DE1204204B - Process for densifying materials in particulate form - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

BOIj

German KL: 12 g-1/01

Number: 1204 204

File number: E 22289IV a / 12 g

Filing date: January 23, 1962

Opening day: November 4, 1965

The invention relates to a method for compacting substances present in particulate form, especially of powder and / or fibrous substances, e.g. B. of powdered metals or metal carbides, under high pressure.

Solid bodies are usually made from powders and / or fibers by pressing and sintering Hot pressing, by pressing and infiltration of molten substances, by flame spraying or produced by using the slip casting technique and firing. The bodies thus obtained have however, usually less due to voids between the granules and particles pigeon than the powders and fibers from which they were made.

The use of dies to compact these porous bodies is not entirely satisfactory » because the pressure is not the same in all directions and there are therefore no uniform densities receives. The application of a hydrostatic pressure leads to an action in all directions same pressure, but when compressing the porous body by means of direct hydrostatic pressure, d. H. when the hydrostatic fluid is in contact with the workpiece, fluid enters the pores so that no compression takes place and also when the pressure is relieved one Explosion of the body can occur. It is also known to be used for pressing powdery substances a rubber container to use (see. German Patent 958 261). Such containers are true Sufficient at lower hydrostatic pressures, but not at high pressures.

The method according to the invention for compacting substances present in particulate form consists in that the particles are enclosed in a jacket made of an inelastic material, the one has high compressibility and a sudden increase in density at a given pressure suffers, and then exerts a hydrostatic pressure on the jacket, which is at least as is as high as the pressure required for the sudden increase in density of the jacket material, on which one removed the jacket from the compacted mass.

This method allows the use of hydrostatic pressures higher than the usual hydrostatic pressures without that liquid can penetrate into the compacted body. The product has a high density on that with the density of the same material that is in a "non-porous" way, i. H. without using a Powder or of fibers as starting material, is produced, is comparable.

Process for densifying in particulate form
present substances

Applicant:

Engelhard Industries, Inc., Newark, N.J.

(V. St. A.)

ίο ".... Representative:

Dr.-Ing. W. Abitz, patent attorney,
Munich 27, Pienzenauer Str. 28

Named as inventor:

Alfred R. Bobrowsky, Livingston, NJ
(V. St. A.)

_ao claimed priority:

V. St. v. America 23 January 1961 (83 989)

According to a preferred embodiment of the invention, the substance is present in particulate form before it is enclosed in the jacket, it is converted into a porous, coherent mass by means of a pre-deformation process, which already has the shape of the end product

According to another embodiment of the method, the pre-compression and pre-deformation omitted and the powdery and / or fibrous material enclosed directly in the jacket and condensed. The porous mass is enclosed in the jacket, for example, by digging into the jacket wall cuts an opening at the top, pours the particles into it and then the opening with it an insert and a sealant made of the same material from which the jacket is made, locks. The exertion of the high hydrostatic pressure on the jacket makes it porous Powder mass compressed into a cohesive mass of high density. This cohesive Mass can then be brought into the desired shape, e.g. B. by punching or Cut.

In the method according to the invention, a jacket made of a material is preferably used the compressibility of which is higher than that of the pre-deformed mass or even higher than that of the compacted end product.

509 720/409

I 204 204

3 4

The jacket material should also be applied before the pre-pressing and pre-forming after the

or relieving the pressure the porous mass not preferred embodiment can the powder a harmful affect. When the coat is mixed out of the binder. Examples of such Melt is applied to the porous mass, binders are for tungsten fibers and copper a noticeable penetration into the porous mass 5 cobalt for binding carbides, such as titanium, is to be avoided be what you, if necessary, by carbide.

Addition of non-wetting agents, e.g. B. Lubricating oil, to apply the hydrostatic pressure

can reach to mass. the coated sample to be compacted in the press

Sheath materials that use a sudden compression or volume io hydrostatic pressure device at a certain height cylinder or the compression chamber of a conventional pressure. The reduction experienced are z. B. cerium, cesium, highest pressure achievable with this device Bismuth and low-melting bismuth alloys can be below the pressure required for the desired densification, such as alloys of 40% bismuth and 60% lead; by the use of 50% bismuth and 50% lead or 55% sheath, the high compressibility comprising bismuth and 45% lead, and also silver, a Legie- i ₅ and at a certain high pressure from a plötzrung 70% thallium, and If 30% indium or a slight compression is experienced, higher pressures will be an alloy of 97.5% thallium and 2.5% tin. achieved than with the conventional devices. Those jacket materials are preferred that can be achieved.

the sudden compression occurs at pressures which after compression can cause the jacket to move away from the

be melted in an ao compacted body suitable for the hydrostatic press. the Work area. In some cases the removal can also be done in other ways, e.g. B. by the compression from a polymorphic transformation cutting, dissolving, evaporating, cooling down to the crystal structure into a denser crystal structure. Embrittlement and breakage or by grinding In other cases, the sudden compression is likely to occur.

