U.S. patent application number 10/511828 was filed with the patent office on 2005-09-22 for easy-clean cooking surface and electrical household appliance comprising such a surface.
Invention is credited to Coudurier, Alain.
Application Number | 20050205172 10/511828 |
Document ID | / |
Family ID | 29558848 |
Filed Date | 2005-09-22 |
United States Patent
Application |
20050205172 |
Kind Code |
A1 |
Coudurier, Alain |
September 22, 2005 |
Easy-clean cooking surface and electrical household appliance
comprising such a surface
Abstract
The invention relates to a food cooking surface for a kitchen
utensil or cooking device, characterized in that said cooking
surface is either an amorphous metallic alloy or a nanocrystalline
metallic alloy. According to the invention, the amorphous alloy has
the formula AaDbEcXd where: A=Zr or Cu, D is at least one element
selected from Ni, Cu, Al if A=Zr or at least one element selected
from, Zr, Al if A=Cu, E=at least one element selected from Ti, or
Hf, X=the impurities of production with 40%<a<70% at. %,
5%<b<30% at. %, c<10% at. %, d<1% at. %, and
a+b+c+d=100% at. %.
Inventors: |
Coudurier, Alain; (Albens,
FR) |
Correspondence
Address: |
BROWDY AND NEIMARK, P.L.L.C.
624 NINTH STREET, NW
SUITE 300
WASHINGTON
DC
20001-5303
US
|
Family ID: |
29558848 |
Appl. No.: |
10/511828 |
Filed: |
October 20, 2004 |
PCT Filed: |
May 22, 2003 |
PCT NO: |
PCT/FR03/01550 |
Current U.S.
Class: |
148/403 |
Current CPC
Class: |
C22C 45/10 20130101;
A47J 36/02 20130101 |
Class at
Publication: |
148/403 |
International
Class: |
C22C 045/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 2002 |
FR |
02/06644 |
Claims
1. Food cooking surface for a kitchen utensil or cooking appliance,
characterized in that this cooking surface is of an amorphous metal
alloy.
2. Cooking surface according to claim 1, characterized in that the
alloy contains a nanocrystalline phase.
3. Food cooking surface for a kitchen utensil or cooking appliance
according to claim 1, characterized in that the alloy has the
formule A.sub.aD.sub.bE.sub.cX.sub.d in which: A is one of the
elements Zr or Cu, D is at least one element chosen from the group
consisting of Ni, Cu, Al if A is Zr or at least one element chosen
from the group consisting if Ni, Zr, Al if A is Cu, E is at least
one element chosen from the group consisting of Ti, Hf, X
represents the impurities of production, with: 40%<a<70% at,
5%<b<30% at, c<10% at, d<1% At, and a+b+c+d=100%
at.
4. Food cooking surface for a kitchen utensil or cooking appliance
according to claim 3, characterized in that the metal alloy is of
the formula Zr.sub.aCu.sub.bNi.sub.cAl.sub.dTi.sub.eX.sub.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: 40%<a<70% 10%<b<25% 5%<c<15%
5%<d<15% 2%<e<10%, where x represents the impurities of
production, with f <1% at, where a+b+c+d+e+f=100% at.
5. Food cooking surface for a kitchen utensil or cooking appliance
according to claim 1, characterized in that it is obtained by the
deposit of a suitable thickness of metallic material on a
substrate.
6. Food cooking surface for a kitchen utensil or cooking appliance
according to claim 5, characterized in that the deposit is obtained
by cathode sputtering of a massive target.
7. Food cooking surface for a kitchen utensil or cooking appliance
according to claim 6, characterized in that the target is 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.
8. Food cooking surface for a kitchen utensil or cooking appliance
according to claim 5, characterized in that the material results
from a powder of the alloy obtained by grinding of a crystallized
alloy, said powder then undergoing a step of vitrification.
9. Food cooking surface for a kitchen utensil or cooking appliance
according to claim 1, characterized in that it is obtained by
assembly of an amorphous alloy sheet on a substrate.
10. Food cooking surface for a kitchen utensil or cooking appliance
according to claim 9, characterized in that the sheet is obtained
by rolling of an amorphous ingot resulting from melting of a
mixture of metals.
