DE102009020325B3 - Use of a molded product of refractory ceramic material - Google Patents

Abstract

The invention relates to a molded product of refractory ceramic material.

Description

The The invention relates to the use of a molded product fireproof ceramic material.

Fireproof ceramic material is used in particular for such products, which are exposed to high temperatures. For example, immersion spouts are made refractory ceramic material used in steel production.

To reduce the content of oxygen (O ₂ ) in the molten steel, it is known to introduce aluminum (Al) into the molten steel. The Al reacts with the O _{2 of} the molten steel to Al ₂ O ₃ and thereby reduces the O ₂ content in the melt. Correspondingly manufactured steels are referred to as aluminum killed (Al killed) steels.

Parts of the Al ₂ O ₃ formed in Al-killed steels may be deposited on the refractory ceramic material with which the molten steel comes into contact. This phenomenon is also called clogging.

Problematic is such a clogging especially with regard to such sections of refractory ceramic material used for casting a Serve aluminum-tempered steel melt.

Especially Clogging is problematic with immersion spouts, because the clogging is here to a change, in particular a constriction, the free cross section of the immersion nozzle leads, what the flow characteristics the molten steel in the immersion nozzle adversely changed.

It has therefore not lacked attempts to clogging in the past in immersion spouts too prevent or at least reduce.

In EP 1 541 259 A1 For example, an immersion nozzle is proposed whose refractory material contains at least 20% of a CaO component. Via intermediate steps, in which, in particular, CaCO ₃ decomposes into CaO and CO ₂ , this CaO component leads to the formation of Al ₂ O ₃ and C on the surface of the immersion nozzle. It is found to be advantageous in this document that the Al ₂ O _{3 formed} with CaO forms meltable substances on the surface, which smoothes them and thus prevents an attack of Al ₂ O ₃ . The disadvantage here, however, is that in this approach additional Al ₂ O _{3 is} formed, which can also be reflected on the surface of the immersion nozzle.

A similar mechanism will be used in EP 0 472 350 A1 proposed, wherein the refractory material contains there CaO portions in the form of dolomite.

It is also known from the prior art to provide a ceramic material for an anti-clogging immersion nozzle containing binder in the form of a calcium aluminate (Ca-Al cement) cement. Such a Ca-Al cement forms low-melting phases upon contact with the molten steel. These low-melting phases therefore form regions of molten refractory material at the contact surface between molten steel and immersion nozzle, which form a "sliding film" in the area of contact between molten steel and immersion nozzle. On this sliding film formed in the molten steel Al ₂ O ₃ does not stop and therefore does not settle on the refractory material. However, a suitably assembled immersion nozzle must have considerable proportions of Al-Ca cement in order to form the said lubricating film in an amount sufficient to effectively suppress clogging. Typically, the proportions of Ca-Al cement in corresponding immersion spouts are above 15% by mass. The disadvantage of this is that correspondingly high proportions of Ca-Al cement in a submerged nozzle lead to a deterioration of its refractory properties. In particular, the refractoriness and thus the life of the immersion nozzle are thereby worsened.

Of the present invention is based on the object, a molded Product of refractory ceramic material available For a good anti-clogging properties and for a other good refractory properties at the same time.

The solution This object is the use of a molded product made of refractory ceramic material according to claim 1 for the casting of Aluminum-tempered steel melts.

In the US 4,760,038 A describes a refractory ceramic filter whose material consists of Ca-stabilized ZrO ₂ and Al ₂ O ₃ . The material mixture should be stable and form little to no melting phase.

The invention is based on the following basic considerations: Basically, clogging can be effectively prevented by producing a lubricating film of melt phases at the contact surface between the Al-killed molten steel and the product. However, it is necessary to prevent the lubricating film-forming material, Ca-Al cement in the art, from adversely affecting the refractory properties of the product. The invention is based on the basic idea, one such, a sliding film of low Although it does provide for phase-producing material, it does, at least not exclusively, already exist in the pre-fabricated product. Rather, this substance should at least partially be formed only when the product is used, ie when the product comes into contact with a molten steel.

There the substance that forms low-melting phases, at least sometimes only when the product is being used product according to the invention be provided with excellent refractory properties. Because the product does not need to contain Ca-Al cement in such an amount which negatively affects the refractory properties of the product.

