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
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/02—Making metallic powder or suspensions thereof using physical processes
  • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
• • 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
• • 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
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/02—Making metallic powder or suspensions thereof using physical processes
  • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
  • B22F2009/041—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by mechanical alloying, e.g. blending, milling
• • 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
  • B22F2998/10—Processes characterised by the sequence of their steps

Definitions

• the invention relates to a process for the production of metal, alloy or composite powders with an average particle diameter D50 of at most 25 ⁇ m, in which case a starting powder is first formed into platelet-shaped particles and these are then crushed in the presence of grinding aids, and thus obtainable metal , Alloy or composite powder.
• melt-spinning In addition to particle generation by atomization, other single-stage melt-metallurgical processes are often used, such as so-called “melt-spinning"
• Extremely fine particles which have particle sizes below a micrometer, can also be generated by the combination of evaporation and condensation processes of metals and alloys, as well as by gas phase reactions (W. Schatt, K.-P. Wieters in “Powder Metallurgy - Processing and Materials ", EPMA European Powder Metallurgy Association, 1997, 39-41).
• these processes are technically very complex.
• a method of fine comminution of relatively brittle, pre-comminuted material which is particularly suitable in many cases, works according to the concept of the gas-counter jet mill, for which there are numerous commercial suppliers, for example the company Hosokawa-Alpine or the company Netzsch-Condux.
• This method is widespread and offers significant advantages compared to conventional mills with purely mechanical comminution, such as ball mills or agitator ball mills, especially for brittle materials in technical (low contamination, autogenous grinding) and economic aspects. Jet mills reach their technical and thus also economic limits when comminuting ductile starting powders, i.e. materials that are difficult to comminute, and small target grain sizes.
• Very fine particles can be obtained, for example, by combining grinding steps with hydrogenation and dehydrogenation reactions, including combining the reaction products to the desired phase composition of the powder (IR Harris, C. Noble, T. Bailey, Journal of the Less-Common Metals, 106 (1985), L1-L4).
• this process is limited to alloys that contain elements that can form stable hydrides. In this way it is possible to largely avoid mechanical influences on the comminution in the form of lattice defects or other defects. This is particularly important if the functional properties of the powder particles, e.g. the crystallites, significantly influence the properties of the powder product, e.g. with NdFeB permanent magnets.
• Another method of producing fine powders from ductile materials is mechanical alloying.
• agglomerates are obtained which are made up of crystallites of approx. 10 to 0.01 ⁇ m in size. Due to the strong mechanical stress, the metallic ductile material changes in such a way that fine individual particles may be formed. These then contain the composition typical of the alloy.
• a disadvantage of this procedure is that mainly considerable abrasion occurs due to abrasion. As a rule, however, uncontrolled abrasion is an obstacle to technical use.
• discrete fine particles are formed only after a very long grinding time. ".Ffti-ne and metal and alloy powders can therefore not be produced economically by simple mechanical alloying.
• the object of the present invention is therefore to provide a process for the production of fine, in particular ductile metal, alloy or composite powders, the process in particular for the production of alloys, i.e. of multi-component systems, and it allows essential properties such as particle size, particle size distribution, sintering activity, impurity content or particle morphology to be set or influenced in a targeted manner.
• the object is achieved according to the invention by a two-stage process, in which a starting powder is first shaped into platelet-shaped particles and these are then comminuted in the presence of grinding aids.
• the invention therefore provides a process for preparing metal, alloy microns .or composite powders having an average particle diameter D50 of at most 25 as determined by the particle measuring instrument Microtrac ® X100 in accordance with ASTM C 1070-01, from a starting powder with a larger average particle diameter, wherein a) the particles of the starting powder are processed into platelet-shaped particles in a deformation step, the ratio of particle diameter to particle thickness of between 10: 1 and 10000: 1, and b) the platelet-shaped particles are subjected to comminution grinding in the presence of a grinding aid.
• the Microtrac ® X100 particle measuring device is commercially available from Honeywell, USA.
• the particle diameter and the particle thickness are determined by means of light-optical microscopy.
