U.S. patent application number 16/992478 was filed with the patent office on 2020-11-26 for method of no-bath plasma electrolytic oxidation and device for implementing the same.
This patent application is currently assigned to ARIEL SCIENTIFIC INNOVATIONS LTD.. The applicant listed for this patent is ARIEL SCIENTIFIC INNOVATIONS LTD.. Invention is credited to Konstantin BORODIANSKIY, Alexey KOSSENKO, Alexander KRASNOPOLSKY, Aleksandr SOBOLEV, Michael ZINIGRAD.
Application Number | 20200370194 16/992478 |
Document ID | / |
Family ID | 1000005075185 |
Filed Date | 2020-11-26 |
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United States Patent
Application |
20200370194 |
Kind Code |
A1 |
ZINIGRAD; Michael ; et
al. |
November 26, 2020 |
METHOD OF NO-BATH PLASMA ELECTROLYTIC OXIDATION AND DEVICE FOR
IMPLEMENTING THE SAME
Abstract
An applicator for no-bath plasma gel electrolytic oxidation of a
workpiece made of a valve metal or an alloy thereof; the applicator
movable over a surface of a workpiece to be treated. The applicator
including an electrode connectable to a power supply and configured
for applying electric voltage to a gap between the electrode and a
workpiece. A gel electrolytic medium body is mounted in a holder
being in an electric contact with the electrode.
Inventors: |
ZINIGRAD; Michael; (Ramat
Gan, IL) ; KRASNOPOLSKY; Alexander; (Petach Tikvah,
IL) ; BORODIANSKIY; Konstantin; (Petach Tikvah,
IL) ; SOBOLEV; Aleksandr; (Ariel, IL) ;
KOSSENKO; Alexey; (Ashdod, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ARIEL SCIENTIFIC INNOVATIONS LTD. |
Ariel |
|
IL |
|
|
Assignee: |
ARIEL SCIENTIFIC INNOVATIONS
LTD.
Ariel
IL
|
Family ID: |
1000005075185 |
Appl. No.: |
16/992478 |
Filed: |
August 13, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/IL2019/050165 |
Feb 12, 2019 |
|
|
|
16992478 |
|
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62629719 |
Feb 13, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C25D 11/005 20130101;
C25D 21/02 20130101; C25D 17/06 20130101; C25D 17/10 20130101; C25D
21/12 20130101 |
International
Class: |
C25D 11/00 20060101
C25D011/00; C25D 17/10 20060101 C25D017/10; C25D 21/12 20060101
C25D021/12; C25D 21/02 20060101 C25D021/02; C25D 17/06 20060101
C25D017/06 |
Claims
1. A method of no-bath plasma electrolytic oxidation of a workpiece
made of a valve metal or an alloy thereof; the method comprising:
deploying a workpiece to form a first electrode; providing an
applicator of a gel electrolyte medium body to form a second
electrode; said applicator comprising a receptacle of a member,
made of said gel electrolyte medium body, facing said workpiece;
mounting said gel electrolyte medium body within a holder; applying
a voltage between said first electrode and said second electrode;
contacting said gel electrolyte medium body to said workpiece.
2. The method according to claim 1, wherein said gel electrolyte
medium body comprises a component selected from the group
consisting of an acidic component, an alkaline component, a current
amplifier component, a component improving thermal and electric
conductivity, water and any combination thereof.
3. The method according to claim 2, wherein said alkaline component
is potassium hydroxide, a gel forming component.
4. The method according to claim 2, wherein said current amplifier
component is sodium silicate.
5. The method according to claim 2, wherein said gel electrolyte
medium body comprises a gel forming component that is
agar-agar.
6. The method according to claim 2, wherein gel electrolyte medium
body comprises a gel forming component that is kappa
carrageenan.
7. The method according to claim 2, wherein said component
improving thermal and electric conductivity is selected from the
group consisting of carbon nanoparticles, carbon nanotubes, metal
particles and any combination thereof.
8. The method according to claim 1, wherein said second electrode
comprises a passage conducting a coolant circulating
therewithin.
9. An applicator for no-bath plasma gel electrolytic oxidation of a
workpiece made of a valve metal or an alloy thereof; the applicator
movable over a surface of a workpiece to be treated; the applicator
comprising: an electrode connectable to a power supply and
configured for applying electric voltage to a gap between said
electrode and a workpiece; a gel electrolytic medium body mounted
in a holder being in an electric contact with said electrode.
10. The applicator according to claim 9, wherein said gel
electrolyte medium body comprises a component selected from the
group consisting of an acidic component, an alkaline component, a
current amplifier component, a component improving thermal and
electric conductivity, water and any combination thereof.
