Method for producing an anti-fouling and anti-wear coating on the inner surface of a tubular member

Abstract

A method of coating an inner surface of a tubular member, the method comprising: forming a sublayer on the inner surface of the tubular member, the sublayer comprising a chromium sublayer, a polymeric sublayer containing electrically conductive or semiconductive particles, or a diamond-like carbon sublayer containing undoped diamond-like carbon material; disposing a hydrophobic layer on the sublayer via plasma-assisted chemical deposition to form a coating on the inner surface of the tubular member, the hydrophobic layer comprising doped diamond-like carbon material, and the doped diamond-like carbon material containing amorphous diamond-like carbon doped with at least one of Si and optionally F, Co, Cr, W, or Ti.

Description

Cross-references to related applications

[0001] This application claims the benefit of U.S. Application No. 18 / 436735, filed on February 8, 2024, the entire contents of which are incorporated herein by reference. Background Technology

[0002] Many industrial products are exposed to harsh environments. For example, tools used in wellbore or other downhole environments in the oil and gas industry are often exposed to corrosive or supersaturated fluids, which can cause scale, composed of inorganic or organic compounds such as CaCO3, BaSO4, CaSO4, SrSO4, asphaltenes, etc., to accumulate on the product's surface. Such deposits can occur in pipes, separators, and other equipment. Once deposited, scale can interfere with the normal function of the product and cause disruptions to the systems and / or processes using the product, potentially requiring repair or replacement. Therefore, there is a constant search for methods to prevent scale-related contamination or extend equipment uptime by minimizing scale formation. Summary of the Invention

[0003] A method for coating the inner surface of a tubular member includes: forming a sublayer on the inner surface of the tubular member, the sublayer comprising a chromium sublayer, a polymer sublayer containing conductive or semi-conductive particles, or a diamond-like carbon sublayer containing undoped diamond-like carbon material; and depositing a hydrophobic layer on the sublayer via plasma-assisted chemical deposition to form a coating on the inner surface of the tubular member, the hydrophobic layer comprising doped diamond-like carbon material, wherein the doped diamond-like carbon material contains amorphous diamond-like carbon doped with Si and optionally at least one of F, Co, Cr, W, or Ti. A coating formed by such a method is also disclosed.

[0004] The above and other features are illustrated by the following figures, detailed embodiments, and examples. Attached Figure Description

[0005] Referring now to the accompanying drawings, which are exemplary and not limiting, and in which the same elements are numbered the same:

[0006] Figure 1 It is a cross-sectional view of the coated inner surface of a tubular component according to the prior art;

[0007] Figure 2 It is a scanning electron microscope (SEM) image showing the textured surface of a dense chromium sublayer;

[0008] Figure 3 This is a schematic cross-sectional view of the coated inner surface of a tubular member according to an embodiment of the present disclosure;

[0009] Figure 4This is a schematic cross-sectional view of the coated inner surface of a tubular member according to another embodiment of this disclosure;

[0010] Figure 5 The image shows an SEM image of a coating that includes a hydrophobic layer and a dense chromium sublayer disposed on the inner surface of a tubular member.

[0011] Figure 6A The contact angle (in degrees) of a diamond-like carbon (DLC) coating without any sublayers is shown. Figure 6B The contact angle (in degrees) of the coating, including the DLC layer disposed on a dense chromium sublayer, is shown, and Figure 6C The contact angle (in degrees) of the coating, including the DLC layer disposed on the polymer sublayer, is shown.

[0012] Figure 7A and Figure 7B Indentation test results are illustrated for DLC coatings without any secondary layer and DLC coatings with a secondary layer disposed on the inner surface of a tubular member, demonstrating the improved adhesion of coatings including both the DLC layer and the secondary layer; and

[0013] Figure 8 This is a graph showing the weight (g) of scale deposits on doped DLC, undoped DLC, and bare metal. Detailed Implementation

[0014] DLC coatings impart hydrophobicity to surfaces, and these hydrophobic surfaces remain easy to clean. DLC coatings can be formed via plasma-enhanced chemical vapor deposition. However, when the inner surface of a tubular component is exposed to plasma for an extended period and the DLC coating accumulates, the deposited coating may begin to discharge due to the combination of the hollow cathode effect and decreased surface conductivity. This can lead to defects and discontinuities in the coating.

