Glass-ceramic article and method for obtaining same

Abstract

The invention in question relates specifically to a glass-ceramic object intended for use with at least one light source and / or at least one heating element, and which includes at least one substrate, such as a plate made of glass-ceramic, which is at least partially equipped, or specifically coated, with at least one nano-wrinkle layer. The invention in question also relates to a process for obtaining the goods in question.

Description

[0001] The present invention relates to the field of glass-ceramics. More specifically, it relates to a glass-ceramic article, or product, intended in particular to cover or house heating elements, such as a cooktop. A glass-ceramic article, or article made of glass-ceramic, is understood to mean an article based on a substrate of glass-ceramic material, such as a glass-ceramic cooktop. This substrate may optionally be equipped with accessories or additional elements (decorative or functional) required for its end use. The article may refer to the substrate alone or to the substrate equipped with additional features (for example, a cooktop with its control panel, heating elements, etc.). The present invention also relates to a method for producing this article.

[0002] Several common ceramic glass products exist, particularly ceramic glass cooktops, which are very popular with homeowners, appliance manufacturers, and users. This success is largely due to the attractive appearance of these cooktops and their ease of cleaning.

[0003] A glass-ceramic is originally a type of glass, called precursor glass, mother glass, or green glass, whose specific chemical composition allows for controlled crystallization through appropriate heat treatments known as ceramization. This specific, partially crystalline structure gives the glass-ceramic its unique properties.

[0004] There are currently different types of glass-ceramic hobs, each variant being the result of significant studies and numerous tests, given that it is very delicate to make modifications to these hobs and / or to their manufacturing process without risking an adverse effect on the desired properties: in particular, in order to be used as a cooking hob, a glass-ceramic hob must generally have a transmission in the wavelengths of the visible range that is both low enough to mask at least part of the underlying heating elements at rest and high enough so that, depending on the case (radiant heating, induction heating, etc.), the user can visually detect the heating elements in operation for safety purposes; it must also have a high transmission in the wavelengths of the infrared range in the case of hobs with radiant elements.Ceramic glass cooktops must also exhibit sufficient mechanical resistance as required for their intended use. In particular, to be used as a cooktop in household appliances, a ceramic glass cooktop must demonstrate good resistance (as defined, for example, according to standard EN 60335-2-6) to pressure, impacts (from supports and dropped utensils, etc.), and other factors.

[0005] The most common ceramic glass cooktops are dark in color, especially black or brown or brownish-orange, but there are also lighter-looking cooktops (especially white, for example with a blur of at least 50% as described in patent FR2766816), or even transparent cooktops generally with opacifying coatings or filters for special color effects.

[0006] Among the coatings (functional and / or decorative) known for ceramic glass cooktops, enamels, made from glass frit and pigments, are traditionally found. Enamels have the advantage of being able to be deposited onto the precursor glass (or mother glass or green glass) before ceramicization and to be fired during the ceramicization process. They can also withstand high temperatures, thus allowing the use of different heating methods for the cooktop. However, they can locally reduce the mechanical resistance of ceramic glass cooktops and can flake, especially with thick deposits or multiple coats. Furthermore, some colors are not achievable or are difficult to obtain (particularly in a single coat), and the firing of enamels can also cause the appearance of unwanted tints (for example, brown or gray for black enamels).

[0007] It is also known to use certain high-temperature resistant paints, particularly silicone-based ones. These paints are applied to the substrates after ceramicization, although their use remains more limited than that of enamels due to their lower resistance, especially to heat and abrasion. The publications of patent applications US 2015 / 174625 A1, US 2001 / 008715 A1, and WO 99 / 08867 A1 describe a glass-ceramic article comprising a glass-ceramic plate coated with a nano-pleated layer.

[0008] A constant concern in the field of glass-ceramics, whether coated or not, is to offer a product that is easy to maintain and retains its appearance and properties over time. Adding a coating often makes maintenance more complex because the layers can be damaged during cleaning or alter the optical or mechanical properties of the glass-ceramic.

[0009] The present invention sought to provide glass-ceramic products, in particular new glass-ceramic hobs intended for use with one or more heating elements such as cooktops, which are increasingly functional and practical, while respecting the constraints, particularly thermal and mechanical, specific to the uses of said products, in particular sought to obtain durable and easy-to-maintain glass-ceramic products, ensuring that a simple and preferably flexible solution is offered, allowing where appropriate the presence of decorations or additional functions according to needs.

