A kind of nuclear radiation resistant heat insulation protective coating for steam pipeline and its preparation method

Abstract

The invention discloses a nuclear radiation resistant heat-insulating protective coating for steam pipelines and a preparation method thereof. The coating comprises a surface layer and a bottom layer; the surface layer comprises 30 to 50 parts of a surface layer base, 10 to 30 parts of pigments and fillers, 5-10 parts of metal powder, 18 to 20 parts of a curing agent and 18 to 20 parts of a diluent; the bottom layer comprises 10 to 30 parts of a bottom layer base, 30 to 50 parts of pigments and fillers, 5-10 parts of metal powder, 18 to 20 parts of a curing agent and 18 to 20 parts of a diluent; wherein the surface layer base comprises acrylic modified organic silicon resin; the bottom layer base comprises water glass; the pigments and fillers comprise enamel powder, ceramics and auxiliary fillers; the auxiliary fillers comprise one or more of mica, iron oxide, zinc titanate, fluoropolymer and borosilicate; the coating of the invention can effectively insulate and protect the steam pipeline in a high temperature and nuclear radiation environment, thereby extending the service life of the steam pipeline and improving the safety and reliability of the nuclear power plant.

Description

Technical Field

[0001] The invention belongs to the technical field of material engineering, and in particular relates to a nuclear radiation resistant heat insulation protective coating for steam pipelines and a preparation method thereof. Background Art

[0002] During the operation of nuclear power plants, steam pipelines are subjected to a complex environment of high-temperature steam and nuclear reaction products (i.e., nuclear radiation). These pipelines operate under high-temperature conditions, so effective thermal insulation protection is required to prevent heat transfer to the surrounding environment and ensure the stability of the pipeline structure. In addition, the radiation generated in nuclear reactions also poses a challenge to pipeline materials, which may cause degradation, deformation, or even damage to the materials.

[0003] Traditional thermal insulation coatings usually perform well in high-temperature environments, but their performance will be affected under the influence of nuclear radiation because radiation can cause changes in the molecular structure of the coating, thereby losing its original properties, resulting in a decrease in its thermal insulation performance and even a loss of effective protection against nuclear radiation.

[0004] Based on this, it is extremely urgent to develop a new type of pipeline thermal insulation coating that can function stably in high temperature and nuclear radiation environments. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a nuclear radiation resistant thermal insulation protective coating for steam pipelines and a preparation method thereof, which can provide excellent thermal insulation and radiation protection effects under high temperature (260-300°C) and nuclear irradiation environment to ensure the long-term stable operation and safety of the pipeline.

[0006] The present invention is achieved through the following technical solutions:

[0007] A nuclear radiation resistant heat insulation protective coating for steam pipelines, comprising a surface layer and a bottom layer;

[0008] The surface layer comprises the following components in parts by weight:

[0009] 30~50 parts of surface base, 10~30 parts of pigments and fillers, 5-10 parts of metal powder, 18~20 parts of curing agent and 18~20 parts of diluent;

[0010] The bottom layer comprises the following components in parts by weight:

[0011] 10~30 parts of base material, 30~50 parts of pigments and fillers, 5-10 parts of metal powder, 18~20 parts of curing agent and 18~20 parts of diluent;

[0012] Wherein, the surface layer substrate comprises acrylic modified silicone resin; the bottom layer substrate comprises water glass;

[0013] The pigments and fillers include enamel powder, ceramics and auxiliary fillers;

[0014] The auxiliary filler includes one or more of mica, iron oxide, zinc titanate, fluoropolymer and borosilicate.

[0015] As some possible implementation methods of the present application, in the surface layer, the mass ratio of enamel powder, ceramics and auxiliary fillers in the color filler is 5~10:5~11:8~20.

[0016] As some feasible implementation methods of the present application, in the bottom layer, the mass ratio of enamel powder, ceramics and auxiliary fillers in the color filler is 25~30:15~25:6~15.

[0017] As some possible implementation methods of the present application, the particle size of the ceramic includes three sizes: 10nm~15nm, 50nm~80nm, and 180-210nm.

