Conductive Anti-icing coating system and method

Abstract

To provide a method of forming a multi-layer type conductive anti-icing coating system used for coating a vane-shaped component, and a method of forming the multi-layer type conductive anti-icing coating system.SOLUTION: The present disclosure provides a method of coating a substrate. The method includes depositing a conductive coating including a conductive material on a substrate to form a conductive layer having a sheet resistivity of about 10 Ω / sq. to about 1,000 Ω / sq., and depositing an anti-icing layer containing a nano material on the conductive layer to form a coating system.SELECTED DRAWING: None

Description

[Technical Field]

[0001] Aspects of the present disclosure relate to conductive anti-icing coating systems and methods for making and using the same. [Background technology]

[0002]

[0002] Cold weather conditions encourage the accumulation of ice on vehicle surfaces. To remove the ice, large amounts of chemicals are often sprayed on the ice to promote melting. Additionally or alternatively, electrically heating the vehicle surface to melt the ice involves large energy consumption to promote adequate de-icing. Each large amount of chemical and / or energy consumption represents a cost burden to the vehicle user.

[0003] De-icing is particularly challenging for airfoils such as the rotor blades of rotorcraft such as helicopters. Prior art de-icing concepts applied to rotorcraft include electro-thermal ice protection systems, which remain the only systems approved by the Federal Aviation Administration and the Department of Defense for implementation on rotor blades.

[0004]

[0004] Although heater designs are constantly improving, many rotor blade materials do not possess sufficient mechanical strength to be integrated into modern high strain designs.

[0005] Another challenge in rotor blade technology is the design of effective and reliable de-icing materials that are compatible with edge erosion protection layers (e.g., titanium, nickel, and polyurethane) disposed adjacent to the rotor blade surface. Erosion coatings are typically thermally insulating, which requires significant energy expenditure for adequate de-icing of the rotor blade surface. Therefore, conventional de-icing materials lack sufficient electrical properties in addition to durable erosion impact protection for life against harsh environments. Conventional surface coatings on aircraft, and rotor blade vehicle components in particular, typically are not highly conductive, having sheet resistivities ranging from hundreds of kilohms to tens of megahms. Therefore, conventional surface coatings on aircraft can cause electrical charges to accumulate on the aircraft surface (and other components). In addition to being unable to dissipate electrical charge accumulation, conventional coatings could be further improved. For example, performance with respect to durability parameters such as rain erosion, resistance to UV light, resistance to high temperatures, resistance to low temperatures, poor flexibility, and resistance to damage from sand and hail could be further improved over conventional surface coatings for surfaces of vehicles such as aircraft exposed to harsh conditions.

[0006] What is needed are materials that are electrically conductive and provide other improved properties, as well as methods for making and using such materials. Summary of the Invention

[0007] In some embodiments, a method of coating a substrate includes depositing a conductive coating over the substrate, the conductive coating including a conductive material to form a conductive layer having a sheet resistivity of about 10 Ω / □ to about 1000 Ω / □, and depositing an anti-icing layer over the conductive layer, the anti-icing layer including a nanomaterial to form a coating system.

[0008] In some embodiments, a coating system is provided having a conductive layer including a conductive material, the conductive layer having a sheet resistivity of about 100 Ω / □ to about 1000 Ω / □, and an anti-icing layer including a nanomaterial, the anti-icing layer disposed on the conductive layer.

[0009] In some embodiments, a coating system is provided having a conductive layer comprising a conductive material. The conductive layer has a sheet resistivity of about 100 Ω / □ to about 1000 Ω / □. The coating system includes an anti-icing layer comprising a hydrophobic material with low interfacial free energy. The anti-icing layer is disposed on the conductive layer.

[0010] In some embodiments, a composite airfoil is provided having a root section having a first surface, a mid section having the first surface and coupled to the root section at a first end, and a tip section having the first surface and coupled to a second end of the mid section at the first end. A coating system is disposed on the first surface of the root section, the first surface of the mid section, the first surface of the tip section, or a combination thereof. The coating system includes a conductive layer including a conductive material. The coating system includes an anti-icing layer having a nanomaterial disposed on the conductive layer.

[0011]

[0011] In order that the above-mentioned features may be understood in detail, the above briefly summarized description will now be more particularly described by reference to exemplary embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only typical embodiments of the present disclosure and therefore should not be considered as limiting the scope of the present disclosure, since the present disclosure may admit of other equally effective embodiments. [Brief explanation of the drawings]

[0012] [Figure 1A]

[0012] FIG. 1 is a perspective view of a rotor blade according to some aspects of the present disclosure. [Figure 1B]

[0013] FIG. 1B is a cross-sectional exploded view of the rotor blade of FIG. 1A according to some embodiments of the present disclosure. [Figure 1C]

[0014] FIG. 2 is an enlarged cross-sectional view of a rotor blade according to some aspects of the present disclosure. [Figure 1D]

[0015] FIG. 2 is an enlarged cross-sectional view of a rotor blade according to some aspects of the present disclosure. [Figure 1E]

[0016] FIG. 2 is an enlarged cross-sectional view of a rotor blade according to some aspects of the present disclosure. [Figure 2]

[0017] FIG. 1 is a side view of an exemplary conductive anti-icing coating system according to some aspects of the present disclosure. [Figure 3]

[0018] FIG. 1 is a flow diagram illustrating a method of forming a coating system according to some aspects of the present disclosure. [Figure 4]

[0019] 1 is a comparative graph depicting the total power required for various coatings, according to some aspects of the present disclosure.

[0013]

[0020] For ease of understanding, the same reference numerals have been used, where possible, to designate identical elements that are common to multiple figures. The drawings are not drawn to scale and may be simplified for clarity. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further description. DETAILED DESCRIPTION OF THE INVENTION

[0014]

[0021] Aspects of the present disclosure generally relate to a multi-layer, electrically conductive, anti-icing coating system and a method for forming the multi-layer, electrically conductive, anti-icing coating system. The material includes high conductivity and anti-icing properties. The electrically conductive anti-icing coating system can be used to coat an airfoil component. As used herein, an "airfoil" includes a substrate in the shape of a wing or blade (of a propeller, rotor, or turbine). An airfoil includes a rotor blade, which is a stationary wing surface of a rotary-wing aircraft or fixed-wing aircraft. An airfoil, such as a rotor blade, includes one or more surfaces, e.g., an exterior surface, and one or more components (e.g., those described in more detail below). As used herein, an "airfoil component" includes any suitable structure adapted to form an airfoil in combination with one or more other airfoil components.

