JPS61134582A - Vertical continuous heating furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electric vertical continuous heating furnace that can continuously heat treat materials housed in a heat-resistant container at high temperatures in a still state. The present invention relates to a heating furnace suitable as a high-temperature furnace for producing materials.

BACKGROUND OF THE INVENTION In recent years, ceramic whiskers such as silicon carbide and silicon nitride have been attracting attention for their use as fiber reinforcement materials. When ceramic whiskers are grown as M1B crystals in a raw material to be treated by a gas phase reaction, it is necessary to subject the raw material to a heat treatment in a stationary state. However, when the raw material to be treated is in a fluid state, the product becomes powder, so conventionally, a hammer-type high-temperature heating furnace that can keep the raw material to be treated has been frequently used.

However, in such cases, high-temperature heat treatment at 1,300 to 2,000 degrees Celsius is performed, so if the raw materials to be treated contain substances that become vaporized at low temperatures as impurities or additives, they may During high-temperature heat treatment, they volatilize or sublimate and are entrained in the atmospheric gas, and when they come into contact with the furnace wall in the low-temperature region, they condense and precipitate, forming deposits inside the furnace (hereinafter referred to as ``wristed iron''). The purpose is to form T. When the amount of deposits increases, problems arise, such as the need to close the furnace wall space and shut down the furnace, or the deposits to be remixed into heat-treated products.

These situations are described, for example, in JP-A-58-172'298.
This problem is taught in Japanese Patent Application Laid-open No. 58-213698, Japanese Patent Publication No. 58-502096, etc., and although various countermeasures have been taken, a sufficient solution has not yet been reached. In addition, in the case of a barrel-type heating furnace, there are other problems such as the need to provide an in-furnace conveyance mechanism for conveying the treated material under high temperature.

Problems to be Solved by the Invention The present invention is an electric method capable of performing high-temperature heat treatment while storing an object to be heated (hereinafter simply referred to as the treatment material) in a heat-resistant container, which needs to be heat-treated in a stationary state. The purpose is to provide a vertical continuous heating furnace.

Specifically, the present invention provides a furnace that is suitable as a whisker manufacturing device that has the problems described above, but is not suitable for use in the manufacture of molded bodies of ceramics, carbon materials, etc. A firing furnace for preforms made by mixing raw material powder with a binder, sintering aid, etc. and molding the mixture by pressure molding, slurry casting, etc.

It can also be applied to various uses such as a sintering furnace for metal powder compacts or a joining furnace for ceramics and metals.

Means for Solving the Problems The present invention provides a vertical heating furnace having an energized heating section, as illustrated in the longitudinal cross-sectional conceptual diagrams of FIGS. A core tube 2 is provided through the core tube 12 in the vicinity of both ends of the furnace body opening. An exhaust pipe 7' is attached, a supply means 11 for the heat-resistant container 10 is provided at the top of the furnace core tube 2, and a support and transport means 16 for the flame-resistant containers 10a, 10b is provided at the bottom of the furnace core tube 2.
This is a vertical continuous heating furnace that is equipped with a heat-resistant container and a heat-resistant container, respectively, so that the material in the heat-resistant container can be continuously heat-treated.

The vertical furnace body 1 can be made into an appropriate fireproof and heat-insulating structure according to the usage temperature conditions, etc. by a conventional method.

For example, in the case of a heat treatment furnace up to about 2400°C, the center part is made of carbonaceous or graphite refractory, and the outer layer is made of silica.
Using alumina-based insulation bricks and fiber insulation materials,
It is constructed by forming the outermost shell with an am exterior material.

The energization heating parts 4, 4' disposed in the vertical furnace body 1 are preferably composed of direct energization heating means in terms of thermal efficiency, but may also be one indirect heating means.

