CH674813A5 - - Google Patents

Description

1

CH 674 813 A5

2nd

description

The invention relates to a method for the surface treatment of a refractory wear part for a closure member of a metallurgical container, in which the wear part is designed as an inlet sleeve, outlet sleeve, slide plate or base plate.

Such wear parts usually consist of fired refractory ceramic materials, e.g. Made of zirconium oxide, boron nitride with hexagonal lattice structure, aluminum titanate or made of high-alumina material. Furthermore, refractory refractory concrete with a high-alumina starting material is also used.

In operation, these wear parts are exposed to very high temperatures, particularly at the surface zones in contact with the liquid steel, and very strong wear due to the constant contact with the liquid steel. As a result, these parts have to be replaced very often.

In a known slide closure according to DE-OS 1 937 742, its slide plate in the flow opening and on the sealing surface consists of a hard material, preferably a high-melting, oxidation-resistant metal silicate. This hard material, which is designed as an insert, is embedded in the slide plate made of conventional material and fastened by means of an elastic, fire-resistant putty. The production as well as the pre-processing of the slide plate for this use is relatively complex.

The object of the present invention is to achieve an increase in durability in the case of wearing parts of the type described in the introduction by means of a simple and effective method.

The object is achieved according to the characterizing part of claim 1. As a result, the service life of these wearing parts can be increased considerably without the need for complex machining.

In a very preferred type of treatment, the surface layer of the wear zone is melted and compressed by a laser beam in such a way that the wear on these surfaces which come into contact with the molten metal is significantly less than with a comparable wear part without treatment.

An additive can also be placed or sprinkled on the surface layer of the wear part, which is melted together with the surface layer of the base body, which together form a type of alloy. The additive is preferably in the form of a powder, e.g. Aluminum oxide, magnesium oxide, zirconium oxide or boron nitride.

The laser beam is guided over the wear zone with such an intensity and feed rate that the surface layer of the wear part is heated briefly and just above the melting temperature to a depth of approximately 2 mm.

If the wear zones are flat surfaces, such as a slide or base plate of a slide closure, it is moved back and forth relative to the laser beam or vice versa at a feed rate and after each linear movement with a transverse adjustment. These transverse adjustments should each be equal to or less than the diameter melted by the laser beam.

The flow opening wall of such a wear part is optionally treated either by a laser beam incident obliquely into the opening, which is rotated relative to the wear part or vice versa about the central axis of the opening and is adjustable in height along this axis, or the laser beam is parallel or slightly oblique to the axis in the Opening guided and deflected by a mirror on the wall, the mirror in the flow opening relative to the wear part or vice versa and is arranged along the axis height adjustable. As a result, the flow openings of such wear parts can be treated very simply and efficiently.

The wear part is preferably arranged between 50 and 100 mm from the laser source. This essentially depends on the lens used for the laser and its focal length.

At a feed speed between 1 and 10 mm / s and respective cross adjustments between 0.5 and 2 mm, the intensity of the laser beam should be between 1 and 50 kW / cm2.

However, the surface layer treatment of a wearing part can also be carried out by the chemical vapor impregnation known per se. In this process, reactants are reacted in a reactor under vacuum, which should have a temperature of approximately 1000 ° C, e.g. Titanium nitride, titanium carbide and / or aluminum oxide introduced.

Plasma welding or coating with metals can also be used as further treatment options for the present invention.

The treated wear parts advantageously consist of ceramic materials known per se, such as alumina, zirconium oxide or magnesium oxide. The invention can also be used for wear parts made of inferior material, in particular fire-resistant refractory concrete.

Adequate surface layer treatment for slide or base plates of slide closures is achieved if at least their sliding surfaces around the flow opening have been treated with approximately half the opening diameter. When using these plates with great wear, it can be advantageous if their sliding surfaces are treated at least in the area covered by the flow opening of the opposite plate from the full closing position to the full opening position of the closure and also the flow opening wall thereof. Since the sliding surface of a plate is often roughened after the surface layer treatment, it is then ground.

Slider or base plates are increasingly repaired after use, in 5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

2nd

3rd

CH 674 813 A5

4th

for example, high-quality inserts are embedded in the drilled plate. Here, too, an increase in durability can be achieved by the surface layer treatment according to the invention on the upper end face and advantageously also in the flow opening of this insert.