[0010] This goal is achieved through the process developed according to the invention, as well as through the resulting glass-ceramic product thus developed.

[0011] The present invention therefore relates to a new glass-ceramic article (or product), comprising (or formed of) at least one substrate (or support), such as a plate, made of glass-ceramic (material), said substrate being at least partly provided, in particular coated (on the surface, on at least part of a face) with at least one nano-pleated layer having pleats of amplitude less than 5 µm, and said nano-pleated layer having a pitch and an amplitude such that the ratio between the pitch and the amplitude is between 4 and 20, preferably between 5 and 15, in particular between 8 and 14.

[0012] The present invention also relates to a method of manufacturing such a glass-ceramic article (comprising at least one glass-ceramic substrate), from a glass substrate (the mother glass substrate, to form the glass-ceramic substrate by ceramization) in which at least a thin layer, the thickness of which does not exceed 20 µm, of a material chosen from the group of nitrides and / or oxides and / or carbides and / or alloys of one or more of the following elements: silicon, aluminum, titanium, zirconia, tin and zinc is applied to at least a part of said glass substrate (mother glass substrate), before ceramization, then ceramization of the glass substrate (mother glass substrate) thus coated, this ceramization then making it possible to obtain a glass-ceramic substrate at least partly coated with at least one nano-pleated layer as previously described.

[0013] By nano-pleated, we mean having folds - or undulations or curved deformations (or changing direction without forming angles / sharp angles) with an alternation of troughs and bumps - on the nanometric scale, that is to say folds of amplitude (or difference in altitude between the highest point - crest of the bump - and the lowest point - at the bottom of the trough - of each fold) less than 5 µm, more precisely (strictly) less than 2 µm, and in particular less than or equal to 1 µm, preferably (strictly) less than 1 µm, the amplitude of the folds (or of each fold) being advantageously on the order of a few nanometers to hundreds of nanometers, as specified later, the average amplitude (arithmetic mean) being generally on the order of hundreds of nanometers.

[0014] The present invention has shown that the deposition of a layer, in particular a thin film of the type whose thickness does not exceed 20 µm, and in particular in the present case less than a few microns, in particular less than 2 µm, of a material chosen from the group previously mentioned (a so-called "hard" material, compared to the glass substrate during ceramization, which sees its viscosity decrease and thus behaves like a flexible substrate compared to the more rigid layer of said material), on the parent glass substrate before ceramization, leads, after the ceramization heat treatment (occurring at high temperatures generally exceeding 900°C), to the wrinkling of the layer on the surface, also causing wrinkling of the substrate on the surface, at the nanometric scale, the surface changing its appearance visually (the coated surface becoming comparatively more matte compared to the uncoated surface or the surface recoated after ceramization,and exhibiting, in particular, a satin metallic appearance in reflection (the satin appearance being intermediate between matte and glossy) and presenting unexpected new technical advantages, such as greater ease of cleaning.

[0015] As described later, it is possible to use a stack of layers or other layers on or under the aforementioned layer, the entire coating then being advantageously nano-pleated. The product according to the invention obtained after ceramicization exhibits good adhesion of the nano-pleated layer or coating to the glass-ceramic substrate (without requiring prior treatment of the substrate and / or the use of an adhesion promoter, a bonding layer, or a primer) or to any adjacent layer that may be present on the substrate. In particular, this layer / coating shows no delamination after thermal shock (for example, at around 600°C) and is resistant to high temperatures. The layer / coating also exhibits good scratch resistance and does not mechanically weaken the glass-ceramic substrate (unlike, for example, an enamel).

[0016] The invention has thus enabled the development of a glass-ceramic product with a nano-pleated surface in the desired areas (for example, on the whole of a face or on only a few areas, for example areas more exposed to handling or soiling, such as control or display areas or heating areas, etc.), this product being able to be obtained by the process defined above and having various advantages, such as allowing less food to stick to the nano-pleated area(s) or surface(s), as well as offering greater ease of cleaning as indicated above, while the product retains a hardness and mechanical resistance such as are required for various uses (in particular for its use as a cooktop).Furthermore, the nano-pleated layer or coating does not affect the light transmission of the glass-ceramic in the area(s) concerned, while allowing light diffusion that prevents glare for the user and provides an unusual satin aesthetic appearance. This nano-pleating also unexpectedly makes it possible to obtain different types of reflected colors without the need for the addition of dyes or pigments (unlike other types of coatings) or filters, by manipulating the thickness and composition of the nano-pleated layer as detailed later.

