DE2404877A1 - COMPOSITE MOLD FOR THE PRODUCTION OF MOLDED PARTS BY SINTERING - Google Patents

Description

The invention relates to a composite mold for the production of Molded parts by sintering metallic or ceramic powder materials that are subject to temperatures during the work process between ambient temperature and e.g. 2000 ° C.

In the production of such molded parts, the powder material used is introduced into the mold; the latter is closed, any air or gases contained in it are sucked off, and the form then becomes an isostatic or another Subject to pressure at temperatures as high as 2000 ° C can. After relaxation and cooling, the molded part produced is removed from the mold, the latter either being destroyed or can be used again.

The production of the casting molds suitable for this process is relatively simple as long as the working temperatures lie low. However, at higher temperatures

409832/0853

Problems because the form is self-supporting during the entire work process and must be deformable when the initial working temperature is reached. In addition, the shape must be absolute at all temperatures stay tight. Finally, it is required that the shape has no influence on the material to be processed, especially this not contaminated.

The ones previously used for the production described above Shapes do not do justice to the listed conditions. In addition, they are difficult to manufacture and at high cost.

The invention is based on the object of developing a form which fulfills the listed conditions and is also easy and inexpensive to manufacture.

This object is achieved according to the invention by a mold wall, those for sealing between the powder material to be compacted and the outside atmosphere or one that applies the working pressure Liquid is used, is self-supporting in relation to the ambient temperature and is deformable at working temperatures, and which is coated with a material formed integrally therewith which makes the shape self-supporting at working temperatures and makes it malleable.

Is there a risk of sticking, diffusion or contamination An inner protective layer is expediently provided between the mold wall and the compacted body.

The new shape is used in conjunction with vacuum filling devices known per se and closing devices are used and can be used to produce various molded parts.

409832/0853

In the drawing is an example embodiment of the Invention shown. Show it:

Fig. 1 is a longitudinal section through a mold and

FIG. 2 shows, on an enlarged scale, a section along the line II-II in FIG. 1.

The shape shown consists of a mold wall 1, which at Working temperature is deformable and the desired tightness between the powder to be compacted and an outside one Pressure fluid guaranteed. The mold wall 1 does not require any mechanical support. It has a coating 2, the Use temperature is rigid and made of fine, porous or discontinuous Material can exist. This coating takes on the role of a support frame and holds the mold wall 1 upright.

Finally, an inner protective layer 3 is provided, the shape of which corresponds to that of the molded part to be produced. It is equipped with a tube 4 for filling, suction and closing Mistake.

The softening temperature of the material forming the mold wall can be below and the melting temperature of this material above the pressing temperature of the powder materials to be processed. However, the melting temperature can also be below the pressing temperature provided that the material forming the coating 2 remains self-supporting at the pressing temperature.

The mold wall 1 can advantageously consist of an inexpensive one borosilicate glass, e.g. Pyrex. This glass can

- 4 409832/0853

blowing, welding and processing in a simple and economical way.

Since the Forinwandung 1 is not resistant to the temperature of use rather, it flows under its own weight at a temperature of the order of about 1150 to 1200 ° C, it is held by the cover 2. After processing the Forinwandung 1 by sandblasting it is either coated with a molybdenum film 0.10 mm thick, a stainless steel film 0.05 mm thick, or a 0.5 mm pure clay film Strength coated. Molybdenum and stainless steel can be used in wire form and alumina in powder form with the help of a welding torch be applied.

In the case of the mold wall 1 described above, glass inclusions can be present appear. In other cases, too, there can be contact between the mold wall and the compacted body for various reasons be undesirable. In this case, the inner protective layer 3 is provided, which can consist of pure alumina and in powder form is applied with the help of a welding torch, even before the two-part mold wall is welded together 1. The protective layer 3 can also be in the form of a fireproof Liner or poteyage can be formed from a ceramic powder, with a hardener as an additive and alcohol as There is dilution. This material is poured into the mold in liquid form and then dried in the oven. The protective layer can also consist of metal, which is applied in wire or powder form with the help of a welding torch. The protective layer can also consist of a carbon solution or the like.

409832/0853

An essential feature of the composite glass can be seen in the fact that none of its components, e.g. glass or pure clay, is usable on its own for the intended goal.

