatment. The plurality of molded bodies 1 stored in the container 5 are sequentially placed on one end of a belt conveyor 6 either manually or automatically (for example, by a gripping arm). The belt conveyor 6 is used to transport the plurality of molded bodies 1 placed on one end of the belt conveyor 6 sequentially to the other end of the belt conveyor 6. The plurality of molded bodies 1 spilled from the other end of the belt conveyor 6 are sequentially placed on a filling device 3 installed on the other end of the belt conveyor 6.

[0016] 5, the upper part of the filling device 3 is the inlet for the compacts 1, but this is not limiting. Furthermore, the compacts 1 are dropped and placed on the filling device 3, but since the compacts 1 have a curved surface, damage to the compacts 1 due to the impact of the drop can be suppressed. Furthermore, by using a belt conveyor 6, the placing step ST3 can be automated.

[0017] After the placing step ST3, a moving step ST4 (shown in FIG. 8 ) is performed in which the filling device 3 on which the plurality of compacts 1 are placed is moved so that the height 4 is 100 mm or less. In the moving step ST4, the filling device 3 on which the plurality of compacts 1 are placed is first moved horizontally to above the heat treatment vessel 2. The heat treatment vessel 2 is a vessel used in the heat treatment process (at least one of the degreasing process and the sintering process). Therefore, the heat treatment vessel 2 is required to be heat resistant. Examples of materials for the heat treatment vessel 2 include carbon, boron nitride, alumina, and silicon nitride. The heat treatment vessel 2 has a bottom portion and sidewall portions. The height of the sidewall portions is optional. In other words, the heat treatment vessel 2 is not a plate material.

[0018] In the moving step ST4, after the horizontal movement, the filling device 3 is lowered until the height 4 is 100 mm or less. The state of the filling device 3 after the horizontal movement and lowering is shown in FIG. 1(B). The bottom surface of the heat treatment vessel 2 refers to the bottom surface of the inner surface of the heat treatment vessel 2. If this bottom surface is uneven, the deepest position is considered to be the bottom surface of the heat treatment vessel 2. The bottom surface of the filling device 3 is also the lowest part on the outside of the filling device 3. The height 4 is the vertical distance from the inner bottom wall of the heat treatment vessel 2 to the bottom surface of the filling device 3.

[0019] The lower limit of the height 4 is not particularly limited and may be 0 mm (the bottom of the heat treatment vessel 2 and the bottom of the filling device 3 are in contact). Furthermore, since the molded body 1 is relatively resistant to the impact of being dropped, the lower limit of the height 4 may be set to 10 mm or more. Filling the heat treatment vessel 2 involves the dropping of the molded body 1, which can improve the filling speed. Therefore, the height 4 is preferably within a range of 0 mm to 100 mm, and more preferably within a range of 10 mm to 50 mm.

[0020] In the moving step ST4, the step of horizontally moving the filling device 3 to above the heat treatment vessel 2 and the step of lowering the filling device 3 until the height 4 is 100 mm or less may be performed in one step. Furthermore, if the height 4 is 100 mm or less when the filling device 3 is moved above the heat treatment vessel 2, the filling device 3 may or may not be lowered continuously.

[0021] After the moving step ST4, a filling step ST5 (shown in FIG. 8 ) is performed in which multiple molded bodies 1 are filled into the heat treatment vessel 2 from the filling device 3. For example, in the moving step ST4, the bottom of the filling device 3 is opened and multiple molded bodies 1 are filled into the heat treatment vessel 2. The state of the filling device 3 after filling is shown in FIG. 1(C). It is important to set the height 4 to 100 mm or less. If the height 4 is greater than 100 mm, the molded bodies 1 may be damaged by the impact of dropping the filling device 3 when the bottom of the filling device 3 is opened and the molded bodies 1 are filled into the heat treatment vessel 2. For this reason, it is preferable that the height 4 be 100 mm or less, and even 50 mm or less. Since the molded bodies 1 have curved surfaces, damage due to the impact of dropping can be suppressed. In other words, the embodiment can be said to be a filling method suitable for molded bodies 1.

[0022] In the filling step ST5, the filling device 3 may be raised so that the difference between the stack height of the filled compacts 1 (the highest part of the compacts 1) and the height 4 of the bottom surface of the filling device 3 is within a predetermined range. In this case, the filling device 3 is raised in stages as the stack height of the compacts 1 filled into the heat treatment vessel 2 increases. In addition, in FIG. 1(B), the bottom surface of the filling device 3 is lowered into the heat treatment vessel 2, but the bottom surface of the filling device 3 may be above the heat treatment vessel 2 as long as the height 4 is 100 mm or less.

