WO2026016265A1 - 一种疏水/富铬耐腐蚀复合涂层及其制备方法、应用 - Google Patents

一种疏水/富铬耐腐蚀复合涂层及其制备方法、应用

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Publication number
WO2026016265A1
WO2026016265A1 PCT/CN2024/114781 CN2024114781W WO2026016265A1 WO 2026016265 A1 WO2026016265 A1 WO 2026016265A1 CN 2024114781 W CN2024114781 W CN 2024114781W WO 2026016265 A1 WO2026016265 A1 WO 2026016265A1
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WIPO (PCT)
Prior art keywords
chromium
coating
corrosion
hydrophobic
rich
Prior art date
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Pending
Application number
PCT/CN2024/114781
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English (en)
French (fr)
Inventor
黄锦阳
赵文玮
胡新元
张醒兴
鲁金涛
袁勇
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Xian Thermal Power Research Institute Co Ltd
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Xian Thermal Power Research Institute Co Ltd
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Publication of WO2026016265A1 publication Critical patent/WO2026016265A1/zh
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
    • C23C10/02—Pretreatment of the material to be coated
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
    • C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
    • C23C10/30—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes using a layer of powder or paste on the surface
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
    • F22B37/025—Devices and methods for diminishing corrosion, e.g. by preventing cooling beneath the dew point
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H9/00—Details
    • F24H9/40—Arrangements for preventing corrosion

Definitions

  • This disclosure belongs to the field of material surface coating technology, specifically relating to a hydrophobic/chromium-rich corrosion-resistant composite coating and its preparation method and application.
  • Hot corrosion of the inner surface of boiler pipes has always been one of the factors restricting thermal power generation. Especially at present, thermal power generation is developing towards higher steam temperatures and pressures, so it is imperative to improve the thermal corrosion resistance of the inner surface of pipes.
  • Pipeline corrosion problems mainly consist of two parts: corrosion caused by gas and metal oxidation corrosion caused by water vapor. Applying a corrosion-resistant coating to the pipe surface can solve problems such as short pipe lifespan, the need for regular oxide removal, and prevent dangerous incidents like pipe bursts.
  • the most common anti-corrosion technology currently is the infiltration of corrosion-resistant metals onto alloy surfaces, such as Al, Si, and Cr. This involves forming a corrosion-resistant coating on the alloy surface through Cr infiltration.
  • There are many methods for preparing Cr-rich coatings typically including powder embedding, vapor deposition, and liquid phase methods.
  • the liquid phase method usually involves placing Cr powder in molten salt and holding it at high temperature to form a Cr-infiltrated layer.
  • the molten salt is prone to volatilization at high temperatures, causing damage to the workpiece and the environment.
  • the slurry method involves directly applying or spraying a slurry onto the workpiece surface and then sintering it at high temperatures to obtain a coating. This method produces coatings with excellent corrosion resistance and good adhesion. Compared to other Cr infiltration methods, this method is simple to operate and suitable for large-scale industrial production.
  • This disclosure aims to at least solve one of the technical problems existing in the prior art, and to provide a hydrophobic/chromium-rich corrosion-resistant composite coating, its preparation method, and its application.
  • One aspect of this disclosure provides a method for preparing a hydrophobic/chromium-rich corrosion-resistant composite coating, the method comprising:
  • a coating slurry is applied to the surface of a preheated workpiece, followed by drying, curing, and sintering to obtain a chromium-rich corrosion-resistant coating.
  • the coating slurry comprises a solid phase component and a liquid phase component.
  • the solid phase component includes chromium powder, nickel powder, iron powder, and rare earth compounds.
  • the liquid phase component includes Al( H2PO4 ) 3 , water glass, ammonium halide, polyvinyl alcohol, and Cr2O3 .
  • a layer of superhydrophobic material is sprayed onto the surface of the chromium-rich corrosion-resistant coating, and then cured to obtain a hydrophobic/chromium-rich corrosion-resistant composite coating.
  • the solid-liquid ratio of the solid phase component to the liquid phase component is 10:(1-5).
  • the chromium powder content is 40-80%;
  • the content of the nickel powder is 5-30%;
  • the content of the iron powder is 2-20%;
  • the content of the rare earth compound is 5-45%.
  • the content of Al(H2PO4)3 is 10-30 %;
  • the water glass content is 15-25%
  • the content of the ammonium halide is 5-10%;
  • the polyvinyl alcohol content is 10-35%
  • the Cr2O3 content is 10-30%.
  • the rare earth compound is a rare earth oxide or a rare earth chloride; and/or,
  • the ammonium halide is ammonium bromide or ammonium iodide.
  • a layer of superhydrophobic material is sprayed onto the surface of the chromium-rich corrosion-resistant coating, and then cured to obtain a hydrophobic/chromium-rich corrosion-resistant composite coating, comprising:
  • Anhydrous ethanol, HDTMS, and nano-alumina particles were mixed to form a suspension, which was then stirred.
  • Superhydrophobic Al2O3 nanoparticles modified with HDTMS were obtained by mixing, centrifugation, and drying.
  • An epoxy resin, polydimethylsiloxane, epoxy resin curing agent, and Al2O3 nanoparticles treated with HDTMS hydrophobicity were dissolved in xylene to prepare a suspension. This suspension was then sprayed onto the surface of a chromium-rich corrosion-resistant coating, and after curing, a superhydrophobic/chromium-rich corrosion-resistant composite coating was obtained.
  • the workpiece preheating treatment is performed at a temperature of 150–220°C for a time of 30–60 min; and/or,
  • the sintering temperature is 980-1150°C and the time is 8-30 min.
  • the thickness of the chromium-rich corrosion-resistant coating is 5-50 ⁇ m; and/or,
  • the thickness of the hydrophobic/chromium-rich corrosion-resistant composite coating is 13-64 ⁇ m.
  • a hydrophobic/chromium-rich corrosion-resistant composite coating is provided, prepared according to the preparation method described above.
  • This disclosure proposes a hydrophobic/chromium-rich corrosion-resistant composite coating, its preparation method, and its application.
  • the preparation method includes: preheating the workpiece; applying a coating slurry to the surface of the preheated workpiece, followed by drying, curing, and sintering to obtain a chromium-rich corrosion-resistant coating on the workpiece surface;
  • the coating slurry includes a solid phase component and a liquid phase component; wherein the solid phase component includes chromium powder, nickel powder, iron powder, and rare earth compounds; the liquid phase component includes Al( H2PO4 ) 3 , water glass, ammonium halide, polyvinyl alcohol, and Cr2O3 ; spraying a layer of superhydrophobic material onto the surface of the chromium-rich corrosion-resistant coating, followed by curing to obtain the hydrophobic/chromium-rich corrosion-resistant composite coating.
  • This method through chromium infiltration and superhydrophobic treatment of the workpiece, endows the workpiece with corrosion resistance, wear resistance, and hydrophobic properties, preventing water vapor from remaining on the inner wall of the pipe, thus avoiding corrosion of the inner wall and improving the overall performance and service life of the pipe.
  • Figure 1 is a flowchart of a method for preparing a hydrophobic/chromium-rich corrosion-resistant composite coating according to an embodiment of the present disclosure.
  • one aspect of this disclosure provides a method S100 for preparing a hydrophobic/chromium-rich corrosion-resistant composite coating, specifically including the following steps S110-S130:
  • the workpiece is preheated at a temperature of 150–220°C for 30–60 minutes.