11. The applicator according to claim 10 wherein said alkaline
component is potassium hydroxide, a gel forming component.
12. The applicator according to claim 10, wherein said current
amplifier component is sodium silicate.
13. The applicator according to claim 10, wherein said gel
electrolyte medium body comprises a gel forming component that is
agar-agar.
14. The applicator according to claim 10, wherein said gel
electrolyte medium body comprises a gel forming component that is
kappa carrageenan.
15. The applicator according to claim 10, wherein said component
improving thermal and electric conductivity is selected from the
group consisting of carbon nanoparticles, carbon nanotubes, metal
particles and any combination thereof.
16. The applicator according to claim 9, wherein said electrode
comprises a passage conducting a coolant circulating therewithin.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part application of
international application PCT/IL2019/050165 filed on Feb. 12, 2019,
which claims priority from U.S. provisional application 62/629,719,
filed on Feb. 13, 2018, the contents of each of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] This invention relates to surface treatment of workpieces
made of valve metals and alloys thereof by means of
plasma-electrolytic oxidation and, more specifically, to local
plasma-electrolytic oxidation of outsized workpieces out of an
electrolytic bath.
Background Information
[0003] Plasma electrolytic oxidation (PEO) is also known as
micro-arc oxidation and spark anodizing is often regarded as a
version of anodizing of valve metals (Mg, Al, Ti, and several
others) and their alloys. Indeed, the essence of both anodizing and
PEO is the production of oxide layers on a metal surface by the
action of electricity in a convenient electrolyte. An oxide layer
has a complex composition and includes various oxides of a base
metal, alloy additives and species coming from the electrolyte. The
part to be coated is immersed in a bath of electrolyte which
usually constitutes a dilute alkaline such as KOH. The part to be
coated is electrically connected and becomes one of the electrodes
in the electrochemical cell, while the "counter-electrode" is
typically made from an inert material such as stainless steel, and
embodied as a wall of a electrolytic bath. Voltage over 200 V is
applied between these two electrodes. Both direct and alternative
potentials are applicable.
[0004] US Patent Application Publication No. 2012/031765, the
entire contents of which are incorporated herein by reference,
discloses a process for the corrosion protection of metals such as
magnesium, aluminium or titanium, where at least two steps are
used, including both plasma electrolytic oxidation and chemical
passivation. The combination of these two processing steps enhances
the corrosion resistance performance of the surface beyond the
capability of either of the steps in isolation, providing a more
robust protection system. This process may be used as a corrosion
protective coating in its own right, or as a protection-enhancing
pre-treatment for top-coats such as powder coat or e-coat. When
used without an additional top-coat, the treated parts can still
retain electrical continuity with and adjoining metal parts.
Advantages include reduced cost and higher productivity than
traditional plasma-electrolytic oxidation systems, improved
corrosion protection, greater coating robustness and electrical
continuity.
[0005] U.S. Pat. No. 6,585,875, the entire contents of which are
incorporated herein by reference, discloses a process for treating
an electrically conducting surface by arranging for the surface to
form the cathode of an electrolytic cell in which the anode is
maintained at a DC voltage in excess of 30V and an electrical arc
discharge (electro-plasma) is established at the surface of the
workpiece by suitable adjustment of the operating parameters,
wherein the working gap between the anode and the cathode is filled
with an electrically conductive medium consisting of a foam
comprising a gas/vapor phase and a liquid phase. The process can be
adapted for simultaneously coating the metal surface by including
ions of the species required to form the coating in the
electrically conductive medium. Apparatus for carrying out the
process is also disclosed and, in particular, an anode assembly
which comprises a perforated anode plate which is in communication
with a chamber adapted to receive a flow of a liquid electrolyte,
means to supply the liquid electrolyte to the chamber, and means to
convert the liquid electrolyte received in the chamber into a
foam.
[0006] Valve metals and alloys thereof are much used as structural
materials in outsized or non-detachable article of vehicles,
machinery and immovable facilities which cannot be placed into
workshop environment. Hence, there is a long-felt and unmet need
for protecting newly made outsized workpieces of valve metals and
their alloys and repairing similar article having corrosion wear
under field conditions.
SUMMARY OF THE INVENTION
[0007] It is hence one object of the invention to disclose a method
of no-bath plasma electrolytic oxidation of a workpiece made of a
valve metal or an alloy thereof. The aforesaid method includes the
processes of: (a) deploying the workpiece to form a first
electrode; (b) providing an applicator of an electrolyte medium to
form a second electrode; (c) forming a working gap between the
first and second electrodes; (d) applying a voltage between the
first and second electrodes; (e) delivering the electrolyte medium
into the working gap between the first and second electrodes.
