ceramic glass element for a cooking appliance

Abstract

The present invention relates to a glass-ceramic article for a cooking device, comprising a glass-ceramic substrate formed from a glass-ceramic material, the substrate having a first face intended to receive cooking elements, the substrate comprising a matte zone, the matte zone comprising at least a portion of the first face, the portion of the first face having a profile exhibiting a peak density RPc between 125 and 3000. FIG. 1

Description

Title of the invention: Vitreous ceramic article for a cooking device Scope of the invention

[0001] The present invention relates to a glass-ceramic article for a cooking device. The invention also relates to a method for manufacturing such an article. Prior art

[0002] It is known to reduce the effect of fingerprints on a glass-ceramic article for a cooking device by texturizing a main face of the article.

[0003] To this end, document FR 3 078 066 describes a process for texturizing the main face of a glass-ceramic article by depositing an enamel comprising pigments onto one face of the parent glass before ceramization. The parent glass coated with the enamel is ceramized. After ceramization, the enamel has a roughness Ra greater than 0.4 µm and a roughness Rt greater than 4 µm, making it possible to reduce the effect of fingerprints compared to a glass-ceramic article without such texturization.

[0004] Independently, it is known to treat one face of a glass-ceramic article of a cooking surface so as to increase the acoustic absorption of the article, which makes it possible, for example, to limit the noise emissions when moving cooking utensils on the article such as pans.

[0005] However, no glass-ceramic article has a matte area that simultaneously reduces the visibility of fingerprints on the article for a user and, on the other hand, limits noise emissions due to the movement of cooking utensils on the matte area. Description of the invention

[0006] An object of the invention is to provide a glass-ceramic article having a matte area which jointly reduces the visibility of fingerprints on the article and limits noise emissions due to the movement of cooking utensils on the matte area.

[0007] This objective is achieved, at least partially, within the scope of the present invention by means of a glass-ceramic article for a cooking device, the article comprising a glass-ceramic substrate formed by a first glass-ceramic material, the substrate having a first face intended to receive cooking elements by direct contact and a second face opposite to the first face with respect to the substrate, the substrate comprising a matte zone, the matte zone comprising at least a portion of the first face, the portion of the first face having a profile having a peak density RPc between 125 and 3000, especially between 175 and 1500, and preferentially between 200 and 350.

[0008] The present invention is advantageously complemented by the following features, taken individually or in any of their technically possible combinations:

[0009] - the profile exhibits an arithmetic mean deviation Ra of less than 2 pm, in particular between 0.01 pm and 2 pm, and preferably between 0.02 pm and 1 pm,

[0010] - the profile has a total height Rt between 1 pm and 10 pm, in particular between 2 pm and 8 pm and preferably between 4 pm and 6 pm,

[0011] - the matte area has a blur factor between 20% and 50%, in particular between 25% and 45% and preferably between 30% and 40%,

[0012] - the part of the first face is formed at least in part by a network two-dimensional ridges spreading over a principal plane following the part of the first face,

[0013] - the first material comprises at least one first element chosen from sodium, potassium, calcium and barium, a portion of the first material forming the portion of the first face, the portion of the first material extending, according to the thickness of the substrate, from the portion of the first face to a depth between 0.1 pm and 2.0 pm of the portion of the first face, the portion of the first material exhibiting a depletion of the content of the first element relative to an average content of the first element in the substrate, and preferably the portion of the first material exhibiting a content of the first element less than one-fifth of the average content of the first element in the substrate,

[0014] - the first material comprises at least one second element selected from lithium and magnesium, a portion of the first material forming the portion of the first face, the portion of the first material extending along the thickness of the substrate from the portion of the first face to a depth between 0.1 pm and 2.0 pm of the portion of the first face, the portion of the first material exhibiting an enrichment of the content of the second element relative to an average content of the second element in the substrate, and preferably the portion of the first material exhibiting a content of the second element greater than 110% of the average content of the second element in the substrate,

[0015] - the substrate is monolithic, the first material being formed by a plurality of elements, the content of each element being constant and / or varying continuously with respect to a direction parallel to a thickness of the substrate,