The manufacture and use of the new mold essentially exist from the following work steps:

- Production of the mold wall 1;

- Processing of the surface of the mold wall 1, e.g. by sandblasting;

- Application of the coating 2;

- Application of the inner protective layer 3;

- Filling in powder or granules;

- suction and closing of the mold;

- heating or preheating of the mold;

- pressing;

- heating with or without pressing;

- Cooling down;

- Removing the shape.

4 09832/0853

The tight mold wall 1 can also consist of a metal foil and its coating material 2 made of ceramic, which the mold wall at Maintains working temperature self-supporting. Figures 1 and 2 can also represent such an embodiment. The Mold wall 1 made of stainless steel with a thickness of about 0.3 mm and the coating made of pure alumina in about the same thickness exist, the latter can be sprayed on.

In contrast to the known forms consisting of only a single material, the new composite form has numerous advantages. The mold made of vitreous material should, if it contains the powder, be able to deform in a plastic manner. The glass used for this purpose costs 30 to 50 times the amount of glass that can be used for the new composite mold. In addition, the glass used for the known molds is much more difficult to process and only at higher temperatures :
can be.

takes place at 2000 ° C, while blown glass is processed at 1100 ° C

A form consisting only of steel has the disadvantage that its manufacture is relatively expensive and its destruction can only be achieved chemically. In contrast, the Glass-alumina mold easily removed by thermal or mechanical shock will. The combination of ceramic-metal or glass-metal can also be easily peeled off or broken off.

A major advantage of the new composite form is its wide range of uses. While a form consisting only of glass frit or ceramic, which can be used at 1200 ⁰ C, breaks at a slightly lower temperature or vice versa at too high a temperature.

409832/0853

w 7 -

If the temperature melts, a composite glass, e.g. glass-alumina, can be either in the course of the same work process or within different work processes are subject to large deformations, namely in Temperature ranges between 500 ° C and 1200 ° C. This allows optimal pressing processes to be used, with the same shapes for Processing different powders can be used. As a result, the standardization of the items results in great economic efficiency.

409832/0853

Claims (11)

- 8 patent claims: 1. Composite mold for the production of molded parts by sintering metallic or ceramic powder materials that during the work process are between ambient temperatures and, for example, 2000 ° C, characterized by a mold wall (1) which is used for sealing between the powder material to be compacted and the outside atmosphere, or a liquid that applies the working pressure, is self-supporting in relation to the ambient temperature and at working temperatures is deformable, and integral with a with their trained material (2) is coated that the shape makes self-supporting and malleable at working temperatures. 2. Form according to claim 1, characterized in that the softening temperature of the material forming the mold wall (1) below the pressing temperature of the powder materials to be processed lies. 3. Form according to claim 2, characterized in that the melting temperature of the material forming the mold wall (1) below the pressing temperature of the powder materials to be processed lies. 4. Form according to claim 2, characterized in that the Fonnwandung (1) consists of an inexpensive borosilicate glass, e.g. Pyrex. 5. Mold according to claim 1, 2 or 3, characterized in that the mold wall (1) is coated with a molybdenum film with a thickness of the order of magnitude of S) UtHH 0.10 mm. 409832/0853 - D _ 6. Form according to claim 1, 2 or 3, characterized in that the Mold wall (1) is covered with a film of stainless steel with a thickness of the order of 0.05 mm. 7. Form according to claim 1, 2 or 3, characterized in that the Mold wall (1) is covered with a film of pure clay with a thickness of the order of 0.5 mm. 8. Mold according to claim 1, characterized in that the mold wall (1) consist of a metal foil and its coating material (2) made of ceramic. 9. Mold according to claim 8, characterized in that the mold wall (1) made of stainless steel and their coating material (2) made of pure alumina. 10! Mold according to one of Claims 1 to 6, characterized by an inner protective layer (3) made of pure clay. 11. Form according to one of claims 1 to 9, characterized by an inner protective layer (3) in the form of a refractory lining or poteyage, which is made of a ceramic powder, with a hardener as an additive and alcohol as a thinner, introduced in liquid form and dried in the oven. Dipl./-ing. Xierner gram Patent attorney Gr / Gr. 409832/0853 JtO Blank page