DE102021110208A1 - Cover plate, process for their production and their use - Google Patents

Abstract

The present invention relates generally to a cover plate, a method for the production thereof and the use thereof.

Description

Field of invention

The present invention relates generally to a cover plate, a method for the production thereof and the use thereof.

Background of the invention

Cover plates are used, for example, in furnishings and there separate areas in which electronic components are arranged, for example, from user areas. For example, cover plates can also be used as so-called hot plates in cooking appliances. Another area of application of cover plates is, for example, the use of a cover plate as a chimney viewing panel in stoves or chimneys or other heating devices.

As a rule, cover plates can therefore be exposed to considerable thermal stresses in operational use.

However, it has been shown time and again that the mechanical stresses to which cover plates are exposed in use can also be considerable. For example, this includes abrasion or scratch loads, which lead to a very significant wear of the surface of such a cover plate and / or of coatings, for example so-called decorative layers, which are used, for example, to identify so-called functional areas of a hotplate, or other coatings arranged on the surface of a cover plate, being able to lead.

It should also be noted that not only the thermal resistance of the material and its wear resistance, such as the hardness of the layer, are important, but also the chemical resistance. This is because, for example, when a cover plate is used as a cooking surface or as a viewing window for hot applications, for example in ovens or chimneys, aggressive substances can come into contact with the cover plate, especially at higher temperatures.

In order to improve the wear resistance, in particular of the surface of such cover plates, so-called scratch protection layers in particular are applied to the surface of the cover plate. However, it has been shown that there are still difficulties in obtaining coatings that are sufficiently hard and still have sufficient chemical resistance even at high temperatures. In addition, the materials for a scratch protection layer should, if possible, also be visually inconspicuous. This means that, if possible, they should not falsify the color of light passing through the cover plate and / or should, if possible, only have a low level of absorption so that, for example, light indicators such as displays can still be easily perceived even at relatively low illuminance levels.

Materials which are suitable, for example, for wear protection layers are, for example, nitrides or carbides of metals, for example nitrides or carbides of aluminum or titanium, or semimetals such as silicon. However, these materials are not sufficiently chemically resistant for use at high temperatures.

Oxides, in particular oxides of metals, are also materials which, at least in principle, come into consideration as a scratch protection layer. They are also very stable materials and some are also transparent or uncolored. However, in terms of their mechanical properties, they are mostly inferior to carbides and nitrides, which are made significantly harder. A disadvantage of some monometallic metal oxides, that is to say metal oxides which contain only one metal as the main metallic component, is that they are colored, such as iron oxide or chromium oxide. Titanium dioxide, on the other hand, is colorless, but has a very high refractive index and therefore reflects visible light too strongly, which increases the visual conspicuousness of such a coating.

Metallic mixed oxides, in particular binary or bimetallic oxides, come into consideration as material alternatives.

In the context of the present disclosure, a metallic mixed oxide is understood to mean an oxide which comprises several metallic components as main constituents. A metallic mixed oxide In other words, as negative ions or anions, it includes oxygen ions O ^2- and the cations of at least two elements, in particular the cations of at least two metals, the second metal, which is comprised by the mixed oxide, is not in the form of a doping or is merely unavoidable Trace, rather than an essential component.

A bimetallic or binary metallic oxide or mixed oxide is understood to mean an oxide which comprises two metals as main components. In particular, the term bimetallic or binary metallic oxide or mixed oxide includes oxides or mixed oxides with a spinel structure of the general formula AB ₂ O ₄ , where within the scope of the present disclosure both oxides or mixed oxides which have a spinel structure and those which have a spinel structure Inverse spinel structure crystallize, are included in the term of the oxide with spinel structure.

In a spinel structure or in a so-called inverse spinel structure, depending on their size, the metal cations are located in the gaps formed by the oxygen ions in a very close packing of spheres. The spinel structure (as well as the so-called inverse spinel structure) is a crystal structure that is known to the person skilled in the art and named after MgAl ₂ O ₄ , the mineral spinel.

Spinel, MgAl ₂ O ₄ , is of particular interest because this material is resistant up to temperatures of 1000 ° C. and more, in particular also sufficiently chemically resistant. In addition, it is known that this material can still be made transparent even with a thickness of several centimeters and that very hard bodies can be obtained from spinel.

Materials based on spinels, for example ceramics, are known. For example, the publication Gatti, A., Development of a process for producing transparent spinel bodies, Final Report, General Electric, Philadelphia Pennsylvania, 1969, describes a method for producing transparent bodies from spinel.

Furthermore describes the EP 0 334 760 B1 a process for the production of high-performance objects as magnesium-aluminum spinels, especially those that are transparent in the infrared and in the visible.

The US patent U.S. 4,029,755 A describes ceramics that are transparent, these ceramics for ceramic processes comprising very small grains with diameters between 50 µm and 300 µm, and which are obtained by a cold pressing process.

Black coatings have also already been obtained including materials with a spinel structure, such as EP 3 502 075 A1 describes.

So far, however, it has not yet been possible to obtain any transparent, uncolored coatings on cover plates which can serve as a scratch protection layer. The layers of EP 3 502 075 A1 are designed as colored coatings and only have a very small thickness of a few 100 nm, since, despite the coloring of the coating, which is based on absorption, sufficient transmission in the infrared range of the electromagnetic spectrum should ultimately be guaranteed. However, the layers of the prior art are therefore not suitable as scratch protection layers, in particular not as colorless scratch protection layers, because the materials are after EP 3 502 075 A1 comprise transition metal ions and are therefore always formed with a distinct intrinsic color.

There is therefore a need for cover plates which have a transparent, mechanically and / or chemically resistant coating, preferably even at high temperatures of up to 1000 ° C., and for a method for producing such cover plates.

Object of the invention

The object of the invention is to provide cover plates which at least partially overcome or at least mitigate the previous problems of the prior art.

Summary of the invention

The object of the invention is achieved by the subject matter of the independent claims. Preferred and / or more specific embodiments can be found in the dependent claims.

The invention therefore relates to a cover plate comprising a glass or glass ceramic substrate with a first main surface and a second main surface as well as a coating arranged on at least one of the main surfaces of the glass or glass ceramic substrate in at least one area of the cover plate, the coating being at least one mixed oxide of the formula A. _x B _y O ₄ comprises or predominantly, that is to say at least 50% by weight, or essentially, that is to say at least 90% by weight, or consists entirely of at least one mixed oxide of the formula A _x B _y O ₄ , the molar ratio from A to B is between at least 0.3 and at most 0.7, the mixed oxide and / or the coating being at least partially crystalline, in particular polycrystalline, and A preferably comprising Fe, Mg, Be, Zn, Co, Si, Mn , or mixtures thereof and where B preferably comprises Al, Fe, Cr, V or mixtures thereof, and where the coating preferably has a light transmittance of meh r than 70%.

• Unter einer Platte wird im Rahmen der vorliegenden Offenbarung ein Formkörper verstanden, bei dem die Abmessung in einer Raumrichtung eines kartesischen Koordinatensystems mindestens eine Größenordnung kleiner ist als in den beiden anderen, zu dieser ersten Raumrichtung senkrechten Raumrichtungen. Mit anderen Worten ist die Dicke des Formkörpers geringer als seine Länge und Breite.

In the context of the present disclosure, the following definitions apply:

• In the context of the present disclosure, a plate is understood to mean a shaped body in which the dimension in one spatial direction of a Cartesian coordinate system is at least one order of magnitude smaller than in the other two spatial directions perpendicular to this first spatial direction. In other words, the thickness of the shaped body is less than its length and width.

In the context of the present disclosure, the main surfaces of a plate or, more generally, of a molded body are understood to mean the surfaces of the molded body or of the plate which comprise the majority of the surface area of the surface of the molded body or of the plate. For a plate, these are in particular the areas whose dimensions are determined by the length and width of the shaped body. These are often also - depending on the exact arrangement of the plate - referred to as the top and bottom or the front and back of the plate.

A configuration of a cover plate as described above has a number of advantages.

The fact that the coating comprises a mixed oxide of the formula A _x B _y O ₄ or predominantly, i.e. more than 50 mol% (or atom%, i.e. in each case based on the molar fraction), or essentially, i.e. more than 90 Mol%, or consists entirely of a mixed oxide of the formula A _x B _y O ₄ , the coating is, on the one hand, designed to be high-temperature stable. In the context of the present disclosure, a high-temperature stable formation of a coating and / or a material is to be understood as meaning that at high temperatures, for example at temperatures up to less than 900.degree. C., in particular up to 800.degree. C., there is no phase transition of the material or the coating comes. The material or the coating also shows no degradation, such as decomposition reactions or cracking.

This very good resistance of the material or, in a corresponding manner, of the coating is advantageously supported by the fact that the mixed oxide and / or the coating are at least partially crystalline. For example, the mixed oxide can be present in the spinel structure or the inverse spinel structure or also in the olivine structure, it being possible for the presence of a spinel structure or possibly an inverse spinel structure to be advantageous. This is because the spinel structure or possibly the inverse spinel structure is a crystallographically very stable structure which does not tend to undergo any phase changes. It is therefore particularly advantageous if the coating has a very high crystal or crystallite content. In particular, the material or the coating or the mixed oxide is polycrystalline.

