JPH06249582A - Atmosphere controlling heat treatment device and heat treatment method - Google Patents

Abstract

PURPOSE:To provide an atmosphere controlling heat treatment device and a heat treatment method in which atmosphere for heat treating ceramics material can be actively and precisely controlled and a physical characteristic such as strength of produced ceramic materials can be improved. CONSTITUTION:A firing device 1 is constructed such that a shell 20 and a carbon heater 12 enclosing the shell 20 are arranged within a main body 10 of the firing device. Within the main body 10 of the device are arranged a furnace gas feeding pipe 14 and a furnace gas discharging pipe 16. An atmosphere control chamber 30 defines an inside part of the shell 20 below the shell 20 and is formed. The atmosphere control chamber 30 is filled with atmosphere control material 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus and a heat treatment method for a ceramic material, and more particularly to a heat treatment apparatus and a heat treatment method for a ceramic material in which the atmosphere of a heat treatment chamber is controlled.

[0002]

2. Description of the Related Art In the conventional heat treatment of ceramic materials, particularly firing of a ceramic molded body, the atmosphere inside the sheath in which the molded body is placed is the gas generated from the molded body during the firing process or the atmospheric gas existing in the sheath. In consideration of the above, it was controlled by appropriately changing the weight of the molded product, the atmospheric gas pressure and the like in relation to the inner volume of the sheath. Here, the "ceramics material" refers to ceramics materials, ceramics compacts, calcined bodies, sintered bodies, and the like.

[0003]

However, in the passive control method as described above, in order to control the atmospheric gas, there is no choice but to change the weight of the molded body or the like, and the molding process is performed in one firing step. There is a problem that not only the weight and shape of the body are restricted but also the atmospheric gas cannot be precisely controlled.

Further, in JP-A-4-275978, a silica coating is removed from a silicon nitride powder, followed by sintering to remove silica for obtaining a silicon nitride sintered body having a reduced silica content. A combined processing / sintering furnace is disclosed. However, the non-oxidizing gas such as N ₂ gas is introduced into this furnace in order to scatter and remove the silica component in the form of gas, and the atmosphere used directly for heat treatment (particularly sintering) is positively activated. Not meant to be created.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to enable active and precise control of the atmosphere for heat-treating a ceramic material, and obtain the resulting ceramic material. An object of the present invention is to provide an atmosphere control heat treatment apparatus and a heat treatment method capable of improving the physical properties such as the strength.

[0006]

Means for Solving the Problems As a result of intensive research to achieve the above object, the present inventor has found that the above object can be achieved by providing a specific atmosphere control chamber,
The present invention has been completed. Therefore, the heat treatment apparatus of the present invention is a heat treatment apparatus for a ceramic material in which a heat treatment chamber for arranging an object to be heat treated is provided in the heat treatment apparatus body, and an atmosphere control material is provided in the vicinity of the heat treatment chamber. It is characterized in that a filled atmosphere control chamber is provided, and the atmosphere control chamber and the heat treatment chamber are connected to each other in a breathable state. Further, the heat treatment method of the present invention is characterized in that when heat-treating the ceramic material, the heat treatment is carried out while actively controlling the atmosphere in the heat treatment chamber in which the object to be heat treated is placed.

[0007]

In the atmosphere controlled heat treatment apparatus of the present invention, the atmosphere control chamber is provided near the heat treatment chamber in which the object to be heat treated is placed. The control chamber is filled with an atmosphere control material that generates an atmosphere control gas. Further, the control chamber and the heat treatment chamber were connected so as to have air permeability. Therefore, in the heat treatment of the object to be heat treated, the atmosphere control gas can be introduced into the heat treatment chamber, if necessary,
The atmospheric gas can be controlled precisely and actively.
Therefore, the type and partial pressure of the atmosphere can be appropriately controlled according to the shape and material of the object to be heat treated, and a ceramic material having suitable physical properties can be obtained.