[0015] Furthermore, from a mechanical perspective, such as wear resistance and corrosion resistance, thick coatings (e.g., exceeding 0.5 micrometers) are ideal. However, when the DLC coating is too thick, internal stress may accumulate at the interface between the coating and the substrate. Figure 1 As shown, when a relatively thick hydrophobic DLC coating (50) (e.g., a hydrophobic DLC coating with a thickness greater than 0.5 micrometers) is applied to the inner surface of a tubular member (30), the coating may delaminate (60) and / or develop cracks (20) when a load (A) is applied to the coating (50).

[0016] The inventors have discovered a novel and cost-effective method for coating the inner surface of tubular components. The coating produced by this method is hydrophobic, scale-resistant, abrasion-resistant, and corrosion-resistant. As used herein, a hydrophobic coating or layer refers to a coating or layer with a water contact angle greater than 90°.

[0017] The method includes depositing a secondary layer on the inner surface of a tubular member and depositing a hydrophobic layer on the secondary layer. The secondary layer may include a chromium secondary layer or a polymer secondary layer, the polymer secondary layer comprising a polymer and conductive or semiconductive particles. The secondary layer may also be a DLC secondary layer, with a composition different from the DLC in the hydrophobic layer. The hydrophobic layer comprises doped DLC material. Doping elements imparting hydrophobicity may include Si and F. Other elements such as Co, Cr, W, and Ti may also be added to increase hydrophobicity and / or reduce internal stress.

[0018] A chromium sublayer can be deposited on the inner surface of a tubular component via an electrochemical process. Preferably, the sublayer is deposited using a thin, dense chromium plating (TDC) process, which is applied at a much slower rate compared to conventional hard chromium plating. The electrophoretic coating process allows the chromium element in the chromium electrolyte solution to penetrate the surface contours of the substrate, resulting in a strong adhesion and a crack-free, continuous, and dense sublayer. In standard ASTM bending tests, the chromium sublayer does not crumble, peel, crack, detach, or separate from the substrate. The TDC sublayer also exhibits a micro-nodular surface finish.

[0019] Prior to any electrochemical deposition, the inner surfaces of tubular components can be pretreated to remove contaminants such as grease, dirt, and debris. Surfactants, solvents, detergents, alkaline cleaners, two-phase cleaners, emulsion cleaners, or other suitable cleaners known in the art can be used. Steam degreasing, dry steam honing, electrolytic cleaning, ultrasonic cleaning, vibratory cleaning, water blasting, steam blasting, or glass bead blasting can also be used to clean the inner surfaces to be coated. The cleaned surfaces must be free of oil, grease, oxides, sulfides, scale, and dirt. Surface textures, such as nodular structures, can be created by removing surface materials during the pretreatment process.

[0020] The cleaned inner surface can then be exposed to a chromium electrolyte solution containing chromic acid, which is formed when chromium trioxide (CrO3) dissolves in water. The electrolyte solution may also include a catalyst, such as sulfuric acid. During electrochemical deposition, hexavalent chromium is reduced to chromium metal due to the catalytic action of sulfate ions. Optionally, fluorides and / or fluorosilicates may also be used as catalysts in the electrolyte solution. More than one catalyst may be used. Known additives may also be included in the electrolyte solution.

[0021] During the electrochemical deposition process, the chromium electrolyte solution can be at a temperature below 65°C, for example, from room temperature to 65°C. During the chromium sublayer formation process, the temperature of the electrolyte solution is maintained within the target temperature range.

[0022] Exposing the inner surface of a tubular member may include filling the tubular member with a chromium electrolyte solution or immersing the tubular member in a container holding the chromium electrolyte solution. If necessary, surfaces not intended to be coated with any chromium may be masked before the tubular member is exposed to the chromium electrolyte solution.

[0023] Once the inner surface of the tubular component reaches the temperature of the chromium electrolyte solution, an electric current is applied to the chromium electrolyte solution for a period of time until the dense chromium layer reaches the target thickness.

[0024] Compared to sublayers formed by conventional hard chromium plating, sublayers deposited via the TDC process exhibit greater density and hardness. Compared to the 80% to 90% chromium content achieved with conventional hard chromium plating, TDC chromium sublayers can achieve near-complete density using greater than 98% or 99% wt% chromium metal. The chromium sublayer is dense and can have a porosity of less than 5%, less than about 1%, or less than 0.1%. Preferably, the chromium sublayer is free of pores and / or cracks. Crack-free sublayers provide long-term corrosion protection.