The Product can basically in the form of any refractory product in steelmaking Use find, preferably in the form of a dip spout or a pouring nozzle for the production aluminum killed steel, or as part, for example or component of the aforementioned components. The product Can be widely used as a functional product for flow control applications used in steel metallurgy.

in the Trap of a molded product in the form of a dip spout The substance forms from the first and second refractory ceramic Material therefore when the molten steel through the immersion nozzle flows. This substance has a melting point at a temperature which are below the temperature of the melting point of the first and second refractory ceramic component is located. This ensures that the use of the product alone results in the formation of a melt phase in the formed material and not in the refractory ceramic components of the Produce comes.

The refractory ceramic material of the product includes ceramic Basic components, in particular the first and the second component made of refractory ceramic material, and optionally further Components made of refractory ceramic material. For these basic components it may in particular be oxidic, inorganic ceramic Basic components act. In addition, the refractory ceramic material the product contain other components, such as refractory Cements or other components, such as binders or Dispersant.

Around to form the said substance when the product comes into contact forms a low-melting phase with a molten steel, are the product a first component of refractory material ("first Component") and a second refractory material component ("second Component") intended. According to the invention, it is provided the first component contains a proportion of a metal ("diffusible Metal") having. Under the influence of temperature, this diffusible Metal diffuse to the second component to get along with this to form a substance ("substance"). To initiate this diffusion process, the second one points Component a proportion of the diffusible metal in a concentration which is below the concentration of the diffusible metal in the first component lies. Diffused due to this concentration gradient the diffusible metal under the influence of temperature from the first to the second component.

The For example, diffusible metal may be in the first component in oxide form. In the diffusion process by which the Diffused metal diffuses from the first to the second component, it may in particular be a solid-state diffusion. at the diffusible metal is then diffusible Metal ions, but also referred to herein as a "diffusible metal" become.

The Formation of the substance by means of a diffusion process has the other Advantage that the amount of substance that diffuses from the Metal and the second component in the application of the product should be formed, is very accurate adjustable. Because the educated Substance quantity essentially of the factors of the diffusion process depends can by adjusting the factors of the diffusion process the amount of fabric formed can be adjusted. The factors of Diffusion process are in particular the concentration of the diffusible Metal in the first and second components (in other words: the concentration gradient the diffusible metal from the first to the second component), the respective proportions of the first and second components of the refractory ceramic material of the product as well as the temperature at which the diffusion process takes place. In particular, the factors determining the diffusion process can be adjusted so that when using the product always only such an amount is formed on said substance, which is necessary to obtain a sufficient amount of low-melting To form phases. This prevents a significant excess on the formed substance or on melt phases in the product which negatively affects the refractory properties of the product could influence.

The fact that the diffusion process of the diffusible metal takes place "under the influence of temperature" means that this diffusion process takes place at the application temperature of the product. In the event of In the case of a product in the form of an immersion nozzle, this temperature of application is the temperature which the product assumes when molten steel flows through the spout, that is to say a temperature usually in the range of 1,600 ° C to 1,650 ° C. In general, the diffusion process in the product, for example, under a temperature effect in the range between 1200 ° C and 1800 ° C take place.

There the effect of temperature on the product, in particular on its Hot side, that is, for example, the one in contact with a molten steel Areas, is regularly higher than in his rest In the application of the product, it may cause a temperature gradient in the product come. This may cause the temperature to rise when the product is used for example, alone in the hot side of the product adjacent Areas of the product be so high that it causes a diffusion of the diffusible metal comes. In other areas of the product a diffusion of the diffusible metal then not or only in small extent. This is another significant advantage of the product. Because they are due to the diffusion process forming, low-melting phases form there alone, where she needs that is, in the contact area of the product with the molten steel.

Of the formed from the diffusible metal and the second component Fabric has a melting point at a temperature below the temperature of the melting point of the first and second components lies. In case of using the product as immersion nozzle for al-calmed steels For example, the formed fabric preferably has a melting point at one Temperature below the temperature of molten steel, usually 1650 ° C is. The formed substance preferably has a melting point in the temperature range between 1,200 ° C and 1,800 ° C, particularly preferably in the temperature range between 1,300 ° C and 1,650 ° C on.

Of the formable from the diffusible metal and the second component The substance does not have to be a uniform, homogeneous substance. For example the formed substance may be a mixture of substances, the compositions each having different proportions of the having diffusible metal and second component, for example a Solid solution. The diffused metal and the second Accordingly, the component formable substance does not have to have a single, uniform melting point exhibit; rather, you can certain areas of the substance, depending on their composition, Have melting points at very different temperatures. These melting points can partly, for example, above the temperature of the melting point of the first and second components lie. All in all, at least alone a melting point of the formed substance have a temperature, which are below the temperature of the melting point of the first and second Component lies.

