Cooking element with ceramic porous underlayer

Abstract

The present invention relates to a cooking element (1) comprising a metal support (2) that comprises an inner face (21) suitable for receiving food and an outer face (25), wherein the inner face (21) is coated with a coating (5) that consists, successively from the support (2), of an underlayer (3) and a surface coating (4), characterised in that the underlayer (3) takes the form of a discontinuous layer, is formed from one or more materials selected from the group consisting of Al2O3-TiO2, Al2O3-SiO2, Al2O3-ZrO2, Al2O3 and mixtures thereof, and has open pores across all or some of the thickness of the underlayer, wherein the open pores account for 20% to 70% by volume of the volume of the underlayer (3), and wherein the open pores are filled with the surface coating (4) to between 40% and 100% by volume, and in that the surface coating (4) penetrates into the thickness of the underlayer (3) to a depth of at least 30% relative to the thickness of the underlayer (3).

Description

[0001] COOKING ELEMENT WITH POROUS CERAMIC UNDERLAYER

[0002] FIELD OF THE INVENTION

[0003] The invention applies in the field of cooking elements with a porous ceramic underlayer.

[0004] The present invention also relates to kitchenware and electrical cooking appliances comprising such a cooking element.

[0005] STATE OF THE ART

[0006] The present invention addresses the technical problem of improving the scratch and chip resistance of coatings on cookware and electrical cooking appliances.

[0007] To remedy this, numerous technical solutions have been proposed which consist of reinforcing the coating with hard fillers or by interposing hard inorganic or organic sub-layers.

[0008] In the case of primers reinforced with hard organic or inorganic fillers, significant improvements in abrasion resistance are indeed observed, but impacts to metal are also observed when cooking foods such as pork chops or when using metal spatulas.

[0009] In the case of hard inorganic bases such as those made from enamel or metal oxides such as alumina layers obtained by electrochemical treatment (anodization), abrasion resistance is further improved and the impact problem is limited without, however, being eliminated.

[0010] Organic polymer undercoats are also known. The polymers used are very often thermoplastics with high thermal resistance and a high melting point, such as polyaryletherketones, particularly oxy-1,4-phenylenephenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene or PEEK, or phenylenesulfides.

[0011] As with other undercoats, the adhesion of the coating to the organic undercoat is not optimal. The need remains for cookware with a coating that offers excellent scratch resistance.

[0012] The consumer will have a more durable cookware or electrical cooking appliance, with a coating that more effectively prevents direct contact of food with the substrate (gain in performance durability, for example non-stick performance, gain in safety in the case of contact with aluminum, aesthetic gain, etc.).

[0013] STATEMENT OF THE INVENTION

[0014] A first subject of the invention relates to a cooking element (1) comprising a metal support (2) which comprises an inner face (21) adapted to receive food and an outer face (25), said inner face (21) being coated with a coating (5) consisting successively, from the support (2), of a sub-layer (3) and a surface coating (4), characterized in that the sub-layer (3) is in the form of a discontinuous layer, is made of one or more materials chosen from the group consisting of AI2O3-TO2, AhO3-SiO2, AhO3-ZrO2, AI2O3 and mixtures thereof and has open pores over all or part of the thickness of the sub-layer representing from 20 to 70% by volume of the volume of said sub-layer (3), which open pores are filled at a rate of 40% to 100% by volume by the surface coating (4),and in that the surface coating (4) penetrates into the thickness of the underlayer (3) to a depth of at least 30% relative to the thickness of the underlayer (3).,

[0015] Another subject of the invention relates to a method for manufacturing a culinary article or an electrical cooking appliance, characterized in that it comprises the following steps: a) a step of providing a metal substrate in the form of a substantially flat metal substrate comprising two opposite faces or a support (2) of convex or hollow shape defining a concave inner face (21) adapted to receive food and a convex outer face (22);b) where appropriate, when a metal substrate in the form of a substantially flat metal substrate is provided during step (a), a step of shaping said substrate to give it the shape of a support (2) of convex or hollow shape defining a concave inner face (21) suitable for receiving food and a convex outer face (22), said step (b) being carried out either before step (a), or before step (d) of producing the underlayer (3), or after step (d) and before step (e) of producing the surface coating (4) or after step (e); c) optionally, a step of treating the inner face (21) of the support (2), to obtain a treated inner face (21) promoting the adhesion of an underlayer (3) to the support (2); d) a step of producing an adherent underlayer (3) on said inner face (21) of the support (2) by thermal projection of a powder or dispersion of a material chosen from;

[0016] AhCh-TiCh AhCh-SiCh AhO3-Zr02 AI2O3 and mixtures thereof, said material being a particulate material comprising particles having a Dv10 greater than or equal to 5 pm and a Dv90 less than or equal to 50 pm; said thermal spraying being a flame spraying carried out by means of a nozzle whose angle relative to the inner face (21) or the bottom (211) of the support (2) is less than or equal to 90°; so as to form on said inner face (24) of the support (2) a sub-layer (3) having an average thickness of 10 pm to 100 pm; e) a step of producing a surface coating (4) on said sub-layer (3) formed in step d).

[0017] The invention also relates to a culinary article (100) comprising a cooking element (1) according to the invention as well as an electric cooking appliance (200) comprising a cooking element (1) according to the invention and a heating source (210) configured to heat said cooking element (1).

[0018] DESCRIPTION OF FIGURES

[0019] [Fig. 1]: Photograph of the scratch resistance test of the coating (5) according to the invention of Example 1

[0020] [Fig. 2]: Photograph of the resistance test of the coating (5) of the Comparative Example

[0021] [Fig. 3]: SEM cross-sectional view of the cap (2) coated with the porous underlayer (3) and the sol-gel surface coating (4) according to the invention of Example 1

[0022] [Fig. 4]: SEM-EDX analysis of the cap (2) coated with the porous underlayer (3) and the sol-gel surface coating (4) according to the invention of Example 1

[0023] [Fig. 5]: SEM cross-sectional view of the cap (2) coated with the porous underlayer (3) and the sol-gel surface coating (4) according to the invention of Example 2 [Fig. 6]: SEM-EDX analysis of the cap (2) coated with the porous underlayer (3) and the sol-gel surface coating (4) according to the invention of Example 2

[0024] In Figures 3 to 6:

[0025] (2) represents the aluminum cap (2)

[0026] (3) represents the sub-layer (3)

[0027] (4a) represents the sol-gel primer of the surface coating (4)

[0028] (4b) represents the sol-gel topcoat of the surface coating (4).

[0029] DETAILED DESCRIPTION OF THE INVENTION

[0030] Definitions:

[0031] 'Layer having open porosity' means a layer having open pores, some of the open pores being interconnected and forming a network extending from one face of said layer to the other.

[0032] Thus the underlayer (3) has a volume of air voids also called open pores incorporated in the thickness of the underlayer in order to absorb the coating deposited on the underlayer. These air voids or open pores come from spaces left free in the material of the underlayer during its formation, forming a discontinuity of the material, leading to the formation of a discontinuous underlayer.

[0033] The air voids or open pores tend to be interconnected, and thus can form a network of through porosity, between the upper face of the undercoat in contact with the coating and the lower face of the undercoat in contact with the support or metal cap. This allows the coating to penetrate into the open pores of the undercoat thanks to this open porosity and possibly to pass through the undercoat.

[0034] According to the invention, the term “open porosity” designates the sum of the porosity induced by the presence of air voids or open pores.

[0035] The open porosity rate corresponds to the volume % of air voids or open pores relative to the volume of said layer.

[0036] The term "primer" or "base coat" means a layer applied directly to the undercoat (3) and not in contact with food. The term "finish coat" or "finish" means a continuous and transparent surface layer giving the coating its non-stick properties.

[0037] Preferably, the final top coat is intended to be in contact with food.

[0038] The term "decor" or "decorative layer" means one or more layers comprising a pigment composition. The decor may be in the form of one or more patterns, or one or more colors. A decor is clearly visible to the user with the naked eye and at a normal distance from the household item.

[0039] "Discontinuous" means a layer that is not uniform in thickness over the entire surface on which it is deposited. Coverage may be non-existent in some areas.

[0040] For the purposes of the present invention, the term sol-gel layer or sol-gel coating means a coating synthesized by sol-gel method from a solution based on precursors in liquid phase, which transforms into a solid by a series of chemical reactions (hydrolysis and condensation), at low temperature. The coating thus obtained can be either organo-mineral or entirely mineral.

[0041] For the purposes of the present invention, the term organo-mineral coating means a coating whose network is essentially inorganic, but which includes organic groups, in particular due to the precursors used and the baking temperature of the coating.

[0042] For the purposes of the present invention, the term “fully mineral coating” means a coating made of a completely inorganic material, free of any organic group. Such a coating can also be obtained by sol-gel method with a baking temperature of at least 400°C, or from precursors of the tetraethoxysilane (TEOS) or tetramethoxysilane (TMOS) type with a baking temperature which can be lower than 400°C.