[0023] 6 shows an example of changing the height of the filling device 3. In the figure, reference numeral 1 denotes the compacts, reference numeral 2 denotes the heat treatment container, reference numeral 3 denotes the filling device, reference numeral 4 denotes the height from the bottom of the heat treatment container 2 to the bottom of the filling device 3, reference numeral G denotes the stack height of the compacts 1 based on the inner bottom wall of the heat treatment container 2, and reference numeral J denotes the container height of the heat treatment container 2. As the compacts 1 are filled into the heat treatment container 2, there is a possibility that the stacked compacts 1 will come into contact with the filling device 3. Therefore, it is preferable to raise the filling device 3 according to the degree to which the compacts 1 have piled up so that the filling device 3 does not come into contact with the stacked compacts 1.

[0024] 6 shows the filling device 3 in a raised position. Note that the moving direction of the filling device 3 is not limited to directly upward, and may be horizontal or diagonal, as long as it does not come into contact with the stacked compacts 1 and the heat treatment container 2. The filling device 3 is controlled so that the difference (distance) between the stacked height G of the compacts 1 and the height 4 of the filling device 3 is within a certain range. The stacked height G of the compacts 1 is, for example, the height of the highest part of the multiple compacts 1 that have been filled.

[0025] Furthermore, it is preferable that the stack height G of the molded bodies 1 filled in the heat treatment vessel 2 be 80% or more of the vessel height J of the heat treatment vessel 2. The vessel height J of the heat treatment vessel 2 is the height of the side wall. If the height of the side wall is uneven, the lowest part is used as the reference. By filling the molded bodies 1 until the stack height G of the molded bodies 1 is 80% or more of the vessel height J of the heat treatment vessel 2, the number of molded bodies 1 to be heat treated at one time can be increased. This improves the mass productivity of ceramic sintered bodies. Furthermore, by controlling the number of molded bodies 1 placed on the filling device 3, the amount of molded bodies 1 filled into the heat treatment vessel can be stabilized.

[0026] Furthermore, although there is no particular upper limit to the stack height G of the compacts 1, it is preferably 100% or less of the container height J of the heat treatment container 2. By setting the stack height G of the compacts 1 to 100% or less of the container height J, multiple heat treatment containers 2 filled with compacts 1 can be stacked without breaking the compacts 1. By stacking multiple heat treatment containers 2, the throughput in the debinding step ST6 and the sintering step ST7 (shown in FIG. 8 ) can be increased. For this reason, it is preferable to set the stack height G of the compacts 1 in the heat treatment container 2 within a range of 80% to 100% of the container height J, and further within a range of 82% to 98%.

[0027] Furthermore, when the stack height G of the compacts 1 exceeds the height J of the heat treatment vessel 2, it is preferable to level the stack height G. An example of a process for leveling the stack height of the stacked compacts 1 is shown in Figure 7. In the figure, reference numeral 1 denotes the compacts, reference numeral 2 denotes the heat treatment vessel, and reference numeral 7 denotes a leveling jig.

[0028] When multiple compacts 1 are stacked inside the heat treatment container 2, the stack height G of the compacts 1 may exceed the container height J of the heat treatment container 2 (left side of FIG. 7). In this case, by using a leveling jig 7 to level the height of the compacts 1 that protrude beyond the container height J, the stack height G of the compacts 1 can be made 100% or less of the container height J (right side of FIG. 7). In FIG. 7, the leveling jig 7 is moved from right to left to level the compacts 1 that protrude above the heat treatment container 2. The direction in which the leveling jig 7 is moved is arbitrary.

[0029] Although a plate-shaped leveling jig 7 has been exemplified, the leveling jig 7 is not limited to this. The leveling jig 7 may have various shapes, such as a rod shape or a mesh shape. Furthermore, by controlling the number of compacts 1 placed on the filling device 3, the efficiency of controlling the stack height G of the compacts 1 using the leveling jig 7 can be improved. Furthermore, it is also possible to level a plurality of compacts 1 by vibrating the heat treatment container 2 from side to side. Furthermore, the use of the leveling jig 7 and the vibration of the heat treatment container 2 may be combined.

