Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/10—Cores; Manufacture or installation of cores
• • 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
  • C23C24/00—Coating starting from inorganic powder
  • C23C24/02—Coating starting from inorganic powder by application of pressure only
  • C23C24/04—Impact or kinetic deposition of particles
• • 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
  • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
  • C23C4/06—Metallic material
  • C23C4/08—Metallic material containing only metal elements

Definitions

• the invention relates to a method for producing a workpiece having at least one cavity, recess, recess, a cavity, an undercut or any other unfilled portion, and a suitable carrier material.
• Unfilled portions such as cavities, recesses, recesses, undercuts, cavities, etc.
• unfilled portions such as cavities, recesses, recesses, undercuts, cavities, etc. are hereinafter referred to as "free space" for the sake of simplicity, which term also includes spaces that are not surrounded on all sides by a wall, such as undercuts.
• the erasable material used as a "placeholder” is also referred to as a "lost core” or “lost shape”.
• a material that can be used for lost cores has to meet a variety of requirements, including mechanical and thermal stresses. These requirements are not met by the desirable for lost cores water-soluble salts.
• salts are an interesting material in terms of their solubility and availability, their use is not possible because of their brittleness in processes that require mechanical stress, such as thermal spraying, cold gas spraying, or compacting. The salts, because of their brittleness, can not withstand the mechanical stress associated with such processes.
• US 3,722,574 A describes the fabrication of superalloy hollow parts by a model fusing process, and more particularly the manufacture of metal parts from cobalt or nickel superalloys, which are provided with small and narrow openings and passages.
• the model casting process envisages the use of a water-soluble core in the manufacture of these hollow articles, the core being in the casting after casting and voids forming after removal of the core.
• US 3,701,379 A describes a metal workpiece having internal portions and openings, wherein the metal workpiece can be obtained by casting molten metal into a mold having a magnesium oxide core.
• the core can be obtained by molding a mixture of magnesium oxide and resin.
• the resin can then be slowly volatilized to form the core of pure MgO, which can then be sintered. After casting the metal into the mold and around the core, the core can be dissolved by washing with a non-corrosive medium.
• this alloy should then be dissolved out with water or an acidic or basic solution. It has been found that this known material is not suitable for all molding processes.
• the material should also be removable when dealing with very complex or very delicate shapes, e.g. narrow channels.
• a carrier material that can be used as a placeholder in the construction of workpieces with at least one free space that consists of a corrodible material, wherein the corrodible material is a mixture or alloy of magnesium and at least one other metal component whose normal potential under reaction conditions is greater than that of magnesium, wherein the material has been compacted with a mechanical loading process.
• a corrodible material which contains magnesium and another metal component having a higher normal potential under reaction conditions loses its structure very rapidly on contact with water or an aqueous medium, with the magnesium dissolving and other metals present, if appropriate, at least partially remain in particle form.
• the material according to the invention has a structure which combines a combination of interesting properties.
• the material provides sufficient strength to serve as a placeholder in a variety of processes, and can withstand mechanical and thermal stress, e.g. as part of the shaping and / or processing.
• the material decomposes very rapidly on contact with a corrosive liquid.
• corrosion means any electrochemical reaction of magnesium with a liquid medium in the presence of another metal component with a higher normal potential, which leads to a substantial or complete dissolution of the magnesium with formation of gas.
• a corrosive medium is an ion-containing liquid which dissolves magnesium due to an electrochemical reaction in the presence of another metal component with a higher normal potential.
• higher normal potential always refers to the normal potential of a metal component in the Comparison to magnesium under the reaction conditions (in terms of temperature, pressure, type and amount of ions in the solution, etc.) and not to the position in the voltage series.
• metal component refers in particular to metals or metal alloys which promote the corrosion reaction of magnesium.
• the advantageous properties of the material according to the invention arise on the one hand by the metallic and mechanical properties of magnesium and other metal components and on the other hand by the corrosion ability of magnesium under certain conditions.
• the support material is brought into contact after completion of the workpiece to remove the placeholder with a corrosive medium, wherein dissolves magnesium and the undissolved carrier material is then rinsed out of the mold formed together with the magnesium-containing medium.
