WO2020254481A1

WO2020254481A1 - Melt receptacle for melting, keeping warm and transporting molten materials, and method for producing a melt receptacle

Info

Publication number: WO2020254481A1
Application number: PCT/EP2020/066916
Authority: WO
Inventors: Philipp Kolbe; Thomas Wamser; Lukas ZULAUF; Andreas Lauer
Original assignee: Schunk Kohlenstofftechnik Gmbh
Priority date: 2019-06-21
Filing date: 2020-06-18
Publication date: 2020-12-24
Also published as: EP3987239A1; DE102019116847A1

Abstract

The invention relates to a melt receptacle (10, 12, 14, 16, 18) for melting and/or keeping warm and/or transporting a molten material. The melt receptacle is an open body made from a fibre-reinforced, oxide-ceramic composite material having an effective porosity of 20 to 40%.

Description

description

Melt pick-up for melting, holding and transporting melts as well as a method for producing a melt pick-up

The invention relates to a melt receiver, in particular crucible, for melting and / or keeping warm and / or transporting a melt, in particular metal, in particular non-ferrous metal, or its melt, in particular aluminum or an aluminum alloy or its or their melt.

The invention relates in particular to melting crucibles which are suitable for melting, in particular metal melts, in particular non-ferrous metal melts, preferably aluminum melts, which are used in melting, holding or transport units.

According to the state of the art, the crucibles are generally designed as open, conical elliptoidal or spherical bodies that can have diameters of 100 mm and 1000 mm and heights of up to 1000 mm. Furthermore, a spout can be provided in the upper edge area.

Corresponding crucibles can be used for melting, keeping warm or transporting liquid melts, in particular non-ferrous metal melts, with quantities between 0.5 kg and 300 kg being able to be taken up by the corresponding melting crucibles.

The melting process includes the following steps. Solid materials are added to the crucible in powder form, in ingot form or as granules, which should result in the desired alloy composition. The crucible is then placed in a Melting unit retracted unless the crucible is already in a corresponding melting unit when it is filled with the material. Melting can be carried out in an induction-heated furnace, among other things.

Depending on the materials used, these are melted down to a specified temperature and a specified process duration.

After melting, the melt is kept warm in the crucible in the liquid state for further processing. The melt is then transported in the crucible for further processing, e.g. to be poured into a mold.

As an alternative or in addition to the casting, a damage-free solidification process can take place for the melted material or parts of it in the crucible, either intentionally or unintentionally. After the melt has been removed or after the solidified material has been removed, the crucible can be used again for the previously explained process steps.

A large number of crucibles are in industrial use, depending on the type of metal to be melted and the type of heating. Different materials and types of construction are used. The materials used are clay-graphite crucibles, SiC crucibles or special melting crucibles, to name just a few.

Crucibles can be designed with or without a spout.

Regardless of the material or the shape, the crucibles according to the prior art have in common that they are made of solid ceramic with a large wall thickness.

The disadvantage of the known crucibles is that a chemical reaction can take place between the crucible material and the melt or melt alloy, especially when it is an aluminum melt. Material that has solidified and stuck in the crucible must be knocked off manually. This gradually leads to wear and tear and destruction of the crucible.

In order to reduce wear, especially with special alloys, it may be necessary to finish the crucible before the melting cycle.

Furthermore, different crucible materials are required for different alloy compositions.

Another disadvantage is that the crucible material becomes brittle after several melting cycles, which means that there is a risk of total failure. Plant safety is also reduced.

Known crucible materials also show a low thermal shock resistance due to the high wall thickness, the adherence of solidified material and the changing melt pool levels. This results in a high thermal gradient along the axis and along the wall thickness.

The melt can be contaminated by detached crucible material (low density inclusions, LDI inclusions). Solidification residues reduce the melting and casting quality.

It should also be mentioned that due to the massive construction of the crucible, heat is withdrawn from the melt, so that a higher energy input is required for compensation. The time required for melting is therefore longer.

In the case of crucibles containing graphite, inconsistent thermal and electrical properties are a problem. The reason for this is that the burn-off of graphite leads to a change in properties and thus makes reproducibility more difficult.