[0016] - a part of the first material forms part of the first face, the portion of the first material extending along the thickness of the substrate from the portion of the first face to a depth between 0.1 pm and 2.0 pm of the portion of the first face, and preferably equal to 0.1 pm, the portion of the first material having a crystalline phase, preferably a quartz-[3,

[0017] - the part of the first material has a volume fraction in crystalline phase quartz-[3 greater than 50%, in particular greater than 60% and preferably greater than 70%,

[0018] - the article comprises a first layer printed on part of the first face,

[0019] -the article includes a second layer printed on the second side.

[0020] Another aspect of the invention is a method for manufacturing an article according to an embodiment of the invention, comprising the successive steps of: a) supply of a glass substrate formed by a second glass material, the glass substrate having a principal face, b) surface treatment of a portion of the glass substrate forming part of the main face, the portion of the glass substrate extending along the thickness of the glass substrate from the portion of the main face to a depth of between 0.1 pm and 2.0 pm from the portion of the main face, the surface treatment comprising subsequent substeps of: - application of a treatment layer made of a third material onto the main surface area, - heat treatment of the assembly formed by the glass substrate and the treatment layer, and - removal of the treatment layer from the part of the main face, c) ceramicizing heat treatment of the glass substrate, the glass substrate forming the glass-ceramic substrate after the ceramicizing heat treatment, the part of the main face forming the part of the first face after the ceramicizing heat treatment.

[0021] Advantageously, the surface treatment is implemented by enriching the part of the glass substrate forming the main face with at least one first element chosen from sodium, potassium, calcium and barium.

[0022] Advantageously, the removal of the treatment layer is a mechanical removal.

[0023] Advantageously, the third material comprises a glass fritt.

[0024] Advantageously, the heat treatment of the assembly formed by the glass substrate and the treatment layer is carried out at a temperature between 570 °C and 640 °C, for a duration between 15 minutes and 150 minutes, in particular between 15 minutes and 90 minutes, and preferably between 30 minutes and 60 minutes.

[0025] Advantageously, the third material comprises an average mass content of first element strictly greater than the average mass content of first element in the glass substrate. Description of the figures

[0026] Other features, objectives and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which:

[0027] [Fig-1] - [Fig.1] schematically illustrates an article according to one embodiment of the invention,

[0028] [Fig.2] - [Fig.2] schematically illustrates a section of an article according to one embodiment of the invention,

[0029] [Fig.3] - [Fig.3] is an image obtained by a scanning electron microscope of a section of an article according to an embodiment of the invention,

[0030] [Fig.4] - [Fig.4] is an image obtained by a scanning electron microscope of a first face of an article according to an embodiment of the invention,

[0031] [Fig.5] - [Fig.5] is an image obtained by a scanning electron microscope of a first face of an article according to an embodiment of the invention,

[0032] [Fig.6] - [Fig.6] illustrates a variation in a normalized mass content of sodium in the substrate of an article according to an embodiment of the invention,

[0033] [Fig.7] - [Fig.7] illustrates a variation in a normalized mass content of lithium in the substrate of an article according to an embodiment of the invention,

[0034] [Fig.8] - [Fig.8] schematically illustrates a section of an article according to an embodiment of the invention comprising layers printed on the substrate,

[0035] [Fig.9] - [Fig.9] schematically illustrates a method for manufacturing an article according to an embodiment of the invention,

[0036] [Fig. 10] - the [Fig. 10] schematically illustrates sub-steps of the surface treatment step of a manufacturing process for an article according to an embodiment of the invention.

[0037] Throughout all the figures, similar elements bear identical reference numerals. Definitions

[0038] The parameters associated with a surface texture and a surface profile are measured according to the methods defined in the international standards ISO 4287 and ISO 4288. The international standard ISO 4287 is considered in its version including the first amendment, defining the number of peaks.

[0039] The international standard ISO 4287 defines a maximum height of a profile Rz as the sum of the greatest of the projection heights Zp of the profile and the greatest of the hollow depths Zv inside a reference length L.