In the case of closure members, inlet and outlet sleeves or pouring pipes are also often used. These are preferably treated at least in the upper area of the flow opening.

Embodiments of the invention are explained below with reference to the drawing. Show it:

1 shows a wear diagram of schematically illustrated refractory wear parts of a sliding closure in longitudinal section,

2 refractory wear parts of a three-plate sliding closure in longitudinal section with the surface layer treatments according to the invention,

3 shows a plan view of a slide plate of a slide closure,

3a shows an enlarged partial section along the line a-a of FIG. 3,

3b is an enlarged plan view along the circular line b of FIG. 3,

4 and FIG. 5 are schematic representations of the surface layer treatment of flow openings of wear parts,

6 and FIG. 7 design variants of closure plates with surface layer treatment according to the invention in longitudinal section.

The closure member shown in FIG. 1 on the spout 15 of a molten metal container 10, which is only partially shown, is a sliding closure 20, in which only the refractory wearing parts 14, 16, 18 and 21 are shown. The inlet sleeve 14 is embedded in the container base 11 having a steel jacket 12. A refractory base plate 16 adjoining this inlet sleeve 14 has a flow opening 17 which is arranged concentrically with the opening 15 of the inlet sleeve 14. By means of a refractory slide plate 18 pressed against the base plate 16, to which a refractory outlet sleeve 21 is connected, the closure 20 can be opened or closed by means of a mechanical drive (not shown). In the position shown, the closure 20 is in the fully open position. Such sliding closures are known per se and therefore only the parts essential to the invention are shown.

As can be seen in FIG. 1, refractory wear parts of closure members for containers containing molten metal are exposed to the greatest wear in the areas that come into contact with the liquid metal. The strength of the wear varies depending on the application and essentially depends on the refractory composition of the individual wear parts, the composition of the metal to be cast and also on the casting time. The inlet sleeve 14 is typically their

Flow opening 15 in the upper area Z14 worn. In the case of the closure plates 16 and 18, their flow openings 17 and 19 are often worn out at the edges Z16 on the side of the sliding surfaces 16 'and 18'. The outlet sleeve 21 is particularly exposed to the greatest wear in its area Z21 of the flow opening 22.

With the sliding closure 30 according to FIG. 2, only the refractory wear parts essential for the invention are also shown. The closure 30 is designed as a three-plate sliding closure and is preferably used as a closure member on intermediate containers in the continuous casting process which can be regulated by the amount of molten metal. The individual wear parts are provided with the surface layer treatment according to the invention. The refractory base plate 32 fixedly arranged at the spout of the intermediate container is in sliding contact with a lower refractory closure plate 36 with a refractory middle plate 34. Again, by moving this middle plate 34, a full or throttled opening or, as shown in FIG. 2, a closing of the Closure 30 can be achieved. The flow opening 33 of the base plate 32 is arranged concentrically with the opening 37 of the plate 36. A pouring pipe 38 with a flow opening 39 which overlaps with the opening 37 is usually connected to the lower plate 36. The purpose of this pouring tube 38, which is immersed in the molten metal of a mold (not shown), is to shield the pouring jet from the surroundings so that the molten metal does not absorb oxygen or other elements.

According to the invention, the wearing parts are compacted by a surface layer treatment at their zones Z exposed to the greatest wear. The upper and lower plates 32 and 32, respectively. 36 are treated at the areas Z32 and Z36 which come into contact with the flow opening 35 of the middle plate 34, the lower plate being additionally treated in the area Z36 'in its flow opening extension. The middle plate 34 is in turn treated with the areas Z34 and Z34 'which come into contact with the flow openings 33 and 37 of the upper and lower plates 32 and 36. In addition, it is also advantageously treated in the wall area Z35 of its flow opening 35, since this opening is normally exposed to particularly heavy wear. The pouring tube 38 is treated in its flow opening wall at least in its upper region Z39. However, it is preferably also treated in the area Z39 'of the outflow and also on the outside in the area Z38 which is in contact with the very aggressive slag which is located above the mold bath.

