JPS5888181A - Thermal hydrostatic press formation for ceramics special form material - 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 hot isostatic press molding method for ceramic profiled materials, and particularly to a method for forming profiled materials with high dimensional accuracy and is suitable for complex shapes.

Ceramic products have long been proposed to be widely used for heat-resistant, corrosion-resistant, wear-resistant coatings, etc., and it is well known that some of them have already been put into practical use; Most of these products have simple shapes that can be easily molded by hot pressing, etc., and since it is difficult to process irregularly shaped products after molding, they have not yet reached the practical level.

However, many different forming methods have been proposed that omit processing after forming, but the biggest problem is that it is difficult to obtain dimensional accuracy during forming, and the technology has not been established at all, especially for high-precision products. It is no exaggeration to say that there is no such thing.

On the other hand, the hot isostatic pressing method (IP method) has recently been attracting attention as a method for producing high-density ceramic sintered bodies, and remarkable progress has been made in technological development in this field. In particular, as a molding method for high-strength ceramic deformed materials,
Interest in the HIP method using non-deformable molds is increasing, and several proposals have been made in this field as well. For example, Figure 1 shows the method shown in Japanese Patent Publication No. 55-26681, in which a lower mold (1) and an L-shaped mold (2) are arranged as shown in the figure. After that, the internal space of the mold is filled with ceramic powder (3), and then the inside is degassed through the degassing pipe (0) and sealed, and then this is charged into the H/P furnace. HIP
With this method, the mold itself is stable against pressure from the lateral direction, and the precision of the widthwise dimension W can be expected to be considerably high. Since the upper die (2) and the lower die (1) move toward each other in response to pressure, there is a problem in that it is difficult to obtain dimensional accuracy in the portions indicated by H in the figure.

The present invention has been made in view of the above-mentioned current situation and to deal with such problems, and particularly relates to a method of molding a high-precision ceramic profile using a mold by the HIP method.The present invention is characterized by: However, the mold is a split mold, and after assembly, it has a structure that does not have any moving parts as described above, and it also has a structure that has an opening for pressure transmission and a cylindrical protrusion around its periphery. After arranging ceramic powder or a compacted powder thereof in a mold and covering the entire outer periphery of the mold with glass, H-P treatment is performed according to a conventional method, and the shrinkage during H-P treatment is The shrinkage allowance of the ceramics caused by this is compensated for by forcing the ceramics, which has been filled in the cylindrical protrusion in advance, into the mold using external pressure.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the accompanying drawings.

Figure 2 shows an example of the concept of the method of the present invention, in which the mold is divided into a lower mold (1) and an upper mold (2), and the upper mold (2) has an opening (4) for pressure transmission. and a cylindrical protrusion (7) formed at that part. Further, since the molds have a divided structure such that they contact each other at the abutting portions (8), there are no movable parts after assembly.

When carrying out the method, first, the ceramic powder (3) is filled into the mold, and a cylindrical protrusion (7) provided at the periphery of the opening (4) for transmitting pressure into the mold is filled. Fill the inside with enough ceramic powder,
Thereafter, the entire outer peripheral surface of the mold is covered with glass (5). In addition, prior to coating the glass, a plug (9) formed of the same material as the mold material is inserted into the cylindrical protrusion (7) so as to be movable within the protrusion (7). is also possible. Next, after filling the mold with ceramic powder in this way, it is inserted into a HIP furnace and subjected to HIP according to the usual method.
However, when using an inert gas, N2 gas is preferable for the HIP processing table, and due to the gas pressure in the furnace, high viscosity glass sulfur may seep into the protrusion when there is no plug, or the plug may In some cases, the plaque 9) will penetrate into the mold, pressurize the ceramic powder (3), shape the ceramic powder along the mold, and sinter it. In this case, since the upper and lower molds (1) and (2) remain completely immobile during the H-P process, the part along the inside shape of the mold shown by the thick line in the figure does not deform at all, and the dimensional accuracy of this part is extremely high. You will get something expensive.

However, since the part inside the cylindrical protrusion (7) is the part where the receiver has all the compression allowance for the ceramics in the mold during HIP, it is difficult to obtain dimensional accuracy for this part.
Since a predetermined dimensional accuracy can be easily achieved by polishing the box after HIP processing, this is not a particular problem. However, if the ceramic filling acid in the cylindrical protrusion (7) is insufficient, it will result in insufficient dimensions, and considering that it is impossible to build up the ceramic sintered body, this insufficient dimension will be fatal. The cylindrical protrusion (7) will result in a defect.
) It is preferable to leave enough room for the ceramic filling inside.