• compaction of the metal powder creates a material whose particles are in sufficient contact to favor an electrochemical reaction.
• the layer covering the particles may possibly be broken up to such an extent by stress or deformation that the reaction can take place and is not inhibited.
• a corrosive medium usually water or an aqueous medium
• the dissolution is achieved at the desired rate.
• the speed of the dissolution reaction can be adjusted in a targeted manner with the support material according to the invention.
• powder mixtures are used with high porosity, which are soaked in the addition of water, an uncontrollable reaction can be the result.
• a material is used whose porosity is not higher than 20% by volume, preferably not is higher than 5% by volume. In a particularly suitable embodiment, the porosity is less than 1%.
• a material according to the invention i. a magnesium-containing mixture or alloy which has been previously compacted, contacted with a corrosive medium, preferably a conductive aqueous medium in contact
• the magnesium dissolves at least as far as possible.
• this effect is exploited to remove a carrier material after completion of a workpiece by bringing the mixture into contact with a corrosive medium and subsequently rinsing out carrier material and medium containing the magnesium, which are then removed from the formed form.
• the carrier material according to the invention is particularly well suited for the production of workpieces with cavities, recesses, recesses, undercuts and cavities, in particular for the production of hollow bodies or workpieces with undercuts using thermal spraying methods.
• the rate of dissolution of magnesium depends on various factors, so that it is possible with routine measures to find and use the optimal material or conditions. Factors influencing the resolution include the temperature, the combination of metals, the type and amount of ions contained in the medium used for dissolution, Area ratios and mechanical stress on the surfaces as well as the hydrogen overvoltage.
• Temperature is an important parameter as the higher the temperature, the faster the reaction.
• the electrochemical reaction of the metals with water is exothermic.
• the rate of dissolution can therefore be adjusted, if necessary or desired, by controlling the temperature of the reaction.
• the reaction can be adjusted by supplying heat and / or possibly by dissipating heat. Supply and removal of heat in the simplest case by using appropriately tempered medium as a solvent.
• the combination of the metals used in the carrier material is a magnesium alloy or a mixture of magnesium with at least one further metal component is used. Depending on the added metals, the magnesium corrosive reaction is stronger or less strong. By selecting one or more metals, therefore, the speed of resolution can be influenced.
• magnesium alone tends to corrode under certain conditions, inter alia when exposed to ion-containing solution.
• the corrosivity can still be increased if at least one other metal component, which is nobler with respect to magnesium, ie, has a higher standard potential or normal potential than magnesium, is alloyed or admixed. Any metal which has a higher normal potential than magnesium under the conditions of the corrosion reaction taking place by adding the corrosive medium is therefore suitable for the carrier material according to the invention.
• a particularly high influence on the corrosivity metals have low hydrogen overvoltage and in particular the metals iron, nickel and copper, which are therefore present mixed or alloyed, preferably singly or in combination with the magnesium, in the support material according to the invention. Most preferably, a combination of magnesium and iron is used.
• the carrier material according to the invention is produced from magnesium and at least one further metal component by compaction. It has been found that when the material and thus the individual particles are heavily stressed before or during the formation, the corrosion proceeds very quickly. This may, without being bound by theory, be due to the fact that the stress possibly existing magnesium protective oxide or oxide layers are disturbed or destroyed, so that the corrosive attack can then be faster and more violent.
• Another factor that can accelerate the corrosion reaction is the proportion of ions and the activity of the ions contained in the corrosive, preferably aqueous medium used for dissolution. It was found that the corrosion and thus dissolution of the Magnesium, the faster the more active anions are available. Particularly reactive in this context are, inter alia, chloride, nitrate and sulfate ions. These ions lead to the formation of slightly soluble magnesium salts, which accelerate the dissolution.
• aqueous solution Further influence on the corrosion reaction has the conductivity of the aqueous solution, which in turn can be influenced by the proportion of ions.
• An aqueous medium with high conductivity or a high proportion of ions leads to rapid dissolution. Therefore, strongly ion-containing aqueous media are preferably used for dissolution.
• strongly ion-containing aqueous media are preferably used for dissolution.
• a saline-containing solution is used.
• seawater is a very suitable medium.