The substances that can be compressed according to the invention to an electron closer to the atomic nucleus include powdered and / or fibrous metals and shell, and in still other cases non-metals occur. The metals include the iron, a sudden compression under certain circumstances, metals, high-temperature alloys, such as nickel, which are not fully clarified. In the following table _m d chromium-containing alloys, e.g. B. one, the pressures for three elements are listed, with ₃₀ alloy of 78.75% nickel, 14% chromium, 7% of which a sudden compression occurs. Iron, 0.2% copper and 0.05% carbon, or

Cobalt-chromium-nickel-molybdenum alloys, e.g. B. an alloy of 51.6% cobalt, 26% chromium, 15% nickel, 6% molybdenum, 1% iron and 0.4% 35 carbon, also bearing metals, such as bronzes and graphite containing bronzes. The powdery and / or fibrous non-metals include, for example, carbides, e.g. B. titanium carbide bound with cobalt, tungsten-titanium carbide (without binder - the volume changes are relatively large; 4 ° additional) and silicon carbide. Other powder and / or they amount to about 9% for bismuth and fibrous non-metallic substances for cesium, which can be compressed according to the approx. 11%. E.g. B. aluminum oxide, lanthanum oxide, beryllium oxide from an alloy of 52% bismuth, 32% lead and magnesium oxide, suffide, telluride or selenide and 16% tin with a melting point of 95 ° C. 45 of the lanthanides, bismuth telluride, lead telluride, lead da the mantle at high pressure suddenly produces selenide and gallium arsenide, silicides, e.g. B. MoSi ₂ , experiences compression, the enclosed porous boride, such as chromium boride, and nitride, such as boron body is subjected to an increased pressure, the nitride. These substances "have, if they are in powder form, ie in the form of fine, free pressure, at the beginning of the process, which is much higher than that exerted on the jacket. 50 flowing (free-flowing) particles are present

The porous, typical particle size of about 15 to 150 μm obtained during prepressing. if sealed bodies made of powder and / or fiber they are in fiber form, they have a diameter Shaped fabric can be enclosed in the sheath by 0.25 mm and below. More metallic are made by cladding the body with fibers that can be compacted are metals pouring around the two halves of a previously 55 in the form of "whiskers", ζ. B. dispersed in copper cast jacket around the body arranges platinum "whiskers". Such a material is obtained and weld the seams or by melting the copper, the platinum The material to be enclosed is added to the melt in a previously cast »whisker« and up to the ErMantel Introduces through an opening and this then cools the copper hard. The expression "Whisverschschlßt. 60 kers "is in an essay" Metals Reinforced with

According to the invention, hydrostatic pressures are fibers "in" Metal Progress ", September 1960, p. 118 over 10,000 at, especially pressures of around 20,000 to 121, and in "Materials in Design Engineering", to 60,000 at is preferred. At the prepress and September 1960, p. 134, explained. Further fiber preforming pressures are sufficient at which the powdery non-metals deform according to the invention Fabric that can be sealed together to form an adherent mass 65 are ceramic fibers, is compressed. The duration of action of the hydro- preferably those with high tensile strength, eg. B, Static pressure can be from about a second in a cobalt-chromium alloy dispersed sapphire bison range to an hour or more. (Aluminum oxide) fibers. Making this

element Pressure (at) cerium 7 600
25,000
44,000 bismuth
Cesium

Claims (1)