[0008] It is a core purpose of the invention to provide the
electrolyte medium selected from the group consisting of a foam
electrolyte medium, a gel electrolyte medium, a pasteous
electrolyte medium and any combination thereof.
[0009] Another object of the invention is to disclose the
electrolyte medium including an acidic component.
[0010] A further object of the invention is to disclose the
electrolyte medium including an alkaline component.
[0011] A further object of the invention is to disclose the
alkaline component which is potassium hydroxide.
[0012] A further object of the invention is to disclose the
electrolyte medium including a current amplifier component.
[0013] A further object of the invention is to disclose the current
amplifier component which is sodium silicate.
[0014] A further object of the invention is to disclose the foam
electrolyte medium including a viscosity and dispersion amplifier
component.
[0015] A further object of the invention is to disclose the
viscosity and dispersion amplifier component which is glycerin.
[0016] A further object of the invention is to disclose the foam
electrolyte medium including a surfactant agent. A further object
of the invention is to disclose the surfactant agent which is
Triton-X100.
[0017] A further object of the invention is to disclose the foam
electrolyte medium includes air.
[0018] A further object of the invention is to disclose the gel
electrolyte medium including a gel forming component.
[0019] A further object of the invention is to disclose the gel
forming component which is agar-agar.
[0020] A further object of the invention is to disclose the gel
forming component which is kappa carrageenan.
[0021] A further object of the invention is to disclose the
component improving thermal and electric conductivity selected from
the group consisting of carbon nanoparticles, carbon nanotubes,
metal particles and any combination thereof.
[0022] A further object of the invention is to disclose the second
electrode including a passage conducting a coolant circulating
therewithin.
[0023] A further object of the invention is to disclose the gel
forming component which is kappa carrageenan.
[0024] A further object of the invention is to disclose the gel
electrolyte medium including water.
[0025] A further object of the invention is to disclose the
pasteous electrolyte medium including thickening agent.
[0026] A further object of the invention is to disclose the
thickening agent which is carboxymethyl cellulose.
[0027] A further object of the invention is to disclose the
pasteous electrolyte medium including water.
[0028] A further object of the invention is to disclose the step of
delivering the electrolyte medium into the working gap including a
step of generating a foam electrolyte medium.
[0029] A further object of the invention is to disclose the method
including a step of draining a used foam electrolyte medium out of
the working gap.
[0030] A further object of the invention is to disclose the step of
delivering the electrolyte medium into the working gap performed in
a close-loop manner.
[0031] A further object of the invention is to disclose the step of
delivering the electrolyte medium into the working gap comprising a
step of placing a gel electrolyte medium body within the working
gap between the first and second electrodes.
[0032] A further object of the invention is to disclose the step of
delivering the electrolyte medium into the working gap including
spreading the pasteous electrolyte medium over a surface of the
workpiece to be treated.
[0033] A further object of the invention is to disclose a foam
electrolyte medium for no-bath plasma electrolytic oxidation of a
workpiece made of a valve metal or an alloy thereof. The aforesaid
foam electrolyte medium includes: (a) an acidic component; (b) a
current amplifier component; (c) a viscosity and dispersion
amplifier component; (d) a surfactant agent; and (e) air.
[0034] A further object of the invention is to disclose the foam
electrolyte medium for no-bath plasma electrolytic oxidation of a
workpiece made of an alloy metal or a valve thereof, the foam
electrolyte medium including: (a) an alkaline component; (b) a
current amplifier component; (c) a viscosity and dispersion
amplifier component; (d) a surfactant agent; and (e) air.
[0035] A further object of the invention is to disclose a gel
electrolyte medium for no-bath plasma electrolytic oxidation of a
workpiece made of an alloy metal or a valve thereof. The aforesaid
foam electrolyte medium includes: (a) an acidic component; (b) a
current amplifier component; (c) a gel forming component; and (d)
water.
[0036] A further object of the invention is to disclose a gel
electrolyte medium for no-bath plasma electrolytic oxidation of a
workpiece made of an alloy metal or a valve thereof. The aforesaid
foam electrolyte medium includes: (a) an acidic component, (b) an
alkaline component, (c) a current amplifier component, (c) a
component improving thermal and electric conductivity and (d)
water.
[0037] A further object of the invention is to disclose a pasteous
electrolyte medium for no-bath plasma electrolytic oxidation of a
workpiece made of a valve metal or an alloy thereof. The aforesaid
foam electrolyte medium includes: (a) an acidic component; (b) a
current amplifier component; (c) a thickening agent; and (d)
water.