• ion-containing wastewater from other processes is very advantageous, which can be utilized very well in this way.
• Another factor which has an influence on the corrosion reaction is the area ratio of anodic particles to cathodic particles and the distance between anodic and cathodic particles.
• the small distance between the anode and the cathode can be produced by the compacting processing, which produces the structure of the carrier material according to the invention.
• the proportion of individual components also influences this factor.
• the hydrogen overvoltage also influences the corrosion. It has been found that in combination with magnesium metals with low hydrogen overvoltage are effective cathodes and therefore favor the reaction. Low hydrogen overvoltage metals include nickel, copper and iron, which are therefore preferred.
• Another factor affecting the rate of dissolution and the course of the reaction is the movement of the medium.
• the medium is agitated after the start of the reaction, the formation of a closed covering layer of magnesium hydroxide over the magnesium particles is hindered, so that the corrosion is in turn further promoted.
• the speed can be adapted to the method, wherein one of the above factors or more can be set.
• the carrier material according to the invention is applicable to shaping methods of any kind.
• the material according to the invention is distinguished, in particular, by its formability, machinability, contour-consistent layer formation, imaging properties and compatibility with other materials. It can be advantageously used especially when forms are formed by layer structure, which are then mechanically reworked to form simple and complex, even filigree body, which serve as a placeholder for any type of space, incl. Undercuts in materials of any kind. Complex or filigree shapes can be formed by machining, usually machining, from the material. The layers formed from the support material according to the invention follow the substrate to which they are applied, contour true and remain there adhere. The material according to the invention can therefore be used in many ways.
• the body is built up in layers and applied in the areas that are to form the space or the undercut later, the material of the invention, which can be flushed out after completion of the workpiece.
• the mixture or alloy forming the carrier material is processed in such a way that a compacted material, which may also be present in sintered form, results from the metal powders or the alloy. It is important that the metal particles of the at least two metals are in intimate contact with each other.
• Alloys are materials which are composed of at least two components and contain at least one metal, wherein the second alloy constituent in the metal is either dissolved and homogeneously distributed therein, or is only partially dissolved, so that a second alloy-rich phase is formed.
• the second or further alloying ingredient is also metallic, it is intermetallic compounds, i. Atoms of one metal are incorporated into the matrix of the other metal.
• the macroscopic properties of the alloy differ from those of the individual metal powders. According to the invention, it is essential that a compacted material is used, as this provides the reactivity and close contact necessary for the corrosion reaction.
• the support material according to the invention contains magnesium powder and at least one further powder of noble metal or metal compound compared with magnesium; Preferably, it consists essentially only of magnesium and metal or metal powder. Due to the potential difference of these two components, when a corrosive medium, in particular water or an aqueous medium, is added, a Redox reaction, which causes the magnesium to dissolve as a base metal.
• This component can be included in addition to the metals another component that contributes further desired properties.
• This component can be selected from a wide variety of materials, with the proviso that it does not disturb the structure of the structure or the electrochemical decomposition of the same.
• another material inert with respect to the electrochemical reaction may be added which has an influence on the mechanical properties, e.g.
• a harder material may be added as a third component to improve adhesion in kinetic compaction.
• a material catalyzing the electrochemical reaction in order to influence the start and / or course of the reaction. It may be the phlegmatizing substances that are phlegmatic in storage, e.g.
• the metal powders which make up the material according to the invention are variable in terms of grain size and grain shape.
• the shape of the particles is not critical, both spherical and flake-like or other forms come into consideration.
• the particle size is not critical, with the proviso that the particles may not be larger than the space to be filled. In thermal spraying, particles with a Size can be processed up to about 0.5 mm. Preference is given to using particles of up to 0.25 mm.
• the dissolution behavior can also be influenced by the particle size of the powders, so that the optimal material can be selected with routine tests for each application.
• compaction behavior and structure can be influenced by selecting the particle sizes of the two powders and their ratio. The particle size can therefore be selected specifically for a powder or both so that the desired properties arise in terms of structure and resolution.
