U.S. patent application number 14/496533 was filed with the patent office on 2015-01-08 for methods for the implementation of nanocrystalline and amorphous metals and alloys as coatings.
This patent application is currently assigned to Xtalic Corporation. The applicant listed for this patent is Xtalic Corporation. Invention is credited to Alan C. Lund, Christopher A. Schuh.
Application Number | 20150008135 14/496533 |
Document ID | / |
Family ID | 38712319 |
Filed Date | 2015-01-08 |
United States Patent
Application |
20150008135 |
Kind Code |
A1 |
Schuh; Christopher A. ; et
al. |
January 8, 2015 |
METHODS FOR THE IMPLEMENTATION OF NANOCRYSTALLINE AND AMORPHOUS
METALS AND ALLOYS AS COATINGS
Abstract
Methods for the use of nanocrystalline or amorphous metals or
alloys as coatings with industrial processes are provided. Three,
specific, such methods have been detailed. One of the preferred
embodiments provides a method for the high volume electrodeposition
of many components with a nanocrystalline or amorphous metal or
alloy, and the components produced thereby. Another preferred
embodiment provides a method for application of a nanocrystalline
or amorphous coatings in a continuous electrodeposition process and
the product produced thereby. Another of the preferred embodiments
of the present invention provides a method for reworking and/or
rebuilding components and the components produced thereby.
Inventors: |
Schuh; Christopher A.;
(Wayland, MA) ; Lund; Alan C.; (Ashland,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Xtalic Corporation |
Marlborough |
MA |
US |
|
|
Assignee: |
Xtalic Corporation
Marlborough
MA
|
Family ID: |
38712319 |
Appl. No.: |
14/496533 |
Filed: |
September 25, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13959291 |
Aug 5, 2013 |
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14496533 |
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11844238 |
Aug 23, 2007 |
8500986 |
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13959291 |
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11383969 |
May 18, 2006 |
7521128 |
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11844238 |
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Current U.S.
Class: |
205/145 |
Current CPC
Class: |
Y10T 428/12174 20150115;
C25D 7/06 20130101; C25D 3/56 20130101; Y10T 428/31504 20150401;
Y10T 428/1216 20150115; C25D 5/04 20130101; C25D 7/0614 20130101;
Y10T 428/12014 20150115; C25D 3/562 20130101; C25D 5/18 20130101;
C25D 7/0607 20130101; Y10T 428/25 20150115 |
Class at
Publication: |
205/145 |
International
Class: |
C25D 5/04 20060101
C25D005/04; C25D 7/06 20060101 C25D007/06; C25D 3/56 20060101
C25D003/56 |
Claims
1-20. (canceled)
21. A method of manufacturing a component strip, comprising:
applying a nanocrystalline or amorphous material coating to a
component strip, wherein the component strip includes a series of
components along a length of the strip, wherein the nanocrystalline
or amorphous material coating comprises a nickel-tungsten alloy,
wherein the nanocrystalline or amorphous material coating is
applied through an electrodeposition process, said
electrodeposition process comprised of a beginning portion of the
component strip entering an electrodeposition bath before an
adjoining portion of the component enters the electrodeposition
bath and the beginning portion of the component strip also exiting
the electrodeposition bath before the adjoining portion of the
component strip exits the electrodeposition bath.
22. The method according to claim 21, wherein the component strip
travels through the bath continuously.
23. The method according to claim 21, wherein the component strip
to be coated is fed from a reel.
24. The method according to claim 23, wherein the coated component
strip is collected on a reel.
25. The method according to claim 21, wherein the component strip
is an electrode in the electrodeposition process.
26. The method according to claim 21, wherein the component strip
is flexible.
27. The method according to claim 21, wherein the component strip
is a conductive material.
Description
FEDERALLY SPONSORED RESEARCH
[0001] N/A
BACKGROUND OF THE INVENTION
[0002] The present invention generally relates to methods for the
practical implementation of nanocrystalline or amorphous metals or
alloys as coating materials. More particularly, methods of applying
such nanocrystalline or amorphous metals or alloys to high volume
electrodeposition operations, to continuous electrodeposition
operations, and to the rebuilding and reworking of components are
presented.
[0003] Industrial applications, such as high-volume
electrodeposition production, barrel plating, continuous
electrodeposition, and rework/rebuild require coating materials
with specific properties. There is a continual need for new and
improved coating materials for these applications, which can offer
economic benefits or improved product properties.
High Volume Electrodeposition:
[0004] High volume electrodeposition coating processes, such as
barrel plating, are economically and practically desirable for
coating many components simultaneously. However, insufficient
coating properties create significant challenges for these high
volume electrodeposition coating processes.
[0005] High volume electrodeposition processes such as barrel
plating generally involve more than two components being plated
simultaneously, and which components may be in electrical contact
with one another during at least part of the process. The parts may
also experience contact mechanical loads and/or abrasive loading at
the electrical contact points. Such loading may be increased if the
components experience agitation during the process.
[0006] In design of high volume electrodeposition processes, an
important issue is the character and properties of the deposited
coating. In general, a weak or poorly adhered coating may be
damaged by the agitation process, as components shift their
relative positions and give rise to sliding contact points or local
impacts on the component surfaces. Similarly, soft and malleable
coatings, or those with low hardness, low resistance to wear,
indentation, or frictional sliding damage, may acquire defects such
as cracks, scratches or delaminations during the process. It is
therefore important that the deposited coating have desirable
properties that resist damage during processing, and that the
process characteristics be controlled to avoid such damage.
[0007] Another coating property of importance to the efficiency and
efficacy of a high volume electrodeposition process is its
electrical conductivity. Because the electrical connection of each
component to the power supply is achieved, in general, through
contacts between components or between components and the
electrical lead connected to the power supply, electrical current
is required to pass across the surfaces of the components. As the
deposition process proceeds and the components become coated,
electrical current is required to pass through the coating material
itself. If the coating is of low electrical conductivity, current
flow is discouraged, reducing the efficiency of the deposition. For
this reason, coatings of relatively higher electrical conductivity
are generally more appropriate to high volume electrodeposition
processes such as barrel plating.
