DE102020104311A1 - Plant and method for producing a strip with a rapid solidification technology and metallic strip - Google Patents

Abstract

A method of making a tape with rapid solidification technology is provided. A melt is poured onto a moving outer surface of a rotating casting wheel, the melt solidifying on the outer surface of the casting wheel and forming a ribbon. A jet is directed at the moving outer surface of the casting wheel and the outer surface of the casting wheel is machined with the jet. The jet has solid particles.

Description

The invention relates to a system for manufacturing a strip using rapid solidification technology, a method for manufacturing a strip using rapid solidification technology, and a metallic strip.

From an economic point of view, it is desirable that thin, rapidly solidified metal strips can be manufactured in large continuous strip lengths without this strip tearing off in the manufacturing process and without the quality of the strip changing negatively over the duration of the casting process. Due to the thermomechanical loading of the casting wheel during strip production, however, the casting track surface of the casting wheel is continuously disrupted within a few kilometers of strip produced on it, which leads to inhomogeneous strip quality with an increase in roughness and thus, among other things, reduces the lamination factor of the strips.

In order to produce continuous pieces of tape that are as long as possible and of constant quality, it is therefore known to process the surface of the casting track simultaneously with the production of the tape in order to maintain the quality of the surface for as long as possible. This can be done through material-removing processes such as polishing the casting wheel, as in the EP 3 089 175 B1 disclosed, or by grinding the casting wheel or by brushing, as in FIG US 6,749,700 B2 revealed to be achieved. the US 9 700 937 B1 discloses an alternative forming process in which the casting wheel track is continuously rolled in order to smooth it. However, further improvements are desirable.

The task is therefore to reliably produce a metal strip with good material quality in great lengths.

According to the present invention there is provided a method for producing a strip using rapid solidification technology, in which a melt is poured onto a moving outer surface of a rotating casting wheel, the melt on the outer surface solidifying and a strip being formed. A jet is directed at the moving outer surface of the casting wheel and the outer surface of the casting wheel is machined with the jet. The jet has solid particles.

The particles can consist of various materials. For example, the particles can be metallic, ceramic, inorganic or organic. In some exemplary embodiments, the particles have a particle size of 10 μm to 10 mm, preferably 10 μm to 500 μm. The particles can be spherical, oblong or angular.

In some exemplary embodiments, the particles are accelerated to the outer surface with a carrier gas. The pressure of the carrier gas can be adjustable in order to adjust the efficiency of the jet of solid particles.

A blasting technique is thus used in connection with the rapid solidification casting process in order to process and prepare the outer surface of the casting wheel, in particular the casting track on which the melt is poured, so that a metallic strip of higher uniform quality can be produced in great lengths. Using a carrier such as compressed air, gases and / or fluids or mechanical components such as a centrifugal wheel, different blasting media with high kinetic energy can be conveyed onto the outer surface of the casting wheel in order to change its condition or properties.

With the choice of the parameters of the jet, a very intensive and at the same time very gentle processing of the outer surface of the casting wheel can be achieved, so that signs of wear cannot develop in the first place. This results in no or only negligible material removal, because with a suitable selection of the blasting agent, essentially only deformation processes take place. Due to the continuous reshaping of the entire stressed outer surface, a uniform, isotropic topology of the outer surface of the casting wheel in the area of the casting track, stable wetting and high product quality can be achieved over a long period of time.

In one embodiment, the jet strikes the outer surface of the casting wheel while the melt is poured onto the outer surface of the rotating casting wheel. The machining process with the jet of solid particles can thus be carried out inline.

In some exemplary embodiments, the outer surface of the casting wheel is reshaped or conditioned by the jet, with no or only negligible material removal and loss of mass occurring.

A deformation process is defined herein by a rate of removal of the material of the casting wheel of less than 10 μm / min, preferably less than 5 μm / min, preferably less than 1 μm / min. For example, spherical particles can be used to keep the removal rate below this limit so that the outer surface is reshaped and conditioned. A forming process has the advantage that wear on the outer surface is avoided, so that a high quality strip is achieved over a long period of time can be. The diameter of the casting wheel is therefore not significantly reduced over a longer period of time, so that adjustments to the distance between the casting nozzle and the outer surface can be avoided and the thickness of the strip remains more homogeneous. In alternative embodiments, however, an abrasive or ablative process is desired by machining the outer surface with the jet of solid particles. In these exemplary embodiments, the removal rate of the material of the outer surface is greater than 10 μm / min. For example, angular particles can be used to increase the removal rate. An abrasive process can be used to renew the outer surface, for example to remove oxidation and wear and tear.

In some exemplary embodiments, the surface roughness of the outer surface of the casting wheel is changed by the jet. In some exemplary embodiments, the mean surface roughness R _{a can be} increased. However, peaks can be reduced and larger foreign particles removed, so that the value of R _{z is} reduced. The quality of the tape can thus be increased, since the risk of tape tears and holes is reduced.

Another advantage of blasting technology results from the use of very different blasting media. The surface topology created by the blasting is very variable and, in contrast to many other processing techniques, isotropic in the x-y direction, i.e. there are no direction-dependent processing traces such as when turning, milling, grinding, brushing or polishing.

In some exemplary embodiments, the jet creates a laterally isotropic structure in the outer surface of the casting wheel. The surface structure therefore does not have a direction-dependent structure, i.e. the structure in an X direction across the casting track or across the direction of rotation of the casting wheel is the same as the structure in a Y direction along the casting track or in the direction of rotation of the casting wheel. Since the surface of the strip that solidifies on the casting wheel largely adopts the surface structure of the casting wheel, this side of the strip also has a direction-independent structure. This is advantageous when the surface structure has an influence on the properties of the tape and homogeneous properties are desired in the transverse direction and in the longitudinal direction of the tape.

In some exemplary embodiments, a speed of the jet and / or a mass flow rate of the jet are adjusted in order to adjust the surface roughness of the outer surface of the casting wheel. For example, the speed and / or the mass flow can be increased in order to remove firmly adhering impurities and / or signs of wear from the outer surface.