5 6 Material is done in a similar way to the manufacture of tools finish-ground. This tool has a Platinum "whiskers" in copper. very long service life when machining , The application of high hydrostatic pressure hard steel alloys in the lathe,
to a crystalline material according to the invention, z. B, to metallic crystalline material, e.g. B. 5 Example3
Ferrous metals, leads to significant and lasting Changes in properties of these materials. An intimate mixture of 20 percent by weight of a-aluminum, for example, the creep resistance and hardness of the iron's miniumoxide powder (grain size 0.048 to 0.053 mm) are permanently increased. and 80 percent by weight of pure iron powder (grain - the effect of the high hydrostatic pressure 0.125 to 0.149 mm) in a rubber could consist in an increase in the number of interference sheaths due to the action of a hydrostatic gene in the crystal lattice of the material. Disturbances of pressure of 1760 at preformed into a cylinder are flaws in the crystal lattice; they are in turn After removing the rubber sheath is individual in AH Cottrell, "Dislocations and the cylinder sintered for 4 hours at 1200 ⁰ C. A jacket made of silver solder 1953 is described around the cylinder "Plastic Flow in Crystals", Oxford, Clarendon Press, 15. According to the theory, cast according to Example 2. The encased form, the number and form of such disturbances, certain bodies is exposed to hydro-material properties such as hardness, creep strength and static pressure of 25,000 at for ^{24 hours at 400 ° C.} That and electrical conductivity, while certain other product is a solid metal-ceramic shaped body properties, such as the modulus of elasticity, do not have any 20 and is better than iron to experience greater influence. in cutting tools. Example 1 Example 4 According to a specific embodiment, a 25 Ni ₂ B powder and CaB ₆ powder are sintered separately powdered metal, such as powdered iron in compressed and then at 1000 ⁰ C. The two die pressed and deformed. Then the porous compacted molded bodies are enclosed in silver solder jackets with a jacket made of a bismuth-lead compound according to Example 2. The compression tin alloy having a melting point of 95 ⁰ C of the coated moldings is carried out at 500 ⁰ C and cast around. The product is then placed in the press 30 20 000 at. The two products have sufficient chamber of conventional hydrostatic pressure resistance so as not to crumble when handled, device. On the jacket is now and are suitable for use as deoxidation, an ultra-high hydrostatic pressure of more than medium for metals.
15 000 at exercised, making the coat both a continuous as well as a sudden 35 Example 5
Subject to compression or reduction in volume. The result is a high, permanent compaction of aluminum silicat fibers in lengths of approximately the porous iron mass, causing the granules to be cut by 6.3 mm and then by four times porous mass cold to a noticeable degree. Weight amount of barium carbonate powder with grain welds will. 40 large mixed under 0.15 mm. The mixture will The jacket is then compacted in a rubber jacket under a hydro- Iron melted. The obtained, compressed static pressure of 1760 at into a cylinder Product has a very high density and is preformed. The jacket is removed and the cylinder a product made of the same material ^{sintered at 100O 0} C for 6 hours. In order to "Non-porous way" is obtained, largely 45 terten molded body around is now according to Example 2 comparable or superior. poured a coat of silver solder, on which the whole According to the invention, for example, 24 hours of wear at 400 ^° C. can be a hydrostatic pressure pegs, turbine blades, machine bolts and exposed to 25,000 at. Receives as a product Components for electron tubes are produced. one ceramic material that works for everyone 50 uses where there is a high Example 2 Strength and oxidation resistance up to to about 1300 ⁰ C arrives. An intimate mixture of 80 percent by weight
Tungsten carbide powder and 20 percent by weight cobalt powder (grain size below 0.074 mm) is 55 claims:
brought into the desired shape by pre-pressing and then sintered ^{at 1000 ° C.} Around the compacted first method for compacting in particle-shaped bodies around a jacket of silver solder in the form of substances, characterized up to a minimum thickness of about 3.2 mm on all sides, is drawn that the particles are poured into one. The silver solder consists of a 50 weight- 60 jacket made of an inelastic material one percent silver, 15.5 weight percent copper, 16.5 closes, which has a high compressibility, weight percent zinc and 18 weight percent cad, and at a certain pressure a mium and melts at 627 ⁰ C. the jacketed sudden increase in density suffers, and subsequently molded body is set at ⁰ at 400 C under a hydro- ßend on the mantle hydrostatic pressure static pressure of 25 000th After the 65 exerts, which is at least as high as the one to open the press, the jacket is melted off. Sudden increase in density of the casing material The carbide body obtained in this way is subjected to the required pressure, whereupon the casing diamond grinding wheel is removed from the compacted mass to form a cutting mechanism. 2. The method according to claim 1, characterized in that a jacket made of a "material is used whose compressibility is higher than that of the compacted end product. 3. The method according to claim 1, characterized in that the present in particulate form Fabric before including in the coat transformed into a porous, coherent mass through a pre-deformation process, which already has the shape of the end product. IO 4. The method according to claim 3, characterized in that a jacket made of a material is used whose compressibility is higher than that of the pre-deformed mass. 5. The method according to claim 1, characterized in that a jacket made of cerium, cesium, Used bismuth or a low melting point bismuth alloy Considered publications:
German patent specification No. 958 261. 509 720/409 10.65 © Bundesdruckerei Berlin