The advantageous design of the coating can be influenced in particular by the choice of material. Component A therefore preferably comprises iron Fe and / or magnesium Mg and / or beryllium Be and / or zinc Zn and / or cobalt Co and / or silicon Si and / or manganese Mn and / or vanadium V and / or mixtures thereof. The metals which form component A or which comprise component A are preferably present in the form of cations which preferably have the oxidation number II +, that is to say, for example, alkaline earth metals. However, component A can also be formed from silicon, a semimetal or comprise silicon, which in oxidic compounds has the oxidation number IV +. B also preferably comprises aluminum Al, iron Fe, chromium Cr or vanadium V or mixtures thereof, the metals which form component B or which comprise component B being present in the form of cations. It is particularly preferred if the major part of A - ie at least 50 atom% or mol% - is magnesium and the major part of B - ie at least 50 atom% or mol% - is aluminum. In particular, it is also possible that the material or the mixed oxide or the coating, apart from unavoidable traces, comprises only magnesium and aluminum as metallic components or their cations, i.e. the material or the mixed oxide or the coating made of spinel MgAl ₂ O ₄ , in particular from polycrystalline spinel. A polycrystalline design of the material and / or the coating can be advantageous, because if very small, fine crystallites are present, these are optically inconspicuous because grain boundaries are not perceived as being visually disturbing and therefore the view through such a coating is not significantly impaired.

• Umfasst A Magnesium und/oder Beryllium, dann ist B vorzugsweise Aluminium und/oder Eisen und/oder Chrom und/oder Vanadium.
• Umfasst B Aluminium, ist A vorzugsweise Magnesium und/oder Beryllium und/oder eine Mischung von Magnesium und/oder Beryllium und/oder Vanadium.
• Umfasst B Chrom, ist A vorzugsweise Magnesium und/oder Eisen und/oder Zink und/oder Cobalt.
• Umfasst B Vanadium, ist A vorzugsweise Mangan und/oder Magnesium.
• Umfasst B Eisen, dann ist A vorzugsweise Magnesium und/oder Silicium.

The following combinations of metals are preferred:

• If A comprises magnesium and / or beryllium, then B is preferably aluminum and / or iron and / or chromium and / or vanadium.
• If B comprises aluminum, A is preferably magnesium and / or beryllium and / or a mixture of magnesium and / or beryllium and / or vanadium.
• If B comprises chromium, A is preferably magnesium and / or iron and / or zinc and / or cobalt.
• If B comprises vanadium, A is preferably manganese and / or magnesium.
• If B comprises iron, then A is preferably magnesium and / or silicon.

According to one embodiment, the coating therefore comprises at least one mixed oxide of the formula A _x B _y O ₄ , the molar ratio of A to B being between at least 0.3 and at most 0.7, A comprising magnesium and / or beryllium, and B aluminum and / or iron and / or chromium and / or vanadium,
and / or at least one mixed oxide of the formula A _x B _y O ₄ , where the molar ratio of A to B is between at least 0.3 and at most 0.7, where B comprises aluminum and A magnesium and / or beryllium and / or a mixture of magnesium and beryllium, and / or vanadium,
and / or at least one mixed oxide of the formula A _x B _y O ₄ , where the molar ratio of A to B is between at least 0.3 and at most 0.7, where B comprises chromium and A magnesium and / or iron and / or zinc and / or cobalt,
and / or at least one mixed oxide of the formula A _x B _y O ₄ , where the molar ratio of A to B is between at least 0.3 and at most 0.7, where B comprises vanadium and A manganese and / or magnesium,
and / or at least one mixed oxide of the formula A _x B _y O ₄ , the molar ratio of A to B being between at least 0.3 and at most 0.7, where B comprises iron and A comprises magnesium and / or silicon.

It is possible that the coating comprises only one crystalline phase, for example comprising only crystals or crystallites or made of MgAl ₂ O ₄ . This is synonymous with the fact that the coating comprises only one mixed oxide or consists predominantly or essentially or completely of only one mixed oxide. However, it is also possible that the coating comprises a plurality of crystalline phases, that is to say for example, in addition to MgAl ₂ O ₄ , Fe ₂ SiO ₄ and / or another crystalline phase. This is synonymous with the fact that the coating comprises several mixed oxides or consists predominantly or substantially or even completely of several mixed oxides.

In general, it is furthermore possible for the coating to be at least partially amorphous, that is to say comprises an amorphous phase in addition to at least one crystalline phase or possibly also several crystalline phases.

A formation of a coating which comprises only one crystalline phase (or comprises only a mixed oxide) is understood to mean that the coating comprises only crystals or crystallites of a specific crystallographically determinable phase. A formation of a coating which comprises several crystalline phases is accordingly understood to mean that different crystal phases can be detected in the coating crystallographically, for example by X-ray diffraction (XRD).

Preferred crystal phases include, for example, MgAl ₂ O ₄ , BeAl ₂ O ₄ , MgFe ₂ O ₄ , MgCr ₂ O ₄ , MgV ₂ O ₄ , (Be, Mg) Al ₂ O ₄ , for example BeMgAl ₄ O ₈ , FeCr ₂ O ₄ , ZnCr ₂ O ₄ , CoCr ₂ O ₄ , FeV ₂ O ₄ , Val ₂ O ₄ , SiFe ₂ O ₄ , MnV ₂ O ₄ .

Furthermore, the advantageous development of the properties of the coating can also be supported by a suitable choice of the molar ratio of components A and B to one another. The molar ratio of components A and B to one another is advantageously in the range between at least 0.3 and at most 0.7. In particular, it is possible that the ratio is exactly 0.5, i.e. one atom A for two atoms B. In this case, the stoichiometric composition results in accordance with the spinel structure or the inverse spinel structure, AB ₂ O ₄ . Deviations from this ideal stoichiometric ratio, which can be based, for example, on changing valences of components A and / or B, are, however, permissible within the above-mentioned limits. In particular, it is generally also possible for the mixed oxide to include a component C in addition to components A and / or B, that is to say that Mixed oxide A _x B _y O ₄ is present doped. Since the components A and B determine the essential properties of the mixed oxide, one can still speak _{of a compound or a mixed oxide A x} B _y O _4. If component C is to be named, the mixed oxide can also be written or specified as A _x B _y O ₄ : C or A _x B _y C _z O ₄ if a doped mixed oxide is present. In this context, it is generally understood, without being restricted to one of the embodiments of the mixed oxide, the coating and / or the cover plate, that the amount of oxygen O can differ somewhat from the stoichiometric amount given in the formula (ie the index “4”), depending according to the valences and / or amounts of the individual components A, B, and / or C. However, this is not considered critical as long as the crystal structure corresponds to the corresponding stoichiometric compound.

The formation of an oxidic phase with the formula A _x B _y O ₄ is particularly advantageous because in this way wear-resistant, for example scratch- and / or abrasion-resistant coatings can be obtained, which, however, compared to known scratch-resistant coatings such as nitrides, have a have reduced layer tension. The amount of the layer stress in the coatings according to embodiments is preferably at most 800 MPa, preferably at most 500 MPA and particularly preferably at most 300 MPa. In other words, the layer stress is preferably ± 800 MPa, preferably at most ± 500 MPa and particularly preferably at most ± 300 MPa. In other words, it is both possible for the coating to have tensile stress or to be under compressive stress, depending on the precise embodiment. This also makes it possible, for example, to coat very thin substrates, for example thin glasses, because due to the reduced layer tension, even thin substrates that are coated with a coating according to embodiments of the present disclosure, in particular coated on one side, have only slight warpage or less Warp up.

The lower layer tension of the coating materials according to embodiments of the present disclosure is also advantageous in the coating process. Because due to the high intrinsic layer tension of nitrides, these coating materials often result in flaking layers on the inside of coating units, for example in the interior of the sputtering chamber.

According to one embodiment of the cover plate, it is designed in such a way that the amount of layer stress in the coatings according to embodiments is at most 800 MPa, preferably at most 500 MPa and particularly preferably at most 300 MPa.

Layer stress in an oxidic and / or in a nitridic system can be influenced by a large number of process parameters. In particular, parameters play an important role which have an influence on the porosity, the packing density, the crystal state and / or the layer structure of the coating. Among other things, the parameters process pressure and temperature should be mentioned here. The influence of temperature is also very much dependent on the coated material and its phase transitions. A general rule cannot be derived in this regard, but due to the influence of temperature on the layer porosity and the crystal state, a strong influence on the layer stresses is also to be expected. Furthermore, a difference in the coefficient of thermal expansion, for example in the coefficient of linear thermal expansion between the substrate and the layer material, can already trigger stresses in the coating as a result of the cooling process after the coating has taken place.

The process pressure is another important parameter for setting the layer tension. In most cases, a low pressure leads to a reduction in voids and to compact layer growth, which often leads to an increase in compressive stresses. This can be shown by way of example for sputtered Si ₃ N _{4 coatings.} Here, namely, low process pressures lead to very high layer stresses with an amount of stress of up to more than 2 GPa, for example 8th in Ruske et al., Thin solid films 351, (1999) , Page 158 ff., Can be found.

And parameters relating to the crystallinity of the coating, for example the type, number and / or size of the crystalline phases comprised by the coating, are summarized here for the crystal state of the coating.

Surprisingly, it has been shown that with a method according to embodiments of the present disclosure, as will be described in more detail below, layers can be obtained which have a relatively low layer tension, which brings the advantages discussed above with it.

Furthermore, the oxidic materials which are included in the coating according to embodiments of the present disclosure have a lower refractive index of, for example, between 1.6 and 1.8, such as 1.7, compared with, for example, nitridic materials or generally known scratch protection coatings. This is advantageous because in this way the perceptibility of the coating according to embodiments of the present disclosure is low, in particular less than in the case of conventional scratch protection coatings. Especially in the case of cover plates, which include glass or glass ceramic substrates that are colored, or in the case of glass or glass ceramic substrates that are opposite the main surface on which the coating is arranged, with a further, for example masking or generally the The coatings according to embodiments of the present disclosure are only slightly noticeable visually.

The coating preferably has a light transmittance of more than 70%. The light transmittance of the coating is preferably at least 80%, particularly preferably at least 90%. The light transmittance of the coating is determined by determining the light transmittance of the uncoated substrate and by determining the light transmittance of the substrate in an area in which only the coating is arranged on only one main surface of the glass or glass ceramic substrate, as well as by calculating the difference between these light transmittances wherein the value obtained for the uncoated substrate is subtracted from that of the coated substrate. The reduction in transmittance determined in this way is due to the coating. The light transmittance resulting for the coating is then 100% less than the difference determined from the light transmittance of the coated or the uncoated substrate, as explained above. The light transmittance for the coated or uncoated substrate is preferably determined based on or in accordance with DIN EN ISO 13468 for the wavelength range from 380 nm to 780 nm.

