Organosilicon-phosphate interpenetrating network coating as well as preparation method and spraying method thereof

Abstract

The invention relates to the technical field of high-temperature-corrosion-resistant protective coatings, in particular to an organic silicon-phosphate interpenetrating network coating as well as a preparation method and a spraying method thereof. The coating comprises the following components in parts by mass: a component A, namely an organic silicon prepolymer, a component B, namely a modified rare earth-functional filler, a component C, namely an inorganic phosphate solution and a component D, namely a water-based curing accelerator, wherein the mass ratio of A to B to C is (30-40): (40-50): (10-20), and D is 1% of the total mass of A, B and C. A flexible organic silicon network and a rigid phosphate network are interpenetrated in a molecular scale to form a Si-O-P-Al-M (M is rare earth, Mg and Zn) hybrid skeleton; meanwhile, rare earth oxide / silicate is introduced to serve as a high-temperature self-healing pinning phase, and rare earth oxygen vacancies are utilized to migrate at high temperature to seal and fill microcracks; a sol-gel and secondary curing process is adopted, three-step gradient curing of normal-temperature condensation, medium-temperature organic crosslinking and high-temperature inorganic ceramization is achieved, and thermal stress is relieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-temperature corrosion-resistant protective coating, and particularly relates to an organic silicon-phosphate interpenetrating network coating, a preparation method thereof and a spraying method. BACKGROUND

[0002] The flue gas discharged by coal-fired power plants, steel sintering machines, waste incinerators and petrochemical cracking devices frequently fluctuates at a temperature of 150-750 DEG C, and is accompanied by and a large amount of dust, which causes thermal shock fatigue and chemical corrosion to the inner walls of metal flues and chimneys. The traditional pure organic silicon coating has a low high-temperature carbon residue rate, is easy to pulverize at a temperature above 800 DEG C, has poor long-term stability, and has insufficient corrosion resistance. The epoxy-organic silicon coating has excellent corrosion resistance, but has poor temperature resistance and thermal shock resistance. The inorganic phosphate coating has high temperature resistance but is brittle, and has a peeling area of greater than 30% after 50 thermal shocks. The organic-inorganic coating prepared by simple physical blending has poor interface compatibility, and the interface microcracks rapidly expand after cold and hot cycles. SUMMARY

[0003] The technical task of the present application is to provide a preparation method of an organic silicon-phosphate interpenetrating network (IPN) high-temperature flue gas corrosion-resistant coating in view of the deficiencies of the prior art. The specific technical method is that the "flexible organic silicon network" and the "rigid phosphate network" interpenetrate at the molecular scale to form a Si-O-P-Al-M (M=rare earth, Mg, Zn) hybrid skeleton. Meanwhile, rare earth oxides / silicates are introduced as "high-temperature self-healing pinning phases", and the rare earth oxygen vacancies are used to migrate and fill microcracks at high temperatures. The sol-gel+secondary curing process is adopted to realize three-step gradient curing of normal-temperature condensation, medium-temperature organic crosslinking and high-temperature inorganic ceramicization, so as to relieve thermal stress.

[0004] Specifically provided is an organic silicon-phosphate interpenetrating network coating, which comprises the following components in parts by mass: A component organic silicon prepolymer, B component modified rare earth-functionality filler, C component inorganic phosphate solution and D component water-based curing accelerator. The mass ratio of A:B:C is (30-40):(40-50):(10-20), and D is 1% of the total mass of A, B and C.

