JPH11228237A - Setter for sintering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a setter used for sintering, not requiring a spacer and not deformed. SOLUTION: This setter 1 for sintering comprises a ceramic plate having parallel upper and lower surfaces, and has depressions 3 for receiving ceramic powder molded products (articles to be sintered) 5 and sintering the molded products on at least one of the upper and lower surfaces. A plurality of the setters can be laminated to each other to cover the depressions 3, thus forming the closed space 4. Thereby, the setters can directly be laminated without requiring a spacer. The articles 5 to be sintered can be received in the closed space 4 to inhibit the evaporation of the components of the articles to be sintered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a setter used for firing a green ceramic body.

[0002]

2. Description of the Related Art Piezoelectric ceramics and the like using PZT (PbZrTiO ₃ ) as a raw material are prepared by molding a predetermined ceramic raw material powder, setting the powder on a firing setter, and setting the powder to 800-140.
It is made by firing in a firing furnace at 0 ° C. However, when a PZT piezoelectric ceramic containing a low-melting point, low-boiling point element, for example, Pb, containing a low-melting point, low-boiling point element is fired by an ordinary flat-plate setter, part of Pb evaporates to the surroundings during firing, and the composition after firing changes. was there.

When a large number of objects to be fired are fired at one time, the setters are stacked. However, there is a problem that a spacer is required for stacking and it takes time to attach and detach the setters. Furthermore, in order to stack and store many setters in the firing furnace, it is necessary to reduce the thickness of the setters,
When the setter is made thinner, there is a problem that the setter is bent and deformed by heat during firing.

[0004]

SUMMARY OF THE INVENTION The present invention solves the conventional problems, and provides a setter which has a small change in composition of an object to be fired, does not require a spacer when firing a large number of objects to be fired, and is not deformed. The purpose is to:

[0005]

The sintering setter of the present invention is made of ceramics and has a plate shape having upper and lower surfaces parallel to each other, and at least one of the upper and lower surfaces is formed of a ceramic powder molded body (a body to be fired). Are housed and fired, and a plurality of such layers are stacked to form a closed space with a cover.

The object to be fired set in the recess of the setter of the present invention is fired in a closed space. Therefore, even in an object to be fired containing an element that easily evaporates such as Pb, the element that easily evaporates evaporates in the initial stage of firing, but the vapor pressure of the element in a closed space increases with time, and the element hardly evaporates . When the inside of the closed space reaches the saturated vapor pressure, the evaporation stops, so that the composition change after firing is small.

The setter of the present invention has a concave portion, and the object to be fired is accommodated in the concave portion and fired. For this reason, the setters can be directly laminated without interposing the spacer, and the space and work time required for interposing the spacer are unnecessary. Further, a firing setter in which a plurality of the concave portions are formed on the same surface may be used. This allows
It is not necessary to increase the number of setters to be laminated even when firing a large number of objects to be fired, so that the thickness of the setters does not need to be reduced, and there is no deformation due to heat during firing.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The firing setter of the present invention is made of ceramics and has a plate-like shape having upper and lower surfaces parallel to each other.
At least one of the upper surface and the lower surface has a concave portion in which a ceramic powder molded body (a body to be fired) is housed and fired, and a plurality of the stacked layers are covered with the concave portion to form a closed space.

The bottom surface of the concave portion may be a curved surface or a flat surface. When the object to be fired is a thin plate, the bottom surface of the setter recess is preferably a plane parallel to the upper and lower surfaces of the setter. The mounting surface on which the molded object is mounted may be the bottom surface of the concave portion, or the upper or lower surface of the setter without the concave portion. When the upper surface or the lower surface of the setter serves as the mounting surface, the object to be fired is covered by the concave portion of the setter laminated thereon and stored in a closed space. It is preferable that the surface roughness of the mounting surface on which the object to be fired is mounted is set to Rmax 6.3 μm or less. When the object to be fired sticks to the setter, the mounting surface can be a surface having fine irregularities. By making the mounting surface a fine uneven surface, the true contact area between the object to be fired and the mounting surface can be reduced, which works to suppress image sticking.

The recess may be a setter formed on both the upper and lower surfaces of the setter, or a plurality of recesses may be formed on the same surface. The depth of the concave portion may be larger than the thickness of the object to be fired, but is preferably as close as possible to the thickness of the object to be fired. As a result, the volume of the closed space formed by stacking the setters is reduced, and most of the volume is occupied by the object to be fired. For this reason, with the slight evaporation of the element that easily evaporates from the object to be fired, the closed space reaches the saturated vapor pressure, and the composition change after firing can be reduced.

It is preferable that not only the depth of the recess be made close to the thickness of the object to be fired but also that the shape be slightly larger or similar to the object to be fired. As a result, the proportion occupied by the object to be fired in the closed space further increases, and the closed space reaches a saturated vapor pressure due to the evaporation of a small amount of elements from the object to be fired, and the composition change after firing is reduced. be able to. The whole shape of the setter can be a square plate such as a square or a rectangle, or an elliptical or perfect circular disk. Dimensions are usually 100-150mm in length and width, and 1.0-thickness
It is about 5.0 mm. The depth of the recess is preferably about 5 to 20% of the thickness of the setter.

The ceramics forming the setter are alumina, silica, mullite, magnesia, cordierite,
The material is not particularly limited as long as it is a material such as silicon nitride, silicon carbide, and zirconia that can withstand the firing temperature of the object to be fired. However, the heat resistance temperature is higher when made of zirconia,
It is chemically stable and does not have a problem of reaction with the object to be fired. On the other hand, since zirconia has a high density and a low thermal conductivity, a temperature difference is likely to occur on the setter, and there is a possibility that uneven burning may occur in the fired body.

