JPH0782043A - Production of ceramic sheet - Google Patents

Abstract

PURPOSE:To prevent the generation of defective appearance caused by the collapse of stacked ceramic green sheets and troubles such as fusion and deterioration in baking. CONSTITUTION:A ceramic green sheet is punched in circular form and several to several tens pieces of the punched ceramic green sheet 1 are stacked one upon another and placed in a baking capsule 3 made of a ceramic material. The stacked ceramic green sheets 1 is topped with a plate-formed weight 2 made of a sintered material of the ceramic material same as the ceramic green sheet. The baking capsule 3 is closed with a lid 4, introduced into a baking furnace and heat-treated to effect the baking and sintering of the ceramic green sheet 1. The weight of the weight 2 is preferably 6-29 times the weight of one punched ceramic green sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a ceramic sheet suitable for producing a thin ceramic sheet such as a piezoelectric ceramic substrate for a piezoelectric buzzer.

[0002]

2. Description of the Related Art A ceramic sheet as a sintered body such as a piezoelectric ceramic substrate for a piezoelectric buzzer is prepared by adding a binder to a ceramic powder and mixing them, and then forming a thin ceramic green sheet by a wet extrusion molding method, a doctor blade method or the like. It is manufactured by punching this into a predetermined shape, stacking a plurality of punched ceramic green sheets, putting it in a firing container that is a container made of ceramic, introducing it with the firing sheath into a firing furnace, and heat treating it. It By this heat treatment, the ceramic green sheet is sintered and a ceramic sheet as a sintered body is obtained.

[0003]

SUMMARY OF THE INVENTION For example, a piezoelectric ceramic substrate is as thin as 25 μm to 200 μm and has a light weight. Moreover, this piezoelectric ceramic requires a binder removal treatment in advance during firing, and vaporization of the Pb component occurs during firing leading to sintering. For this reason,
The light piezoelectric ceramics are moved by the air flow generated by the evaporation of the binder component by the binder removal and the vaporization of the Pb component, and the stacked ceramic green sheets are easily collapsed.

When the ceramic green sheet collapses during firing and is fired as it is, the resulting ceramic sheet as a sintered body is deformed such as warping or waviness, resulting in a poor appearance of the ceramic sheet and being unusable as a product. There is. Therefore, in the past, the shape and dimensions of the firing sheath were matched with the shape and dimensions of the stacked ceramic green sheets, and the stacked ceramic green sheets were stored in the firing sheath without any gaps, or with zirconia rods or the like. Attempts have also been made to surround the stacked ceramic green sheets so that the ceramic green sheets do not move during firing.

However, with these means, not only mass productivity and workability are poor and high productivity cannot be obtained, but also the evaporation of the binder component by the debinder and the escape of the vapor of the Pb component are hindered. There is a drawback that the binder and sintering cannot be performed smoothly. Therefore, an object of the present invention is to provide a method for firing a ceramic sheet in which the stacked ceramic green sheets are less likely to collapse and other obstacles do not occur.

[0006]

That is, according to the present invention,
In order to achieve the above object, a method for producing a ceramic sheet as a sintered body by stacking a plurality of ceramic green sheets of a predetermined shape, introducing these stacked ceramic green sheets into a firing furnace, and heat-treating them A ceramic sheet having the same planar shape as or a larger planar shape than that of the stacked ceramic green sheets and placing a weight made of a sintered body of the same ceramic material and introducing the weight into a firing furnace. A method for manufacturing the same is provided. The weight of the weight is preferably 6 to 29 times the weight of one ceramic green sheet.

[0007]

[Function] By stacking a stack of ceramic green sheets with a weight made of a sintered body of the same ceramic material having the same plane shape or a plane shape larger than that of the sheets and introducing the weight into a firing furnace and firing the sheets. , The weight of the stacked ceramic green sheets is pressed from above so that they do not collapse over the whole. Therefore, the ceramic green sheet is fired in a stable state so as not to collapse. Further, even if the weight is directly placed on the ceramic green sheet, the weight of the weight is made of a sintered body of the same ceramic material as the stacked ceramic green sheets, so that the ceramic green sheet does not deteriorate during firing. As a result, a ceramic sheet having no characteristic fluctuation can be obtained.

As will be apparent from the examples described below, the weight of the ceramic green sheet is 6 times the weight of one ceramic green sheet.
When it is more than doubled, the effect of preventing the collapse of the stacked ceramic green sheets becomes remarkable. However, if the weight is too large, the surface pressure of the stacked ceramic green sheets becomes high, so that the upper and lower ceramic green sheets are likely to stick to each other at the time of firing, so-called a fusion phenomenon easily occurs. This fusion phenomenon is remarkable when the weight of the weight exceeds 29 times the weight of one ceramic green sheet. Therefore, the weight of the ceramic green sheet is preferably 29 times or less.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. As described above, the ceramic sheet as the sintered body is manufactured as follows. First, a binder is added to and mixed with ceramic powder, a thin ceramic green sheet is produced by a wet extrusion method, and this is punched into a predetermined shape. Next, FIG. 1 and FIG.
As shown in FIG. 5, several to several tens of the punched ceramic green sheets 1 are stacked and placed in a firing sheath 3 which is a ceramic container.

