JPS61252481A - Baking device for ceramics - 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] upper The present invention relates to a ceramic firing apparatus.

Random ILL The materials to be fired are placed in a large batch type furnace and fired at a uniform temperature throughout. Firing is performed by repeating heating and cooling in each cycle.

1. This type of furnace is expensive and requires a large installation space.

Since large quantities of firebricks are used, impurity contamination from the bricks is likely to occur.

The amount of moisture increases, leading to deterioration of the properties of the object to be fired and the deterioration of the heater.

The life of the furnace structure is short due to repeated heating and cooling.

Also, energy loss due to cooling is large.

■1st mark 11- This invention was made to solve the above-mentioned problems, and it is possible to achieve compactness, to be able to bake the object for a longer time than the high temperature range of the heating furnace, and to prevent impurities from the bricks. It is an object of the present invention to provide a ceramic firing apparatus that causes less contamination, can improve the characteristics of a sintered body, and can extend the life of a furnace body and heater.

To 11 1E Therefore, in the present invention, a setting zone in which the object to be fired is placed, a heating zone for sintering through the object to be fired, and a take-out section for taking out the ceramic sintered body after sintering are arranged in order in the vertical direction, The gist of the present invention is a ceramic firing apparatus in which shutters that can be opened and closed are provided between a setting zone and a heating zone, and between a take-out section and a heating zone.

A setting zone 16, a heating zone 17, and a take-out part 18 are arranged in order in the vertical direction. The setting zone 16 is a part where the object to be fired 7 is placed. The heating zone 17 is a part where the object 7 to be fired is passed through and fired. The take-out part 18 is a part from which the ceramic sintered body is taken out after sintering.

A lower shutter 15 is provided between the setting zone 16 and the heating zone 17. Further, an upper shutter 9 is provided between the take-out section 18 and the heating zone 17.

The object to be fired 7 can be sintered continuously at the same temperature without cooling the heating furnace 1.

Tai 101 FIG. 1 shows a firing device.

First, the structure of this firing apparatus will be explained.

A heating furnace 1 (Z one S 1nter furnace), an upper setting section 2, and a lower setting section 3 are arranged in series.

The heating furnace 1 has a heat insulation [14]. This heat insulating layer 4 is constructed by connecting each of the segmented layers 5a to 5e in the axial direction. This heat insulating layer 4 may have a cylindrical shape, for example. A heating element 6 is set inside each section 1158 to 5e. This heating element 6 may be made of a heat generating material such as tungsten.

The partition layer 5b indicated by hatching in FIG. 1 functions as a high temperature region. That is, the heat generation temperature in the segmented layer 5b is
The heat generation temperature is set higher than that in the other partitioned layers 5a, 5c, 5d, and 5e. The maximum heat generation temperature of the section 115b is set to at least 1400°C or more, for example 1900°C.

The heat insulating layer 4 is provided vertically within the heating furnace 1 . The atmosphere inside the furnace is made of reducing gas or inert gas. The atmosphere inside the furnace can be composed of hydrogen, for example.

The space of the upper setting part 2 has sufficient space for the integral object to be fired 7 to move in the vertical direction. Upper setting section 2
An upper opening 8 is provided on the side surface of the housing. This upper opening 8 can be opened and closed.

An upper shutter 9 is provided between the upper setting section 2 and the heating furnace 1. The upper shutter 9 is configured such that a pair of left and right shielding portions 9a can be closed or opened by an actuator 9b.

A lifting device 10 for the object to be fired 7 is provided above the upper setting section 2 . The pulling device 10 includes a drive roller 11
and a contact roller 12.

The lower end of a high melting point metal live shell 13 is attached to the upper end of the object 7 to be fired. Therefore, the object to be fired 7 is pulled up by the pulling device [1
By operating 0, it is possible to move vertically.

The lower end of the lower setting section 3 is closed. A lower opening 14 is provided on the side of the lower setting portion 3 as required. This lower opening 14 can be opened and closed.

Either the lower opening 14 or the upper opening 8 can be omitted depending on the application.

A lower shutter 15 is provided between the lower setting section 3 and the heating furnace 1. This lower shutter 15 has the same configuration as the upper shutter 9.