[0017] The solution according to the present invention thus makes it possible to obtain, simply and economically, without complex operations (the layer can be deposited by low-pressure deposition techniques such as sputtering, as described later), in a durable and highly flexible manner, functional and aesthetic areas in any desired area of ​​the product, even when these areas are intended to be subjected to high temperatures. The article according to the invention exhibits, in particular, good thermal resistance compatible with the use of various types of heating systems, and does not present maintenance, scratching, or abrasion problems as previously mentioned. The product according to the invention, in particular, does not undergo thermal degradation at temperatures of 400°C or higher, which can be reached, for example, in applications such as use as cooktops.

[0018] The article according to the invention comprises, as previously stated, a substrate at least partially (i.e., in or on at least one area of ​​said substrate, on at least one face, or even several faces) provided (or furnished), in particular coated, with at least one nano-pleated layer – or a coating in the form of at least one layer. This texturing, which is referred to in this case as nano-pleating, is located on the surface of the substrate in the desired areas and provides the aforementioned advantages, and is observed on the substrate itself (on its surface layer) at the same time as on the coating that, where applicable, generated this nano-pleating.This texturing alternates between hollows and bumps in the manner of pleating, with a particular amplitude and periodicity, this pleating being generally (and preferably to obtain the desired effects) multidirectional, the folds formed then extending in a multitude of directions parallel to the surface of the substrate and forming an isotropic texturing or structuring, as illustrated later in the . figures 2a, 2b et 2c . This texturing, which is reflected on the surface layer of the glass-ceramic substrate, replaces any initial micro-roughness on the surface of the parent glass, said texturing thus constituting the only roughness of amplitude less than 5 µm in the zone (or zones) of the substrate equipped with said nano-pleated layer (other possible zones not equipped with this texturing may, where applicable, present other texturings or superimposed texturings).

[0019] The profile or morphological appearance of this texturing or nano-pleating generally resembles a quasi-periodic curve. This profile can vary within certain limits defined below, depending, where applicable, on the thickness of the coating layer, its nature, and the temperatures, processing times, or stresses applied during the manufacturing process used. For example, as mentioned previously, the process defined according to the invention provides a contraction that forms a normally isotropic texturing, but it is also possible to control the orientation of the pleats by applying anisotropic deformation or stresses to the substrate when it is sufficiently soft during the ceramicization or cooling phase, for example, by applying unidirectional tension simultaneously with cooling.The resulting nano-pleating can thus be along a single direction or along a principal direction (unidirectional nano-pleating), and / or may be anisotropic. The thickness and nature of the coating layer also impact the morphology of the pleating, in particular its pitch and amplitude, as well as the coating's coloration (a function, notably, of the L* reflection intensity of the coated area).

[0020] The nano-pleating according to the invention takes the form of folds, undulations, sinuosity, or wrinkles, particularly with substantially rounded apexes, (pseudo)periodic, more or less sinuous, and generally multi-oriented, as illustrated later in the figures 2a, 2b et 2c , with a width of bumps and hollows and an amplitude that are substantially constant.

[0021] The nano-pleated layer, or the folds of the nano-pleated layer or coating, advantageously exhibits a quasi-periodic pitch or period (average distance – arithmetic mean – between two consecutive peaks – or highest points – of bumps, or between two consecutive lowest points of troughs) between 10 nm and 40,000 nm, preferably between 100 nm and 10,000 nm, in particular between 500 and 8,500 nm, especially greater than 500 nm and less than or equal to 8,000 nm, or even less than 6,000 nm, or even less than 5,000 nm, and an amplitude of less than 5 µm, more precisely less than 2 µm, especially less than or equal to 1 µm, preferably less than 1 µm, in particular between 4 nm and 900 nm, preferably between 50 nm and 850 nm.The measurement and analysis of the pitch and folds is done for example by atomic force microscopy (AFM) or optical profilometry (for example the stylus profilometer marketed by the Bruker company under the reference Dektak), in particular on an analysis surface of 80 µm by 80 µm, for example with 1024 measurement points.

