Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C45/00—Amorphous alloys
  • C22C45/10—Amorphous alloys with molybdenum, tungsten, niobium, tantalum, titanium, or zirconium or Hf as the major constituent
• • A—HUMAN NECESSITIES
  • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
  • A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
  • A47J36/00—Parts, details or accessories of cooking-vessels
  • A47J36/02—Selection of specific materials, e.g. heavy bottoms with copper inlay or with insulating inlay

Definitions

• the present invention relates to the field of articles intended for the preparation and cooking of food and more particularly the cooking surface of these articles that is in contact with the food to be processed.
• Metal deposition such as chromium plating on stainless steel, quasi-crystals, or nonmetallics (silicates, . . . ) thus appeared.
• Quasi-crystals are a phase or metal compound presenting, at the crystallographic level, symmetries of rotation of the axis of the order 5, 8, 10 or 12, as icosahedral and decagonal phases.
• Such coatings are in particular described in patent EP 0 356 287 and have qualities of scratch resistance, even non-stick in certain cases.
• the document FR 2784280 describe a composite cooking surface constituted by two phases, ceramic and metal, intended to bring to treated kitchen utensil bottoms a non-deformability in their range of use, as well as a good wear resistance.
• such coatings do not have very good performance with regard to ease of cleaning, so that the addition of a solid lubricant, such PTFE, is often recommended when this function is required. This additional step involves overall a significant cost for the development of such a cooking surface.
• the present invention aims at overcoming the above mentioned disadvantages of the prior art, by proposing a cooking surface with scratch resistance, ease of cleaning, corrosion resistance characteristics.
• the present invention is achieved by a food cooking surface for a kitchen utensil or cooking appliance, characterized in that this cooking surface is of an amorphous metal alloy.
• amorphous metal alloys also called metal glasses brings interesting properties in term of surface properties (hardness in particular), and corrosion resistance. Indeed, the absence of a crystalline phase leads to the absence of crystalline solid defects (dislocations, grain boundary . . . ) and the phenomena induced by these defects (in particular corrosion at the grain boundaries).
• the presence of a nanocrystalline phase can observed.
• the nanocrystalline structure has properties close to the amorphous structure, by the absence of atomic order at large distance, at least with regard to the desired characteristics, such as previously mentioned.
• the alloy has the formula A a D b E c X d in which:
• alloys comprising at least three elements are more stable than binary alloys, and are all the more stable as the number of elements is large.
• the alloys obtained remain in particular stable, without structural transformation, when they are brought up to temperatures of the order of 300° C., temperatures that are higher than the temperatures usually used for food cooking.
• zirconium also makes it possible to further increase the thermal stability of the final alloy.
• the metal alloy is of the formula Zr a Cu b Ni c Al d Ti e X f , where a, b, c, d, e, are the respective proportions of Zr, Cu, Ni, Al and Ti in the alloy, said proportions being comprised within the following ranges:
• compositions were selected in particular so that the corresponding alloy has a high vitreous transition temperature.
• the compositions were a priori defined to approach the compositions corresponding to eutectics in order to decrease the temperature of the liquid, which allows lower speeds of cooling to obtain the amorphous state with or without the presence of nanocrystalline phase.
• composition of alloys was also adjusted according to the intended properties of mechanical strength, corrosion resistance and ease of cleaning of the alloy obtained.
• the food cooking surface of the kitchen utensil or cooking appliance is obtained by the deposit of a suitable thickness of metallic material on a substrate.
• This deposit can be carried out by one or the other of the following processes: thermal projection of a powder of adequate granulometry, deposit by electrophoresis of a micro or submicronic powder, cathode sputtering of a massive target.
• the target can be obtained by assembly on a copper substrate of one or several sheets or plates of a material having the desired composition, said sheets or plates being obtained either by powder sintering or thermal projection of powder, or resulting from casting.
• Other techniques, such as hot compaction or the deposit by electrolyses also can be used.
