U.S. patent application number 10/522688 was filed with the patent office on 2006-05-11 for method for coating the surface of a metallic material, device for carrying out said method.
Invention is credited to Daniel Chaleix, Patrick Choquet.
Application Number | 20060096674 10/522688 |
Document ID | / |
Family ID | 30129694 |
Filed Date | 2006-05-11 |
United States Patent
Application |
20060096674 |
Kind Code |
A1 |
Choquet; Patrick ; et
al. |
May 11, 2006 |
Method for coating the surface of a metallic material, device for
carrying out said method
Abstract
The invention relates to a method for coating the surface of a
metallic material having a crystallographic structure. The
inventive method consists in producing a first coating of said
material with a metal layer or a metal alloy layer having a melting
point of T.sub.f and a thickness equal to or less than 2.5 .mu.m,
heating the first coating by a flash heating in such a way that it
is heated to a temperature ranging from 0.8 T.sub.f to T.sub.f,
producing a second metal or metal alloy coating with a thickness
equal to or less than 1 .mu.m. The device for carrying out said
method and the thus coated metallic material are also
disclosed.
Inventors: |
Choquet; Patrick; (Longville
Les Metz, FR) ; Chaleix; Daniel; (Verny, FR) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Family ID: |
30129694 |
Appl. No.: |
10/522688 |
Filed: |
August 4, 2003 |
PCT Filed: |
August 4, 2003 |
PCT NO: |
PCT/FR03/02457 |
371 Date: |
August 4, 2005 |
Current U.S.
Class: |
148/525 ;
148/526 |
Current CPC
Class: |
C23C 2/26 20130101; C23C
28/322 20130101; C23C 28/3455 20130101; C23C 28/321 20130101; C23C
28/345 20130101 |
Class at
Publication: |
148/525 ;
148/526 |
International
Class: |
C21D 1/09 20060101
C21D001/09 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 5, 2002 |
FR |
02/09952 |
Claims
1. Method for coating the surface of a metal material having a
crystallographic structure, according to which the material is
first coated with a layer of a metal or a metal alloy having a
melting point equal to T.sub.f and a thickness less than or equal
to 2.5 .mu.m, characterised in that: the first coating is subjected
to thermal processing using a rapid heating means in order to bring
the surface of the first coating to a temperature of between 0.8
T.sub.f and T.sub.f; a second coating is deposited from a metal or
a metal alloy having a thickness less than or equal to 1 .mu.m.
2. Method according to claim 1, characterised in that the first and
second coatings have melting points less than or equal to
700.degree. C.
3. Method according to claim 1, characterised in that the first and
second coatings are constituted by the same material.
4. Method according to claim 1, characterised in that a transparent
mineral film is then deposited on the second coating.
5. Method according to claim 1, characterised in that the metal
material to be coated is a carbon steel.
6. Method according to claim 1, characterised in that the metal
material to be coated is a stainless steel.
7. Method according to claim 1, characterised in that the metal
material to be coated is aluminium or one of the alloys
thereof.
8. Method according to claim 1, characterised in that the first
coating is produced by means of electrodeposition.
9. Method according to claim 1, characterised in that the first
coating is produced by a physical vapour deposition method.
10. Method according to claim 1, characterised in that the means
for rapid heating is an infra-red heating device.
11. Method according to claim 1, characterised in that the means
for rapid heating is an induction heating device.
12. Method according to claim 1, characterised in that the means
for rapid heating is a device for discharge with plasma with a
non-reactive gas.
13. Method according to claim 1, characterised in that the means
for rapid heating is a device for ion bombardment with a
non-reactive gas.
14. Method according to claim 1, characterised in that the second
coating is produced by means of electrodeposition.
15. Method according to claim 1, characterised in that the second
coating is produced by means of a physical vapour deposition
method.
16. Method according to claim 4, characterised in that the
transparent mineral film is deposited by means of a reactive plasma
assisted chemical vapour deposition method.
17. Method according to claim 1, characterised in that the first
and/or second coating(s) is/are constituted by tin.
18. Method according to claim 1, characterised in that the first
and/or second coating(s) is/are constituted by aluminium.
19. Method according to claim 1, characterised in that the mineral
film is constituted by a metal oxide or a mixture of metal
oxides.
20. Method according to claim 19, characterised in that the metal
oxide(s) is/are selected from the oxides of austenitic stainless
steel, chromium, titanium, silicon, zinc, tin.
