High-temperature-resistant, wear-resistant and corrosion-resistant coating for boiler and preparation method thereof

Abstract

The invention belongs to the technical field of boiler protection, and particularly relates to a high-temperature-resistant, wear-resistant and corrosion-resistant coating for a boiler and a preparation method of the coating. The product provided by the invention is prepared from the following raw materials in parts by weight: 60 to 65 parts of carbon-coated aluminum oxide, 6 to 8 parts of sepiolite, 30 to 35 parts of methyl phenyl type organic silicon resin, 10 to 15 parts of a solvent, 2 to 3 parts of a BYK-163 dispersing agent and 0.5 to 0.8 part of a silane coupling agent. Wherein the carbon-coated aluminum oxide comprises an aluminum oxide core and a carbon coating layer coating the surface of the aluminum oxide core; the carbon coating layer comprises amorphous carbon and nano graphene oxide; the solvent is formed by compounding xylene and butanone according to the mass ratio of (3-3.5): 1; the D50 of the aluminum oxide core is 10 to 15 [mu] m; the D50 of the carbon-coated aluminum oxide is 1.05 times of the D50 of the aluminum oxide core.

Description

Technical Field

[0001] The present invention belongs to the technical field of boiler protection. More specifically, it relates to a high-temperature resistant, abrasion-resistant and corrosion-resistant coating for boilers and a preparation method thereof. Background Art

[0002] The high-temperature resistant, abrasion-resistant and corrosion-resistant coating for boilers is a special coating designed for the high-temperature, corrosion and wear working conditions inside boilers. It is mainly applied to protect the metal surfaces inside boilers, such as the furnace and other parts, so as to achieve the purpose of extending the service life of boilers and improving the operation efficiency of boilers.

[0003] At present, the commonly used high-temperature resistant, abrasion-resistant and corrosion-resistant coatings for boilers include ceramic-based coatings, cermet composite coatings, and organic-inorganic hybrid coatings. Under the above working conditions, it is hoped that the coating can withstand the working temperature reaching above 600 °C for a long time, and, under high-temperature conditions, it does not fall off, crack, and maintains stable physical and chemical properties; in addition, it is also hoped that it can effectively resist the high-speed erosion and wear of impurities such as pulverized coal and ash slag; naturally, it also needs to rely on it to prevent high-temperature oxidation, sulfide corrosion and acid-base erosion. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: aiming at the problem that the existing high-temperature resistant coatings for boilers need to balance the corrosion resistance and wear resistance under high-temperature conditions during use. Based on the above problems, the present invention provides a high-temperature resistant, abrasion-resistant and corrosion-resistant coating for boilers and a preparation method thereof.

[0005] The purpose of the present invention is to provide a high-temperature resistant, abrasion-resistant and corrosion-resistant coating for boilers.

[0006] Another purpose of the present invention is to provide a preparation method of a high-temperature resistant, abrasion-resistant and corrosion-resistant coating for boilers.

[0007] The above objects of the present invention are achieved by the following technical solutions:

[0008] A high-temperature resistant, abrasion-resistant and corrosion-resistant coating for boilers, comprising the following raw materials in parts by weight:

[0009] 60 - 65 parts of carbon-coated alumina, 6 - 8 parts of sepiolite, 30 - 35 parts of methylphenyl silicone resin, 10 - 15 parts of solvent, 2 - 3 parts of BYK-163 dispersant, 0.5 - 0.8 parts of silane coupling agent;

[0010] Wherein, the carbon-coated alumina includes an alumina core and a carbon coating layer coated on the surface of the alumina core;

[0011] In the carbon coating layer, there are amorphous carbon and nano-graphene oxide.

[0012] Among them, graphene oxide nanoparticles can select graphene oxide with a D50 of 10-12 nm as the raw material.