[0015]

[0022] A rotor blade of the present disclosure includes one or more rotor blade components. As used herein, a "rotor blade component" includes any suitable structure adapted to form a rotor blade in combination with one or more other rotor blade components. FIG. 1A is a perspective view of a rotor blade according to some embodiments of the present disclosure. As shown in FIG. 1A, a rotor blade 100 of a main rotor assembly (not shown) is made up of a root section 102, a mid-section 104, and a tip section 106. Each of the sections 102, 104, and 106 can be any shape suitable for tailoring the aerodynamic properties of the rotor blade to accommodate increasing speed along the rotor blade's span. The lengths of the sections 102, 104, and 106 are substantially the same or within 10% of each other. The tip section 106 can include angled shapes such as anhedral, cathedral, gull, and bend, among others. The rotor blade sections 102, 104, 106 define a span of the rotor blade 100 between the axis of rotation A and the distal end 110 of the tip section 106 along a longitudinal axis P between the first edge 112 and the second edge 114.

[0016]

[0023] FIG. 1B is a cross-sectional exploded view of the rotor blade of FIG. 1A. As shown in FIG. 1B, the rotor blade 100 is fabricated from an upper skin 116, a core 118, a spar 120 (e.g., a main spar), a lower skin 122, and a leading edge assembly 124. The core 118 comprises a lightweight foam material, a honeycomb material, or a combination thereof. The skins 116 and 122 comprise one or more plies of prepreg composite material, such as a woven fiberglass material embedded in any suitable resin matrix material. The resin matrix material may include an epoxy resin, a polyimide polymer matrix composite, a bismaleimide high-temperature polymer matrix composite, an inorganic polymer, polybenzoxazole, polybenzoxazine, polyetheretherketone, or a combination thereof. Alternatively or additionally, the disclosed multi-layer conductive anti-icing coating system 150 may be disposed on (e.g., adjacent to) one or more components of the rotor blade, such as sections 102, 104, and / or 106, skins 116 and 122, core 118, edge assembly 124, counterweight assembly 126, and / or spar 120, as described in further detail below. The spar 120, core 118, and skins 116 and 122 are commonly referred to as a pocket assembly, the forward portion of which is covered by a leading edge assembly 124. The spar 120 comprises titanium, other metals, composite materials, or combinations thereof. In at least one embodiment, the spar 120, core 118, skins 116 and 122, and leading edge assembly 124 are divided into multiple segments that may include various combinations of spanwise lengths (as opposed to chordwise lengths).

[0017]

[0024] 1C, 1D, and 1E are enlarged cross-sectional views of the rotor blade of FIG. 1A. As shown in FIG. 1C, the edge assembly 124 can be made of a wear-resistant material layer 130, such as a titanium or nickel erosion layer, for protection against abrasion. The wear-resistant material layer 130 is optional and can be disposed (e.g., adhesively bonded) to a conductive anti-icing coating system 150. As used herein, "wear resistance" is measured using one or more methods, such as rain erosion according to ASTM G73-10, erosion rate-velocity dependence of materials at supersonic speeds according to STP 474, and abrasion resistance of organic coatings by abrasive shedding according to ASTM D968-17. As shown in FIG. 1D, the edge assembly 124 of the present disclosure includes a conductive anti-icing coating system 150 and does not include an additional wear-resistant material layer 130. As shown in FIG. 1D , in some embodiments, the conductive anti-icing coating system 150 includes abrasion resistance that reduces or eliminates the need for the additional abrasion-resistant material layer 130. In some embodiments, the conductive anti-icing coating system 150 of FIG. 1C or 1D includes silica, silicon carbide, alumina mica, aluminum flake, or one or more combinations thereof for additional abrasion resistance. The anti-icing effect is modified by adjusting the loading concentration and particle size. The conductive anti-icing coating system 150 is disposed (e.g., adhesively bonded) to the spar 120 and / or counterweight assembly 126. The edge assembly 124 may include any additional suitable abrasion-resistant and electrostatic dissipative materials. The adhesive bond may be a polyester adhesive and / or an epoxy adhesive. FIG. 1E shows electrodes 152 patterned on the component, each connected to a lead wire through which a voltage is applied to heat the electrode. The electrodes 152 have a length-to-width ratio (e.g., aspect ratio) greater than 1. An electrically conductive anti-icing coating system 150 is coated over one or more electrodes 152 .It has been found that the conductive anti-icing coating system 150 provides for the use of electrodes 152 having an aspect ratio greater than 1, such as an aspect ratio of 1.5 to 20, such as an aspect ratio of 2 to 10, such as an aspect ratio of 5 to 7. The ability to use electrodes having an aspect ratio greater than 1 reduces the overall weight of the component by requiring fewer leads to heat the electrodes 152.

[0018]

[0025] Counterweight assembly 126 is fabricated from filler material 136 within which weight 138 is located. Filler material 136 includes one or more plies of a prepreg composite material, such as a woven fiberglass material embedded in a suitable resin matrix material, with weight 138 located therein. The resin matrix material may be an epoxy resin, a polyimide high-temperature polymer matrix composite, a bismaleimide high-temperature polymer matrix composite, an inorganic polymer, polybenzoxazole, polybenzoxazine, polyetheretherketone, or a combination thereof. Counterweight assembly 126 is adhesively bonded to the edge of spar 120 such that it is positioned between conductive anti-icing coating system 150 and the edge of spar 120. Counterweight assembly 126 provides weight balance for rotor blade 100. In at least one embodiment, the counterweight assembly 126 is made from weights 138 that are foam, tungsten, lead, or a mixture thereof, spanning the span from the root section 102 to the tip section 106 to provide a weight distribution that balances the weight of the rotor blade 100.

[0019]

[0026] The materials of the present disclosure provide rapid surface heating of rotor blade surfaces and / or rotor blade components (e.g., to temperatures of about 100°C, such as about 150°C or higher), thereby reducing the energy consumption required for adequate de-icing of one or more components of the rotor blade surfaces and / or rotor blade components. As used herein, the term "de-icing" refers to the removal of snow, ice, or frost from a surface. Rapid surface heating is desirable and advantageous because it reduces the overall energy demands of a rotor blade heater compared to a typical rotor blade. Conventional heaters only melt the ice interface, allowing the centrifugal forces inherent in the rotating blade to remove the ice from the surface. If the heating rate is too low or heating is performed on a thin ice formation, the ice will not break off because the centrifugal forces are not large enough to break the ice / rotor bond. In such cases, the ice melts locally, and liquid water flows to the aft portion of the blade and refreezes. This process, called runback, is disadvantageous because the refreezing location is typically outside the area affected by the heater, and the ice cannot be removed with additional heater pulses. Additionally, the refreezing location near the maximum blade thickness is typically in a region that significantly reduces airfoil performance. The more rapidly the surface heats up, the faster the accumulated ice melts. The higher the applied power is based on the ice thickness and ice temperature. The higher the power, the faster the existing ice melts, increasing the likelihood of preventing ice buildup. The conductive anti-icing coating system 150 described herein has a heating rate that is equal to or greater than the rate at which ice accumulates.

