Note: Descriptions are shown in the official language in which they were submitted.
PROTECTIVE COATINGS FOR AIRCRAFT ENGINE COMPONENTS
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to Italian application number
102021000024893, filed September 29, 2021.
FIELD
[0002] The present disclosure generally pertains to protective coatings for
aircraft
engine components, methods of applying protective coatings, and aircraft
engine
components that include a protective coating.
BACKGROUND
[0003] Aircraft engine components such as gearboxes, oil tanks, and the
like may
utilize various forms of protection to mitigate various sources of potential
heat,
corrosion, fretting, handling, and the like. It is desirable to protect such
aircraft
engine components, for example, to prolong operating life. Accordingly, there
exists
a need for improved protective coatings for aircraft engine components, as
well as
improved methods for applying protective coatings, and aircraft engine
components
that include an improved protective coating.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] A full and enabling disclosure, including the best mode thereof,
directed to
one of ordinary skill in the art, is set forth in the specification, which
makes reference
to the appended Figures, in which:
[0005] FIG. 1 schematically depicts a perspective view of an exemplary
aircraft
engine component;
[0006] FIG. 2 schematically depicts a cross-sectional view of a wall of the
aircraft
engine component of FIG. 1, with an exemplary protective coating applied to
the wall
of the aircraft engine component; and
[0007] FIG. 3 shows a flow chart depicting a method of applying a
protective
coating to an aircraft engine component.
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Date Recue/Date Received 2022-09-20
[0008] Repeat use of reference characters in the present specification and
drawings is intended to represent the same or analogous features or elements
of the
present disclosure.
DETAILED DESCRIPTION
[0009] Reference now will be made in detail to exemplary embodiments of the
presently disclosed subject matter, one or more examples of which are
illustrated in
the drawings. Each example is provided by way of explanation and should not be
interpreted as limiting the present disclosure. In fact, it will be apparent
to those
skilled in the art that various modifications and variations can be made in
the present
disclosure without departing from the scope of the present disclosure. For
instance,
features illustrated or described as part of one embodiment can be used with
another
embodiment to yield a still further embodiment. Thus, it is intended that the
present
disclosure covers such modifications and variations as come within the scope
of the
appended claims and their equivalents.
[0010] It is understood that terms such as "top", "bottom", "outward",
"inward",
and the like are words of convenience and are not to be construed as limiting
terms.
As used herein, the terms "first", "second", and "third" may be used
interchangeably
to distinguish one component from another and are not intended to signify
location or
importance of the individual components. The terms "a" and "an" do not denote
a
limitation of quantity, but rather denote the presence of at least one of the
referenced
item.
[0011] Approximating language, as used herein throughout the specification
and
claims, may be applied to modify any quantitative representation that could
permissibly vary without resulting in a change in the basic function to which
it is
related. Accordingly, a value modified by a term or terms, such as "about,"
"substantially," and "approximately," are not to be limited to the precise
value
specified. In at least some instances, the approximating language may
correspond to
the precision of an instrument for measuring the value, or the precision of
the methods
or machines for constructing or manufacturing the components and/or systems.
For
example, the approximating language may refer to being within a 10 percent
margin.
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Date Recue/Date Received 2022-09-20
[0012] Here and throughout the specification and claims, range limitations
are
combined and interchanged, such ranges are identified and include all the sub-
ranges
contained therein unless context or language indicates otherwise. For example,
all
ranges disclosed herein are inclusive of the endpoints, and the endpoints are
independently combinable with each other.
[0013] The present disclosure generally pertains to protective coatings for
aircraft
engine components, as well as methods of applying protective coatings, and
aircraft
engine components that include a protective coating. The presently disclosed
protective coatings may provide protection from a variety of sources of heat,
fire,
corrosion, fretting, handling, and the like. Exemplary protective coatings may
exhibit
good thermal properties in the presence of heat and/or fire, while also
exhibiting good
surface toughness and resistance to corrosive materials. The thermal
properties of
exemplary protective coatings may include good insulative properties and/or
good
ablative properties. Good insulative properties may include a low thermal
conductivity. Good ablative properties may include a high ablation
temperature, a
high heat of ablation, and/or a high continuous use temperature.
[0014] A protective coating may provide thermal protection by way of
insulation,
for example, when the protective coating is at a temperature below an ablation
temperature. Additionally, or in the alternative, a protective coating may
provide
thermal protection by way of ablation, for example, when the protective
coating
exceeds the ablation temperature. As used herein, the term "ablation" or
"ablative
properties" refers to thermal protection based on physicochemical
transformations of
a solid material when exposed to sufficiently high convective or radiant heat.
Thermal protection by ablation of a protective coating may be quantified at
least in
part by the heat of phase and chemical transformation of the protective
coating and/or
the reduction in heat flow attributable to one or more of pyrolysis, charring,
melting,
subliming, vaporizing, spalling, swelling, and the like. In some embodiments,
a
protective coating that provides thermal protection by ablation may include an
intumescent material. As used herein, an "intumescent material" refers to a
material
that swells as a result of heat exposure, leading to an increase in volume and
a
decrease in density. An intumescent material may produce char, such as light
char, or
hard char. Such char may exhibit relatively low heat conductivity. As used
herein,
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Date Recue/Date Received 2022-09-20
"intumescent properties" refers to swelling and/or the production of char as a
result of
heat exposure.
100151 In some embodiments, a protective coating that exhibits ablative
properties
and/or intumescent material may undergo a chemical reaction when heated to
form an
expanded, thermally insulating layer. Additionally, or in the alternative,
when
exposed to heat, one or more components in the protective coating may form a
char or
melt, which may expand to form a porous or sponge-like layer that provides a
physical protection and a thermal insulation of a base material from further
heat
exposure.
[0016] In addition to good thermal properties, exemplary protective
coatings may
have a combination of surface toughness and bulk softness that allows the
protective
coating to provide good protection from wear and tear. Further, exemplary
protective
coatings may provide protection from corrosion, for example, in the event of
exposure
to corrosive materials such as oil, fuel, hydraulic fluid, alkaline fluids,
cleaning fluids,
solvents, or salt water, as well as other fluids commonly associated with
operation of
aircraft, aircraft engines, and related systems.
[0017] These and other advantages of the presently disclosed protective
coatings
may be realized by a combination of layers that provide a synergistic effect.
Exemplary protective coatings may include a silane coupling agent and an
organic
titanate that together provide for improved bonding between the surface of an
aircraft
component and silicone polymers that make up a majority of the thickness of
the
protective coating. The silane coupling agent and the organic titanate may be
dispersed in an organic solvent that leaves little to no residue. Exemplary
protective
coatings may include a silicone elastomer layer formed from a silicone polymer
formulation that includes one or more silicone polymers and one or more filler
materials. When cured, the one or more silicone polymers and one or more
filler
materials may form a silicone elastomer layer that includes the one or more
filler
materials dispersed in a matrix of cross-linked silicone polymers.
Additionally, the
one or more silicone polymers may bond with the silane coupling agent and/or
the
organic titanate in the prime layer. In some embodiments, the silicone polymer
formulation may include a silanization agent that may enhance bonding between
silicone polymers in the silicone polymer formulation and the silane coupling
agent
4
Date Recue/Date Received 2022-09-20
and/or the organic titanate in the prime layer. Additionally, or in the
alternative, the
silanization agent may enhance bonding within the silicone polymer
formulation,
including bonding between filler materials and silicone polymers. An inward
portion
of the protective coating may have a low to medium density, and a soft to
medium-
soft Shore A hardness, while an outward portion of the protective coating may
have a
medium to high density with a somewhat higher Shore A hardness, thereby
providing
a combination of good resistance to abrasions as well as impacts, and the
like.