[0008] An example relating to the electrical conductivity of
electrodeposited coatings is provided by the case of hexavalent
chromium deposits. Coatings of chromium produced by deposition from
the hexavalent bath are desirable in many respects, due to the high
hardness, wear resistance, and corrosion resistance of the coating.
However, the electrical conductivity of hexavalent chromium
coatings is low compared to many metals, and reduces the efficiency
of a high volume process such as barrel plating. This renders such
operations economically difficult to sustain.
[0009] A need has long existed for new electrodeposited coatings
which combine new suites of properties, to be produced in high
volume with such techniques. For example, it would be desirable to
use a high-strength, strong adhesion, abrasion resistant
nanocrystalline or amorphous coating with high electrical
conductivity, to improve both the quality of the coating and coated
product, as well as increase the efficiency of the process.
Additionally desired properties include higher hardness, ductility,
wear resistance, electrical properties, magnetic properties,
corrosion characteristics, substrate protection, improved
environmental impact, improved worker safety, improved cost, and
many others.
Continuous Electrodeposition:
[0010] Continuous electrodeposition processes are economically and
practically desirable for applying a coating onto a strip of
material. A need has long existed for coatings being applied using
continuous electrodeposition which create a final product with more
desirable properties. For example, higher hardness, strength,
ductility, wear resistance, electrical properties, magnetic
properties, corrosion characteristics, substrate protection,
improved environmental impact, improved worker safety, improved
cost, and many others.
Rework/Rebuild:
[0011] Rework/rebuild processes are economically and practically
desirable for correcting deficiencies in products. A critical step
in the rework/rebuild process is the application of a suitable
coating material. One common material used for this coating process
is hard electrodeposited chromium, alternatively called "hard
chromium" or "hard chrome". Rework/rebuild is a common procedure
for chromium plating facilities, in which hard chromium is the
material plated as a coating. Frequently, the chromium coating will
be up to or in excess of 375 .mu.m in thickness prior to the
machining step. K. O. Legg cites rework and rebuild operations as
comprising one of the largest single uses of hard chromium plating
in his article "Overview of Chromium and Cadmium Alternative
Technologies" (in Surface Modification Technologies XV, edited by
T. S. Sudarshan and M. Jeandin, ASM International, Materials Park
Ohio, 2002), which is fully incorporated herein by reference. A
drawback of hard chromium coatings for rework/rebuild operations is
the toxicity and carcinogenicity of the chemicals used in the
coating process; these have serious implications for the
environment and for worker safety.
[0012] Other coating technologies can be applied to rework
operations, including but not limited to other electroplated metal
technologies, electroless coatings, plasma or thermal spray
coatings, and physical vapor deposition coatings. These coating
technologies are generally more expensive than is hard chromium
coating, but can mitigate the negative environmental issues
associated with hard chromium. The main requirements for the
coating used in rework/rebuild operations are that it be deposited
to sufficient thickness, that it have the desired surface
properties (i.e., resistance to corrosion, abrasion, erosion, wear,
fatigue, etc.), that it adhere to the base material of the
substrate component, and that it can be machined by a suitable
method to exhibit the correct geometry.
[0013] Other factors may influence the choice of a coating
technology for use in rework/rebuild operations. For example, the
geometry of the component may preclude some coating technologies.
Plasma spray coatings are not generally useful for coating internal
diameters of bores or other re-entrant geometries, and so could not
be used for rework/rebuild except for regions of the component
material that may be connected by a line-of-sight to the spray
nozzle. Similarly, hard chromium plating is often said to be a "low
throwing-power" process, meaning that the process preferentially
deposits chromium on portions of the component closer to a
line-of-sight with a nearby plating anode. Many anodes are often
used in parallel to improve the density of "sight lines" to the
component and provide a uniform coating, but the coating of
recesses, internal surfaces, and re-entrant geometries is often
non-uniform. For these reasons, rework/rebuild operations on
complex surfaces are generally more challenging than those on
simpler geometries.
[0014] Accordingly, a need has long existed for coatings, coating
materials, and coating application processes to be used in
rework/rebuild operations that would provide the following: high
strength and hardness, high corrosion resistance, high wear and
abrasion resistance, thicknesses of at least 200 .mu.m, improved
environmental impact, improved worker safety, improved cost,
improved ability to coat geometries with internal surfaces and
non-line-of-sight surfaces, better compatibility or matching of the
substrate material to the rework/rebuild coating, improved surface
properties, the ability to withstand subsequent machining
operations, and the ability to utilize existing electroplating
equipment.
SUMMARY OF THE INVENTION
[0015] The present invention relates to methods for the use of
nanocrystalline or amorphous metals or alloys as coatings by
industrial processes. One of the preferred embodiments provides a
method for coating many components with a nanocrystalline or
amorphous metal or alloy, using a high volume electrodeposition
process such as barrel plating and the components produced thereby.
Another preferred embodiment provides a method for application of a
nanocrystalline or amorphous coating in a continuous
electrodeposition process and the product produced thereby. Another
of the preferred embodiments of the present invention provides a
method for reworking and/or rebuilding components and the
components produced thereby.
[0016] These and other features of the present invention are
discussed or apparent in the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 illustrates a front view of a high volume
electrodeposition apparatus suitable for the simultaneous coating
of many parts in a high volume process.
[0018] FIG. 2 illustrates a front view of an apparatus suitable for
the continuous electrodeposition of a coating.
[0019] FIG. 3 illustrates a side view of a worn component in need
of rework/rebuild.
[0020] FIG. 4 illustrates a side view of a component in need of
rework/rebuild after a coating has been applied.
[0021] FIG. 5 illustrates a side view of a component after
completion of rework/rebuild.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] Disclosed herein are methods for the implementation of
nanocrystalline and amorphous metals and alloys as coatings.
Specifically, three methods for implementation have been described:
the simultaneous coating of many parts in a high volume
electrodeposition process, the continuous electrodeposition of a
coating, and the rework/rebuild of a component using a coating.
[0023] Nanocrystalline metal refers to a metallic body in which the
number-average size of the crystalline grains is less than one
micrometer. The number-average size of the crystalline grains
provides equal statistical weight to each grain. The number-average
size of the crystalline grains is calculated as the sum of all
spherical equivalent grain diameters divided by the total number of
grains in a representative volume of the body. Amorphous metal
refers to a metallic body without long-range crystalline order,
i.e., a metallic body which is solid but not crystalline. A
metallic body which comprises regions of crystalline structure in
addition to the amorphous regions is additionally included in the
definition of an amorphous metal.