21. Method according to claim 1, characterised in that the metal
material is in the form of a moving strip, and in that the various
method steps are carried out continuously by means of installations
which are arranged successively over the path of the moving
strip.
22. Device for coating a metal material in the form of a strip,
characterised in that it comprises means for moving the strip and,
arranged successively over the path of the strip: first means for
coating the strip with a layer of a metal or a metal alloy having a
melting point equal to T.sub.f; means for rapidly heating the strip
which can bring the surface of the layer to a temperature of
between 0.8 T.sub.f and T.sub.f; and second means for coating the
strip with a layer of metal or metal alloy.
23. Device according to claim 22, characterised in that it
comprises, downstream of the second means for coating the strip
with a layer of a metal or a metal alloy, means for coating the
strip with a transparent mineral film.
24. Metal material, characterised in that it comprises, on at least
one of the surfaces thereof, a metal coating having a
three-dimensional visual effect, the coating being formed directly
on the surface of the material.
25. Metal material according to claim 24, characterised in that it
is produced using a method according to which the material is first
coated with a layer of a metal or a metal alloy having a melting
point equal to T.sub.f and a thickness less than or equal to 2.5
.mu.m, the first coating is subjected to thermal processing using a
rapid heating means in order to bring the surface of the first
coating to a temperature of between 0.8 T.sub.f and T.sub.f and a
second coating is deposited from a metal or a metal alloy having a
thickness less than or equal to 1 .mu.m.
Description
[0001] The invention relates to the coating of metal surfaces. More
precisely, it relates to processing operations for coating the
surface of a metal material intended to confer a three-dimensional
visual effect on the material.
[0002] A visual effect of this type can be achieved using holograms
which are produced by recording and reproducing an image by means
of two laser beams on a photosensitive medium which is capable of
recording highly contrasting luminous interferences. Media of this
type are, for example, thermoplastic films, photopolymers,
photosensitive films . . .
[0003] Up to the present time, in order to produce a
three-dimensional visual effect on a metal surface, no method has
been known other than to apply to the surface, by means of
adhesive-bonding or colamination, a photosensitive medium of the
type described above. The decoration of metal packagings of steel
or aluminium is a preferred use of this technique which has the
disadvantage for the metal company of requiring the involvement of
an external supplier to provide the photosensitive medium.
Furthermore, there is the risk of the medium becoming separated
from the packaging or damaged during processing and handling
operations to which the packaging is subjected following the
adhesive-bonding or colamination.
[0004] The object of the invention is to provide a method which
allows three-dimensional visual effects to be produced on the
surface of a metal material without a photosensitive medium having
to be applied to the surface.
[0005] To this end, the subject-matter of the invention is a method
for coating the surface of a metal material having a
crystallographic structure, according to which the material is
first coated with a layer of a metal or a metal alloy having a
melting point equal to T.sub.f and a thickness less than or equal
to 2.5 .mu.m, characterised in that:
[0006] the first coating is subjected to thermal processing using a
rapid heating means in order to bring the surface of the first
coating to a temperature of between 0.8 T.sub.f and T.sub.f;
[0007] a second coating is deposited from a metal or a metal alloy
having a thickness less than or equal to 1 .mu.m.
[0008] According to a variant of the method, the first and second
coatings have melting points less than or equal to 700.degree.
C.
[0009] The first and second coatings can be constituted by the same
material.
[0010] According to a variant of the method, a transparent mineral
film is then deposited on the second coating.
[0011] The metal material to be coated can preferably be a carbon
steel, a stainless steel, or aluminium or one of the alloys
thereof.
[0012] The first coating can preferably be produced by means of
electrodeposition or a physical vapour deposition method.
[0013] The rapid heating means can preferably be an infra-red
heating device, an induction heating device, a device for discharge
with plasma with a non-reactive gas or a device for ion bombardment
with a non-reactive gas.
[0014] The second coating can preferably be produced by means of
electrodeposition or a physical vapour deposition method.
[0015] The transparent mineral film can be deposited by means of a
reactive plasma assisted chemical vapour deposition method.
[0016] The first and second coatings can each be constituted by tin
and/or aluminium.
[0017] The mineral film can be constituted by a metal oxide or a
mixture of metal oxides, preferably selected from the oxides of
austenitic stainless steel, chromium, titanium, silicon, zinc,
tin.