As noted above, prior anti-clogging products have components which react with the Al of the Al-killed molten steel to form Al ₂ O ₃ and thus "consume" aluminum from the molten steel. In order to suppress this effect in the product, it is provided that the diffusible metal in the electrochemical voltage series is below aluminum. This ensures that the diffusible metal is a stronger reducing agent than aluminum. The oxygen affinity of the diffusible metal is therefore higher than that of the aluminum and it forms a "more stable" oxide than aluminum. Such diffusible metals are, for example, Ca, sodium (Na) or potassium (K).

It can be provided that the second component no share having the diffusible metal, or at most very small Quantities, such as impurities. For example, the Shares of the diffusible metal in the second component less than 1 mass%, based on the mass of the second component. hereby let yourself so a particularly high concentration gradient at the diffusible Create metal between the first and second components.

Of the For example, the proportion of diffusible metal in the first component may be based on the mass of the first component, over 1% by mass, ie for example, too 2% by mass or above 3% by mass and, for example, less than 30% by mass, for example also below 25% by mass. Accordingly, the proportion of diffusible Metal in the first component, for example, between 1 and 30 Mass% lie. Particularly preferably, the proportion of diffusible Metal in the first component, for example, between 3 and 25 Mass% lie.

Of the For example, the proportion of diffusible metal in the product can be based on the mass of the product, over 0.1% by mass, so for example also over 0.2% by mass or above 0.4% by mass and, for example, less than 10% by mass, for example also below 8% by mass or below 6% by mass. Accordingly, the proportion on diffusible metal in the product, for example, between 0.1 and 10% by mass. Particularly preferably, the proportion of diffusible Metal in the product, for example, between 0.4 and 6% by mass.

The herein given in terms of mass% with respect to the diffusible Metal refer to its mass in its oxide form, as in the refractory technology usual.

It can be provided that the proportion of the first component in Product, by weight of the product, eg more than 1% by mass is, for example, also over 5% by mass, over 8% by mass, over 15% by mass, over 30% by mass, over 40% by mass or over 50% by mass and for example less than 65% by mass, so for example also below 62% by mass, below 40% by mass, below 30% by mass or below 25% by mass. Accordingly, the proportion of the first component in the product for example, between 1 and 65% by mass. In particular, then if the product is not a priori at the application temperature Having melt phase-forming component, ie in particular no Ca-Al cement, the proportion of the first component in the product preferably, for example, below 30% by mass or below 25% by mass lie. Otherwise, the proportion of the first component in the product prefers for example over 40% by mass or over 50% by mass lie.

Of the Share of the second component in the product, relative to the product Mass of the product, for example, can be over 30% by mass, ie for example, too 35% by mass, over 50% by mass, over 60% by mass or above 70% by mass and, for example, less than 99% by mass, for example also below 95% by mass, below 90% by mass, below 85% by mass below 80% by mass below 60% by mass, below 50% by mass or below 45% by mass. Accordingly, the proportion of the second component in the product for example, between 99 and 30% by mass. In particular, then if the product is not a priori at the application temperature Having melt phase-forming component, ie in particular no Ca-Al cement, the proportion of the second component in the product may be preferred, for example, below 60% by mass, less than 50% by mass or less than 45% by mass. Otherwise For example, the proportion of the first component in the product may be more than 50% by mass, over 60% by mass. or over 70 Mass% lie.

Particularly preferred is a diffusible metal in the form of calcium (Ca) or calcium ions (Ca ²⁺ ) is provided. Diffusible Ca is, as usual in refractory technology, subsequently also indicated and represented in its oxide form as CaO.

CaO is on the one hand in the electrochemical voltage series below aluminum. On the other hand, CaO together with other components, for example aluminum or Al ₂ O ₃ -containing components, forms substances with a low melting point, in particular a melting point which is below the temperature of an Al-killed molten steel.