For the case that the light transmittance of the coated substrate in the area in which only the coating is arranged on only one main surface of the substrate is, for example, 76%, and for the case of the uncoated substrate is 77%, the difference in the light transmittance results 1% substrate. Correspondingly, the light transmittance of the coating is then 100% less 1%, that is to say here 99%.

Hierbei steht LTG für Lichttransmissionsgrad, der Lichttransmissionsgrad des beschichteten Substrats ist der Lichttransmissionsgrad der Abdeckplatte in dem Bereich, in welchem nur das Substrat und die Beschichtung angeordnet sind. Der Lichttransmissionsgrad des beschichteten Substrats und der Lichttransmissionsgrad des unbeschichteten Substrats werden dabei vorzugsweise bestimmt in Anlehnung an oder gemäß DIN EN ISO 13468 für den Wellenlängenbereich von 380 nm bis 780 nm.In other words, the light transmittance of the coating results from the following formula: $$\text{LTG}\left(\text{Coating}\right)=100\%-\left(\text{LTG}\left(\text{coated substrate}\right)-\text{LTG}\left(\text{uncoated substrate}\right)\right)$$

LTG stands for light transmittance, the light transmittance of the coated substrate is the light transmittance of the cover plate in the area in which only the substrate and the coating are arranged. The light transmittance of the coated substrate and the light transmittance of the uncoated substrate are preferably determined based on or in accordance with DIN EN ISO 13468 for the wavelength range from 380 nm to 780 nm.

Such a configuration with a high light transmittance of the coating of at least 70% is advantageous because in this way the transparency through the coating is not greatly reduced. Such a high degree of light transmission is therefore preferred, especially for applications in the case of viewing panes. However, such a configuration of the coating as a highly transparent coating can also be advantageous for applications in which, for example, the coating is applied to substrates that have already been coated. In this case, for example, other coatings for which the coating according to embodiments of the present disclosure is a “topcoat” can also be clearly perceived through the coating according to embodiments of the present disclosure. This is particularly advantageous in the event that further coatings are present, for example in the form of logos.

According to one embodiment of the disclosure, the coating has a thickness between 0.05 μm or more and preferably 3 μm or less. Such a minimum layer thickness is advantageous because it improves the mechanical stability of the coating. The mechanical stability of the coating is the property of the coating to be resistant to wear and tear, such as scratching or abrasion. It is surprising that the advantageous properties of the coating can already be achieved with a layer thickness of 50 nm. The mechanical properties of the coating can be further improved if the layer thickness of the coating is increased. However, the limitation of the layer thickness to preferably at most 3 μm is particularly advantageous. This is because mixed oxides, which can be included in the coating, can sometimes have an inherent color. This inherent coloration is developed in particular when the mixed oxide in question is present as a bulk material. However, this can be different if such a material, which has an inherent color as a bulk material, is present as a thin coating. In this case, the coating may only be colored to a very small extent and the inherent coloring of the mixed oxide may not be perceptible at all. Therefore, the coating should not be too thick, because a thick coating is not only visually more noticeable than a thinner coating, it is also more prone to cracking. In addition, it is not economical to produce coatings that are too thick, especially since thick coatings in the μm range can also reduce the breaking strength, for example the impact resistance or flexural strength, of a cover plate. The thickness of the coating is therefore preferably limited. It is preferably at most 3 μm.

According to a further embodiment of the disclosure, the coating is transparent and uncolored. This is advantageous because the coating is particularly inconspicuous visually in this way. This not only ensures that the coating preferably only slightly reduces the light transmission through the glass or glass ceramic substrate, but also that there is particularly preferably no shift in the color locus of light which penetrates through the glass or glass ceramic substrate through the coating itself comes. In other words, for example, luminous displays, such as displays, which are arranged below or behind such a cover plate, can be perceived in this way in a particularly color-fast manner and / or without particularly strong luminous powers being required.

wobei der Farbort E₁₁₀ gegeben ist durch die Farbkoordinaten a*₁₁₀, b*₁₁₀, L*₁₁₀ und der Farbort E₁₀₁ gegeben ist durch die Farbkoordinaten a*₁₀₁, b*₁₀₁, L*₁₀₁ und vorzugsweise jeweils bestimmt ist in einer Messung gegen eine Weißkachel, insbesondere mit einem Spektrophotometer CM-700d der Firma Konica-Minolta.The optical properties of the coating with regard to the transparent, uncolored formation can preferably be characterized by comparing the color locations of the uncoated glass or glass ceramic substrate and the glass or glass ceramic substrate coated with the coating according to embodiments. In the context of the present disclosure, the coating is therefore preferably referred to as transparent uncolored if the color location E _{101 of} the cover plate is in the sub-area in which only the coating is arranged on only one main surface of the glass or glass ceramic substrate from the color location E ₁₁₀ of the cover plate in an area in which no coating is arranged on the glass or glass ceramic substrate differs at most by a value ΔE of less than 20, preferably less than 15, particularly preferably less than 10, the color location E ₁₁₀ in the Partial range and the color location E ₁₀₁ in the area are particularly preferably determined in the L * a * b * color system and the color location difference ΔE is calculated using the following formula: $$\Delta \mathrm{E.}=\sqrt{\left({\left(a_{110}^{*}-a_{101}^{*}\right)}^2+{\left({\mathrm{<figure-callout\; id="110"\; label="b"\; filenames="DE102021110208A1\_0006.png"\; state="\{\{state\}\}">b</figure-callout>}}_{110}^{*}-{\mathrm{<figure-callout\; id="101"\; label="b"\; filenames="DE102021110208A1\_0006.png"\; state="\{\{state\}\}">b</figure-callout>}}_{101}^{*}\right)}^2+{\left({\mathrm{L.}}_{110}^{*}-{\mathrm{L.}}_{101}^{*}\right)}^2\right)}.$$

The color location E _{110 is} given by the color coordinates a * ₁₁₀ , b * ₁₁₀ , L * ₁₁₀ and the color location E _{101 is} given by the color coordinates a * ₁₀₁ , b * ₁₀₁ , L * ₁₀₁ and is preferably each determined in one measurement against a white tile, especially with a CM-700d spectrophotometer from Konica-Minolta.

According to a further embodiment of the cover plate, the cover plate has a thickness between 2 mm and 8 mm, preferably between 4 and 6 mm. This is advantageous because in this way the cover plate has sufficient mechanical strength against breaking loads in order to be able to be used, for example, as a viewing window in hot applications or as a so-called hotplate. The mechanical strength of the cover plate against breaking loads includes the so-called impact resistance, which can be determined, for example, in a so-called ball drop test, as well as the flexural strength, which can be determined, for example, in a three-point bend. In order to achieve sufficient strength of the cover plate here, it is advantageous if the cover plate has a minimum thickness of 2 mm, preferably of at least 4 mm. However, the thickness of the cover plate should not be too great either, since otherwise the material costs are too high on the one hand and the weight of the cover plate on the other hand is too high. The cover plate therefore preferably has a thickness of at most 8 mm, preferably of at most 6 mm. According to one embodiment, it is possible that the cover plate comprises a substrate which has a thickness of at least 2 mm, preferably of at least 4 mm, and a thickness of at most 8 mm, preferably of at most 6 mm.

According to a further embodiment, however, it is also possible that the cover plate has a thickness of less than 2 mm, for example 1 mm, or even less, for example at least 30 μm, for example 50 μm, or 100 μm Embodiment possible that the cover plate comprises a substrate which is designed as so-called thin glass. In particular, it is also possible that the substrate has a thickness of less than 2 mm, for example 1 mm, or less, for example at least 30 μm, for example 50 μm, or 100 μm. Such a configuration is surprisingly possible with a coating according to embodiments possible, because the layer tension in the coating according to embodiments is very low for a so-called hard material or scratch protection or wear protection layer. This is particularly evident from the only slight curvature of a cover plate that is provided with such a coating.

According to yet another embodiment of the cover plate, the cover plate has a haze of less than 5% in the partial area of the area of the cover plate or of the glass or glass ceramic substrate in which only the coating is arranged on only one main surface of the glass or glass ceramic substrate, preferably less than 2% and particularly preferably less than 1%, measured in accordance with ASTM-D 1003.

In other words, the cover plate has only very little cloudiness or the cover plate is very clear in the sub-area of the cover plate or the glass or glass ceramic substrate in which only the coating is arranged on only one main surface of the glass or glass ceramic substrate. This is achieved, in particular, in that the coating itself has only a very low level of opacity or is formed without any significant opacity. Such a configuration is advantageous because in this way a particularly good view through the cover plate is ensured, so that, for example, light elements arranged behind or under the cover plate can be easily perceived, such as displays. Such a configuration is also advantageous for viewing panes for hot applications, for example for stove or fireplace viewing panes.

According to a further embodiment of the cover plate, the coating has a hardness of 6 to 11 GPa, determined in a measuring method according to or based on DIN EN ISO 14577-1 and -4 (so-called Martens hardness). Such a design is particularly preferred, because in this way the cover plate has particularly good resistance to wear and tear, such as scratching the surface or abrasion, in the area in which the coating is arranged. In other words, according to this embodiment, the cover plate is designed as a wear-resistant, in particular as a scratch- and / or abrasion-resistant cover plate, at least in the area in which the coating is arranged on a main surface of the glass or glass ceramic substrate. This is especially important for applications in which the cover plate comes into contact with abrasive materials and / or objects. Such a design of the cover plate is of particular advantage in the cleaning process of a so-called hotplate or a viewing window for stoves or chimneys, in particular when so-called scrapers are used for cleaning. But contact with cookware, for example, can also scratch the surface.