That is, when the current heating section 4.4' is used as a current heating means, as illustrated in FIG.
By connecting the bus bars 6 and 6' through the im jacket type water-cooled holders 5 and 5' and applying electricity, the core tube 2 itself generates heat and raises its temperature. An appropriate resistance heating material can be used depending on the heat treatment temperature of the furnace. For example, when the heating temperature is 1000 to 2400°C, heat-resistant materials such as silica carbide, carbonaceous, or graphite may be used. used. In addition, in its application, moldings made only of these INs, molds made of a mixture of two or more of them, or molded products made from different materials with low temperature and high temperature regions, etc. It can take various forms. Furthermore, the bus bars 6, 6' can also be connected to the furnace core tube within the furnace body.

On the other hand, in order to mix the energized heating parts 4, 4' with the interlayer heating means, as illustrated in FIG. The tube 2 is buried so as to surround it, and the cooling holders 5, 5 as described above are placed therein.
The bus bar 6°6' is connected through the bus bar 6°6' and energized to generate heat, thereby raising the temperature of the furnace core tube 2 directly.

In this case, the furnace core tube 2 is made of a heat-resistant and thermally conductive material that is appropriate depending on the heating temperature, but for example,
It is manufactured from materials such as silicon nitride, silicon carbide, carbon or graphite.

The furnace core tube 2 heats the heat-resistant container 10 transferred therein.
As mentioned above, it can be made of an appropriate material depending on the heating means applied, and in the case of an indirect heating method, it can be divided into several parts in the longitudinal direction of the furnace. It can be done. It is also appropriate to form a coating layer of oxidation-resistant or wear-resistant material 1, such as oxide, carbide, or nitride, on the exposed surface depending on the heating atmosphere or the like.

The coolers 3 and 3' are arranged to surround the entire circumference of the core W2 and serve to prevent oxidation and wear and tear of the portion of the core tube that comes into contact with the outside air and to cool the heat-resistant container. Appropriate types such as those wrapped in a shape or those of a jacket type are applicable.

The air supply pipe 7 and the exhaust pipe 7', which are connected to the ventilation pipe, are provided to adjust the atmosphere inside the furnace core tube 2, and are designed to maintain an inert atmosphere (argon, nitrogen, etc.) inside the furnace.

- formation and maintenance of a gas atmosphere such as carbon oxide).

Removal of fIO heat-generated gas 1 Depending on the purpose of supplying reactive gas used in reaction sintering, etc., it is connected to a gas supply source, gas suction device, gas recovery/recirculation device (none of which are shown), etc. Ru.

As illustrated in the partially enlarged views of FIGS. 3 and 4, backing materials 9 and 9' for maintaining airtightness within the core tube are held at both ends of the core tube 2, and 11ii! 1111
A guide tube, for example, graphite tube bodies 14 and 14', is connected to properly guide the flow of the container into and out of the reactor core tube. The backing materials 9 and 9' are made of a flexible material such as raw rubber, silicone rubber, or Mu fluorine, and have a shape smaller than the outer diameter of the heat-resistant container, and are curved into close contact with the wall of the heat-resistant container during transportation. Make sure to maintain sufficient airtightness.

The supply means 11 for the heat-resistant container 10 is for feeding the heat-resistant container into the furnace core tube from the uppermost stage of the furnace core tube 2.
A lateral transfer machine 13 that transfers the heat-resistant container 10 containing the processing material located above to the upper part of the reactor core tube, and a transferred ha capacity H10.
It consists of a guide pipe 14 that guides the heat-resistant container 10 to a fixed position, and a vertical transfer device 15 that forcibly moves the heat-resistant container 10 downward.

The support/unloading means 16 for the heat-resistant container 10 is a guide pipe 14 at the bottom of the furnace.
A lifting device @ 17 for supporting the heat-resistant container during heat treatment, and a lifting device It consists of a feeding device @ 18 for laterally carrying out the heat-resistant container that has come out of the hearth by lifting the rod 17, and a pedestal 19 for holding the heat-resistant container to be carried out. A U-shaped placement portion 21 is provided at the tip of the rod of the lifting device 17 and the feeding device 18.
Support plate portions 20 that can operate within the gaps between the arm portions are arranged in a row to face each other.