The possibilities of blasting technology range from gentle cleaning to aggressive material removal, which can be achieved, for example, with sandblasting or corundum blasting, to targeted solidification of the material in the near-surface area by cold forming or by introducing internal stresses, as achieved, for example, with shot peening can be.

Beam technology also offers an extremely wide range of variation in the intensity of the processing. The selection of the right abrasive is essential. Blasting media differ in material (organic, inorganic, ceramic, metallic, etc.), particle size (from µm .... mm range), strength values (hardness, yield strength, tensile strength, elongation at break, modulus of elasticity, etc.), geometry (sharp-edged , round, elongated, etc.) and specific weight.

In some exemplary embodiments, the particles are sucked off after they hit the outer surface of the casting wheel. In this way, an area of the outer surface can be processed in a targeted manner, and at the same time it is prevented that particles get into the melt droplets and thus into the metal strip that is being formed.

In one embodiment, the jet is directed onto the outer surface of the casting wheel by means of compressed air jets or suction head jets or injector jets with blasting medium return. Suction head blasting and injector blasting with abrasive return have the advantage of lower spatial emission of abrasive. In this way, the penetration of the blasting agent or solid particles into the melt and the solidified strip can be better avoided. For example, ring brushes placed on the rapidly rotating casting wheel surface can be used to seal off the blasting space well from the environment so that only a small amount of blasting media is discharged.

In some exemplary embodiments, one or more jet nozzles are used to align the jet or jets with the outer surface of the casting wheel. In some exemplary embodiments, a distance between the jet nozzles and the outer surface of the casting wheel can be adjusted so that the intensity with which the jet hits the outer surface of the casting wheel can be adjusted.

In some embodiments, the outer surface of the casting wheel moves in a direction of rotation. The jet of solid particles hits the outer surface of the casting wheel at a first one Position which, viewed in the direction of rotation, is arranged in front of a second position at which the melt hits the outer surface. This first position is arranged after the detachment point of the strip from the casting wheel, as seen in the direction of rotation. The outer surface is thus processed with the jet of solid particles after the solidified strip has been detached and before the melt comes into contact.

The blasting technique for processing the outer surface of the casting wheel can be used together with one or more other surface processing methods.

In one embodiment, the outer surface is further cleaned or reshaped or abraded at a third position with a surface treatment agent. This third position is arranged after the first position, seen in the direction of rotation, at which the jet of solid particles hits the outer surface of the casting wheel, but seen in the direction of rotation, before the second position, at which the melt hits the outer surface of the casting wheel.

If the outer surface of the casting wheel is reshaped with the jet of solid particles, the subsequent surface treatment agent can reshape and / or clean the outer surface, since an abrasive abrasive process could increase the surface roughness compared to the reshaped surface roughness. If, however, the outer surface is removed with the jet of solid particles, the subsequent surface processing agent can reshape, remove and / or clean the outer surface.

The surface treatment means at this third position can be one or more brushes which are pressed onto the outer surface of the casting wheel while the casting wheel is rotating and / or have a jet of _{compressed air and / or a jet containing CO 2.} The CO _{2 of} the CO ₂ containing jet strikes at least partially in the solid state the moving outer surface of the casting wheel.

In the event that the surface treatment _{agent has a jet containing CO 2} at the third position, residues on the casting wheel, which can lead to wetting problems of the melt and to defects in the strip, can be removed. Due to material-removing processes, machining residues such as dust, bristle hair, polish and / or lubricant residues can remain on the outer surface of the casting wheel and can thus be carried into the melt droplets and lead to imperfections in the forming strips. In the case of thicker strips of more than 20 μm strip thickness, such wetting problems can be seen as air pockets on the casting wheel side of the amorphous strip. However, particularly in the case of thin strips with a thickness of less than 20 μm, these wetting defects can lead to undesirably large holes in the strip, which can be the starting point for breaks in the strip. Even with forming methods of machining the casting wheel surface, it cannot be ruled out that lubricant can get from the pivot and bearing points onto the wheel surface and lead to disturbances in wetting and thus to flaws in the strip. According to the invention, these residues on the outer surface of the casting wheel are removed with a jet with the aid of which CO _{2 is} accelerated in a solid state onto the outer surface, this jet being able to remove the residues in order to improve the surface quality of the outer surface. Thus, the number of defects in the tape can be reduced. The production length can also be increased and a low surface roughness can be ensured over longer lengths of the strip.

The solid CO ₂ has the further advantage that it sublimates. This prevents the jet itself from leaving residues on the outer surface. Through this sublimation, residues and other undesirable foreign bodies such as lubricants, which are present in the solid and liquid state on the surface of the casting wheel, can also be carried along and removed from the solid state in the gas phase _{through the sublimation of the CO 2 particles occurring on the surface.}

In one embodiment, the gas-containing jet hits the outer surface of the casting wheel at the third position, while the melt is poured onto the outer surface of the rotating casting wheel. Thus, the outer surface can be processed and cleaned inline and before each contact with the melt. This exemplary embodiment can be used in processes in which the outer surface is machined with an abrasive and / or reshaping process while the melt is poured onto the outer surface of the rotating casting wheel.

One or more jet nozzles can be provided through which the _{jet or jets containing CO 2} are directed to the outer surface of the casting wheel. The beam can thus be directed spatially in order to process a predetermined area of the outer surface, primarily the casting track.

In one embodiment, a distance between the jet nozzle and the outer surface of the casting wheel can be adjusted. In this way, the intensity with which the gas-containing jet hits the outer surface of the casting wheel can be adjusted.

In one embodiment, a CO ₂ source of liquid CO _{2 is} provided as a jet. From this liquid CO _2, particles crystallize, ie CO ₂ in a solid state, to form CO ₂ snow, which hits the outer surface of the casting wheel as a jet containing _{gas and CO 2 snow.} The particles that crystallize from the liquid CO ₂ are typically spherical due to this process. The particles of CO ₂ snow have an average particle size of 0.1 µm to 100 µm.