[0018] These and other properties are realized at least in part by the
composition
of the respective parts of the presently disclosed protective coatings. For
example, by
formulating a protective coating in accordance with the present disclosure,
much
thicker protective coatings may be applied to aircraft components, while
maintaining
good bonding to the surface of the aircraft component as well as within the
protective
coating itself The combination of good bonds at the surface and within the
protective
coating provides for good resilience, while mitigating the possibility for
cracks, chips,
or delamination, and the like to effect the longevity of the protective
coating. For
example, the presently disclosed protective coatings may have a thickness of
several
millimeters, such as up to 10 millimeters or more. Such an enhanced thickness
may
provide for improved protection from heat sources, including improved
insulative
properties and/or ablative properties, as well as improved protection from
wear and
tear, corrosive materials, and the like. Advantageously, the presently
disclosed
protective coatings preferably include silicone polymers and filler materials
that,
when cured, provide a protective coating that substantially retains its size
and shape
when exposed to heat and/or flames, for example, substantially without
exhibiting
thermal expansion when below a threshold temperature for continuous use. For
example, in some embodiments, the presently disclosed protective coatings may
withstand sustained continuous operating temperatures of up to 315 C, or
more. In
some embodiments, a protective coating may be foimulated to exhibit
intumescent
properties, if desired.
[0019] The presently disclosed protective coatings are generally intended
to be
applied to the surface of aircraft engine components. It will be appreciated,
however,
that aircraft engine components are merely one example use of the presently
disclosed
protective coatings, and that the protective coatings may additionally or
alternatively
Date Recue/Date Received 2022-09-20
be applied to any component that may benefit from protection against exposure
to
heat sources, wear and tear, and/or corrosive fluids or other materials. For
example,
the presently disclosed protective coatings may be applied to any kind of
engine, any
kind of aircraft component, any kind of industrial equipment, and so forth.
[0020] Referring now to FIG. 1, an exemplary component 100 may include a
gearbox 102 and/or an oil tank 104. The gearbox 102 may be configured as a
power
gearbox configured to transfer power from a turbomachine to a fan or propeller
assembly (not shown). For example, the gearbox 102 may include an epicyclic
gear
assembly 106 configured to couple the fan or propeller assembly to the
turbomachine.
Alternatively, the gearbox 102 may be configured as an accessory gearbox
configured
to transfer power from a turbomachine to one or more accessory systems of an
aircraft
engine or other aircraft systems.
[0021] A protective coating 108 may cover all or a portion of a wall 200 of
the
component 100 such as the gearbox 102 and/or the oil tank 104 as shown in FIG.
1. It
will be appreciated that the gearbox 102 and the oil tank 104 shown in FIG. 1
are
provided by way of example and not to be limiting. Further examples of
aircraft
engine components that may receive the protective coating 108 include
turbomachine
casings, combustion chambers, exhaust ducts, bypass ducts, heat exchangers,
fuel
systems, oil systems, firewalls, and so forth. In fact, the presently
disclosed protective
coatings 108 may be suitable for any aircraft engine component that may be
exposed
to sources of heat, fire, corrosion, fretting, handling, and the like.
[0022] Referring to FIG. 2, the protective coating 108 may be applied to
the wall
200 of the component 100. The protective coating 108 may be applied to all or
a
portion of a surface 202 of the wall 200, such as the surface 202 that may be
exposed
to a heat source 204. The surface 202 may be an external surface or an
internal
surface. The heat source 204 may include an extant heat source such as a flame
from
a burner or fumes from an exhaust duct. Additionally, or in the alternative,
the heat
source 204 may include a potential heat source, such as an area that may be
exposed
to flame, sparks, slag, embers, fumes, hot gasses, combustion residues, and
the like in
the event of an emergency or malfunction.
[0023] The presently disclosed protective coatings 108 are suitable for use
with
aircraft engine components 100 fanned of metal alloys, such as aluminum
alloys,
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Date Recue/Date Received 2022-09-20
magnesium alloys, and alloys that include a combination of aluminum and
magnesium. The protective coatings 108 may be suitable, for example, for use
with
components 100 that are formed by any manufacturing process, including
casting,
forging, machining, additive manufacturing, subtractive manufacturing, and so
forth.
By way of example, the protective coating 108 may be applied to aluminum
alloys
that include chromium, copper, iron, magnesium, manganese, titanium, scandium,
silicon, or zinc, as well as combinations of these. An exemplary aluminum
alloy may
have a composition that includes aluminum, silicon, copper, and magnesium. The
aluminum alloy may be formed, for example, according to ASM4215. As a further
example, the protective coating 108 may be applied to magnesium alloys that
include
aluminum, copper, manganese, one or more rare earth elements, silicon, zinc,
or
zirconium, as well as combinations of these. An exemplary magnesium alloy may
have a composition that includes magnesium, zinc, rare earth, and zirconium.
The
magnesium alloy may be formed, for example, according to ASM4439. The
presently
disclosed protective coatings 108 may also be suitable for use with various
other
materials, including steel alloys, nickel-chromium alloys, carbon fiber,
ceramics,
plastics, and so forth.
[0024] As shown in FIG. 2, and as will be discussed in more detail herein,
the
protective coating 108 may generally include a prime layer 206 at least
partially
covering the surface 202 of the wall 200 of the component 100, a silicone
elastomer
layer 208 at least partially covering the prime layer 206, and an abrasion
resistant
layer 210 at least partially covering the silicone elastomer layer 208. The
prime layer
206 may include a silane coupling agent and an organic titanate. The silicone
elastomer layer 208 may include one or more filler materials dispersed in a
matrix of
cross-linked silicone polymers. The abrasion resistant layer 210 may include
one or
more fibrous reinforcing materials dispersed in a matrix of cross-linked
silicone
polymers. In some embodiments, the surface 202 of the wall 200 of the
component
100 may receive a surface treatment 212 in preparation for the protective
coating 108.
The surface treatment 212 may be included as a base layer of the protective
coating
108, and/or the surface treatment 212 may define as a property of the surface
202 of
the wall 200 of the component 100 to which the protective coating 108 may be
applied.
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Date Recue/Date Received 2022-09-20
[0025] In some embodiments, the surface treatment 212 may include a
chemical
conversion coating, such as a chromate conversion coating. Additionally, or in
the
alternative, the surface treatment 212 may include an anodizing coating. The
surface
treatment 212 may provide improved adhesion between the surface 202 of the
wall
200 and the prime layer 206. A chemical conversion coating may be applied by
immersing the component 100 in a chemical bath that contains suitable metal
ions,
such as chromium ions. An anodizing coating may be applied by immersing the
component 100 in an electrolytic bath that contains a suitable acid, such as
chromic
acid, sulfuric acid, phosphoric acid, and so forth, while passing an electric
current
through the bath. A chromate conversion coating and/or an anodizing coating
may be
particularly suitable for components 100 formed of aluminum and/or magnesium
alloys.
[0026] The prime layer 206 may be applied over all or a portion of the
surface
202 of the wall 200 of the component 100. In some embodiments, the prime layer
206 may be applied over the surface 202 that has received the surface
treatment 212.
The prime layer 206 may include a silane coupling agent and/or an organic
titanate.
