JPS624630B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot isostatic press apparatus (hereinafter referred to as a HIP apparatus) for sintering metal powder ceramics or a mixture thereof in a high-temperature, high-pressure gas atmosphere, particularly a hot isostatic press apparatus disposed in a high-pressure chamber. This relates to the structure of the self-heating layer.

In recent years, the demand for processing various materials under high temperature and high pressure has increased, and HIP equipment has been attracting attention as a device for this purpose.

According to this HIP equipment, powder materials such as metal powders and ceramic powders can be sintered under high pressure, and they have higher density and strength than those sintered under atmospheric pressure or vacuum. It has many advantages such as high In addition, it is also possible to subject sintered products and cast products to high-temperature, high-pressure treatment, and these products generally have many microscopic pores inside, and sometimes large pores that can be observed with the naked eye. However, through high-temperature and high-pressure treatment, it is possible to completely refine or reduce these pores to the point where they are practically unbearable, and as a result, it is possible to improve strength, eliminate casting defects, and improve quality. plays a major role in

These HIP devices basically consist of a high-pressure container that can tightly seal high-pressure gas, a heat insulating layer placed inside the container, and a heating device placed inside the heat insulating layer. The furnace chamber that houses the processing body is constructed, and among these components, the important one that basically controls the performance of the HIP equipment is the heat insulation layer, which is usually not used because it is under special conditions of high pressure. This requires a different insulation layer configuration from that of high-temperature furnaces. In other words, in this type of equipment, argon gas (hereinafter abbreviated as Ar gas) is normally used as the pressure medium, but Ar gas at high temperature and pressure is, for example, 2000 kg/cm ² and at 1450°C, it is different from that at normal temperature and pressure. In comparison, the viscosity is only about 3.8 times higher, but the heat capacity is over 240 times higher.Although the heat capacity is extremely large, it is highly fluid, so the amount of heat transfer by convection is extremely large. It is desired that the heat insulating layer effectively prevents the high temperature gas inside the furnace chamber from flowing out to the outside of the furnace chamber and keeps heat loss low, and a device such as the one shown in Figure 1 is generally used. . That is, in the same figure, a high pressure chamber 4 is defined by a high pressure cylinder 1, an upper plug 2 and a lower plug 3 that protrude into the upper and lower openings of the cylinder to seal them, and a cylindrical heat insulating layer is provided in the high pressure chamber 4. 5 and a heating device 6 disposed inside the furnace chamber 7, the object to be processed 13 is placed on a heat insulating seat 12 integrally attached to the lower plug 3. The HIP process is performed under a high temperature and high pressure atmosphere inside the furnace chamber 7.

In the above device, the heat insulating layer consists of two or more layers made of a material that does not have air permeability or has low permeability, such as a stainless steel plate or a molybdenum plate, so that the gas in the furnace chamber 7 as a whole does not pass through to the outside of the furnace chamber. It is composed of an inverted top 8, 8' or a cylinder and a heat insulating material 9 such as ceramic felt for convection and radiation suppression filled between them, and is suspended in the high pressure chamber 4 by a holding member 14 on the upper plug 2. As a result, the furnace chamber and the outside of the furnace chamber are communicated only through the space surrounding the heat insulating seat 12 at the bottom of the furnace chamber, and the high temperature gas inside the furnace chamber is prevented from flowing out to the outside of the furnace chamber due to convection. It is structured as follows.

However, the above heat insulating layer has the following drawbacks.

(1) Pressure-resistant members such as high-pressure cylinders are very expensive, so it is preferable to effectively utilize the internal volume of the high-pressure chamber to improve economic efficiency, and for this purpose, it is better to make the insulation layer as thin as possible. However, there is a limit to how thin the heat insulating layer of the above structure can be made.

(2) The properties of heat insulating materials such as ceramic felt change over time, and their thermal insulation properties deteriorate after they are used for the maximum period of time.

(3) When processing objects containing relatively active elements such as Ti alloys and superalloys, the atmosphere in the furnace must be clean. Insulating materials such as ceramic felt absorb water etc. at low temperatures,
It is released at high temperatures and damages the atmosphere inside the furnace.

Therefore, as a method to compensate for the drawbacks of such a heat insulating layer structure, Japanese Patent Publication No. 1176-1976 and Japanese Patent Application Laid-Open No. 47-25007
The publication discloses a heat insulating layer in which metal sheets are stacked in multiple layers and gaps are provided between each layer.

As means for forming the gap, the former method uses a spirally wound thin wire and the method of scattering particles of porcelain material, and the latter method uses a narrow metal band with a thickness of 1 mm, for example. There is.