The upper shutter 9 and the lower shutter 15 may be of the same type, or may be of different types.

Next, the processing procedure for the integrated object to be fired 7 will be explained.

100 parts of high-purity alumina powder (purity 99.9%), 0.5 part of magnesium sulfate heptahydrate, PVA as a binder
Mix 1 part (polyvinyl alcohol) and make a slip.

(Magnesium sulfate heptahydrate is a grain growth inhibitor.)
The raw material made into a slip is dried with a spray dryer and granulated.

This granulated powder is formed into a tube shape using an isostatic press at a pressure of, for example, 1 ton/Cl112, and then ground into a predetermined shape. The obtained workpiece has, for example, an outer diameter x inner diameter x length of approximately 3 On+mx 27a+mx
It is 1300+m.

This is pre-fired at 1100°C to scatter the binder, and then fired in a hydrogen atmosphere using the above-mentioned firing apparatus.

The segmented layer 5b of the heating furnace 1 has an axial length of, for example, 30 mm.
It is set to 0IIllll. This axial length is
It is smaller than the axial length of the object 7 to be fired. The segmented layer 5b has a high temperature region in which the object to be fired 7 can be fired.

The object to be fired 7 is fired in the following manner.

The object to be fired 7 is held in the lower setting part 3 by a pulling device 10.

The lower shutter 15 is closed. The high melting point metal live shellfish 13 is sandwiched between the lower shutter 15. In this case, the lower setting part 3 is a setting zone 16 for the object 7 to be fired. The lower setting section 3 is sealed and its atmosphere is replaced with air, N2, and H2 in this order.

Both the atmosphere in the lower setting part 3 and the atmosphere in the heating furnace 1 are composed of hydrogen.

The lower shutter 1r shutter 15 is opened, the lifting device 10 is activated, and the object to be fired 7 is pulled upward from the setting zone 16. The object to be fired 7 is pulled upward within the heat insulating layer 4 .

The object to be fired 7 passes through the partition layer 5b of the heating zone 17, as shown in FIGS. 2 to 4.

As shown in FIG. 2, the upper end 7a of the object to be fired 7 passes through the partitioned layer 5b at a speed of, for example, 500! It passes at lll1/hour. Next, as shown in FIG. 3, the intermediate portion 7b of the object to be fired 7 passes through the partitioned layer 5b at a passing speed of 100 mm/hour, for example. Further, the lower end 7C of the object to be fired 7 passes through the section 115b at a passing speed of 500 nun/hour.

In this way, the passing speed of the object 7 to be fired is changed, and the object 7 is sintered within the partitioned layer 5b.

Next, the upper shutter 9 is opened and the object to be fired 7 enters the upper setting section 2. The upper setting part 2 is a take-out part 18 for the object to be fired 7.
functions as

When the upper shutter 9 is closed, the atmosphere in the upper setting section 2 is H.
2, N2, and air are substituted in this order. The object to be fired 7 is taken out from the upper setting section 2.

Note that the flow direction of H2 in the heating zone 17 is opposite to the direction in which the object to be fired 7 passes.

In this way, a monolithic ceramic sintered body, for example a translucent alumina tube, is obtained. The resulting tube has the particle size dependent properties shown in FIG.

In FIG. 5, the horizontal axis indicates the position from the top of the ceramic sintered body. Moreover, the average particle size, radial crushing strength, and diffused (total) transmittance are plotted on the vertical axis.

As already mentioned, the passing speed at the upper end 78 and lower end 7C of the object to be fired 7 is set higher than the passing speed at the intermediate section 7b.

From this, as shown in Figure 5, the average particle diameter of the translucent alumina tube is 20 to 40μ or less, and is set small at the upper and lower ends, but larger at the middle part. . This average particle size-dependent property is characterized by diffusion (
total) transmittance and radial crushing strength.

The diffuse (total) transmittance is small at the upper and lower ends of the translucent alumina tube, and is greater than 95% at the middle. Conversely, the radial crushing strength is large at the upper and lower end portions of the translucent alumina tube, and is small at the middle portion.

On the other hand, FIG. 6 shows the properties of a translucent alumina tube sintered by a conventional manufacturing method.