[0013] The beneficial effects of the above technical solution are as follows:

[0014] In the above technical solution, by carbon coating the alumina, the polarity of the alumina surface is reduced by the carbon layer, thereby reducing the van der Waals force between particles, reducing the occurrence of agglomeration between alumina particles, which is beneficial to the uniformity of the coating during the spraying process, avoiding the occurrence of coating unevenness caused by local agglomeration, and thus preventing performance failure caused by local peeling; in addition, it can also act as a solid lubricant, reducing the viscosity of the coating during high-speed shearing, which is beneficial to the uniformity of atomization during the spraying process; however, the inventor found that if amorphous carbon is used alone to coat the alumina, in the high-temperature aerobic environment of the boiler, the amorphous carbon is prone to oxidation failure, resulting in the destruction of the coating structure of the surface alumina. After the destruction, the porosity of the coating surface increases significantly, and the corrosive medium is easy to diffuse inward. Moreover, the wear resistance of the product also begins to decline. By adding graphene oxide nanoparticles, this problem can be improved. On the one hand, it is because graphene oxide has higher thermal stability compared with amorphous carbon. In addition, even after the amorphous carbon is oxidized at high temperature, the presence of graphene oxide can still provide a truncating effect on the corrosion path of the corrosive medium. And more importantly, graphene oxide can still provide excellent wear resistance, effectively extending the service life of the product.

[0015] Further, the sepiolite is sepiolite treated with strong acid. The specific treatment steps of the sepiolite treated with strong acid include:

[0016] Mix sepiolite and strong acid solution according to a mass ratio of 1:8-10, react at a temperature of 85-95 °C for 2-4 h, then filter, wash and dry. Subsequently, calcine at a temperature of 500-550 °C for 60-80 min, cool, and discharge to obtain sepiolite treated with strong acid;

[0017] Among them, the mass fraction of the strong acid solution is 6-8%;

[0018] The strong acid solution is selected from any one of hydrochloric acid solution, sulfuric acid solution or nitric acid solution.

[0019] The beneficial effects of the above technical solution are as follows:

[0020] Through the above technical solution, by adding sepiolite, its porous structure can adsorb the solvent in the coating, adjust the drying rate of the coating after spraying, thereby reducing the occurrence probability of an uneven paint film surface during spraying and improving the overall uniformity; in particular, sepiolite fibers can fill the gaps between ceramic particles, reducing the coating porosity and improving the overall density and wear resistance;

[0021] However, the inventor found that due to the presence of impurities in sepiolite or the possible dehydration problem at temperatures above 300°C, it may cause slight cracks in the coating under high-temperature conditions, which will instead lead to a decrease in the corrosion resistance and wear resistance of the product under high-temperature conditions. Based on this, by performing strong acid treatment on sepiolite, hydrogen ions in the strong acid can displace the impurity metal ions between its layers, and then combined with high-temperature calcination, the possibility of dehydration under the high-temperature environment of the boiler is avoided, and its crystal structure is stabilized in advance.

[0022] Furthermore, the solvent is compounded from xylene and methyl ethyl ketone according to a mass ratio of 3 - 3.5:1.

[0023] Furthermore, the silane coupling agent is selected from any one of silane coupling agent KH-540, silane coupling agent KH-550, silane coupling agent KH-560, silane coupling agent KH-570, and silane coupling agent KH-580.

[0024] Furthermore, the D50 of the alumina core is 10 - 15 μm; the D50 of the carbon-coated alumina is 1.05 - 1.08 times that of the alumina core D50.

[0025] During the preparation process, by controlling process conditions such as the concentration of the carbon source or the dosage ratio of the alumina core and the carbon source solution, the particle size of the carbon-coated alumina compared to that before coating can be controlled, and finally obtained through screening.

[0026] Furthermore, the sphericity of the alumina core is 0.75 - 0.85.

[0027] Furthermore, N element is doped in the carbon coating layer.

[0028] The beneficial effects of the above technical solution are:

[0029] By further doping N element in the carbon coating layer in the above technical solution, N atoms are used to change the electronic structure of the carbon layer, form stable C-N bonds, and delay the oxidation rate of the carbon layer under high-temperature aerobic environmental conditions; specifically, the doping of N element can be achieved through various ways. For example, in the carbon source solution, a precursor with N element, such as dopamine, is added.