[0043] The expression "culinary article" is understood to mean, within the meaning of the present invention, an object intended for cooking. To do this, it is intended to receive heat treatment.

[0044] By the expression "object intended to receive heat treatment", it is necessary to understand within the meaning of the present invention an object which will be heated by an external heating system such as pans, saucepans, sauté pans, woks, barbecue grills and which is capable of transmitting the heat energy provided by this external heating system to a material or food in contact with said object.

[0045] The expression "electric cooking appliance" is understood to mean, within the meaning of the present invention, a heating object having its own heating system, such as an electric crepe maker, an electric raclette appliance, an electric fondue appliance, an electric grill, an electric griddle, an electric cooker, a bread maker, or an electric pressure cooking appliance.

[0046] Measurement of the porosity of the underlayer (3), the filling rate of the open pores of the underlayer (3) by the surface coating (4) and measurement of the penetration of the surface coating (4) into the underlayer (3):

[0047] The open porosity of the sub-layer (3) can be determined as follows: determination by weighing of the mass deposited by thermal spraying of: o AhCh-TiCh o AhCh-SiCh o AhCh-ZrCh o AI2O3 o or their mixtures permascope measurement of the deposited thickness (average of 10 measurements). This non-destructive method is a method of measuring the thickness by eddy currents and / or magnetic currents. measurement of the diameter of the deposited layer calculation of the theoretical mass of the deposited layer if it had no porosity using the theoretical density of the deposited material calculation of the % of open porosity = (1 -(deposited mass / theoretical mass))*100.

[0048] 'Open porosity' as applied to the sub-layer (3) in the culinary element (1) means the porosity of the sub-layer (3) which is discontinuous and has cavities free of:

[0049] AhCh-TiCh

[0050] AhCh-SiCh

[0051] AhCh-ZrCh

[0052] AI2O3 and mixtures thereof, said cavities or open pores devoid of said materials forming a communicating network, the pores being interconnected up to the surface of the underlayer (3). The open pores of the underlayer (3) can fill and contain the materials of the surface coating (4) in the cooking element (1).

[0053] The porosity of the underlayer (3) in the cooking element (1) can be determined by grayscale analysis of cross-sectional SEM images of said article as detailed in the examples.

[0054] The filling rate of the open pores of the underlayer (3) as well as the penetration depth of the surface coating (4) into the underlayer (3) can be determined by cross-sectional SEM-EDX analysis of said article as detailed in the examples.

[0055] The inventors have developed a cooking element (1) meeting the expressed needs.

[0056] COOKING ELEMENT

[0057] A first subject of the invention relates to a cooking element (1) comprising a metal support (2) which comprises an inner face (21) adapted to receive food and an outer face (25), said inner face (21) being coated with a coating (5) consisting successively, from the support (2), of a sub-layer (3) and a surface coating (4), characterized in that the sub-layer (3) is in the form of a discontinuous layer, is made of one or more materials chosen from the group consisting of AI2O3-TO2, AhO3-SiO2, AhO3-ZrO2, AI2O3 and mixtures thereof and has open pores over all or part of the thickness of the sub-layer representing from 20 to 70% by volume of the volume of said sub-layer (3), which open pores are filled at a rate of 40% to 100% by volume by the surface coating (4),and in that the surface coating (4) penetrates into the thickness of the underlayer (3) to a depth of at least 30% relative to the thickness of the underlayer (3).,

[0058] Undercoat (3)

[0059] The underlayer (3) consists of one or more materials chosen from the group consisting of AhCh-TiCh, AhCh-SiCh, AhCh-ZrCh, AI2O3 and their mixtures.

[0060] Advantageously, the material is a mixed mixture of alumina AI2O3 and titanium oxide TiC>2 in which the mass percentage of titanium oxide is at least 10%. The mixed mixture of alumina AI2O3 and titanium oxide TiCh may contain from 10% to 90% by mass of titanium oxide and from 90% to 10% by mass of alumina. The mixed mixture of alumina and titanium oxide may contain from 20% to 60% of titanium oxide and from 80% to 40% by mass of alumina. Advantageously, the mixed mixture of alumina and titanium oxide contains from 30% to 50% of titanium oxide and from 70% to 50% by mass of alumina.

[0061] Advantageously, the mixed mixture of alumina and titanium oxide contains from 35 to 45% titanium oxide and from 65% to 35% by mass of alumina.

[0062] According to advantageous embodiments, the mixed mixture of alumina and titanium oxide contains 40% titanium oxide and 60% by mass of alumina.

[0063] Advantageously, the material is a mixed mixture of alumina AI2O3 and silica SiC>2 in which the mass percentage of silica is at least 10%.

[0064] The mixed mixture of alumina AI2O3 and silica TiCh may contain from 10% to 90% by mass of silica and from 90% to 10% by mass of alumina. The mixed mixture of alumina and silica may contain from 10% to 40% of silica and from 90% to 60% by mass of alumina. Advantageously, the mixed mixture of alumina and silica contains from 15% to 35% of silica and from 85% to 65% by mass of alumina.

[0065] Advantageously, the mixed mixture of alumina and silica contains from 20% to 30% silica and from 80% to 70% by mass of alumina.

[0066] According to advantageous embodiments, the mixed mixture of alumina and silica contains 25% silica and 75% by mass of alumina.

[0067] Advantageously, the material is a mixed mixture of alumina AI2O3 and zirconium oxide ZrC>2 in which the mass percentage of zirconium oxide is at least 10%.

[0068] The mixed mixture of alumina AI2O3 and zirconium oxide ZrC>2 may contain from 10% to 90% by mass of zirconium oxide and from 90% to 10% by mass of alumina. The mixed mixture of alumina and zirconium oxide may contain from 10% to 30% of zirconium oxide and from 90% to 70% by mass of alumina. Advantageously, the mixed mixture of alumina and zirconium oxide contains from 15% to 25% of zirconium oxide and from 85% to 75% by mass of alumina. According to advantageous embodiments, the mixed mixture of alumina and zirconium oxide contains 20% of zirconium oxide and 80% by mass of alumina.

[0069] Advantageously, the material is a mixed mixture of alumina AI2O3 and TiCh, a mixed mixture of alumina AI2O3 and SiC>2 or a mixed mixture of alumina AI2O3 and ZrC>2.

[0070] The material may be a mixture of two or more materials selected from the group consisting of AI2O3-TO2, AhCh-SiCh, AhCh-ZrCh and AI2O3. Thus, the material may be a ternary mixture of ALCh and two compounds selected from TiC>2, SiC>2 and ZrC>2. Advantageously, the material may be a ternary mixture of ALCh, TiC>2 and ZrC>2.

[0071] The underlayer (3) can be presented as a hard underlayer.

[0072] The underlayer (3) is porous and has open porosity so that the underlayer

[0073] (3) and the surface coating (4) are interpenetrated, i.e. the surface coating

[0074] (4) penetrates at least partially into the open pores of the sub-layer (3) and fills these pores.

[0075] The inventors have discovered that this penetration of the surface coating (4) into the open pores of the underlayer (3) or in other words, the interpenetration of the underlayer (3) and the surface coating (4), allows for excellent anchoring of said surface coating (4). Thus the surface coating (4) has very good adhesion to the metal support (2) and resists tearing.

[0076] The underlayer (3) has open pores over all or part of its thickness representing from 20 to 70% by volume of the volume of said underlayer (3). If the open pores represent more than 70% by volume, the underlayer (3) does not have sufficient mechanical strength to reinforce the surface coating (4). If the pores represent less than 20% by volume, the underlayer (3) is not sufficiently porous so that the anchoring of the surface coating (4) in the underlayer (3) is not optimal.

[0077] Open pores can represent 20% to 40%, 25% to 35%, 20% to 50%, 30% to 60%, 40% to 70%, 50% to 70% or 60% to 70% of the volume of the sub-layer (3).

[0078] According to one embodiment, the underlayer (3) has open pores over its entire thickness. In this case, the air voids or open pores form a network of porosity extending through it, between the upper face of the underlayer in contact with the surface coating (4) and the lower face of the underlayer in contact with the support. Thus, the surface coating can, if necessary, penetrate into the thickness of the underlayer (3) as far as the support, i.e. to a depth of 100%. According to another embodiment, the underlayer (3) has open pores over only part of its thickness. The underlayer (3) can thus have open pores forming a network of porosity from the upper face of the underlayer in contact with the surface coating (4) without this network extending through it.

[0079] The surface coating (4) penetrates into the thickness of the undercoat (3) to a depth of at least 30% relative to the thickness of the undercoat (3).

[0080] A high penetration depth of the surface coating (4) into the thickness of the underlay (3) ensures strong anchoring of the surface coating (4).