In particular, a particular advantage of a diffusible metal in the form of CaO is that this CaO can form low-melting phases with the Al ₂ O ₃ forming in the Al-killed molten steel and coming into contact with the surface of the product. see CaO-Al ₂ O ₃ phase diagram according to 1 , Due to the Ca concentration gradient from the first component to the molten steel, the CaO diffuses during use of the product (also) from the first component to the contact surface between the product and molten steel and forms there with the Al ₂ O ₃ molten steel melt phases, for further Al ₂ O _{3 of} the molten steel, as stated above, act as a sliding film on which Al ₂ O _{3 of} the molten steel does not find support. Clogging can be suppressed.

According to a particularly preferred embodiment, the product has a first component in the form of Ca-stabilized Zro ₂ . In a Ca-stabilized ZrO ₂ , the Ca is the metal which diffuses under the influence of temperature. An advantage of a suitably designed first component is that the Ca concentration can be set very precisely therein. As a result, the diffusion process of the CaO at a certain temperature is easily determinable and the amount of material formable from CaO and the second component can be easily adjusted.

As far as Ca-stabilized ZrO _{2 is provided} as a first component, the Ca in ZrO _{2 is} preferably present in a proportion that it - especially at the application temperature of the product - is completely incorporated into the ZrO ₂ . The ZrO ₂ -CaO phase diagram is in 2 shown. At the application temperatures of the product (see above), CaO may be fully incorporated into the tetragonal or cubic ZrO ₂ crystal lattice to a level of about 20-24 mass%. Only at higher CaO concentrations does a two-phase region of cubic ZrO ₂ and CaZrO ₃ arise. Accordingly, the proportion of CaO in the Ca-stabilized ZrO _{2 is} preferably below 25 mass%, based on the mass of Ca-stabilized ZrO ₂ , that is, for example, also below 20 mass% or below 15 mass% and preferably above 2 mass%. %, that is, for example, over 3% by mass, over 6% by mass or over 8% by mass. Thus, the proportion of CaO in the Ca-stabilized ZrO _{2 can be,} for example, between 3 and 25% by mass.

The product may preferably have a second Component in the form of at least one of the following substances: Al ₂ O ₃ or compounds of Al ₂ O ₃ and other metal oxides. Al ₂ O ₃ may, for example, be in the form of corundum, for example in at least one of the following forms: sintered corundum or fused corundum. Compounds of Al ₂ O ₃ and other metal oxides may be, for example, compositions of the system Al ₂ O ₃ -MgO, for example spinel (MgAl ₂ O ₄ ).

In the case of a diffusible metal in the form of CaO and a second component in the form of Al ₂ O ₃ (or Al ₂ O ₃ compounds), a substance can therefore be formed from CaO and Al ₂ O ₃ , in particular CaAl ₂ O ₄ . The formation of such a substance is particularly advantageous since compositions of the system CaO-Al ₂ O ₃ form melt phases even at temperatures significantly below 1650 ° C. (ie the usual temperature of a molten steel).

As can be seen from the attached phase diagram of the system CaO-Al ₂ O ₃ , below 1,650 ° C, compounds of CaO and Al ₂ O ₃ can form liquid melt phases when the concentration of Al ₂ O ₃ in the compositions of CaO and Al ₂ O _{3 is} about 30 to 55 mol%. In the case of a diffusible metal in the form of CaO and a second component in the form of Al ₂ O ₃ , therefore, melt phases can only be formed from the formed substance in the article when such an amount of CaO has diffused to Al ₂ O ₃ that the Concentration of Al ₂ O ₃ there below 55 mol% decreases. This diffusion process leads to a very uniform, continuous formation of material or melt phase formation, since not at the first contact of CaO with Al ₂ O ₃ directly form melt phases, but only when a certain amount of CaO is diffused to Al ₂ O ₃ .

The first component may be in the form of granular material, for example be present, for example in a grain size ≥ 0.02 mm, so for example in a particle size ≥ 0.05 mm, ≥ 0.1 mm or ≥ 0.15 mm, and, for example, in a grain size ≤ 3 mm, so for example in a particle size ≤ 2 mm, ≤ 1 mm or ≤ 0.5 mm. Therefore For example, the first component may be present in a particle size ≥ 0.02 and ≦ 2 mm. The advantage of a first component in the form of granular material lies in particular in the fact that the diffusion of the diffusible metal runs very evenly and therefore it is easy to adjust.