  • preheating treatment can optimize the microstructure of the metal workpiece, eliminate residual stress, reduce workpiece deformation, improve surface quality, and increase the workpiece temperature, which is beneficial for subsequent chromium diffusion paste coating on its surface.
  • the workpiece can also be cleaned before preheating treatment.
  • alcohol or acetone can be used to clean oil stains and dust from the pipe surface
  • steel brushes can be used to remove surface oxide scale, thereby increasing the specific surface area of the workpiece, enhancing the subsequent penetration effect of metal powder, and increasing the adhesion of the coating.
  • the coating slurry is applied to the surface of the preheated workpiece, and after drying, curing and sintering, a chromium-rich corrosion-resistant coating is obtained on the surface of the workpiece.
  • the coating slurry comprises a solid phase component and a liquid phase component; wherein, the solid phase component includes chromium powder, nickel powder, iron powder, and rare earth compounds; and the liquid phase component includes Al( H2PO4 ) 3 , water glass, ammonium halide, polyvinyl alcohol, and Cr2O3 .
  • the solid-liquid ratio (g:mL) of the solid phase component to the liquid phase component is 10:(1-5), for example, the two components are mixed in proportions of 10:1, 10:2, 10:3, 10:4, 10:5, etc.
  • this embodiment does not specifically limit the mixing method of the solid and liquid components.
  • the solid component can be directly added to the liquid component, or the liquid component can be injected into the solid component for mixing.
  • the powders in the solid component can be...
  • Pre-mixing can be carried out, for example, by ball milling each solid component in a star-shaped ball mill jar at a speed of 350-400 r/min for 6-24 h to pre-mix the solid components, and then mixing the mixed solid components with the liquid components.
  • the chromium powder content is 40-80%, for example, 40%, 50%, 60%, 70%, 80%; the nickel powder content is 5-30%, for example, 5%, 10%, 15%, 20%, 25%, 30%; the iron powder content is 2-20%, for example, 2%, 7%, 10%, 15%, 17%, 20%; and the rare earth compound content is 5-45%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%.
  • the rare earth compound can be a rare earth oxide, such as samarium oxide, europium oxide, yttrium oxide, etc.
  • the rare earth compound can also be a rare earth chloride, such as lanthanum chloride, etc.
  • rare earth atoms are provided by adding oxides and chlorides of rare earth elements.
  • the rare earth element oxides or chlorides segregate at the grain boundaries, acting as grain boundary pinning agents and refining the coating grains. Simultaneously, they prevent Cr atoms from diffusing deeper into the substrate, allowing the coating to grow outwards, increasing the coating thickness and the Cr element concentration within the coating.
  • segregation at the oxide film grain boundaries suppresses the rapid "short-circuit diffusion" of Cr3+ along the grain boundaries, changing the coating oxidation mechanism from primarily outward diffusion of Cr3+ to inward diffusion of O2 ⁇ .
  • This internally grown oxide film is tightly bonded to the substrate, improving the oxide film's resistance to peeling and thus enhancing the coating's corrosion resistance.
  • chromium-iron-nickel co-diffusion can significantly improve the wear resistance and corrosion resistance of the diffusion layer.
  • the content of Al( H2PO4 ) 3 is 10-30%, for example, 10%, 15%, 20%, 25%, or 30%; the content of water glass is 15-25%, for example, 15%, 20%, or 25%; the content of ammonium halide is 5-10%, for example, 5%, 7%, or 10%; the content of polyvinyl alcohol is 10-35%, for example, 10%, 20%, 25%, 30%, or 35%; and the content of Cr2O3 is 10-30%, for example, 10%, 15%, 20%, 25%, or 30%.
  • ammonium halide is either ammonium bromide or ammonium iodide.
  • the liquid phase component through the synergistic effect of the liquid phase component and the solid phase component, can achieve a coating of the required thickness in a single coating process, and the coating surface is smooth and the interior... It is uniform and dense, and has good corrosion resistance.
  • Al( H2PO4 ) 3 serves as a binder, exhibiting high bonding strength with the metal substrate, allowing the required coating thickness to be achieved in a single coating process; simultaneously, this component possesses good high-temperature toughness, making it less prone to cracking during curing and drying.
  • the binder is modified by adding water glass and polyvinyl alcohol, further increasing the high-temperature toughness of Al(H2PO4)3 and its adhesion to the metal substrate.
  • Al ( H2PO4 ) 3 can directly volatilize during the drying process of the slurry, preventing the formation of pores inside the coating due to gas generation during sintering.
  • the polyvinyl alcohol in this embodiment serves as a substance that can improve the high-temperature toughness and bonding strength of Al( H2PO4 ) 3 .
  • NH4I or NH4Br acts as a permeation enhancer to promote the generation of active chromium atoms and nickel atoms.
  • Cr2O3 acts as a curing agent, causing the acidic phosphate ions in the binder to dehydrate and condense, which can effectively reduce the curing film temperature of the slurry.
  • adding an appropriate amount of Cr2O3 can also improve the curing film performance of Al(H2PO4)3 , making the surface of the coating layer smooth and flat, and the interior uniform and dense after drying and curing.
  • this embodiment does not specifically limit the method of applying the coating slurry to the surface of the workpiece.
  • the chromium-impregnating slurry can be applied to the surface of the workpiece by spraying or brushing.
  • this embodiment does not specifically limit the temperature of drying and curing and sintering.
  • the temperature of drying and curing is 60-300°C and the time is 5 min-150 min
  • the temperature of sintering is 980-1150°C and the time is 8-30 min.
  • the drying and curing adopts a segmented gradient curing process. For example, pre-drying at 60-85°C for 5-30 minutes, then drying at 100-160°C for 30-60 minutes, and finally curing at 250-300°C for 20-60 minutes.
  • the segmented curing process ensures that the coating slurry will not have surface quality problems due to local stress during the curing process, and at the same time, it is beneficial to increase the adhesion of the coating.
  • an inert gas protection system is used throughout the sintering process.
  • the workpiece is then subjected to chromizing treatment via rapid heating, followed by furnace cooling.
  • the sintering temperature is [insert temperature here].
  • the temperatures are 980°C, 1000°C, 1050°C, 1100°C, and 1150°C, with times of 8 min, 15 min, 20 min, and 30 min, respectively.
  • the required slurry thickness under this process is 0.5-1.0 mm, and the resulting chromium-rich corrosion-resistant coating on the workpiece surface is approximately 5-50 ⁇ m thick.
  • a layer of superhydrophobic material is sprayed or coated onto the surface of the chromium-rich corrosion-resistant coating and cured to obtain the chromium-rich corrosion-resistant coating.
  • the thickness of the composite coating is 13-64 ⁇ m.
  • a layer of superhydrophobic material is sprayed or coated onto the surface of the chromium-rich corrosion-resistant coating, including:
  • Anhydrous ethanol, HDTMS and nano-alumina particles were mixed to form a suspension, which was then stirred, centrifuged and dried to obtain superhydrophobic Al2O3 nanoparticles modified with HDTMS.
  • An epoxy resin, polydimethylsiloxane, epoxy resin curing agent, and Al2O3 nanoparticles treated with HDTMS hydrophobicity were dissolved in xylene to prepare a suspension. This suspension was then sprayed onto the surface of a chromium-rich corrosion-resistant coating, and after curing, a superhydrophobic/chromium-rich corrosion-resistant composite coating was obtained.
