Corrosion-resistant anti-static composite structure for storage tank and preparation method of corrosion-resistant anti-static composite structure

Abstract

The invention discloses a corrosion-resistant anti-static composite structure for a storage tank and a preparation method of the corrosion-resistant anti-static composite structure, a conductive grid layer is innovatively introduced into the structure, a corrosion-resistant resin coating and a corrosion-resistant anti-static metal coating are arranged at the same time, and by controlling the relative position and the section thickness size of each layer structure, the corrosion-resistant anti-static composite structure is obtained. The bonding strength of the anti-corrosion and anti-static structure and the storage tank base body can be improved, the problem that the anti-static performance of a traditional anti-static structure is low due to the fact that conductive filler is not evenly dispersed or abraded can be solved, and the anti-corrosion and anti-static storage tank has excellent, lasting and reliable anti-corrosion performance and anti-static performance; in the preparation process, by controlling the operation process and related parameters and increasing the modification process, the combination effect between the layers in the composite structure is further enhanced, and a conductive network path with excellent charge transfer capacity is constructed, so that the composite structure has high corrosion resistance and antistatic performance and long service life.

Description

Technical Field

[0001] The present invention relates to the field of corrosion-resistant and antistatic storage tanks, and in particular to a corrosion-resistant and antistatic composite structure for storage tanks and a preparation method thereof. Background Art

[0002] As core equipment for modern industrial storage, transportation, and use, corrosion-resistant and anti-static storage tanks play an irreplaceable role in the petroleum, chemical, and environmental protection sectors. In the petrochemical sector, storage tanks are exposed to corrosive media such as high-sulfur crude oil, strong acids, and alkalis for extended periods. Ordinary materials are susceptible to localized corrosion, such as perforations in the tank bottom and corrosion in welds, leading to leakage risks and significant losses. Furthermore, during storage, transportation, and use, the flow of materials within the tanks can easily generate static electricity. Failure to quickly dissipate static electricity within the tanks can easily lead to explosions.

[0003] Currently, mainstream anti-corrosion methods include coating the surface of storage tanks with organic coatings such as epoxy resin and polyurethane, as well as newer materials such as epoxy antistatic oil tank paint. These coatings form a dense film to isolate corrosive media. Furthermore, conductive fillers such as carbon fiber, graphite, and carbon nanotubes are added to eliminate static electricity. However, these anti-corrosion and anti-static methods are prone to failure, high maintenance costs, and degradation of anti-static performance. Long-term exposure to high temperatures, high salt concentrations, or strong acid and alkali environments can lead to cracking and flaking of the coating, accelerating localized corrosion. Temperature fluctuations cause water vapor to condense, forming a liquid film containing corrosive substances, which also accelerates tank roof corrosion. Furthermore, uneven dispersion or wear of the conductive filler can cause the anti-static performance to deteriorate over time, necessitating frequent maintenance. The development of highly reliable, long-lasting, corrosion-resistant, and anti-static coating structures for storage tanks is crucial for ensuring industrial safety and improving production efficiency.

[0004] It should be noted that the information disclosed in the background section is only used to understand the background of the present application. Therefore, the background section of the present invention may include background information about the problem or environment of the present invention, but does not necessarily describe the prior art. Therefore, the content included in the background section does not constitute an admission by the applicant of prior art. Summary of the Invention

[0005] The purpose of the present invention is to overcome one or more deficiencies in the prior art and to provide a novel corrosion-resistant and antistatic composite structure for storage tanks, which has both excellent antistatic and corrosion resistance, and has a long service life and strong reliability.

[0006] The present invention also provides a method for preparing the above-mentioned corrosion-resistant and antistatic composite structure for a storage tank.

[0007] The present invention also provides a corrosion-resistant and antistatic storage tank comprising the above-mentioned corrosion-resistant and antistatic composite structure for a storage tank.

[0008] In order to achieve the above object, a technical solution adopted by the present invention is:

[0009] A corrosion-resistant and antistatic composite structure for a storage tank, the composite structure comprising a storage tank base layer, a conductive mesh layer disposed on the storage tank base layer and having a plurality of void structures, a corrosion-resistant resin coating, and a corrosion-resistant and antistatic metal coating;

[0010] The corrosion-resistant resin coating is at least filled in the void structure, and the bottom of the corrosion-resistant resin coating is at least covered on the tank base layer, and the upper surface is lower than the upper surface of the conductive grid layer;

[0011] The corrosion-resistant and antistatic metal coating is respectively provided on the conductive grid layer and the corrosion-resistant resin coating;

[0012] The thickness of the portion of the corrosion-resistant antistatic metal coating located on the conductive grid layer is a first thickness, and the thickness of the portion of the corrosion-resistant antistatic metal coating located on the corrosion-resistant resin coating is a second thickness, and the first thickness is less than the second thickness.

