Method for regulating and controlling metal-fluoroplastic binding force through multi-scale interface and metal-fluoroplastic product

Abstract

The invention provides a method for regulating and controlling metal-fluoroplastic binding force through a multi-scale interface and a metal-fluoroplastic product. The method comprises the following steps that S1, the surface of a metal matrix is treated in an electrolysis mode, electrolyte is at least two of hydrochloric acid, sulfuric acid and phosphoric acid, and hydrochloric acid is necessary; and S3, the cavity of the metal matrix treated in the S2 is filled with polytrifluorochloroethylene through thermoplastic compression molding. According to the method for adjusting and controlling the metal-fluoroplastic interface in multiple sizes, the binding force between the metal and the fluoroplastic is effectively enhanced, and the method is suitable for a metal matrix in a complex geometrical shape and has important application in a polytrifluorochloroethylene valve low-temperature sealing assembly.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of polymer-metal matrix composites, and relates to a method for regulating the bonding force of metal-fluoroplastic and a metal-fluoroplastic product, in particular to a method for regulating the interface performance of a metal-fluoroplastic low-temperature sealing assembly, which has important application in aerospace valve sealing. BACKGROUND As a sealing material that can be used for a long time in an ultra-low temperature (minus 200 DEG C) working condition, polytrifluorochloroethylene (PCTFE) does not crack and does not creep in a liquid nitrogen and liquid oxygen environment, and maintains a certain flexibility, and has an important application prospect in the field of national defense and military industry. At present, the material of the valve rod product in the liquid hydrogen and liquid oxygen filling valve of a carrier rocket is metal, which is easy to wear when the valve moves, thereby causing movement stagnation. Therefore, polytrifluorochloroethylene and metal composite structures are selected when designing valve products to improve the reliability of the valve. However, due to the inertness of polytrifluorochloroethylene, the bonding performance between the polytrifluorochloroethylene and the metal valve is poor, and the debonding phenomenon occurs in use, and the "gas leakage" is easy to occur under high pressure working conditions.

[0002] Patent CN106563629A discloses a method for improving the bonding force of polytrifluorochloroethylene and a metal matrix. A dispersion liquid of polytrifluorochloroethylene is prepared first, then is coated on the surface of a sandblasted metal matrix, and then a sealing assembly connected with the polytrifluorochloroethylene and the metal matrix is prepared by hot plastic molding, so as to improve the interface bonding force of the metal-fluoroplastic. Considering the complex geometry of the metal matrix, the dispersion liquid is difficult to be uniformly coated on the surface of the metal matrix, which affects the quality stability of the product.

[0003] CN117565301A discloses a preparation method for improving the interface performance of a polytrifluorochloroethylene and aluminum alloy composite structure. The method comprises the following steps: S1, treating the sandblasted aluminum alloy (valve) matrix by adopting a method of first sulfuric acid anodization and then potassium dichromate sealing, to form an oxide layer on the surface of the aluminum alloy; S2, filling the polytrifluorochloroethylene into the cavity of the aluminum alloy (valve) matrix treated in S1, and integrally forming by hot plastic molding. In the application, the oxide layer on the surface of the aluminum alloy not only enhances the bonding strength of the aluminum alloy and the polytrifluorochloroethylene, but also can be used for the aluminum alloy valve matrix with a complex geometry, and has important application in the polytrifluorochloroethylene valve sealing. However, the scheme includes multiple process procedures such as surface sandblasting, anodic oxidation and sealing treatment, and the process procedure is complex. SUMMARY

[0004] In view of the deficiencies in the prior art, the application provides a method for regulating the bonding force of metal-fluoroplastic by a multi-scale interface and a metal-fluoroplastic product. In the application, the surface of a metal substrate is first treated by electrolysis, and then polytrifluorochloroethylene is filled in the cavity of the treated metal substrate by hot plastic die forming to obtain a metal-fluoroplastic low-temperature sealing assembly.

[0005] The purpose of the application is achieved by the following technical solutions: In a first aspect, the application provides a method for regulating the bonding force of metal-fluoroplastic by a multi-scale interface, which comprises the following steps: S1, the surface of a metal substrate is first treated by electrolysis; the electrolyte is at least two of hydrochloric acid, sulfuric acid and phosphoric acid, and hydrochloric acid is a necessary component; the voltage is 10-25 V; the temperature is 10-30 DEG C; and the time is 2-10 min; S2, polytrifluorochloroethylene is filled in the cavity of the metal substrate treated in S1 by hot plastic die forming.

[0006] As an embodiment of the application, in step S1, if the electrolysis time is prolonged to 20 min, the multi-scale micro-nano structure will be destroyed, or the pore structure will be too large, or even a micron or irregular rough structure will be formed.

