JPH05117011A - Method for burning ceramic material of thin plate - Google Patents

Abstract

PURPOSE:To prevent warpage and bending of burnt material of thin plate by placing members made of ceramics having a higher coefficient of thermal expansion than an outer mold made of ceramics having a low coefficient of thermal expansion, sandwiching a thin plate material between the members made of ceramics and burning. CONSTITUTION:An outer mold member 1 consists of a ceramics material (e.g. alumina) having a relatively lower coefficient of thermal expansion and members 2 composed of a ceramics material (e.g. magnesia) having a relatively higher coefficient of thermal expansion than the outer mold are put inside the outer mold. A ceramics material 3 of thin plate to be burnt is sandwiched between the members 2. Consequently, when temperature is raised in burning, the amount of the inner members 2 thermally expanded is larger than that of the outer mold member 1, pressure is continuously applied to the sandwiched ceramics material 3 of thin plate to be burnt and the ceramics material of thin plate will not bend. Moreover, the ceramics material of thin plate do not require lying, a great number of thin plates are put, burnt and volatile components such as Pb will not vaporize.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for firing a thin plate ceramic material and a firing jig used therefor. More specifically, the present invention relates to a firing method and a firing jig that prevent a deformation due to firing by firing a thin plate material to be fired while applying pressure.

[0002]

2. Description of the Related Art Conventionally, in the production of ceramics, in particular, in the production of electronic ceramics, for example, piezoelectric ceramics such as PZT, thermistors such as PTC, varistors, ceramic capacitors or ferrites, a thin plate shape is used. It is necessary to bake things, and in such a case, one to-be-baked object was laid on the setter one by one, or several objects were fired. Alternatively, a smooth plate was placed on the object to be fired for restraint and fired. Alternatively, it was fired using a machine called a hot press.

Further, the firing jig is used for mounting an article to be fired, and is generally used to reduce friction caused by fusion between the article to be fired and the firing jig, reaction or shrinkage of the article to be fired. Inorganic powder called sowing powder is sprayed on. When firing is performed by the above method, the article to be fired (thin plate) is warped, and it is often impossible to perform flat firing. In order to prevent this, several sheets were stacked or a restraining plate was placed on the upper part, but there was a problem that the conditions changed between the upper part and the lower part.

Further, since it has to be laid on a flat plate and fired, that is, it bends when it is stood up, so that the area in the furnace cannot be effectively utilized. In addition, when the Pb component and the like were included, the whole had to be put in the sheath. Alternatively, the components may volatilize and the characteristics of the fired ceramics may not be obtained. Alternatively, firing with a hot press requires a great amount of equipment cost, and since only a few sheets can be fired at one time, enormous cost and time are required.

That is, when a thin plate is fired by a conventional firing method, a. Sleds b. Takes up area, c. If the components volatilize or if they are fired with a hot press, there are various drawbacks such as cost and time. Further, as a result of research to find out a method of firing a thin plate in an upright state without using a special jig in order to eliminate defects, the present invention has been achieved.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and a firing method in which deformation or deformation of a thin plate is basically prevented by constantly suppressing or applying pressure during firing. It is intended to provide a jig for that purpose.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned technical problems, and an outer frame made of a ceramic material having a low coefficient of thermal expansion has a thermal expansion coefficient higher than that of the outer frame. A member made of high-ceramic material,
(EN) Provided is a method for firing a thin plate ceramic material, which comprises sandwiching a thin plate material to be fired, and firing, and a firing jig therefor.

[0008]

According to the method for firing a thin ceramic material of the present invention, the outer frame material is made of a ceramic material having a relatively low coefficient of thermal expansion, while the inner frame has a relatively higher coefficient of thermal expansion. This structure has a member made of a ceramic material. Therefore, when the temperature is increased during firing, both the inner member and the outer frame member thermally expand, but the amount of thermal expansion of the inner member is large relative to the amount of thermal expansion of the outer frame member, so it is sandwiched. The difference becomes narrower in the open part, and the sandwiched part is always under pressure. The member having a relatively low coefficient of thermal expansion is preferably one having a smaller creep, for example, alumina or the like. As the member having a relatively high coefficient of thermal expansion, for example, magnesia is suitable.