Such a configuration is particularly advantageous for applications of the cover plate in which a frictional load can occur, as occurs, for example, in the case of a hotplate when pans are moved. It is noteworthy that, for example, abrasive particles can also be arranged between the surface of the hotplate and the cookware, which then additionally develop an abrasive effect. A configuration of the cover plate in which the coating also has abrasion resistance as stated above is therefore particularly advantageous. Because this leads to less surface wear.

According to a particularly advantageous embodiment of the cover plate, the coating covers a main area of the glass or glass ceramic substrate essentially over the entire area. In the context of the present disclosure, essentially full-surface coverage is understood to mean that the coating covers the relevant surface to at least 90%, preferably at least 95%. Such a configuration is particularly advantageous when the coating has a high hardness and / or high abrasion resistance, because in this way the main surface, which is essentially fully covered with the coating, is particularly wear-resistant over almost the entire surface, for example abrasion-resistant and / or scratch-resistant, designed. A substantially full-area coating is also understood to mean an embodiment in which the coating, according to embodiments, is not arranged directly on a main surface of the substrate, but rather, for example, a layer is present between the substrate and the coating. The degree of occupancy results generally from the ratio of the areas of the main area covered with the coating to the total area of the main area.

According to a further embodiment of the cover plate, the cover plate has a further coating. This further coating can be designed, for example, as a glass flow-based coating, which is obtained, for example, by printing a so-called enamel color with subsequent baking. Glass flow-based coatings for cover plates are known. For example, such coatings are used as cooking zone markings and / or to mark functional areas. This is particularly important because, for example, in the case of cover plates which are to be used as hotplates, in particular in so-called induction heaters, it is important to mark the functional areas. Because only the correct placement of the cookware ensures that a cooking process can actually take place.

According to the embodiment of the cover plate, the further coating is arranged on the same main surface of the glass or glass ceramic substrate as the coating and covers this main surface at least or only partially. The further coating is arranged between the glass or glass ceramic substrate and the coating. In particular, the further coating preferably adjoins the coating.

Such a configuration of the cover plate can be advantageous in particular when the further coating itself is not particularly mechanically and / or chemically resistant. For example, it is known that substances that come into contact with a cover plate can attack the surface of the cover plate or the glass or glass ceramic substrate. As described above, this can lead to mechanical abrasion such as scratching and / or abrasion of the surface, but it is also possible that some substances enter into a chemical reaction with the surface and thus degrade it. In particular, however, it is also known that coatings applied to the surface of the cover plate and / or the glass or glass ceramic substrate, such as, for example, glass flow-based coatings, can be particularly susceptible to mechanical and / or chemical attacks. This can be due, for example, to the fact that such glass-flow-based coatings can only build up insufficient adhesion to the glass or glass-ceramic substrate, or because, for example, the surface of such a glass-flow-based, pigmented coating is very rough and therefore for both mechanical and chemical attack Attack offers a larger attack surface. In the case of hotplates in particular, it is also possible, for example, for food to burn onto the surface of the cover plate that faces the user during operational use, i.e. the top, and thereby also form an intimate connection with the glass-flow-based, pigmented decoration. When cleaning, which is preferably done by means of a so-called scraper, it is entirely possible that parts of the decoration will be removed together with the soiling. This is not only visually disruptive, but can also lead to large parts of important markings being removed from functional areas.

Therefore, according to one embodiment of the cover plate, it is particularly preferred if the further coating is arranged on the same main surface of the glass or glass ceramic substrate as the coating and at least or only partially covers this main surface, the further coating being between the glass or glass ceramic substrate and the coating is arranged. The further coating can be arranged directly on the main surface of the glass or glass ceramic substrate, that is to say it can be in direct contact with the glass or glass ceramic substrate. This can be advantageous, for example, if an intimate connection is to be formed between the material of the glass or glass ceramic substrate and that of the further coating, for example a glass-flow-based coating, for example to form a melting reaction zone. However, it can also be possible for a coating to be arranged between the further coating and the surface of the glass or glass ceramic substrate, which acts, for example, as an adhesion promoter or as a separating layer, for example to reduce the formation of so-called halos around a glass-flow-based coating.

The coating is advantageously applied to the further coating. For this purpose, it is advantageous if the coating adheres well to the further coating so that there is no failure of the adhesion at the interface between the coating and the further coating. Because when the coating is applied to the further coating, the coating functions as a type of topcoat and protective coating for the further layer and can in this way also improve the mechanical and / or chemical resistance of the further coating at the same time.

According to a further embodiment of the cover plate, the glass or glass ceramic substrate is designed to be transparent, uncoloured or transparently colored. The glass or glass ceramic substrate can be smooth on both sides as well as dimpled on one side, preferably on the side that faces away from the user during operational use. The formation of the glass or Glass ceramic substrate as transparent and uncolored is preferred when a good view through the glass or glass ceramic substrate and in a corresponding manner also through the cover plate is necessary, for example for a viewing window, in particular a viewing window for hot applications. However, it can also be advantageous to select a transparent, uncolored glass or glass ceramic substrate and to at least partially provide a coating that reduces transparency on one side, preferably on the side that faces away from the user or operator during operational use. Such a configuration is possible, for example, for applications of the cover plate as a hotplate, in particular if displays and / or other display elements are also integrated into the cooking appliance and are arranged below the cover plate or hotplate. In this case, a particularly good view of these display elements is possible, in particular the absorption of light by the display element by a transparently colored substrate is not given here.

However, it can also be advantageous to design the glass or glass ceramic substrate to be transparently colored for use as a cooking surface. In this way, components and / or structures arranged behind or below the cover plate are no longer clearly visible. It may also be possible to adjust the transmission of visible light by means of a specifically colored absorption in the glass or glass ceramic substrate in such a way that certain elements or structures can be perceived through the cover plate, but not others.

In the context of the present disclosure, a transparent colored formation of a glass or glass ceramic substrate is understood to mean that the glass or glass ceramic substrate is colored in particular by coloring metal ions. In the context of the present disclosure, this is also understood as volume coloring. In the context of the present disclosure, a material and / or a product, such as, for example, a glass or glass ceramic substrate, is referred to as transparent if it is not designed to be scattering. In contrast to a transparent design, there is in particular an opaque and a translucent design, the opacity or translucency being caused by scattering particles in the material or in the product. In particular, it is therefore possible within the scope of the present disclosure for a material and / or a product to be absorbed, but still referred to as transparent, because the transmission of visible light in transmitted light is indeed reduced in this case, but it occurs with such a design not to scatter visible light.

According to a further embodiment of the cover plate, the coating is arranged on the main surface of the glass or glass ceramic substrate which, when the cover plate is in use, faces the user and is therefore designed as a top or front side. This is particularly useful when the coating is designed as a hard and / or abrasion-resistant coating, that is to say is particularly scratch-resistant and / or abrasion-resistant. This is because it is precisely on the side facing the user during operational use that the greatest stress on the surface of the cover plate will usually take place, for example on the top of a hotplate.

The top or front of the cover plate usually has a special design. As a rule, the upper side or front side of a cover plate is smooth on the one hand, whereas the underside or rear side of the cover plate can, for example, also be nubbed. In the event that a cover plate is designed as a cooking surface, the top of the cover plate is generally also covered with further coatings which, for example, mark functional areas such as cooking zones. Finally, the top of a cover plate is also the one from which the strength of the cover plate is determined. This means that the mechanical strength of the cover plate against breaking loads is determined in such a way that the top side is the side on which the corresponding loads act, i.e. on which a steel ball falls, for example in the ball drop test.

• - Bereitstellen eines Glas- oder Glaskeramiksubstrats
• - Einbringen des Glas- oder Glaskeramiksubstrats in eine Beschichtungskammer
• - Bereitstellen eines keramischen oder metallischen Targets umfassend die Komponenten A und B, wobei A vorzugsweise umfasst Fe, Mg, Be, Zn, Co, Si, Mn, oder Mischungen hiervon und wobei B vorzugsweise umfasst AI, Fe, Cr, V oder Mischungen hiervon,
• - Bereitstellen eines Gases als Reaktivgas, wobei das Gas vorzugsweise Sauerstoff ist
• - Einstellen eines Drucks in der Beschichtungskammer, wobei der Druck zwischen mindestens 1*10^-3 mbar und höchstens 5*10^-2 mbar beträgt
• - Einstellen einer Temperatur von mehr als 40°C in der Beschichtungskammer, wobei die Herstellungstemperatur vorzugsweise höchstens 350°C beträgt,
• - Beschichten durch Aufdampfen oder Sputtern, wobei das Sputtern als DC-Sputtern oder als gepulstes Sputtern erfolgen kann, beispielsweise als Mittelfrequenz- oder Hochfrequenz-Sputtern,
• - Optional Nachbehandlung der Beschichtung durch einen weiteren Prozessschritt in der Form von thermischer Behandlung in einem Ofen, vorzugsweise einem Keramisierungsofen, durch Lasereintrag, durch Blitzlampenbehandlung, durch UV-Nachbehandlung, durch zusätzlichen Plasmaeintrag wie z.B. mittels Sauerstoffplasma im Vakuum oder mittels Plasmaline an Atmosphäre oder über Beflammung und/ oder optional Zugabe eines weiteren Stoffes in der Ausführung als Si oder Ti, wobei der Anteil des zusätzlichen Stoffes kleiner 10 %, bevorzugt kleiner 5 %, besonders bevorzugt kleiner 2 % beträgt sodass wenigstens eine Hauptfläche wenigstens teilweise mit einer Beschichtung umfassend ein oder überwiegend oder im Wesentlichen oder vollständig bestehend aus einem Mischoxid der Formel A_xB_yO₄ beschichtet wird, wobei das Stoffmengenverhältnis von A zu B zwischen mindestens 0,3 und höchstens 0,7 liegt, wobei das Mischoxid und/oder die Beschichtung zumindest teilweise kristallin vorliegt, insbesondere polykristallin. wobei A bevorzugt umfasst Fe, Mg, Be, Zn, Co, Si, Mn, oder Mischungen hiervon und wobei B bevorzugt umfasst AI, Fe, Cr, V oder Mischungen hiervon, und wobei vorzugsweise die Beschichtung einen Lichttransmissionsgrad von mehr als 70% aufweist.