• the platelet-shaped powder particles are first mixed with a viscous, transparent epoxy resin in a ratio of 2 parts by volume of resin and 1 part by volume of platelets.
• the air bubbles introduced during the mixing are then expelled by evacuating this mixture.
• the then bubble-free mixture is poured out on a flat surface and then rolled out with a roller. In this way, the platelet-shaped particles are preferably aligned in the flow field between the roller and the base.
• the preferred position is expressed by the fact that the surface normals of the platelets are aligned on average parallel to the surface normals of the flat base, that is to say the platelets are arranged in layers on average on the base.
• samples of suitable dimensions are worked out from the epoxy resin plate on the base. These samples are examined microscopically perpendicular and parallel to the base. Using a microscope with calibrated optics and taking sufficient particle orientation into account, at least 50 particles are measured and an average is formed from the measured values. This mean represents the particle diameter of the platelet-shaped particles. After a vertical cut through the base and the sample to be examined, the particle thicknesses are determined using the microscope with a calibrated lens, which was also used to determine the particle diameter.
• the process according to the invention can be used in particular to produce fine, ductile metal, alloy or composite powders.
• Ductile metal, alloy or composite powders are understood to mean those powders which, when subjected to mechanical stress until the yield point is reached, undergo plastic expansion or deformation before they become significant
• Material damage occurs. Such plastic material changes are material-dependent and range from 0.1 percent to several 100 percent, based on the initial length.
• the degree of ductility ie: the ability of materials to deform plastically, ie permanently, under the action of mechanical stress, can be determined or described using mechanical tensile and / or pressure tests.
• a so-called tensile test is made from the material to be evaluated. It can e.g. around a cylindrical
• Measuring sensors make it possible to follow the increase in length in the selected measuring length while applying a mechanical tensile stress.
• the tension is increased until the sample breaks, and the plastic part of the change in length is evaluated on the basis of the strain-tension record.
• Materials that achieve a plastic change in length of at least 0.1% in such an arrangement are referred to as ductile in the sense of this document.
• Fine ductile alloy powders which have a degree of ductility of at least 5% are preferably produced by the process according to the invention.
• the crushability of alloy or metal powders which cannot be further crushed per se is improved by the use of mechanical, mechanochemical and / or chemical grinding aids which are added in a targeted manner or are produced in the grinding process.
• An essential aspect of this approach is not to change the chemical “target composition” of the powder produced in this way or to influence it in such a way that the processing properties, such as sintering behavior or flowability, are improved.
• the method according to the invention is suitable for producing a wide variety of fine metal, alloy or composite powders with an average particle diameter D50 of at most 25 ⁇ m.
• metal, alloy or composite powders of a composition of the formula I hA-iB-jC-kD (I) can be obtained, where
• Elemenj e_V, Nb M Ta A Cr, _Mo, W, Mn, Re, Ti, Si, Ge, Be, Au a • Ag, Ru, Rh, Pd, Os, Ir, Pt, C represents one or more of the elements Mg, Al, Sn, Cu, Zn, and D represents one or more of the elements Zr, Hf, rare earth metal, and h, i, j and k indicate the proportions by weight, where
• -h, i, j and k each independently means 0 to 100% by weight, with the proviso that the sum of h, i, j and k is 100% by weight.
• h is preferably 50 to 80% by weight, particularly preferably 60 to 80% by weight.
• i is preferably 15 to 40% by weight, particularly preferably 18 to 40% by weight.
• j is preferably 0 to 15% by weight, particularly preferably 5 to 10% by weight.
• k is preferably 0 to 5% by weight, particularly preferably 0 to 2% by weight.
• the metal, alloy or composite powders produced according to the invention are distinguished by a small average particle diameter D50.
• the average particle diameter D50 is not more than 15 microns, as determined by ASTM C 1070-01 (measuring device: Microtrac ® X 100).
• powders which already have the composition of the desired metal, alloy or composite powder can be used as the starting powder.
• the composition of the metal, alloy or composite powder produced can also be influenced by the choice of grinding aid, provided that it remains in the product.