[0081] Thus, advantageously, the penetration depth of the surface coating (4) into the thickness of the underlayer (3) is at least 50%, preferably at least 70%, particularly preferably at least 85% relative to the thickness of the underlayer (3).

[0082] The open pores of the underlayer (3) are filled to a level of 40% to 100% by volume with the surface coating (4). This corresponds, for example, to a penetration of the surface coating (4) into the thickness of the underlayer (3), having through-porosity, to a depth of at least 50% relative to the thickness of the underlayer (3) with a pore filling rate in the penetration thickness of 80% to 100%.

[0083] Advantageously, the filling rate of the open pores of the underlayer (3) by the surface coating (4) ranges from 60% to 100%, preferably from 80% to 100% by volume of the total volume of said open pores.

[0084] Advantageously, the average thickness of the underlayer (3) ranges from 10 pm to 100 pm, preferably from 20 pm to 50 pm.

[0085] Advantageously, the sub-layer (3) is in the form of a stack of particles of AI2O3-TO2, AhCh-SiCh, AhCh-ZrCh, AI2O3 or their mixture, said particles having a Dv10 greater than or equal to 5 pm and a Dv90 less than or equal to 50 pm, preferably a Dv10 greater than or equal to 5 pm and a Dv90 less than or equal to 30 pm. The volume average diameter Dv10 corresponds to the io ème percentile of the particle size volume distribution, i.e. 10% of the volume consists of particles smaller than D10 and 90% larger than D10.

[0086] The particle size distribution is measured by the dry laser diffraction method.

[0087] The stacking of particles forms a disordered assembly of particles creating interparticle cavities connected to each other and constituting a network at the origin of the open porosity of the sub-layer (3).

[0088] Support / Cap (2) metal

[0089] Advantageously, the metal support (2) is formed from a metal substrate made of aluminum, stainless steel, cast iron or aluminum, iron, titanium or copper.

[0090] For the purposes of the present invention, aluminum means a metal consisting of 100% aluminum or an aluminum alloy.

[0091] Preferably, the support (2) is a single-layer support made of aluminum or aluminum alloy, cast aluminum, stainless steel, cast steel or copper, or a multi-layer support comprising from the outside to the inside the following layers: ferritic stainless steel / aluminum / austenitic stainless steel or stainless steel / aluminum / copper / aluminum / austenitic stainless steel, or a cap of cast aluminum, aluminum or aluminum alloys lined with an outer base of stainless steel.

[0092] Advantageously, the support (2) is an aluminum, stainless steel or multi-layer metal substrate. The metal substrate (2) may be a two-layer or three-layer substrate, these multi-layers being able to be obtained for example by co-lamination, by hot diffusion under load (solid state bonding) or by hot or cold impact bonding.

[0093] Preferably, the support (2) comprises alternating layers of metal and / or metal alloy. According to one embodiment, the support (2) is a substrate made of aluminum alloy, stainless steel or a multilayer metal substrate whose face (2a) is made of aluminum alloy or stainless steel.

[0094] Preferably, the support (2) is an aluminum substrate.

[0095] Advantageously, the thickness of the support (2) is between 0.5 mm and 10 mm.

[0096] The face (2a) of the support (2) may first undergo a surface treatment to improve the adhesion of the coating (5) to said substrate.

[0097] According to one variant, the support (2) is a convex or hollow metal cap.

[0098] According to one embodiment, the surface of the face (2a) of the metal substrate (2) has undergone a surface treatment, said surface treatment being a chemical attack, brushing, hydration, sandblasting, shot blasting, a physicochemical treatment of the plasma or corona or laser type, a chemical activation or a combination of these different techniques.

[0099] Advantageously, the average arithmetic roughness Ra of the surface of the face (2a) of the metal substrate (2) is greater than or equal to 1 pm.

[0100] The arithmetic mean roughness Ra is measured using a roughness meter according to ISO 4287. Ra represents the arithmetic mean of the deviations from the mean. The surface topography can be studied in particular with a profilometer with a probe equipped with a fine stylus equipped with a diamond tip, or with an optical metrology device such as Altisurf®, in which a chromatic confocal sensor allows a contactless measurement. The study of this surface topography makes it possible to define the arithmetic mean roughness Ra.

[0101] Surface coating (4)

[0102] The surface coating (4) may be a coating of any kind conferring the desired properties on the coating (5).

[0103] According to embodiments, the surface coating (4) comprises at least one layer comprising at least one fluorocarbon resin, or at least one layer comprising at least one silicone resin, or at least one sol-gel layer, or at least one layer comprising one or more polyarylether ketone(s) (PAEK).

[0104] According to embodiments, the surface coating (4) comprises several layers. The surface coating (4) may then comprise at least one primer layer (4a) and a topcoat layer (4b) and may comprise at least one layer comprising at least one fluorocarbon resin, or at least one layer comprising at least one silicone resin, or at least one sol-gel layer, or at least one layer comprising one or more polyarylether ketone(s) (PAEK).

[0105] The surface coating (4) may comprise one or more decorative layers between the primer layer (4a) and the finishing layer (4b).

[0106] The primer layer (4a) of the surface coating (4) penetrates into the open pores of the undercoat (3) and allows, after deposition of the finishing layer (4b), to obtain a coating (5) strongly adhering to the metal support (2).

[0107] According to a variant, the top layer (4b) of the surface coating (4) also penetrates into the open pores of the underlayer (3).

[0108] According to other embodiments, the surface coating (4) is a single-layer coating.

[0109] In this case, the surface coating (4) consists of a single layer (4) comprising at least one fluorocarbon resin, or at least one layer comprising at least one silicone resin, or at least one sol-gel layer, or at least one layer comprising one or more polyarylether ketone(s) (PAEK).

[0110] The composition of the coating (4) may be identical to that of the finishing layer (4b) of the multi-layer coating described above.

[0111] According to other embodiments, the coating (4) is devoid of primer and may consist of one or more layers of decorations and an outer layer comprising at least one fluorocarbon resin, or at least one layer comprising at least one silicone resin, or at least one sol-gel layer, or at least one layer comprising one or more polyarylether ketone(s) (PAEK). The decoration(s) are positioned between the underlayer (3) and the outer layer. The composition of the outer layer may be identical to that of the finishing layer (4b) of the multilayer coating described above.

[0112] According to one variant, the surface coating (4) gives non-stick properties to the coating (5).

[0113] Surface coating (4) sol-gel

[0114] The surface coating (4) comprises at least one sol-gel layer.

[0115] Advantageously, the surface coating (4) comprises at least one sol-gel finishing layer.

[0116] The surface coating (4) may comprise at least one sol-gel primer layer (4a) and one sol-gel finishing layer (4b).

[0117] The sol-gel coating can be a sol-gel, organo-mineral or entirely mineral coating. These coatings synthesized by sol-gel method from precursors of the metal polyalkoxylate type, preferably have a hybrid network, generally of silica with grafted alkyl groups. A sol-gel (SG) composition comprises at least one colloidal metal oxide and at least one precursor of the metal alkoxide type.

[0118] The metal oxide is preferably a colloidal metal oxide selected from colloidal silica and / or colloidal alumina.

[0119] Preferably, a metal alkoxide chosen from the group consisting of:

[0120] - precursors corresponding to the general formula Mi(ORi) n ,

[0121] - precursors corresponding to the general formula M2(OR2) <n-i) 2', et

[0122] - precursors corresponding to the general formula M3(OR3) <n-2) 3'2, avec :

[0123] Ri, R2, R3 or R3' denoting an alkyl group,

[0124] R2' denoting an alkyl or phenyl group, n being an integer corresponding to the maximum valence of the metals Mi, M2 or M3, Mi M2 or M3 denoting a metal chosen from Si, Zr, Ti, Sn, Al, Ce, V, Nb, Hf, Mg or Ln.

[0125] Advantageously, the metal alkoxide of the SG solution is an alkoxysilane. As alkoxysilanes that can be used in the SG solution of the process of the invention, mention may in particular be made of methyltrimethoxysilane (MTMS), tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), dimethyldimethoxysilane, and mixtures thereof.

[0126] Preferably, the alkoxysilanes MTES and TEOS will be used, because they have the advantage of not containing methoxy groups. Indeed, the hydrolysis of methoxy leads to the formation of methanol in the sol-gel formulation, which, given its toxic classification, requires additional precautions during application. Conversely, the hydrolysis of ethoxy groups only generates ethanol, which has a more favorable classification and therefore less restrictive usage requirements for the sol-gel coating.

[0127] The formation of this SG coating consists of mixing an aqueous composition A comprising the colloidal metal oxide and a solution B comprising the metal alkoxide. The mixing is advantageously carried out in a ratio of 40 to 75% by weight of the aqueous composition relative to the weight of the sol-gel composition (A + B), so that the quantity of colloidal metal oxide represents 5 to 50% by weight of the sol-gel composition (A + B) in the dry state.

