DE10333038B4 - Process for pressure infiltration of porous components - Google Patents

Abstract

Process for pressure infiltration of porous components characterized
that in a first method step the component (1) is covered with a first infiltration liquid (2),
at least two areas of the component surface do not come into contact with the infiltration fluid (2),
that in a second method step, the component (1) is freed on the surface largely from the first infiltration liquid (2) and the remaining portion is solidified, in such a way
a gas-tight layer (3) is formed on and / or in the edge regions of the porous component (1),
in a third method step, the sealed porous component (1) is immersed in a second infiltration liquid (4), in such a way
That at least a first of the areas not covered by the gas-tight layer comes into contact with the second infiltration fluid (4), and
- That at least a second of the not with the gas-tight layer (3) covered areas with a relation to the ...

Description

The The invention relates to a method for pressure infiltration of porous components according to the generic term of claim 1

The pressure infiltration is known: A porous preform is placed in a mold. In this form, a liquid is introduced under high pressure, which then infiltrates the porous preform. See eg the DE 100 47 384 A1 , The disadvantage is the relatively large amount of time for the production of preform, form and end product. The material properties of such a composite material are advantageous.

The production of the porous preform by means of laser sintering promises time advantages, cf. DE 199 09 882 A1 , The rapidly produced porous preform is then to be infiltrated by simple immersion in liquid brazing material due to capillary action. With larger dimensions or poor wetting longer infiltration times and / or uneven infiltration are to be expected. Also questionable is the dimensional accuracy due to superficially adhering and subsequently solidified infiltration material.

The The object of the present invention is therefore a method to specify without tool molds for infiltration of porous components, which high component accuracy, uniform infiltration, and has low cycle times.

These Task is by a method with the characteristics of the preamble of claim 1 solved by its characterizing features. advantageous Embodiments are specified in the subclaims.

According to the invention, in a first method step, a porous component is covered with a first infiltration liquid,
at least two areas of the component surface do not come into contact with the infiltration liquid,
in a second process step, the component is freed on the surface largely from the first infiltration liquid and solidifies the remaining portion, in such a way
a gas-tight layer forms on and / or in the edge regions of the porous component,
In a third process step, the sealed porous member is immersed in a second infiltration liquid, such
at least a first of the regions not covered by the gastight layer comes into contact with the second infiltration liquid, and
at least a second of the areas not covered by the gas-tight layer is subjected to a lower pressure than the first area,
in a fourth process step, the sealed porous member is removed from the second infiltration fluid as soon as the infiltration is stopped.

there the infiltration is stopped when the infiltration fluid at the second area exits the component or if no further Material flow takes place or should take place.

Usually becomes the second infiltration fluid within the porous Component then solidified. However, it is also conceivable their inlet and outlet openings in the sintered body to seal and thus prevent a continuous leakage. A quick outflow anyway hardly occurs due to capillary action.

through the first step very quickly becomes a thin layer on the surface (and due to capillary action also brought in), which after their solidification as a gas-tight form for the subsequent fast Pressure infiltration is used. The covering of the component with the first infiltration liquid is preferably done by dipping, spraying or brushing.

Of the second step ensures a high dimensional accuracy of the infiltrated component. The third process step includes the actual pressure infiltration. The fourth process step guaranteed the complete or maximum or desired filling of the porous one Component between inlet and outlet. The latter are according to the To arrange component requirements. Can connect a renewed Relief of excess infiltration fluid to guarantee the dimensional stability.

suitable Inlet and outlet openings are particularly easy to apply by applying masks to the porous Create component. The can Masks basically on any releasable Way to be fixed on the component. Is advantageous doing an attachment alone along the edge of the mask. Especially it is advantageous for the latter Pressure infiltration when at least one mask is used, the is designed as a pressure connection with passage to the porous component, so that at these at least one pressure connection in the third step the lower pressure can be applied.

According to an advantageous embodiment In the method according to the invention, during the second method step, the component is flowed through by a gas flow in such a way that the adhering first infiltration liquid flows off at least partially from the surface and thus no substantial thickening of the component occurs as a result of its solidification. Small amounts of the remaining infiltration liquid are usually sucked by capillary action in the near-surface pores, so that no thickening takes place. The solidified thin layer on the surface and in the near-surface pores is sufficient to serve as a gas-tight mold for subsequent pressure infiltration.

