U.S. patent application number 15/936121 was filed with the patent office on 2019-09-26 for wear resistant coatings containing precipitation-hardened alloy bodies and methods for the formation thereof.
This patent application is currently assigned to HONEYWELL INTERNATIONAL INC.. The applicant listed for this patent is HONEYWELL INTERNATIONAL INC.. Invention is credited to Ersan Ilgar, James Piascik.
Application Number | 20190292674 15/936121 |
Document ID | / |
Family ID | 65911021 |
Filed Date | 2019-09-26 |
United States Patent
Application |
20190292674 |
Kind Code |
A1 |
Ilgar; Ersan ; et
al. |
September 26, 2019 |
WEAR RESISTANT COATINGS CONTAINING PRECIPITATION-HARDENED ALLOY
BODIES AND METHODS FOR THE FORMATION THEREOF
Abstract
Methods for producing a coated component are provided, as are
coated components having wear resistant coatings. In embodiments,
the method includes the step or process of fabricating, purchasing,
or otherwise obtaining a component having a component surface. An
XP alloy body is formed over the component surface to yield a
coated component, wherein P is phosphorus and X is cobalt, nickel,
or a combination thereof. After formation of the XP alloy body, the
XP alloy body is machined; and, following machining, the coated
component is heat treated to precipitate harden the XP alloy body.
In certain embodiments, heat treatment may be conducted to
concurrently anneal the underlying component in conjunction with
precipitation hardening of the XP alloy body. In other instances,
the method further includes the step of forming a barrier layer
over the component surface prior to deposition of the XP alloy
body.
Inventors: |
Ilgar; Ersan; (Morristown,
NJ) ; Piascik; James; (Randolph, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HONEYWELL INTERNATIONAL INC. |
Morris Plains |
NJ |
US |
|
|
Assignee: |
HONEYWELL INTERNATIONAL
INC.
Morris Plains
NJ
|
Family ID: |
65911021 |
Appl. No.: |
15/936121 |
Filed: |
March 26, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C25D 5/40 20130101; F04C
2230/91 20130101; C25D 5/02 20130101; C25D 5/18 20130101; F04C
2230/41 20130101; C21D 9/0068 20130101; E21B 43/121 20130101; C25D
3/12 20130101; C25D 5/48 20130101; F04C 2/107 20130101; F04C
2240/20 20130101; C25D 5/10 20130101; C25D 5/50 20130101; F04C
13/008 20130101; F04C 2230/10 20130101; C25D 5/34 20130101; C25D
3/562 20130101; C23C 30/00 20130101; C25D 5/12 20130101 |
International
Class: |
C25D 5/50 20060101
C25D005/50; C21D 9/00 20060101 C21D009/00; C25D 3/56 20060101
C25D003/56; C25D 5/48 20060101 C25D005/48; C25D 3/12 20060101
C25D003/12; C25D 5/10 20060101 C25D005/10; C25D 5/12 20060101
C25D005/12; F04C 13/00 20060101 F04C013/00; F04C 2/107 20060101
F04C002/107 |
Claims
1. A method for producing a coated component, comprising: obtaining
a component having a component surface; forming an XP alloy body
over the component surface to yield a coated component, wherein P
is phosphorus and X is cobalt, nickel, or a combination thereof;
after forming the XP alloy body, machining the XP alloy body; and
after machining the XP alloy body, heat treating the coated
component to precipitate harden the XP alloy body.
2. The method of claim 1 wherein heat treating comprises heat
treating the coated component to anneal the component, while
concurrently precipitate hardening the XP alloy body.
3. The method of claim 1 further comprising forming a barrier layer
on the component surface prior to deposition of the XP alloy body,
the barrier layer containing a greater amount of X than does the XP
alloy body.
4. The method of claim 3 wherein the barrier layer consists
essentially of X.
5. The method of claim 3 wherein depositing comprises
electroplating the XP alloy body directly onto the barrier
layer.
6. The method of claim 1 wherein the component comprises a mud
rotor shaft having a lobed outer surface, and wherein machining
comprises machining the mud rotor shaft to impart the lobed outer
surface with an average roughness equal to or less than 1
micron.
7. The method of claim 1 further comprising formulating the XP
alloy body to contain: a majority X, by weight; and about 5% to
about 25% P, by weight.
8. The method of claim 1 further comprising formulating the XP
alloy body to consist essentially of: about 10% to about 15% P, by
weight; and the remainder X.
9. The method of claim 1 wherein the XP alloy body is formed by
successively depositing at least a first XP alloy layer and a
second XP alloy layer, and wherein the method further comprises:
depositing the first XP alloy layer; machining the first XP alloy
layer to remove areas of nodular growth therefrom; and after
machining the first XP alloy layer, depositing a second XP alloy
layer over the first XP alloy layer.
10. The method of claim 1 wherein the XP alloy body comprises
opposing inner and outer surfaces, the inner surface located closer
to the component than is the outer surface; and wherein forming
comprises forming the XP alloy body to contain a first P content
adjacent the inner surface and a second P content adjacent the
outer surface, the second P content at least twice the first P
content.
11. The method of claim 1 wherein forming the XP alloy body
comprises: depositing an XP alloy layer over the component surface
utilizing an electroplating process; and increasing a current
density during the electroplating process to increase the P content
of the XP alloy body as the XP alloy body is compiled over the
component surface.
