DE2412149A1 - PROCESS FOR THE PRODUCTION OF SOLID, THREADY MATERIAL DIRECTLY FROM THE MELT - Google Patents

Description

KDB / RST October 29, 1973

2412H9

BATTELLE DEVELOPMENT CORPORATION COLUMBUS / OHIO (V.St.A.)

Process for the production of solid, thread-like material directly from the melt

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The present invention relates generally to the technical field of the preparation of solid, filamentary products / by moving a continuous chill surface, which communicates with a bath of molten material in contact _r The invention relates particularly to a method for producing such a thread-like material through in Bringing the surface of the melt into contact with a protrusion running over the circumference or with a peripheral protrusion which is part of a rotating, heat-dissipating component.

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In DT-OS 2 225 684 a method for the production of thread-like, solid material directly from a bath with molten Material disclosed. With the help of a rotating, heat-dissipating component that has at least one protrusion on its Periphery possesses a limited, elongated area - namely a part of this bulge - in the surface of the Introduced melt and solidified a thread adhering to the bulge. Furthermore, the rotation of the component leads to a spontaneous one Detachment of the thread from the shaping component, while the protrusion is guided back into the melt during the rotation. the Practicing this method presents at least three difficulties which the present invention solves will.

The first difficulty is that the rotation of the _; heat-dissipating component causes a flow of the atmosphere surrounding the component. The component is moved fastest on the outer surface of the rotating disc, where the solidification of the thread takes place (at least at a speed of more than 0.9 m / sec); this surface can carry a layer of the ambient air into the melt surface, whereby the shaping surface is separated from the melt. Aside from that

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Induction of the perturbation flow caused by the separation is disadvantageous that the atmosphere in general represents an oxidizing agent to the melt and that the flow of such an oxidizing gas into the melt can lead to the reaction of the gas with the shaping surface and the introduction of oxides at the critical point. According to the invention is made by bubbling a stream of non-oxidizing gas into the area between the molten material and the rotating component at the point of entry of the component into the Melt surface improves the known process decisively, because the gas introduction can be carried out in such a way, that the adhering layer of oxidizing gas is destroyed and replaced by non-oxidizing gas. One in the molten one Non-oxidizing gas introduced into the material prevents the formation of oxide at the point where the thread solidification begins.

Second, the regulated introduction of a non-oxidizing Gases to create a barrier that prevents individual solid material particles from settling on the surface of the melt collect where the rotating component could pull such contaminants into the melt and to the place where the

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Thread consolidation begins. The vibratable solids can be in the form of oxides of the molten material or they can consist of an additive introduced into the surface to avoid oxidation on the surface of the melt.

Finally, by switching off oxidizing gas and contaminant particles at the point where the rotating component enters the melt, increases the stability of the separation point of the solid threads from the rotating component and also promotes spontaneous thread separation.

In summary, it should be noted that the present invention includes an improvement of the known method in which nit a rotating, heat-dissipating component, which at least has a peripheral protrusion, thread-like material is formed by contacting the melt surface with this protrusion, so that a thread-like product on the peripheral protrusion is solidified and spontaneously peeled off. the Invention comprises the introduction and supply of a non-oxidizing gas to the point at which the rotating component enters the melt surface. After a pre-

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The preferred embodiment of the invention is also a polishing device present, which acts on the protrusion of the rotating component arranged on the circumference, whereby the detachment of the thread formed on this component is further improved.

Further features, advantages and possible uses of the invention emerge from the following illustration and from the accompanying figures of exemplary embodiments of the invention.

It shows

FIG. 1 shows, in an enlarged illustration, a cross-sectional illustration of the point at which the gas is introduced,

FIG. 2 shows, in cross section, a preferred embodiment of the protrusion on the rotating component in a state-of-the-art design,

Figure 3 is an overall view of an arrangement embodying the invention when used in conjunction with a single peripheral protrusion and with localized initiation of non-oxidizing gas.

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Figure 4 is an overall view of an embodiment embodying the invention, in which the rotating component is partially is enclosed to facilitate the introduction of gas to the surface of the molten material,

FIG. 5 shows an overall view of an embodiment of the invention in which the means for protecting the molten Material from oxidizing gas consists of a solid, which preferably removes oxygen from the system and which also provides protection or shielding for the molten material, and

Figure 6 is a plan view of an embodiment of the invention, at a discontinuous thread is made using a bath for polishing the peripheral protrusion or edge of the rotating component.