[0040] The international standard ISO 4287 defines an average width of the profile elements RSm as the average value of the widths XSi of the profile elements, within a predetermined length, according to the following formula: RSm=ÀL"1(Xs)(1)

[0041] The average width of the RSm profile elements requires height and spacing discrimination. The height discrimination must be 10% of Rz and the spacing discrimination must be 1% of the reference length L. Both conditions must be met.

[0042] The international standard ISO 4287 defines the number of peaks (which will be referred to interchangeably as "number of peaks" as in ISO 4287 or "peak density" in the present), as the number of average widths of the profile elements RSm in a reference length L, according to the following formula (2): The reference length L is equal to 10 mm. When calculating the number of peaks, a height discrimination of ±0.5 qm is recommended for the calculation of RSm.

[0043] The international standard ISO 4287 defines the total height of the profile Rt as being the sum of the greatest of the projection heights of the profile and the greatest of the hollow depths of the profile inside the profile.

[0044] The international standard ASTM 1003 defines the haze factor, also known as the blur factor, expressed as a percentage. This factor is defined with a D65 illumination and with an observer inclined at 2.5°. The haze factor is equal to the ratio between the diffuse light transmission (expressed as a percentage) and the total light transmission (expressed as a percentage).

[0045] Preferably, a glass substrate can be a substrate formed from a material suitable for becoming a glass-ceramic material after heat treatment of the glass substrate. The glass substrate can be a mother glass for a glass-ceramic substrate, also called a precursor glass for a glass-ceramic substrate. Detailed description of the invention Article 1 glass-ceramic

[0046] With reference to [Fig. 1], one aspect of the invention is a glass-ceramic article 1 for a cooking device 2. Article 1 comprises a glass-ceramic substrate 3 formed from a first glass-ceramic material. The substrate 3 has a first Face 4 is intended to receive cooking elements 5 by direct contact. A cooking element may be, for example, a saucepan or a frying pan. Article 1 includes a second face 6 opposite the first face 4 with respect to the substrate 3. When article 1 is mounted in a cooking appliance 2, the first face 4 may be described as the upper face with respect to the floor and the second face 6 may be described as the lower face with respect to the floor. The glass-ceramic substrate 3 is preferably flat.

[0047] The substrate 3 includes a matte zone 7. The matte zone 7 includes at least a part of the first face 4. The part of the first face 4 has a profile having a peak density RPc between 125 and 3000, in particular between 175 and 1500, and preferably between 200 and 350.

[0048] Thus, with reference to [Fig.2], [Fig.3], [Fig.4] and [Fig.5], the aforementioned peak density RPc is representative of a two-dimensional network of peaks and valleys in a principal plane of the first face 4. The topological characteristics of this two-dimensional network represent a pleated surface formed of peaks and valleys, the gaps of which jointly reduce the visibility of fingerprints on the article for a user compared to known articles and limit the noise emissions due to the movement of cooking utensils on the matte area.

[0049] With reference to [Fig.8], article 1 may include a first layer 8 printed on the part of the first face 4. Article 1 may also include a second layer 9 printed on the second face 6. The printed layer(s) may allow the substrate to be decorated with visual indications, optical filters, or to be opacified with article 1.

[0050] Topology and roughness of the first face 4 of the matte zone 7

[0051] Preferably, the profile has an arithmetic mean deviation Ra of less than 2 pm, in particular between 0.01 pm and 2 pm, and preferably between 0.1 pm and 1 pm, in particular between 0.4 pm and 0.65 pm.

[0052] Preferably, the profile has a total height Rt between 1 pm and 10 pm, in particular between 2 pm and 8 pm and preferably between 4 pm and 6 pm.

[0053] Preferably, the matte area 7 has a blur factor between 20% and 50%, in particular between 25% and 45% and preferably between 30% and 40%.