12. A method for producing a coated component, comprising:
obtaining a component having a component surface; and forming a
precipitation-hardened alloy body over the component surface,
forming comprising: electrodepositing at least one alloy layer in a
pre-hardened state over the component surface to yield a coated
component; after electrodepositing, machining the at least one
alloy layer in the pre-hardened state; and heat treating the coated
component to anneal the component, while precipitate hardening the
at least one alloy layer to yield a precipitation-hardened alloy
body having a hardness at least twice that of the one or more alloy
layers in the pre-hardened state.
13. The method of claim 12 further comprising: prior to
electrodepositing the at least one alloy layer, forming a barrier
layer over the component surface; and formulating the barrier layer
to be less susceptible to precipitate hardening than is the at
least one alloy layer.
14. The method of claim 13 further comprising: formulating the at
least one alloy layer to be composed of an XP alloy, wherein P is
phosphorus and X is cobalt, nickel, or a combination thereof; and
formulating the barrier layer to contain an increased amount of X
and a decreased amount of P as compared to the at least one alloy
layer.
15. The method of claim 12 wherein the one or more alloy layers
comprise opposing inner and outer surfaces, the inner surface
located closer to the component than is the outer surface; and
wherein the method further comprises electrodepositing the at least
one alloy layer to have a P content, which decreases when moving
from the outer surface toward the inner surface.
16. A coated component, comprising: a component having a component
surface; and a precipitation-hardened alloy body overlying the
component surface, the precipitation-hardened layer composed of an
XP alloy body wherein P is phosphorus and X is cobalt, nickel, or a
combination thereof.
17. The coated component of claim 16 further comprising a barrier
layer disposed between the component surface and the
precipitation-hardened alloy body, the barrier layer containing X
in a greater amount than does the XP alloy body.
18. The coated component of claim 16 wherein the XP alloy body
comprises: a majority X, by weight; and about 5% to about 25% P, by
weight.
19. The coated component of claim 16 wherein the XP alloy body
comprises: opposing inner and outer surfaces, the inner surface
located closer to the component than is the outer surface; a first
P content adjacent the inner surface; and a second P content
adjacent the outer surface and at least twice the first P
content.
20. The coated component of claim 16 wherein the coated component
comprises a mud rotor shaft having a lobed outer surface, and
wherein the lobed outer surface has an average surface roughness
equal to or less than 1 micron.
Description
TECHNICAL FIELD
[0001] The following disclosure relates generally to wear resistant
coatings and, more particularly, to wear resistant coatings
containing precipitation-hardened alloy bodies, as well as to
methods for the formation of such wear resistant coatings.
BACKGROUND
[0002] There is a need for low cost, high performance wear
resistant coatings across various industries. In the oil and gas
industry, for example, there exists a continued demand for wear
resistant coatings suitable for deposition over components utilized
in downhole drilling applications, such as lobed rotor shafts of
the type found in the power section of steerable and non-steerable
downhole mud rotors. Ideally, such wear resistant coatings are
relatively durable and possess high hardness values exceeding, for
example, 900 Vickers Pyramid Number (HV). It may also be desirable
for such wear resistant coatings to serve as a barrier against
undesired chemical reactions with environmental contaminants. For
example, in the case of a downhill drilling applications, such wear
resistant coatings beneficially shield the underlying substrate or
component from exposure to environmental acids, sulfides, and
salts, which could corrode or otherwise structurally degrade the
underlying component.
[0003] Specialized coatings have been developed for usage in
downhole drilling applications and other applications demanding
high wear and corrosion resistance. Examples of such coatings
include hard chrome platings and tungsten-carbide (WC) coatings.
Such legacy wear resistant coatings are, however, typically limited
in one or more respects. For example, the High Velocity Oxygen Fuel
(HVOF) deposition processes utilized to deposit WC coatings are
often costly to perform. Further, in the case of both hard chrome
platings and WC coatings, such coatings are typically quite hard
and brittle as initially deposited As a result, such legacy wear
resistant coatings pose additional challenges when machining is
desirably performed following coating deposition to define
structural features, to satisfy dimensional tolerances, or meet
surface finish requirements. Post-coating machining, such as
grinding to satisfy surface finish requirements, is thus a costly
and time consuming process, often requiring diamond cutting tools
and specialized operations. Post-coating machining can also
potentially result in damage, such as chipping or cracking, of the
newly-deposited wear resistant coating. This may not only adversely
impact the structural integrity of the wear resistant coating, but
may also render the coating prone to the ingress of environmental
contaminants as noted above.
[0004] There thus exists an ongoing demand for high performance,
wear resistant coatings and methods for forming such wear resistant
coatings, which can be performed in a relatively cost efficient,
timely, and reliable manner. It would be particularly desirable for
such coating formation methods to ease post-coating machining of
the coating, while achieving finished coatings with relatively high
hardness values and other desirable properties. It would also be
desirable for embodiments of wear resistant coatings to serve as
effective environmental barriers by deterring the penetration of
environment contaminants through the coating thickness and to the
underlying substrate or component. Other desirable features and
characteristics of embodiments of the present invention will become
apparent from the subsequent Detailed Description and the appended
Claims, taken in conjunction with the accompanying drawings and the
foregoing Background.