The second component may, for example, in at least one of the following Forms are: granular Good or flour. As far as the second component in the form of granular material is present, this may for example be in a particle size ≥ 0.02 mm, So for example, in a grain size ≥ 0.1 or ≥ 0.5 mm or ≥ 1 mm, and for example in a grain size ≤ 10 mm, ie for example, in a grain size ≤ 8 mm, ≤ 6 mm, ≤ 5 mm or ≤ 3 mm. Accordingly, the second Component, for example, in a particle size ≥ 0.5 and ≤ 3 mm. As far as the second Component is present in the form of flour, this may for example in a particle size below 100 μm are present So for example, in a particle size less than 40 microns.

It may be provided in particular that the second component both in the form of granular Good as well as in the form of flour. For example, 10 up to 40% by mass, ie for example also 15 to 35% by mass of the second component, based on the mass of the product, present as a flour.

In addition to the first and the second component, the product may comprise at least one further component of refractory ceramic material ("further component"), for example at least one further component of refractory ceramic material in the form of at least one of the following oxides or compounds thereof: MgO, ZrO ₂ ,

It can be provided that at least one further component is present in the form of a refractory cement or in the form of a forming at the application temperature of the product melt phases component, for example in the form of a refractory Ca-Al cement (CaO-Al ₂ O ₃ cement). This Ca-Al cement may be a cement known in the art used for anti-clogging immersion spouts. According to the invention, however, this component or cement is used in the product in much lower proportions than known from the prior art. The proportion of this component or this Ca-Al cement in the product is, based on the mass of the product, in particular below 15% by mass, preferably below 10% by mass, for example below 8% by mass or below 7% by mass. , and for example, over 0.5% by mass, that is, for example, over 1% by mass, over 2% by mass or over 3% by mass. The CaO content in the Ca-Al cement is preferably between 10 and 38% by mass, based on the mass of the Ca-Al cement. Insofar as the product also contains such a component or Ca-Al cement, the product's melt phases producing the anti-clogging lubricating film are formed from two sources: first, the substance resulting from the application of the product from the diffusible material Metal and the second component and on the other from the already existing component or the existing Ca-Al cement. The latter Accordingly, it can be metered much lower than in the prior art, since a further melt phase source is available in the form of the forming material. Since the proportions of Ca-Al cement in the product are significantly lower than the proportions of this cement known from the prior art, the refractory properties of the product are not adversely affected thereby.

The relationship the mass fraction of CaO in a Ca-Al cement of the product to the mass fraction of Ca in the first component can be over 0.5 are, for example, also over 0.6, over 1.0 over 1.2 or over 1.4 and, for example, below 5, so for example, also below 4, under 3, under 2 or under 1.8. Accordingly, this ratio can, for example in the range between 0.5 and 5 and preferably in the range between 0.5 and 3, so for example between 0.6 and 3.0.

Of the Share of the other component in the product, by mass of the product may, for example, be less than 10% by mass, for example also below 8% by mass, below 5% by mass or below 3% by mass, and for example, over 1 Mass%, that is, for example, over 2% by mass or over 2.5 Dimensions-%.

It is preferably provided that the proportion of carbon (C), in free or bound form, of the product, based on the mass of the product, is below 3 mass%, that is, for example, below 2 mass% or below 1 mass%. , This has the particular advantage in the presence of oxides which can be reduced by carbon under the conditions of use, for example SiO ₂ . Due to such redox reactions, the additional oxygen available would again be able to oxidize metallic aluminum of the molten steel and be another cause for the deposition of aluminum oxide (clogging).

For the same reason, it can be provided that the proportion of SiO ₂ or silicate material in the product, based on the mass of the product, is below 3 mass%, that is, for example, below 2 mass% or below 1 mass%.

It may be provided that the proportion of mineral CaO in the product (for example the CaO content of the Ca-Al cement or of other CaO-containing components, for example of dolomite), based on the mass of the product, at a maximum of 4 mass. % and preferably less than 3 mass%, that is, for example, less than 2 mass% or less than 1 mass%. This reduces the formation of low-melting Ca aluminates by reaction with the Al ₂ O ₃ matrix of the product and the associated reduction in refractoriness.

In addition to the aforementioned components, the refractory ceramic material of the product may comprise additional components, for example dispersants or binders, preferably inorganic binders. For example, alumina (Al ₂ O ₃ ) based binders may be provided. Dispersant may be any dispersant used in refractory technology, for example, polycarboxylate ethers, and may be present in, for example, proportions greater than 0.05 or greater than 0.1% by weight and, for example, less than 1 or less than 0.4% by weight, based in each case Mass of the product. Binder can be present, for example, in amounts above 0.5 or above 1% by mass and, for example, in proportions below 6 or below 4% by mass, in each case based on the mass of the product.

