U.S. patent application number 13/932228 was filed with the patent office on 2015-01-01 for fluorinated polymer based coatings and methods for applying the same.
This patent application is currently assigned to General Electric Company. The applicant listed for this patent is General Electric Company. Invention is credited to Krishnamurthy Anand, Kalaga Murali Krishna, Surinder Singh Pabla, Padmaja Parakala.
Application Number | 20150003996 13/932228 |
Document ID | / |
Family ID | 50981019 |
Filed Date | 2015-01-01 |
United States Patent
Application |
20150003996 |
Kind Code |
A1 |
Krishna; Kalaga Murali ; et
al. |
January 1, 2015 |
FLUORINATED POLYMER BASED COATINGS AND METHODS FOR APPLYING THE
SAME
Abstract
Coatings includes about 60 weight percent to about 90 weight
percent of one or more fluorinated polymers, about 1 weight percent
to about 7 weight percent of one or more erosion resistant fillers
about 3 weight percent to about 9 weight percent of one or more
anticorrosive pigments, about 1 weight percent to about 4 weight
percent of one or more thixotropic agents, and about 1 weight
percent to about 4 weight percent of one or more porosity reducing
filler materials.
Inventors: |
Krishna; Kalaga Murali;
(Bangalore, IN) ; Parakala; Padmaja; (Bangalore,
IN) ; Pabla; Surinder Singh; (Greer, SC) ;
Anand; Krishnamurthy; (Bangalore, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Assignee: |
General Electric Company
|
Family ID: |
50981019 |
Appl. No.: |
13/932228 |
Filed: |
July 1, 2013 |
Current U.S.
Class: |
416/241R ;
427/385.5; 428/141; 428/220; 428/421; 524/1; 524/404; 524/405;
524/406; 524/417; 524/420; 524/423; 524/425; 524/428; 524/439;
524/442; 524/443; 524/444; 524/449; 524/451; 524/545; 524/546;
524/612 |
Current CPC
Class: |
Y10T 428/24355 20150115;
F01D 5/286 20130101; Y10T 428/3154 20150401; C09D 127/12 20130101;
F01D 5/28 20130101; C08K 3/013 20180101; C09D 127/12 20130101; F01D
5/288 20130101 |
Class at
Publication: |
416/241.R ;
524/546; 524/612; 524/1; 524/545; 524/443; 524/404; 524/406;
524/428; 524/439; 524/417; 524/420; 524/405; 524/449; 524/442;
524/444; 524/423; 524/425; 524/451; 427/385.5; 428/220; 428/421;
428/141 |
International
Class: |
F01D 5/28 20060101
F01D005/28 |
Claims
1. A coating comprising: about 60 weight percent to about 90 weight
percent of one or more fluorinated polymers; about 1 weight percent
to about 7 weight percent of one or more erosion resistant fillers;
about 3 weight percent to about 9 weight percent of one or more
anticorrosive pigments; about 1 weight percent to about 4 weight
percent of one or more thixotropic agents; and, about 1 weight
percent to about 4 weight percent of one or more porosity reducing
filler materials.
2. The coating of claim 1, wherein the one or more fluorinated
polymers are selected from a group consisting of
polytetrafluoroethylenes, perfluoroalkoxy polymers, ethylene
tetrafluoroethylenes, polyvinylidene fluorides and polyvinyl
fluorides.
3. The coating of claim 1, wherein the one or more erosion
resistant fillers are selected from a group consisting of alumina,
silica, boron carbide, silicon carbide, titania, tungsten carbide,
aluminium nitride, boron nitride, and silicon nitride.
4. The coating of claim 1, wherein the one or more anticorrosive
pigments are selected from a group consisting of zinc dust, zinc
phosphates, iron sulphide, borates, precipitated silica and
titanium dioxide.
5. The coating of claim 1, wherein the one or more thixotropic
agents are selected from a group consisting of montmorillonite,
mica, and silicon fumes.
6. The coating of claim 1, wherein the one or more porosity
reducing filler materials are selected from a group consisting of
barium sulphate, calcium sulphate, talc, and calcium carbonate.