BRIEF SUMMARY
[0005] Methods for producing coated components are provided. In
embodiments, the method includes the step or process of
fabricating, purchasing, or otherwise obtaining a component having
a component surface. An XP alloy body is formed over the component
surface to yield a coated component, wherein P is phosphorus and X
is cobalt, nickel, or a combination thereof. After formation of the
XP alloy body, the XP alloy body is machined; and, following
machining, the coated component is heat treated to precipitate
harden the XP alloy body. In certain embodiments, heat treatment
may be conducted to concurrently anneal the underlying component in
conjunction with precipitation hardening of the XP alloy body. In
other instances, the method further includes the step of forming a
barrier layer over the component surface prior to deposition of the
XP alloy body. The barrier layer may contain a greater amount of X
and, perhaps, a lesser amount of P than does the XP alloy body;
e.g., in certain implementations, the barrier layer may consist
essentially of X. In other embodiments in which the component
assumes the form of a mud rotor shaft having a lobed outer surface,
the step of machining may entail polishing, grinding, or otherwise
machining the mud rotor shaft to impart the lobed outer surface
with an average roughness equal to or less than 1 micron.
[0006] In further embodiments, the method includes the step or
process of obtaining a component having a component surface. A
precipitation-hardened alloy body is formed over the component
surface. The precipitation-hardened alloy body is formed by
depositing at least one alloy layer in a pre-hardened or relatively
soft state over the component surface to yield a coated component.
The at least one alloy layer is then machined in the pre-hardened
state. Afterwards, heat treatment is performed to anneal the
component, while precipitate hardening the at least one alloy layer
to thereby yield a precipitation-hardened alloy body. Following
heat treatment, the precipitation-hardened alloy body may have a
hardness at least twice that of the at least one alloy layer, as
measured in the pre-hardened state. In certain implementations, the
method further includes the step of forming a barrier layer over
the component surface prior to deposition of the at least one alloy
layer, while formulating the barrier layer to be less susceptible
to precipitate hardening, when heat treated, than is the at least
one alloy layer. In still other embodiments, the at least one alloy
layer may be composed of an XP alloy, wherein P is phosphorus and X
is cobalt, nickel, or a combination thereof. In such instances, the
barrier layer may contain an increased amount of X and a decreased
amount of P as compared to the at least one alloy layer.
[0007] Components protected by wear resistant coatings (herein,
"coated components") are further provided. In embodiments, the
coated component includes a base component having a component
surface and a precipitation-hardened alloy body, which is formed
over the component surface and which may or may not directly
contact the component surface. The precipitation-hardened layer is
composed of an XP alloy body wherein P is phosphorus and X is
cobalt, nickel, or a combination thereof. In certain
implementations, the coated component further includes a barrier
layer disposed between the component surface and the
precipitation-hardened alloy body, with the barrier layer
containing X in a greater amount than does the XP alloy body. In
other implementations, the XP alloy body may be composed of a
majority X, by weight, and between about 5% to about 25% P, by
weight. In still further implementations, the XP alloy body may
have opposing inner and outer surfaces, with the inner surface
located closer to the component than is the outer surface. In such
implementations, the XP alloy body may further have a first P
content adjacent the inner surface and a second P content adjacent
the outer surface, with the second P content exceeding (e.g., at
least twice) the first P content.
[0008] Various additional examples, aspects, and other useful
features of embodiments of the present disclosure will also become
apparent to one of ordinary skill in the relevant industry given
the additional description provided below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] At least one example of the present invention will
hereinafter be described in conjunction with the following figures,
wherein like numerals denote like elements, and:
[0010] FIG. 1 is a cross-section of a limited region of coated
component including a component body over which a wear resistant
coating is formed, as illustrated in accordance with an exemplary
embodiment of the present disclosure;
[0011] FIG. 2 is an isometric cutaway view of the power section of
a downhole mud rotor, which contains a lobed rotor shaft protected
by a wear resistant coating similar or identical to that shown in
FIG. 1 and which is illustrated in accordance with an exemplary
embodiment of the present disclosure; and
[0012] FIG. 3 is a flowchart setting-forth a method for forming a
wear resistant coating over selected surfaces of an underlying
component or substrate, as illustrated in accordance with an
exemplary embodiment of the present disclosure.
[0013] For simplicity and clarity of illustration, descriptions and
details of well-known features and techniques may be omitted to
avoid unnecessarily obscuring the exemplary and non-limiting
embodiments of the invention described in the subsequent Detailed
Description. It should further be understood that features or
elements appearing in the accompanying figures are not necessarily
drawn to scale unless otherwise stated.
DETAILED DESCRIPTION
[0014] The following Detailed Description is merely exemplary in
nature and is not intended to limit the invention or the
application and uses of the invention. The term "exemplary," as
appearing throughout this document, is synonymous with the term
"example" and is utilized repeatedly below to emphasize that the
description appearing in the following section merely provides
multiple non-limiting examples of the invention and should not be
construed to restrict the scope of the invention, as set-out in the
Claims, in any respect. As further appearing herein, statements
indicating that a first layer or first body of material is
"deposited over," "deposited on," "formed over," or "formed on" a
second layer, a second body of material, or a component does not
require that that the first layer or body is deposited or formed
directly on and intimately contacts the second layer, body, or
component unless otherwise specifically stated.