[0054] With reference to [Fig. 2], [Fig. 3], [Fig. 4], and [Fig. 5], the first face 4 may be formed, at least in part, by a two-dimensional network of ridges extending along a principal plane following the portion of the first face 4. Generally, a peak of the portion of the surface 4 may be rounded and / or have a sharp edge. The edge can be formed by a discontinuity of the first material on part of the surface 4, as illustrated by [Fig.3].

[0055] Fig. 3 is an image obtained by a scanning electron microscope illustrating a section of the substrate 3 comprising part of the first face 4. The scale bar represents a length of 5 pm.

[0056] Figures 4 and 5 are scanning electron microscope images illustrating the portion of surface 4 forming the matte area 7. In Figure 4, the magnification used is 500X and the scale bar represents a length of 100 pm. In Figure 5, the magnification used is 2000X and the scale bar represents a length of 30 pm.

[0057] Spatial distribution of the content of element(s) in the substrate 3

[0058] With reference to [Fig. 6], the first material may comprise at least one first element selected from sodium, potassium, calcium, and barium. A portion of the first material forms part of the first face 4. This portion of the first material extends, depending on the thickness of the substrate 3, from part of the first face 4 to a depth of between 0.1 pm and 2.0 pm of part of the first face 4. This portion of the first material may exhibit a depletion of the first element content relative to an average first element content in the substrate 3. In particular, this portion of the first material may have a first element content less than one-fifth of the average first element content in the substrate 3, and preferably less than one-tenth of the average first element content in the substrate 3.The inventors discovered that this characteristic is representative of a manufacturing process of Article 1 comprising a step, prior to ceramization, in which the surface of a precursor substrate (or mother glass) is treated with substrate 3 by depositing a treatment layer, thermally treating the entire assembly, and then removing the treatment layer, so as to enrich the treated portion of the precursor substrate in at least one element selected from sodium, potassium, calcium, and barium. As described below, the surface treatment results in a reorganization of the constituent elements of the glass substrate (or precursor) in the portion of the glass substrate in contact with the treatment layer 12. Following the ceramization of the precursor substrate, the inventors discovered, counterintuitively, a depletion of the first element in the portion of the first material.

[0059] Figure 6 illustrates such a depletion for the element sodium. In particular, Figure 6 illustrates a variation in the normalized mass content of sodium with distance or depth to the portion of the first face 4. Curves (a) and (b) illustrate variations in the normalized mass content of sodium for portions of the first face 4 excluded from a matte area 7. Curves (c) and (d) illustrate variations in normalized mass content of sodium for parts of the first face 4 of the matte zone 7. Similar depletions were measured for potassium, calcium and barium.

[0060] With reference to [Fig. 7], the first material may comprise at least one second element selected from lithium and magnesium. The portion of the first material may exhibit an enrichment of the second element content relative to an average second element content in substrate 3, and preferably the portion of the first material may exhibit a second element content exceeding 110% of the average second element content in substrate 3. The inventors have discovered that this feature is representative of a manufacturing process for the article comprising a step, prior to ceramization, in which the surface of a precursor substrate (or mother glass) to substrate 3 is treated by depositing a treatment layer, thermally treating the entire surface, and then removing the treatment layer, so as to enrich the treated portion of the precursor substrate in at least one element selected from sodium, potassium, calcium, and barium.As described below, the surface treatment leads to a reorganization of the contents in the constituent elements of the glass substrate (or precursor) in the part of the glass substrate in contact with the treatment layer 12. Following the ceramization of the precursor substrate, the inventors discovered, counterintuitively, an enrichment in the second element in the part of the first material.

[0061] Figure 7 illustrates such an enrichment for the element lithium. In particular, Figure 7 illustrates a variation in the normalized mass content of lithium with distance or depth from the portion of the first face 4. Curves (e) and (f) illustrate variations in the normalized mass content of lithium for portions of the first face 4 excluded from a matte zone 7. Curves (g) and (h) illustrate variations in the normalized mass content of lithium for portions of the first face 4 of the matte zone 7. Similar enrichments have been measured for magnesium.

