JPS59223275A - Manufacture of high density sintered body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a high-density sintered body. In the production of sintered bodies, since the hot press method sinters while applying pressure, it is necessary to densify the sintered bodies7 (lead fl phosphate (PbZr0.) and lead titanate (PbTi05)). of-
It is used to produce solutions, solid solutions in which part of the lead in the solid solutions is replaced with lanthanum, and sintered bodies such as zinc sulfide and sialon.

The following method (known as the conventional hot press method)

(1) Method of using a mold a) As shown in Figure 1, the sintered raw material powder 3 is placed in a high temperature resistant, high strength mold 1 made of alumina, graphite, SiO, etc. Method of applying pressure from above and below using push rod 2. In this case, heating is carried out by using an external heater for the entire mold or by using an electrically conductive mold and passing an electric current or an induced current through it using high frequency.

, b) When the mold and the sintering raw material react, as shown in FIG. , alumina + Si
A method in which a mold release material 5 made of powder such as O, zirconia, or foil of platinum, tantalum, etc. is interposed and pressure is applied with a push rod 2.

is being carried out.

However, since these methods use uniaxial pressure, 1) the pressure distribution inside the mold tends to be uneven, making it difficult to obtain a uniform product;

2) - Cracks are likely to form inside the blow-molded body, resulting in easy damage and poor product yield.

3)-The shape of the blow-molded body is limited to a simple shape due to uniaxial compression.

There are drawbacks such as.

As a method to eliminate the drawbacks of this method, (2) "Put the sintering raw material powder in a capsule made of a diaphragm made of metal or glass in a pressure-resistant container, or sinter it in advance to 95% or more. A method (hereinafter referred to as the HIP method) has been developed in which an object is housed and heated by passing an inert high-pressure gas such as He or Ar into a pressure-resistant container.

This HIP method is advantageous in that a sintered body is relatively uniform and has a complicated shape because it is sintered under isotropic pressure, but it also has the disadvantage of being shaped.

1) Since an inert high pressure gas such as He or Ar is used as the pressure medium, the equipment becomes large and requires careful maintenance and operation.

2) Since it is necessary to use a capsule made of a metal or glass diaphragm between the pressure medium and the sintering raw material powder, it is necessary to separate the diaphragm after sintering, making the operation complicated.

5) To avoid the use of capsules, they must be pre-sintered until the open pores are eliminated.

The present invention was made to eliminate the drawbacks of the conventional hot press method and HIP method, and its purpose is to enable the use of hot press equipment as is and to easily manufacture products with complex shapes without the need for capsules. The purpose of the present invention is to provide a method for producing a high-density sintered body.

As a result of research to achieve the above object, the present inventors have developed a hexagonal boron nitride (hereinafter referred to as h-BN) table PjiKB20.
．． The layered powder (referred to as solid lubricant; 1) is
The viscosity coefficient is small (less than 0.5 Boise at a temperature of 500°C or higher), and the friction between powders is small. Alternatively, when this is filled together with a pre-sintered molded body and sintered under pressure, the solid lubricant transmits pressure in the same direction, and a uniform, high-density sintered body can be easily obtained, and it also does not have multiple sintered bodies. We have found that it is also possible to manufacture products with different shapes. The present invention was completed based on this knowledge.

The method of the invention uses the surface K of h-BN as a pressure medium.
This method is characterized by using a solid lubricant on which a B2O5 layer is formed, and pressurizing and sintering a molded body of sintered raw material powder or a molded body obtained by pre-sintering the same using a hot press device.

Solid water with a B2O3 layer formed on the surface of h-BH.
u: An oxygen-containing atmosphere in which h-BN powder is moistened, 1
Exclusively in humid air or humid oxygen at 500-1000℃1
Obtained by processing the rod.

The solid lubricant obtained in step t may be filled into the mold, or the sintered powder t2. After filling the h-BN powder together with the IM body or a pre-sintered molded body thereof, heat treatment may be performed at 500 to 1000° C. in air containing water vapor. The shape of the h-BN powder may be any shape such as a plate or one sphere.

Further, a part of a solid lubricant such as h-BN, graphite, mica, molybdenum disulfide, etc. may be mixed with the solid lubricant in which an 8205 layer is formed on the surface of the b-BN powder.

Preliminary sintering of the molded body of the sintered raw material powder is 90% or less sintered.

The method of the present invention is explained with drawings.
1 is a cross section of a hot press device showing an embodiment of the same (however, the heating device is omitted).

A molded body of sintered raw material powder or a pre-sintered molded body 4 is filled into a mold 1 together with a solid lubricant 6 having a B20° layer formed on the surface of h-BH. In this case, the filling direction and position of the molded body may be in any state as long as it is embedded in the solid lubricant 6. Then, the mold 1 is heated and pressurized by the press 1R42. Due to this pressurization, the solid lubricant 6 flows freely and the molded body 4
By applying pressure in the same direction, a uniformly dense sintered body can be obtained.

According to the method of the present invention, since a solid lubricant having an 8205 (melting point 577°C) layer formed on the surface of h-BH is used as a pressure medium, its excellent flow 1 #11 property is achieved, and the sintered powder It can be obtained by applying pressure in the same direction to the molded body or its pre-sintered molded body, and a uniform and highly dense sintered body can be obtained.

In addition, since it does not use inert high-pressure gas such as He or Ar as in the conventional HIP method, the equipment does not need to be large, making it possible to replace the conventional hot press equipment! 1. It can be used easily, and even complex shapes can be easily sintered, resulting in excellent effects.

Example 1゜ 99.99% purity ZnO powder was molded into a cylindrical shape, and this was further hydrostatically pressed at 2 tons/cm2 to form 8 pieces.
In an alumina mold with an inner diameter of 5 cm and an outer diameter of 8α,
HH' was loaded together with BN powder (particle size of 10 microns or less). This was treated at 500°C for 1 hour in an air storm containing steam, then pressurized at 5ooKy/m2 and then heated to 85.0°C for 50 minutes.
Processed in air for an hour. What was obtained was a transparent, high-density (98% or more) ZnO sintered body.

Example 2゜ZnS powder was used in place of the ZnO powder in Example 1, and sintering was carried out in the same manner as in Example 1.

What was obtained was a ZnS high-density sintered body having translucency.

Example 3 The ZnO powder K 2 O of Example 1 and 1 mol % Lip powder were mixed and a molded body was prepared in the same manner as in Example 1. Eight of these molded bodies and a solid lubricant in which B2o3ffi was formed on the surface of the h-BN powder prepared in advance were filled into an alumina mold, and sintered in the same manner as in Example 1. A sintered body with good optical properties was obtained.

[Brief explanation of the drawing]

The mX diagram shows the conventional general hot press method, Figure 2 shows the hot press method using a mold release material, and Figure 3 shows an embodiment of the present invention, in which a solid lubricant is used and the molded body is pressure-sintered. FIG. 1... Mold, 2... Press keyaki, 3...
Sintered raw material powder, 4... Molded body, 5... Mold release material,
6...Solid lubricant.

Claims (1)

[Claims] Using a solid lubricant in which a B2O5 layer is formed on the surface of hexagonal boron nitride as a pressure medium, a molded body of the sintering raw material powder or a molded body obtained by pre-sintering this is sintered under pressure using a hot press machine. A method for producing a high-density sintered body.