• Starting powder required can be obtained, for example, by atomizing metal melts and, if necessary, subsequent screening or sieving.
• the starting powder is first subjected to a deformation step.
• the deformation step can be carried out in known devices, for example in a rolling mill, a Hametag mill, a high-energy mill or an attritor or an agitator ball mill.
• process engineering parameters in particular through the effect of .
• Mechanical stresses that are sufficient to achieve plastic deformation of the material or the powder particles are deformed so that they ultimately have a platelet shape, the thickness of the platelets preferably being 1 to 20 ⁇ m. This can be caused, for example, by one-time loads in a roller or a
• the grinding media and the other grinding conditions are preferably selected so that the contamination by abrasion and / or reactions with oxygen or nitrogen is as low as possible and below that critical size for the application of the product or within the specification applicable to the material.
• the platelet-shaped particles are produced in a rapid solidification step, for example by so-called “melt spinning", directly from the melt by cooling onto or between one or more, preferably cooled, rolls, so that flakes are produced directly
• platelet-shaped "Pa-rük & r " obtained in the defofmation step are subjected to comminution grinding.
• the ratio of particle diameter to particle thickness changes, primary particles with a ratio of particle diameter to particle thickness of 1: 1 to 10: 1 being obtained as a rule
• the desired average particle diameter of at most 25 ⁇ m is set without particle agglomerates which are difficult to comminute again.
• the comminution grinding can be carried out, for example, in a mill, for example an eccentric mill, but also in material bed rollers, extrusion presses or similar devices which bring about material disruption due to different speeds of movement and stress in the platelet.
• the grinding is carried out in the presence of a grinding aid.
• Liquid grinding aids, waxes and / or brittle powders, for example, can be added as grinding aids.
• the grinding aids can act mechanically, chemically or mechanochemically.
• the grinding aid can be paraffin oil, paraffin wax, metal powder, alloy powder, metal sulfides, metal salts, salts of organic acids and / or hard material powder.
• Brittle powders or phases act as mechanical grinding aids and can be used, for example, in the form of alloy, element, hard material, carbide, suicide, oxide, boride, nitride or salt powder.
• pre-comminuted element and / or alloy powders are used which, together with the starting powder used, which is difficult to comminute, give the desired composition of the product powder.
• Brittle powders which are preferably used are those which consist of binary, ternary and / or higher compositions of the elements A, B-, C, and / or D which occur in the starting alloy used, where A, B, C and D have the meanings given above to have.
• Liquid and or easily deformable grinding aids for example waxes
• examples include hydrocarbons such as hexane, alcohols, amines or aqueous media. These are preferably compounds which are required for the subsequent steps of further processing and / or which can be easily removed after the grinding.
• grinding aids are used which enter into a targeted chemical reaction with the starting powder in order to achieve the grinding progress and / or to adjust a certain chemical composition of the product.
• This can be, for example, decomposable chemical compounds, of which only one or more constituents are required to set a desired composition, it being possible for at least one component or one constituent to be largely removed by a thermal process.
• reducible and / or decomposable compounds such as hydrides, oxides, sulfides, salts, sugars, which are at least partially removed from the millbase in a subsequent processing step and / or powder-metallurgical processing of the product powder, the remainder remaining in the powder composition chemically supplemented in the desired manner.
• the grinding aid is not added separately, but is generated in situ during the grinding.
• the grinding aid can be produced by adding a reaction gas which reacts with the starting powder to form a brittle phase under the grinding conditions. Hydrogen is preferably used as the reaction gas.
• the brittle phases formed in the treatment with the reaction gas can generally be reactivated by appropriate process steps after comminution or after processing of the fine metal, alloy or composite powder obtained remove.
• grinding aids which are not or only partially removed from the metal, alloy or composite powder produced according to the invention, these are preferably chosen such that the remaining constituents influence the property of the material in the desired manner, such as, for example, the improvement of the mechanical properties, reducing the susceptibility to corrosion, increasing the hardness and improving the abrasion behavior or the friction and sliding properties.