[0062] The substrate 3 is monolithic and the first material can be formed by a plurality of elements, the content of each element being constant and / or varying continuously with respect to a direction parallel to a thickness of the substrate 3. The substrate 3 does not include a discrete interface delimiting two layers on either side of the interface. Crystalline structure

[0063] The part of the first material defined above extends along the thickness of the substrate 3 from the part of the first face 4 to a depth between 0.1 pm and 2.0 pm of the part of the first face 4, and preferably equal to 0.1 pm.

[0064] The portion of the first material may have a crystalline phase, preferably a quartz-[3] crystalline phase. Preferably, a volume fraction of the crystalline phase, particularly the quartz-[3] crystalline phase, may be greater than 50%, particularly greater than 60%, and preferably greater than 70%. Thus, it is possible to reduce the difference between the volume fraction of the crystalline phase in the portion of the first material and the average volume fraction of the crystalline phase in the substrate 3. Manufacturing process for article 1

[0065] With reference to [Fig.9] and [Fig.10], another aspect of the invention is a method 900 for manufacturing an article 1 according to an embodiment of the invention.

[0066] The process comprises the successive steps of supplying 901 a glass substrate 10, surface treating 902 a portion of the glass substrate, and ceramicizing the glass substrate 903. The glass substrate 10 may be flat.

[0067] As stated, the process 900 includes a step 901 of supplying a glass substrate 10 formed from a second glass material. The glass substrate 10 has a main face 11.

[0068] As stated, the process 900 then includes a surface treatment step 902 of a portion of the glass substrate 10 forming a portion of the main face 11 of the portion of the glass substrate 10. The portion of the main face 11 extends along the thickness of the glass substrate 10 from the portion of the main face 11 to a depth of between 0.1 pm and 2.0 pm of the portion of the main face 11.

[0069] With reference to [Fig. 10], the surface treatment 902 comprises the subsequent substeps of: - deposition 902a of a treatment layer 12 formed by a third material on the part of the main face 11, - 902b heat treatment of the assembly formed by the glass substrate 10 and the treatment layer, and - 902c removal of the treatment layer from the main face part 11.

[0070] As stated, the process 900 then comprises a ceramicizing heat treatment step 903 of the glass substrate. The glass substrate 10 forms the glass-ceramic substrate 3 after the ceramicizing heat treatment 903. The portion of the main face 11 forms the portion of the first face 4 after the ceramicizing heat treatment 903.

[0071] Thus, the surface treatment step 902 leads to a reorganization of the contents of the constituent elements of the glass substrate 10 in the part of the glass substrate 10 in contact with the treatment layer 12. The reorganization occurs more particularly during the heat treatment step of the glass substrate 10 and the treatment layer 12. This reorganization affects the coefficient of expansion In particular, thermal properties allow for a difference between the thermal dilution coefficient of the material forming the portion of the glass substrate 10 after ceramicization and the thermal expansion coefficient of the material forming the remainder of the glass substrate 10. Due to this difference, the portion of the glass substrate 10 undergoes mechanical stresses when transitioning from the ceramicization treatment temperature 903 to ambient temperature. These mechanical stresses cause wrinkling of the portion of the main face 11, which defines the roughness of the first face 4 of the article 1. This roughness simultaneously reduces the visibility of fingerprints on the article 1 for a user and limits noise emissions from the movement of cooking utensils on the matte area.

[0072] The second material comprises a glassy phase having a coefficient of thermal expansion. The surface treatment 902 can be implemented by enriching the portion of the glass substrate 10 forming the main face 11 with at least one first element selected from sodium, potassium, calcium, and barium. Thus, the portion of the glass substrate may, counterintuitively, exhibit a decrease in the coefficient of thermal expansion compared to the rest of the substrate after the ceramicizing heat treatment 903. This decrease results in the wrinkling of the portion of the main face 11 described above. Preferably, the first element can be adapted to increase the coefficient of thermal expansion of the second material and / or to induce reorganizations of the element contents of the second material in the portion of the glass substrate 10.

[0073] The removal of the treatment layer can be mechanical. Mechanical removal can be carried out manually by wiping with a cloth or by sliding, followed by washing the article in a washing machine.