• This implementation has the advantage of using little material and of being able to adjust the thickness of the cooking surface.
• the material deposited in the processes previously described can result from a powder, amorphous from the start or obtained by grinding of a crystallized alloy, said powder then undergoing a step of vitrification before the depositing step or at the time of the depositing step, according to the technique used. In this procedure, the idea is thus to obtain the amorphous phase at the very end.
• the food cooking surface of the kitchen utensil or cooking appliance is obtained by assembly of an amorphous alloy sheet with or without the presence of a nanocrystalline phase on a substrate.
• This implementation has the advantage of approaching the known implementations for assembly of metals, which makes it possible to be able to adapt known techniques without significant specific development.
• the sheet is obtained by rolling of an amorphous ingot resulting from melting of a mixture of metals. It is particularly favorable, from an economic point of view, to use the method of melting then rolling, in particular in the case of amorphous materials, because they show a significant rate of reduction by rolling, with controlled temperature.
• the sheet is obtained by the technique of solidification on a wheel.
• This technique by solidifying metal alloy on a cooled wheel driven in rotation, makes it possible to obtain sufficiently high cooling speeds so that an amorphous film can formed.
• the thicknesses obtained being able to reach 0.1 mm, are completely compatible with the use envisioned, without it being necessary to carry out a later rolling.
• the assembly of the sheet on the substrate is carried out by one of the following techniques: colaminating, brazing, hot striking, in a manner known per se.
• the sheet and the substrate undergo, after assembly, a step of forming by stamping.
• the example of realization of the invention relates to a massive amorphous alloy substrate of composition Zr 60 Cu 17.5 Ni 10 Al 7.5 Ti 5 obtained by melting in an inductive crucible of a massive ingot cooled in a copper mould according to conditions leading to the formation of an amorphous alloy.
• One face of this substrate underwent an intensive polishing, approximating an optical polishing, before the performance of tests, in order to make it comparable with other cooking surfaces so that the tests for evaluation of the ease of cleaning such a surface, in a domestic cooking use, can be compared.
• This system for evaluation comprises the following steps:
• the following comparative table shows the results obtained on three different cooking surfaces, namely polished stainless steel, quasi-crystals, and the amorphous alloy of formulation Zr 60 Cu 17.5 Ni 10 Al 7.5 Ti 5 such as previously described, in a severe test with a food composition based on milk and rice considered to be difficult to clean once carbonized. Such a test thus makes it possible to highlight well the differences between cleaning quality of the surfaces. Polished stainless steel Quasi-crystals Amorphous Quantity of 25% 30% 90% carbonized residue removed
• the present invention is not limited to the realization of a layer of small thickness of an amorphous metal alloy with or without the presence of a nanocrystalline phase deposited or assembled on a thick substrate, but also aims at the realization of massive material, with or without a substrate, this latter, when it is present, not having a mechanical supporting role for the layer, but assuring another function, such as the thermal distribution of heat for a utensil placed on a heat source (frying pan, sauce pan, . . . ).

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Food Science & Technology (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Cookers (AREA)

Applications Claiming Priority (3)

Publications (1)

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Cited By (8)

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Citations (8)

Family Cites Families (4)

• 2002
  • 2002-05-30 FR FR0206644A patent/FR2840177B1/fr not_active Expired - Fee Related
• 2003
  • 2003-05-22 JP JP2004510492A patent/JP4390275B2/ja not_active Expired - Fee Related
  • 2003-05-22 WO PCT/FR2003/001550 patent/WO2003102259A1/fr active Application Filing
  • 2003-05-22 EP EP10177986.6A patent/EP2316982A3/fr not_active Withdrawn
  • 2003-05-22 RU RU2004138572/12A patent/RU2318424C2/ru not_active IP Right Cessation
  • 2003-05-22 AU AU2003260564A patent/AU2003260564A1/en not_active Abandoned
  • 2003-05-22 US US10/511,828 patent/US20050205172A1/en not_active Abandoned
  • 2003-05-22 EP EP03756003A patent/EP1507880A1/fr not_active Withdrawn

Patent Citations (8)

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