The product according to the invention can be present as unbaked product and as described above be used. This can - compared to a baked product - prevented be that the diffusion process, which is preferred only in the application of the product, at least in part already at Brand of the product expires. After a continuation of this According to the invention, the product can be used before its use subjected to thermal treatment, but at a temperature below which diffusion of the diffusible metal occurs and below which one may be present in the product, at the application temperature of the product melt phase forming component, in particular a Ca-Al cement already forms melt phases.

Further features of the invention will become apparent from those in the table according to 3 specified embodiments Nos. 1 to 12, which show exemplary compositions.

In the table according to 3 contain the products according to embodiments no. 1 to 12 specified in the respective column components according to lines 1 to 11 in the proportions indicated in each case in mass%, each based on the mass of the respective product. The components according to lines 1 to 4 are present in the respective particle sizes given in brackets. The components according to lines 8 to 11 are Ca-stabilized ZrO ₂ , with the proportion of CaO in mass%, in each case in parentheses, based on the mass of the respective component. The Ca-stabilized ZrO ₂ is present in particle sizes ranging from 0.1 to 1.0 mm.

The dispersant used according to Zei 6. is a polycarboxylate ether, the inorganic binder according to line 7 is hydratable, finely divided Al ₂ O ₃ .

Further, in the table according to 3 under line 12, the proportion of CaO in the Ca-stabilized ZrO ₂ (this proportion of CaO is called "dyn", ie "dynamic" share of CaO because it diffuses) and line 13, the maximum of this CaO in the respective Product by diffusion and associated reaction with the Al ₂ O ₃ formable mass of CaAl ₂ O ₄ , based on the mass of the respective product indicated. Under line 14, the proportion of CaO (this proportion of CaO is referred to as "st", ie as a "static" proportion of CaO because it does not diffuse) in Ca-Al cement (CaO content 30% by mass) and under line 15, the mass of CaAl ₂ O ₄ , formed from the CaO content of the Ca-Al cement, based on the mass of the respective product specified. Under line 16, the sum of the masses according to lines 13 and 15 is indicated. Line 17 shows the ratio of the CaO content according to line 12 to the CaO content according to line 14, if available. The data according to lines 12 to 16 are again given in mass%.

The Products according to the embodiments Nos. 1 to 12 are as molded, dried and unfired products in front. The products can for example, as a functional product for flow control applications in the Steel metallurgy, for example as pouring nozzles or immersion nozzles, and for example, as parts of these components, such as Inserts or sleeves, for example Al-killed steel melts, to be used.

All the aforementioned features of the invention, individually or in combination, be combined with each other as desired.

Claims (11)

Use of a molded product of refractory ceramic material with the following features: a) a first Component of refractory ceramic material; b) a second one Component of refractory ceramic material; c) the first Component has a proportion of diffusible under the influence of temperature Metal on; d) the diffusible metal is in the electrochemical Voltage range below aluminum; e) the second component has a proportion of the diffusible metal in a concentration which is below the concentration of the diffusible metal in the first component lies, for potting aluminum-calmed Molten steel such that f) the diffusible metal Application temperature of the product from the first component diffused to the second component and g) with the second component forms a substance that has a melting point at a temperature which is below the temperature of the melting point of the first and second component. Use according to claim 1 with the proviso that the product has a pouring nozzle, a Immersion nozzle or part of the aforesaid products. Use according to claim 1 with a proportion of diffusible Metal in the first component between 1 and 30% by weight, based on the mass of the first component. Use according to claim 1 with a share in the first component of the product between ≥ 1 and ≤ 65% by mass referred to Mass of the product. Use according to claim 1 with a share in the second component of the product between ≤ 99 and ≥ 30 mass%. Use according to claim 1 with a proportion of mineral CaO on the ceramic material of the product below 3% by mass, based on the mass of the product. Use according to claim 1 with a first component in the form of Ca-stabilized ZrO ₂ . Use according to claim 1 with a second component in the form of at least one of the following substances: Al ₂ O ₃ , compounds of Al ₂ O ₃ and other metal oxides. Use according to claim 1 with at least one further Component of refractory ceramic material in the form of a refractory Cement. Use according to claim 1 with at least one another component of refractory ceramic material in the form a refractory Ca-Al cement. Use according to claim 1, wherein the of diffusible metal and the second component formable fabric has a melting point at a temperature below 1650 ° C.