[0015] Definitions
[0016] The following definitions apply throughout this document.
Those terms not expressly defined here or elsewhere in this
document are assigned their ordinary meaning in the relevant
technical field.
[0017] Coating--One or more layers of material formed over a
component surface.
[0018] Coated Component--A component having at least one surface
over which a wear resistant coating is formed.
[0019] Cobalt-Phosphorous (CoP) Alloy--An alloy predominately
composed of cobalt and phosphorus, by weight.
[0020] Component--Any article of manufacture over which a coating
can be formed. This term is synonymous with or encompasses similar
terms including "substrate," "part," and "workpiece."
[0021] Nickel-Phosphorous (NiP) Alloy--An alloy predominately
composed of nickel and phosphorus, by weight.
[0022] XP Alloy--An alloy predominately composed of phosphorous and
"X," by weight, wherein "X" is cobalt, nickel, or a combination
thereof.
[0023] Overview
[0024] Embodiments of wear resistant coatings, coated components
protected by wear resistant coatings, and methods for forming wear
resistant coatings are disclosed. Embodiments of the wear resistant
coatings contain precipitation-hardened alloy bodies, which are
initially deposited in a pre-hardened and subsequently
precipitation hardened to enhance the final hardness of the alloy
bodies. In the pre-hardened state, the alloy bodies may be soft and
ductile, in a relative sense, and therefore amenable to machining
utilizing conventional tooling equipment and techniques. By
initially depositing the alloy bodies in a pre-hardened state,
performing the needed machining operations, and subsequently
precipitate hardening the alloy bodies, wear resistant coatings can
be fabricated having relatively high hardness values, while
machining of the coating is eased. Depending upon alloy body
composition and heat treatment parameters, the alloy bodies can
achieve relatively high hardness values approaching or exceeding
950 Vickers Pyramid Number (HV) following precipitate hardening.
Comparatively, a given alloy body may have a hardness value between
500 and 600 HV in its initially-deposited, pre-hardened state.
Process efficiency can also be enhanced by precipitate hardening
the alloy body, while concurrently annealing the underlying
substrate or component utilizing a single heat treatment process in
certain instances.
[0025] In accordance with embodiments of the present disclosure, a
given alloy body may be electrodeposited over a component surface,
whether as a single, continuous layer or as multiple,
successively-deposited layers. If deposited in multiple layers,
machining can be performed at suitable junctures between layer
deposition to, for example, remove nodular growth from
newly-deposited material layers, to define more detailed structural
features, or the like. Generally, the precipitation-hardened alloy
body may be composed of any material or combination of materials
suitable for achieving the desired wear resistance functionality
and other desired properties (e.g., high ductilities), while
remaining capable of significant enhancement in hardness values via
heat treatment and precipitate hardening; e.g., ideally,
precipitation hardening results in an increase of at least 50% in
hardness value, if not a doubling of the hardness value when
transitioning from the pre-hardened to the post-hardened state of
the alloy body. In implementations, the precipitation-hardened
alloy body is composed of an XP alloy; that is, an alloy containing
alloy predominately composed of phosphorous (P) and "X," by weight,
wherein "X" is cobalt (Co), nickel (Ni), or a combination thereof.
For example, in one embodiment, the XP alloy contains a majority X,
by weight; a lesser amount of P, by weight; and any number (zero or
more) additional constituents present in a lesser amount than P, by
weight.
[0026] In embodiments, the wear resistant coating may consist
solely of the precipitation-hardened alloy body, which is formed
directly on and physically contacts the underlying substrate or
component surface. Alternatively, the wear resistant coating may
contain one or more additional layers, such as a bondcoat, formed
between the precipitation-hardened alloy body and the underlying
component. In this latter regard, when the wear resistant coating
desirably provides environmental barrier protection, one or more
barrier layers may be formed between the precipitation-hardened
alloy body and the underlying component, with the barrier layer(s)
composed of a material less susceptible to precipitate hardening
than is the alloy body. As compared to the alloy body, the
intervening barrier layer may remain relatively impermeable to
contaminant penetration following heat treatment and precipitate
hardening the alloy body, which may experience grain growth
rendering the alloy body more susceptible to containment
penetration. In further implementations, the wear resistant coating
may lack any such barrier layer, and the precipitation-hardened
alloy body may instead be deposited to undergo reduced (e.g.,
little to no) precipitation formation in one or more limited
regions or bands. In embodiments in which the alloy body is
composed of an XP alloy, the alloy body may be deposited to contain
a lower (and possibly zero) P content adjacent its inner surface,
while having a substantially higher (e.g., at least twice the) P
content adjacent its outer surface. As still further possibility, a
combination of the aforementioned approaches can be employed such
that the wear resistant coating contains a barrier layer, while the
alloy body is imparted with a varied P content through its
thickness; e.g., a P content that decreases in a stepped or
non-stepped (gradual) manner, as taken through the thickness of the
alloy body moving toward the barrier layer. Exemplary embodiments
of coated components having wear resistant coatings will now be
discussed in conjunction with FIGS. 1-2.