[0030] The method for filling the compact 1 according to the embodiment can be used in a method for manufacturing a ceramic sintered body (hereinafter simply referred to as a "sintered body") by performing a heat treatment process on the compact 1. Fig. 8 shows an example of a process flow included in the method for manufacturing a ceramic sintered body.

[0031] The method for manufacturing a sintered body mainly includes a raw material powder mixing step ST1, a molding step ST2, a placing step ST3, a moving step ST4, a filling step ST5, a debinding step ST6, and a sintering step ST7. The heat treatment step for the compact 1 includes at least one of the debinding step ST6 and the sintering step ST7. Note that in FIG. 8 , the placing step ST3, the moving step ST4, and the filling step ST5 are performed before the debinding step ST6, but this is not a limitation. For example, the placing step ST3, the moving step ST4, and the filling step ST5 may be performed only before the sintering step ST7. In this case, the placing step ST3, the moving step ST4, and the filling step ST5 are performed using the debound body after the debinding step ST6. Furthermore, for example, the placing step ST3, the moving step ST4, and the filling step ST5 may be performed before the debinding step ST6 and before the sintering step ST7, respectively.

[0032] The raw material powder mixing step ST1 is a step of mixing a ceramic powder that will serve as a base material with a sintering aid powder. When the total of the ceramic powder that will serve as a base material and the sintering aid powder is taken as 100 mass%, the ceramic powder that will serve as a base material is the component that is contained in the largest amount by mass%. The ceramic powder that will serve as a base material may be one selected from silicon nitride, sialon, aluminum nitride, aluminum oxide, and zirconium oxide. Silicon powder may also be used as the ceramic powder that will serve as a base material. A silicon nitride sintered body can be obtained by reactive sintering of the silicon powder.

[0033] Various sintering aid powders can be used. Examples of sintering aids include one or more selected from rare earth element compounds, aluminum compounds, magnesium compounds, titanium compounds, zirconium compounds, hafnium compounds, tungsten compounds, molybdenum compounds, silicon carbide, boron nitride, etc. The amount of sintering aid added is preferably within a range of 1% by mass to 20% by mass.

[0034] In the mixing step ST1, in which the base ceramic powder and the sintering aid powder are mixed, it is preferable to use a pulverizer such as a ball mill or a bead mill. If necessary, an organic binder or a solvent, or both, are added. By mixing the base ceramic powder and the sintering aid powder, a raw material mixed powder can be obtained. By adding an organic binder or a solvent, a raw material mixed powder slurry can be obtained.

[0035] The molding step ST2 is a step of molding the raw material mixed powder (including raw material mixed powder slurry). The molding step ST2 may include a mold molding method, a doctor blade method, an injection molding method, a slip casting method, a rolling granulation method, a cold isostatic pressing method (CIP), etc. In the molding step ST2, a combination of these methods may be used. To obtain the molded body 1, it is preferable to employ a mold molding method, a slip casting method, a rolling granulation method, or a cold isostatic pressing method. In the mold molding method, it is preferable to use a mold having a curved surface. In the slip casting method, it is preferable to use a mold having a curved surface. In the rolling granulation method, a ball-shaped molded body 1 (shown in FIG. 2) can be produced.

[0036] CIP is preferably performed using a rubber mold having curved surfaces. Furthermore, CIP can be performed on a pre-fabricated molded body 1 to densify the molded body 1 and obtain a CIP body (an example of molded body 1). Alternatively, the molded body 1 may be processed to form curved surfaces. The obtained molded body may be subjected to a drying process, if necessary.

[0037] As described above, the placing step ST3, the moving step ST4, and the filling step ST5 are performed using a molded body 1, for example, a CIP body. Note that one heat treatment vessel 2 may be filled with the molded body 1 by one filling device 3 only once, or one filling device 3 may be repeatedly filled with the molded body 1 multiple times, or multiple filling devices 3 may be repeatedly filled with the molded body 1 as many times as there are filling devices 3. When one heat treatment vessel 2 is filled with the molded bodies 1 multiple times, the process may switch to filling the next heat treatment vessel 2 when the stack height G of the molded bodies 1 or the weight of the heat treatment vessel 2 including the molded bodies 1 exceeds a threshold value.

[0038] The degreasing step ST6 is a step of subjecting the compact 1, for example, a CIP compact, to a heat treatment at 400° C. to 800° C. After filling a plurality of compacts 1 into the heat treatment container 2 in the filling step ST5, the degreasing step ST6 is performed on the plurality of compacts 1, thereby removing the organic binder and solvent from the compacts 1. By performing the degreasing step ST6, a degreased body (an example of the compact 1) can be obtained.