[0128] The aqueous composition A may further comprise a solvent, in particular a solvent comprising at least one alcohol.

[0129] The aqueous composition A may further comprise at least one silicone oil.

[0130] The aqueous composition A may further comprise a pigment.

[0131] The aqueous composition A may further comprise a mineral filler.

[0132] The aqueous composition A may also comprise fumed silica, the function of which is to regulate the viscosity of the sol-gel composition and / or the gloss of the dry coating.

[0133] The aqueous composition A typically comprises for a primer layer: i) 5 to 50% by weight relative to the total weight of the aqueous composition A of at least one colloidal metal oxide, ii) 0 to 20% by weight relative to the weight of the composition A of a solvent comprising at least one alcohol, iii) optionally 0.05 to 3% by weight relative to the total weight of said aqueous composition A of at least one silicone oil. iv) 5 to 30% of pigment v) 2 to 30% of mineral filler

[0134] The aqueous composition A typically comprises for a finishing layer: i) 5 to 50% by weight relative to the total weight of the aqueous composition A of at least one colloidal metal oxide, ii) 0 to 20% by weight relative to the weight of the composition A of a solvent comprising at least one alcohol, iii) optionally 0.05 to 3% by weight relative to the total weight of said aqueous composition A of at least one silicone oil. iv) 0.1 to 1% of metal flakes

[0135] Solution B may further comprise an acid in Bronsted or Lewis terms. Advantageously, the metal alkoxide precursor of solution B is mixed with an organic, mineral Lewis acid which represents 0.01 to 10% by weight of the total weight of solution B.

[0136] Particular examples of acids suitable for mixing with the metal alkoxide precursor are acetic acid, citric acid, ethyl acetoacetate, hydrochloric acid or formic acid.

[0137] Solution B may further comprise a solvent, in particular a solvent comprising at least one alcohol.

[0138] Solution B may further comprise at least one silicone oil.

[0139] Solution B may additionally include metallic flakes.

[0140] According to an advantageous embodiment of the process of the invention, solution B may comprise a mixture of one of the alkoxysilanes as defined above and an aluminum alcoholate.

[0141] Fluorinated surface coating (4)

[0142] The surface coating (4) comprises at least one layer comprising at least one fluorocarbon resin, alone or in a mixture with at least one thermostable bonding resin resistant to at least 200°C. Preferably, the fluorocarbon resin is chosen from polytetrafluoroethylene (PTFE), the copolymer of tetrafluoroethylene and perfluoropropylvinylether (PFA), the copolymer of tetrafluoroethylene and hexafluoropropylene (FEP) and their mixtures.

[0143] Preferably, the bonding resin is chosen from polyamide imides (PAI), polyether imides (PEI), polyamides (PA), polyethercetanes (PEK), polyetherethercetanes (PEEK), polyethersulfones (PES), polyphenylene sulfides (PPS), tannins and mixtures thereof. More preferably, the bonding resin is chosen from polyamide imides (PAI).

[0144] Preferably, the surface coating (4) comprises at least one finishing layer (4b) comprising at least one fluorocarbon resin.

[0145] The surface coating (4) may comprise at least one primer layer (4a) comprising at least one fluorocarbon resin and a topcoat layer (4b) comprising at least one fluorocarbon resin.

[0146] Surface coating (4) silicone

[0147] The surface coating (4) comprises at least one layer comprising at least one silicone resin.

[0148] In the text of the description, the expression "silicone resin" is used interchangeably to refer to the silicone before its crosslinking or after its crosslinking. In the text of the description, the expression "silicone" designates an organopolysiloxane material. Crosslinking is the step which makes it possible to transform the silicone into an insoluble material, for example by polyaddition, polycondensation or dehydrogenation. Crosslinking is carried out from precursors which are generally silicone oils or resins, which crosslink to obtain a three-dimensional network forming a material called silicone resin, in the description.

[0149] This crosslinking can be done by thermal activation, or chemical activation using a catalyst, such as platinum.

[0150] Silicone resins can be obtained from precursors, advantageously soluble in a solvent or in emulsion in water, such as oils or crosslinkable resins, in particular chosen from: a silicone hydride, a silicone oil resin comprising at least one vinyl group (-CF CFL), a silicone or silicone-polyester resin (copolymer) comprising at least one alkoxy group, for example methoxy or ethoxy, and / or a silicone or silicone-polyester resin (copolymer) comprising at least one alkoxy group, in particular ethoxy, or a hydroxy group and mixtures thereof. These precursors have the capacity to crosslink in order to obtain a silicone resin which is characterized by its insolubility and its substantially solid form.

[0151] Advantageously, these precursors are polymeric or oligomeric, either in the form of silicone oils with a variable degree of branching, or in the form of silicone resins with a variable degree of pre-crosslinking or copolymers of silicone resins such as silicone-polyester, silicone-alkyd, silicone-polyurethane, silicone-epoxy resins, or in the form of a mixture of silicone oils, silicone resins and copolymers of silicone resins. The silicon atoms may be substituted by alkyl (in particular methyl) or aryl (in particular phenyl) groups or mixtures thereof. The oils or resins preferably comprise one or more (2, 3 or more) hydroxy or alkoxy (in particular methoxy, ethoxy, butoxy) functional groups as substituents of silicon atoms.

[0152] Advantageously, the silicone resin(s), obtained after crosslinking their precursors, i.e. crosslinked, is / are chosen from the group consisting of methyl silicone and / or phenyl silicone and / or methyl-phenyl-silicone resins, methyl silicone-polyester resin (copolymers), phenyl silicone-polyester resin (copolymers), methyl-phenyl silicone-polyester resin (copolymers), silicone-alkyd resin (copolymers), modified silicone resin and their mixtures.

[0153] Advantageously, the silicone resin(s) is / are chosen from the group consisting of methyl silicone and / or phenyl silicone and / or methyl-phenyl-silicone resins, methyl silicone-polyester resin (copolymers), phenyl silicone-polyester resin (copolymers), methyl-phenyl silicone-polyester resin (copolymers), silicone-alkyd resin (copolymers), modified silicone resin and mixtures thereof.

[0154] Silicone resins can be obtained from precursors, notably chosen from: a silicone hydride, a silicone resin comprising at least one vinyl group (-CH=CH2), a silicone-polyester resin (copolymer) comprising at least one methoxy group, and / or a silicone-polyester resin (copolymer) comprising at least one ethoxy group, and mixtures thereof.

[0155] The silicone resin of the single layer (3) forms a network which can be made up of a combination of 4 simple organosiloxane units named M, D, T and Q depending on the degree of substitution by oxygen of the silicon atom, as described in the following table, where R is an organic substituent described below.

[0156] [Table 1]

[0157] The organopolysiloxane material or polymer is obtained by crosslinking from precursors which can be monomeric or polymeric, or intermediately which can be oligomeric. The organopolysiloxane polymer can also be obtained from a mixture of these different kinds of precursors. When the network contains a higher number of T and Q units, than D, the crosslinking density is higher. The distribution between the M, D, T and Q units depends on the chemical structure of the precursors, in particular on this M, D, T, Q distribution within the precursors.

[0158] The polymeric precursors are organopolysiloxanes. These macromolecules are formed from M, D, T, and / or Q units as described in the table, where R is independently an alkyl group, in particular methyl, or aryl group, in particular phenyl, different natures of R being able to be present on the same macromolecule.

[0159] Organopolysiloxanes can be either linear or slightly branched (majority of D groups), or branched or highly branched (majority of T and Q groups). Linear or lightly branched organopolysiloxanes are generally liquid, more or less viscous at room temperature, and are called silicone oils. Branched or highly branched (pre-crosslinked) organopolysiloxanes form a network at the level of the individual macromolecule and are called silicone resins. At room temperature, the resins are substantially in solid form, or in liquid form, provided in particular that they have a fairly low molecular weight, in the form of a solution in a solvent or in the form of an aqueous emulsion. They can be copolymerized with organic polymers or oligomers not containing silicon, chosen in particular from polyesters, acrylics, alkyds, polyurethanes, epoxy resins.

[0160] When the crosslinking is a hydrolysis-polycondensation: it is carried out thanks to the reactive hydroxy or alkoxy functions, in particular methoxy, ethoxy or butoxy, present on the organopolysiloxane.

[0161] When the crosslinking is a polyaddition (or hydrosilylation): it is carried out by reaction between the reactive vinyl functions (-Ch ChL) present on one of the organopolysiloxanes and the reactive silyl hydride functions (Si-H) present on the other organopolysiloxane mixed with the first.

[0162] All these reactive functions are present on each organopolysiloxane in number of at least one and can be present in number of 2, 3, or more ... as much as the molecular structure allows. Silicone oils containing at least one reactive function are called "reactive oils". The reactive functions can be found either at the end of the macromolecular chain (termination), or distributed over the chain.