In one embodiment, the particles of CO ₂ snow are accelerated onto the outer surface of the casting wheel without additional carrier gas in the CO _{2 gas flow.}

In an alternative embodiment, the particles of CO ₂ snow are accelerated onto the outer surface of the casting wheel with a carrier gas. The pressure of the carrier gas can be adjustable.

gilt. Die Schmelze und somit das Band können ferner bis zu 1 Atom-% an Verunreinigungen enthalten.The melt and thus the tape can have different compositions. In one embodiment, the melt consists of Fe _100-abwxyz T _a M _b S _iw B _x P _y C _z (in atomic%), where T is one or more of the elements of the group consisting of Co, Ni, Cu, Cr and V denotes, M denotes one or more of the elements of the group consisting of Nb, Mo and Ta, and $$\begin{array}{ccccc}\text{0}& \le & \text{a}& \le & 70\\ 0& \le & \text{b}& \le & 9\\ 0& \le & \text{w}& \le & \mathrm{18th}\\ 5& \le & \text{x}& \le & \mathrm{20th}\\ 0& \le & \text{y}& \le & \mathrm{7th}\\ 0& \le & \text{z}& \le & 2\end{array}$$

is applicable. The melt and thus the tape can also contain up to 1 atom% of impurities.

The solidified ribbon is normally at least predominantly amorphous and can be heat treated in a further process in order to produce a nanocrystalline ribbon. The heat treatment can also be used to adjust the properties, for example the magnetic properties, of the tape.

For example, the solidified amorphous band can consist of at least 80% by volume of amorphous material. The nanocrystalline band can have at least 80% by volume of nanocrystalline grains and amorphous residual matrix, of which at least 80% of the nanocrystalline grains have an average grain size of less than 50 nm and a random orientation.

According to the invention, a system for producing a metal strip with rapid solidification technology is provided. The system comprises a rotating casting wheel with an outer surface onto which a melt is poured through a nozzle, the melt solidifying on the outer surface and forming a metal strip. The system further comprises means for directing a jet comprising solid particles onto the outer surface of the casting wheel in order to process the outer surface of the casting wheel with the jet.

The solid particles can be inorganic, organic, ceramic or metallic. The particles can have a particle size of 10 μm to 10 mm, preferably 10 μm to 500 μm, and can be spherical, oblong or angular.

In one embodiment, the shape and size of the particles and / or the jet pressure is selected to reshape the outer surfaces and reduce the removal rate to less than 10 μm / min, preferably less than 5 μm / min, preferably less than 1 μm / min.

For example, the means for directing a jet containing solid particles can have a nozzle system which is suitable for compressed air blasting or suction head blasting or injector blasting with blasting medium return. The nozzle system can have a single-fluid nozzle or a two-fluid nozzle. In some exemplary embodiments, the nozzle system can also be connected to a carrier gas source, with the aid of which the solid particles are accelerated onto the outer surface of the casting wheel.

The nozzle system can be used to determine the spatial direction of the jet so that the jet hits the outer surface of the casting wheel, in particular hits a desired location on the outer surface of the casting wheel.

In some exemplary embodiments, the system also has a suction system for removing the solid particles and the material detached from the outer surface of the casting wheel. In this way, the penetration of the solid particles and the detached material into the melt and the band solidified from it can be better avoided.

In some exemplary embodiments, the casting wheel can be moved in a direction of rotation and the means is designed or arranged in relation to the casting wheel in such a way that the jet strikes the outer surface of the casting wheel at a first position which, when viewed in the direction of rotation, is arranged before a second position which the melt hits the outer surface of the casting wheel. Thus, the outer surface becomes solid particles with the jet machined and poured the melt onto the machined outer surface.

In some exemplary embodiments, the system also has surface processing means for processing the outer surface at a third position of the casting wheel. This third position, viewed in the direction of rotation, is arranged after the first position, at which the jet hits the outer surface, but, viewed in the direction of rotation, is arranged before the second position, at which the melt hits the outer surface of the casting wheel.

The outer surface of the casting wheel is thus first processed with the jet of solid particles and then again with the additional surface processing agents and only then is the melt poured onto the repeatedly processed outer surface of the casting wheel. The system can also have several surface processing means, so that the outer surface can be processed several times after processing with the jet of solid particles.

The surface treatment means at this third position can have one or more brushes which are pressed onto the outer surface of the rotating casting wheel while the casting wheel outer surface is moving, and / or means for directing a _{jet containing CO 2} onto the outer surface of the casting wheel, the jet Has CO ₂ , which at least partially in the solid state hits the moving outer surface of the casting wheel in order to process and / or clean the outer surface of the casting wheel with the jet.

The surface treatment means at this third position can thus have several separate means, for example two brushes arranged one after the other as seen in the direction of rotation, or, as seen in the direction of rotation, first one or more brushes and then means for directing a jet containing _{CO 2.}

In embodiments in which the plant has means for directing a _{jet containing CO 2} onto the outer surface of the casting wheel, the plant can furthermore have a further nozzle system for forming the jet _{containing CO 2.}

In one exemplary embodiment, the system also has a nozzle system for forming the jet _{containing CO 2.} The design of the nozzle system can be adapted to the type of CO ₂ source.

In one embodiment, the CO _{2 is provided} as liquid CO ₂ and the nozzle system is a nozzle system for liquid CO ₂ . The nozzle system can have a single-fluid nozzle or a two-fluid nozzle. In embodiments in which a carrier gas is used in addition to the liquid CO ₂ , a two-substance nozzle can be used.

In some exemplary embodiments, the system also has an exhaust air system for removing CO ₂ gas. This ensures that the atmosphere in the vicinity of the system complies with environmental and occupational health and safety regulations.

In some exemplary embodiments, the system also has a winder for continuously taking up the solidified strip.

In some exemplary embodiments, the system also has a casting nozzle for a melt made of an alloy, from which the melt can be poured onto the outer surface of the casting wheel.

The use of the system according to one of the preceding exemplary embodiments for the production of a metallic strip consisting of Fe _100-abwxyz T _a M _b Si _w B _x P _y C _z (in atomic%) and up to 1 atom% of impurities, where T denotes one or more of the elements of the group consisting of Co, Ni, Cu, Cr and V, M denotes one or more of the elements of the group consisting of Nb, Mo and Ta, and 0 a 70, 0 b 9, 0 ≤ w ≤ 18, 5 ≤ x ≤ 20, 0 ≤ y ≤ 7 and 0 ≤ z ≤ 2 applies.