[0038] A further object of the invention is to disclose a pasteous
electrolyte medium for no-bath plasma electrolytic oxidation of a
workpiece made of an alloy metal or a valve thereof. The aforesaid
foam electrolyte medium includes: (a) an alkaline component; (b) a
current amplifier component; (c) a thickening agent; and (d)
water.
[0039] A further object of the invention is to disclose an
applicator for no-bath plasma electrolytic oxidation of a workpiece
made of a valve metal or a valve thereof. The aforesaid applicator
is movable over a surface of a workpiece to be treated. The
applicator includes: (a) an electrode connectable to a power supply
and configured for applying electric voltage to a gap between the
electrode and the workpiece; and (b) electrolyte delivering
means;
[0040] It is another core purpose of the invention to provide the
electrolyte delivering means selected from the group consisting of:
a generator of a foam electrolyte medium; a holder of a gel
electrolyte medium, a dispenser of a pasteous electrolyte medium
and any combination thereof.
[0041] A further object of the invention is to disclose the
applicator including a drain pump configured for draining a used
foam electrolyte medium out of the working gap.
[0042] A further object of the invention is to disclose the
applicator including a working chamber attachable to the surface of
the workpiece and accommodating the foam electrolyte medium being
in an electric field created between the electrode and the
workpiece.
[0043] A further object of the invention is to disclose the foam
electrolyte medium generated by the generator and circulating via
the working chamber in a close-loop manner.
[0044] A further object of the invention is to disclose the
applicator including a holder configured for holding a gel
electrolyte body made of the gel electrolyte medium such that the
gel electrolyte medium body is positioned within the working gap
between the first and second electrodes.
[0045] A further object of the invention is to disclose the
applicator including a dispenser configured for spreading the
pasteous electrolyte medium over a surface of the workpiece to be
treated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] In order to understand the invention and to see how it may
be implemented in practice, a plurality of embodiments is adapted
to now be described, by way of non-limiting example only, with
reference to the accompanying drawings, in which
[0047] FIG. 1 is a flowchart of a method of no-bath plasma
electrolytic oxidation of a workpiece made of a valve metal or an
alloy thereof;
[0048] FIG. 2 is a general schematic diagram of an applicator for
no-bath foam plasma electrolytic oxidation;
[0049] FIG. 3 is a schematic cross-sectional view of an applicator
for no-bath foam plasma electrolytic oxidation;
[0050] FIGS. 4a and 4b are schematic cross-sectional views of an
applicator for no-bath gel plasma electrolytic oxidation; and
[0051] FIG. 5 is a schematic cross-sectional view of an applicator
for no-bath pasteous plasma electrolytic oxidation.
DETAILED DESCRIPTION OF THE INVENTION
[0052] The following description is provided, so as to enable any
person skilled in the art to make use of the invention and sets
forth the best modes contemplated by the inventor of carrying out
this invention. Various modifications, however, are adapted to
remain apparent to those skilled in the art, since the generic
principles of the present invention have been defined specifically
to provide a method of no-bath plasma electrolytic oxidation of a
workpiece made of a valve metal or an alloy thereof. Electrolytes
and applicators for implementing the aforesaid method are also
disclosed.
[0053] Reference is now made to FIG. 1 showing a method 100 of
no-bath plasma electrolytic oxidation. Method 100 is directed to
protection workpieces made of valve metals or their alloys. Method
100 is specifically applicable to outsized workpieces or
non-detachable structural workpieces of vehicles, machinery and
immovable facilities which cannot be placed into workshop
environment. In accordance with the present invention, method 100
begins with step 110 of deploying a workpiece to form a first
electrode. Specifically, the workpiece is electrically connected to
a first terminal of a power supply. It should be emphasized that no
need for placing the workpiece into an electrolytic bath. An
applicator provided at step 120 has a second electrode connected to
a second terminal of the power supply. In alignment with an
electrolyte type, as any direct-current polarity of the first and
second electrodes and alternative current are in the scope of the
present invention. The first and the second electrodes are
positioned at a predetermined distance such that a working gap
therebetween is formed (step 130). A voltage between the first and
the second electrodes is applied at step 140. In order to start the
plasma electrolytic oxidation process per se, electrolytic medium
is delivered into the working gap at step 150. The aforesaid
electrolytic medium can alternatively include acidic or alkaline
components. In addition, the electrolytic medium includes a current
amplifier component such as sodium silicate and a
viscosity-and-dispersion-amplifier component such as glycerin.
