DE102007058225A1 - Producing heterogeneous grain-refining agent for metallic materials such as melt-admixture for the production of products by casting process, comprises introducing two fine-grain materials in a mixer, and introducing the air into the mixer - Google Patents

Abstract

The method for producing a heterogeneous grain-refining agent for metallic materials such as melt-admixture for the production of products by casting process, comprises subjecting fine particles of a first fine-grain material, which has a high melting temperature than the melt and is provided as nucleating agent, with a metallic powder of a second fine-grain material to a common mechanical milling process in a mixer with mechanically moved mixer means until the fine particles of the first fine-grain material are moistened with the metallic powder of the second fine-grain material. The method for producing a heterogeneous grain-refining agent for metallic materials such as melt-admixture for the production of products by casting process, comprises subjecting fine particles of a first fine-grain material, which has a high melting temperature than the melt and is provided as nucleating agent, with a metallic powder of a second fine-grain material to a common mechanical milling process in a mixer with mechanically moved mixer means until the fine particles of the first fine-grain material are moistened with the metallic powder of the second fine-grain material, introducing the air into the mixer by a chemical inert protective gas or protective gas mixture, setting the mixer in a movement, stimulating the mixer for producing a relative high energy supply to the powder mixture to be milled, counting a pre-determined time duration, and stopping the mixer. The fine-grain materials introduced in the mixer stand to each other in a pre-determined mixing ratio. The first fine-grain material is non-metallic or metallic material with a high melting point than the melting point of the melt. The first non-metallic fine-grain material is a ceramic material. The ceramic material is non-oxidic or oxidic ceramic. The second fine-grain material is equal to the material of the melt or has equal or low melting point. The grain-refining agent is exposed to solidification in an additional process step by a pressing force effect. The pressing force effect is carried out in an extruded strand or in a pressing mold. The first fine-grain material acting as nucleating agent has a dimension of 1-10 mu m. The second fine-grain material has a dimension of 20-60 mu m. The energy supply to the particles of the milled mixture is mechanically carried out by the friction of the milled mixture due to the mixer movement. The control of the energy supply to the particles of the milled mixture is carried out by a movement speed setting or a rotational-speed setting and/or a movement speed control or a rotational-speed control of the mechanically moved mixer means of the mixer, and by a temperature setting and/or a temperature control. The pre-determined time duration of the mechanical and energetic effects on the mixture of the fine-grain materials in the order of magnitude is 5-30 minutes. The first and second fine-grain materials are selected, so that they step with one another in a chemical reaction. Independent claims are included for: (1) a grain-refining agent; (2) a cast-product; and (3) a dispersion material.

Description

The The invention relates to a process for producing a heterogeneous grain refining agent for metallic materials with those in the preamble of the claim 1 features, the grain refining agent produced by this method and the use of this grain refining agent in castings.

It It is known that a variety of precursors, semi-finished and Components made of metallic materials by means of various casting technology Process is prepared. The term "metallic material indicates in this context materials made of elemental metal as well as metal alloys. This also includes starting materials for metallic materials, which one later Be subjected to forming, as is the case, for example, with aluminum and magnesium materials.

requirement for the production of high-quality castings in the form of intermediate products, semi-finished products and end products is sufficiently high Homogeneity of the structure, which by a so-called Grain refining can be achieved.

In In the past, there have been extensive developments in this regard but no efficient grain refining agent has been started found for metallic materials, which the desired Properties sufficiently in particular in relation to an economically efficient production. Further influences grain refinement, which is the introduction of very small particles, which are also called nucleating agents, a higher-melting one Material in the melt corresponds, in a favorable manner the formation of grain structures during the solidification of the molten metal, which leads to higher mechanical properties of the cast product to lead. It can, for example, a higher Strength and / or hardness of the cast product be achieved.

at Magnesium castings was a melt addition of such agents To achieve a grain refining so far little successful. As a grain refining agent For example, zirconium was used, but Al, Si, Mn, Sn, Sb Ni Fe, or Co contained only in a limited amount in the melt may be. As a further grain refining agent for Magnesium alloys became carbon C in the form of metallic C6C16 Melt added. The disadvantage here is the formation of chlorine gas when decomposing the grain refining agent, therefore, in the melting treatment elaborate protective measures must be taken. As a grain refining agent for aluminum casting alloys usually potassium titanium fluoride, potassium boron fluoride salts or Titanium diboride master alloys used which have a distinct grain refining Have an effect on the structure. However, theirs is Effect insufficient to critical parts of cast components to produce a sufficiently fine-grained microstructure. In order to obtain the required microstructure morphology, must For example, when chill casting critical points in addition be cooled there to a rapid solidification of the Create mold wall. However, areas are problematic in the Inside large components where no fast cooling can be done. Here it comes to a slower solidification, whereby the cast structure over the cross-section of the component has strong inhomogeneity.

