Preparation method of microwave-induced cold spraying carbon nano network reinforced composite coating

Abstract

The invention discloses a preparation method of a microwave-induced cold spraying carbon nano network reinforced composite coating. According to the technical scheme, the preparation method is characterized by comprising the steps that S1, powder is prepared; coating the surface of the metal powder with a carbon nanomaterial to obtain composite powder with a carbon-coated structure; s2, base material treatment; the base material is treated through abrasive paper polishing and ultrasonic cleaning, and a cleaned surface is obtained; s3, spraying treatment is conducted; depositing the carbon-coated composite powder on the surface of a base material through supersonic speed cold spraying to obtain a carbon network skeleton structure coating; compared with the prior art, the preparation method has the technical effects that the carbon layer is rapidly heated after absorbing microwave energy, and the metal matrix wrapped in the carbon layer absorbs heat and generates local melting and recrystallization through the skeleton structure, so that the toughness of the composite material coating is remarkably enhanced on the premise of not damaging the original characteristics of the base material. And after heating is completed, the composite coating is naturally cooled to the room temperature along with the furnace, the composite coating with the excellent performance is obtained, and efficient preparation can be achieved on the basis that the original characteristics of the base material are not changed through the technology.

Description

Technical Field

[0001] The invention relates to the technical field of composite coatings, and in particular to a method for preparing a microwave-induced cold-sprayed carbon nano-network-enhanced composite coating. Background Art

[0002] Cold spray technology, as an advanced surface coating and material preparation technology, has received extensive attention and research since the beginning of the 21st century. This technology is based on the principle of cold gas dynamics, using high-pressure gas (usually helium or nitrogen) to accelerate solid powder particles to supersonic speeds and then impact the surface of the target substrate. During the impact process, the powder particles undergo plastic deformation and are tightly combined to form a continuous coating or structure. Since the powder particles do not undergo a high-temperature melting stage during the cold spray process, the problems of phase change, oxidation and porosity that may occur in traditional thermal spray technology are avoided, thereby ensuring the purity and density of the coating.

[0003] As a material with excellent conductivity, thermal stability and mechanical strength, the carbon network skeleton has broad application prospects in electrochemical energy storage, electromagnetic shielding, thermal management and biomedicine.

[0004] Traditional methods for preparing carbon network skeletons often have problems such as complex processes, high costs, and low production efficiency, which limit their large-scale application. Therefore, it is particularly important to develop a preparation method that is efficient, low-cost, and can maintain the excellent properties of the carbon network skeleton. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a microwave-induced cold-sprayed carbon nano-network-enhanced composite coating, which has the advantages that the carbon layer rapidly heats up after absorbing microwave energy, and the metal matrix wrapped therein absorbs heat and undergoes local melting and recrystallization through the skeleton structure, thereby significantly enhancing the strength and toughness of the composite material coating without destroying the original properties of the substrate. After the heating is completed, the composite coating is naturally cooled to room temperature with the furnace to obtain a composite coating with excellent performance. Through this technology, it can be efficiently prepared without changing the original properties of the substrate.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions: a method for preparing a microwave-induced cold-sprayed carbon nano-network reinforced composite coating, the preparation method comprising the following steps:

[0007] S1: powder preparation; coating the carbon nanomaterial on the surface of the metal powder to obtain a composite powder with a carbon-coated structure;

[0008] S2: Substrate treatment: The substrate is treated by sandpaper polishing and ultrasonic cleaning to obtain a clean surface;

[0009] S3: spraying treatment: depositing the carbon-coated composite powder on the surface of the substrate by supersonic cold spraying to obtain a carbon network skeleton structure coating;

[0010] S4: coating reinforcement; the substrate after spraying treatment is placed in a heating device, a partition plate is added, and an absorbing material is added and placed in a mullite box, and then heated by microwaves and cooled in a furnace.