[0030] A preparation method of a high-temperature resistant, abrasion-resistant and corrosion-resistant coating for boilers, the specific preparation steps include:

[0031] Preparation of carbon-coated alumina:

[0032] After mixing alumina and a carbon source dispersion, spray drying is carried out to obtain precursor particles;

[0033] The precursor particles are subjected to high-temperature carbonization under the protection of an inert gas to form a carbon coating layer on the surface of alumina, thereby obtaining carbon-coated alumina;

[0034] Among them, the carbon source dispersion comprises raw materials in the following weight parts: 100 - 120 parts of water, 10 - 15 parts of microcrystalline cellulose, 1.5 - 1.8 parts of nano-graphene oxide, and 2 - 3 parts of polyvinyl alcohol;

[0035] The mass ratio of the alumina to the carbon source dispersion is 1:8.5 - 9.5.

[0036] Furthermore, in the carbon source dispersion, dopamine accounting for 3 - 5% of the mass of microcrystalline cellulose is further included. Specific embodiments

[0037] The following specific examples are used to further illustrate the present invention, but the examples do not impose any form of limitation on the present invention. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field.

[0038] Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0039] Among them, the brand of the methylphenyl silicone resin is SICO - P112, which is purchased from Shandong Silicone New Materials Co., Ltd.

[0040] Example 1

[0041] Preparation of carbon-coated alumina:

[0042] After mixing alumina and a carbon source dispersion, it is transported to a spray dryer through a screw pump, and spray drying is carried out under the conditions of a feed rate of 30 g / min, an inlet air temperature of 125 °C, an outlet air temperature of 105 °C, and a main disk rotation speed of 8000 r / min to obtain precursor particles;

[0043] The precursor particles are heated and raised to 650 °C at a rate of 3 °C / min under the protection of an inert gas, subjected to high-temperature carbonization for 1 h, and then cooled to room temperature with the furnace to form a carbon coating layer on the surface of alumina, and then sieved to obtain carbon-coated alumina;

[0044] Among them, the carbon source dispersion comprises raw materials in the following weight parts: 100 parts of water, 10 parts of microcrystalline cellulose, 1.5 parts of nano-graphene oxide, 2 parts of polyvinyl alcohol; and dopamine accounting for 3% of the mass of microcrystalline cellulose;

[0045] The D50 of graphene oxide nanoparticles is 10 nm;

[0046] The mass ratio of the aluminum oxide to the carbon source dispersion is 1:8.5;

[0047] Among them, the D50 of the aluminum oxide is 10 μm; the sphericity of the aluminum oxide is 0.75; during the screening process after coating, aluminum oxide-carbon coated aluminum oxide with a D50 1.05 times that of the aluminum oxide is screened out;

[0048] Preparation of strongly acidic treated sepiolite:

[0049] After mixing sepiolite and a strong acid solution at a mass ratio of 1:8, reacting at a temperature of 85 °C and a stirring speed of 200 r / min for 2 h, filtering, collecting the filter cake, washing the filter cake with deionized water until neutral, drying, and then calcining at a temperature of 500 °C for 60 min, cooling, and discharging to obtain strongly acidic treated sepiolite;

[0050] Among them, the mass fraction of the strong acid solution is 6%;

[0051] The strong acid solution is selected from: hydrochloric acid solution;

[0052] Preparation of the coating:

[0053] By weight, take 60 parts of aluminum oxide-carbon coated aluminum oxide, 6 parts of strongly acidic treated sepiolite, 30 parts of methylphenyl silicone resin, 10 parts of solvent, 2 parts of BYK-163 dispersant, and 0.5 part of silane coupling agent;

[0054] The solvent is prepared by compounding xylene and methyl ethyl ketone at a mass ratio of 3:1;

[0055] The silane coupling agent is selected from silane coupling agent KH-540;

[0056] First, mix the methylphenyl silicone resin and the solvent, and stir and mix for 20 min at a rotation speed of 600 r / min. Then, add the aluminum oxide-carbon coated aluminum oxide, strongly acidic treated sepiolite, BYK-163 dispersant, and silane coupling agent, and continue to stir and mix for 40 min to obtain the high-temperature resistant anti-wear and corrosion-resistant coating for boilers.