[0074] The third material may include a glass frit. Thus, it is possible to form matte patterns on the first face 4. The treatment layer 12 can be deposited by screen printing. Other deposition methods are also possible, such as inkjet printing.

[0075] The glass frit may include sodium fluoride and / or calcium fluoride crystals. In particular, the glass frit may include opal glass. Thus, the presence of such crystals reduces the adhesion of the enrichment layer to the substrate 10, thereby facilitating its removal.

[0076] The heat treatment of the assembly formed by the glass substrate 10 and the treatment layer can be carried out at a temperature between 570 °C and 640 °C, for a duration between 15 and 150 minutes, in particular between 15 and 90 minutes, and preferably between 30 and 60 minutes. This allows for the exchange of a sufficient quantity of elements between the treatment layer and the substrate 10 so as to The main face 11 of the substrate is pleated as described previously, without irreversibly fixing the treatment layer to the substrate 10 so as to allow its removal. Indeed, at temperatures above the aforementioned ranges, the treatment layer adheres too strongly to the glass substrate 10 and, after ceramic heat treatment, resembles an enamel layer. At temperatures below the aforementioned ranges, the quantities of elements exchanged between the treatment layer and the glass substrate 10 are insufficient to pleat the main face 11.

[0077] The thickness of the treatment layer can be between 5 µm and 50 µm. Indeed, for a thickness greater than the aforementioned range, the treatment layer is difficult to remove. For a thickness less than the aforementioned range, the treatment layer may not contain enough elements to allow efficient diffusion of elements between the treatment layer and the glass substrate 10.

[0078] The third material may comprise a first element mass content strictly greater than the average first element mass content in the glass substrate 10. Preferably, the third material comprises a first element mass content greater than 3%, in particular greater than 5%, and preferably greater than 10%. Thus, the elements migrating from the treatment layer 12 to the glass substrate 10 are the elements that increase the coefficient of thermal expansion of the glassy phase of the glass substrate 10. Surprisingly, such an increase in the first element content relative to the average content of the substrate before the ceramization treatment 903 results in a decrease in the first element content relative to the average content of the substrate after the ceramization treatment 903. Examples and results

[0079] The glass substrate 10 used has a composition in which the element contents are chosen from the following ranges: SiO2: between 49% and 75%, preferably between 63% and 69%, and especially between 65% and 68%. A12O3: between 15% and 30%, preferably between 18% and 24%, and especially between 19.5% and 23%. Li2O: between 1% and 8%, preferably between 2.7% and 4.2%, and especially between 3.4% and 4.2%. K2O: between 0% and 5%, preferably between 0.1% and 0.8%, and especially between 0.2% and 0.8%. Na2O: between 0% and 5%, preferably between 0.1% and 0.8%, and especially between 0.14% and 0.62%. ZnO: between 0% and 5%, preferably between 0% and 2.8%, and in particular between 0.19% and 2.3%. MgO: between 0% and 5%, preferably between 0.1% and 1.2%, and especially between 0.3% and 1.2%. CaO: between 0% and 5%, preferably between 0% and 0.6%, and especially between 0.02% and 0.47%. BaO: between 0% and 5%, preferably between 0.6% and 2.7%, and especially between 0.8% and 2.5%. SrO: between 0% and 5% TiO2: between 0% and 6%, preferably between 2.4% and 3.2%, and especially between 2.6% and 3.0%. ZrO2: between 0% and 5%, preferably between 1.1% and 2.0%, and especially between 1.3% and 1.9%. P2O5: between 0% and 10% B2O3: between 0% and 5%, SnO2: preferably between 0.2% and 0.6%, preferably between 0.25% and 0.3%, As2O3: preferably between 0% and 0.8%, preferably between 0.02% and 0.76%, Fe2O3: preferably between 0.013% and 0.13%, V2O5: preferably between 0.028% and 0.048%, Cr2O3: preferably between 0.0221% and 0.0234%.

[0080] Preferably, the total mass content of colorants in the glass substrate is less than 2% and in particular less than 0.2%.