The subject of DE 10 2017 128 546 A1 is a refractory container for the heat treatment of workpieces, which container can have openings through which fluid can flow. The container is made of a fiber-reinforced oxide-ceramic composite material. AT 247533 relates to a container for holding molten metal. The container can consist of a dispersion material with finely divided particulate metallic oxide-ceramic components in the areas that are exposed to particular attack.

DE 20 2012 010 696 U1 discloses a component in contact with the melt made of a ceramic composite material. Si ₃ N ₄ and ZrO ₂ are mixed and then subjected to shaping.

The present invention is based on the object of developing a melt pick-up and a method for producing such a system in such a way that melting, holding and transporting liquid melts, preferably metal melts, preferably non-ferrous metal melts, in particular aluminum or aluminum alloy melts, without the formation of Melt artifacts and contamination of the melt is possible.

The process security should be increased. Compared to aluminum melts in particular, there should also be advantages with regard to wetting and corrosion properties. Finishing should be unnecessary. Compared to known crucibles, the service life should be increased and it should be possible to process it in an energetically favorable manner. A low thermal conductivity should be achieved.

To achieve the object, the invention essentially provides that the

Melt absorption an open body made of a fiber-reinforced oxide-ceramic composite material with an open porosity of 20% to 40%, optionally up to 45%, consists or contains this.

In particular, it is provided that the composite material contains oxide-ceramic fibers, preferably formed from at least one material from the group Al ₂ O ₃ , SiO ₂ , ZrO ₂ , Y ₂ O ₃ , TiO ₂ , CaO, MgO, Y ₂ O ₃ stabilized ZrO ₂ .

Furthermore, the invention is characterized in that the composite material contains an oxide-ceramic matrix, preferably formed from at least one material AI ₂ O ₃ , SiO ₂ , ZrO ₂ , Y ₂ O ₃ , TiO ₂ , CaO, MgO, ZrO ₂ (tetragonally stabilized, partially stabilized and fully stabilized)

It is preferably provided that the matrix and the fibers consist of the same oxide-ceramic material or the same oxide-ceramic materials or contain this or these.

Particularly good properties are obtained when the metal of the composite material and that of the metal of the melt or of the metal of the main component of the metal alloy of the melt are the same.

Due to the ceramic fiber reinforcement according to the invention and the porous ceramic matrix, a considerable increase in strength and ductility (damage tolerance) can be achieved, which is significantly higher than that of unreinforced monolithic ceramics or clay graphites. This leads to a quasi ductile material behavior, whereby brittle fracture is avoided and impacts or similar mechanical loads can be classified as uncritical.

The open porosity between 20% and 40%, possibly up to 45%, in particular between 27% and 32%, provides a melt absorption which has a low thermal conductivity of in particular less than 10 W / mK.

It should also be emphasized that the composite material has excellent thermal shock resistance and resistance to high-temperature fatigue, which is sufficient for use in particular for cast aluminum. Brittle fracture and material fatigue are prevented. At the same time, process reliability is increased. Lower heating times are also made possible.

The inherent material composition of fibers and matrix, for example made of aluminum oxide, leads in connection with aluminum melts and its alloys to a prevention of corrosion of the material of the melting crucible and also shows a favorable wetting behavior. In this context it is particularly advantageous if matrix additives or additives made of zirconium oxide or Y ₂ O ₃ -reinforced ZrO ₂ are present. It is particularly provided that the proportion of ZrO ₂ or Y ₂ O ₃ reinforced ZrO _{2 is} between 5% by weight and 30% by weight, in particular between 12% by weight and 25% by weight, of the total amount of the ceramic metal oxide.

Due to the favorable wetting behavior, the flow behavior of the melt is improved, which ensures a higher output during casting or, among other things, solidification in the crucible is made possible. Continuous melting / solidification processes in the crucible do not damage the material.

The good wetting behavior reduces wear. The cleaning effort due to adherence that is difficult to remove and the resulting damage is minimized.

It should be particularly emphasized that the material composition does not lead to any contamination of the melt by loosened ceramic compounds / particles or solidification residues, so that an improvement in the casting quality can be achieved compared to the prior art. Aggressive aluminum alloys such as those containing alkali do not lead to any change in the crucible due to the material composition of the crucible, i.e. no changes in mass or structure occur. This in turn means that wear can be reduced and the service life can be increased considerably.