That is, although FIG. 5 shows an example in which the support plate 820 is disposed on the elevating device t17 side and the U-shaped arm portion 21 is disposed on the feeding device 78 (Ill), this relationship may be reversed if desired. The operating parts of the above-mentioned lateral transfer device 13°, longitudinal transfer device 15, lifting device fal 17 and feeding device @18 are as follows:
Any mechanism that can reciprocate the rod may be used, such as a piston-cylinder mechanism operated by hydraulic pressure or air pressure, or a worm-worm gear mechanism operated by an electric motor.

The basic configuration of the vertical continuous heating furnace of the present invention has been described above, but means such as adding a conventional means for a furnace or replacing it with an appropriate equivalent means can be applied as appropriate.

For example, the furnace body 1 may be provided with a thermometer or a pressure gauge 22 to control the temperature and pressure inside the furnace tube 2, or a peep IX (
Conventional means such as attaching a flexible bus bar (not shown) or providing a sequential control device for each part of the furnace can be added. Furthermore, the holding table 12 and the pedestal 19 may be not only a smooth horizontal fixed floor, but also a smooth inclined fixed floor, or a movable top such as a belt conveyor or a roller conveyor. Furthermore, as illustrated in FIG. 2, the lateral transfer device 13 in the supply means 11 is replaced with a mechanism in which a rod reciprocates on a wheel to send the container 14, for example, by holding a heat-resistant container between both arms and separating it from the holding table surface. The robot transfer device 23, which can be directly transferred onto the reactor core tube, or the lifting device 17 or the feeding device f! The U-shaped arm portion 21 provided at N8 is not a fixed type, but can be replaced with a clamping means that can be opened and closed.

The heat-resistant container 10 is manufactured from an appropriate heat-resistant material in consideration of heat resistance, thermal conductivity, corrosion resistance, etc., depending on the processing conditions (temperature, atmosphere). For example, if the temperature is up to about 1,500℃, it will be manufactured from silicon nitride, alumina, silica-alumina refractories, etc., and if it will reach 2,000℃ or higher, it will be made of refractory materials such as silicon carbide, carbonaceous, graphite, etc. For use at temperatures below 1000°C, a wider variety of conventional materials are applicable. In addition, as its configuration, the car-
It may be formed not only of materials, but may also be formed by laminating materials of 2M or more.

The shape of the heat-resistant container 10 may be either an open type or a closed type, an example of which is shown in FIG. (b) with gas flow holes formed.

Items with continuous internal protrusions to improve heat transfer to the interior (cl), items with a perforated bottom to allow high temperature gas to enter and exit the interior (d), and when the treated material is a formed shape A container with an appropriate shape is used, such as a cage-shaped container (e), or a closed type with a lid (f) 1. At that time, the upper and lower surfaces of the WI! It is also effective to use auxiliary means, such as providing fitting uneven parts to ensure stability in stacking containers.

The outer diameter of the heat-resistant container 1σ can be set as appropriate, but the narrower the clearance, the better the thermal movement, and the ability to scrape off accumulated debris when the container descends. Preferably, the thickness is approximately 4 mm. The inner diameter of the furnace core tube itself is not particularly limited, but when used as a whisker manufacturing furnace, a diameter of about 50 mm to 500 mm is often used.

Although various types of WM can be used for the fermentation furnace, an example of the furnace according to FIG. 1 and No. 59 is shown below.
a) General-purpose mode Air supply [While introducing an inert gas such as nitrogen gas from 7', convert the 2 yen core tubes stacked with empty #heat containers into an inert atmosphere a1, and While water is flowing through the busbars 4 and 5 and 5 and 5', electricity is applied to the busbars 4 and 4' to raise the temperature to a predetermined temperature.

