Anticorrosive coating and preparation and use method thereof

Abstract

The present invention relates to an anti-corrosion coating and a method for preparing and using the same, belonging to the technical field of coating application. It solves one of the problems in the prior art that the anti-corrosion coating cannot be simultaneously resistant to high temperatures and corrosion, and cannot withstand high-temperature thermal shock. The present invention discloses a two-component anti-corrosion coating, wherein the composition of component one is as follows by mass: 20% to 30% polysiloxane, 15 to 25% phosphate-coated spherical aluminum powder, 10 to 20% silane-coated flaky aluminum powder, 1% to 2% functional additive, and the remainder is a diluent and other unavoidable impurities; component two is composed of modified polysilazane; the mass ratio of component one to component two is 100:10 to 15. The hybrid coating formed by this anti-corrosion coating has excellent properties of high-temperature resistance, corrosion resistance, and high-temperature thermal shock resistance. Parts treated with this coating can work for a long time in a high-temperature, corrosive environment, and are suitable for special application scenarios such as shipping and aviation.

Description

Technical Field

[0001] The present invention relates to the technical field of coating application, in particular to an anti-corrosion coating and a preparation and use method thereof, and in particular to an anti-corrosion coating resistant to thermal shock of high-temperature airflow and a preparation and use method thereof. Background Art

[0002] Key structural components such as offshore gas turbines and rocket launch towers need to withstand airflows at temperatures of 500°C to 700°C or even higher for a long time and repeatedly. At the same time, due to the presence of environmental media such as water, they are also faced with thermal shock impacts from rapid cooling media in high-temperature gaps. They face the dual damage of high temperature and corrosion, which is extremely destructive to the coating. The comprehensive performance of high-temperature anti-corrosion coatings plays a vital role in the operating life of the entire equipment.

[0003] Currently, various coatings in the existing technology cannot meet the comprehensive protection requirements in such special environments. Chinese patent application CN103614071B discloses an 800°C high-temperature resistant silicone anti-corrosion coating for pipe outer walls and its preparation method. The patent selects hydroxyl-containing methylphenyl silicone resin as the resin base material and utilizes the melting characteristics of low-melting-point glass frit at high temperatures to solve the problem of silicone coating decomposition at high temperatures and insufficient protection. At the same time, it has high-temperature resistance at the level of 850°C and can withstand salt spray for 1000 hours and UV artificial aging for 1000 hours. Chinese patent application CN103113768A discloses a high-temperature resistant coating for engine exhaust systems. The coating is formulated using silica sol or aluminum sol as the base material. It can withstand long-term baking at 800°C for 240 hours, as well as 240 hours of neutral salt spray and 72 hours of wet heat corrosion.

[0004] The coating materials formed by the existing technologies, including the above-mentioned two anti-corrosion coatings, have two independent properties of high temperature resistance and corrosion resistance, and cannot meet the performance requirements of comprehensive protection at the same time. That is, the degradation behavior of the coating after long-term high temperature resistance is often ignored. Even if the coating does not fall off after high temperature, it no longer has corrosion protection performance. This type of traditional coating also does not have the ability to withstand high-temperature thermal shock. Once it undergoes rapid cooling, the coating is easy to peel off and fail. In addition, the high-temperature resistant coating needs to be heated for complete curing, which greatly limits its applicability in large-scale parts and open-air operations. Summary of the Invention

[0005] In view of the above analysis, the embodiments of the present invention aim to provide an anti-corrosion coating that is resistant to high-temperature airflow thermal shock and its preparation and use method, so as to solve one of the problems in the prior art that the anti-corrosion coating cannot be simultaneously resistant to high temperature and corrosion, does not have high-temperature thermal shock resistance, and is difficult under normal temperature conditions.

[0006] The invention discloses a two-component anti-corrosion coating, comprising a first component and a second component; the first component comprises, by mass, 20% to 30% of polysiloxane, 15% to 25% of phosphate-coated spherical aluminum powder, 10% to 20% of silane-coated flaky aluminum powder, 1% to 2% of a functional additive, and the remainder is a diluent and other inevitable impurities; the second component comprises modified polysilazane; and the mass ratio of the first component to the second component is 100:10 to 15.

[0007] Specifically, the polysiloxane is a phenyl-methylsiloxane copolymer, and the terminal groups are one or more of amino, epoxy, carboxyl, and double bonds.

[0008] Specifically, the number average molecular weight of the polysiloxane is 10,000 to 20,000.

[0009] Specifically, the phosphate in the phosphate-coated spherical aluminum powder is one of dodecyl phosphate, octadecyl phosphate, octylphenol polyoxyethylene ether phosphate and 2-ethylhexyl phosphate.