The silane coupling agent may be selected to provide a durable bond between
the
surface 202 or surface treatment 212 of the component 100 and the silicone
elastomer
layer 208 to be applied over the prime layer 206. The silane coupling agent
may
include hydrolyzable functional groups, such as acyloxy groups, alkoxy groups,
amine groups, butyl groups, ethoxy groups, ethyl groups, halogen groups, or
phenyl
groups, as well as combinations of these. The hydrolyzable functional groups
may
form stable condensation products with oxides of aluminum and/or oxides of
magnesium, as well as other metal oxides. Following hydrolysis, the silane
coupling
agent may include silanol groups that may react with the silicone polymers to
form
siloxane bonds during the curing process of the formulation used to form the
silicone
elastomer layer 208. These siloxane bonds may be particularly stable and
thereby
promote good adhesion between the prime layer 206 and the silicone elastomer
layer
208. Exemplary silane coupling agents may include trialkoxysilane,
monoalkoxysilane, or dipodal silane. Further exemplary silane coupling agents
may
include a silicic acid ester, such as tetramethoxysilane, methyl silicate,
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Date Recue/Date Received 2022-09-20
tetraethyoxysilane, ethyl polysilicate, tetrapropoxysilane,
tetraisopropoxysilane,
tetrabutoxysilane, or tetrakis(butoxyethoxy)silane, as well as combinations of
these.
[0027] The organic titanate may similarly be selected to provide a durable
bond
between the surface 202 or surface treatment 212 of the component 100 and the
silicone elastomer layer 208 to be applied over the prime layer 206. The
organic
titanate may include hydrolysable functional groups that react with oxides of
aluminum and/or oxides of magnesium, as well as other metal oxides. In some
embodiments, hydrolysis of the organic titanate may form a monomolecular layer
on
the surface 202 or surface treatment 212 of the component 100, for example,
without
yielding a condensation product. Additionally, or in the alternative, the
organic
titanate may include thermosetting functional groups that may form bonds with
hydrocarbon chains of the silicone polymers, and/or the organic titanate may
include
hydrocarbon chains that may bond with the silicone polymers by way of Van der
Waals forces. Exemplary thermosetting functional groups of the organic
titanate may
include acrylate groups, alkyl groups, amine groups, carboxylic acid groups,
epoxy
groups, hydroxy groups, mercaptan groups, or vinyl groups, as well as
combinations
of these. Additionally, or in the alternative, in some embodiments, the
organic
titanate may hydrolyze to yield titanium oxides such as titanium dioxide that
may
catalyze or react with silicone polymers in the formulation used to form the
silicone
elastomer layer 208. For example, an organic titanate may include a titanium
dioxide
content of from about 15 mol.% to about 30 mol.%, such as from about 20 mol.%
to
about 25 mol.%. Exemplary organic titanates may include ethyl acetoacetate
titanate,
di-iso-butoxy titanium, di-n-butoxy titanium, di-iso-propoxy titanium, n-Butyl
polytitanate, tetra n-Butyl titanate, titanium tetrabutanolate, titanium
butoxide,
titanium ethylacetoacetate, or titanium tetraisopropoxide, as well as
combinations of
these.
[0028] The prime layer 206 may be provided in a solution that includes the
silane
coupling agent, the organic titanate, and an organic solvent such as an
aliphatic
solvent. In an exemplary embodiment, the organic solvent may include naphtha.
The
organic solvent, such as naphtha may be selected to leave little to no
residue. The
substantial absence of residues from the prime layer promotes good
functionality of
the silane coupling agent and the organic titanate, for example, with respect
to cross-
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Date Recue/Date Received 2022-09-20
linking reactions with silicone polymers in the silicone elastomer layer 208.
The
solution may include an organic solvent in an amount of from about 75 wt.% to
about
95 wt.%, such as from about 77 wt.% to about 94 wt.%, or such as from about 80
wt.% to about 85 wt.%. The silane coupling agent may be included in the
solution in
an amount of from about 2 wt.% to about 10 wt.%, such as from about 4 wt.% to
about 6 wt.%. The organic titanate may be included in the solution in an
amount of
from about 2 wt.% to about 10 wt.%, such as from about 4 wt.% to about 6 wt.%.
By
way of example, an exemplary solution that may be utilized to apply the prime
layer
206 may include from about 75 wt.% to about 95 wt.%, such as from about 82
wt.%
to about 88 wt.% light aliphatic naphtha; from about 4 wt.% to about 6 wt.%
tetrakis(2-butoxyethyl) orthosilicate; and from about 4 wt.% to about 6 wt.%
tetra n-
Butyl titanate. Such a solution is commercially available as DOWSILTM PR-1200,
Dow Chemical Company, Midland, MI.
[0029] After the organic solvent has at least partially evaporated,
preferably fully
evaporated, the prime layer 206 may include a silane coupling agent in an
amount of
from about 15 wt.% to about 85 wt.%, such as from about 15 wt.% to about 40
wt.%,
such as from about 40 wt.% to about 60 wt.%, or such as from about 60 wt.% to
about
85 wt.%. Additionally, or in the alternative, after the organic solvent has at
least
evaporated, preferably fully evaporated, the prime layer 206 may include an
organic
titanate in an amount of about 15 wt.% to about 85 wt.%, such as from about 15
wt.%
to about 40 wt.%, such as from about 40 wt.% to about 60 wt.%, or such as from
about 60 wt.% to about 85 wt.%.
[0030] The silicone elastomer layer 208 may be applied over at least a
portion of
the prime layer 206. The silicone elastomer layer 208 may be provided by way
of one
or more silicone polymer formulations that can be applied to the prime layer
206
using standard spray equipment and/or using standard trowel/molding equipment.
When cured, the one or more silicone polymer formulations may include one or
more
filler materials dispersed in a matrix of cross-linked silicone polymers. The
presently
disclosed silicone polymer formulations may be utilized to form the silicone
elastomer layer 208 that has good insulation properties and/or good ablation
properties in the presence of the heat source 204. The silicone elastomer
layer 208
may also exhibit good elastomeric properties that, for example, may provide
Date Recue/Date Received 2022-09-20
protection from wear and tear from bumps, nicks, dings, and the like that may
arise in
the course of installation, maintenance, handling, and operation. Exemplary
silicone
polymer formulations may include one or more silicone polymers and one or more
filler materials. The one or more silicone polymers may be cross-linked or
cured, for
example, by any suitable cross-linking agent. Additionally, or in the
alternative, the
one or more silicone polymers may be self-curing in the presence of
atmospheric
moisture.
[0031] Exemplary
silicone polymers may include room-temperature-vulcanizing
(RTV) silicone, or liquid silicone rubber, as well as combinations of these.
Suitable
RTV silicones may be cured in the presence of atmospheric moisture, such as in
the
case of one-component silicone formulations, which may sometimes be referred
to as
"RTV 1 silicone." Additionally, or in the alternative, suitable RTV silicones
may be
cured in the presence of a catalyst, such as in the case of two-component
silicone
formulations, which may sometimes be referred to as "RTV 2 silicone." The
curing
process of such RTV silicones may be accelerated by heat or pressure. A
silicone
polymer may be derived from one or more polyorganosiloxanes, such as
polydimethylsiloxane, polymethylhydrogensiloxane,
dimethyidiphenylpolysiloxane,
dimethyl/methylphenylpolysiloxane, polymethylphenylsiloxane,
methylphenyl/dimethylsiloxane, vinyldimethyl terminated polydimethylsiloxane,
vinylmethyl/dimethylpolysiloxane, vinyldimethyl terminated
vinylmethyl/dimethylpolysiloxane, divinylmethyl terminated
polydimethylsiloxane,
vinylphenylmethyl terminated polydimethylsiloxane, dimethylhydro terminated
polydimethylsiloxane, methylhydro/dimethylpolysiloxane, methylhydro terminated
methyloctylpolysiloxane, methylhydro/phenylmethyl polysiloxane,
oligosiloxanes, or
fluoro-modified polysiloxanes, as well as combinations of these. To form a
silicone
elastomer, the one or more polyorganosiloxanes may be crosslinked using any
suitable technique, such as catalyst curing, heat curing, or the like. Any
suitable
crosslinking agent may be utilized, such as alkoxy silanes that include one or
more
cross-linking functional groups such as alkyl groups, alkenyl groups,
carboxyalkyl
groups, as well as combinations of these. Any suitable catalyst may be used,
such as
a platinum catalyst, a peroxide catalyst, or a tin catalyst. Tt will be
appreciated that
the aforementioned silicone polymer components are provided by way of example
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Date Recue/Date Received 2022-09-20
and not to be limiting, and that the silicone elastomer layer 208 may include
other
types of silicone polymers, and/or that the silicone elastomer layer 208 may
include
other components, without departing from the scope of the present disclosure.