Figure 1 explains a variant of the teaching according to DT-OS 2 225 684, according to which a rotating, heat-dissipating component 30 with at least one peripheral protrusion or a projection 31 on the Perimeter old of the surface 11 of a bath of molten material 10 is brought into contact. One narrow edge 32

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the protrusion 31 comes into contact with the melt surface 11. The component 50 can be set at relatively high rotational speeds in order to produce a thread-like product 20 train. According to the present invention, in an arrangement according to the aforementioned DT-OS, a source of non-oxidizing gas is added in such a way that the Gas flow is mainly directed to the point 51 at which the edge 32 enters the melt surface 11. Through the The introduction of non-oxidizing gas to this point, according to the invention, decisively improves the method of operation according to the prior art.

The prior art on which the present invention is based works essentially according to the teaching in the above-mentioned laid-open specification. The molten material is after In a preferred embodiment of the present invention, a molten metal because of such a material normally at a temperature above its melting point under equilibrium conditions, against oxidation in the ambient air is sensitive. Although the advantages of such a Process using molten non-metals

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may not be as drastic as when using metals, the present invention is nevertheless applicable to any molten material which is close to the melting temperature, ie within a maximum deviation of 25-6 from that ^{measured in 0} K, under equilibrium conditions valid melting temperature, which has the following properties: surface tension in the range between 10 and 2500 dyn / cm;

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Viscosity in the range of 10 to 1 poise; reasonable discrete melting point (i.e. a discontinuous viscosity versus the temperature curve).

The disk-like, heat-dissipating component according to a preferred one The embodiment of the invention, as shown in Figure 2, has a radius of curvature (r) in one plane parallel to the axis of rotation at edge 32 between 0.0125 mm and 2.5 mm (between 0.0005 and 0.1 inches), and preferably one Between 10 cm and 75 cm (between 4 and 30 inches) in diameter. The preferred rotational speed of the component 30 results a linear velocity on circumference 32 in excess of 0.9 m / sec (3 feet / sec). The edge 32 is in this case with the surface 11 in contact and has a surface immersion depth not more than 1.5 mm (0.06 inches). The component 30 or the section

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this component, which includes the edge 3 2, need not consist of a special material, but it must have the ability have to conduct heat from the edge 32 into the component 30 in order to initiate the solidification at the edge 32 and thus the Form thread 20 '. The solid part of the denotes the final thread 20, which is produced while the adjacent edge 32 is still below the equilibrium surface 11 the melt 10 is located.

The objective of the present invention lies in the improvement in the formation and detachment of the thread 20; this improvement is achieved by eliminating various adverse effects namely by introducing a non-oxidizing gas into the area 12 of the fuselage surface 11. The gas 41 is initially arranged and aligned in such a way that there is a material floating on the surface 11, which is present in individual particles steers away from entry point 51. Figures 1, 3 and 4 show on the surface 11 a in the area 12 through the Effect of the gas 41 interrupted layer of individual particles of aggregates 15; this floating layer can but also from the oxide of the molten starting material

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exist. The gas flow does not have to be in such a direction that it completely transports the aggregate 15 or an oxidic impurity away from the point 51, but it is sufficient to keep the floating material in motion, so that not a quantity can be accumulated at the point 51 and drawn into the melt by the movement of the edge 32.

The gas 41 does not need any special chemical properties possess to accomplish this task, however, the procedure will further improved when the oxidation of the melt surface 11 in the area 12 where the protective aggregate 15 is not is present, is reduced to a minimum. This is achieved by choosing a gas composition that is either im is essentially inert (such as nitrogen or argon) or by using a gas that is resistant to the molten material serves as a reducing agent, or at least by using a gas that does not oxidize the molten material. Such a gas is here called non-oxidizing Denotes gas, and the person skilled in the art does not need any further information about the composition of such a gas, because the relative oxidizing properties of molten materials and gases are well known. A particular success