[0018] As some possible implementation methods of the present application, the ceramics are hollow ceramic microspheres and ceramic particles;

[0019] In the surface layer, the mass ratio of enamel powder, hollow ceramic microspheres, ceramic particles YSZ, mica, iron oxide, zinc titanate, fluoropolymer and borosilicate in the pigment filler is 5-10:5-8:2-3:1-3:1-2:3-5:0.5-1:5-7;

[0020] As some possible implementation methods of the present application, the ceramics are hollow ceramic microspheres and ceramic particles YSZ;

[0021] In the bottom layer, the mass ratio of enamel powder, hollow ceramic microbeads, ceramic particles, mica, iron oxide, zinc titanate, fluoropolymer and borosilicate in the color filler is 25-30:15-20:3-5:1-3:1-2:3-5:0.5-1:1-3.

[0022] As some possible implementation methods of the present application, the metal powder is one or more of Ta and Ti.

[0023] As some possible implementation methods of the present application, the surface layer has a thickness of 100 μm to 1 mm; the bottom layer has a thickness of 1 mm to 1 cm.

[0024] As some feasible implementation methods of the present application, the enamel powder, calculated by mass fraction, includes 61-67% silicon dioxide, 6-11% zirconium dioxide, 3-10% aluminum oxide, 4-9% boron trioxide, 1-7% calcium oxide, 7-13% strontium oxide, and 2-6% potassium oxide. The total content of calcium oxide, strontium oxide and potassium oxide is 16-22%.

[0025] In addition, to achieve the above-mentioned purpose, the present invention also provides a method for preparing a nuclear radiation resistant heat insulation protective coating for a steam pipeline, comprising the following steps:

[0026] S1. The surface layer substrate, pigments, metal powder and diluent are mixed by ball milling, and after being evenly dispersed, a curing agent is added, and after being evenly dispersed, a surface layer coating is obtained; the bottom layer substrate, pigments, metal powder and diluent are mixed by ball milling, and after being evenly dispersed, a curing agent is added, and after being evenly dispersed, a bottom layer coating is obtained;

[0027] S2 The base coating and top coating are sprayed on the workpiece surface in sequence, and a protective coating is obtained after curing at room temperature.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention uses an organic coating as a surface layer and an inorganic coating as a bottom layer to collaboratively prepare a coating with strong corrosion resistance, nuclear radiation resistance, high temperature resistance and thermal insulation performance. The coating can effectively insulate and protect steam pipelines in high temperature and nuclear radiation environments, thereby extending the service life of the steam pipeline and improving the safety and reliability of nuclear power plants.

[0030] The specific properties of the coating of the present invention are as follows:

[0031] The coating of the present invention has excellent resistance to nuclear radiation. 5 After irradiation with γ-rays of 100 Gy, the coating was intact without any peeling or powdering;

[0032] The coating of the present invention has excellent heat insulation performance and can reduce the temperature from 260-300°C to 80°C;

[0033] The coating of the present invention has excellent high temperature resistance and corrosion resistance. The coating does not peel off, powder or other defects when it works continuously for 5000 hours at 260-300°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 : Schematic diagram of the microstructure of the coating of the present invention;

[0035] Figure 2 : Schematic diagram of the microstructure of the coating of the present invention; DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0037] During the operation of nuclear power plants, steam pipelines are subjected to a complex environment of high-temperature steam and nuclear reaction products (i.e., nuclear radiation). These pipelines operate under high temperature conditions, generally 260-300°C, so effective thermal insulation protection is required to prevent heat transfer to the surrounding environment and ensure the stability of the pipeline structure. In addition, the radiation generated in nuclear reactions also poses a challenge to pipeline materials, which may cause degradation, deformation, or even damage to the materials.

[0038] Based on this, the present invention proposes a nuclear radiation resistant heat insulation protective coating for steam pipelines, comprising a surface layer and a bottom layer;

[0039] The surface layer comprises the following components in parts by weight:

[0040] 30~50 parts of surface base, 10~30 parts of pigments and fillers, 5-10 parts of metal powder, 18~20 parts of curing agent and 18~20 parts of diluent;

[0041] The bottom layer comprises the following components in parts by weight:

[0042] 10~30 parts of base material, 30~50 parts of pigments and fillers, 5-10 parts of metal powder, 18~20 parts of curing agent and 18~20 parts of diluent;

[0043] Wherein, the surface layer substrate comprises acrylic modified silicone resin; the bottom layer substrate comprises water glass;

[0044] The pigments and fillers include enamel powder, ceramics and auxiliary fillers;

[0045] The auxiliary filler includes one or more of mica, iron oxide, zinc titanate, fluoropolymer and borosilicate.