[0057] Example 2

[0058] Preparation of aluminum oxide-carbon coated aluminum oxide:

[0059] After mixing the aluminum oxide and the carbon source dispersion, it is pumped to a spray dryer by a screw pump, and spray dried under the conditions of a feeding rate of 35 g / min, an inlet air temperature of 128 °C, an outlet air temperature of 106 °C, and a main disk rotation speed of 8100 r / min to obtain precursor particles;

[0060] The precursor particles are heated at a rate of 4 °C / min to 670 °C under an inert gas protection, carbonized at high temperature for 2 h, and then cooled to room temperature in the furnace to form a carbon coating layer on the surface of alumina. After screening, carbon-coated alumina is obtained.

[0061] Among them, the carbon source dispersion liquid includes the following raw materials in parts by weight: 110 parts of water, 12 parts of microcrystalline cellulose, 1.6 parts of nano-graphene oxide, 2.3 parts of polyvinyl alcohol; and 4% of dopamine based on the mass of microcrystalline cellulose.

[0062] The D50 of nano-graphene oxide is 11 nm.

[0063] The mass ratio of the alumina to the carbon source dispersion liquid is 1:9.

[0064] Among them, the D50 of alumina is 12 μm; the sphericity of the alumina is 0.8; during the screening process after coating, carbon-coated alumina with a D50 1.06 times that of alumina is screened out.

[0065] Preparation of strongly acidic treated sepiolite:

[0066] Sepiolite and a strong acid solution are mixed at a mass ratio of 1:9, reacted at a temperature of 88 °C and a stirring speed of 260 r / min for 3 h, then filtered, the filter cake is collected, washed with deionized water until neutral, dried, and then calcined at a temperature of 520 °C for 70 min, cooled, and discharged to obtain strongly acidic treated sepiolite.

[0067] Among them, the mass fraction of the strong acid solution is 7%.

[0068] The strong acid solution is selected from: sulfuric acid solution.

[0069] Preparation of the coating:

[0070] By weight, 62 parts of carbon-coated alumina, 7 parts of strongly acidic treated sepiolite, 32 parts of methylphenyl silicone resin, 12 parts of solvent, 2.5 parts of BYK-163 dispersant, and 0.7 part of silane coupling agent are taken.

[0071] The solvent is compounded from xylene and methyl ethyl ketone at a mass ratio of 3.2:1.

[0072] The silane coupling agent is selected from silane coupling agent KH-550.

[0073] First, the methylphenyl silicone resin and the solvent are mixed, stirred and mixed at a speed of 600 r / min for 20 min, and then carbon-coated alumina, strongly acidic treated sepiolite, BYK-163 dispersant and silane coupling agent are added, and stirring and mixing are continued for 50 min to obtain the boiler high-temperature wear-resistant and corrosion-resistant coating.

[0074] Example 3

[0075] Preparation of carbon-coated alumina:

[0076] After mixing alumina and the carbon source dispersion, it is delivered to a spray dryer by a screw pump. Under the conditions of a feeding rate of 40 g / min, an inlet air temperature of 130 °C, an outlet air temperature of 110 °C, and a main disk rotation speed of 8200 r / min, spray drying is carried out to obtain precursor particles;

[0077] Under the protection of inert gas, the precursor particles are heated and raised to 700 °C at a rate of 5 °C / min, carbonized at high temperature for 3 h, and then cooled to room temperature with the furnace to form a carbon coating layer on the surface of alumina, and then sieved to obtain carbon-coated alumina;

[0078] Among them, the carbon source dispersion includes the following raw materials in parts by weight: 120 parts of water, 15 parts of microcrystalline cellulose, 1.8 parts of nano-graphene oxide, 3 parts of polyvinyl alcohol; and 5% of dopamine based on the mass of microcrystalline cellulose;

[0079] The D50 of nano-graphene oxide is 12 nm;

[0080] The mass ratio of the alumina to the carbon source dispersion is 1:9.5;

[0081] Among them, the D50 of alumina is 15 μm; the sphericity of the alumina is 0.85; during the sieving process after coating, carbon-coated alumina with a D50 1.08 times that of alumina is sieved out;