Therefore, as the temperature is raised for firing, the difference in the amount of thermal expansion further increases, and the pressure applied to the thin plate to be fired increases as the firing process progresses. With this pressure, the sheet is pressed from both sides and does not bend. Moreover, it is not necessary to lay down the thin plates, and a large number of thin plates can be housed in the firing process. Also, because pressure is constantly applied, Pb
Volatile components such as do not escape.

Therefore, the material having a relatively high coefficient of thermal expansion used for the inside can be sandwiched between the sheets to be fired and used. Further, the outer frame having a low coefficient of thermal expansion and the inner member having a high coefficient of thermal expansion may have any structure or configuration as long as the above characteristics can be exhibited, and any structure may be used as long as it is suitable for the structure. You can For example, it can be used in various structures and configurations as shown in FIG.

In FIG. 3, the member 1 is a member having a relatively high coefficient of thermal expansion, and the member 2 is a member having a relatively low coefficient of thermal expansion.

The thin plate ceramic material obtained by the present invention is particularly suitable as a PZT piezoelectric element, a PTC thermistor, and a zirconia substrate.

Next, the method of firing the thin plate ceramic material and the jig for firing the same according to the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

[0014]

EXAMPLE A ceramic thin plate (material ZrO ₂ 3Y ₂ O ₃ ) 3 molded to 10 × 10 × 1 mm was mounted on a firing jig as shown in FIG. 1 and fired. In FIG. 1, the outer frame 1 has a boat shape as shown and is made of alumina. On the other hand, the inner member 2 is provided inside the outer frame 1 in a sandwiched manner as shown in the drawing, and the material thereof is magnesia.
In the meantime, as shown in the figure, the thin plate-shaped objects 3 to be fired are arranged in a standing manner. From this, 25 ℃ to 500 ℃
Up to 500 to 150 at a heating rate of 25 ° C / hour
Up to 0 ° C, the temperature is raised at a heating rate of 120 ° C / hour to 150 ° C.
After holding at 0 ° C. for 2 hours, the temperature was lowered to 25 ° C. at a temperature decreasing rate of 300 ° C./hour. The heating furnace was a molybdenum disilicide type heating element, and was fired in an air atmosphere.

The sled of the obtained thin plate fired product was about 0.1 m.
Within m, the specific gravity was 5.95-5.96. On the other hand, lay thin plates of the same size and composition,
When a fired ceramics plate was placed as a weight on top and fired, the sled became about 2 mm and the specific gravity was
It was about 5.92 to 5.93. Further, in the lower part, the thin plate was cracked due to the load.

Further, a firing jig having a structure as shown in FIG. 2 was prepared. That is, the round outer frame 1 is made of alumina,
Two rectangular parallelepiped fired ceramics 2 made of magnesia are placed in the inside as shown in the figure, and a thin plate forming body 3 to be fired is stood between the two magnesia fired bodies 2 and arranged side by side without a gap. The one having such a structure is placed in a firing furnace and fired.

[0017]

As described above, the above-described effects are obtained by the method for firing a thin plate ceramic material of the present invention. Summarizing them, the following remarkable technical effects are obtained. That is, first, as is clear from the above description, a fired thin plate-shaped ceramics that does not warp and does not bend can be obtained. Secondly, a firing method is provided in which the space can be effectively used because the space can be arranged vertically.
Thirdly, a firing jig was provided in which volatile components such as Pb did not easily fly and did not contaminate others. Fourth, the fired thin-plate fired ceramics are
A firing method that can be obtained with a high density is provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a firing jig of the present invention.

FIG. 2 is a perspective view showing another example of the firing jig of the present invention.

FIG. 3 is a sectional view and a perspective view showing various firing jigs of the present invention.

[Explanation of symbols]

1 Ceramic outer frame having a low coefficient of thermal expansion 2 Ceramic material member having a high coefficient of thermal expansion 3 Thin plate material to be fired

Claims (2)

[Claims] 1. An outer frame made of a ceramic material having a low coefficient of thermal expansion is sandwiched between a member made of a ceramic material having a higher coefficient of thermal expansion and a thin plate material to be fired. A method for firing a thin plate ceramic material, which comprises: 2. A thin plate to be fired having a structure in which a member made of a ceramic material having a higher coefficient of thermal expansion is placed inside an outer frame made of a ceramic material having a lower coefficient of thermal expansion. A jig for firing thin plate ceramic materials for sandwiching and firing the material.