JPS5869780A - Method of baking ceramic formed body - 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 The present invention relates to a method of packing porcelain molded bodies into a box and firing them, and in particular, a firing method suitable for firing a large number of porcelain molded bodies with large outer diameters and thin walls. It is related to.

Porcelain is obtained by firing an unfired molded body formed into an appropriate shape. This firing step is typically performed in the manner shown in FIG. 1 or 2.

That is, as shown in FIGS. 1 and 2, I! ! 1
is prepared, a plurality of molded bodies 2 are packed therein, and sintered 11s is obtained by firing at, for example, 1250 to 1400°C for 0.5 to 3 hours. The material of the box 1 is usually selected from a material that does not react with the molded body 2, and is made of, for example, a porcelain material such as mullite, alumina, or a mixture of mullite and alumina.

Porcelain used for electronic components is often prepared in the form of a plate, and therefore the molded body 2 is also in the form of a plate. As a method for packing such a plate-shaped molded body 2 into a box 1, there is a method shown in FIG. 1 or FIG. 2. The first WA is a so-called stacking process in which a plurality of plate-shaped molded bodies are stacked upward and swelled. In Fig. 2, a plurality of molded bodies 2 are arranged horizontally, and each part of the molded bodies 2 is separated! ! ! This is what is called horizontal packing, in which the pieces are packed so that they are in contact with the bottom of 1. Among these methods, the method shown in Fig. 2 has a high packing index of the compact 2 and is optimal in terms of productivity, but in the case of a compact with a large outer diameter and thin wall thickness, it is difficult to Shrinkage occurs in the molded body 2 after firing.
Obtained from. The sintered body may fall over. In addition to this falling phenomenon, a part of the molded body 2 is in contact with the bottom of the box 1, so even if "warpage" occurs during firing, there is no way to correct it; Since only the effect of increasing the size will work, a large "warp" will occur in the obtained sintered body.

-4- In other words, JR2rjA's method does not involve any horse-building to prevent ``sledding,'' but rather allows the horse to continue to cause ``sledding.''
Only Ja lumps are provided to the molded body 2 or the sintered body. Therefore, the appearance of the sintered body is not only desirable, but also poses a serious problem in practical use. Therefore, conventionally, in the case of a molded body having a large outer diameter and a thin wall, the method shown in Fig. W41 is used.

However, this so-called stacking in Fig. 1
Compared to the horizontal packing shown in the figure, the packing index is reduced by half, and the number of molded bodies 2 packed at once is reduced, resulting in a large wm in terms of productivity. Also, even in the case of Figure 1,
There are fewer causes that actively cause "warpage" than in the case shown in Figure 2, but there is no means to proactively prevent warpage, and it is more or less completely possible to prevent "warpage" from occurring. do not have.

Therefore, the main object of the present invention is to provide a method for firing such an IIA molded body, which uses the packing method with a high packing index shown in FIG. It is to be.

In this invention, a major ** is that a bottom plate made of an unfired molded body is laid on the bottom of the box.

Embodiments of the invention having this feature will be described in detail below with reference to the drawings.

FIG. 3 shows an embodiment of the invention. FIG. 4 is a plane view taken along line 11ir-4 in FIG. 3.

For box 1, figure 111 and figure 21! ! A device similar to the conventional example shown in 1 is used. A bottom plate 3 is laid on the bottom of the box 1. The bottom plate 3 is prepared from an unfired molded body,
A material that does not react with the molded body 2 to be fired is selected. Preferably, the bottom plate 3 has the same or similar composition to the molded body 2. Also, with 3 floor plates! ! In order to make it easier for the bottom plate 3 to soak against the bottom of the box 1, it is preferable to spread bedding powder 4 between the molded body 2 and the bottom plate 1. It is preferable to spread a bedding powder 5 to prevent a reaction with. On such a floor plate 3, a plurality of plate-shaped porcelain molded bodies 2 are placed one on top of the other in an upright state. This is so-called vA packing. Then, a pair of blocks 6 are arranged so as to sandwich the ends of the plurality of molded bodies 2 stacked in this manner. The material of the block 6 is selected to be the same as or similar to the material of the box 1.

That is, the prong 6 may be made of a material that does not react with the molded body 2. When the blocks 6 are arranged, it is preferable that the plurality of molded bodies 2 be slightly compressed.