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has been found in experiments with molten metals using the following gases: acetylene, natural gas, argon, nitrogen, methane, cracked ammonia gas and processed gas (a mixture of about 20 percent by volume H ₂ and 80 percent by volume N 2). It is understood, however, that the gas only needs to be non-oxidizing in the area 12, i.e. where the edge 32 enters the melt surface 11 ^ therefore the gas supplied can consist of a reducing gas, but the combustion of a reducing gas in the Atmosphere also leads to reducing or inert combustion products at point 12 which would accomplish the object of the invention. Reducing gases have an advantage over relatively inert gases in that they not only simply replace the oxygen in the vicinity of the process, but that they can be made to actually take up and consume oxygen by combustion so that non-oxidizing products of combustion become attached the critical point in the implementation of the procedure. The products of combustion can contain solids; the process, when using acetylene, leads to individual carbon particles within the non-oxidizing gas and to extremely good results.

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The gas 41 also acts in a different way that is advantageous for the process. Because of the high rotation speeds of the heat-dissipating component becomes a gas layer, the ambient air, in the vicinity of the edge 32 due to the flow effect contains, accelerates. If the process is carried out at high speeds, this can lead to the edge oxidizing gas from the environment can be blown or injected into the melt. The localized oxidation of the Melt is detrimental to the process, but an additional difficulty arises from the fact that the introduced Gas separates the edge 32 from the melt 10 so that the formation of the thread 20 'is disrupted for a short time. If the edge 32 exposed to a flow of non-oxidizing gas, the layer of oxidizing gas can at least partially removed and this will reduce the extent of oxidation at the point of thread formation.

FIG. 3 illustrates an embodiment of the invention in which the non-oxidizing gas is allowed to impinge on region 12, that is, where the rotating component 30 enters the melt surface 11; this is achieved through the use of a nozzle-like, reached tubular gas line, which is connected to a source for the gas 41.

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Figure 4 shows an embodiment of the invention in which a Section of the component 30 is partially surrounded by the part 45. Non-oxidizing gas is in this envelope 45 from the Gas supply 40 initiated in such a way that a gas flow in the direction of the area 12 and the point 51 is caused. This embodiment affects the process in some respects in the same way as the Local introduction of gas when using a nozzle, because there is a good possibility for the non-oxidizing gas there, from the rotating component at the shaping edge to be carried away by the effect of the flow resistance at this edge. The edge 32 has during rotation a relatively long residence time in the non-oxidizing atmosphere, which is why it is when entering the surface of the molten material is essentially free of oxygen.

Figure 5 shows a device which is provided to the To prevent the introduction of oxidizing gas into the area 12 in which the edge 32 enters the surface of the molten material at location 51. The rotating, Heat dissipating member 30 is arranged with respect to bath of molten material 10 in the same manner as in FIG the other embodiments of the invention. However, in this one

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Embodiment a fixed cover 22 is arranged over the melt to prevent the entry of gas from the environment into the To refuse melt surface 11. The inventive idea of this type of embodiment lies in the selection of a material for the cover 22 which, when heated, absorbs or with the oxygen in the atmosphere in the area of the cover this oxygen reacts, so that then the gas in the. Area between the melt surface 11 and the cover 22 will contain non-oxidizing gas. Particular success has been achieved with the use of a cover made of solid carbon or made of Graphite found, with the heat radiated from the melt surface increasing the temperature of the cover up to such a value has been used, at which air in contact with the cover as a result of the reaction of the oxygen present with the carbon and the formation of carbon monoxide or carbon dioxide or a mixture of both, in which the remainder was essentially non-oxidizing nitrogen gas, in a non-oxidizing gas has been converted. In a preferred embodiment of the invention, the gas was that associated with the cover came into contact, opposite to the cover at the elevated working temperature essentially inert. Both in the aforementioned use of the word inert and in the other places in this Disclosure in which the gas is described as being essentially inert

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is not necessarily a chemically inert gas classified gas, such as argon, helium or Kryton, meant. To an essentially inert gas in the sense This revelation is in fact when it is not at a noticeable rate with one of the components of the system used reacts. Nitrogen is essentially inert with respect to some molten metals and therefore falls in the description under the class of essentially inert gases.