[0020]

[0027] In at least one embodiment, there are no heaters within the rotor blade of the present disclosure. Furthermore, unlike typical rotor blade heaters, the material of the present disclosure may be disposed on or above the rotor blade spars 120. This allows for easy repair of the rotor blade components without substantial disassembly of the rotor blade, for example, to repair the heater.

[0021]

[0028] FIG. 2 is a side view of an exemplary conductive anti-icing coating system 150, e.g., a dual-layer conductive anti-icing coating system. The conductive anti-icing coating system 150 includes a conductive layer 206 disposed on a substrate 204. The substrate 204 can include one or more insulating layers 204B disposed on the surface of a component 204A. The insulating layer 204B can be formed from a resin material. Exemplary resin materials include epoxy, thermoplastic, phenolic, or silicone resins, which are characterized by durability and operable at high temperatures. In some embodiments, the resin material includes a heat-stable resin material, such as a thermosetting polymer or a thermoplastic polymer, e.g., polyurethane. The component 204A can be the airfoil component described in FIGS. 1A, 1B, and 1C. In some embodiments, the component 204A is a rotor. An aluminum foil is embedded in the rotor through a hub for power supply and electrically connected to the conductive anti-icing coating system 150 described herein. In some embodiments, the power requirement for deicing the substrate 204 is approximately 5 watts / inch. 2 from approximately 30 watts per inch 2 , for example, about 5 watts / inch 2 from approximately 15 watts per inch 2 , or about 10 watts per inch 2 from approximately 20 watts per inch 2 In some embodiments, component 204A and insulating layer 204B each have a thickness of about 12.7 μm to about 127 μm. The thickness can be any suitable thickness depending on the type of component to provide electrical insulation.

[0022]

[0029] The weight percentage of the conductive material in the conductive layer 206 is about 0.1 wt % to about 80 wt %, for example, about 20 wt % to about 60 wt %, for example, about 10 wt % to about 25 wt %, based on the total weight of the conductive layer including the conductive material. The conductive material can be polyaniline (PANI), poly(ethylenedioxythiophene) (PEDOT), or a combination thereof. The conductive material can be doped with one or more sulfonic acids. The conductive material can be PANI or PEDOT doped with one or more of poly(styrene sulfonate) (PSS), dinonylnaphthalene sulfonic acid (DNNSA), and dodecylbenzene sulfonic acid (DDBSA). The conductive material provides lightning strike protection, such as static charge dissipation and electromagnetic shielding. The conductive material is selected to provide compatibility with other components of the conductive anti-icing coating system 150. Compatibility includes properties such as solubility, miscibility, and overall ease of processing. Additionally, the conductive material provides high conductivity and stability for use in de-icing.

[0023]

[0030] The conductive layer 206 further includes an adhesive material. The adhesive material can be a thermoplastic such as polyurethane, polyvinyl butyral, acrylate, epoxy, glycidyl-Si-Zr-containing sol-gel, polyester, a resin such as phenoxy resin, a sealant such as polysulfide, or a mixture thereof. The adhesive material for the conductive layer 206 is selected based on its compatibility with the underlying surface (e.g., substrate, electrode, insulating layer) and the anti-icing layer. The conductive layer 206 can include a thermal stabilizer such as a metal oxide, e.g., zinc oxide. The weight percentage of the thermal stabilizer in the conductive layer 206, based on the total weight of the conductive layer 206, can be about 0.1 wt % to about 10 wt %, for example, about 1 wt % to about 2 wt %, or about 3 wt % to about 5 wt %. The conductive layer 206 does not necessarily need to include a thermal stabilizer. The thermal stabilizer provides thermal and ultraviolet (UV) stability. The thermal stabilizer can function as both a thermal stabilizer and a nanomaterial. The thermal stability function may be secondary to the nanomaterial function described herein.

[0024]

[0031] The conductive layer 206 can be between about 0.1 μm and about 100 μm thick, such as about 1 μm to about 8 μm, for example, about 2 μm to about 6 μm, or about 15 μm to about 35 μm. The thickness of the conductive layer 206 is determined based on the component's function, expected ice conditions, expected exposure to abrasive conditions, and the component's tendency to ice. A thicker conductive layer 206 provides better resistance to abrasive conditions and enhanced de-icing properties. The electrical properties of the disclosed materials enable de-icing of airfoils, such as rotor blade surfaces and / or rotor blade components. The material's higher conductivity allows for a reduced thickness of the material layer compared to materials with lower conductivity. The reduced thickness reduces the overall weight of the component. The thickness controls the electrical resistance of the conductive anti-icing coating system 150. Thicker coatings are more conductive and provide higher power. A thin material layer, less than about 1 micron, is advantageous for applying a conductive surface within a confined structure, such as a rotor blade spar. Conventional materials placed on the spar have thicknesses of, for example, thousands of inches, which can hinder the bonding of the material to the erosion protection layer. Bonding is affected by substrates that are incompatible with the erosion protection layer or have poor adhesion to the erosion protection layer. In at least one embodiment, the sheet resistivity (e.g., ohms per square (Ω / □) is the unit of sheet resistance) of materials used in the conductive layer 206 of the present disclosure is greater than 10 3 From 10 7 Ω (per square) per ASTM D4496-21; 10 3 As measured by ASTM B193-20 in ohms per square, it is from about 1 to about 10,000 ohms per square, for example from about 10 ohms per square to about 100 ohms per square, or from about 50 ohms per square to about 150 ohms per square, for example from about 200 ohms per square to about 500 ohms per square.

[0025]

[0032] Conductivity is proportional to the inverse of sheet resistivity and provides electrostatic dissipation and de-icing. In aerospace applications requiring durable coatings, a thin layer of conductive layer 206 may not be durable enough by itself, and the conductive coating may use high energy to operate. It has been discovered that an anti-icing layer 208 can be placed on top of the thin conductive layer 206 to reduce the amount of energy required to operate the conductive coating. Without the anti-icing layer 208, a certain amount of power (e.g., P) is required to prevent ice from accumulating. With a perfect anti-icing coating that is 100% effective (e.g., a completely icephobic coating), no power would be required. If the anti-icing coating were 50% effective, the power required would be P / 2. The anti-icing layer 208 reduces power demands. The conductive anti-icing coating system 150 is particularly useful in areas where large amounts of erosion are observed using conventional coatings, such as leading edge wing or rotor blade surfaces. Without being bound by any theory, it is believed that the anti-icing layer 208 contributes to preventing ice buildup when supercooled water vapor contacts the surface of the component. The conductive layer 206 is electrically heated, melting any accumulated ice. The dual-layer conductive anti-icing coating system 150 is more effective and uses less energy than each individual layer used alone. The composition and thickness of each layer of the conductive anti-icing coating system 150 can be tailored to the component being coated. Without the anti-icing layer 208, as in conventional coating systems, the conductive layer 206 would use more energy to adequately melt accumulated ice. Conventional de-icing systems may de-ice certain portions of the substrate 204, while ice accumulates on other portions of the substrate 204. As ice buildup migrates to different portions of the surface, imbalances can occur. Due to its hydrophobic properties, the de-icing systems described herein are adaptable to temperature fluctuations across the surface, and the movement of ice buildup on various portions of the substrate surface is further assisted by the heating provided by the conductive layer.