[0024] Nanocrystalline and amorphous metals and alloys are
generally regarded as advanced structural materials, because as a
materials class they tend to exhibit high strength, high abrasion
resistance, high hardness, and other desirable structural and
functional properties. Many technologies can be used to prepare
nanocrystalline or amorphous metals or alloys, including some which
naturally yield coatings. For example, electrodeposition processes
can be used to synthesize nanocrystalline or amorphous metal or
alloy coatings on electrically conductive surfaces. A coating
produced by electrodeposition may be made in nanocrystalline form
by many techniques, including addition of grain refining additives,
deposition of an alloy that takes a nanocrystalline form, use of
pulsed current, or use of reverse pulsed current. Recent
technologies around the use of electrodeposition allow for precise
control of the grain size in a nanocrystalline metal or alloy,
which is desirable to adjust coating properties to the needs of a
particular application.
[0025] Electrodeposition is commonly carried out in aqueous fluids,
but is not restricted to aqueous systems. For example, the
electrodeposition bath can comprise molten salts, cryogenic
solvents, alcohol baths, etc. Any type of electrodeposition bath
can be used in conjunction with the present inventions.
[0026] Electrodeposition involves the flow of electrical current
through the deposition bath, due to a difference in electrical
potential between two electrodes. One electrode is commonly the
component or part which is to be coated. The process may be
controlled by controlling the applied potential between the
electrodes (a process of potential control or voltage control), or
by controlling the current or current density that is allowed to
flow (current or current density control). The control of the
process may also involve variations, pulses, or oscillations of the
voltage, potential, current, and/or current density. The method of
control can also be a combination of several techniques during a
single process. For example, pulses of controlled voltage may be
alternated with pulses of controlled current or current density. In
general, during an electrodeposition process an electrical
potential exists on the component to be plated, and changes in
applied voltage, current, or current density result in changes to
the electrical potential on the component. Any such control methods
can be used in conjunction with the present inventions.
[0027] Nanocrystalline and amorphous metal or alloy coatings are
unique and offer desirable properties. The implementation of these
materials and coatings in practical applications requires relevant
methods of production for industrial applications. Thus, there is a
need for new applications of nanocrystalline or amorphous metal or
alloy coatings, especially those prepared by electrodeposition.
[0028] One specific method to control the grain size of
electrodeposited nanocrystalline metals or alloys was presented by
Detor and Schuh, in U.S. patent application Ser. Nos. 11/032,680
and 11/147,146, which are fully incorporated herein by reference.
This method consists of carefully controlling the composition of an
alloy deposit, which in turn allows for control of nanocrystalline
grain size. For example, in electroplated alloys of Ni--W, Ni--P,
and many others, there is a simple relationship between grain size
and composition. In these cases higher W or P contents are
correlated with finer nanocrystalline grain sizes. Control of the W
or P level therefore allows one to tailor the grain size in the
nanocrystalline range. Sufficiently high levels of W or P, in these
examples, can lead to amorphous structures. The method of Detor and
Schuh is to manipulate the electrodeposition process to control the
composition, and thereby control the grain size in the
nanocrystalline or amorphous deposit.
[0029] A specific application of the above method of Detor and
Schuh is based on reverse pulsed current during the process.
Reverse pulsing of the current allows control of the coating
composition, and thereby allows control of grain size. This reverse
pulse technique can produce coatings of tailorable grain size with
reduced macroscopic defects such as cracks or voids.
[0030] This reverse pulsing technique involves the introduction of
a bipolar wave current, with both positive and negative current
portions, during the electrodeposition process. Using this
technique provides the ability to adjust the composition of the
deposit, its grain size, or both within a relatively quick amount
of time, and without changing either the composition or temperature
of the electrodeposition bath liquid. Further, the technique
produces high quality homogeneous deposits with a lesser degree of
voids and cracks than is conventionally achieved. The technique
also enables grading and layering of nanocrystalline crystal size
and/or composition within a deposit. Additionally, the technique is
economical, scalable to industrial volumes, and robust.
[0031] It is possible to produce a variety of metals and alloys
with nanocrystalline or amorphous structures using
electrodeposition. For example, Ni--W alloys can be
electrodeposited. Nanocrystalline or amorphous metals and alloys
can be produced with a variety of different elemental compositions
in an electrodeposition process with a variety of average grain
sizes in the nanocrystalline range, and can be produced as an
amorphous metallic form as well. As well, many Ni-based alloys
including Ni--W, Ni--Mo, Ni--P, Ni--B, Ni--Fe, Ni--Co, Ni--S, and
others can be electrodeposited in nanocrystalline or amorphous
form. The inventions reported herein specifically apply to these
electrodeposited metals and alloys in nanocrystalline or amorphous
form, and to others as well. Co-based alloys such as Co--Mo, Co--W,
Co--P and others are also possible, as are iron, copper, tin,
cadmium, and zinc-based systems. Individuals skilled in the art
will recognize many other metals or alloys, both commercial and
experimental, which can be electrodeposited in nanocrystalline or
amorphous form. The present invention may be used with any such
existing metals or alloys, or new systems that may be developed in
the future.
[0032] The present inventions also apply to composite systems, in
which a nanocrystalline or amorphous metal or alloy is combined
with additional phases. For example, hard particulates of metal,
ceramic, intermetallic, or other material might be incorporated
into a nanocrystalline or amorphous metal or alloy. Other potential
phases which may be incorporated will also be recognized by those
skilled in the art, such as solid lubricant particles of graphite
or MoS.sub.2. Nanocrystalline and amorphous phases may also coexist
in a single electrodeposited coating, which represents another
composite structure which is a straightforward variation that may
be used in the present invention.
[0033] Nanocrystalline and amorphous metals and alloys can also
exhibit a wide range of properties, depending upon their
composition and structure. Of importance in this regard is a method
which allows the grain size to be tailored, allowing the coating
properties to be controlled in a manner that is desirable both for
the functionality of the final coating, and for optimization of a
high volume production process like barrel plating. For example,
high electrical conductivity is desirable in barrel plating or
other high volume electrodeposition processes, and by tailoring the
grain size of a nanocrystalline deposit the conductivity may be
increased to acceptable levels to permit efficient high volume
production.
