KR20070095130A - A crucible for an electromagnetic continuous casting apparatus with high melting efficiency and product yield - Google Patents

Abstract

A simple crucible for an electromagnetic continuous casting machine, which substantially improves heating and melting efficiencies of a raw material with a high melting point and a low electrical conductivity, can maintain electromagnetic force in a state that the electromagnetic force is higher than hydrostatic pressure of molten metal over the entire molten metal section, and can continuously cast the raw material into a polycrystalline ingot with a high purity, is provided. A crucible for an electromagnetic continuous casting machine with excellent melting efficiency and recovery ratio is characterized in that: the crucible has a vertical shaft, consists of a hot crucible(11) in the upper part and a cold crucible(2) in the lower part, and is surrounded by an induction coil; the hot crucible is not cooled and made from an electrically conductive nonmetallic material; the cold crucible has a water cooling structure and made from a thermally and electrically conductive metallic material; and the crucible includes an insulating insert member(13) inserted into a groove formed in the vicinity of a position on an inner wall surface of the cold crucible that is longitudinally lower than a position at which an induction coil(1) is disposed.

Description

A crucible for an electromagnetic continuous casting apparatus with high melting efficiency and product yield}

1 is an overall configuration diagram of a crucible for a typical typical electromagnetic continuous casting machine.

Figure 2 is a cross-sectional view for explaining the structure of the cold crucible used in the comparative example of the prior art.

3 is a cross-sectional view for explaining the structure of the crucible for the electromagnetic continuous casting machine according to the first embodiment of the present invention.

Figure 4 is a cross-sectional view for explaining the structure of the crucible for an electromagnetic continuous casting machine according to a second embodiment of the present invention.

5 is a cross-sectional view for explaining the structure of the crucible for the electromagnetic continuous casting machine according to the third embodiment of the present invention.

6 is a CT tomography photograph of the silicon ingot prepared according to the second and third embodiments of the present invention.

Figure 7 is a cross-sectional photograph of the silicon ingot prepared according to the second and third embodiments of the present invention.

<Description of Main Parts of Drawing>

1: induction coil 2: cold crucible

3: slit 4: segment

5: molten metal 6: charging raw materials

7: dummy bar 8: ingot

9: plasma arc heating source 10: annealing furnace

11: thermal crucible 12: insulation (magnetic field permeation)

13: insulation insert member 20: partition plate

21: inlet 22: outlet

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crucible for electromagnetic continuous casting of semiconductors or metal materials having high melting points and low electrical conductivity into high purity ingots, such as the production of silicon ingots used for substrates of solar cells.

Ingots of this type are used as starting materials for the production of photovoltaic elements, for example silicon wafers, for example solar cells.

Until now, in order to manufacture silicon wafers for polycrystalline solar cells, ingots are prepared by dissolving silicon in a quartz crucible or in a quartz crucible placed inside the graphite crucible and then slowly directional solidifying from a water-cooled mold (or crucible mold-integrated) bottom. The manufacturing method of slicing ingots into very thin wafers having a thickness of less than 500 mu m has been most widely used. However, this method has a problem that silicon ingot is contaminated by graphite and oxygen flowing from graphite crucible and quartz crucible and quartz crucible is destroyed during the solidification and expansion of silicon. There is a problem.

On the other hand, since the quality and cost of the silicon wafer is determined by the quality and cost of the ingot, recently, the quality of the silicon wafer is improved by suppressing the incorporation of impurities, eliminating the loss of the crucible and the mold, and improving the productivity to lower the manufacturing cost. As a method, electromagnetic continuous casting has begun to be used.

As a conventional electromagnetic continuous casting method, as shown in FIG. 1, a continuous open-type cold casting of a lower open type made of an induction coil 1 and a conductive material (typically using oxygen-free copper) disposed inside the induction coil 1 Crucible 2 (cold crucible) is used.

This cold crucible 2 has a structure in which at least a portion along the circumferential direction, in particular a portion located inside the induction coil 1, is divided into several segments 4 by longitudinal slits 3, It consists of a water-cooled structure in which the cooling water passes through for the purpose of solidifying the molten metal (5) and protecting the cold crucible (2).