[0039] The sintering step ST7 is a step of subjecting the degreased body to a heat treatment at a temperature of 1500°C to 2000°C. A ceramic sintered body can be obtained by performing the sintering step ST7. The sintering step ST7 may include atmospheric sintering, pressure sintering, hot pressing, hot isostatic pressing (HIP), reactive sintering, or the like. A combination of these methods may be performed in the sintering step ST7.

[0040] In the method for producing a sintered body according to the embodiment, the heat treatment step for the compact 1 includes at least one of a debinding step ST6 and a sintering step ST7. In other words, the heat treatment for the compact 1 includes not only the heat treatment for the CIP compact as the compact 1, but also the heat treatment for the debound compact as the compact 1.

[0041] As described above, by the method for filling the compacts 1 according to the embodiment, a plurality of compacts 1 having curved surfaces are filled into the heat treatment vessel 2. Furthermore, by using the method for filling the compacts 1 according to the embodiment, the stack height G of the compacts 1 filled into the heat treatment vessel 2 is controlled to be 80% or more of the vessel height J, thereby increasing the number of processed compacts 1. This provides excellent mass productivity for sintered bodies.

[0042] Furthermore, according to the method for filling the compact 1 according to the embodiment, damage to the compact 1 can be suppressed by controlling the height 4 of the filling device 3. This also improves the yield of the sintered body.

[0043] Furthermore, by using the method for filling the compacts 1 according to the embodiment, the stack height G of the compacts 1 filled in the heat treatment vessel 2 can be set to 100% or less of the vessel height J, so that a plurality of heat treatment vessels 2 can be stacked to perform the heat treatment steps ST6 and ST7. This further improves the mass productivity of the sintered body.

[0044] (Examples) (Examples 1 to 5, Comparative Examples 1 and 2) The molded bodies 1 shown in Table 1 were prepared. Ball-shaped molded body 1A is shown in FIG. 2, band-shaped molded body 1B is shown in FIG. 3, and cylindrical molded body 1C is shown in FIG. 4. The molded bodies 1 in the examples and comparative examples were produced by at least one of a mold molding method and CIP. The size was the value of the sintered body (e.g., silicon nitride sintered body) after sintering step ST7. A molded body was prepared to obtain a sintered body of this size.

[0045]

[0046] Next, in the placing step ST3, multiple molded bodies 1 were placed on the filling device 3. After the moving step ST4, the process proceeded to the filling step ST5. The height 4 of the bottom surface of the filling device 3 in the filling step ST5 is shown in Table 2. The bottom of the filling device 3 was opened, and multiple molded bodies 1 were filled into the heat treatment container 2. The surface scratches of the multiple molded bodies 1 in the heat treatment container 2 were then checked, and the probability of surface scratch occurrence was calculated. At this time, surface scratches were defined as gouges, holes, etc. on the surface of the molded bodies 1 that were observable with the naked eye and had a major diameter of 2 mm or more. Dimples, adhesions, etc. that were not accompanied by gouges were not considered to be surface scratches. The filling step ST5 into the heat treatment container 2 was performed 100 times, and the percentage of the number of molded bodies that had surface scratches was defined as the surface scratch occurrence probability [%] of the molded bodies 1.

[0047] In Examples 1 to 5, the compacts 1 were placed on the filling device 3 using a belt conveyor, which allowed for automation of the placement on the filling device 3.

[0048]

[0049] As can be seen from Table 2, no scratches (damage) were observed on the ceramic molded bodies in Examples 1 to 5. Therefore, it can be said that not only the filling step ST5 but also the placing step ST3 and the moving step ST4 were appropriate. Furthermore, in Examples 4 and 5, the molded bodies 1 were filled while the filling device 3 was raised so that it would not come into contact with the stacked molded bodies 1.

[0050] In contrast, in Comparative Examples 1 to 3, the compact 1 was filled so that the height 4 exceeded 100 mm. In Comparative Examples 1 to 3, the impact of dropping the compact 1 during the filling step was large, resulting in a high probability of breakage of the compact 1. Furthermore, in the case of the plate-shaped compact 1D of Comparative Example 4, the compact 1D was bent when dropped, and all of the compacts 1D were deformed.

[0051] Next, in Examples 1 to 5, the ratio [%] of the stack height of the compacts 1 filled in the heat treatment vessel 2 to the vessel height was adjusted as shown in Table 3. When the stack height exceeded the vessel height of the heat treatment vessel 2, it was adjusted using a leveling jig 7.