[0034] A particular method of producing a nanocrystalline or
amorphous metal or alloy, and controlling and tailoring the grain
size in the coating, is the method outlined by Detor and Schuh
above. In this method the composition of the coating is tailored to
control the grain size of the nanocrystalline deposit. This may be
accomplished by many techniques, including, for example, the use of
periodic reverse pulses that tailor the composition and grain size
of the deposit.
[0035] Because electrodeposition processes can be adjusted to yield
nanocrystalline or amorphous metal or alloy coatings using
technologies such as those described above, there are potential
industrial applications that will benefit from the improved
properties of such coating materials.
High Volume Electrodeposition:
[0036] An invention disclosed herein is a method to simultaneously
coat many components using a high volume electrodeposition process,
using a nanocrystalline or amorphous metal or alloy coating. A
related invention is a component that has been coated with a
nanocrystalline or amorphous metal or alloy using a high volume
electrodeposition process.
[0037] One industrial coating process in use in the
electrodeposition or electroplating industry pertains to the rapid,
low-cost coating of many components simultaneously. FIG. 1
illustrates a front view of a high volume electrodeposition
apparatus 100 suitable for this simultaneous coating of many
components 102 in a high volume process. The high volume
electrodeposition apparatus 100 includes components 102, a
component vessel 104, an electrodeposition bath 106, a component
terminal 108, an electrical power supply 110, component electrical
lead 112, a counter terminal 114, a suitable counter electrode 116,
a counter electrical lead 118, a bath vessel 120, an oil bath 122,
an oil bath vessel 124, a thermal controller 126, a heater 128,
sensors 130, a composition adjustment module 132, a stirring
apparatus 134, a moving stirrer 136, an agitation motor 138, and an
agitation drive unit 140.
[0038] Such high volume electrodeposition operations are often
carried out in a so-called barrel plating operation, in which many
components 102 to be coated are placed into a component vessel 104,
which contains or is contained within an electrodeposition bath
106. Some or all of the components 102 in the component vessel 104
are in contact with the electrodeposition bath 106, and the
components 102 are all in electrical contact with one another in
the vessel. The components 102 are further electrically connected
to the component terminal 108 of an electrical power supply 110
through a component electrical lead 112, which is in contact with
one or more of the components 102, but not necessarily all of the
components 102.
[0039] The component electrical lead 112 can take many forms, and
in general can be considered an assembly of parts in electrical
contact with one another, whose function is to channel electric
current to components. The component electrical lead 112 can be a
conductive wire such as a metal wire, or a series of metal wires in
electrical contact with one another. The component electrical lead
112 can also be a conductive rod or other geometry of conductive
material, or an assembly of many such geometries. In some cases,
functional geometries are part of the component electrical lead
112, as in the case of mechanical clips, clamps, screws, hooks, or
brushes which facilitate electrical contact with components. The
component electrical lead 112 need not be stationary, but can move
due to the agitation of the process. For example, the component
electrical lead 112 can be part of a rotating component vessel
104.
[0040] Electrical current passes from the electric power supply
110, through the component terminal 108, through the component
electrical lead 112, and into the components 102 with which it is
in contact, to the other components 102 via the physical contacts
between the components 102. The other terminal of the electrical
power supply 110 is the counter terminal 114 and is connected to a
suitable counter electrode 116 through the counter electrical lead
118. The suitable counter electrode 116 is present in the
electrodeposition bath 106 but does not contact the components 102
to be coated.
[0041] When electrical current is permitted to flow in this
operation, provided that the conditions of the operation are
appropriate for electrodeposition, metal ions in the
electrodeposition bath 106 are deposited or plated onto the various
components 102 that are in the component vessel 104, over the
portions of the components 102 surfaces which are immersed in the
electrodeposition bath 106. In this way, all of the components may
be coated at the same time, as they are all part of a single
electrode "system" that comprises many components 102.
[0042] The electrodeposition bath 106 is contained within the bath
vessel 120. The bath vessel 120 sits within the oil bath 122, which
is contained within the oil bath vessel 124. The thermal controller
126 is connected electronically to the heater 128, which extends
into the oil bath 122. The temperature of the oil bath 122 is used
to control the temperature of the electrodeposition bath 106. The
heater 128, which is controlled by the thermal controller 128,
heats the oil bath 122. There are many possible ways to control and
maintain the proper temperature of the electrodeposition bath 106.
The heater 128 can be directly placed in the electrodeposition bath
106, ambient environmental conditions can be used, etc.
[0043] Sensors 130 also extend into the electrodeposition bath 106.
The sensors 130 include temperature, composition, pH, and viscosity
measurement devices. Additional or fewer measurement devices can be
included as sensors 130. A composition adjustment module 132 also
extends in the electrodeposition bath 106. The composition
adjustment module adds material to the electrodeposition bath based
on data produced by the sensors 130. The sensors 130 also provide
data used by the thermal controller 126.
[0044] It is often desirable for the electrodeposition bath 106 to
be stirred. The stirring apparatus 134 creates a magnetic field
which causes movement of the moving stirrer 136, thereby stirring
the electrodeposition bath. Many methods exist for stirring the
electrodeposition bath 106. The stirrer can be driven by a
mechanical power source, components or other apparatus devices can
be moved, etc. Pumps can also create aggressive fluid flow in the
electrodeposition bath 106 to achieve stirring of the
electrodeposition bath 106.
[0045] As the coating process proceeds, the points of contact
between components 102 allow transmission of electrical current
between them, but they may also shield the contact points and
regions in their immediate vicinity from being thoroughly coated.
For this reason, such barrel plating operations generally require
some agitation of the components 102, to continuously re-locate the
inter-component contact points as the coating process proceeds.
[0046] The agitation motor 138 is connected to and powers the
agitation drive unit 140, which is connected to the component
vessel 104. Movement of the agitation drive unit 140 causes
movement of the component vessel 104, which causes movement and
agitation of the components 102.