Thus, the slits 4 formed in the longitudinal direction transmit the magnetic field generated by the high frequency current flowing in the induction coil 1 to the inside of the crucible 2 to generate an induction current in the molten raw material. In addition to dissolving the charging raw material 6 continuously supplied by the Joule heating effect, electromagnetic force is generated toward the inside of the cold crucible 2 to reduce the contact between the melting raw material and the wall surface.

Electromagnetic continuous casting method has the advantage that the contamination of the raw material is suppressed by the contact reduction effect with the crucible, the quality of the ingot product is improved and at the same time the mold is not consumed and replaced, thereby reducing the equipment cost and improving productivity. In addition, the continuous casting operation is possible and the production rate is very high, it is possible to manufacture economic ingots.

However, such an electromagnetic continuous casting method causes a problem in manufacturing a high purity ingot of a material having high melting point and low electrical conductivity because the cold crucible has a water-cooled structure. In other words, in the electromagnetic continuous casting process of steel or aluminum, which does not require high purity, there is a separate melting process for dissolving raw materials in advance, and only the casting process takes place in the cold crucible, whereas in order to manufacture an ingot of high purity material. Since the melting process and the casting process are continuously performed together in the cold crucible, much power is required for melting the raw materials.

In particular, silicon is a semiconductor material having a very high melting point and low electrical conductivity, which has a large cooling effect due to radiant heat emission, but a small heating effect due to induction heating, which makes it difficult to continuously dissolve the material efficiently. This is due to the very low thermal conductivity and lack of coupling between the electrically nonconductive silicon and the induction heating source at temperatures below about 700 ^° C.

As a result, it is possible to use a large-capacity power supply unit of several hundred kW or to use the induction coil and plasma arc heating source by induction coils arranged around the crucible as in Japanese Patent Application Laid-Open No. 2001-19594. Although a method of forming a silicone solution in an open crucible is disclosed, these have the disadvantage of excessive equipment and manufacturing costs.

Accordingly, the present inventors maintain the electromagnetic pressure acting on the molten metal throughout the entire section of the molten metal in the continuous casting of low electroconductive material, while improving the heating and dissolving efficiency of the raw material significantly, while maintaining the vertical pressure. A high melting efficiency electromagnetic continuous casting device, which is composed of a thermal crucible at the top and a cold crucible at the bottom, and is surrounded by an induction coil, has been proposed in Korean Patent Application No. 10-2004-0065177.

On the other hand, according to the continuous research by the inventors, the structure of the crucible in the continuous continuous electromagnetic casting of high melting point, low electrical conductivity and high brittle semiconductor or metal material is easy to work, dissolution efficiency of raw material, ingot quality and It has a big influence on the recovery rate.

Referring to the cold crucible used in the conventional electromagnetic continuous casting method, only a part of the longitudinal direction of the assembled type and the cold crucible used in which several independent segments are assembled to match the cross-sectional shape of the ingot is divided into segments by the longitudinal slits. In the case of an assembled cold crucible, it is convenient in the research and development stage before the cross-sectional shape and size of the ingot is determined, but in the production stage, the independent segment is dismantled or assembled. Due to the process, there is a disadvantage that the ease of operation.

In the case of the integrated cold crucible, it is advantageous to prevent deformation of the segments and maintain the shape. However, as shown in Fig. 2, there is no slit, so that the slit portion that shields the magnetic field penetration into the cold crucible is used at the top of the cold crucible. There is a problem that the melting efficiency of the fall. That is, the raw material of the cool solid is supplied, and the hydrostatic pressure is small, so that the molten metal is far from the crucible wall, thereby lowering the magnetic field value at the upper part of the molten metal, which reduces the concentration effect of the magnetic field. It is difficult to install a thermal crucible for improving the melting efficiency as in Patent Application No. 10-2004-0065177, and even if it is installed, a large effect cannot be expected.

At this time, according to Japanese Patent Application Laid-Open No. 2001-19594, when the plasma arc heating source is used together to compensate for the insufficient heating effect, there is a problem that a side arc occurs to the wall surface of the cold crucible, and thus, a quartz tube or the like is used. Additional insulation must be provided.

On the contrary, if the slit portion of the integrated crucible is placed under the cold crucible, it can reduce the magnetic field attenuation effect at the top of the molten crucible and is suitable for installing the thermal crucible, which is advantageous from the viewpoint of the heating effect of the raw material, but this time ingot Will adversely affect the quality and recovery rate. In other words, as the distance from the bottom of the induction coil where the solidification layer, which is the cooling unit, is formed, to exit the cold crucible is increased, the temperature of the ingot is rapidly decreased, so that a large thermal stress field is formed, and thus crystal defects such as dislocations are easily generated. In particular, in the case of highly brittle materials, cracks occur and the recovery rate is reduced.