  • the volume of anhydrous ethanol is preferably 45-55 mL, for example, 45 mL, 50 mL, 55 mL, etc.
  • the volume of hexadecyltrimethoxysilane (HDTMS) is preferably 0.5 mL, 1 mL, 1.5 mL, etc.
  • the content of nano-alumina particles is preferably 1 g, 2 g, 3 g, etc.
  • this embodiment does not specifically limit the mixing method of anhydrous ethanol, HDTMS and nano-alumina particles.
  • each component can be placed in a constant temperature magnetic stirrer and stirred for 12 hours to make the alumina particles uniformly distributed in the suspension.
  • superhydrophobic Al2O3 nanoparticles modified with HDTMS can be obtained by centrifugation. After that, the formed nanoparticles are washed with anhydrous ethanol and dried at 120°C for 3 hours to obtain superhydrophobic Al2O3 nanoparticles modified with HDTMS.
  • the content of epoxy resin (EP) is preferably 0.5-1.5g, for example, 0.5g, 1g, 1.5g, etc.
  • the content of polydimethylsiloxane (PDMS) is preferably 0.5-0.7g, for example, 0.5g, 0.6g, 0.67g, 0.7g, etc.
  • the content of HDTMS hydrophobically treated Al2O3 nanoparticles is preferably 1-2g, for example, 1g, 1.5g, 2g, etc.
  • the volume of xylene is preferably 10-30mL, for example, 10mL, 15mL, 20mL, 25mL, 30mL, etc.
  • the ratios of EP and PDMS to the curing agent are 3:1 and 10:1, respectively. That is, the content ratio of EP to epoxy resin curing agent is 3:1, and the ratio of PDMS to curing agent is 10:1.
  • this embodiment applies to epoxy resin, polydimethylsiloxane
  • the method of preparing a suspension by dissolving epoxy resin curing agent and HDTMS hydrophobic Al2O3 nanoparticles in xylene is not specifically limited.
  • each component can be dissolved in xylene, and then HDTMS hydrophobic Al2O3 nanoparticles can be added.
  • the suspension can be uniformly dispersed by heating in a constant temperature water bath at 50°C for 1 hour to obtain a suspension.
  • the process parameters for spraying the suspension onto the surface of the chromium-rich corrosion-resistant coating are as follows: the distance between the spray gun and the substrate is 15-20 cm, for example, 15 cm, 18 cm, or 20 cm, and the spray pressure is 0.8 MPa.
  • the curing temperature is preferably 90-110°C, for example, 90°C, 95°C, 100°C, 110°C, and the curing time is 1-3 hours, for example, 1 hour, 2 hours, 3 hours.
  • superhydrophobic treatment forms a hydrophobic film on the workpiece surface, preventing water vapor from remaining on the surface and ensuring the inner surface of the pipe remains dry, thereby improving its overall performance, such as corrosion resistance and wear resistance. Furthermore, this process can eliminate surface micro-defects and improve its gloss and smoothness.
  • the preparation method of this embodiment is simple and does not require vacuum conditions. At the same time, the preparation efficiency of the chromium infiltration coating is high, the pollution is small, the thickness is adjustable, and the wear resistance is good. In particular, it has excellent resistance to high and low temperature corrosion and steam oxidation. It also has superhydrophobic properties, which can prevent metal oxidation corrosion caused by water vapor, thereby solving the problem of pipeline oxidation corrosion from the root.
  • a hydrophobic/chromium-rich corrosion-resistant composite coating is provided, prepared according to the preparation method described above.
  • the coating of this embodiment has good surface quality, strong hydrophobic effect, excellent corrosion resistance and oxidation resistance, and can be applied to various carbon steel, austenitic steel and high temperature alloy metal parts that need to be strengthened.
  • This example uses a large boiler pipe made of carbon steel as an example to demonstrate its hydrophobic/chromium-rich corrosion resistance.
  • the preparation of the corrosion-resistant composite coating, for pipes with an outer diameter of 55mm, a wall thickness of 8mm, and a length of 4000mm, includes the following steps:
  • the coating slurry should be applied to a suitable thickness in one go using spraying (or brushing, etc.), and multiple layers should not be applied; the thickness of the coating slurry layer should be 0.5 mm.
  • the preparation method of the coating slurry is as follows: Based on the mass percentage of the solid phase components, weigh 60% chromium powder, 15% nickel powder, 5% iron powder, 5% aluminum powder, and 15% yttrium oxide, respectively. Ball mill the mixed metal powders at 350 r /min for 8 hours to obtain the final solid phase component. Based on the mass percentage of the liquid phase components, weigh 25% Al( H2PO4 ) 3 , 18% water glass, 7% ammonium iodide, 15% polyvinyl alcohol, and 35% Cr2O3 , and mix them to obtain the liquid phase component. Mix the solid and liquid phase components at a solid-liquid (g:ml) ratio of 10:2 to obtain the final coating slurry.
  • the metal pipe coated with chromium-impregnated material was pre-dried at 60°C for 5 minutes, then dried at 100°C for 55 minutes, and finally cured at 250°C for 30 minutes.
  • the pipeline was subjected to rapid sintering and diffusion chromizing using a rapid heating method, followed by air cooling to room temperature; the heating rate was set at 1000°C/min, the holding temperature at 980°C, and the holding time at 8min.
  • a suspension was prepared by mixing 50 mL of anhydrous ethanol, 1 mL of hexadecyltrimethoxysilane (HDTMS), and 2 g of nano-alumina particles. The suspension was stirred for 12 h using a constant-temperature magnetic stirrer to ensure uniform distribution of the alumina particles. Superhydrophobic Al2O3 nanoparticles modified with HDTMS were obtained by centrifugation. The nanoparticles were then washed with anhydrous ethanol and dried at 120 °C for 3 h. 1 g of epoxy resin (EP) and 0.67 g of polydimethylsiloxane (PDMS) were completely dissolved...
  • EP epoxy resin
  • PDMS polydimethylsiloxane
  • the ratio of EP to PDMS curing agent was 3:1 and 10:1, respectively.
  • 1.5 g of Al2O3 nanoparticles treated with HDTMS hydrophobicity were added, and the mixture was heated in a constant-temperature water bath at 50 °C for 1 h to achieve uniform dispersion, resulting in a suspension.
  • the suspension was sprayed onto the surface of a chromium-rich corrosion-resistant coating, with a spray gun/substrate distance of 15 cm and a spray pressure of 0.8 MPa. After curing at 100 °C for 2 h, a composite corrosion-resistant coating with a thickness of approximately 13 ⁇ m was obtained.
  • the hydrophobic/chromium-rich corrosion-resistant composite coating prepared in Example 1 has a static water contact angle of 154.1° and a roll-off angle of 2.3°. Water droplets can roll freely on the surface of the coating prepared in Example 1, and the coating still maintains good superhydrophobic properties after undergoing 80 sandpaper abrasion tests (one test cycle is defined as the coating sample is placed face down on a piece of sandpaper (2000 grit) under a 100g load and moved 20cm along a ruler with the help of a horizontal external force).