[0163] Silicone-polyester resins in particular have silicone / polyester mass ratios of, for example, 90 / 10, 80 / 20, 70 / 30, 60 / 40, 50 / 50, 40 / 50, 30 / 70, 20 / 80, 10 / 90, advantageously between 80 / 20 and 50 / 50.

[0164] Linear PDMS silicone oils, pure or pre-emulsified in water, are characterized firstly by their molecular mass, which is a direct increasing function of the viscosity of the pure oil. They are then characterized by the presence or absence of reactive functions, for example hydroxyls on the silicon atoms (silanol), their number and their location on the molecular chain. For example, reactive oils with viscosities between 50 and 20,000 mPa.s, and in particular between 300 and 5,000 mPa.s, can be used, having at least one reactive function, preferably at least 2, which can be placed at the end of the chain.

[0165] Polymer precursors reacting by polyaddition may include, for example, polymethylhydrosiloxane, vinylmethylsiloxane, vinyl-terminated polydimethylsiloxane (PDMS), in particular linear, vinyl-terminated diphenylsiloxane-dimethylsiloxane copolymers, hydride-terminated polydimethylsiloxanes, hydride-terminated polyphenylmethylsiloxanes, cyclic vinylmethylsiloxane, vinyl-MQ resin, trimethylsilyl-terminated polymethylhydrosiloxane, trimethylsiloxane-terminated dimethylsiloxane copolymer, MQ resin hydride, and the like, as well as combinations thereof.Polymeric precursors reacting by hydrolysis-polycondensation, whether silicone resins or silicone oils, may include, for example, poly(methylsilsesquioxanes), poly(propylsilsesquioxanes), poly(phenylsilsesquioxanes), polydimethylsiloxane (PDMS), trimethylsilyl-terminated polydimethylsiloxane (PDMS), hydroxyl-terminated polydimethylsiloxane (PDMS), silanol-terminated polydimethylsiloxane (PDMS), silanol-terminated polyphenylsiloxane (PDMS), silanol-terminated diphenylsiloxane-dimethylsiloxane copolymer, poly(2-acetoxyethylsilsesquioxanes), organo-modified alkoxy-silanes and their oligomers, and all similar macromolecules and their mixtures.

[0166] The organopolysiloxane material or polymer may also be obtained by crosslinking a mixture of one or more monomeric precursors and one or more polymeric precursors as described above, as well as one or more oligomeric precursors which may be linear, branched or cyclic. These oligomeric precursors have a lower molecular weight than the polymeric precursors. Polymeric and / or oligomeric precursors comprising a number of reactive functions as described above greater than 2, advantageously much greater than 2, may be added to the mixture as a “co-binder” in order to promote a high crosslinking density of the organopolysiloxane polymer finally obtained.

[0167] Monomeric, oligomeric and / or polymeric precursors, in particular silicone resins, copolymerized or not with an organic polymer, act as a polymeric binder in order to obtain the solid organopolysiloxane polymer combined with the thermoplastics of each layer.

[0168] Silicone oil-type organopolysiloxane precursors can be considered additives if they are added in small amounts (typically between 0.1 and 5% dry) to the overall formulation of a layer, independently of other components for the formation of the solid organopolysiloxane polymer.

[0169] Crosslinking may require a catalyst:

[0170] - In the case of crosslinking organopolysiloxanes by hydrolysis-polycondensation, the formula may include a metal catalyst, such as, for example, metal complexes based on platinum, tin, zinc, zirconium and cerium, in particular platinum-cyclovinylmethyl-silxane complexes, tin ethylhexanoate, zinc ethylhexanoate, zirconium ethylhexanoate, cerium ethylhexanoate, and dibutyl tin laurate. - In the case of crosslinking organopolysiloxanes by hydrosylilation, the addition of a catalyst may be necessary: ​​this may be, for example, platinum or a suitable platinum-based catalyst such as the Karstedt catalyst or the Ashbys catalyst.

[0171] A crosslinking agent, for example carrying Si-H bonds, may be present.

[0172] Advantageously, the surface coating (4) comprises at least one finishing layer comprising at least one silicone resin.

[0173] According to embodiments, the finishing layer (4b) consists of one or more silicone resin(s) and optionally one or more thermoplastic polymer(s), and / or one or more filler(s), and / or one or more additive(s), and / or flakes.

[0174] Advantageously, the thermoplastic polymer(s) is / are chosen from the group consisting of polyethersulfone (PES), polyphenylene ether sulfone (PPSU), polyamideimide (PAI), polyimide (PI), poly(phenylene oxide) (PPO), poly(arylene sulfide) (PAS), polyetherimide (PEI), and polybenzymidazole (PBI), liquid crystal polymers (LCP), polyphenylene sulfide (PPS), polyarylether ketone (PAEK) including polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), polyether ketone ether ketone ketone (PEKEKK) and mixtures thereof.

[0175] Examples of heterocyclic thermoplastic polymers suitable according to the invention are polyetherimides (PEI), polyimides (PI), polyamideimides (PAI) and polybenzymidazole (PBI), or mixtures thereof.

[0176] The surface coating (4) may comprise at least one primer layer (4a) comprising at least one silicone resin and a finishing layer (4b) as described above comprising at least one silicone resin.

[0177] Surface coating (4) comprising one or more polyarylether ketone(s) (PAEK)

[0178] The surface coating (4) comprises at least one layer comprising at least one or more polyarylether ketone(s) (PAEK). Advantageously, the surface coating (4) comprises at least one finishing layer comprising at least one or more polyarylether ketone(s) (PAEK).

[0179] According to embodiments, the topcoat is comprised of one or more polyarylether ketone(s) (PAEK), one or more filler(s) and, optionally, one or more additive(s), one or more pigment(s) or glitter.

[0180] According to embodiments, the finishing layer consists of:

[0181] - a polymeric phase consisting of: o at least 50%, by weight of one or more polyarylether ketone(s) (PAEK), the remainder being chosen from the group consisting of one or more organopolysiloxane polymer(s), one or more aromatic thermoplastic polymer(s) other than PAEK, one or more heterocyclic thermoplastic polymers, and mixtures thereof, and optionally one or more fluorocarbon resin(s); or o or less 50%, by weight of one or more polymer(s) chosen from the group consisting of aromatic thermoplastic polymers other than PAEK, heterocyclic thermoplastic polymers, organopolysiloxane polymers and mixtures thereof, the remainder being chosen from one or more polyarylether ketone(s) (PAEK), and optionally one or more fluorocarbon resin(s);

[0182] - one or more charge(s);

[0183] - possibly one or more additive(s);

[0184] - possibly one or more pigment(s); and

[0185] - possibly glitter.

[0186] The surface coating (4) may comprise at least one primer layer (4a) and one topcoat (4b) as described above, the primer layer and the topcoat comprising at least one or more polyarylether ketone(s) (PAEK). Polymeric phase

[0187] PAEK

[0188] Advantageously, the polyaryletherketone(s) (PAEK) is (are) chosen from the group consisting of: polyetherketones (PEK), polyetheretherketone (PEEK), polyetherketoneketones (PEKK), polyetheretherketoneketones (PEEKK) and polyetherketoneetherketoneketones (PEKEKK), particularly preferably is (are) PEEK.

[0189] As aromatic thermoplastic polymer(s) other than PAEK, examples which are suitable according to the invention are poly(phenylene oxide) (PPO), poly(arylethersulfone) polymer (PAES), and in particular polyethersulfone (PES), polyphenylene ether sulfone (PPSll), polyphenylene sulfide (PPS), poly(arylene sulfide) (PAS), liquid crystal polymers and their mixtures.

[0190] Heterocyclic thermoplastic polymers

[0191] Examples of heterocyclic thermoplastic polymers suitable according to the invention are polyetherimide (PEI), polyimides (PI), polyamideimides (PAI) and polybenzymidazole (PBI), or mixtures thereof.

[0192] Polysiloxanes are as described above.

[0193] According to embodiments, the surface coating (4) comprises at least one primer layer (4a) comprising at least one silicone resin or at least one fluorocarbon polymer or a sol-gel primer layer, or a layer comprising at least one or more polyarylether ketone(s) (PAEK); and a finishing layer (4b) chosen from a layer comprising at least one silicone resin or at least one fluorocarbon polymer or a sol-gel layer, or a layer comprising at least one or more polyarylether ketone(s) (PAEK); the primer layer and the finishing layer being of different or identical nature.