Accordingly, the present invention is to solve the above problems, while significantly improving the heating and dissolution efficiency of the high melting point and low electrical conductivity raw materials, it is possible to maintain the electromagnetic force greater than the hydrostatic pressure of the melt over the entire section of the melt It is an object of the present invention to provide a crucible for a simple electromagnetic continuous casting machine capable of continuously casting this raw material into a high-purity polycrystalline ingot.

It is also an object of the present invention to provide a crucible for an electromagnetic continuous casting machine capable of continuously casting electromagnetically or highly brittle semiconductor or metal material with high purity in a high recovery rate without generating crystal defects and cracks. do.

Experimental and numerical results show that in typical electromagnetic continuous casting method using only cold crucible, 70 ~ 80% of induction calorific value is generated in cold crucible, so that it does not contribute to heating and melting of raw materials but is lost by cooling water. do.

In particular, the upper part of the molten metal to which the raw material is supplied has a small hydrostatic pressure proportional to the height of the molten metal, so that the molten metal is far from the crucible wall, and thus the concentration effect of the electromagnetic field is small, resulting in a low electromagnetic field value and a reduction in induced calorific value.

In this case, when the raw material is a material with high melting point and low conductivity, the capacity of the high frequency power supply is small and the current applied to the induction coil is small, so that the heating effect due to induction heating is smaller than the cooling effect due to the emission of radiant heat. This makes the continuous melt casting process difficult.

On the other hand, since the hydrostatic pressure increases as the height of the melt increases, the lower portion of the melt is an area in which the effect of electromagnetic pressure becomes more important than the heating effect in order to maintain contact with the crucible.

In addition, in the case of a high melting point, low electrical conductivity, and brittle material, it is preferable to avoid a sudden temperature drop when a solidification layer is formed outside the bottom of the induction coil to prevent crystal defects and cracks. In particular, the semiconductor material such as silicon, once solidified, the electrical conductivity is drastically reduced, and thus the amount of induction heating is drastically reduced, so the temperature of the ingot is more easily dropped.

Therefore, in order to solve these problems, in the present invention, a crucible for an electromagnetic continuous casting machine having a vertical axis and having no bottom surface is configured as follows.

A crucible for an electromagnetic continuous casting machine having excellent dissolution efficiency and recovery rate used in the electromagnetic continuous casting device, wherein the crucible has a vertical axis, and consists of a hot crucible at the top and a cold crucible at the bottom, and is surrounded by an induction coil. The crucible is not cooled, it is made of an electrically conductive non-metallic material, and the cold crucible has a water-cooled structure, is made of a thermally conductive and electrically conductive metal material, and at least a portion of the upper side of the cold crucible and the heat At least a part of the outer side of the crucible is located inside the induction coil, while greatly improving the dissolution efficiency of the raw materials, while maintaining the electromagnetic force greater than the hydrostatic pressure of the molten metal throughout the entire section of the molten metal, and in the longitudinal direction of the inner wall of the crucible. At least a portion below the induction coil is dug out and the base metal It provides a dissolution efficiency and electromagnetic continuous casting crucible appointed recovery is excellent so that by inserting the insulated insert element of charge reduces the radiant heat emission.

Preferably, the thermal crucible has an upper end integrated in the circumferential direction, and the lower end has a structure in which at least a portion of the circumferential direction is divided into segments by longitudinal slits, and the cold crucible has at least a portion in the circumferential direction. The present invention provides a crucible for an electromagnetic continuous casting machine with excellent dissolution efficiency and recovery rate, which forms a structure divided into segments from an upper end portion to a lower end portion by longitudinal slits.

Also preferably, the thermal crucible and the heat insulation insert member may be thermally and electrically separated from each other by inserting or voiding a sheet of low electrical conductivity and low thermal conductivity between the cold crucible. In particular, the thermal crucible electrically separated from the cold crucible is advantageous in preventing side arc generation when a heating source such as a plasma and an electron beam is used in combination, and the amount of heat generated by thermal separation should be reduced to the cold crucible. It is advantageous to increase the amount delivered to the molten metal. In addition, the insulating insert member must be separated from the cold crucible thermally so that the surface temperature of the insulating insert member is closer to the temperature of the ingot, which is advantageous to suppress the rapid cooling of the ingot by radiant heat release. To be advantageous.