7. The coating of claim 1, wherein the coating is from about 10
.mu.m to about 60 .mu.m thick.
8. The coating of claim 1 further comprising a plurality of layers,
wherein each layer comprises about 60 weight percent to about 90
weight percent of one or more fluorinated polymers; about 1 weight
percent to about 7 weight percent of one or more erosion resistant
fillers; about 3 weight percent to about 9 weight percent of one or
more anticorrosive pigments; about 1 weight percent to about 4
weight percent of one or more thixotropic agents; and, about 1
weight percent to about 4 weight percent of one or more porosity
reducing filler materials.
9. The coating of claim 1, wherein the erosion resistant fillers,
anticorrosive pigments, thixotropic agents and the porosity
reducing filler materials all have an average particle size less
than or equal to about 50 .mu.m and have a maximum individual
particle size less than or equal to about 100 .mu.m
10. The coating of claim 1, wherein the coating withstands
temperatures of at least 300.degree. C.
11. The coating of claim 1, wherein a porosity of the coating is
less than or equal to about 1 percent by volume.
12. The coating of claim 1, wherein a surface roughness of the
coating is from about 5 Ra to about 20 Ra.
13. The coating of claim 1, wherein the coating is hydrophobic and
oleophobic such that it has a contact angle of from about 90
degrees to about 140 degrees.
14. A coated article comprising: a substrate piece comprising an
outer surface; and a coating covering at least a portion of the
outer surface of the substrate piece, wherein the coating
comprises: about 60 weight percent to about 90 weight percent of
one or more fluorinated polymers; about 1 weight percent to about 7
weight percent of one or more erosion resistant fillers; about 3
weight percent to about 9 weight percent of one or more
anticorrosive pigments; about 1 weight percent to about 4 weight
percent of one or more thixotropic agents; and, about 1 weight
percent to about 4 weight percent of one or more porosity reducing
filler materials.
15. The coated article of claim 14, wherein the substrate piece
comprises a compressor blade for a turbine.
16. The coated article of claim 14, wherein the outer surface of
the substrate comprises a base coat such that the coating covers at
least a portion of the base coat.
17. A method for coating a substrate with a coating, the method
comprising: applying a coating onto an outer surface of the
substrate, wherein the coating comprises: about 60 weight percent
to about 90 weight percent of one or more fluorinated polymers;
about 1 weight percent to about 7 weight percent of one or more
erosion resistant fillers; about 3 weight percent to about 9 weight
percent of one or more anticorrosive pigments; about 1 weight
percent to about 4 weight percent of one or more thixotropic
agents; and, about 1 weight percent to about 4 weight percent of
one or more porosity reducing filler materials; and, curing the
coating on the outer surface of the substrate at a curing
temperature of from about 50.degree. C. to about 300.degree. C.
18. The method of claim 17, wherein the coating has a viscosity of
from about 0.1 Pascal-second to about 0.15 Pascal-second prior to
curing.
19. The method of claim 17 further comprising applying an
additional layer of the coating, wherein the additional layer of
the coating comprises: about 60 weight percent to about 90 weight
percent of one or more fluorinated polymers; about 1 weight percent
to about 7 weight percent of one or more erosion resistant fillers;
about 3 weight percent to about 9 weight percent of one or more
anticorrosive pigments; about 1 weight percent to about 4 weight
percent of one or more thixotropic agents; and, about 1 weight
percent to about 4 weight percent of one or more filler materials;
and, curing the additional layer of the coating at an additional
curing temperature of from about 50.degree. C. to about 300.degree.
C.
20. The method of claim 19 wherein the additional curing
temperature is higher than the first curing temperature.
Description
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates to coatings and,
more specifically, to fluorinated polymer based coatings that can
be applied to compressor blades of turbines.