[0005] The A component (organic silicon prepolymer) comprises 10-20 parts of hydroxyl-terminated polydimethylsiloxane, 1-2 parts of vinyltrimethoxysilane (VTMS), 1-2 parts of gamma-aminopropyl triethoxysilane (KH-550), 0.1-0.5 parts of nano silica sol (10-30 nm, solid content 30%), 1-3 parts of ethylene glycol monobutyl ether, 0.2-0.5 parts of polyether-modified siloxane leveling agent (commercial BYK-333) and 1-10 parts of deionized water. The A component (organic silicon prepolymer) comprises 10-20 parts of hydroxyl-terminated polydimethylsiloxane, 1-2 parts of vinyltrimethoxysilane (VTMS), 1-2 parts of gamma-aminopropyl triethoxysilane (KH-550), 0.1-0.5 parts of nano silica sol (10-30 nm, solid content 30%), 1-3 parts of ethylene glycol monobutyl ether, 0.2-0.5 parts of polyether-modified siloxane leveling agent (commercial BYK-333) and 1-10 parts of deionized water.

[0006] B component (modified rare earth-functional filler, ≤5μm), including rare earth-functional filler and 3%wt silane coupling agent (KH-560) ethanol solution; wherein, the rare earth-functional filler, including flaky aluminum powder (particle size 10-20μm) 10-15 parts by weight; rare earth oxide at least one of, <100nm) 2-5 parts; ultra-fine ZnO (particle size <100nm, smoke suppression self-cleaning) 5-10 parts; zirconium powder (thermal shock buffer) 10-15 parts; silicon carbide whisker (cubic silicon carbide β-SiC, aspect ratio 10-20) 3-5 parts; copper chromium black (pigment) 8-10 parts; mica powder (aspect ratio ≥60) 8-10 parts; glass powder 10-15 parts; the amount of KH-560 is 1% of the total mass of rare earth-functional powder;

[0007] C component (inorganic phosphate solution): including aluminum dihydrogen phosphate solution (50%wt);

[0008] D component (aqueous curing accelerator): including triethanolamine aqueous solution (50%wt).

[0009] The application also provides a preparation method of the organic silicon-phosphate interpenetrating network coating, comprising the following steps,

[0010] Step 1: in-situ pre-polymerization of A component

[0011] at 60℃, under protection, stirring and mixing hydroxyl-terminated polydimethylsiloxane, VTMS, KH-550, nano sol, keeping warm for 2h to form organic-inorganic hybrid pre-polymer; cooling to 40℃, adding ethylene glycol monobutyl ether, polyether modified siloxane leveling agent and deionized water in turn to obtain A component;

[0012] Step 2: B component modified rare earth-functional filler

[0013] Mixing and stirring anhydrous ethanol and deionized water (mass ratio 4:1) uniformly, adding acetic acid dropwise to adjust PH to 4.0, and then adding KH560 slowly into the ethanol solvent to obtain 3%wt silane coupling agent (KH-560) ethanol solution.

[0014] Grinding the rare earth-functional filler to ≤5μm through powder grinding and mixing equipment, and then high-speed shearing with silane coupling agent (KH-560) ethanol solution for 30min, and drying at 80℃ to obtain B component surface modified rare earth-functional filler;

[0015] Step 3: IPN coating preparation

[0016] ​The mass ratio of A:B:C is (30-40):(40-50):(10-20), and the D component is 1% of the total of the A, B and C components.

[0017] Before field application, A:B:C are mixed in a mass ratio, and dispersed at 800 r / min for 10 min; the D component is added, and stirring is continued for 5 min, to obtain the silicone-phosphate interpenetrating network heat shock resistant high-temperature flue gas corrosion resistant coating; the coating is used after maturation for 15 min, and the pot life is 4 h.

[0018] According to another aspect of the present application, a spraying method of the silicone-phosphate interpenetrating network heat shock resistant high-temperature flue gas corrosion resistant coating is also provided, comprising the following steps,

[0019] Substrate treatment: dry sand blasting method is used for sand blasting treatment of the substrate; 24-46 mesh brown corundum (or quartz sand) is selected, and the outlet air pressure is 0.4-0.6 MPa; compressed air (degreased and dehumidified) is used to remove dust, debris and abrasives on the surface immediately after sand blasting; after dust removal, non-woven fabric or gauze soaked with alcohol is used to wipe the substrate; the dust and residual grease on the surface of the substrate are wiped off to achieve a surface cleanliness of Sa2.5, and spraying is performed within 2 h;

[0020] Spraying: the outlet pressure of the spray gun is adjusted to 0.4-0.6 MPa, and the above-mentioned coating is loaded for uniform spraying; the vertical distance between the spray gun nozzle and the surface to be sprayed is about 250 mm, and cross spraying is defined as one pass; the substrate is placed on a rotating table, and the rotating speed of the rotating table is 5-8 r / min.

