A high-temperature-resistant anticorrosive coating for boilers and a preparation method thereof

Abstract

The present application belongs to the technical field of boiler protection. More particularly, it relates to a kind of high-temperature resistant anticorrosive coating for boiler and a preparation method thereof. The product of the present application comprises: primer, transition coating and topcoat; the primer comprises: 25-30 parts of epoxy modified silane resin, 55-60 parts of composite filler, 3-5 parts of phosphate anti-rust pigment, 2-4 parts of fumed silica, 8-12 parts of xylene; wherein the composite filler is compounded by flaky zinc powder and hollow spherical alumina according to a mass ratio of 4-6:1; the transition coating comprises: 35-40 parts of epoxy-silicone copolymer resin, 10-15 parts of organic bentonite, 8-10 parts of hollow spherical alumina, 2-4 parts of silane coupling agent, 10-12 parts of propylene glycol methyl ether; the topcoat comprises: 25-30 parts of methylphenyl type silicone resin, 20-25 parts of spherical nanometer silicon carbide, 10-15 parts of flaky nanometer aluminum powder, 8-15 parts of micron glass flake, 0.8-1.2 parts of silane coupling agent, 12-16 parts of xylene.

Description

Technical Field

[0001] This invention belongs to the field of boiler protection technology. More specifically, it relates to a high-temperature resistant and corrosion-resistant coating for boilers and its preparation method. Background Technology

[0002] High-temperature resistant anti-corrosion coatings for boilers are protective materials specifically designed for high-temperature equipment such as boilers and heat exchangers. They can effectively protect metal substrates in high-temperature and corrosive environments, extending the service life of the equipment.

[0003] These types of coatings can typically withstand high temperatures of 300℃-1200℃, with some special coatings (such as ceramic-based coatings) reaching over 1500℃. During use, it is necessary to consider the erosion caused by corrosive media such as water vapor, sulfides, salt spray, and acidic gases.

[0004] However, in actual use, the boiler will undergo repeated hot and cold cycles. During this process, it is necessary to consider that after repeated cooling cycles, the coating can still be firmly bonded to the metal substrate (usually carbon steel or stainless steel) to prevent it from falling off. Summary of the Invention

[0005] The technical problem this invention aims to solve is that existing high-temperature resistant coatings for boilers often experience a decrease in adhesion between the coating and the metal substrate during repeated hot and cold cycles, leading to paint peeling. To address this challenge, this invention provides a high-temperature resistant anti-corrosion coating for boilers and its preparation method.

[0006] The purpose of this invention is to provide a high-temperature resistant and corrosion-resistant coating for boilers.

[0007] Another objective of this invention is to provide a method for preparing a high-temperature resistant and corrosion-resistant coating for boilers.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution:

[0009] A high-temperature resistant and corrosion-resistant coating for boilers includes a primer, a transition coating, and a topcoat;

[0010] The primer comprises the following raw materials in parts by weight:

[0011] 25-30 parts epoxy-modified silane resin, 55-60 parts composite filler, 3-5 parts phosphate anti-rust pigment, 2-4 parts fumed silica, 8-12 parts xylene;

[0012] The composite filler is composed of flaky zinc powder and hollow spherical alumina in a mass ratio of 4-6:1.

[0013] The transition coating comprises the following raw materials in parts by weight:

[0014] 35-40 parts epoxy-organosilicon copolymer resin, 10-15 parts organobentonite, 8-10 parts hollow spherical alumina, 2-4 parts silane coupling agent, 10-12 parts propylene glycol methyl ether.

[0015] The topcoat comprises the following raw materials in parts by weight:

[0016] 25-30 parts methylphenyl type organosilicon resin, 20-25 parts spherical nano silicon carbide, 10-15 parts flake nano aluminum powder, 8-15 parts micron glass flakes, 0.8-1.2 parts silane coupling agent, 12-16 parts xylene;

[0017] The D50 of the spherical silicon carbide nanoparticles is 5-10 nm.

[0018] The D50 of the flake-shaped nano-aluminum powder is 95-100 nm;

[0019] The D50 of the micron-sized glass flakes is 20-30 μm.