[0026]

[0033] The anti-icing layer 208 includes a substrate. In some embodiments, the substrate is a polymer selected from polyurethane, polyvinyl butyral, polyacrylate, epoxy, glycidyl-Si-Zr-containing sol-gel, polyester, phenoxy resin, polysulfide, fluoropolymer, polysiloxane, or a mixture thereof. In some embodiments, the substrate is a polymer based on a fluoropolymer (e.g., polytetrafluoroethylene, polyvinylidene fluoride) or a polysiloxane (e.g., polydimethylsiloxane). In some embodiments, the substrate is a sol-gel, a silicon-based material, polyester, or a mixture thereof. In some embodiments, the substrate is a hydrophobic material, e.g., a material having a contact angle greater than 90 degrees according to ASTM D7334-08(2013). The substrate can be a fluoropolymer or a polysiloxane. The anti-icing layer 208 may further include a nanomaterial. Nanomaterials include silica, alumina, titania, zinc oxide, fluoropolymers, silicones, fluorine derivatives, polytetrafluoroethylene (PTFE) (e.g., Teflon) TMThe nanomaterial may be a glycol-based component (e.g., antifreeze), such as monoethylene glycol, monopropylene glycol, ethylene glycol, propylene glycol, propylene glycol methyl ether, or the like; a carbon-based nanomaterial; a carbon nanotube; graphene; graphene oxide; reduced graphene oxide; functionalized graphene; or a combination thereof. In some embodiments, the nanomaterial may be silica or a metal oxide, such as Al2O3, Cr2O3, or ZrO2. In some embodiments, the nanomaterial is a nanoparticle, a nanorod, a nanofiber, a nanosheet, or a combination thereof. Nanomaterials, such as nanorods, have random shapes and a variety of aspect ratios, e.g., greater than about 1.0, e.g., from about 1.5 to about 2.0, or about 2.5 or greater, e.g., greater than 100, e.g., greater than 1,000, e.g., greater than 1,000,000. In some embodiments, nanomaterials are incorporated into the substrate as fillers or to impart surface roughness to the anti-icing layer 208. Surface roughness is measured using any method known in the industry, such as Geometric Product Specification (GPS) based on ISO 3274:1996, surface texture:profile methods, or nominal characteristics of contact (stylus) instruments. Surface roughness can also be measured using laser profilometry. As used herein, the term "aspect ratio" refers to the ratio of the largest length scale to the smallest length scale. The average length scale of the nanomaterials can be about 10 nm to about 500 nm, e.g., about 100 nm to about 200 nm, or about 250 nm to about 350 nm, as measured under a microscope, such as an atomic force microscope (AFM), a transmission electron microscope (TEM), or a scanning electron microscope (SEM). In some embodiments, the nanomaterials are carbon nanotubes of 10 nm to 10 cm, e.g., about 1000 nm to about 3 cm.

[0027]

[0034] The substrate of the anti-icing layer 208 comprises one or more materials that are the same as the adhesive material of the conductive layer 206. The inclusion of the same material(s) in the conductive layer 206 and the anti-icing layer 208 provides good interfacial adhesion at the coating interface 212 between the anti-icing layer 208 and the conductive layer 206. Enhanced interfacial adhesion is possible because the same materials in both layers bond to each other. In some embodiments, the nanomaterial in the anti-icing layer 208 is composed of the same material(s) as the thermal stabilizer in the conductive layer 206. In some embodiments, the conductive layer 206 and the anti-icing layer 208 each comprise polyurethane and ZnO in both layers, providing good interfacial adhesion and reduced thermal expansion / contraction (e.g., improved material compatibility) of the coating system. The anti-icing layer 208 provides good electrical insulation, e.g., zero surface sheet resistivity. The anti-icing layer 208 can include low surface energy additives or moisture-absorbing additives. The anti-icing layer 208 meets the rain erosion requirements of conventional aerospace stackups. The rain erosion requirements are measured by pivot arm rain erosion according to ASTM G73-10. In some embodiments, the nanomaterials include nanoparticles surface-modified with a hydrophobic material selected from the group consisting of alkylsilanes, alkyldisilazanes, fluoropolymers, and combinations thereof. The anti-icing layer 208 is hydrophobic (repells liquids), anti-icing (prevents freezing), and durable. As used herein, durable refers to lasting for at least one rotorcraft mission or multiple commercial flights. The nanomaterials disposed within the anti-icing layer 208 inhibit ice nucleation on the surface of the conductive anti-icing coating system 150. In particular, the surface can repel water, and ice accumulation is reduced and / or delayed at sub-freezing temperatures and pressures. The weight percentage of the substrate in the anti-icing layer 208 can be from about 5 wt % to about 90 wt %, for example, from about 10 wt % to about 40 wt %, based on the total weight of the anti-icing layer 208. It has been discovered that the conductive layer 206 and the anti-icing layer 208 together form a conductive anti-icing coating system 150 that provides improved durability and ice-phobic properties at a reduced film thickness compared to coatings consisting of either the conductive layer 206 or the anti-icing layer 208.The combination of conductive layer 206 and anti-icing layer 208 allows for a thinner coating system and / or lower power requirements due to the presence of anti-icing layer 208. The weight percentage of the nanomaterial in anti-icing layer 208 is about 0.5 wt% to about 25 wt%, e.g., about 10 wt% to about 20 wt%, or about 5 wt% to about 10 wt%. In some embodiments, anti-icing layer 208 can be about 0.1 μm to about 1500 μm thick, e.g., about 100 μm to about 1020 μm, e.g., about 200 μm to about 600 μm, or about 300 μm to about 500 μm thick. In some embodiments, anti-icing layer 208 is the same thickness as the conductive layer or within about 10% of the thickness of the conductive layer. In some embodiments, the ratio of the conductive layer thickness to the anti-icing layer thickness is about 1:1 to about 1:100, e.g., about 1:10 to 1:40. In some embodiments, the anti-icing layer 208 adds additional durability to the application of a thin conductive layer, e.g., about 0.1 μm to about 1 μm. The thickness of the anti-icing layer is increased relative to the conductive layer depending on durability requirements. The conductive layer 206 alone would not be durable enough for aerospace applications. The addition of the anti-icing layer 208 provides overall durability to the system and reduces the energy required for the conductive coating to function. Conventional conductive coatings use increased thicknesses to accommodate durability applications, and further increasing the thickness of conventional conductive coatings to achieve similar anti-icing properties would be too heavy for airworthiness.