• the use of a hard material is mentioned here, the proportion of which is increased in a subsequent step to such an extent that the hard material can be further processed together with the alloy component to form a hard metal or a hard material-alloy composite material.
• the primary particles of the metal, alloy or composite powder produced according to the invention have "distant mean particle diameters ' ser bS ⁇ " , oiled according to ASTM C 1070-01 (Microtrac ® X 100) of at most 25 ⁇ m on.
• coarser secondary particles agglomerates
• the comminution grinding is therefore preferably followed by a deagglomeration step in which the agglomerates are broken up and the primary particles are released.
• the deagglomeration can take place, for example, by applying shear forces in the form of mechanical and / or thermal stresses and / or by removing previously in the process
• the deagglomeration method to be used in particular depends on the degree of agglomeration, the intended use and the susceptibility to oxidation of the fine powder, and the permissible impurities in the finished product.
• the deagglomeration can take place, for example, by mechanical methods, for example by
• Treatment in a gas counter jet mill sieving, screening or treatment in an attritor, a kneader or a rotor-stator-disperser. It is also possible to use a voltage field such as is generated in an ultrasound treatment, a thermal treatment, for example dissolving or converting a previously introduced separation layer between the primary particles by cryogenic or high-temperature treatments, or a chemical conversion of introduced or specifically generated phases.
• the deagglomeration is preferably carried out in the presence of one or more liquids, dispersants and / or binders.
• a slip, a paste, a Plasticine, or a suspension with a solids content between 1 and 95 wt .-% can be obtained.
• solids contents between 30 and 95% by weight, these can be processed directly by known powder technology processes, such as, for example, injection molding, film casting, coating, hot casting, in order then to be converted into a final product in suitable steps of drying, debinding and sintering.
• a gas counter-jet mill is preferably used, which is operated under inert gases, such as argon or nitrogen.
• the metal, alloy or composite powders produced in accordance with the invention are distinguished from conventional powders with the same average particle diameter and the same chemical composition by atomization.
• Dig-bfö.s-pi-elweise are made by a number of special properties.
• the invention therefore also metal, alloy and composite powder microns with a mean particle diameter D50 of at most 25 as determined by the particle measuring instrument Microtrac ® X 100 in accordance with ASTM C 1070-01, which are obtainable by the novel process.
• the metal, alloy and composite powders according to the invention show, for example, excellent sintering behavior.
• the same sintering densities can be achieved as with powders produced by atomization.
• higher sintered densities can be achieved based on powder compacts with a defined press density.
• the invention therefore also relates to metal, alloy or composite powders.
• the powder to be examined can be compacted with the addition of customary press-supporting agents, such as paraffin wax or other waxes or salts of organic acids, for example zinc stearate.
• Metal, alloy or composite powders which are produced by means of atomizing, and compared to which the powders according to the invention have improved sintering behavior, are to be understood as those powders which are produced by conventional atomizing and known to the person skilled in the art.
• the advantageous sintering behavior of the metal, alloy and composite powders according to the invention can also be recognized from the course of sintering or shrinkage curves, as are shown, for example, in FIG. 7.
• FIG. 7 shows, for a comparison powder (V) and a powder (PZD) according to the invention, the course of the shrinkage S or the shrinkage rate AS in relative units as a function of the temperature T N standardized to the respective sintering temperature T s .
• the comparison powder (V) is a product produced by spraying under inert conditions and having a composition corresponding to that described in Example 1
• the powder according to the invention is a powder produced according to Example 1, with the morphology shown in FIG. 6 and an oxygen content of 0.4% by weight.
• Powders produced in a press tool using a uniaxial pressure of 400-600 MPa powder compacts are then sintered individually in a dilatometer in accordance with DIN 51045-1 under protective gas conditions using argon as the process gas.
• the heating is carried out at a speed of approx. 1 K / min (corresponds to approx. 6 * 10 "4 * Ts / min, with T s : approx. 1600 K).
• the feeler stamp of the dilatometer does not exert any pressure on the sample makes a measurable contribution to the sintering shrinkage in the temperature range of interest for sintering (approx. 0.5 T s to approx. 0.95 T s ).