[0020] The beneficial effects of the above technical solution are as follows:

[0021] The above technical solution constructs a high-temperature resistant and anti-corrosion coating system for boilers by employing a combination of primer, transition coating, and topcoat. Specifically, the primer is used to directly bond with the boiler substrate. By using a composite filler system composed of flake zinc powder and hollow spherical alumina, and selecting an appropriate amount of addition, the primer has a relatively low coefficient of thermal expansion, avoiding coating peeling caused by the difference in thermal expansion coefficient between the primer and the substrate during alternating hot and cold cycles. In particular, during the primer curing process, at least a portion of the hollow spherical alumina can float to the surface of the primer due to its hollow structure, while the flake zinc powder remains dispersed in the coating system. The hollow spherical alumina floating to the surface can form a stress-relieving interface at the interface between the primer and the transition coating, thus effectively preventing interface delamination caused by expansion or contraction stress at the interface during hot and cold cycles.

[0022] The above technical solution improves the bonding between the primer and the topcoat by setting a coating system with both adhesion and high temperature resistance in the transition layer. It also increases the diffusion path of corrosive media by using organic bentonite. By adding hollow spherical alumina, at least a portion of the hollow spherical alumina can float to the surface of the transition layer due to its hollow structure, thus forming an interface with stress relief at the interface. In this way, it can effectively avoid interface peeling caused by expansion or contraction stress at the interface during thermal cycling.

[0023] The above technical solution further adjusts the topcoat system with excellent high-temperature resistance, and uses spherical nano-silicon carbide and flake nano-aluminum powder of different sizes, combined with a micron-sized glass flake filler system with larger particle size. This forms a dense filler in the topcoat. Since the small-sized nano-silicon carbide and nano-aluminum powder are spherical and flake-shaped respectively, a complex three-dimensional corrosion medium diffusion path can be formed during the dense filling process. As a result, the product has excellent corrosion resistance and will not fail due to local corrosion in actual use.

[0024] Furthermore, the epoxy-modified silane resin is obtained by reacting the following raw materials:

[0025] 30-40 parts epoxy resin E-51, 20-25 parts methyltriethoxysilane, 4-6 parts silane coupling agent KH-560, 1.2-1.5 parts tetraisopropyl titanate.

[0026] Furthermore, the D50 of the flake zinc powder is 10-15 μm; the D50 of the hollow spherical alumina is 60-80 nm, and the average wall thickness of the hollow spherical alumina is 10-15 nm; the D50 of the organobentonite is 18-20 μm.

[0027] The beneficial effects of the above technical solution are as follows:

[0028] By further controlling the D50 of the flake zinc powder to 10-15 μm, the D50 of the organobentonite to 18-20 μm, and the D50 of the hollow spherical alumina to 60-80 nm, the hollow spherical alumina, due to its larger particle size difference compared to the flake zinc powder and organobentonite, diffuses more easily to the surface of the primer or transition layer. The flake zinc powder, due to its flake structure, is easily dispersed within the polymer chains of the polymer resin in the primer. Thus, the distribution of hollow spherical alumina significantly improves the interface between the primer and the transition layer, as well as the interface between the transition layer and the topcoat, resulting in superior resistance to thermal cycling. In particular, its dense distribution at the interface also helps prevent corrosive media from rapidly crossing the interface and corroding the underlying substrate.

[0029] Furthermore, the organobentonite is modified organobentonite, and sodium dodecylbenzenesulfonate is embedded in the interlayer of the modified organobentonite.

[0030] The beneficial effects of the above technical solution are as follows:

[0031] The above technical solution further widens the interlayer spacing of the layered bentonite by embedding sodium dodecylbenzenesulfonate between the layers. In this way, during the hot and cold cycle, the widened interlayer spacing has the effect of buffering expansion or contraction stress, further reducing the local peeling of the coating caused by transition layer fatigue.

[0032] Furthermore, the sphericity of the spherical nano-silicon carbide is 0.85-0.90; the sphericity of the hollow spherical alumina is 0.85-0.90.

[0033] Furthermore, the silane coupling agent is selected from any one of silane coupling agents KH-540, KH-550, KH-560, KH-570, and KH-580.

[0034] A method for preparing a high-temperature resistant and corrosion-resistant coating for boilers, comprising the following specific steps:

[0035] Raw material preparation:

[0036] Weigh each component according to the raw material composition;

[0037] Primer preparation:

[0038] After the epoxy-modified silane resin and xylene are stirred and dispersed evenly, composite filler, phosphate anti-rust pigment and fumed silica are added, and stirred and dispersed evenly to obtain the primer.

[0039] Preparation of transition coating:

[0040] After the epoxy-organosilicon copolymer resin and propylene glycol methyl ether are stirred and dispersed evenly, organobentonite, hollow spherical alumina and silane coupling agent are added and stirred and dispersed evenly to obtain a transition coating.