[0011] The present invention is further configured as follows: in the step S1, the carbon nanomaterial is coated on the surface of the metal powder, and can be prepared by any one of electrostatic adsorption method, sol-gel method, vapor deposition method, mechanical ball milling method and arc method.

[0012] The present invention is further configured as follows: in the step S1, the thickness of the carbon nano material coating layer in the prepared carbon nano coated powder is 3 to 30 nm.

[0013] The present invention is further configured as follows: in the step S1, the carbon nanomaterial includes carbon nanotubes and graphene, and the metal powder includes iron powder, nickel powder, copper powder, aluminum powder and titanium powder.

[0014] The present invention is further configured as follows: in step S2, the sandpaper polishing treatment uses sandpaper with grits of 100, 800, 1000 and 2000 for step-by-step polishing, and the ultrasonic cleaning treatment uses a cleaning agent of ethanol, acetone or deionized water.

[0015] The present invention is further configured as follows: in step S3, the parameter adjustment formula of supersonic cold spraying is as follows:

[0016]

[0017] Among them, σ t is the tensile strength, σ0 is the tensile strength of the substrate itself, g is a coefficient related to the spraying parameters and the properties of the substrate, A is the optimal aspect ratio, a is the general aspect ratio, σ AR is the standard deviation of the aspect ratio distribution, which is used to describe the degree of fluctuation of the aspect ratio around the optimal value.

[0018] The present invention is further configured as follows: in step S4, the microwave oven heating time control formula is as follows:

[0019] a=gH

[0020] H=dtK

[0021]

[0022] g is a coefficient related to the spraying parameters and the properties of the substrate, H is the coating thickness, K is the carbon nanomaterial content in the coating powder, t is the reaction time for preparing the coating powder, d is the parameter coefficient for preparing the coating powder, f is the heating coefficient, ΔT is the heating time, C1ρ1V1 is the specific heat capacity, density and volume of the carbon nanomaterial, and C2ρ2V2 is the specific heat capacity, density and volume of the metal powder.

[0023] The present invention is further configured as follows: in the step S4, the partition plate is used to separate the substrate from the absorbing material to prevent the absorbing material from directly contacting the surface of the substrate, while ensuring that the microwave energy can act evenly on the coating. The amount of the absorbing material used is referenced to the mass of silicon carbide powder (g) = M*sintered sample volume (cm3), and M is taken as 15.

[0024] The present invention is further configured as follows: in step S3, the substrate includes copper, iron, nickel, aluminum, titanium and alloys thereof.

[0025] The present invention is further configured as follows: in step S4, the heating device specifically includes a metal shell, a microwave is arranged in the metal shell, a turntable is provided on the bottom side of the metal shell, mullite is provided on the turntable, a substrate is placed in the mullite, a coating is provided on the substrate, a partition plate is provided above the coating, and the mullite is filled with absorbing powder.

[0026] In summary:

[0027] 1. Specifically, carbon nanomaterials are coated on the surface of metal powders to obtain composite powders with carbon-coated structures, and then the powders are deposited on the surface of the substrate by supersonic cold spraying to obtain a carbon network skeleton structure coating. The substrate is wrapped and fixed with thermal insulation materials, and absorbing materials are arranged on the surface of the coating. A layer of partition is used between the absorbing material and the coating to separate them to prevent the absorbing material from directly contacting the powder. In this process, the absorbing material will first transfer heat downward layer by layer in the form of heat conduction, and conduct it through the carbon layer, and then trigger the coupling of metal powder and microwaves layer by layer, and finally react chemically with the metal matrix around the carbon nanonetwork to generate carbides, thereby forming an in-situ self-generated skeleton to increase strength. At the same time, the metal matrix is ​​heat-treated to form recovery and recrystallization, which increases toughness and forms an enhanced toughening effect. The overall process of this method is simple to operate, has a fast heating speed, high energy utilization, and uniform heating. The bonding mode between the carbon layer inside the coating and the metal matrix and between the coating and the substrate is transformed into metallurgical bonding, which significantly improves the bonding strength between them.

