EP2733451B1 - Cooling element for metallurgical furnaces - Google Patents

Description

The invention relates to a cooling element for metallurgical furnaces, in particular shaft furnaces, for example blast furnaces, according to the features in the preamble of patent claim 1.

Cooling elements are used to protect the wall of the oven, such as a blast furnace, from overheating, as well as from abrasive wear, thermomechanical and thermochemical attacks. The installation of cooling elements on the inside of the furnace wall reduces or even prevents such attacks.

There are selectively acting cooling elements known, for. B. cylindrical or oval cooling tubes. There are so-called cooling boxes or cooling plates as well as the state of the art, such as area-covering cooling elements, so-called staves, which consist of various metallic materials, preferably steel, gray cast iron and copper. Also, combinations of punctual and area-covering cooling elements are known.

Protective layers are provided to protect the cooling element surfaces. These serve as wear and collision protection. They are made of refractory, unshaped and shaped ceramic materials in different thicknesses up to approx. 250 mm.

Further, inserts in receptacles, which are arranged on the furnace interior facing the hot side of the cooling plate, known. The shots are mostly grooves with an undercut. As a rule, they are dovetail-like grooves which accommodate both unshaped and shaped refractory materials, graphite, steel, cast steel or gray cast iron.

In metallurgical processes there is a high cost pressure due to changing raw material qualities and thus the need for flexible, process and procedural operations of the metallurgical furnaces, in order to come to competitive production prices per ton of molten pig iron. Therefore, in the future shaft furnaces with further increasing specific performances on the one hand, and / or decreasing ore, - coke and Möller quality on the other hand, operated. These operating conditions are not conducive to the previously known cooling elements, especially not for the blanket used unprotected copper staves in the cohesive range of shaft furnaces, because they are exposed to increased wear.

Strongly center-running operations of a blast furnace to achieve higher specific performance, for example, lead to temperature deficiencies at the inner blast furnace periphery, d. H. on the cooling elements made of copper. This leads to the penetration of partially unreduced ores and Möllerstoffen on the wall of the shaft furnace into the cohesive area z. B. blast furnaces. This is accompanied by a significant increase in wear due to abrasion on the cooling elements.

The actual task of the cooling elements, namely the freezing of a wear protection layer by high thermal conductivity of> 300W / mK, is no longer possible with partially unreduced Möllerstoffen on the cooling element hot side in the cohesive zone of a blast furnace. Due to the low abrasion resistance of cast or rolled copper cooling elements, it can Early lead to premature wear of the cooling plates, with the result that coolant-carrying channels suffer leaks.

Efforts by varying the use in the images of cooling elements, both in geometry and in the choice of materials, have so far been unsuccessful. For example, inserts of graphite, steel, steel and gray cast iron or refractory, coarse ceramic amorphous, unshaped and shaped products of different raw materials were used.

All these materials have a comparatively low thermal conductivity compared to copper and are therefore unable to freeze a protective layer on the surface of the cooling element. An increase in the abrasion resistance by various uses in the recordings of the cooling plate or a change in the coating on the cooling element surfaces taken alone has proven to be ineffective. Especially in the lower part of the cohesive zone of a shaft furnace, the so-called metallization zone, where in some cases very high process and operating temperatures and high heat flows with superimposed temperature and heat flow changes, the abrasion resistance could not be increased sufficiently.

The state of the art is on the DE 20 2010 011 142 U1 to point. It is proposed to provide a cooled furnace wall with corrosion protection bodies consisting of two different ceramic materials with different porosities. A base body is to be formed by an open-pore silicon carbide ceramic, preferably nitride-bonded silicon carbide, while the second ceramic material of the furnace inside arranged plate-shaped components by a dense silicon carbide, preferably reaction bonded, silicon-infiltrated silicon carbide (SiSic) is formed.

From the NL 8700293 A a lining of a furnace with a refractory material is known, wherein the refractory material z. B. consists of graphite. The refractory material is traversed inside by tubes through which a cooling medium is passed.

Towards the inside of the furnace, a further refractory material is arranged in groove-shaped recesses on the refractory material. The material may be silicon carbide.