[0041] Topcoat preparation:

[0042] After the methylphenyl type organosilicon resin and xylene are stirred and dispersed evenly, spherical nano silicon carbide, flake nano aluminum powder, micron glass flakes and silane coupling agent are added and stirred and dispersed evenly to obtain the topcoat.

[0043] Furthermore, the specific preparation steps also include:

[0044] Preparation of epoxy-modified silane resin:

[0045] Epoxy resin E-51 is added to the reactor, heated to 75-80℃, and vacuum dehydrated to remove residual moisture. Then, 10-15% of the mass of epoxy resin E-51 in anhydrous ethanol is added to obtain a premix.

[0046] Methyltriethoxysilane, silane coupling agent KH-560 and tetrabutyl titanate are mixed and heated to 75-80℃. Then, 8-10% of the mass of methyltriethoxysilane and deionized water are added. After stirring and reacting, hydrolysate is obtained.

[0047] After adjusting the pH of the premix to 5.0-6.0, the hydrolysate is added dropwise to the premix. After the addition is complete, the temperature is raised to 90℃ and kept at this temperature for 3-5 hours. Acetic acid is then added dropwise for neutralization, and ethanol and byproducts are removed by distillation to obtain epoxy-modified silane resin.

[0048] Furthermore, the specific preparation steps also include:

[0049] Preparation of epoxy-organosilicon copolymer resin:

[0050] By weight, take 100-120 parts of epoxy resin E-51, 45-50 parts of methyl phenyl silicone resin, 12-15 parts of silane coupling agent KH-560, 1-3 parts of tetraisopropyl titanate, and 45-50 parts of xylene.

[0051] Epoxy resin E-51 was added to the reactor, heated to 75-80℃, and vacuum dehydrated to remove residual moisture. Then, xylene was added to dilute the resin to obtain pretreated epoxy resin.

[0052] After mixing methylphenyl silicone resin, silane coupling agent KH-560, and tetraisopropyl titanate, 3-5% (by weight of methylphenyl silicone resin) of deionized water was added dropwise. The mixture was stirred and reacted for 10-15 minutes at a pH of 5.0-5.2 to obtain the activated material.

[0053] The activator is added dropwise to the pretreated epoxy resin, and the mixture is heated and reacted at 100-110℃ for 3-5 hours. Acetic acid is then added dropwise to neutralize the resin, and xylene is removed by distillation to obtain the epoxy-organosilicon copolymer resin. Detailed Implementation

[0054] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0055] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0056] The methyl phenyl silicone resin, designated SICO-P112, was purchased from Shandong Silicon Science New Materials Co., Ltd.

[0057] Example 1

[0058] Preparation of epoxy-modified silane resin:

[0059] By weight, take 30 parts epoxy resin E-51, 20 parts methyltriethoxysilane, 4 parts silane coupling agent KH-560, and 1.2 parts tetraisopropyl titanate.

[0060] Epoxy resin E-51 was added to the reactor, heated to 75°C, and vacuum dehydrated to remove residual moisture. Then, 10% by weight of anhydrous ethanol of epoxy resin E-51 was added to obtain a premix.

[0061] Methyltriethoxysilane, silane coupling agent KH-560 and tetrabutyl titanate were mixed and heated to 75°C. Then, 8% by weight of deionized water was added to the mixture and stirred to react, yielding the hydrolysate.

[0062] After adjusting the pH of the premix to 5.0, the hydrolysate was added dropwise to the premix at a rate of 4 mL / min. After the addition was complete, the temperature was raised to 90°C and kept at that temperature for 3 hours. Acetic acid was added dropwise to neutralize the reaction, and then ethanol and byproducts were removed by distillation to obtain epoxy-modified silane resin.

[0063] Preparation of epoxy-organosilicon copolymer resin:

[0064] By weight, take 100 parts of epoxy resin E-51, 45 parts of methyl phenyl silicone resin, 12 parts of silane coupling agent KH-560, 1 part of tetraisopropyl titanate, and 45 parts of xylene.

[0065] Epoxy resin E-51 was added to the reactor, heated to 75°C, and vacuum dehydrated to remove residual moisture. Then, xylene was added to dilute the resin to obtain pretreated epoxy resin.

[0066] Methylphenyl silicone resin, silane coupling agent KH-560, and tetraisopropyl titanate were mixed, and then 3% (by weight of methylphenyl silicone resin) of deionized water was added dropwise. The mixture was stirred and reacted for 10 minutes at pH 5.0 to obtain the activated material.