_{According to the} invention, a metallic strip is provided which consists of Fe 100-abwxyz Ta M _b Si _w B _x P _y C _z (in atomic%) and up to 1 atom% of impurities, where T is one or more of the elements of the Group consisting of Co, Ni, Cu, Cr and V denotes, M denotes one or more of the elements of the group consisting of Nb, Mo and Ta, and 0 ≤ a ≤ 70, 0 ≤ b ≤ 9, 0 ≤ w ≤ 18, 5 x 20, 0 y 7, 0 z 2, the metallic strip having at least one surface with an average surface roughness R _a between 0.05 μm and 1.5 μm.

In one embodiment, the surface roughness R _{a has} a deviation of less than +/- 0.2 μm over a production length of at least 5 km, preferably of at least 20 km.

The metallic tape can be ductile and amorphous or nanocrystalline. Typically, the metallic strip is amorphous in the cast state and has a structure that is at least 80% by volume amorphous, and is heat-treated or annealed in order to produce a nanocrystalline structure from the amorphous strip. The heat treatment conditions depend on the composition, the properties desired, for example the desired magnetic properties, as well as the desired grain size dependent. The nanocrystalline structure can have at least 80% by volume of nanocrystalline grains and amorphous residual matrix, of which at least 80% of the nanocrystalline grains have an average grain size of less than 50 nm and a random orientation.

The metallic strip has a casting wheel side which has solidified on the outer surface of the casting wheel and an opposite air side which has solidified in air. In some exemplary embodiments, the metallic strip on the casting wheel side has a technically clean surface immediately after it has been detached from the casting wheel, free of organic and inorganic residues, which is achieved in the solid state _{due to the treatment of the outer surface of the casting wheel with the jet with CO 2.}

In some exemplary embodiments, the metallic strip has a width of 2 mm up to 300 mm, a thickness of less than 50 μm, and a maximum of 50 holes per square meter.

In some exemplary embodiments, the metallic strip has a width of 20 mm to 200 mm and / or a thickness between 10 μm and 18 μm and / or fewer than 25 holes per square meter, preferably less than 10 holes per square meter. Here, the term “hole” is used to define a hole in the strip with a minimum area of 0.1 mm ^2.

In some exemplary embodiments, the metallic strip has a structure which is at least 80% by volume amorphous, or which has at least 80% by volume of nanocrystalline grains and amorphous residual matrix, of which at least 80% of the nanocrystalline grains have an average grain size of less than 50 nm and show a random orientation, the air side and / or the casting wheel side having a surface crystallization fraction of less than 23%.

In some exemplary embodiments, the air side and / or the casting wheel side have a surface crystallization fraction of less than 5%.

The properties of the casting wheel side and the air side of the metal strip are different due to the manufacturing process and can therefore be recognized on the metal strip produced. The casting wheel side and the air side of the metal strip can also be distinguished with the naked eye. The air side typically appears shiny metallic, while the casting wheel side appears more matt.

Surface crystallization refers to the formation of crystalline grains on the surface of the tape, i.e. within a surface layer of the tape. For example, the crystalline grains of the surface layer in more than 80% by volume of the crystalline grains have an average grain size of more than 100 nm.

These crystalline grains have an average grain size which, in the case of a nanocrystalline metal strip, is larger than the average grain size of the nanocrystalline grains of the nanocrystalline metal strip and can therefore be distinguished from them. The crystalline grains of the surface layer have, for example, an average grain size of more than 100 nm, while the nanocrystalline grains have an average grain size of at most 50 nm.

The proportion of surface crystallization can be determined by means of X-ray powder diffractometry using copper-Kα radiation. The surface crystallization proportions given herein are determined as follows. For an amorphous strip, the surface portion is divided by the quotient of the area portion of a characteristic reflection of a crystalline phase, i.e. the crystalline phase of the surface crystallization, by the sum of the area portion of a halo, which is characteristic of an amorphous phase, and the area portion of the characteristic reflection the crystalline phase determined.

The characteristic reflection of the crystalline phase of the surface crystallization depends on the structure and composition of the crystalline phase. For example, a (400) reflection is used for silicon-containing phases if these, as is almost always the case in the present cases, are strongly textured in the (100) direction.

• Zunächst wird der Flächenanteil eines zweiten charakteristischen Reflexes bestimmt, der charakteristisch für die nanokristalline Phase ist.

Since in the present cases the surface crystallization was almost always strongly textured in the (100) direction, the proportion of surface crystallization in a nanocrystalline sample can be determined as follows:

• First, the area portion of a second characteristic reflex is determined, which is characteristic of the nanocrystalline phase.

Then the area portion of a first characteristic reflex is determined, which is characteristic of the crystalline phase of the surface crystallization. However, this surface area must be reduced by the amount that the nanocrystalline phase contributes to this reflex. With pure iron this is 20% of the second characteristic reflex, with Fe ₃ Si 12.8%. Since the exact Si content is not easily known, 20% was always deducted, which in the case of Si-containing alloys can lead to a slight underestimation of the proportion of surface crystallization.

For a nanocrystalline strip, the surface portion is now divided by the quotient of the surface portion of a first characteristic reflection of a crystalline phase, i.e. the crystalline phase of the surface crystallization, but by the contribution of the nanocrystalline phase to this reflection, divided by the sum of the surface portion of a second characteristic Reflexes, which is characteristic of the nanocrystalline phase, and the total area portion of the first characteristic reflex of the crystalline phase is determined.

For example, for silicon-containing phases, a (400) reflection is used as the first characteristic reflection of the surface crystallization and the (220) reflection is used as the second characteristic reflection of the nanocrystalline phase.

In the event that the surface crystallization is not textured, its proportion can only be determined on the cast amorphous strip, as described above for amorphous strips. In the nanocrystalline state, the portion of the surface crystallization and the nanocrystalline phase can no longer be distinguished by powder diffractometry due to the lack of the texture of the surface crystallization. However, since the surface crystallization grows into a continuous layer under the heat treatment, the proportion of surface crystallization in the nanocrystalline sample is always the same or greater than in the amorphous sample.