[0013] In some embodiments of the present invention, the base layer of the storage tank is made of stainless steel.

[0014] According to some specific aspects of the present invention, the conductive grid layer is composed of conductive metal wires, and the material of the conductive metal wires is stainless steel, nickel, nickel alloy or tantalum.

[0015] Furthermore, the diameter of the conductive metal wire is 10-1000 μm. Furthermore, the diameter of the conductive metal wire is 10-100 μm. In the present invention, if the diameter of the conductive metal wire is too thick, the following adverse effects will occur: (1) the weight of the tank body will increase significantly, making lightweight design inconvenient; (2) the intermediate corrosion-resistant layer will not be well bonded to the conductive metal grid; and (3) the material cost will increase.

[0016] In some embodiments of the present invention, the thickness of the conductive grid layer is 20-500 μm.

[0017] According to some specific aspects of the present invention, the first thickness is 10-100 μm smaller than the second thickness.

[0018] In some preferred embodiments of the present invention, the corrosion-resistant resin coating is a polytetrafluoroethylene coating.

[0019] Furthermore, the raw materials of the polytetrafluoroethylene coating include polytetrafluoroethylene and selective conductive fillers, and the conductive fillers are a combination of one or more selected from graphite, carbon fiber, carbon nanotubes and graphene.

[0020] In some embodiments of the present invention, the corrosion-resistant resin coating has a thickness of 10-490 μm.

[0021] According to some specific aspects of the present invention, the corrosion-resistant and antistatic metal coating is a tantalum metal coating.

[0022] In some embodiments of the present invention, the corrosion-resistant and antistatic metal coating has a thickness of 1-20 μm.

[0023] Another technical solution provided by the present invention is a method for preparing the above-mentioned corrosion-resistant and antistatic composite structure for storage tanks, the preparation method comprising:

[0024] (1) Under the protection of a protective gas, a conductive metal wire is welded to a base layer of a storage tank by a welding method to form a conductive mesh layer having a plurality of void structures, thereby obtaining a first intermediate; wherein, during the welding process, 70% to 90% of the welding energy is supplied to the base layer of the storage tank;

[0025] (2) surface-treating the first intermediate with a modifier solution to obtain a second intermediate; wherein the modifier solution comprises a solvent and naphthalene, sodium, hydrogen fluoride and / or an alkali metal fluoride salt respectively dispersed in the solvent;

[0026] (3) spraying polytetrafluoroethylene on the second intermediate, sintering and curing to form a corrosion-resistant resin coating to obtain a third intermediate;

[0027] (4) Tantalum is sprayed onto the third intermediate by a thermal spraying method to obtain the corrosion-resistant and antistatic composite structure for the storage tank.

[0028] In some embodiments of the present invention, in step (1), before welding, the surface of the conductive metal wire and the surface of the storage tank base layer are cleaned separately. Furthermore, the cleaning method adopts a solution method or an ultrasonic method. The solution method cleaning can include but is not limited to using one or more of acetone, alcohol, and an alkaline solution. The alkaline solution can be an aqueous solution of an alkali metal hydroxide.

[0029] In some embodiments of the present invention, in step (1), before welding, the surface of the base layer of the storage tank is roughened by sandblasting or chemical etching.

[0030] Furthermore, the sandblasting method uses aluminum oxide and / or silicon carbide sand particles to increase surface roughness, improve the bonding strength of subsequent coatings, and simultaneously remove the oxide layer on the surface of the tank body to enhance the electrical conductivity of the tank body.

[0031] Furthermore, the particle sizes of the aluminum oxide and silicon carbide sand particles are 60-200 meshes respectively, and the roughness of the surface of the storage tank base layer after roughening is 1.0-20.0 μm.

[0032] According to some specific and preferred aspects of the present invention, in step (1), the welding method includes resistance spot welding and / or laser welding.

[0033] Furthermore, when laser welding is used as the welding method, the power of the laser welding is 1.0-8.0 kW, the pulse energy is 5-100 J, and the welding speed is 0.1-9.0 m / min.

[0034] Furthermore, when the welding method adopts resistance spot welding, the welding current is 1-10 kA, the welding time is 5-100 ms, and the electrode pressure is 0.1-1.5 kN.

[0035] According to some preferred aspects of the present invention, in step (2), the modifier solution contains 40-80 g of naphthalene, 5-12 g of sodium, and the mass percentage of hydrogen fluoride and / or alkali metal fluoride salt in the modifier solution is 1%-10%, based on 200-600 mL of solvent.