[0013]

The setter of the present invention has a plate-like shape whose upper and lower surfaces are parallel to each other. At least one of the upper and lower surfaces has a concave portion. Become. The object to be fired is accommodated in the concave portion forming the closed space, and the same setter is stacked thereon, and is heated in a firing furnace. Even if the object to be fired contains an element that easily evaporates due to a rise in temperature due to heating, since the object to be fired is in a closed space, evaporation hardly occurs, and the composition change of the object to be formed is small.

Further, the setter of the present invention has a concave portion, and the object to be fired is accommodated in the concave portion and fired. For this reason, the setters can be directly laminated without interposing the spacer, and the space and work time required for interposing the spacer are unnecessary. Furthermore, by forming a plurality of concave portions on the same surface as a firing setter, it is not necessary to increase the number of stacked setters even when firing a large number of objects to be fired.

[0015] In the setter of the present invention, the wall sectioning the periphery of the concave portion functions as a spacer. The wall surrounds the periphery of the recess and supports the bottom of the recess. For this reason, the thickness of the bottom portion of the setter can be reduced, and even if the bottom portion is reduced, it does not deform due to heat during firing.

[0016]

The present invention will be described in more detail with reference to Examples of the present invention. (Example 1) FIG. 1 shows a cross section in which two sintering setters according to this example are stacked. The firing setter 1 has a concave portion 3 on the upper surface of a plate-like body 2 whose upper surface and lower surface are parallel to each other, and a closed space 4 is formed by stacking. The bottom surface of the recess 3 is parallel to both the upper and lower surfaces of the flat plate 2, and the shape of the opening is rectangular. 5 is a calcined body having a diameter of 25 mm and a thickness of 0.7.
It is a 5 mm PZT molded body.

The firing setter 1 is made of zirconia.
The zirconia powder was put into a mold, press-molded under a pressure of 1 ton / cm ² , and fired in a firing furnace at 1450 ° C. for 2 hours. The dimensions of the setter are 120 mm in length and width and 5 mm in thickness. The dimensions of the recess 3 are 105 mm in length and width and 1 mm in depth. A total of 16 pieces of the object 5 to be baked having the above dimensions were set in the recesses 3 having the above dimensions in four rows in the width direction and four rows in the depth direction so that the side surfaces coincided therewith, that is, the recesses 3 were closed. The setters 1 on which the molded objects 5 were placed one after another so as to form the space 4 were laminated. In addition, the uppermost setter was emptied, the molded object was not placed, and it was used as a lid.

The multi-layer setters were fired in an air atmosphere at 1330 ° C. for 2 hours in a firing furnace. In the case of this embodiment, the volume of the closed space 4 is 1102.
5 mm ³ , and the total volume of the 16 sintered bodies 5 in the closed space 4 is about 1472 mm ³ , so that the closed space 4
The space not occupied by the object 5 to be fired is 9553 mm
³ (9.553 cm ³ ). Space 4 closed in this way
Since the empty space inside is small, the inside of the closed space 4 reaches a saturated vapor pressure due to slight evaporation from the object 5 and cannot evaporate any more. The piezoelectric characteristics were shown. (Embodiment 2) FIG. 2 is a plan view of two firing setters according to this embodiment, and FIG. 3 is a cross-sectional view taken along line AA of FIG. The sintering setter 1 was made of zirconia, and was manufactured by the same process as in Example 1. This setter has a total of 12 recesses 3 in 3 rows × 4 columns on the upper surface of the plate-like body 2, and 12 closed spaces 4 are formed by stacking. Reference numeral 5 denotes a PZT molded body having a diameter of 25 mm and a thickness of 0.75 mm, which is an object to be fired. The concave portion 3 is designed to have a size and a shape in which the fired body 5 can be set just one by one, and has a diameter of 26 mm and a depth of 1 m.
m. A total of 12 pieces of the fired object 5 having the above dimensions are set in the recesses 3 having the above dimensions, and the empty setters 1 are placed thereon so that the side surfaces thereof coincide with each other, that is, the recesses 3 become a closed space 4. Laminated.

This was placed in a baking furnace in an air atmosphere to provide 133
Baking was performed at 0 ° C. for 2 hours. In the case of this embodiment,
The volume of the closed space 4 is 530 mm ³ , and the volume of the object 5 in the closed space 4 is 368 mm ³ . Therefore, the space not occupied by the object 5 in the closed space 4 is 162 mm ³ (0.162 cm ³ ). Since the space not occupied by the fired object 5 in the closed space 4 is narrow, the closed space 4 reaches a saturated vapor pressure due to slight evaporation from the fired object 5 and cannot evaporate any more. The later PZT showed little change in composition and showed good piezoelectric characteristics.

In the sintering setter of this embodiment, since one object to be sintered enters almost one space in one closed space, heat is supplied from all directions and PZT without unevenness in sintering. Could be fired.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view in which two firing setters of Example 1 are stacked.

FIG. 2 is a plan view in which two firing setters of Example 2 are stacked.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

[Description of Signs] 1. Setter for firing 2. Plate-shaped body 3. Recessed part 4. Closed space 5. Object to be fired

Claims (5)

[Claims] An upper surface and a lower surface of a ceramic have a parallel plate shape, and at least one of the upper surface and the lower surface has a recess in which a ceramic powder molded body (a body to be fired) is housed and fired. A baking setter characterized in that the lamination is a closed space in which the recess is covered with a lid. 2. A firing setter according to claim 1, wherein said recess has a bottom surface parallel to said upper and lower surfaces. 3. The firing setter according to claim 1, wherein said recess is formed on said upper surface and said lower surface. 4. The firing setter according to claim 1, wherein a plurality of said concave portions are formed on the same surface. 5. The firing setter according to claim 1, wherein said ceramic is zirconia.