  • the hydrophobic/chromium-rich corrosion-resistant composite coating prepared in Example 1 showed a significantly improved charge transfer resistance (RCT) value of more than 7 orders of magnitude in a 3.5 wt.% sodium chloride solution, with a corrosion inhibition rate of 99.99%.
  • RCT charge transfer resistance
  • This example uses a large boiler pipe made of austenitic steel as an example to prepare a hydrophobic/chromium-rich corrosion-resistant composite coating.
  • the pipe specifications are all 55mm outer diameter, 8mm wall thickness, and 4000mm length.
  • the steps include:
  • the coating slurry should be applied to a suitable thickness in one go using spraying (or brushing, etc.), and multiple layers should not be applied; the thickness of the coating slurry layer should be 0.5 mm.
  • the preparation method of the coating slurry is as follows: Based on the solid phase components by mass percentage, weigh out 70% chromium powder, 15% nickel powder, 5% iron powder, 5% aluminum powder, and 5% yttrium oxide. The mixed metal powders are then ball-milled at 350 r/min for 10 h to obtain the final solid phase component.
  • the liquid phase component by mass percentage, is 30%... Al( H2PO4 ) 3 , 25% water glass, 10% ammonium iodide, 15% polyvinyl alcohol, and 20% curing agent were mixed and stirred to obtain the liquid phase component.
  • the solid phase component and the liquid phase component were mixed at a solid-liquid (g:ml) ratio of 10:3 to obtain the final coating slurry.
  • the metal pipe coated with chromium-impregnated material was pre-dried at 70°C for 5 minutes, then dried at 120°C for 55 minutes, and finally cured at 300°C for 30 minutes.
  • the pipeline was subjected to rapid sintering and diffusion chromizing using a rapid heating method, followed by air cooling to room temperature; the heating rate was set at 1000°C/min, the holding temperature at 1080°C, and the holding time at 20min.
  • a superhydrophobic material was directly sprayed or coated onto the surface of the prepared chromium-rich corrosion-resistant coating.
  • the spraying process was the same as in Example 1. After curing, a composite corrosion-resistant coating with a thickness of approximately 43 ⁇ m was obtained.
  • the hydrophobic/chromium-rich corrosion-resistant composite coating prepared in Example 2 has a static water contact angle of 155.6° and a roll-off angle of 1.8°. Water droplets can roll freely on the surface of the coating prepared in Example 2, and the coating still maintains good superhydrophobic properties after undergoing 80 sandpaper abrasion tests (one test cycle is defined as the coating sample is placed face down on a piece of sandpaper (2000 grit) under a 100g load and moved 20cm along a ruler with the help of a horizontal external force).
  • the hydrophobic/chromium-rich corrosion-resistant composite coating prepared in Example 2 also showed a charge transfer resistance (RCT) value that was increased by more than 7 orders of magnitude in a 3.5 wt.% sodium chloride solution, and the corrosion inhibition rate also reached 99.99%.
  • RCT charge transfer resistance
  • This example uses a large boiler pipe made of high-temperature alloy as an example to prepare a hydrophobic/chromium-rich corrosion-resistant composite coating.
  • the pipe specifications are all 55mm outer diameter, 8mm wall thickness, and 4000mm length. The process includes the following steps:
  • the coating slurry should be applied to a suitable thickness in one go using spraying (or brushing, etc.), and multiple layers should not be applied; the thickness of the coating slurry layer should be 1.0 mm.
  • the preparation method of the coating slurry is as follows: Based on the solid phase components by mass percentage, weigh 70% chromium powder, 5% nickel powder, 5% iron powder, 5% aluminum powder, and 15% yttrium oxide. Ball mill the mixed metal powders at 350 r /min for 12 h to obtain the final solid phase component. Based on the liquid phase components by mass percentage, weigh 30% Al( H2PO4 ) 3 , 20% water glass, 5% ammonium iodide, 15% polyvinyl alcohol, and 30% curing agent, and mix them to obtain the liquid phase component. Mix the solid and liquid phase components at a solid-liquid (g:ml) ratio of 10:5 to obtain the final coating slurry.
  • the metal pipe coated with chromium-impregnated material was pre-dried at 80°C for 10 minutes, then dried at 150°C for 30 minutes, and finally cured at 300°C for 20 minutes.
  • the pipeline was subjected to rapid sintering diffusion chromizing by rapid heating, followed by air cooling to room temperature; the heating rate was set at 1000°C/min, the holding temperature was 1150°C, and the holding time was 30min.
  • a superhydrophobic material was directly sprayed or coated onto the surface of the prepared chromium-rich corrosion-resistant coating.
  • the spraying process was the same as in Example 1. After curing, a composite corrosion-resistant coating with a thickness of approximately 64 ⁇ m was obtained.
  • the hydrophobic/chromium-rich corrosion-resistant composite coating prepared in Example 3 has a static water contact angle of 154.5° and a roll-off angle of 2.7°. Water droplets can roll freely on the surface of the coating prepared in Example 3, and the coating still maintains good superhydrophobic properties after undergoing 80 sandpaper abrasion tests (one test cycle is defined as the coating sample is placed face down on a piece of sandpaper (2000 grit) under a 100g load and moved 20cm along a ruler with the help of a horizontal external force).
  • the hydrophobic/chromium-rich corrosion-resistant composite coating prepared in Example 3 also showed a charge transfer resistance (RCT) value that was increased by more than 7 orders of magnitude in a 3.5 wt.% sodium chloride solution, thus inhibiting corrosion.
  • the success rate also reached 99.99%.
  • This disclosure presents a hydrophobic/chromium-rich corrosion-resistant composite coating, its preparation method, and its application, which have the following advantages compared to the prior art:
  • this disclosure combines chromium diffusion treatment with surface hydrophobic treatment, so that the surface of the workpiece not only has wear-resistant and corrosion-resistant properties, but also hydrophobic properties, which can prevent metal oxidation and corrosion caused by water vapor, thereby solving the problem of pipeline oxidation and corrosion from the root.
  • the chromium infiltration treatment disclosed herein is highly efficient, produces little pollution, and the coating thickness is adjustable.