[0067] The activator was added dropwise to the pretreated epoxy resin at a rate of 6 mL / min. After heating and reacting at 100°C for 3 h, acetic acid was added dropwise to neutralize the resin. Then, xylene was removed by distillation to obtain the epoxy-organosilicon copolymer resin.

[0068] Modified organobentonite:

[0069] Sodium-based bentonite and water were mixed at a mass ratio of 1:8 and then microwaved and ultrasonically dispersed for 20 minutes at a microwave power of 200W and an ultrasonic frequency of 80kHz. Then, sodium dodecylbenzenesulfonate (8% by mass of sodium-based bentonite) was added, and the microwave ultrasonic reaction was continued for 30 minutes. The mixture was then filtered, the filter cake was collected, and the filter cake was dried to constant weight at a temperature of 100℃. The cake was then broken up and sieved to obtain modified organic bentonite.

[0070] Primer preparation:

[0071] By weight, take 25 parts epoxy-modified silane resin, 55 parts composite filler, 3 parts phosphate anti-rust pigment, 2 parts fumed silica, and 8 parts xylene.

[0072] The composite filler is composed of flaky zinc powder and hollow spherical alumina in a mass ratio of 4:1.

[0073] After the epoxy-modified silane resin and xylene are stirred and dispersed evenly, composite filler, phosphate anti-rust pigment and fumed silica are added, and stirred and dispersed evenly to obtain the primer.

[0074] Preparation of transition coating:

[0075] By weight, take 35 parts epoxy-organosilicon copolymer resin, 10 parts modified organobentonite, 8 parts hollow spherical alumina, 2 parts silane coupling agent, and 10 parts propylene glycol methyl ether.

[0076] After the epoxy-organosilicon copolymer resin and propylene glycol methyl ether are stirred and dispersed evenly, modified organobentonite, hollow spherical alumina and silane coupling agent are added and stirred and dispersed evenly to obtain a transition coating.

[0077] Topcoat preparation:

[0078] By weight, take 25 parts of methylphenyl silicone resin, 20 parts of spherical nano silicon carbide, 10 parts of flake nano aluminum powder, 8 parts of micron-sized glass flakes, 0.8 parts of silane coupling agent, and 12 parts of xylene.

[0079] Wherein, the spherical nano-silicon carbide has a D50 of 5 nm; the sheet-like nano-aluminum powder has a D50 of 95 nm; and the micron-sized glass flakes have a D50 of 20 μm.

[0080] After the methylphenyl type organosilicon resin and xylene are stirred and dispersed evenly, spherical nano silicon carbide, flake nano aluminum powder, micron glass flakes and silane coupling agent are added and stirred and dispersed evenly to obtain the topcoat.

[0081] The D50 of the flaky zinc powder is 10 μm; the D50 of the hollow spherical alumina is 60 nm, and the average wall thickness of the hollow spherical alumina is 10 nm; the D50 of the modified organobentonite is 18 μm; the sphericity of the spherical nano-silicon carbide is 0.85; the sphericity of the hollow spherical alumina is 0.85; and the silane coupling agent is selected from silane coupling agent KH-540.

[0082] Example 2

[0083] Preparation of epoxy-modified silane resin:

[0084] By weight, take 35 parts epoxy resin E-51, 22 parts methyltriethoxysilane, 5 parts silane coupling agent KH-560, and 1.3 parts tetraisopropyl titanate.

[0085] Epoxy resin E-51 was added to the reactor, heated to 78°C, and vacuum dehydrated to remove residual moisture. Then, 12% by weight of anhydrous ethanol of epoxy resin E-51 was added to obtain a premix.

[0086] Methyltriethoxysilane, silane coupling agent KH-560 and tetrabutyl titanate were mixed and heated to 78°C. Then, 9% of the mass of methyltriethoxysilane and deionized water were added. After stirring and reacting, hydrolysate was obtained.

[0087] After adjusting the pH of the premix to 5.5, the hydrolysate was added dropwise to the premix at a rate of 6 mL / min. After the addition was complete, the temperature was raised to 90°C and kept at that temperature for 4 hours. Acetic acid was added dropwise to neutralize the mixture, and then ethanol and byproducts were removed by distillation to obtain epoxy-modified silane resin.

