DE1181671B - Permeable, essentially compact metal material for filtering purposes - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school KI .: BOId

Number:
File number:
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German class: 12 d - 25/02

F 35331 VIIb / 12 d
November 10, 1961
November 19, 1964

The invention relates to a permeable, substantially compact metal material for filtering purposes made of disorganized, interlocking, long and thin metal fibers.

It is known to use solid steel wall fibers, which are pulped into a filter vessel, as liquid filter material to use. For remote filtering purposes, i. H. for filtering out solids in the order of magnitude only a few microns, this filter material is not suitable because the pore spaces between the fibers are too big. The same applies to a known filter material made of flat metal tape, the is spirally wound on a carrier and thereby forms a cylindrical filter element. as well can be known by squeezing and sintering together stainless steel wires in No fine porosity for filter purposes, just a relatively coarse filter material are formed.

The same applies to a filter material made of melted, but again compact metal fibers that create a pore size of 10 to 60 microns between them. On the other hand, a certain Fine porosity can be guaranteed in a manner known per se by sintered metal, which by Sintering together of powdery particles has been produced. But this material does not have any Fiber structure and therefore not the permeability properties that are required for a filter material according to of the invention are required, which must not have the structure of a compact sintered metal block.

Also the well-known sintering together of compact fine steel wires or compact metal wool fibers or of glass threads does not produce the fine structure desired according to the invention.

The invention aims at a metal material compared to the known filter materials of the aforementioned type to create with a fine structure, its filter properties, in particular its filter efficiency in terms of permeability for the filtrate and retention capacity for dirt particles at least those of the highest quality filter materials made of paper or treated with synthetic resin Are the same as paper, but are much better than the best filters made of fine steel wire mesh to date, ζ. B. the so-called Dutch Twill Weave, even if this fabric is made with sintered metal powder has been made particularly fine-pored; however, in contrast to paper filters, the high Temperature resistance, e.g. B. can be guaranteed for use at temperatures up to 150 ° C and more, which have the well-known metal filters.

Permeable, essentially compact
Metal material for filtering purposes

Applicant:

Fram Corporation, Providence, R. I. (V. St. A.)

Representative:

Dr. W. Schalk and Dipl.-Ing. P. Wirth,

Patent attorneys,

Frankfurt / M., Große Eschenheimer Str. 39

Named as inventor:

Robert William Turnbull, Barrington, R. I.

(V. St. A.)

Claimed priority:
V. St. v. America November 16, 1960
(69 685)

This aim is achieved according to the invention for a filter material of the type mentioned at the outset achieved that the metal material consists of hollow metal tubes with a wall thickness of less than 1 micron to a few microns consists of more or less within the associated structure are compressed flat to the compact material, namely by tubes, as they are in the destruction organic, metal-plated carrier strands or fibers remain.

The metal fibers compressed in this way are preferably at their points of contact also sintered together in a manner known per se.

The filter material according to the invention results in a filter efficiency of up to 99%, below that Filter efficiency the retention capacity for dirt particles as a percentage of that to be filtered Medium added amount of dirt particles is to be understood as described in more detail below Way is measured according to certain prescribed standards. This filter efficiency is still slightly larger than that measured in the same way with filter paper reinforced with synthetic resin (Kraft paper) and was significantly larger than with stainless steel fabric with or without likewise measured

409 728/298

Sintered powder coating. Compared to paper indispensable for many applications advantage is achieved that the filter material up to 15O ⁰ C or more, ie for. B. can also be used for hydraulic pressure medium and oils, as they must be used under such temperatures when operating aircraft.

The filter according to the invention is also suitable for filtering out solids under such circumstances on the order of a few, e.g. B. 10 to 20 microns.

One method of making a permeable metal material according to the invention is that a mass of randomly distributed organic carrier fibers or strands and longer and thinner ones interlinked or matted fibers are produced, a thin metal jacket on each individual Fiber or each fiber strand is applied, then the fibers or strands are destroyed in the mass without destroying their metal sheaths, and finally this hollow sheath into a compact, permeable mass are compressed. Devices to hold fibers or other objects Metal vapor deposition plating are known, and it can be used for the purposes of the above Method made use of this in the production of the metal material according to the invention will.

The length and circumference of the carrier fibers or strands to be used in this process can vary greatly, and the length can be between a fraction of a Centimeters up to 2.5 or more centimeters. In most cases, however, it is advisable to to produce a fiber mat or a fleece from the organic strands and this fiber layer of the aforementioned, to subject so-called gas plating, in which then each individual fiber or each Fiber strand receives a thin metal jacket. The wall thickness of the metal jacket produced in this way can be less than 1 micron or a few microns.

The compressed hollow sheath remaining after the fibers or strands have been destroyed or fiber mats from hollow sheaths can according to the invention still as a whole or at least in their points of contact are sintered together to prevent migration of the fibers within the then formed to prevent solid metal layer.