[0194] MANUFACTURING PROCESS

[0195] A second subject of the invention relates to a method for manufacturing a culinary article or an electrical cooking appliance, characterized in that it comprises the following steps: a) a step of providing a metal substrate in the form of a substantially flat metal substrate comprising two opposite faces or a support (2) of convex or hollow shape defining a concave inner face (21) adapted to receive food and a convex outer face (22);b) where appropriate, when a metal substrate in the form of a substantially flat metal substrate is provided during step (a), a step of shaping said substrate to give it the shape of a support (2) of convex or hollow shape defining a concave inner face (21) suitable for receiving food and a convex outer face (22), said step b) being carried out either before step (a), or before step (d) of producing the underlayer (3), or after step (d) and before step (e) of producing the surface coating (4), or after step (e); c) optionally, a step of treating the inner face (21) of the support (2), to obtain a treated inner face (21) promoting the adhesion of an underlayer (3) to the support (2); d) a step of producing an adherent underlayer (3) on said inner face (21) of the support (2) by thermal projection of a powder or dispersion of a material chosen from;

[0196] AhCh-TiCh AhCh-SiCh AhO3-Zr02 AI2O3 and mixtures thereof, said material being a particulate material comprising particles having a Dv10 greater than or equal to 5 pm and a Dv90 less than or equal to 50 pm; said thermal spraying being a flame spraying carried out by means of a nozzle whose angle relative to the inner face (21) or the bottom (211) of the support (2) is less than or equal to 90°; so as to form on said inner face (24) of the support (2) a sub-layer (3) having an average thickness of 10 pm to 100 pm; e) a step of producing a surface coating (4) on said sub-layer (3) formed in step d).

[0197] The metal support (2), as well as the treatment step c) which can make it possible to roughen the inner face (21), are as described above.

[0198] When the metal substrate (2) is a substantially flat substrate, a shaping step (b) of said substrate (2) is carried out either before step (a), or before step (d) of producing the underlayer (3), or after step (d) and before step (e) of producing the surface coating (4), or after step (e).

[0199] Step (b) is a step of shaping the metal substrate (2), preferably by stamping. The underlayer (3) may be a hard underlayer whose shapeability is reduced. Thus, according to a first embodiment, the step of shaping the substrate (2) is carried out before step (a) or before step (d).

[0200] According to a second embodiment, the underlayer (3) can be deposited during step (d) at the level of the area of ​​the substrate (2) intended to form the bottom of the cooking element (1) and optionally at the level of the area intended to form the skirt. Said areas are less mechanically stressed during shaping. Thus, the step of shaping the substrate (2) can be carried out after step (d) of producing the underlayer (3), or after step (d) and before step (e) of producing the surface coating (4), or after step (e).

[0201] Depending on the nature of the surface coating (4) and its suitability for shaping, the shaping step may be carried out after step (e) of producing the surface coating (4).

[0202] If the surface coating (4) has poor formability, the forming is carried out before step (e).

[0203] If the surface coating (4) has good formability, the forming can be carried out after step (e).

[0204] The surface coating (4) is as described above.

[0205] According to a variant of this second embodiment, if the coating (4) is a sol-gel coating having a low capacity for shaping, then the shaping step is advantageously carried out after step (d) and before step (e) of obtaining said coating (4).

[0206] According to another variant of this same embodiment, if the surface coating (4) is a fluorinated coating or a silicone coating or a coating based on polyarylether ketone(s) which is resistant to the mechanical stresses applied during shaping, then the shaping step can be carried out after step (d) and before step (e) or after step (e) of obtaining said coating (4).

[0207] According to another variant of this same embodiment, the surface coating (4) may be different at the level of the area of ​​the substrate (2) intended to form the bottom of the cooking element (1) and at the level of the rest of the surface of the substrate 2. For example, a sol-gel surface coating with low mechanical resistance may be deposited at the level of the area of ​​the substrate (2) TJ intended to form the bottom and a more resistant fluorinated or silicone coating may be deposited on the rest. The shaping step may be carried out after step (d) and before step (e) or after step (e) of said coating (4).

[0208] Preferably, the metal support (2) in step a), when it is in the form of a substantially flat metal substrate, is in the form of a disc.

[0209] Thermal spraying, as its name suggests, involves projecting a powder or dispersion onto a surface. Thermal spraying is a flame spray.

[0210] Preferably, the material intended to be projected is a powdery material comprising particles having a Dv10 greater than or equal to 5 pm and a Dv90 less than or equal to 30 pm.

[0211] Advantageously, the average thickness of the sub-layer (3) ranges from 20 pm to 50 pm.

[0212] According to one embodiment, the thermal projection is carried out by means of a nozzle whose angle relative to the inner face (21) or the bottom (211) of the support (2) ranges from 70° to 90°, preferably from 85° to 90°, particularly preferably is 90°.

[0213] According to one embodiment, the thermal projection is carried out by means of a nozzle whose angle relative to the inner face (21) or the bottom (211) of the support (2) ranges from 30° to 70°.

[0214] Advantageously, during thermal spraying, a carrier gas is used to transport the powder or dispersion to the inner face (21) of the support (2) and the carrier gas flow rate ranges from 5 l / min to 20 l / min for a powder or dispersion flow rate ranging from 10 g / min to 120 g / min, preferably from 40 g / min to 80 g / min.

[0215] Without wishing to be bound by any theory, the inventors believe that the parameters of the process according to the invention make it possible to generate the fusion of the particles of the projected material at their outer surface without reaching the core so that the particles agglomerate while substantially retaining their shape. The particles then create an open porosity as described above with interparticle cavities connected to each other at the origin of an open porosity.

[0216] Preferably, in flame spray, step d) of producing the underlayer (3) is preceded by a step of preheating said support (2) or said cap (2) at low temperature, depending on whether step b) of shaping is carried out before producing d) the underlayer (3) or after producing e) said surface coating (4). This preheating is carried out at a maximum temperature of 100°C.

[0217] Step e) can be carried out by spray, coating, screen printing or roller.

[0218] ARTICLE

[0219] The invention also relates to a culinary article (100) comprising a cooking element (1) as described above.

[0220] According to one embodiment, the culinary article (100) comprises a heating face (6) intended to be placed in contact with an external heating source, the heating face (6) being opposite the cooking face (5) intended to be placed in contact with the food during cooking.

[0221] Advantageously, the culinary article (100) according to the invention is chosen from the group consisting of saucepan, frying pan, skillets or caquelons for fondue or raclette, stewpot, wok, sauté pan, crepe pan, grill, griddle, pot, casserole dish, cooker or bread machine bowl, culinary mold.

[0222] The invention also relates to an electrical cooking appliance (200) comprising a coated cooking element (1) according to the invention and a heating source (210) configured to heat said coated cooking element (1).

[0223] Advantageously, the electric cooking appliance (200) is chosen from the group consisting of electric crepe maker, electric raclette appliance, electric fondue appliance, electric grill, electric griddle, electric cooker, bread maker, electric pressure cooking appliance, waffle makers, rice cookers and jam makers.

[0224] The culinary article according to the present invention may in particular be a culinary article of which one of the two opposite faces of the substrate is an inner face, possibly concave, intended to be arranged on the side of food likely to be introduced into or onto said article, and of which the other face of the substrate is an outer face, possibly convex, intended to be arranged towards a heat source.

[0225] Non-limiting examples of cooking articles in accordance with the present invention include cooking articles such as saucepans and frying pans, woks and sauté pans, stewpots and pots, crepe makers, baking molds and baking trays, barbecue plates and grills, and preparation bowls.

[0226] EXAMPLES AND RESULTS

[0227] The aims, aspects and advantages of the present invention will be better understood from the description given below of a particular embodiment of the invention presented by way of non-limiting example.

[0228] Of course, the invention is in no way limited to the embodiment described and illustrated, which has been given only as an example. Modifications remain possible, in particular from the point of view of the constitution of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

[0229] Example 1: Porous ALOs-TiC^ undercoat, white sol-gel primer and aluminum finish

[0230] ALCh-TiCh powder consisting of 60% by mass of ALCh and 40% by mass of TiCh is manufactured and sold under the brand name METCO Amdry 6250. Its particle size characteristics are as follows: Dv10=5 pm and Dv90=25 pm.

[0231] Process parameters:

[0232] - Equipment: Eutectic-Castodyn Castodyn DS8000 spray flame torch with a Eutectic-Castodyn SSM30 module reference flame nozzle.