It is also not necessary that different crucibles have to be used for different alloy compositions.

In particular, it is provided that the matrix and the fibers consist of Al ₂ O ₃ or contain them as the main component.

With regard to the oxide-ceramic fibers, it should be noted that the density r of the fibers should be 2 g / cm ³ <r <6 g / cm ³ , in particular 2.5 g / cm ³ <r <3.2 g / cm ³ , and / or the fiber diameter should be 5 mm to 20 mm, in particular 10 mm to 12 mm. The open porosity of the composite is in particular in the range between 27% and 32%.

The melt receptacle itself can have a wall thickness between 1 mm and 20 mm, in particular between 1 mm and 4 mm.

With regard to the geometrical designs, there are basically no limits. In particular, conical, elliptoidal or spherical geometries with or without a spout can be selected.

There is also the possibility that the melt receptacle is designed as an insert in a metallic support structure.

Further components of the melting unit itself can be made from the same oxide-ceramic material.

Due to the thin walls of the melt receptacle and its open porosity, the melt can be heated up within a short period of time. The main reason for this is a reduced heat extraction. The heating can be done by conventional heating elements or preferably by inductive heating. A selectable smaller coil distance to the material to be melted with inductive heating leads to an increase in inductivity.

Since the construction of the overall unit is compact, a problem-free process is possible.

The melt volume per melt holder can be reduced by using several smaller-volume melt holders.

The melt absorption can be produced by means of winding technology or on the basis of textile fiber semi-finished products such as fabrics, braids, scrims. An additional coating is possible. A coating can die

Increase corrosion resistance or hardness. The permeability for gases can also be reduced.

It should also be emphasized that the fiber reinforcement can be designed to suit the load, i.e. that in areas subject to special loads, e.g. in the floor area or in the transition area between floor and peripheral wall, are exposed, thickening of the fiber reinforcement can be made.

There is no geometrical restriction due to the manufacturing process, another advantage over monolithic ceramics.

Ribbed elements or stiffeners are possible.

In particular, it is provided that a corresponding melt absorption is determined in order to process melts, in particular metal melts, preferably non-ferrous metal melts, which are composed of at least one element from the group Al, Si, Mg, Cu, Zn, Sn, Ti, Na, Sr, B consists or contains this, in particular aluminum melts or aluminum alloy melts are to be mentioned.

The lightweight construction associated with the oxide-ceramic fiber reinforcement results in improved heat and temperature insulation properties. The extreme reduction in wall thickness compared to the prior art should be emphasized. In particular, this also results in an energy saving.

The small wall thickness in particular has the advantage that the distance between an induction coil and the alloy material to be melted is reduced, so that significantly shorter melting times can be achieved compared to the prior art.

As mentioned, a high degree of geometric design freedom is given, so that any complex geometries can be produced, if necessary with undercuts. A process-desired adaptation of the geometry can take place, so that the melting is improved.

Due to the oxide ceramic material, there is the possibility of larger volume

Making enamel receptacles than with monolithic ceramic crucibles.

The thin wall thickness enables the melt to be tempered by heating and cooling elements when the melt is transported.

There is also the possibility of integrating sieve elements or filters in the area of the spout to enable the melt to be cleaned. The flow-free melt flow can be improved by using flow aids.

A connection technology and assembly or disassembly, as well as simple cleaning, which are simple compared to the prior art, are possible.

Due to the material used and the advantages resulting therefrom, new processing possibilities arise in the processing of melts, in particular aluminum melts. A portioned melting matched to cycle times with in-line processing of cast parts from melting through to casting through the use of the invention

Enamel absorption is possible.

The compact design of the melt receptacle enables several melt receptacles to be passed through a heating zone one after the other or the heating units can be moved over the melt receptacles, i.e. Crucible are moved. In the case of small melt absorption dimensions, changes in the melt quality can be reacted to extremely quickly, the process can be started up or interrupted quickly, and the parts to be manufactured can be melted in line with requirements.

