JPH09278535A - Production of ceramic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ceramic excellent in piezoelectricity and mechanical strength etc., even if subjected to low-temperature baking, by calcinating stock powder with the particle size below a specified level at a temperature comparable to the baking temperature or higher followed by grinding and then baking. SOLUTION: First, stock powder such as of PbO, SrCO3 , ZnO, SnO2 , Nb2 O5 , TiO2 , ZrO2 and/or MnCO3 is ground so as to be <=0.5Lμm in particle size using e.g. a ball mill. Secondly, the ground powder is calcined at a temperature comparable to the baking temperature or higher and then ground so as to be <=0.5μm is particle size. Thirdly, a binder is added to the resultant powder followed by homogeneous mixing, and the resultant mixture is molded to a desired shape. Finally, the molding is heat-treated to burn off the binder and then baked to obtain the objective ceramic. By this method, because the particle size is small and the temperature of the calcination is comparable to or higher than the baking temperature, the rate of reaction is raised and the crystallinity of the stock is improved, thus obtaining the objective ceramic having electrical properties comparable to those of ceramics produced by high-temperature baking and excellent in mechanical strength.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing ceramics such as piezoelectric ceramics.

[0002]

2. Description of the Related Art Conventionally, calcination of raw material powder has been performed at a temperature lower than the firing temperature.

[0003]

The particle diameter of the raw material powder is 1.
As it becomes as small as 0 μm or less, the firing temperature can be lowered. However, in the piezoelectric material, when the raw material powder has a small particle size and is fired at a low temperature, the piezoelectricity is low,
It was difficult to obtain high strength and high output ceramics.

Therefore, an object of the present invention is to provide a ceramic exhibiting excellent piezoelectricity even at low temperature firing and capable of high strength and high output.

[0005]

In order to achieve this object, the present invention is to calcinate a raw material powder having a particle size of 0.5 μm or less at a temperature equal to or higher than a calcining temperature, pulverize and calcinate. By making the particle size of the raw material powder fine and making the calcination temperature equal to or higher than the firing temperature, the reaction rate is increased and the crystallinity is improved. It is possible to obtain ceramics that exhibit high properties and have high strength as the crystal grain size becomes finer.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is one in which a raw material powder having a particle diameter of 0.5 μm or less is calcined at a temperature equal to or higher than the firing temperature, pulverized and then fired. If the particle size of the raw material powder is made fine and the calcination temperature is equal to or higher than the firing temperature, the reaction rate is increased and the crystallinity is improved. Further, it is possible to obtain a high-strength porcelain as the crystal grain size becomes finer.

According to the second aspect of the present invention, a lead-based material is used as the raw material powder, and the raw material powder is calcined at a temperature equal to or higher than the firing temperature by making the particle diameter fine. Also, since the flying amount of the lead component is small and a powder having excellent crystallinity can be obtained, it is possible to obtain a high-output and high-strength ceramic having good piezoelectricity even when fired at a low temperature.

According to the third aspect of the invention, the particle size of the pulverized powder after calcination is set to 0.5 μm or less. Can be fired at.

An embodiment of the present invention will be described below. (Embodiment 1) First, as starting materials, PbO, Sr
CO ₃ , ZnO, SnO ₂ , Nb ₂ O ₅ , TiO ₂ , Zr
Using O ₂ and MnCO ₃ , Pb (Zn _1/3 Nb _2/3 ) _0.06
(Sn _1/3 Nb _2/3 ) _0.12 Ti _0.42 Zr _0.40 O ₃ +0.5
Weighed so as to be wt% MnO ₂ . Next, water, a dispersant and the like were added to these raw materials and wet-mixed with a medium stirring mill or a ball mill so that the mixed particle diameter was as shown in (Table 1).

[0010]

[Table 1]

Next, a slurry is prepared from this mixed powder,
After drying, the powder was put in a magnesia porcelain crucible as it was, and calcined for 2 hours under the temperature condition of (Table 1). After crushing, wet crushing was performed with a ball mill or a medium stirring mill under the same conditions as when mixing. After drying, a binder was added, and the mixture was homogeneously stirred with a grinder, and then sized using a 32 mesh sieve. This powder was molded into a disk having a diameter of 13 mm and a thickness of 1 mm at a pressure of 70 MPa. Next, this molded product was heat-treated in air at 700 ° C. to incinerate the binder. After incineration of the binder, to prevent scattering of lead components, 1100 to 1200
Firing was performed in the air at ℃. Next, this sintered body was flat-polished to a thickness of 0.3 mm, and the electrodes were vacuum-deposited with Cr-Au.
I attached. Polarization is 3kV / m in 150 ° C silicon oil
The direct current of m was applied for 30 minutes. Moreover, the piezoelectric constant was measured by the resonance-antiresonance method. The results are shown in (Table 1). As is clear from (Table 1), in the conventional method, the piezoelectric characteristics that cannot be obtained unless the firing temperature is 1290 ° C. or higher, but the piezoelectric ceramics according to the present embodiment are pulverized to a mixed particle size of 0.5 μm or less. When pulverized to a particle size of 0.5 μm or less by calcination at a temperature equal to or higher than the calcination condition, 1
It can be seen that even in the case of low temperature sintering at 100 ° C., the dielectric constant is 1270 or more, the coupling coefficient is 0.58 or more, and piezoelectricity higher than that of the conventional manufacturing method can be obtained.

More preferably, by setting the mixed particle size to 0.2 μm or less and the particle size of the powder after calcination to 0.2 μm or less, a piezoelectric ceramic having further excellent piezoelectric characteristics can be obtained.

Note that the composition in this embodiment is an example, and PbO-TiO ₂ -ZrO _2- (Zn _1/3 Nb) is also used.
_2/3 ) O ₂ , PbO-TiO ₂ -ZrO _2- (Mg _1/3 Nb
_2/3 ) O ₂ , PbO-TiO _2- (Ni _1/3 Nb _2/3 ) O ₂ ,
Similar effects were obtained also for materials containing lead such as PbO—TiO ₂ —ZrO ₂ — (Sn _1/3 Nb _2/3 ) O ₂ system, that is, ceramic materials that generate solid-state reaction.

[0014]

As described above, according to the present invention, for example,
Ceramic composition is PbO-ZrO _Two-TiO_TwoSystem
In the case of a piezoelectric material containing lead-based materials, the crystallinity is excellent at the calcination stage.
It is possible to obtain
Even if the obtained sintered body is sintered at low temperature,
It has high output and high strength with good piezoelectricity
Of.

Claims (3)

[Claims] 1. A method for producing ceramics, characterized in that a raw material powder having a particle diameter of 0.5 μm or less is calcined at a temperature equal to or higher than a firing temperature, pulverized, and then fired. 2. The method for producing ceramics according to claim 1, wherein the raw material powder is a lead-based material. 3. The particle size of the pulverized powder after calcination is 0.5.
The method for producing ceramics according to claim 1, wherein the ceramics has a thickness of not more than μm.