[0047] The agitation can be achieved in many ways, such as by
vibrating the component vessel 104 and its contents (including the
components 102), by rotating or revolving the vessel, moving a belt
on which the parts rest as is used in the Technic Tumbleplater
process. Aggressive fluid flow of the electrodeposition bath 106
induced by pumps can also be used to agitate the components 102. Of
such agitation methods, rotation of the vessel is most commonly
employed. The component vessel 104 need not be a barrel, it can be
any device capable of holding the components 102.
[0048] Agitation of the components 102 and/or component vessel 104
provides for redistribution of the electrical contact points
between the various components 102, as well as the contact between
some of the components 102 and the component electrical lead 112
connected to the electric power supply 110. It helps prevent
non-uniform coating of the components 102 near such contacts, and
can also prevent the coating from forming a permanent bond between
components 102 at their contact points. Agitation can be carried
out continuously or in shorter periods separated by periods without
agitation.
[0049] Agitation can have many other benefits for an
electrodeposition coating process. It can lead to detachment of
undesirable gas bubbles from coating surfaces (e.g., hydrogen
bubbles). Agitation can also serve to cycle some components into
and out of the electrodeposition bath 106. Agitation can also
affect the quality of the coated product, by leading to such things
as leveling and improved surface finish.
[0050] High volume electrodeposition processes such as barrel
plating can be conducted in a batch mode, or in a continuous mode.
In a continuous operation some mechanism of introducing and
removing components 102 at a regular rate is introduced.
[0051] Some or all of the components 102 in a high volume
electrodeposition process can be partly or completely masked, as by
a paint or tape applied to parts of the components 102 surface upon
which no coating is desired. Thus, although an entire individual
component 102 is exposed to the deposition fluid, the masked
portions of the surface would not be involved in electrodeposition.
In a system using agitation to relocate electrical contacts between
components 102, contacts with the masked portions of a component
102 may not conduct electrically. In this case, some components 102
may be out of electrical contact for some period or periods of time
during the process. In general, agitation should be sufficient to
render these periods insignificant, or to insure that similar total
such periods are experienced by all components 102.
[0052] In design of a high volume electrodeposition process, it is
important that the agitation process is not too severe. Severe
agitation can cause mechanical damage to the components 102 being
coated, which may be small and delicate.
[0053] High volume electrodeposition coating methods, such as the
barrel plating process and Technic Tumbleplater Process, can be
adapted to use various technologies to yield nanocrystalline or
amorphous electrodeposits. This would allow for high volume coating
of components with nanocrystalline or amorphous coatings.
Nanocrystalline and amorphous metals and alloys exhibit many of the
desirable properties important to high volume or barrel plating.
They are generally strong and resist contact damage, abrasion and
wear; these properties are desirable to avoid damage to the coating
and the components during high volume electrodeposition processing.
Furthermore, the electrical conductivity of a nanocrystalline or
amorphous metal or alloy may be high, facilitating the passage of
electrical current across contacts between components 102 or across
the contact between a component 102 and the component electrical
lead 112 connected to the electric power supply 110.
[0054] It is a preferred embodiment of the present invention to use
the method of Detor and Schuh for electrodepositing nanocrystalline
or amorphous alloys or metals as coatings, using a high volume
production process like barrel plating or the Technic Tumbleplater
process, and to induce a desired nanocrystalline grain size by
controlling the composition of the deposited alloy. Another
embodiment of the invention uses the method of Detor and Schuh
where the composition of the deposit is controlled by using a
designed periodic reverse pulse process during deposition, in order
to control the grain size. By controlling and tailoring the grain
size, desired material properties in the coating can be
achieved.
Continuous Electrodeposition:
[0055] An invention disclosed herein is a continuous
electrodeposition process including the deposition of a
nanocrystalline or amorphous metal or alloy coating. A related
invention is the product coated by a nanocrystalline or amorphous
metal or alloy in a continuous process.
[0056] A high-volume electrodeposition processes based on
continuous electrodeposition is also in use in industry. FIG. 2
illustrates a front view of a continuous electrodeposition
apparatus 200 suitable for the continuous coating of a component
strip 202 in a high volume process. The continuous
electrodeposition apparatus 200 includes a component strip 202, a
component coating 203, an electrodeposition bath 206, a component
terminal 208, an electrical power supply 210, component electrical
lead 212, a counter terminal 214, a suitable counter electrode 216,
a counter electrical lead 218, a bath vessel 220, an oil bath 222,
an oil bath vessel 224, a thermal controller 226, a heater 228,
sensors 230, a composition adjustment module 232, stirring
apparatus 234, and a moving stirrer 236.
[0057] Continuous deposition of a coating onto a component strip
202, such as a strip of metal, can be achieved if a continuous feed
of the component strip 202 is traveling through the
electrodeposition bath 206, and the component strip 202 is made an
electrode as in a conventional deposition process. Unlike a
conventional electrodeposition process in which a component is
dipped into the electrodeposition bath, continuous deposition
involves the component strip 202 traveling through the
electrodeposition bath 206 whereby a beginning portion of the
component strip 202 enters the electrodeposition bath 206 before an
adjoining portion of the component strip 202 and the beginning
portion of the component strip 202 also exits the electrodeposition
bath 206 before the adjoining portion of the component strip 202.
As the component strip 202 travels through the electrodeposition
bath 206 the component coating 203 is applied.
[0058] The component strip 202 to be coated enters the
electrodeposition bath 206, which contains or is contained within
an electrodeposition bath 206. A portion of the component strip 202
is in contact with the electrodeposition bath 206. The component
strip 202 is further electrically connected to the component
terminal 208 of an electrical power supply 210, through a component
electrical lead 212, which is in contact with the component strip
202. The component electrical lead 212 includes anything used to
contact with the component strip 202, such as a wire, rod,
alligator clip, screw, clamp, etc.
[0059] Electrical current passes from the electric power supply
210, through the component terminal 208, through the component
electrical lead 212, and into the component strip 202. The other
terminal of the electrical power supply 210 is the counter terminal
214 and is connected to a suitable counter electrode 216 through
the counter electrical lead 218. The suitable counter electrode 216
is present in the electrodeposition bath 206, but does not contact
the component strip 202.
[0060] When electrical current is permitted to flow in this
operation, provided that the conditions of the operation are
appropriate for electrodeposition, metal ions in the
electrodeposition bath 206 are deposited or plated onto the portion
of the component strip 202 which is immersed in the
electrodeposition bath 206.