[0028]

[0035] Epoxies include partially cured epoxies, two-part epoxy resins containing specific epoxy additions, catalysts (e.g., HYSOL® EA 956 epoxy resin available from Henkel Corporation of Bay Point, California), two-part systems containing both a resin and a curing agent (e.g., EPOFIX resin available from Struers A / S of Ballerup, Denmark), tetrafunctional epoxies such as triglycidyl ethers of aminophenols (e.g., Araldite MY 0500 or MY 0510 from Huntsman Advanced Materials, Monthey, Switzerland), N,N,N′,N′-tetraglycidyl-m-xylylenediamine (e.g., Araldite MY0720 or MY0721 from Huntsman Advanced Materials, Monthey, Switzerland), and mixtures thereof. Epoxies also include difunctional epoxies, such as bisphenol-A (Bis-A) or bisbisphenol-F (Bis-F)-based epoxies. Bis-A epoxy resins are commercially available as Araldite GY6010 (Huntsman Advanced Materials) or DER 331 available from Dow Chemical Company (Midland, Mich.). Bis-F epoxy resins are commercially available as Araldite GY281 and GY285 (Huntsman Advanced Materials). For example, epoxies are suitable as thermoset resins on the exterior of aircraft because they last behind or below the leading edge surface of erosion protection materials, for example, on rotor blades.

[0029]

[0036] Polyaniline can be, for example, a compound represented by the formula (I): TIFF2023027014000001.tif29170 (wherein x is a positive integer, e.g., an integer between about 10 and about 10,000), polyaniline, leucoemeraldine, emeraldine, and (per)nigraniline, mixtures thereof, salts thereof, or bases thereof. The polyaniline is unsubstituted, mono-, or multiply substituted (e.g., di-, tri-, or tetra-substituted), with each instance of substitution independently being alkyl (e.g., C1-C20 alkyl), aryl, amino, nitro, or halo (-F, -Cl, -Br, -I).

[0030]

[0037] Poly(ethylenedioxythiophene) can be, for example, a compound represented by formula (II): TIFF2023027014000002.tif60170, where x is a positive integer, e.g., an integer between about 10 and about 10,000, and / or a salt thereof. The poly(ethylenedioxythiophene) is unsubstituted, mono-substituted, or multiply substituted (e.g., di-, tri-, or tetra-substituted), with each instance of substitution independently selected from alkyl (e.g., C1-C20 alkyl), aryl, amino, nitro, and halo (-F, -Cl, -Br, -I).

[0031]

[0038] Poly(styrene sulfonate) can be, for example, a poly(styrene sulfonate) represented by formula (III): The poly(styrene sulfonate) and / or salt thereof has the formula: TIFF2023027014000003.tif59170, where x is a positive integer, e.g., an integer between about 10 and about 10,000. The poly(styrene sulfonate) is unsubstituted, mono-substituted, or multiply substituted (e.g., di-, tri-, or tetra-substituted), with each instance of substitution independently selected from alkyl (e.g., C1-C20 alkyl), aryl, amino, nitro, and halo (-F, -Cl, -Br, -I).

[0032]

[0039] The acrylate may be, for example, a compound represented by formula (IV): TIFF2023027014000004.tif45170

[0040] (wherein x is a positive integer, for example, an integer between about 10 and about 10,000) and / or a salt thereof. 1 and R 2 is independently C1-C20 alkyl or C1-C20 hydroxyalkyl. In at least one embodiment, R 2is methyl. Acrylates include hydroxyalkyl polyacrylates, hydroxyalkyl polymethacrylates, alkyl polyacrylates, and alkyl polymethacrylates. Examples of suitable hydroxyalkyl polyacrylates or hydroxyalkyl polymethacrylates include poly(2-hydroxyethyl acrylate), poly(2-hydroxy-1-methylethyl acrylate), poly(2-hydroxypropyl acrylate), poly(3-hydroxypropyl acrylate), poly(2-hydroxybutyl acrylate), poly(4-hydroxybutyl acrylate), poly(2-hydroxyethyl methacrylate), poly(2-hydroxy-1-methylethyl methacrylate), poly(2-hydroxypropyl methacrylate), poly(3-hydroxypropyl acrylate), poly(2-hydroxybutyl methacrylate), and poly(4-hydroxybutyl methacrylate), as well as acrylic or methacrylic acid esters of ethylene glycol and propylene glycol, such as poly(diethylene glycol acrylate). Also useful are hydroxy-containing esters and / or amides of unsaturated acids such as maleic acid, fumaric acid, and itaconic acid. In at least one embodiment, the hydroxy acrylic polymer is made from 5 to 35 weight percent, and in certain embodiments, 10 to 25 weight percent, of monoethylenically unsaturated hydroxy-containing monomers based on the total acrylate weight.Suitable alkyl polyacrylates and polymethacrylates include poly(methyl acrylate), poly(ethyl acrylate), poly(propyl acrylate), poly(isopropyl acrylate), poly(butyl acrylate), poly(isobutyl acrylate), poly(hexyl acrylate), poly(2-ethylhexyl acrylate), poly(nonyl acrylate), poly(lauryl acrylate), poly(stearyl acrylate), poly(cyclohexyl acrylate), poly(isodecyl acrylate), poly(phenyl acrylate), poly(isobornyl acrylate), Poly(methyl methacrylate), poly(ethyl methacrylate), poly(propyl methacrylate), poly(isopropyl methacrylate), poly(butyl methacrylate), poly(isobutyl methacrylate), poly(hexyl methacrylate), poly(2-ethylhexyl methacrylate), poly(nonyl methacrylate), poly(lauryl methacrylate), poly(stearyl methacrylate), poly(cyclohexyl methacrylate), poly(isodecyl methacrylate), poly(phenyl methacrylate), and poly(isobornyl methacrylate).

[0033]

[0041] The polyurethane may be, for example, a polyurethane having the formula (V): TIFF2023027014000005.tif40170, where x is an integer between about 10 and about 10,000. 1 , R 2 , R 3 , R 4 , and R 5 is independently hydrogen or C1-C20 alkyl. Polyurethanes include Aptek 2100A / B and Aerodur 3002 (available from Argosy International, Inc.). The polyurethanes are unsubstituted, mono-substituted, or multiply substituted (e.g., di-, tri-, or tetra-substituted), and each instance of substitution is independently alkyl (e.g., C1-C20 alkyl), aryl, amino, nitro, or halo (-F, -Cl, -Br, -I).

