JPH02283675A - 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 a magnetic material such as mild steel to obtain a capsule 1 having an outer diameter of about 60mm, a length of about 200mm and a wall thickness of about 2mm. Protruded crosses 2 having a width of about 2mm and a height of about 2-4mm are integrally formed on both ends of the obtained capsule. Separately, a magnetic holding member 3 composed of a side yoke 4, an opening 4a, a center yoke 5. a perma nent magnet 6, a groove 7, etc., is formed by forming a stepped cylinder with a magnetic material such as mild steel. A raw material powder or a preformed article is put into the obtained capsule 1, evacuated, sealed and sintered under HIP condition to fix the yoke-side of the member 3 to both ends of the capsule 1 and obtain an integrated product composed of the capsule 1 and the member 3. The integrated product is clamped with a lathe, etc., and the cylinder wall of the capsule is cut and removed with a proper cutting tool to obtain the objective ceramics.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides three scintillator materials for XIaCT, such as Gd, O, and S:Pr, in a hot isostatic pressing (hereinafter referred to as HIP) state. Obtained by sintering [Conventional technology] Conventionally, when manufacturing ceramics, raw material powders mixed to have predetermined components are filled into a mold for compression molding, and then the molded body is produced. A method of heating and sintering is used. In this case, with normal sintering alone without applying pressure, the pores enclosed in the sintered body remain even after sintering, making it impossible to obtain high-density, high-performance ceramics, especially with scintillators such as those mentioned above. For materials 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 methods, pressure sintering, especially HIP sintering, improves the compacting density and increases the sintering temperature. This is because residual pores can be almost completely removed without excessive grain growth.

It has been widely used in recent years. In HIP sintering, 1
For example, a raw material powder or a preformed body is housed in a hollow cylindrical capsule made of mild steel, and after removing the air inside the capsule, the capsule is sealed and HIP sintering is performed. The capsule must be removed, usually 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, there is a problem in that the adhesive force of the adhesive decreases due to the heat generated when turning or grinding the capsule, and the sintered body falls from between the two centers. 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, the present invention has the following features.

The raw material powder or preform is placed in a hollow cylindrical capsule made of a metal material, the capsule is degassed and sealed,
A method for manufacturing ceramics in which the capsule is removed by machining after hot isostatic pressing sintering, using a capsule made of a magnetic material and having radial protrusions on the end face that engage with a magnetic holding member. A technical method was adopted.

[For production]

With the above configuration, even if heat is generated during capsule removal, the air retaining member and the capsule continue to be firmly attached to each other, and the sintered body can be maintained between the two centers.

〔Example〕

The first g(al(bl) are a partially omitted front view and a side view, respectively, showing a capsule in an embodiment of the present invention.

In both figures, a capsule 1 is made of a magnetic material such as mild steel and has a hollow cylindrical shape 2, and has an outer diameter of 6Q+*m, for example.
It has a length of 200mm and a wall thickness of 2fi, and a sintered body (not disclosed) is housed inside. On both end faces of the capsule 1, protrusions 2 having a diameter of 2 cranes and a height of 2 to 411, for example, are integrally provided in a cross shape.

Next, in FIG. 2+8+ (bl is a partially vertical cross-sectional front view and left side view showing the magnetic holding member 3 in the embodiment of the present invention, respectively, 4 is a side yoke, and 1 is made of, for example, mild steel. It is formed into a single-stepped cylindrical shape from a magnetic material, and an opening 4a is provided on the large diameter side.

Reference numerals 5 and 6 denote a center yoke and a permanent magnet, each of which is formed into a cylindrical shape, and the opening 4a of the side yoke 4.
fixed coaxially and integrally. The permanent magnet 6 is magnetized in the axial direction, and the center yoke 5 is made of a ferromagnetic material such as mild steel like the side yokes 4. Next, 7 is a groove 2, for example, the radius is 2.51 m and the depth is 3 to 5.
They are provided in a cross shape on the end faces of the center yoke 5 and side yokes 4. The diameter of the large diameter portion of the side yoke 4 is approximately 60n. 8 is the center hole.

With the configuration shown in FIGS. 1 and 20 above, first the HIP
When the center yoke 5 side of the magnetic holding member 3 is fixed to both ends of the capsule 1 containing the sintered body after sintering, the protrusion 2 of the capsule 1 fits into the groove 7, and both of them form a soldier character shape. Since they are formed, the capsule 1 and the magnetic holding member 3 are automatically aligned. The magnetic flux from the permanent magnet 6 is transmitted from the center yoke 5 to the capsule 1. Furthermore, a so-called magnetic circuit is formed from the side yoke 4, and the capsule l
and the magnetic holding member 3 are firmly fixed and integrated. In this state, by holding the capsule 1 between the two centers of a lathe through the center hole 8 and rotating it, the cylindrical surface of the capsule 1 can be worked with a predetermined tool and removed one by one. In this case, even if heat is generated due to processing, the two capsules 1 and the magnetic holding member 3 continue to be magnetically fixed and integrated. Therefore, the sintered body can be held between both centers and rotated without falling.

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. That's fine.

In addition, the protrusions and grooves to be provided on the end faces of the capsule and the magnetic holding member can have a shape other than the cross shape.
What is necessary is just to form it so that the rotational torque at the time of turning or grinding can be transmitted to a capsule.

Moreover, it can be removed smoothly, and there is no need to worry about the accidents of falling sintered bodies that have previously been experienced when removing capsules.

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

[Brief explanation of drawings]

Fig. 1(a) (bl is a partially omitted front view and side view showing a capsule in an embodiment of the present invention, respectively; Fig. 2 1a)
) (bl is a partial cross-sectional front view and left side view showing a magnetic holding member in an example of the present invention, respectively. 1: Capsule, 2: Protrusion, 3: M1 magnetic holding member 6: Permanent magnet, 7: Groove .

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. A method for manufacturing ceramics, characterized in that the capsule is made of a magnetic material and has a radial protrusion on its end face that engages with a magnetic holding member.