The EP 0 008 261 A1 discloses a lining for smelting furnaces in which inside steel columns are cast in blocks of refractory material. These internal pillars have a high thermal conductivity and serve to deliver the heat from the interior of the refractory material to the furnace wall. This is intended to improve the service life of the refractory material. By the EP 1 069 389 A1 includes a water-cooled metal cooling element of the prior art, in which refractory profile components are arranged on a hot side facing the interior of the furnace. The refractory profile components are easily replaceable, whereby the life of the cooling element can be extended altogether.

Out J. Pause et al: "New fields of application for heat pipes, Hufenbach, WA (ed.): Proceeding of the International Colloquium of the Leading Edge Technology Cluster ECEMP 2010, TU Dresden 2010, pp. 215-225 It is known to use for heat pipes as a material selection for the heat exchanger SSiC and SiSiC. The silicon carbides are characterized by high abrasion resistance, mechanical strength and thermal shock resistance, as well as resistance to slagging and high thermal conductivity.

From the LU 88 629 a refractory brick lining for a cooling element of a blast furnace is known, wherein the bricks are anchored by means of fastening bolts in the cooling plate. As a material for the brick, inter alia, nitridically bonded silicon carbide is proposed.

Proceeding from this, the object of the invention is to provide a cooling element which has the ability to freeze and to obtain protective layers and at the same time has an increased abrasion resistance.

This object is achieved with a cooling element having the features of patent claim 1.

Advantageous developments of the invention are the subject of the dependent claims.

The cooling element according to the invention is characterized in that it comprises at least one profile component which is inserted into the receptacles on the hot side of the cooling plate in a positive, non-positive or cohesive manner. A profile component exists at least partly from a high-performance ceramic based on non-oxide-ceramic materials.

The so-called high-performance ceramic materials in the context of the invention are materials according to the standard DIN ENV 12212 (such as, for example, silicon-infiltrated, reaction-bonded silicon carbide, abbreviation SBSiC). With these materials, it is possible to solve the above problem. In particular, it is possible that the operator of a metallurgical furnace, in particular a blast furnace, is not forced, proven modes of operation, for. B. middle-rate driving with higher specific pig iron production rates, in favor of longer life of the cooling elements give up or change.

Another advantage is that the cooling elements in their basic structure also need not be changed. Rather, novel profile components from at least partially, in particular on the outside, high-performance ceramic materials are used. These materials can be produced by continuous casting. Preferably, they have a thermal conductivity of more than 120 W / mK. The thermal conductivity is in particular in a range of 120 to 150 W / mk. In addition, they are characterized by high fire resistance up to 1550 ° C. At the same time they are extremely temperature change resistant. The abrasion resistance is preferably in a range <0.5 cm ³ (ASTM C 704).

The sum of these main characteristics of high performance ceramics is required to render copper cooling elements insensitive to abrasive wear, particularly in the cohesive zone of shaft furnaces such as blast furnaces, and to provide natural protective layers for self-protection due to the high levels of resistance Freeze on Wärmeleitzahlen.

The said profile components made of at least partially high-performance ceramic materials can be used not only in cooling elements made of rolled materials, but also in cast cooling elements.

The high-performance ceramic materials belong to the group of non-oxide-ceramic materials based on SiC.

The profile components can be full or open profiles.

Preferably, it is hollow profiles. A hollow profile according to the invention is in particular a circumferentially closed hollow profile.

Such hollow profiles can be produced easily in a continuous casting process and also save material. It is therefore possible to use hollow profiles, which are additionally provided on the inside with a refractory material. The refractory material is in particular a self-flowing, amorphous-ceramic, unshaped refractory SiC material, in particular the low-cement group, so-called LCC concretes (LCC = low cement castables).

The mass is also resistant to wear and easily processed as a self-fluxing material, so that cavities within the profile component can be completely poured or filled. The mass is cured after casting.

In the context of the invention, it is also possible to arrange several profiles nested. Should the outer hollow section be damaged, the wear-resistant refractory material will come into contact with the interior of the blast furnace. Another profile inside the outer hollow profile can act here supportive. It may have the positive material properties of the outer hollow profile and in particular protect against abrasive wear, but at the same time preferably have the very high thermal conductivity and said refractoriness. In this sense, several profiles can be arranged nested. This does not have to be hollow profiles for all profiles. It is conceivable, however, that all profiles which are arranged nested, are formed in their cross-sectional area congruent. Inner profiles may preferably be made of the same material as the outer hollow profile.