[0027] Examples of Coated Component Having Wear Resistant
Coatings
[0028] FIG. 1 is a cross-sectional schematic of a coated component
10, as illustrated in accordance with an exemplary embodiment of
the present disclosure. Coated component 10 includes an underlying
substrate or component body 12, which has a principal component
surface 14 over which a wear resistant coating 16 is formed. Only
limited regions of wear resistant coating 16 and component body 12
are shown in FIG. 1 for clarity. Component body 12 can have any
number and type of structural features, which may be present prior
to formation of wear resistant coating 16 or which may be defined
via machining operations carried-out during the below-described
coating formation process. To further illustrate this point, the
illustrated region of coated component 10 is depicted to include a
cavity, bore, depression, or channel 18, which is partially shown
and which or may not penetrate fully through component body 12. As
generically illustrated in FIG. 1, component body 12 can be any
article of manufacture over which wear resistant coating 16 is
usefully formed; e.g., in one embodiment, component body 12 may be
a mud rotor shaft having a lobed outer surface, as described below
in conjunction with FIG. 2.
[0029] Wear resistant coating 16 contains a precipitation-hardened
alloy body 20, which is produced over component surface 14
utilizing a combination of deposition, machining, and heat
treatment processes. Wear resistant coating 16 may consist wholly
or entirely of alloy body 20 in certain implementations. In other
embodiments, wear resistant coating 16 may contain one or more
additional material layers, such as a bondcoat or a barrier layer,
which may be combined with alloy body 20 in a stacked relationship.
In such embodiments, precipitation-hardened alloy body 20 will
typically be the outermost layer or portion of wear resist coating
16 and may consequently be considered a topcoat; however, the
possibility that another layer of material, such as a relatively
thin, solid film lubricant layer, may be formed over alloy body 20
in alternative implementations of coating 16 is not precluded.
Precipitation-hardened alloy body 20 may or may not directly
contact component surface 14, depending upon whether wear resistant
coating 16 is produced to contain a bondcoat, barrier layer, or
other material layer between coating 16 and component surface 14.
Wear resistant coating 16 may have an average thickness ranging
from 2 to 10 microns (.mu.m) in an embodiment. In other
embodiments, coating 16 may be thicker or thinner than the
aforementioned range.
[0030] Precipitation-hardened alloy body 20 may be composed of any
material or combination of materials providing the desired wear
resistance properties, while also being susceptible to precipitate
hardening through heat treatment. As previously indicated,
precipitation-hardened alloy body 20 is usefully composed of an XP
alloy, with "X" representing Co, Ni, or a combination thereof. As a
specific example, precipitation-hardened alloy body 20 may contain
at least 50% X and between about 5% and about 25% P, by weight, in
embodiments. In other implementations, precipitation-hardened alloy
body 20 may be consist essentially of X and P; and, perhaps, may
contain about 10% to about 15% P, by weight, with the remainder of
alloy body 20 composed of X. The particular formulation or
composition of precipitation-hardened alloy body 20 will vary among
embodiments depending, at least in part, upon the desired
properties of wear resistant coating 16, the intended operational
environment of coated component 10, the technique utilized to
deposit alloy body 20, cost considerations, and other such factors.
When precipitation-hardened alloy body 20 is composed of an XP
alloy, Ni may be favored over Co for cost saving purposes,
particularly when the pre-hardened alloy body is deposited
utilizing an electroplating process. Accordingly, precipitation
hardened alloy body 20 may be predominately composed of Ni, by
weight, with the remainder of alloy body 20 composed of Co, P, or a
combination thereof in embodiments. If desired, micro-size or
nano-size particles may be embedded in precipitation-hardened alloy
body 20 by, for example, co-deposition during plating to enhance or
tailor certain properties of alloy body 20. Again, as indicated
above and described more fully below, precipitation-hardened alloy
body 20 is suitably deposited utilizing an electroplating process;
however, other deposition techniques can be equivalently
utilized.
[0031] Precipitation-hardened alloy body 20 may be deposited as a
single layer or as multiple layers. For example, as indicated in
FIG. 1 by dashed line 22, precipitation-hardened alloy body 20 may
be deposited as a first XP alloy layer 24 and as second,
subsequently-deposited XP alloy layer 26. When so formed, XP alloy
layers 24, 26 may or may not have substantially equivalent
thicknesses, morphologies, and/or formulations. In one approach,
first XP alloy layer 24 is electrodeposited over component surface
14 utilizing a first plating bath chemistry; the partially-coated
component is removed from the plating bath, machined, and returned
to the same or a similar plating bath; and second XP alloy layer 26
is then electrodeposited over first XP alloy layer 24. As discussed
below in conjunction with FIG. 3, such an approach may be useful
when precipitation-hardened alloy body 20 is deposited at
relatively high thicknesses and is prone to nodular growth. In this
case, nodule growth can occur near edges, corners, and similar
topological features of component surface 14 as the electroplating
process progresses. Localized irregulates or nodular protuberances
can consequently develop, grow, and potentially scavenge the
plating current, obstruct features having smaller dimensions, and
cause similar issues. As a more specific example, in an embodiment
in which channel 18 exists prior to the coating formation process
(as opposed to being formed after the coating formation process by
drilling or other machining), localized growth can occur near the
mouth of channel 18 and may potentially pinch-off or obstruct
channel 18 if not removed. By temporarily halting the plating
process, grinding or otherwise removing such regions of localized
growth, and then resuming the plating process, this can be avoided.