The thermo-mechanical properties of the material are to be emphasized, ie high strength and damage tolerance. Brittle fracture does not occur, so that there is more security in the process. There is thermal shock resistance and dimensional stability against thermal cycles. There is good thermal insulation from the melt, ie temperature losses during melting, holding and transport are avoided, so that processing can be carried out in an energetically favorable manner. A continuous melting and solidification of the melts with no damage to the melt absorption is given.

The good chemical properties of the composite material should be emphasized, with particular mentioning of its resistance to aggressive aluminum melts.

This increases the flexibility when using different alloy compositions. The wetting behavior is favorable, so that easy cleaning is made possible and less wear occurs. Oxidation and corrosion are avoided. Finishing is generally not required. The melt is not contaminated and this results in a higher quality cast part. A continuous melting and solidification of the melts without damage to the melt absorption is possible.

Finishing is e.g. understood the application of slips to the crucible surface before the melt is enveloped. The application of the size must be repeated at regular intervals, since the size is removed during processing and does not adhere permanently.

With regard to process-relevant parameters, it should be noted that compared to the state of the art, a reduced use of energy is made possible. Furthermore, constant thermal and electrical properties are ensured. The possibility of introducing a new type of processing arises as "proportioned melting", i.e. In-line melting process or production and thus substitution of energy and system-intensive holding furnaces.

The geometric freedom of design has the particular advantage that the

Melt receptacle has integral means in its peripheral wall, such as at least one depression or at least one projection for interacting with a handle, such as gripping tongs. There is also the possibility that the circumferential wall has a plurality of adjoining areas, preferably areas arranged one above the other when viewed with respect to the height of the melt receptacle, which have angles that differ from one another with respect to the longitudinal axis of the melt receptacle.

The invention is also characterized by a method for producing a

Melt absorption, such as crucible, for melting and / or keeping warm and / or transporting metal, in particular non-ferrous metal, or its melt, comprising the process steps:

- Impregnation of an arrangement of oxide-ceramic fibers with a slip containing oxide-ceramic particles,

- Winding or laying the impregnated arrangement of the fibers on a tool that depicts the interior geometry of the device,

Drying of the arrangement laid or wound on the tool.

The arrangement is then demolded or partially demolded and sintered. If necessary, the device produced in this way is reworked.

In this case, one or more impregnated continuous fiber bundles or impregnated flat structures, in particular fiber fabrics, woven fabrics or braids, are used as the arrangement.

In particular, it is provided that the drying process for forming a green body from the arrangement is carried out in a temperature range between 40 ° C. and 250 ° C., in particular between 80 ° C. and 150 ° C.

After drying, sintering takes place, in particular at a temperature between 1000 ° C and 1300 ° C, preferably between 1150 ° C and 1250 ° C.

In particular, the invention is also characterized by the use of a

Melt absorption, such as crucibles, for melting and / or keeping warm and / or Transporting metal or its melt with one or more of the previously explained features of the melt absorption.

Further details, advantages and features of the invention emerge not only from the claims, the features to be taken from them - individually and / or in combination, but also from the following description of preferred exemplary embodiments to be taken from the drawing and their explanations.

Show it:

1 shows the principle of crucibles and FIG. 2 shows the principle of a winding process.

In Fig. 1 different embodiments of melting crucibles 10, 12, 14, 16, 18 to be designated as S chmelzaufhahmen are shown, with which metals such as non-ferrous metals or alloys of these are to be melted, kept warm and transported.

If non-ferrous metal is used, this is not intended to be a restriction.

The geometry of the melting bodies 10, 12, 14, 16, 18 can be designed in such a way that the melting behavior of the metals is influenced.

Melting crucibles 10, 12, 14, 16, 18 consist of an open body which, for example, can have a conical, rotationally elliptoidal or spherical geometry. Areas, in particular the peripheral wall of the crucible, can also include different angles of inclination with respect to the longitudinal axis.

In particular, it can be seen in the case of the crucible 12 that the base area 20, which can be exposed to particular loads, is reinforced in a manner appropriate to the load. There is also the possibility of integrally forming a circumferential recess 22 in order to be able to securely grasp the crucible 16 by a handle such as gripping tongs.

In the interior, structures such as ribs 24, 26 can be provided in order to e.g. B. to influence the pouring behavior of the melt or the material stiffness of the melt absorption.