[0088] Preparation of epoxy-organosilicon copolymer resin:

[0089] By weight, take 110 parts of epoxy resin E-51, 48 parts of methyl phenyl silicone resin, 13 parts of silane coupling agent KH-560, 2 parts of tetraisopropyl titanate, and 48 parts of xylene.

[0090] Epoxy resin E-51 was added to the reactor, heated to 78°C, and vacuum dehydrated to remove residual moisture. Then, xylene was added to dilute the resin to obtain pretreated epoxy resin.

[0091] Methylphenyl silicone resin, silane coupling agent KH-560, and tetraisopropyl titanate were mixed, and then 4% (by weight of methylphenyl silicone resin) of deionized water was added dropwise. The mixture was stirred and reacted for 12 minutes at pH 5.1 to obtain the activated material.

[0092] The activator was added dropwise to the pretreated epoxy resin at a rate of 7 mL / min. After heating and reacting at 105 °C for 4 h, acetic acid was added dropwise to neutralize the resin. Then, xylene was removed by distillation to obtain the epoxy-organosilicon copolymer resin.

[0093] Modified organobentonite:

[0094] Sodium-based bentonite and water were mixed at a mass ratio of 1:8. The mixture was then microwaved and ultrasonically dispersed for 25 minutes at a microwave power of 200W and an ultrasonic frequency of 90kHz. Sodium dodecylbenzenesulfonate (9% by mass of sodium-based bentonite) was then added, and the microwave ultrasonic reaction was continued for another 35 minutes. The mixture was then filtered, the filter cake was collected, and the filter cake was dried to constant weight at 100℃. The cake was then broken up and sieved to obtain modified organic bentonite.

[0095] Primer preparation:

[0096] By weight, take 28 parts epoxy-modified silane resin, 56 parts composite filler, 4 parts phosphate anti-rust pigment, 3 parts fumed silica, and 10 parts xylene.

[0097] The composite filler is composed of flaky zinc powder and hollow spherical alumina in a mass ratio of 5:1.

[0098] After the epoxy-modified silane resin and xylene are stirred and dispersed evenly, composite filler, phosphate anti-rust pigment and fumed silica are added, and stirred and dispersed evenly to obtain the primer.

[0099] Preparation of transition coating:

[0100] By weight, take 36 parts epoxy-organosilicon copolymer resin, 12 parts modified organobentonite, 9 parts hollow spherical alumina, 3 parts silane coupling agent, and 11 parts propylene glycol methyl ether.

[0101] After the epoxy-organosilicon copolymer resin and propylene glycol methyl ether are stirred and dispersed evenly, modified organobentonite, hollow spherical alumina and silane coupling agent are added and stirred and dispersed evenly to obtain a transition coating.

[0102] Topcoat preparation:

[0103] By weight, take 27 parts of methylphenyl silicone resin, 21 parts of spherical nano silicon carbide, 13 parts of flake nano aluminum powder, 12 parts of micron glass flakes, 0.9 parts of silane coupling agent, and 14 parts of xylene.

[0104] The spherical silicon carbide nanoparticles have a D50 of 8 nm; the sheet-like aluminum nanoparticles have a D50 of 98 nm; and the micron-sized glass flakes have a D50 of 25 μm.

[0105] After the methylphenyl type organosilicon resin and xylene are stirred and dispersed evenly, spherical nano silicon carbide, flake nano aluminum powder, micron glass flakes and silane coupling agent are added and stirred and dispersed evenly to obtain the topcoat.

[0106] The D50 of the flaky zinc powder is 12 μm; the D50 of the hollow spherical alumina is 70 nm, and the average wall thickness of the hollow spherical alumina is 12 nm; the D50 of the modified organobentonite is 19 μm; the sphericity of the spherical nano-silicon carbide is 0.88; the sphericity of the hollow spherical alumina is 0.86; and the silane coupling agent is selected from silane coupling agent KH-550.

[0107] Example 3

[0108] Preparation of epoxy-modified silane resin:

[0109] By weight, take 40 parts epoxy resin E-51, 25 parts methyltriethoxysilane, 6 parts silane coupling agent KH-560, and 1.5 parts tetraisopropyl titanate.

[0110] Epoxy resin E-51 was added to the reactor, heated to 80°C, and vacuum dehydrated to remove residual moisture. Then, 15% by weight of anhydrous ethanol of epoxy resin E-51 was added to obtain a premix.