• the corrosive medium can be any liquid that aids in the corrosion reaction. It is usually ion-containing water or an aqueous solution that initiates or promotes the redox reaction by which the magnesium is oxidized to form hydroxide ions and simultaneously hydrogen. As a result, part of the carrier material dissolves, the structure is destroyed and the undissolved particles are released. These particles are then rinsed out together with the solution containing the magnesium dissolved. The evolution of gas creates enough movement to keep the reaction going, even in the case of narrow channels or filigree cavities.
• the pH may shift to the acidic or basic range, depending on the material and medium used. Therefore, if a material susceptible to corrosion at acidic or basic pH values is used to produce the workpiece, it can be protected by appropriately selecting carrier material and / or corrosive medium so as to avoid the corrosion of the workpiece material becomes.
• a material susceptible to corrosion at acidic or basic pH values is used to produce the workpiece, it can be protected by appropriately selecting carrier material and / or corrosive medium so as to avoid the corrosion of the workpiece material becomes.
• the formation of a basic solution is advantageous if the material forming the shaped body is steel, since the basic solution acts here as a kind of rust protection.
• a slightly acidic pH which can be achieved by the medium used, may be more advantageous.
• a carrier material which does not dissolve completely, but whose structure is destroyed upon contact with water, since only a part is dissolved, which is sufficient, however, to flush out the entire material.
• at least magnesium and another metal component are necessary, which are preferably used in the purest possible form.
• pure is understood to mean that the powders contain at most small amounts of contaminants of interfering elements.
• Such a structure is preferably formed by thermal spraying, cold gas spraying and / or kinetic spraying.
• a structure is achieved in which the particles form a compacted matrix.
• the material applied by such a method has a porosity of less than 20%, more preferably less than 5% and even more preferably less than 1%. If the porosity of the material and thereby the proportion of open pores becomes too high, the support material could become soaked with the aqueous medium and, depending on reaction conditions and reactants, dissolve so rapidly that an uncontrollable reaction with high gas pressure would result, which is undesirable. In addition, due to an increase in volume due to hydroxide formation, the removal of the undissolved particles may be disturbed.
• the matrix formed from the metals is so dense that the surfaces of the particles have sufficient contact to promote the electrochemical reaction upon addition of water.
• the metal powders are used in proportions such that the electrochemical reaction proceeds to the desired extent.
• the magnesium dissolves at least partially, while the remaining component or components remain as a powder. Therefore, the magnesium must be present in such a proportion that by dissolving it dissolves or destroys the structure previously formed by compaction to such an extent that the resulting material, i. essentially metal particles, can be flushed out.
• the volume ratio of magnesium to the other components is between 250: 1 and 1:10.
• the metal powders are preferably combined in a volume ratio of magnesium to more noble metal of 5: 1 to 1:10, preferably 3: 1 to 1: 3.
• magnesium powder and "nobler" component are combined in approximately equal volumes.
• any magnesium corrosive liquid can be used.
• the corrosive, preferably aqueous medium is not critical and any medium that consists predominantly of water is suitable here. It is important to make sure that the electrochemical reaction is negative affecting ingredients are contained in the water. Preference is given to using an aqueous medium which promotes the electrochemical reaction, in particular an ion-containing solution. Acid, neutral and basic ion-containing solutions, eg salt solutions, are suitable. It is also possible to use dilute acids or bases. Also suitable as wastewater, containing ionic media. These are advantageous for environmental and cost reasons. Therefore, both tap water and waste water from other processes, which is preferably saline, can be used as long as it does not affect the redox reaction.
• the invention relates to a method for producing a workpiece with at least one free space, i. inter alia, an undercut, a cavity, a recess or recess, wherein the space forming the free space is filled with a carrier material which is rinsed out after completion, wherein the carrier material is a material as defined in claim 1.
• the carrier material according to the invention is very well suited to form a lost core for a molding process in which workpieces with cavities or undercuts are formed.
• the carrier material according to the invention is characterized by its mechanical strength, so that it can be used wherever a mechanically strong material is necessary.
• it can be processed by molding processes, in particular it can be formed by machining processes into complex shapes.
• the carrier material according to the invention for processing with thermal spraying, kinetic compaction or cold gas spraying is particularly suitable.
• the material according to the invention is particularly preferably used for a process for the production of workpieces, in which a layered structure is achieved by thermal spraying, wherein the layers are then optionally post-processed by machining.