[0002] In a gas turbine engine, the compressor section generally
includes multiple stages that have a row of compressor blades (also
referred to as "rotor blades" or "rotor airfoils") and stator
blades (also referred to as "stator airfoils"). The compressor
blades rotate about a rotor and, thusly, impart kinetic energy to
the airflow through the compressor. Directly following the row of
compressor blades is a row of stator blades, which remain
stationary. Acting in concert, the compressor blades and stator
blades turn the airflow and slow the air velocity, respectively,
which can increase the static pressure of the airflow through the
compressor section. Multiple stages of compressors blades and
stator blades can be stacked in an axial flow compressor to achieve
the required discharge to inlet air pressure ratio. Compressor and
stator blades can thus be secured to rotor wheels and the stator
case, respectively, by means of a dovetail or root or base
attachment.
[0003] In operations, compressor blades may be subject to
mechanical stresses and harsh operating conditions because of the
rotational velocity of the compressor. These levels of stress
combined with the other operating conditions may affect the
experienced levels of erosion or corrosion. For example, the
ambient air pulled in through the compressor section can include
constituents that may be corrosive and abrasive to the compressor
blades and other such parts. Some components may further be subject
to mixtures of hydrocarbon-based lubricating oils, carbonaceous
soot, dirt, rust and the like.
[0004] Coatings such as polytetrafluoroethylenes (PTFEs) may be
applied to articles such as compressor blades to provide additional
protection against these elements. However, as coating thickness
increases aerodynamic performance may be affected.
[0005] Accordingly, alternative fluorinated coatings would be
welcome in the art.
BRIEF DESCRIPTION OF THE INVENTION
[0006] In one embodiment, a coating is disclosed. The coating
includes about 60 weight percent to about 90 weight percent of one
or more fluorinated polymers, about 3 weight percent to about 5
weight percent of one or more erosion resistant fillers about 5
weight percent to about 7 weight percent of one or more
anticorrosive pigments, about 1 weight percent to about 4 weight
percent of one or more thixotropic agents, and, about 2 weight
percent to about 3 weight percent of one or more porosity reducing
filler materials.
[0007] In another embodiment, a coated article is disclosed. The
coated article includes a substrate piece comprising an outer
surface; and a coating covering at least a portion of the outer
surface of the substrate piece. The coating includes about 60
weight percent to about 90 weight percent of one or more
fluorinated polymers, about 1 weight percent to about 7 weight
percent of one or more erosion resistant fillers, about 3 weight
percent to about 9 weight percent of one or more anticorrosive
pigments, about 1 weight percent to about 4 weight percent of one
or more thixotropic agents, and, about 1 weight percent to about 4
weight percent of one or more porosity reducing filler
materials.
[0008] In yet another embodiment, a method for coating a substrate
with a coating is disclosed. The method includes applying a coating
onto an outer surface of the substrate. The coating includes about
60 weight percent to about 90 weight percent of one or more
fluorinated polymers, about 1 weight percent to about 7 weight
percent of one or more erosion resistant fillers, about 3 weight
percent to about 9 weight percent of one or more anticorrosive
pigments, about 1 weight percent to about 4 weight percent of one
or more thixotropic agents, about 1 weight percent to about 4
weight percent of one or more porosity reducing filler materials.
The method further includes curing the coating on the outer surface
of the substrate at a curing temperature of from about 50.degree.
C. to about 300.degree. C.
[0009] These and additional features provided by the embodiments
discussed herein will be more fully understood in view of the
following detailed description, in conjunction with the
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The embodiments set forth in the drawings are illustrative
and exemplary in nature and not intended to limit the inventions
defined by the claims. The following detailed description of the
illustrative embodiments can be understood when read in conjunction
with the following drawings, where like structure is indicated with
like reference numerals and in which:
[0011] FIG. 1 is a cross-sectional schematic illustration of a
coating on a substrate according to one or more embodiments shown
or described herein;
[0012] FIG. 2 is a cross-sectional schematic illustrate of a
coating on a substrate with a base coat there between according to
one or more embodiments shown or described herein;
[0013] FIG. 3 is a perspective view of a compressor blade with a
coating according to one or more embodiments shown or described
herein; and,
[0014] FIG. 4 is an exemplary illustrate of a coating method
according to one or more embodiments shown or described herein.