[0022] The ratio between the pitch and the amplitude (that is, the ratio of pitch to amplitude, or pitch relative to amplitude, expressed in nanometers) is between 4 and 20, preferably between 5 and 15, in particular between 8 and 14, especially in the order of 10 to 12.

[0023] Advantageously, the nano-pleated layer is a coating layer, meaning that the substrate is coated (on its surface in the relevant area) with said layer, as opposed to the case (discussed later) where the nano-pleated layer is the surface layer of the substrate (in which case the substrate is said to be "equipped" with said layer and not "coated"). In particular, it is the layer or a layer of the coating, deposited before ceramicization, which caused the wrinkling during ceramicization. This layer or coating may subsequently be covered by one or more other layers, so as, if necessary, to preserve the nano-pleated profile for the final coating. This nano-pleated layer is advantageously, as already seen in the process, made of a material selected from the group of nitrides and / or oxides and / or carbides and / or alloys of one or more of the following elements: silicon, aluminum, titanium, zirconia, tin, and zinc.Preferably, the layer material is chosen from the group of nitrides and / or oxides of one or more of the following elements: silicon, aluminum, titanium, zirconia, tin and zinc, in particular Si3N4, SiO2, TiO2, ZnO, SnZnO or SnO2, and particularly preferably, this material is silicon nitride (Si3N4) or silicon oxide (SiO2), more particularly silicon nitride.

[0024] The nano-pleated layer coating the substrate is most simply and generally in the form of a single layer (monolayer) of a material chosen from the previous materials, but it is also possible to have a nano-pleated layer formed from a stack of (sub-)layers (the set of sub-layers forming the layer and being nano-pleated) each chosen from the previous materials, or that the aforementioned nano-pleated layer according to the invention is itself part of a stack of layers (possibly including other layers of different materials than mentioned above) the whole then forming a final coating, itself advantageously nano-pleated.

[0025] The thickness of the nano-pleated coating, whether formed from the aforementioned layer (in the case formed from a stack of sub-layers) or from several layers, is generally between 20 nm and 2000 nm, preferably greater than or equal to 50 nm and less than or equal to 300 nm, in particular less than or equal to 200 nm, each layer in a material chosen from the previous materials being a thin-film type layer with a thickness of in particular of 20 to 200 nm.

[0026] Preferably, the ratio between the thickness of the nano-pleated layer deposited before ceramization and which caused the pleating during ceramization and the amplitude (of the pleats) of said nano-pleated layer (i.e. the thickness-to-amplitude ratio, expressed in nanometers) is between 0.15 and 0.30, preferably is in the order of 0.20 to 0.28, in particular 0.21 to 0.27.

[0027] The substrate according to the invention can also be coated with other non-nano-pleated layers according to the invention, deposited for example after ceramicization, with a functional and / or decorative effect and deposited in particular in areas other than the nano-pleated areas, such as usual enamel-based patterns or a layer of paint on a part of the substrate other than the nano-pleated part(s).

[0028] It is also possible that the coating layer used for nano-pleating according to the process of the invention may subsequently be removed, for example by chemical attack or laser ablation, leaving the surface layer of the glass-ceramic substrate itself as the nano-pleated layer, this solution also being advantageous in terms of cleaning.

[0029] The pleating of the substrate's surface layer conforms to that of the nano-pleated layer or coating used for nano-pleating. The pleating does not break the (very good) adhesion between the glass-ceramic and the nano-pleated coating layer or the layer used for nano-pleating, and there is no blistering in the resulting nano-pleated layer or coating.

[0030] As previously stated, nano-pleating is achieved particularly and advantageously by proceeding as described in the process according to the invention. At least one layer of a material selected from those mentioned above is applied to at least a portion of the glass substrate that will be ceramized into a glass-ceramic substrate, and then the coated glass substrate is ceramized.