Also preferably, the water cooling structure of the cold crucible provides a crucible for an electromagnetic continuous casting machine having excellent dissolution efficiency and recovery rate in which inlets and outlets are formed at the lower end of the lower portion of the cold crucible. The inlet and outlet locations are formed at the lower end of the cold crucible because the integrated cold crucible is used by placing the slit in the lower part of the cold crucible to supply raw materials of cold solids and to keep the molten metal away from the crucible wall. This is because the magnetic field attenuation effect by the slit portion in the upper part of the molten metal becomes smaller as the concentration effect of the magnetic field decreases, and it is also suitable for installing a thermal crucible, which is advantageous in terms of the heating effect of the raw material.

Also preferably, the electrically conductive nonmetallic material provides a crucible for an electromagnetic continuous casting machine with excellent melting efficiency and recovery rate of graphite.

Also preferably, the present invention provides a crucible for an electromagnetic continuous casting machine having excellent dissolution efficiency and recovery rate, further comprising a magnetic field transparent cover of a heat insulating material surrounding the outside of the crucible.

Also preferably, at least some of the longitudinal slits provide a crucible for an electromagnetic continuous casting machine with excellent dissolution efficiency and recovery rate that extends linearly across the thermal crucible and the cold crucible.

( Example )

Hereinafter, the present invention will be described in more detail with reference to Comparative Examples and Examples.

2 to 4, the magnetic field was measured and compared while changing the structure of the crucible for the electromagnetic continuous casting machine, and silicon melting and casting experiments were performed. The prepared ingots were subjected to CT tomography and direct inspection by cross section cutting. It was confirmed whether or not it occurred.

On the outside of the crucible is placed an induction coil (1) wound by a 5-10 turn solenoid with a water cooled copper tube with a diameter of 125 mm and an outer diameter of 125 mm and an outer diameter of 145 mm, with the top of the induction coil 1 positioned 5 mm below the top of the crucible. An AC current of 20 kHz was applied up to 1,230 A.

For continuous casting, first, the raw material (6) is charged into the crucible while the bottom of the crucible is blocked with the dummy bar (7), and the initial molten metal (5) is formed until the top of the crucible is 5 mm below the top of the crucible. , While continuously supplying the raw material 6, the dummy bar 7 is lowered at a constant speed to continuously manufacture the ingot 8.

( Comparative example )

As shown in FIG. 2, the conventional crucible consists of a cold crucible 2 of a lower open type of conductive material disposed inside the induction coil 1, the upper part of the crucible 2 being integrated in the circumferential direction. It is a slit-free portion, and the lower portion is an integral structure divided into several segments 4 by longitudinal slits 3 along the circumferential direction. In addition, for the purpose of solidifying the molten metal 5 and protecting the crucible, the inside of the crucible was configured to allow water to cool by passing cooling water. The inner diameter of the cold crucible, which determines the diameter of the ingot, was 50 mm, and was divided into equally spaced segments by twelve slits (3).

In the comparative example, the lowest magnetic field value was shown under the same applied current as compared with Examples 1 to 3, and as a result, the continuous melt casting process after forming the initial molten metal 5 was very difficult. This is because silicon is a material with low electrical conductivity and high melting point, and the heating effect due to induction heating is small while the cooling effect due to radiant heat emission is large, so that the molten metal 5 is easily cooled.

First embodiment

As shown in FIG. 3, the crucible 2 of the first embodiment consists of a cylindrical member which is open without a bottom surface. In the lower open type cold crucible 2, the upper part is divided into a plurality of parts (segments) 3 in the circumferential direction, and the lower part thereof has an integral structure consisting of a slit part in the circumferential direction. By forming a plurality of slits in the upper portion of the cold crucible, the magnetic field is transmitted to the inside, and the lower portion of the cold crucible is integrated to support the segments 4 of the upper portion. The inner diameter of the cold crucible, which determines the diameter of the ingot, was 50 mm, and was divided into equally spaced segments by twelve slits (3).