[0010] Specifically, the particle size distribution of the phosphate-coated spherical aluminum powder is as follows: 2 μm to 5 μm is 10% to 15% by mass, 10 μm to 15 μm is 30% to 50% by mass, and 30 μm to 40 μm is 35% to 50% by mass, and the total of the three is 100%.

[0011] Specifically, the silane in the silane-coated flaky aluminum powder is one of 3-aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethylsilane, and 3-(methacryloyloxy)propyltrimethoxysilane.

[0012] Specifically, the diluent is one or more of xylene, butyl acetate, ethyl acetate, methyl isobutyl ketone, methyl isoamyl ketone, and propylene glycol methyl ether acetate.

[0013] Specifically, the modified polysilazane base structure is The R1 and R2 groups are one or more of methyl, ethyl, vinyl, benzene, and hydrogen, the end-capping is amino or carboxyl, and the number average molecular weight is 2000-3000.

[0014] The present invention also discloses a method for preparing the above-mentioned anti-corrosion coating, comprising the following steps:

[0015] S1: Preparation of phosphate-coated spherical aluminum powder and silane-coated flake aluminum powder;

[0016] S2: Weigh polysiloxane, spherical coated aluminum powder, flake coated aluminum powder, functional additives and diluent according to a preset mass ratio;

[0017] S3: adding a functional additive, spherical coated aluminum powder, flake coated aluminum powder and a diluent to the polysiloxane in sequence, and dispersing at high speed to obtain a mixture, i.e., component 1;

[0018] S4: Prepare polysilazane, i.e. component 2.

[0019] The present invention also discloses a method for using the anti-corrosion coating, comprising the following steps:

[0020] S1: Mix component 1 and component 2 in a preset ratio, stir evenly, and adjust the viscosity of the paint with a thinner until it reaches a viscosity suitable for spraying or brushing;

[0021] S2: Use a spray gun or paint brush to apply paint on the surface of the substrate that needs protection. After reaching the required thickness, dry it at room temperature for 3 to 5 days to obtain an anti-corrosion coating that is resistant to high-temperature airflow and thermal shock.

[0022] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0023] a) The coating structure can be kept stable for a long time under high temperature environment. The present invention adopts a composite composition formula of polysilazane, polysiloxane and surface modified aluminum powder to realize the establishment of an organic-inorganic hybrid coating, which can greatly improve the coating's resistance to high-temperature airflow thermal shock and corrosion protection, and more effectively ensure the reliability of the high-temperature operating substrate. Polysilazane and polysiloxane have good temperature resistance as film-forming substances and are not easy to decompose under high temperature conditions. At the same time, polysiloxane has excellent corrosion resistance and strong adhesion, which can effectively prevent the substrate from being corroded. Spherical aluminum powder and flaky aluminum powder are introduced into the coating system to increase the contact points of the two aluminum powders and improve the overall corrosion resistance of the coating. At the same time, aluminum powder has higher ductility in high temperature environment, and can balance the internal stress of the coating in extreme temperature environment, so that the coating does not crack or fall off. Polysilazane is used as a film-forming component to copolymerize with polysiloxane to replace the organic chain segments in polysiloxane, thereby improving the temperature resistance of the overall chemical structure of the coating. It still has a quality retention rate of more than 90% after high temperatures of 600℃ to 700℃.

[0024] b) Excellent corrosion resistance. Using phosphate-coated and silane-coated aluminum powder as the filler phase, through innovatively designed ratios and diameter coupling, the coating achieves sufficient stacking of cathodic protection fillers. The phosphate-coated surface treatment significantly slows the corrosion rate of the aluminum phase, thereby greatly extending the protective life of the substrate. The silane coating improves the compatibility of the flaky aluminum powder with the film-forming material, allowing it to be fully dispersed and exert the dual functions of dielectric barrier and anodic self-sacrifice.

[0025] c) Excellent thermal shock resistance. The polysilazane-polysiloxane coating, prepared according to the designed ratio, matches the thermal expansion coefficient of the metal at high temperatures and can maintain a highly consistent shrinkage rate with the substrate under repeated rapid cooling. The addition of aluminum powder of different particle sizes further balances the coating's heat, eliminates internal stress, and prevents cracking, thereby demonstrating unique thermal shock resistance not found in ordinary high-temperature resistant coatings.

[0026] d) The preparation conditions are mild, suitable for large-scale production, and the cost is controllable. It does not require the high-temperature baking process of traditional polysiloxane coatings, greatly simplifying the process and is suitable for coating and protective coating of large parts.

[0027] e) Curing can be achieved at room temperature without heating, significantly expanding the application environment of this anti-corrosion coating and simplifying the use process. And because the two components take effect after mixing (forming a cross-linked structure), component one and component two are not easy to cure when stored separately, making it easier to store and transport.