To In the second method step, the porous component has a solidified, gas-tight envelope with at least two openings on. The first of these openings is dipped in a second infiltration liquid and between the first and second openings becomes a pressure gradient which accelerates the second infiltration fluid (compared to pure Capillary effects) in the porous Component penetrates. The pressure gradient may alternatively or additionally by applying a negative pressure to the second opening (which is preferably covered by a mask with pressure connection) and / or by applying the second infiltration fluid with an overpressure be generated. The overpressure may be by gas, immiscible liquid or a solid (e.g. Piston) are exerted on the second infiltration fluid.

The porous component can be produced particularly quickly and inexpensively by means of a rapid prototyping method. Suitable methods are laser sintering or 3D printing, but also by means of the so-called Laminated Object Manufacturing (LOM), suitable porous components can be produced quickly and inexpensively, cf. DE 10157757 A1 ,

The Procedure can for Any combination of materials can be used. As base material for the porous component are all Suitable solids, in particular plastics, metals or ceramics as well as their mixtures. For the infiltration fluids applies in principle the same, but with consideration be taken on the material properties of the base material must: for a porous one Plastic-based component is a molten metal (except the low-melting alloys) as infiltration fluid not suitable because it would destroy the base material. Suitable are curable plastics (Duromers, in particular resins, for example epoxy, acrylate, phenolic and polyurethane resins; or thermoplastics, the latter in particular if a renewed liquefaction is required) or waxes and silicones. For metallic or ceramic porous Components are in addition to the already mentioned infiltration fluids also suitable for metal melts (metal matrix composite).

Hereinafter, the inventive method using two embodiments and the 1 to 6 explained in more detail:
Showing:

1 An abstracted porous component 1

2 The component 1 with masks 12 and 13 and a pressure port 14

3 That with the masks 12 . 13 provided component 1 immersed in a first infiltration fluid 2 to produce the gas-tight layer 3

4 That from the first infiltration fluid 2 removed component 1 with gas-tight layer 3 and removed mask 12

5 That with the masks 13 and the gas-tight layer 3 provided component 1 immersed in a second infiltration fluid 4 for pressure infiltration

6 The completely infiltrated part (without mask)

In a first embodiment, 3D-printing first of all becomes a porous component from coated PMMA particles 1 produced; see. eg DE 10227224 A1 , On the top and bottom of this component 1 become two masks 12 and 13 adhesively bonded by means of commercial adhesive along the mask edge. The mask 13 has a pressure connection 14 with passage 15 to the porous component.

In a first process step, the thus-prepared component 1 with an epoxy resin 2 coated on all sides, leaving only the masks 12 . 13 covered areas free of epoxy resin 2 stay. The resin residue adhering to the surface is sucked into the body by capillary action. As a result, the component is superficially freed from the first infiltration liquid - the resin. Thereafter, the resin is cured and a solidified gas-tight layer is formed 3 ,

In an alternative first method step, the thus-prepared component 1 with a low melting wax 2 sprayed on all sides, leaving only the masks 12 . 13 covered areas free of wax 2 stay. In a second process step, the component 1 emitted with a warm air jet in the same direction, so as to ensure a uniformly thin wax layer on and in the component surface. Thereafter, the wax is cured by cooling and there is a solidified gas-tight layer 3 ,

In a third process step, the mask 12 from the component 1 removed and the pressure connection 14 the mask 13 is connected to a vacuum line. The component 1 is in liquid epoxy resin 4 , which is under normal pressure, so far submerged that at least the open bottom side of the component (at the previously mask 12 was covered). Due to the pressure difference between the open bottom of the component and the pressure connection 14 on the upper side of the component, the second infiltration liquid infiltrates epoxy resin 4 the porous component 1 with comparatively high speed. The infiltration is continued until the epoxy resin 4 exits at the top of the component. Thereafter, the infiltrated component 1 removed, excess, externally adherent epoxy resin 4 is emitted by means of gas steel and the infiltrated epoxy resin 4 is solidified. The infiltrated component 5 is finished.

In a second embodiment of the construction, laser sintering initially makes a porous component of SiC or steel particles 1 produced. On the top and bottom of this component 1 become two masks 12 and 13 releasably clamped. The mask 13 has a pressure connection 14 with passage 15 to the porous component.

