A high-temperature-resistant, anti-abrasion and anti-corrosion coating for boilers and a preparation method thereof

Abstract

The present application belongs to the technical field of boiler protection, and more particularly relates to a high-temperature-resistant, anti-abrasion and corrosion-resistant coating for boilers and a preparation method thereof. The product comprises the following raw materials in parts by weight: 60-65 parts of carbon-coated alumina, 6-8 parts of sepiolite, 30-35 parts of methylphenyl-type silicone resin, 10-15 parts of solvent, 2-3 parts of BYK-163 dispersant, and 0.5-0.8 parts of silane coupling agent. The carbon-coated alumina comprises an alumina core and a carbon coating layer coated on the surface of the alumina core. The carbon coating layer comprises amorphous carbon and nano-oxidized graphene. The solvent is a compound of dimethylbenzene and butanone in a mass ratio of 3-3.5:1. The D50 of the alumina core is 10-15 microns. The D50 of the carbon-coated alumina is 1.05 times the D50 of the alumina core.

Description

TECHNICAL FIELD

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

[0002] The high-temperature-resistant anti-abrasion and corrosion-resistant coating for boilers is a special coating designed for the high-temperature, corrosion and abrasion working conditions inside boilers, which is mainly applied to protect the metal surfaces inside boilers, such as furnace chambers and the like, so as to prolong the service life of boilers and improve the operating efficiency of boilers.

[0003] At present, the commonly used high-temperature-resistant anti-abrasion and corrosion-resistant coatings for boilers include ceramic-based coatings, metal-ceramic composite coatings and organic-inorganic hybrid coatings. Under the above working conditions, it is hoped that the coating can withstand a working temperature of 600℃ or above for a long time, and does not fall off or crack under high-temperature conditions, and maintains stable physical and chemical properties; in addition, it is also hoped that it can effectively resist the high-speed scouring and abrasion of impurities such as coal powder and ash; and it is also necessary to rely on it to prevent high-temperature oxidation, sulfide corrosion and acid and alkali corrosion. SUMMARY

[0004] The technical problem to be solved by the present application is that the existing high-temperature-resistant coating for boilers needs to consider both the corrosion resistance and the abrasion resistance under high-temperature conditions during use. Based on the above problem, the present application provides a high-temperature-resistant anti-abrasion and corrosion-resistant coating for boilers and a preparation method thereof.

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

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

[0007] The above purposes of the present application are achieved by the following technical solutions:

[0008] A high-temperature-resistant anti-abrasion and corrosion-resistant coating for boilers comprises 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 type silicone resin, 10-15 parts of solvent, 2-3 parts of BYK-163 dispersant, and 0.5-0.8 parts of silane coupling agent.

[0010] The carbon-coated alumina includes an alumina core and a carbon coating layer coated on the surface of the alumina core.

[0011] The carbon coating layer includes amorphous carbon and nano-oxidized graphene.

[0012] The nano-oxidized graphene can be selected from graphene oxide with a D50 of 10-12 nm as raw material.

[0013] The technical scheme has the beneficial effects that:

[0014] The technical scheme has the beneficial effects that:

[0015] Further, the sepiolite is a strong acid treated sepiolite, and the specific treatment steps of the strong acid treated sepiolite include:

[0016] The sepiolite and the strong acid solution are mixed at a mass ratio of 1:8-10, and then reacted at a temperature of 85-95 DEG C for 2-4 h, filtered, washed and dried, and then calcined at a temperature of 500-550 DEG C for 60-80 min, cooled, discharged, and the strong acid treated sepiolite is obtained;

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

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

[0019] The technical scheme has the beneficial effects that:

[0020] The above technical solution adds sepiolite, whose porous structure can adsorb solvents in the coating and adjust the drying rate of the coating after spraying, thereby reducing the probability of uneven paint film surface during spraying and improving overall uniformity; in particular, sepiolite fibers can fill the gaps between ceramic particles, reducing coating porosity and improving overall density and wear resistance.

[0021] However, the inventors discovered that due to impurities in sepiolite, or the possibility of dehydration at temperatures above 300°C, slight cracks may appear in the coating under high-temperature conditions. This, in turn, reduces the product's corrosion resistance and wear resistance under high-temperature conditions. Based on this, by treating sepiolite with strong acid, the hydrogen ions in the strong acid can replace the impurity metal ions between its layers. 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 a mixture of xylene and methyl ethyl ketone in a mass ratio of 3-3.5:1.

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

[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.

[0025] By adjusting the concentration of the carbon source or the ratio of the alumina core to the carbon source solution during the preparation process, the particle size of the carbon-coated alumina compared to its uncoated state can be controlled, and it can ultimately be obtained by sieving.