[0028] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0030] Figure 1 This is a flow chart of the preparation method for coating spherical aluminum powder;

[0031] Figure 2 This is a flow chart of the preparation method for coating flaky aluminum powder;

[0032] Figure 3 This is a flow chart of the preparation and use of anti-corrosion coatings. DETAILED DESCRIPTION

[0033] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0034] The invention discloses a two-component anti-corrosion coating. The composition of component one is as follows by mass: 20% to 30% of polysiloxane, 15% to 25% of phosphate-coated spherical aluminum powder, 10% to 20% of silane-coated flaky aluminum powder, 1% to 2% of functional additives, and the balance is a diluent and other inevitable impurities; component two is composed of modified polysilazane; and the mass ratio of component one to component two is 100:10 to 15.

[0035] The specific functions and content ranges of each component are selected based on the following:

[0036] Polysiloxane: Its main chain structure is a phenyl-methylsiloxane copolymer, with end groups consisting of one or more of amino, epoxy, carboxyl, and double bonds. For example, when the end groups are hydroxyl groups, the silamine groups in the polysilazane molecular chain can undergo a deamination reaction with the silanol groups on the siloxane chain, resulting in a cross-linking reaction. The removal of the silanol groups in the cross-linked macromolecular network provides improved heat resistance, with a quality retention rate exceeding 90% at high temperatures. A polysiloxane content of less than 20% will result in incomplete coating of spherical and flake aluminum powders, preventing the formation of a continuous, complete paint film. Excessive content will result in material waste and reduced overall protective performance of the final paint film.

[0037] Phosphate-coated spherical aluminum powder: Aluminum powder coating has two advantages: 1. It prevents aluminum powder from oxidizing. Oxidized aluminum powder has low activity and is difficult to play the role of sacrificial anode to protect the substrate; 2. The coated aluminum powder is easier to disperse in the resin matrix, which is beneficial to the uniformity of the coating and improves the corrosion resistance of the coating. Spherical aluminum powder and flake aluminum powder have lower electrode potential and can protect the substrate with higher electrode potential.

[0038] Silane-coated aluminum flakes: Silane-coated aluminum flakes prevent oxidation and improve dispersion within the matrix. Selecting a particle size between 30-40 μm enhances the mechanical properties and durability of the coating. Larger particle sizes hinder application and can result in poor surface finish after spraying. After spraying, the flakes are distributed in layers within the coating due to surface tension. The addition of spherical aluminum powder connects the aluminum powder between layers and fills the gaps between layers, increasing contact points between the powders.

[0039] The addition amounts of spherical and flake aluminum powders are interrelated. Excessive spherical aluminum powder content will reduce the coating's physical barrier effect, increase permeability to corrosive media, and reduce corrosion resistance. Excessive flake aluminum powder content will reduce the amount of spherical aluminum powder added, resulting in fewer contact points between the flakes in the coating, an inability to form a complete conductive path between the coatings, and reduced resistance to corrosive media.

[0040] According to experimental results, the comprehensive corrosion resistance is best when the addition amount of phosphate-coated spherical aluminum powder is 15-25% and the addition amount of silane-coated flake aluminum powder is 10-20%.

[0041] Functional additives: A mixture of dispersing agents and leveling agents. The main function of dispersing agents is to change the viscosity of the coating, delay the precipitation of solid components such as pigments and fillers, and improve the storage stability of the coating. Leveling agents mainly improve the gloss and smoothness of the coated surface, improving coating efficiency and quality. Excessive addition of dispersing agents and leveling agents will lead to reduced stability of the coating; too little addition will lead to uneven dispersion of the filler, pinholes in the coating, and reduced gloss and physical properties. For example, a mixture of dispersing agent TEGO Dispers670 and leveling agent BYK310 can be used.

[0042] Thinner: Adjusts the viscosity of the paint, facilitates the uniform dispersion of the components and improves the spraying process.

[0043] Modified polysilazane: The silanamine groups in its molecular chain react with the silanol groups on the siloxane chain to produce a crosslinking reaction, which allows for complete room-temperature curing without a catalyst. The stable crosslinking structure of polysilazane inhibits degradation caused by the terminal hydroxyl groups in siloxanes at high temperatures, thereby enhancing the stability of the siloxane crosslinking network and improving heat resistance.

[0044] When the ratio of component one to component two is 100:10-15, it is conducive to the cross-linking of polysiloxane and modified polysilazane, and the formed skeleton structure is relatively stable.

[0045] Specifically, the polysiloxane is a phenyl-methylsiloxane copolymer, and the terminal groups are one or more of amino, epoxy, carboxyl, and double bonds.