[0061] The electrodeposition bath 206 is contained within the bath
vessel 220. The bath vessel 220 sits within the oil bath 222, which
is contained within the oil bath vessel 224. The thermal controller
226 is connected electronically to the heater 228, which extends
into the oil bath 222. The temperature of the oil bath 222 is used
to control the temperature of the electrodeposition bath 206. The
heater 228, which is controlled by the thermal controller 228,
heats the oil bath 222. There are many possible ways to control and
maintain the proper temperature of the electrodeposition bath 206.
The heater 228 can be directly placed in the electrodeposition bath
206, ambient environmental conditions can be used, etc.
[0062] Sensors 230 also extend into the electrodeposition bath 206.
The sensors 230 include temperature, composition, pH, and viscosity
measurement devices. Additional or fewer measurement devices can be
included the sensors 230. A composition adjustment module 232 also
extends in the electrodeposition bath 206. The composition
adjustment module adds material to the electrodeposition bath based
on data produced by the sensors 230. The sensors 230 also provide
data used by the thermal controller 226 used to control the
temperature.
[0063] It is often desirable for the electrodeposition bath 206 to
be stirred. The stirring apparatus 234 creates a magnetic field
which causes movement of the moving stirrer 236, thereby stirring
the electrodeposition bath. Many methods exist for stirring the
electrodeposition bath 206. The stirrer can be driven by a
mechanical power source, components 102 or other apparatus devices
can be moved, etc. Pumps can also create aggressive fluid flow in
the electrodeposition bath 206 to achieve stirring.
[0064] In a continuous process, the component strip 202 to be
coated can travel through a stationary electrodeposition bath 206,
or the electrodeposition bath 206 may be translated along its
length. The electrodeposition bath 206 need not be contained in a
bath vessel 220, for example a traveling sprayed bath, which may or
may not recirculate the bath fluid, can be used. Both the
electrodeposition bath 206 and component strip 202 can also be in
motion, provided that there is a net relative motion of the
electrodeposition bath 206 and component strip 202 with respect to
one another. A flexible component strip 202 can also deflect or
curve to enter the electrodeposition bath 206 rather than traveling
straight through the electrodeposition bath 206.
[0065] Furthermore, the relative motion of the component strip 202
with respect to the bath need not be uninterrupted, smooth, or
perfectly continuous. Periodic discrete advances of the component
strip 202, for example, constitute a continuous process with an
average feed rate given by the sum of the lengths of each advance
divided by the sum of the dwell times after each advance and the
sum of the times involved in each advance. Furthermore, periods of
reverse relative motion of the component strip 202 in the
deposition bath 206 are possible and affect the average feed rate
of the process, but do not limit the generality of the present
inventions.
[0066] The component strip 202 may be fed from one reel to another
in a continuous fashion, or part of a larger manufacturing
operation. Additionally, the geometry of the component strip 202 is
arbitrary in such an operation. Component strips 202 such as Wires,
rods, I-beams, sheets, perforated sheets or strips, extrusions, or
even more complex geometries can be coated in high volumes through
a continuous process.
[0067] Part or all of the component strip 202 geometry can be
coated. By masking or otherwise preventing current flow to some
portions of the geometry, it is possible to selectively coat, for
example, one side of a sheet or strip, one edge of a rectangular
beam, or a length-wise groove or raised feature on a complex
geometry.
[0068] In continuous processes such as described above, the coating
material is chosen for its desirable properties in the final coated
product. Some desirable properties may be high hardness, high
strength, ductility, wear resistance, electrical properties,
magnetic properties, corrosion characteristics, substrate
protection, and many others.
[0069] Continuous electroplating operations can also be adapted to
incorporate technologies that allow the deposition of
nanocrystalline or amorphous metals or alloys. Continuous
operations include the coating of a continuous feed of a component
strip 202 or sheet of metal, where the component strip 202 or sheet
is made an electrode as in a conventional deposition process. Such
component strip 202 may be fed from one reel to another in a
continuous fashion, or part of a larger manufacturing operation
with or without feeding reels. Additionally, the geometry of the
component strip 202 is arbitrary in such an operation. Component
strips 202 such as wires, rods, I-beams, sheets, perforated sheets
or strips, extrusions, or even more complex geometries can be
coated in high volumes through a continuous process. Part or all of
the geometry can be coated in this manner. By masking or otherwise
preventing current flow to some portions of the geometry, it is
possible to selectively coat, for example, one side of a sheet or
strip, one edge of a rectangular beam, or a length-wise groove or
raised feature on a complex geometry.
[0070] A continuous plating process can also be used to coat a
series of discrete components, which are assembled into a
continuous strip. For example, a sheet of metal can be perforated
into many individual components that are connected to one another,
and this connected strip of components moved through the deposition
bath to coat the components. Individual components can also be
assembled into a continuous strip by many other methods that
provide an electrical contact between components along the length
of the strip. For example, a traveling wire or cable upon which a
series of hooks are affixed may be used to hang many components,
which travel through the deposition bath with the wire. Other
continuous processes involving discrete components will be apparent
to those skilled in the art, and any such processes may be used in
conjunction with the present invention.
[0071] In a preferred embodiment of the present invention, a
continuous electroplating operation is adapted to produce a
nanocrystalline or amorphous metal or alloy coating, where the
method of Detor and Schuh described above is used to effect
nanocrystalline grain size of a desired dimension, or an amorphous
structure, in the coating material. In its most general form, the
method of Detor and Schuh employs control of the alloy composition
of the coating to control the nanocrystalline grain size. Another
embodiment of the invention is to use the method of Detor and Schuh
via the application of a periodic reverse pulse to control the
coating composition and grain size, in a continuous
electrodeposition process.
Rework/Rebuild:
[0072] Another invention disclosed herein is a rework/rebuild
process including the use of a nanocrystalline or amorphous metal
coating. A related invention is a component that has been reworked
or rebuilt using a nanocrystalline or amorphous metal coating.
[0073] Another use of electrodeposited coatings is for the
reworking and rebuilding of components. The terms "rework" and/or
"rebuild", collectively--"rework/rebuild," are defined herein to
describe a process of depositing a coating material atop a
substrate material or component in order to bring the dimensions of
the component to within a specified tolerance and/or repair surface
defects in the component. These processes are also sometimes
referred to as "remanufacturing" in the literature.