[0046] The fluoropolymer is (C 2 F 4 ) n The borosilicate refers to borosilicate glass, which is composed mainly of SiO 2 , B 2 O 3 、Na 2 O glass, the basic composition range is: ω (SiO 2 )=70%~80%, ω (B 2 O 3 )=6%~15%, ω(Na 2 O)=4%~10%, ω(Al 2 O 3 )=0~5%, ω(BaO)=0~2%, ω(CaO)=0~2%;

[0047] The water glass refers to a mixture of potassium silicate or sodium silicate, which is in the prior art.

[0048] In actual implementation, the surface layer and the bottom layer also include 0.1-0.5 parts of a dispersant, 0.1-0.5 parts of a defoaming agent and 0.1-0.5 parts of a rheological agent.

[0049] In this solution, the organic coating is used as the surface layer and the inorganic coating is used as the bottom layer. Under the synergistic effect of the two, the overall linear expansion coefficient of the coating can be adjusted, so that the coating is well bonded and has few defects, thereby ensuring that the coating has strong corrosion resistance, nuclear radiation resistance, high temperature resistance and thermal insulation performance. Secondly, the organic coating and inorganic coating selected in the present invention have very good compatibility, such as no problems such as decreased adhesion. Specifically, during high-temperature service, the bonding strength of the inorganic coating of the bottom layer with the substrate increases, while the organic coating of the surface layer softens, degrades or thermally decomposes, resulting in deterioration of its physical and chemical properties, thereby reducing the bonding strength with the substrate. The present invention can effectively overcome the technical defect of decreased bonding strength between the organic coating and the substrate by combining the organic coating and the inorganic coating, thereby improving the bonding between the coating and the substrate. The adhesion test results of the coating of the present invention show that the adhesion of the surface layer is measured using the national standard pull-off method, and the adhesion is 5~6Mpa. The adhesion of the bottom layer is originally 1~3Mpa, which is increased to 3~5Mpa after oxidation. Therefore, the coating of the present invention can significantly improve the adhesion level of the bottom layer under high-temperature service environment, especially at the lower substrate / bottom layer interface and the bottom layer / surface layer interface.

[0050] Specifically, the present invention can effectively improve the temperature resistance, radiation resistance and thermal expansion system of the coating by adding metal powder. The metal powder nanometer metal powder added to the coating system of the present application has very good dispersibility, and will be rapidly oxidized and expand in high temperature environment, so that the coating has self-repair function in harsh high temperature environment; secondly, the metal can adjust the thermal expansion coefficient of the coating at high temperature, so that the coating can avoid cracking or peeling caused by stress at high temperature. Adding enamel powder and ceramics can effectively improve the high temperature resistance and corrosion resistance of the coating; in addition, the pigments and fillers added in the present invention are mostly low thermal conductivity materials, which can effectively improve the thermal insulation performance of the coating.

[0051] Through the synergistic effect of the above components, the prepared coating can have high temperature resistance, nuclear radiation resistance, corrosion resistance and heat insulation performance. In addition, since the coating in the present invention will decompose or volatilize during the high temperature service stage in the nuclear environment, resulting in holes or gaps in the coating, the addition of enamel powder can fill these holes and defects, thereby improving the compactness of the coating.

[0052] Furthermore, since the coating of the present invention is mainly used in steam pipelines with a certain pressure in a nuclear environment, the temperature of the pipeline can reach 260-300°C. Therefore, the present invention focuses on solving the protection problem of steam pipelines at this temperature. The specific performance of the coating is as follows:

[0053] 1.7×10 5 After irradiation with γ-rays of 1000 Gy, the coating is intact without peeling or powdering; the temperature can be reduced from 260-300°C to 80°C to avoid burns to personnel; the coating works continuously for 5000 hours at 260-300°C without peeling, powdering or other defects. This shows that the coating of the present invention has excellent high temperature resistance, nuclear radiation resistance, corrosion resistance and thermal insulation performance, can effectively insulate and protect steam pipelines, thereby extending the service life of steam pipelines and improving the safety and reliability of nuclear power plants.

[0054] In order to further improve the high temperature resistance, nuclear radiation resistance, corrosion resistance and thermal insulation performance of the coating, as some feasible implementation methods of the present application, the amount of each component in the color and filler in the surface layer is further limited, that is, in the surface layer, the mass ratio of enamel powder, ceramics and auxiliary fillers in the color and filler is 5~10:5~11:8~20.

[0055] In order to further improve the high temperature resistance, nuclear radiation resistance, corrosion resistance and thermal insulation performance of the coating, as some feasible implementation methods of the present application, the amount of each component in the pigment and filler in the base layer is further limited, that is, in the base layer, the mass ratio of enamel powder, ceramic and auxiliary filler in the pigment and filler is 25~30:15~25:6~15.

