Powder metallurgy processes – Powder metallurgy processes with heating or sintering – Post sintering operation
Patent
1987-04-30
1989-12-12
Lechert, Jr., Stephen J.
Powder metallurgy processes
Powder metallurgy processes with heating or sintering
Post sintering operation
419 36, 419 38, 419 49, 419 54, 419 55, 419 57, 419 60, B22F 324
Patent
active
048866393
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to structural components produced by powder metallurgy, particularly by injection molding or injection pressing. In the production of structural components, especially high temperature resistant structural components which are shaped by injection molding or dry pressing and which are sintered or at least capable of being sintered, such components are placed, for example, on plates, or they are embedded in a powder or the like for the sintering following the shaping.
DESCRIPTION OF THE PRIOR ART
As a rule, the sintering takes place after the burn-out or evaporation of the binding agent or material which was mixed with the metallic alloy in the form of a starting powder. The structural components have only an extremely small shape retaining stability during the driving out of the binder agent. Thus, the components are very sensitive to any type of contact, and therefore must be supported or covered or otherwise protected by the support, or/base, or/intermediate layers or embedding material, whereby the sintering process is hindered. Besides, friction results at the contact locations whereby the friction forces oppose any shrinking forces. The danger of chemical reaction at the contact locations or contact surfaces is also not excludable at the high sintering temperatures reaching up to about 1300.degree. C.
Further, due to the foregoing surface cracks, pores, or notches may occur or may increase in size. Due to nonuniform shrinking distortions may occur.
OBJECT OF THE INVENTION
It is the object of the invention to contribute to the production of such structural components which are temperature resistant and which have a contour or shape retaining stability, that is, they are true to size and have a smooth surface without cracks.
SUMMARY OF THE INVENTION
This objective has been achieved according to the invention by a method for producing of structural components having a complicated shape which have a high shape stability and dimensional accuracy as well as a high surface quality, and which are made of powder metallurgically processable materials by injection molding or pressing followed by a sintering, said method being characterized in that the prepared mass which contains powder metallurgically processable materials and a binding agent is deformed in an injection molding device or in a press such as a dry press, after heating out the binding agent in a mold. The preformed component or blank is introduced into a gas-tight, heatable container, especially of a vacuum oven or an oven with a protective gas atmosphere and sintered therein, whereby the preformed component or blank is freely exposed to the atmosphere in the oven, and whereby it is suspended or held freely floating so that at least the zones of its surface are exposed and accessible for a treatment, so that said surface zones are desirably free of cracks. According to the invention there is further provided, that said binding agent is added to the powder metallurgical materials for achieving a sufficient flowability, wherein the binding agent is first driven out after the shaping step by applying a burn-out temperature adapted to burn-out the binding agent. The structural components are then heated up to perform said first mentioned sintering step at a temperature between 50% and 70% of the solid status temperature of the powder metallurgical material in a vacuum or under a protective gas atmosphere for a duration of 0.1 to 10 hours, preferably 0.1 to 2 hours. A second sintering step is performed by again heating the blank in the same atmosphere to a temperature up to 400.degree. C. higher than the temperature of the first sintering for a time duration sufficient for closing all cracks present in the outer surface.
BRIEF DESCRIPTION OF THE DRAWINGS
An example embodiment of the invention is illustrated purely schematically in the accompanying drawing.
FIG. 1 shows an injection molded metal sample in its treatment chamber, here a container of a sintering oven;
FIG. 2 shows an injection molded
REFERENCES:
patent: 3432296 (1969-03-01), McKinnon et al.
patent: 4002473 (1977-01-01), Klein
"Metals Handbook", Ninth Edition, vol. 7, Powder Metallurgy, American Society for Metals, Metals Park, Ohio, 44073, pp. 373, 374, 375 and 497.
Andrees Gerhard
Kranzeder Josef
Vogel Wilhelm
Fasse W. G.
Kane, Jr. D. H.
Lechert Jr. Stephen J.
MTU Motoren - und Turbinen-Union Muenchen GmbH
LandOfFree
Construction elements produced by powder metallurgy does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Construction elements produced by powder metallurgy, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Construction elements produced by powder metallurgy will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2120574