• 1 zeigt eine schematische Darstellung einer Anlage zum Herstellen eines metallischen Bandes mittels Rascherstarrungstechnologie nach einem ersten Ausführungsbeispiel.
• 2 zeigt eine schematische Darstellung eines Düsensystems zum Bearbeiten der Außenoberfläche mit einem Strahl aus festen Partikeln.
• 3 zeigt eine Aufnahme einer Oberfläche eines Metallbandes, das auf einer Oberfläche erstarrt worden ist, welche mit einem feste Partikel aufweisenden Strahl bearbeitetet, wurde.
• 4 zeigt eine schematische Darstellung einer Anlage zum Herstellen eines metallischen Bandes mittels Rascherstarrungstechnologie nach einem zweiten Ausführungsbeispiel.

The exemplary embodiments will now be explained with reference to the drawings.

• 1 shows a schematic representation of a plant for producing a metallic strip by means of rapid solidification technology according to a first embodiment.
• 2 shows a schematic representation of a nozzle system for processing the outer surface with a jet of solid particles.
• 3 FIG. 13 shows a photograph of a surface of a metal strip which has been solidified on a surface which has been processed with a jet comprising solid particles.
• 4th shows a schematic representation of a plant for producing a metallic strip by means of rapid solidification technology according to a second embodiment.

1 shows a schematic representation of a plant 10 for the production of a metallic band 11 by means of rapid solidification technology according to a first embodiment.

The attachment 10 has a rotating casting wheel 12th with an outer surface 13th on to which a melt 14th is poured. The casting wheel 12th can also be described as a heat sink. In the system shown 10 the casting wheel rotates around an axis 15th in a direction of rotation indicated by the arrow 16 is shown. The melt 14th solidifies on the outer surface 13th of the casting wheel 12th and the metal band 11 is formed. The rate of solidification of the melt 14th is typically very high, for example greater than 10 ⁵ ° C / s, so that the melt 14th as an amorphous ribbon 11 stiffens.

The casting wheel surface 13th has good thermal conductivity and causes the melt applied to solidify very quickly 14th and a bond is created 11 which, due to its special structure and / or composition, has special mechanical, physical and / or magnetic properties. The outside surface 13th of the casting wheel 12th can be made of copper or a copper-based alloy.

The attachment 10 also has means 17th for directing a beam 18th of solid particles or abrasives to the outer surface 13th of the casting wheel 12th on. The beam 18th exhibits particles 19th on, at a desired speed, the moving outer surface 13th of the casting wheel 12th meet to the outside surface 13th of the casting wheel 12th with the beam 18th to edit. These solid particles 19th can be ceramic, inorganic, metallic or organic. For example, the particles 19th made of sand, metal, corundum, glass or, for example, granules made from nutshells. The term “solid particles” excludes CO ₂ particles in the solid state at this point.

Depending on the material of the particles 19th , the shape of the particles and the speed with which they hit the outer surface 13th of the casting wheel 12th they can hit the outside surface 13th edit differently. For example, the outer surface 13th are mainly reshaped, so that a desired surface roughness of the outer surface 13th can be adjusted. During forming, the rate of removal of the material from the outer surface of the casting wheel is less than 10 μm / min, preferably less than 5 μm / min, preferably less than 1 μm / min. Spherical particles can be used to keep the removal rate below this limit. Thus, the surface roughness of the outer surface 13th on which the melt 14th is poured, only have minor deviations from an average value, so that signs of wear are avoided. This enables, for example, the tape 11 Manufacture over longer production lengths with a more homogeneous and / or lower surface roughness, as the side of the belt 11 that are on the outside surface 13th of the casting wheel 12th solidified, largely reflects the nature of the outer surface.

In other exemplary embodiments, the outer surface 13th be machined with the removal rate greater than 10 µm / min. This allows unwanted particles and material to be removed from the outer surface 13th removed. For example, the speed and / or the particle size can be increased in order to exert an abrasive effect instead of a reshaping effect on the outer surface of the casting wheel.

The beam 18th hits the outside surface 13th of the casting wheel 12th at a first position 20th that are in the direction of rotation 16 seen in front of a second position 21 at which the melt 14th the outer surface 13 meets, is arranged. This first position 20th is seen in the direction of rotation after the separation point 22nd of the tape 11 from the casting wheel 12th arranged. Thus, after the removal of the tape 11 from the outside surface 13th the outer surface 13th with the jet having solid particles 18th processed before the melt 14th again this area of the outer surface 13th meets.

gilt. Die Schmelze kann ferner bis zu 1 Atom-% an Verunreinigungen enthalten.The melt 14th and thus the tape 11 can have different compositions. In one embodiment, the melt exists 14th Fe _100-abwxyz T _a M _b S _iw B _x P _y C _z (in atom _-.%), where T represents one or more elements of the group consisting of Co, Ni, Cu, Cr and V, M, one or denotes several of the elements of the group consisting of Nb, Mo and Ta, and $$\begin{array}{ccccc}\text{0}& \le & \text{a}& \le & 70\\ 0& \le & \text{b}& \le & 9\\ 0& \le & \text{w}& \le & \mathrm{18th}\\ 5& \le & \text{x}& \le & \mathrm{20th}\\ 0& \le & \text{y}& \le & \mathrm{7th}\\ 0& \le & \text{z}& \le & 2\end{array}$$

is applicable. The melt can also contain up to 1 atom% of impurities.

In one embodiment, the means 17th for directing a jet comprising solid particles 18th to the outer surface 13th of the casting wheel 12th a nozzle system 23 on. The nozzle system can have one or more nozzles. The width of the nozzle system 23 can be adapted to the width of the metal strip to be produced 11 adjusted so that the complete casting track with the beam 18th is covered. The nozzle system 23 but can also in the axial direction over the casting wheel 12th be moved in order to drive with a punctual spray jet over the casting track in order to process the entire casting track in this way. The nozzle system 23 can be one or more rays 18th produce. The particles 19th can also be accelerated to the beam using a carrier gas 18th to build.

The attachment 10 can also use a suction system 25th to remove the particles 19th as well as from the outer surface 13th of the casting wheel have detached material to prevent the particles 19th or the detached material again on the outer surface 13th lands and melts 14th will be carried. For example, means for suction head blasting or injector blasting with blasting medium return can be used as a nozzle system 23 be used.