In other embodiments, alloy body 20 can be deposited in three or
more layers, with any number and type of machining operations
interspersed with the layer deposition steps.
[0032] Wear resistant coating 16 may be fabricated to contain one
or more additional layers in addition to precipitation-hardened
alloy body 20 in at least some embodiments of coated component 10.
This possibility is illustrated in FIG. 1, which depicts wear
resistant coating 16 as further containing a barrier layer 28
provided between alloy body 20 and component surface 20. Barrier
layer 28 is formulated to prevent or at least deter penetration of
contaminants through the thickness of coating 16; that is, along an
axis orthogonal to outer surface 30 of wear resistant coating 16
corresponding to the Y-axis identified in FIG. 1 by coordinate
legend 34. In so doing, barrier layer 28 shields coated component
10 from exposure to such contaminants during usage to reduce
corrosion or other degradation of underlying component body 12. To
enable barrier layer 28 to provide this function, barrier layer 28
is beneficially formulated to experience minimal or no precipitate
hardening during the below-described heat treatment process.
[0033] In implementations in which precipitation-hardened alloy
body 20 is composed of an XP alloy, barrier layer 28 may be
composed of an alloy containing an increased amount of X and/or a
lesser amount of P as compared to alloy body 20. For example, in an
embodiment in which precipitation-hardened alloy body 20 contains
first amount of P and a first amount of Ni, barrier layer 28 may
contain a second amount of P less than the first amount of P (and
possibly being zero) and second amount of Ni exceeding the first
amount of Ni. In at least some instances, barrier layer 28 may
consist essentially of pure Ni; the term "consist essentially," as
appearing herein, indicating that a named layer or body (here,
barrier layer 28) contains a minimum of 99% of a named constituent
(here, Ni), by weight. Similarly, in embodiments in which
precipitation-hardened alloy body 20 contains P and a first amount
of Co, barrier layer 28 may contain a second amount of P less than
the first amount of P (possibly 0% P, by weight) and a second
amount of Co exceeding the first amount of Co; e.g., barrier layer
28 may consist essentially of pure Co. When provided, barrier layer
28 usefully, but non-essentially has a thickness equal to or less
than that of precipitation-hardened alloy body 20. For example, in
one embodiment, a barrier layer 28 may be formed to have a global
average thickness between 4 and about 8 .mu.m, while alloy body 20
has a global average thickness greater than that of barrier layer
28.
[0034] As noted above, wear resistant coating 16 need not contain a
discrete or separately-formed barrier layer in all instances.
Instead, in alternative embodiments, wear resistant coating 16 can
be imparted with a barrier layer functionality by strategically
varying the composition of precipitation-hardened alloy body 20
through its thickness; that is, as taken along an axis orthogonal
to the outer surface of alloy body 20 corresponding to the Y-axis
in coordinate legend 34 (FIG. 1). This, in effect, may create
certain bands or regions within precipitation-hardened alloy body
20, which possess a reduced susceptibility to precipitate hardening
and thus better retain the ability to act as a shield or sealant
deterring the penetration of environmental contaminants through
coating 16 and to component body 12. For example, when composed of
an XP alloy, precipitation-hardened alloy body 20 can be deposited
to have a varied P content through its thickness, noting that the
bands of alloy body 20 having a decreased P content will typically
be more resistive to P-phase formation and grain growth induced by
precipitate hardening. As a still further possibility, the
above-described approaches can be combined such that wear resistant
coating 16 contains a barrier layer, while precipitation-hardened
alloy body 20 has a varied P content and thus selectively resists
grain growth through its thickness.
[0035] In embodiments, precipitation-hardened alloy body 20
possesses a maximum P content at or adjacent outer surface 30 of
alloy body 20, which may correspond to location L.sub.1 identified
in FIG. 1. When moving through alloy body 20 toward component body
12, the P content of precipitation-hardened alloy body 20 may
decrease in a gradual or stepped fashion to a minimum value or
local minima. In at least some instances, this minimum value may be
located at or adjacent inner surface 32 of alloy body 20, which may
correspond to location L.sub.2 in FIG. 1. For example, in an
embodiment, the minimum P content at location L.sub.2 may be at
least one half the P content at location L.sub.1, considered by
weight percentage. Further, while the minimum P content at location
L.sub.2 will typically be greater than zero in such embodiments,
the minimum P content at location L.sub.2 may be closer to zero
weight percentage than to the P content at location L.sub.1. When
an electroplating process is utilized to deposit alloy body 20,
such variations in P concentration, whether present in a gradual or
more stepped distribution, can be created by adjusting process
parameters, such as current density, in situ during the
electroplating process. To provide a specific example, the current
density may be first maintained at a relatively low level to
deposit the initially-plated portion of alloy body 20 to contain a
minimum P content. Afterwards, the current density may be boosted
to deposit the remainder of precipitation-hardened alloy body 20 to
contain an increased P content as alloy body 20 is gradually
compiled or build-up over component surface 14 and barrier layer
28, if present. In still further embodiments, the P content of
precipitation-hardened alloy body 20 may vary in another manner
(e.g., such that alloy body 20 has a minimum P content between
locations L.sub.1 and L.sub.2 identified in FIG. 1) or alloy body
20 may have a substantially uniform P content through its
thickness.