A plate 40 according to FIG. 3, which can be, for example, a slide plate, is compacted in the area Z40 by surface layer treatment using a laser. In operation, the slide plate 40 can be moved from a full closed to a full open position and vice versa over a predetermined stroke. The flow opening of one with the sliding surface 42 of the slide

5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

3rd

5

CH 674 813 A5

6

The fixed base plate in contact with the top plate 40 and thus the melt located in the throughflow opening of this base plate covers the area Z40 of the slide plate 40. According to the invention, the surface layer of this area is melted by a laser beam at a determinable depth t according to FIG. 3a and is thereby compacted. The depth t is generally between 0.5 and 2 mm. The laser beam melts the surface in a diameter d and is guided over the area Z40 with an adjustable feed speed vs, by back and forth movements sx and transverse adjustments sy. The back and forth movements are preferably provided transversely to the direction of displacement 43 of the plate 40, but could also take place along the direction of displacement. A transverse adjustment sy preferably takes place after each back and forth movement, likewise with the feed speed vs, as shown in FIG. 3b. The transverse adjustment sy should be equal to or less than the diameter d melted by the laser beam. This ensures that the entire area is melted and that there are no unmelted gaps between the back and forth movements.

In the case of surface layer treatment by means of laser through flow openings 51 in a wear part 50, a laser beam 52 falling obliquely into the bore is shown in FIG. 4, which is caused by a rotary movement of the wear part 50 or by rotation of the laser source 55 about the opening axis 54 and by a height adjustment sy the same is guided on the opening wall Z50, the height adjustment preferably being carried out after each rotation of the wearing part or else of the laser source by an upward or downward movement.

5, the laser beam 52 is advantageously directed coaxially to the bore axis 54 onto a mirror 53 located in the opening 51, which is advantageously at an angle of 45 ° to the axis, and deflected perpendicularly by the latter onto the flow opening wall Z51. Again, in order to generate a predetermined feed rate of the laser beam 52 on the flow opening wall, the workpiece 50 or the mirror 53 is to be rotated about the axis of the bore 54 and adjusted by the height sy after each revolution. This in turn ensures that the entire area of the treated flow opening wall Z50 is melted by the laser beam.

The laser source should preferably be placed between 50 and 100 mm away from the workpiece, depending on the focal length of the lens used in the laser source. The focal point should be approximately in the area of the surface layer to be treated. In practice, a feed rate vs between 1 and 10 mm / s and respective transverse adjustments sy between 0.5 and 2 mm with an intensity of the laser beam between 1 and 50 kW / cm2 have proven successful. A CO 2 laser is preferably used as the laser.

For example, the treatment of a high-alumina ceramic plate was carried out with a laser beam which had an intensity of 11.5 kW / cm2 and a melting diameter on the surface of 1.2 mm and a feed rate vs of 4.7 mm / s in Cross adjustments of 1 mm over the surface was performed. The distance from the laser source to the workpiece was approximately 85 mm.

The following sizes were selected for another treatment of high-alumina ceramic material: intensity 2.4 kW / cm2, diameter 2.6 mm, feed speed 4.7 mm / s, transverse adjustment 1 mm and distance of laser source to workpiece approx. 50 mm.

The following sizes were used for two different treatments of zirconium oxide plates: intensities a) 11.5, b) 2.4 kW / cm2; Diameter a) 1,2, b) 2,6 mm; Feed speed a) 4.7, b) 29.5 mm / s; Transverse adjustment a) 0.5, b) 0.5 mm; Distance laser source to workpiece a) 85, b) 50 mm.

In a similar way, the invention can also be used for all other materials that are used in connection with closure members on molten metal containers, e.g. Magnesium oxide, refractory concrete, as described for example in DE-PS 2 624 299, or also apply to fiber-containing materials.

In the case of surface layer treatment by means of a laser, in which an additive is sprinkled or placed on the surface to be treated, the same sizes as described above are used, but advantageously at about half the feed rate compared to the treatment without the use of additives. A powder with a grain size between 0.01 and 0.2 mm can be used as an additive, which is sprinkled evenly on the surface, or sintered platelets with a thickness of up to one millimeter could also be placed on the surface to be treated. After the surface layer to be treated has been covered by the additive, it is melted together with the surface layer by a laser beam in the same way as shown in FIG. 3, thereby creating a connection between the additive and the molten surface layer. When treating a flow opening wall with additive, if powder is used, it can be glued to the wall before the treatment or a sintered sleeve can be fitted.