[0032] The silicone elastomer layer 208 may include one or more filler
materials
dispersed in a matrix of cross-linked silicone polymers. Exemplary filler
materials
that may be included in a silicone polymer formulation that may be used to
form the
silicone elastomer layer 208 include glass microspheres (hollow or solid),
glass fibers,
cenospheres, fumed silica, precipitated silica, silica fibers, silicon
dioxide, silicon
carbide, titanium dioxide, zinc oxide, rare earth minerals, silicate minerals,
inosilicates, aluminum silicate, alumina trihydrate, polyepoxide
microparticles,
phenolic resin microspheres (hollow or solid), ceramics, carbon fibers, carbon
black,
graphene, cellulosic fibers, or cork, as well as combinations of these.
Exemplary
filler materials may have an average cross-sectional width of from about 10
nanometers (nm) to about 1,000 micrometers (gm), such as from about 10 nm to
about 1,000 nm, such as from about 100 nm to about 500 nm, such as from about
l
gm to about 1,000 gm, such as from about 10 gm to about 500 gm, or such as
from
about 100 gm to about 1,000 gm. It will be appreciated that the aforementioned
filler
materials are provided by way of example and not to be limiting, and that the
silicone
elastomer layer 208 may include other types of filler materials without
departing from
the scope of the present disclosure.
[0033] The particular filler material(s) and amount thereof in a silicone
polymer
formulation may be selected to realize desired material properties of the
resulting
silicone elastomer layer 208. An exemplary silicone elastomer layer 208 may
include
one or more fillers in an amount, individually or collectively, of from about
0.1 vol.%
to about 90 vol.%, such as from about 1 vol.% to about 80 vol.%, such as from
about
vol."/0 to about 60 vol.% such as from about 10 vol.% to about 60 vol.%, such
as
from about 20 vol.% to about 50 vol.%, such as from about 30 vol.% to about 40
vol.%, or such as from about 60 vol.% to about 90 vol.%. The total filler
content of
the silicone elastomer layer 208 may be at least about 1 vol.%, such as at
least about 5
vol.%, such as at least about 10 vol.%, such as at least about 20 vol.%, such
as at least
about 30 vol.%, such as at least about 40 vol.%, such as at least about 50
vol.%, such
12
Date Recue/Date Received 2022-09-20
as at least about 60 vol.%, such as at least about 70 vol.%, or such as at
least about 80
vol.%.
100341 In some embodiments, the silicone elastomer layer 208 may include a
silanization agent, such as an aminosilane, a glycidoxysilane, or a
mercaptosilane, as
well as combinations of these. The silanization agent may form siloxane bonds
between one or more materials in the silicone polymer formulation used to form
the
silicone elastomer layer 208 and one or more components of the prime layer
206. For
example, a silanization agent may form siloxane bonds between organic titanate
of the
prime layer 206 and a silicone polymer in the formulation used to form the
silicone
elastomer layer 208. Additionally, or in the alternative, a silanization agent
may form
siloxane bonds between the organic titanate of the prime layer 206 and one or
more
filler materials in the formulation used to form the silicone elastomer layer
208,
and/or between the silicone polymer and the one or more filler materials in
the
formulation used to form the silicone elastomer layer 208. Suitable
aminosilanes may
include (3-aminopropyl)triethoxysilane, (3-aminopropy1)-diethoxy-methylsilane,
(3-
aminopropy1)-dimethyl-ethoxysilane, (3-aminopropy1)-trimethoxysilane. An
exemplary glycidoxysilane may include (3-glycidoxypropy1)-dimethyl-
ethoxysilane.
Exempalry mercaptosilanes include (3-mercaptopropy1)-trimethoxysilane and (3-
mercaptopropy1)-methyl-dimethoxysilane.
[0035] In some embodiments, the silicone elastomer layer 208 may include an
intumescent material. An intumescent material may include a material that
produces
char when exposed to heat. For example, a silicone polymer formulation may
include
an intumescent material. In some embodiments, a silicone polymer may exhibit
intumescent properties. Additionally, or in the alternative, the silicone
elastomer
layer 208 may include one or more intumescent materials that are utilized as
filler
materials. For example, the one or more intumescent materials may be dispersed
in a
matrix of cross-linked silicone polymers. Further exemplary intumescent
materials
that may be included in the silicone elastomer layer 208 include vinyl
acetates,
styrene acrylates, as well as combinations of these. An exemplary intumescent
material may include a soft char formulation. The soft char formulation may
include
ammonium polyphosphate, pentaerythritol, or melamine, as well as combinations
of
these. The soft char formulation may produce light char when exposed to heat.
13
Date Recue/Date Received 2022-09-20
Additionally, or in the alternative, an exemplary intumescent material may
include a
hard char formulation. The hard char formulation may include one or more
sodium
silicates, one or more ammonium phosphates, or graphite, as well as
combinations of
these. The hard char formulation may produce hard char when exposed to heat.
One
or more intumescent materials, such as one or more components in a soft char
formulation and/or one or more components in a hard char formulation, may be
dispersed in a matrix, such as a matrix of cross-linked silicone polymers,
acetate
copolymers, or styrene acrylate polymers, as well as combinations of these.
The
intumescent material may form a microporous carbonaceous foam, for example, as
a
result of a chemical reaction of one or more components in the intumescent
material.
[0036] When cured, the silicone elastomer layer 208 may have good thertnal
properties to withstand exposure to the heat source 204, including good
insulative
properties and/or good ablative properties. For example, when cured, the
silicone
elastomer layer 208 may have a thermal conductivity at 38 C of from about
0.05
W/mK to about 0.15 W/mK, such as from about 0.07 W/mK to about 0.12 W/mK, or
such as from about 0.08 W/mK to about 0.11 W/mK, as measured, for example,
according to ASTM C177. Additionally, or in the alternative, the silicone
elastomer
layer 208 may have a specific heat at 24 C of from about 1.0 kJ/kg-K to about
1.6
kJ/kg-K, such as from about 1.2 kJ/kg-K to about 1.6 kJ/kg-K, or such as from
about
1.2 kJ/kg-K to about 1.4 kJ/kg-K, as measured, for example, according to ASTM
E1269-11 (2018). Additionally, or in the alternative, the silicone elastomer
layer 208
may have an ablation temperature of from about 450 C to about 600 C, such as
from
about 475 C to about 550 C, or such as from about 500 C to about 525C, as
measured, for example, according to ASTM E285-80 (2002). Additionally, or in
the
alternative, the silicone elastomer layer 208 may have a heat of ablation of
from about
40 megajoules per kilogram (MJ/kg) to about 70 MJ/kg, or such as from about 50
MJ/kg to about 60 MJ/kg, with a heat exposure of 330 kilojoules per square
meter per
second (kJ/m2-sec), as measured, for example, according to ASTM E458 ¨08
(2020).
Additionally, or in the alternative, an exemplary silicone elastomer layer 208
may
have a continuous use temperature of up to at least about 300 C, such as up
to at least
about 315 C, or such as up to at least about 325 C. Additionally, or in the
alternative, an exemplary silicone elastomer layer 208 may exhibit a thermal
14
Date Recue/Date Received 2022-09-20
expansion of from about 0.2% to about 0.01%, such as from about 0.1% to about
0.05%, or such as from about 0.09% to about 0.07%, as measured across an
increase
in temperature from 3 C to 34 C.