Another aspect of the present disclosure relates to a method for producing a cover plate according to the embodiments described above. It is a physical coating process (or PVD, physical vapor deposition). The method comprises the steps

• - Providing a glass or glass ceramic substrate
• - Introducing the glass or glass ceramic substrate into a coating chamber
• Provision of a ceramic or metallic target comprising the components A and B, where A preferably comprises Fe, Mg, Be, Zn, Co, Si, Mn, or mixtures thereof and where B preferably comprises Al, Fe, Cr, V or mixtures thereof ,
• - Provision of a gas as a reactive gas, the gas preferably being oxygen
• - Setting a pressure in the coating chamber, the pressure being between at least 1 * 10 ^-3 mbar and at most 5 * 10 ^-2 mbar
• - Setting a temperature of more than 40 ° C in the coating chamber, the production temperature preferably being at most 350 ° C,
• Coating by vapor deposition or sputtering, whereby the sputtering can take place as DC sputtering or as pulsed sputtering, for example as medium-frequency or high-frequency sputtering,
• - Optional post-treatment of the coating by means of a further process step in the form of thermal treatment in an oven, preferably a ceramization oven, by laser input, by flash lamp treatment, by UV post-treatment, by additional plasma input such as by means of oxygen plasma in a vacuum or by means of plasma line in the atmosphere or above Flame exposure and / or optional addition of a further substance in the form of Si or Ti, the proportion of the additional substance being less than 10%, preferably less than 5%, particularly preferably less than 2%, so that at least one main surface is at least partially covered with a coating or one predominantly or essentially or completely consisting of a mixed oxide of the formula A _x B _y O ₄ , the molar ratio of A to B being between at least 0.3 and at most 0.7, the mixed oxide and / or the coating at least partially is present in crystalline form, especially polycrystalline stallin. where A preferably comprises Fe, Mg, Be, Zn, Co, Si, Mn, or mixtures thereof and where B preferably comprises Al, Fe, Cr, V or mixtures thereof, and the coating preferably has a light transmittance of more than 70% .

It is possible for the coating to take place inline, but it is also possible for the coating to take place in the form of a batch process and thus not within a production line.

As already explained above with regard to the layer tension, a very advantageous configuration of the coating is surprisingly possible with the method according to embodiments according to the present disclosure, in particular by coating with a sputtering method according to embodiments. Surprisingly, it has been shown that with the above method, in particular with a sputtering method, for example with a pulsed sputtering, in particular a preferably pulsed medium-frequency or high-frequency sputtering, coatings can be obtained which are at least partially crystalline, in particular polycrystalline, (or which comprise a mixed oxide which is at least partially crystalline, in particular polycrystalline), and which nevertheless have a low layer tension. This effect can be enhanced by additional post-treatment of the coating either directly in a vacuum or in an atmosphere. Another possibility to support this effect is to add at least one additional substance which acts as a kind of nucleating agent.

• - Thermische Nachbehandlung bei Temperaturen von wenigstens etwa 400°C, besser von wenigstens etwa 500°C, noch vorteilhafter bei wenigstens etwa 600°C oder sogar bei wenigstens etwa 900°C, maximal aber bei der maximalen Einsatztemperatur der Abdeckplatte von höchstens 1100°C, für vorzugsweise wenigstens 2 Stunden, besser wenigstens etwa 4 Stunden oder sogar mehr, bestenfalls von wenigstens etwa 6 Stunden, jedoch nicht mehr als 100 Stunden, insbesondere bei atmosphärischem Druck. Auf diese Weise kann die Beschichtung „annealed“ werden, was auch als „ausgeheilt“ oder allgemein als thermisch nachbehandelt oder thermisch behandelt bezeichnet oder verstanden werden kann. Beispielsweise kann diese Nachbehandlung in einem thermischen Vorspannprozess der Abdeckplatte (insbesondere für den Fall, dass die Abdeckplatte ein Glassubstrat umfasst) oder einem Keramisierungsprozess der Abdeckplatte (insbesondere für den Fall, dass die Abdeckplatte ein Glaskeramiksubstrat umfasst) erfolgen. Vorteilhaft an der thermischen Nachbehandlung ist es insbesondere, dass diese thermische Nachbehandlung auch in Schritten erfolgen kann, die in der Prozessierung der Abdeckplatte nach erfolgter Beschichtung vorgesehen sind, beispielsweise einem thermischen Vorspannen oder in einem Keramisierungsprozess. D.h. es bedarf in diesem Fall keiner gesonderten Temperung der Abdeckplatte, sondern die thermische Nachbehandlung kann auch während sonstiger Prozessschritte stattfinden. Daher ist es vorteilhaft möglich, die thermische Behandlung in einem Keramisierungsofen, also während der Umwandlung eines Grünglases in eine Glaskeramik, oder in einem Vorspannofen, also während des thermischen Vorspannens eines Glassubstrats, durchzuführen.
• - Behandlung mit einem Plasma (beispielsweise einem Argon, Sauerstoff, Ammoniak oder Wasserstoff- Plasma) bei einem Druck von höchstens etwa 10 mbar, bevorzugt höchstens etwa 5 mbar, ganz besonders bevorzugt höchstens etwa 1 mbar, jedoch vorzugsweise mindestens 0,001 mbar, für eine Dauer von mindestens 5 Minuten, bevorzugt mindestens 15 Minuten, besonders bevorzugt mindestens etwa 60 Minuten, jedoch vorzugsweise nicht mehr als 10 Stunden, vorzugsweise nicht mehr als 5 Stunden,
• - Behandlung mit einer Xenon-Blitzlampe bei unterschiedlichen Energien oder Energiedichten von wenigstens 8 J/cm², bevorzugt wenigstens 20 J/cm² und besonders bevorzugt wenigstens 40 J/cm² für wenigstens eine, besser für mindestens fünf, besonders bevorzugt von zehn Entladungen oder mehr
• - Behandlung mit einer UV-Lampe, beispielsweise einer UV-Lampe, welche ein Linienspektrum aufweist, wobei bevorzugt die charakteristischen Linien dieses Linienspektrums bei 185 nm und/oder 254 nm liegen, für wenigstens 2 Stunden, bevorzugt wenigstens 4 Stunden, besonders bevorzugt wenigstens etwa 6 Stunden, jedoch nicht mehr als 100 Stunden, bei atmosphärischem Druck behandelt werden,
• - Behandlung mit einem Laser.

Coated samples can be subjected to a post-treatment directly in the coating chamber or to an additional treatment after the coating process. This can happen in different ways:

• Thermal aftertreatment at temperatures of at least about 400 ° C, better of at least about 500 ° C, even more advantageous at least about 600 ° C or even at least about 900 ° C, but at most at the maximum operating temperature of the cover plate of no more than 1100 ° C , for preferably at least 2 hours, more preferably at least about 4 hours or even more, at best for at least about 6 hours, but not more than 100 hours, especially at atmospheric pressure. In this way, the coating can be “annealed”, which can also be referred to or understood as “cured” or generally as thermally post-treated or thermally treated. For example, this post-treatment can take place in a thermal toughening process of the cover plate (in particular for the case that the cover plate comprises a glass substrate) or a ceramization process of the cover plate (in particular for the case that the cover plate comprises a glass ceramic substrate). A particular advantage of the thermal aftertreatment is that this thermal aftertreatment can also take place in steps that are provided in the processing of the cover plate after the coating has taken place, for example thermal toughening or in a ceramization process. In other words, in this case there is no need for a separate tempering of the cover plate, but the thermal aftertreatment can also take place during other process steps. It is therefore advantageously possible to carry out the thermal treatment in a ceramization furnace, that is to say during the conversion of a green glass in a glass ceramic or in a tempering furnace, i.e. during the thermal tempering of a glass substrate.
• Treatment with a plasma (for example an argon, oxygen, ammonia or hydrogen plasma) at a pressure of at most about 10 mbar, preferably at most about 5 mbar, very particularly preferably at most about 1 mbar, but preferably at least 0.001 mbar, for a period of at least 5 minutes, preferably at least 15 minutes, particularly preferably at least about 60 minutes, but preferably not more than 10 hours, preferably not more than 5 hours,
• Treatment with a xenon flash lamp at different energies or energy densities of at least 8 J / cm ² , preferably at least 20 J / cm ² and particularly preferably at least 40 J / cm ² for at least one, better for at least five, particularly preferably out of ten discharges or more
• Treatment with a UV lamp, for example a UV lamp, which has a line spectrum, the characteristic lines of this line spectrum preferably being at 185 nm and / or 254 nm, for at least 2 hours, preferably at least 4 hours, particularly preferably at least about Treated for 6 hours, but not more than 100 hours, at atmospheric pressure,
• - Treatment with a laser.

By adding a so-called nucleating agent, which for the form A _x B _y O ₄ consists of at least silicon or titanium or a mixture of both materials, crystal growth can be stimulated and / or promoted. As an alternative or in addition to a post-treatment step, a nucleating agent or an additive can therefore also be added. The amount of additive is kept so low that it does not have any negative effects on the physicochemical properties of the coating, but leads to a reduction in the crystallization temperature. For this reason, according to one embodiment, the amount of nucleating agent is less than 10%, preferably less than 5%, particularly preferably less than 2%, of the compound A _x B _y O ₄ . The above percentages are based on the amount of substance or amount of substance (so-called atom% or mol%). In other words, the connection A _x B _y C _z O ₄ z is significantly smaller than the numbers x and y. C here preferably comprises the elements titanium or silicon or a mixture of these two elements or consists of the element titanium or the element silicon or a mixture of these elements.