Of course, it is possible that the inner profile is also a component without a hollow structure. A hollow structure according to the invention refers to a circumferentially open or closed contour. Of course can also be U-shaped, Z-shaped, S-shaped or provided in other ways multi-armed profiles. Such arms provided with arms can also be combined with a hollow profile, for example by a circular or polygonal core is designed as a hollow profile, are arranged on the outside virtually quasi radially projecting arms. The arms then extend in the direction of the outer hollow profile. The reverse arrangement is conceivable, namely the arms protrude from the outer hollow profile to the interior of the hollow profile. Arms according to the invention are webs or continuous projections, as they can be easily produced by the continuous casting process. The wall thickness of the profiles or hollow profiles can vary widely over the circumference of a profile. The invention is therefore not limited to a particular profile geometry. Decisive is that the profile component has a total of a very high thermal conductivity and protects against abrasive wear.

If a plurality of nested profiles are present, it is provided that the spaces between the profiles and the hollow profile are filled by a refractory material, so that the entire surrounding of the outer hollow profile interior is filled.

Also, a gap between the receptacle and the profile component may be filled with the refractory material. As a result, the heat transfer between the profile component and the recording is additionally improved.

The refractory material in or between the profiles is in particular a non-oxide ceramic material. As described above, the refractory materials for filling gaps and spaces are a self-flowing, that is castable, amorphous ceramic, unshaped, refractory SiC material, preferably the group LCC (low cement castable). Through this material, the various profiles are connected and anchored.

The refractory, unshaped material can also consist of a mixture of recycled high performance ceramics, in particular RBSiC high performance ceramics and a refractory, non-oxide ceramic SiC mass which is particularly low in cements (Group LLC).

In contrast, at least one of the profiles preferably consists of a refractory material of group HA65. This material is for example a high alumina, refractory material with at least 65% Al2O3 content.

The profile component, which comes into contact with the receptacle of the cooling plate, is preferably trapezoidal in cross section. It may protrude a piece from the cooling element. The outer profile component may have an undercut in its region protruding from the receptacle of the cooling plate. This undercut can serve to provide a positive anchoring of a refractory wear protection layer. This can be applied at the factory or also form during operation, so that even for forming, frozen wear protection layers anchoring is provided.

In addition, alternately other materials can be used in the recordings, such as full ceramic inserts. These can be used alternately with the profile components according to the invention, wherein it is not absolutely necessary to observe the same subsequence of alternating profile components over the entire cooling element. The subsequences of profile components and ceramic inserts may vary.

Figur 1

einen Längsschnitt durch ein Kühlelement in Form eines Kupferstaves mit teilweise eingesetzten Profilbauteilen;

Figur 2

einen Längsschnitt durch eine weitere Ausführungsform eines Kühlelements in Form eines Gussstaves mit teilweise eingesetzten Profilbauteilen;

Figur 3

ein Profilbauteil im Querschnitt;

Figur 4

eine weitere Ausführungsform eines Profilbauteils im Querschnitt;

Figur 5

eine weitere Ausführungsform eines Profilbauteils im Querschnitt;

Figur 6

eine weitere Ausführungsform eines Profilbauteils im Querschnitt;

Figur 7

eine weitere Ausführungsform eines Profilbauteils im Querschnitt;

Figur 8

eine weitere Ausführungsform eines Profilbauteils im Querschnitt;

Figur 9

einen Teilschnitt durch ein Kühlelement einer weiteren Ausführungsform mit verankerter Verschleißschutzschicht;

Figur 10

einen weiteren Teilschnitt durch ein Kühlelement mit verankerter Verschleißschutzschicht;

Figur 11

einen Teilschnitt durch eine weitere Ausführungsform eines Kühlelements mit eingesetzten Profilbauteilen;

Figur 12

einen Teilschnitt durch eine weitere Ausführungsform eines Kühlelements mit eingesetzten Profilbauteilen und Befestigungselementen und

Figur 13

einen Teilschnitt durch ein Kühlelement mit einem offenen Profil eines Profilbauteils.