[0111] Methyltriethoxysilane, silane coupling agent KH-560 and tetrabutyl titanate were mixed and heated to 80°C. Then, 10% of the mass of methyltriethoxysilane and deionized water were added. After stirring and reacting, hydrolysate was obtained.

[0112] After adjusting the pH of the premix to 6.0, the hydrolysate was added dropwise to the premix at a rate of 8 mL / min. After the addition was complete, the temperature was raised to 90°C and kept at that temperature for 5 hours. Acetic acid was added dropwise to neutralize the mixture, and then ethanol and byproducts were removed by distillation to obtain epoxy-modified silane resin.

[0113] Preparation of epoxy-organosilicon copolymer resin:

[0114] By weight, take 120 parts of epoxy resin E-51, 50 parts of methyl phenyl silicone resin, 15 parts of silane coupling agent KH-560, 3 parts of tetraisopropyl titanate, and 50 parts of xylene.

[0115] Epoxy resin E-51 was added to the reactor, heated to 80°C, and vacuum dehydrated to remove residual moisture. Then, xylene was added to dilute the resin to obtain pretreated epoxy resin.

[0116] Methylphenyl silicone resin, silane coupling agent KH-560, and tetraisopropyl titanate were mixed, and then 5% (by weight of methylphenyl silicone resin) of deionized water was added dropwise. The mixture was stirred and reacted for 15 minutes at pH 5.2 to obtain the activated material.

[0117] The activator was added dropwise to the pretreated epoxy resin at a rate of 8 mL / min. After heating and reacting at 110°C for 5 h, acetic acid was added dropwise to neutralize the resin. Then, xylene was removed by distillation to obtain the epoxy-organosilicon copolymer resin.

[0118] Modified organobentonite:

[0119] Sodium-based bentonite and water were mixed at a mass ratio of 1:8. The mixture was then microwaved and ultrasonically dispersed for 30 minutes at a microwave power of 200W and an ultrasonic frequency of 100kHz. Sodium dodecylbenzenesulfonate (10% of the mass of sodium-based bentonite) was then added, and the microwave ultrasonic reaction was continued for 45 minutes. The mixture was then filtered, the filter cake was collected, and the filter cake was dried to constant weight at a temperature of 100℃. The cake was then broken up and sieved to obtain modified organic bentonite.

[0120] Primer preparation:

[0121] By weight, take 30 parts epoxy-modified silane resin, 60 parts composite filler, 5 parts phosphate anti-rust pigment, 4 parts fumed silica, and 12 parts xylene.

[0122] The composite filler is composed of flaky zinc powder and hollow spherical alumina in a mass ratio of 6:1.

[0123] After the epoxy-modified silane resin and xylene are stirred and dispersed evenly, composite filler, phosphate anti-rust pigment and fumed silica are added, and stirred and dispersed evenly to obtain the primer.

[0124] Preparation of transition coating:

[0125] By weight, take 40 parts epoxy-organosilicon copolymer resin, 15 parts modified organobentonite, 10 parts hollow spherical alumina, 4 parts silane coupling agent, and 12 parts propylene glycol methyl ether.

[0126] After the epoxy-organosilicon copolymer resin and propylene glycol methyl ether are stirred and dispersed evenly, modified organobentonite, hollow spherical alumina and silane coupling agent are added and stirred and dispersed evenly to obtain a transition coating.

[0127] Topcoat preparation:

[0128] By weight, take 30 parts of methylphenyl silicone resin, 25 parts of spherical nano silicon carbide, 15 parts of flake nano aluminum powder, 15 parts of micron glass flakes, 1.2 parts of silane coupling agent, and 16 parts of xylene.

[0129] Wherein, the spherical nano-silicon carbide has a D50 of 10 nm; the sheet-like nano-aluminum powder has a D50 of 100 nm; and the micron-sized glass flakes have a D50 of 30 μm.

[0130] After the methylphenyl type organosilicon resin and xylene are stirred and dispersed evenly, spherical nano silicon carbide, flake nano aluminum powder, micron glass flakes and silane coupling agent are added and stirred and dispersed evenly to obtain the topcoat.

[0131] The D50 of the flaky zinc powder is 15 μm; the D50 of the hollow spherical alumina is 80 nm, and the average wall thickness of the hollow spherical alumina is 15 nm; the D50 of the modified organobentonite is 20 μm; the sphericity of the spherical nano-silicon carbide is 0.90; the sphericity of the hollow spherical alumina is 0.90; and the silane coupling agent is selected from silane coupling agent KH-570.