[0025] The chromium sublayer can have a surface with microstructures, such as... Figure 2 The nodules are shown. The chromium sublayer can promote bonding between the sublayer and the hydrophobic layer, for example, by forming a compositionally gradient transition chromium carbide layer between the sublayer and the hydrophobic layer, thereby reducing the residual stress of the hydrophobic layer. In addition, the surface texture of the chromium sublayer can also improve the hydrophobicity of the coating.

[0026] The chromium sublayer can also have outstanding adhesive properties to the inner surface of the tubular member. For example, the chromium sublayer can form a permanent bond to the inner surface of the tubular member by penetrating the surface pores of the inner surface.

[0027] The thickness of the chromium sublayer can be from about 1.2 μm to about 10 μm, preferably from about 1.2 μm to about 5 μm, and more preferably from about 1.2 μm to about 3.8 μm.

[0028] When the sublayer is a polymer layer, the method includes forming the polymer sublayer by dip coating, air spraying, airless spraying, melt bonding, brushing or roller coating, or other coating techniques. Surface preparation may include a sandblasting process to form a nodular pattern, thereby increasing anchoring strength and water contact angle. The coating is preferably applied using a compressed air or airless spraying system. In air spraying methods, high-pressure air or compressed air generated by a compressor atomizes the fluid to be sprayed and delivers it to the inner surface of the tubular component. In airless spraying coatings, the coating composition is atomized or broken into small droplets without the use of compressed air. Instead, the coating composition is pumped under high pressure through the nozzle tip and then separated into very small droplets forming a spray pattern. Dipping can be used for small parts. After the coating dries, it may be further cured at elevated temperatures between about 200℉ and about 400℉. The coating composition used may include polymers and conductive or semi-conductive particles. Optionally, the coating composition may also include an organic solvent.

[0029] The polymer may include at least one of epoxy resins, phenolic resins, or epoxy-phenolic resins. As used herein, epoxy resin refers to a cured product of an epoxide containing one or more epoxy groups. Epoxy resins may be formed from at least one of aliphatic epoxides (such as butanediol diglycidyl ether), bisphenol epoxides (such as bisphenol A diglycidyl ether (CAS#1675-54-3) and / or bisphenol F diglycidyl ether), or thermoplastic phenolic resin epoxides (such as phenol-formaldehyde polymeric glycidyl ether (CAS#28064-14-4)). The curing agent includes an active group capable of reacting with the epoxy groups. Examples of such active groups include amino and anhydride groups. In one aspect, the curing agent is at least one of an aliphatic amine or an aromatic amine.

[0030] Phenolic resins, also known as phenol-formaldehyde resins, are synthetic resins produced by the polymerization of phenol (C6H5OH), alkyl-substituted phenols, halogen-substituted phenols, or combinations thereof with formaldehyde compounds such as formaldehyde (CH2C=O) . Phenolic resins may include repeating units such as -[(C6H3OH)-CH2]-.

[0031] Epoxy phenolic resins are phenolic resins modified at the phenolic hydroxyl groups to include epoxy functional groups such as –CH2-(C2H3O), where –(C2H3O) is a three-membered epoxy ring. The added functionality of phenolic resins increases their crosslinking ability, thereby forming stronger polymers with higher resistivity.

[0032] As used herein, conductive and semiconducting particles refer to particles with a conductivity of 1-1000 Siemens per centimeter (S / cm). Specific conductive or semiconducting particles may include graphite particles, metal sulfides (such as molybdenum sulfide, tungsten sulfide, titanium sulfide, copper sulfide, zinc sulfide, etc.), or combinations thereof. The number-average particle size may be from about 0.1 μm to about 500 μm, preferably from about 0.5 μm to about 100 μm, and more preferably from about 0.5 μm to about 10 μm.

[0033] The organic solvent in the coating composition may include at least one of alcohols, amines, amides, ethers, esters, ketones, acetonitrile, dimethyl sulfoxide, or aromatic solvents (such as toluene and xylene). The solvent may be removed after the coating composition has been deposited on the inner surface of the tubular member.