Next the heavy burden of chlorine gas in the foundry sector the use of C6C16, the problem persists Detectability of the grain refinement effect of carbon in the Matrix of magnesium alloys. Likewise there may be reactions with come to the melt added alloying elements, which to neutralize the grain refining effect of carbon.

by virtue of The interaction with other alloying elements could also be zirconium only with some magnesium alloys its grain-refining effect unfold. Another disadvantage is the high price of zirconium, which an economic use as grain refining difficult.

Rest Alloying elements for magnesium alloys such as Ca, Mn and Al are in terms of concentration, interactions with other alloying components and variations the casting parameters only in small quantities or not at all used. One use of these elements as grain refining agents is therefore only conditionally possible.

In summary can be noted that all previously known grain refining agents not in general, but only for certain metallic materials can be used under a complex dependency.

Farther Such grain refiners are only in tuned concentration Can be used in metallic material to develop their grain-refining effect to be able to. In this context, they are partially subject the interactions with the components of the metallic materials, whereby the variation possibilities of the remaining ones Casting parameters are severely limited.

There is already an approach that provides grain refining means by mechanically alloying various powders with the aid of a ball mill produce. Here, carbides or nitrides are proposed as grain refining agents for magnesium alloys, which are subjected to grinding with magnesium powders and thereby mechanically alloyed. The use of planetary ball mills limited due to the high peripheral speeds of the grinding container only on the laboratory scale.

industrial In contrast, ball mills, in principle, allow also a mechanical alloying of powders, but require for an equivalent energy input for production of grain refining agent significantly longer milling times. This in turn is associated with increased wear of the mills and grinding media, which in turn leads to high maintenance costs Machines leads.

In WO 03/033750 discloses a method in which by high-energy ball milling or vibratory ball milling of a powder mixture consisting of two powders, a deformable metal and a boron powder, a reduction of the particles down to 0.1-10 microns and at the same time a sheath of the boron particles (or carbon particles) takes place with the deformable metal. When using aluminum as a malleable metal, argon is used as the shielding gas to prevent oxidation of the aluminum. The use of ball grinder is as described above in terms of economy, wear and duration of the manufacturing process disadvantageous. The method is limited to the production of boron particles of the order of 0.1 to 10 microns, because smaller particles are not achieved and uses particles of the deformable material, a metal, in the order of 0.5 to 5 mm, ie quite macroscopic particles. In a later, in WO 03/095689 Further developed method is disclosed that the particles of the deformable material have a size of 0.05 to 5 mm, that may be compared to previously smaller, but still remain relatively large with 0.05 mm. In these processes, during the milling process, the boron particles migrate into and become trapped within the much larger particles of deformable material. Furthermore, it is disclosed that with particle sizes of the nucleating agent below 1 .mu.m, the heterogeneous nucleation of an aluminum melt is ineffective. It can be seen that the smaller particles of a nucleating agent are mechanically forced into comparatively large particles of a metallic material which later envelops them, so that in a larger deformable metal particle several nucleating agents can be included, which are thus arranged close to the surface of this larger particle , In extreme cases, it is a 5 mm ball, which has taken in its surface layer, a large number of, for example boron salt particles of the order of 0.1 to 10 microns.

In DE 10 2004 031 367 A1 discloses a method for producing a grain refining agent, wherein the nanoscale particles of a nucleating agent are subjected to a common grinding process with a metallic powder until they are wetted with the metallic material. The grain refining agents thus produced require a relatively long grinding time, whereby they are relatively expensive to manufacture. Furthermore, the method and the grain refining agent are suitable for producing dispersion materials. The finished grain refining agent is mechanically stabilized by pressing into pellets or extrudates for better transportation and handling.

Of the Invention is based on the object, a process for the preparation a grain refining agent for foundry melt, a grain refining agent and to propose materials to be produced which are economically viable Preparation of the grain refining agent and alike one allow further improvement of grain refining properties. Furthermore, no agglomeration, ie enlargement of the Particles by the means according to the invention occur.