[0031] As a reminder, the manufacturing process for glass-ceramic cooktops generally proceeds as follows: in a melting furnace, the glass of the chosen composition is melted to form the glass-ceramic. The molten glass is then laminated into a standard ribbon or sheet by passing it between laminating rollers, and the glass ribbon is cut to the desired dimensions. The cut sheets are then ceramicized using a well-established process. Ceramicization involves firing the sheets according to the chosen thermal profile to transform the glass into the polycrystalline material called "glass-ceramic," which has a coefficient of thermal expansion of zero or near-zero and can withstand thermal shock up to 700°C.Ceramization generally includes a step of progressive temperature increase up to the nucleation range, usually located near the glass transformation range, a step of crossing the nucleation range (e.g. between 650 and 830°C) over several minutes (e.g. between 5 and 60 minutes), a further temperature increase to allow crystal growth (ceramization in a range from 850 to 1000°C), with maintenance of the ceramization plateau temperature for several minutes (e.g. from 5 to 30 minutes) and then rapid cooling to room temperature.

[0032] The application or deposition, prior to ceramization, of the layer (or where applicable each layer) of a material chosen from the aforementioned materials on the parent glass can be carried out by any appropriate and rapid technique allowing in particular to make flat or uniform layers of this type of layer, in particular by deposition process under reduced pressure such as cathodic sputtering, in particular magnetron assisted, or chemical vapor deposition (CVD), where appropriate plasma field assisted (PECVD), the application being preferably carried out by cathodic sputtering, in particular magnetron assisted.

[0033] The coated substrate is then subjected to a ceramicizing heat treatment (at temperatures reaching between 850 and 1000°C) for a period generally lasting several tens of minutes, as previously mentioned. During the high-temperature ceramicizing step, the glass substrate's viscosity decreases, the glass densifies (crystallization of the glass matrix), and it undergoes volumetric shrinkage or contraction (generally isotropic, if no stress is applied), specifically of approximately 1.5%.The contraction of the substrate, resulting from the temperature rise to a temperature above the glass transition temperature of the substrate glass and then the cooling of the substrate, and the difference between the thermal contraction of the substrate glass and the thermal contraction of the coating layer, causes the layer and surface of the glass to wrinkle or crease, the wrinkle not breaking the adhesion between the glass-ceramic and the thin film, the process not causing blister formation.

[0034] This process allows for simple, and potentially large-scale, nanometric pleating of the coated area. The surface of this area becomes satin-like, diffusive, and pleasant to the touch. The nano-pleating, where necessary, replaces any micro-roughness of the original glass surface.

[0035] Where appropriate, the process also includes a cutting operation (usually before ceramicization), for example by water jet, mechanical tracing with a wheel, etc. followed by a shaping operation (grinding, beveling,...).

[0036] The nano-pleated layer or nano-pleated coating can cover only part of the substrate, or an entire face, for example the top face in the position of use, which is particularly subject to cleaning, or possibly all or part of the bottom face of the substrate.

[0037] Preferably, the substrate (or the article according to the invention itself if it consists only of the substrate) is a plate, intended in particular to be used with, in particular to cover or receive, at least one light source and / or a heating element. This substrate (or respectively this plate) is generally of geometric shape, in particular rectangular, or even square, or even circular or oval, etc., and generally has an "upper" or "external" face (the face visible or facing the user) in the position of use, another "lower" or "internal" face (generally hidden, for example in a frame or furniture box) in the position of use, and an edge (or edge or thickness).The upper surface is generally flat and smooth but may also have at least one raised area and / or at least one recessed area and / or at least one opening and / or beveled edges (these features having been added during the substrate manufacturing process, for example by rolling, collapse, or pressing, etc., or having been added later), these variations in shape advantageously constituting continuous variations of the plate (without changes in materials or joints). The lower surface may also be flat and smooth or have raised bumps.

[0038] The thickness of the glass-ceramic substrate is generally at least 2 mm, in particular at least 2.5 mm, and is advantageously less than 15 mm, in particular is in the range of 3 to 15 mm, in particular in the range of 3 to 8 mm or in the range of 3 to 6 mm. The substrate is preferably a flat or nearly flat plate (in particular with a deflection of less than 0.1% of the plate diagonal, and preferably in the range of zero).

[0039] The substrate can be based on any glass-ceramic, this substrate advantageously having a CTE of zero or almost zero, in particular less (in absolute value) than 30.10 -7< K -1< between 20 and 700°C, notably less than 15.10 -7< K -1< , or even less than 5.10 -7< K -1< between 20 and 700°C.