As is clear from this, conventionally it is not possible to arbitrarily set the diffused (total) transmittance and radial crushing strength by changing the average particle diameter.

Incidentally, the object to be fired 7 is passed through the lower setting part 3 and the heating furnace 1 and taken out from the upper setting part 2.

However, the object to be fired 7 may be fired as follows.

For example, the object to be fired 7 is introduced from the upper opening 8 of the upper setting part 2, passes through the heating zone 17, and then
It can also be taken out from the lower opening 14.

In this case, the upper setting section 2 functions as a setting zone. The lower setting section 3 functions as a take-out section.

Alternatively, the object to be fired 7 may be introduced from the lower setting part 3, passed through the heating zone 17, raised to the upper setting part 2, and lowered again to the lower setting part 3 and taken out from the lower opening 14. good. In this case, the lower setting section 3 functions as a setting and removal section. Furthermore, put the object to be fired 7 from the upper setting part 2 and lower it to the lower setting part 3.
You can return it and take it out.

FIG. 7 shows another embodiment of the firing device.

Above and below the heating furnace 41, there are an upper setting section 42 and a lower setting section 43.
is provided. The heating furnace 41 has a heat insulating layer (firebrick')
30, 31.32. The heat insulating layer 30 is provided with a tungsten heater 30a. The heat insulating layer 31 is provided with an auxiliary heater 31a. The heat insulating layer 32 is provided with an auxiliary heater 32a.

Also, between the heating furnace 41 and the upper setting part 42, there is an upper shield 1r.
A vine 49 is provided. A lower shutter 45 is provided between the heating furnace 41 and the lower setting part 43.

A pulling device 40 is located above the upper setting portion 42 .

The object to be fired 37 is made as follows.

High purity alumina powder with an average particle size of 0.5 μII or less (purity 9
9.9%), 0.5 part of magnesium sulfate hydrate as a grain growth inhibitor, and 1 part of PVA (polyvinyl alcohol) as a binder are mixed, and the mixture is dried with a spray dryer and granulated.

Next, this granulated powder is compressed into 1 ton/Cl using a rubber press.
Pressurize with a pressure of 112 mm, for example, diameter 40 mm x length 200 mm.
A pipe with a diameter of 0I1m to 70mn1x length 2500II1m is formed.

After machining this with a lathe, it is pre-fired at 1100°C.

The object to be fired 37 thus produced is placed in advance through the upper setting part 42 and placed inside the lower setting part 43 (see FIG. 8). In the figure, 56 is a setting zone for the object to be fired 37.

The object to be fired 37 is suspended by a high melting point metal live shell 33.

As shown in FIG. 8, the lower shutter 45 is closed to seal the lower setting section 43. Then, the atmosphere inside the lower setting section 43 is
Air, N2, and H2 are replaced in this order to make the setting zone 56 and heating zone 57 have the same atmosphere.

Thereafter, the lower shutter 45 is opened and the object to be fired 37 is pulled up at a moving speed (passing speed) of, for example, 200 gin/hour. The inside of the heat insulating layer 30 of the heating zone 57 is maintained at a temperature of 1400°C or higher, for example, 1800°C to 1850°C.

As shown in FIG. 9, the object to be fired 37 passes through the heating zone 57 at a constant moving speed. Thereby, the object to be fired 37 is fired continuously and uniformly along its longitudinal direction.

Next, as shown in FIG. 10, the upper shutter 49 is opened and the object to be fired 37 is lifted into the take-out section 58 (upper setting section 42).

Then, the upper shutter 49 is closed again, and the upper setting section 42 is closed again.
teeth,! 5 It becomes a leap state. The atmosphere in the upper setting section 42 is changed to -12, N2, and air in this order.

After that, the ceramic sintered body (material to be fired 37) is removed from the take-out section 5
It is taken out from 8.

Note that the object to be fired 37 may be moved not only upward but also downward.

The characteristics of ceramic sintered bodies, such as translucent alumina, are
It is shown in Table-1.

Table 1 shows examples (No. 1 to 1) made according to the present invention.
8) and examples made by conventional methods (Nos. 9 to 11) are shown. In Table 1, the bending in the examples made according to the present invention is smaller than that in the conventional example.

Note that the conventional method uses a batch furnace.