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

[0027] Furthermore, the carbon coating layer is doped with nitrogen (N) element.

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

[0029] The above technical solution further dops the carbon coating with nitrogen (N) to change the electronic structure of the carbon layer, forming stable C-N bonds and slowing down the oxidation rate of the carbon layer under high temperature and oxygen conditions. Specifically, N doping can be achieved through various means, such as adding a precursor containing N, like dopamine, to the carbon source solution.

[0030] A method for preparing a high-temperature resistant, wear-resistant, and corrosion-resistant coating for boilers, comprising the following specific preparation steps:

[0031] Preparation of carbon-coated alumina:

[0032] After mixing the alumina and carbon source dispersion solution, spray drying to obtain precursor particles;

[0033] The precursor particles are carbonized at high temperature under inert gas protection to form a carbon coating layer on the surface of the alumina, and carbon-coated alumina is obtained;

[0034] The carbon source dispersion solution includes the following raw materials in parts by weight: 100-120 parts of water, 10-15 parts of microcrystalline cellulose, 1.5-1.8 parts of nano-oxidized graphene, and 2-3 parts of polyvinyl alcohol;

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

[0036] Further, the carbon source dispersion solution further includes 3-5% dopamine by mass of the microcrystalline cellulose. DETAILED DESCRIPTION

[0037] The present application will be further described in conjunction with specific examples, but the examples do not limit the present application in any form. Unless otherwise specified, the reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the technical field.

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

[0039] The methylphenyl type silicone resin is SICO-P112, purchased from Shandong Silicon New Material Co., Ltd.

[0040] Example 1

[0041] Preparation of carbon-coated alumina:

[0042] After mixing the alumina and carbon source dispersion solution, the mixture is transported to a spray dryer by a screw pump, and spray dried 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 disc rotation speed of 8000 r / min to obtain precursor particles;

[0043] The precursor particles are carbonized at high temperature under inert gas protection to form a carbon coating layer on the surface of the alumina, and carbon-coated alumina is obtained;

[0044] The carbon source dispersion solution includes the following raw materials in parts by weight: 100 parts of water, 10 parts of microcrystalline cellulose, 1.5 parts of nano-oxidized graphene, and 2 parts of polyvinyl alcohol; and 3% dopamine by mass of the microcrystalline cellulose;

[0045] The D50 of the nano-graphene oxide is 10 nm;

[0046] The mass ratio of the alumina and the carbon source dispersion solution is 1:8.5;

[0047] The D50 of the alumina is 10 μm; the sphericity of the alumina is 0.75; in the screening process after the coating is completed, the carbon-coated alumina with a D50 of 1.05 times the alumina is screened out;

[0048] Preparation of strong acid-treated sepiolite:

[0049] After the sepiolite and the strong acid solution are mixed at a mass ratio of 1:8, and under the conditions of a temperature of 85°C and a stirring speed of 200 r / min, the mixture is reacted for 2 h, then filtered, the filter cake is collected and washed with deionized water until neutral, dried, and then calcined at a temperature of 500°C for 60 min, cooled, discharged, and the strong acid-treated sepiolite is obtained;

[0050] The mass fraction of the strong acid solution is 6%;

[0051] The strong acid solution is selected from the group consisting of a hydrochloric acid solution;

[0052] Preparation of the coating:

[0053] According to weight parts, 60 parts of carbon-coated alumina, 6 parts of strong acid-treated sepiolite, 30 parts of methylphenyl type silicone resin, 10 parts of solvent, 2 parts of BYK-163 dispersant, and 0.5 parts of silane coupling agent are taken;

[0054] The solvent is a compound of xylene and butanone at a mass ratio of 3:1;

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

[0056] First, the methylphenyl type silicone resin and the solvent are mixed, and then stirred and mixed at a speed of 600 r / min for 20 min, and then the carbon-coated alumina, the strong acid-treated sepiolite, the BYK-163 dispersant, and the silane coupling agent are added, and the stirring and mixing is continued for 40 min, and the high-temperature resistant, anti-abrasion, and anti-corrosion coating for boilers is obtained.