[0034] Based on the total volume of the coating composition, the solvent concentration may be from 25 volume percent to about 80 volume percent or from about 33 volume percent to about 67 volume percent. Based on the total weight of the coating composition, the concentration of conductive or semi-conductive particles may be from about 2 weight percent to about 80 weight percent or from about 30 weight percent to about 70 weight percent. In one aspect, the formed polymer sublayer comprises, based on the total weight of the polymer sublayer, about 10 weight percent to about 80 weight percent, about 30 weight percent to about 70 weight percent, or about 40 weight percent to about 60 weight percent of conductive or semi-conductive particles, and about 20 weight percent to about 90 weight percent, about 30 weight percent to about 70 weight percent, or about 40 weight percent to about 60 weight percent of a polymer, the polymer comprising at least one of epoxy resin, phenolic resin, or epoxy-phenolic resin.

[0035] The thickness of the polymer sublayer can be from about 1 μm to about 50 μm, preferably from about 5 μm to about 25 μm, and more preferably from about 5 μm to about 10 μm.

[0036] The DLC sublayer can be formed via a plasma-assisted chemical vapor deposition (CVD) process as described herein in the context of forming a hydrophobic layer. The DLC sublayer may comprise undoped DLC material. The DLC sublayer may be formed from a precursor composition comprising or consisting of methane (CH4) and / or acetylene (C2H2) gas, without any doped precursors. The thickness of the DLC sublayer can be from about 0.1 μm to about 1 μm, preferably from about 0.25 μm to about 0.75 μm.

[0037] The hydrophobic layer can be deposited on a chromium, polymer, or DLC sublayer via plasma-assisted chemical vapor deposition. The precursor composition for the hydrophobic layer may include (1) a silicon-doped precursor and (2) methane (CH4) and / or acetylene (C2H2) gas. The silicon-doped precursor may include at least one of tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), hexamethyldisiloxane (HMDSO), or hexamethyldisilazane (HMDS). HMDSO is a liquid at room temperature and has a boiling point of 100.5 °C at 1 atm and a vapor pressure of about 4400 Pa at 20 °C. HMDSO is a preferred silicon-doped precursor because it evaporates under the coating operation pressure. The precursor composition may be used alone or optionally in the formation of a plasma with the assistance of a carrier gas such as argon, nitrogen, or a combination thereof. To add fluorine dopant, the precursor composition may also include at least one of tetrafluoromethane or difluoroacetylene. To add other doping elements such as Co, Cr, W, and Ti, the precursor composition may also include carbonyl metals W(CO)6, Mo(CO)6, Cr(CO)6, Co2(CO)8, (C5H5)2Ti(CO)2, metal halides WF6, CrF5, or combinations thereof. If used, the volume ratio of the precursor composition to the carrier gas is about 20:1 to about 1:20 or about 10:1 to about 1:10.

[0038] Prior to deposition, a vacuum can be created within the internal volume of the tubular member defined by its inner surface, reaching a pressure of 0.01 Pa to approximately 10 Pa or approximately 0.1 Pa to approximately 5 Pa. To create the vacuum, the tubular member can be placed in a vacuum chamber. If the tubular member cannot be fitted into the vacuum chamber, a pump connected to the tubular member can be used to create the vacuum, for example, connected to one or both ends of the tubular member. More than one type of pump can be used.

[0039] The precursor composition and optional carrier gas can then be supplied into the internal volume of the tubular member. A manifold disposed longitudinally within the internal volume of the tubular member can be used to introduce the precursor composition and optional carrier gas into the internal volume of the tubular member. The manifold can be perforated to provide a uniform distribution of gas flow on a sublayer coated on the inner surface of the tubular member. The manifold can also be used as an electrode at ground potential. The flow rate of CH4 and / or C2H2 gas can be about 0.1 cm. 3 / min to approximately 1000cm 3 / min, preferably about 1cm 3 / min to approximately 500cm 3 / min. The flow rate range for doped precursors (such as HMDSO) can be approximately 0.1 cm⁻¹. 3 / min to approximately 500cm 3 / min, preferably about 0.5cm 3 / min to approximately 300cm3 / min. A heater or evaporator can be added to control the gas flow rate, especially for precursors with high boiling points or low evaporation pressures at room temperature.