[0028] 2. The present invention is applicable to the preparation of repair layers on the surfaces of various substrates and has a wide range of applications. The traditional method of optimizing the preparation of carbon network skeletons often has problems such as low mechanical properties of the coating, complex process, high cost, and low production efficiency.

[0029] 3. The present invention can obtain a coating with a uniform thickness range, and the coating thickness can be controlled by controlling the amount of the filled metal powder, which is easy to regulate.

[0030] 4. The process of the present invention is simple, easy to operate, does not require the use of chemical reagents that are harmful to the environment, is energy-saving and environmentally friendly, has low cost, and is easy to realize industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flow chart of the method for preparing the carbon nano-network reinforced composite coating of this embodiment;

[0032] Figure 2 This is a schematic diagram of the overall structure of the heating device used in this embodiment.

[0033] Figure numerals: 1. metal shell; 2. microwave; 3. mullite; 4. turntable; 5. microwave-absorbing powder; 6. partition plate; 7. coating; 8. substrate. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0035] Example: Refer to Figure 1-2 As shown, a method for preparing a microwave-induced cold spray carbon nano-network reinforced composite coating comprises the following steps:

[0036] S1: Powder preparation; carbon nanomaterials are coated on the surface of metal powders to obtain composite powders with carbon-coated structures. For example, mechanical ball milling of graphene powder and nickel powder is used to apply mechanical forces such as shear, collision and friction to the mixed powders through the grinding balls during the ball milling process. These mechanical forces lead to physical and chemical interactions between graphene powder and nickel powder, such as van der Waals forces and chemical bonding. As the ball milling proceeds, graphene sheets are gradually coated on the surface of nickel powder to form a carbon-coated nickel structure.

[0037] S2: Substrate treatment: The substrate is treated by sandpaper polishing and ultrasonic cleaning to obtain a clean surface. The purpose of surface treatment is to ensure that the substrate has an average surface roughness. At the same time, a smooth surface is also a necessary condition for the effective combination of powder and substrate during spraying;

[0038] S3: Spraying treatment; the carbon-coated composite powder is deposited on the surface of the substrate by supersonic cold spraying to obtain a carbon network skeleton structure coating, wherein the high-pressure gas is divided into two parts by the cold spraying equipment, one part is heated by the heater, and the other part passes through the powder feeding channel. The two parts of gas are mixed and enter the nozzle, expanding to form an ultrasonic gas-powder flow. In this process, the carbon-coated powder is impacted at high speed and accelerated to an extremely high speed. The accelerated powder particles hit the surface of the substrate at a supersonic speed. Due to the extremely high impact speed, the powder particles undergo strong plastic deformation and are deposited on the substrate. The bonding force between the powder particles and the bonding force between the particles and the substrate are enhanced. As the cold spraying process continues, more and more powder particles are deposited on the substrate and connected to each other to form a network structure. Since the carbon material in the carbon-coated powder has good conductivity and mechanical properties, the formed carbon skeleton network structure has high strength and stability. At the same time, the presence of carbon material can also improve the corrosion resistance and wear resistance of the entire structure;

[0039] S4: Coating reinforcement; the substrate after spraying treatment is loaded into the heating device, and the absorbing material is added after the partition plate is added and placed in the mullite box. After microwave heating, it is cooled in the furnace. The purpose of using the absorbing material is to first heat up through the absorbing material, transfer heat downward layer by layer in the form of heat conduction, and then trigger the coupling effect between the metal powder and the microwave layer by layer, and finally achieve the remelting of the entire coating. Since the skin depth of the metal is low (usually in microns) and its surface reflects microwaves, it cannot be heated by direct exposure to microwave radiation. Once the metal powder reaches the critical temperature of melting, it will begin to absorb microwave energy and heat up rapidly. Therefore, the absorbing material is used to heat the metal powder to its critical temperature through heat conduction, so that the metal powder absorbs microwaves and then achieves cladding. The microwave heating coating makes the carbon-coated powder quickly reach the melting temperature, and the powder particles are more likely to diffuse and penetrate each other in the molten state, thereby strengthening the connection of the carbon skeleton network structure.