[0007] As an embodiment of the application, the roughness of the metal substrate treated in step S1 is 5-20 μm, and the size of the surface pores is 30-100 nm.

[0008] As an embodiment of the application, in step S1, the concentration of hydrochloric acid in the electrolyte is 20 g / L-25 g / L. As known by those skilled in the art, hydrochloric acid reacts violently with Al and is difficult to be anodized, so it is usually not used as an electrolyte. In the application, the appropriate introduction of hydrochloric acid significantly improves the roughness of the surface of the pre-metal substrate, which belongs to an unexpected effect.

[0009] As an embodiment of the application, in step S1, the electrolyte is hydrochloric acid and sulfuric acid with a molar ratio of 1-3:8-12; or hydrochloric acid, sulfuric acid and phosphoric acid with a molar ratio of 1-3:8-12:1-3.

[0010] As an embodiment of the application, in step S2, the particle size of the polytrifluorochloroethylene is 20-100 mesh. If the particle size is too large, the volume is large, the shrinkage ratio is large after melting and pressing, and it is not conducive to forming; and if the particle size is too small, the heated particles are unstable and impurities are easily produced.

[0011] In one embodiment of the present invention, in step S2, the molding temperature of polychlorotrifluoroethylene is 230~250 ℃, the molding pressure is 1~4 MPa, and the molding time is 15~90 min. If the temperature is too low, the melting will be uneven, resulting in defects.

[0012] In a second aspect, the present invention provides a metal-fluoroplastic product prepared by any of the methods described above.

[0013] As one embodiment of the present invention, the metal-fluoroplastic product is a metal-fluoroplastic low-temperature sealing component.

[0014] Thirdly, the present invention provides an application of the above-mentioned metal-fluoroplastic product or metal-fluoroplastic cryogenic sealing component in the manufacture of aerospace valve products.

[0015] This invention employs an electrolytic method to treat the surface of a metal substrate, then fills the cavity of the treated metal substrate with polychlorotrifluoroethylene (PTFE), and finally thermoplastically molds it into a single metal-fluoroplastic sealing assembly. Compared with the prior art, this invention has the following advantages: (1) The key to the effective connection between polychlorotrifluoroethylene and metal is the effective interface bonding area. The roughness of the metal surface directly determines the interface bonding area. Traditional sulfuric acid or phosphoric acid electrolysis processes are difficult to obtain a large surface roughness, generally below 5 μm. This invention proposes a hydrochloric acid-sulfuric acid or hydrochloric acid-sulfuric acid-phosphoric acid synergistic strategy. The introduction of hydrochloric acid significantly improves the surface roughness, thus improving the surface bonding force.

[0016] (2) Compared with sandblasting, the aluminum alloy surface after electrolytic treatment forms a multi-scale micro-nano structure. The multi-scale micro-nano structure is mainly characterized by: a certain roughness at the micron level, and nanopore structure in the micron-sized area. The anchoring effect of this multi-level structure is similar to that of tree roots, with many branch structures, which enhances the bonding force. Therefore, it not only increases the contact area between metal and fluoroplastic, but also has an "anchoring" effect, enhancing the bonding force between the two.

[0017] (3) Compared with sandblasting the metal surface first and then applying the primer, the primer is difficult to coat the surface of a substrate with complex geometry. However, the electrolytic treatment method in this invention does not depend on the geometry of the metal substrate, and the process has high reliability. Attached Figure Description

[0018] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 Here is a picture of the actual tooling used for pull-out strength testing; Figure 2A scanning electron microscope image (10 μm) of Example 1; Figure 3 A scanning electron microscope image (100 nm) of Example 1; Figure 4 A scanning electron microscope image (10 μm) of Example 2; Figure 5 A scanning electron microscope image (100 nm) of Example 2; Figure 6 A scanning electron microscope image (10 μm) of Example 3; Figure 7 A scanning electron microscope image (100 nm) of Example 3. DETAILED DESCRIPTION

[0019] The application will be described in further detail below with specific examples. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the application. These are all within the scope of protection of the application.

[0020] In order to further illustrate the technical effects of the application, the application has carried out related experiments. Table 1 is the metal-fluoroplastic drawing performance and the qualified rate of metal-fluoroplastic sealing assembly string gas.

[0021] Example 1 This example relates to the surface treatment of an aluminum alloy substrate, and the specific preparation includes the following: an electrolytic method is used to treat a sandblasted 2A14 aluminum alloy substrate, the concentration of hydrochloric acid is 20 g / L, the concentration of sulfuric acid is 200 g / L, the voltage is 15 V, the temperature is 20 ℃, and the time is 5 min. After drying, the aluminum alloy substrate after surface treatment is obtained, the surface roughness is 10 μm, and the surface nanopore size is 40 nm (the scanning electron microscope image is shown in Figure 2 、 3 ).