[0040] Preferably, a dark-appearing substrate with low transmissivity and low diffusion is used, particularly one based on any glass-ceramic having an intrinsic light transmission ranging from 0.8% to 40%, especially from 0.8% to 5%, particularly from 0.8% to 2%, and an optical transmission (determined by a known method by calculating the ratio of transmitted intensity to incident intensity at a given wavelength) of at least 2.5% for a wavelength of 625 nm within the visible spectrum. "Intrinsically" means that the plate possesses such transmission in itself, without the presence of any coating. In particular, a black or brown-appearing substrate is used, which, in combination with light sources placed beneath it, allows for the display of illuminated areas or designs while masking any underlying elements.It can notably be based on a black glass-ceramic comprising β-quartz structure crystals within a residual glassy phase, the absolute value of its coefficient of expansion being advantageously less than or equal to 15.10 -7< K -1< , or even to 5.10 -7< K -1< , such as the glass-ceramic of the plates marketed under the name Kerablack+ by the company Eurokera. In particular, it may be an arsenic-refined glass-ceramic of composition as described in patent application EP0437228 or US5070045 or FR2657079, or a tin-refined glass-ceramic, having an arsenic oxide content of less than 0.2%, for example of composition as described in patent application WO 2012 / 156444, or refined with sulfide(s) as described in patent application WO2008053110.

[0041] Alternatively, a transparent substrate can be used, coated where appropriate with an opacifying coating (for example in paint) generally on its underside, such as a plate marketed under the name Keralite ®< by the company Eurokera.

[0042] The aforementioned substrate (preferably dark in appearance, or possibly opaque transparent), equipped with the nano-pleated layer or coating, has in particular a light transmission TL between 0% and 10%, a light reflection between 8% and 20%, and its diffusion rate is greater than 90%.

[0043] Optical measurements are made according to the EN 410 standard. In particular, the light transmission TL is measured according to the EN 410 standard using the illuminant D65, and is the total transmission (in particular integrated in the visible range and weighted by the sensitivity curve of the human eye), taking into account both direct transmission and any diffuse transmission, the measurement being made for example using a spectrophotometer equipped with an integrating sphere (in particular with the spectrophotometer marketed by the company Perkin Elmer under the reference Lambda 950), the light reflection is also measured using the spectrophotometer (such as the one marketed by the company Perkin Elmer under the reference Lambda 950) in total reflection mode.The light scattering rate, defined as the ratio of diffuse transmission to total transmission using illuminant D65, is also evaluated, for example, using the spectrophotometer equipped with an integrating sphere used for light transmission and reflection measurements.

[0044] As previously stated, the presence of other types of coatings than the aforementioned layer is not excluded on the substrate, including the presence of other functional layers (scratch-resistant layer, spill-resistant layer, opacifying layer, etc.) or additional decorations, particularly localized ones (for example, an enamel on the top surface to form simple patterns or logos).

[0045] The article according to the invention may further comprise, associated or combined with the substrate, one or more light sources and / or one or more heating elements (or heating elements, such as one or more radiant or halogen elements and / or one or more atmospheric gas burners and / or one or more induction heating means), generally placed on the underside of the substrate.

[0046] The light source(s) can be integrated into / coupled with one or more display structures (for example, with so-called "7-segment" LEDs), an electronic control panel with touch-sensitive buttons and a digital display, etc. The light sources are advantageously formed by LEDs, spaced more or less far apart, possibly combined with one or more optical guides.

[0047] The article may optionally include, in combination with the light sources, at least one waveguide intended to propagate light from one part of the article to another (in particular by total internal reflection or by metallic reflection), the source or sources cooperating with the guide or guides and emitting / being coupled for example by the edge or side edge of the associated guide or guides, and / or one or more filters under the substrate, generally between one or more sources and the substrate.

[0048] The article according to the invention may, in particular, be a cooktop or any glass-ceramic article featuring, for example, a display or at least one illuminated area of ​​a functional or decorative nature and / or heating elements, such as a glass-ceramic worktop or a kitchen island, or even a console-type piece of furniture (the substrate forming, for example, the upper part), etc. In its most common application, the article according to the invention is intended to serve as a cooktop, this cooktop generally being intended to be integrated into a hob or cooker also comprising heating elements, for example, radiant or halogen elements or induction heating elements. In another advantageous application, the article according to the invention is a worktop with various displays, and not necessarily with cooking zones.

[0049] The item may also be equipped with (or associated with) additional functional element(s) (frame, connector(s), cable(s), control element(s), etc.