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Abstract

一种疏水/富铬耐腐蚀复合涂层及其制备方法、应用，属于材料表面涂层技术领域。制备方法包括：对工件预热处理；将涂覆料浆涂覆在预热处理后的工件表面，经烘干固化、烧结处理，在工件表面得到富铬耐腐蚀涂层；涂覆料浆包括固相组分和液相组分；其中，固相组分包括铬粉、镍粉、铁粉和稀土化合物；所述液相组分包括Al(H 2PO 4) 3、水玻璃、卤化铵、聚乙烯醇及Cr 2O 3；在富铬耐腐蚀涂层表面喷涂一层超疏水材料，经固化处理得到疏水/富铬耐腐蚀复合涂层。通过对工件进行渗铬处理与超疏水处理，使工件具有耐腐蚀性、耐磨损性以及疏水特性，使管道内水蒸气无法停留在管道内壁，可避免对管道内壁的腐蚀，提高管道的综合性能，延长使用寿命。

Description

一种疏水/富铬耐腐蚀复合涂层及其制备方法、应用
相关申请的交叉引用
本申请要求在2024年7月19日提交中国专利局、申请号为202410975831.4、发明名称为“疏水/富铬耐腐蚀复合涂层及其制备方法、应用”的中国专利申请的优先权，其全部内容通过引用的方式并入本文中。
技术领域
本公开属于材料表面涂层技术领域，具体涉及一种疏水/富铬耐腐蚀复合涂层及其制备方法、应用。
背景技术
锅炉管道内表面热腐蚀问题一直是制约火力发电的因素之一，尤其是现阶段火力发电工作条件向着更高蒸汽温度和压力的方向发展，提高管道内表面热防腐性能刻不容缓。
管道的腐蚀问题主要有两部分组成，一种为煤气造成的腐蚀问题，另外一种是水蒸汽造成的金属氧化腐蚀问题。通过在管材表面构建耐腐蚀涂层可以解决管道寿命短、定期处理氧化物等问题，避免管道爆管等危险事件。
目前最常见的抗腐蚀技术就是合金表面渗耐蚀性金属技术，如渗Al、Si、Cr等；通过渗Cr在合金表面形成耐腐蚀涂层，而针对富Cr涂层的制备方法也有很多种，通常包括粉末包埋法、气相沉积法和液相法。液相法通常是将Cr粉放入熔盐中，通过高温保温形成渗Cr层，但该方法高温下熔盐易挥发，对工件、环境等造成伤害。料浆法是通过将料浆直接涂敷或喷涂至工件表面后高温烧结得到涂层，该方法得到涂层耐腐蚀优异且涂层附着性较好。相比其他渗Cr方法，该方法操作简单，适合工业化大范围生产。
然而，根据水的饱和蒸汽压发现在高温高压条件下，管道内仍可存 在液态水。上述防腐蚀的方法仅能在一定程度上延缓管道腐蚀，仍不能从根源上解决管道氧化腐蚀问题。
发明内容
本公开旨在至少解决现有技术中存在的技术问题之一，提供一种疏水/富铬耐腐蚀复合涂层及其制备方法、应用。
本公开的一方面，提供一种疏水/富铬耐腐蚀复合涂层的制备方法，所述制备方法包括：
对工件预热处理；
将涂覆料浆涂覆在预热处理后的工件表面，经烘干固化、烧结处理，在工件表面得到富铬耐腐蚀涂层；所述涂覆料浆包括固相组分和液相组分；其中，所述固相组分包括铬粉、镍粉、铁粉及稀土化合物；所述液相组分包括Al(H2PO4)3、水玻璃、卤化铵、聚乙烯醇及Cr2O3；
在所述富铬耐腐蚀涂层表面喷涂一层超疏水材料，经固化处理得到疏水/富铬耐腐蚀复合涂层。
可选地，所述固相组分与所述液相组分的固液比为10:(1-5)。
可选地，所述铬粉的含量为40-80％；
所述镍粉的含量为5-30％；
所述铁粉的含量为2-20％；
所述稀土化合物的含量为5-45％。
可选地，所述Al(H2PO4)3的含量为10-30％；
所述水玻璃的含量为15-25％；
所述卤化铵的含量为5-10％；
所述聚乙烯醇的含量为10-35％；
所述Cr2O3的含量为10-30％。
可选地，所述稀土化合物为稀土氧化物或稀土氯化物；和/或，
所述卤化铵为溴化铵或碘化铵。
可选地，在所述富铬耐腐蚀涂层表面喷涂一层超疏水材料，经固化处理得到疏水/富铬耐腐蚀复合涂层，包括：
将无水乙醇、HDTMS和纳米氧化铝颗粒混合，制成悬浊液，经搅 拌、离心、干燥处理获得经HDTMS修饰的超疏水Al2O3纳米颗粒；
将环氧树脂、聚二甲基硅氧烷、环氧树脂固化剂、经HDTMS疏水处理的Al2O3纳米颗粒溶于二甲苯中制成悬浊液，将该悬浮液喷涂在富铬耐腐蚀涂层表面，经固化后得到超疏水/富铬耐腐蚀复合涂层。
可选地，所述工件预热处理的温度为150～220℃，时间为30～60min；和/或，
在惰性气体保护下，烧结处理的温度为980-1150℃，时间为8～30min。
可选地，所述富铬耐腐蚀涂层的厚度为5-50μm；和/或，
所述疏水/富铬耐腐蚀复合涂层的厚度为13-64μm。
本公开的另一方面，提出一种疏水/富铬耐腐蚀复合涂层，根据前文记载的制备方法制得。
本公开的另一方面，提出一种疏水/富铬耐腐蚀复合涂层的应用，采用前文记载的疏水/富铬耐腐蚀复合涂层应用于锅炉管道内表面。
本公开提出一种疏水/富铬耐腐蚀复合涂层及其制备方法、应用，制备方法包括：对工件预热处理；将涂覆料浆涂覆在预热处理后的工件表面，经烘干固化、烧结处理，在工件表面得到富铬耐腐蚀涂层；所述涂覆料浆包括固相组分和液相组分；其中，所述固相组分包括铬粉、镍粉、铁粉和稀土化合物；所述液相组分包括Al(H2PO4)3、水玻璃、卤化铵、聚乙烯醇及Cr2O3；在所述富铬耐腐蚀涂层表面喷涂一层超疏水材料，经固化处理得到疏水/富铬耐腐蚀复合涂层。该方法通过对工件进行渗铬处理与超疏水处理，使工件具有耐腐蚀性、耐磨损性，同时还具有疏水特性，使管道内水蒸气无法停留在管道内壁，可避免对管道内壁的腐蚀，进而提高管道的综合性能，延长其使用寿命。
附图说明
图1为本公开一实施例的疏水/富铬耐腐蚀复合涂层的制备方法的流程框图。
具体实施方式
为使本领域技术人员更好地理解本公开的技术方案，下面结合附图和具体实施方式对本公开作进一步详细描述。显然，所描述的实施例是本公开的一部分实施例，而不是全部的实施例。基于所描述的本公开的实施例，本领域普通技术人员在无需创造性劳动的前提下所获得的所有其他实施例，都属于本公开保护范围。
如图1所示，本公开的一方面，提供一种疏水/富铬耐腐蚀复合涂层的制备方法S100，具体包括以下步骤S110-S130：
S110、对工件预热处理。
具体地，将工件在温度为150～220℃的条件下进行预热处理30～60min。
在本实施方式中，通过预热处理可以优化金属工件的组织结构，消除残留应力，使工件变形少，表面质量好，同时提升工件的温度，利于后续渗铬浆料涂覆在其表面上。
应当理解的是，还可以在对工件预热处理前，对工件进行清洁，例如：采用酒精或丙酮清洗管道表面油渍、灰尘等，同时利用钢刷将表面氧化皮去除，提高工件比表面积，增强后续金属粉末渗透效果，增加涂层的附着性。