[0021] 4. Curing process

[0022] After spraying is completed, curing can be performed at room temperature (above 20℃) for 5-7 days, or after curing at room temperature for 24 h, drying at 120℃ for 1 h can accelerate the curing. The silicone Si-OH and the phosphate P-OH are condensed to form a heat shock resistant high-temperature flue gas corrosion resistant coating layer with Si-O-P-Al-M bridge bonds, and the coating layer surface is uniform and smooth without cracks.

[0023] The film forming mechanism of the "silicone-phosphate interpenetrating network" in the present solution is as follows: the silicone resin serves as a flexible segment to provide flexibility and certain temperature resistance of the coating. The main component is the silicon-oxygen bond (Si-O) which has a high bond energy and can remain stable at high temperatures. The phosphate dehydrates and condenses at high temperatures to form a macromolecular network structure with aluminum phosphate as the skeleton, thus serving as a rigid segment to provide high temperature resistance and hardness. During film formation, the silicone resin and the phosphate form an interpenetrating network structure through chemical bonding. The flexible segment of the silicone resin is interlaced in the rigid network of the phosphate to form a whole. This structure retains the flexibility of the silicone and combines the high temperature resistance and high hardness characteristics of the phosphate. At the same time, the rare earth elements can react with the phosphate to form more stable compounds, filling the micropores and microcracks in the coating and preventing the penetration of corrosive media. The synergistic effect of the components gives the coating better corrosion resistance and temperature resistance, and also good thermal shock resistance.

[0024] Inorganic systems (such as silicates and phosphates used alone or in combination) are generally brittle and prone to cracking, because the thermal expansion coefficient of inorganic materials differs greatly from that of the metal matrix, and stress concentration is easily generated under thermal shock, leading to cracking of the coating. In the "silicone-phosphate interpenetrating network" coating, the flexible segment of the silicone resin can effectively relieve thermal stress and reduce stress concentration, thereby improving the flexibility and thermal shock resistance of the coating.

[0025] Organic coatings such as epoxy and acrylic resins are prone to thermal decomposition and aging at high temperatures, and have limited temperature resistance, generally not exceeding 300°C. In the "silicone-phosphate interpenetrating network" coating, the high temperature resistance of the phosphate can reach more than 1000°C, and the silicone resin begins to thermally decompose at 400-500°C. After the combination of the two, the temperature resistance and stability of the coating are significantly better than those of pure organic resin coatings.

[0026] Therefore, unlike the brittleness and cracking of the dual inorganic system, the present solution has better flexibility and thus better thermal shock resistance. Moreover, the temperature resistance and stability are better than those of organic resin coatings such as epoxy and acrylic, and the synergistic effect of the functional powder such as rare earth can achieve better corrosion resistance. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, those skilled in the art can obtain other drawings from these drawings without creative labor.

[0029] Figure 1 The schematic diagram of the photos of the coating adhesion test by grid method of the present application;

[0030] Figure 2 The schematic diagram of the photos of the coating after the temperature resistance test of 900℃ for 2h after spraying the coating of the present application;

[0031] Figure 3 The photos of the coating after the salt spray test of 1000h after spraying the coating of the present application;

[0032] Figure 4 The photos of the coating after the temperature resistance test of 750℃ for 30min, then taking out the test piece to room temperature and repeating 50 times. DETAILED DESCRIPTION

[0033] The exemplary embodiments will be described in detail herein with reference to the attached drawings. In the following description, like reference numerals refer to like elements, unless the context clearly dictates otherwise. The following exemplary embodiments described herein are not meant to represent all embodiments consistent with the present application. Rather, they are merely examples of systems consistent with some aspects of the present application as detailed in the appended claims.