[0082] Preparation of strongly acid-treated sepiolite:

[0083] After mixing sepiolite and a strong acid solution in a mass ratio of 1:10, reacting at a temperature of 95 °C and a stirring speed of 300 r / min for 4 h, filtering, collecting the filter cake, washing the filter cake with deionized water until neutral, drying, and then calcining at a temperature of 550 °C for 80 min, cooling, and discharging to obtain strongly acid-treated sepiolite;

[0084] Among them, the mass fraction of the strong acid solution is 8%;

[0085] The strong acid solution is selected from: nitric acid solution;

[0086] Preparation of the coating:

[0087] By weight, take 65 parts of carbon-coated alumina, 8 parts of strongly acid-treated sepiolite, 35 parts of methylphenyl silicone resin, 15 parts of solvent, 3 parts of BYK-163 dispersant, and 0.8 part of silane coupling agent;

[0088] The solvent is prepared by compounding xylene and methyl ethyl ketone according to a mass ratio of 3.5:1;

[0089] The silane coupling agent is selected from silane coupling agent KH-560;

[0090] First, mix the methylphenyl silicone resin and the solvent, and then stir and mix for 20 min at a rotation speed of 600 r / min. Subsequently, add carbon-coated alumina, strongly acid-treated sepiolite, BYK-163 dispersant and silane coupling agent, and continue to stir and mix for 60 min to obtain the high-temperature resistant anti-wear and anti-corrosion coating for boilers.

[0091] Example 4

[0092] Compared with Example 1, the difference in this example is that the preparation method of the strongly acid-treated sepiolite is different. Specifically:

[0093] Mix sepiolite and strong acid solution according to a mass ratio of 1:8, react at a temperature of 85 °C and a stirring speed of 200 r / min for 2 h, then filter, collect the filter cake, wash the filter cake with deionized water until neutral, and dry to obtain strongly acid-treated sepiolite;

[0094] Keep the remaining conditions unchanged.

[0095] Example 5

[0096] Compared with Example 1, the difference in this example is that the sepiolite is directly used without being strongly acid-treated. Specifically, that is, it is neither reacted with strong acid nor calcined; keep the remaining conditions unchanged.

[0097] Example 6

[0098] Compared with Example 1, the difference in this example is that dopamine is not added, and the remaining conditions remain unchanged.

[0099] Comparative Example 1

[0100] Compared with Example 1, the difference in this comparative example is that nano-graphene oxide is not added, and the remaining conditions remain unchanged.

[0101] Comparative Example 2

[0102] Compared with Example 1, the difference in this comparative example is that alumina is directly used without being carbon-coated, that is, the surface of alumina is not coated with amorphous carbon and nano-graphene oxide;

[0103] Keep the remaining conditions unchanged.

[0104] Perform performance tests on the products obtained in the above examples and comparative examples. The specific test methods and test results are as follows:

[0105] Select Q235B steel plate as the base material and sandblast it to Sa2.5 level; the area of the base material is 50 cm 2 ;

[0106] Subsequently, spray the products obtained in the examples or comparative examples onto the surface of the base material respectively. After heat preservation and curing at 200 °C for 20 min, continue to heat up to 500 °C and keep heat preservation and curing for 2 h, and adjust the dry film thickness to 300 μm;

[0107] Conduct high-temperature wear resistance test on the base material after spraying. Specifically, at a temperature of 600 °C, use coal ash for erosion, the erosion rate is 15 m / s, the erosion angle is 45°, the D50 of the coal ash is 50 μm, and evaluate its high-temperature wear resistance by the mass loss per unit time and per unit area to obtain the mass loss 1. The specific test results are shown in Table 1;

[0108] Adopt the same spraying method as above to obtain a base material sprayed with coating, then deposit a sodium sulfate salt film with a thickness of 20 μm on the surface of the coating. Subsequently, use the same test method as above to test the high-temperature wear resistance of the base material with the salt film, so as to evaluate the high-temperature wear resistance of the product under the corrosion effect of the superimposed salt film at high temperature to obtain the mass loss 2. The specific test results are shown in Table 2;

[0109] Table 1: Test results of product performance

[0110] <![CDATA[Mass loss 1 (mg / cm 2 ·h)]]> <![CDATA[Mass loss 2 (mg / cm 2 ·h)]]> Example 1 0.03 0.05 Example 2 0.02 0.04 Example 3 0.02 0.04 Example 4 0.05 0.08 Example 5 0.08 0.11 Example 6 0.06 0.10 Comparative Example 1 0.18 0.23 Comparative Example 2 0.25 0.30

[0111] It can be seen from the test results in Table 1 that the products obtained by the present invention have excellent corrosion resistance under high-temperature conditions.