[0074] FIG. 3 illustrates a side view of a worn component 302 in
need of rework/rebuild. The worn component 302 has a worn surface
304 which is need of rework/rebuild. A worn surface 304 is one,
which, owing to its use in service, has experienced abrasion,
erosion, wear, corrosion, or any other such process or combination
of processes that may tend to remove some material and consequently
alter the shape of the component. A worn surface 304 can also be a
result of the initial component 302 manufacturing process.
[0075] FIG. 4 illustrates a side view of a worn component 302 in
need of rework/rebuild after a coating has been applied.
Rework/rebuild is used as a means of replenishing the worn material
by first depositing fresh material in the form of an applied
coating 402.
[0076] FIG. 5 illustrates a side view of a worn component 302 after
completion of rework/rebuild. After the application of the applied
coating 402, subsequent machining is performed on the applied
coating 402, creating a machined surface 502. The machined surface
502 brings the worn component 302 back to within an acceptable
dimensional tolerance 504 of its intended shape. Rework/rebuild
might also be used to repair defects in a material that has not
been put into service, but which developed defects during synthesis
and processing stages, or perhaps developed such defects
unintentionally by misuse or during handling or storage. Defects
formed during the application of a coating may also be
reworked.
[0077] In some cases, the wear, abrasion, corrosion, or erosion
that a component experienced may have involved the degradation not
only of the worn component's 302 base material, but also of a
coating material previously applied to the component. In this case
the rework/rebuild process often begins by removal (stripping) of
the original coating material prior to the subsequent application
of a new coating for the purpose of rebuilding the component.
Rework/rebuild can also apply to components upon which the only
wear or degradation occurred on a prior coating layer, where only
said coating layer requires rework.
[0078] Rework/rebuild can also be used on worn components 302 which
underwent a surface degradation process that did not involve
material removal, for example oxidation, abrasion, or fatigue crack
growth. In these cases, rework/rebuild can be preceded by a surface
finishing process such as machining, polishing, shot peening,
chemical milling, etc. In this case the rework process would
rebuild material removed by the surface finishing process rather
than that removed by virtue of abrasion or corrosion in
service.
[0079] Although rework/rebuild is a process most commonly applied
to components that experience mechanical loads (i.e., machine
components or structural components), the process is quite general
and may have application in many other domains including for
components with electrical, electronic, magnetic, anti-corrosive,
optical, aesthetic, medical, or other functional or decorative
properties.
[0080] After the application of a suitable coating, a machining
operation is often used to form the coated component into a
desirable geometry. The term `machining` may refer to conventional
machine shop operations including milling, grinding, filing, or
turning on a lathe, or can more generally refer to any process by
which some of the coating material is removed. This can include
mechanical polishing, chemical polishing, combined
mechanical-chemical polishing, electro-chemical milling,
electro-chemical etching, or electro-chemical polishing.
[0081] In some instances, a machining operation is not required at
all for a rework/rebuild operation, if the deposited coating brings
the geometry of the component to within the required dimensional
tolerance without the need for machining.
[0082] The rework/rebuild process includes three stages: surface
preparation, coating, and machining. The first stage involves
preparing the surface of the component to be reworked/rebuilt for
the later coating. This surface preparation includes cleaning,
removal (stripping) of an original coating material, machining,
polishing, shot peening, chemical milling, etc. Surface preparation
is not always required and includes any operations which prepares
the surface for further rework/rebuild processing. The second stage
involves coating the surface of the component to be
reworked/rebuilt; an invention contained herein is to use a
nanocrystalline or amorphous metal coating.
[0083] Nanocrystalline and amorphous metals are desirable for
rework/rebuild operations because they are generally very strong,
hard, and can exhibit improved abrasion and corrosion resistance as
compared with their more conventional microcrystalline counterparts
(which have an average crystalline grain size above one
micrometer).
[0084] Electrodeposition is a common technology for the application
of coatings. Accordingly, existing electrodeposition equipment can
be used to apply the nanocrystalline and amorphous metallic
coatings.
[0085] Coatings of 200 .mu.m or thicker are generally required for
rework/rebuild operations. Nanocrystalline metal coatings greater
than 200 .mu.m in thickness can be produced by electrodeposition.
Amorphous metals can also be electrodeposited to the required high
thicknesses for rebuild/rework, as explained in U.S. patent
application Ser. No. 11/032,680 by Schuh and Detor, which is
included fully herein by reference.
[0086] Thus, electrodeposition can be used to produce
nanocrystalline and amorphous coatings of the proper thickness and
desirable properties for a rework or rebuild operation. They also
generally have desirable high hardness and abrasion resistance, and
can be machined, polished, electro-chemically milled, or otherwise
treated to achieve a desirable final geometry. Electrodeposited
nanocrystalline and amorphous metals are therefore ideal for
rework/rebuild operations.
[0087] A technique for the electrodeposition of nanocrystalline
metals is that of Detor and Schuh described above. This technique
controls the composition of an alloy deposit in order to control
the grain sizes of a nanocrystalline or amorphous alloy. It is a
preferred embodiment of the present invention to use the method of
Detor and Schuh for the purpose of rebuild and rework.
[0088] Another embodiment of the invention is to use periodic
reverse pulsing to control composition, and thereby to control
grain size of a nanocrystalline coating. This reverse pulse
technique is particularly suited for the purpose of rework and
rebuild because it produces coatings of tailorable grain size
without macroscopic defects such as cracks or voids.
[0089] This reverse pulsed technique involves the introduction of a
bipolar wave current, with both positive and negative current
portions, during the electrodeposition process. Using this
technique provides the ability to adjust the composition of the
deposit, its grain size, or both within a relatively quick amount
of time, and without changing either the composition or temperature
of the electrodeposition bath liquid. Further, the technique
produces high quality homogeneous deposits with a lesser degree of
voids and cracks than is conventionally achieved. The technique
also enables grading and layering of nanocrystalline crystal size
and/or composition within a deposit. Additionally, the technique is
economical, scalable to industrial volumes, and robust.