Furthermore, extensions 28 can be provided at the edge, which serve as a pouring aid.

The respective crucible 10, 12, 14, 16, 18 is preferably produced using the winding technique, although prepregs, which can be placed on a tool that reproduces the inner geometry of the crucible 10, 12, 14, 16, 18, or a combination are also used can.

If the winding technique is used, a winding core is used whose external geometry should correspond to that of one or two crucibles. In the case of the latter, these should merge into one another in their respective opening area, consequently two crucibles are wound opposite one another in one process.

Fiber bundles are wound on the winding core, with the individual fiber diameters between 5 mm and 20 mm, in particular in the range between 10 mm and 12 mm. The density should be in the range between 2 g / cm ³ to 6 g / cm.

Before being wound onto the winding core, the fiber bundles are passed through a slip and thus impregnated. The slip contains the ceramic particles that form the matrix of the composite body.

The proportion of ceramic particles can be 10% by volume to 50% by volume, in particular 20% by volume to 40% by volume, based on the total volume of the slip.

In particular, a water-based slip is used with preferably organic additives, for example polyols, polyvinyl alcohols or polyvinylpyrrolidones, dispersion binders, preferably styroacrylate dispersions. The slip can be at least 10% by weight to 20% by weight, preferably at least 24% by weight

Wt%, e.g. B. 21 wt .-% to 35 wt .-%, containing glycerol based on the total weight of the ceramic particles.

A material from the group Al ₂ O ₃ , SiO ₂ , ZrO ₂ , Y ₂ O ₃ , TiO ₂ , CaO, MgO, and ZrO ₂ stabilized with Y ₂ O _{3 are used} as oxide ceramic both for the ceramic particles and for the fibers in question.

If an aluminum melt or an aluminum alloy melt is to be melted, kept warm or transported with the melting crucible, Al ₂ O ₃ should be used as material for the matrix, i.e. consequently the ceramic particles, and for the fibers. The slip can optionally contain additives such as ZrO ₂ , the proportion being between 5% and 30%, in particular between 12% and 25% in% by weight of the total powder amount of the ceramic metal oxide.

A volume fraction of the ceramic particles should be 10 to 40% by volume based on the total volume of the slip.

The corresponding impregnated fiber bundles are then wound onto the winding core, then dried, in particular in the temperature range between 40 ° C and 250 ° C, preferably in the range between 80 ° C and 150 ° C. The body produced in this way is severed and pulled off the winding core. This is followed by sintering in the temperature range between 1,000 ° C and 1,300 ° C, in particular between 1,150 ° C and 1,250 ° C. Possibly. a post-processing is carried out in order to then use the crucible 10 produced in this way.

The drying time depends on the temperature and is between 2 hours and 48 hours, preferably between 12 hours and 24 hours.

The sintering takes place over a temperature / time curve with different holding stages and durations, the holding duration at the maximum temperature should be between 5 min and 24 h, preferably between 1 h and 12 h. On the basis of the winding technology used, the geometry of the crucible 10, 12, 14, 16, 18 can be changed to the desired extent as a function of the geometry of the winding core, as has been explained above.

It is also possible to vary the wall thickness or the

To design end sections of the winding core in such a way that flow aids such as the rib 24, 26 result in the interior.

In particular, it is provided that the fiber volume content of the device / melt receptacle is 30% to 50%, preferably 35% to 42%.

The following is to be added in addition to the winding technique.

In order to produce essentially rotationally symmetrical parts, winding processes are used. The internal geometry of the object is given by the so-called winding core on which the fibers impregnated with the slip are placed.

In the case of the winding core, a distinction is made between reusable, lost, meltable and separable cores. In the present case, the crucibles are removed from the core so that the latter can be used again. Meltable cores are often used for smaller components and separable cores for components with larger diameters.

The winding is usually done with a winding machine that corresponds to that of a CNC lathe. The winding core is clamped at one of its ends to a three-jaw chuck and at the other end z. B. stored a tailstock.