In a first process step, the thus-prepared component 1 preheated and depressurized in a high-melting aluminum alloy melt 2 dipped on all sides, leaving only the masks 12 . 13 covered areas free of the melt 2 stay. In a second process step, the component 1 Radiated with a protective gas jet in the same direction, so as to ensure a uniformly thin aluminum layer on and in the component surface. The gas jet acts simultaneously cooling. Thereafter, the melt is cured by cooling and there is a solidified gas-tight layer 3 ,

In a third process step, the mask 12 from the component 1 removed and the pressure connection 14 the mask 13 is connected to a vacuum line. The component 1 is preheated and into a lower melting aluminum alloy melt 4 , which is under pressure, so far submerged that at least the open bottom of the component (at the previously mask 12 was covered). The chamber temperature above the melt 4 is adjusted so that the non-submerged higher melting layer 3 does not melt, but that the preheated component remains sufficiently warm, so that the low-melting aluminum alloy melt 4 does not harden during infiltration in the component by cooling and blocks complete infiltration.

Due to the pressure difference between the open bottom of the component and the pressure connection 14 on the upper side of the component, the second infiltration liquid infiltrates aluminum alloy melt 4 the porous component 1 with comparatively high speed. The infiltration is continued until the aluminum alloy melt 4 exits at the top of the component. Thereafter, the infiltrated component 1 taken, excess, externally adherent aluminum alloy melt 4 is emitted by means of gas steel and the infiltrated aluminum alloy melt 4 is solidified by cooling. The infiltrated component 5 is finished.

The inventive method proves in the embodiments the examples described above are particularly suitable for construction prototype tools and MMC functional components, especially in the automotive industry.

Just MMC materials can thus be produced particularly quickly and inexpensively.

The Invention is not limited to the previously described embodiments limited, but rather transferable to others.

So In particular, metal-infiltrated porous ceramic components prove to be suitable (For example: SiC / Al) as material technology particularly advantageous.

Of further is the inventive method for components any size applicable. Optionally, each have a plurality of inlet and outlet openings in the porous one Provide component or the component is first to divide and after the To unite infiltration.

1

Porous component

12

mask (Underside)

13

mask (Upper side)

14

pressure connection

15

passage to the component

2

First infiltration liquid

3

Sealed layer

4

Second infiltration liquid

5

infiltrated component

Claims (8)

Method for pressure infiltration of porous components, characterized in that in a first method step, the component ( 1 ) with a first infiltration fluid ( 2 ) such that at least two regions of the component surface are not covered with the infiltration liquid ( 2 ) in contact come that in a second process step the component ( 1 ) superficially largely from the first infiltration fluid ( 2 ) and the remaining portion is solidified, such that a gas-tight layer ( 3 ) and / or in the edge regions of the porous component ( 1 ) that in a third process step the sealed porous component ( 1 ) into a second infiltration fluid ( 4 ) in such a way that at least a first of the regions not covered by the gas-tight layer is in contact with the second infiltration liquid ( 4 ), and - that at least a second of the non-gastight layer ( 3 ) is subjected to a lower pressure compared to the first region, that in a fourth process step the sealed porous component ( 1 ) from the second infiltration fluid ( 4 ) is removed as soon as the infiltration is stopped. A method according to claim 1, characterized in that when covering the component ( 1 ) with the first infiltration fluid ( 2 ) at least two areas of the component surface with masks ( 12 . 13 ) so that these areas do not interfere with the first infiltration fluid ( 2 ) get in touch. Method according to claim 2, characterized in that at least one mask ( 13 ), which is used as pressure connection ( 14 ) with passage ( 15 ) to the porous component ( 1 ) and that at least one pressure connection ( 14 ) is applied in the third step, the lower pressure. Method according to one of the preceding claims, characterized in that the component ( 1 ) for the superficial liberation of the first infiltration fluid ( 2 ) is flown by a gas stream such that the adhering infiltration liquid ( 2 ) flows at least partially and thus no significant component thickening takes place by solidification. Method according to one of the preceding claims, characterized in that in the third method step to the second infiltration liquid ( 4 ) is exerted relative to the normal pressure increased pressure. Method according to one of the preceding claims, characterized in that the porous component ( 1 ) is produced by means of a rapid prototyping method, preferably laser sintering or 3D printing. Method according to one of the preceding claims, characterized in that as the first infiltration liquid ( 2 ) a silicone and as a second infiltration fluid ( 4 ) a resin is used. Method according to one of claims 1 to 6, characterized in that as first and second infiltration liquid ( 2 . 4 ) a molten metal is used.