However, these heat insulating layers also have the disadvantage that, for example, the method of scattering particles of porcelain material requires special techniques such as thermal spraying and is expensive; 1) The work of winding up thin wires and metal bands together with metal sheets is extremely complicated.

(2) If the thin wires and straps are not fixed to the sheet in some way, they will fall off during use, resulting in uneven gaps and sheets touching each other. Also,
Thin wires are difficult to fix, and straps require riveting, which requires a great deal of effort.

(3) With thin wires and metal bands, the contact area with the sheet is linear or band-like, and the contact area becomes large, making it impossible to avoid a decrease in heat insulation due to heat conduction through this area.

(4) There are few communication parts between the inside of the insulation layer and the outside, so
Sudden changes in internal and external pressure can cause deformation, and there are restrictions on the gap between the sheets, which limits how thin the insulation layer can be.

There are some drawbacks, and it is still not sufficient.

It is an object of the present invention to address and eliminate the drawbacks of the conventional heat insulating layer structure and provide a more suitable heat insulating layer for a HIP device.

In addition, the present invention provides an excellent heat insulating layer that is easy to install, easy to fix, does not have to worry about falling off, and has a small contact area that does not reduce the heat insulation properties due to heat conduction and does not cause deformation or destruction. for other purposes.

Thus, the ultimate objective of the present invention is to provide a HIP device that is responsive to the trends of the times and is effective and effective for processing a variety of materials.

Therefore, the object of the present invention as described above is to alternately polymerize sheets having no gas permeability and wire meshes associated in both warp and warp directions in a multilayer manner, with a gap between each sheet maintained by the wire mesh. This is achieved by forming the thickness of the sheet, the mesh of the wire gauze, the wire diameter, and the relationship ratio between the lattice gap and the wire diameter within specific effective ranges.

Hereinafter, embodiments and specific aspects of the present invention will be described further based on the accompanying drawings. However, the present invention is not limited in any way by the accompanying drawings and the following description, and it goes without saying that design changes may be made as appropriate within the scope of the invention.

FIG. 2 is a schematic diagram of a HIP device (heating device and sample omitted) that corresponds to the device shown in FIG. 1 and to which a heat insulating layer according to the present invention is applied. FIG. 3 is an enlarged longitudinal and horizontal cross-sectional view.

In FIG. 2, 1, 2, and 3 indicate a high pressure cylinder, an upper plug, and a lower plug, respectively, as in FIG. Although completely similar, the cylindrical heat insulating layer is composed of a body part 16 and an upper lid part 17, of which the upper lid part 17 has a cap 18 made of a material that does not have gas permeability and a heat insulating material 9'. and each member of the disc 19.
On the other hand, the body part 16 is airtightly connected to the upper lid part 17 via a ring 20, and the structure of this body part is a main feature of the present invention, and is shown in FIGS. 3 and 4. As shown in the enlarged view of the part (A part), it is constructed by overlapping a sheet 21 that does not have gas permeability and a net material 22 made of heat-resistant wire material, and in the illustrated example, it has seven layers of gas permeability. A non-woven sheet 21 and six layers of net material 22 are shown. Each gap in the sheet 21 is maintained at a required gap by a mesh material 22, and each gap is filled with Ar gas through the opening 23 at the bottom in FIG.

Normally, although high-pressure Ar gas has an extremely large heat capacity, its viscosity is extremely low, so the amount of heat transferred by convection is large.As mentioned above, the structure of the heat insulating layer is designed to absorb heat from this convective transfer as well as radiation. It is necessary to be able to efficiently suppress dissipation.

On the other hand, the thermal conductivity of high-pressure Ar gas itself is extremely small, for example 1000Kg/cm ² and 1.24× at 400℃.
10 ⁴ cal/cmsec℃, which is only 1/60 of alumina.

From this, it is extremely effective to confine high-pressure Ar gas in a narrow space so as not to cause convection, and then stack multiple layers of this in order to obtain a heat insulating layer with excellent thermal insulation properties.

The amount of heat transfer due to the convection of Ar gas in each gap between the sheet 21 and the net material 22 is determined by the gap distance, the temperature difference between the inner and outer sheets, and the thermal conductivity, thermal expansion coefficient, density, viscosity, etc. of the Ar gas. Although it is determined by physical properties, by setting the gap spacing below a certain value for any given pressure and temperature difference between the inner and outer sheets, convection will virtually not occur, and the heat transfer between the inner and outer sheets will be controlled by the Ar gas itself. Only the thermal conductivity and radiant heat will be generated. Practically sufficient thermal insulation can be obtained by setting the distance between the inner and outer sheets to 2 mm or less, preferably 1 mm or less.