Thereby, that in a process for producing a heterogeneous grain refining agent for metallic materials, in particular for the addition of melt for the manufacture of articles of metallic materials Help of casting process, in which fine particles of a first fine-grained material, which has a higher melting temperature as that of the melt, along with a metallic powder an at least second fine-grained material as long a common mechanical grinding process in a mixing plant with mechanical moving mixing agents are subjected to the fine particles of the first fine-grained material with the metallic one Powders of the second fine-grained material are wetted, in a first step at least two fine-grained materials entered in the mixer, in a second step the Air in the mixer by a chemically inert inert gas or Inert gas mixture is replaced, in a third step, the mixer is set in motion, in a fourth step, the grinder for Generating a relatively high energy input to the milled Powder mixture is stimulated and in a fifth step a predetermined period of time is counted until in a sixth Step the mixer is stopped, it is possible within a relatively short period of time, a grain refining agent with required properties.

In a further advantageous embodiment of the method according to the invention are in ers th step input into the mixer fine-grained materials mixed in a predetermined mixing ratio to each other. The mixing ratio is advantageously chosen so that as complete as possible dispersion of the fine-grained materials involved can take place.

In Yet another advantageous embodiment of the invention Process is essentially the first fine-grained material any metallic or non-metallic material having a higher melting point than the melting point of the melt. It is possible that the first fine-grained material is nonmetallic and this first, nonmetallic fine-grained Material is a ceramic material. Furthermore, the ceramic material a non-oxide or oxidic ceramic. It still happens an effective coating of the nucleating agent with the metallic Material of the second powder involved, which consists of a suitable, melt dissolvable metal or a metal alloy may exist or in an advantageous further embodiment the process of the invention substantially is equal to the material of the melt.

In a further advantageous embodiment of the invention Process is in an additional process step the grain refining agent is solidifying or so-called consolidating subjected by pressing force and this will be advantageous by the pressing force effect during extrusion or in a Mold executed. This does not agglomerate, that means no fusion of the metallic particles with the trapped particles of the nucleating agent under each other. The cut extruded pieces or in pressed molds pressed so-called pellets can be better store, transport and handle for adding to a melt.

In Yet another advantageous embodiment of the invention Method has the first, acting as a nucleating fine-grained Material dimensions between mm and 10 μm. In contrast to known grain refining agents described above, which in a below a lower limit of size for Nucleating agent of 1 micron lying dimension a decreasing Determine grain refining effect causes the invention produced Grain refining agent also with dimensions of the nucleating agent particles in the nanometer range a very good grain refining effect and allows so an extended influence on the properties of a The grain refining agent according to the invention refined Melt in terms of their flow properties and through the grain formation achievable mechanical properties of a finished cast product.

The second fine-grained material preferably has dimensions between 20 microns and 60 microns. The much smaller ones Particles of the nucleating agent mechanically become plastic during milling deformable material of the metallic powder introduced so that a plurality of nucleating agent particles in a metallic powder particle is introduced.

In a further advantageous embodiment of the invention Process, the energy is supplied to the particles of the milling mixture mechanically by friction of the grinding mixture due to the mixer movement the mechanically moving mixing means. The movement of the mixing means kneads the powder mixture and creates friction both on the surface the mixing parts and walls of the mixer as well as under the Particles themselves, which convert the mechanical kinetic energy resulting in heat energy, which thereby exactly It is where it is needed, namely the surfaces of the fine particles.

The Control of the energy supply to the particles of the grinding mixture is in an advantageous embodiment of the invention Method using a movement speed or a Speed specification and / or a movement speed or speed control performed the mechanically moving mixing means of the mixing plant. The detection of the movement of the mixing agent can for a particular mixer and a particular mixture of a particular one Mixture amount be determined experimentally.

In a further advantageous embodiment of the invention Method is controlling the energy input to the particles the milling mixture by means of a temperature specification and / or a Temperature control performed, which compared to previous, movement-related measurand one much more direct measure is used.

The predetermined period of mechanical and energetic action on the mixture of at least two fine-grained materials essentially on the order of 5 to 30 minutes. Here one of the main advantages of the according to the invention, in short production cycles, and therefore economically advantageous, a highly effective To be able to produce grain refining agent.

In Yet another advantageous embodiment of the invention Process is the first fine-grained material and the second fine-grained material chosen so that they together enter into a chemical reaction.

