JPS5848500B2 - Oriented sintered body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly consists of zinc oxide consisting of needle-shaped, strip-shaped, or plate-shaped particles having a specific relationship with the crystal orientation. This relates to an oriented sintered body in which two crystallographic crystal planes are aligned in the same direction.

Generally, a sintered body is an aggregate of minute particles, and the crystallographic orientation of each particle is oriented in a tenonally disordered direction, exhibiting isotropy as a whole.

For this reason, even if a substance exhibits crystal anisotropy, the sintered body exhibits isotropy as described above.

Isotropy is both an advantage and a disadvantage as a sintered body.

The advantage is that, for example, isotropic materials can be constructed without considering orientation, while the disadvantages are, for example, when viewed locally, they can be oriented in different directions. As the microcrystalline particles are adjacent to each other, stress is generated at their joints, which ultimately leads to performance deterioration.

The present invention provides an oriented ZnO sintered body in which the specific crystallographic orientation of each particle constituting the sintered body is oriented in a certain direction,
oZnO, which enables new applications utilizing its anisotropy, belongs to a hexagonal crystal system and has anisotropy due to this.

The orientation of the oriented ZnO sintered body according to the present invention is determined by a certain process, and the orientation can be easily determined and processed. Furthermore, since the crystal axis is oriented in a certain direction,
It has anisotropy in its properties, and it is a material that can be used for new applications that utilize this anisotropy.

As will be described later, the manufacturing method thereof has much in common with conventional sintered bodies, and therefore conventional equipment can be used.

The oriented ZnO sintered body of the present invention has ZnO having a specific shape.
The main raw material is nO particles.

The shape of ZnO particles is amorphous, needle-like, plate-like, hexagonal plate-like,
There are various other shapes, but it is necessary that the crystal orientation of the particles has a specific relationship with the crystal grains, such as needle-like, plate-like, and hexagonal plate-like shapes.

For example, when Zn is oxidized at a temperature of 500°C to 1350°C to produce microcrystalline particles, strip-like or thin-plate-like ZnO particles as shown in Figure 1 are obtained, and the flat-looking ZnO particles shown in Figure 1 are obtained. A unique ZnO particle having one (110) plane is obtained.

When this particle is used as the main raw material, the (110) of ZnO
An oriented ZnO sintered body in which --cifi is arranged in a certain direction is obtained.

In addition, ZnO particles made at a temperature of 1400°C or higher are
As shown in FIG. 2, it is ideally considered to have a hexagonal plate shape, and the hexagonal plate surface corresponds to one (001) surface.

When such ZnO particles are used as the main raw material, ZnO
Orientation Z in which one (001) face of the crystal is aligned in a certain direction
An nO sintered body is obtained.

The method for producing an oriented ZnO sintered body according to the present invention is as follows.

Desired subcomponents are added to ZnO powder having a specific shape, and thoroughly mixed by soaking in a medium such as water or alcohol.

The obtained mud-like mixture is shaped by uniaxial pressure, and the shaped body is fired in an appropriate atmosphere.

The aligned orientation planes of the sintered body obtained in this way are perpendicular to the uniaxial pressing direction during shaping, and the orientation axis can be easily determined. Although similar results can be obtained by using a wet method, the wet method is superior when handling methods and environment are taken into account.

It is desirable that the particle size of ZnO be larger, but if the particle size is 0.1 μ or more, an orientation of about 50% can be obtained.

The pressure used for molding is determined depending on the desired degree of orientation and density, but may range from 100 kg/i to several tons/i.
Cr? The larger the grain size after sintering, the more desirable it is, but in order to obtain a degree of orientation of about 50% (
The size of this is preferably about 5μ.

Although it is not clear why a small amount of sub-compound is effective, it is thought that it precipitates at grain boundaries and improves orientation when promoting grain growth.

As mentioned above (the degree of orientation of the oriented ZnO sintered body obtained in this way is 50 to 80 coefficients, but when the sintering temperature is increased to produce a sintered body with a large grain size, the degree of orientation becomes 90 coefficients or more) This has been confirmed.

The degree of orientation is calculated by calculating the X-ray diffraction intensities htoo and h002 of (ioo) and (002) of the aligned planes and using the following formula. h
This is the value of loo/ho02.

The oriented ZnO sintered body obtained by the method described above has various characteristics due to its anisotropy, and is a novel material with new applications.

A conventional example (Example 1) and examples of the present invention (Examples 2 to 5) are shown below.

Example 1 Using ZnO powder having a crystal shape as shown in the electron micrograph of Fig. 1, C and alcohol were added, wet mixed, and molded at a pressure of 1000 kg/1.
It was fired at 1350'C to obtain a sintered body with a crystal grain size of about 2μ.

The degree of orientation of the (110) plane of this sintered body was 30%.

As mentioned above, the degree of orientation is low in Example 1, but as shown in the example below, it can be seen that the product to which a small amount of subcomponent is added according to the present invention shows a very high degree of orientation. ○Example 2 Example 1 Using 99.7 moles of ZnO powder used in C. to obtain a sintered body with a crystal grain size of approximately 30 μm and a (110) one-plane orientation degree of 65.

Example 3 To the ZnO-Bi203 mixture used in Example 2, 0.3% of Bed was added and treated in the same manner as in Example 2 to give a crystal grain size of about 65μ (IIO). )
A sintered body with a degree of orientation of about 80 degrees on one side was obtained.

Example 4 The same process as in Example 3 was carried out except that ZnO powder having the crystal shape as shown in the electron micrograph of FIG. 2 was used in place of the ZnO used in Example 3. A sintered body with a grain size of about 70 μm and a (001) orientation of about 80% was obtained.

Example 5 Using the pre-shaped body obtained in Example 4, 1350℃, 150kg/a
Hot press sintering was carried out under the conditions of IT to obtain a dense sintered body with a crystal grain size of about 120 μm.

The orientation degree of one surface (ooi) of this sintered body was about 95φ.

As is clear from the above, the present invention has the following remarkable effects.

(1) In the oriented sintered body according to the present invention, the crystal orientation is related to the orientation of the electrical properties, thus making it possible to improve the electrical properties. (2) In the conventional sintered body, the mechanical Because the grains had anisotropy and the orientations were not uniform, different orientations faced each other at the grain boundaries, leading to deterioration of strength, but the oriented sintered body according to the present invention does not Never.

(3) The degree of orientation is greatly improved by adding a small amount of preservatives.

Claims (1)

[Claims] 1 Mainly composed of zinc oxide consisting of needle-shaped, strip-shaped, or plate-shaped particles that have a specific relationship with the crystal orientation, and a small amount of secondary particles are added to ensure that the specific crystal planes of each particle are highly aligned in the same direction. A homozygous sintered body characterized by being arranged in an array.