DETAILED DESCRIPTION OF THE INVENTION
[0015] One or more specific embodiments of the present invention
will be described below. In an effort to provide a concise
description of these embodiments, all features of an actual
implementation may not be described in the specification. It should
be appreciated that in the development of any such actual
implementation, as in any engineering or design project, numerous
implementation-specific decisions must be made to achieve the
developers' specific goals, such as compliance with system-related
and business-related constraints, which may vary from one
implementation to another. Moreover, it should be appreciated that
such a development effort might be complex and time consuming, but
would nevertheless be a routine undertaking of design, fabrication,
and manufacture for those of ordinary skill having the benefit of
this disclosure.
[0016] When introducing elements of various embodiments of the
present invention, the articles "a," "an," "the," and "said" are
intended to mean that there are one or more of the elements. The
terms "comprising," "including," and "having" are intended to be
inclusive and mean that there may be additional elements other than
the listed elements.
[0017] Modified fluorinated polymeric coatings may be provided to
protect underlying substrates from a variety of external forces and
environmental conditions. Furthermore, by combining select
additives with the fluorinated polymer(s) in regulated particle
size distributions, a thin, smooth coating with high adhesion can
be provided to protect the substrate without inhibiting aerodynamic
performance. These coatings may be used both for new make articles
or modifying applications (e.g., repair) to potentially promote
longer and/or more efficient operational performance.
[0018] Referring now to FIG. 1, a schematic representation of a
cross section of a coated article 5 is illustrated comprising at
least a substrate 15 and a coating 10.
[0019] The coating 10 is formulated such that it withstands
elevated temperatures, and has sufficient adhesion, porosity,
surface roughness and hydrophobic and oleophobic properties to
protect the underlying substrate 15 while still enabling at least
sufficient operational performance. The coating can generally
comprise about 60 weight percent to about 90 weight percent of one
or more fluorinated polymers, about 1 weight percent to about 7
weight percent of one or more erosion resistant fillers, about 3
weight percent to about 9 weight percent of one or more
anticorrosive pigments, about 1 weight percent to about 4 weight
percent of one or more thixotropic agents, and about 1 weight
percent to about 4 weight percent of one or more porosity reducing
filler materials.
[0020] The fluorinated polymers of the coating 10 can comprise any
one or more fluorocarbon based polymers. Exemplary fluorinated
polymers include, but are not limited to, PTFE
(polytetrafluoroethylene), PFA (perfluoroalkoxy polymer), ETFE
(ethylene tetrafluoroethylene), PVDF (polyvinylidene fluoride) and
PVF (polyvinyl fluoride). The one or more fluorinated polymers in
total can comprise from about 60 weight percent to about 90 weight
percent of the coating 10, or from about 70 weight percent to about
80 weight percent of the coating 10.
[0021] The erosion resistant fillers of the coating 10 can comprise
any material that increases the crack resistance of the overall
coating 10. Exemplary erosion resistant fillers include, but are
not limited to, alumina, silica, boron carbide, silicon carbide,
titania, tungsten carbide, aluminium nitride, boron nitride, and
silicon nitride. The one or more erosion resistant fillers in total
can comprise from about 1 weight percent to about 7 weight percent
of the coating 10, or from about 3 weight percent to about 5 weight
percent of the coating 10.
[0022] The anticorrosive pigments of the coating 10 can comprise
any material that helps prevent the corrosion of the overall
coating 10. Exemplary anticorrosive pigments include, but are not
limited to, zinc dust, zinc phosphates, iron sulphide, borates,
precipitated silica and titanium dioxide. The one or more
anticorrosive pigments in total can comprise from about 3 weight
percent to about 9 weight percent of the coating 10, or about from
5 weight percent to about 7 weight percent of the coating 10.
[0023] The thixotropic agent or agents of the coating 10 can
comprise any material that modifies the viscosity of the overall
coating 10. Exemplary thixotropic agents include, but are not
limited to, montmorillonite, mica and silicon fumes. The one or
more thixotropic agents in total can comprise from about 1 weight
percent to about 4 weight percent of the coating 10, or about from
2 weight percent to about 3 weight percent of the coating 10.