Graphite has the additional advantage that it can be combined with an induction heating system, which is used to heat the melt, can be coupled so that its heating is not complete depends on the radiation of the melt surface. In addition, graphite can be easily abraded; it can therefore be a cover can be made with a tight fit by grinding the rotating part 3O to the final fit or the opening in which the component 30 rotates is used. Of course, in the cover 30 precautions must be taken, in order to enable the thread 20, which is still adhering to the edge 32, to emerge from the cover.

The embodiment according to FIG. 5 can be compared with the embodiment according to

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Figure 4 by simply adding the cover 45 to the rotating component and adapting the casing to the cover are combined. In the same way, the embodiment according to FIG. 5 with that according to FIG. 3 when using a non-oxidizing source arranged at a certain point Gas can be combined. Although the non-oxidizing gas is locally introduced either above or below the cover 22 a preferred embodiment of the present invention is to inject the non-oxidizing gas into the area between the cover 22 and the surface 11 of the molten material 10.

Both with the embodiment of the invention in which an oxygen "pick up" cover is used and with the other versions using only one source of non-oxidizing gas and one of molten gas Material is brought into contact, it should be noted that certain combinations of gas, combustion products, molten liquid Materials and gas "absorbing" bodies can be dangerous. Those skilled in the art working with oxidation-sensitive molten materials should be sufficiently familiar with the possible danger of mixtures of the foregoing

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Components be familiar, without there being any special teaching or explanation about the behavior of all combinations of gases, temperatures, packing and molten liquids Requires materials that would be safe to operate in accordance with the present invention. The following specific examples will be enable the person skilled in the art to understand the interaction of the various material components according to the invention to understand without all known usable combinations of materials having to be specified.

The present invention works in an advantageous manner the spontaneous detachment of the thread simply by introducing a non-oxidizing gas at the point where the heat-dissipating gas Component enters the surface of the melt. In addition, however, the separation of discontinuous threads can be achieved Polishing the peripheral edge of the disc following the Further improve detachment of the thread. The polishing of the edge in connection with the introduction of non-oxidizing gas leads to a great improvement in the stability of the spontaneous thread detachment from the edge on the circumference of the heat-dissipating component. In the context of this invention, the term "polishing" means a gentle, moderate abrasion, which is carried out by a Relative movement between the edge and another fixed

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Material is brought about. Furthermore, if the polishing is carried out in such a way that the inner surfaces of the notches in the rotating component used for generating discontinuous filaments are also touched, the occurrence of the spontaneous separation is further improved. According to a preferred embodiment of the invention, the polishing movement (arrow 61) does not take place in a parallel direction, but at an angle to the direction of movement 37 of the protrusion arranged on the circumference of the circle on the rotating, heat-dissipating component 30. An arrangement with a rotating wheel, as shown in FIG is shown with the axis of rotation of the polishing wheel 60 at an angle to the rotating "heat dissipating" component, is one embodiment of such a system. For metals, consisting essentially of iron, the percentage of discontinuous filaments, which are detached spontaneously is further increased when the temperature of the molten material is less than 222 ° C (400 ⁰ F) above the melting point of the schraelzflüssigen iron under equilibrium conditions lies.

example 1

Natural gas with a flow rate of 0.0142 m / min (0.5 cfm) was fed through a 6.3 mm (1/4 inch) diameter nozzle to the entry point of a disc into the surface

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of the molten material directed. The material consisted essentially of AISI 1330 alloy steel (0.3 wt% C; 1.2 to 2.2% Mn; 0.1 to 0.7% Si), the temperature of the high-melt steel being between 1616 ° C and 1638 ° C. That The heat-dissipating component was water-cooled and consisted of a copper disk with a single V-shaped peripheral Bulge that coincides with the surface of the molten steel was brought into contact. The disc had a diameter of 20.8 cm (8 inches), was 1.27 cm (1/2 inch) thick, and the legs of the V were at -90 degrees from one another (Angle 0 in Figure 2). On the surrounding edge or protrusion Notches were arranged on the disc to give threads of a length corresponding to the distance between the notches produce. The disk rotated at 250 to 270 rpm. It came into being Steel filaments 2.54 cm (1 inch) in length and about 0.508 mm (0.020 inch) in effective diameter in continuous Way during / hours. During the manufacturing process, As in all examples, the appearance of fibers sticking to the edge of the pane after each interruption of the gas flow there, where the disc edge entered the melt surface, considerable elevated.