In other words, the cylindrical protrusion (7) in the present invention acts as if it were a runner that replenishes the shrinkage of the molten metal in the mold during casting, so the shrinkage of the ceramics in the mold is taken into consideration in this part. It is necessary to fill the container with sufficient ceramic powder.

Note that the mold material used in the present invention must be made of a material having heat-resistant strength, such as graphite or heat-resistant ceramics.

In addition, if there is a concern about reaction or seizure between the ceramic inside the mold and the mold material during H'UP, the inner surface of the mold can be coated with a mold release agent by spraying or coating. As mold release agents, BN and talc can be used. Representative.

In addition, in Fig. 2, if it is necessary to degas the inside of the mold before the H/P treatment, a deaeration pipe is attached to the plug (9), and the inside is deaerated after glass coating.
Needless to say, the degassing tube must be sealed after that.

Next, Figure 3 shows a model that allows degassing in the mold and glass coating to be performed at the same time.After the mold is completely filled with ceramics (3), this is filled with glass powder (11). The glass is melted by being buried in a crucible (00) and heated while degassing in a vacuum furnace, etc., and mold (1) (
2) The outer peripheral surface is covered with glass.

In the case of this figure, the opening (4) is facing downwards.
Unlike the case shown in the figure, the plug (9) is not arranged, so depending on the type of ceramic (3), the specific gravity may be lower than that of the molten glass, and when the glass is melted, ceramic powder floats through the opening (4) inside the glass. This is because there is a risk of this happening; if there is no such risk, there will be no problem with the stationery even if it is placed with the opening facing upward without using a plug.

In addition, when embedding the mold in the glass powder, instead of burying the entire mold, the glass powder is placed around the downward opening as shown by the dotted line in Figure 3, and the upper part is The same effect can be achieved by placing an inverted glass cup (b) to warm the JJ mouth.

Note that when placing the ceramic in the mold, it is preferable to increase the initial packing density by compacting the ceramic powder in advance by cold pressing, rather than simply filling the ceramic powder.

Furthermore, in this case, since it is difficult to form the deformed material by cold pressing, the deformed material is molded separately into several parts, and these divided compacts are placed in the mold at the same time as the mold is assembled. It is preferable to place them.

As explained above, in the method of the present invention, when performing H-P forming of a ceramic profiled material using a mold, the mold is a split mold,
Moreover, since the mold does not have any moving parts after the mold is assembled, the dimensional accuracy of the product is extremely high, and the compression allowance of the ceramic during H-processing is reduced by the openings for transmitting pressure into the mold. Since the cylindrical protrusion provided in the mold is replenished with surplus ceramics, it is possible to uniformly feed ceramics into the mold, which also greatly contributes to improving the dimensional accuracy of the molded product. are doing. Furthermore, since the mold itself does not deform the stationery during HIP processing, it can be used repeatedly, which greatly contributes to reducing HIP processing costs.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing a conventional method for forming a ceramic profiled material, and FIGS. 2 and 3 are conceptual diagrams showing an embodiment of the method of the present invention. (1)...Lower mold, (2)...Upper mold, (3)...Ceramics. (4)......opening, (5)...glass, (7)...cylindrical protrusion. Patent applicant: Kobe Steel, Ltd.

Claims (1)

[Claims] 1. In a method for hot isostatic press forming of a ceramic profiled material using a mold, the split mold is made of a material having high temperature strength and has no movable parts after assembly. In a mold having an opening and a planar protrusion on the periphery of the opening, ceramic powder or a green compact thereof is placed so as to fill the cylindrical protrusion, and then A ceramic variant characterized in that the entire outer peripheral surface of the mold is covered with glass and the ceramic in the mold is compressed and sintered through the opening by hot isostatic pressing in a high temperature (% pressure) gas atmosphere. Hot isostatic pressing method for materials. a. A plug member formed of a mold material is inserted into the cylindrical protrusion, and the plug member enters the mold during hot isostatic pressing to compress the ceramic inside the mold. A hot still water press molding method for a ceramic profiled material according to claim 1. 8. A mold is embedded in a glass powder granule in a container filled with glass powder granules, and the glass is heated and melted. A hot still water press molding method for a ceramic profiled material according to claim 1 or 2, wherein the entire circumferential surface of the mold is coated with molten glass. 4. Glass powder particles are formed with the mold opening facing downward. A hot isostatic press molding method for a ceramic profiled material according to claim 8, in which a split mold is embedded in a body. 6. The hot isostatic press molding method for a ceramic profiled material according to any one of claim 4. 6. The hot isostatic press molding method for a ceramic profiled material according to claim 5, wherein the mold release agent is BN. 7. A hot isostatic press forming method for a ceramic profile material according to any one of claims 1 to 6, wherein the hot isostatic press treatment is carried out in a high 1 MN2 gas atmosphere.