[0036] According to some preferred aspects of the present invention, in step (2), the naphthalene is sublimed naphthalene, the sodium is metallic sodium with a radial size of less than 5 mm, the alkali metal fluoride salt is sodium fluoride, and the solvent is tetrahydrofuran.

[0037] In some embodiments of the present invention, in step (2), the first intermediate is cleaned before the surface treatment is performed.

[0038] In some embodiments of the present invention, in step (2), a plasma method is used instead of a modifier solution for treatment, or a modifier solution and a plasma method are used separately for treatment.

[0039] In some embodiments of the present invention, in step (3), the sintering and curing process is as follows: pre-drying at 50-160°C for 5-40 minutes; then maintaining at 180-300°C for 5-30 minutes; raising to 350-450°C and keeping warm for 5-30 minutes.

[0040] According to some preferred aspects of the present invention, before spraying tantalum, the upper surface of the conductive grid layer in the third intermediate body is controlled to be exposed.

[0041] According to some preferred aspects of the present invention, in step (4), preheating is performed before the thermal spraying, and the preheating temperature is 60-200°C.

[0042] According to some preferred aspects of the present invention, in step (4), the operating parameters of the thermal spraying are: the thermal spraying main gas is argon, the flow rate is 20-100 L / min, the thermal spraying secondary gas is hydrogen, the flow rate is 5-50 L / min, the current is 300-800 A, the voltage is 30-100 V, the power is controlled at 20-85 kW, the spraying distance is 50-260 mm, and the tantalum powder feeding rate is 10-80 g / min.

[0043] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0044] The present invention innovatively provides a new type of corrosion-resistant and antistatic composite structure for storage tanks. The structure innovatively introduces a conductive grid layer, and simultaneously and sequentially arranges a corrosion-resistant resin coating and a corrosion-resistant and antistatic metal coating, and controls their relative position relationship and arrangement method, so that the corrosion resistance and antistatic performance of the present invention are both durable and reliable, and are relatively excellent, and are not prone to falling off. It can also avoid the problem of uniform dispersion or wear of the conductive filler causing a decrease in antistatic performance.

[0045] At the same time, the present invention further provides a preparation method for the above-mentioned corrosion-resistant and antistatic composite structure. When the conductive mesh layer is prepared by welding with a conductive metal wire, the preparation method tends to supply welding energy to make the surface layer of the tank base layer melt quickly while the conductive metal wire only slightly melts and locally diffuses slightly. On the one hand, it can ensure the welding effect of the two, and on the other hand, it can avoid damage to the conductive metal wire. Especially when the polytetrafluoroethylene coating is used as the corrosion-resistant resin coating, the first intermediate is first surface-treated with a specific modifier solution. After the treatment with the modifier solution, a film layer containing fluoride ions, sodium and naphthalene can be formed on the surface of the first intermediate, so that the surface metal oxide can be reduced by covering with fluoride ions. The sodium-naphthalene combination can be used to treat the subsequently sprayed polytetrafluoroethylene coating (the combination of sodium-naphthalene can destroy the structure of polytetrafluoroethylene, such as destroying the carbon-fluorine bond, increasing the surface adhesion effect, etc.), thereby improving the adhesion effect of the subsequent polytetrafluoroethylene coating on the tank base layer and the conductive grid layer. In particular, the void structure of the conductive grid layer itself also has a limiting effect on the polytetrafluoroethylene structure, and the bonding force is better. Afterwards, the present invention innovatively introduces a tantalum coating, which not only has excellent corrosion resistance, but also can form an excellent conductive path with the conductive grid layer, thereby improving the antistatic effect. At the same time, when the hot tantalum metal first contacts the resin, the resin will be softened or deformed to a certain extent, thereby improving the bonding strength between the two.

[0046] In summary, the present invention introduces various functional layers so that they support and cooperate with each other, thereby achieving a highly reliable, long-life, corrosion-resistant and anti-static composite structure that can be used in storage tanks. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0048] Figure 1 Schematic front view of a corrosion-resistant and antistatic composite structure for a storage tank according to an embodiment of the present invention;

[0049] Figure 2 Schematic cross-sectional view of a corrosion-resistant and antistatic composite structure for a storage tank according to an embodiment of the present invention;

[0050] In the accompanying drawings: 1. tank base layer; 2. conductive mesh layer; 3. corrosion-resistant resin coating; 4. corrosion-resistant antistatic metal coating. DETAILED DESCRIPTION