[0052]

[0053] By using the leveling jig 7, it was possible to level the height of the green bodies 1 that protruded above the container height J of the heat treatment container 2. Furthermore, by setting the stack height G of the green bodies 1 filled into the heat treatment container 2 to be within the range of 80% to 100% of the container height J of the heat treatment container 2, it was possible to easily stack multiple heat treatment containers 2 while increasing the number of green bodies 1 to be heat treated at one time. Furthermore, it was possible to perform the debinding step ST6 and the sintering step ST7 while the green bodies were still filled into the heat treatment container 2.

[0054] By setting the stack height of the compacts 1 filled in the heat treatment vessel 2 within a range of 80% to 100% of the vessel height, the heat treatment vessels 2 could be stacked and the debinding step ST6 and the sintering step ST7 could be carried out.

[0055] According to at least one of the embodiments described above, it is possible to improve the yield and mass productivity of the sintered body.

[0056] Although several embodiments of the present invention have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other.

Claims

1. A method for filling a heat treatment container with a plurality of ceramic green compacts having a curved surface portion, the method comprising: a placing step of placing the plurality of ceramic green compacts on a filling device; a moving step of moving the filling device on which the plurality of ceramic green compacts are placed above the heat treatment container and to a height of 100 mm or less of the bottom surface of the filling device with reference to the bottom surface of the heat treatment container; and a filling step of filling the heat treatment container with the plurality of ceramic green compacts from the filling device. The method for filling a ceramic green compact is characterized by comprising these steps.

2. The method for filling a ceramic green compact according to claim 1, wherein the moving step moves the filling device on which the plurality of ceramic green compacts are placed to a height of 50 mm or less of the bottom surface of the filling device with reference to the bottom surface of the heat treatment container.

3. The method for filling a ceramic green compact according to claim 1 or 2, wherein the placing step places the plurality of ceramic green compacts on the filling device using a belt conveyor.

4. The method for filling a ceramic green compact according to claim 1 or 2, wherein the filling step raises the filling device so that the difference between the stacking height of the ceramic green compacts filled in the heat treatment container and the height of the bottom surface of the filling device is within a predetermined range.

5. The method for filling a ceramic green compact according to claim 1 or 2, wherein the filling step is performed until the stacking height of the ceramic green compacts filled in the heat treatment container reaches 80% or more of the height of the heat treatment container.

6. The method for filling a ceramic green compact according to claim 3, wherein the filling step is performed until the stacking height of the ceramic green compacts filled in the heat treatment container reaches 80% or more of the height of the heat treatment container.

7. The method for filling a ceramic green compact according to claim 1 or 2, wherein the filling step levels the stacking height when the stacking height of the ceramic green compacts filled in the heat treatment container exceeds the height of the heat treatment container.

8. The filling step is characterized in that when the stacking height of the ceramic compacts filled in the heat treatment container exceeds the height of the heat treatment container, the stacking height is leveled. The method for filling a ceramic compact according to claim 5.

9. The method for filling a ceramic compact according to claim 1 or claim 2, characterized in that the plurality of ceramic compacts are silicon nitride compacts.

10. The method for filling a ceramic compact according to claim 5, characterized in that the plurality of ceramic compacts are silicon nitride compacts.

11. The moving step includes: moving the filling device on which the plurality of ceramic compacts are placed until it is above the heat treatment container; and lowering the filling device on which the plurality of ceramic compacts are placed until it reaches the height. The method for filling a ceramic compact according to claim 1 or claim 2.

12. A method for manufacturing a ceramic sintered body, comprising: the placing step, the moving step, and the filling step according to claim 1; and a heat treatment step of heat-treating the plurality of ceramic compacts filled in the heat treatment container by the filling step.

13. A method for manufacturing a ceramic sintered body, comprising: the placing step, the moving step, and the filling step according to claim 9; and a heat treatment step of heat-treating the plurality of ceramic compacts filled in the heat treatment container by the filling step.

14. The method for manufacturing a ceramic sintered body according to claim 12, characterized in that in the heat treatment step, a plurality of the heat treatment containers are stacked, and the plurality of ceramic compacts in each heat treatment container are heat-treated.

15. The method for manufacturing a ceramic sintered body according to claim 13, characterized in that in the heat treatment step, a plurality of the heat treatment containers are stacked, and the plurality of ceramic compacts in each heat treatment container are heat-treated.

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