[0018] The metal material can be in the form of a moving strip and
the various method steps can be carried out continuously by means
of installations which are arranged successively over the path of
the moving strip.
[0019] The invention also relates to a device for coating a metal
material in the form of a strip, characterised in that it comprises
means for moving the strip and, arranged successively over the path
of the strip:
[0020] first means for coating the strip with a layer of a metal or
a metal alloy having a melting point equal to T.sub.f;
[0021] means for rapidly heating the strip which can bring the
surface of the layer to a temperature of between 0.8 T.sub.f and
T.sub.f; and
[0022] second means for coating the strip with a layer of metal or
metal alloy.
[0023] The device can comprise, downstream of the second means for
coating the strip with a layer of a metal or a metal alloy, means
for coating the strip with a transparent mineral film.
[0024] The invention also relates to a metal material,
characterised in that it comprises, on at least one of the surfaces
thereof, a metal coating which has a three-dimensional visual
effect, the coating being formed directly on the surface of the
material, and which is carried out in particular by the above
method.
[0025] As will be appreciated, the invention consists in producing
the desired three-dimensional visual effect using a series of
operations for processing the surface of the metal material itself.
In this manner, a multilayered coating is produced which cannot be
separated from the metal material and which can be produced by the
metal company which made the base material. This coating, in
addition to the aesthetic qualities thereof, has a number of
technical advantages and allows the manufacturer of the metal
material to maintain complete control over the decoration
process.
[0026] The invention will be better understood from a reading of
the following description, given with reference to appended FIGS. 1
to 6 which illustrate the appearances of various coatings produced
by different variants of the method according to the invention.
[0027] The starting material is a metal material, such as a carbon
steel, a stainless steel, aluminium or one of the alloys thereof,
etcetera. It is, for example, in the form of a plate or a wound
strip. In this last case, it is possible to carry out the
processing operation which will be described by unwinding the strip
and moving it continuously in an installation where the equipment
which allows the various steps of the processing operation to be
carried out is arranged successively over the path of the strip. In
order to achieve the desired aesthetic effect, it is necessary for
the metal material used as a substrate to have a crystallographic
structure.
[0028] Before carrying out the depositing, the surface of the
material is conditioned in a manner known per se in order to remove
any superficial contamination.
[0029] The first method step is the depositing of a first coating,
constituted by a metal element (tin or aluminium, for example) or a
metal alloy, preferably having a low melting point T.sub.f in the
order of 700.degree. C. or less. This coating must have a thickness
less than or equal to 2.5 .mu.m.
[0030] Advantageously, it is produced by means of an
electrodeposition method or a physical vapour deposition method.
The physical vapour deposition methods which can be used include
conventionally known methods involving vacuum evaporation,
magnetron sputtering, ion plating, self-induced ion plating.
[0031] The second method step is a thermal processing operation
which is carried out on the first coating using a rapid heating
means, such as infra-red lamps, an inductor, a plasma discharge
operation, or ion bombardment with a non-reactive gas, such as an
inert gas. This thermal processing must bring the surface of the
first coating to a temperature of between 0.8 T.sub.f and T.sub.f.
So that it is effected with kinetics compatible with being carried
out on a strip moving at a speed in the order of 100 m/mn, it is
preferable for T.sub.f to be less than or equal to 700.degree.
C.
[0032] The third method step is the depositing of a second coating,
from a metal element or an alloy which may or may not be identical
to the material of the first coating. This coating must have a
thickness which does not exceed 1 .mu.m. It can be produced using
the same methods as the first coating.
[0033] Preferably (but not necessarily), the method can comprise a
fourth step which consists in depositing a transparent mineral film
on the second metal coating. Materials such as oxides of austenitic
stainless steel, chromium, titanium, silicon, zinc, tin
(non-limiting list) and the mixtures thereof are particularly
appropriate. This transparent mineral deposit can be carried out by
any known means for this purpose, the reactive plasma assisted
chemical vapour deposition methods being particularly appropriate.
If this film has a thickness less than or equal to 1 .mu.m, a
coloured coating can be produced by means of an interference effect
of the mineral film. The colours green, yellow, blue, violet and
red are accessible in this manner, in accordance with the
refraction index of the material deposited. Generally, this
transparent film gives an appearance of additional depth to
patterns having a three-dimensional appearance which are produced
following the first three method steps.