To Another aspect of the present invention, in a Grain refining agent, in particular a heterogeneous grain refining agent for Metallic materials for the addition of melt for the production of articles of metallic materials by means of casting, in the fine particle of a first fine-grained material, which has a higher melting temperature than that of the melt and is provided as a nucleating agent, together with a metallic one Powder of at least second fine-grained material as long as a common mechanical grinding in a mixer be subjected to mechanically agitated mixing means until the Fine particles of the first fine-grained material with the metallic powder of the second fine-grained material are wetted, the fine particles of the intended as a nucleating agent Material dimensions between 1 nm and 10 microns, where the second fine-grained material in an advantageous Embodiment of the present invention Dimensions between 20 microns and 60 microns.

In a preferred embodiment of the present invention the fine-grained materials fed into the mixer in a predetermined mixing ratio to each other.

The First fine-grained material is in a further preferred Embodiment of the present invention, a substantially arbitrary metallic or non-metallic material with a higher Melting point as the melting point of the melt, which in a advantageous further embodiment is non-metallic and further in a still further embodiment of the present invention a ceramic material is.

The Ceramic material can be a non-oxide or oxidic ceramic be, wherein the second fine-grained material is preferably is substantially equal to the material of the melt. This is ensures that this second material immediately melts after addition of the grain refining agent in a melt and seamlessly merges into the melt, eliminating the particles of the nucleating agent immediately in the metal or metal alloy the melt and have been previously wetted with him.

Corresponding Another aspect of the present invention is a grain refining agent proposed that with the method steps described above is made.

To Yet another aspect of the present invention is a use of the grain refining agent described above, with the above-described Process steps is prepared for addition to a metallic Melt proposed.

Further According to yet another aspect of the present invention are cast products proposed, with the admixture of the above described Process steps produced grain refining agent produced are.

About that In addition, according to yet another aspect of the present invention proposed a dispersion material consisting of particles of at least two of different materials arranged as alternately adjacent Tiny particles of the respective material, the heterogeneous material structure of the material Forming of the dispersion material, consists in which as at least single smallest particle an inventive heterogeneous grain refining agent according to one of the previously described Aspects and configurations is used.

Further preferred embodiments of the invention will become apparent from the compositions of the others, in the subclaims, features.

The Application spectrum of the grain refining agent according to the invention extends over all casting processes. In particular, it is excellent for applications to casting technical production large volume and thick-walled components, such as engine blocks or Gearbox. Likewise, the grain fining agent according to the invention for the production of continuous casting precursors which are starting materials for wrought alloys represent.

Especially in heavily loaded aluminum components, as in the aggregate of the Case is a grain refining treatment in addition to the homogenization the cast structure already during casting of the melt an improvement of the flowability. To this Wise could also previously difficult to cast alloys AlCu-based, very low silicon AL alloys and hypereutectic Al-silicon alloys for complicated and simultaneous highly loaded components can be utilized.

The foregoing embodiments of the present invention are merely exemplary in nature and are not to be construed as limiting the present invention. The present invention may easily be transferred to other applications. The description of the embodiment is provided for illustration and not to limit the scope of the claims. Many alternatives, modifications and variations will be apparent to one of ordinary skill in the art without departing from the scope of the present invention as set forth in US following claims is defined.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• WO 03/033750 [0013]
• WO 03/095689 [0013]
• DE 102004031367 A1 [0014]

Claims (28)