2 shows an example of a nozzle system 23 for vacuum and suction head blasting, which has several nozzles 24 having. These nozzles 24 can rotate and be venturi nozzles. The particles 19th are in the form of several rays 18th on the surface 13th with the help of a carrier gas, for example air, accelerates what is indicated by the arrow 26th is shown, and after blasting or hitting the surface is caught again by vacuum, as with the arrows 27 will be shown. The particles 19th can be re-circulated. With this nozzle system the spatial distribution of the particles 19th after hitting the surface 13th limited.

3 shows a photograph of a surface of a metal strip that has been solidified on a surface processed with a jet comprising solid particles. The surface has a structure that is laterally isotropic and is therefore independent of the direction of rotation of the casting wheel and thus independent of the orientation of the strip, for example the longitudinal direction and transverse direction of the strip.

In some exemplary embodiments, the system has 10 furthermore one or more additional surface treatment agents 28 on. 4th shows an embodiment in which the further surface processing means 28 a brush 29 having. Rotating metal brushes can be used to remove residues that would impair wetting on the casting wheel 12th to remove.

In the 4th is also a winder 31 shown for continuously picking up the solidified metal strip.

The additional surface treatment agent 28 is in a third position 30th of the casting wheel 12th arranged, this third position 30th in the direction of rotation 16 seen after the first position 20th at which the beam 18th with solid particles 19th the outer surface 13th meets, is arranged, and in front of the second position 21 at which the melt is poured onto the outer surface. Particles and residues can be removed with the brush 29 can be removed and only then does the melt 14th again to the outer surface 13th poured.

In other exemplary embodiments, the further surface processing means can 28 have a jet comprising CO _{2 , the CO 2 being} at least partially in the solid state. Particles from the casting track as well as adhering oils and other wetting-impairing layers on the casting track can be removed, the residue of the CO ₂ particles, the CO ₂ gas produced by sublimation, even having an advantageous effect in the production of many amorphous alloys.

The outside surface 13th of the casting wheel 12th can be processed or cleaned _{with CO 2 snow blasting.} With CO ₂ snow blasting, liquid CO ₂ from pressure bottles is applied to the surface to be treated via a nozzle system 13th sprayed. The expansion of the pressurized, liquid CO ₂ creates small, finely distributed ice crystals or CO ₂ snow, which hit the surface with high kinetic energy 13th hits. A second nozzle system for the _{jet containing CO 2} can be provided, which can consist of single-substance nozzles (only CO ₂ ) or two-substance nozzles (ie with the assistance of compressed air). The CO ₂ particles in the jet sublime before and after the jet hits the outer surface of the casting wheel, leaving the residues and other particles on the outer surface 13th carried along and by the outer surface of the casting wheel 13th removed.

Through the sublimation of the CO ₂ crystals of the snow on the surface of the casting wheel 13th a CO ₂ -containing atmosphere is created in front of the melt drop, which is very advantageous for wetting iron-containing metal melts and for reducing the air pocket size on the underside of the strip. This will make the surface 13th the casting track is also cooled directly, which is advantageous for the rapid solidification process of the molten metal 14th on the casting wheel 12th is.

Residues and particles can be removed by the jet with solid CO ₂ due to the effect of impulse transmission, the creation of mechanical stresses due to the sudden temperature difference, a solvent effect caused by the change in the state of aggregation when it hits the surface, and sublimation impulse rinsing caused by the large increase in volume, for example a 600 to 800-fold increase in volume, takes place during sublimation.

An exhaust system for removing CO ₂ gas can also be provided. This ensures that the atmosphere in the vicinity of the system complies with environmental and occupational health and safety regulations.

During casting, the surface of the casting wheel is subject to very high mechanical and physical loads. For example, the local application of very hot, metallic melt (approx. 900 ... 1500 ° C) in the areas close to the surface leads to high temperature peaks and extreme temperature gradients. During the further cooling, the tape shrinks both in the longitudinal and in the transverse direction. In this way, high shear stresses arise between the tape and the heat sink surface and relative movements occur and at the detachment point the tape tears spontaneously or forcibly from the surface.

These processes are repeated many thousands to tens of thousands of times in a casting process and thus constantly change the surface of the casting wheel. As a result of thermal and mechanical stresses, signs of wear and tear such as material fatigue, surface roughness and material breakouts arise, which in turn can have negative repercussions on the rapidly solidified strip to be produced.

The efficiency of this manufacturing process therefore depends very much on mastering and avoiding the wear processes as far as possible. Much can be done in advance by a suitable selection of the material, the manufacturing process and the surface treatment to reduce the occurrence of these undesirable side effects, but it has so far not been possible to completely avoid them with these measures alone. According to the invention, the outer surface of the casting wheel is thus processed and reshaped by means of a jet containing solid particles.

In the rapid solidification technology (melt-spinning) required for the production of amorphous strips, a glass-forming metal alloy is melted in a crucible, which typically consists essentially of oxide ceramic (e.g. aluminum oxide) and / or graphite. The melting process can, depending on the reactivity of the melt, take place under air, vacuum or a protective gas such as argon. After the alloy has melted down to temperatures well above the liquidus point, the melt is transported to a pouring table and injected through a pouring nozzle, which usually has a slot-shaped outlet opening, onto a rotating wheel made of a copper alloy. For this purpose, the casting nozzle is brought very close to the surface of the rotating copper roller and has a distance of about 50-500 µm from it during the casting process. The melt, which passes the nozzle outlet and hits the moving copper surface, solidifies there with cooling speeds of around 10 ⁴ K / min to 10 ⁶ K / s. By the rotation of the roller the solidified melt is transported away as a continuous strip of tape, detached from the cooling roller, ie from the surface of the casting wheel, and wound onto a winding device as a continuous strip of tape. The maximum possible length of the strip is usually limited by the capacity of the crucible, which can be between a few kilograms and several tons, depending on the size of the system. In parallel operation with several crucibles, a quasi-continuous melt supply to the casting table can even be implemented. Plant sizes on which commercially available amorphous ribbons are manufactured economically typically have crucible sizes of several 100 kg. With the alloy VITROPERM 500 with a ribbon cross-section of around 100 mm width and 0.018 mm thickness, approx. 100 kg results in a ribbon length of around 8 km. In an industrial process, tens of kilometers are produced from one crucible filling, and if the casting process is designed as a continuous casting process via the regular filling of a pouring table, even significantly more kilometers.