11. Food cooking surface for a kitchen utensil or cooking appliance
according to claim 9, characterized in that the sheet is obtained
by the technique of solidification on a wheel.
12. Food cooking surface for a kitchen utensil or cooking appliance
according to claim 9, characterized in that the assembly is carried
out by one of the following techniques: colaminating, brazing, hot
striking.
13. Food cooking surface for a kitchen utensil or cooking appliance
according to claim 9, characterized in that the sheet and the
substrate undergo, after assembly, a step of forming by
stamping.
14. Food cooking surface for a kitchen utensil or cooking appliance
according to claim 5, characterized in that the substrate is
composed of one or more metal sheet(s) of the following materials:
aluminum, stainless steel, cast iron, steel, copper.
15. A kitchen utensil or cooking appliance having a food cooking
surface as defined in claim 1.
Description
[0001] 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.
[0002] For many years, significant efforts have been developed in
order to facilitate the everyday preparation of meals. Among the
notable progress, coatings, or claddings, based on fluorocarbonated
polymers as non-stick coating in kitchen utensils quickly developed
since the end of 1950. Such coatings are universally known since
the process presented in the patent FR 1120749 allowed a sure
fixing of such coatings on various metals, such as aluminum.
[0003] However, such coatings remain fragile. Thus, easy ways were
developed in order to mechanically reinforce the layer on its
support. Many improvement patents describe methods and means making
it possible to increase the scratch resistance of such coatings, by
acting on the coating and/or on the substrate. Even so, such
coatings remain sensitive to the repeated use of sharp or pointed
metallic materials, such knives or forks.
[0004] At the same time, developments were carried out on
mechanically resistant surfaces for which it was attempted to
improve the ease of cleaning. Metal deposition, such as chromium
plating on stainless steel, quasi-crystals, or nonmetallics
(silicates, . . . ) thus appeared.
[0005] 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.
[0006] In addition, 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. However, 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.
[0007] 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.
[0008] 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.
[0009] The use of 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).
[0010] According to the formulation and the manner of producing the
alloy, the presence of a nanocrystalline phase can observed.
However, 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. One could even expect a slight improvement
of the hot behavior, in particular with regard to its hardness.
[0011] In a surprising way, it was noted, during tests, that some
amorphous metal alloy coatings also presented properties of ease of
cleaning, which can also be expressed by the possibility of easily
removing elements carbonized on the cooking surface. However, among
these alloys, some are not compatible with food contact.
[0012] Thus, advantageously, the alloy has the formula
A.sub.aD.sub.bE.sub.cX.sub.d in which:
[0013] A is one of the elements Zr or Cu,
[0014] D is at least one element chosen from the group consisting
of Ni, Cu, Al if A is Zr or at least one element chosen from the
group consisting if Ni, Zr, Al if A is Cu,
[0015] E is at least one element chosen from the group consisting
of Ti, Hf,
[0016] X represents the impurities of production, with:
[0017] 40%<a<70% at,
[0018] 5%<b<30% at,
[0019] c<10% at,
[0020] d<1% At, and
[0021] a+b+c+d=100% at.
[0022] It is significant to note that this selection has already
been carried out among alloys being able to made amorphous.
Moreover, other elements have voluntarily been put aside by their
toxicity with respect to humans. The coatings proposed thus do not
supply any toxicity to food in contact, even brought to high
temperature.
[0023] In addition, the selection of the components of alloy also
took account of the elements which support the germination of
crystals, in order to limit this phenomenon.
[0024] The contents of various elements are the result of the
fabrication conditions, supplemented by tests concerning the
abrasion resistance and the ease of cleaning of such coatings after
difficult cooking.
[0025] Account is also taken of eutectic compositions that have a
low melting point as well as a lower viscosity of the liquid,
favorable to obtaining the amorphous state.
[0026] Various tests have shown in an unexpected way that a
significant proportion of zirconium makes it possible to obtain
coatings presenting an exceptional ease of cleaning.
[0027] Moreover, studies have shown that the 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.
