U.S. patent application number 10/680180 was filed with the patent office on 2004-04-08 for manufacturing process for a plated product comprising a support part in steel and an anticorrosion metallic coating.
This patent application is currently assigned to Le Carbone Lorraine. Invention is credited to Hug, Christian, Totino, Ernest.
Application Number | 20040065392 10/680180 |
Document ID | / |
Family ID | 8858097 |
Filed Date | 2004-04-08 |
United States Patent
Application |
20040065392 |
Kind Code |
A1 |
Totino, Ernest ; et
al. |
April 8, 2004 |
Manufacturing process for a plated product comprising a support
part in steel and an anticorrosion metallic coating
Abstract
The aim of the present invention is a process for manufacturing
a plated product (1) comprising a support part in steel (2) and an
anticorrosion metallic coating (3), characterized in that the
anticorrosion coating (3) is fixed on the support part (2) by
controlled-atmosphere brazing, in particular by vacuum brazing. The
process according to the invention makes it possible to fix solidly
an anticorrosion coating with a thickness smaller than 1 mm on a
steel plate.
Inventors: |
Totino, Ernest; (Ruffine,
FR) ; Hug, Christian; (Saint Paul, FR) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ LLP
SUITE 800
1990 M STREET NW
WASHINGTON
DC
20036-3425
US
|
Assignee: |
Le Carbone Lorraine
Courbevoie
FR
|
Family ID: |
8858097 |
Appl. No.: |
10/680180 |
Filed: |
October 8, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10680180 |
Oct 8, 2003 |
|
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|
10024009 |
Dec 21, 2001 |
|
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60261817 |
Jan 17, 2001 |
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Current U.S.
Class: |
148/528 ;
428/660 |
Current CPC
Class: |
Y10T 428/12806 20150115;
B23K 1/008 20130101 |
Class at
Publication: |
148/528 ;
428/660 |
International
Class: |
B32B 015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2000 |
FR |
00 16897 |
Claims
1. A process for manufacturing a plated product comprising a
support part in steel and an anticorrosion metallic coating, said
process comprising at least one brazing operation under controlled
atmosphere, utilizing at least one brazing material, in such a way
as to establish a mechanical bond between at least one defined part
of the support and at least one defined part of the coating.
2. The manufacturing process of claim 1, wherein the brazing
operation comprises bringing said defined parts closer together in
such a way as to obtain a space D less than 0.1 mm.
3. The manufacturing process of claim 1, wherein the brazing
operation is effected under vacuum.
4. The manufacturing process of claim 3, wherein the residual
pressure of said vacuum is less than 10.sup.-4 mbar.
5. The manufacturing process of claim 3, wherein said brazing
operation comprises: interposing at least one brazing material
between the steel support part and the anticorrosion coating, in
such a way as to form an initial assembly; optionally, applying a
plating pressure on said initial assembly; introducing the initial
assembly into a vacuum chamber provided with means of heating;
formation of a vacuum in said chamber; heating of said assembly up
to a temperature at least equal to the brazing temperature of said
brazing material.
6. The manufacturing process of claim 1, wherein the brazing
operation is effected under inert gas.
7. The manufacturing process of claim 6, wherein the inert gas is
selected from the group comprising rare gases, nitrogen and
mixtures thereof.
8. The manufacturing process of claim 6, wherein said brazing
operation comprises: interposing at least one brazing material
between the steel support part and the anticorrosion coating, in
such a way as to form an initial assembly; possibly, applying a
plating pressure on said initial assembly; introducing the initial
assembly into a controlled-atmosphere chamber provided with means
of heating; replacing the atmosphere in said chamber with an inert
gas; heating of said assembly up to a temperature at least equal to
the brazing temperature of said brazing material.
9. The manufacturing process of claim 1, further comprising at
least one treatment selected from the group comprising the chemical
treatments, the electrochemical treatments, the physico-chemical
treatments, the mechanical treatments and the combinations
thereof.
10. The manufacturing process of claim 1, further comprising
depositing at least one layer capable of improving the tying of the
brazing material.
11. The manufacturing process of claim 10, wherein said layer is
metallic.
12. The manufacturing process of claim 10, wherein said depositing
is effected by chemical means, electrolytic means or in vapor
phase.
13. The manufacturing process of claim 1, wherein the thickness of
said coating is less than 1 mm.
14. The manufacturing process of claim 1, wherein the thickness of
said coating is less than 0.5 mm.
15. The manufacturing process of claim 1, wherein said coating is
in tantalum or an alloy of tantalum.