[0051] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments. The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0052] In the description of the present invention, “a plurality of” means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0053] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0054] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0055] See also Figures 1 to 2 As shown, this example provides a corrosion-resistant and antistatic composite structure for a storage tank, which includes a storage tank base layer 1, a conductive mesh layer 2 arranged on the storage tank base layer 1 and having multiple void structures, a corrosion-resistant resin coating 3 and a corrosion-resistant antistatic metal coating 4; the corrosion-resistant resin coating 3 is at least filled in the void structure, and the bottom of the corrosion-resistant resin coating 3 at least covers the storage tank base layer 1, and the upper surface is lower than the upper surface of the conductive mesh layer 2; the corrosion-resistant antistatic metal coating 4 is respectively arranged on the conductive mesh layer 2 and the corrosion-resistant resin coating 3; the thickness of the portion of the corrosion-resistant antistatic metal coating 4 located on the conductive mesh layer 2 is a first thickness, and the thickness of the portion of the corrosion-resistant antistatic metal coating 4 located on the corrosion-resistant resin coating 3 is a second thickness, and the first thickness is less than the second thickness.

[0056] The base layer 1 of the storage tank is usually made of metal, such as stainless steel, which has good corrosion resistance.

[0057] The conductive mesh layer 2 is composed of conductive metal wires. A single long or multiple short conductive metal wires are welded to the tank base layer 1 in a predetermined shape to form a conductive mesh layer 2 having multiple void structures. The void structures in the conductive mesh layer 2 can have cross-sectional shapes such as square, circular, elliptical, or triangular. The orthographic projection areas of the individual void structures on the tank base layer 1 can be the same or different, but in this example, they are substantially the same. Constructing the conductive mesh layer 2 from conductive metal wires provides excellent support for other coatings included in the composite structure and acts as a limiter, enhancing overall bonding strength. The resulting conductive network provides excellent electrical conductivity, thereby improving antistatic properties.

[0058] The conductive metal wire is made of stainless steel, nickel, nickel alloy, or tantalum, and may also be other metal materials with good electrical conductivity and good corrosion resistance. Furthermore, the conductive metal wire has a diameter of 10-100 μm, for example, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, etc. The thickness of the conductive grid layer is 20-500μm, for example, it can be 20μm, 50μm, 80μm, 100μm, 120μm, 145μm, 150μm, 160μm, 180μm, 200μm, 210μm, 230μm, 300μm, 320μm, 350μm, 400μm, 410μm, 440μm, 450μm, 470μm, etc.

[0059] The upper surface of the corrosion-resistant resin coating 3 is lower than the upper surface of the conductive mesh layer 2, that is, the upper surface of the conductive mesh layer 2 is exposed to the outside, which is convenient for contacting and combining with the subsequent corrosion-resistant antistatic metal coating 4 to construct a better conductive path. The first thickness is 10-100 μm smaller than the second thickness, that is, the upper surface of the corrosion-resistant resin coating 3 is about 10-100 μm lower than the upper surface of the conductive mesh layer 2 (for example, it can be 10 μm, 12 μm, 13 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, etc.), which can also help the corrosion-resistant antistatic metal coating 4 form a protrusion extending into the void structure of the conductive grid layer 2, and the protruding part is combined with the corrosion-resistant resin coating 3 in the void structure, which greatly improves the bonding force between the functional structures, so that the tank base layer 1, the conductive grid layer 2, the corrosion-resistant resin coating 3 and the corrosion-resistant antistatic metal coating 4 form a tightly combined whole, thereby improving durability and reliability. Further, the first thickness is 1-20μm, for example, it can be 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 12μm, 13μm, 15μm, 16μm, 17μm, 18μm, 19μm, etc.

[0060] The corrosion-resistant resin coating 3 is a polytetrafluoroethylene coating. Furthermore, the raw materials of the polytetrafluoroethylene coating include polytetrafluoroethylene and a selective conductive filler, and the conductive filler is a combination of one or more selected from graphite, carbon fiber, carbon nanotubes, and graphene. The thickness of the corrosion-resistant resin coating is 10-490 μm, for example, 10 μm, 50 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, 220 μm, 250 μm, 260 μm, 3000 μm, 310 μm, 330 μm, 350 μm, 380 μm, 400 μm, 420 μm, 430 μm, 440 μm, etc.