[0040] The hydrophobic layer is deposited at a temperature of about room temperature to about 200°C, preferably about room temperature to about 100°C, and more preferably about room temperature to about 50°C.

[0041] The plasma supplies the energy to initiate the decomposition of the precursor composition. To initiate the deposition of the hydrophobic layer on the sublayer, plasma is formed within the internal volume of the tubular member by the precursor composition and an optional carrier gas. The plasma pressure is from about 0.1 Pa to about 100 Pa or from about 0.1 Pa to about 10 Pa. A pump can be used to maintain the pressure during deposition. In one aspect, plasma is generated by electrically exciting the tubular member by negatively biasing it with a pulse voltage in the range of about -0.1 kV to about -10 kV, preferably about -0.3 kV to about -8 kV, a pulse frequency relative to ground of less than 20,000 Hz, preferably about 500 Hz to about 5000 Hz, and a pulse width in the range of about 0.01 microseconds (ms) to about 50 ms. The pulse voltage can be provided by a pulsed DC power supply electrically connected to the tubular member.

[0042] The deposition time can range from about 5 minutes to about 240 minutes, preferably from about 10 minutes to about 120 minutes, or from about 15 minutes to about 60 minutes.

[0043] The formed hydrophobic layer may comprise a doped DLC material, for example, an amorphous DLC doped with Si and optionally at least one of F, Co, Cr, W, or Ti. Preferably, the doped DLC material in the hydrophobic layer is doped with about 20 atomic percent to about 35 atomic percent or about 30 atomic percent Si. The amount of dopant can be controlled by the volume ratio of CH4 / HMDSO or C2H2 / HMDSO. The volume ratio is between 0 and 30, or greater than 0 to 30. Optionally, the doped DLC material in the hydrophobic layer also includes about 15 atomic percent to about 25 atomic percent hydrogen atoms.

[0044] The doped DLC material in the hydrophobic layer may comprise about 50 atomic percent to about 90 atomic percent or about 60 atomic percent to about 70 atomic percent sp 2 Bonded carbon and about 10 atomic percent to about 50 atomic percent or about 30 atomic percent to about 40 atomic percent sp 3 Bonded carbon. As used in this article, "sp" 2 "Bound carbon" refers to carbon atoms bonded to adjacent carbon atoms in a crystal structure that essentially corresponds to the carbon isotopes of graphite. 3"Bound carbon" refers to carbon atoms bonded to adjacent carbon atoms in a crystal structure that is essentially the same as the diamond isotope of carbon.

[0045] sp 2 and sp 3 Bonded carbon can be uniformly distributed within the hydrophobic layer or exist in a gradient. For example, in the direction from the sublayer to the outer surface of the hydrophobic layer, sp... 2 and sp 3 The relative atomic ratio of bonded carbons can be reduced. 2 and sp 3 The relative atomic ratio of bonded carbons can be controlled by changing the bias voltage, the precursor gas, or a combination thereof. For example, adding nitrogen to the precursor gas promotes the formation of NH, C=N, and C≡N bonds, which in turn reduces the fraction of sp3 carbon bonds and / or hinders carbon-carbon crosslinking. In one aspect, the method also includes controlling or reducing the amount of nitrogen in the precursor composition, so that the sp3 carbons in the hydrophobic layer... 2 and sp 3 The relative atomic ratio of bonded carbon decreases in the direction from the sublayer to the outer surface of the hydrophobic layer.

[0046] Optionally, the method further includes forming an intermediate layer between the secondary layer and the hydrophobic layer. The intermediate layer may comprise an undoped DLC material or a second DLC material doped with less silicon than the doped DLC material in the hydrophobic layer. The intermediate layer is formed without using HMDSO in the precursor gas or by reducing the concentration of HMDSO to less than 50% or less than 25% compared to the HMDSO used to form the hydrophobic layer. The thickness of the intermediate layer may be from about 0.1 μm to about 1 μm, preferably from about 0.25 μm to about 0.75 μm.

[0047] The method disclosed herein can produce a tubular member having an inner surface coated with a multilayer coating, the multilayer coating having a sublayer disposed on the inner surface and a hydrophobic layer disposed on the sublayer. For example... Figures 3 to 5 As shown, the tubular member (100, 200) has a substrate (160) having an inner surface and a coating disposed on the inner surface, wherein the coating includes a chromium, polymer, or DLC sublayer (150) disposed on the inner surface of the tubular member and a hydrophobic layer (110) disposed on the sublayer (150). The coating may also include an intermediate layer (120) between the hydrophobic layer (110) and the sublayer (150). The intermediate layer (120) may include a second DLC material different from the doped DLC material in the hydrophobic layer (110).