[0034]

[0042] FIG. 3 is a flow diagram illustrating a method for forming a conductive anti-icing coating system 150. The method 300 includes depositing 302 a conductive coating on a substrate to form a conductive layer 206. The substrate can be an airfoil component, such as a rotor blade surface and / or rotor blade component. In some embodiments, the substrate is a radome, engine inlet, airfoil, or other component subject to ice accumulation, such as a fixed wing or wind turbine. The substrate 204 can include one or more insulating layers 204B disposed on a surface of the component 204A. The insulating layer 204B can be deposited on the component 204A by various methods, such as brushing, painting, patterning, printing, any additive manufacturing method, or any combination of one or more of these. Each layer is deposited based on thickness control requirements. Notably, for thinner systems, spray application increases the deposition thickness by 0.4 to approximately 2 mils per pass, while brush application increases the deposition thickness by approximately 2-3 mils per pass. The insulating layer 204B can be cured by heat or chemical additives, among other processes. The curing can be partial or complete, depending on the application and implementation. The surface 210 of the insulating layer 204B is configured to receive the conductive layer 206, such as the conductive layer 206 described herein.

[0035]

[0043] Depositing the conductive layer 206 may include dissolving the conductive material and / or adhesive material of the conductive coating in a solvent prior to deposition. The solvent may be xylene, benzene, toluene, dimethyl sulfoxide, water, and mixtures thereof. Depositing may include flood coating, drop casting, dipping, spray coating, screen printing, slot die coating, flood coating, in-mold molding, co-curing, and / or inkjet printing. The method may further include depositing a thermal stabilizer, such as zinc oxide, on one or both of the conductive material and adhesive material. Alternatively, the thermal stabilizer may be suspended within one or both of the conductive material and adhesive material (e.g., using a solvent). The conductive layer 206 may be at least partially or fully cured. The conductive layer can be at least partially cured at a temperature of about 10° C. to about 200° C., e.g., about 10° C. to about 40° C., a pressure of about 3 Torr to about 760 Torr, e.g., about 500 Torr to about 760 Torr, and a relative humidity of less than about 50%, e.g., about 20% relative humidity to about 40% relative humidity, or about 60% relative humidity to about 90% relative humidity. In some embodiments, an interfacial layer is disposed between the conductive layer 206 and the anti-icing layer 208, or the conductive layer 206 is in direct contact with the anti-icing layer 208.

[0036]

[0044] The method 300 further includes depositing 304 an anti-icing layer 208 on the at least partially cured conductive layer 206 to form the conductive anti-icing coating system 150. The anti-icing layer 208 can be formed by dispersing nanomaterials within a polymer. The nanomaterials can be chemically and / or physically bonded to the polymer layer. The weight percentage of the nanomaterials can be about 5 wt % to about 25 wt % based on the weight of the anti-icing layer 208, and the anti-icing layer 208 is substantially free of conductive materials. Depositing the anti-icing layer 208 can use processes such as flow coating, drop casting, dipping, spray coating, brush coating, spin coating, roll coating, co-curing, electrocoating, screen printing, slot-die coating, flow coating, in-mold molding, co-curing, inkjet printing, or a combination of one or more thereof. The anti-icing layer 208 can be at least partially cured at a temperature of about 10°C to about 200°C, e.g., about 10°C to about 40°C, a pressure of about 3 Torr to about 760 Torr, e.g., about 500 Torr to about 760 Torr, and a relative humidity of less than about 50%, e.g., about 20% relative humidity to about 40% relative humidity, or about 60% relative humidity to about 90% relative humidity.

[0037]

[0045] Example

[0046] Data was generated (e.g., simulated) for example coating systems to compare coating system attributes, such as sheet resistivity, power density, and total power, as a function of variables such as coating thickness, conductive layer conductivity, and the aspect ratio of the underlying electrode. Table 1 summarizes data for an electrode with a width of 12.7 cm and a voltage of 150 V, while Table 2 summarizes data for an electrode with a width of 12.7 cm and a voltage of 190 V. The length of each electrode was determined based on the tabulated aspect ratio. For both tables, a conductive layer comprising a composition with a conductivity of 2 S / cm was used to simulate the total power required for different coating thicknesses (25 μm, 50 μm, and 75 μm), the aspect ratio of the electrode, and the percentage of the total coating system thickness that is the anti-icing layer 208 relative to the combined thickness of the anti-icing layer 208 and conductive layer 206. In particular, FIG. 4 is provided to compare the total power required for a coating system 402 without an anti-icing layer, a coating system 404 with a 50% anti-icing layer thickness (e.g., also represented as 50% anti-icing efficiency), and a coating system 406 with a 90% anti-icing layer thickness (e.g., also represented as 90% anti-icing efficiency). As shown, the power required for coating system 406 is reduced, which allows the gauge of the underlying conductive layer to be reduced to achieve the same de-icing capacity. The overall coating thickness, electrode aspect ratio, and anti-icing layer thickness can each be adjusted based on the application and de-icing requirements of the coating system. De-icing needs can be categorized as ice intensity, ranging from light, moderate, heavy, and very heavy. Light icing intensity corresponds to an accumulation rate of 0.6 cm / hr to 2.5 cm / hr, moderate icing intensity corresponds to an accumulation rate of 2.5 cm / hr to 7.5 cm / hr, severe icing intensity corresponds to an accumulation rate of 7.5 cm / hr or more, and severe icing intensity typically corresponds to icing conditions that cannot be managed by conventional de-icing systems. Icing intensity can be measured with an appropriate ice rate meter. An accumulation rate of 0.6 cm / hr requires approximately 3 W / cm to melt the ice.2 Therefore, a power density target is used to design the coating system and electrode structure specifically for the desired application and freeze strength. Power density is the total power over the area of ​​the electrode. For example, a 0.08 W / cm2 target is shown below. 2 The power density can be calculated by dividing the product of the current (e.g., 0.78 A) and voltage (150 V) by the area of ​​the electrode. The sheet resistivity is the inverse of the product of the conductivity (2 S / cm) and thickness of the coating system.

[0038]

[0047] Table 1 - 150V voltage TIFF2023027014000006.tif137170

[0039]

[0048] Table 2 - 190V voltage TIFF2023027014000007.tif137170

[0040]

[0049] Additional Aspects

[0050] Clause 1. A method of coating a substrate, the method comprising: depositing a conductive layer on the substrate, the conductive layer comprising a conductive material, the conductive layer having a sheet resistivity of about 10 Ω / □ to about 1000 Ω / □; and depositing an anti-icing layer on the conductive layer, the anti-icing layer comprising a nanomaterial, to form a conductive anti-icing coating system.

[0041]

[0051] Clause 2. The method of clause 1, further comprising at least partially curing the conductive layer prior to depositing the anti-icing layer over the conductive layer.

[0042]

[0052] Clause 3. The method of clause 2, wherein at least partially curing the conductive layer comprises at least partially curing the conductive layer at about 10°C to about 40°C, about 500 Torr to about 760 Torr, and a relative humidity of less than about 50%.

[0043]

[0053] Clause 4. The method of any of clauses 1 to 3, wherein the conductive material is selected from the group consisting of polyaniline, poly(ethylenedioxythiophene), poly(styrenesulfonate), and mixtures thereof.