• the organic pressing aid is driven out up to a temperature of about 0.45 * T s .
• the actual heating is then carried out by further heating at the same heating rate
• ⁇ max or n Maximum value of the shrinkage rates, determined from the shrinkage curves V S (T N ) or PZD S (T N ) derived from the temperature.
• the temperature at which the shrinkage begins at which 10% of this final shrinkage has been reached, based on the same final shrinkage, and at which the shrinkage has reached its maximum in PZD powders.
• the initial temperature range up to the shrinkage maximum is wider for PZD powder.
• the temperature range from the beginning of the shrinkage to the maximum of the shrinkage is larger for PZD powder.
• the temperature range between the temperature at which a shrinkage of 10% was reached to the temperature at which a shrinkage of 90% was reached is larger for PZD powder.
• the temperature range from the onset of shrinkage to the temperature at which 90% of the final shrinkage is reached is larger for PZD powder.
• the metal, alloy and composite powders according to the invention are also notable for excellent pressing behavior due to a special particle morphology with a rough particle surface and for a comparatively broad particle size distribution due to high pressing density. This manifests itself in the fact that pellets made of atomized powder are otherwise the same Manufacturing conditions have a lower bending strength than the compacts from powders according to the invention of the same chemical composition and average particle size D50. A further improvement in the pressing behavior can be achieved if powder mixtures of 1 to 95% by weight of metal, alloy and composite powder according to the invention and 99 to 5% by weight atomized powder are used.
• the sintering behavior of powders produced according to the invention can also be specifically influenced by the choice of grinding aid.
• one or more alloys can be used as grinding aids which, due to their low melting point compared to the starting alloy, already form liquid phases during heating, which improve particle transfer, material diffusion and thus the sintering behavior and the shrinkage behavior and thus higher sintered densities allow the same " SinterSi ⁇ to be achieved at the same sintering temperature or at a lower Sirit temperature.
• X-ray analyzes of the metal, alloy and composite powders according to the invention show a broadening of X-ray reflections in comparison to X-ray reflections, as they are obtained for powders with the same average particle diameter and the same chemical composition, which were produced by atomization.
• the broadening is shown by broadening the half-widths.
• the half-widths of the X-ray reflexes are broadened by a factor> 1.05. This is due to the mechanical stress state of the particles, the presence of a higher dislocation density, i.e. of perturbations of the solid in the atomic range, and in the crystallite size in the particles.
• alloy and / or process-related phases occur in the diffractograms, which are important for the shrinkage properties.
• the method according to the invention allows the production of metal, alloy and composite powders in which the contents of oxygen, nitrogen, carbon, boron, silicon are set in a targeted manner. If oxygen or nitrogen is introduced, the high energy input can lead to the formation of oxide and / or nitride phases. Such phases can be desired for certain applications because they can lead to material reinforcement. This effect is known as the “particle dispersion strengthening” effect (PDS effect). However, the introduction of such phases is often associated with a deterioration in the processing properties (for example compressibility, sintering activity). Due to the generally inert Properties of the dispersoids in relation to the alloy component can therefore have a sinter-inhibiting effect.
• the phases mentioned are immediately finely distributed in the powder produced. Therefore, in the metal, alloy and composite powders according to the invention, the phases formed (e.g. oxides, nitrides, carbides,
• the processing properties of the metal, alloy and composite powders according to the invention for example the pressing and sintering behavior and the processability by means of metal powder injection molding (MIM), slip-based methods ß ⁇ - ⁇ - J ⁇ j »e" Ca-sjting, can often be admixed of metal, alloy and composite powders produced conventionally, in particular via atomization.
• MIM metal powder injection molding
• the invention therefore furthermore relates to mixtures comprising 1 to 95% by weight of a metal, alloy or composite powder according to the invention and 99 to 5% by weight of a conventionally produced metal, alloy or composite powder.
• the mixtures according to the invention preferably contain 10 to 70% by weight of a metal, alloy or composite powder according to the invention and 90 to 30% by weight of a conventionally produced metal, alloy or composite powder.