[0048] The material used to form the inner surface of the tubular member is not particularly limited and may include metals such as iron, chromium, nickel, titanium, cobalt, or alloys thereof, or combinations thereof. In one embodiment, the substrate comprises steel and a nickel-based alloy. The inner surface may have an undulating shape. The length-to-diameter ratio (length / inner diameter) of the tubular member may be greater than 1.

[0049] The coating thickness can be from about 2 micrometers to about 5 micrometers. Preferably, the coating thickness is from about 3 micrometers to about 5 micrometers.

[0050] Compared to DLC coatings without any sublayers, multilayer coatings with chromium, polymer, or DLC sublayers can have improved properties, such as improved hydrophobicity or anti-fouling properties, improved abrasion resistance or wear resistance, and / or enhanced corrosion resistance or erosion resistance.

[0051] Figures 6A to 6C The contact angles (in degrees) of DLC coatings without any sublayers, coatings including DLC ​​layers disposed on dense chromium sublayers, and coatings including DLC ​​layers disposed on polymer sublayers were compared. The results show that the hydrophobicity of the coating can be significantly increased when the coating has a sublayer as disclosed herein. For example, as determined by comparing the contact angle of water with a coating on a surface without any sublayers and the contact angle of water with the same DLC on a surface with sublayers, the sublayer can increase the hydrophobicity of the coating by more than 30%, more than 40%, or even more than 50%.

[0052] Another advantageous feature is that coatings with sublayers exhibit excellent bond strength. For example... Figure 7A and Figure 7B As shown, when indentation testing is performed according to ASTM E18, the coating having the sublayer disclosed herein has improved bond strength to the inner surface of the tubular member, as determined by VDI 3198.

[0053] When the hydrophobic layer comprises a doped DLC material as disclosed herein, the coating may also exhibit improved anti-fouling properties compared to a coating with undoped DLC or bare metal without any coating, such as... Figure 8 As shown.

[0054] Various implementation schemes of this disclosure are described.

[0055] Aspect 1. A method for coating the inner surface of a tubular member, the method comprising: forming a sublayer on the inner surface of the tubular member, the sublayer comprising a chromium sublayer, a polymer sublayer having conductive or semi-conductive particles, or a DLC sublayer having an undoped DLC material; and depositing a hydrophobic layer on the sublayer via plasma-assisted chemical deposition to form a coating on the inner surface of the tubular member, the hydrophobic layer comprising a doped DLC material, and the doped DLC material comprising amorphous DLC doped with Si and optionally at least one of F, Co, Cr, W or Ti.

[0056] Aspect 2. The method according to any of the preceding aspects, wherein the thickness of the coating is from about 1 micrometer to about 5 micrometers.

[0057] Aspect 3. The method according to any prior aspect, the method further comprising forming the chromium sublayer by electrochemical deposition.

[0058] Aspect 4. The method according to any prior aspect, wherein the electrochemical deposition comprises exposing the inner surface of the tubular member to a chromium electrolyte solution comprising chromic acid and a catalyst at a temperature of about room temperature to about 65°C.

[0059] Aspect 5. The method according to any of the preceding aspects, wherein the thickness of the chromium sublayer is from about 2.5 micrometers to about 7.5 micrometers.

[0060] Aspect 6. The method according to any of the preceding aspects, wherein the porosity of the chromium sublayer is less than 1%.

[0061] Aspect 7. The method according to any previous aspect, wherein the chromium sublayer has a textured surface including nodules.

[0062] Aspect 8. The method according to any prior aspect, the method further comprising forming the polymer sublayer by dip coating, air spraying or airless spraying.

[0063] Aspect 9. The method according to any of the preceding aspects, wherein the thickness of the polymer sublayer is from about 2.5 micrometers to about 12.5 micrometers.

[0064] Aspect 10. The method according to any prior aspect, wherein the polymer sublayer comprises at least one of epoxy resin, phenolic resin, or epoxy-phenolic resin.