[0034] As mentioned, the appearance of patterns on the surface of
the substrate requires the substrate to have a crystallographic
structure. The nucleation of the solidification patterns of the
metal deposits is produced on the basis of preferential sites at
the surface of the substrate which exist only if the substrate has
a crystallographic structure.
[0035] The size of the patterns produced depends on the quantity of
energy used during the second method step and the thickness of the
coating: the patterns will be larger as this quantity of energy
and/or this thickness become(s) greater. The use of a metal or
alloy having a low melting point (700.degree. C. or less) as a
coating material during the first method step allows the
metallurgical conversion of the coating to be carried out in a very
short space of time during the second step. The methods of heating
which have been mentioned allow the necessary energy to be provided
in the shortest possible time.
[0036] Compared with producing three-dimensional visual effects
using photosensitive media applied to the metal product, the method
according to the invention has a number of advantages. As
mentioned, it allows the manufacturer of metal products to maintain
complete control over the method. Since the coating which produces
the three-dimensional visual effect is an integral part of the
medium in this case, there is no risk of it becoming separated
during subsequent processing and handling operations. Furthermore,
most particularly if the method is used in its entirety with four
steps, the coating produced in this manner increases the resistance
of the substrate to cosmetic corrosion. The coating also has a
higher resistance to ultra-violet radiation and temperature. It is
less sensitive to fingermarks. It has a high degree of superficial
hardness which makes it less sensitive to scratches. It is easy to
clean and effectively withstands maintenance products and other
mechanical influences. Finally, it is possible, if the coating
metal used is appropriate (for example, tin), to make the coating
compatible with use in the field of foodstuffs.
[0037] Various examples for carrying out the method according to
the invention will now be described. They are carried out on sheets
of soft steel of 200.times.200 mm and a thickness of 0.7 mm. These
sheets are degreased beforehand in conventional manner using damp
means (solvent agitated by ultrasound). They are then subjected to
an ion pickling operation starting from an argon plasma in a vacuum
reactor which is then used during the various steps for carrying
out the method according to the invention.
EXAMPLE 1
[0038] In the first method step according to the invention, the
sheet is coated with a layer of tin of 0.8 .mu.m by means of
magnetron sputtering in an atmosphere of argon at a pressure of
10.sup.-3 mbar (0.1 Pa). The target current is 0.9 A and the target
voltage is 450V. The rate at which the tin is deposited is 0.25
.mu.m/min.
[0039] In the second method step according to the invention, the
sheet is thermally processed using an argon plasma at a pressure of
10.sup.-3mbar (0.1 Pa). The energy conferred on the ions of argon
is 400 eV and the quantity of ions received by the sheet is
4.7.times.10.sup.22 ions Ar.sup.+/m.sup.2. The sheet is placed as a
cathode. The surface of the tin is brought to a temperature in the
order of 210.degree. C.
[0040] In the third step, a tin coating of 0.4 .mu.m is deposited
by means of magnetron sputtering, under the same experimental
conditions as for the first coating.
[0041] In the fourth step, a transparent film of silicon having a
thickness of 0.1 .mu.m is deposited by means of plasma CVD. The
depositing is carried out in an atmosphere composed of
hexamethyldisiloxane (HMDSO) and oxygen at a pressure of 10.sup.-3
mbar (0.1 Pa), with a ratio of partial pressures of HMDSO and
O.sub.2 of 1/10. A current is used having a frequency of 50 kHz at
a power of 100W. The depositing rate is 1.0 .mu.m/min.
[0042] Using this method, a coating is produced whose external
appearance is illustrated in FIG. 1, which coating has
anti-corrosion and anti-fingermarking properties, is easy to clean
and has a high degree of superficial hardness. It is capable of
withstanding significant mechanical, chemical and thermal
influences.
EXAMPLE 2
[0043] The sheet of steel is coated under conditions identical to
those of example 1 for the first three steps. The fourth step
consists in producing a coloured film of titanium dioxide by means
of reactive magnetron sputtering of a titanium target. The
thickness of the film is 0.05 .mu.m. The conditions under which it
is produced are an atmosphere O.sub.2/Ar with
P.sub.O2/P.sub.Ar=0.4, a total pressure of 5.10.sup.-3 mbar (10.5
Pa) and a power of 1.7 kW. In this manner, a coating is produced
which is illustrated in FIG. 2, having properties similar to those
of example 1, additionally with a blue appearance owing to the
refraction index of the titanium dioxide (2.5) and the properties
specific to titanium dioxide, that is to say, significant chemical
inertia, a high degree of stability at high temperature, effective
resistance to chemical influences and a self-cleaning action owing
to the catalytic effect thereof of degradation of the materials
containing carbon and oxygen in the presence of ultra-violet
light.