The molded body 2 is fired in the state shown in the third WA and FIG. At this time, as the molded body 2 is sintered, the molded body 2 or the sintered body shrinks, and at the same time, the bottom plate 3 holding the molded body 2 underneath also contracts. Therefore, the blocks 6 that sandwich the molded body 2 at both ends move inwardly as the bottom plate 3 contracts, and the molded body 2 remains sandwiched between the pair of blocks 6 until its sintering is completed. In this way, the molded body 2 or the sintered body
Since it does not fall down as it contracts and is compressed appropriately by the block 6, it is possible to obtain a sintered body with small warpage even if the molded body has a large outer diameter and a thin wall. can. In addition, since it is packed in a machine, it has a high packaging index and is suitable for mass production.

Hereinafter, specific examples will be described along with comparative examples.

Example First, a molded body of barium titanate-based semiconductor porcelain having a diameter of 24.5 mm and a wall thickness of 1.00 mm was prepared. This was packed into a box 1 as shown in 11311 and FIG. 4, and fired in a batch furnace at 1350° C. and opened at 1 o'clock to obtain semiconductor porcelain. The semiconductor porcelain obtained in this way is
Thirty sintered bodies were randomly selected and the "warpage" of each sintered body was measured. This "sled" test was conducted as follows. As shown in FIG. 5, the wall thickness t at three points of the sintered body 7 is 1. t
2. Measure t3 with a micrometer and find the average value T
Find I-(t i +t 2+t 3)/3. Also,
As shown in FIG. 6, the apparent total thickness T2 of the sintered body 7 including the warpage is measured using a dial gauge.

The difference Ts-T2-71 is defined as "warpage". The result of this test is x-0,07am, S-0,01
It was 3g+s. Here, X is n-30 [sled J
The average value of Ts, S is its standard deviation, and it was found that the "warp" was extremely small and the variation thereof was also small.

Comparative Example 1 Semiconductor porcelain was obtained in the same manner as in the example by stacking the same molded bodies as in the example in 10 layers as shown in FIG. Thirty pieces of the obtained semiconductor porcelain were randomly sampled, and the "warp" was measured in the same manner as in the example. As a result, X-0,1
5sa, s -0,037m5.

Comparative Example 2 The same molded bodies as in the example were packed horizontally as shown in FIG. 2, and semiconductor porcelain was obtained in the same manner as in the example.

Thirty pieces of the obtained semiconductor porcelain were randomly sampled, and the "warpage" was measured in the same manner as in the example. As a result, X-0
, 35 m5, and $-0,015 mm, and could not be put to practical use at all.

As is clear from these Examples and Comparative Examples, the method shown in Comparative Example 1 does not cause much warpage, but is still inferior to the Examples, and furthermore, in terms of productivity, the packing index is low. , there is an opening question. The method shown in Comparative Example 2 has extremely large "warpage" and cannot be put to practical use. On the other hand, the products shown in the examples have less "warp" and less variation, and are also excellent in mass production.

As described above, according to the present invention, since the bottom plate and the block are used, it is possible to prevent the molded body or the sintered body from falling down or "warping", and therefore the porcelain sintered body is practically excellent with less "warpage". can be obtained. Also, magnetic like this! I! Since horizontal packing is possible while maintaining the quality of the sintered body, a method with excellent mass productivity can be obtained.

Note that this invention is not limited to the barium titanate-based semiconductor porcelain shown in the above embodiments, but can also be applied to barium titanate-based dielectric porcelain, alumina porcelain, etc., regardless of the composition thereof.
Equally applicable.

Furthermore, during firing, the bottom plate used in this invention has the following properties:
It is preferable that the material shrinks in the same way as the molded product. From this point of view, the composition of the pedestal and its geometry will naturally be determined.

[Brief explanation of drawings]

1 and 2 respectively show conventional examples. FIG. 3 shows an embodiment of the invention. Figure 4 is a 1liIIIi diagram along the line -mV in Figure 3. Figure 5 shows “
Indicates the point at which the wall thickness of the sample is measured in the warpage test. Figure 6 shows the apparent total wall thickness including one warp of the sample in the warp test. In the figure, 1 is a box, 2 is a molded body, 3 is a floor plate, and 6 is a 70
It's Tsuku. Patent applicant: Murata Co., Ltd.-Sakusho Figure 1 Figure 5

Claims (2)

[Claims] (1) In a method in which a porcelain molded body is packed in a box and fired, a bottom plate made of an unfired molded body is laid on the bottom of the box, and a plurality of plate-shaped porcelain molded bodies are stood up on the bottom plate. A method for firing a porcelain molded body, characterized in that firing is carried out in a state in which a pair of blocks are arranged so as to sandwich the ends of a plurality of stacked porcelain molded bodies. (2) The method for firing a magnetic 11IR body according to claim (1), wherein the bed plate has a layer of bed powder added to both sides thereof.