[0056] In order to further improve the high temperature resistance, nuclear radiation resistance, corrosion resistance and thermal insulation performance of the coating, as some feasible implementation methods of the present application, the particle size of the ceramic is further limited, that is, the particle size of the ceramic includes three sizes: 10nm~15nm, 50nm~80nm, and 180-210nm.

[0057] By limiting the size of the spherical ceramic particles, the present invention can design the filler size in the coating from large to small, and can form fine protrusions and depressions on the microscopic level of the coating, thereby forming a three-dimensional buckle size interlocking structure, such as Figure 1 and Figure 2 As shown, it can effectively avoid corrosion and improve the efficiency of heat conduction. Figure 1 The medium spherical filler is mainly ceramic, and the lamellar filler is mainly one or more of the auxiliary fillers.

[0058] Specifically, the specific functions of the dimensional interlocking structure are as follows:

[0059] First, improve density: The dimensional interlocking structure helps to reduce pores and defects in the coating and improve the density of the coating. The dense coating structure can effectively prevent the corrosive medium from penetrating into the substrate and increase the protective performance of the coating.

[0060] Second, increase the surface area of ​​the coating: By increasing the concave-convex structure of the coating surface, the surface area of ​​the coating can be increased, increasing its contact area with the environment, which helps to improve the corrosion resistance of the coating, because more coating surface means more ability to resist corrosive media;

[0061] Third, improve mechanical properties: dimensional interlocking can also improve the mechanical properties of the coating, making it more wear-resistant and scratch-resistant; fourth, the locking structure can increase the coating's resistance to peeling, thereby extending its service life;

[0062] Fifth, improve chemical corrosion resistance: Dimensional interlocking not only helps reduce the penetration of corrosive media, but also slows down the process of chemical corrosion by reducing the residence time of the media on the coating surface.

[0063] In order to further improve the high temperature resistance, nuclear radiation resistance, corrosion resistance and thermal insulation performance of the coating, as some feasible implementation methods of the present application, the amount of each component in the color filler in the surface layer is further limited, that is, the ceramics are hollow ceramic microbeads and ceramic particles YSZ; in the surface layer, the mass ratio of enamel powder, hollow ceramic microbeads, ceramic particles YSZ, mica, iron oxide, zinc titanate, fluoropolymer and borosilicate in the color filler is 5~10:5~8:2~3:1~3:1~2:3~5:0.5~1:5~7.

[0064] In order to further improve the high temperature resistance, nuclear radiation resistance, corrosion resistance and thermal insulation performance of the coating, as some feasible implementation methods of the present application, the amount of each component in the color filler in the bottom layer is further limited, that is, the ceramics are hollow ceramic microbeads and ceramic particles; in the bottom layer, the mass ratio of enamel powder, hollow ceramic microbeads, ceramic particles, mica, iron oxide, zinc titanate, fluoropolymer and borosilicate in the color filler is 25~30:15~20:3~5:1~3:1~2:3~5:0.5~1:1~3.

[0065] In order to further improve the high temperature resistance, nuclear radiation resistance, corrosion resistance and thermal insulation performance of the coating, as some feasible implementation methods of the present application, the type of metal powder is further limited, that is, the metal powder is one or more of Ta and Ti.

[0066] Metal powder has temperature resistance, radiation resistance and thermal expansion regulation, etc. However, in the field of nuclear applications, metal elements added to conventional coatings are strictly limited or prohibited, such as Al, Cr, etc., because these metals are unstable in irradiated environments. In order to adapt to the coating system and environment in the present invention, the present invention has made special screening of metal powders, and the screened metals can be stable in the coating system and can significantly improve the performance of the coating in various aspects.

[0067] In order to further improve the high temperature resistance, nuclear radiation resistance, corrosion resistance and thermal insulation performance of the coating, as some feasible implementation methods of the present application, the coating thickness of the surface layer and the bottom layer is further limited, that is, the thickness of the surface layer is 100μm~1mm; the thickness of the bottom layer is 1mm~1cm.

[0068] In this solution, when the coating is actually implemented, if the overall thickness is too small, then the performance is difficult to achieve. For example, if the thickness of the surface layer is too low, then the corrosion resistance, high temperature resistance or nuclear radiation resistance will be greatly weakened; if the thickness of the bottom layer is too low, the thermal insulation performance is difficult to meet the requirements. Similarly, if the coating is too thick, a large amount of residual stress and growth stress will be generated, causing the coating to crack and peel off very easily, which is not conducive to the ability to resist oxidation / thermal shock. The present invention can effectively meet the requirements of high corrosion resistance, high nuclear radiation resistance, high temperature resistance and high thermal insulation performance by limiting the coating thickness of the surface layer and the bottom layer.