[0081] For the examples of articles according to embodiments of the invention (example no. 1, example no. 2 and example no. 3), an enrichment layer having a predefined composition is deposited by screen printing on the glass substrate 10.

[0082] A first composition (composition no. 1) of the enrichment layer is defined by the mass content of the following elements: SiO2: 69.6%, A12O3: 8.01%, B2O3: 0.14%, Na2O: 11.9%, K2O: 1.41%, CaO: 1.98%, MgO: < 0.01% BaO: 2.01%, ZrO2: 0.03%, TiO2: 0.07%, Fe2O3: 0.04% F: 4.79%.

[0083] A second composition (composition no. 2) of the enrichment layer is defined by the following mass contents of elements: SiO2: 69.8%, Al2O3: 7.14%, Li2O: < 0.01%, B2O3: 1.77%, Na2O: 13.09%, K2O: 0.03%, CaO: 1.93%; MgO: <0.01%, ZnO: <0.02% BaO: 1.22%, ZrO2: 0.11%, TiO2: 0.04%, Fe2O3: 0.03%, and F: 4.88%.

[0084] Articles 1 according to embodiments of the invention are manufactured according to processes according to embodiments of the invention, as described in examples No. 1, No. 2 and No. 3 of Table 1 below.

[0085] Comparative example no. 1 is a different article of the invention, in which no treatment resulting in a matte area has been implemented.

[0086] Comparative example No. 2 is a different article from the invention, in which the manufacturing process of this article comprises a step of depositing an enamelled mesh, comprising a glass frit. Before the ceramicizing heat treatment, the glass frit has a mass content of 30% talc and 70% of a third composition. The third composition has the following mass contents: SiO2: between 45% and 60%, B2O3: between 6% and 19%, Al2O3: between 9% and 19.5%, Na2O: between 0% and 4.5%, K2O: between 1% and 7%, Li2O: between 0% and 6%, CaO: between 0% and 8%, BaO: between 6.5% and 15.5%, ZnO: between 1.5% and 10.5% MgO: between 0% and 6.5% TiO2: between 0% and 1.5%, and ZrO2: between 0% and 4%.

[0087] Comparative example No. 3 is a different article of the invention, in which the surface treatment has been implemented on a glass-ceramic substrate.

[0088] [Tables] Example no. 1 Example no. 2 Example no. 3 Comparative example no. 1 Comparative example no. 2 Comparative example no. 3 enrichment layer composition no. 100 / 100 100 / 100 100 / 100 Screen printing canvas (number of threads / cm - thread diameter in pm) 100 - 40 77-40 77-40 N / A 165-31 100 - 40 non-ceramized glass substrate non-ceramized non-ceramized non-ceramized glass substrate no ceramized ceramic treatment th Enrichment coating 30 minutes at 600°C 30 minutes at 600°C 30 minutes at 600°C 30 minutes at 600°C Deposition of an enameled layer No No No No Yes No Matte layer Yes Yes Yes No Yes No Homogeneous gloss at 60°C 6.6 6.1 5.8 92 46 81 L* 10.83 12.31 10.65 0.6 7 2.94 a* 0.56 0.55 1.03 0.20 b* -0.55 -0.18 -0.42 -0.69 Ra (pm) 0.4 0.6 0.53 0.1 0.2 0.1 Rt (pm) 3.9 5.1 3.35 1.1 2.5 1.1 RPc 233 214 298 54 122 104 Fingerprints (visibility / 5) 0.7 0.5 0.1 4 0.8 N / A Measurement of pan movement noise (dB(A)) 57.5 + 1.1 N / AN / A 56.4 + 0.2 65.8 + 1.2 N / A

Claims

Demands

1. Article (1) glass-ceramic for a cooking device (2), article (1) comprising a glass-ceramic substrate (3) formed of a first glass-ceramic material, substrate (3) having a first face (4) intended to receive by direct contact cooking elements (5) and a second face (6) opposite to the first face (4) with respect to substrate (3), characterized in that substrate (3) comprises a matte zone (7), matte zone (7) comprising at least a part of the first face (4), part of the first face (4) having a profile having a peak density RPc between 125 and 3000.