The invention is explained with reference to the drawings. It shows

Fig. 1 is a perspective view of the fleece or the layer of textile fibers or strands,

F i g. 2 on a greatly enlarged scale some of the strands or fibers according to FIG. 1, after each The fiber has been surrounded by a thin metal jacket,

F i g. 3 is a perspective view of a porous metal layer obtained by incorporating the fibers or strands according to FIG. 1 coated with metal, then the carrier fibers destroyed and the remaining ones Metal jacket are pressed together,

F i g. 4 shows a diagrammatic view, on a greatly enlarged scale, of part of the porous metal layer according to FIG Fig. 3,

F i g. 5 shows one of the compressed or collapsed metal jackets on an even larger scale according to FIG. 4 and

6 is a perspective view of a filter disk or a catalyst which is obtained from the mat according to FIG. 3 has been cut out.

The fleece or the layer according to FIG. 1 can be any desired thickness, width and length. This layer is provided with the reference number 10 and consists of fine individual fibers or threads or Fiber strands 11. It is essential that these fiber strands or individual fibers, hereinafter usually referred to as "Carrier strands" are referred to, consist of organic fibers or threads, which, as will be described later can be practically completely decomposed by heat.

These carrier strands 11 can be natural fibers, such as cotton, or synthetic fibers, such as. B. pressed viscose threads. These extruded threads are preferably too proportionate cut or broken small lengths, ranging from a fraction of an inch up to Can be 2.5 cm or more inches so that they can be blown on top of each other or otherwise haphazardly can be stacked to form a layer 10 of the desired size and thickness deliver. If the layer 10 consists of cotton fibers, these tend to be entwined with one another or matting which is desirable. If the fiber layer consists of synthetic fibers or man-made fibers, so these fibers are preferably initially crimped so that they interlock in the layer 10 gobble up or matted. The carrier fibers 11 are preferably fine for reasons to be stated Fibers.

Thin metal sheaths or coatings 12 are applied to the individual fibers or fiber strands 11. These sheaths can be applied to continuous strands of synthetic fibers made of synthetic threads by passing these fibers through a metal vapor deposition chamber as in the above-mentioned patents, and then cut the coated filaments into short lengths and arbitrarily one above the other in the one shown in FIG. 2 can be arranged.

Preferably, however, the layer 10 of organic is arranged in a random or disorderly manner Fibers 11 are produced as described above and then become the carrier strands 11 throughout the layer

10 by means of a metal vapor coating method to be described now covered with metal. Each fiber of the layer becomes with this coating encased in a thin metal jacket which may be less than 1 micron thick and up to Can be 1 micron. If cotton fibers are used as carrier strands, their cross-section is not is round, the applied jacket also has a non-round cross-section, whereas in the case of the Using round drawn threads as carrier strands, the metal jacket has a round cross-section own.

The method of covering the carrier strands

11 in the mat or fleece 10 with metal consists in that the organic fiber layer 10, 11 is suspended in a chamber with windows permeable to infrared radiation, the chamber is _{cleaned with an inert gas such as CO 2} or N ₂ , the layer is cleaned by means of externally arranged infrared heater is heated to a temperature which is above the decomposition temperature of the plating vapor, and then the plating gas with a carrier gas such as

N ₂ or H ₂ , mixed, is supplied until a plating layer of the desired thickness has deposited on the fibers 11. The plating gas can be any metal carrier gas or a volatile liquid such as iron or nickel carbonyl, the decomposition temperature of which is lower than the decomposition temperature of the organic fibers. In this way, a sheath 12 of the desired thickness is deposited on the carrier fibers 11.

The fleece is then heated in an inert or reducing atmosphere, for example N ₂ or H ₂ , to a temperature which is high enough to glow the metal and to decompose or destroy the organic fibers 11. So the jackets 12 remain as empty tubes or hoses. In the case of a nickel coating on cellulose, this destruction can take place at a temperature of about 760 to about 815 ° C., this temperature being below the melting point of nickel. The mat is then cooled to room temperature and compressed to the desired thickness and average density, creating a permeable metal layer of partially or practically completely flat hoses or tubes. This layer 13 of compressed tubes is shown in FIG. 3 shown. The layer consists entirely of hollow metal jackets 14. These jackets, which can have a length from a fraction of a centimeter to several centimeters, are predominantly referred to as "metal fibers" above and below.

Since it is the main purpose of the invention, a porous metal material with an extremely fine pore structure To create, the carrier fibers or strands 11 should have a small diameter or Have cross-section, and the metal sheaths applied to these fibers should be very thin, for example no thicker than a few microns.