[0069] In order to further improve the density performance of the coating, as some feasible implementation methods of the present application, the components and dosage of the enamel powder are further limited, that is, the enamel powder, calculated by mass fraction, includes 61-67% silicon dioxide, 6-11% zirconium dioxide, 3-10% aluminum oxide, 4-9% boron trioxide, 1-7% calcium oxide, 7-13% strontium oxide, and 2-6% potassium oxide. The total content of calcium oxide, strontium oxide and potassium oxide is 16-22%.

[0070] By adding enamel powder, this solution can increase the surface area through its self-repair function and volume expansion to block or bridge the void defects caused by ceramics, effectively improve the density of the coating, and thus improve the performance of the coating.

[0071] In addition, to achieve the above-mentioned purpose, the present invention also provides a method for preparing a nuclear radiation resistant heat insulation protective coating for a steam pipeline, comprising the following steps:

[0072] S1. The surface layer substrate, pigments, metal powder and diluent are mixed by ball milling, and after being evenly dispersed, a curing agent is added, and after being evenly dispersed, a surface layer coating is obtained; the bottom layer substrate, pigments, metal powder and diluent are mixed by ball milling, and after being evenly dispersed, a curing agent is added, and after being evenly dispersed, a bottom layer coating is obtained;

[0073] S2 The base coating and top coating are sprayed on the workpiece surface in sequence, and a protective coating is obtained after curing at room temperature.

[0074] In this scheme, after the bottom layer and the surface layer are coated, they are cured at room temperature. Generally speaking, the coating cured at room temperature does not perform well under high temperature conditions because it is difficult to resist thermal stress and oxidation in a high temperature environment. However, the coating of the present invention is cured at room temperature and then used in a high temperature environment. It can not only effectively resist thermal stress and oxidation in a high temperature environment, but also hybridize the organic and inorganic in the surface layer and the bottom layer under a high temperature service environment, further enhance the bonding force of the coating at high temperature, and improve the high temperature stability of the coating.

[0075] The coating of the present invention can be cured at room temperature thanks to the selection of the coating base. If the surface base is replaced with other resins (such as polyurethane, phenolic resin, etc.), it may lose the ability to cure at room temperature, such as extending the curing time, or even requiring baking for curing. This increases the difficulty of actual operation and makes it difficult to ensure that the coating can effectively resist thermal stress and oxidation in a high temperature environment.

[0076] The preparation of the coating described in the present application is further described in detail below in conjunction with the specific implementation methods; it is worth noting that: the various raw materials in the embodiments are all commercially available products, the hollow microbeads are a mixture of hollow alumina and hollow silica, and the mass ratio of the two is 1-9:9-1; the curing agent in the present invention is polyurethane resin.

[0077] Example 1

[0078] S1: 45 parts of acrylic modified silicone resin, 30 parts of pigments and fillers (enamel powder, hollow ceramic microspheres, ceramic particles YSZ, mica, iron oxide, zinc titanate, fluoropolymer and borosilicate in a mass ratio of 5:6:2:2:2:3.5:0.5:5), 7 parts of metal powder (the mass ratio of Ta and Ti is 1:1), 20 parts of diluent (the mass ratio of xylene and ethyl acetate is 1:1), 0.3 parts of leveling agent (polydimethylsiloxane), 0.3 parts of dispersant (polyethylene glycol), and 0.3 parts of defoamer (polyoxypropylene glycerol ether) are ball-milled and mixed, and after being evenly dispersed, 20 parts of polyurethane resin are added, and after being evenly dispersed, a surface coating is obtained;

[0079] 28 parts of water glass, 45 parts of pigments and fillers (enamel powder, hollow ceramic microspheres, ceramic particles YSZ, mica, iron oxide, zinc titanate, fluoropolymer and borosilicate in a mass ratio of 30:18:3:2:1:3:0.8:1), 8 parts of metal powder (the mass ratio of Ta and Ti is 1:1), 20 parts of diluent (the mass ratio of xylene and ethyl acetate is 1:1), 0.3 parts of leveling agent (polydimethylsiloxane), 0.3 parts of dispersant (polyethylene glycol), and 0.3 parts of defoamer (polyoxypropylene glycerol ether) are ball-milled and mixed, and after being evenly dispersed, 20 parts of polyurethane resin are added and evenly dispersed to obtain a primer;

[0080] S2 Spray the base coat on the workpiece surface (there should not be any other primer on the workpiece surface. If there is primer, it needs to be completely removed). The spraying thickness is 3mm. After curing at room temperature, spray the top coat with a spraying thickness of 500μm. After curing at room temperature, a coating is obtained.