[0034] The present application provides a silicone-phosphate interpenetrating network coating, comprising the following components by mass fraction:

[0035] A component (silicone prepolymer): comprising, hydroxyl-terminated polydimethylsiloxane 10-20 parts; vinyltrimethoxysilane (VTMS) 1-2 parts; γ-aminopropyltriethoxysilane (KH-550) 1-2 parts; nano sol (10-30nm, solid content 30%) 10-15 parts; ethylene glycol monobutyl ether 1-3 parts; polyether modified siloxane leveling agent (commercial BYK-333) 0.2-0.5 parts; deionized water 1-10 parts;

[0036] B component (modified rare earth-functional filler, ≤5μm), comprising rare earth-functional filler and 3%wt silane coupling agent (KH-560) ethanol solution; wherein, the rare earth-functional filler, by weight fraction, comprises flaky aluminum powder (particle size 10-20μm) 10-15 parts; rare earth oxide ( at least one of, <100 nm) 2-5 parts; ultrafine ZnO (particle size <100 nm, smoke suppression self-cleaning) 5-10 parts; zircon powder (thermal shock buffer) 10-15 parts; silicon carbide whisker (cubic silicon carbide β-SiC, aspect ratio 10-20) 3-5 parts; copper-chromium black (pigment) 8-10 parts; mica powder (aspect ratio ≥60) 8-10 parts; glass powder 10-15 parts; KH-560 is 1% of the total mass of rare earth-functional powder;

[0037] C component (organophosphate solution): includes aluminum dihydrogen phosphate solution (50%wt);

[0038] D component (aqueous curing accelerator): includes triethanolamine aqueous solution (50%wt).

[0039] The configuration mass ratio is A:B:C=(30-40):(40-50):(10-20), and the D component is 1% of the total mass of the A, B, and C components. The specific preparation method of the coating is as follows:

[0040] Example 1:

[0041] Step 1: In-situ pre-polymerization of A component

[0042] At 60°C, under protection, 15 parts of hydroxyl-terminated polydimethylsiloxane, 2 parts of VTMS, 1 part of KH-550, 10 parts of nano sol are stirred and mixed, and incubated for 2h to form an organic-inorganic hybrid prepolymer; cooled to 40°C, 1 part of ethylene glycol monobutyl ether, 0.2 parts of polyether modified siloxane leveling agent and 5.8 parts of deionized water are added in turn to obtain the A component.

[0043] Step 2: Surface modified rare earth-functional filler

[0044] 15 parts of aluminum powder, 2 parts of , 5 parts of zinc oxide, 10 parts of zircon powder, 3 parts of silicon carbide, and 10 parts of mica powder, 8 parts of copper-chromium black, and 10 parts of glass powder are ground to ≤5μm by a powder grinding and mixing device to obtain a rare earth-functional filler.

[0045] Take 1% of the total mass of the powder KH560 and slowly add it to a mixed solution of anhydrous ethanol and deionized water (mass ratio 4:1) (adjust the PH to 4.0 with acetic acid), stir well, and prepare a 3wt% silane coupling agent (KH-560) ethanol solution

[0046] High-speed shear the rare earth-functional powder with the above-mentioned 3wt% silane coupling agent (KH-560) ethanol solution for 30min at 80°C, and dry to obtain the B component modified rare earth functional filler.

[0047] Step 3: IPN coating preparation

[0048] Before field application, A:B:C were mixed at a mass ratio of 35:45:20, and dispersed at 800 r / min for 10 min; 1% triethanolamine aqueous solution (50%wt) was added, and stirring was continued for 5 min; after aging for 15 min (pot life 4 h), the coating was used.

[0049] Step 4: Spraying

[0050] The coating was sprayed on a carbon steel plate with sand blasting treatment to Sa2.5 level, with a dry film thickness of 180 μm, and self-dried at 23℃ for 7 d.