In addition, the inside of the crucible 2 has a structure in which the inside of the crucible is water cooled by passing a cooling liquid for the purpose of solidifying the molten metal 5 and protecting the crucible. Specifically, by dividing by the partition plate 20 to form the inside and the outside, the coolant introduced through the inlet 21 formed at the lower end of the cold crucible 2 rises along the inside to cool the inner wall surface. Thereafter, it descends along the outer portion and is collected at the outlet 22 formed at the lower end of the cold crucible 2, and then discharged out of the cold crucible 2.

The induction coil 1 is provided concentrically on the upper outer side of the open crucible 2 and is connected to a power source (not shown) by a coaxial cable (not shown). The induction coil 1 and the coaxial cable (not shown) are cooled by the same cooling means.

The bottom open cold crucible 2 has a width of about 13 mm between the segments 4 formed in the circumferential direction. The material of the lower open crucible 2 may be a conductive material in addition to copper.

Although the first embodiment showed the highest magnetic field value among all the examples including the comparative example, the continuous melt casting process after forming the initial melt 5 was still difficult. According to the calculation result of OPERA-3D, a commercial program dedicated to electromagnetic field analysis, about 70% of the total induction calorific value generated in the electromagnetic continuous casting process as in the first embodiment is generated in the cold crucible (2), thereby heating and dissolving raw materials. This is because the cooling process does not contribute to the loss.

Second embodiment

In the second embodiment, as shown in FIG. 4, the lower open cold crucible 2 is divided into equally spaced segments 4 by twelve longitudinal slits 3 in the circumferential direction at the top except the bottom. It consists of a hollow cylindrical member with an inner diameter of 50 mm made of copper having a divided structure. Divided into segments by longitudinal slits, the magnetic field is transmitted into the interior of the cold crucible.

The lower part of the lower open cold crucible 2 is integrated in the circumferential direction to support the upper segments 4.

The interior of the cold crucible 2 is partitioned by the partition plate 20 to form the inside and the outside, so that the coolant introduced through the inlet 21 formed at the lower end of the cold crucible 2 rises along the inside and the inner wall surface. It cools, descends along the outer portion and is collected in the outlet 22 formed at the lower end of the cold crucible 2, and then discharged out of the cold crucible 2. In the embodiment according to the present invention, the inlet port 21 and the outlet port 22 form a structure formed at the lower end of the lower portion of the cold crucible.

The lower open crucible 2 has a width of about 13 mm between the segments 4 formed in the circumferential direction. The material of the lower open crucible 2 may be a conductive material in addition to copper.

The thermal crucible 11 is provided on the lower open cold crucible 2 in a concentric manner. The thermal crucible 11 arranged on the cold crucible 2 does not have a cooling structure and is not cooled. The crucible 11 is made of a graphite material having an inner diameter of 50 mm, an outer diameter of 80 mm, and a height of 30 mm. The lower part has a structure divided into 12 equally spaced segments 4 by a slit 3 having a length of 20 mm.

The induction coil 1 is arranged to surround at least a portion of the outer circumference of the upper portion of the cold crucible 2 and at least a portion of the outer circumference of the thermal crucible 10 and has a longitudinal direction formed on the upper portion of the cold crucible 2. The slits 3 and the slits 3 formed at the bottom of the thermal crucible 10 were continuously connected to each other so that electromagnetic forces were not cut off and canceled even near the boundary of the two crucibles.

In the second embodiment, the magnetic field value was slightly lower than that of the first embodiment, but the magnetic field value was much higher than the comparative example. As a result of the melt casting test, the solid raw material 6 was added at a rate of 170 g / min or more, and the molten metal 5 was used. Melt casting was also possible while suppressing contact with the crucible.

However, there occurs a problem that cracks are formed in the ingot as shown in FIGS. 6 and 7. This is because the length of the cooling section, that is, the distance from the lower end of the induction coil (1) where the solidification layer is formed to exit the cold crucible (2) becomes long, and the temperature of the ingot (8) rapidly decreases to form a large thermal stress field. As a result, cracking occurred in the brittle silicon ingot.

Third embodiment (optimum preferred embodiment)

In the third embodiment, as shown in FIG. 5, a part of the inner wall located below the induction coil 1 in the longitudinal direction of the inner wall of the cold crucible 2 is grooved and an insulating insert member made of a non-metallic material ( 13) is inserted. Other remaining conditions are the same as in the second embodiment.