[0037] In addition to good thermal properties, an exemplary silicone
elastomer
layer 208 may have a low to medium density, and a soft to medium-soft Shore A
hardness. For example, an exemplary silicone elastomer layer 208 may have a
density of from about 0.2 g/cm3 to about 0.6 g/cm3, such as from about 0.2
g/cm3 to
about 0.3 g/cm3, such as from about 0.35 g/cm3 to about 0.45 g/cm3, or such as
from
about 0.45 g/cm3 to about 0.55 g/cm3. An exemplary silicone elastomer layer
208
may have a Shore A hardness of from about 30 to about 80, such as from about
35 to
about 45, such as from about 40 to about 60, or such as from about 60 to about
80, as
measured, for example, according to ASTM D2240-15el.
[0038] In some embodiments, an exemplary silicone elastomer layer 208 may
include RTV silicone, glass microspheres, silicone oil, fumed silica, and (3-
aminopropyl)triethoxysilane. Additionally, or in the alternative, in some
embodiments, an exemplary silicone elastomer layer 208 may include one or more
silicone polymers in an amount of from about 22 wt.% to about 26 wt.%, silica
fibers
in an amount of from about 1 wt.% to about 5 wt.%, carbon fibers in an amount
of
from about 1 wt.% to about 5 wt.%, silica microspheres in an amount of from
about
30 wt.% to about 40 wt.%, phenolic resin microspheres in an amount of from
about 4
wt.% to about 8 wt.%, and cork in an amount of from about 20 wt.% to about 40
wt.%. Exemplary silicone polymer formulations that may be included in a
formulation used to form the silicone elastomer layer 208 are commercially
available
as MA-25S Ablative Material and/or MI-158 Ablative Material, from Thermal
Protection Products, New Orleans, LA.
[0039] After the silicone elastomer layer 208 has at least partially cured,
preferably fully cured, an abrasion resistant layer 210 may be applied over at
least a
portion of the silicone elastomer layer 208. The abrasion resistant layer 210
may be
formed using a formulation that can be applied to the silicone elastomer layer
208
using standard spray, brush, or roller equipment. The abrasion resistant layer
210
may exhibit good toughness. For example, the abrasion resistant layer 210 may
have
a medium to high density, while still having a soft to medium-soft Shore A
hardness.
Date Recue/Date Received 2022-09-20
This combination of medium to high density with soft to medium-soft Shore A
hardness may provide good resistance to fretting and other sources of wear.
100401 The abrasion resistant layer 210 may include a fiber-reinforced
elastomeric
material. The fiber-reinforced elastomeric material of the abrasion resistant
layer 210
may include one or more polymeric materials and one or more fibrous
reinforcing
materials. The one or more fibrous reinforcing materials may be dispersed in a
matrix
of cross-linked polymeric material. The polymeric material may be cross-linked
or
cured, for example, by any suitable cross-linking agent. Exemplary polymeric
material that may be included in the formulation used to form the abrasion
resistant
layer 210 may include one or more silicone polymers, such as those described
above
with reference to the silicone elastomer layer 208. In addition, or in the
alternative to
silicone polymers, further exemplary polymeric materials that may be included
in the
formulation used to form the abrasion resistant layer 210 include
thermoplastic
materials and/or thermosetting materials. Exemplary thermoplastic materials
include
acrylics, such as polyacrylic acids, and polymethyl methacrylate; polyamides,
polylactic acids; polybenzimidazole; polycarbonates; polyether sulfone;
polyoxymethylene; polyether ether ketone; polyetherimide; polyphenylene oxide;
polyphenylene sulfide; or polytetrafluoroethylene, as well as combinations of
these.
In addition to silicone polymers, exemplary thei -nosetting materials
include epoxy
resins, polyester resins, polyurethanes, or vinyl ester resins, as well as
combinations
of these. Any one or more of these thermoplastic materials and/or
thermosetting
materials may be included in a formulated used to form an abrasion resistant
layer
210. Additionally, or in the alternative, any one or more of these
thermoplastic
materials and/or thermosetting materials may be included in a formulation uses
to
form the silicone elastomer layer 208.
[0041] Exemplary fibrous reinforcing materials that may be included in the
formulation used to form the abrasion resistant layer 210 may include glass
fibers,
basalt fibers, carbon fibers, ceramic fibers, aramid fibers, polycrystalline
fibers, or
polysiloxane fibers, as well as combinations of these. By way of example,
suitable
glass fibers may be formulated from silica sand, limestone, kaolin clay,
fluorspar,
colemanite, dolomite, or alumino-borosilicate, as well as combinations of
these.
Suitable carbon fibers may be formulated from polyacrylonitrile, rayon, or
pitch
16
Date Recue/Date Received 2022-09-20
precursors, as well as combinations of these. Suitable ceramic fibers may be
formulated from may be formulated from zirconia, aluminosilicate,
polycrystalline
alumina, polycrystalline mullite fiber. Ceramic fibers may additionally, or
alternatively include ceramic matrix composites, such as silicon carbide
polycrystalline fibers. Suitable aramid fibers may include para-aramid fibers,
meta-
aramid fibers, and/or poly-aramid fibers. Aramid fibers may be formulated from
one
or more aromatic polyamides, such as para-polyaramide, p-phenylene diamine, or
terephthaloyl dichloride. It will be appreciated that the abrasion resistant
layer 210
may include other types of reinforcing fibers without departing from the scope
of the
present disclosure.
[0042] Exemplary fibrous reinforcing materials that may be included in the
abrasion resistant layer 210 may have an average length (e.g., an as-formed
length or
a chopped length) of from about 1 micrometers (gm) to about 10,000 um, such as
from about 100 um to about 500 gm, such as from about 500 gm to about 1,000
um,
such as from about 1,000 gm to about 5,000 um, or such as from about 1,000 gm
to
about 10,000 p.m. Additionally, or in the alternative, exemplary fibrous
reinforcing
materials may have an average cross-sectional width of from about 1 gm to
about 50
gm, such as from about 1 p.m to about 5 um, such as from about 5 gm to about
10
um, such as from about 10 gm to about 25 gm, or such as from about 25 gm to
about
50 gm.
[0043] The particular fibrous reinforcing material(s) and amount thereof in
the
abrasion resistant layer 210 may be selected to realize desired material
properties. An
exemplary abrasion resistant layer 210 may include one or more fibrous
reinforcing
materials in an amount, individually or collectively, of from about 0.1 vol.%
to about
60 vol.%, such as from about 1 vol.% to about 60 vol.%, such as from about 5
vol.%
to about 60 vol.% such as from about 10 vol.% to about 60 vol.%, such as from
about
20 vol.% to about 50 vol.%, or such as from about 30 vol.% to about 40 vol.%.
The
total fibrous reinforcing material content of the abrasion resistant layer 210
may be at
least about 1 vol.%, such as at least about 5 vol.%, such as at least about 10
vol.%,
such as at least about 20 vol.%, such as at least about 30 vol.%, such as at
least about
40 vol.%, such as at least about 50 vol.%, or such as at least about 60 vol.%.
17
Date Recue/Date Received 2022-09-20
[0044] In addition to fibrous-reinforcing material(s), the abrasion
resistant layer
210 may include one or more filler materials, such as one or more of the
filler
materials described with reference to the silicone elastomer layer 208.
Additionally,
or in the alternative, the silicone elastomer layer 208 may include one or
more
fibrous-reinforcing materials in addition to filler material(s), such as one
or more of
the fibrous-reinforcing materials described with reference to the abrasion
resistant
layer 210. Additionally, or in the alternative, in some embodiments, the
abrasion
resistant layer 210 may include an intumescent material, such as one or more
of the
intumescent materials described with reference to the silicone elastomer layer
208.