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Example 2

Acetylene was through a conventional welding nozzle (tip Wr. 3, US type) aimed at the point where the disk entered the melt surface. The melt consisted of steel, of nominal composition SAE 1024 at a temperature of about 1593 ° C (2900 ° F). The same type of disk as in example 1 was used and rotated at about 260 rpm. Manufactured became 25.4 mm long fibers in a continuous manner without substantial fiber adhesion to the disc over a period of 20 minutes.

Example 3

Natural gas was introduced into a partial envelope similar to that in Figure 4 at a flow rate of about 0.0283 m / min (1 cfm), with the envelope covering about 1/3 of the entire circumference of the disc. The molten material was SAE 1034 steel (with a composition of 0.35% by weight C; 0.49 to 0.52% Mn; O _f 28 to 0.37% Si) with a temperature of about 150 ° C (280O ⁰ F). The rotating heat dissipating member was water cooled and consisted of a copper washer 38.1 mm (1.5 inches) thick, 20.8 cm (8 inches) in diameter, and six V-shaped

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peripheral protrusions (4 per inch) rait angles of inclination θ the Leg of 90 °. Each of the six edges were notched to create 25.4 mm (1 inch) long fibers. The disc rotated at 210 rpm, and blowing gas into the envelope gave a non-oxidizing gas where the six edges entered the melt surface, and resulted in a significant reduction in the incidence of fibers sticking to the forming edge.

Example 4

Natural gas was introduced into an envelope as used in Example 3 at a flow rate of 0.0283 to 0.0566 m / min (1 to 2 cfm). The molten material was nominally SAE 1024 steel having a temperature of 1521 ⁰ C (277O ° F). The heat dissipating component consisted of three contiguous disks each having a diameter of 20.8 cm (8 inches) and each 12.7 mm (0.5 inch) thick, with one disk made of copper, the other made of aluminum, and the third made of brass duration. Each disc was water cooled and had a V-shaped edge around the perimeter. The disks rotated at 250 rpm and were in contact with the melt. A continuous thread was created on each disc with the same detachment point on the circumference of each of these three shaping edges. The separation points remained stable, with none

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Thread sticking occurred during gas introduction into the envelope.

Example 5

The same composite heat dissipating disk and molten material as in Example 4 were used with various other gases introduced into the enclosure. Argon at a flow rate of 0.0142 m ³ / min (0.5 cfm), nitrogen at 0.0283 to 0.0566 m ³ / min (1 to 2 cfm), acetylene at 0.0071 m / min (0 , 25 cfm) and hydrogen at 0.0283 to 0.0566 m / min (1 to 2 cfm) all resulted in improved resistance to detachment of the formed fibers over the manufacturing process without the use of a protective gas, but none of the gases were in this example equally effective as the natural gas according to example 4.

Example 6

Acetylene was directed through a nozzle to the point where the disk entered the melt, as shown in Figure 3 shown. is. In this embodiment of the invention, a circular polishing wheel made of a heat-resistant covering material, rotating in the opposite direction to the disk offset and brought into contact with the peripheral edge of the disc. The polishing effect of the wheel increased the percentage of discounted

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natural threads spontaneously detached from the disc. The molten material was nominally SAE 1024 steel with a temperature of 1566 ° C (2850 ° F). ■ '. '

Example 7

The arrangement of Example 6 was repeated, except that the axis of rotation of the circular polishing wheel obliquely to that of the rotating, heat-dissipating component, whereby the polishing of the peripheral protrusion under took place at an angle. The appearance of iron on the rotating component Adhering threads were further reduced in this exemplary embodiment compared to that according to Example 6. This was probably that Result of the covering material of the polishing wheel, the larger one Has an effect on the surface of the peripheral protrusion between the notches, which divide the thread into discrete lengths are available.

The invention was used both for the production of discontinuous as well as continuous metallic filaments with an effective diameter of less than 1.5 mm (0.06 inches). The effective diameter corresponds to the diameter of a round thread with the same cross-sectional area as the in cross-section non-circular thread, which was produced according to the present invention.