[0065] Aspect 11. The method according to any prior aspect, wherein the conductive or semiconducting particles comprise at least one of graphite particles or metal sulfide particles.

[0066] Aspect 12. The method according to any preceding aspect, wherein the conductive or semiconductive particles in the polymer sublayer are present in an amount of about 10% to about 80% by weight based on the total weight of the polymer sublayer.

[0067] Aspect 13. The method according to any prior aspect, further comprising forming the DLC sublayer using a precursor composition via a plasma-assisted chemical deposition process, the precursor composition comprising or consisting of at least one of methane or acetylene, without doped precursors.

[0068] Aspect 14. The method according to any prior aspect, wherein the hydrophobic layer is formed from a precursor composition comprising a silicon-doped precursor and at least one of methane or acetylene.

[0069] Aspect 15. The method according to any prior aspect, wherein the precursor composition further comprises nitrogen, and the method further comprises controlling or reducing the amount of nitrogen in the precursor composition such that the hydrophobic layer contains sp... 2 and sp 3 The relative atomic ratio of bonded carbon decreases in the direction from the sublayer to the outer surface of the hydrophobic layer.

[0070] Aspect 16. The method according to any prior aspect, the method further comprising forming an intermediate layer between the hydrophobic layer and the sublayer, and the intermediate layer comprising an intermediate DLC material different from the doped DLC material in the hydrophobic layer.

[0071] Aspect 17. The method according to any previous aspect, wherein the intermediate layer is formed by adjusting the amount of silicon-doped precursor to less than 50% of the silicon-doped precursor used to form the hydrophobic coating.

[0072] Aspect 18. The method according to any of the preceding aspects, wherein the length-to-diameter ratio of the tubular member is greater than 1.

[0073] Aspect 19. A tubular member having a coated inner surface, the tubular member comprising: an inner surface; and a coating disposed on the inner surface, the coating comprising a sublayer disposed on the inner surface of the tubular member, the sublayer comprising a chromium sublayer, a polymer sublayer having conductive or semi-conductive particles, or a DLC sublayer having an undoped DLC material; and a hydrophobic layer disposed on the sublayer, the hydrophobic layer comprising a doped DLC material, the doped DLC material being an amorphous DLC doped with about 20 atomic percent to about 35 atomic percent of silicon, wherein the thickness of the coating is about 1 micrometer to about 5 micrometers.

[0074] Aspect 20. The tubular member according to any of the preceding aspects, wherein the secondary layer is a chromium secondary layer and the porosity of the chromium secondary layer is less than 1%.

[0075] Aspect 21. The tubular member according to any preceding aspect, wherein the secondary layer is a polymer layer comprising at least one of epoxy resin, phenolic resin, or epoxy-phenolic resin, and the conductive or semi-conductive particles comprising at least one of graphite particles, alumina particles, or silicon carbide particles.

[0076] Aspect 22. The tubular member according to any of the preceding aspects, wherein the coating further comprises an intermediate layer disposed between the hydrophobic layer and the sublayer, and the intermediate layer comprises an intermediate DLC material having less silicon than the doped DLC material in the hydrophobic layer.

[0077] All scopes disclosed herein include endpoints, and endpoints can be combined independently of each other. As used herein, "combination" includes blends, mixtures, alloys, and reaction products, etc. All references are incorporated herein by reference.

[0078] In the context of describing the invention (particularly in the context of the appended claims), the terms “a” and “the”, and similar designations, should be interpreted to cover both singular and plural unless otherwise specified herein or clearly contradicted by the context. The modifier “about” used in conjunction with quantity includes the stated value and has a meaning determined by the context (e.g., it includes the degree of error associated with a particular number of measurements). In one embodiment, the term “about” means that the value associated with about can vary by 10%. As used herein, size means the maximum dimension. Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0079] All references cited herein are incorporated herein by reference in their entirety. Although typical implementations have been described for illustrative purposes, the foregoing description should not be considered as limiting the scope of this document. Therefore, various modifications, adaptations, and substitutions will arise for those skilled in the art without departing from the spirit and scope of this document.