Next, the vertical transfer device 15 and the lifting device 1117 work together to extract the heat-resistant container 10a to the same level as the bottom of the hearth, and move the rod of the feeding device 1B forward to connect it to the tip thereof. The upper surface of the U-shaped arm 1521 receives the upper heat-resistant container 10b to prevent it from falling, while gripping the extracted heat-resistant container 10a with the front surface of the arm 21 and transporting it sideways to the outside of the hearth. Carry it out onto floor 19. Next, the support plate part 20 connected to the rod tip of the lifting device 1117
is raised through the gap in the U-shaped arm portion 21 to support the upper heat-resistant container 10b, and then the rod of the feeding device 18 is moved back to move the U-shaped arm portion 21 from the bottom of the furnace to its original position. Back to the page. By repeating the above cycles,
The heat-resistant container 10 inside the furnace core tube 2 can be carried out of the system from the bottom of the furnace.

On the other hand, in the upper part of the furnace, after the heat-resistant container 10a is extracted from the bottom of the furnace, the supply means 11 fills and stores the processing material in advance with a quantitative supply device (not shown).
t The heat container 10 is supplied into the furnace tube 2.

That is, by advancing the rod of the lateral transfer device 13, the heat-resistant container 10 on the holding stand 12 is transferred laterally onto the reactor core tube 2, and after the alignment with the reactor core tube is ensured by the guide tube 14, A heat-resistant container 1° is fed into the furnace tube 2 from above by lowering a rod of 8% 15 in the longitudinal direction.

By adjusting the speed of extraction of the heat-resistant container from the bottom of the furnace and supply from the top of the furnace, the desired maximum temperature range (e.g. 1000 to 2000°C) can be maintained for a predetermined time (e.g. 30 minutes to 40 hours). and store it in a heat-resistant container 10.
The filled treatment material is subjected to a predetermined high temperature heat treatment.

During this time, in order to adjust the atmosphere inside the reactor core tube, inert gas or reactive gas is introduced from the air supply pipe 7, or the exhaust pipe 7'
This can be done by suctioning the generated gas from or as appropriate.

At that time, the gas flow and the flow of the processing material become countercurrent, so
It is extremely easy to raise the temperature of the atmosphere under heating, and the heat possessed by the gas is used for preheating, so the energy movement is good.

In addition, even if the volatile components in the treated material become deposits during the process of raising the temperature of the treated material, the gas flow and the heat container are in countercurrent contact, so the volatile components are in the target temperature range. It will not be re-mixed into the material.

Even if deposits occur on the core tube wall, they will be scraped off by the container wall when the heat-resistant container descends, and will be discharged through the guide pipe 14' at the bottom of the furnace, causing operational trouble. There is no.

Furthermore, during such high-temperature heat treatment, the treated material is stored in a heat-resistant container and heated at high temperature statically without being subjected to vibration, so that the treated material does not have a preformed body with poor shape retention or a whisker structure. Even raw materials can now undergo appropriate high-temperature heat treatment.

b) Specific usage mode This heating furnace can be applied to heat treatment in various temperature ranges up to about 2400°C, but specific usage when used as a whisker production furnace, which is a preferred example [An example of Jl is shown] .

1. Application example for manufacturing silicon carbide whiskers The treated material prepared by mixing fine carbon powder and fine silica powder has a bulk density of α
100g 7cm 3. A graphite cylindrical container with a depth of 150 mm (T shown in Figure 6 (b), filled to a clearance of 3 mm with the reactor core tube, with a length of 3 m and an inner diameter of 150 mm) with a filling height of 100 mm. It was supplied to the furnace core tube. When the inside of the furnace was moved at a speed such that it was heated and maintained at 1400 to 2000°C for 30 minutes to 30 hours and heat treated, a β type with a diameter of α1-4.9 mm and a length of 50 to 200 μm was formed. Silicon carbide whiskers were obtained with a yield of 90-100%.