In order to wind rovings, that is to say fiber bundles, which can comprise, for example, 100 or more individual fibers, so-called filaments, on the winding core, these are unwound from a melt receiver. The rovings can then pass deflection rollers, by means of which the tension of the rovings is adjusted via a resistor. The fiber bundle is then passed through a thread eye over further deflection rollers through a slip bath, the composition of which has been described above. After the fibers have been impregnated, they are passed over one or more other pulleys, also determine the spring tension and the number of revolutions, winding speed and length of the used fiber strand, centered by a thread eye and placed on the winding core, which is rotating. The thread tension is also of paramount importance. If this is too low, the fibers are not pressed onto the winding core to a sufficient extent. If the tension is too great, the slip cannot get enough between the individual fiber filaments and the roving can tear.

After the winding process, the wound fiber architecture is tied with tear-off fabric. This serves to develop a uniform surface, to compress it by displacing excess slip and thus to increase the fiber volume content and also to protect the component.

In the circumferential winding, which is also called radial winding, the rovings are laid down in parallel, as can be seen from the horizontal illustration in FIG. In the case of cross-winding, the rovings are laid down from one pole cap, i.e. from one end to the other pole cap, i.e. to the other end, in order to also obtain fiber reinforcement in the x and y directions. The winding angle is measured from the deposited fiber strand against the axis of rotation and influences the melt absorption of axial loads.

If a winding part has purely unidirectional circumferential windings, d. H. the angle a is about 90, the highest tensile strengths can be achieved in tangential orientation. If the lap lies between the load direction and the fiber orientation, e.g. at 5, a drop in strength of 50% occurs. If the winding angle is <45 °, more axial loads are absorbed. With reinforcement in the axial direction, i. H. small winding angles, the problem arises that it is no longer possible to fix the roving at the end of the body.

Various calculation programs are available for the coordination of the type of winding, winding angle, number of layers (fiber requirement).

After the winding process, the wound fiber architecture is tied with a tear-off fabric in order to achieve a uniform surface. This is also followed by compaction by displacement of excess slip and thus an increase in the Fiber volume content and also protects the component. Then the

Drying and the sintering process.

An exemplary embodiment follows: First, oxide-ceramic prepregs are produced. For this purpose, fabrics made of aluminum oxide fibers (> 99% Al ₂ O ₃ ) are impregnated with a water-based slip containing oxide-ceramic particles. The filament diameter is 10-12 mm and the yarn count is 20,000 denier. The slip has a solids content of 30% by volume consisting of 80% Al ₂ O ₃ particles and 20% ZrO ₂ particles. The mean particle size is 1 mm. 2% by weight of polyacrylic acid are added as a dispersant. After the water content of the infiltrated fiber architecture has been reduced, the resulting prepreg can be processed by cutting it to size and placing it on a tool that depicts the inner contour of the crucible. This is followed by drying using autoclave technology, with the application of temperature and excess pressure, so that a green body is obtained. After drying, the crucible made of fabric can be removed from the core. Sintering then takes place at 1200 ° C. Rework can be done by turning, milling or grinding.

Claims

1. Melt pick-up, in particular crucible, for melting and / or keeping warm and / or transporting a melt, in particular metal, in particular non-ferrous metal, or its melt, in particular aluminum or an aluminum alloy or its or its melt,

characterized,

that the enamel receptacle is an open body made of a fiber-reinforced oxide-ceramic composite material with an open porosity of 20% to 40% or contains this.

2. enamel absorption according to claim 1,

characterized,

that the composite material contains oxide-ceramic fibers, preferably formed from at least one material from the group Al ₂ O ₃ , SiO ₂ , ZrO ₂ , Y ₂ O ₃ , TiO ₂ , CaO, MgO, Y ₂ O ₃ stabilized ZrO ₂ .

3. enamel absorption according to claim 1 or 2,

characterized,

that the composite material contains an oxide ceramic matrix, preferably formed from at least one material Al ₂ O ₃ , SiO ₂ , ZrO ₂ , Y ₂ O ₃ , TiO ₂ , CaO, MgO, ZrO ₂ (tetragonal stabilized, partially stabilized and fully stabilized).

4. enamel absorption according to claim 1,

characterized,

that continuous melting and solidification processes in the melt receptacle do not damage the melt receptacle or its material.