An additional nucleating agent can be added to components A and B in an alloy target, so that all three elements A, B and C are present in this target, with component C having a significantly lower proportion compared to A or B. As stated above, component C can be formed from titanium or silicon or a mixture of these elements. This alloy target consisting of three components or comprising these three components can be processed almost identically to a two-component target due to the small amount of component C.

• - Bereitstellen eines Glas- oder Glaskeramiksubstrats
• - Einbringen des Glas- oder Glaskeramiksubstrats in eine Beschichtungskammer
• - Bereitstellen eines keramischen oder metallischen Targets umfassend die Komponenten A und B, wobei A vorzugsweise umfasst Fe, Mg, Be, Zn, Co, Si, Mn, oder Mischungen hiervon und wobei B vorzugsweise umfasst AI, Fe, Cr, V oder Mischungen hiervon,
• - Bereitstellen eines Gases als Reaktivgas, wobei das Gas vorzugsweise Sauerstoff ist
• - Einstellen eines Drucks in der Beschichtungskammer, wobei der Druck zwischen mindestens 1*10^-3 mbar und höchstens 5*10^-2 mbar beträgt,
• - Einstellen einer Temperatur von mehr als 40°C in der Beschichtungskammer, wobei die Herstellungstemperatur vorzugsweise höchstens 350°C beträgt,
• - Beschichten durch Aufdampfen oder Sputtern, wobei das Sputtern als DC-Sputtern oder als gepulstes Sputtern erfolgen kann, beispielsweise als Mittelfrequenz- oder Hochfrequenz-Sputtern,

sodass wenigstens eine Hauptfläche wenigstens teilweise mit einer Beschichtung umfassend ein oder überwiegend oder im Wesentlichen oder vollständig bestehend aus einem Mischoxid der Formel A_xB_yO₄ beschichtet wird,
wobei das Stoffmengenverhältnis von A zu B zwischen mindestens 0,3 und höchstens 0,7 liegt,
wobei das Mischoxid und/oder die Beschichtung zumindest teilweise kristallin vorliegt, insbesondere polykristallin.
wobei A bevorzugt umfasst Fe, Mg, Be, Zn, Co, Si, Mn, oder Mischungen hiervon und
wobei B bevorzugt umfasst AI, Fe, Cr, V oder Mischungen hiervon, und wobei vorzugsweise die Beschichtung einen Lichttransmissionsgrad von mehr als 70% aufweist,
weiterhin aufweisend wenigstens eines der folgenden Merkmale:

• - eine Nachbehandlung der Beschichtung (2) durch einen weiteren Prozessschritt in der Form von thermischer Behandlung in einem Ofen, vorzugsweise einem Keramisierungsofen oder in einem Vorspannofen, durch Lasereintrag, durch Blitzlampenbehandlung, durch UV-Nachbehandlung, durch zusätzlichen Plasmaeintrag wie z.B. mittels Sauerstoffplasma im Vakuum und/oder mittels Plasmaline an Atmosphäre und/oder über Beflammung,
• - eine Zugabe einer weiteren Komponente umfassend oder bestehend aus Titan oder Silizium oder eine Mischung dieser beiden Elemente, wobei der Anteil der weiteren Komponente weniger als 10 %, bevorzugt weniger als 5 % und besonders bevorzugt weniger als 2 %, bezogen auf den Stoffmengenanteil, beträgt, sodass eine Beschichtung umfassend eine Verbindung A_xB_yC_zO₄ mit z deutlich kleiner als x und y erhalten ist oder wird.

Another possibility is to add the third component C to the plasma via what is known as co-sputtering, with one target material consisting or being able to consist of components A and B and a second target material consisting of component C. The proportion of atoms or ions made available in component C is significantly lower than the number of atoms or ions made available via the alloy target of components A and B. According to one embodiment, the present disclosure therefore also relates to a method for producing a cover plate, preferably a cover plate according to one of the embodiments described in the disclosure, comprising the steps:

• - Providing a glass or glass ceramic substrate
• - Introducing the glass or glass ceramic substrate into a coating chamber
• Provision of a ceramic or metallic target comprising the components A and B, where A preferably comprises Fe, Mg, Be, Zn, Co, Si, Mn, or mixtures thereof and where B preferably comprises Al, Fe, Cr, V or mixtures thereof ,
• - Provision of a gas as a reactive gas, the gas preferably being oxygen
• - Setting a pressure in the coating chamber, the pressure being between at least 1 * 10 ^-3 mbar and at most 5 * 10 ^-2 mbar,
• - Setting a temperature of more than 40 ° C in the coating chamber, the production temperature preferably being at most 350 ° C,
• Coating by vapor deposition or sputtering, whereby the sputtering can take place as DC sputtering or as pulsed sputtering, for example as medium-frequency or high-frequency sputtering,

so that at least one main surface is at least partially coated with a coating comprising one or predominantly or essentially or completely consisting of a mixed oxide of the formula A _x B _y O ₄ ,
where the molar ratio of A to B is between at least 0.3 and at most 0.7,
wherein the mixed oxide and / or the coating is at least partially crystalline, in particular polycrystalline.
where A preferably comprises Fe, Mg, Be, Zn, Co, Si, Mn, or mixtures thereof and
where B preferably comprises Al, Fe, Cr, V or mixtures thereof, and where the coating preferably has a light transmittance of more than 70%,
furthermore having at least one of the following features:

• - A post-treatment of the coating (2) by a further process step in the form of thermal treatment in an oven, preferably a ceramization oven or in a tempering oven, by laser input, by flash lamp treatment, by UV post-treatment, by additional plasma input such as by means of oxygen plasma in a vacuum and / or by means of plasmaline in the atmosphere and / or via flame,
• an addition of a further component comprising or consisting of titanium or silicon or a mixture of these two elements, the proportion of the further component being less than 10%, preferably less than 5% and particularly preferably less than 2%, based on the molar proportion so that a coating comprising a compound A _x B _y C _z O ₄ with z significantly smaller than x and y is or will be obtained.

Vorzugsweise beträgt bei einer Abdeckplatte erhalten in einem Verfahren nach einer Ausführungsform, wie auch vorstehend ausgeführt, der Betrag der Schichtspannung in den Beschichtungen nach Ausführungsformen höchstens 800 MPa, bevorzugt höchstens 500 MPA und besonders bevorzugt höchstens 300 MPa. Mit anderen Worten ist die Schichtspannung vorzugsweise ±800 MPa, bevorzugt höchstens ±500 MPa und besonders bevorzugt höchstens ±300 MPa.It is therefore possible according to this embodiment that the coating comprises a nucleating agent. Since the mole fraction of component C in the coating is small, a doped mixed oxide of the formula A _x B _y O _{4 is} obtained, with the main properties of the mixed oxide still being determined by the main components A and B due to a small proportion of a dopant, such as for example the crystal structure. In the context of the present disclosure, a mixed oxide of the general formula A _x B _y O _{4 is} also understood to mean a doped mixed oxide of the general formula A _x B _y C _z O ₄ , provided that component C is at most 10%, based on the mole fraction, and possibly less, is available. The mole fraction can also be given by the ratio of the indices x, y and z to each other, whereby the mole fraction (SMA) is calculated according to the following formula: $$\text{SMA}=\text{z}/\left(\text{x + y + z}\right).$$

In a cover plate obtained in a method according to one embodiment, as also stated above, the amount of layer stress in the coatings according to embodiments is preferably at most 800 MPa, preferably at most 500 MPA and particularly preferably at most 300 MPa. In other words, the layer stress is preferably ± 800 MPa, preferably at most ± 500 MPa and particularly preferably at most ± 300 MPa.

It is also surprising that the coating or the mixed oxide comprised by the coating is at least partially crystalline, especially when it is a mixed oxide which is present in the spinel structure or the inverse spinel structure or also in the olivine structure. This is because it is known that the formation of such crystalline structures generally requires high temperatures, for example when producing powder (see example Alhaji et al, Optical Materials 98 (2019) , Section 2, with temperatures of at least 1400 ° C, or Orlinski et al., Journal of the European Ceramic Society 39 (2019) , Section 2, where temperatures of 1000 ° C are mentioned, whereby a eutectic is used here) or in the production of single crystals (see for example Takebuchi et al., Radiation Physics and Chemistry 177 (2020), Section 2, where in particular a temperature of 1400 ° C).

Surprisingly, with the method according to the present application, at least partial crystallinity can be achieved even at low temperatures of at most 350 ° C. in the sputtering chamber, which are otherwise usually used at most for drying precursor materials (see Orlinski et al, loc. Cit.).

The present disclosure therefore also relates in particular to a cover plate, in particular a cover plate according to the embodiments described above, produced or producible in a method according to embodiments of the present disclosure, as well as the use thereof.

Figure list

• 1 bis 3 verschiedene Ausführungsformen von Abdeckplatten.

The invention is explained further below with reference to figures. In the figures, the same reference symbols denote the same or corresponding features. Show it

• 1 until 3 different embodiments of cover plates.

1 shows a first embodiment of a cover plate 1 according to the present application in a schematic and not to scale sectional view through a cover plate 1 . The cover plate 1 comprises a glass or glass ceramic substrate 10 with a first main area 11 and a second major surface 12th as well as one on one of the main surfaces 11 , 12th , here namely the main area 12th , arranged coating 2 . The coating 2 is in at least one area 100 the cover plate 1 or the glass or glass ceramic substrate 10 arranged.