Although production continued for 30 consecutive days, the inside of the reactor core tube was not clogged with deposits, and even though the introduction of inert gas was stopped during normal operation and heat treatment was performed, the graphite vessel and reactor core tube were not clogged with deposits. Almost no oxidative consumption was observed.

2. Application example for manufacturing silicon nitride sintered body: 30% porosity
Carbonized MW in the graphite container (the one shown in Figure 6(d))
After filling with R, it was fed into a silicon nitride-coated graphite furnace tube through which nitriding gas was flowing.

Heat treatment was carried out while moving the inside of the furnace tube downward so as to maintain heating in a range of 1300 to 1400° C. for 5 to 20 hours. As a result, silicon nitride with a diameter α of 5 to 1 μm and a length of 50 to 300 μm was obtained, and the furnace was operated continuously for 20 days without any problems.

In addition to these uses, for example, sintering of aluminum 6 minilum powder preforms, fermentation treatment of small metal parts, and bonding of ceramics and metals using a brazing filler metal.

For firing or graphitizing carbonaceous products molded with coal tar pitch binder, such as electrolytic layer Sa and electrodes for electrical discharge machining, or for manufacturing silicon nitride sintered bodies by the friendly reaction of metal silicon powder and nitrogen gas. It can be widely applied to appropriate high-temperature heat treatments. 4 Effects of the Invention The present invention is a vertical continuous heating furnace in which the treated material is supplied from the upper stage of the furnace and taken out from the lower stage. Therefore, the material to be treated is subjected to high-temperature heat treatment in a stationary state, and there is no need for a conveyance device inside the furnace.

2. Even if deposits are generated, they are scraped off as the heat-resistant container descends, so there is no problem with shutdowns that occur with horizontal heating furnaces.

& Since the gas flow and the flow of the processing material are in a countercurrent state, it is easy to adjust the atmosphere in the furnace, and the heat retained by the gas is effectively used for pre-warming the processing material.

Due to the above-mentioned effects, a furnace is provided which is particularly suitable as an f+ manufacturing apparatus for whisker materials involving gas phase reactions such as silicon carbide whiskers.

It is extremely useful in industry as it exhibits the following effects.
It is something that

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual longitudinal sectional view of a preferred embodiment of the present invention, and FIG. 2 is a conceptual longitudinal sectional diagram of another embodiment. FIG. 3 shows a partially enlarged sectional view of the vicinity of the backing material in the upper stage of the furnace, and FIG. 4 shows a partially enlarged sectional view of the vicinity of the backing material in the lower stage of the furnace.

FIG. 5 is a plan view showing the positional relationship in the support and carry-out mechanism as seen from line AA' in FIGS. 1 and 2, and FIG. FIG. 2 is a perspective view showing the actual state of the heat container.

19.6. Vertical furnace body, 2...furnace core tube.

3.3'...Cooler, 4.4'...Electric heating section.

7... Air pipe, 7'... Exhaust pipe.

9.9′・・・Backing material.

TO, +Oa, tob...-, heat-resistant container.

11... Supply means, 16... Supporting and carrying out means.

20... Support plate part, 21... U-shaped arm part.

Claims (1)

[Claims] 1. In a vertical heating furnace having an energized heating furnace, a core tube is provided in the center of the furnace body passing through it, and a cooler and a vent pipe are installed in the core tube near both ends of the furnace body opening. A supply means for a heat-resistant container is provided at the top of the furnace core tube, and a means for supporting and discharging the heat-resistant container is installed at the bottom of the furnace core tube to continuously heat the processing material in the heat-resistant container. A vertical continuous heating furnace characterized by being capable of processing. 2. The means for supporting and transporting the heat-resistant container consists of an elevating device, a feeding device, and a platform, and a U-shaped arm and a gap between the U-shaped arms are provided at the rod tips of the elevating device and the feeding device. The vertical continuous heating furnace according to claim 1, characterized in that operable support plate portions are arranged in series in a row to face each other.