[0022] Example 2 This example relates to the surface treatment of an aluminum alloy substrate, and the specific preparation includes the following: an electrolytic method is used to treat a sandblasted 2A14 aluminum alloy substrate, the concentration of hydrochloric acid is 20 g / L, the concentration of sulfuric acid is 200 g / L, the concentration of phosphoric acid is 20 g / L, the voltage is 15 V, the temperature is 20 ℃, and the time is 8 min. After drying, the aluminum alloy substrate after surface treatment is obtained, the surface roughness is 14 μm, and the surface nanopore size is 55 nm (the scanning electron microscope image is shown in Figure 4 、 5 ).

[0023] Example 3 This embodiment relates to surface treatment of a stainless steel substrate, and specifically preparation includes the following: treating the surface substrate of sandblasted 06cr19ni10 stainless steel by electrolysis, the concentration of hydrochloric acid is 25 g / L, the concentration of sulfuric acid is 200 g / L, the voltage is 15 V, the temperature is 20 ℃, the time is 8 min, and after drying, the surface treated stainless steel substrate is obtained, the surface roughness is 15 μm, and the surface nanopore size is 47 nm (the scanning electron microscope image is shown in Figure 6 、 7 ).

[0024] Example 4 This embodiment relates to surface treatment of a titanium alloy substrate, and specifically preparation includes the following: treating the surface substrate of sandblasted TC4 titanium alloy by electrolysis, the concentration of hydrochloric acid is 25 g / L, the concentration of sulfuric acid is 200 g / L, the voltage is 15 V, the temperature is 20 ℃, the time is 10 min, and after drying, the surface treated titanium alloy substrate is obtained, the surface roughness is 17 μm, and the surface nanopore size is 45 nm.

[0025] Example 5 This embodiment relates to the preparation of an aluminum alloy-polytrifluorochloroethylene sealing assembly (polytrifluorochloroethylene sealing ring), and specifically preparation includes the following: specifically preparation includes the following steps: adding 25 g of polytrifluorochloroethylene into an aluminum alloy substrate cavity (Example 2, the cavity outer diameter is 68 mm, and the inner diameter is 58 mm), the mold temperature is 230 ℃, the holding pressure is 2 MPa, and the molding time is 60 min.

[0026] Example 6 This embodiment relates to the preparation of a stainless steel-polytrifluorochloroethylene sealing assembly, and specifically preparation includes the following: specifically preparation includes the following steps: adding 25 g of polytrifluorochloroethylene into an aluminum alloy substrate cavity (Example 3, the cavity outer diameter is 68 mm, and the inner diameter is 58 mm), the mold temperature is 230 ℃, the holding pressure is 2 MPa, and the molding time is 60 min.

[0027] Example 7 This embodiment relates to the preparation of a titanium alloy-polytrifluorochloroethylene sealing assembly, and specifically preparation includes the following: specifically preparation includes the following steps: adding 25 g of polytrifluorochloroethylene into a titanium alloy substrate cavity (Example 4, the cavity outer diameter is 68 mm, and the inner diameter is 58 mm), the mold temperature is 230 ℃, the holding pressure is 2 MPa, and the molding time is 60 min.

[0028] Comparative Example 1 This comparative example relates to the preparation of an aluminum alloy-polychlorotrifluoroethylene sealing assembly. The specific preparation includes the following steps: 25 g of polychlorotrifluoroethylene is added to the surface of an aluminum alloy cavity that has been sandblasted with 20-mesh brown corundum at 0.7 MPa (specifications are the same as in Example 5). The mold temperature is 230°C, the holding pressure is 2 MPa, and the molding time is 60 min.

[0029] Comparative Example 2 This comparative example relates to the preparation of a stainless steel-polychlorotrifluoroethylene sealing assembly. The specific preparation includes the following steps: 25 g of polychlorotrifluoroethylene is added to the surface of a stainless steel cavity that has been sandblasted with 20-mesh brown corundum at 0.7 MPa (specifications are the same as in Example 5). The mold temperature is 230°C, the holding pressure is 2 MPa, and the molding time is 60 min.

[0030] Comparative Example 3 This comparative example relates to the preparation of a titanium alloy-polychlorotrifluoroethylene sealing assembly. The specific preparation includes the following steps: 25 g of polychlorotrifluoroethylene is added to the surface of a titanium alloy cavity that has been sandblasted with 20-mesh brown corundum at 0.7 MPa (specifications are the same as in Example 5). The mold temperature is 230°C, the holding pressure is 2 MPa, and the molding time is 60 min.