In the third embodiment, as a result of the melt casting experiment of silicon, the molten metal 5 was continuously melt cast while the solid raw material 6 was charged at a rate of 170 g / min or more under a non-contact condition with the crucible. In addition, the results of the direct examination by CT tomography and cross-sectional cutting showed no cracks.

In order to evaluate the magnetic field value at the position corresponding to the upper part of the molten metal 5 in which the change of the magnetic field according to each embodiment, in particular the radiant heat emission is the largest and the magnetic field concentration effect is determined to be the smallest, Magnetic field values at the center of the top are summarized in Measurement Table 1. As in the first to second embodiments, it can be seen that the cold crucible 2 preferably has a portion divided into segments 4 disposed upward.

Table 1 Magnetic field values at the center of the upper end of the induction coil in Comparative Examples and Examples

Comparative example First embodiment Second embodiment Magnetic field (gauss) 150 260 220

FIG. 6 and FIG. 7 show photographs of the ingot 8 manufactured in the second and third embodiments, respectively, in which cracks were generated by CT scan and direct inspection by cross section cutting. Cracking of the ingot 8 can be effectively suppressed by a simple method of digging a portion of the inner wall of the cold crucible 2 under the induction coil 1 and inserting the insulating insert member 13. Able to know. This is determined by the surface temperature of the two facing objects as the hot surface of the insulating insert member 13 replaces the cold surface of the cold crucible 2 in the cooling section. This is because radiant heat emissions, which are determined by the difference of four squared values, are greatly reduced.

The present invention as described above can significantly improve the heating and dissolving efficiency of the raw material while maintaining the electromagnetic pressure acting on the molten metal over the entire section of the molten metal than the hydrostatic pressure of the molten metal, in particular, the heating effect of the electromagnetic field is small, the induction calorific value On the other hand, it is effective in improving the heating effect of the upper part of the molten metal, which is large in radiant heat emission, and can maintain the contactless or thermal contact state over the entire section of the molten metal to significantly improve the dissolution efficiency of raw materials. The combination of the primary heating source is easy.

Further, according to the present invention, it is possible to effectively suppress the formation of crystal defects and cracks by reducing the radiant heat emission of the cooling unit, thereby improving the recovery rate, and easy to maintain the crucible. Therefore, there is an advantage that the continuous melting of the semiconductor or metal material having a high melting point, low electrical conductivity and high brittleness by using a simple crucible.

Claims (7)

Crucible for continuous casting machine with excellent melting efficiency and recovery rate The crucible has a vertical axis and is composed of an upper crucible and a lower crucible, surrounded by an induction coil, and the crucible is not cooled, but is made of an electrically conductive nonmetallic material, and the cold crucible is water cooled It has a structure and is made of a thermally and electrically conductive metal material, A crucible for an electromagnetic continuous casting machine having excellent dissolution efficiency and recovery rate, including an insulation insert member inserted into a groove formed near the bottom of the induction coil in the longitudinal direction of the inner wall of the cold crucible. The crucible of claim 1, wherein an upper end portion is integrated in a circumferential direction, and a lower end portion has a structure in which at least a portion of the circumferential direction is divided into segments by longitudinal slits, and the cold crucible is formed in at least a circumferential direction. A crucible for an electromagnetic continuous casting machine with excellent melting efficiency and recovery rate, in which a part is divided into segments from an upper end to a lower end by longitudinal slits. The crucible for an electromagnetic continuous casting machine according to claim 1, wherein the thermal crucible and the insulating insert member are excellent in melting efficiency and recovery rate, which are thermally and electrically separated from the cold crucible. The crucible for an electromagnetic continuous casting machine according to claim 1, wherein the water-cooling structure of the cold crucible is excellent in dissolution efficiency and recovery rate in which inlets and outlets are formed at the lower end of the lower part of the cold crucible.         The crucible for an electromagnetic continuous casting machine according to claim 1, wherein the electrically conductive nonmetallic material is graphite. The crucible for an electromagnetic continuous casting machine of claim 1, further comprising a magnetic field permeable cover of a heat insulating material surrounding the outside of the crucible. 3. A crucible for an electromagnetic continuous casting machine according to claim 2, wherein at least some of the longitudinal slits are linearly spread across the thermal crucible and the cold crucible.

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