5. enamel absorption according to at least one of the preceding claims,

characterized,

that the matrix and the fibers consist of the same oxide-ceramic material or the same oxide-ceramic materials or contain this or these.

6. enamel absorption according to at least one of the preceding claims,

characterized,

that the metal of the composite material and that of the metal or main component of the metal alloy are the same.

7. melt absorption according to at least one of the preceding claims,

characterized,

that the matrix and the fibers consist of Al ₂ O ₃ or contain them as a main component.

8. enamel absorption according to at least one of the preceding claims,

characterized,

that the open porosity of the enamel absorption is between 27% and 32%.

9. melt pick-up according to at least one of the preceding claims,

characterized,

that the density r of the fibers is 2 g / cm ³ <r <6 g / cm ³ , in particular between 2.5 and 3.2 g / cm ³ , and / or the fiber diameter is 5 mm to 20 mm, in particular 10 mm to 12 mm.

10. Melt pick-up according to at least one of the preceding claims, characterized in that

that the enamel receptacle is produced by winding fibers onto a tool that depicts the inner geometry of the enamel receptacle and / or by using textile fabrics, braids, fabrics made from the oxide-ceramic fibers.

11. enamel absorption according to at least one of the preceding claims,

characterized,

that the oxide-ceramic fibers consist of continuous fibers, in particular in the form of continuous fiber bundles, short fibers or a combination of these.

12. enamel absorption according to at least one of the preceding claims,

characterized,

that the body has a conical, rotationally symmetrical, rotationally elliptoidal or spherical geometry or at least in sections such a geometry.

13. enamel absorption according to at least one of the preceding claims,

characterized,

that the melt receptacle is thin-walled and in particular has a wall thickness W _{D of} 1 mm £ W _D £ 20 mm, in particular 1 mm £ W _D £ 4 mm.

14. enamel absorption according to at least one of the preceding claims,

characterized,

that the melt receptacle has a metallic support structure, the melt side with a consisting of the oxide-ceramic composite material and into the

Enamel absorption is provided with its own rigid body.

15. enamel absorption according to at least one of the preceding claims,

characterized,

that the body has load-bearing fiber reinforcements, especially in the bottom area of the body.

16. Melt pick-up according to at least one of the preceding claims, characterized in that

that the body has structures on the inside, such as ribs, in particular designed as flow aids.

17. enamel absorption according to at least one of the preceding claims,

characterized,

that the body has integral means in its peripheral wall, such as at least one depression or at least one projection, for interacting with a handle, such as gripping pliers.

18. enamel absorption according to at least one of the preceding claims,

characterized,

that the circumferential wall of the body has a plurality of adjoining areas, preferably areas which are arranged one above the other when viewed in relation to the height of the body and which enclose angles that differ from one another with respect to the longitudinal axis of the body.

19. A method for producing a melt receiver, such as a crucible, for melting and / or holding warm and / or transporting metal, in particular non-ferrous metal, or its melt, in particular aluminum or an aluminum alloy or its or their melt,

comprehensive the process steps

- Winding or laying the impregnated arrangement of the fibers on a tool that depicts the internal geometry of the melt receptacle,

- drying of the arrangement placed or wound on the tool,

- Demolding or partial demolding of the arrangement and sintering.

20. The method according to claim 19,

characterized,

that the arrangement will be reworked.

21. The method according to claim 19 or 20,

characterized,

that the arrangement of the fibers at a temperature between 40 ° C and 250 ° C, in particular between 80 ° C and 150 ° C, is dried.

22. The method according to any one of claims 19 to 21,

characterized,

that the arrangement of the fibers is sintered at a temperature between 1,000 ° C and 1,300 ° C, in particular between 1,150 ° C and 1,250 ° C.

23. The method according to any one of claims 19 to 22,

characterized,

that the arrangement used is one or more endless fiber bundles or flat fiber structures, in particular fiber scrims, fabrics or braids.

24. Use of a melt receptacle according to at least one of claims 1-18 for melting and / or keeping warm and / or transporting a metal melt, in particular a non-ferrous metal melt.

25. Use according to claim 24,

characterized,

that the metal of the oxide-ceramic composite material and the metal or main component of the molten metal are the same.