JPH0610114B2 - Method for manufacturing long ceramic body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for firing a long ceramic body, and is applicable to, for example, a ceramic filter, a ceramic heater, a ceramic kiln tool, an electrode supporting member, and the like.

(Prior art and its problems) In recent years, for example, in ceramic filters, ceramic heaters, ceramic kiln tools, electrode support members, etc., the filtration area, heating area, power generation area, etc. have been increased to improve the performance per unit. There is an increasing demand for them to do so. For this purpose, it is essential to make ceramics longer.

Conventionally, a long ceramics product that requires straightness (dimensional accuracy in the lengthwise direction) is generally so-called fried, in which the upper portion is hooked on a supporting portion and hung and fired. However, in this method, a dimensional difference and a characteristic difference (for example, a difference in porosity) between the suspended upper portion and the suspended lower portion occurred due to the tensile stress due to the weight of the suspended firing.

Further, the long ceramic body was fired in a horizontal position and, after firing, processed into a predetermined size. However, according to this method, since the long ceramic body is bent, it is very difficult to process it with high precision, and the cost is high.

(Problems to be Solved by the Invention) An object of the present invention is to provide a ceramic long member capable of suppressing a dimensional difference and a characteristic difference between one end side and the other end side of the ceramic long member. A method of manufacturing a body is provided.

(Means for Solving the Problem) In the present invention, the length direction of the ceramic elongated body is substantially aligned with the vertical direction, and one end of the ceramic elongated body is the uppermost end, A first firing step of firing the ceramic elongated body at a predetermined temperature; and thereafter, reversing the ceramic elongated body so that the length direction thereof substantially coincides with the vertical direction and the one end is the lowermost end. And a second firing step of firing the ceramic elongated body at a temperature higher than the predetermined temperature in the state of a part.

The vertical direction means a direction in which gravity is applied, and is not limited to the weight direction of a planet, and also includes an artificial gravity direction when artificially generating gravity at a space station or the like.

(Example) FIGS. 1 (A), (B), and (C) are schematic views showing a state in which the long ceramic body 1 is fired in the first firing step, and FIGS. 3B and 3C are schematic views showing a state in which the long ceramic body 1 is turned upside down and fired in the second firing step.

In this example, first, the first firing is performed by any of the methods shown in FIGS. 1 (A), (B), and (C).

In FIG. 1 (A), a collar 4 is attached near the other end 1b of the elongated ceramic body (1), the elongated ceramic body 1 is passed through the through hole 5a of the support 5, and the elongated collar 4 is used. Supports body 1. Thereby, the long body 1 is hung vertically by its own weight. In the example shown in FIG. 1 (B), a hole 7b is provided in the vicinity of the other end 1b of the long ceramic body 1, a hanging rod 6 is inserted into the hole 7b, and the hanging rod 6 is hooked on the supporting portion 5 to make the long ceramic body. Hanging body 1. In the example of FIG. 1 (C), a taper portion is provided on the other end of the long ceramic body 1.
8b is provided, and the taper portion 8b is hooked on the support portion 5 to suspend the elongated ceramic body 1.

Next, after finishing the first firing as described above, the upper and lower sides of the ceramic long body 1 are exchanged, and the other end portions 1b, 8b
Invert so that is toward the bottom. In this state, the second
The second firing is carried out by the method shown in any of the figures (A), (B) and (C). The second firing temperature at this time is higher than the first firing temperature. The firing methods shown in FIGS. 2 (A), (B) and (C) are the same as the firing methods shown in FIGS. 1 (A), (B) and (C), respectively. However, the vertical arrangement of the elongated ceramic body 1 is reversed. That is, in the example of FIG. 2 (A), the collar 4 is attached near one end 1a of the elongated ceramic body 1 to support it. Further, in the example of FIG. 2 (B), one end 1a
A hole 7a is provided in the vicinity, and a support rod 6 is passed through the hole 7a for support. In the example of FIG. 2 (C), one end 1a
The taper portion 8a provided on one side is supported by the taper portion 8a, and the taper portion 8b provided on the other end portion 1b side is located on the lowermost end side. Of course, after the first firing is performed by the hanging method of FIG. 1 (A), the firing may be performed upside down as shown in FIG. 2 (B) and (C), or another combination may be performed. Can also be arbitrarily selected.

According to this example, as described above, after the first firing, the ceramic long body 1 is turned upside down and the second firing is performed at a temperature higher than the first firing temperature. There is a remarkable feature in the creation of.

That is, first, by the first firing, firing of the long ceramic body is advanced to some extent to densify the structure. Of course, especially when the ceramic elongated body 1 is elongated, a large load is applied to the side closer to the other end 1b due to its own weight, so that the length dimension is longer than that of the one end 1a side (the side closer to the lowermost end). And the porosity increases.

However, after this, the elongated ceramic body 1 is inverted upside down for the second firing, so that one end 1a becomes the uppermost end and the other end 1b side becomes the lowermost end. Therefore,
The closer to one end 1a, the larger the load becomes, and since the second firing is performed in this state, the length and porosity on the side closer to one end 1a become larger. As a result, the vertical dimensional difference and the porosity difference in the first firing step are just canceled, and the dimensional difference and the characteristic difference between the one end 1a side and the other end 1b side as a whole are very small. Scale 1
Can be provided. In addition, it is possible to fire a long ceramic body that is longer than before.