Claims

1. A method for coating the inner surface of a tubular member (100, 200), the method being characterized in that: A sublayer (150) is formed on the inner surface of the tubular member (100, 200), the sublayer (150) comprising a chromium sublayer, a polymer sublayer having conductive or semi-conductive particles, or a diamond-like carbon sublayer having undoped diamond-like carbon material. A hydrophobic layer (110) is deposited on the sublayer (150) via plasma-assisted chemical deposition, thereby forming a coating on the inner surface of the tubular member. The hydrophobic layer comprises a doped diamond-like carbon material, and the doped diamond-like carbon material comprises amorphous diamond-like carbon doped with Si and optionally at least one of F, Co, Cr, W or Ti.

2. The method of claim 1, wherein the thickness of the coating is from about 1 micrometer to about 5 micrometers.

3. The method of claim 1, further comprising forming the chromium sublayer by electrochemical deposition; and the electrochemical deposition comprising exposing the inner surface of the tubular member to a chromium electrolyte solution comprising chromic acid and a catalyst at a temperature of about room temperature to about 65°C.

4. The method of claim 3, wherein the chromium sublayer has a thickness of about 2.5 micrometers to about 7.5 micrometers; a porosity of less than 1%; a textured surface including nodules; or a combination thereof.

5. The method according to claim 1, characterized in that, The polymer sublayer is formed by dip coating, air spraying or airless spraying; and the thickness of the polymer sublayer is from about 2.5 micrometers to about 12.5 micrometers.

6. The method of claim 1, wherein the polymer sublayer comprises at least one of epoxy resin, phenolic resin, or epoxy-phenolic resin; the conductive or semi-conductive particles comprise at least one of graphite particles or metal sulfide particles; and the conductive or semi-conductive particles in the polymer sublayer are present in an amount of about 10% to about 80% by weight based on the total weight of the polymer sublayer.

7. The method according to claim 1, characterized in that, The diamond-like carbon sublayer is formed using a precursor composition via a plasma-assisted chemical deposition process, the precursor composition comprising at least one of methane or acetylene, without any doped precursor.

8. The method according to any one of claims 1 to 7, wherein the hydrophobic layer (110) is formed from a precursor composition comprising a silicon-doped precursor and at least one of methane or acetylene.

9. The method of claim 8, wherein the precursor composition further comprises nitrogen, and the method further comprises reducing the amount of nitrogen in the precursor composition such that the hydrophobic layer contains sp... 2 and sp 3 The relative atomic ratio of bonded carbon decreases in the direction from the sublayer to the outer surface of the hydrophobic layer.

10. The method according to any one of claims 1 to 7, characterized in that, An intermediate layer (120) is formed between the hydrophobic layer (110) and the sublayer (150), and the intermediate layer (120) comprises an intermediate diamond-like carbon material that is different from the doped diamond-like carbon material in the hydrophobic layer.

11. The method of claim 10, wherein the intermediate layer (120) is formed by adjusting the amount of silicon-doped precursor to less than 50% of the silicon-doped precursor used to form the hydrophobic coating.

12. A tubular member (100, 200) having a coated inner surface, said tubular member comprising: Inner surface; and A coating is provided on the inner surface. The coating is characterized in that A secondary layer (150) is disposed on the inner surface of the tubular member, the secondary layer comprising a chromium secondary layer, a polymer secondary layer having conductive or semi-conductive particles, or a diamond-like carbon secondary layer having undoped diamond-like carbon material; and A hydrophobic layer (110) is disposed on the sublayer (150), the hydrophobic layer (110) comprising a doped diamond-like carbon material, the doped diamond-like carbon material being an amorphous diamond-like carbon doped with about 20 atomic percent to about 35 atomic percent of silicon. The thickness of the coating is from about 1 micrometer to about 5 micrometers.

13. The tubular member of claim 12, wherein the secondary layer is a chromium secondary layer and the porosity of the chromium secondary layer is less than 1%.

14. The tubular member of claim 12, wherein the secondary layer is a polymer layer comprising at least one of epoxy resin, phenolic resin, or epoxy-phenolic resin, and the conductive or semi-conductive particles comprising at least one of graphite particles, alumina particles, or silicon carbide particles.

15. The tubular member according to any one of claims 12 to 14, wherein The coating further includes an intermediate layer (120) disposed between the hydrophobic layer (110) and the sublayer (150), and The intermediate layer (120) includes an intermediate diamond-like carbon material having less silicon than the doped diamond-like carbon material in the hydrophobic layer (110).

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