The heat treatment apparatus of the present invention will be described below. The heat treatment apparatus of the present invention comprises a heat treatment chamber provided in the main body of the heat treatment apparatus. The shape of the main body and processing chamber is
Although not particularly limited, in consideration of heat transfer to the processing chamber and the like, it is preferable that the two have a similar shape relationship,
More preferably, both of them have a substantially cylindrical shape and are arranged on concentric circles. A heat generating member, for example, a heater is arranged around the processing chamber, and heat is transferred from the heat generating member to the processing chamber. Further, an atmosphere control chamber is provided near the processing chamber, and the atmosphere used for the heat treatment can be controlled via this control chamber.

The material of the apparatus main body is not particularly limited, but it is preferable that it has heat insulation and corrosion resistance, and carbon, SiC, ZrO ₂ , Si ₃ N _{4 and the} like can be exemplified. The same material may be used. The material of the processing chamber is not particularly limited, and can be changed as appropriate depending on the type of ceramic material to be heat-treated and the intended treatment. However, when performing the firing treatment, carbon, Si
The same material as C, Si ₃ N ₄ and the object to be heat treated can be used. Further, the heat generating member is not limited, and can be appropriately changed depending on the temperature required for the heat treatment and the like, and examples thereof include a carbon heater, a ceramic heater, and a metal heater.

Next, the atmosphere control room will be described.
This atmosphere control chamber is arranged near the heat treatment chamber as described above, and the atmosphere control chamber is filled with the atmosphere control material. Further, the atmosphere control chamber and the heat treatment chamber are connected to each other in a state having sufficient air permeability to supply the atmosphere control gas generated from the atmosphere control material from the atmosphere control chamber to the heat treatment chamber. The position of the atmosphere control chamber is not particularly limited as long as it is in the vicinity of the heat treatment chamber, but the heat from the heat generating member can be received and the atmosphere control gas generated from the atmosphere control material can be smoothly fed to the heat treatment chamber. Considering the supply, it is preferable that the heat treatment chamber is arranged in the lower part of the heat treatment chamber. Therefore, it is more preferable that the atmosphere control chamber is provided by partitioning a part (especially the lower part) of the heat treatment chamber.

The atmosphere control material to be filled in the atmosphere control chamber can be appropriately selected according to the intended heat treatment, for example, calcination, firing, oxidation treatment, etc. In the firing treatment, oxides such as silica are used. , Carbon, nitrides such as silicon nitride, carbides such as SiC, and borides such as BN. Moreover, you may combine 2 or more types of these materials. The material may be in the form of powder, lump, or the like. The atmosphere control chamber acts extremely effectively on a material existing as a gas only near the heat treatment temperature, such as SiO. Here, the atmosphere in the heat treatment chamber is, in addition to N ₂ , Ar, and air that mainly constitute the atmosphere as the furnace gas, SiO generated when SiO ₂ is added, or CO generated when carbon and oxygen react. It is composed of

In order to supply the atmosphere control gas from the atmosphere control chamber to the heat treatment chamber more smoothly and to control the heat treatment atmosphere more precisely, a carrier gas introducing pipe is connected to the atmosphere control chamber to introduce the carrier gas. Alternatively, an atmosphere exhaust pipe may be connected to the heat treatment chamber to exhaust the atmosphere, or both may be performed. Further, if a flow rate control device is provided in the carrier gas introduction pipe and / or the atmosphere discharge pipe to control the introduction amount of the carrier gas and / or the atmosphere discharge amount, the heat treatment atmosphere can be further finely adjusted. Also,
Between the atmosphere control chamber and the carrier gas introduction pipe, a carrier gas heating region, for example, a spiral introduction pipe may be provided.
As a result, the temperature difference between the carrier gas and the atmosphere control gas can be reduced, and the partial pressure of the atmosphere control gas can be controlled more precisely.

Next, the heat treatment method of the present invention will be described. In the heat treatment method of the present invention, the object to be heat treated, for example, a ceramic molded body, a calcined body, a sintered body is placed in the heat treatment chamber,
The heat treatment is performed while actively controlling the atmosphere in the heat treatment chamber. That is, introducing an atmosphere control gas into the heat treatment chamber,
By selecting the type and partial pressure of the atmosphere control gas according to the intended heat treatment, the atmosphere in the heat treatment chamber can be precisely controlled and the heat treatment can be performed under optimum conditions. In the heat treatment method of the present invention, in particular, during heat treatment, the heat-treated object generates a large amount of gas, the atmosphere in the heat treatment chamber is changed from an oxidizing gas to a reducing gas, and vice versa. This is effective when it is necessary to change to gas.