16. The manufacturing process of claim 15, wherein the brazing
material is a material containing nickel and boron.
17. The manufacturing process of claim 15, wherein the brazing
material is a silver-based material containing lithium, copper,
aluminium, zinc and/or tin.
18. The manufacturing process of claim 1, wherein said coating is
in titanium or an alloy of titanium.
19. The manufacturing process of claim 18, wherein the brazing
material is an alloy with a titanium base.
20. The manufacturing process of claim 18, wherein the brazing
material is a silver-based material containing lithium, copper,
aluminium, zinc and/or tin.
21. The manufacturing process of claim 1, wherein said coating is
in zirconium or an alloy of zirconium.
22. The manufacturing process of claim 21, wherein the brazing
material is an alloy with a base of zirconium, copper or
nickel.
23. The manufacturing process of claim 21, wherein the brazing
material is a silver-based material containing lithium, copper,
aluminium, zinc and/or tin.
24. The manufacturing process of claim 1, wherein the brazing
material comes in the form of powder, a sheet or a mesh.
25. The manufacturing process of claim 1, wherein said steel is a
chromium steel.
26. The manufacturing process of claim 1, wherein the difference
between the thermal expansion coefficient of said steel and the
thermal expansion coefficient of said anticorrosion coating is less
than 20%.
27. The manufacturing process of claim 1, wherein said support part
comes in the form of a plate or sheet.
28. The manufacturing process of claim 1, wherein said coating
comes in the form of a plate or sheet.
29. The manufacturing process of any one of claims 1 to 28, wherein
said plated product is an assembly part or an element of a chemical
device.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to devices for the handling,
stocking and processing of chemical products intended for the
chemical industries. In particular it concerns mixers, processing
devices and routing devices capable of handling highly corrosive
products, such as concentrated acids or bases. In the present
application, the expression "elements of chemical devices" means in
particular, and in a collective manner, storage chambers, tanks,
heat exchangers, mixers, treatment devices and routing devices.
[0002] More specifically, the invention relates to a manufacturing
process for plated products comprising at least one support part in
steel and an anticorrosion metallic coating, such as elements of
chemical devices or assembly parts intended for manufacturing
elements of chemical devices.
STATE OF THE ART
[0003] The chemical industries use numerous elements of chemical
devices, which are needed for handling, stocking and/or processing
highly corrosive chemical products and which, consequently, have to
be capable of resisting any attack from the latter.
[0004] In order to guarantee high resistance to corrosion, the
elements of the chemical device usually comprise steel support
parts and a metallic anticorrosion coating with a base of so-called
"noble" metals, such as titanium, tantalum, zirconium, a
nickel-based alloy or stainless steel. The elements of the chemical
device can be manufactured by mounting assembly parts, such as
plates, previously coated with an anticorrosion metallic coating.
The anticorrosion coating can be fixed to the support part in
different ways, such as knurling, explosion cladding, hot rolling
or simple covering without any junction between the plate and the
anticorrosion coating.
[0005] Certain applications, such as devices with low internal
pressure, need a strong link between the steel support part and the
anticorrosion coating, that is to say a link with high resistance
to stripping, in order to avoid separation which could, for
example, lead to collapse of the anticorrosion coating. Knurling,
explosion cladding and hot rolling make it possible to obtain very
strong part/coating links, but these techniques can only be used
when the thickness of the anticorrosion coating is less than 0.7
mm.
[0006] The applicant therefore looked for a method applicable to
industrial development for fixing solidly a low thickness
anticorrosion coating on a support part in steel.
AIM OF THE INVENTION
[0007] The aim of the invention is a process for manufacturing a
plated product comprising a support part in steel and an
anticorrosion metallic coating, such as an element of a chemical
device or an assembly part intended to manufacture chemical device
elements, characterized in that the anticorrosion coating is fixed
on the support part by brazing under controlled atmosphere, such as
vacuum brazing or brazing under inert gas.
[0008] The applicant noted that the process according to the
invention made it possible to fix solidly on a metallic part in
steel an anticorrosion coating with a thickness less than 1 mm, or
even less than 0.5 mm, possibly smaller than or equal to 0.3
mm.
FIGURES
[0009] FIG. 1 shows diagrammatically a product plated according to
the invention.
[0010] FIG. 2 shows diagrammatically an embodiment of the process
according to the invention.
DESCRIPTION OF THE INVENTION
[0011] According to the invention, the process for manufacturing a
plated product 1 comprising a support part in steel 2 and an
anticorrosion metallic coating 3 is characterized in that it
comprises at least one controlled-atmosphere brazing operation,
using at least one brazing material 4, in such a way as to
establish a mechanical link between at least one defined part of
the support 2 and at least one defined part of the coating 3.