[0024] The porosity reducing filler materials of the coating 10 can
comprise any filler material that decreases the porosity of the
overall coating 10. Exemplary porosity reducing filler materials
include, but are not limited to, barium sulphate, calcium sulphate,
talc, and calcium carbonate. In some embodiments the porosity
reducing filler materials can comprise one or more of the
aforementioned fluorinated polymers, erosion resistant fillers,
anticorrosive pigments and/or thixotropic agents. The one or more
porosity reducing filler materials in total can comprise from about
1 weight percent to about 4 weight percent of the coating 10, or
about from about 2 weight percent to about 3 weight percent of the
coating 10.
[0025] In some embodiments, the coating 10 can comprise one or more
additional materials. For example, the coating 10 may further
comprise additional fillers including, but not limited to, carbon
black. In some embodiments, the coating 10 may further comprise
molybdenum sulfide, such as from about 5 weight percent to about 10
weight percent, to increase wear resistance. In some embodiments,
the coating 10 may comprise from about 2 weight percent to about 5
weight percent graphite or bronze fines to reduce friction. In even
some embodiments, the coating 10 may further comprise ceramic
nanoparticles, (e.g., zirconia fines) for up to 10 weight percent
to increase compressive strength. While certain elements have been
listed herein, it should be appreciated that these are non-limiting
examples and other material(s) may additionally or alternatively be
included.
[0026] Still referring to FIG. 1, the coating 10 can comprise a
variety of thicknesses to protect an underlying substrate 15. For
example, in some embodiments the coating 10 can be from about 10
.mu.m to about 60 .mu.m thick. In some embodiments, the coating 10
can comprise a plurality of layers. In such embodiments, each layer
can comprise about 60 weight percent to about 90 weight percent of
one or more fluorinated polymers; about 3 weight percent to about 5
weight percent of one or more erosion resistant fillers; about 5
weight percent to about 7 weight percent of one or more
anticorrosive pigments; about 1 weight percent to about 4 weight
percent of one or more thixotropic agents; and, about 2 weight
percent to about 3 weight percent of one or more porosity reducing
filler materials.
[0027] In some embodiments, the outer surface 17 of the substrate
15 may comprise the base alloy of the component itself such that
the coating 10 is applied directly thereto. However, referring now
to FIG. 2, in some embodiments, the outer surface 17 of the
substrate may comprise one or more base coats 19 that were applied
to the substrate 15 prior to applying the layer of coating 10 which
itself comprises about 60 weight percent to about 90 weight percent
of one or more fluorinated polymers, about 3 weight percent to
about 5 weight percent of one or more erosion resistant fillers,
about 5 weight percent to about 7 weight percent of one or more
anticorrosive pigments, about 1 weight percent to about 4 weight
percent of one or more thixotropic agents, and about 2 weight
percent to about 3 weight percent of one or more porosity reducing
filler materials as discussed above. The base coat 19 can comprise,
for example, any coating that assists in the overall adhesion
between the underlying substrate 15 and the subsequent coating(s)
10.
[0028] For example, a base coat 19 may comprise any material with
galvanic compatibility with the substrate 15 to provide a
supporting layer of protection in the event that the subsequently
applied coating 10 is lost during operation. The base coat in such
embodiments may comprise a thickness range, for example, of from
about 5 .mu.m to about 20 .mu.m.
[0029] Furthermore, in some embodiments, the non fluorinated
polymer elements of the coating can possess reduced particle size
to assist in the functional properties of the overall coating.
Specifically, the erosion resistant fillers, anticorrosive
pigments, thixotropic agents and the porosity reducing filler
materials can all have an average particle size ranging from nano
to micron levels to less than or equal to about 50 .mu.m.
Furthermore, the erosion resistant fillers, anticorrosive pigments,
thixotropic agents and the porosity reducing filler materials can
have a maximum individual particle size less than or equal to about
100 .mu.m. These combinations of elements with the aforementioned
particle size distributions can combine to produce a coating with a
plurality of functional properties including hydrophobicity and
oleophobicity while still providing corrosion, erosion and fouling
resistance to an underlying substrate 15.
[0030] For example, the coating 10 can withstand elevated
temperatures during operation. As used herein "withstand" refers to
not showing significant signs of degradation after prolonged
exposure to the elevated temperature. In some embodiments, the
coating 10 can withstand temperatures of at least 300.degree.