[0014]

EXAMPLES The present invention will be described below with reference to the drawings through examples and comparative examples. FIG. 1 shows an embodiment of the heat treatment apparatus of the present invention. In the figure, a firing apparatus 1 according to the present invention
In the apparatus main body 10, a sheath 20 which is an example of a heat treatment chamber and a carbon heater 12 which is an example of a heat generating member which surrounds the sheath 20 are arranged. Further, the apparatus body 10 is provided with an in-furnace gas introduction pipe 14 and an in-furnace gas discharge pipe 16. The introduction pipe 14 and the discharge pipe 16 do not have to be provided, but it is preferable to provide the introduction pipe 14 and the discharge pipe 16 because the inner and outer pressures of the sheath 20 can be made uniform by flowing an appropriate gas.

An atmosphere control chamber 30 is formed below the sheath 20 by partitioning the inside of the sheath 20, and an atmosphere control material 32 is filled in the control chamber 30. The atmosphere control material 32 is appropriately gasified during firing,
The atmosphere in the sheath 20 can be actively and precisely controlled by flowing into the sheath 20 through the ventilation holes 34. As a result, the body 22 to be fired arranged in the sheath 20 is fired under suitable or optimum conditions, and the performance of the obtained sintered body can be improved. Further, by controlling the atmosphere in this way, the performance of the obtained sintered body can be matched to the intended use, and a sintered body having good adaptability for various applications can be easily obtained.

An atmosphere discharge pipe 40 is provided above the sheath 20.
Are connected, and a cooler 42 is connected to the discharge pipe 40. In the lower part of the atmosphere control chamber 30, a spiral spiral lead pipe 5 made of graphite, which is an example of a carrier gas heating region, is provided.
2 are connected, and further, the carrier gas introduction pipe 50 is connected via the spiral introduction pipe 52. Also,
The atmosphere discharge pipe 40 and the carrier gas introduction pipe 50 are provided with flow rate control devices 44 and 54, respectively, so that the discharge amount and the introduction amount thereof can be controlled. Therefore, the atmosphere control chamber 30 and the atmosphere exhaust pipe 4
0, the carrier gas introducing pipe 50, and the like are appropriately cooperated, whereby the atmosphere (sintering atmosphere) in the sheath 20 can be controlled more precisely.

Next, an example of a method of firing a ceramic material using the firing apparatus 1 will be described. First, the body 22 to be fired is placed in the sheath 20, and the atmosphere control chamber 30 is filled with the atmosphere control material 32 corresponding to the body 22 to be fired.
Next, inside the apparatus main body 10, while the appropriate gas is being circulated through the in-furnace gas introduction pipe 14 and the exhaust pipe 16, the heater 12 is used to heat the sheath 20.

At the time of raising the temperature of the sheath 20, the atmosphere control material 3
2 gasifies and produces an atmosphere control gas. The atmosphere control gas is introduced into the sheath 20 while controlling the partial pressure of the atmosphere control gas by the carrier gas introduction pipe 50, the flow rate control device 54 and the spiral introduction pipe 52 with the carrier gas of a predetermined amount and temperature. To do. On the other hand, while the atmospheric gas is discharged from above the sheath 20 through the discharge pipe 40, the cooler 42 and the flow rate control device 44 while being controlled, the atmosphere in the sheath 20 is controlled more precisely, and the object to be fired is controlled. 22 is fired. As described above, since the firing can be performed while actively and precisely controlling the atmosphere in the sheath 20, the performance of the obtained sintered body can be made uniform.

(Example 1) Si ₃ N ₄ powder 8 having a particle size of 0.6 μm, an oxygen content of 1.5% by weight, and a specific surface area of 12 m ² / g.
6% by weight, Yb ₂ O ₃ powder having a particle size of 0.5 μm and a specific surface area of 10 m ² / g 9% by weight, a particle size of 0.2 μm and a specific surface area of 2
² % by weight of 0 m ² / g SiC powder and 3% by weight of MgO powder were mixed, pulverized and granulated to obtain a molding powder. This molding powder was uniaxially pressed into a size of 50 × 50 × 10 mm and then cold isostatically pressed to obtain a ceramic molded body.