In the above structure, it is desirable to select the thinnest thickness of the sheet while considering strength. It is extremely important to make the heat insulating layer thin in order to effectively utilize the volume inside the furnace within the heat insulating layer, and in the present invention, it is preferable to use a thin sheet material with a thickness of 0.05 to 2 mm in combination with the above-mentioned thermal insulation effect.

As the material for the sheet that does not have gas permeability, any sheet suitable for the purpose can be used, but in general, metals such as aluminum, stainless steel, Ni-based superalloys, molybdenum, and flexible graphite are used. (trade name Graph Oil) etc. are suitable.

The number of stacked sheets is appropriately selected depending on the furnace temperature and the required thermal insulation.

On the other hand, the net material interposed between the sheets is used to maintain the required gap between the inner and outer sheets and to suppress heat dissipation due to convection, as shown in FIGS. 3 and 4. It is formed by cross-linking thin wire rods 22' along the warp and warp, and the thickness is determined by the holding gap between the inner and outer sheets, but the mesh gap is preferably as large as possible within the range where the inner and outer sheets do not contact each other, and is 100 mesh or less. ,Preferably
For efficiency and handling, the roughness should be 60 mesh or less, more preferably 30 mesh or less.
suitable. If the mesh spacing is unnecessarily narrow, the heat conduction through the material not only impairs the thermal insulation properties but also unnecessarily increases the weight, which is undesirable. Furthermore, if the wire diameter is too large, the apparent thermal conductivity of the heat insulating layer will increase due to the heat conduction of the net material itself, which is undesirable in terms of the convection suppressing effect, and satisfactory heat insulating properties cannot be obtained. , preferably about 0.5 to 0.8 mm is most effective.

If it is less than 0.1 mm, it will become too thin and it is virtually impossible to maintain the spacing between the sheets, and if it is more than 1 mm, the sheet spacing will exceed 2 mm and insulation properties will not be obtained due to the intersection between the sheets. increases. Therefore, those within the above range are usually selected and used.

The material of this net material is a heat-resistant linear material, and in addition to the same metal material as the sheet, glass fibers, ceramic fibers, carbon fibers, etc. may be used, and they are selected as appropriate.

In addition, when overlapping the sheet and the netting material, it is preferable to overlap each other separately in a circular manner, but it is practically sufficient to roll the sheet and the netting material together to form a cylindrical shape. Thermal insulation can be obtained.

Further, if the size of the sheet is insufficient due to the large size, it is also possible to sequentially stack sheets divided vertically or circumferentially.

With the structure described above, the heat dissipation in the radial direction in the body of the heat insulating layer is thinner than that of the heat insulating layer with a conventional structure, and can be suppressed sufficiently for practical purposes. If the cylinder is still formed by stacking the cylinders with both the upper and lower ends open, Ar gas will flow from the bottom to the top, and sufficient thermal insulation may not be obtained.
The upper end of the cylinder becomes hot, and the upper part of the high-pressure cylinder may rise in temperature. Therefore, in order to avoid this, measures are taken such as airtightly joining the upper end to the ring 20 shown in FIG. 2 by means such as welding, or opening the upper end and making the lower end airtight. It is preferable that

FIGS. 5 and 6 show modified examples of the heat insulating layer of the present invention having the overlapping structure, and in FIG. 5, a thick cylinder 23 with no gas permeability is provided as the innermost layer of the cylindrical heat insulating layer. At the same time, a similar cylinder 24 is also placed on the outermost layer to improve roundness. In this case, the inner and outer cylinders 23 and 24 may be made of reinforcing materials sufficient to maintain roundness, and may be made of materials that have a slightly poor gas permeability due to the relationship with the sheet. Especially for high temperature applications, alumina can be used, and a molybdenum skeleton can also be used.

On the other hand, FIG. 6 differs from FIG. 5 in that the heat insulating layer is divided into a plurality of blocks in the radial direction. In this case, caps 25 and 2 made of a gas-impermeable material are provided at the upper ends of each of the divided layers.
5', and an inverted tip 26 is placed over the outer layer to form a substantially airtightly coupled structure.
By dividing in this way and keeping the upper end portions of each airtight, it is possible to suppress upward heat dissipation due to convection.

In addition, the upper caps 25, 25' shown in FIG.
Alternatively, it is also suitable to arrange a plurality of heat insulating layers similar to those of the side cylindrical walls between each layer of the inverted cup 26 in order to prevent heat from dissipating upward.

It is also a preferable embodiment to provide a space 27 between each of the divided blocks to absorb the accommodation stress.

Furthermore, in addition to the above-mentioned modifications, the heat insulating layer of the present invention does not overlap the entire surface of the sheet between the sheets, but divides the net material in the longitudinal direction, shifts the positions of adjacent net materials, and divides them at appropriate intervals. It is also possible to interpose a layer after the addition of a layer, and this is also included in the scope of the present invention.