[0050] The following figures, which are not exhaustive, illustrate the present invention: there figure 1a represents a schematic, not to scale, cross-section of a coated glass substrate or part of a coated parent glass substrate used to obtain the article according to the invention; the figure 1b represents the substrate or the portion of substrate obtained after ceramization of the substrate or the portion of substrate of the figure 1a ; There figure 2a shows an optical microscope view of the nano-pleated surface obtained in a first embodiment of the invention; The figure 2b shows an optical microscope view of the nano-pleated surface obtained in a second embodiment of the invention; The figure 2c shows an optical microscope view of the nano-pleated surface obtained in a third embodiment of the invention

[0051] There figure 1b illustrates an article, or part of an article according to the invention, this article comprising a glass-ceramic substrate 1, coated with a nano-pleated layer 2 of a material selected from the group of nitrides and / or oxides and / or carbides and / or alloys of one or more of the following elements: silicon, aluminum, titanium, zirconia, tin and zinc, the nano-pleated layer, formed of an alternation of troughs 3 and bumps 4, having an amplitude a of less than 5 µm, more precisely less than 2 µm, in particular less than or equal to 1 µm, preferably less than 1 µm, in particular between 4 nm and 900 nm, and preferably between 50 and 850 nm, a pitch p between 10 nm and 40,000 nm, preferably between 100 and 10,000 nm, in particular between 500 and 8500 nm, and a thickness e (uniform over the entire surface of the layer) of the order of 20 nm to 200 nm.Nano-pleating is reproduced in the thickness of the coating layer as well as over a certain depth, corresponding to the amplitude of the pleating, of the glass-ceramic substrate, the face 1a of the substrate bearing the coating and the coating layer 2 being intimately bonded to each other and thus constituting a unitary whole with an identical profile.

[0052] This substrate is obtained by ceramization of a mother glass substrate 1' coated in the chosen area with a layer 2' ( figure 1a ), in the form of a flat layer deposited for example by cathodic sputtering, in particular magnetron-assisted sputtering, in a material chosen from the group of nitrides and / or oxides and / or carbides and / or alloys of one or more of the following elements: silicon, aluminium, titanium, zirconia, tin and zinc, this layer having the same thickness as the nano-pleated layer obtained after ceramization.

[0053] The nano-pleated layer (shown in simplified cross-section in figure 1b ) is generally isotropic and quasi-periodic. An optical microscope view of the nano-pleated surface 2a, 2b, 2c obtained is shown in three different examples of products made according to the invention by varying the thickness of the coating layer, the thickness being 50 nm in the case of the figure 2a , 100 nm in the case of the figure 2b and 200 nm in the case of the figure 2c , the deposited layer being a silicon nitride layer and the glass-ceramic substrate being a translucent black glass-ceramic, marketed under the reference KeraBlack+ or KeraVision by the company Eurokera, this plate having a smooth upper face and a smooth lower face and a thickness of 4 mm.

[0054] The resulting nano-pleated surface is mostly in the form of elongated, more or less sinuous folds, each with a substantially constant width, multi-oriented (along several directions) and practically isotropic. The spacing between two folds (pseudo-period) is respectively 2000 nm for the 50 nm thick layer, 5000 nm for the 100 nm thick layer and 8000 nm for the 200 nm thick layer; the amplitude is respectively 185 nm for the 50 nm thick layer, 450 nm for the 100 nm thick layer and 800 nm for the 200 nm thick layer; the ratio between the pitch and the amplitude (pitch over amplitude) is respectively 10.81 for the 50 nm thick layer, 11.11 for the 100 nm thick layer and 10 for the 200 nm thick layer; and the ratio between the thickness and the amplitude (thickness over amplitude) is respectively 0.27 for the 50 nm thick layer, 0.22 for the 100 nm thick layer and 0.25 for the 200 nm thick layer.

[0055] The substrate and nano-pleated layers obtained showed no delamination after a thermal shock of 620°C and showed no degradation in appearance after 100 h at 580°C.

[0056] They also demonstrated increased ease in cleaning the carbonized tomato concentrate at 200°C for 20 minutes. Fewer than 5 passes with a standard yellow sponge (without a scouring surface) soaked in water were required to completely clean the surface of the substrate equipped with the nano-pleating.