[0081] Wherein, in Example 1, in the hollow microspheres, the mass ratio of hollow alumina to hollow silica is 3:5;

[0082] The mass percentages of the components in the enamel powder are: 61% silicon dioxide, 7% zirconium dioxide, 7% aluminum oxide, 6% boron trioxide, 4% calcium oxide, 11% strontium oxide, and 4% potassium oxide.

[0083] The coating prepared in Example 1 was subjected to relevant performance tests, and the test results are as follows:

[0084] Nuclear irradiation resistance: 1.7×10 5 After irradiation with γ-rays of 100 Gy, the coating was intact without any peeling, powdering or other defects;

[0085] Thermal insulation performance: can reduce the temperature from 260℃ to 80℃;

[0086] High temperature resistance and corrosion resistance: After working continuously for 5000 hours at 260℃, the coating showed no peeling, powdering or other defects;

[0087] Adhesion test: The adhesion was measured using the national standard pull-off method, the surface layer adhesion was 5.3Mpa, the bottom layer adhesion was originally 1.5Mpa, and was increased to 3.4Mpa after oxidation. Therefore, the coating in the present invention can significantly improve the adhesion level of the bottom layer under high temperature environment, especially at the bottom substrate / bottom layer interface and the hidden bottom layer / surface layer interface, effectively improving the adhesion of the coating.

[0088] Example 2

[0089] S1: 50 parts of acrylic modified silicone resin, 28 parts of pigments and fillers (enamel powder, hollow ceramic microspheres, ceramic particles YSZ, mica, iron oxide, zinc titanate, fluoropolymer and borosilicate in a mass ratio of 6:7:3:2:1.5:4:1:6), 9 parts of metal powder (the mass ratio of Ta and Ti is 1:1), 20 parts of diluent (the mass ratio of xylene and ethyl acetate is 1:1), 0.3 parts of leveling agent (polydimethylsiloxane), 0.5 parts of dispersant (polyethylene glycol), and 0.3 parts of defoaming agent (polyoxypropylene glycerol ether) are ball-milled and mixed, and after being evenly dispersed, 20 parts of polyurethane resin are added, and after being evenly dispersed, a surface coating is obtained;

[0090] 28 parts of water glass, 48 ​​parts of pigments and fillers (enamel powder, hollow ceramic microspheres, ceramic particles YSZ, mica, iron oxide, zinc titanate, fluoropolymer and borosilicate in a mass ratio of 28:18:5:2:2:3:1:2), 6 parts of metal powder (the mass ratio of Ta and Ti is 1:1), 20 parts of diluent (the mass ratio of xylene and ethyl acetate is 1:1), 0.3 parts of polydimethylsiloxane, 0.3 parts of polyethylene glycol and 0.3 parts of polyoxypropylene glycerol ether are ball-milled and mixed, and after being evenly dispersed, 20 parts of polyurethane resin are added and evenly dispersed to obtain a primer;

[0091] S2 Spray the base coat on the workpiece surface (there should not be any other primer on the workpiece surface. If there is primer, it needs to be completely removed). The spraying thickness is 3mm. After curing at room temperature, spray the top coat with a spraying thickness of 500μm. After curing at room temperature, a coating is obtained.

[0092] Among them, in Example 2, in the hollow microspheres, the mass ratio of hollow alumina to hollow silica is 2:5;

[0093] The mass percentages of the components in the enamel powder are: 61% silicon dioxide, 7% zirconium dioxide, 7% aluminum oxide, 6% boron trioxide, 4% calcium oxide, 11% strontium oxide, and 4% potassium oxide.

