Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/05—Metallic powder characterised by the size or surface area of the particles
  • B22F1/052—Metallic powder characterised by the size or surface area of the particles characterised by a mixture of particles of different sizes or by the particle size distribution
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/06—Metallic powder characterised by the shape of the particles
  • B22F1/065—Spherical particles
  • B22F1/0655—Hollow particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy

Definitions

• the invention relates to a metal powder mixture and particularly advantageous uses of such a metal powder mixture.
• metal powder mixtures of metal-metal alloy powders in order to be able to produce materials with a specific alloy composition.
• meta-alloying powders which contain a selection of alloying elements and at least one metal which corresponds to the metal powder used.
• heterogeneous metal powder mixtures which consist of at least two chemically and / or morphologically different components, which represent only an intermediate stage on the way to a formation of a desired metal alloy or of a requirement-oriented material to be produced during a heat treatment.
• Mixtures of metal powders are also used, which are formed as a result of a fines fraction naturally occurring during manufacture (e.g., 10% ⁇
• Such mixtures have the advantage that an improved filling density can be achieved due to the favorable space filling with adapted particle size distribution.
• the effects to be detected by caloric methods on the individual powders or of the powder mixture phase transformations, melting and solidification ranges
• effects to be used correspondingly via the chemical composition of the alloy e.g. chemically gra- ded between adjacent powder particles a central role in the alloying or metal formation and representation of the material.
• the desired metal alloy in the form of a fine powder (d 50 ⁇ 10 microns) for the powder metallurgy production of corresponding materials / components it is technically and economically difficult and has little commercial importance due to the problems encountered in the processing of such powders.
• the required heat treatment due to the high temperatures required, the required heat treatment (sintering) results in losses of elemental components due to their high vapor pressure, which results in a change in the desired alloy composition and causes technical problems in the thermal processing plants due to material deposition.
• metal powder blends are made from at least two or even three different powders.
• the individual powders should be formed from different metal alloys and have a narrow particle size distribution.
• the metal-powder blends described in this prior art must be prepared in a very complex manner in order in particular to be able to achieve the desired very small particle size, which is difficult with some metal alloys, eg ductile.
• Metal alloying powders which are provided as part of a desired metal powder mixture, can be produced inexpensively by atomization (gas or water atomization) of an alloy melt or by conventional means by melting and comminuting, if particle sizes d 50 ⁇ 45 ⁇ m are to be obtained.
• the production of coarser metal powder by Verdusung is also possible.
• the required for the production of the material during the heat treatment maximum temperature can be reduced.
• this object can be achieved with a metal powder mixture having the features of claim 1. Suitable uses of such a metal powder mixture are mentioned in claim 16. Advantageous embodiments and further developments of the invention can be achieved with features described in the subordinate claims.
• the metal powder mixture according to the invention is formed from at least two different powder fractions.
• a metal powder is used, which is formed of a metal alloy containing a first metal in which, in conjunction with the other alloying constituents of the first powder fraction contained in the metal alloy, the beginning of a phase transformation takes place at a temperature which is min - At least 200 K lower than the beginning of the melting of a material to be formed from the metal powder mixture by a heat treatment.
• the first powder fraction has a mean particle size of d 50 ⁇ 45 ⁇ m.
• the second powder fraction contained in the metal powder mixture according to the invention is preferably formed from a single second metal which is part of the metal alloy of the first powder fraction. However, it can also be formed from a mixture of at least two metals. This powder fraction has an average particle size d so ⁇ 10 microns. It should be understood for the second Puiverfr quasi under a single metal such that at least almost entirely consists of the single metal or the mixture and in which only very small alloying additions or impurities, up to a maximum of 3 wt .-% are allowed.
• a second powder fraction formed with a mixture of at least two metals one of the metals should be present in a significantly higher proportion than another metal contained therein. For a metal, the proportion should be at least 75% by weight. This metal will be referred to below as the second metal.
• the mean particle size of the first powder fraction should be at least three times greater than the mean particle size of the second powder fraction.
• the second powder fraction should be present at a level of at least 1% by weight.
• a binary metal alloy ie a metal alloy formed from two components, can be used.
• Cheaper is However, it is to use for the first Puiverfrsure a metal alloy formed of at least three different metals.