[0028] The alloys obtained remain in particular stable, without
structural transformation, when they are brought up to temperatures
of the order of 300.degree. C., temperatures that are higher than
the temperatures usually used for food cooking.
[0029] In addition, zirconium also makes it possible to further
increase the thermal stability of the final alloy.
[0030] According to an advantageous realization of this invention,
the metal alloy is of the formula
Zr.sub.aCu.sub.bNi.sub.cAl.sub.dTi.sub.eX.s- ub.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:
[0031] 40%<a<70%
[0032] 10%<b<25%
[0033] 5%<c<15%
[0034] 5%<d<15%
[0035] 2%<e<10%,
[0036] and where x represents the impurities of production, with
f<1% at.
[0037] In this formulation, a+b+c+d+e+f=100 % at.
[0038] The elements entering into the composition of these alloys
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.
[0039] Of course, the composition of alloys was also adjusted
according to the intended properties of mechanical strength,
corrosion resistance and ease of cleaning of the alloy
obtained.
[0040] According to a first mode of implementation of the
invention, 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. In this last case 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.
[0041] This implementation has the advantage of using little
material and of being able to adjust the thickness of the cooking
surface.
[0042] All of these techniques make it possible, in addition, to
obtain deposits having strong cohesion with the substrate on which
they are deposited. The risks of degradation of the deposit by
pointed objects of the knife or fork type are thus very low.
[0043] 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.
[0044] According to a second mode of implementation of the
invention, 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.
[0045] According to a procedure, 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.
[0046] According to another process of development, the sheet is
obtained by the technique of solidification on a wheel.
[0047] 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.
[0048] In this second mode of implementation of the invention, 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.
[0049] Advantageously, the sheet and the substrate undergo, after
assembly, a step of forming by stamping.
[0050] Other advantages resulting from the tests will appear from a
reading of the description that will follow, in relation to an
illustrative example of the present invention given as a
non-limiting example.
[0051] The example of realization of the invention relates to a
massive amorphous alloy substrate of composition
Zr.sub.60Cu.sub.17.5 Ni.sub.10Al.sub.7.5Ti.sub.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.
[0052] The system for evaluation of the ease of cleaning makes it
possible to quantify the capability of a cooking surface to be
restored to its original appearance after use. This system for
evaluation comprises the following steps:
[0053] surface is locally covered with a food mixture of known
composition,
[0054] this mixture is carbonized, or burnt, in a furnace under
defined conditions, for example 210.degree. C for 20 minutes,
[0055] after cooling, the surface is caused to soak during a
controlled time in a mixture of water and detergent,
[0056] an abrasive pad is then applied under a defined constraint
using an abrading apparatus (plynometer) to the soiled surface in a
back and forth movement for a given number of cycles,
[0057] the percentage of correctly cleaned surface is noted and
characterizes the ease of cleaning of the cooking surface.
[0058] The tests carried out on various types of surface thus make
it possible to comparatively evaluate the quality of the surfaces
as regards their ease of cleaning.
[0059] Of course, the tests are carried out by respecting the same
parameters for each step of the system of evaluation: same food
mixture, same surface to which the food mixture is applied, same
temperature of carbonization,...
[0060] 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.sub.60Cu.sub.17.5Ni.sub.10Al.sub.7.5Ti.sub.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.
1 Polished stainless steel Quasi-crystals Amorphous Quantity of 25%
30% 90% carbonized residue removed
[0061] The table shows without ambiguity the exceptional results
obtained with the amorphous alloy.
[0062] It should be noted that the number of cycles of abrasion on
the plynometer was fixed at 10. This low number of cycles
highlights well the quality of ease of cleaning of the amorphous
surface since there remains no more than 10% of the soiled surface
after only 10 back and forth passes of the abrasive pad.
[0063] Repetitive tests after complete cleaning of the surface show
that the ease of cleaning of the amorphous alloy is not
altered.
[0064] When the implementation of the invention implies the use of
a substrate, this one is then composed of one or more metal
sheet(s) of the following materials: aluminum, stainless steel,
cast iron, steel, copper. However, 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, . . . ).
* * * * *