[0040] At the same time, the uniformity of microwave heating helps to reduce defects and pores in the coating, improve the density and strength of the coating. Microwave heating can also promote the bonding between the coating and the substrate, and improve the adhesion and durability of the coating.

[0041] Furthermore, in step S1, the carbon nanomaterial is coated on the surface of the metal powder, and can be prepared by any one of electrostatic adsorption method, sol-gel method, vapor deposition method, mechanical ball milling method and arc method.

[0042] Furthermore, in step S1, the carbon nanomaterial coating layer in the prepared carbon nano-coated powder has a thickness of 3 to 30 nm. In step S1, the carbon nanomaterial includes carbon nanotubes and graphene, and the metal powder includes iron powder, nickel powder, copper powder, aluminum powder and titanium powder.

[0043] Furthermore, in step S2, the sandpaper polishing treatment uses sandpaper with grits of 100, 800, 1000 and 2000 for polishing in stages, and the ultrasonic cleaning treatment uses a cleaning agent such as ethanol, acetone or deionized water.

[0044] Furthermore, in step S3, the parameter adjustment formula of supersonic cold spraying is as follows:

[0045]

[0046] Among them, σ t is the tensile strength, σ0 is the tensile strength of the substrate itself, g is a coefficient related to the spraying parameters and the properties of the substrate, A is the optimal aspect ratio, a is the general aspect ratio, σ AR is the standard deviation of the aspect ratio distribution, which is used to describe the degree of fluctuation of the aspect ratio around the optimal value.

[0047] Further, in step S4, the microwave oven heating time control formula is as follows:

[0048] a=gH

[0049] H=dtK

[0050]

[0051] g is a coefficient related to the spraying parameters and the properties of the substrate, with a value of 0.5 to 1.6, H is the coating thickness, K is the carbon nanomaterial content in the coating powder, t is the reaction time for preparing the coated powder, with a value of 0.3 to 0.8d is the parameter coefficient for preparing the coated powder, f is the heating coefficient, ΔT is the heating time, C1ρ1V1 is the specific heat capacity, density, and volume of the carbon nanomaterial, respectively, and C2ρ2V2 is the specific heat capacity, density, and volume of the metal powder, respectively.

[0052] Furthermore, in step S4, a partition plate is used to separate the substrate from the absorbing material to prevent the absorbing material from directly contacting the surface of the substrate, while ensuring that the microwave energy can act evenly on the coating. The amount of the absorbing material used is referenced as follows: mass of silicon carbide powder (g) = M*volume of sintered sample (cm3), where M is 15. In step S3, the substrate includes copper, iron, nickel, aluminum, titanium and their alloys.

[0053] Further, in step S4, the heating device specifically includes a metal shell 1, a microwave 2 is arranged in the metal shell 1, a turntable 4 is arranged on the bottom side of the metal shell 1, mullite 3 is arranged on the turntable 4, a substrate 8 is placed in the mullite 3, a coating 7 is arranged on the substrate 8, a partition plate 6 is arranged above the coating 7, and the mullite 3 is filled with absorbing powder 5.

[0054] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A method for preparing a microwave-induced cold sprayed carbon nano-network reinforced composite coating, characterized in that: The preparation method comprises the following steps: S1: powder preparation; coating the carbon nanomaterial on the surface of the metal powder to obtain a composite powder with a carbon-coated structure; S2: Substrate treatment: The substrate is treated by sandpaper polishing and ultrasonic cleaning to obtain a clean surface; S3: spraying treatment: depositing the carbon-coated composite powder on the surface of the substrate by supersonic cold spraying to obtain a carbon network skeleton structure coating; S4: coating reinforcement; the substrate after spraying treatment is placed in a heating device, a partition plate is added, and an absorbing material is added and placed in a mullite box, and then heated by microwaves and cooled in a furnace.