[0045] When cured, the exemplary abrasion resistant layer 210 may have a
density of from about 0.9 g/cm3 to about 1.4 g/cm3, such as from about 1.0
g/cm3 to
about 1.3 g/cm3, or such as from about 1.1 g/cm3 to about 1.2 g/cm3. An
exemplary
fiber-reinforced elastomer formulation may have a Shore A hardness, when
cured, of
from about 40 to about 90, such as from about 50 to about 60, such as from
about 60
to about 80, or such as from about 80 to about 90, as measured, for example,
according to ASTM D2240-15e1.
[0046] In addition to a combination of medium to high density with soft to
medium-soft Shore A hardness, an exemplary fiber-reinforced elastomer
formulation
may have good thermal properties to withstand exposure to the heat source 204,
including good insulative properties and/or good ablative properties. For
example,
when cured, an exemplary fiber-reinforced elastomer formulation may have a
thermal
conductivity at 38 C of from about 0.10 W/mK to about 0.25 W/mK, such as from
about 0.15 W/mK to about 0.25 W/mK, or such as from about 0.20 W/mK to about
0.25 W/mK, as measured, for example, according to ASTM C177. Additionally, or
in
the alternative, an exemplary fiber-reinforced elastomer formulation may have
a
specific heat at 38 C of from about 0.9 kJ/kg-K to about 1.5 kJ/kg-K, such as
from
about 1.0 kJ/kg-K to about 1.1 kJ/kg-K, or such as from about 1.2 kJ/kg-K to
about
1.5 kJ/kg-K, at 24 C, as measured, for example, according to ASTM E1269-11
(2018). Additionally, or in the alternative, an exemplary fiber-reinforced
elastomer
formulation may have an ablation temperature of from about 450 C to about 600
C,
such as from about 475 C to about 550 C, or such as from about 500 C to
about
525C, as measured, for example, according to ASTM E285-80 (2002). An exemplary
18
Date Recue/Date Received 2022-09-20
fiber-reinforced elastomer formulation that may be included in a fottnulation
utilized
to form a fiber-reinforced elastomer layer is commercially available as MI-15
Topcoat, from Thei -nal Protection Products, New Orleans, LA.
[0047] Exemplary protective coatings 108 may have a thickness of from about
1.2
millimeters (mm) to about 10 mm, such as from about 2 mm to about 4 mm, such
as
from about 4 mm to about 6 mm, such as from about 6 mm to about 8 mm, or such
as
from about 8 mm to about 10 mm. The prime layer 206 may have a thickness of
from
about 25 micrometers (gm) to about 50 gm, such as from about 25 gm to about 40
gm, or such as from about 35 gm to about 50 gm. The silicone elastomer layer
208
may have a thickness of from about 1,000 gm to about 10,000 gm, such as from
about
1,000 gm to about 4,000 gm, or such as from about 4,000 gm to about 8,000 gm,
or
such as from about 6,000 gm to about gm 10,000. The abrasion resistant layer
210
may have a thickness of from about 150 gm to about 500 gm, such as from about
150
gm to about 300 gm, or such as from about 250 gm to about 500 gm.
[0048] Referring now to FIG. 3, exemplary methods of applying a protective
coating 108 (FIGs. 1 and 2) will be described. As shown, an exemplary method
300
may include, at block 302, forming a prime layer 206 (FIG. 2) at least
partially
covering a surface 202 (FIG. 2) of a wall 200 (FIGs. 1 and 2) of an aircraft
engine
component 100 (FIG. 1). The prime layer 206 may include a silane coupling
agent
and an organic titanate as described herein. The prime layer 206 may be
applied in a
light, even coat by wiping, dipping or spraying. Excess material for the prime
layer
206 may be wiped off to avoid overapplication. Additional material for the
prime
layer 206 may be applied every 3 to 5 minutes to ensure fresh material can
react with
previously applied material. In some embodiments, forming the prime layer 206
may
include at least partially curing the prime layer 206, preferably fully curing
the prime
layer 206. The prime layer 206 may be cured at room temperature, such as from
about 18 C to about 23 C, and a relative humidity of from about 30% to about
90%,
such as from about 40% to about 70%. The curing time for the prime layer 206
may
be from about 1 to 2 hours, and may vary depending on temperature and
humidity.
The curing rate of the prime layer 206 may be accelerated with moderate heat,
such as
at a temperature of from about 40 C to about 60 C, or such as from about 50
C to
about 60 C.
19
Date Recue/Date Received 2022-09-20
[0049] At block 304, the exemplary method 300 may include forming the
silicone
elastomer layer 208 (FIG. 2) at least partially covering a surface of the
prime layer
206. The silicone elastomer layer 208 may be fat_ ned using a foimulation
as
described herein, and the formulation and may be applied by conventional
spraying or
rolling techniques, or the like. The silicone elastomer layer 208 may include
one or
more filler materials dispersed in a matrix of cross-linked silicone polymers
as
described herein. The silicone elastomer layer 208 may be applied in a series
of
sublayers. Respective sublayers of the silicone elastomer layer 208 may have a
thickness of from about 100 micrometers (gm) to about 500 gm, such as from
about
200 gm to about 400 gm. The number of sublayers may be determined based on the
desired thickness of the silicone elastomer layer 208 and the thickness of the
respective sublayers. By way of example, an exemplary silicone elastomer layer
208
may include from about 2 to about 40 sublayers, such as from about 5 to about
10
sublayers, such as from about 10 to about 20 sublayers, or from about 20 to
about 40
sublayers. The sequential sublayers may be applied after solvent in the
previous
sublayer has flashed off but prior to fully curing. In some embodiments,
application
of the silicone elastomer layer 208 to the prime layer 206 may commence after
the
prime layer 206 has fully cured.
[0050] Forming the silicone elastomer layer 208 may include at least
partially
curing the silicone elastomer layer 208. For example, after the silicone
elastomer
layer 208 has been applied to the desired thickness, the silicone elastomer
layer 208
may be at least partially cured, preferably fully cured. The silicone
elastomer layer
208 may be cured at an ambient temperature of from about 20 C to about 30 C,
and
a relative humidity of from about 30% to about 90%, such as from about 40% to
about 70%. At an ambient temperature, the cure time may be about 24 hours.
Additionally, or in the alternative, the silicone elastomer layer 208 may be
cured at an
elevated temperature of from about 30 C to about 70 C, such as from about 55
C to
about 65 C. In some embodiments, the silicone elastomer layer 208 may be
cured at
such an elevated temperature, for example, in an oven, heated curing chamber,
or the
like, after initially being partially cured at an ambient temperature. For
example, the
silicone elastomer layer 208 may receive an ambient-temperature cure, such as
for a
duration of from about 2 to about 6 hours, followed by an elevated-temperature
cure,
Date Recue/Date Received 2022-09-20
such as for a duration of from about 1 to about 4 hours, or such as from about
1 to 2
hours.
[0051] At block 306, the exemplary method 300 may include forming the
abrasion resistant layer 210 (FIG. 2) at least partially covering the silicone
elastomer
layer 208. The abrasion resistant layer 210 may be formed using a formulation
as
described herein, and the formulation and may be applied by conventional
spraying or
rolling techniques, or the like. The abrasion resistant layer 210 may include
a fiber-
reinforced elastomeric material as described herein. The abrasion resistant
layer 210
may be applied in a series of sublayers. Respective sublayers of the abrasion
resistant
layer 210 may have a thickness of from about 100 micrometers (gm) to about 500
gm, such as from about 200 gm to about 400 gm. The number of sublayers may be
determined based on the desired total thickness of the abrasion resistant
layer 210 and
the thickness of the respective sublayers. By way of example, an exemplary
abrasion
resistant layer 210 may include from about 2 to about 40 sublayers, such as
from
about 5 to about 10 sublayers, such as from about 10 to about 20 sublayers, or
from
about 20 to about 40 sublayers. The sequential sublayers may be applied after
solvent
in the previous sublayer has flashed off but prior to fully curing. In some
embodiments, application of the abrasion resistant layer 210 to the silicone
elastomer
layer 208 may commence after the silicone elastomer layer 208 has fully cured.