Furthermore, although the above explanation corresponds to FIG. 1 and applies to the case where the heating device is arranged inside the heat insulating layer, the same applies to a hot isostatic press device equipped with the heating device 6 at the bottom of the sample stage as shown in FIG. 7. can be applied to achieve the same effect.

As described above, since the device of the present invention has a heat insulating layer structure in which a sheet with no gas permeability and a specified net material are layered together, it is sufficient to simply overlap and wind it up. If the width or length of the mesh is insufficient, it can be added by simply sewing it together, and the construction is extremely easy, as small holes are made in the sheet as appropriate and the mesh can be tied with thin wire to secure it. If the upper end is fixed, there is no risk of it slipping off, and since the contact area between the sheet and the net material is dotted, the contact area is small and there is no reduction in insulation properties due to heat conduction. , It has various advantages such as being open in both horizontal directions, making it easy for gas to pass in and out, preventing pressure from building up inside and outside the insulation layer, and reducing the risk of deformation or destruction of the insulation layer.It has excellent thermal insulation properties, and A thin heat insulating layer can be obtained, making it possible to effectively utilize the internal volume of the high pressure chamber and reducing the diameter of the high pressure vessel, making it possible to downsize the equipment and improve the economic efficiency of processing. Since it does not use , it can be used stably for a long period of time and its durability can be increased.

Furthermore, the above structure does not use ceramic materials that tend to adsorb and release water, etc., making it easier to clean the atmosphere inside the furnace, making it possible to process materials containing active elements, and other remarkable effects. Therefore, the apparatus of the present invention brings great benefits as a hot isostatic pressing apparatus, whether directly or indirectly.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a conventional hot isostatic press device, FIG. 2 is a longitudinal sectional view showing an example of a hot isostatic press device according to the present invention, and FIGS. Vertical and horizontal cross-sectional views of part A in Figure 2,
FIGS. 5 and 6 are sectional views of essential parts showing modified examples of the heat insulating layer in the apparatus of the present invention. Moreover, FIG. 7 is a schematic sectional view showing another type of hot isostatic press apparatus to which the heat insulating layer according to the present invention is applied. 1...High pressure cylinder, 2...Upper plug, 3...
...Lower plug, 4...High pressure chamber, 5...Insulation layer, 6
... Heating device, 7 ... Furnace chamber, 8, 8' ... Inverted cup, 9, 9 ... Insulation material, 11 ... Support, 14
... Holding member, 21 ... Sheet without gas permeability, 22 ... Netting material.

Claims (1)

[Scope of Claims] 1. A high-pressure device in which an inverted cup-shaped or cylindrical heat-insulating layer is arranged in a high-pressure container that encloses high-pressure gas, and a heating device is disposed inside the heat-insulating layer, at least The body of the layer is formed by alternately layering sheets with no gas permeability and net material made of heat-resistant wires crossed in warp and warp, and forming the required gap between adjacent sheets by the net material. At the same time, the thickness of the sheet is 0.05 to 2 mm, the mesh material is coarser than 100 mesh, and the wire diameter of the constituting wire is 0.1 mm.
A hot isostatic press device characterized in that the thickness is 1 mm. 2. The hot static insulation layer according to claim 1, wherein the body of the heat insulating layer is divided into a plurality of blocks in the radial direction, and each block has a plurality of stacked layers each consisting of a sheet and a net material. Hydraulic press equipment. 3. The hot isostatic press apparatus according to claim 2, wherein a gap is formed between each block to absorb thermal stress. 4. The hot isostatic press apparatus according to claim 1, 2, or 3, wherein the net material is divided into a plurality of pieces in the axial direction of the trunk and interposed between the sheets. 5. The hot isostatic press apparatus according to claim 4, wherein the phases of adjacent net materials are shifted from each other. 6. Hot isostatic pressure according to any one of claims 1 to 5, wherein the innermost layer and the outermost layer of the heat insulating layer are cylinders that are thicker than the intermediate sheet and have no gas permeability. Press equipment. 7. Any one of claims 1 to 6, wherein the sheet having no gas permeability is a sheet selected from metals such as aluminum, stainless steel, Ni-based superalloys, molybdenum, or flexible graphite. The hot isostatic press apparatus described. 8 The heat-resistant wire material constituting the net material is aluminum,
The hot hydrostatic pressure according to any one of claims 1 to 7, which is a wire selected from stainless steel, Ni-based superalloy, molybdenum, etc., or a wire selected from glass fiber, ceramic fiber, and carbon fiber. Press equipment.