[0046] Specifically, the number average molecular weight of the polysiloxane is 10,000 to 20,000. Resins within this molecular weight range are easy to handle and have suitable viscosity.

[0047] Specifically, the phosphate ester in the phosphate-coated spherical aluminum powder is one of dodecyl phosphate, octadecyl phosphate, octylphenol polyoxyethylene ether phosphate, and 2-ethylhexyl phosphate. The phosphate groups react with oxides on the surface of the aluminum powder to form chemical bonds, tightly binding the phosphate ester to the aluminum powder and providing a coating. Furthermore, these four phosphates interact with the aluminum powder through van der Waals forces and hydrogen bonds, enhancing the stability of the coating.

[0048] Specifically, the particle size distribution of the phosphate-coated spherical aluminum powder is as follows: 10% to 15% for 2-5μm, 30% to 50% for 10-15μm, and 35% to 50% for 30-40μm, with the total of these three distributions adding up to 100%. This particle size distribution helps increase the number of contact points between the flaky aluminum powder at different depth gradients, achieving sufficient stacking of the flaky aluminum powder, which helps improve the overall corrosion resistance of the coating (i.e., an inappropriate particle size distribution of the spherical aluminum powder will result in insufficient contact between the flaky aluminum powder). Furthermore, under high-temperature conditions, the incorporation of aluminum powder of different particle sizes further balances the coating's heat, eliminates internal stress in the coating, and prevents cracking, thereby enhancing the coating's thermal shock resistance.

[0049] Specifically, the flaky coated aluminum powder is silane-coated aluminum powder, and the silane is one of 3-aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethylsilane, and 3-(methacryloyloxy)propyltrimethoxysilane. The aluminum powder coated with the silane has further improved corrosion resistance.

[0050] Specifically, the diluent is one or more of xylene, butyl acetate, ethyl acetate, methyl isobutyl ketone, methyl isoamyl ketone, and propylene glycol methyl ether acetate. These diluents do not react with the film-forming components and can adjust the viscosity of the coating, making it easier to store / transport or achieving a viscosity suitable for spraying / brushing.

[0051] Specifically, the modified polysilazane base structure is The R1 and R2 groups are one or more of methyl, ethyl, vinyl, benzene, and hydrogen, and the end capping is amino or carboxyl. The number average molecular weight is 2000 to 3000. The modified polysilazane of this molecular weight has a suitable viscosity and is easy to handle.

[0052] The present invention also discloses a method for preparing the above-mentioned anti-corrosion coating, comprising the following steps:

[0053] S1: Preparation of phosphate-coated spherical aluminum powder and silane-coated flake aluminum powder;

[0054] S2: Weigh polysiloxane, spherical coated aluminum powder, flake coated aluminum powder, functional additives and diluent according to a preset mass ratio;

[0055] S3: adding a functional additive, spherical coated aluminum powder, flake coated aluminum powder and a diluent to the polysiloxane in sequence, and dispersing at high speed to obtain a mixture, i.e., component 1;

[0056] S4: Prepare polysilazane, i.e. component 2.

[0057] Specifically, the specific operation of preparing phosphate-coated spherical aluminum powder in step S1 is as follows: weigh an appropriate amount of spherical aluminum powder with different particle size distributions, weigh butanone at a mass ratio of (0.1-1):100 and mix, fill with nitrogen, stir at 80°C-100°C, slowly add phosphate, the mass ratio of phosphate to aluminum powder is 1:10, condense and reflux for 8h-12h, take the precipitate after centrifugation, and repeatedly wash it with butanone for more than 3 times to obtain spherical coated aluminum powder. The above-mentioned aluminum powder-butanone mass ratio of the feed can ensure sufficient dispersion and coating of the aluminum powder. In actual operation, an aluminum powder-butanone mass ratio of 1:100 can be used to avoid wasting solvent; the reaction temperature should not be too high to avoid uncontrollable side reactions.

[0058] Specifically, the specific operation of preparing silane-coated flaky aluminum powder in step S1 is: weighing water and ethanol in a mass ratio of 2:98 and mixing, weighing an appropriate amount of flaky aluminum powder, and adding silane and flaky aluminum powder to the solution in a mass ratio of 1:10, stirring at 80°C to 100°C, condensing and refluxing for 8h to 12h, taking the precipitate after centrifugation, and repeatedly washing it with ethanol for more than 3 times to obtain silane-coated flaky aluminum powder.

[0059] Specifically, the specific operation of step S3 is to add functional additives, spherical coated aluminum powder, flake coated aluminum powder and diluent to polysiloxane in sequence, and disperse them at a high speed of 1000rpm to 1500rpm until the paint fineness is less than 40μm to obtain a mixture, i.e. component one.