Additionally, or in the alternative, the abrasion resistant layer 210 may be
applied to
the silicone elastomer layer 208 prior to curing the silicone elastomer layer
208, such
as prior to fully curing the silicone elastomer layer 208. For example, the
first
sublayer of the abrasion resistant layer 210 may be applied to the last
sublayer of the
silicone elastomer layer 208 after solvent from the silicone elastomer layer
208 has
flashed off but prior to fully curing.
[0052] Forming the abrasion resistant layer 210 may include at least
partially
curing the abrasion resistant layer 210. For example, after the abrasion
resistant layer
210 has been applied to the desired thickness, the abrasion resistant layer
210 may be
at least partially cured, preferably fully cured. In some embodiments, the
abrasion
resistant layer 210 and the silicone elastomer layer 208 may be cured
concurrently,
such as when the abrasion resistant layer 210 has been applied prior to fully
curing the
silicone elastomer layer 208. The abrasion resistant layer 210 may be cured at
an
21
Date Recue/Date Received 2022-09-20
ambient temperature of from about 20 C to about 30 C, and a relative
humidity of
from about 30% to about 90%, such as from about 40% to about 70%. At an
ambient
temperature, the cure time may be about 24 hours. Additionally, or in the
alternative,
the abrasion resistant layer 210 may be cured at an elevated temperature of
from about
30 C to about 70 C, such as from about 55 C to about 65 C. In some
embodiments, the abrasion resistant layer 210 may be cured at such an elevated
temperature, for example, in an oven, heated curing chamber, or the like,
after initially
being partially cured at an ambient temperature. For example, the abrasion
resistant
layer 210 may receive an ambient-temperature cure, such as for a duration of
from
about 2 to about 6 hours, followed by an elevated-temperature cure, such as
for a
duration of from about 1 to about 4 hours, or such as from about 1 to 2 hours.
[0053] In some embodiments, the wall 200 of the aircraft engine component
100
may include the surface treatment 212 (FIG. 2). Additionally, or in the
alternative,
the exemplary method 300 may optionally include, at block 308, imparting the
surface
treatment 212 to at least a portion of the surface 202 of the wall 200 of the
component
100. The surface treatment 212 may include a chemical conversion coating
and/or an
anodizing coating. The surface treatment 212 and/or the surface 202 of the
wall 200
of the component 100 may be cleaned with a solvent-wetted clean cloth prior to
applying the prime layer 206. The prime layer 206 may be farmed in a manner
that at
least partially covers the surface treatment 212 imparted to the surface 202
of the wall
200 of the component 100.
[0054] The protective coating 108 may be applied to internal or external
surfaces
202 of the wall 200 of the component 100. The protective coating 108 may be
applied to new or refurbished components 100. In some embodiments, a pre-
existing
coating may be removed from the component 100 prior to applying the protective
coating 108 in accordance with the present disclosure. Such a pre-existing
coating
may be removed with water, solvents, stripping agents, abrasives, or the like,
for
example, using conventional surface preparation techniques. For example, a pre-
existing coating may be removed by way of high-pressure jetting of water
and/or
solvents, blasting with micro-abrasives, and/or soaking in a solution that
includes a
solvent or stripping agent.
22
Date Recue/Date Received 2022-09-20
[0055] Further aspects of the present disclosure are provided by the
subject matter
of the following clauses:
[0056] An aircraft engine component, comprising: a wall comprising an
aluminum alloy and/or a magnesium alloy; and a protective coating at least
partially
covering a surface of the wall, the protective coating comprising: a prime
layer at
least partially covering the surface of the wall, the prime layer comprising a
silane
coupling agent and an organic titanate; a silicone elastomer layer at least
partially
covering the prime layer, the silicone elastomer layer comprising one or more
filler
materials dispersed in a matrix of cross-linked silicone polymers; and an
abrasion
resistant layer at least partially covering the silicone elastomer layer, the
abrasion
resistant layer comprising a fiber-reinforced elastomeric material.
[0057] The aircraft engine component of any clause herein, wherein the
prime
layer 206 has a thickness of from 25 micrometers to 50 micrometers.
[0058] The aircraft engine component of any clause herein, wherein the
silicone
elastomer layer has a thickness of from 1,000 micrometers to 10,000
micrometers.
[0059] The aircraft engine component of any clause herein, wherein the
abrasion
resistant layer has a thickness of from 150 micrometers to 500 micrometers.
[0060] The aircraft engine component of any clause herein, wherein the
silane
coupling agent comprises a trialkoxysilane, a monoalkoxysilane, and/or a
dipodal
silane, and wherein preferably, the silane coupling agent comprises one or
more of:
tetramethoxysilane, methyl silicate, tetraethyoxysilane, ethyl polysilicate,
tetrapropoxysilane, tetraisopropoxysilane, tetrabutoxysilane, or
tetrakisbutoxyethoxysilane.
[0061] The aircraft engine component of any clause herein, wherein the
organic
titanate comprises one or more of: ethyl acetoacetate titanate, di-iso-butoxy
titanium,
di-n-butoxy titanium, di-iso-propoxy titanium, n-Butyl polytitanate, tetra n-
Butyl
titanate, titanium butoxide, titanium ethylacetoacetate, or titanium
tetraisopropoxide.
[0062] The aircraft engine component of any clause herein, wherein the
prime
layer is applied using a solution that comprises: light aliphatic naphtha in
an amount
of from 75 to 95 wt.%; tetrakis2-butoxyethyl orthosilicate in an amount of
from 4 to 6
wt.%; and tetra n-Butyl titanate in an amount of from 4 to 6 wt.%.
23
Date Recue/Date Received 2022-09-20
[0063] The aircraft engine component of any clause herein, wherein the
silicone
elastomer layer comprises a one-component room-temperature-vulcanizing
silicone or
a two-component room-temperature-vulcanizing silicone.
[0064] The aircraft engine component of any clause herein, wherein the
silicone
elastomer layer comprises a silicone polymer derived from one or more
polyorganosiloxanes, and wherein preferably, the one or more
polyorganosiloxanes
comprises: polydimethylsiloxane, polymethylhydrogensiloxane,
dimethyidiphenylpolysiloxane, dimethyl/methylphenylpolysiloxane,
polymethylphenylsiloxane, methylphenyl/dimethylsiloxane, vinyldimethyl
terminated
polydimethylsiloxane, vinylmethyl/dimethylpolysiloxane, vinyldimethyl
terminated
vinylmethyl/dimethylpolysiloxane, divinylmethyl terminated
polydimethylsiloxane,
vinylphenylmethyl terminated polydimethylsiloxane, dimethylhydro terminated
polydimethylsiloxane, methylhydro/dimethylpolysiloxane, methylhydro terminated
methyloctylpolysiloxane, methylhydro/phenylmethyl polysiloxane, and/or fluoro-
modified polysiloxane.
[0065] The aircraft engine component of any clause herein, wherein the
silicone
elastomer layer comprises one or more filler materials dispersed in a matrix
of cross-
linked silicone polymers, and wherein preferably, the one or more filler
materials
comprises: glass microspheres, glass fibers, cenospheres, fumed silica,
precipitated
silica, silica fibers, silicon dioxide, silicon carbide, titanium dioxide,
zinc oxide, rare
earth minerals, silicate minerals, inosilicates, aluminum silicate, alumina
trihydrate,
polyepoxide microparticles, phenolic resin microspheres, ceramics, carbon
fibers,
carbon black, graphene, cellulosic fibers, and/or cork.