S120、将涂覆料浆涂覆在预热处理后的工件表面，经烘干固化处理与烧结处理，在工件表面得到富铬耐腐蚀涂层。
在本实施方式中，涂覆料浆包括固相组分和液相组分；其中，固相组分包括铬粉、镍粉、铁粉及稀土化合物；液相组分包括Al(H2PO4)3、水玻璃、卤化铵、聚乙烯醇和Cr2O3。通过将固相组分与液相组分按一定比例混合形成料浆，有助于各金属粉末包覆在工件表面，形成耐腐蚀涂层。
在一些可选实施例中，固相组分与液相组分的固液比(g:mL)为10:(1-5)，例如，以10:1、10:2、10:3、10:4、10:5等比例将两个组分进行混合。
需要说明的是，本实施方式对于固相组分与液相组分的混合形式不做具体限定，可以直接将固相组分加入至液相组分中，也可以将液相组分注入至固相组分中进行混合。当然，也可以将固相组分中的各粉末进 行提前混合，例如，将各固相组分在星式球磨罐中进行球磨处理，转速为350-400r/min，球磨时间为6-24h，以将固相组分进行预混合，将混合后的固相组分再与液相组分混合。
在一些可选实施例中，铬粉的含量为40-80％，例如，40％、50％、60％、70％、80％；镍粉的含量为5-30％，例如，5％、10％、15％、20％、25％、30％；铁粉的含量为2-20％，例如，2％、7％、10％、15％、17％、20％；稀土化合物的含量为5-45％，例如，5％、10％、15％、20％、25％、30％、35％、40％。
作为可选的方案，稀土化合物为稀土氧化物，例如、氧化钐、氧化铕、氧化钇等，当然，稀土化合物还可以为稀土氯化物，例如、氯化镧等。
在本实施方式的固相组分中，通过添加稀土元素的氧化物、氯化物提供稀土原子。在烧结过程中，稀土元素氧化物或氯化物在晶界偏聚，起钉扎晶界的作用，能够细化涂层晶粒；同时，能够防止Cr原子向基体更深层扩散，使涂层向外生长，增加了涂层的厚度和涂层中的Cr元素浓度；在服役过程中，在氧化膜晶界偏聚，从而抑制了Cr3+沿晶界的快速的“短路扩散”，使涂层的氧化机制由Cr3+向外扩散为主转变为O2－向内扩散，这种内生长的氧化膜与基体结合紧密，提高了氧化膜的抗剥落性能，进而提升涂层耐腐蚀的能力。
进一步地，在本实施方式的固相组分中，添加少量的铁和镍主要是为了提高渗铬的速度，降低渗铬温度；铬与铁、镍元素分别形成固溶体，相较于单一渗铬涂层，铬铁镍共渗能显著提高渗层耐磨和耐腐蚀性能。
在另一些可选实施例中，Al(H2PO4)3的含量为10-30％，例如，10％、15％、20％、25％、30％；水玻璃的含量为15-25％，例如，15％、20％、25％；卤化铵的含量为5-10％，例如，5％、7％、10％；聚乙烯醇的含量为10-35％，例如，10％、20％、25％、30％、35％；Cr2O3的含量为10-30％，例如，10％、15％、20％、25％、30％。
作为可选的方案，卤化铵为溴化铵或碘化铵。
在本实施方式的液相组分中，经上述液相组分与固相组分协同作用可实现一次涂覆处理制备形成所需厚度的涂层，且涂层表面光滑，内部 均匀致密，具有良好的耐腐蚀性。
进一步地，在本实施方式的液相组分中，Al(H2PO4)3作为粘结剂，与金属基体间的粘结强度高，一次涂覆处理即可达到制备涂层所需的厚度；同时，该组分高温韧性好，在固化、烘干的过程中不易开裂。
进一步地，在本实施方式的液相组分中，通过添加水玻璃和聚乙烯醇对粘结剂进行改性，进一步增加Al(H2PO4)3的高温韧性和对金属基体的附着能力，且Al(H2PO4)3作为一种无机粘结剂，在对料浆进行烘干的过程中能够直接挥发，不会在烧结过程中因分解产生气体导致涂层内部形成气孔。也就是说，本实施方式的聚乙烯醇作为一种能够改善Al(H2PO4)3高温韧性和粘结强度的物质。
进一步地，在本实施方式的液相组分中，NH4I或NH4Br作为促渗剂，促进活性铬原子、镍原子产生。
更进一步地，在本实施方式的液相组分中，Cr2O3作为固化剂，使粘结剂中的酸式磷酸根脱水缩聚，能有效降低料浆的固化成膜温度，此外，添加适量的Cr2O3还能提高Al(H2PO4)3固化成膜性能，使经过烘干、固化后的涂覆层表面光滑平坦，内部均匀致密。
进一步需要说明的是，本实施方式对于涂覆料浆涂覆在工件表面的方式不做具体限定，例如，采用喷涂或排刷形式将渗铬浆料涂覆至工件表面。
仍需要说明的是，本实施方式对于烘干固化和烧结处理的温度不做具体限定，例如，烘干固化的温度为60～300℃，时间为5min～150min，烧结处理的温度为980-1150℃，时间为8～30min。
在一些可选实施例中，烘干固化采用分段式梯度固化工艺，例如，在60～85℃预烘干5～30min，然后在100～160℃下烘干30～60min，最后在250～300℃下中温固化20～60min，分段固化工艺在保证涂覆料浆在固化过程中不会因局部应力而产生表面质量问题，同时有利于涂料的附着性增加。
在另一些可选的实施例中，为了防止高温下料浆中各组分在空气中发生氧化现象，在烧结过程中全程惰性气体保护，采用快速升温的方式对工件进行渗铬处理，然后采用随炉冷却。其中，烧结处理的温度为 980℃、1000℃、1050℃、1100℃、1150℃，时间为8min、15min、20min、30min。在该工艺下需要涂覆的料浆厚度为0.5-1.0mm，经处理后在工件表面获得的富铬耐腐蚀涂层厚度约为5-50μm。
S130、在富铬耐腐蚀涂层表面喷涂或者涂敷一层超疏水材料，经固化处理，得到富铬耐腐蚀涂层，该复合涂层的厚度为13-64μm。
具体地，在富铬耐腐蚀涂层表面喷涂或者涂敷一层超疏水材料，包括：
将无水乙醇、HDTMS和纳米氧化铝颗粒混合，制成悬浊液，经搅拌、离心、干燥处理获得经HDTMS修饰的超疏水Al2O3纳米颗粒；
将环氧树脂、聚二甲基硅氧烷、环氧树脂固化剂、经HDTMS疏水处理的Al2O3纳米颗粒溶于二甲苯中制成悬浊液，将该悬浮液喷涂在富铬耐腐蚀涂层表面，经固化后得到超疏水/富铬耐腐蚀复合涂层。
在一些可选实施例中，无水乙醇的体积优选45-55mL，例如，45mL、50mL、55mL等，十六烷基三甲氧基硅烷(HDTMS)的体积优选0.5mL、1mL、1.5mL等，纳米氧化铝颗粒的含量优选1g、2g、3g等。
需要说明的是，本实施方式对于无水乙醇、HDTMS和纳米氧化铝颗粒混合方式不做具体限定，例如，将各组分置于恒温磁力搅拌器中搅拌处理12h，使氧化铝颗粒在悬浊液中均匀分布，并通过离心法获得经HDTMS修饰的超疏水Al2O3纳米颗粒，之后，采用无水乙醇将形成的纳米颗粒清洗后在120℃下干燥3h，得到经HDTMS修饰的超疏水Al2O3纳米颗粒。