C.
[0031] Furthermore, the coating can have a porosity of less than or
equal to about 1 percent by volume and a surface roughness from
about 5 Ra to about 20 Ra. The relatively low surface roughness can
assist in meeting the aerodynamic requirements of the underlying
substrate 15 such as when said substrate 15 comprises a compressor
blade for a turbine.
[0032] As discussed above, the coating 10 can also be hydrophobic
and oleophobic to help prevent the resident buildup of fluids such
as water and oil. "Hydrophobic" refers to the physical property of
a material that is water repellent. "Oleophobic" refers to the
physical property of a material that is oil repellent.
Specifically, surfaces with low surface energy for a foulant (e.g.
water and/or oil) should have a high contact angle and should
provide reduced adhesion with the foulant relative to a surface
which is wet by the foulant or with which the foulant has low
contact angle. As used herein, the term "contact angle" is the
angle formed by a static liquid droplet on the surface of a solid
material. The higher the contact angle, the less the interaction of
the liquid with the surface. Thus, it is more difficult for the
foulant to wet or adhere to the surface if the contact angle of the
oil or other foulant with the surface is high. For example, the
coating can have a contact angle of from about 90 degrees to about
140 degrees.
[0033] The substrate 15 of the coated article can comprise any
metallic substrate 15 such as one utilized in a gas turbine.
Metallic substrates can include, but not be limited to, iron based
alloys (e.g., stainless steels), nickel based alloys, cobalt based
alloys and the like. For example, referring now to FIG. 3, in some
embodiments, the substrate can comprise a compressor blade 50. The
compressor blade 50 can include an airfoil 52, which, when spun
about the rotor, imparts kinetic energy to air flowing through the
compressor, and a base or root 53. The airfoil 52 generally
includes a suction-side 56 (i.e., convex-side) and a pressure-side
57 (i.e., concave-side).
[0034] The root 53 can include a platform 54, which is the outward
radial face of the root 53 from which the airfoil 52 extends. The
platform 54 may be integrally joined to the root 53 of the
compressor blade 50. The platform 54 defines the radial inner
boundary of the airflow across the airfoil 52. As one of ordinary
skill in the art will appreciate, the root 53 further generally
includes a dovetail 55 that connects via a complimentary groove in
the rotor wheel (not illustrated) to secure the compressor blade 10
in the appropriate position within the compressor.
[0035] The substrate 15 (e.g., the compressor blade 50) can
comprise the coating 10 covering at least a portion of the outer
surface 17 (e.g., the suction-side 56 and/or the pressure-side 57)
to form the coated article 10. The coating 10 of the coated article
5 can thus comprise about 60 weight percent to about 90 weight
percent of one or more fluorinated polymers, about 1 weight percent
to about 7 weight percent of one or more erosion resistant fillers,
about 3 weight percent to about 9 weight percent of one or more
anticorrosive pigments, about 1 weight percent to about 4 weight
percent of one or more thixotropic agents, and about 1 weight
percent to about 4 weight percent of one or more porosity reducing
filler materials as discussed above.
[0036] In some embodiments where the substrate 15 comprises the
compressor blade 50, the compressor blade 50 may comprise an early
stage compressor blade 50. As used herein, "early stage" refers to
one of the first few stages of the compressor section for the
overall turbine. In such embodiments, the coating described herein
can thereby provide a thin coating with a smooth surface to protect
the compressor blade 50 without significantly impacting its
aerodynamics when in operation.
[0037] The coating 10 may be applied to either new-make parts or
serviced parts for modification (e.g., repair operations or the
like). Furthermore, the coating 10 may be applied to the substrate
15 in the field or back at a service facility. In some embodiments,
the coating 10 may be applied directly to the substrate 15. In
other embodiments, the coating 10 may be applied to one or more
other coatings (e.g., base coat(s)) already disposed on the
substrate 15.