[0051] Performance test results:

[0052] Adhesion: Grade 1 or below (crosshatch method) with carbon steel;

[0053] Temperature resistance: 900℃ for 2 h, coating intact;

[0054] Thermal shock resistance: 750℃ for 30 min ↔ room temperature, 50 cycles, coating intact;

[0055] Salt spray resistance: 5% NaCl, 35℃, 1000 h, coating intact;

[0056] Acid dew resistance: 50℃, 20% +5% HCl mixed condensate, 30 d, no blistering, no rust spots.

[0057] Example 2:

[0058] Step 1: In-situ prepolymerization of A component

[0059] At 60℃, under protection, 15 parts of hydroxyl-terminated polydimethylsiloxane, 2 parts of VTMS, 1 part of KH-550, 10 parts of nano sol were stirred and mixed, and aged for 2 h to form an organic-inorganic hybrid prepolymer; the temperature was lowered to 40℃, and 1 part of ethylene glycol monobutyl ether, 0.2 parts of polyether-modified silicone leveling agent and 5.8 parts of deionized water were added in sequence to obtain the A component.

[0060] Step 2: Surface-modified rare earth-functional filler

[0061] 10 parts of aluminum powder, 2 parts of , 5 parts of zinc oxide, 15 parts of zirconium powder, 3 parts of silicon carbide and 10 parts of mica powder, 8 parts of copper-chromium black, and 15 parts of glass powder were ground to ≤5 μm by a powder grinding and mixing device to obtain a rare earth-functional filler.

[0062] Take 1% of the total mass of powder KH560 slowly into the mixed solution of anhydrous ethanol and deionized water (mass ratio 4:1) (adjust the PH to 4.0 with acetic acid), fully stir, and prepare 3wt% silane coupling agent (KH-560) ethanol solution

[0063] Shear the rare earth-functional powder and the silane coupling agent (KH-560) ethanol solution at high speed for 30 min, dry at 80℃, and obtain the modified rare earth functional filler of B component.

[0064] Step 3: IPN coating preparation

[0065] Before field application, mix A:B:C according to the mass ratio of 35:50:15, disperse at 800r / min for 10 min; add 1% triethanolamine aqueous solution (50%), continue stirring for 5 min, and use after aging for 15 min (pot life 4h).

[0066] Step 4: spray coating

[0067] Spray the coating on the carbon steel plate treated by sand blasting to reach Sa2.5 level, dry film thickness 200μm, and self-dry at 23℃×7d.

[0068] Performance test results:

[0069] Adhesion: adhesion to carbon steel below grade 1 (cross hatch method);

[0070] Temperature resistance: 900℃ for 2 hours, coating is intact;

[0071] Thermal shock resistance: 750℃×30min ↔ room temperature, 50 cycles, coating is intact;

[0072] Salt spray resistance: 5% NaCl, 35℃, 1000h, coating is intact;

[0073] Acid dew resistance: 50℃, 20% +5% HCl mixed condensate, 30d, no blister, no rust spot.

[0074] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled in the art, without departing from the technical principles of the present application, several improvements and modifications can be made, and these changes and modifications should be considered as the protection scope of the present application.

Claims

1. An organosilicon-phosphate interpenetrating network coating, characterized in that, It includes the following components: Component A is an organosilicon prepolymer, comprising, by weight, 10–20 parts of hydroxyl-terminated polydimethylsiloxane; 1–2 parts of vinyltrimethoxysilane (VTMS); 1–2 parts of γ-aminopropyltriethoxysilane (KH-550); and nano- Sol 10–15 parts; ethylene glycol monobutyl ether 1–3 parts; polyether-modified siloxane leveling agent 0.2–0.5 parts; deionized water 1–10 parts; Component B is a modified rare earth-functional filler: comprising rare earth-functional filler and a 3% wt ethanol solution of silane coupling agent (KH-560); wherein, the rare earth-functional filler, by weight, comprises 10–15 parts of flake aluminum powder; rare earth oxides 2–5 parts; ultrafine ZnO 5–10 parts; zircon powder 10–15 parts; silicon carbide whiskers 3–5 parts; copper chromium black pigment 8–10 parts; mica powder 8–10 parts; glass powder 10–15 parts; KH-560 dosage is 1% of the total mass of rare earth and functional powders; Component C is an inorganic phosphate solution, including aluminum dihydrogen phosphate solution (50% wt). Component D is an aqueous curing accelerator: including triethanolamine aqueous solution (50% wt); The mass ratio of A:B:C is (30–40):(40–50):(10–20), and D is 1% of the total mass of A, B, and C.