[0060] Specifically, the polysilazane in step S5 can be purchased according to the required parameters.

[0061] The present invention also discloses a method for using the anti-corrosion coating, comprising the following steps:

[0062] S1: Mix component 1 and component 2 in a preset ratio, stir evenly, and adjust the viscosity of the paint with a thinner until it reaches a viscosity suitable for spraying or brushing;

[0063] S2: Use a spray gun or paint brush to apply paint on the surface of the substrate that needs protection. After reaching the required thickness, dry it at room temperature for 3 to 5 days to obtain an anti-corrosion coating that is resistant to high-temperature airflow and thermal shock.

[0064] Specifically, the diluent is one or more of xylene, butyl acetate, ethyl acetate, methyl isobutyl ketone, methyl isoamyl ketone, and propylene glycol methyl ether acetate. These diluents do not react with the film-forming components and can adjust the viscosity of the coating, making it easier to store / transport or achieving a viscosity suitable for spraying / brushing.

[0065] Example 1

[0066] 1. Spherical aluminum powder coating: Weigh 15g of aluminum powder with an average particle size of 2μm to 5μm, 70g of aluminum powder with an average particle size of 10μm to 15μm, and 65g of aluminum powder with an average particle size of 30μm to 40μm, weigh 15000g of butanone and mix them, fill with nitrogen, stir at 80℃, slowly add 15g of dodecyl phosphate, condense and reflux for 12h, centrifuge and collect the precipitate, and wash it repeatedly with butanone for more than 3 times to obtain spherical coated aluminum powder;

[0067] 2. Flake aluminum powder coating: Weigh 1960g of ethanol and 40g of water and mix them, add 20g of 3-aminopropyltriethoxysilane and 200g of ball-milled flaky aluminum powder, stir at 100°C, condense and reflux for 8h, centrifuge and collect the precipitate, and repeatedly wash it with ethanol for more than 3 times to obtain flaky coated aluminum powder;

[0068] 3. Prepare (purchase) polysilazane;

[0069] 4. Ingredients: weigh 300g polysiloxane, 150g spherical coated aluminum powder, 200g flake coated aluminum powder, 10g dispersing agent TEGO Dispers670, 5g leveling agent BYK310, 150g xylene, 130g butyl acetate and 55g propylene glycol methyl ether acetate;

[0070] 5. Dispersion: Add dispersing agent, leveling agent, xylene, butyl acetate, propylene glycol methyl ether acetate, spherical coated aluminum powder and flake coated aluminum powder to polysiloxane in sequence, and disperse at a high speed of 1500 rpm until the paint fineness is less than 40 μm to obtain component 1;

[0071] 6. Paint mixing: Mix component 1 and component 2 in a mass ratio of 100:10, stir manually until evenly mixed, and adjust the viscosity of the paint with xylene until it reaches a sprayable viscosity;

[0072] 7. Coating: Use a spray gun to coat the surface of the Q235 steel substrate to a thickness of 60μm to 70μm and then dry it at room temperature for 3 days to obtain an anti-corrosion coating that is resistant to high-temperature airflow thermal shock.

[0073] After testing, the coating can withstand 21 repeated impacts of 650°C and seawater for 10 minutes respectively without damage or corrosion. After 168 hours of continuous high temperature at 650°C, the coating is intact with an adhesion of 18.80MPa.

[0074] Example 2

[0075] 1. Spherical aluminum powder coating: Weigh 30g of aluminum powder with an average particle size of 2μm to 5μm, 70g of aluminum powder with an average particle size of 10μm to 15μm, and 100g of aluminum powder with an average particle size of 30μm to 40μm, weigh 20,000g of butanone, mix them, fill with nitrogen, stir at 80°C, slowly add 20g of dodecyl phosphate, condense and reflux for 12h, centrifuge, take the precipitate, and repeatedly wash it with butanone for more than 3 times to obtain spherical coated aluminum powder;

[0076] 2. Flake aluminum powder coating: Weigh 1960g of ethanol and 40g of water and mix them, add 20g of 3-aminopropyltriethoxysilane and 200g of ball-milled flaky aluminum powder, stir at 100°C, condense and reflux for 8h, centrifuge and collect the precipitate, and repeatedly wash it with ethanol for more than 3 times to obtain flaky coated aluminum powder;

[0077] 3. Prepare (purchase) polysilazane, i.e. component 2;

[0078] 4. Ingredients: weigh 270g polysiloxane, 200g spherical coated aluminum powder, 200g flake coated aluminum powder, 10g dispersing aid TEGO Dispers670, 5g leveling agent BYK310, 130g xylene, 130g butyl acetate and 55g propylene glycol methyl ether acetate;