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Claims (27)

Claims 1. A method for producing solid, thread-like material directly from molten material by bringing the surface of this melt into contact with at least one peripheral protrusion in the form of the outer edge of a rotating, heat-dissipating component, characterized in that at the point (51) which the edge of the rotating component (30) enters the surface of the molten material (10), non-oxidizing gas is conducted. 2. The method according to claim 1, characterized in that the gas is allowed to impinge locally on the surface of the molten material (10). 3. The method according to claim 1, characterized in that the gas is passed by partially enclosing or enveloping the rotating, heat-dissipating component (30) and introducing the gas into this enveloped area to that point (51) at which the edge of the rotating component (30) enters the surface of the melt (10). 409842/0717 2412H9 ir 4. The method according to claim 1, characterized in that a gas which is essentially inert to the molten material (10) is used as the non-oxidizing gas. 5. The method according to claim 1, characterized in that a gas which has a reducing effect on the surrounding atmosphere is used as the non-oxidizing gas. 6. The method according to claim 1, characterized in that the non-oxidizing gas is formed from the combustion products obtained when a gas such as methane, natural gas, acetylene, cracked ammonia gas or processed gas (forming gas) is burned under a lack of oxygen. 7. The method according to claim 1, characterized in that the non-oxidizing gas is formed from a gas mixture which has no oxidizing effect on the molten material (10) at a temperature which is within a deviation of 25% from the melting temperature measured in ° K of the molten material (10) is under equilibrium conditions. . »09842/0717 2412H9 8t 8. The method according to claim 7, characterized in that the non-oxidizing gas is a flame burning with an oxygen deficit. 9. The method according to claim 7, characterized in that the non-oxidizing gas also contains carbon particles. 10. The method according to claim \, characterized, gekennzeighnet that the introduction of the gas takes place in such a way that on the surface of the molten material (10) floating solid
Material is deflected away from where the edge is
of the rotating component (30) enters the melt surface. 11. The method according to claim 10, characterized in that the solid material consists of the oxide of the molten material (10). 12. The method according to claim 10, characterized in that the solid material is a supplement to prevent oxidation of the molten material (10) on the surface. 409842/0717 2412H9 13. The method according to claim 1, characterized in that a metal is used as the molten material (10). 14. The method according to claim 13, characterized in that the metal is essentially iron. 15. The method according to claim 13, characterized in that the metal is sensitive to oxidation at a temperature which does not deviate by more than 25% from the ^{melting temperature measured in 0} K under equilibrium conditions. 16. The method according to claim 13, characterized in that the outer edge (32) of the rotating component (30) is provided with notches (33) and that discontinuous threads are formed, the length of which corresponds approximately to the distance between the notches. 17. The method according to claim 16, characterized in that the outer edge (32) is stripped or polished following the spontaneous detachment of the discontinuous threads. 4Ö9842 / 0717 2412H9 18. The method according to claim 17, characterized in that the outer edge (32) of the component (30) is polished with the aid of a body or material (60) which is moved obliquely to the direction of movement of this edge (32). 19. The method of claim 16, characterized in that the molten material (10) consists essentially of iron and has a temperature which is less than 222 ° C (400 ° F) above the equilibrium melting temperature of that material. 20. The method according to claim 1 -19, characterized in that by covering the molten material (10) with a body (22) which keeps oxygen away from the atmosphere in the area of this cover, a non-oxidizing atmosphere in the vicinity of that point (51) is maintained, at which the edge (32) of the rotating component (30) enters the surface of the melt (10). 21. The method according to claim 20, characterized in that the cover (22) is heated to the extent that it absorbs oxygen. 409842/0717 2412H9 22.- The method according to claim 20 _y characterized / that the cover (22) consists at least partially of solid carbon. 23. The method according to claim 22, characterized in that the cover (22) consists essentially of graphite. 24. The method according to claim 20, characterized in that the rotating component (30) is at least partially provided with an envelope and a gas is passed into this envelope (45). 25. The method according to claim 24, characterized in that the gas introduced into the enveloped area is essentially inert both to the metal in its molten state and to the graphite cover at the increased operating temperature of this cover. 26. The method according to claim 25, characterized in that the graphite cover is heated by radiant energy from the nearby molten material (10) and also by coupling with the induction heating system used to heat the molten material (10) . ^ 09842/0717 2412H9 27. The method according to claim 20, characterized in that the non-oxidizing gas is introduced into the area between the cover (22) and the surface of the molten material (10). 409842/0717 eers e ι te