[0012] Said defined parts are called bonding surfaces. The link
between the support and the coating can be established by several
bonding surfaces. The bonding surface or surfaces are
advantageously pre-treated, before the brazing operation, in such a
way, in particular, so as to eliminate the surface oxides. For
example, one can carry out at least one treatment selected from the
chemical, the electrochemical, the physico-chemical and the
mechanical treatments (such as chemical pickling, electrochemical
pickling, machining or sanding). These treatments may be
combined.
[0013] In order to enhance the strength of the bonding the process
of the invention may also comprise depositing at least one layer
capable of improving the tying of the brazing material. The
deposition can be effected by chemical means, electrolytic means or
in vapor phase (chemical vapor deposition or physical vapor
deposition). Said layer is typically metallic, for example titanium
or copper. The deposition may be carried out on the support part 2,
the metallic coating 3 or both. The deposition is effected before
the brazing operation.
[0014] The brazing operation normally comprises bringing said
defined parts together in such a way as to obtain a spacing D which
is preferentially chosen so as to avoid the formation of gas
bubbles or bonding defects between the bonding surfaces during the
brazing operation. The spacing D is typically less than 0.1 mm. The
appropriate value of the spacing D can be obtained by applying a
plating pressure on the support and the coating.
[0015] The controlled atmosphere may be a vacuum (at least partial)
or an inert gas (such as a rare gas (typically argon or helium) or
nitrogen or a mixture thereof).
[0016] The brazing under controlled atmosphere is preferably vacuum
brazing. Preferably the vacuum is fairly high, that is to say that
the residual pressure in the chamber is less than 10.sup.-4 mbar,
and typically is comprised between 10.sup.-4 and 10.sup.-5 mbar.
This embodiment makes it possible to avoid contamination of the
elements of the assembly and/or possible pollution by the gas of
the controlled atmosphere (which may, for example, weaken the
metallic coating at the brazing temperature (typically by the
action of oxygen possibly contained in the industrial inert
gases)).
[0017] In the preferred embodiment of the invention, said
controlled-atmosphere brazing operation comprises:
[0018] interposing at least one brazing material 4 between the
steel support part 2 and the anticorrosion coating 3, in such a way
as to form an initial assembly 5;
[0019] possibly, applying a plating pressure on said initial
assembly 5;
[0020] introducing the initial assembly into a
controlled-atmosphere chamber, such as a vacuum chamber, 10
provided with means of heating 11 such as a resistance;
[0021] controlling the atmosphere in the chamber 10 (and thus in
proximity to said assembly), such as forming a vacuum in said
chamber or replacing the atmosphere in said chamber with an inert
gas;
[0022] heating of said assembly 5 up to a temperature at least
equal to the brazing temperature of said brazing material 4.
[0023] The brazing temperature, typically equal to the fusion
temperature of the brazing material, is such that the material
melts and produces an intimate bond with the element in contact
with it (steel support part and/or anticorrosion coating).
[0024] The brazing material is preferably spread uniformly between
the support part and the anticorrosion coating in order to obtain a
uniform bonding layer and to increase the contact surface between
these two elements.
[0025] Interposing the brazing material 4 between the support part
2 and the anticorrosion coating 3 can be carried out in two stages.
In particular, the interposing can comprise:
[0026] depositing the brazing material 4 on the support part 2, at
the location of the so-called "bonding" surface;
[0027] positioning of the anticorrosion coating 3 on the support
part 2, in such a way as to form said initial assembly 5.
[0028] In certain cases, it can be advantageous to first carry out
the deposit of the brazing material 4 on the anticorrosion coating
3, level with the so-called "bonding" surface, and then to position
the support part 2 on the anticorrosion coating, in such a way as
to form said initial assembly 5.
[0029] Advantageously one can apply a mechanical plating pressure
on said assembly before and/or during said re-heating. This plating
pressure is exercised so that the support part and the
anticorrosion coating are tightened against each other so as to
compress the brazing material.
[0030] Preferably, the anticorrosion metallic coating 3 is in
titanium, an alloy of titanium, tantalum, an alloy of tantalum,
zirconium or an alloy of zirconium.
[0031] The brazing material 4 can be a fusible alloy (typically an
eutectic alloy) or a fusible metal. Said material 4 can possibly
contain a flux. Advantageously the brazing material can diffuse in
the element with which it is in contact, which makes it possible to
ensure a very strong bonding between said elements. The brazing
material is typically in the form of a powder, a sheet or a mesh.