The coating 2 comprises a mixed oxide of the formula A _x B _y O ₄ or consists predominantly, i.e. at least 50% by weight, or essentially, i.e. at least 90% by weight, or even completely of a mixed oxide of the formula A _x B _y O _4th The molar ratio of A to B is between at least 0.3 and at most 0.7. In particular, the molar ratio can be 0.5. The mixed oxide and / or the coating 2 are at least partially crystalline, in particular polycrystalline. A preferably comprises Fe, Mg, Be, Zn, Co, Si, Mn or a mixture thereof. B preferably comprises Al, Fe, Cr, V or a mixture thereof. The coating preferably has 2 a light transmittance of more than 70%.

The area 100 is designed here so that in this area 100 just the coating 2 and the glass or glass-ceramic substrate 10 are arranged. In other words, the area forms here 100 a sub-area 101 in which only the coating 2 only on one main area, here on the main area 12th , is arranged. Such a sub-area 101 of the area 100 is exemplary and not true to scale also for a further embodiment of a cover plate 1 in 2 shown in the form of a schematic and not to scale sectional illustration. In 2 is also another coating 3 on the main area 12th of the glass or glass ceramic substrate 10 shown.

Preferably the cover plate is 1 designed so that in at least the partial area 101 of the area 100 in which only the coating 2 on only one main area 11 , 12th , here the main area 12th of the glass or glass ceramic substrate 10 is arranged, it has a light transmittance of more than 70%.

In general, without being limited to the exemplary embodiment of a cover plate shown here 1 however, it is also possible that on the main surfaces 11 , 12th of the glass or glass ceramic substrate 10 further coatings 3 are arranged, in particular also in the area 100 . These other coatings 3 can for example be arranged on the same main surface as the coating 2 , taking them the coating 2 can generally be subordinate or superimposed. Other coatings 3 can be, for example, conductor tracks or haptic coatings or, for example, also glass flow-based coatings or enamels or enamel coatings. In 2 is shown that the further coating 3 on the same major surface 12th of the glass or glass ceramic substrate 10 is arranged like the coating 2 , the further coating 3 here in direct contact with the main surface 12th of the glass or glass ceramic substrate 10 stands and between the glass or glass ceramic substrate 10 and the coating 2 is arranged. Such an arrangement of the coating can be preferred in particular when the coating 2 mechanically particularly stable and / or chemically particularly inert and then also the further coating 3 from the coating 2 should be covered as a topcoat, so that overall a particularly mechanically and / or chemically resistant surface of a cover plate 1 will be obtained.

According to the present embodiment, the cover plate also includes an area 110 , in which no coating is formed, but only the glass or glass ceramic substrate 10 is present. This is for example in 1 designated.

The coating 2 According to a preferred embodiment, it has a thickness between 0.05 μm or more and 3 μm or less. Thinner coatings are generally not thick enough, even if they include a mechanically and / or chemically resistant material, such as the material AB ₂ O _{4 here} , or consist predominantly or essentially or even completely of such a resistant material, as in this case for example the wear resistance of a surface of a glass or glass ceramic substrate 2 to improve sufficiently. On the other hand, coatings that are more than 3 µm thick tend to form cracks and furthermore it takes a long time to deposit such a thick coating, which is no longer economically viable.

wobei der Farbort E₁₁₀ gegeben ist durch die Farbkoordinaten a*₁₁₀, b*₁₁₀, L*₁₁₀ und der Farbort E₁₀₁ gegeben ist durch die Farbkoordinaten a*₁₀₁, b*₁₀₁, L*₁₀₁ und vorzugsweise jeweils bestimmt ist in einer Messung gegen eine Weißkachel, insbesondere mit einem Spektrophotometer CM-700d der Firma Konica-Minolta.It is beneficial if the coating 2 transparent and uncolored. Because then the coating is 2 visually inconspicuous. In the context of the present disclosure, the coating is preferably referred to as transparent, uncolored if the color location E _{101 of} the cover plate is 1 in the sub-area 101 in which only the coating 2 on a main area 11 , 12th of the glass or glass ceramic substrate 10 is arranged, from the color point E ₁₁₀ , the cover plate in an area 110 in which no coating on the glass or glass ceramic substrate 10 is arranged to differ by a value ΔE less than 20, preferably less than 15, particularly preferably less than 10, the color location E ₁₁₀ in the sub-area 110 and the color location E ₁₀₁ in the area 101 are particularly preferably determined in the L * a * b * color system and the color locus difference ΔE is calculated using the following formula: $$\Delta \mathrm{E.}=\sqrt{\left({\left(a_{110}^{*}-a_{101}^{*}\right)}^2+{\left({\mathrm{<figure-callout\; id="110"\; label="b"\; filenames="DE102021110208A1\_0006.png"\; state="\{\{state\}\}">b</figure-callout>}}_{110}^{*}-{\mathrm{<figure-callout\; id="101"\; label="b"\; filenames="DE102021110208A1\_0006.png"\; state="\{\{state\}\}">b</figure-callout>}}_{101}^{*}\right)}^2+{\left({\mathrm{L.}}_{110}^{*}-{\mathrm{L.}}_{101}^{*}\right)}^2\right)}.$$

The color location E _{110 is} given by the color coordinates a * ₁₁₀ , b * ₁₁₀ , L * ₁₁₀ and the color location E _{101 is} given by the color coordinates a * ₁₀₁ , b * ₁₀₁ , L * ₁₀₁ and is preferably each determined in one measurement against a white tile, especially with a CM-700d spectrophotometer from Konica-Minolta.

The cover plate 1 preferably has a thickness between at least 2 mm and at most 8 mm. The cover plate is preferably at least 4 mm thick. The thickness of the cover plate is also preferred 1 at most 6 mm. Is the cover plate 1 If made too thin, it does not have sufficient mechanical resistance with regard to the fracture behavior. In particular, the impact resistance and / or the flexural strength may not be sufficient, for example, for use as a hotplate or as a viewing panel, in particular for viewing panels for hot applications. Is the cover plate 1 but too thick, then the plate will be too heavy. It can also be that the transmission properties, for example in the IR range and / or in the visible light range, are too poor. For example, if the cover plate is too thick, which is used, for example, as a window in a stove or a chimney, then no sufficient penetration of thermal radiation into the room to be heated can take place. Will the cover plate 1 For example, used as a hotplate, it may be that if the cover plate is too thick 1 a sufficiently rapid parboiling can no longer be guaranteed.

Another schematic representation, not true to scale, of a sectional view through a cover plate 1 show the 3 . Here the arrangement of the coatings corresponds 2 and 3 those in 2 . In contrast to the glass or glass ceramic substrate 10 from the 1 and 2 in which both major surfaces 11 , 12th are smooth, the main surface is here 11 not smooth, but nubbed in front. Such a design of a cover plate can be advantageous, for example, if the cover plate has a particularly high impact resistance and / or flexural strength 1 necessary is. Because the knobs, which can be arranged in particular on a main surface, which in operational use of the cover plate 1 is turned away from the user, have a strength-increasing effect, since cracks on the knobbed underside do not spread as easily and thus cannot lead to breakage of the cover plate as easily as with a smooth underside.

According to one embodiment of the cover plate 1 the cover plate is designed so that it is in the partial area 101 of the area 100 the cover plate 1 or the glass or glass ceramic substrate 10 or the cover plate 1 in which only the coating 2 on only one main area 11 , 12th of the glass or glass ceramic substrate 10 is arranged, a haze of less than 5%, preferably of less than 2% and particularly preferably of less than 1%, measured according to ASTM-D 1003. This means that the cover plate in the partial area of the cover plate 1 or the glass or glass ceramic substrate 10 in which only the coating on only one main surface 11 or 12th of the glass or glass ceramic substrate 10 is arranged, has only a very low turbidity. The cover plate 1 is therefore in this sub-area 101 very clear, so there is only a slight scattering of light. This is advantageous for a particularly good view through the cover plate 1 .

It is also advantageous if the cover plate 1 or the coating 2 is designed so that the coating 2 has a hardness of 6 GPa to 11 GPa, determined in a measuring method according to or based on DIN EN ISO 14577 (so-called Martens hardness). Because in this way the coating can 2 Especially when it is applied as the top coating on a cover plate, it has a particularly good effect unfold as a wear-resistant coating, ie protect the surface of the cover plate against scratches, for example.

Furthermore, according to a further embodiment of the cover plate 1 this designed so that the coating 2 a main area 11 , 12th of the glass or glass ceramic substrate 10 essentially covered over the entire area, that is to say at least 90% of the main area, preferably even at least 95% of the main area. This is particularly advantageous when the coating 2 is made very hard and / or very abrasion-resistant, because then the one with the coating 2 The area covered essentially over the entire surface is designed to be particularly wear-resistant, for example particularly scratch-resistant and / or abrasion-resistant.

According to a further embodiment of the cover plate 1 is the cover plate 1 designed to have another coating 3 having. It is general, without limitation to the designs of the cover plate shown in the figures 1 , possible that the cover plate a variety of other coatings 3 includes, for example, conductor tracks or other coatings such as masks, in particular also coatings that are on the main surface of the glass or glass ceramic substrate 10 are arranged as the coating 2 . In particular, however, it is possible that a coating 3 on the same main area, according to 2 and 3 here on the main area 12th , is arranged like the coating 2 . The further coating 3 covers this main area at least partially or only partially. Especially if the further coating 3 is designed as a glass flow-based coating, in particular as a pigmented glass flow-based coating, so for example as an enamel coating, the coating 3 not be applied over the entire surface, but only partially cover the main surface.

For example, the coating 3 in this case be applied as a cooking zone marking. It is also possible that the coating 3 is applied in the form of a grid on the main surface. This can be advantageous in particular when the main surface is particularly resistant to scratches or abrasion, as a further coating 3 , which is designed as a pigmented glass-flow-based coating, is usually several micrometers thick and can in this way serve as a spacer, for example, between a base of a cookware and the main surface of the glass or glass ceramic substrate. The further coating 3 is here wiping the glass or glass ceramic substrate 10 and the coating 2 arranged. This is advantageous because in this way not only the spacer effect of the further coating 3 remains, but also the further coating 3 through the coating 2 is covered. Especially when the coating 2 is scratch-resistant and / or abrasion-resistant and / or designed to be particularly hard, the further coating is thus also 3 through the coating 2 Protected from scratches and / or abrasion.