The molded body thus obtained was placed in the silicon nitride sheath 20 of the firing apparatus 1, and Si ₃ was placed in the atmosphere control chamber 30.
Pellets made at a ratio of N ₄ / SiO ₂ = 9/1 (weight ratio) were filled. After the inside of the sheath 20 was evacuated through the discharge pipe 16, N ₂ gas was introduced up to 9 atm through the introduction pipe 14, and the heater 12 was energized to heat the molded body.

When the maximum calcination temperature of 1800 ° C. is reached, the N ₂ gas whose flow rate is controlled to 0.5 l / min by the flow control device 54 is introduced into the introduction pipe 50, the swirl introduction pipe 52 and the atmosphere control chamber 30. Saya 20 was filled via At this time, the atmospheric gas in the sheath 20 was discharged through the discharge pipe 40 while the flow rate control device 44 controlled the flow rate to 0.5 l / min.

After 3 hours had passed since the maximum temperature was reached, the introduction of N ₂ gas was stopped, and the energization of the heater 12 was stopped. A plate body in which the surface of the obtained sintered body was used as a tensile surface as it was and was ground to a surface roughness of 0.8.
A test piece of 3 × 4 × 40 mm was cut out from the processed product obtained as s, and a bending test according to JIS R 1601 was performed at room temperature and 1200 ° C., and the obtained results are shown in Table 1.
The relative density is also shown.

Comparative Example 1 A molded body similar to that of Example 1 was prepared. The compact was fired using a normal sintering furnace having no gas introduction mechanism. That is, as a firing device,
Except that the carrier gas introduction pipe 50, the spiral introduction pipe 52, the atmosphere control chamber 30, and the atmosphere discharge pipe 40 are not provided,
It is similar to the firing apparatus 1. The above-mentioned molded body was placed in a silicon nitride sheath and the same operation as in Example 1 was repeated. The obtained results are shown in Table 1.

Example 2 Si ₃ N ₄ powder 8 having a particle size of 0.6 μm, an oxygen content of 1.4% by weight and a specific surface area of 13 m ² / g.
4% by weight, S having a particle size of 0.9 μm and a specific surface area of 8 m ² / g
c ₂ O ₃ powder 3% by weight, particle size 0.8 μm, specific surface area 9 m
13% by weight of ² / g Yb ₂ O ₃ powder was mixed, pulverized and granulated to obtain a molding powder. 50 × 50 × this molding powder
It was uniaxially pressed into a size of 50 mm and then cold isostatically pressed to obtain a ceramic molded body.

The obtained molded body was set in the sheath 20 of the firing apparatus 1, and BN / C = 20/1 was set in the atmosphere control chamber 30.
The pellets prepared in the ratio (weight ratio) were filled. After vacuuming the inside of the sheath 20 through the discharge pipe 16, N ₂ gas is introduced up to 9 atm through the introduction pipe 14, and the heater 12
Was energized to heat the molded body.

The temperature was raised at 500 ° C./hr, and N ₂ gas was introduced into the sheath 20 at a flow rate of 1.0 l / min in the same manner as in Example 1 from when the temperature reached 1700 ° C. until the temperature was raised to 2000 ° C. Then, the introduction of N ₂ gas was stopped when the maximum firing temperature of 2000 ° C. was reached. After holding in this state for 4 hours, it was cooled to obtain a sintered body (42 × 42 × 42 mm). The relative density of the obtained sintered body was measured, and from the surface to be fired (the surface of the sintered body as it is after firing without post-processing),
The test piece was cut out so that the thickness (depth) of 3 mm and 10 mm was near the center of the thickness of the JIS size test piece, and the bending strength was measured at room temperature and 1400 ° C. as in Example 1. . The surface roughness of the test piece was 0.8 s. The obtained results are shown in Table 2.

Comparative Example 2 The same operation as in Example 2 was carried out except that the same baking apparatus as in Comparative Example 1 was used, and the results obtained are shown in Table 2.