2. The method for preparing a microwave-induced cold sprayed carbon nano-network reinforced composite coating according to claim 1, characterized in that: In the step S1, the carbon nanomaterial is coated on the surface of the metal powder, and can be prepared by any method including electrostatic adsorption method, sol-gel method, vapor deposition method, mechanical ball milling method, and arc method.

3. The method for preparing a microwave-induced cold sprayed carbon nano-network reinforced composite coating according to claim 1, characterized in that: In the step S1, the thickness of the carbon nanomaterial coating layer in the prepared carbon nanomaterial coated powder is 3 to 30 nm.

4. The method for preparing a microwave-induced cold sprayed carbon nano-network reinforced composite coating according to claim 1, characterized in that: In the step S1, the carbon nanomaterial includes carbon nanotubes and graphene, and the metal powder includes iron powder, nickel powder, copper powder, aluminum powder and titanium powder.

5. The method for preparing a microwave-induced cold sprayed carbon nano-network reinforced composite coating according to claim 1, characterized in that: In step S2, the sandpaper polishing treatment uses sandpaper with grits of 100, 800, 1000 and 2000 in a step-by-step manner, and the ultrasonic cleaning treatment uses a cleaning agent such as ethanol, acetone or deionized water.

6. The method for preparing a microwave-induced cold sprayed carbon nano-network reinforced composite coating according to claim 1, characterized in that: In step S3, the parameter adjustment formula of supersonic cold spraying is as follows: Among them, σ t is the tensile strength, σ0 is the tensile strength of the substrate itself, g is a coefficient related to the spraying parameters and the properties of the substrate, A is the optimal aspect ratio, a is the general aspect ratio, σ AR is the standard deviation of the aspect ratio distribution, which is used to describe the degree of fluctuation of the aspect ratio around the optimal value.

7. The method for preparing a microwave-induced cold sprayed carbon nano-network reinforced composite coating according to claim 1, characterized in that: In step S4, the microwave oven heating time control formula is as follows: a=gH H=dtK g is a coefficient related to the spraying parameters and the properties of the substrate, H is the coating thickness, K is the carbon nanomaterial content in the coating powder, t is the reaction time for preparing the coating powder, d is the parameter coefficient for preparing the coating powder, f is the heating coefficient, ΔT is the heating time, C1ρ1V1 is the specific heat capacity, density and volume of the carbon nanomaterial, and C2ρ2V2 is the specific heat capacity, density and volume of the metal powder.

8. The method for preparing a microwave-induced cold sprayed carbon nano-network reinforced composite coating according to claim 1, characterized in that: In step S4, the partition plate is used to separate the substrate from the absorbing material to prevent the absorbing material from directly contacting the surface of the substrate, while ensuring that the microwave energy can act evenly on the coating. The amount of the absorbing material used is based on the mass of silicon carbide powder (g) = M*sintered sample volume (cm3), where M is 15.

9. The method for preparing a microwave-induced cold sprayed carbon nano-network reinforced composite coating according to claim 1, characterized in that: In the step S3, the substrate includes copper, iron, nickel, aluminum, titanium and alloys thereof.

10. The method for preparing a microwave-induced cold sprayed carbon nano-network reinforced composite coating according to claim 1, characterized in that: In step S4, the heating device specifically comprises a metal shell (1), a microwave (2) is arranged in the metal shell (1), a turntable (4) is arranged on the bottom side of the metal shell (1), mullite (3) is arranged on the turntable (4), a substrate (8) is placed in the mullite (3), a coating (7) is arranged on the substrate (8), a partition plate (6) is arranged above the coating (7), and the mullite (3) is filled with microwave absorbing powder (5).

Images