[0031] Comparative Example 4 This comparative example relates to the formation of an oxide layer on an aluminum alloy substrate. The specific preparation process includes the following: First, 50-mesh brown steel is used... The aluminum alloy substrate was sandblasted at 0.5 MPa. Then, it underwent sulfuric acid anodizing treatment at 15 V, 10 °C, and 30 min. Finally, it was closed with potassium dichromate at 95 °C for 15 min. After drying, an aluminum alloy substrate with an alumina coating of 9 μm was obtained. Then, 25 g of polychlorotrifluoroethylene was added to the cavity of the hot-pressed alumina-coated aluminum alloy substrate. The mold temperature was 230 °C, the holding pressure was 2 MPa, and the molding time was 60 min.

[0032] Comparative Example 5 This comparative example involves the surface treatment of an aluminum alloy substrate. The specific preparation includes the following: the sandblasted 2A14 aluminum alloy substrate is treated by electrolysis with a sulfuric acid concentration of 200 g / L, a voltage of 15 V, a temperature of 20 ℃, and a time of 5 min. After drying, the surface-treated aluminum alloy substrate is obtained with a surface roughness of 5 μm and a surface nanopore size of 33 nm.

[0033] Comparative Example 6 The comparative example relates to surface treatment of an aluminum alloy substrate, and the preparation specifically comprises the following: treating a sandblasted 2A14 aluminum alloy substrate by electrolysis, the sulfuric acid concentration is 200 g / L, the phosphoric acid concentration is 20 g / L, the voltage is 15 V, the temperature is 20 °C, and the time is 8 min, and after drying, the surface-treated aluminum alloy substrate is obtained, the surface roughness is 6 μm, and the surface nanopore size is 38 nm.

[0034] The valve clack drawing performance and the valve clack air leakage pass rate of the aluminum alloy substrate before and after coating of each example and the comparative example are shown in Table 1. Table 1 is the valve clack drawing performance and the valve clack air leakage pass rate of the aluminum alloy substrate before and after coating

[0035] Note: (1) The drawing strength is tested by using a self-made bacteria-shaped tooling, and the sample is prepared by hot pressing, Figure 1 is a physical diagram, the two ends are symmetrical metal T-shaped structures, and the middle is a polytrifluorochloroethylene plastic. The tensile rate is 5 mm / min, which is tested by a universal testing machine.

[0036] (2) The valve clack air leakage experiment is carried out in a liquid nitrogen deep cooling environment, the pressure is 1 MPa, and it is qualified when discontinuous bubbles are generated.

[0037] The above description of the examples is for the purpose of facilitating the understanding and use of the invention by those of ordinary skill in the art. Those skilled in the art can easily make various modifications to these examples, and apply the general principles described herein to other examples without creative labor. Therefore, the present application is not limited to the above examples, and the improvements and modifications made by those skilled in the art without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. A method for multi-scale interface modulation of metal-fluoroplastic bonding force, characterized in that, It consists of the following steps: S1. First, treat the surface of the metal substrate by electrolysis; the electrolyte is at least two of hydrochloric acid, sulfuric acid and phosphoric acid, with hydrochloric acid being a necessary component; the voltage is 10~25 V, the temperature is 10~30 ℃, and the time is 2~10 min. S2. Polychlorotrifluoroethylene is filled into the cavity of the metal substrate treated in S1 by thermoplastic molding.

2. The preparation method for multi-scale interface-controlled metal-fluoroplastic bonding according to claim 1, characterized in that, In step S1, the metal substrate is an aluminum alloy, stainless steel, or titanium alloy.

3. The method for multi-scale interface regulation of metal-fluoroplastic bonding force according to claim 1, characterized in that, In step S1, the electrolyte is hydrochloric acid and sulfuric acid in a molar ratio of 1~3:8~12; or hydrochloric acid, sulfuric acid and phosphoric acid in a molar ratio of 1~3:8~12:1~3.

4. The method for multi-scale interface regulation of metal-fluoroplastic bonding force according to claim 1, characterized in that, The roughness of the metal substrate after step S1 is 5~20 μm, and the surface pore size is 30~100 nm.

5. The method for multi-scale interface regulation of metal-fluoroplastic bonding force according to claim 1, characterized in that, In step S2, the particle size of the polychlorotrifluoroethylene is 20~100 mesh.

6. The method for multi-scale interface regulation of metal-fluoroplastic bonding force according to claim 1, characterized in that, In step S2, the molding temperature of polychlorotrifluoroethylene is 230~250 ℃, the molding pressure is 1~4 MPa, and the molding time is 15~90 min.

7. A metal-fluoroplastic product, characterized in that, It is prepared by the method described in any one of claims 1-6.

8. The metal-fluoroplastic product according to claim 7, characterized in that, The metal-fluoroplastic product is a metal-fluoroplastic low-temperature sealing component.

9. The use of a metal-fluoroplastic article as described in claim 6 or 7 in the manufacture of aerospace valve products.

Images