EXAMPLE 3
[0044] The sheet of soft steel is coated under the same conditions
as for example 2, with the exception that the thickness of the
first deposit of tin is increased to 1.2 .mu.m, and the quantity of
ions received by the first layer of tin during the second method
step is increased. In this case, this quantity reaches
9.4.times.10.sup.22 ions Ar.sup.+/m.sup.2. The surface of the tin
is brought to a temperature in the order of 235.degree. C. The
result can be seen in FIG. 3.
EXAMPLE 4
[0045] The sheet of soft steel is coated under the same conditions
as for example 2, with the exception that, as for example 3, the
quantity of ions received by the first layer is increased to
9.4.times.10.sup.22 ions Ar.sup.+/m.sup.2, and the thickness of the
titanium dioxide film is increased to 0.08 .mu.m. The result can be
seen in FIG. 4.
[0046] It should be noted that the increase in the energy used
during the second processing step leads to a significant increase
in the size of the patterns.
EXAMPLE 5
[0047] The sheet is coated under identical conditions to those of
example 1, with the exception that, for the second step, two
infra-red lamps are used to heat the substrate and the first layer
of tin thereof, and no oxide is deposited on the second layer of
tin. Only the first three method steps are therefore carried out,
those which are required to produce the desired three-dimensional
visual effect. The heating of the layer of tin is static and lasts
for 8 minutes in a lamp-type furnace controlled at a temperature of
200.degree. C. The result can be seen in FIG. 5.
EXAMPLE 6
[0048] A very thin sheet of soft steel of 200.times.200 mm and 0.2
mm thick is coated with an electrodeposited layer of tin in such a
manner as to produce a sheet of "tinplate" of the type
conventionally used in the field of foodstuffs. The second and
third method steps according to the invention are then carried out
under conditions identical to those of example 2. The fourth
optional processing step according to the invention is not carried
out. The result can be seen in FIG. 6.
EXAMPLE 7
[0049] In a first method step according to the invention, the sheet
is coated with a layer of aluminium of 0.6 .mu.m by means of
magnetron sputtering in an atmosphere of argon at a pressure of
10.sup.-3 mbar (0.1 Pa). The target current is 1.8 A and the target
voltage is 355V. The rate at which the aluminium is deposited is
0.33 .mu.m/min.
[0050] In the second method step according to the invention, the
sheet is thermally processed with an argon plasma at a pressure of
10.sup.-3 mbar (0.1 Pa). The energy conferred on the argon ions is
280 eV and the quantity of ions is 18.4.times.10.sup.22 ions
Ar.sup.+/m.sup.2. The sheet is placed as a cathode. The surface of
the sheet coated in aluminium is brought to a temperature of
615.degree. C. at the end of the processing operation.
[0051] In a third step, a coating of tin is deposited by means of
magnetron sputtering under the same experimental conditions as
those described in the third step of example 1.
[0052] Under these production conditions, a coating is produced
whose external appearance is identical to that of the example of
FIG. 1.
EXAMPLE 8
[0053] The sheet of soft steel is coated with tin under the same
conditions as for example 3 for the first two steps. In a third
step, an aluminium coating is deposited by means of magnetron
sputtering, under the same experimental conditions as those
described in the first step of example 7, with the exception that
the aluminium is deposited with a thickness of 0.4 .mu.m.
[0054] Under these production conditions, a coating is produced
whose external appearance is identical to that of the example of
FIG. 3.
[0055] The examples of materials which form the substrate and the
various layers which coat it, and the conditions under which they
are formed have been given in a non-limiting manner. The person
skilled in the art will be able to envisage variants in accordance
with the desired properties of the final product.
[0056] If the three-dimensional visual appearance is desired on
only one surface or portions of the surface of the metal material,
it is possible to protect the material using one or more covers
which mask the zones which are not to be coated during the various
processing operations to which they are subjected.
* * * * *