2. Article (1) according to the preceding claim, wherein the profile has an arithmetic mean deviation Ra of less than 2 pm.

3. Article (1) according to claim 1 or 2, wherein the profile has a total height Rt between 1 pm and 10 pm.

4. Article (1) according to any one of the preceding claims, wherein the matte area (7) has a blur factor of between 20% and 50%

5. / 0. Article (1) according to any one of the preceding claims, wherein the part of the first face (4) is formed at least in part by a two-dimensional network of ridges spreading over a principal plane along the part of the first face (4).

6. Article (1) according to any one of the preceding claims, wherein the first material comprises at least one first element selected from sodium, potassium, calcium and barium, wherein a portion of the first material forms part of the first face (4), the portion of the first material extending, according to the thickness of the substrate (3), from part of the first face (4) to a depth of between 0.1 pm and 2.0 pm of part of the first face (4), the portion of the first material exhibiting a depletion of the first element content relative to an average first element content in the substrate (3).

7. Article (1) according to any one of the preceding claims, wherein the first material comprises at least one second element selected from lithium and magnesium, in which a portion of the first material forms part of the first face (4), the portion of the first material extending along the thickness of the substrate (3) from part of the first face (4) to a depth between 0.1 pm and 2.0 pm of part of the first face (4), the portion of the first material exhibiting an enrichment of the content of the second element relative to an average content of the second element in the substrate (3).

8. Article (1) according to any one of the preceding claims, wherein the substrate (3) is monolithic, the first material being formed by a plurality of elements, a content of each element being constant and / or varying continuously with respect to a direction parallel to a thickness of the substrate.

9. Article (1) according to any one of the preceding claims, wherein a portion of the first material forms part of the first face (4), the portion of the first material extending along the thickness of the substrate (3) from part of the first face (4) to a depth of between 0.1 pm and 2.0 pm of part of the first face (4).

10. Article (1) according to the preceding claim, wherein the portion of the first material having a volume fraction in quartz-[3] crystalline phase greater than 50%.

11. A method (900) for manufacturing an article (1) according to any one of the preceding claims, comprising the successive steps of: a) supplying (901) a glass substrate (10) formed by a second glass material, the glass substrate (10) having a principal face (11), b) surface treating (902) a portion of the glass substrate (10) forming a portion of the principal face (11), the portion of the glass substrate (10) extending along the thickness of the glass substrate (10) from the portion of the principal face (11) to a depth of between 0.1 pm and 2.0 pm of the portion of the principal face (11), the surface treatment comprising subsequent substeps of: - deposition (902a) of a treatment layer (12) formed by a third material onto the portion of the principal face (11), - heat treating (902b) the assembly formed by the glass substrate (10) and by the treatment layer, and - removal (902c) of the treatment layer from the part of the main face (11), c) ceramicizing heat treatment (903) of the glass substrate (10), the glass substrate (10) forming the glass-ceramic substrate (3) after the ceramicizing heat treatment (903), the part of the main face (11) forming the part of the first face (4) after the ceramicizing heat treatment (903).

12. A method according to claim 11, wherein the surface treatment (902) is carried out by enriching the part of the glass substrate (10) forming the main face (11) in at least one first element selected from sodium, potassium, calcium and barium.

13. Method (900) according to claim 11 or 12, wherein the removal of the treatment layer is a mechanical removal.

14. Method (900) according to any one of claims 11 to 13, wherein the third material comprises a glass frit.

15. A method (900) according to any one of claims 11 to 14, wherein the heat treatment of the assembly formed by the glass substrate (10) and by the treatment layer (12) is carried out at a temperature between 570 °C and 640 °C, for a period of between 15 minutes and 150 minutes, in particular between 15 minutes and 90 minutes, and preferably between 30 minutes and 60 minutes.

16. Method (900) according to any one of claims 12 to 15, wherein the third material comprises an average mass content of first element strictly greater than the average mass content of first element in the glass substrate (10).