The invention will be explained in more detail with reference to embodiments shown in the drawings. Show it:

FIG. 1

a longitudinal section through a cooling element in the form of a copper stator with partially inserted profile components;

FIG. 2

a longitudinal section through a further embodiment of a cooling element in the form of a cast-iron with partially inserted profile components;

FIG. 3

a profile component in cross section;

FIG. 4

a further embodiment of a profile component in cross section;

FIG. 5

a further embodiment of a profile component in cross section;

FIG. 6

a further embodiment of a profile component in cross section;

FIG. 7

a further embodiment of a profile component in cross section;

FIG. 8

a further embodiment of a profile component in cross section;

FIG. 9

a partial section through a cooling element of another embodiment with anchored wear protection layer;

FIG. 10

a further partial section through a cooling element with anchored wear protection layer;

FIG. 11

a partial section through a further embodiment of a cooling element with inserted profile components;

FIG. 12

a partial section through a further embodiment of a cooling element with inserted profile components and fasteners and

FIG. 13

a partial section through a cooling element with an open profile of a profile component.

FIG. 1 shows a cooling element 1 a, which on a wall, the so-called tank 2 of a metallurgical furnace, not shown, in particular a shaft furnace, such. B. a blast furnace, is attached. The cooling element 1 a comprises a cooling plate 3 a, with coolant channels 4 extending in the interior, which are supplied with coolant via coolant connections 5, 6 on a cold side of the cooling plate 3 a in a manner not shown. The coolant connections 5, 6 pass through the wall 2. A fastening element 7 serves to fix the cooling element 1 a to the tank 2.

On the inside of the furnace facing hot side, that is in the image plane right, are located on the cooling plate 3a groove-shaped receptacles 8, which are each bounded by webs 9. In this embodiment, the groove-shaped receptacles 8 extend horizontally. The groove-shaped receptacles 8 preferably have a dovetail-shaped cross-section.

The groove-shaped receptacles 8 serve to receive profile components 10a. The profile components 10a are produced by continuous casting. They consist of a high-performance ceramic. They are adapted in their cross section to the contour of the receptacle 8 and are held in a form-fitting manner in the receptacle 8. The profile components 10a protrude a short distance over the hot side of the webs 9, so that the surface 11 of the cooling plate 3a set back from the profile components 10a is protected from abrasive wear.

FIG. 2 shows a further embodiment, for example, a Gußstave cooling element 1 b with profile components 10b, which are arranged in groove-shaped receptacles 8 a cooling plate 3b. For example, the cooling element 1b is made of gray cast iron. With regard to the arrangement of the grooves 8, 9 and the geometry of the profile elements 10b is to the comments too FIG. 1 Referenced. Identical components were provided with the already introduced reference numerals.

The special feature of the cooling elements 1 a and 1 b the FIGS. 1 and 2 are the profile components 10a, 10b used there. FIG. 3 shows in a detailed representation of the basic shape of such a profile component 10a. The profile component 10a has a multi-part construction. It comprises a hollow profile 12. In this embodiment, it is trapezoidal in cross section. The hollow section 12 is closed circumferentially. It has a filling of a refractory material 13th

The profile element 10a therefore consists of two different materials. The hollow profile 12 made of high-performance ceramic materials produced by continuous casting is characterized by extremely high abrasion resistance and very high thermal conductivities of up to 150W / mK and also by extremely high refractoriness up to 1550 ° C and high thermal shock resistance. It consists of a high-performance ceramic material, for example silicon-infiltrated, recrystallized silicon nitride.

The refractory material 13 consists of a self-fluxing in the processing state, amorphous-ceramic, unshaped, refractory material. This SiC mass belongs to the group LCC (low cement castable). This refractory material 13 can also be used to anchor other profiles that are located within the outer hollow section 12.

FIG. 4 shows a profile member 10c, in turn, that of FIG. 3 known outer hollow section 12 includes, but in addition a further, internal profile 14 has. The inner, hollow profile 14 may have a smaller wall thickness and additionally has arms 15 which point from the corners of the substantially rectangular or trapezoidally configured inner profile 14 to the corners of the outer hollow profile 12. The spaces are in turn filled with the refractory material 13, as it is also in FIG. 3 is shown. As a result, the core, ie the interior of the profile component 10c, is additionally made even more wear-resistant and even more thermally conductive.

FIG. 5 shows an alternative embodiment of a profile component 10d. Notwithstanding the embodiment of the FIG. 4 has the inner profile 16 in addition to the arms 15 in the corners more arms 17 in the region of the upper and lower longitudinal side of the profile designed as a hollow profile 16. All remaining spaces are in turn filled with the refractory material 13.