[0061] The corrosion-resistant and antistatic metal coating 4 is a tantalum metal coating. Tantalum is a metal element with an atomic number of 73 and a chemical symbol of Ta. The corresponding element is a steel-gray metal. Tantalum has a very small thermal expansion coefficient and very excellent chemical properties. It has extremely high corrosion resistance. Whether under cold or hot conditions, it does not react with hydrochloric acid, concentrated nitric acid and aqua regia. Therefore, in this example, it is used as the outermost layer that directly contacts the material inside the tank body, that is, tantalum is made into a tantalum metal coating to attach to the conductive grid layer 2 and the corrosion-resistant resin coating 3 to serve as the first line of corrosion resistance. At the same time, due to the good conductivity of tantalum, it directly forms a good conductive network path after contacting the conductive grid layer 2, thereby improving the charge transfer ability and thus improving the antistatic ability.

[0062] This example also provides a method for preparing the above-mentioned corrosion-resistant and antistatic composite structure for a storage tank, the preparation method comprising:

[0063] (1) Under the protection of a protective gas, a conductive metal wire is welded to a base layer of a storage tank by a welding method to form a conductive mesh layer having a plurality of void structures, thereby obtaining a first intermediate; wherein, during the welding process, 70% to 90% of the welding energy is supplied to the base layer of the storage tank;

[0064] (2) surface-treating the first intermediate with a modifier solution to obtain a second intermediate; wherein the modifier solution comprises a solvent and naphthalene, sodium, hydrogen fluoride and / or an alkali metal fluoride salt respectively dispersed in the solvent;

[0065] (3) spraying polytetrafluoroethylene on the second intermediate, sintering and curing to form a corrosion-resistant resin coating to obtain a third intermediate;

[0066] (4) Tantalum is sprayed onto the third intermediate by a thermal spraying method to obtain a corrosion-resistant and antistatic composite structure for a storage tank.

[0067] In step (1), before welding, the surface of the conductive metal wire and the surface of the storage tank base layer are cleaned separately. Furthermore, the cleaning method adopts a solution method or an ultrasonic method. The solution method cleaning can include but is not limited to using one or more of acetone, alcohol and alkaline solution. The alkaline solution can be an aqueous solution of alkali metal hydroxide. Cleaning can remove oil, oxides or impurities on the surface, facilitating the subsequent better welding effect.

[0068] In step (1), before welding, the surface of the base layer of the storage tank is roughened by sandblasting or chemical etching. Furthermore, the sandblasting method uses aluminum oxide and / or silicon carbide sand particles to increase the surface roughness, improve the bonding strength of the subsequent coating, and remove the oxide layer on the surface of the tank body to enhance the electrical conductivity of the tank body. Furthermore, the particle size of the aluminum oxide and silicon carbide sand particles is 60-200 mesh, respectively, and the roughness of the surface of the base layer of the storage tank after roughening is 1.0-20.0 μm.

[0069] In step (1), the welding method includes resistance spot welding and / or laser welding. When laser welding is used, the laser welding power is 1.0-8.0 kW, the pulse energy is 5-100 J, and the welding speed is 0.1-9.0 m / min. When resistance spot welding is used, the welding current is 1-10 kA, the welding time is 5-100 ms, and the electrode pressure is 0.1-1.5 kN. During the welding process, the shielding gas used can be argon, helium, or nitrogen, preferably high-purity argon. In this example, parameter control is more important to achieve good welding results.

[0070] Furthermore, in step (1), during the welding process, 70%-90% of the welding energy is supplied to the base layer of the storage tank. The supply method of the welding energy can be operated according to conventional methods and is not specifically limited here. In this way, the surface layer of the base layer of the storage tank (made of stainless steel) can be preferentially melted quickly while the conductive metal wire is only slightly melted and slightly diffused. When the two are welded together, not only is the welding firmness guaranteed, but the thinner conductive metal wire is also well protected, avoiding damage or unexpected damage or deformation of the thinner conductive metal wire.

[0071] In step (2), in the modifier solution, in solvent 200-600mL, naphthalene is 40-80g, and sodium is 5-12g, and the mass percentage composition that hydrogen fluoride and / or alkali metal fluoride salt account for modifier solution is 1%-10% (for example, can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5% etc.). Further, naphthalene is sublimed naphthalene, and sodium is the sodium Metal 99.9 that radial dimension is less than 5mm, for example, can select the sodium Metal 99.9 block that radial dimension is about 2-3mm, and alkali metal fluoride salt is sodium fluoride, and solvent can be tetrahydrofuran (THF) etc. In this example, by spraying the modifier solution on the surface of the first intermediate, a modified layer containing fluoride ions, sodium and naphthalene can be obtained on the surface of the first intermediate. On the one hand, the presence of fluoride ions can prevent the surface metal of the first intermediate from being oxidized, reduce the formation of surface oxides, and thus ensure the conductive effect. On the other hand, the simultaneous presence of sodium and naphthalene, when subsequent polytetrafluoroethylene is sprayed onto this modified layer, can destroy the carbon-fluorine bond (CF bond) on the surface of the polytetrafluoroethylene resin, thereby improving its surface properties, that is, improving the adhesion performance of the polytetrafluoroethylene surface, improving the bonding ability between the resin and the metal, and improving the stability of the overall structure.