The wear and tear of the casting wheel surface during the uninterrupted casting process leads to an increasing roughness of the wheel surface, which leads to the creation of cavities or structures that transport air or process gas under the melt droplets and thus larger air or gas bubbles in the contact area between the melt droplet and the casting wheel to lead. When the melt solidifies, these gas bubbles are frozen in the amorphous strip (air or gas pockets) and can lead to hole-like defects, especially in the case of thin strips. On the other hand, this roughness of the surface of the casting wheel is also expressed through to the surface of the strip produced on it, which means that the strips produced thereon also have an increased roughness.

In order to minimize wear on the casting wheel, it would be desirable to select a casting wheel material with a high strength. In the case of the commonly used fused-metallurgical copper materials, however, the properties of strength and thermal conductivity are usually in opposite directions. A copper material with the highest possible thermal conductivity always has a lower strength than higher alloyed copper materials. The higher alloyed copper materials usually have a higher strength, which, however, is associated with a lower thermal conductivity. To manufacture amorphous metal strips, however, it is necessary to use casting wheel materials with relatively high thermal conductivity in order to achieve sufficiently high cooling rates during strip manufacture. If the cooling rates are not sufficiently high, the strips become brittle or partially brittle, form undesirable crystalline structures, e.g. a proportion of surface crystallinity, and then cannot be continuously wound up in the casting process or tear off during winding, which leads to undesirably low productivity in the Ribbon manufacturing leads. It is therefore desirable to use casting wheel materials that have a thermal conductivity of more than 200 W / mK. Such materials, however, have a hardness of less than 250 HV (HV30).

In order to be able to use these relatively soft and highly thermally conductive materials permanently in the casting process of amorphous strips, it is necessary to ensure uniform processing of the contact surface between the melt / strip and the casting wheel, i.e. the casting track on the casting wheel surface, even during strip production and the roughness of the casting wheel surface constant and evenly kept at a low level.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 3089175 B1 [0003]
• US 6749700 B2 [0003]
• US 9700937 B1 [0003]

Claims (45)

A method of making a tape with rapid solidification technology comprising: Pouring a melt onto a moving outer surface of a rotating casting wheel, wherein the melt solidifies on the outer surface and a ribbon is formed, Directing a jet at the moving outer surface and machining the outer surface of the casting wheel with the jet, the jet comprising solid particles. Procedure according to Claim 1 wherein the jet hits the outer surface of the casting wheel while the melt is poured onto the outer surface of the rotating casting wheel. Procedure according to Claim 1 or Claim 2 , whereby the outer surface of the casting wheel is reshaped by the jet Procedure according to Claim 3 wherein a rate of removal of the material of the casting wheel during the deformation of the outer surface is less than 10 μm / min, preferably less than 5 μm / min, preferably less than 1 μm / min. Method according to one of the preceding claims, wherein the surface roughness of the outer surface of the casting wheel is changed by the jet. Method according to one of the preceding claims, wherein the beam creates a laterally isotropic surface structure in the outer surface of the casting wheel. Method according to one of the preceding claims, wherein a speed of the jet and / or a mass flow rate of the jet is adjusted in order to adjust the surface roughness of the outer surface of the casting wheel. Method according to one of the preceding claims, wherein the particles are metallic, ceramic, inorganic or organic. Method according to one of the preceding claims, wherein the particles have a particle size of 10 µm to 10 mm, preferably 10 µm to 500 µm. Method according to one of the preceding claims, wherein the particles are spherical, oblong or angular. Method according to one of the preceding claims, wherein the particles are accelerated to the outer surface with a carrier gas. Method according to one of the Claim 11 , the pressure of the carrier gas being adjustable. Method according to one of the preceding claims, wherein the particles are sucked off after hitting the outer surface of the casting wheel. Method according to one of the preceding claims, wherein the jet is directed onto the outer surface of the casting wheel by means of compressed air jets or suction head jets or injector jets with blasting medium return. Method according to one of the preceding claims, further comprising one or more jet nozzles, through which the jet or jets are directed to the outer surface of the casting wheel. Procedure according to Claim 15 , wherein a distance between the jet nozzles and the outer surface of the casting wheel is adjustable so that the intensity with which the jet hits the outer surface of the casting wheel is adjustable. Method according to one of the preceding claims, wherein the casting wheel moves in a direction of rotation and the jet hits the outer surface of the casting wheel at a first position which, viewed in the direction of rotation, is arranged in front of a second position at which the melt meets the outer surface, this being arranged The first position is arranged after the point of separation of the strip from the casting wheel, viewed in the direction of rotation. Procedure according to Claim 17 , wherein the outer surface is further cleaned, reshaped or abraded at a third position with a surface processing agent, this third position, viewed in the direction of rotation, being arranged after the first position at which the gas-containing jet hits the outer surface of the casting wheel, but viewed in the direction of rotation before the second position where the melt hits the outer surface of the casting wheel. Procedure according to Claim 18 wherein the surface treatment agent is one or more brushes which are pressed onto the outer surface of the casting wheel while the casting wheel is rotating and / or a compressed air _{jet and / or a jet comprising CO 2} , the CO ₂ at least partially in a solid state hits the moving outer surface of the casting wheel. Procedure according to Claim 18 or Claim 19 , wherein the surface _{processing agent is a jet comprising CO 2} , the CO ₂ at least partially in the solid state striking the moving outer surface of the casting wheel, and a CO ₂ - Source of liquid CO _{2 is} provided, from which particles crystallize to form a CO ₂ snow, which hits the outer surface of the casting wheel as a jet containing _{gas and CO 2 snow.} Procedure according to Claim 20 , the particles of CO ₂ snow having an average particle size of 0.1 µm to 100 µm. Procedure according to Claim 20 or Claim 21 , the particles of CO ₂ snow being accelerated onto the outer surface of the casting wheel _{in the CO 2} gas flow without additional carrier gas. Method according to one of the Claims 20 until 22nd the particles of CO ₂ snow being accelerated onto the outer surface of the casting wheel with a carrier gas. Procedure according to Claim 23 , the pressure of the carrier gas being adjustable. Method according to one of the preceding claims, wherein the melt consists of F2 _100-abwxyz T _a M _b Si _w B _x P _y C _z (in atomic%), where T is one or more of the elements of the group consisting of Co, Ni , Cu, Cr and V denotes, M denotes one or more of the elements of the group consisting of Nb, Mo and Ta, and $$\begin{array}{ccccc}\text{0}& \le & \text{a}& \le & 70\\ 0& \le & \text{b}& \le & 9\\ 0& \le & \text{w}& \le & \mathrm{18th}\\ 5& \le & \text{x}& \le & \mathrm{20th}\\ 0& \le & \text{y}& \le & \mathrm{7th}\\ 0& \le & \text{z}& \le & 2\end{array}$$