• the conventionally produced metal, alloy or composite powder is preferably a powder which has been produced by atomization.
• the conventionally produced metal, alloy or composite powder can have the same chemical composition as the PZD powder contained in the mixture. Compared to pure PZD powders, such mixtures are characterized in particular by a further improvement in the pressing behavior.
• PZD powder and conventionally produced powder can have different chemical compositions in the mixture.
• the composition can be changed in a targeted manner and, as a result, certain powder properties and consequently the material properties can be specifically adjusted.
• the following examples serve to explain the invention in more detail, the examples being intended to facilitate understanding of the principle according to the invention and not to be understood as restricting the Emsc thereof.
• Ni20Crl6Co2.5Til, 5Al was used as the starting powder.
• the alloy powder obtained was sieved between 53 and 25 ⁇ m. The density was approximately 8.2 g / cm 3 .
• the starting powder had largely spherical particles, as can be clearly seen in FIG. 1 (scanning electron microscope image (SEM image) at 300 ⁇ magnification).
• the starting powder was subjected to deformation grinding in a "Vcrt- & leü '- Hin ⁇ -:' ei" k-skuge-l gg ⁇ le- (from Netzsch Feinmahltechnik; type: PR IS), so that the originally spherical particles had a platelet shape assumptions.
• the following parameters were used:
• Fig. 2 is a SEM image at 300 times magnification of the platelets formed in the deformation step.
• a structural damage (cracking) of the material can also be clearly recognized.
• a comminution grinding was then carried out.
• a so-called eccentric vibratory mill (from Siebtecb-nik GmbH, ESM 324) was used with the following process engineering parameters:
• Grinding bowl volume 5 1 operated as a satellite (diameter 20 cm, length approx. 15 cm) ball filling: 80 VoL- (bulk volume of the balls) grinding bowl material: 100Cr6 (DIN 1.3505: approx. 1.5 wt.% Cr, approx. 1 wt % C, approx.0.3% Si, approx.0.4% Mn, ⁇ 0.3% Ni, ⁇ 0.3% Cu, balance Fe ) ball material: 100 Cr6 Kügel carefullymesser: '10 mm of powder: 150 g "" milling assistants: 2 g paraffin vibration amplitude: 12 mm milling atmosphere: argon (99.998%)
• FIG. 3 is a SEM image at 1000X magnification of the product obtained.
• the cauliflower-like structure of the agglomerate (secondary particles) can be seen, the primary particles having particle diameters of well below 25 ⁇ m.
• a sample of the primary particles or femoral particle agglomerates was subjected to a deagglomeration in a third process step by a 10 minute ultrasound treatment in isopropanol in an ultrasonic device TG 400 (Sonic Ultrasoundbau GmbH) at 50% of the maximum power in order to separate separated primary particles receive.
• TG 400 Sonic Ultrasoundbau GmbH
• the particle size distribution of the deagglomerated sample was determined using Microtrac ® XI 00 (manufacturer: Honeywell / US) in accordance with ASTM C 1070-01.
• the particle size distribution thus obtained is shown in FIG. 4.
• the D50 value of the starting powder was 40 ⁇ m and has been reduced to approximately 15 ⁇ m by the treatment according to the invention.
• the remaining amount of the primary particles from the comminution grinding were subjected to a deagglomeration in an alternative 3rd method step by treatment in a gas counter jet mill and subsequent ultrasound treatment in isopropanol in a TG 400 ultrasound device (Sonic Ultrasoundbau GmbH) at 50% of the maximum output. Again, there was a particle size determination by means of Microtrac ® XI 00. In Fig. 5, the obtained Particle size distribution shown. The D50 value was now only 8.4 ⁇ m. This demonstrates the possibility of further increasing the fine fraction in the powder produced according to the invention by means of a high-energy aftertreatment.
• FIG. 6 shows an SEM photograph (magnification 600 times) of the powder after treatment in the gas counter jet mill.
• the paraffin grinding aid introduced can be removed during the powder-metallurgical further processing of the alloy powder by thermal decomposition and / or evaporation, or can serve as a pressing aid.