[0036] In the embodiment shown in FIG. 1, coated component 10 is
illustrated in a highly generalized manner to emphasize that
underlying component body 12 can assume virtually any desired shape
or physical form. Similarly, wear resistant coating 16 can be
formed over any type of component, regardless of application or
usage. This notwithstanding, wear resistant coating 16 may be
particularly beneficial when formed over components subject to high
wear conditions or corrosive environments during usage. In this
regard, FIG. 2 illustrates a coated component in the form of a mud
rotor shaft 36, which is contained in the power section of a
downhole mud rotor 38 (partially shown). As indicated by gap 40,
mud rotor shaft 36 can have any desired length, which may approach
or exceed 10 meters in implementations. Additionally, multiple mud
rotor shafts 36 may be ganged together or joined in series to span
the full depth of a given well. In addition to mud rotor shaft 36,
downhole mud rotor 38 further includes a tubular stator casing 42
and an inner tubular sleeve 44, which may be composed of a rubber
or another polymer. The interior of sleeve 44 is threaded or lobbed
in a twisting or spiral pattern. The twisting, lobed interior
geometry of sleeve 44 combines with the twisting, lobed outer
geometry of mud rotor shaft 36 to form a sealed cavity, which
varies in location as rotor shaft 36 rotates with respect to sleeve
44 and casing 42. During operation of downhole mud rotor 38, a
pressurized liquid is delivered into the sealed cavity, which
varies in shape and location as rotor shaft 36 rotates, to drive
rotation of rotor shaft 36 and a non-illustrated bit in which mud
rotor 38 terminates.
[0037] During mud rotor operation, relatively severe frictional
forces or harsh abrasive forces may be exerted between the mating
surfaces of mud rotor shaft 36 and sleeve 44. To stave-off
premature wear of rotor shaft 36 and sleeve 44, a wear resistant
coating 46 is formed over the outer lobed surface of rotor shaft
36. As shown in FIG. 2, wear resistant coating 46 may be considered
analogous to wear resistant coating 16 described above in
conjunction with FIG. 1, and the combination of wear resistant
coating 46 and rotor shaft 36 may be considered an example of a
"coated component." Wear resistant coating 46 and, specifically,
the precipitation-hardened alloy body contained in coating 46
(corresponding to alloy body 20 shown in FIG. 1) can be imparted
with a highly smooth surface finish by machining prior to
precipitate hardening of the alloy body. For example, in an
embodiment, grinding or polishing may be performed to impart
coating 46 with a surface finish finer than 1 .mu.m (approximately
40 .mu.in) and, perhaps, a surface finish equivalent to or finer
than 0.4 microns (approximately 15 .mu.in). Such a highly smooth
surface enhances the integrity of the seal formed between rotor
shaft 36 and sleeve 44, while concurrently minimizing abrasion of
sleeve 44 during rotation of rotor shaft 36. An exemplary method
for forming wear resistant coating 46 shown in FIG. 2, wear
resistant coating 16 shown in FIG. 1, or a similar wear resistant
coating will now be described in conjunction with FIG. 3.
[0038] Examples of a Method for Producing a Coated Component
[0039] FIG. 3 is a flowchart setting-forth an exemplary coating
formation method 48, which can be carried-out to form a wear
resistant coating over selected surfaces of one or more components.
In the illustrated example, coating formation method 48 includes a
number of process steps identified as STEPS 50, 52 54, 56, 58, 60,
62. Depending upon the particular manner in which coating formation
method 48 is implemented, each illustrated step (STEPS 50, 52 54,
56, 58, 60, 62) may entail a single process or multiple
sub-processes. Further, the steps shown in FIG. 3 and described
below are offered purely by way of non-limiting example. In
alternative embodiments of coating formation method 48, additional
process steps may be performed, certain steps may be omitted,
and/or the illustrated steps may be performed in alternative
sequences. For ease of explanation, method 48 will be described
with reference to coated component 10 shown in FIG. 1.
[0040] Coating formation method 48 commences at STEP 50 during
which the component or components to be coated are obtained by, for
example, purchase from a third party supplier or by independent
fabrication. Selected surfaces of the components are also prepared
for deposition of the wear resistant coating. Surface preparation
involve cleaning, such as treatment with acid to dissolve surface
oxides or degreasing. Grinding may be performed to improve surface
finish. Afterwards, a barrier layer (e.g., barrier layer 28 shown
in FIG. 1) can be plated or otherwise deposited over the component
surfaces, if desired (STEPS 52, 54). For example, in embodiments in
which the later-deposited alloy body precursor contains Ni, a
barrier layer having a relatively high Ni content, and possibly
consisting essentially of Ni, may be plated onto selected surfaces
of the components. Conversely, in embodiments in which the
subsequently-deposited alloy body precursor contains Co, a barrier
layer having a relatively high Co content, if not consisting
essentially of Co, may be plated onto selected component surfaces.
In other embodiments, if a barrier layer is not desirably formed
over the components, method 48 may advance directly to STEP 56, as
described below.
[0041] During STEP 56 of coating formation method 48, the
precipitation-hardened alloy body is electroplated or otherwise
deposited over targeted surfaces of the processed component(s).