• At least one metal in the corresponding metal alloy should be present in the first powder fraction in a proportion which corresponds to twice the proportion as it should be contained in a material formed with the metal powder mixture subsequent to a heat treatment.
• the proportion of the second metal in the metal alloy of the material produced after the heat treatment should be at least 10% by weight.
• the metal alloy of the first powder fraction there may be used a metal whose phase transformation occurs at the lower temperature already mentioned, which is selected from among aluminum, magnesium, zinc, tin and copper.
• a metal whose phase transformation occurs at the lower temperature already mentioned which is selected from among aluminum, magnesium, zinc, tin and copper.
• These metals, in conjunction with other alloying constituents of the first powder fraction have the property of lowering the melting temperatures of the metal alloy or of achieving partial phase transformations, including molten states, in partial volumes.
• the metal used for the second powder fraction may be powdered iron, nickel, cobalt and copper. In this case, one of these metals may be contained in the second Puiverfr syndrome alone:
• the second powder fraction may also be formed with at least two of these metals, as a powder mixture.
• a metal compound mixture consists in using for the first powder fraction a metal alloy which has a general composition M1 M2CrR.
• the metal M1 is selected from aluminum, magnesium, tin, zinc and copper.
• the metal M2 is selected from iron, Nicke! and cobalt.
• R is selected from yttrium, molybdenum, tungsten, vanadium, manganese, a rare earth metafl, a lanthanide, rhenium, hafnium, tantalum, niobium, carbon, boron, phosphorus and silicon.
• Metail M1 can be used in a proportion of 1-70% by weight, metal M2 in a proportion of 1-60% by weight, Cr in a proportion of 0-80
• Wt .-% and R in a proportion of 0 - 70 wt .-% be contained. It is also advantageous to provide aluminum in the metal alloy for the first powder fraction with a proportion of at least 15% by weight.
• a powder which is formed with an alloy containing iron, chromium and aluminum, with a second powder fraction, which is formed from powdered iron, is used with a metal powder mixture according to the invention in a first powder fraction, for example, a material can be used a heat treatment are prepared, which in addition to predominantly iron, chromium in a proportion of 15 to 30 wt.% and an aluminum content of 5 to 20 wt .-%, are produced.
• a second powder fraction should have at least 10% by weight, preferably at least 30% by weight and more preferably at least 50% by weight of the total mass.
• the metal which, in combination with the other alloying constituents, should reach a phase transition temperature at least 200 K lower than the temperature at which the start of the melting of the material to be produced occurs (transition temperature), should be at least 10% by weight.
• the metal powder mixture according to the invention after a heat treatment, it is possible to produce materials in which all the metal components are distributed significantly more homogeneously in the material than is the case with conventionally used ones.
• the heat treatment can be carried out at temperatures which are at least 10 K below that required by the prior art.
• the inventive combination of the two selected powder fractions selected and also the use of a clear affects finer powder for a second powder fraction, with the in question smaller particle sizes, as this is the case for the first powder fraction, advantageous.
• Mass transport in consequence of diffusion, rearrangement and grain growth can be achieved.
• mass transport in addition to the homogeneous distribution of the individual metal alloy components in the material volume, it is also possible to achieve a reduced maximum temperature required for a heat treatment during the production of the material from the metal powder mixture.
• the heat treatment can be carried out using known sintering technologies. However, they should be suitable for the desired sintering atmospheres and temperatures.
• Metalipulvermischung be achieved an improvement in properties of a component made therefrom or a corresponding protective layer applied to a component. It can also be achieved an improved corrosion resistance.
• improved corrosion protection can be achieved by the targeted formation of a corresponding oxide layer on the surface, which usually reaches a layer thickness of 0.1-10 ⁇ m.
• a material produced with the metal powder mixture according to the invention may have an improved pitting potential in comparison to high-alloyed corrosion-resistant steels.
• a further fraction which is formed of a metal may be contained in the metal powder mixture, a further fraction which is formed of a metal.
• This may preferably be pure iron, in which contaminants and trace elements, if any, should be present at less than 3% by mass.
• the further fraction may also be pulverulent and significantly coarse-grained than the two powder fractions already described.
• the mean particle size can be larger than 150 ⁇ m and also considerably higher.
• the other faction can also be alone with
• Fibers be formed or contain fibers in addition to particles.
• the fibers may have diameters in the range of 1 mm and lengths of several millimeters.
• the proportion of second powder fraction may be kept very small and less than 5% by mass.
• Formation of layers on surfaces of devices may be accomplished by techniques known in the art, such as those disclosed in U.S. Pat. thermal spraying or build-up welding done.