• Example 2 Production of Fe24CrlOAHY fine powders using mechanical grinding aids without changing the composition of the starting powder
• a comminution grinding was then carried out in an eccentric vibratory mill, as described in Example 1.
• the composition of the grinding aid used is summarized in Table 1. The result is a mixture which contains 65% by weight of Fe, 24% by weight of Cr, 10% by weight of Al and 1% by weight of Y.
• the composition of the starting powder was not changed.
• the components used in the composite powder obtained starting powder, grinding aid
• Table 1 Composition of a mechanical grinding aid
• Example 3 Production of Fe24CrlOAllY fine powders using mechanical grinding aids with a change in composition compared to the starting powder
• Example 2 In contrast to Example 2, a change in the chemical composition during the grinding process was aimed for or permitted.
• An atomized alloy of the composition Fe25.6CrlO, 67Al with an average particle diameter D50 of 40 ⁇ m was subjected to a deformation step under the conditions described in Example 1. Platelet-shaped particles with an average particle diameter D50 of 70 ⁇ m were obtained, the appearance of which did not differ significantly from that from Example 1.
• a comminution grinding was then carried out.
• the procedure was as in Example 1, except that 10 g of a Fel6Y powder with an average particle diameter D50 of 40 ⁇ m were used as the grinding aid and the grinding time was 2 hours.
• Table 2 shows the composition and amount of the platelet-shaped starting alloy and of the grinding aid added for the grinding.
• the composite powder obtained had the composition Fe24CrlOAllY.
• the composite powder was subjected to an ultrasonic treatment, after which a composite powder with an average particle diameter D50 of 13 ⁇ m was obtained.
• Example 3 The procedure was as in Example 3, a mixture of several brittle substances and pure iron powder being used as the grinding aid.
• Table 3 contains the composition and weight of the starting powder and the grinding aid.
• the brittle painting aids Fe60Al, Fe70Cr and Y2.2H were brought to a mean particle diameter D50 of 40 ⁇ m in a separate grinding step before use.
• the Fe powder used had an average particle diameter D50 of 10 ⁇ m.
• the composite powder obtained had the composition Fe24CrlOAllY.
• the composite powder was subjected to an ultrasonic treatment, after which a composite powder with an average particle diameter D50 of 15 ⁇ m was obtained.
• Example 5 Production of an Fe24CrlOAllY fine powder from two FeCrAl master alloys and Fel ⁇ Y as the only brittle mechanical grinding aid
• the only brittle grinding aid used was the particularly brittle FelöY alloy, which previously had an average particle diameter D50 of approx. 40 ⁇ m was crushed.
• the procedure was as in Example 1, the milling time being 2.5 hours.
• Table 4 contains the composition and weight of the two plate-shaped FeCrAl starting alloys and the brittle grinding aid (Fel6Y).
• Table 4 Composition of the platelet-shaped starting alloys and the mechanical grinding aid used
• the composite powder obtained had the composition Fe24CrlOAUY.
• the composite powder was subjected to an ultrasonic treatment, after which a composite powder with an average particle diameter D50 of 12 ⁇ m was obtained.
• Example 6 In-situ preparation of the grinding agent
• the chemical composition of the resulting fine powder differed only slightly from that of the starting powder.
• the hydrogen content rose to ⁇ 1000 ppm.
• the hydrogen content fell back to below about 50 ppm.
• Example 7 Si powder as a mechanical grinding aid
• Grinding bowl volume 5 1 ball filling: 80 vol .-% grinding bowl material: 100 Cr6 ball material: 100 Cr6 ball diameter: 3.5 mm powder weight: 150 g Ni38Cr8.7All, 09Hf peripheral speed: 4.2 m / s grinding liquid: ethanol grinding time: 1, 5 h grinding aid: 13 g Si powder (D50: approx. 40 ⁇ m) After a milling time of 1.5 hours and subsequent Ultrasschalldeagglomeration an alloy powder having an average particle diameter D50 of 13 microns was measured by Microtrac ® X100 obtained.