在另一些可选实施例中，环氧树脂(EP)的含量优选0.5-1.5g，例如，0.5g、1g、1.5g等，聚二甲基硅氧烷(PDMS)的含量优选0.5-0.7g，例如，0.5g、0.6g、0.67g、0.7g等，HDTMS疏水处理的Al2O3纳米颗粒优选含量为1-2g，例如，1g、1.5g、2g等，二甲苯的体积优选为10-30mL，例如，10mL、15mL、20mL、25mL、30mL等。
在另一些可选实施例中，EP和PDMS与固化剂的比例分别为3:1和10:1。也就是说，EP与环氧树脂固化剂的含量比例为3:1，PDMS与固化剂的比例为10:1。
进一步需要说明的是，本实施方式对于环氧树脂、聚二甲基硅氧烷、 环氧树脂固化剂、经HDTMS疏水处理的Al2O3纳米颗粒溶于二甲苯中制成悬浊液的处理方式不做具体限定，例如，将各组分溶于二甲苯中，然后加入经HDTMS疏水处理的Al2O3纳米颗粒，用恒温水浴锅50℃水浴加热1h使其均匀分散，得到悬浮液。
在另一些可选实施例中，将悬浮液喷涂在富铬耐腐蚀涂层表面的工艺参数为：喷枪/基体距离为15-20cm，例如，15cm、18cm、20cm，喷雾压力为0.8MPa。
在另一些可选实施例中，固化处理的温度可优选90-110℃，例如，90℃、95℃、100℃、110℃，固化处理的时间为1-3h，例如，1h、2h、3h。
在本实施方式中，通过超疏水处理可使工件表面形成一层疏水薄膜，使水蒸气无法停留在工件表面，保证管道内表面干燥，从而提高其耐腐蚀性和耐磨损性等综合性能。此外，该工艺还可以消除表面微观缺陷，提高其光泽度和平整度。
本实施方式的制备方法简单，无需在真空条件下进行，同时渗铬涂层制备效率高、污染小、厚度可调、耐磨性能好，尤其具有优异的抗高低温腐蚀和抗蒸汽氧化性能，同时还具有超疏水性能，可以防止水蒸汽造成的金属氧化腐蚀，进而从根源解决管道氧化腐蚀问题。
本公开的另一方面，提出一种疏水/富铬耐腐蚀复合涂层，根据前文记载的制备方法制得。
本公开的另一方面，提出一种疏水/富铬耐腐蚀复合涂层的应用，采用前文记载的疏水/富铬耐腐蚀复合涂层应用于锅炉管道内表面。
本实施方式的涂层具有表面质量好，具有较强的表面疏水效果，耐腐蚀性和抗氧化性能优异，可适用于各类碳钢、奥氏体钢及高温合金等需要强化的金属部件。
下面将结合几个具体实施例进一步说明疏水/富铬耐腐蚀复合涂层的制备方法：
实施例1
本示例以碳钢所制备的大型锅炉管道为例对其进行疏水/富铬耐腐 蚀复合涂层的制备，管道规格均为外径55mm、壁厚8mm、长度4000mm，包括如下步骤：
S1、管道表面清洁
采用酒精或丙酮对管道表面油渍、灰尘等，同时利用钢刷将表面氧化皮去除掉。
S2、管道预热处理
将管道在220℃下预热30min。
S3、管道表面料浆涂覆
采用喷涂(也可采用排刷等方式)形式一次性将涂覆料浆涂覆至合适厚度，不可多次分层涂覆；涂覆料浆层厚度为0.5mm。
涂覆料浆的制备方法如下：按照固相组分按质量百分比计，分别称量60％的铬粉、15％的镍粉、5％的铁粉、5％的铝粉以及15％氧化钇，将混合好的金属混合粉末进行球磨，球磨转速为350r/min，球磨时间为8h得到最终的固相组分。液相组分按照质量百分比计，量取25％的Al(H2PO4)3、18％的水玻璃、7％的碘化铵、15％的聚乙烯醇以及35％的Cr2O3，进行混合搅拌得到液相组分。固相组分与液相组分按照固液(g:ml)比10:2进行混合，得到最终涂覆料浆。
S4、烘干固化
将涂覆有渗铬材料的金属管道于60℃低温预烘干5min，然后100℃低温烘干55min，最后在250℃下中温固化30min。
S5、快速烧结
采用快速升温的方式对管道进行快速烧结扩散渗铬，然后空冷至室温；其中升温速率设为1000℃/min，保温温度为980℃，保温时间为8min。
S6、超疏水处理
将50mL的无水乙醇、1mL的十六烷基三甲氧基硅烷(HDTMS)和2g的纳米氧化铝颗粒制成悬浊液，用恒温磁力搅拌器搅拌12h，使氧化铝颗粒在悬浊液中均匀分布，并通过离心法获得经HDTMS修饰的超疏水Al2O3纳米颗粒，用无水乙醇将形成的纳米颗粒清洗后在120℃下干燥3h。将1g环氧树脂(EP)和0.67g的聚二甲基硅氧烷(PDMS)完全溶 解在20mL二甲苯中，EP和PDMS固化剂的比例分别为3:1和10:1。然后加入1.5g经HDTMS疏水处理的Al2O3纳米颗粒，用恒温水浴锅50℃水浴加热1h使其均匀分散，得到悬浮液。最后，将悬浮液喷涂在富铬耐腐蚀涂层表面，喷枪/基体距离为15cm，喷雾压力为0.8MPa。在100℃固化2h后，得到复合耐腐蚀涂层，该涂层厚度约为13μm。
实施例1中所制备疏水/富铬耐腐蚀复合涂层的静态水接触角为154.1°，滚动角2.3°。水滴可在实施例1所制备涂层表面自由滚动且在经历80次砂纸磨损试验测试(将涂层样品在100g载荷下，面朝下放置在一张砂纸(2000目)上，并在水平外力的帮助下沿尺子移动20cm定义为一次测试循环)后，涂层仍保持良好的超疏水性能。
进一步地，本实施例1所制备疏水/富铬耐腐蚀复合涂层在3.5wt.％氯化钠溶液中的电荷转移电阻(RCT)值显著提高7个数量级以上，缓蚀率达到99.99％。
实施例2
本示例以奥氏体钢所制备的大型锅炉管道为例对其进行疏水/富铬耐腐蚀复合涂层的制备，管道规格均为外径55mm、壁厚8mm、长度4000mm，包括如下步骤：
S1、管道表面清洁
采用酒精或丙酮对管道表面油渍、灰尘等，同时利用钢刷将表面氧化皮去除掉。
S2、管道预热处理
将管道在220℃下预热20min。
S3、管道表面料浆涂覆
采用喷涂(也可采用排刷等方式)形式一次性将涂覆料浆涂覆至合适厚度，不可多次分层涂覆；涂覆料浆层厚度为0.5mm。
涂覆料浆的制备方法如下：按照固相组分按质量百分比计，分别称量70％的铬粉、15％的镍粉、5％的铁粉、5％的铝粉以及5％的氧化钇，将混合好的金属混合粉末进行球磨，球磨转速为350r/min，球磨时间为10h得到最终的固相组分。液相组分按照质量百分比计，量取30％的 Al(H2PO4)3、25％的水玻璃、10％的碘化铵、15％的聚乙烯醇以及20％的固化剂，进行混合搅拌得到液相组分。固相组分与液相组分按照固液(g:ml)比10:3进行混合，得到最终涂覆料浆。
S4、烘干固化
将涂覆有渗铬材料的金属管道于70℃低温预烘干5min，然后120℃低温烘干55min，最后在300℃下中温固化30min。
S5、快速烧结