[0038] Referring now to FIG. 4, with additional reference to the
structures illustrated in FIGS. 1-3, a method 100 is illustrated
for coating a substrate 15 with a coating 10. The method 100 can
first comprise applying a coating 10 onto an outer surface 17 of
the substrate 15 in step 110, wherein the coating 10 comprises
about 60 weight percent to about 90 weight percent of one or more
fluorinated polymers, about 1 weight percent to about 7 weight
percent of one or more erosion resistant fillers, about 3 weight
percent to about 9 weight percent of one or more anticorrosive
pigments, about 1 weight percent to about 4 weight percent of one
or more thixotropic agents, and about 1 weight percent to about 4
weight percent of one or more porosity reducing filler
materials.
[0039] The coating 10 applied in step 110 can be provided such that
it has a suitable viscosity for sufficiently covering the substrate
15 and residing in place before curing. For example, in some
embodiments, the coating 10 can have a viscosity of from about 0.1
Pascal-second to about 0.15 Pascal-second prior to curing as will
become appreciated herein.
[0040] Applying the coating 10 in step 110 can be accomplished
through any suitable means to cover the targeted area of the outer
surface 17 of the substrate 15. For example, in some embodiments
the coating 10 can be applied in step 110 through dipping,
spraying, brushing and/or rolling.
[0041] The method 100 further comprises curing the coating 10 in
step 120 on the outer surface of the substrate 15 at a curing
temperature of from about 50.degree. C. to about 300.degree. C.
Curing in step 120 can occur for any period of time and at any
combination of intervals, ramp rates, environmental conditions,
etc., to provide sufficient cohesion between the coating 10 and the
substrate 15 and/or any layers there between.
[0042] In some optional embodiments, the method 100 may further
comprise modifying the outer surface 17 of the substrate 15 in step
105 prior to applying the coating 10 in step 110. Modifying the
outer surface 17 can comprise any treatment, preparation or
modification to the outer surface 17 that can help facilitate
adhesion with the subsequently applied coating 10. For example, in
some embodiments, modifying the outer surface 17 can comprise zinc
phosphating, blast cleaning, water jetting or the like. In other
embodiments, modifying the outer surface 17 can comprise applying a
base coat 19 as should be appreciated herein.
[0043] In some embodiments, the method 100 may at least partially
repeat one or more times such an additional layer of the coating 10
is applied. The additional layer can similarly comprise about 60
weight percent to about 90 weight percent of one or more
fluorinated polymers, about 1 weight percent to about 7 weight
percent of one or more erosion resistant fillers, about 3 weight
percent to about 9 weight percent of one or more anticorrosive
pigments, about 1 weight percent to about 4 weight percent of one
or more thixotropic agents, and about 1 weight percent to about 4
weight percent of one or more porosity reducing filler materials.
The additional layer may further be cured at a curing temperature
to promote sufficient adhesion between the multiple layers of
coating 10.
[0044] In some of these embodiments wherein a plurality of layers
is applied, the curing temperature used for each additional cure
step may increase at incremental levels. For example, the curing
temperature can increase at least about 15.degree. C. and held for
15-30 minutes before applying an additional layer and repeating a
similar curing temperature increase and hold time. Such embodiments
can provide a plurality of thin coats with the increased
cross-linking efficiency leading to increased durability of the
overall coating 10.
[0045] It should now be appreciated that coatings may be provided
to protect underlying substrates from a variety of external forces
and environmental conditions. The coatings embodying the
compositions presented herein can seal the surface of an underlying
substrate to help suppress the penetration of corrosive vapors and
liquids. Moreover, the coatings can be provided in a relatively
thin layer with a smooth surface to protect the part without
significantly affecting the aerodynamic properties of the
application.
[0046] While the invention has been described in detail in
connection with only a limited number of embodiments, it should be
readily understood that the invention is not limited to such
disclosed embodiments. Rather, the invention can be modified to
incorporate any number of variations, alterations, substitutions or
equivalent arrangements not heretofore described, but which are
commensurate with the spirit and scope of the invention.
Additionally, while various embodiments of the invention have been
described, it is to be understood that aspects of the invention may
include only some of the described embodiments. Accordingly, the
invention is not to be seen as limited by the foregoing
description, but is only limited by the scope of the appended
claims.
* * * * *