[0112] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A high-temperature resistant, abrasion-proof and corrosion-resistant coating for boilers, characterized in that, Comprising raw materials in the following parts by weight: 60 - 65 parts of carbon-coated alumina, 6 - 8 parts of sepiolite, 30 - 35 parts of methylphenyl silicone resin, 10 - 15 parts of solvent, 2 - 3 parts of BYK-163 dispersant, 0.5 - 0.8 part of silane coupling agent; Among them, the carbon-coated alumina includes an alumina core and a carbon coating layer coated on the surface of the alumina core; In the carbon coating layer, amorphous carbon and nano-graphene oxide are included.

2. The high-temperature resistant, abrasion-proof and corrosion-resistant coating for boilers according to claim 1, characterized in that, The sepiolite is sepiolite treated with strong acid, and the specific treatment steps of the sepiolite treated with strong acid include: Mix sepiolite and strong acid solution according to a mass ratio of 1:8 - 10, react at a temperature of 85 - 95 °C for 2 - 4 h, then filter, wash and dry, and then calcine at a temperature of 500 - 550 °C for 60 - 80 min, cool, and discharge to obtain sepiolite treated with strong acid; Among them, the mass fraction of the strong acid solution is 6 - 8%; The strong acid solution is selected from any one of hydrochloric acid solution, sulfuric acid solution or nitric acid solution.

3. A high-temperature resistant, abrasion-resistant and corrosion-resistant coating for boilers according to claim 1, characterized in that, The solvent is compounded from xylene and methyl ethyl ketone according to a mass ratio of 3 - 3.5:

1.

4. A high-temperature resistant, abrasion-proof and corrosion-resistant coating for boilers according to claim 1, characterized in that, The silane coupling agent is selected from any one of silane coupling agent KH-540, silane coupling agent KH-550, silane coupling agent KH-560, silane coupling agent KH-570, and silane coupling agent KH-580.

5. A high-temperature resistant, abrasion and corrosion resistant coating for boilers according to claim 1, characterized in that, The D50 of the alumina core is 10 - 15 μm; the D50 of the carbon-coated alumina is 1.05 - 1.08 times that of the alumina core D50.

6. A high-temperature resistant, abrasion and corrosion resistant coating for boilers according to claim 1, characterized in that, The sphericity of the alumina core is 0.75 - 0.

85.

7. A high-temperature resistant, abrasion and corrosion resistant coating for boilers according to claim 1, characterized in that, In the carbon coating layer, N element is doped.

8. A preparation method of a high-temperature resistant, abrasion-proof and corrosion-resistant coating for boilers according to any one of claims 1-7, characterized in that, The specific preparation steps include: Preparation of carbon-coated alumina: Mix alumina and carbon source dispersion liquid, and spray dry to obtain precursor particles; Carry out high-temperature carbonization of the precursor particles under the protection of inert gas to form a carbon coating layer on the surface of the alumina to obtain carbon-coated alumina; Among them, the carbon source dispersion liquid includes raw materials in the following parts by weight: 100 - 120 parts of water, 10 - 15 parts of microcrystalline cellulose, 1.5 - 1.8 parts of nano-graphene oxide, 2 - 3 parts of polyvinyl alcohol; The mass ratio of the alumina to the carbon source dispersion liquid is 1:8.5 - 9.

5.

9. The preparation method of a high-temperature resistant, abrasion-proof and corrosion-resistant coating for boilers according to claim 8, characterized in that, In the carbon source dispersion liquid, dopamine accounting for 3 - 5% of the mass of microcrystalline cellulose is also included.