The embodiment of the FIG. 6 shows a profile component 10e, which in turn comprises the outer hollow profile 12 and additionally an inner profile 18. They are both trapezoidal in cross section, so that the inner profile 18 is substantially equidistant from the walls of the outer profile 12. The interstices are in turn filled with the refractory material 13, as well as the interior of the inner profile 18th

FIG. 7 shows an embodiment of a profile component 10f, which, in contrast to the embodiment of the FIG. 6 still a third profile 19 includes, which in turn is surrounded by the middle profile 18 and the outer hollow section 12. The profiles 12, 18, 19 are spaced equidistant, resulting in a multiple interleaving. On the explanation of the FIG. 12 is referred to. Interspaces are in turn filled with the refractory material 13, as well as the interior of the inner profile 19th

FIG. 8 shows a variant of a profile component 10g, in which the outer hollow profile 12 receives an inner profile 20, which is not a hollow profile unlike in all previous embodiments. It includes a horizontal bar. From the horizontal web go up and down from each three transverse webs, so that the shape of two adjacent letters H results. The gaps are in turn filled with the refractory material. The outer webs of the profile 20 are slightly inclined relative to the vertical direction of the central web, so that there is a constant distance to the outer hollow member 12 in the region of the outer webs.

FIG. 9 shows an application in which a cooling element 1 c is shown in partial section. The special feature of this cooling element 1 c is that two different types of profile components 10a, 10h are used alternately. The profile element 10h further projects beyond the hot side of the cooling plate 3c so that it grips into a wear protection layer 21 and anchors it to the hot side of the cooling plate 3c. For this purpose, the profile component has 10h on both sides undercuts, which in the representation of FIG. 9 extend into the picture plane. In other words, the profile component 10h from the groove bottom to Nutmündung forth in adaptation to the dovetail shape of the groove younger and widened in the same way and at the same distance from the groove again. This creates an hourglass-shaped constriction, behind which the wear-resistant layer 21 can dig in a form-fitting manner. Also, the profile member 10h is filled with the refractory material 13, as is the case with the above embodiments.

The embodiment of the FIG. 10 differs from the previous one in that instead of the profile components 10a solid, amorphous ceramic, abrasion-resistant, shaped refractory profile components 22 of material group HA65 or non-oxide ceramic SiC grades are used alternately to the profile components 10a in the grooves of the cooling plate 3d. Also in this embodiment is a wear protection layer 21 on the hot side of the cooling plate 3d. In addition, the explanation of the FIG. 9 Referenced.

FIG. 11 shows an embodiment of a cooling element 1 e, which differs from that of the FIG. 1 differs in that slightly smaller profile components 10i are used in the cooling plate 3e in cross-section, which are still held in a form-fitting manner in the dovetail-shaped undercut receptacles 8. The resulting gap between the profile components 10i and the receptacles 8 is filled with a refractory adhesive material 24. One can speak here of a high temperature bonding technique. The temperature-resistant ceramic adhesive material is based on polymer.

FIG. 12 finally shows in addition to FIG. 11 , the back of the cooling plate 3f fasteners 23 are used, which point in the direction of the hot side of the cooling plate 3f and the profile components 10i anchored in the receptacles 8 additionally. In this exemplary embodiment, these are screw connections, which are respectively arranged centrally behind one of the receptacles 8 or off-center, so that each individual profile component 10i is anchored.

Of course, all other of the profile components described above can also be anchored in this way in addition to the cooling plate, so that a frictional, positive and cohesive anchoring to the cooling element is possible. Alternatively, each of the anchoring forms can be realized individually.

FIG. 13 shows an open profile member 10j, unlike the closed profile components 10a - i is not located exclusively between the webs 9, but each embraces a web 9. The webs 9 have on both sides undercuts, wherein the open profile component 10j squeezes into the undercuts and is thereby held in a form-fitting manner on the respectively engaged web 9. The webs 9 are trapezoidal in cross-section, so that the profile components 10j are trapezoidal with a constant wall thickness.