[0233] - the torch movement speed is 150 to 200 mm / s

[0234] - double powder dispenser - Sulzer Metco 9MPE-CL & Powder mixing flow rate: varies from 10 to 120 g / min

[0235] - Undercoat thickness: 10 pm - 100 pm

[0236] - Propellant gas: Argon varies from 5 to 20 l / min at a pressure between 1 and 5 bars

[0237] - Fuel gas: acetylene varies from 10 to 16 I / min and acetylene pressure varies from 0.5 b to

[0238] 1 b

[0239] - Combustible gas: oxygen varies from 10 to 20.0 I / min and oxygen pressure varies from 3 to 5 b - The temperature of the support during the application of the base: equal to or higher than the ambient temperature (in the order of 20 to 250°C)

[0240] - Torch application distance - room between 8 cm and 20 cm

[0241] - Rotation speed of parts between 200 and 1,500 rpm

[0242] - Projection angle: 30° to 90°

[0243] The flame spray thermal projection method or flame thermal projection is a method for manufacturing a culinary article, characterized in that it comprises, in the case of example 1, the following steps: a) a step of providing a metal support in the form of an aluminum disc, comprising two opposite faces; b) a step of shaping said support to give it the shape of a cap, which comprises a bottom and a side wall rising from the bottom, and thus define a concave inner face suitable for receiving food and a convex outer face; c) a step of treating the inner face of the support by sandblasting, to obtain a treated inner face promoting the adhesion of an underlayer on the support; d) a step of producing an adherent underlayer on said inner face of the support; e) a step of producing a coating on said hard base formed in step d);said method being characterized in that step d) of producing the hard base comprises thermal projection, on said inner face of a ceramic material in powder form, so as to form on said inner face of the cap a layer which is at least discontinuous, the discontinuous part being in the form of a stack of particles, substantially distributed homogeneously on said inner inner face.;

[0244] The open porosity of the sub-layer (3) is determined as follows:

[0245] - determination by weighing of the deposited mass of AI2C>3-TiO2 by thermal projection

[0246] - permascope measurement of the deposited thickness (average of 10 measurements). This non-destructive method is a measurement method using eddy currents and / or magnetic currents.

[0247] - measurement of the diameter of the deposited layer (23 cm for a pan with a diameter of 26 cm)

[0248] - calculation of the theoretical mass of the deposited layer if it had no porosity (density AI203 / TiO2(40%) = 4.06)

[0249] - calculation of open porosity = (1 - (deposited mass / theoretical mass))*100

[0250] As an example, a porosity rate of 62% is calculated for a measured thickness of 34 pm, a rate of 55% for a thickness of 48 pm and a rate of 48% for a thickness of 63 pm. With this method, repeatable results are obtained (on 8 parts) and consistent with what is observed in SEM / EDX imaging (see Figure 3 - thickness of the underlayer (3) of 50 pm). The ceramic coating, both primary and finish, is prepared from a two-component system: part A and part B respectively:

[0251] Part A includes pigments (in the case of a primer), fillers and additives;

[0252] Part B incorporates the reactive silanes and the catalyst.

[0253] White primer

[0254] [Table 2]

[0255] Hydrophobic finish

[0256] [Table 3] The process for formulating the primer and finish is as follows:

[0257] Part A is prepared by successively introducing colloidal silica, isopropanol, and where appropriate pigment, alumina, or additives into a planetary mixer to obtain a homogeneous liquid. This mixing can also be carried out under a shearing paddle.

[0258] The B parts are prepared separately by mixing the silanes with the organic acid, as well as the wetting agent, the solvent and the glitter in the case of the finish.

[0259] These two parts can be stored separately for six months.

[0260] Parts A and B are then mixed using a high-speed stirrer for three hours to allow the silane to hydrolyze. The mixture is then left at room temperature for 24 hours before application. The shelf life of this formulation is at least 48 hours.

[0261] The primer mix is ​​then filtered with a 60 micron filter before being spray-applied onto the ALOs-TiCh undercoat. The thickness of the entire solgel primer / undercoat composite is 45 pm to 140 microns, the thickness depending on the thickness of the ALCh-TiCh undercoat.

[0262] This primer coat is then optionally dried at 50°C for one minute before cooling to 30°C.

[0263] The finish mixture will be filtered through a 110 micron filter and sprayed onto the primer coat. Its dry thickness will be 5 to 20 microns.

[0264] With this method, we obtain repeatable results consistent with what we observe in SEM / EDX imaging (see Figure 4).

[0265] In the case of Figures 3 and 4: the thickness of the undercoat (3) is 50 pm; the thickness of the entire undercoat (3) / sol-gel primer (4a) composite is 75 pm; the thickness of the topcoat (4b) is 10 pm. 2: White sol-gel AbOs-SiC undercoat and aluminum finish

[0266] ALCh-SiCh powder consisting of 75% by weight AI2O3 and 25% by weight of SiC>2 is manufactured and sold under the brand name METCO, reference Mollit. Its particle size characteristics are as follows: Dv10 = 5 pm and Dv90 = 22 pm.

[0267] Process parameters:

[0268] - Equipment: Eutectic-Castodyn Castodyn DS8000 spray flame torch with a Eutectic-Castodyn SSM30 module reference flame nozzle.

[0269] - the torch movement speed is 150 to 200 mm / s

[0270] - double powder dispenser - Sulzer Metco 9MPE-CL & Powder mixing flow rate: varies from 10 to 120 g / min

[0271] - Undercoat thickness: 20 pm - 50 pm

[0272] - Propellant gas: Argon varies from 5 to 20 l / min at a pressure between 1 and 5 bars

[0273] - Fuel gas: acetylene varies from 10 to 16 I / min and acetylene pressure varies from 0.5 b to

[0274] 1 b

[0275] - Combustible gas: oxygen varies from 10 to 20.0 I / min and oxygen pressure varies from 3 to 5 b

[0276] - The temperature of the support during application of the hard base: equal to or higher than room temperature (around 20 to 250°C)

[0277] - Torch application distance - room between 8 cm and 20 cm

[0278] - Rotation speed of parts between 200 and 1,500 rpm

[0279] - Projection angle: 30° to 90°

[0280] The porosity of the underlayer (3), calculated as for example 1, is 40% to 70% depending on the thickness deposited.

[0281] The two-layer sol-gel coating is then prepared and sprayed in the same manner as in Example 1.

[0282] In the case of Figures 5 and 6: the thickness of the undercoat (3) is 40 pm; the thickness of the entire undercoat (3) / sol-gel primer (4a) composite is 80 pm; the thickness of the topcoat (4b) is 10 pm. Comparative example: white sol-gel primer and hydrophobic finish, without undercoat, on aluminum

[0283] In this comparative example, there is no undercoat (3) applied to the sandblasted aluminum substrate, but directly the same sol-gel primer and finish coats as examples 1 and 2.

[0284] The formulation, coating and final cooking processes are also unchanged from Example 1.

[0285] TEST RESULTS AND MEB / EDX CHARACTERIZATION

[0286] Scratch resistance test:

[0287] Using a 200 μm radius Rockwell diamond tip, a progressive load is applied to the coating, increasing the applied force from 0 to 30 Newtons. The trace of the scratch is then observed under an optical microscope. The delamination value retained for the coating corresponds to the force for which a clear break of the film down to the metal is observed. The parameters of load increase rate and tip displacement speed are kept constant for all tests.

[0288] For each sample, 5 scratches are carried out, and the average of the 5 metal delamination values ​​is retained.

[0289] The results of the 3 configurations are reported below:

[0290] Tested configuration Scratch to metal (in N) [Table 4]

[0291] The gain in scratch resistance is very marked.

[0292] The results can also be visualized in Figures 1 (Example 1 - 18N metal scratch for 50pm undercoat thickness) and 2 (Comparative example). MEB / EDX characterizations:

[0293] The SEM is a versatile, multifunctional equipment that allows obtaining images of the surface structure and morphology of the material with a resolution of a few nm and a very large depth of field; It also provides qualitative (BSE) and quantitative (EDX, lateral resolution around 1 pm) chemical information.

[0294] EDX is a technique in which the X-rays generated by the interaction between the electron beam and the sample are analyzed to give an elemental composition of the sample. An EDX spectrum has peaks that correspond to the characteristic radiation of a specific element. A quantitative chemical characterization of the sample is deduced from the EDX spectrum.

[0295] The MEB-EDX analysis technique allows the coupling of a surface topographic analysis with a scanning electron microscope (SEM) with a chemical analysis using energy dispersive X-ray spectroscopy (EDX).

[0296] The principle of SEM is based on the detection of secondary electrons. A beam of electrons (called primary electrons) comes into contact with the surface of the sample. When they collide with the atoms present on the surface, the primary electrons can transfer energy to electrons on the upper layers of these atoms. These electrons are then ejected; we speak of secondary electrons. The analysis of these electrons, which come from the surface layers, makes it possible to obtain information on the topography. When the primary electrons collide with the atoms, the latter can pass into an excited state. When they return to a stable state, they emit X-rays whose wavelength is characteristic of the nature of the atom. Thus, the analysis of these X-rays makes it possible to obtain information on the chemical nature of the sample.

[0297] Figure 3 shows a SEM sectional view of the coated cap according to example 1:

[0298] (2) represents the aluminum cap (2)

[0299] (3) represents the sub-layer (3)

[0300] (4a) represents the sol-gel primer of the surface coating (4)

[0301] (4b) represents the sol-gel topcoat of the surface coating (4).

[0302] The sub-layer (3) is in the form of a stack of AhCh-TiCh particles. The AhCh-TiCh particles agglomerate while substantially retaining their shape. The particles then create an open porosity with interparticle cavities connected to each other, resulting in an open porosity.