When an electroplating process is employed, the particular
parameters and plating bath chemistries of the electroplating
process may vary among embodiments. However, as a non-limiting
example in implementations in which the alloy body is desirably
composed of an XP alloy, a liquid additive, a powder additive,
and/or dissolvable anodes can be utilized to provide the source of
X ions during the plating process. For example, in certain
embodiments, Ni ions may be supplied in the form of a chemical
additive (e.g., a Ni sulfate compound) introduced into the plating
bath, in which case inert (e.g., platinum-plated titanium) anodes
may be inserted into the NiW plating bath and energized to drive
the electroplating process. In other implementations, the Ni ion
source may be provided utilizing consumable or soluble Ni anodes,
which are replenished as needed during the electroplating process.
Comparatively, Co ions may be provided as a water-soluble additive,
such as Co sulfate (CoSO.sub.4.7H.sub.2O). P ions can likewise be
provided utilizing suitable chemical species and, in an embodiment,
may be supplied by breakdown of phosphorous acid (H.sub.3PO.sub.3)
added to plating bath solution. The plating bath chemistry may also
be formulated to include other ingredients or constituents
including pH balancing agents and/or chelating agents, such as
organic acids. Other bath formulations are also possible, with fine
tuning of other parameters (e.g., temperatures and agitation
intensities) performed as appropriate for a particular plating bath
operation.
[0042] Advancing next to STEP 58 of coating formation method 48,
machining of the newly-deposited alloy body or layer is conducted.
Generally, conventional tooling and processes can be utilized to
machine alloy body 20 in its pre-hardened or soft state in which
alloy body 20 may have a relatively hardness value on the order of,
for example, 500 to 600 HV. Such machining operations may be
performed to define detailed structural features in alloy body 20
and component body 12, as desired. For example, in an embodiment,
mechanical drilling, laser drilling, water jetting, electro
discharge machining, or the like may be performed to form channel
18 in bodies 12, 20, as shown in FIG. 1. Additionally or
alternatively, grinding or polishing may be performed to impart
outer surface 30 with a highly smooth surface finish, such as a
surface finish having an average roughness less than 0.4 microns
(approximately 15 .mu.in) RA. As further indicated in FIG. 3 by
STEPS 56, 58, 60, such process steps can be repeated, as
appropriate, until a desired alloy body thickness is achieved.
[0043] After achieving the desired thickness, coating formation
method 48 advances to STEP 62 and heat treatment is performed to
precipitate harden alloy body 20. In embodiments in which component
body 12 is desirably annealed (e.g., as may be the case when
component body 12 is composed of a cold-worked metal or alloy, such
as steel), a single heat treatment process can be carried-out to
precipitate harden alloy body 20, while concurrently annealing
component body 12. The particular parameters of the heating
schedule employed will vary depending upon the composition of alloy
body 20 and whether component body 12 is desirably annealed.
However, in at least some embodiments, heat treatment may be
performed at peak temperature between 250 and 450 degrees Celsius
for a time period ranging from 2 to 24 hours. After heat treatment
and precipitate hardening, the hardness value of alloy body 20
beneficially exceeds 950 HV and, in certain instances, may have
been increased by a factor of two or more. Coating formation method
48 concludes following STEP 62, and can be repeated, as needed, to
form additional wear resistant coatings over other components in
the above-described manner.
CONCLUSION
[0044] There has thus been provided embodiments of wear resistant
coatings, coated components protected by wear resistant coatings,
and methods for forming wear resistant coatings. The wear resistant
coatings contain precipitation-hardened alloy bodies, which are
initially deposited in a pre-hardened and subsequently
precipitation hardened to greatly enhance the final hardness of the
alloy bodies. By initially depositing the alloy bodies in a
pre-hardened state, machining as appropriate, and subsequently
precipitate hardening the alloy bodies, wear resistant coatings can
be fabricated having relatively high hardness values, while
facilitating the coating formation process; in particular, while
facilitating machining of the coating to define refined structural
features, to achieve highly smooth surface finishes, to satisfy
stringent dimensional tolerances, or the like. Process efficiency
can also be enhanced by precipitate hardening the alloy body, while
concurrently annealing the underlying substrate or component
utilizing a single heat treatment process in embodiments. The wear
resistant coating may consist solely of the precipitation-hardened
alloy body or, instead, may contain one or more additional layers,
such as a barrier layer formed between the precipitation-hardened
alloy body and the underlying component.
[0045] Terms such as "comprise," "include," "have," and variations
thereof are utilized herein to denote non-exclusive inclusions.
Such terms may thus be utilized in describing processes, articles,
apparatuses, and the like that include one or more named steps or
elements, but may further include additional unnamed steps or
elements. While at least one exemplary embodiment has been
presented in the foregoing Detailed Description, it should be
appreciated that a vast number of variations exist. It should also
be appreciated that the exemplary embodiment or exemplary
embodiments are only examples, and are not intended to limit the
scope, applicability, or configuration of the invention in any way.
Rather, the foregoing Detailed Description will provide those
skilled in the art with a convenient road map for implementing an
exemplary embodiment of the invention. Various changes may be made
in the function and arrangement of elements described in an
exemplary embodiment without departing from the scope of the
invention as set-forth in the appended Claims.
* * * * *