• FIG. 1 part of a shell of a hollow sphere made of an FeCrAl alloy, with five points on which a chemical analysis of the elements Fe, Cr and At was carried out;
• FIG. 3 shows a diagram which illustrates the mass increase during the removal of FeC-rAI hollow spheres
• FIG. 4 shows a cross section with chemical point analyzes of an FeCrAl
• a first powder fraction having a mean particle size d50 of 25 microns and a composition of the alloy Nt-SOCr-25AI-0.125Hf and a second powder fraction with a mean particle size d50 of 5 ⁇ m predominantly pitch! (99.9 wt .-%) can be used.
• the proportion of the first Pulverfrakt ⁇ on is 40 wt .-% and the proportion of the second powder fraction is 60 wt .-%.
• 100 g of this Metaüpulvermischung are dispersed with 100 g of water, 3 g of polyvinyl alcohol and 0.5 g Dolapix with a disperser over a period of 1 h at a speed of 3000 rev / min to a homogeneous distribution of the particles in a suspension to reach.
• the suspension thus obtained does not sediment during intensive stirring.
• the resulting low-viscosity metal powder suspension is applied as a coating on spherical particles of polystyrene and dried. After reaching a layer thickness of 100 microns, the coating on the polystyrene particles, the heat treatment can be performed. In this case, working in an atmosphere with flowing hydrogen (30 i / min). First, the organic components are thermally decomposed, being heated at a heating rate of 1 k / min up to a temperature of 600 0 C. Thereafter, the temperature is increased to 1280 0 C while maintaining a heating rate of 5 K / min in the hydrogen atmosphere. After a holding time of 2 h at the maximum temperature, the mixture was cooled to room temperature at 5 K / min.
• the metallic hollow spheres produced in this way had an outer diameter of about 2 mm and a wall thickness of about 70 ⁇ m.
• the bulk density is included
• the shell material of the metallic hollow spheres which was produced with this Betspiel a metal powder mixture according to the invention, is formed in addition to nickel with 20 wt .-% chromium, 10 wt .-% aluminum and 0.05 wt .-% hafnium.
• an Ni-20Cr-10-Al-0.05Hf alloy is processed by inert gas atomization of a metal alloy into a fine alloy powder having a particle size d 50 of 10 ⁇ m. From this powder, in an analogous procedure, as in the example according to the invention, the steps of suspension production, coating, drying of polystyrene particles and heat treatment are carried out.
• the metallic hollow spheres produced in this way achieved significantly lower fracture strengths, measured on the basis of the deformation up to breakage, than those produced with the metal powder mixture according to the invention.
• the powder fraction was selected to be an Fe-49Cr-23Al alloy and the second powder fraction was formed from predominantly iron (99.5 mass%).
• Example 2 43.5% of the first and 56.5% and the second powder fraction were processed.
• FIGS. 1 and 2 with a section through the shell of a hollow sphere produced in this way, the homogeneity of the shell material is shown. recognizable.
• the shell material made with the metal powder mixture of this example was an Fe-23Cr-10Al alloy.
• the metallic fibers which were provided by milling of a block of pure iron ⁇ 99.9% iron), circulated in a 5 liter Eiche mixer at a speed of 20 rev / min.
• the mixing vessel was by blowing with heated air from the outside at a temperature of 50 0 C ⁇ 10 K.
• FIG. 4 shows a transverse section through a fiber produced in this way.
• the composition of the fiber material after the heat treatment could be determined to be a homogeneous Fe-19Cr-9Al alloy.
• a metal powder mixture having a first powder fraction, the 15. an average particle size d 50 of 4.4 microns and a second powder fraction having an average particle size d 5Q of 3.0 microns was used.
• the first powder fraction was a .
• the polymeric foam structure should be coated as completely as possible with the suspension.
• the coated pieces were then dried for a period of 2 hours at a temperature of 60 0 C.
• a heat treatment was performed in a hydrogen atmosphere. This was done with a heating rate of 1 K / min to a Tempe- temperature of 600 ° C heated to remove the organic components. Thereafter, while maintaining a heating rate of 5 K / min, heating was continued up to a temperature of 1280 ° C. and this temperature was maintained for a period of 2 h. When cooling down to room temperature, a rate of 5 K / min was also observed.
• an open-cell foam structure having a physical density of 0.8 g / cm 3 was obtained in which the ridges of the porous structure were formed after the heat treatment with a Fe23Cr1OAl alloy.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Nanotechnology (AREA)
• Powder Metallurgy (AREA)

Priority Applications (4)

Applications Claiming Priority (4)

Publications (2)

Family

ID=40282480

Family Applications (1)

Country Status (7)

Cited By (2)

Families Citing this family (3)

Citations (5)

• 2008
  • 2008-09-11 WO PCT/EP2008/062060 patent/WO2009053156A2/de active Application Filing
  • 2008-09-11 JP JP2010530372A patent/JP2011501783A/ja active Pending
  • 2008-09-11 AU AU2008315429A patent/AU2008315429A1/en not_active Abandoned
  • 2008-09-11 RU RU2010120780/02A patent/RU2010120780A/ru not_active Application Discontinuation
  • 2008-09-11 EP EP08804025A patent/EP2205381A2/de not_active Withdrawn
  • 2008-09-11 CA CA2695764A patent/CA2695764A1/en not_active Abandoned
  • 2008-09-11 KR KR1020107007037A patent/KR20100085019A/ko not_active Application Discontinuation

Patent Citations (5)

Also Published As

Similar Documents

Legal Events