[0094] The coating prepared in Example 2 was subjected to relevant performance tests, and the test results are as follows:

[0095] Nuclear irradiation resistance: 1.7×10 5 After irradiation with γ-rays of 100 Gy, the coating was intact without any peeling, powdering or other defects;

[0096] Thermal insulation performance: can reduce the temperature from 275℃ to 80℃;

[0097] High temperature resistance and corrosion resistance: After working continuously for 5000 hours at 290℃, the coating showed no peeling, powdering or other defects;

[0098] Adhesion test: The adhesion was measured using the national standard pull-off method, the surface layer adhesion was 5.5 MPa, the bottom layer adhesion was originally 2.1 MPa, and was increased to 4.1 MPa after oxidation. Therefore, the coating in the present invention can significantly improve the adhesion level of the bottom layer under high temperature environment, especially at the bottom substrate / bottom layer interface and the hidden bottom layer / surface layer interface, effectively improving the adhesion of the coating.

[0099] Example 3

[0100] S1: 48 parts of acrylic modified silicone resin, 28 parts of pigments and fillers (enamel powder, hollow ceramic microspheres, ceramic particles YSZ, mica, iron oxide, zinc titanate, fluoropolymer and borosilicate in a mass ratio of 6:6:3:2:1:3.5:1:5), 7 parts of metal powder (the mass ratio of Ta and Ti is 1:1), 20 parts of diluent (the mass ratio of xylene and ethyl acetate is 1:1), 0.3 parts of leveling agent (polydimethylsiloxane), 0.5 parts of dispersant (polyethylene glycol), and 0.3 parts of defoaming agent (polyoxypropylene glycerol ether) are ball-milled and mixed, and after being evenly dispersed, 20 parts of polyurethane resin are added, and after being evenly dispersed, a surface coating is obtained;

[0101] 28 parts of water glass, 46 parts of pigments and fillers (enamel powder, hollow ceramic microspheres, ceramic particles YSZ, mica, iron oxide, zinc titanate, fluoropolymer and borosilicate in a mass ratio of 26:16:3:2:2:3:0.8:2), 8 parts of metal powder (the mass ratio of Ta and Ti is 1:1), 20 parts of diluent (the mass ratio of xylene and ethyl acetate is 1:1), 0.4 parts of polydimethylsiloxane, 0.5 parts of polyethylene glycol and 0.3 parts of polyoxypropylene glycerol ether are ball-milled and mixed, and after being evenly dispersed, 20 parts of polyurethane resin are added and evenly dispersed to obtain a primer;

[0102] S2 Spray the base coat on the workpiece surface (there should not be any other primer on the workpiece surface. If there is primer, it needs to be completely removed). The spraying thickness is 3mm. After curing at room temperature, spray the top coat with a spraying thickness of 500μm. After curing at room temperature, a coating is obtained.

[0103] Among them, in Example 3, in the hollow microspheres, the mass ratio of hollow alumina to hollow silica is 2:5;

[0104] The mass percentages of the components in the enamel powder are: 61% silicon dioxide, 7% zirconium dioxide, 7% aluminum oxide, 6% boron trioxide, 4% calcium oxide, 11% strontium oxide, and 4% potassium oxide.

[0105] The coating prepared in Example 3 was subjected to relevant performance tests, and the test results are as follows:

[0106] Nuclear irradiation resistance: 1.7×10 5After irradiation with γ-rays of 100 Gy, the coating was intact without any peeling, powdering or other defects;

[0107] Thermal insulation performance: can reduce the temperature from 290℃ to 80℃;

[0108] High temperature resistance and corrosion resistance: After working continuously for 5000 hours at 300℃, the coating showed no peeling, powdering or other defects;

[0109] Adhesion test: The adhesion was measured using the national standard pull-off method. The surface layer adhesion was 5.5 MPa, and the bottom layer adhesion was originally 2.2 MPa, which was increased to 4.0 MPa after oxidation. Therefore, the coating of the present invention can significantly improve the adhesion level of the bottom layer under high temperature conditions, especially at the bottom substrate / bottom layer interface and the hidden bottom layer / surface layer interface.

[0110] Comparative Example 1

[0111] The top coating and the base coating in Example 1 are directly mixed and then applied, and the coating thickness is the same as in Example 1.

[0112] The coating is in poor condition after coating. Under microscopic observation, gaps or cracks can be observed between the layers, and the interface is difficult to mix. After high-temperature service, the coating cracks and peels off quickly, and the service time is less than 20 hours.

[0113] The mixed coating in comparative example 1 is difficult to be applied in the nuclear industry environment. Because the substrates of the topcoat coating and the bottomcoat are not a system, there can only be interface bonding, which is difficult to be compatible.

[0114] Comparative Example 2

[0115] Only the topcoat paint in Example 1 is used as the protective coating, and only the primer paint in Example 1 is used as the protective coating, and the coating thickness is the same as that in Example 1.