[0054] According to the first alternative embodiment of the present
invention, a foam electrolytic medium is delivered at step 151. In
addition to the common components (acidic or alkaline component,
current amplifier component and viscosity-and-dispersion-amplifier
component), the foam electrolytic medium includes a surfactant such
as Triton-X100 and air.
[0055] According to the second alternative embodiment of the
present invention, a gel electrolytic medium is delivered at step
152. Similar to the foam electrolytic medium, in addition to the
common components, the gel electrolytic medium includes a gel
forming component such as agar-agar or kappa carrageenan and water.
Adding a component improving thermal and electric conductivity such
as carbon nanoparticles, carbon nanotubes or metal particles are
also in the scope of the present invention.
[0056] According to the third alternative embodiment of the present
invention, a pasteous electrolytic medium is delivered at step 153.
In addition to the common components, the pasteous electrolytic
medium includes a thickening component such as Carboxymethyl
cellulose and water.
[0057] The specific choice of the electrolyte components depends on
the following parameters the plasma electrolytic oxidation: current
and voltage provided by a power supply, thickness of the oxide
coating to be obtained and characteristics of the obtained oxide
coating.
[0058] Reference is now made to FIG. 2 presenting a general
schematic diagram of applicator 200 for no-bath foam plasma
electrolytic oxidation. Applicator 200 includes housing 205 having
cavity (receptacle) 207 configured for accommodating (holding) an
electrolytic medium (not shown) applicable to workpiece 209 to be
coated. Power supply 230 controlled by control unit 231 provides
difference of electric potentials between the aforesaid article and
electrolytic medium. According to the present invention, a foam, a
gel and a paste are usable as alternative electrolytic media.
[0059] Numerals 250 and 255 refer to a foam generator and a lockup
valve which are optional components of applicator 200 when foam
electrolytic medium is used.
[0060] Reference is now made to FIG. 3 presenting applicator 200a
which is configured for no-bath plasma electrolytic oxidation with
a foam electrolytic medium. Applicator 200a includes housing 210
having cavity 240 accommodating the foam electrolytic medium, which
is fed by foam generator 250 into cavity 240 via pipe 253 and
hollow electrode 220. It should be mentioned that in the current
and further embodiments, the housing is made of an electrical
insulating material. The electrostatic field is created between
hollow electrode 220 (first electrode) and workpiece 260 (second
electrode) which are electrically connected to supply 230 by wires
233 and 235. Spent foam electrolytic medium is withdrawn from
cavity 240 via passage 245 and pipe 255. According to one
embodiment of the present invention, applicator 200a includes a
drain pump (not shown) for withdrawing the foam electrolytic medium
in a forced manner.
[0061] Reference is now made to FIGS. 4a and 4b showing applicator
200b which is configured for no-bath plasma electrolytic oxidation
with a gel electrolytic medium. Applicator 200b includes housing
310 having receptacle 340 configured for holding gel electrolytic
medium body 330. The aforesaid body 330 is in an electric contact
with electrode 320. According to one embodiment of the present
invention, housing 310 has a passage (not shown) conducting a
coolant circulating in the aforesaid passage. Terminals of power
supply 320 are connected to electrode 320 and workpiece 350 by
wires 233 and 235, respectively. It should be emphasized that
sufficient elasticity of gel electrolytic medium body 330 enables
treating any irregular surfaces having convex and concave elements
shown in FIGS. 4a and 4b, respectively. Any geometry of the surface
to be treated (including a flat surface) is in the scope of the
present invention.
[0062] Reference is now made to FIG. 5 illustrating applicator 200c
which is configured for no-bath plasma electrolytic oxidation with
a pasteous electrolytic medium. Applicator 200c comprises housing
410 provided with electrode 420. Numeral 440 refers to a pasteous
electrolytic medium which is a gap between aforesaid electrode 420
and workpiece 450 connected to power supply 230 by wires 233 and
235, respectively. Electrode 420 is placed within recess 430 to
define a minimal gap between electrode 420 and workpiece 450 and
prevent them from a shortcut.
[0063] Contrary to electrolytic bath technology where the workpiece
is immersed within the electrolyte, in present invention, the
applicator is moved over a surface of the workpiece in order to
treat different areas of the workpiece surface.
[0064] It will be appreciated by those skilled in the art that
changes could be made to the embodiments described above without
departing from the broad inventive concept thereof. It is
understood, therefore, that this invention is not limited to the
particular embodiments disclosed, but it is intended to cover
modifications within the spirit and scope of the present invention
as defined by the appended claims.
* * * * *