Applies, and the melt can contain up to 1 atom% of impurities. Plant for producing a metal strip with rapid solidification technology, comprising: a rotating casting wheel with an outer surface onto which a melt is poured, the melt solidifying on the outer surface and forming a metal strip, Means for directing a jet comprising solid particles at the outer surface of the casting wheel in order to process the outer surface of the casting wheel with the jet. Plant after Claim 26 which further comprises a nozzle system for forming the jet. Plant after Claim 27 , wherein the nozzle system has a single-fluid nozzle or a two-fluid nozzle. Plant after Claim 28 , wherein the nozzle system can also be connected to a carrier gas source, with the aid of which the solid particles are accelerated onto the outer surface of the casting wheel. Plant according to one of the Claims 26 until 29 which further comprises a suction system for removing the solid particles and the material detached from the outer surface of the casting wheel. Plant according to one of the Claims 26 until 30th , wherein the casting wheel is movable in a direction of rotation and the means is designed such that the jet hits the outer surface of the casting wheel at a first position which, viewed in the direction of rotation, is arranged in front of a second position at which the melt hits the outer surface of the casting wheel . Plant according to one of the Claims 26 until 31 which further comprises surface processing means for processing the outer surface at a third position of the casting wheel, this third position, viewed in the direction of rotation, being arranged after the first position at which the beam hits the outer surface, but, viewed in the direction of rotation, before the second position at which the melt hits the outer surface of the casting wheel. Plant after Claim 31 , wherein the surface treatment means are one or more brushes which are pressed onto the outer surface of the rotating casting wheel while the casting wheel outer surface is moving, and / or means for directing a _{jet comprising CO 2} at the outer surface of the casting wheel, the jet being CO ₂ which at least partially in the solid state hits the moving outer surface of the casting wheel in order to process and / or clean the outer surface of the casting wheel with the jet. Plant after Claim 33 which further comprises a further nozzle system for forming the jet comprising _{CO 2.} Plant after Claim 33 or 34 Wherein CO ₂ is provided as the liquid CO ₂ and the nozzle system having a nozzle system for liquid CO _2. Plant according to one of the Claims 26 until 35 which further comprises a winder for continuously taking up the solidified tape. Plant according to one of the Claims 26 until 36 which further comprises a casting nozzle for a melt made of an alloy, from which the melt can be poured onto the outer surface of the casting wheel. Use of the system after one of the Claims 25 until 36 for the production of a metallic strip which consists of Fe _100-abwxyz T _a M _b Si _w B _x P _y C _z (in atomic%) and up to 1 atomic% of impurities, where T is one or more of the elements of the Group consisting of Co, Ni, Cu, Cr and V denotes, M denotes one or more of the elements of the group consisting of Nb, Mo and Ta, and $$\begin{array}{ccccc}\text{0}& \le & \text{a}& \le & 70\\ 0& \le & \text{b}& \le & 9\\ 0& \le & \text{w}& \le & \mathrm{18th}\\ 5& \le & \text{x}& \le & \mathrm{20th}\\ 0& \le & \text{y}& \le & \mathrm{7th}\\ 0& \le & \text{z}& \le & 2\end{array}$$

is applicable. Metallic tape consisting of Fe _100-abwxyz T _a M _b Si _w B _x P _y C _z (in atom%) and up to 1 atom% of impurities, where T is one or more of the elements of the group consisting of Co, Ni, Cu, Cr and V denotes, M denotes one or more of the elements of the group consisting of Nb, Mo and Ta, and $$\begin{array}{ccccc}\text{0}& \le & \text{a}& \le & 70\\ 0& \le & \text{b}& \le & 9\\ 0& \le & \text{w}& \le & \mathrm{18th}\\ 5& \le & \text{x}& \le & \mathrm{20th}\\ 0& \le & \text{y}& \le & \mathrm{7th}\\ 0& \le & \text{z}& \le & 2\end{array}$$

applies, with at least one surface with an average surface roughness R _a between 0.05 µm and 1.5 µm. Metallic tape after Claim 39 , wherein at least one surface has an average surface roughness R _a between 0.05 µm and 1.5 µm. Metallic tape after Claim 39 or Claim 40 wherein the metallic tape is ductile and amorphous or is nanocrystalline. Metallic tape according to one of the Claims 39 until 41 , which has a width of 2 mm up to 300 mm, a thickness of less than 50 µm, and a maximum of 50 holes per square meter. Metallic tape after Claim 42 , which has a width of 20 mm to 200 mm, and / or a thickness between 10 µm and 18 µm, and / or less than 25 holes per square meter, preferably less than 10 holes per square meter. Metallic tape according to one of the Claims 39 until 43 , which has a casting wheel side that has been solidified on an outer surface of a casting wheel, an opposite air side and a structure that is at least 80 percent by volume amorphous, or that has at least 80 percent by volume of nanocrystalline grains and amorphous residual matrix, of which at least 80 percent are the nanocrystalline grains show an average grain size of less than 50 nm and a random orientation, the air side and / or the casting wheel side having a surface crystallization proportion of less than 23%. Metallic tape after Claim 44 , the air side and / or the casting wheel side having a surface crystallization fraction of less than 5%.

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