采用快速升温的方式对管道进行快速烧结扩散渗铬，然后空冷至室温；其中升温速率设为1000℃/min，保温温度为1080℃，保温时间为20min。
S6、超疏水处理
在制备的富铬耐腐蚀涂层表面直接喷涂或者涂敷一层超疏水材料，喷涂过程与实施例1相同，经固化处理得到复合耐腐蚀涂层，该涂层厚度约为43μm。
实施例2中所制备疏水/富铬耐腐蚀复合涂层的静态水接触角为155.6°，滚动角1.8°。水滴可在实施例2所制备涂层表面自由滚动且在经历80次砂纸磨损试验测试(将涂层样品在100g载荷下，面朝下放置在一张砂纸(2000目)上，并在水平外力的帮助下沿尺子移动20cm定义为一次测试循环)后，涂层仍保持良好的超疏水性能。
进一步地，本实施例2所制备疏水/富铬耐腐蚀复合涂层在3.5wt.％氯化钠溶液中的电荷转移电阻(RCT)值同样提高7个数量级以上，缓蚀率也达到99.99％。
实施例3
本示例以高温合金所制备的大型锅炉管道为例对其进行疏水/富铬耐腐蚀复合涂层的制备，管道规格均为外径55mm、壁厚8mm、长度4000mm，包括如下步骤：
S1、管道表面清洁
采用酒精或丙酮对管道表面油渍、灰尘等，同时利用钢刷将表面氧化皮去除掉。
S2、管道预热处理
将管道在220℃下预热50min。
S3、管道表面料浆涂覆
采用喷涂(也可采用排刷等方式)形式一次性将涂覆料浆涂覆至合适厚度，不可多次分层涂覆；涂覆料浆层厚度为1.0mm。
涂覆料浆的制备方法如下：按照固相组分按质量百分比计，分别称量70％的铬粉、5％的镍粉、5％的铁粉、5％的铝粉以及15％的氧化钇，将混合好的金属混合粉末进行球磨，球磨转速为350r/min，球磨时间为12h得到最终的固相组分。液相组分按照质量百分比计，量取30％的Al(H2PO4)3、20％的水玻璃、5％的碘化铵、15％的聚乙烯醇以及30％的固化剂，进行混合搅拌得到液相组分。固相组分与液相组分按照固液(g:ml)比10:5进行混合，得到最终涂覆料浆。
S4、烘干固化
将涂覆有渗铬材料的金属管道于80℃低温预烘干10min，然后150℃低温烘干30min，最后在300℃下中温固化20min。
S5、快速烧结
采用快速升温的方式对管道进行快速烧结扩散渗铬，然后空冷至室温；其中升温速率设为1000℃/min，保温温度为1150℃，保温时间为30min。
S6、超疏水处理
在制备的富铬耐腐蚀涂层表面直接喷涂或者涂敷一层超疏水材料，喷涂过程与实施例1相同，经固化处理得到复合耐腐蚀涂层，该涂层厚度约为64μm。
实施例3中所制备疏水/富铬耐腐蚀复合涂层的静态水接触角为154.5°，滚动角2.7°。水滴可在实施例3所制备涂层表面自由滚动且在经历80次砂纸磨损试验测试(将涂层样品在100g载荷下，面朝下放置在一张砂纸(2000目)上，并在水平外力的帮助下沿尺子移动20cm定义为一次测试循环)后，涂层仍保持良好的超疏水性能。
进一步地，本实施例3所制备疏水/富铬耐腐蚀复合涂层在3.5wt.％氯化钠溶液中的电荷转移电阻(RCT)值同样提高7个数量级以上，缓蚀 率也达到99.99％。
本公开提出一种疏水/富铬耐腐蚀复合涂层及其制备方法、应用，相对于现有技术而言具有以下有益效果：
第一、本公开将渗铬处理与表面疏水处理相结合，使工件表面不仅具有耐磨耐蚀特性，还具有疏水特性，可以防止水蒸汽造成的金属氧化腐蚀，进而从根源解决管道氧化腐蚀问题；
第二、本公开的渗铬处理效率高、污染小、涂层的厚度可调。
可以理解的是，以上实施方式仅仅是为了说明本公开的原理而采用的示例性实施方式，然而本公开并不局限于此。对于本领域内的普通技术人员而言，在不脱离本公开的精神和实质的情况下，可以做出各种变型和改进，这些变型和改进也视为本公开的保护范围。

Claims (10)

  1. 一种疏水/富铬耐腐蚀复合涂层的制备方法，其特征在于，所述制备方法包括：
    对工件预热处理；
    将涂覆料浆涂覆在预热处理后的工件表面，经烘干固化、烧结处理，在工件表面得到富铬耐腐蚀涂层；所述涂覆料浆包括固相组分和液相组分；其中，所述固相组分包括铬粉、镍粉、铁粉及稀土化合物；所述液相组分包括Al(H2PO4)3、水玻璃、卤化铵、聚乙烯醇及Cr2O3；
    在所述富铬耐腐蚀涂层表面喷涂一层超疏水材料，经固化处理得到疏水/富铬耐腐蚀复合涂层。
  2. 根据权利要求1所述的制备方法，其特征在于，所述固相组分与所述液相组分的固液比为10:(1-5)。
  3. 根据权利要求1所述的制备方法，其特征在于，所述铬粉的含量为40-80％；
    所述镍粉的含量为5--30％；
    所述铁粉的含量为2--20％；
    所述稀土化合物的含量为5-45％。
  4. 根据权利要求1所述的制备方法，其特征在于，所述Al(H2PO4)3的含量为10-30％；
    所述水玻璃的含量为15-25％；
    所述卤化铵的含量为5-10％；
    所述聚乙烯醇的含量为10-35％；
    所述Cr2O3的含量为10-30％。
  5. 根据权利要求1所述的制备方法，其特征在于，所述稀土化合物为稀土氧化物或稀土氯化物；和/或，
    所述卤化铵为溴化铵或碘化铵。
  6. 根据权利要求1至5任一项所述的制备方法，其特征在于，在所述富铬耐腐蚀涂层表面喷涂一层超疏水材料，经固化处理得到疏水/富铬耐腐蚀复合涂层，包括：
    将无水乙醇、HDTMS和纳米氧化铝颗粒混合，制成悬浊液，经搅拌、离心、干燥处理获得经HDTMS修饰的超疏水Al2O3纳米颗粒；
    将环氧树脂、聚二甲基硅氧烷、环氧树脂固化剂、经HDTMS疏水处理的Al2O3纳米颗粒溶于二甲苯中制成悬浊液，将该悬浮液喷涂在富铬耐腐蚀涂层表面，经固化后得到超疏水/富铬耐腐蚀复合涂层。
  7. 根据权利要求1至5任一项所述的制备方法，其特征在于，所述工件预热处理的温度为150～220℃，时间为30～60min；和/或，
    在惰性气体保护下，烧结处理的温度为980-1150℃，时间为8～30min。
  8. 根据权利要求1至5任一项所述的制备方法，其特征在于，所述富铬耐腐蚀涂层的厚度为5-50μm；和/或，
    所述疏水/富铬耐腐蚀复合涂层的厚度为13-64μm。
  9. 一种疏水/富铬耐腐蚀复合涂层，其特征在于，根据权利要求1至8任一项所述的制备方法制得。
  10. 一种疏水/富铬耐腐蚀复合涂层的应用，其特征在于，采用权利要求9所述的疏水/富铬耐腐蚀复合涂层应用于锅炉管道内表面。
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