[0090] Thus, the reader will see that this invention provides a
method of rework/rebuild and an article of that method that
provides many benefits. A nanocrystalline and/or amorphous metal
coating for rework/rebuild provides: high strength and hardness,
high corrosion resistance, high wear and abrasion resistance,
thicknesses of at least 200 .mu.m, improved environmental impact or
worker safety as compared with prior art (e.g., when using a
Ni-based, Co-based or Cu-based nanocrystalline or amorphous metal
instead of hard chromium), improved cost (e.g., when using an
electrodeposited nanocrystalline or amorphous coating instead of a
physical vapor deposited or plasma sprayed coating), improved
ability to coat geometries with internal surfaces and
non-line-of-sight surfaces (e.g., when using a high throwing-power
electrodeposition process for a nanocrystalline or amorphous
Ni-based alloy, as compared with a line-of-sight process such as
plasma spray coating or a lower throwing-power electrodeposition
process such as hard chromium plating), better compatibility or
matching of the substrate material to the rework/rebuild coating
(e.g., if a nanocrystalline or amorphous Ni-based coating is used
atop a nickel based alloy for better matching of the elastic
properties, as compared with the use of hard chromium atop the
nickel based alloy, which have different elastic properties),
improved surface properties (e.g., if a nanocrystalline or
amorphous form with better corrosion resistance is used instead of
hard chromium), ability to withstand subsequent machining
operations, and the ability to utilize existing electroplating
equipment.
[0091] While the above description contains much specificity, these
should not be construed as limitations on the scope of the
invention but rather as an explanation of one preferred embodiment
thereof. Many other variations are possible. Accordingly the scope
of the invention should be determined not by the embodiments
illustrated but by the appended claims and their legal
equivalents.
Partial Summary:
[0092] Inventions disclosed and described herein include methods
for the use of nanocrystalline or amorphous metals or alloys as
coatings by industrial processes. Processes of manufacture using
such coatings are described, as are products incorporating or using
such coatings.
[0093] Thus, this document discloses many related inventions.
[0094] One invention disclosed herein is an article of manufacture
comprising a nanocrystalline or amorphous material applied to a
component, whereby the nanocrystalline or amorphous material is
applied through an electrodeposition process where an electric
potential exists on the component through an electrical contact
with other components.
[0095] The electrodeposition process may be tailored to produce a
specific grain size. The electrodeposition process may also be
tailored to apply material with more than one grain size, or with
varying composition or grain size.
[0096] According to one preferred embodiment, the article of
manufacture comprises a nanocrystalline or amorphous material
applied to a component, whereby the nanocrystalline or amorphous
material is applied through an electrodeposition process where an
electric potential exists on the component through an electrical
contact with other components, and the process uses a vessel to
hold multiple components.
[0097] According to another set of preferred embodiments, the
electrodeposition process involves an electrical potential having
periods of both positive polarity and negative polarity, or in
which the electrodeposition process involves an electrical
potential that is pulsed more than once.
[0098] A related set of preferred embodiments involves the
deposition of a nanocrystalline or amorphous Ni-based coating
containing one of the elements W, Mo, P, or B, in conjunction with
an electrical potential having periods of both positive and
negative polarity, or in which the electrodeposition process
involves an electrical potential that is pulsed more than once.
[0099] In yet another preferred embodiment, the article of
manufacture comprises a nanocrystalline or amorphous material
applied to a component, whereby the nanocrystalline or amorphous
material is applied through an electrodeposition process where an
electric potential exists on the component through an electrical
contact with other components, and where the electrical contact
with other components is changing as a result of agitation of the
components.
[0100] Another invention disclosed herein is an article of
manufacture comprising a nanocrystalline or amorphous metal applied
to a component whereby the nanocrystalline or amorphous metal is
applied through an electrodeposition process with a beginning
portion of the component entering the electrodeposition bath before
an adjoining portion of the component and the beginning portion of
the component also exiting the electrodeposition bath before the
adjoining portion of the component.
[0101] The electrodeposition process may be tailored to produce a
specific grain size. The electrodeposition process may also be
tailored to apply material with more than one grain size, or with
varying composition or grain size.
[0102] The electrodeposition process may involve an electrical
potential existing on the component.
[0103] According to a set of preferred embodiments, the article of
manufacture comprises a nanocrystalline or amorphous metal applied
to a component whereby the nanocrystalline or amorphous metal is
applied through an electrodeposition process with a beginning
portion of the component entering the electrodeposition bath before
an adjoining portion of the component and the beginning portion of
the component also exiting the electrodeposition bath before the
adjoining portion of the component, and the electrodeposition
process involves an electrical potential having periods of both
positive polarity and negative polarity, or in which the
electrodeposition process involves an electrical potential that is
pulsed more than once.
[0104] A related set of preferred embodiments involves the
deposition of a nanocrystalline or amorphous Ni-based coating
containing one of the elements W, Mo, P, or B, in conjunction with
an electrical potential having periods of both positive and
negative polarity, or in which the electrodeposition process
involves an electrical potential that is pulsed more than once.
[0105] Still another invention disclosed herein is an article of
manufacture comprising a nanocrystalline or amorphous material
applied to a component for a purpose of repairing damage to a
component surface or bringing the geometry of the component to
within a desired dimensional size.
[0106] The application of a nanocrystalline or amorphous metal can
comprise an electrodeposition process. The application of a
nanocrystalline or amorphous metal can also comprise an
electrodeposition process tailored to produce a specific grain
size, or tailored to apply material with varying composition or
grain size.
[0107] In a set of related preferred embodiments, the application
of a nanocrystalline material comprises an electrodeposition
process with an electrical potential having periods of both
positive polarity and negative polarity, or where the electrical
potential is pulsed more than once.
[0108] A related set of preferred embodiments involves the
deposition of a nanocrystalline or amorphous Ni-based coating
containing one of the elements W, Mo, P, or B, in conjunction with
an electrical potential having periods of both positive and
negative polarity, or in which the electrodeposition process
involves an electrical potential that is pulsed more than once.
[0109] In a final preferred embodiment, an article of manufacture
comprises a nanocrystalline or amorphous material applied to a
component for a purpose of repairing damage to a component surface
or bringing the geometry of the component to within a desired
dimensional size, where the component surface receives subsequent
processing to bring the geometry of the component to within a
desired dimensional size.
* * * * *