Reference numerals:

1a -

cooling element

1b -

cooling element

1c -

cooling element

1d -

cooling element

1e -

cooling element

1f -

cooling element

2 -

tank

3a -

cooling plate

3b -

cooling plate

3c -

cooling plate

3d -

cooling plate

3e -

cooling plate

3f -

cooling plate

4 -

Coolant channel

5 -

Coolant connection

6 -

Coolant connection

7 -

fastener

8th -

groove-shaped recording

9 -

web

10a -

profile component

10b -

profile component

10c -

profile component

10d -

profile component

10e -

profile component

10f -

profile component

10g -

profile component

10h -

profile component

10i -

profile component

10y -

profile component

11 -

surface

12 -

closed hollow profile

13 -

refractory material

14 -

profile

15 -

poor

16 -

profile

17 -

poor

18 -

profile

19 -

profile

20 -

profile

21 -

Wear protection layer

22 -

profile component

23 -

fastener

24 -

ceramic adhesive material

Claims (19)

1. Cooling element for metallurgical furnaces, having a metallurgical cooling plate (3a - f) having coolant channels (4) running in the interior, to which fire-resistant profile components (10a - j, 22) are fastened, which catch in receivers (8) which are arranged on the hot side of the cooling plate (3a - f) facing towards the interior of the furnace, characterised in that at least one profile component (10a - j) consists at least partially of a high-performance ceramic based on non-oxide ceramic materials.
2. Cooling element according to claim 1, characterised in that the high-performance ceramic has a thermal conductivity of at least 120 W/mK to freeze on a protective layer and has a fire resistance up to 1550°C.
3. Cooling element according to claim 2, characterised in that the thermal conductivity ranges from 120 to 150 W/mK.
4. Cooling element according to any one of claims 1 or 3, characterised in that at least one profile component (10a - i) comprises at least one hollow profile (12).
5. Cooling element according to claim 4, characterised in that the hollow profile (12) consists of the abrasion-resistant, highly thermally conductive, high-performance ceramic.
6. Cooling element according to claim 4 or 5, characterised in that a fire-resistant material (13) is arranged within the hollow profile (12).
7. Cooling element according to any one of claims 4 or 5, characterised in that several profiles (14, 16, 18 - 20) and hollow profiles (12) are arranged nested one inside the other.
8. Cooling element according to claim 7, characterised in that the profiles (14, 16, 18 - 20) consist of the abrasion-resistant, highly thermally conductive, high-performance ceramic.
9. Cooling element according to claim 6 or 7, characterised in that at least one of the inner profiles (14, 16, 18, 19) is a hollow profile.
10. Cooling element according to any one of claims 7 to 9, characterised in that at least one of the profiles (14, 16, 20) has arms (15, 17) which extend from the wall of the one profile (14, 16, 20) in the direction of the wall of another profile (14, 16, 20) or hollow profile (12).
11. Cooling element according to any one of claims 7 to 10, characterised in that a fire-resistant material (13) is arranged in the intermediate spaces between profiles (12, 14, 16, 18 - 20) which are nested one inside the other, such that the entire interior surrounded by the outer hollow profile (12) is filled.
12. Cooling element according to any one of claims 6 to 11, characterised in that the fire-resistant material (13) in or between the profiles (14, 16, 18 - 20) and the hollow profile (12) is a non-oxide ceramic material.
13. Cooling element according to any one of claims 1 to 12, characterised in that a gap between the groove-shaped receiver (8) and the profile component (10i, j) is filled with a fire-resistant ceramic adhesive (24).
14. Cooling element according to any one of claims 1 to 13, characterised in that the profile component (10a - -j) has a trapezoidal cross-section.
15. Cooling element according to one of claims 1 to 14, characterised in that the profile component (10i) has an undercut in its region protruding from the groove-shaped receiver (8) of the cooling plate (3c), for positive anchoring of a fire-resistant wear protection layer (21).
16. Cooling element according to any one of claims 1 to 15, characterised in that profile components (10a - i) with hollow profiles and the full-ceramic profile components (22) are arranged alternately in the groove-shaped receivers (8).
17. Cooling element according to any one of claims 1 to 16, characterised in that the profile components (10i) are anchored positively to the cooling plate (3f) via additional fastening elements (23).
18. Cooling element according to any one of claims 6 to 17, characterised in that the fire-resistant, unformed material (13) consists of a mixture of recycled RBSiC high-performance ceramic and a fire-resistant, non-oxide ceramic SiC compound.
19. Cooling element according to any one of claims 1 to 18, characterised in that the high-performance ceramic has an abrasion resistance according to ASTM C 704 of <0.5cm³.

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