[0072] The preparation method of the modifier solution comprises: dispersing naphthalene in a solvent such as tetrahydrofuran under protective gas protection, adding sodium, hydrogen fluoride and / or alkali metal fluoride salt after uniform dispersion, mixing and dispersing, and placing at room temperature for standby use.

[0073] In step (2), before surface treatment, the first intermediate is cleaned. The cleaning method can be the same as the cleaning before welding in step (1), mainly to remove impurities such as grease and oxides on the surface.

[0074] As an optional embodiment, in step (2), a plasma method is used instead of a modifier solution for treatment, or a modifier solution and a plasma method are used for treatment respectively. Plasma treatment can also improve the surface wettability and bonding strength of the conductive metal wire and the tank base layer to a certain extent.

[0075] In step (3), the method for spraying polytetrafluoroethylene on the second intermediate can adopt a conventional spraying method. For example, polytetrafluoroethylene, water and a wetting agent (such as polyvinyl alcohol (PVA), acetylene glycol, etc.) can be pre-configured into a polytetrafluoroethylene dispersion, and the mass content of polytetrafluoroethylene in the polytetrafluoroethylene dispersion is controlled to be 15%-85%, and the mass content of the wetting agent is controlled to be 0.1%-5%; then, a spray gun with a diameter of approximately 0.5-2.5 mm is used to spray the polytetrafluoroethylene dispersion on the surface of the second intermediate. The thickness of a single layer can be controlled to be 5-50 μm, and multiple sprayings can be performed according to the required thickness;

[0076] Electrostatic spraying may also be used. For example, polytetrafluoroethylene powder with a particle size of about 10-100 μm may be prepared and then sprayed using a conventional electrostatic spraying method.

[0077] In step (3), the sintering and curing process is as follows: pre-drying at 50-160°C for 5-40 minutes; then maintaining at 180-300°C for 5-30 minutes; then heating to 350-450°C and maintaining for 5-30 minutes. Pre-drying removes solvents and moisture, and then heating to melt the polytetrafluoroethylene powder particles. Finally, high-temperature treatment promotes molecular chain entanglement to form a dense, corrosion-resistant layer.

[0078] In actual operation, before spraying tantalum, the upper surface of the conductive mesh layer in the third intermediate is controlled to be exposed. For example, during the process of spraying polytetrafluoroethylene, the conductive mesh layer is also covered with polytetrafluoroethylene. In order to ensure direct contact between the tantalum and the conductive metal wires of the conductive mesh layer, it is preferred to expose the conductive mesh layer so that it is not covered by polytetrafluoroethylene. For example, the upper surface of the conductive mesh layer can be polished by a process such as grinding, using tools such as sandpaper, until the upper surface of the conductive mesh layer is completely exposed. The surface dirt is then cleaned and removed. The polished surface can be cleaned with deionized water and / or alcohol.

[0079] In step (4), preheating is performed before thermal spraying, and the preheating temperature is 60-200°C, for example, 60-80°C, 90-100°C, 110-130°C, 140-160°C, 180-200°C, etc.

[0080] In step (4), the operating parameters of thermal spraying are: the main gas for thermal spraying is argon, the flow rate is 20-100 L / min, the secondary gas for thermal spraying is hydrogen, the flow rate is 5-50 L / min, the current is 300-800 A, the voltage is 30-100 V, the power is controlled at 20-85 kW, the spraying distance is 50-260 mm, and the tantalum powder feeding rate is 10-80 g / min.

[0081] Application Case 1:

[0082] Prepare as above Figures 1 to 2 The corrosion-resistant and antistatic composite structure for storage tanks shown in the figure is prepared in the following process:

[0083] (1) Using acetone, alcohol and a 10% sodium hydroxide aqueous solution, the surface of the conductive metal wire and the surface of the tank base layer were cleaned in sequence;

[0084] The surface of the tank base layer is roughened by sandblasting, and the roughness after treatment is about 3μm;

[0085] The shielding gas is high-purity argon gas with a purity of more than 99.5%. During the welding process, most of the welding energy is supplied to the base layer of the storage tank, causing the surface layer of the stainless steel base layer of the storage tank to melt rapidly while the conductive metal wire (tantalum wire with a diameter of approximately 50 μm) only slightly melts and diffuses. The conductive metal wire is then welded together to form a conductive mesh layer with a thickness of approximately 100 μm and a plurality of void structures, thereby obtaining a first intermediate.