A process for the preparation of a heterogeneous grain refining agent for metallic materials, in particular for the melt addition for the production of products from metallic materials by means of casting processes, wherein the fine particles of a first fine-grained material having a higher melting temperature than that of the melt and provided as a nucleating agent is a common mechanical grinding in a mixer with moving mechanical mixing means together with a metallic powder of at least the second fine granular material while subjected to the fine particles of the first fine-grained material are wetted with the metal powder of the second fine-grained material, characterized in that that in a first step at least two fine-grained materials are introduced into the mixing plant, in a second step the air in the mixing plant is replaced by a chemically inert protective gas or inert gas mixture, in e in the third step, the mixer is set in motion, in a fourth step, the grinder for generating a relatively high energy supply to the powdered mixture is stimulated and in a fifth step a predetermined period of time is counted until in a sixth step, the mixer is stopped. Process for the preparation of a heterogeneous grain refining agent according to claim 1, characterized in that in the first step in the mixer entered fine-grained materials in a predetermined mixing ratio to each other. Process for the preparation of a heterogeneous grain refining agent according to one of the preceding claims, characterized that the first fine-grained material is a substantially any metallic or non-metallic material having a higher melting point than the melting point of the melt is. Process for the preparation of a heterogeneous grain refining agent according to one of the preceding claims, characterized that the first fine-grained material is non-metallic. Process for the preparation of a heterogeneous grain refining agent according to claim 4, characterized in that the first, non-metallic fine-grained material is a ceramic material. Process for the preparation of a heterogeneous grain refining agent according to claim 5, characterized in that the ceramic material non-oxide or oxide ceramic is. Process for the preparation of a heterogeneous grain refining agent according to one of the preceding claims, characterized that the second fine-grained material is substantially the same the material of the melt is equal or lower Has melting point. Process for the preparation of a heterogeneous grain refining agent according to one of the preceding claims, characterized that in an additional process step, the grain refining agent is subjected to solidification by pressing force. Process for the preparation of a heterogeneous grain refining agent according to claim 7, characterized in that the pressing force executed in an extrusion or in a mold becomes. Process for the preparation of a heterogeneous grain refining agent according to one of the preceding claims, characterized that the first, acting as a nucleating fine-grained material Dimensions between mm and 10 microns. Process for the preparation of a heterogeneous grain refining agent according to one of the preceding claims, characterized that the second fine-grained material dimensions between 20 microns and 60 microns. Process for the preparation of a heterogeneous grain refining agent according to one of the preceding claims, characterized that the energy supply to the particles of the grinding mixture mechanically due to friction of the grinding mixture as a result of the mixer movement. Process for the preparation of a heterogeneous grain refining agent according to one of the preceding claims, characterized that controlling the energy input to the particles of the milling mixture with the help of a movement speed or a speed specification and / or a Bewegungsgeschwindigkeits- or speed control of mechanically moving mixing means of the mixing plant takes place. Process for the preparation of a heterogeneous grain refining agent according to one of the preceding claims, characterized that controlling the energy input to the particles of the milling mixture with the help of a temperature specification and / or a temperature control he follows. A method for producing a heterogeneous grain refining agent according to any one of the preceding claims, characterized in that the predetermined period of mechanical and energetic table effect on the mixture of at least two fine-grained materials in the order of 5 to 30 minutes. Process for the preparation of a heterogeneous grain refining agent according to one of the preceding claims, characterized that the first fine-grained material and the second fine-grained material Material are chosen so that they are together in a chemical Reaction occur. Grain refining agent prepared by the method according to claim 1 to 16. Grain refining agent, especially a heterogeneous Grain refining agent for metallic materials for the melt additive for the manufacture of metallic products Materials by means of casting, in which fine particles of a first fine-grained material, which has a higher melting temperature as that of the melt and provided as a nucleating agent is, together with a metallic powder of at least a second fine-grained material as long as a common mechanical Subjected grinding in a mixer with mechanically moving mixing agents until the fine particles of the first fine-grained material with the metallic powder of the second fine-grained material are wetted, characterized in that the fine particles of the as nucleating material provided dimensions between mm and 10 microns. Grain refining agent according to claim 18, characterized that the second fine-grained material dimensions between 20 microns and 60 microns. Grain refining agent according to claim 18 or 19, characterized characterized in that in the mixer entered fine-grained Materials in a predetermined mixing ratio to stand by each other. Grain refining agent according to one of the claims 18 to 20, characterized in that the first fine-grained Material is a substantially arbitrary metallic or non-metallic Material with a higher melting point than the melting point the melt is. Grain refining agent according to one of the claims 18 to 21, characterized in that the first fine-grained Material is non-metallic. Grain refining agent according to one of the claims 18 to 22, characterized in that the first, non-metallic fine-grained material is a ceramic material. Grain refining agent according to claim 23, characterized that the ceramic material is a non-oxidic or oxidic Ceramics is. Grain refining agent according to one of the claims 18 to 24, characterized in that the second fine-grained Material is essentially equal to the material of the melt or has the same or lower melting point. Use of the grain refining agent with the A method according to claim 1 to 16 is prepared, or the grain refining agent according to claim 18 to 25 for addition in a metallic melt. Castings obtained with the addition of a Process according to Claims 1 to 16, grain refining agent prepared or the grain refining agent of claims 18 to 25 are. Dispersion material consisting of particles at least two different materials, which are considered to be adjacent arranged smallest particles of each material, the heterogeneous Form material structure of the dispersion material, characterized that as at least single smallest particle, a heterogeneous grain refining agent used according to one of the preceding claims 1 to 27 is.