[0116] Only the surface coating is used as the protective coating. Compared with Example 1, although it has certain heat resistance, radiation resistance, and corrosion resistance, its heat insulation performance is almost lost, and it is difficult to be used in a nuclear environment.

[0117] Only the primer is used as the protective coating. Compared with Example 1, although the heat resistance and heat insulation performance are relatively improved, the radiation resistance and corrosion resistance will be significantly reduced, making it difficult to be applied in a nuclear environment.

[0118] Comparative Example 3

[0119] Compared with Example 1, no metal is added to the base coating and the top coating.

[0120] The coating's radiation resistance drops by an order of magnitude and it lacks the ability to be used in nuclear applications. Secondly, the coating's heat resistance is reduced and it cannot meet the basic requirements for use in high-temperature nuclear environments. Finally, the coating's mechanical properties are greatly degraded. Because metal fillers can enhance the coating's hardness, wear resistance and impact resistance, not using metal fillers may lead to a decrease in the coating's mechanical properties.

Claims

1. A nuclear radiation resistant heat insulation protective coating for steam pipelines, characterized in that: Including the surface layer and the bottom layer; The surface layer comprises the following components in parts by weight: 30~50 parts of acrylic modified silicone resin, 10~30 parts of pigments and fillers, 5-10 parts of metal powder, 18~20 parts of curing agent and 18~20 parts of diluent; The bottom layer comprises the following components in parts by weight: 10~30 parts of water glass, 30~50 parts of pigments and fillers, 5-10 parts of metal powder, 18~20 parts of curing agent and 18~20 parts of diluent; Wherein, the pigments and fillers include enamel powder, ceramics and auxiliary fillers; The auxiliary fillers include mica, iron oxide, zinc titanate, fluoropolymer and borosilicate; In the surface layer, the mass ratio of enamel powder, ceramics and auxiliary fillers in the pigments and fillers is 5-10:5-11:8-20; In the bottom layer, the mass ratio of enamel powder, ceramics and auxiliary fillers in the pigments and fillers is 25-30:15-25:6-15.

2. The nuclear radiation resistant heat insulation protective coating for steam pipeline according to claim 1, characterized in that: The ceramics are hollow ceramic microspheres and ceramic particles; in the surface layer, the mass ratio of enamel powder, hollow ceramic microspheres, ceramic particles, mica, iron oxide, zinc titanate, fluoropolymer and borosilicate in the color filler is 5-10:5-8:2-3:1-3:1-2:3-5:0.5-1:5-7.

3. The nuclear radiation resistant heat insulation protective coating for steam pipeline according to claim 1, characterized in that: The ceramics are hollow ceramic microspheres and ceramic particles YSZ; in the bottom layer, the mass ratio of enamel powder, hollow ceramic microspheres, ceramic particles YSZ, mica, iron oxide, zinc titanate, fluoropolymer and borosilicate in the color filler is 25-30:15-20:3-5:1-3:1-2:3-5:0.5-1:1-3.

4. The nuclear radiation resistant heat insulation protective coating for steam pipeline according to claim 1, characterized in that: The metal powder is one or more of Ta and Ti.

5. The nuclear radiation resistant heat insulation protective coating for steam pipeline according to claim 1, characterized in that: The thickness of the surface layer is 100 μm to 1 mm; the thickness of the bottom layer is 1 mm to 1 cm.

6. The nuclear radiation resistant heat insulation protective coating for steam pipeline according to claim 1, characterized in that: The enamel powder comprises, by mass fraction, 61-67% silicon dioxide, 6-11% zirconium dioxide, 3-10% aluminum oxide, 4-9% boron oxide, 1-7% calcium oxide, 7-13% strontium oxide, and 2-6% potassium oxide. The total content of calcium oxide, strontium oxide and potassium oxide is 16-22%.

7. The method for preparing the nuclear radiation resistant heat insulation protective coating for steam pipeline according to any one of claims 1 to 6, characterized in that: The steps include: S1. The acrylic modified silicone resin, pigments, fillers, metal powder and diluent are mixed by ball milling, and after being evenly dispersed, a curing agent is added, and after being evenly dispersed, a top coating is obtained; the water glass, pigments, fillers, metal powder and diluent are mixed by ball milling, and after being evenly dispersed, a curing agent is added, and after being evenly dispersed, a bottom coating is obtained; S2 sprays the base coating and the top coating on the workpiece surface in sequence, and obtains a protective coating after curing at room temperature.

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