[0086] Laser welding is used, with a power of approximately 2.5kW, a pulse energy of 50J, and a welding speed of 0.5m / min;

[0087] (2) In the modifier solution, based on 500 mL of tetrahydrofuran solvent, 50 g of naphthalene, 8 g of sodium, and the mass percentage of sodium fluoride in the modifier solution are 2.5%;

[0088] (3) spraying polytetrafluoroethylene powder having an average particle size of about 60 μm onto the second intermediate by electrostatic spraying;

[0089] The sintering and curing process is as follows: pre-drying at 120°C for 25 minutes; then maintaining at 260°C for 15 minutes; raising to 400°C and maintaining for 25 minutes;

[0090] The polytetrafluoroethylene on the upper surface of the conductive grid layer is polished and removed, and then cleaned to obtain a polytetrafluoroethylene coating with a thickness of about 90 μm;

[0091] (4) Clean the polished surface with deionized water and alcohol solution to remove dirt and impurities;

[0092] The preheating temperature is about 95℃;

[0093] The thermal spraying operating parameters are as follows: the main thermal spraying gas is argon with a flow rate of 80L / min, the secondary thermal spraying gas is hydrogen with a flow rate of 10L / min, the current is 400A, the voltage is 60V, the power is controlled at 50kW, the spraying distance is 80mm, and the tantalum powder feeding rate is 30g / min;

[0094] The first thickness is 20 μm, and the second thickness is 30 μm.

[0095] Application Comparative Example 1:

[0096] The same as Application Case 1, the only difference is that step (2) is omitted.

[0097] Application Comparative Example 2:

[0098] The same as Application Case 1, the only difference is that step (4) is omitted.

[0099] Performance testing:

[0100] The composite structures obtained from the above-mentioned application case 1 and application comparative examples 1-2 were subjected to the following performance tests, and the specific results are shown in Table 1.

[0101] Table 1

[0102]

[0103] Note: (1) The conductivity requirement of anti-static storage tanks in international standards is: 1×10 -9 ~1×10 -5 , the initial conductivity of Comparative Example 2 does not meet the requirements directly.

[0104] (2) Conductivity test standard: IEC61340-5-1.

[0105] (3) Corrosion current density test standard: GB / T 24196-2009.

[0106] (4) Calculation method of theoretical service life:

[0107] (A) Assume that the conductivity decreases by 0.15 to 0.2 orders of magnitude per year;

[0108] (B)8.6×10 -9 Reduced to 1×10 -9 , about 0.93 orders of magnitude (subtracting the logarithmic values ​​with base 10), the theoretical service life is 4.7 to 6.2 years (taking 5 years) according to theoretical calculation;

[0109] (C)5.2×10 -6 Reduced to 1×10 -9 , about 3.7 orders of magnitude (subtracting the logarithmic values ​​with base 10), and the theoretical service life is obtained by theoretical calculation to be 18.5 to 24.7 years (taking 20 years).

[0110] As mentioned throughout the specification and claims, "comprising" is an open term and should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem and basically achieve the technical effect. It should also be noted that the terms "comprising", "including" or any other variants thereof are intended to cover non-exclusive inclusion, so that a product or system including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also includes elements that are inherent to such product or system. In the absence of further restrictions, the elements defined by the sentence "comprising one" do not exclude the existence of other identical elements in the product or system including the elements.

[0111] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

[0112] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

Claims

1. A corrosion-resistant and antistatic composite structure for a storage tank, characterized in that: The composite structure includes a storage tank base layer, a conductive grid layer provided on the storage tank base layer and having a plurality of void structures, a corrosion-resistant resin coating and a corrosion-resistant antistatic metal coating; The corrosion-resistant resin coating is at least filled in the void structure, and the bottom of the corrosion-resistant resin coating is at least covered on the tank base layer, and the upper surface is lower than the upper surface of the conductive grid layer; The corrosion-resistant and antistatic metal coating is respectively provided on the conductive grid layer and the corrosion-resistant resin coating; The thickness of the portion of the corrosion-resistant antistatic metal coating located on the conductive grid layer is a first thickness, and the thickness of the portion of the corrosion-resistant antistatic metal coating located on the corrosion-resistant resin coating is a second thickness, and the first thickness is less than the second thickness.