Example 3 Si ₃ N ₄ powder 9 having a particle size of 0.6 μm, an oxygen content of 2.0% by weight and a specific surface area of 13 m ² / g
2% by weight, Y ₂ having a particle size of 0.8 μm and a specific surface area of 8 m ² / g
A ceramic compact was obtained in the same manner as in Example 1, except that 8% by weight of O ₃ powder was used as the raw material powder. S in the atmosphere control room 30
i ₃ N ₄ / SiO ₂ = 5/1 (weight ratio) was filled with the pellets, and the inside of the sheath 20 was evacuated to N.
₂ gases were introduced up to 9 atm and heating was started.

The temperature was raised at 1000 ° C./hr, the temperature was maintained for 2 hours after reaching 1700 ° C., and N ₂ gas was introduced into the sheath 20 at a flow rate of 1 l / min. After 2 hours, when the maximum firing temperature of 1900 ° C. was reached, N ₂
The introduction of gas was stopped and the gas was maintained for 2 hours. Then, it was cooled to obtain a sintered body, and the same bending test as in Example 1 was performed. The obtained results are shown in Table 3.

(Comparative Example 3) A molded body similar to that of Example 3 was used.
Example 3 except that firing was performed using the firing apparatus of Comparative Example 1.
The same operation as above was performed, and the obtained results are shown in Table 3.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

As is clear from Tables 1 to 3, according to Examples 1 to 3 included in the scope of the present invention, it is possible to obtain a sintered body having excellent performance. That is, in Examples 1 and 3, a high-strength sintered body was obtained even if the surface after firing was used as the tensile surface of the bending test piece as it was. In addition, in the second embodiment,
A high-strength sintered body was obtained inside the sintered body. Although the present invention has been described with reference to the embodiments, the present invention is not limited to the embodiments and various modifications can be made within the scope of the gist of the present invention. For example, the present invention is not limited to firing treatment,
It can also be applied to other heat treatments such as oxidation treatment and calcination. Also,
The atmosphere discharge pipe 40, the carrier gas introduction pipe 50 and the like are not always necessary, and the same effect can be obtained by adjusting the filling amount of the atmosphere control material.

[0035]

As described above, according to the present invention,
Since a specific atmosphere control chamber is provided, it is possible to provide an atmosphere control heat treatment apparatus and a heat treatment method capable of actively and precisely controlling the atmosphere for heat-treating a ceramic material and improving the physical properties such as strength of the obtained ceramic material. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a heat treatment apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Firing apparatus 10 Main body 12 Carbon heater 20 Saya 22 Object to be fired 30 Atmosphere control chamber 32 Atmosphere control material 40 Atmosphere discharge pipe 50 Carrier gas introduction pipe 52 Whirlpool introduction pipe

Claims (6)

[Claims] 1. A heat treatment apparatus for a ceramic material, comprising a heat treatment chamber for arranging an object to be heat treated in a main body of the heat treatment apparatus, wherein an atmosphere control material is filled with an atmosphere control material in the vicinity of the heat treatment chamber. An atmosphere controlled heat treatment apparatus comprising a chamber, wherein the atmosphere control chamber and the heat treatment chamber are connected in a state of having air permeability. 2. The heat treatment apparatus according to claim 1, further comprising a carrier gas introduction pipe connected to the atmosphere control chamber and / or an atmosphere discharge pipe connected to the heat treatment chamber. 3. The heat treatment apparatus according to claim 1, wherein a carrier gas heating region is interposed between the atmosphere control chamber and the carrier gas introduction pipe. 4. The atmosphere control material is one or two or more materials selected from the group consisting of carbon, carbides, oxides, nitrides and borides. The heat treatment apparatus according to any one of the items. 5. When heat-treating a ceramic material,
A ceramic material characterized by performing heat treatment while actively controlling the atmosphere in the heat treatment chamber in which the object to be heat treated is to be controlled by an atmosphere control gas from an atmosphere control chamber connected to the heat treatment chamber in a breathable state. Manufacturing method. 6. When heat-treating a ceramic material,
A ceramic material characterized by performing heat treatment while controlling the atmosphere in the heat treatment chamber in which the object to be heat treated is adjusted so as to match the object to be heat treated by adjusting the types and partial pressures of the atmosphere control gas and the carrier gas. Heat treatment method.