[0132] Example 4

[0133] The difference between this embodiment and Embodiment 1 is that the D50 of the hollow spherical alumina is 10 μm, while the other conditions remain unchanged.

[0134] Example 5

[0135] The difference between this embodiment and Example 1 is that the organic bentonite is not modified, that is, sodium dodecylbenzenesulfonate is not added, and the other conditions remain unchanged.

[0136] Comparative Example 1

[0137] The difference between this comparative example and Example 1 is that hollow spherical alumina is not added to the primer and transition coating, while the other conditions remain unchanged.

[0138] Comparative Example 2

[0139] The difference between this comparative example and Example 1 is that, in both the primer and the transition coating, solid spherical alumina of equal mass is used instead of hollow spherical alumina, while the other conditions remain unchanged.

[0140] Comparative Example 3

[0141] The difference between this comparative example and Example 1 is that hollow spherical alumina was not added to the primer, while the other conditions remained unchanged.

[0142] Comparative Example 4

[0143] The difference between this comparative example and Example 1 is that hollow spherical alumina was not added to the transition coating, while the other conditions remained unchanged.

[0144] Comparative Example 5

[0145] The difference between this comparative example and Example 1 is that the D50 of the flake-shaped nano-aluminum powder is 20 μm; all other conditions remain unchanged.

[0146] Comparative Example 6

[0147] The difference between this comparative example and Example 1 is that no flake-shaped nano-aluminum powder was added, while all other conditions remained unchanged.

[0148] Performance tests were conducted on the products obtained in the examples and comparative examples. The specific test methods and results are as follows:

[0149] Using Q235B steel plate as the substrate, after sandblasting to Sa2.5 grade, the primer, transition coating and topcoat are applied in sequence according to the following specifications:

[0150] Primer spraying: dry film thickness of 80μm, baked at 80℃ for 4h;

[0151] Transition layer spraying: The dry film thickness is 60μm, and the spraying is carried out after the primer has been baked.

[0152] Topcoat spraying: The dry film thickness is 100μm. After baking and curing at 80℃ for 1 hour, the temperature is raised to 200℃ and baked and cured for another hour. Then, the temperature is raised to 400℃ and baked and cured for another hour.

[0153] Reference standard: ASTM D4541. The product adhesion was tested after heating to 200°C at a rate of 5°C / min, holding at that temperature for 10 min, cooling to 25°C at a rate of 5°C / min, and holding at that temperature for 10 min; after 200 cycles of this heating and cooling, the adhesion of the product was tested. The detailed test results are shown in Table 1.

[0154] Referring to the standard ASTM B117, the product's salt spray resistance was tested for 500 hours. The detailed test results are shown in Table 1.

[0155] After the steel plate was sprayed, it was heated to 300°C and then quenched in cold water at 10°C. After 50 cycles of heating and quenching, the surface was observed to see if there were any obvious cracks or local peeling. The detailed results are shown in Table 1.

[0156] Table 1: Product Performance Test Results

[0157]

[0158] As can be seen from the test results in Table 1, the product obtained by the present invention can effectively protect the steel plate and has excellent resistance to alternating hot and cold cycles.

[0159] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A high-temperature resistant and corrosion-resistant coating for boilers, characterized in that, Includes primer, transition coating, and topcoat; The primer comprises the following raw materials in parts by weight: 25-30 parts epoxy-modified silane resin, 55-60 parts composite filler, 3-5 parts phosphate anti-rust pigment, 2-4 parts fumed silica, 8-12 parts xylene; The composite filler is composed of flaky zinc powder and hollow spherical alumina in a mass ratio of 4-6:

1. The D50 of the flaky zinc powder is 10-15 μm; The hollow spherical alumina has a D50 of 60-80 nm; The transition coating comprises the following raw materials in parts by weight: 35-40 parts epoxy-organosilicon copolymer resin, 10-15 parts organobentonite, 8-10 parts hollow spherical alumina, 2-4 parts silane coupling agent, 10-12 parts propylene glycol methyl ether. The D50 of the organic bentonite is 18-20 μm; The topcoat comprises the following raw materials in parts by weight: 25-30 parts methylphenyl type organosilicon resin, 20-25 parts spherical nano silicon carbide, 10-15 parts flake nano aluminum powder, 8-15 parts micron glass flakes, 0.8-1.2 parts silane coupling agent, 12-16 parts xylene; The D50 of the spherical silicon carbide nanoparticles is 5-10 nm. The D50 of the flake-shaped nano-aluminum powder is 95-100 nm; The D50 of the micron-sized glass flakes is 20-30 μm.