[0079] 5. Dispersion: Add dispersing agent, leveling agent, xylene, butyl acetate, propylene glycol methyl ether acetate, spherical coated aluminum powder and flake coated aluminum powder to polysiloxane in sequence, and disperse at a high speed of 1500 rpm until the paint fineness is less than 40 μm to obtain component 1;

[0080] 6. Paint mixing: Mix component 1 and component 2 in a mass ratio of 100:12, stir manually until evenly mixed, and adjust the paint viscosity with xylene until it reaches a sprayable viscosity;

[0081] 7. Coating: Use a spray gun to coat the surface of the Q235 steel substrate to a thickness of 60μm to 70μm and then dry it at room temperature for 3 days to obtain an anti-corrosion coating that is resistant to high-temperature airflow thermal shock.

[0082] After testing, the coating can withstand repeated impacts of 650°C and seawater for 10 minutes each without being damaged or corroded. After 144 hours of continuous high temperature at 650°C, the coating is intact with an adhesion of 16.87MPa.

[0083] Example 3

[0084] 1. Spherical aluminum powder coating: Weigh 35g of aluminum powder with an average particle size of 2μm to 5μm, 125g of aluminum powder with an average particle size of 10μm to 15μm, and 90g of aluminum powder with an average particle size of 30μm to 40μm, weigh 25000g of butanone and mix them, fill with nitrogen, stir at 80℃, slowly add 25g of dodecyl phosphate, condense and reflux for 12h, centrifuge and collect the precipitate, and wash it repeatedly with butanone for more than 3 times to obtain spherical coated aluminum powder;

[0085] 2. Flake aluminum powder coating: Weigh 980g of ethanol and 20g of water and mix them, add 10g of 3-aminopropyltriethoxysilane and 100g of ball-milled flaky aluminum powder, stir at 100°C, condense and reflux for 8h, centrifuge and collect the precipitate, and repeatedly wash it with ethanol for more than 3 times to obtain flaky coated aluminum powder;

[0086] 3. Prepare (purchase) polysilazane, i.e. component 2;

[0087] 4. Ingredients: weigh 240g polysiloxane, 250g spherical coated aluminum powder, 100g flake coated aluminum powder, 15g dispersing aid TEGO Dispers670, 5g leveling agent BYK310, 200g xylene, 130g butyl acetate and 60g propylene glycol methyl ether acetate;

[0088] 5. Dispersion: Add dispersing agent, leveling agent, xylene, butyl acetate, propylene glycol methyl ether acetate, spherical coated aluminum powder and flake coated aluminum powder to polysiloxane in sequence, and disperse at a high speed of 1500 rpm until the paint fineness is less than 40 μm to obtain component 1;

[0089] 6. Paint mixing: Mix component 1 and component 2 in a mass ratio of 100:12, stir manually until evenly mixed, and adjust the paint viscosity with xylene until it reaches a sprayable viscosity;

[0090] 7. Painting: Use a spray gun to paint on the surface of Q235 steel substrate to a thickness of 60μm to 70μm and then dry it at room temperature for 5 days to obtain an anti-corrosion coating that is resistant to high-temperature airflow thermal shock.

[0091] After testing, the coating can withstand 24 repeated impacts of 650°C and seawater for 10 minutes respectively without damage or corrosion. After 144 hours of continuous high temperature at 650°C, the coating is intact with an adhesion of 17.45MPa.

[0092] Example 4

[0093] 1. Spherical aluminum powder coating: Weigh 20g of aluminum powder with an average particle size of 2μm to 5μm, 70g of aluminum powder with an average particle size of 10μm to 15μm, and 60g of aluminum powder with an average particle size of 30μm to 40μm, weigh 15000g of butanone and mix them, fill with nitrogen, stir at 80℃, slowly add 15g of dodecyl phosphate, condense and reflux for 12h, centrifuge and collect the precipitate, and wash it repeatedly with butanone for more than 3 times to obtain spherical coated aluminum powder;

[0094] 2. Flake aluminum powder coating: Weigh 1470g of ethanol and 30g of water and mix them, add 15g of 3-aminopropyltriethoxysilane and 150g of ball-milled flaky aluminum powder, stir at 100°C, condense and reflux for 8h, centrifuge and collect the precipitate, and repeatedly wash it with ethanol for more than 3 times to obtain flaky coated aluminum powder;

[0095] 3. Prepare (purchase) polysilazane, i.e. component 2;

[0096] 4. Ingredients: weigh 300g polysiloxane, 150g spherical coated aluminum powder, 150g flake coated aluminum powder, 15g dispersing aid TEGO Dispers670, 5g leveling agent BYK310, 160g xylene, 130g butyl acetate and 90g propylene glycol methyl ether acetate;

