DE3210770A1 - Process for the production of metallic, in particular spherical, lightweight elements and for the production of mouldings with inclusion of such lightweight elements, and lightweight elements and mouldings produced by such processes - Google Patents

Abstract

In order to form lightweight metallic elements as filling material for mouldings having closed or open-pore cavities, plastic granules are metallised on the surface up to a coating thickness of about 0.05 mm first by wet-chemical processes and subsequently by electroplating. The metallised plastic granules are pyrolysed by heating at about 400 DEG C and then used as an inclusion material for the formation of lightweight mouldings by casting liquid metal around them or by sintering them at temperatures below the melting point. <IMAGE>

Description

DESCRIPTION:

Process for the production of metallic, in particular spherical Light bodies and for the production of shaped bodies including such light bodies as well as light bodies and moldings produced by such processes, OBJECT THE INVENTION The invention relates to a method of making ketal.

Lischer, especially spherical light body and for the production of molded bodies including such light bodies and by such processes Manufactured lightweight bodies and molded bodies.

PRIOR ART Hollow spheres made of glass and other materials with Diameters from a few microns to millimeters are now available from various manufacturers mainly as a raw material for the production of bodies with a low specific weight offered. Hollow glass spheres, for example, serve as filler and reinforcement material as well as to improve the properties of thermal and duroplastic plastics. Mineral hollow spheres are only conditionally suitable as a lightweight filler for metals.

It is used for the production of low-weight metallic moldings known. Cavities wrong. To form molded bodies that in the Gußforrr for the Metal a bed of soluble granules introduced through special treatment connected to a coherent framework, the remaining cavity then with the intended metal poured out and the granular material. the desired voids forming, is washed out. This process is only for the formation of metal bodies to use with open pores. Around light metallic moldings not closed To produce cavities. one has one similar process developed how it be for plastic foams.

is known. So far, however, this process has only been possible with aluminum will.

OBJECT The invention is based on the object of providing metallic light bodies produce, in particular as a filler material for the formation of moldings with closed or open-pored cavities, and in particular for formation lightweight molded bodies made of metallic base material are suitable.

ACHIEVEMENT OF THE OBJECT The invention works in solving this object on the assumption that it would be useful for moldings made of metal, small ones To use hollow metal balls, which is with the surrounding metal of the molded body is related and with this. a solid connection through mixed crystal formation comes in. So far, however, hollow metal spheres suitable as fillers have not been available Disposal.

In the manufacture of everyday objects made of plastic, such as portable radios, Televisions, door handles and arnatures are known to galvanic processes to be used for metallizing. Urr; to obtain a well-adhering metal coating, These molded plastic bodies have to undergo a whole series of pretreatment stages be subjected. Before going to electroplating by immersion treatment in metal bids activated and catalyzed. iyuss them with repeated intermediate rinsing first degreased and then roughened.

in order to achieve good adhesion of the metal overlap.

This cumbersome and time-consuming process can be used for Ge.

Winnung smaller rr etallic light body according to the invention will. alternatively to commercially available plastic granulate, in particular polystyrene - Metallized foam granulate. This can be done without granules costly pretreatment initially coated with a thin metal film without current are then either in special electroless metallization baths or after the usual galvanic process is further reinforced.

In the case of light bodies according to the invention, there is also the advantageous one Possibility of using the plastic core, which is only used as a mold core, after the metal jacket has been formed to make it completely or partially disappear. This can be done by heating up to the Decomposition of the plastic happen. Most of the plastic goes there into the gaseous state and can escape through diffusion or convection.

There are various possibilities for the application. In particular can light bodies according to the invention as inclusions in molded bodies of the most varied Kind of use. You can z. B. sinter to super-light moldings, which are used in filter technology and as a sandwich panel in space travel etc. can find.

Because of the good gas and liquid permeability of such shaped bodies there is a large contact surface for chemical reactions. The spherical Lightweight metal bodies can also be used as a filler in acid-resistant sintered materials like glass. Coal, metal oxides are incorporated. Will they be due after pre-sintering the microporous structure of the sintered material is extracted with acid very light sintered body of high strength.

When used in charcoal, the spherical light bodies also remain in the sintered material and serve to increase the electrical conductivity. with a simultaneous decrease in density.

DESCRIPTION OF EXEMPLARY EXAMPLES In the drawing, Fig. 1 - 9, the invention is shown schematically in some exemplary embodiments in cross-sectional views, partly in high magnification, illustrated.

Fig. 1 shows a greatly enlarged cross section through (one) one substantially spherical light body 1 according to the invention. This light body consists of plastic and is covered with a metal film 3.