Further, the embodiment according to the present invention and the embodiment according to the conventional method have the same composition.

Table 2 shows the characteristics of another example made by the method of the present invention.

In this case, 100 parts of high-purity spinel powder (purity 99.9%) with an average particle size of 0.5 μl or less and 5 parts of methylcellulose as a binder are mixed, and the mixture is dried with a spray dryer and granulated.

The granulated powder is then pre-calcined in the same manner as described above, and fired at a moving speed of 100 mm/hour using the apparatus shown in FIG. At this time, the temperature inside the heat insulating zone 130 of the heating zone 57 is 1450 to 1600°C. The properties of the translucent spinel thus obtained are shown below.
It is shown in 2.

As is clear from Table 2, Examples (Nos. 1 to 6) made by the method of the present invention and conventional examples (Nos. 7 to 9)
), the bending of the embodiment according to the present invention is smaller.

Table 3 shows the characteristics of the furnace core tube made as follows.

Alumina (purity 99°9%) 10 with an average particle size of 3 to 4 μm
0 parts, and 0.0 parts of magnesium sulfate salt water as a grain growth inhibitor.
5 parts were added thereto, one item of PVA was heated as a binder, and this was dried with a spray dryer and granulated.

The granulated powder was molded and processed in the same manner as described above.
Calcinate at 00°C. The object to be fired is heated at 50°C in a hydrogen atmosphere.
Firing was carried out at a travel speed of 0 + n/h. Heat insulation layer 3
The temperature within 0 is set at 1750-1800°C.

As is clear from Table 3, the examples (Nos. 1 to 6) produced by the method of the present invention are different from the conventional examples (Nos. 7 to 6).
The bend is smaller than that in 9).

Thus, the firing apparatus has three zones. By opening and closing the upper shutter 9 and the lower shutter 15, it is possible to create a desired atmosphere in each of the three zones. During firing, the atmosphere in the three zones can be made the same, so heating zone 1
7. Prevents changes in atmosphere and temperature. Therefore, it is possible to reliably and continuously fire a long object to be fired.

Further, by providing a pulling device, it becomes possible to continuously move the object to be fired in the vertical direction within the firing device.

11911 ■ Since the high temperature area of the heating furnace is small, the overall size is compact and energy costs are low.

■ In the high temperature range of the heating furnace, the high temperature range enables the firing of long objects to be fired.

■ The amount of furnace bricks used is small, impurity contamination from the bricks is reduced (and the properties of the fired product are improved).

(2) There is no need for a heating-cooling cycle of the furnace, and the lifespan of the furnace body and heater can be extended. There is also less energy loss.

(2) A long object to be fired can be fired continuously without changing the atmosphere and temperature of the heating zone. Long translucent ceramic tubes, furnace core tubes, protection tubes, etc. can be obtained in large quantities at low cost.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the firing apparatus of the present invention, FIGS. 2 to 4 are diagrams for explaining the firing process of the object to be fired,
FIG. 5 is a diagram showing an example of the characteristics of a translucent alumina tube made by the firing apparatus of the present invention, FIG. 6 is a diagram showing an example of the characteristics of an alumina tube made by a conventional apparatus, and FIG. FIG. 7 is a diagram showing another embodiment of the firing apparatus of the present invention, and FIGS. 8 to 10 are diagrams showing the firing process of the object to be fired in another embodiment. 1...Heating furnace 7...Object to be fired
916...Setting zone 17...Heating zone 18...Takeout section 9...Upper shutter 15...Lower shutter Figure 1 Figure 2 Figure 3 Figure 4 Figure 7 7C Figure 5 Position from top edge (mm) Figure 6 Position from top edge (mm)

Claims (3)

[Claims] (1) A setting zone for putting the object to be fired, a heating zone for sintering through the object to be fired, and a take-out section for taking out the ceramic sintered body after sintering are arranged in order in the vertical direction, and the setting zone and heating zone A ceramic firing device that has shutters that can be opened and closed between the opening and the heating zone. (2) A ceramic firing apparatus according to claim 1, which is provided with a device for moving objects to be fired above. (3) The ceramic firing apparatus according to claim 1, wherein the heating element in the heating zone is a tungsten heater.