[0097] 5. Dispersion: Add dispersing agent, leveling agent, xylene, butyl acetate, propylene glycol methyl ether acetate, spherical coated aluminum powder and flake coated aluminum powder to polysiloxane in sequence, and disperse at a high speed of 1500 rpm until the paint fineness is less than 40 μm to obtain component 1;

[0098] 6. Paint mixing: Mix component 1 and component 2 in a mass ratio of 100:15, stir manually until evenly mixed, and adjust the viscosity of the paint with xylene until it reaches a sprayable viscosity;

[0099] 7. Painting: Use a spray gun to paint on the surface of Q235 steel substrate to a thickness of 60μm to 70μm and then dry it at room temperature for 5 days to obtain an anti-corrosion coating that is resistant to high-temperature airflow thermal shock.

[0100] After testing, the coating can withstand repeated impacts of 650°C and seawater for 10 minutes each for 25 times without damage or corrosion. After 144 hours of continuous high temperature at 650°C, the coating is intact with an adhesion of 18.76MPa.

[0101] Comparative Example 1

[0102] 1. Spherical aluminum powder coating: Weigh 10g of aluminum powder with an average particle size of 2μm to 5μm, 50g of aluminum powder with an average particle size of 10μm to 15μm, and 40g of aluminum powder with an average particle size of 30μm to 40μm, weigh 10000g of butanone and mix them, fill with nitrogen, stir at 80℃, slowly add 10g of dodecyl phosphate, condense and reflux for 12h, centrifuge and collect the precipitate, and wash it repeatedly with butanone for more than 3 times to obtain spherical coated aluminum powder;

[0103] 2. Flake aluminum powder coating: Weigh 2450g of ethanol and 50g of water and mix them, add 25g of 3-aminopropyltriethoxysilane and 250g of ball-milled flaky aluminum powder, stir at 100°C, condense and reflux for 8h, centrifuge and collect the precipitate, and repeatedly wash it with ethanol for more than 3 times to obtain flaky coated aluminum powder;

[0104] 3. Prepare (purchase) polysilazane, i.e. component 2;

[0105] 4. Ingredients: weigh 300g polysiloxane, 100g spherical coated aluminum powder, 250g flake coated aluminum powder, 10g dispersing aid TEGO Dispers670, 5g leveling agent BYK310, 150g xylene, 130g butyl acetate and 55g propylene glycol methyl ether acetate;

[0106] 5. Dispersion: Add dispersing agent, leveling agent, xylene, butyl acetate, propylene glycol methyl ether acetate, spherical coated aluminum powder and flake coated aluminum powder to polysiloxane in sequence, and disperse at a high speed of 1500 rpm until the paint fineness is less than 40 μm to obtain component 1;

[0107] 6. Paint mixing: Mix component 1 and component 2 in a mass ratio of 100:10, stir manually until evenly mixed, and adjust the viscosity of the paint with xylene until it reaches a sprayable viscosity;

[0108] 7. Coating: Use a spray gun to coat the surface of the Q235 steel substrate to a thickness of 60μm to 70μm and then dry it at room temperature for 3 days to obtain an anti-corrosion coating that is resistant to high-temperature airflow thermal shock.

[0109] After testing, the coating can withstand repeated impacts of 650°C and seawater for 10 minutes each for 15 times without damage or corrosion. After 144 hours of continuous high temperature at 650°C, the coating is intact with an adhesion of 13.22MPa.

[0110] Comparative Example 2

[0111] 1. Flake aluminum powder coating: Weigh 3430g of ethanol and 70g of water and mix them, add 35g of 3-aminopropyltriethoxysilane and 350g of ball-milled flaky aluminum powder, stir at 100°C, condense and reflux for 8h, centrifuge and collect the precipitate, and repeatedly wash it with ethanol for more than 3 times to obtain flaky coated aluminum powder;

[0112] 2. Prepare (purchase) polysilazane, i.e. component 2;

[0113] 3. Ingredients: weigh 300g polysiloxane, 350g flaky coated aluminum powder, 10g dispersing aid TEGO Dispers670, 5g leveling agent BYK310, 150g xylene, 130g butyl acetate and 55g propylene glycol methyl ether acetate;

[0114] 4. Dispersion: Add dispersing agent, leveling agent, xylene, butyl acetate, propylene glycol methyl ether acetate, spherical coated aluminum powder and flake coated aluminum powder to polysiloxane in sequence, and disperse at a high speed of 1500 rpm until the paint fineness is less than 40 μm to obtain component 1;

[0115] 5. Paint mixing: Mix component 1 and component 2 in a mass ratio of 100:10, stir manually until evenly mixed, and adjust the viscosity of the paint with xylene until it reaches a sprayable viscosity;

[0116] 6. Painting: Use a spray gun to paint on the surface of Q235 steel substrate to a thickness of 60μm to 70μm and then dry at room temperature for 3 days to obtain an anti-corrosion coating that is resistant to high-temperature airflow thermal shock.