[0057] Example 2

[0058] Preparation of carbon-coated alumina:

[0059] After the alumina and the carbon source dispersion solution are mixed, they are transported to a spray dryer by a screw pump, and then spray dried under the conditions of a feeding rate of 35 g / min, an air inlet temperature of 128°C, an air outlet temperature of 106°C, and a main disc speed of 8100 r / min, and the precursor particles are obtained;

[0060] The precursor particles are heated at a rate of 4℃ / min to 670℃ under inert gas protection, carbonized at high temperature for 2h, and then cooled to room temperature in the furnace to form a carbon coating layer on the surface of the alumina, and then sieved to obtain the carbon-coated alumina;

[0061] The carbon source dispersion liquid comprises the following raw materials in parts by weight: 110 parts of water, 12 parts of microcrystalline cellulose, 1.6 parts of nano-oxidized graphene, and 2.3 parts of polyvinyl alcohol; and 4% of dopamine by mass of the microcrystalline cellulose;

[0062] The D50 of the nano-oxidized graphene is 11 nm;

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

[0064] The D50 of the alumina is 12 μm; the sphericity of the alumina is 0.8; and during the sieving after the coating is completed, the carbon-coated alumina with a D50 of 1.06 times the D50 of the alumina is sieved out;

[0065] Preparation of the strong acid-treated sepiolite:

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

[0067] The mass fraction of the strong acid solution is 7%;

[0068] The strong acid solution is selected from the group consisting of sulfuric acid solution;

[0069] Preparation of the coating:

[0070] According to parts by weight, 62 parts of carbon-coated alumina, 7 parts of strong acid-treated sepiolite, 32 parts of methylphenyl type silicone resin, 12 parts of solvent, 2.5 parts of BYK-163 dispersant, and 0.7 parts of silane coupling agent are taken;

[0071] The solvent is a compound of xylene and butanone at a mass ratio of 3.2:1;

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

[0073] The methylphenyl type silicone resin and the solvent are first mixed, and then stirred and mixed at a speed of 600r / min for 20min, and then the carbon-coated alumina, the strong acid-treated sepiolite, the BYK-163 dispersant, and the silane coupling agent are added, and the stirring and mixing is continued for 50min to obtain the high-temperature resistant, anti-abrasion and anti-corrosion coating for boilers.

[0074] Example 3

[0075] Preparation of carbon-coated alumina:

[0076] After mixing the alumina and the carbon source dispersion, the mixture was transported to a spray dryer by a screw pump, and then spray dried at a feed rate of 40 g / min, an inlet air temperature of 130℃, an outlet air temperature of 110℃, and a main disc rotation speed of 8200 r / min to obtain precursor particles;

[0077] The precursor particles were heated to 700℃ at a rate of 5℃ / min under inert gas protection, and then carbonized at high temperature for 3 h, and then cooled to room temperature in the furnace to form a carbon coating layer on the surface of the alumina, and then sieved to obtain carbon-coated alumina;

[0078] 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-oxidized graphene, and 3 parts of polyvinyl alcohol; and 5% of dopamine by mass of the microcrystalline cellulose;

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

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

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

[0082] Preparation of strong acid-treated sepiolite:

[0083] After mixing the sepiolite and the strong acid solution at a mass ratio of 1:10, the mixture was reacted at a temperature of 95℃ and a stirring rotation speed of 300 r / min for 4 h, then filtered, the filter cake was collected and washed with deionized water until neutral, dried, and then calcined at a temperature of 550℃ for 80 min, cooled, and discharged to obtain strong acid-treated sepiolite;

[0084] The mass fraction of the strong acid solution is 8%;

[0085] The strong acid solution is selected from the group consisting of nitric acid solution;

[0086] Preparation of the coating material:

[0087] 65 parts of carbon-coated alumina, 8 parts of strong acid-treated sepiolite, 35 parts of methylphenyl type silicone resin, 15 parts of solvent, 3 parts of BYK-163 dispersant, and 0.8 parts of silane coupling agent were taken by parts by weight;

[0088] The solvent is compounded by xylene and butanone according to the mass ratio of 3.5:1;

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

[0090] The methyl phenyl type silicone resin and the solvent are mixed first, and then stirred and mixed at a rotation speed of 600 r / min for 20 min, and then the carbon-coated alumina, the strong acid treated sepiolite, the BYK-163 dispersant and the silane coupling agent are added and stirred and mixed for 60 min, to obtain the high-temperature resistant, anti-abrasion and anti-corrosion coating for boilers.

[0091] Example 4

[0092] Compared with Example 1, the difference lies in that the preparation method of the strong acid treated sepiolite is different, specifically:

[0093] The sepiolite and the strong acid solution are mixed according to the mass ratio of 1:8, and then reacted at a temperature of 85℃ and a stirring rotation speed of 200 r / min for 2h, and then filtered, and the filter cake is washed with deionized water until neutral, and dried to obtain the strong acid treated sepiolite;

[0094] The rest of the conditions remain unchanged.