2. The organosilicon-phosphate interpenetrating network coating as described in claim 1, characterized in that, The nano sol The rare earth oxide has a wavelength of 10-30 nm and a solid content of 30%. for At least one of them, <100nm; the ultrafine ZnO particle size is <100nm; The silicon carbide whiskers are cubic silicon carbide β-SiC with an aspect ratio of 10–20; the mica powder particles have a diameter-to-thickness ratio ≥60; and the flake aluminum powder has a particle size of 10–20 μm.

3. A method for preparing an organosilicon-phosphate interpenetrating network coating, characterized in that, Includes the following steps, Step 1: At 60℃, Under protection, hydroxyl-terminated polydimethylsiloxane, VTMS, KH-550, and nano-polymers are used. The sol was stirred and mixed, and kept at the temperature for 2 hours to form an organic-inorganic hybrid prepolymer. The temperature was then lowered to 40°C, and ethylene glycol monobutyl ether, polyether-modified siloxane leveling agent, and deionized water were added in sequence to obtain component A, i.e., the organosilicon prepolymer. Step 2: Grind the rare earth-functional filler using a powder grinding and mixing equipment until... After being ≤5μm thick, it was subjected to high-speed shearing with ethanol solution of silane coupling agent (KH-560) for 30 min and dried at 80℃ to obtain the surface-modified rare earth-functional filler of component B. Step 3: IPN coating preparation. Mix components A, B, and C in a mass ratio of A:B:C = (30–40):(40–50):(10–20) to obtain a mixture. Disperse the mixture at 800 r / min for 10 min. Add component D at 1% of the total mass of the mixture and continue stirring for 5 min to obtain the organosilicon-phosphate interpenetrating network thermal shock resistant high-temperature flue gas anticorrosion coating. Use after curing for 15 min. The applicable period is 4 hours.

4. The method for preparing an organosilicon-phosphate interpenetrating network coating as described in claim 3, characterized in that, Anhydrous ethanol and deionized water were mixed and stirred evenly at a mass ratio of 4:

1. Acetic acid was added dropwise to adjust the pH to 4.

0. After stirring thoroughly, KH560 was slowly added to the ethanol solvent to prepare a 3%wt silane coupling agent (KH-560) ethanol solution.

5. A method for spraying an organosilicon-phosphate interpenetrating network coating, characterized in that, Includes the following steps, Substrate preparation: The substrate is sandblasted using a dry sandblasting method; 24-46 mesh brown corundum or quartz sand and an outlet air pressure of 0.4-0.6 MPa are selected; immediately after sandblasting, compressed air is used to remove dust, debris and abrasive from the surface of the substrate. This air is degreased and dehumidified; after dust removal, the substrate is wiped with a non-woven cloth or gauze soaked in alcohol; the surface cleanliness of the substrate is reduced to Sa2.5 after wiping off dust and residual grease, and spraying is carried out within 2 hours. Spraying: Adjust the spray gun outlet pressure to 0.4-0.6MPa, load the above-mentioned paint and spray evenly; the vertical distance between the spray gun nozzle and the surface to be sprayed is about 250mm, and cross-spraying is defined as one pass. Place the substrate on the turntable and the turntable speed is 5-8r / min. Curing process: After spraying, it will cure in 5-7 days at room temperature above 20℃; or cure at room temperature for 24 hours, then dry at 120℃ for 1 hour to speed up the curing process.

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