[0066] The aircraft engine component of any clause herein, wherein the
silicone
elastomer layer comprises one or more filler materials that have an average a
cross-
sectional width of from 10 nanometers to 1,000 micrometers.
[0067] The aircraft engine component of any clause herein, wherein the
silicone
elastomer layer comprises a total filler content of from 1 vol.% to 90 vol.%.
[0068] The aircraft engine component of any clause herein, wherein the
silicone
elastomer layer comprises a silanization agent, and wherein preferably, the
silanization agent comprising an aminosilane, a glycidoxysilane, and/or a
mercaptosilane.
24
Date Recue/Date Received 2022-09-20
[0069] The aircraft engine component of any clause herein, wherein the
silicone
elastomer layer has one or more of the following properties: a thermal
conductivity at
38 C of from 0.05 W/mK to 0.15 W/mK, as measured according to ASTM C177; a
specific heat at 24 C of from 1.0 kJ/kg-K to 1.6 kJ/kg-K, as measured
according to
ASTM E1269-11 2018; an ablation temperature of from 450 C to 600 C, as
measured according to ASTM E285-80 2002; and a heat of ablation of from 40
MJ/kg
to 70 MJ/kg, with a heat exposure of 330 kJ/m2-sec, at as measured according
to
ASTM E458 ¨08 2020.
[0070] The aircraft engine component of any clause herein, wherein the
silicone
elastomer layer has one or more of the following properties: a density of from
0.2
g/cm3 to 0.6 g/cm3; and a Shore A hardness of from 30 to 80, as measured
according
to ASTM D2240-15e1.
[0071] The aircraft engine component of any clause herein, wherein the
silicone
elastomer layer comprises room-temperature-vulcanizing silicone, glass
microspheres,
silicone oil, fumed silica, and 3-aminopropyltriethoxysilane.
[0072] The aircraft engine component of any clause herein, wherein the
silicone
elastomer layer comprises one or more of: one or more silicone polymers in an
amount of from 22 wt.% to 26 wt.%; silica fibers in an amount of from 1 wt.%
to 5
wt.%; carbon fibers in an amount of from 1 wt.% to 5 wt.%; silica microspheres
in an
amount of from 30 wt.% to 40 wt.%; phenolic resin microspheres in an amount of
from 4 wt.% to 8 wt.%; and cork in an amount of from 20 wt.% to 40 wt.%.
[0073] The aircraft engine component of any clause herein, wherein the
fiber-
reinforced elastomeric material of the abrasion resistant layer comprises one
or more
silicone polymers and one or more fibrous reinforcing materials, and wherein
preferably, the one or more fibrous reinforcing materials comprises: glass
fibers,
basalt fibers, carbon fibers, ceramic fibers, aramid fibers, polycrystalline
fibers,
and/or polysiloxane fibers.
[0074] The aircraft engine component of any clause herein, wherein the
fiber-
reinforced elastomeric material of the abrasion resistant layer comprises one
or
thermoplastic materials, and wherein preferably, the one or more thermoplastic
materials comprises one or more of the following: an acrylic, a polyamides, a
polylactic acid, a polybenzimidazole, a polycarbonate; a polyether sulfone, a
Date Recue/Date Received 2022-09-20
polyoxymethylene, a polyether ether ketone, a polyetherimide, a polyphenylene
oxide, a polyphenylene sulfide, or a polytetrafluoroethylene.
[0075] The aircraft engine component of any clause herein, wherein the
fiber-
reinforced elastomeric material of the abrasion resistant layer comprises one
or
thermosetting materials, and wherein preferably, the one or more thermosetting
materials comprises one or more of the following: an epoxy resin, a polyester
resin, a
polyurethane, or a vinyl ester resin.
[0076] The aircraft engine component of any clause herein, wherein the one
or
more fibrous reinforcing materials have an average length of from 1 micrometer
to
10,000 micrometers; and/or wherein the one or more fibrous reinforcing
materials
have an average cross-sectional width of from 1 um to 50 um.
[0077] The aircraft engine component of any clause herein, wherein the
fiber-
reinforced elastomeric material comprises a total fibrous reinforcing material
content
of from 1 vol.% to 60 vol.%.
[0078] The aircraft engine component of any clause herein, wherein the
abrasion
resistant layer has one or more of the following properties: a density of from
0.9
g/cm3 to 1.4 g/cm3; and a Shore A hardness of from 40 to 90, as measured
according
to ASTM D2240-15e1.
[0079] The aircraft engine component of any clause herein, wherein the
abrasion
resistant layer has one or more of the following properties: a thermal
conductivity at
38 C of from 0.10 W/mK to 0.25 W/mK, as measured according to ASTM C177; a
specific heat at 38 C of from 0.9 kJ/kg-K to 1.5 kJ/kg-K, as measured
according to
ASTM E1269-11 2018; and an ablation temperature of from 450 C to 600 C, as
measured according to ASTM E285-80 2002.
[0080] The aircraft engine component of any clause herein, wherein the wall
comprises a surface treatment, and wherein preferably, the surface treatment
comprising a chemical conversion coating or an anodizing coating.
[0081] The aircraft engine component of any clause herein, wherein the
component 100 comprises at least one of: a turbomachine casing, a combustion
chamber, an exhaust duct, a bypass duct, a heat exchanger, a fuel system
component,
an oil system component, and a firewall.
26
Date Recue/Date Received 2022-09-20
[0082] The aircraft engine component of any clause herein, wherein the
component 100 comprises at least one of: a gearbox and an oil tank.
[0083] The aircraft engine component of any clause herein, wherein the
component comprises a gearbox, the gearbox comprising an epicyclic gear
assembly.
[0084] A protective coating-kit for applying a protective coating to an
aircraft
engine component, the protective coating-kit comprising: a prime layer for at
least
partially covering a wall of an aircraft component, the prime layer comprising
a silane
coupling agent and an organic titanate; a silicone elastomer layer for at
least partially
covering the prime layer, the silicone elastomer layer comprising one or more
filler
materials dispersed in a matrix of cross-linked silicone polymers; and an
abrasion
resistant layer for at least partially covering the silicone elastomer layer,
the abrasion
resistant layer comprising a fiber-reinforced elastomeric material; wherein
upon
having applied the protective coating to the aircraft engine component.
[0085] The protective coating-kit of any clause herein, wherein the
aircraft engine
component and/or the prime layer is configured according to any clause herein.
[0086] A method of protecting an aircraft engine component from a heat
source,
the method comprising: applying a prime layer to a wall of an aircraft engine
component, the prime layer comprising a silane coupling agent and an organic
titanate; applying a silicone elastomer layer to the prime layer, the silicone
elastomer
layer comprising one or more filler materials dispersed in a matrix of cross-
linked
silicone polymers; and applying an abrasion resistant layer to the silicone
elastomer
layer, the abrasion resistant layer comprising a fiber-reinforced elastomeric
material.
[0087] The method of any clause herein, wherein the aircraft engine
component
and/or the prime layer is configured according to any clause herein.
[0088] This written description uses exemplary embodiments to describe the
presently disclosed subject matter, including the best mode, and also to
enable any
person skilled in the art to practice such subject matter, including making
and using
any devices or systems and performing any incorporated methods. The patentable
scope of the presently disclosed subject matter is defined by the claims, and
may
include other examples that occur to those skilled in the art. Such other
examples are
intended to be within the scope of the claims if they include structural
elements that
do not differ from the literal language of the claims, or if they include
equivalent
27
Date Recue/Date Received 2022-09-20
structural elements with insubstantial differences from the literal languages
of the
claims.
28
Date Recue/Date Received 2022-09-20