[0095] Example 5

[0096] Compared with Example 1, the difference lies in that the sepiolite is not treated with strong acid but used directly, specifically, the strong acid is not used for reaction treatment, and the calcination treatment is also not performed; the rest of the conditions remain unchanged.

[0097] Example 6

[0098] Compared with Example 1, the difference lies in that dopamine is not added, and the rest of the conditions remain unchanged.

[0099] Comparative Example 1

[0100] Compared with Example 1, the difference lies in that the nano graphene oxide is not added, and the rest of the conditions remain unchanged.

[0101] Comparative Example 2

[0102] Compared with Example 1, the difference lies in that the alumina is not treated with carbon but used directly, that is, the surface of the alumina is not coated with amorphous carbon and nano graphene oxide;

[0103] The rest of the conditions remain unchanged.

[0104] The products obtained in the above examples and comparative examples are tested for performance, and the specific test methods and test results are as follows:

[0105] Q235B steel plate is selected as the base material, sand blasting treatment is performed to Sa2.5 level; the base material area is 50cm 2 ;

[0106] Subsequently, the product obtained in the example or the comparative example is respectively sprayed to the surface of the base material, after curing at 200℃ for 20min, the temperature is continuously increased to 500℃, and curing is performed for 2h, and the dry film thickness is controlled to be 300μm;

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

[0108] The same spraying method is used to obtain the base material sprayed with the coating, and then a sodium sulfate salt film with a thickness of 20μm is deposited on the surface of the coating, and then the base material with the deposited salt film is tested by the same test method 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 of the superimposed salt film under high temperature conditions, to obtain mass loss 2, and the specific test results are shown in Table 2;

[0109] Table 1: Product performance test results

[0110] mass loss 1 (mg / cm 2 • h)]]> 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] From the test results in Table 1, it can be seen that the product obtained by the present application has excellent corrosion resistance under high temperature conditions.

[0112] The above examples are preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A high temperature resistant anti-erosion coating for boilers, characterized by, The raw materials include the following components by weight: 60-65 parts of carbon-coated alumina, 6-8 parts of strongly acid-treated sepiolite, 30-35 parts of methylphenyl type silicone resin, 10-15 parts of solvent, 2-3 parts of BYK-163 dispersant, and 0.5-0.8 parts of silane coupling agent; The carbon-coated alumina includes an alumina core and a carbon coating layer coated on the surface of the alumina core. The carbon coating layer includes amorphous carbon and nano-oxidized graphene. The specific treatment steps of the strongly acid-treated sepiolite include: After mixing sepiolite and a strongly acid solution at a mass ratio of 1:8-10, reacting at a temperature of 85-95℃ for 2-4h, filtering, washing and drying, and then calcining at a temperature of 500-550℃ for 60-80min, cooling, discharging, the strongly acid-treated sepiolite is obtained. The mass fraction of the strongly acid solution is 6-8%. The strongly acid solution is selected from any one of hydrochloric acid solution, sulfuric acid solution or nitric acid solution.

2. A high temperature resistant anti-erosion coating for boilers according to claim 1, characterized in that, The solvent is a compound of xylene and butanone at a mass ratio of 3-3.5:

1.

3. A high temperature resistant anti-erosion 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.

4. A high temperature resistant anti-erosion coating for boilers as claimed in claim 1, wherein The D50 of the alumina core is 10-15μm, and the D50 of the carbon-coated alumina is 1.05-1.08 times the D50 of the alumina core.

5. The high temperature resistant anti-erosion coating for boilers according to claim 1, characterized in that, The sphericity of the alumina core is 0.75-0.

85.

6. A high temperature resistant anti-erosion coating for boilers according to claim 1, characterized in that, The carbon coating layer is doped with N element.

7. A process for the preparation of a high-temperature corrosion and abrasion resistant coating for boilers as claimed in any one of claims 1 to 6, characterized in that, The specific preparation steps include: Preparation of carbon-coated alumina: Mixing alumina and carbon source dispersion, spray drying to obtain precursor particles; High-temperature carbonization of the precursor particles under inert gas protection to form a carbon coating layer on the surface of the alumina, thereby obtaining carbon-coated alumina; The carbon source dispersion includes the following components by weight: 100-120 parts of water, 10-15 parts of microcrystalline cellulose, 1.5-1.8 parts of nano-oxidized graphene, and 2-3 parts of polyvinyl alcohol. The mass ratio of the alumina to the carbon source dispersion is 1:8.5-9.

5.

8. The method for preparing a high-temperature resistant, wear-resistant, and corrosion-resistant coating for boilers according to claim 7, characterized in that, The carbon source dispersion also includes 3-5% dopamine of the mass of microcrystalline cellulose.