[0057] It was also observed that the coating reduces scratch formation during cleaning. The light transmission obtained for the different substrates coated with the tested thicknesses (50, 100, and 200 nm in these examples) was around 1%, and the light reflection ranged from 8 to 20%, with the light scattering rate exceeding 90% in each case.

[0058] For comparison, the same tests were performed on the same ceramic cooktop but without the nano-pleated coating. In the test of cleaning tomato paste, charred at 200°C for 20 minutes, it took more than 30 passes with the same water-soaked sponge as previously mentioned to completely clean the surface. Furthermore, the surface showed more visible scratches. The cooktop also exhibited a light transmission of approximately 1%, a light reflection of less than 5%, and a light diffusion rate of less than 5%.

[0059] For comparison, the same tests were performed on the same ceramic glass cooktop, but this time coated with a 200 nm thick layer of silicon nitride deposited after ceramicization (and therefore not nano-pleated). In the test of cleaning the tomato paste, carbonized at 200°C for 20 minutes, more than 30 passes of the same water-soaked sponge as previously mentioned were required to completely clean the surface. Furthermore, the cooktop exhibited a light transmission of approximately 1%, a light reflection of approximately 20%, and a light diffusion rate of less than 5%.

[0060] The articles, in particular plates, according to the invention can in particular be used to advantage to produce a new range of cooking plates for cookers or hobs or a new range of work tables, consoles, credenzas, central islands, etc.

Claims

1. Glass-ceramic article, intended in particular for use with at least one light source and / or at least one heating element, said article comprising at least one substrate, such as a plate, made of glass-ceramic, said substrate being at least partly provided, in particular coated, with at least one nano-wrinkled layer having an amplitude of less than 5 µm, said nano-wrinkled layer having a pitch and amplitude such that the ratio between pitch and amplitude is between 4 and 20, preferably between 5 and 15, in particular between 8 and 14.

2. Glass-ceramic article according to Claim 1, characterized in that the nano-wrinkled layer has a pitch between 10 nm and 40 000 nm, preferably between 100 and 10 000 nm, in particular between 500 and 8500 nm.

3. Glass-ceramic article according to one of Claims 1 to 2, characterized in that the nano-wrinkled layer has an amplitude of less than 5 µm, more precisely less than 2 µm, in particular less than or equal to 1 µm, preferably less than 1 µm, in particular between 4 nm and 900 nm, and preferably between 50 and 850 nm.

4. Glass-ceramic article according to one of Claims 1 to 3, characterized in that the nano-wrinkled layer is isotropic.

5. Glass-ceramic article according to one of Claims 1 to 4, characterized in that the nano-wrinkled layer is a coating layer of a material selected from the group of nitrides and / or oxides and / or carbides and / or alloys of one or more of the following elements: silicon, aluminium, titanium, zirconia, tin and zinc.

6. Glass-ceramic article according to one of Claims 1 to 5, characterized in that the thickness of the nano-wrinkled coating is between 20 nm and 2000 nm, preferably greater than or equal to 50 nm and less than or equal to 300 nm, in particular less than or equal to 200 nm.

7. Glass-ceramic article according to one of Claims 1 to 6, characterized in that the nano-wrinkled layer is a layer deposited prior to the ceramisation of the glass substrate to form the glass-ceramic substrate, which layer has caused the wrinkling during the ceramisation of the glass substrate into the glass-ceramic substrate.

8. Glass-ceramic article according to Claim 7, characterized in that the ratio between the thickness of said nano-wrinkled layer and the amplitude of said layer is between 0.15 and 0.30, preferably is of the order of 0.20 to 0.28, in particular 0.21 to 0.27.

9. Glass-ceramic article according to one of Claims 1 to 8, characterized in that the nano-wrinkled layer is the surface layer of the glass-ceramic substrate itself.

10. Glass-ceramic article according to one of Claims 1 to 9, characterized in that said article or substrate is a cooking hob or a worktop.

11. Process for the manufacture of a glass-ceramic article according to one of Claims 1 to 10, wherein at least one thin layer, which the thickness does not exceed 20 µm, of a material selected from the group of nitrides and / or oxides and / or carbides and / or alloys of one or more of the following elements: silicon, aluminium, titanium, zirconia, tin and zinc is applied to at least part of a glass substrate, and then the glass substrate thus coated is ceramised.

12. Process according to Claim 11, characterized in that said layer is subsequently removed, for example by chemical etching or laser ablation.