Moreover, it is important to make the firing temperature in the second firing step higher than the firing temperature in the first firing step. When the temperature of the first firing step is equal to or higher than the firing temperature of the second firing step, the sintering of the ceramic progresses sufficiently in the first firing step, and the dimensional difference between the top and bottom of the ceramic elongated body 1 and the porosity are increased. This is because the difference is fixed and can no longer be corrected in the second firing step.

The temperature difference between the firing temperature in the first firing step and the firing temperature in the second firing step is preferably 50 to 150 ° C. If the temperature is lower than 50 ° C., the firing proceeds too much in the first firing step, and the effect of correcting the dimensional difference and the like in the second firing step tends to decrease. Also, the difference between the two is 150
If the temperature is higher than 0 ° C, the diameter dimension on the one end 1a side tends to be small in the second firing step, and the overall diameter tends to be long.

In addition, it is advantageous in strength that the firing temperature in the first firing step is equal to or higher than the shrinkage start temperature of the ceramic molded body.

The outer peripheral cross section of the ceramic elongated body may have any shape such as a rectangle, a circle, and a triangle. Further, it may have a tubular shape, and the inner peripheral cross section thereof may have any shape such as a rectangle, a circle, and a triangle.

When the present invention is applied to a ceramics heater, the heating area increases due to lengthening, and when applied to a ceramics filter, the filtration area and filtration rate can be increased, and since the filtration area can be increased, the filtration rate decreases even if the filter is densified. You can avoid it.

Further, according to the present invention, when an electrode supporting member of a fuel cell, particularly SOFC (solid electrolyte fuel cell) is manufactured, the length of the electrode supporting member can increase the amount of power generation per unit, and The production cost can be reduced.

The material, size, shape, and the like of the ceramic long body manufactured according to the present invention can be variously changed, and the molding method of the long body can be a known method such as a casting method, an extrusion method, or a pressing method.

Hereinafter, more specific examples will be described.

20mm ceramic rod (made of ZrO ₂ ) with a length of 800mm
Was extruded and subjected to the first firing at the firing temperature shown in Table 1 as shown in FIG. 1 (B). After this, as shown in Fig. 2 (B), the ceramic rod is turned upside down and the firing temperature
A second calcination was performed at 1600 ° C. Hanging bar 6 (Fig. 2
(See (B)), a 3 mm alumina rod was used. In this example, the shrinkage start temperature is 1250 ° C.

Then, with respect to the ceramic rod 1A (see FIG. 3) manufactured by each example shown in Table 1, the diameter dimension and the porosity after the second firing were measured at three points. The measurement point is one end 1a
The position (a) is 30 mm from the side end, the position (b) is also 400 mm, and the position (c) is 30 mm from the end on the other end 1b side. The results are shown in Table 1.

As can be seen from Table 1, when the first firing is not performed,
When the first calcination temperature is equal to the second calcination temperature (1600 ° C.), the diameter and porosity are very different. Also,
When the first firing temperature is 1450 to 1550 ° C, especially the diameter dimension,
It can be seen that the variation in porosity is small and the material is homogenized.

(Effect of the Invention) According to the method for manufacturing a long ceramic body according to the present invention,
The ceramic long body is fired in the first firing step with one end of the long body being the uppermost end, and after the sintering is advanced to some extent, the one end is referred to as the lowermost end. In this state, the long ceramic body is fired in the second firing step. Therefore, since the load applied to each part of the long ceramic body is reversed between the first firing step and the second firing step, there is a vertical deviation in the diameter dimension, porosity, etc. in the first firing step. Occurrence can be corrected in the second firing step.

Moreover, since the second firing is carried out at a temperature higher than the firing temperature in the first firing step, the sintering of the ceramics has already progressed too much in the first firing step, so that the diameter dimension, the porosity, etc. rise and fall. It will not be impossible to correct it in the second firing step by fixing it with a gap.

Therefore, it is possible to manufacture a long ceramics body having a uniform difference in characteristics such as dimensional difference and porosity between one end side and the other end side.

Further, it becomes possible to manufacture a long ceramic body which is longer than before.

[Brief description of drawings]

1 (A), (B), and (C) are schematic views showing a state in which a long ceramics body is fired in the first firing step, and FIGS. 2 (A), (B), and (C), respectively. ) Is a schematic view showing a state where the ceramic long body is being fired in the second firing step, and FIG. 3 is a front view for explaining a measurement position on the ceramic rod 1A. 1 …… Ceramic elongated body 1a …… One end, 1b …… The other end 4 …… Collar, 6 …… Hanging rod 7a, 7b …… Hole, 8a, 8b …… Tapered part

Claims (1)

[Claims] 1. The ceramic elongated body is kept at a predetermined temperature while the longitudinal direction of the elongated ceramic body is substantially aligned with the vertical direction and one end of the elongated ceramic body is the uppermost end. A first firing step in which the ceramics are fired, and then the ceramics elongate body is turned over so that the length direction thereof substantially coincides with the vertical direction and the one end is the lowermost end, and And a second firing step of firing the long body at a temperature higher than the predetermined temperature.