Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D23/00—Casting processes not provided for in groups B22D1/00 - B22D21/00
  • B22D23/003—Moulding by spraying metal on a surface
• • 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
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/115—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces by spraying molten metal, i.e. spray sintering, spray casting
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/10—Alloys containing non-metals
  • C22C1/1036—Alloys containing non-metals starting from a melt
  • C22C1/1042—Alloys containing non-metals starting from a melt by atomising
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
  • C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
  • C23C4/123—Spraying molten metal

Definitions

• the invention relates to a method for producing a hot working tool according to the preamble of patent claim 1.
• non-porous or almost non-porous preforms by atomizing a molten metal and immediately collecting the drops in a mold is already known.
• a method is described in DE-OS 2537103.
• the relative density of these preforms should be at least 90%, usually 95-99%. This means that the pores that are still present are no longer connected to one another. This is important because the parts are to be further processed in the hot state by forging, pressing or extrusion and the penetration of oxygen into the pores would lead to an undesirable internal oxidation with the consequence of a deterioration in the mechanical properties.
• the object of the invention is to provide a simplified method which allows the production of a hot working tool with a relative density of 70-90% from an atomized metal melt, and an apparatus for carrying out this method.
• large porous hot work tools can be produced directly by atomizing a molten metal and collecting the melt particles in a mold.
• the process parameters i.e. in particular the overheating of the melt, the melt flow per unit time (which is determined by the diameter of the melt jet), the amount, temperature and speed of the atomizing gas and the distance of the mold from the atomizing nozzle so that the melt particles when they hit the under the Atomizing nozzle located or on the melt particles already accumulated in the mold have already cooled so far that they have a doughy consistency.
• “dough” is understood to mean a state in which the particles are still deformable under slight pressure, i.e.
• the particles are already completely solidified or can still have a liquid core, which, however, must be so small that the enveloping body surrounding it no longer bursts when it hits the mold. This is necessary so that the tool produced has a relative density of 70-90%, preferably 80-85%.
• the melt particles should still have enough thermal energy to weld (sinter).
• the setting of the particle consistency differs fundamentally from that for the production of metal powder, in which a solid particle character is required and the particles should have as little thermal energy as possible in order to prevent caking.
• a process parameter combination is thus set during the atomization of the melt, which was to be avoided in any case according to the prior art.
• a suitable parameter combination can e.g. determine by experimenting that the distance between the mold and the atomizing nozzle is varied under otherwise constant conditions. It should be noted that a tendency towards a higher overheating of the melt, an increase in the melt flow rate per unit of time, an increase in the gas temperature and a decrease in the amount of atomizing gas supplied per unit of time under otherwise constant conditions will lead to a softer particle consistency a higher specific gravity.
• desired material properties e.g. heat resistance
• the method according to the invention also enables the production of tools with specifically different properties within the Molding volume. This is possible, for example, by supplying hard materials (eg carbides, nitrides, oxides, etc.) to the atomizing nozzle in a time-controlled manner during the atomization process and introducing them into the shaped body with the flow of the melt particles.
• hard materials eg carbides, nitrides, oxides, etc.
• the metal melt is atomized and / or during a reaction annealing treatment (ie in the shaped body itself).
• one or more metals e.g. Al, Ti, Nb
• the gas used in the atomization and / or reaction annealing e.g. nitrogen, carbon dioxide, oxygen in the air, etc.
• the shaped body should have a relative density of approximately 80-85% for the annealing treatment.
• the atomization of the molten metal and the collection in the mold are advantageously carried out in a container sealed from the outside atmosphere.
• the setting of different material properties within the tool can also be achieved by changing the distance of the collecting form from the atomizing nozzle over time, so that layers of different density, ie also different porosity, are formed in the shaped body. This has e.g. also influence any subsequent reaction annealing treatment.
• a high density is usually desired where fastening elements are to be attached to the tool.
• a uniform or even specifically non-uniform filling of the mold can be achieved by moving the mold under the nozzle in approximately horizontal directions.
• a tool with very different material properties can be produced within the molded body volume, possibly also in conjunction with a time-metered addition of hard material.
• the tools produced by the method according to the invention can generally be used directly as finished parts or only have to be subjected to a comparatively simple mechanical processing (e.g. seating surfaces, drilling). In some cases, however, it is important to largely eliminate the open pore structure of the molded body.
• a device for carrying out the method according to the invention has a melt container, in the bottom of which a pouring opening is provided, below which a preferably annular atomizing nozzle is arranged coaxially to the pouring opening.
• This nozzle has a connection for the atomizing gas.
• a different cross-sectional shape of the nozzle e.g. rectangular
• the shape for collecting the melt particles is interchangeably arranged below the nozzle on a holding device that is adjustable in height (e.g. by means of a motor drive) in order to be able to vary the distance to the nozzle. It is particularly advantageous to make the receiving device pivotable or movable under the nozzle in order to be able to change the impact zone of the spray jet within the shape as desired (e.g. by means of a motor drive).
• the nozzle and the receiving device with the mold in an atomization container which is closely connected to the melt container and is sealed off from the external atmosphere and has an outlet for the discharge of the atomization gas. Since the melting of the melt particles resulting from the atomization takes place primarily through heat radiation and less through heat emission to the atomization gas until solidification, it can also be advantageous to provide the atomization container with additional cooling in or on its wall in order to influence the solidification conditions .
• a molded body is to be produced which, as a hot working tool, is subject to heavy wear.
• the part has the dimensions 420 mmx120 mmx40 mm.
• a steel mold with the corresponding internal dimensions is in a closed container under the exclusion of air movably mounted under an atomizing nozzle.
• the distance between the mold and the annular nozzle (diameter 80 mm) is 600 mm.
• the density of the shaped body is about 6.3 g / cm, which corresponds to a relative density of about 80% for the CrNi steel used.
• a fine-grained oxide (A1 2 0 3 ) is continuously supplied as hard material in the suction area of the nozzle in an amount that corresponds to approximately a 5% share of the steel melt.
• the melt flows through the nozzle at about 0.5 kg / sec. Nitrogen at room temperature is used as the atomizing gas.
• the mold is moved under the jet of the melt particles in such a way that the mold is evenly filled.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Manufacturing & Machinery (AREA)
• Powder Metallurgy (AREA)
• Manufacture Of Metal Powder And Suspensions Thereof (AREA)

Applications Claiming Priority (2)

Publications (3)

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ID=6230492

Family Applications (1)

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• 1984
  • 1984-03-12 DE DE19843409366 patent/DE3409366A1/de not_active Withdrawn
• 1985
  • 1985-02-27 DE DE8585730029T patent/DE3578391D1/de not_active Expired - Fee Related
  • 1985-02-27 EP EP85730029A patent/EP0156760B1/de not_active Expired - Lifetime
  • 1985-03-11 JP JP60048097A patent/JPS60211001A/ja active Granted

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