[0117] After testing, the coating can withstand repeated impacts of 650°C and seawater for 10 minutes each for 10 times without damage or corrosion. After 96 hours of continuous high temperature at 650°C, the coating is intact with an adhesion of 7.56MPa.

[0118] Compared with Examples 1 to 4, the content of spherical aluminum powder in Comparative Example 1 is lower than the specified value, and the content of flaky aluminum powder is higher than the set value, resulting in the corrosion medium penetrating into the shrinkage holes of the coating during thermal shock. The defects of the coating will be rapidly amplified after multiple thermal shock shocks. After 15 thermal shock shocks, the coating will eventually fall off and fail.

[0119] Compared to Examples 1-4, Comparative Example 2 omitted the spherical aluminum powder, resulting in difficulty in coating dispersion. Furthermore, the flaky aluminum powder absorbed a large amount of oil, preventing it from being fully encapsulated during film formation. After 10 repeated washes, the coating exhibited slagging and localized cracking. The discontinuity of the resin also reduced coating adhesion.

[0120] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A two-component anti-corrosion coating, characterized by: It includes component one and component two; The composition of the component 1 is as follows by mass: 20% to 30% polysiloxane, 15% to 25% phosphate-coated spherical aluminum powder, 10% to 20% silane-coated flake aluminum powder, 1% to 2% functional additive, and the balance is diluent and other inevitable impurities; The second component is composed of modified polysilazane; The mass ratio of the component one to the component two is 100:10-15.

2. The anticorrosive coating according to claim 1, wherein: The polysiloxane is a phenyl-methylsiloxane copolymer, and the terminal groups are one or more of amino, epoxy, carboxyl and double bonds.

3. The anti-corrosion coating according to claim 1, characterized in that: The number average molecular weight of the polysiloxane is 10,000 to 20,000.

4. The anti-corrosion coating according to claim 1, characterized in that: The phosphate in the phosphate-coated spherical aluminum powder is one of dodecyl phosphate, octadecyl phosphate, octylphenol polyoxyethylene ether phosphate and 2-ethylhexyl phosphate.

5. The anti-corrosion coating according to claim 1, characterized in that: The particle size distribution of the phosphate-coated spherical aluminum powder is as follows: 2μm-5μm accounts for 10%-15% by mass, 10μm-15μm accounts for 30%-50% by mass, 30μm-40μm accounts for 35%-50% by mass, and the total of the three is 100%.

6. The anti-corrosion coating according to claim 1, characterized in that: The silane in the silane-coated flaky aluminum powder is one of 3-aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethylsilane and 3-(methacryloyloxy)propyltrimethoxysilane.

7. The anti-corrosion coating according to claim 1, characterized in that: The diluent is one or more of xylene, butyl acetate, ethyl acetate, methyl isobutyl ketone, methyl isoamyl ketone, and propylene glycol methyl ether acetate.

8. The anti-corrosion coating according to claim 1, characterized in that: The basic structure of the modified polysilazane is The R1 and R2 groups are one or more of methyl, ethyl, vinyl, benzene, and hydrogen, the end-capping is amino or carboxyl, and the number average molecular weight is 2000-3000.

9. A method for preparing the anticorrosive coating according to any one of claims 1 to 8, characterized in that: S1: Preparation of phosphate-coated spherical aluminum powder and silane-coated flake aluminum powder; S2: Weigh polysiloxane, spherical coated aluminum powder, flake coated aluminum powder, functional additives and diluent according to a preset mass ratio; S3: adding a functional additive, spherical coated aluminum powder, flake coated aluminum powder and a diluent to the polysiloxane in sequence, and dispersing at high speed to obtain a mixture, i.e., component 1; S4: preparing modified polysilazane, i.e. component 2.

10. A method for using the anti-corrosion coating according to any one of claims 1 to 8 or the anti-corrosion coating prepared by the preparation method according to claim 9, characterized in that: The following steps are involved: S1: Mix component 1 and component 2 in a preset ratio, stir evenly, and adjust the viscosity of the paint with a thinner until it reaches a viscosity suitable for spraying or brushing; S2: Use a spray gun or paint brush to apply paint on the surface of the substrate that needs protection. After reaching the required thickness, dry it at room temperature for 3 to 5 days to obtain an anti-corrosion coating that is resistant to high-temperature airflow and thermal shock.

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