JPH02283674A - Production of ceramics - Google Patents

Abstract

PURPOSE:To enable easy and smooth removal of a capsule by putting raw material powder, etc., into a specific capsule and sintering the powder under hot hydraulic pressure (HIP). CONSTITUTION:A hollow cylinder is formed with mild steel, etc., to obtain a capsule 1 having an outer diameter of about 60mm, a length of about 200mm and a wall thickness of about 2mm. A protruded ring 2 having a height of about 2mm is formed on the inner surface of the end part 1a of the capsule 1 by welding and padding. A raw material powder or a preformed article is put into the obtained capsule 1 having protrusion 2, evacuated, sealed and sintered under HIP condition to obtain a capsule containing the sintered material 3 integrated with the protrusion 2. The ends 1a,1a of the capsule 1 are clamped with a lathe, etc., the wall 1b of the cylinder is cut and removed and the sintered article 3 is removed from the capsule to recover the ceramics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is directed to the use of GdxOx S:Pr, which is a scintillator material for X-ray CT, by sintering in a hot isostatic pressing (hereinafter referred to as HIP) state. The present invention relates to a method for manufacturing ceramics obtained by bonding the ceramics, and in particular to a method for manufacturing ceramics that has been improved so that the capsules used during HIP can be easily and smoothly removed.

[Conventional technology]

Conventionally, when manufacturing ceramics, a method has been used in which raw material powders mixed with predetermined components are filled into a mold, compression molded, and then the molded body is heated and sintered. ing. In this case, if only normal sintering without applying pressure is performed, the pores sealed in the sintered body remain even after sintering.

Unable to obtain high-density, high-performance ceramics,
Particularly in scintillator materials such as those mentioned above, whose properties are affected by the transmittance of radiation or light, it is necessary to bring the density after sintering as close to the theoretical density as possible.

For this purpose, methods such as high-pressure molding, heat molding, and pressure sintering have been adopted. Among these, pressure sintering, especially Htp sintering, improves the compacting density and increases the sintering temperature. It has also been widely used in recent years because it can almost completely remove residual pores without causing excessive grain growth. HI
In P sintering, the raw material powder or preform is housed in a hollow cylindrical capsule made of mild steel, for example, and after removing the air inside the capsule, the capsule is sealed and HIPed.
Although sintering is carried out, the capsule must be removed in order to take out the sintered body, which is usually done by turning and/or grinding means.

[Problem to be solved by the invention]

In the above conventional means, 1, for example, a holding jig is fixed to both ends of the capsule through an adhesive, and the capsule is held between both centers of a lathe or grinding machine via this holding jig, so that the cylindrical surface of the capsule is The sintered body inside the capsule is removed by sequential turning or grinding. However, in the above case, the capsule and the sintered body are only in contact with each other in a crimped state, so as the time approaches the end of turning or grinding, the pressure of the capsule against the sintered body decreases dramatically or disappears.
There is a problem that not only may relative movement occur, but also that the sintered body may fall from between the two centers due to the disappearance of the capsule. This not only makes the capsule removal operation extremely complicated, but also causes cracks, breakage, and other inconveniences when the sintered body falls.

The present invention solves the problems existing in the above-mentioned prior art, and
It is an object of the present invention to provide a method for producing ceramics that allows easy and smooth removal of capsules used during P.

[Means to solve the problem]

In order to achieve the above object, there are two aspects of the present invention.

The raw material powder or preform is placed in a hollow cylindrical capsule made of a metal material, the capsule is degassed and sealed,
In a ceramic manufacturing method in which a capsule is removed by machining after hot isostatic pressing and sintering, a protrusion that protrudes into the raw material powder or the preform is provided on the inner surface of the end portion. A technical method was adopted.

[For production]

With the above configuration, even after the cylindrical surface of the capsule is removed, both end surfaces of the capsule continue to be integrated with the sintered body through the protrusions, and the sintered body can be maintained between the two centers. It is.

〔Example〕

The figure is a partially sectional front view showing a capsule and a sintered body in an embodiment of the present invention. In figure 0, 1 is a capsule;
For example, it is formed into a hollow cylindrical shape from mild steel and
The outer diameter is 60u and the length is 200mm.

It has a wall thickness of 2M. Reference numeral 2 denotes a protrusion, which is formed in the shape of an annular ring projecting from the inner surface of the end portion 1a of the capsule 1, and is integrated with the capsule 1. The protrusions 2 may be formed by welding overlay means, or may be bulged out integrally by, for example, a mold when molding the capsule 1.
is a sintered body.

It is integrally pressed into the capsule 1 without any gaps.

The protrusion 2 is also integrally pressed against the sintered body 3.

While the ends 1a and la of the capsule 1 containing the sintered body 3 after HIP sintering as described above are held, for example, between both centers of a lathe, two cylindrical surfaces 1b are sequentially turned. Even after lb is completely removed, the end portion 1a continues to be integrated with the sintered body 3 via the protrusion 2. Therefore, the sintered body 3 can be held between both centers and rotated without falling. If the sintered body 3 is removed from between both centers after the cylindrical surface 1b of the capsule 1 is removed, the end portion 1a can be removed very easily and without any particular difficulty.

In this example, an example is shown in which the capsule is made of mild steel, but it may also be made of a metal material other than mild steel (in short, it can withstand the heating during HIP sintering and meet the desired requirements for the sintered body). The shape of the protrusion provided on the inner surface of the end of the capsule can be any shape other than a circular ring, as long as it does not impair its properties. What is necessary is just to form it so that the rotational torque at the time can be transmitted to a sintered compact.

〔Effect of the invention〕

Since the present invention has the structure and operation as described above,
Capsules used during HIP sintering can be removed easily and smoothly, and the accident of falling sintered bodies that has conventionally been experienced when removing capsules can be avoided.

This has the effect of completely eliminating cracking or destruction accidents that occur in the sintered body.

[Brief explanation of drawings]

The figure is a partially sectional front view showing a capsule and a sintered body in an embodiment of the present invention. 1: Capsule. : Protrusion: Sintered body.

Claims (1)

[Claims] Production of ceramics by accommodating raw material powder or a preformed body in a hollow cylindrical capsule made of metal material, deaerating the capsule, sealing it, sintering it under hot isostatic pressure, and then removing the capsule by machining. 1. A method for producing ceramics, characterized in that a capsule is used, the inner surface of the end of which is provided with a protrusion that protrudes into the raw material powder or the preform.