2. The boiler high-temperature resistant and anti-corrosion coating according to claim 1, characterized in that, The epoxy-modified silane resin is obtained by reacting the following raw materials: 30-40 parts epoxy resin E-51, 20-25 parts methyltriethoxysilane, 4-6 parts silane coupling agent KH-560, 1.2-1.5 parts tetraisopropyl titanate.

3. The boiler high-temperature resistant and anti-corrosion coating according to claim 1, characterized in that, The average wall thickness of the hollow spherical alumina is 10-15 nm.

4. A boiler high-temperature resistant and corrosion-resistant coating according to any one of claims 1 or 3, characterized in that, The organobentonite is a modified organobentonite, wherein sodium dodecylbenzenesulfonate is embedded in the interlayer of the modified organobentonite.

5. The boiler high-temperature resistant and anti-corrosion coating according to claim 1, characterized in that, The sphericity of the spherical nano-silicon carbide is 0.85-0.90; the sphericity of the hollow spherical alumina is 0.85-0.

90.

6. The boiler high-temperature resistant and anti-corrosion coating according to claim 1, characterized in that, The silane coupling agent is selected from any one of silane coupling agents KH-540, KH-550, KH-560, KH-570, and KH-580.

7. A method for preparing a high-temperature resistant and corrosion-resistant coating for boilers as described in any one of claims 1-6, characterized in that, The specific preparation steps include: Raw material preparation: Weigh each component according to the raw material composition; Primer preparation: After the epoxy-modified silane resin and xylene are stirred and dispersed evenly, composite filler, phosphate anti-rust pigment and fumed silica are added, and stirred and dispersed evenly to obtain the primer. Preparation of transition coating: After the epoxy-organosilicon copolymer resin and propylene glycol methyl ether are stirred and dispersed evenly, organobentonite, hollow spherical alumina and silane coupling agent are added and stirred and dispersed evenly to obtain a transition coating. Topcoat preparation: After the methylphenyl type organosilicon resin and xylene are stirred and dispersed evenly, spherical nano silicon carbide, flake nano aluminum powder, micron glass flakes and silane coupling agent are added and stirred and dispersed evenly to obtain the topcoat.

8. The method for preparing a high-temperature resistant and corrosion-resistant coating for boilers according to claim 7, characterized in that, The specific preparation steps also include: Preparation of epoxy-modified silane resin: Epoxy resin E-51 is added to the reactor, heated to 75-80℃, and vacuum dehydrated to remove residual moisture. Then, 10-15% of the mass of epoxy resin E-51 in anhydrous ethanol is added to obtain a premix. Methyltriethoxysilane, silane coupling agent KH-560 and tetrabutyl titanate are mixed and heated to 75-80℃. Then, 8-10% of the mass of methyltriethoxysilane and deionized water are added. After stirring and reacting, hydrolysate is obtained. After adjusting the pH of the premix to 5.0-6.0, the hydrolysate is added dropwise to the premix. After the addition is complete, the temperature is raised to 90℃ and kept at this temperature for 3-5 hours. Acetic acid is then added dropwise for neutralization, and ethanol and byproducts are removed by distillation to obtain epoxy-modified silane resin.

9. The method for preparing a high-temperature resistant and corrosion-resistant coating for boilers according to claim 7, characterized in that, The specific preparation steps also include: Preparation of epoxy-organosilicon copolymer resin: By weight, take 100-120 parts of epoxy resin E-51, 45-50 parts of methyl phenyl silicone resin, 12-15 parts of silane coupling agent KH-560, 1-3 parts of tetraisopropyl titanate, and 45-50 parts of xylene. Epoxy resin E-51 was added to the reactor, heated to 75-80℃, and vacuum dehydrated to remove residual moisture. Then, xylene was added to dilute the resin to obtain pretreated epoxy resin. After mixing methylphenyl silicone resin, silane coupling agent KH-560, and tetraisopropyl titanate, 3-5% (by weight of methylphenyl silicone resin) of deionized water was added dropwise. The mixture was stirred and reacted for 10-15 minutes at a pH of 5.0-5.2 to obtain the activated material. The activator is added dropwise to the pretreated epoxy resin, and the mixture is heated and reacted at 100-110℃ for 3-5 hours. Acetic acid is then added dropwise to neutralize the resin, and xylene is removed by distillation to obtain the epoxy-organosilicon copolymer resin.

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