In another surface layer treatment of wearing parts for closure members on metal melt containers according to the invention is chemical vapor impregnation (CVI), which is a special form of chemical vapor deposition (CVD) and is known per se. The wearing parts are placed in a furnace heated to approximately 1000 ° C and under vacuum (pressure approximately 50-150 mbar). Reactants introduced into the furnace form a reaction substance which is deposited on the surface of the wearing parts and whose surface

5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

4th

7

CH 674 813 A5

8th

Diffuse layer and thereby adhere. For the treatment, the commercially available materials mentioned above can in turn be used as wearing parts.

For example, the following quantities of reactants can be fed into the furnace: To generate and separate titanium nitride, hydrogen (4 l / min), nitrogen (4 l / min) and 1% of the amount of hydrogen chloride (TÌCI4) were placed in the furnace for four hours entered. Hydrogen (9.6 l / min), metane (CH4, 400 cm3 / min) and titanium chloride (TÌCI4, 4% of the amount of hydrogen) were introduced into the furnace for four hours to produce and deposit titanium carbide. Hydrogen (7.4 l / min), carbon dioxide (0.36 l / min) and aluminum chloride (AICI3, 0.19 l / min) were also introduced into the furnace during seven hours during the production and deposition of alumina. The wearing parts are coated over their entire sliding surface.

The plasma welding process, in which ionized gas such as inert gas, e.g. Argon, together with alumina powder, is melted into the surface layer of the wear part to be treated.

A further type of surface layer treatment would also be a metal coating, in particular of wear parts in closure members for light metal melts with lower melting temperatures. In principle, a combined treatment could also be considered. For example, laser treatment could also be carried out after the metal coating.

Closure plates for sliding closures are repaired more and more frequently after a first use by embedding high-quality inserts 62 in the worn flow opening of the closure plate 60 according to FIG. 6. Even in such applications, the invention has proven itself very well through surface layer treatment of at least the area Z62, but preferably also the flow opening wall Z63.

7, plates 70 (80) ground on both sides are often used for sliding closures, which are turned over on one side 71 and the flow opening 72 after wear; the other side 73 and the flow opening 74 are then used, the latter being filled with a plug 74. This plug 74 is removed after the plate 70 has been turned and inserted into the worn opening 72. In accordance with the invention, this plate is compacted on both sides, at least in the areas Z71 and Z73 which are subject to the greatest wear, by surface layer treatment. The two holes could also be treated. The plate 70 is held together by a sheet metal ring 75 surrounding it.

The invention can of course also be applied in a corresponding manner to rotary slide closures or other types of slide closures.

Find particularly in the steel mill industry

predominantly the slide closures already described in more detail, but the invention can also be used with other closure members, such as stoppers or rotary stoppers, but also with wear parts of free-running nozzles. The refractory wear parts used in this case are correspondingly compacted with one of the surface layer treatments mentioned, at least in the zones exposed to the greatest wear.

Claims (23)