• the silicon used here is desired or necessary in terms of alloying in order to set the final composition Ni35Cr8A18SilHf and has been selected in terms of process technology in order to achieve the desired grinding effect. Silicon is best suited to the elements in question as a grinding aid because of its brittleness. This grinding led to an increase in the oxygen content in the powder. At the end of the grinding, the oxygen content was 0.4% by weight.
• Hastelloy ® A spherically atomized Nil7Mol5Cr6Fe5WlCo alloy with an average particle diameter D50 of 40 ⁇ m, which is called Hastelloy ® .
• C is commercially available, was subjected to a deformation step as described in Example 1.
• the grinding of the platelet-shaped particles obtained was carried out in the presence of tungsten carbide as grinding aid under the following conditions in an eccentric vibratory mill:
• the grinding process resulted in an alloy-hard material composite powder in which the alloy component was ground to an average particle diameter D50 of approx. 5 ⁇ m and the hard material component to an average particle diameter D50 of approx. 1 ⁇ m.
• the hard material particles were largely homogeneously distributed in the volume of the alloy powder.
• the alloy-hard material composite powder was able to become one by means of customary process steps
• Spray powder can be processed.
• 797 g WC were added to 163 g of the alloy-hard material composite powder produced according to the invention for the dispersion and production of a suspension an average particle diameter according to ASTM B 330 (FSSS) of 1 ⁇ m, ethanol, PVA (polyvinyl alcohol) and suspension stabilizers were added.
• a suspension was formed which consisted of 25 vol% of the metallic binding phase and 75 vol% of the WC hard material phase.
• This suspension was further processed by spray granulation and classification into a green wettable powder with a particle size of 20-63 ⁇ m.
• the organic auxiliaries were first removed from this green wettable powder by degassing at 100 to 400 ° C. and then sintered at approximately 1300 ° C.
• Titanium powder with an average particle diameter D50 of 100 ⁇ m was processed into flakes in accordance with the invention in accordance with Example 1
• the titanium powder produced according to the invention can be processed further into shaped bodies by means of customary process steps.
• the titanium powder produced according to the invention was dissolved under organic solvent, e.g. stored n-hexane.
• organic solvent e.g. stored n-hexane.
• Long-chain hydrocarbons, such as paraffin, or amines were added before further processing by powder metallurgy.
• the paraffin was dissolved, for example, in n-hexane, added to the powder, and the n-hexane was then evaporated with constant circulation of the powder.
• Flake of an alloy 17-4 PH ® (Fel7Crl2Ni4Cu2.5Mo0.3Nb) which were prepared analogously to Example 1, were treated in a counter-jet mill.
• the platelets had a ratio of particle diameter to particle thickness of approx. 1000: 1 and an average particle diameter D50 of 150 ⁇ m.
• the counter jet mill was operated with inert gas. Atomized, spherical and not pretreated material of the same alloy with a particle diameter between 100 and 63 ⁇ m was used as grinding aid.
• the grinding chamber (volume: approx. 5 1) was filled with 2.5 1 powder bulk volume (67% by weight of grinding aid and 33% by weight of platelet) of powder and the grinding process was started. The fine fraction generated was separated off by appropriate settings of a classifier downstream of the mill at 10 ⁇ m.
• Nil7Mol5Cr6Fe5WlCo alloy with a particle diameter of 100 - 63 ⁇ m which is commercially available under the name Hastelloy ® C, was mechanically treated in a high-energy mill (eccentric vibratory mill) under the following conditions:
• Platelets were formed which had a diameter-thickness ratio of 1: 2 and a platelet thickness of approx. 20 ⁇ m. This was followed by comminution grinding in a Gas Gegeri-Krahl mill. During the comminution, particles with a particle diameter ⁇ 20 ⁇ m were removed by suitable adjustment of a downstream sifter. In this way, a fine alloy powder was produced which, after an ultrasound treatment, had an average particle diameter D50 of 12 ⁇ m and a D90 value of 20 ⁇ m, determined using Microtrac ® X 100.

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