[0303] Figure 3 shows that the undercoat (3) is very porous and that the undercoat (3) and the sol-gel primer are interpenetrated throughout the thickness of the undercoat (3).

[0304] The spray-coated sol-gel coating is impregnated into the macroporosity of the sub-layer, this creates, after crosslinking of the sol-gel network, a composite, without the need for post-treatment (hot pressing, etc.). This creates a dense network, with excellent mechanical properties due to the anchoring of the sol-gel in the ceramic matrix (Figures 3 and 4).

[0305] The physicochemical analysis by SEM-EDX analysis of the surface (Figure 4) illustrates the distribution of silicon (present in the sol-gel coating) and shows that silicon is present up to the aluminum substrate. Figure 4 therefore also shows that the undercoat (3) and the sol-gel primer are interpenetrated over the entire thickness of the undercoat (3).

[0306] The porosity of the undercoat (3), the pore filling percentage and the interpenetration of the undercoat (3) and the sol-gel coating (4) can be determined by image analysis as follows.

[0307] On 5 sectional views of length 0.4 mm: determination of the average thickness (ep) of the sub-layer (3), by analysis of the gray levels on the SEM views of the surface ep mm * 0.4 mm, determination of the surface percentage of open pores devoid of o AhCh-TiCh o AhCh-SiCh o AhCh-ZrCh o AI2O3 o or their mixtures, said surface percentage corresponding to the porosity rate of the sub-layer (3). by EDX analysis on the SEM views of the surface ep mm * 0.4 mm: o determination of the surface percentage occupied by the surface coating (4) and calculation of the pore filling percentage (= surface % occupied by the coating / surface % of open pores determined above) o determination of the average penetration thickness of the surface coating (4) and calculation of the interpenetration percentage by calculating the ratio of the average penetration thickness of the coating to the thickness ep of the sub-layer (3).

[0308] The porosity rate of the sub-layer (3), the percentage of pore filling and the interpenetration of the sub-layer (3) and the sol-gel coating correspond to the average of the values ​​obtained for the 5 sectional views.

[0309] Thus, in the case of example 1: porosity of the sub-layer (3) = 45% pore filling percentage = greater than 90%

[0310] - the coating (4) penetrates into the thickness of the underlay (3) down to the support to a depth of 100% relative to the thickness of the underlay (3).

[0311] Figure 5 and Figure 6 represent a SEM cross-sectional view of the coated cap according to example 2 and a SEM / EDX analysis (chromium monitoring) of this same layer. They show that the sub-layer (3) is very porous and that the sub-layer (3) and the sol-gel primer are interpenetrated over the entire thickness of the sub-layer (3).

[0312] Thus, in the case of example 2: porosity of the undercoat (3) = 51% pore filling percentage = greater than 90% the coating (4) penetrates into the thickness of the undercoat (3) down to the support to a depth of 100% compared to the thickness of the undercoat (3).

Claims

CLAIMS 1 . Cooking element (1) comprising a metal support (2) which comprises an inner face (21) adapted to receive food and an outer face (25), said inner face (21) being coated with a coating (5) consisting successively, from the support (2), of a sub-layer (3) and a surface coating (4), characterized in that the sub-layer (3) is in the form of a discontinuous layer, is made of one or more materials chosen from the group consisting of AI2O3-TO2, AhO3-SiO2, AhO3-ZrO2, AI2O3 and their mixtures and has open pores over all or part of the thickness of the sub-layer representing from 20 to 70% by volume of the volume of said sub-layer (3), which open pores are filled at a rate of 40% to 100% by volume by the surface coating (4), and in that the surface coating (4) penetrates into the thickness of the sub-layer (3) on a depth of at least 30% compared to the thickness of the sub-layer (3).

2. Cooking element (1) according to claim 1, characterized in that the average thickness of the underlayer (3) ranges from 10 μm to 100 μm, preferably from 20 μm to 50 μm.

3. Cooking element (1) according to claim 1 or claim 2, characterized in that the penetration depth of the surface coating (4) into the thickness of the underlayer (3) is at least 70%, preferably at least 85% relative to the thickness of the underlayer (3).

4. Cooking element (1) according to any one of the preceding claims, characterized in that the filling rate of the open pores of the underlayer (3) by the surface coating (4) ranges from 60% to 100%, preferably from 80% to 100% by volume of the total volume of said open pores.

5. Cooking element (1) according to any one of the preceding claims, characterized in that the sub-layer (3) is in the form of a stack of particles of said material(s), said particles having a Dv10 greater than or equal to 5 pm and a Dv90 less than or equal to 50 pm, preferably a Dv10 greater than or equal to 5 pm and a Dv90 less than or equal to 30 pm.

6. Cooking element (1) according to any one of the preceding claims, characterized in that the surface coating (4) comprises at least one layer comprising at least one fluorocarbon resin, or at least one layer comprising at least one silicone resin, or at least one sol-gel layer, or at least one layer comprising one or more polyarylether ketone(s) (PAEK).

7. Cooking element (1) according to any one of the preceding claims, characterized in that the support (2) is a single-layer support made of aluminum or aluminum alloy, cast aluminum, stainless steel, cast steel or copper, or a multi-layer support comprising from the outside to the inside the following layers ferritic stainless steel / aluminum / austenitic stainless steel or stainless steel / aluminum / copper / aluminum / austenitic stainless steel, or a cap of cast aluminum, aluminum or aluminum alloys lined with an outer base of stainless steel.

8. Method for manufacturing a culinary article or an electrical cooking appliance comprising a cooking element (1) according to any one of claims 1 to 7, characterized in that it comprises the following steps: a) a step of providing a metal substrate in the form of a substantially flat metal substrate comprising two opposite faces or a support (2) of convex or hollow shape defining a concave inner face (21) adapted to receive food and a convex outer face (22);b) where appropriate, when a metal substrate in the form of a substantially flat metal substrate is provided during step (a), a step of shaping said substrate to give it the shape of a support (2) of convex or hollow shape defining a concave inner face (21) suitable for receiving food and a convex outer face (22), said step (b) being carried out either before step (a), or before step (d) of producing the underlayer (3), or after step (d) and before step (e) of producing the surface coating (4) or after step (e); c) optionally, a step of treating the inner face (21) of the support (2), to obtain a treated inner face (21) promoting the adhesion of an underlayer (3) to the support (2); d) a step of producing an adherent underlayer (3) on said inner face (21) of the support (2) by thermal projection of a powder or dispersion of a material chosen from; AhCh-TiCh AhCh-SiCh AhO3-Zr02 AI2O3 and their mixtures, said material being a particulate material comprising particles having a Dv10 greater than or equal to 5 pm and a Dv90 less than or equal to 50 pm; said thermal spraying being a flame spraying carried out by means of a nozzle whose angle relative to the inner face (21) or the bottom (211) of the support (2) is less than or equal to 90°; so as to form on said inner face (24) of the support (2) a sub-layer (3) having an average thickness of 10 pm to 100 pm; e) a step of producing a surface coating (4) on said sub-layer (3) formed in step d).

9. Method according to claim 8, characterized in that the material intended to be projected is a particulate material comprising particles having a Dv10 greater than or equal to 5 pm and a Dv90 less than or equal to 30 pm.

10. Method according to any one of claims 8 to 9, characterized in that the average thickness of the sub-layer (3) ranges from 20 μm to 50 μm.

11. Method according to any one of claims 8 to 10, characterized in that, during thermal projection, a carrier gas is used to transport the powder or dispersion to the inner face (21) of the support (2) and in that the flow rate of carrier gas ranges from 5 l / min to 20 l / min for a flow rate of powder or dispersion ranging from 10 g / min to 120 g / min, preferably from 40 g / min to 80 g / min.

12. Method according to any one of claims 8 to 11, characterized in that step e) is carried out by spray, by coating, by screen printing or by roller.

13. Culinary article (100) comprising a cooking element (1) according to any one of claims 1 to 7.

14. Culinary article (100) according to claim 13 characterized in that it comprises a heating face (6) intended to be placed in contact with an external heating source, the heating face (6) being opposite the cooking face (5) intended to be placed in contact with the food during cooking.

15. Culinary article (100) according to one of claims 13 or 14 chosen from the group consisting of saucepan, frying pan, skillets or pots for fondue or raclette, stewpot, wok, sauté pan, crepe pan, grill, griddle, pot, casserole dish, cooker or bread machine bowl, cooking mold.

16. Electrical cooking appliance (200) comprising a cooking element (1) and a heating source (210) configured to heat said cooking element (1), characterized in that said cooking element (1) is according to any one of claims 1 to 7.

17. Electric cooking appliance (200) according to claim 16, chosen from the group consisting of electric crepe maker, electric raclette appliance, electric fondue appliance, electric grill, electric griddle, electric cooker, bread maker, electric pressure cooking appliance, waffle makers, rice cookers and jam makers.

Images