A granular particle is preferably made of sheep synthetic material as the core used. Foam granules are available in sizes from around 0.5 to 3 mm.

In order to achieve self-supporting strength of the metal film, it is sufficient generally a film thickness of about 5 to 15 microns. In the drawing is the metal film Exaggerated for the sake of clarity.

The metal film can be electroless or total. as in Fig. 1 schematically illustrates, in two layers, namely in a first layer 3.1 electroless and then electroplated in a second, thicker layer 3. 2 will. as described in more detail below.

Depending on the size of the hollow metal balls, the layer thickness is from 5 to 15 microns and is then sufficient to prevent the decomposition of the plastic to withstand the resulting gas pressure and to allow for later use as a filling material in connection with various basic materials necessary Eigenfe stigkeit to own.

Foam plastic has a specific gravity of about 0.02-0.08 g / cm³, metal, e.g. B. copper has a specific gravity of 8.9 g / cm³. At a mean diameter of e.g. 1 mm of the metallic granulate particle and one Film thickness of 2 microns results in an average specific weight of the light body according to Fig. 1 from 0.08-0.2 g / cm³.

The specific weight of the light body can still be thereby reduce the fact that the plastic core is subjected to a decomposition process by pyrolization will.

Fig. 2 shows the light body of Fig. 1 after pyrolysis.

At the temperature of about 400 ° C required for this, the remains Metal film 3 preserved in its original form; much of the plastic mass however, it turns into a gaseous state and escapes.

mainly by diffusion, possibly also by convection, if how as described below, it is ensured that dao is contained in an association of light bodies according to Fig. 1 or

2 the core spaces of neighboring corpses communicate with one another. Only a small space then remains in the cavity enclosed by the metal film 3 Remnants of solid matter, especially in the form of coal.

fabric 4.

Fig. 3 shows a schematic representation of a device for electricity loose metal sizing of plastic granulate. consisting of a tub 5 for Taking up a suitable metallization bath, preferably a copper or Nickel bath (available under the name Metylat Cu or Metylat Ni from Blasber, Solingen). The plastic granulate 2 to be metallized is placed in a sieve basket 5. 3 introduced, which is immersed in the bath 5.2.

A motorized stirrer 5.4 turns the granulate into the Bath fluid is swirled around so that the entire surface of its particles is uniform exposed to the metalization process. This electroless metallization can It can be continued until the desired total thickness of the metal film is reached but it is also possible initially to apply only a thin conductive layer 3.1 and the metallization can then be continued galvanically until the desired film thickness is achieved.

Fig. 4 shows a device for galvanic amplification of a first electrolessly applied thin metal film serving as a conductive layer 3. 1, consisting from a tub 6. 1 for receiving the galvanic bath 6. 2, with cathode 6. 3 and anode 6.4. For receiving the plastic granulate 2 provided with the base film 3.1 a sieve drum 6. 5 is provided which rotates around its axis 6. 6. This drum is at the same time cathode sheet through a partition 6.7, in two chambers 6. 8 and 6. 9 subdivided, which the plastic granulate to be metallized 2 approximately each stop halfway. The partition 6, 7 is impermeable to the plastic granulate 2; it can be permeable to the metal ions. The specifically light plastic granulate constantly strives upwards through its buoyancy in the galvanic bath.

Because of the compartmentalization and rotation, it is tongued in a steady manner Change from the cylindrical inner wall of the drum to the flat partition to hike while doing the Cross the chambers filled by the electroplating bath and its entire surface for the deposition of the galvanic from the cathode to the anode to present wandering metal ponds. The anode is in the form of a sieve drum designed with a free spacing receiving trough.

Fig. 5 shows a device 7 for producing a bandage (shaped body) communicating light body in a tub 7. 1 with a currentless one Metallization.

Bad 7.2 and in addition in Fig. 5 a cross section through part of such Molded body 8 on a larger scale. The shape of the molded body to be produced is by a Gefäß1 in the following called Form 7. 1, determined, which is filled to the brim with the to be metallized plastic granulate 2 is filled in such a way that the granulate particles touched each other. In order to metallize this in the device 7, the form 7.1 immersed with the granules in the tub 7.2 or @ bath 7. 3 and for example connected to the bottom of the suction port of a circulation pump 7.4, so that the bath liquid is sucked through the top of the mold and constantly in the direction of the arrow through the Vessel with the granules flows. It will. the entire free surface of the plastic granulate covered with a metal film, while the contact points of the densely packed granules particles remain uncoated. A structure is then obtained after pyrolization of intercommunicating cavities on the one hand and metal films on the other.