2. The corrosion-resistant and antistatic composite structure for a storage tank according to claim 1, characterized in that: The material of the base layer of the storage tank is stainless steel; and / or the conductive grid layer is composed of conductive metal wires, the material of the conductive metal wires is stainless steel, nickel, nickel alloy or tantalum, and the diameter of the conductive metal wires is 10-100μm; and / or the thickness of the conductive grid layer is 20-500μm; and / or the first thickness is 10-100μm smaller than the second thickness.

3. The corrosion-resistant and antistatic composite structure for a storage tank according to claim 1, characterized in that: The corrosion-resistant resin coating adopts a polytetrafluoroethylene coating, the raw materials of the polytetrafluoroethylene coating include polytetrafluoroethylene and selective conductive fillers, and the conductive fillers are a combination of one or more selected from graphite, carbon fiber, carbon nanotubes and graphene; and / or the thickness of the corrosion-resistant resin coating is 10-490 μm.

4. The corrosion-resistant and antistatic composite structure for a storage tank according to claim 1, characterized in that: The corrosion-resistant and antistatic metal coating is a tantalum metal coating; and / or the first thickness is 1-20 μm.

5. A method for preparing the corrosion-resistant and antistatic composite structure for a storage tank according to any one of claims 1 to 4, characterized in that: The preparation method comprises: (1) Under the protection of a protective gas, a conductive metal wire is welded to a base layer of a storage tank by a welding method to form a conductive mesh layer having a plurality of void structures, thereby obtaining a first intermediate; wherein, during the welding process, 70% to 90% of the welding energy is supplied to the base layer of the storage tank; (2) surface-treating the first intermediate with a modifier solution to obtain a second intermediate; wherein the modifier solution comprises a solvent and naphthalene, sodium, hydrogen fluoride and / or an alkali metal fluoride salt respectively dispersed in the solvent; (3) spraying polytetrafluoroethylene on the second intermediate, sintering and curing to form a corrosion-resistant resin coating to obtain a third intermediate; (4) Tantalum is sprayed onto the third intermediate by a thermal spraying method to obtain the corrosion-resistant and antistatic composite structure for the storage tank.

6. The method for preparing the corrosion-resistant and antistatic composite structure for a storage tank according to claim 5, characterized in that: In step (1), before welding, the surface of the conductive metal wire and the surface of the storage tank base layer are cleaned respectively; and / or, in step (1), before welding, the surface of the storage tank base layer is roughened by sandblasting or chemical etching.

7. The method for preparing the corrosion-resistant and antistatic composite structure for a storage tank according to claim 5, characterized in that: In step (1), the welding method includes resistance spot welding and / or laser welding; When the welding method adopts laser welding, the power of laser welding is 1.0-8.0kW, the pulse energy is 5-100J, and the welding speed is 0.1-9.0m / min; When resistance spot welding is used as the welding method, the welding current is 1-10 kA, the welding time is 5-100 ms, and the electrode pressure is 0.1-1.5 kN.

8. The method for preparing the corrosion-resistant and antistatic composite structure for a storage tank according to claim 5, characterized in that: In step (2), in the modifier solution, based on 200-600 mL of solvent, naphthalene is 40-80 g, sodium is 5-12 g, and the mass percentage of hydrogen fluoride and / or alkali metal fluoride salt in the modifier solution is 1%-10%; and / or, In step (2), the naphthalene is sublimed naphthalene, the sodium is metallic sodium having a radial dimension less than 5 mm, the alkali metal fluoride is sodium fluoride, and the solvent is tetrahydrofuran; and / or, In step (2), before performing the surface treatment, the first intermediate is cleaned; and / or, In step (2), a plasma method is used instead of a modifier solution for treatment, or a modifier solution and a plasma method are used separately for treatment.

9. The method for preparing the corrosion-resistant and antistatic composite structure for a storage tank according to claim 5, characterized in that: In step (3), the sintering and curing process is as follows: pre-drying at 50-160°C for 5-40 minutes; then maintaining at 180-300°C for 5-30 minutes; raising to 350-450°C and keeping warm for 5-30 minutes; and / or, Before spraying tantalum, the upper surface of the conductive grid layer in the third intermediate body is controlled to be exposed.

10. The method for preparing the corrosion-resistant and antistatic composite structure for storage tanks according to claim 5, characterized in that: In step (4), before the thermal spraying is performed, preheating is performed, and the preheating temperature is 60-200°C; and / or, in step (4), the operating parameters of the thermal spraying are: the main gas for thermal spraying is argon, the flow rate is 20-100L / min, the secondary gas for thermal spraying is hydrogen, the flow rate is 5-50L / min, the current is 300-800A, the voltage is 30-100V, the power is controlled at 20-85kW, the spraying distance is 50-260mm, and the tantalum powder feeding rate is 10-80g / min.

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