According to a further embodiment of the cover plate 1 can be the glass or glass ceramic substrate 10 transparent uncolored or transparent colored. For certain applications, for example for viewing panes, it can be particularly advantageous if the glass or glass ceramic substrate 10 does not have strong absorption, such as, for example, due to metal ions present in the glass ceramic or the glass, which color due to absorption. In this case, the glass or glass-ceramic substrate 10 advantageously be transparent and uncolored. For other applications, if, for example, it is supposed to be difficult to see through, it can be more advantageous if the glass or glass ceramic substrate 10 transparent colored is present, for example when using the cover plate 1 as a hotplate.

According to a further embodiment of the cover plate 1 is the coating 2 on the main area 11 , 12th arranged, which in operational use of the cover plate 1 is facing the user and is therefore designed as a top or front.

List of reference symbols

1

Cover plate

10

Glass or glass ceramic substrate

11, 12

Major surfaces of the glass or glass ceramic substrate

100

Area of the cover plate

101

Part of area 100

110

Area of the cover plate without coating

2

Coating

3

further coating

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 0334760 B1 [0015]
• US 4029755 A [0016]
• EP 3502075 A1 [0017, 0018]

Non-patent literature cited

• Ruske et al., Thin solid films 351, (1999) [0040]
• DIN EN ISO 13468 [0044, 0046]
• DIN EN ISO 14577-1 and -4 [0055]
• Alhaji et al, Optical Materials 98 (2019) [0076]
• Orlinski et al., Journal of the European Ceramic Society 39 (2019) [0076]
• DIN EN ISO 14577 [0091]

Claims (14)

A cover plate (1) comprising a glass or glass ceramic substrate (10) with a first main surface (11) and a second main surface (12) and one on at least one of the main surfaces (11, 12) of the glass or glass ceramic substrate (10) in at least Coating (2) arranged in an area (100) of the cover plate (1), the coating (2) _{comprising at least one mixed oxide of the formula A x} B _y O ₄ or predominantly or essentially or completely of at least one mixed oxide of the formula A _x B _y O ₄ , the molar ratio of A to B being between at least 0.3 and at most 0.7, the mixed oxide and / or the coating (2) being at least partially crystalline, in particular polycrystalline, and A preferably comprising Fe, Mg, Be, Zn, Co, Si, Mn, or mixtures thereof and where B preferably comprises Al, Fe, Cr, V or mixtures thereof, and where the coating (2) preferably has a light transmittance of more than 70%. Cover plate (1) Claim 1 wherein the coating (2) has a thickness between 0.05 µm or more and 3 µm or less. Cover plate (1) according to one of the Claims 1 or 2 , the coating (2) being transparent and uncolored, the coating (2) preferably being referred to as transparent uncolored when the color location E _{101 of} the cover plate (1) is in the sub-area (101) in which only the coating (2 ) is arranged on a main surface (11, 12) of the glass or glass ceramic substrate (10), from the color point E _{110 of} the cover plate (1) in an area (110) in which there is no coating on the glass or glass ceramic substrate (10) is arranged, differs at most by a value ΔE of less than 20, preferably less than 15, particularly preferably less than 10, the color location E ₁₁₀ in the sub-area (110) and the color location E ₁₀₁ in the area (101) being particularly preferred are determined in the L * a * b * color system and the color locus difference ΔE is calculated using the following formula: $$\Delta \mathrm{E.}=\sqrt{({\left(a_{110}^{*}-a_{101}^{*}\right)}^2+{\left(b_{110}^{*}-b_{101}^{*}\right)}^2+\left({\mathrm{L.}}_{110}^{*}-{\mathrm{L.}}_{101}^{*}\right){}^2)}.$$

The color location E _{110 is} given by the color coordinates a * ₁₁₀ , b * ₁₁₀ , L * ₁₁₀ and the color location E _{101 is} given by the color coordinates a * ₁₀₁ , b * ₁₀₁ , L * ₁₀₁ and is preferably each determined in one measurement against a white tile in particular with a CM-700d spectrophotometer from Konica-Minolta. Cover plate (1) according to one of the Claims 1 until 3 , wherein the cover plate has a thickness between 2 mm and 8 mm, preferably between 4 mm and 6 mm. Cover plate (1) according to one of the Claims 1 until 4th wherein the cover plate (1) is arranged in the partial area (101) of the area (100) of the cover plate (1) in which only the coating (2) is arranged on only one main surface (11, 12) of the glass or glass ceramic substrate (10) has a haze of less than 5%, preferably less than 2% and particularly preferably less than 1%, measured in accordance with ASTM-D 1003. Cover plate (1) according to one of the Claims 1 until 5 , the coating (2) having a hardness of 6 GPa to 11 GPa, determined in a measuring method according to or based on DIN EN ISO 14577-1 and -4. Cover plate (1) according to one of the Claims 1 until 6th wherein the coating (2) covers a main surface (11, 12) of the glass or glass ceramic substrate (10) essentially over the entire surface. Cover plate (1) according to one of the Claims 1 until 7th , having a further coating (3), the further coating (3) being arranged on the same main surface (11, 12) of the glass or glass ceramic substrate (10) as the coating (2) and this main surface (11, 12) at least or only partially covered, the further coating (3) being arranged between the glass or glass ceramic substrate (10) and the coating (2). Cover plate (1) according to one of the Claims 1 until 8th , wherein the glass or glass ceramic substrate (10) - is transparent and uncolored or - is transparent colored. Cover plate (1) according to one of the Claims 1 until 9 , wherein the coating (2) is arranged on the main surface (11, 12) which, when the cover plate (1) is in use, faces the user and is thus designed as a top or front side. A method for producing a cover plate (1), preferably a cover plate (1) according to one of the Claims 1 until 10 , comprising the steps: - providing a glass or glass ceramic substrate (10) - introducing the glass or glass ceramic substrate (10) into a coating chamber - providing a ceramic or metallic target comprising the components A and B, where A preferably comprises Fe, Mg, Be, Zn, Co, Si, Mn, or mixtures thereof and where B preferably comprises Al, Fe, Cr, V or mixtures thereof, - providing a gas as reactive gas, the gas preferably being oxygen - setting a pressure in the coating chamber, the pressure being between at least 1 * 10 ^-3 mbar and at most 5 * 10 ^-2 mbar, setting a temperature of more than 40 ° C in the coating chamber, the production temperature preferably being at most 350 ° C, coating by vapor deposition or Sputtering, where the sputtering can take place as DC sputtering or as pulsed sputtering, for example as medium-frequency or high-frequency sputtering, so that at least one Hau The surface (11, 12) is at least partially coated with a coating (2) comprising one or predominantly or essentially or completely consisting of a mixed oxide of the formula A _x B _y O ₄ , the molar ratio of A to B being between at least 0.3 and is at most 0.7, the mixed oxide and / or the coating (2) being at least partially crystalline, in particular polycrystalline. where A preferably comprises Fe, Mg, Be, Zn, Co, Si, Mn, or mixtures thereof and where B preferably comprises Al, Fe, Cr, V or mixtures thereof, and where the coating (2) preferably has a light transmittance of more than 70%. A method for producing a cover plate (1), preferably a cover plate (1) according to one of the Claims 1 until 10 , comprising the steps: - providing a glass or glass ceramic substrate (10) - introducing the glass or glass ceramic substrate (10) into a coating chamber - providing a ceramic or metallic target comprising the components A and B, where A preferably comprises Fe, Mg, Be, Zn, Co, Si, Mn, or mixtures thereof and where B preferably comprises Al, Fe, Cr, V or mixtures thereof, - providing a gas as reactive gas, the gas preferably being oxygen - setting a pressure in the coating chamber, the pressure being between at least 1 * 10 ^-3 mbar and at most 5 * 10 ^-2 mbar, setting a temperature of more than 40 ° C in the coating chamber, the production temperature preferably being at most 350 ° C, coating by vapor deposition or Sputtering, where the sputtering can take place as DC sputtering or as pulsed sputtering, for example as medium-frequency or high-frequency sputtering, so that at least one Hau The surface (11, 12) is at least partially coated with a coating (2) comprising one or predominantly or essentially or completely consisting of a mixed oxide of the formula A _x B _y O ₄ , the molar ratio of A to B being between at least 0.3 and is at most 0.7, the mixed oxide and / or the coating (2) being at least partially crystalline, in particular polycrystalline. where A preferably comprises Fe, Mg, Be, Zn, Co, Si, Mn, or mixtures thereof and where B preferably comprises Al, Fe, Cr, V or mixtures thereof, and where the coating (2) preferably has a light transmittance of more than 70%, furthermore having at least one of the following features: post-treatment of the coating (2) by a further process step in the form of thermal treatment in an oven, preferably a ceramization oven or in a tempering oven, by laser entry, by flash lamp treatment, by UV - Follow-up treatment, through additional plasma input such as eg by means of oxygen plasma in a vacuum and / or by means of plasma lines in the atmosphere and / or by means of flame, an addition of a further component comprising or consisting of titanium or silicon or a mixture of these two elements, the proportion of the further component being less than 10%, preferred less than 5% and particularly preferably less than 2%, based on the amount of substance or amount of substance, so that a coating comprising a compound A _x B _y C _z O ₄ with z is or will be obtained . Cover plate, in particular cover plate according to one of the Claims 1 until 10 , manufactured or manufactured in a process according to Claim 11 or Claim 12 . Use of a cover plate (1) according to one of the Claims 1 until 10 or 13th and / or produced in a process according to Claim 11 or after Claim 12 as a cooking surface, display, oven viewing panel, scanner cover, optical component / optical filter, viewing pane, worktop, window, pane in the consumer electronics sector, glass packaging, watch glass, protective pane.

Images