Fig. 5 a shows a partial section through such a molded body 8 in a larger Scale. That communication can be important, namely the cavities where there is The aim is to achieve intense convection in or through the shaped body, and the MoUllfilme, in order to ensure a real electrical and thermal conductivity.

Communicating with the outside world can be achieved or avoided through Use of a porous or closed casing, e.g. B. in the form of a Sheathing of the molded body remaining porous or closed form, Fig. 6, 7 show shaped bodies 9 and 10, respectively, cast in partial section with inclusion of light bodies 1 according to Fig. 1 or 2 or with the inclusion of an association of communicating light bodies according to FIG. 5 in a base material 11.

The basic material can consist of various substances, which are pourable or flowable or are otherwise suitable, with the light bodies one to enter into a usable forn-firm connection. For the inclusion of light bodies with a copper film, for example, casting with aluminum or zinc is possible. Rr-it plastic, hardening substances can also be molded with inclusion heretellen of light bodies according to the invention.

Fig. 8, 9 show sintered bodies only made of closed light bodies 1 and from closed light bodies 1 with sintering works.

fabric 14 as the basic material.

REFERENCE SIGNS LIST Fig. 1, 2: 1 light body 1. 1 light body with Plastic core 1.2 pyrolized light body 2 core, plastic granulate 3 metal film 3.1 base film 3.2 film reinforcement 4 carbon Fig. 3: 5 device for electroless Metallization 5.1 Bath 5.2 Metallization bath Bath 5.3 Sieve basket 5.4 Agitator Fig. 4: 6 device for electroplating 6. 1 tub 6.2 electroplating bath 6.3 cathode 6.4 anode 6.5 Sieve drum 6. 6. Axis of 6. 5 6.7 Partition wall, cathode sheet 6.8 6. 9 chambers from 6. 5 Fig. 5: 7 device for the production of moldings 7.1 Form 7.2 tub 7.3 bath 7.4 circulation pump 8 form body, fig. 5, 5a fig. 6 - 9: 8, 9, 10 Shaped body made of base material with lightweight single keys 11 base material in 9, 10 12 secured molded body made of closed light.

bodies 13 sintered molded bodies made of closed lightweight bodies with a sintered material as the base material 14 sintered material

Claims (19)

PATENT CLAIMS Process for the production of metallic, in particular Bullet. shaped light body, characterized in that plastic granules (2) is metallized on the surface. 2. The method according to claim 1, characterized by using Foam plastic. 3. The method according to claim 1 or 2, characterized by metallization in a wet chemical process. 4. The method according to claim 3, characterized in that the coating by galvanic means up to a layer thickness of preferably a maximum of about 0, 05 mm is continued. 5. The method according to any one of claims 1 to 4, characterized in that that metallized plastic granulate (29 is pyrolyzed (i.e. to the point of disintegration of the plastic is heated to around 400 ° C). 6. Process for the production of molded articles with lightweight elements. key. characterized by the use of lightweight bodies (1) according to one of claims 1 to 5 as the inclusion material. 7. The method according to claim 6, characterized in that many light. body (1L) are poured in a mold with liquid metal. 8. The method according to claim 6, characterized in that a bed of light bodies (1) in a form at temperatures below the melting point is sintered. 9. Veriahren according to claim 8, characterized in that the bed is sintered together with a surrounding sintered material, 10. Metallic Light body, characterized. that he was made of a metal coated Granulate particles (1) made of art. substance is made. 11. Metallic light body according to claim 10, characterized in that that it consists of a metal-coated core (1) made of plastic foam. 12. Metallic light body, characterized in that it is characterized by Heating of a metallized light body (1) according to claim 10 or 11 to Decomposition temperature of the plastic used. core (1) (pyrolysis) is formed. 13. Shaped body, the base material of which has many inclusions after molding having relatively low specific gravity, characterized in that the Inclusions made from metallic lightweight bodies (1) according to one of Claims 10 to 12 exist. 14. molded body according to claim 13, characterized by closed Inclusions. 15. molded body according to claim 13 or 14 characterized by communicating Inclusions. 16. Molded body according to one of claims 12 to 14, characterized. that the inclusions have a higher electrical and thermal conductivity as the basic material surrounding them. 17. Shaped body according to one of claims 13 to 15, characterized in that that light bodies (1) are sintered together. 18. Forn body according to claim 17, characterized by the lightweight body surrounding sintered material (14) as the base material. 19. Shaped body according to claim 18, characterized. that the sintered material (14) consists of cunot coal.