In its trials, the applicant noted that the mesh presented the
advantage of compensating efficiently for any possible variation in
spacing D between the bonding surfaces.
[0032] When the coating 3 is in tantalum or an alloy of tantalum,
the brazing material 4 is typically composed of nickel, chromium,
silicon or boron, or a mixture or an alloy thereof, such as an
alloy of the BNi type containing nickel and boron (according to
ASTM classification), such as Ni-14Cr-3B-4.5Si-4Fe,
Ni-7Cr-3B-4.5Si-3Fe or Ni-2B-3.5Si-1.5Fe. In these cases, the
brazing temperature is situated typically between 1000.degree. and
1050.degree. C. The brazing material 4 may also be a silver-based
material (such as an alloy or a mixture) containing lithium,
copper, aluminium, zinc and/or tin.
[0033] When the coating 3 is titanium or an alloy of titanium, the
brazing material 4 is typically a silver-based material (such as an
alloy or a mixture) containing lithium, copper, aluminium, zinc
and/or tin, or an alloy with a titanium base, such as TiNi, TiZrBe,
48Ti-48Zr-4Be or 43Ti-43Zr-12Ni-2Be.
[0034] When the coating 3 is zirconium or an alloy of zirconium,
the brazing material 4 is typically an alloy with a base of
zirconium, copper or nickel, such as Zr-5Be, Cu-20Pd-3In,
Ni-20Pd-10Si, Ni-30Ge-13Cr or Ni-6P. The brazing material 4 may
also be a silver-based material (such as an alloy or a mixture)
containing lithium, copper, aluminium, zinc and/or tin.
[0035] The steel support parts and the anticorrosion coatings can
take the form of plates. These elements, which can be cut out
beforehand, are typically flat, but they can also be rounded,
half-cylindrical or another shape. The elements can also be shaped
before being bonded by brazing. It is also possible to carry out a
brazing on a chemical device element using anticorrosion metallic
coatings with an appropriate shape.
[0036] The steel used is generally a carbon steel, and preferably a
chromium steel. It is particularly advantageous to use a steel
whose thermal expansion coefficient is close to that of the
anticorrosion coating, that is to say that, advantageously, the
difference between the thermal expansion coefficient of said steel
and the expansion coefficient of the anticorrosion coating is less
than 20% and preferably lower than 10%. More precisely, the thermal
expansion coefficient of said steel is equal to that of said
coating .+-.20% and preferably .+-.10%.
[0037] The support part 2 and/or the anticorrosion coating can be
presented in the form of a plate or sheet.
[0038] Said plated product 1 can be an assembly part or a chemical
device element.
EXAMPLES
Trials 1
[0039] Trials on manufacturing assembly parts were carried out by
vacuum brazing using plates in carbon steel and anticorrosion
coatings in tantalum. The brazing material was a BNi alloy of the
ASTM classification, with a nickel base and containing boron,
chromium and silicon.
[0040] The values of resistance to stripping observed during these
trials were between those obtained on assembly parts produced by
explosion cladding and those obtained on assembly parts produced by
knurling.
[0041] The applicant noted that the depth of diffusion of the
brazing material in the tantalum element was of the order of 10 to
20 .mu.m, such that the resistance to corrosion of the tantalum
coating was not affected by this diffusion.
[0042] Trials 2
[0043] Trials on manufacturing assembly parts were also carried out
by vacuum brazing using plates in carbon steel and anticorrosion
coatings in either tantalum or titanium. The brazing material had a
silver and copper base.
[0044] Bending and punching tests (with a curvature radius varying
between 30 mm and 100 mm) have shown no breaking or decoherence of
the brazing bond which exhibited a low relative hardness (110 Hv).
Moreover calendering of titanium plates (with dimensions 1
m.times.1 m) was done with a radius of curvature equal to 150 mm
without degrading the quality of the bond (even at a microscopic
scale).
[0045] The applicant further noticed that the diffusion depth of
the brazing material 4 in the anti-corrosion coating 3 was lower
than 60 .mu.m, so that the resistance to corrosion is not affected
by this diffusion.
Advantages of the Invention
[0046] The plated products obtained by the process of the invention
present the advantage of high transversal thermal conductivity
thanks to a close bonding between the support part and the
anticorrosion coating over the greater part of the bonding surface,
which is not the case, for example, with a bond obtained by
knurling which only produces bonding bands. Transversal thermal
conductivity is particularly advantageous in chemical devices
comprising means of thermal transfer such as an exchanger or a
double envelope for cooling or heating.
* * * * *