In the present invention, the plate-like weight 2 which is a sintered body of the same ceramic material is placed on the stacked ceramic green sheets 1. For example, if the ceramic green sheet 1 is a circular sheet, the weight 2 may have a disk shape having the same diameter as that of the ceramic green sheet 1. However, the weight 2 is slightly flatter than the ceramic green sheet 1 as long as it does not lose stability when placed. It may be a large plate.

If the weight 2 alone has sufficient weight, only one weight 2 is used as shown in FIG. 1, for example. If the weight 2 alone does not have sufficient weight, another weight 5 may be placed on top of the weight 2, for example as shown in FIG. The upper weight 5 does not need to be a sintered body of the same ceramic material as the ceramic green sheet 1.

With the ceramic green sheets 1 stacked in the firing sheath 3 as described above, the lid 4 is placed on the firing sheath 3, and the lid 4 is introduced into a firing furnace and heat-treated to obtain the ceramic green sheet 1. Baking to sinter the ceramic green sheets. After that, the firing sheath 2 is taken out of the firing furnace, the lid 4 is opened, and the sintered ceramic sheet is taken out of the lid 4, thereby completing the process. 1 and 2, for the sake of convenience, only one stack of the stacked ceramic green sheets 1 is stored in the firing sheath 3, but in reality, one firing sheath 3 is used.
A few to several tens of ceramic green sheets 1 are stored in the.

Next, a more specific embodiment of the present invention will be described. Example 1 A piezoelectric ceramic green sheet having a thickness of 60 μm was prepared by a wet extrusion method by adding and mixing a binder containing methyl cellulose as a main component to a piezoelectric ceramic raw material powder containing lead zirconate titanate as a main component. This was cut into a circle having a diameter of 31 mm to produce a circular green sheet-shaped ceramic green sheet. Fifty sets of thirty stacked ceramic green sheets are prepared and housed in a firing sheath, and a disc-shaped weight having a diameter of 31 mm made of a sintered body of the piezoelectric ceramic is placed thereon and fired. The sheath of the sword was put on the lid, introduced into a firing furnace, and fired.

Here, five weights each having a different weight from 1.00 g to 6.25 g were used, and for comparison, those without a weight (weight weight = 0 g) were also fired. . After firing, appearance defects due to collapse and defects due to fusion were examined, and the results are shown in Table 1 for each weight of the weight used. In addition, the number on the right side of the weight column in Table 1 is
The weight ratio of one weight of the ceramic green sheet is shown.

[0015]

[Table 1]

(Embodiment 2) 10 sheets of the same ceramic green sheets as in the above-mentioned Embodiment 1 were stacked and no weight was placed on them, 2.00 g of weight was placed on them, 6.30 g
Each of the weighted products was fired in the same manner as in Example 1 above. After firing, the appearance defect due to collapse and the defect due to fusion were examined, and the results are shown for each weight of the weight used.
It was shown to. The number on the right side of the weight column in Table 2 indicates the weight ratio of the weight to one ceramic green sheet, as in Table 1.

[0017]

[Table 2]

(Embodiment 3) The same ceramic green sheets as in Embodiment 1 are stacked 30 sheets, and no weight is placed on this, or a weight of zirconia is placed on the weight of piezoelectric ceramic, and the total weight is 2.00 g and 6.30 g were fired in the same manner as in Example 1 above. After firing, appearance defects due to collapse and defects due to fusion were examined, and the results are shown in Table 3 for each weight of the weight used. The number on the right side of the weight column in Table 3 indicates the weight ratio of the total weight of the weight to one ceramic green sheet, as in Table 1.

[0019]

[Table 3]

As is clear from the above results, the weight of the ceramic green sheets is about 6 times the weight of one ceramic green sheet, regardless of the number of stacked ceramic green sheets.
When it is more than doubled, the effect of preventing the collapse of the stacked ceramic green sheets suddenly becomes remarkable. On the other hand, the so-called fusion bonding phenomenon, in which the upper and lower ceramic green sheets are burned together during firing, becomes remarkable when the weight of the weight exceeds 29 times the weight of one ceramic green sheet. Therefore, the weight of the ceramic green sheet 1
It can be seen that the weight per sheet is preferably 6 to 29 times.

[0021]

As described above, according to the present invention, the stacked ceramic green sheets are unlikely to collapse, so that it is possible to prevent appearance defects such as warpage and undulation of the ceramic sheets, and to perform firing. It is possible to obtain an effect that a ceramic sheet having stable characteristics can be manufactured with a high yield without causing problems such as fusion at the time and deterioration of the ceramic sheet.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a stacked ceramic green sheet housed in a firing sheath in an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a stacked ceramic green sheet housed in a firing sheath in another embodiment of the present invention.

[Explanation of symbols]

 1 Ceramic green sheet 2 Stack 3 Sinter for burning 4 Saya lid for sintering 5 Stack

Claims (2)

[Reference number] 0050101-01 [Claims] 1. A method for producing a ceramic sheet as a sintered body by stacking a plurality of ceramic green sheets of a predetermined shape, introducing the stacked ceramic green sheets into a firing furnace, and heat-treating them to obtain a ceramic sheet as a sintered body. A ceramic sheet characterized by having the same plane shape as that of the same sheet or a plane shape larger than that and placing a weight made of a sintered body of the same ceramic material and introducing the weight into a firing furnace. Method. 2. The method for producing a ceramic sheet according to claim 1, wherein the weight of the weight is 6 to 29 times the weight of one ceramic green sheet.