Claims 1. A method for the surface treatment of a refractory wearing part for a closure member of a container containing molten metal, in which the wearing part is designed as an inlet, outlet sleeve, slide or base plate, characterized in that the wearing part is at least in the zone (Z) exposed to the greatest wear. is compacted by surface coating. 2. The method according to claim 1, characterized in that the surface layer of the wear zone (Z) is melted by a laser beam and thereby compressed. 3. The method according to claim 1, characterized in that the surface layer of the wear zone (Z) after application or sprinkling of an additive is melted by a laser beam and the likewise melted additive binds to the surface layer. 4. The method according to claim 3, characterized in that the additive as a powdery material before treatment is evenly sprinkled on the surface of the wear zone (Z) or placed as a sintered plate, the material used being in particular aluminum oxide, magnesium oxide, zirconium oxide or boron nitride. 5. The method according to any one of claims 2, 3 or 4, characterized in that the laser beam is guided over the wear zone (Z) with such an intensity and feed rate (vs) that the surface layer is briefly and just above up to 2 mm deep the melting temperature is heated. 6. The method according to claim 5, wherein the wear part has a flat surface as the wear zone, characterized in that the wear part is moved back and forth (sx) with transverse adjustments (sy) relative to the laser beam or vice versa at a feed speed (vs). 7. The method according to claim 6, characterized in that the transverse adjustment (Sy) is equal to or less than the diameter (d) of the surface layer melted by the laser beam. 8. The method according to any one of claims 2 to 7, characterized in that the wear part (50) having a flow opening (51) is treated in its flow opening wall (Z51) by an obliquely incident laser beam (52) which is relative to the wear part 5 10th 15 20th 25th 30th 35 40 45 50 55 60 65 5 9 CH 674 813 A5 10th or vice versa, is rotated about the central axis (54) of the opening and is guided to be height-adjustable along this axis. 9. The method according to any one of claims 2 to 7, characterized in that the wear part (50) having a flow opening (51) in its flow opening wall (Z51) by means of a laser beam deflected by a mirror (53) onto the flow opening wall (Z51) ) is treated, the mirror (53) in the flow opening (51) being rotated relative to the wearing part (50) or vice versa about the central axis (54) of the opening and being adjusted in height along the axis (54). 10. The method according to any one of the preceding claims, characterized in that the wearing part is preferably located between 50 and 100 mm away from the laser source and at a feed rate (vS) between 1 and 40 mm / s, with respective transverse adjustments (sy) between 0.5 and 2 mm and treated with an intensity of the laser beam between 1 and 50 kW / cm2, using a C02 laser. 11. The method according to claim 1, characterized in that it is compressed on the surface layer of the wear zone (Z) by chemical vapor impregnation (CVI). 12. The method according to claim 11, characterized in that the chemical vapor impregnation (CVI) with titanium nitride, titanium carbide and / or aluminum oxide. 13. The method according to claim 1, characterized in that it is compressed on the surface layer of the wear zone (Z) by plasma welding using a powder, for example alumina or magnesium oxide. 14. The method according to claim 1, characterized in that it is compacted on the surface layer of the wear zone (Z) by metal coating, for example cobalt, tungsten or molybdenum. 15. Wear part, obtainable by the method according to one of claims 1 to 14, characterized in that it consists of a ceramic material with a predominantly alumina-containing material, predominantly zirconium oxide or predominantly magnesium oxide. 16. Wear part, obtainable by the method according to one of claims 1 to 14, characterized in that it consists of a refractory concrete. 17. Wear part, obtainable by the method according to one of claims 1 to 7 or 10 to 14, which is designed as a slide or bottom plate of a slide closure with a sliding surface, characterized in that the sliding surface at least around the flow opening of approximately half the opening diameter is treated. 18. Wear part, obtainable by the method according to one of claims 1 to 7 or 10 to 14, which is designed as a slide or base plate of a slide closure with a sliding surface, characterized in that its sliding surface at least in that of the flow opening (33, 35, 37) of the opposite plate (34, 32, 36) from the fully closed to the fully open position of the closure area covered (Z32, Z34, Z36). 19. Wear part according to claim 17 or 18, characterized in that it is treated in the flow opening wall (Z35). 20. Wear part according to claim 17, 18 or 19, characterized in that the sliding surface of the slide or the base plate is ground after the surface layer treatment. 21. Wearing part according to one of the preceding claims 15 to 20, which has a refractory sleeve insert in its flow opening, characterized in that this sleeve insert (62) is treated at least on its upper end face (Z62) and preferably also in its flow opening (Z63). 22. Wear part, obtainable by the method according to one of claims 1 to 5 or 8 to 14, which is designed as an inlet or outlet sleeve, characterized in that it is treated at least in its flow opening (15, 22) in the upper region. 23. Wear part, obtainable by the method according to one of claims 1 to 5 or 8 to 14, which is designed as a pouring tube, characterized in that this pouring tube (38) in its flow opening (39) at least in its upper region (Z39) and / or in the outer area (Z38) which is in contact with the slag in a mold. 5 10th 15 20th 25th 30th 35 40 45 50 55 60 65