[0044]

[0054] Clause 5. The method of any of clauses 1 to 4, further comprising combining the conductive material with an adhesive material selected from the group consisting of polyurethane, polyvinyl butyral, polyacrylate, epoxy, glycidyl-Si—Zr-containing sol-gel, polyester, phenoxy resin, polysulfide, and mixtures thereof.

[0045]

[0055] Clause 6. The method of any of clauses 1 to 5, wherein combining the conductive material with the adhesive material includes dissolving the conductive material in a solvent prior to combining the adhesive material with the conductive material.

[0046]

[0056] Clause 7. The method of any of clauses 1 to 6, wherein the anti-icing layer comprises a polymer selected from the group consisting of polyurethane, polyvinyl butyral, polyacrylate, epoxy, glycidyl-Si—Zr-containing sol-gel, polyester, phenoxy resin, polysulfide, and mixtures thereof.

[0047]

[0057] Clause 8. The method of any of clauses 1 to 7, wherein the conductive layer further comprises an adhesive material selected from the group consisting of polyurethane, polyvinyl butyral, polyacrylate, epoxy, glycidyl-Si-Zr containing sol-gel, polyester, phenoxy resin, polysulfide, and mixtures thereof, and wherein the polymer and adhesive material are the same.

[0048]

[0058] Clause 9. The method of any of clauses 1 to 8, wherein the anti-icing layer comprises nanomaterials in an amount of about 5 wt% to about 25 wt%, based on the weight of the anti-icing layer, and the anti-icing layer is substantially free of conductive materials.

[0049]

[0059] Clause 10. The method of any of clauses 1 to 9, further comprising combining a heat stabilizer with the conductive material, wherein the conductive layer comprises the heat stabilizer in an amount less than 5 wt %, based on the weight of the conductive layer.

[0050]

[0060] Clause 11. The method of any of clauses 1 to 10, wherein coating the substrate includes coating one or more electrodes disposed on the substrate.

[0051]

[0061] Clause 12. The method of any of clauses 1 to 11, wherein the anti-icing layer is deposited by pouring, drop casting, dipping, spraying, brushing, spin coating, roll coating, in-mold coating, co-curing, or electrocoating.

[0052]

[0062] Clause 13. The method of any of clauses 1 to 12, further comprising curing the anti-icing layer at about 10°C to about 40°C, about 500 Torr to about 760 Torr, and a relative humidity of less than about 50%.

[0053]

[0063] Clause 14. The method of any of clauses 1 to 3, further comprising dissolving the conductive material in a solvent selected from the group consisting of xylene, benzene, toluene, dimethyl sulfoxide, water, and mixtures thereof.

[0054]

[0064] Clause 15. The method of any of clauses 1 to 14, wherein the conductive layer is deposited by flow coating, drop casting, dipping, spray coating, brush coating, spin coating, roll coating, in-mold coating, co-curing, or electrocoating.

[0055]

[0065] Clause 16. A coating system comprising: a conductive layer comprising a conductive material, the conductive layer having a sheet resistivity of about 100 Ω / □ to about 1000 Ω / □; and an anti-icing layer comprising a nanomaterial, the anti-icing layer disposed on the conductive layer.

[0056]

[0066] Clause 17. The coating system of clause 16, wherein the conductive material is selected from the group consisting of polyaniline, poly(ethylenedioxythiophene), poly(styrenesulfonate), and mixtures thereof.

[0057]

[0067] Clause 18. The coating system of clause 16 or 17, wherein the conductive layer comprises an adhesive material selected from the group consisting of polyurethane, polyvinyl butyral, polyacrylate, epoxy, glycidyl-Si-Zr containing sol-gel, polyester, phenoxy resin, polysulfide, and mixtures thereof.

[0058]

[0068] Clause 19. The coating system of any of clauses 16 to 18, wherein the nanomaterial is selected from the group consisting of silica, alumina, titania, zinc oxide, fluoropolymers, silicones, carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, functionalized graphene, and combinations thereof.

[0059]

[0069] Clause 20. The coating system of any of clauses 16 to 19, wherein the nanomaterial is a surface modified with a hydrophobic material selected from the group consisting of alkylsilanes, alkyldisilazanes, fluoropolymers, and combinations thereof.

[0060]

[0070] Clause 21. The coating system of any of clauses 16 to 20, wherein the nanomaterial is selected from the group consisting of nanoparticles, nanorods, nanofibers, nanosheets, and combinations thereof.

[0061]

[0071] Clause 22. The coating system of any of clauses 1 to 21, wherein the conductive layer comprises a heat stabilizer.

[0062]

[0072] Clause 23. The coating system of clause 22, wherein the heat stabilizer comprises zinc oxide.

[0063]

[0073] Clause 24. The coating system of clause 22, wherein the conductive layer has a thickness of about 15 μm to about 35 μm.

[0064]

[0074] Clause 25. The coating system of any of clauses 1 to 24, further comprising an insulating layer underlying the conductive layer.

[0065]

[0075] Clause 26. The coating system of any of clauses 1 to 25, wherein the anti-icing layer comprises a polymer selected from the group consisting of sol-gel, polysiloxane, polyester, fluoropolymer, polysiloxane, and combinations thereof.

[0066]

[0076] Clause 27. The coating system of any of clauses 1 to 26, wherein the anti-icing layer further comprises a low surface energy additive or a moisture absorbing additive.

[0067]

[0077] Clause 28. The coating system of any of clauses 1 to 27, wherein the anti-icing layer comprises polytetrafluoroethylene (PTFE) and / or a glycol-based component.

[0068]

[0078] Clause 29. A coating system comprising a conductive layer comprising a conductive material, the conductive layer having a sheet resistivity of about 100 Ω / □ to about 1000 Ω / □, and an anti-icing layer comprising a material having a contact angle greater than 90 degrees according to ASTM D7334, the anti-icing layer disposed over the conductive layer.

[0069]

[0079] Clause 30. A composite airfoil comprising: a root section including a first surface; a midsection including the first surface and connected at a first end to the root section; a tip section including the first surface and connected at the first end to a second end of the midsection; a coating system disposed on the first surface of the root section, the first surface of the midsection, the first surface of the tip section, or a combination thereof, wherein the coating system comprises a conductive layer comprising an electrically conductive material and an anti-icing layer disposed on the conductive layer.

[0070]

[0080] Clause 31. The composite airfoil of clause 30, wherein a coating system is disposed on the first surface of the root section, the conductive layer having a thickness of about 0.1 μm to about 100 μm, and the anti-icing layer having a thickness of about 500 μm to about 1000 μm.

[0071]

[0081] Clause 32. The composite airfoil of clause 30 or 31, wherein the anti-icing layer comprises nanorods.

[0072]

[0082] Clause 33. The composite airfoil of any of clauses 30 to 32, wherein the anti-icing layer comprises nanorods in an amount of about 0.5 wt% to about 10 wt%, based on the weight of the anti-icing layer.