• a method for producing a workpiece in which a structure is built up by thermal spraying, kinetic compaction or cold gas spraying, wherein the regions which are to form a free space in the finished body are formed with the carrier material according to the invention, wherein the carrier material according to Completion of the workpiece is removed by contact with a corrosive medium.
• the carrier material according to the invention can also be used for other processes in which a placeholder is required, but is particularly advantageous for processes in which thermal spraying is used.
• the thermal spraying preferably takes place by kinetic spraying.
• the carrier material according to the invention is very well suited for forming lost cores. It can be processed into a variety of forms. Upon completion of the workpiece, contact with a corrosive medium destroys the matrix formed upon application of the material by an electrochemical reaction, and the movement due to gas formation during the electrochemical reaction produces enough water exchange to appropriately promote the electrochemical reaction. The metal powder remaining on destruction of the matrix can then be easily rinsed out together with the resulting solution and, if necessary, reused.
• the electrochemical reaction and thus the dissolution of the magnesium and the destruction of the structure can be promoted in a preferred embodiment by providing a movement of the medium during and after the addition of the aqueous medium. This can e.g. by rinsing, by moving the workpiece or by ultrasonic treatment.
• a carrier material which, due to its mechanical strength as well as ductility and its electrochemical reactivity, provides an ideal combination of properties. Furthermore, a method is provided, with which also very complicated shapes can be produced, since it is possible to build the workpieces in layers by spraying and then even complicated recesses, cavities, recesses, cavities, undercuts or other unfilled portions by flushing the To form carrier material.
• the material according to the invention described above is very well suited for any form of placeholder. Due to the advantageous mechanical and electrochemical properties, the support material according to the invention can always be used when it is necessary to keep a place for a certain period of time and then to remove the placeholder material.
• the carrier material according to the invention is suitable when the placeholder is mechanically stressed in its function, for example, is exposed to stress. Therefore, except for the above-mentioned use for the production of workpieces with cavities and cavities, the support material according to the invention can also be used as a spacer, spacer, spacer and lost core in any form.
• a combination of magnesium and at least one of the metals iron, nickel or copper is used. Especially these combinations have an optimal combination of mechanical load capacity and corrosivity.
• the combination of magnesium and iron is particularly preferred because upon dissolution of the support material, an aqueous suspension is formed which contains only magnesium or its decomposition products formed by corrosion, and iron as metals. This combination is environmentally friendly and can be easily disposed of either as wastewater, without polluting the environment or being recycled. If other metals are used in addition to iron or instead of iron, it may be necessary to treat the resulting solution before disposal.
• the mechanical properties and the environmental friendliness of the product formed after dissolution contribute to the carrier material according to the invention being particularly advantageous.
• the support material according to the invention which consists of magnesium and at least one other metal component which is selected from iron, nickel and copper, is compacted by a mechanically stressing process.
• the same procedures as outlined above and the same ratios of the components as set out above are also generally suitable for use of the support material as placeholders.
• the dissolution of the placeholder is carried out in the same manner as stated above, namely with an aqueous solution containing ions, in particular an aqueous medium containing active anions.
• aqueous media with chloride, nitrate and / or sulfate ions for example, seawater is a very suitable medium due to its good availability.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Plasma & Fusion (AREA)
• Physics & Mathematics (AREA)
• Powder Metallurgy (AREA)
• ing And Chemical Polishing (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)
• Coating By Spraying Or Casting (AREA)
• Other Surface Treatments For Metallic Materials (AREA)
• Mold Materials And Core Materials (AREA)

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• 2007
  • 2007-04-16 DE DE102007017762.5A patent/DE102007017762B4/de active Active
• 2008
  • 2008-04-16 US US12/596,134 patent/US20110091660A1/en not_active Abandoned
  • 2008-04-16 JP JP2010503405A patent/JP5143891B2/ja active Active
  • 2008-04-16 ES ES08735289.4T patent/ES2687269T3/es active Active
  • 2008-04-16 WO PCT/EP2008/003049 patent/WO2008125351A1/de active Application Filing
  • 2008-04-16 EP EP08735289.4A patent/EP2136942B1/de active Active

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