After the permeable layer 13 of more or less flattened metal jackets 14 in the described manner and the fibers have been sintered together to form them To keep their position, porous disks, as shown in FIG. 6 and denoted by 15 are cut out, or the permeable layer 13 can be otherwise used. In this way, the porous metal layer 13 can be folded and this folded material can be shaped into a cylinder which can be used as a high-temperature metal filter with a very fine pore structure from a flowing medium is.

If desired, the porous metal layer 13 can be reinforced by adding on one or both sides the layer 13 a suitable metal mesh or mesh (not shown) is applied. The metal layer 13 can with this wire mesh or metal mesh in a reducing atmosphere sintered together at the time and temperature appropriate for the given metal and fiber size will. The reinforced porous metal layer or the filter medium can then be added to any desired shape can be deformed.

From the foregoing it can be seen that the manufacture of the described permeable Metal material made of very fine metal sheaths, a metal layer with an extremely fine pore structure results, in which the metal fibers are entangled. Depending on the application, the one described in the Wise made metal fiber mass,

d. H. depending on the medium to be filtered and the size of the particles to be filtered out, the degree the permeability can be designed differently.

The filter efficiency, ie the ability to retain dirt from a medium to be filtered, can be measured in the filter material according to the invention as a percentage of the amount of dirt added to the medium in the usual manner with a measuring device, which is also otherwise required for paper filters and the like. A filter sheet made of the filter material according to the invention with a size of 24.2 cm ² is placed in the form of a filter insert in a sample housing, in which the insert is traversed by the entire flow of a hydraulic medium to be filtered, which via a control valve with a predetermined pressure into the Sample housing enters. In front of the valve, glass beads with a diameter of 10 to 20 microns and a weight of 0.5 g are evenly mixed into the hydraulic medium as a contaminant. The amount of hydraulic medium is 2000 ml, and the amount of pollutant mixed with it is 0.5 g. The flow rate is set to 1.31 per minute on the valve located between the mixing chamber and the sample chamber. The air pressure acting on the medium to be filtered is set to 2.8 kp / cm ² by means of a control valve.

After flowing through the sample chamber, it is rinsed with 1000 ml of petroleum naphtha and then with 1000 ml of petroleum ether. The total of 4000 ml of liquid collected behind the sample chamber is left to stand for 16 hours in a beaker with a liquid height of 16 × 1.2 cm = 19.2 cm. After the heavier liquid has settled, the lighter liquid is sucked off to a liquid level of 2.54 cm. The remaining heavy liquid is allowed to flow through a fritted glass filter. After drying the residue remaining on the filter at a temperature between 70 and 93 ° C. and cooling in a desiccator, the dry residue, which consists of glass beads, is weighed. The filter efficiency is calculated in percent from its weight X using the formula

0.5 g

With this test arrangement and with this type of test implementation, for the inventive Filter material when filtering out the pollutant from a hydraulic pressure medium, namely a light oil with a viscosity of 17 cSt at 98 ° C a filter efficiency of 99.0% found. The same test procedure with the same hydraulic means resulted in a filter sheet made of synthetic resin treated Kraft paper 98.5%, with a steel wire mesh of 200 weft wires and 1400 warp wires made of stainless steel 95.6% and with the same fabric plus applied sintered metal powder 97.0% filter efficiency.

In addition, it was found that the absorption capacity of the filter material according to the invention for the contaminant, d. H. its useful life, about twice that of the one with or without sintered Powder-provided wire mesh is, the production of which is also even more complex than that

this filter material according to the invention, which has the same temperature resistance as wire mesh made of the same metal.

Claims (3)

Patent claims: 1. Permeable, essentially compact metal material for filtering purposes, made of disordered running, interlocking, long and thin metal fibers, characterized in that that the material (10) consists of hollow metal tubes (12) with a wall thickness of less than 1 micron to a few microns, which are compressed more or less flat to the compact material (14) within the disordered structure, namely of tubes, as they occur when organic, metal-plated carrier strands (11) or Fibers remain. 2. Permeable metal material according to claim 1, characterized in that the metal tubes (14) are sintered together at their points of contact in a manner known per se (13). 3. A method for producing a permeable metal material for filtering purposes according to a of claims 1 or 2, characterized in that a fleece of randomly distributed organic Carrier fibers or strands with longer and thinner interlinked or matted Fibers is made, a thin metal jacket on each individual fiber or each fiber strand is applied, intestine the fibers or strands in the metal jacket are destroyed and finally these hollow jackets are compressed and sintered to form a compact, permeable filter material will. Considered publications: German Patent No. 515,852; German interpretation document F11378 IVc / 12 d (published on December 20, 1956); U.S. Patent Nos. 1774 232, 2,945,591,
2834730; VDI magazine, vol. 98 (1956), p. 844, as well as vol. 102 (1960), pp. 1301 ff; Chemical Engineering, 1960, pp. 209-212. 1 sheet of drawings 409 728/258 11.64 © Bundesdruckerei Berün