[0073]

[0083] Clause 34. The composite airfoil of any of clauses 30 to 33, wherein the conductive layer comprises the conductive material in an amount of about 10 wt% to about 25 wt%, based on the weight of the conductive layer.

[0074]

[0084] In this disclosure, reference is made to various embodiments. However, it should be understood that the disclosure is not limited to the specifically described embodiments. Instead, any combination of the following features and elements, whether related to various embodiments or not, is contemplated for implementing and practicing the teachings provided herein. In addition, when elements of an embodiment are described in the format "at least one of A and B," embodiments including exclusively element A, embodiments including exclusively element B, and embodiments including elements A and B are respectively contemplated. Furthermore, while some embodiments may realize other possible solutions and / or advantages over the prior art, whether or not a particular advantage is achieved by a given embodiment does not limit the scope of the disclosure. Accordingly, the embodiments, features, and advantages disclosed in the specification are merely exemplary and are not considered elements or limitations of the claims unless expressly recited in the claims.

[0075]

[0085] Aspects of the present disclosure are described herein with reference to flow diagrams and / or block diagrams of methods, apparatus (systems), and computer program products according to aspects of the present disclosure. It will be understood that each block of the flow diagrams and / or block diagrams, and combinations of blocks in the flow diagrams and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus to produce a machine, whereby the instructions, when executed by the processor of the computer or other programmable data processing apparatus, create means for implementing the function(s) / act(s) identified in one or more blocks of the flow diagrams and / or block diagrams.

[0076]

[0086] These computer program instructions may also be stored on a computer-readable medium that can instruct a computer, other programmable data processing apparatus, or other device to function in a particular manner, such that the instructions stored on the computer-readable medium produce an article of manufacture that includes instructions that implement the functions / acts identified in one or more blocks of the flow diagrams and / or block diagrams.

[0077]

[0087] Furthermore, computer program instructions can be loaded into a computer, other programmable data processing apparatus, or other device to generate a computer-implemented process into a series of operational steps performed on the computer, other programmable data processing apparatus, or other device, whereby the instructions executing on the computer, other programmable data processing apparatus, or other device provide a process for implementing the functions / acts identified in one or more blocks of the flow diagrams and / or block diagrams.

[0078]

[0088] The flow diagrams and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various aspects of the present disclosure. In this regard, each block in the flow diagrams or block diagrams may represent a module, segment, or portion of code, including one or more executable instructions for implementing one or more logical functions. It should also be noted that in some alternative implementations, the functions shown in the blocks need not occur in the order described in the accompanying drawings. For example, two blocks shown in succession may, in fact, be executed substantially simultaneously, or the blocks may be executed in the reverse order or out of order, depending on the functionality involved. It should also be noted that each block of the block diagrams and / or flow diagrams, and combinations of blocks in the block diagrams and / or flow diagrams, may be implemented by special-purpose hardware-based systems that perform particular functions or functions, or by a combination of special-purpose hardware and computer instructions.

[0079]

[0089] While the forgoing is directed to aspects of the present disclosure, other and further aspects of the disclosure may be devised without departing from the basic scope thereof, which scope is determined by the following claims.

Claims

1. A method (300) of coating a substrate (204), comprising: depositing (302) a conductive layer (206) containing a conductive material on the substrate, wherein the conductive layer (206) has a resistivity of from about 10 Ω / sq to about 1000 Ω / sq; and depositing (304) an anti-freezing layer (208) containing a nanomaterial on the conductive layer (206) to form a coating system (150). A method comprising the above.

2. The method according to claim 1, further comprising at least partially curing the conductive layer (206) before depositing the anti-freezing layer (208) on the conductive layer (206).

3. The method according to claim 2, wherein at least partially curing the conductive layer comprises at least partially curing the conductive layer at a temperature of from about 10 °C to about 40 °C, a pressure of from about 500 Torr to about 760 Torr, and a relative humidity of less than about 50%.

4. The method according to claim 1, wherein the conductive material is selected from the group consisting of polyaniline, poly(ethylenedioxythiophene), poly(styrenesulfonate), and mixtures thereof.

5. The method according to claim 1, further comprising combining the conductive material with an adhesive material selected from the group consisting of polyurethane, polyvinyl butyral, polyacrylate, epoxy, glycidyl-Si-Zr-containing sol-gel, polyester, phenoxy resin, polysulfide, and mixtures thereof.

6. The method according to claim 1, wherein the anti-freezing layer comprises a polymer selected from the group consisting of polyurethane, polyvinyl butyral, polyacrylate, epoxy, glycidyl-Si-Zr-containing sol-gel, polyester, phenoxy resin, polysulfide, and mixtures thereof.

7. The method according to claim 1, wherein coating the substrate comprises coating one or more electrodes (152) disposed on the substrate.

8. The method according to claim 1, wherein the anti-freezing layer is deposited by flow coating, drop casting, dip coating, spray coating, brush coating, spin coating, roll coating, in-mold coating, co-curing, or electrocoating.

9. The method according to claim 1, further comprising curing the anti-freezing layer at a temperature of about 10°C to about 40°C, a pressure of about 66661 Pa (500 Torr) to about 101324 Pa (760 Torr), and a relative humidity of less than about 50%.

10. The method according to claim 1, further comprising dissolving a conductive material in a solvent selected from the group consisting of xylene, benzene, toluene, dimethyl sulfoxide, water, and mixtures thereof.

11. A conductive layer (206) comprising a conductive material, the conductive layer having a resistivity of about 100 Ω / sq to about 1000 Ω / sq; and An anti-freezing layer (208) comprising a nano material, the anti-freezing layer disposed on the conductive layer A coating system (150) comprising.

12. The coating system according to claim 11, wherein the conductive material is selected from the group consisting of polyaniline, poly(ethylenedioxythiophene), poly(styrenesulfonate), and mixtures thereof.

13. The coating system according to claim 11, wherein the conductive layer comprises an adhesive material selected from the group consisting of polyurethane, polyvinyl butyral, polyacrylate, epoxy, glycidyl-Si-Zr-containing sol-gel, polyester, phenoxy resin, polysulfide, and mixtures thereof.

14. The coating system according to claim 11, wherein the nano material is selected from the group consisting of silica, alumina, titania, zinc oxide, fluoropolymer, silicone, carbon nanotube, graphene, graphene oxide, reduced graphene oxide, functionalized graphene, and combinations thereof.

15. A root section (102) including a first surface; An intermediate section (104) including a first surface and connected to the root section at a first end; A tip section (106) including a first surface and connected to a second end of the intermediate section at a first end; A coating system (150) disposed on the first surface of the root section, the first surface of the intermediate section, the first surface of the tip section, or a combination thereof, comprising: A conductive layer (206) comprising a conductive material; and An anti-freezing layer (208) disposed on the conductive layer A coating system comprising A composite airfoil comprising.

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