A coating material, composite material resistant to oxidation and chlorine corrosion under high temperature environment and their preparation methods

Abstract

The present invention discloses a coating material, a composite material and a preparation method thereof which are resistant to oxidation and chlorine corrosion under high temperature environments. In terms of mass percentage, the components of the coating material include: 60% - 70% iron-based alloy powder, 25% - 35% aluminum powder, and 5% - 10% titanium powder. The iron-based alloy powder includes: Cr 19% - 21%, Ni 17.5% - 18.5%, Mo 6.0% - 6.5%, Cu 0.5% - 1.0%, N 0.15% - 0.22%, Si ≤ 0.8%, C ≤ 0.02%, Mn ≤ 1.0%, S ≤ 0.01%, P ≤ 0.02%, and the balance is Fe. The aluminum powder is pure aluminum or a mixed powder of pure aluminum and alumina (weight ratio not exceeding 30%), and the titanium powder is any one or two of commercial TA0, TA1, TA2 powders and a mixture of two or more. The coating prepared by the present invention significantly reduces the coating preparation cost, effectively ensures the chlorine corrosion resistance, oxidation resistance, high temperature resistance of the alloy system and the strength of the coating or the cladding layer, and significantly improves the stability, plasticity and toughness of the coating structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of corrosion protection, and particularly relates to a coating material, a composite material and a preparation method thereof which are resistant to oxidation and chlorine corrosion in a high-temperature environment. Background Art

[0002] At present, co-firing municipal solid waste, biomass materials or inferior coal in thermal power units can improve economy and is beneficial to environmental protection. However, as the core component of the boiler, the boiler heating surface furnace tubes have serious problems of high-temperature oxidation and chlorine corrosion in a high-temperature and complex flue gas environment, posing a great threat to the safe operation of the boiler.

[0003] At present, spraying a protective coating is the most common protective measure. However, there are problems such as high coating cost, easy oxidation at high temperature, poor high-temperature stability and low strength. Therefore, it is necessary to develop a coating with better oxidation resistance and chlorine corrosion resistance in a high-temperature environment to provide an effective solution for improving the problem of chlorine corrosion of the heating surface of coal-fired boilers. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a coating material, a composite material and a preparation method thereof which are resistant to oxidation and chlorine corrosion in a high-temperature environment. The coating in the present invention has the properties of oxidation resistance and chlorine corrosion resistance, and can improve the problem of chlorine corrosion of the heating surface of coal-fired boilers.

[0005] The present invention is realized through the following technical solutions:

[0006] A coating material resistant to oxidation and chlorine corrosion in a high-temperature environment, in terms of mass percentage, its components include: 60%-70% iron-based alloy powder, 25%-35% aluminum powder and 5%-10% titanium powder;

[0007] In terms of mass percentage, the composition of the iron-based alloy powder includes: Cr 19%-21%, Ni 17.5%-18.5%, Mo 6.0%-6.5%, Cu 0.5%-1.0%, N 0.15%-0.22%, Si≤0.8%, C≤0.02%, Mn≤1.0%, S≤0.01%, P≤0.02%, and the balance is Fe;

[0008] The aluminum powder adopts a mixed powder of pure aluminum and alumina or pure aluminum powder. In the mixed powder of pure aluminum and alumina, the weight ratio of alumina does not exceed 30%.

[0009] Preferably, the titanium powder adopts a mixture of one or more of TA0 powder, TA1 powder and TA2 powder.

[0010] The present invention also provides a preparation method of a composite material, including the following process:

[0011] The coating material with oxidation resistance and chlorine corrosion resistance under high temperature as described above for the present invention is ball-milled to obtain a uniformly mixed ball-milled mixture;

[0012] A coating is prepared on the surface of the substrate by using the ball-milled mixture by means of thermal spraying or cladding to obtain the composite material.

[0013] Preferably, the iron-based alloy powder is prepared by means of molten atomization in an inert gas or vacuum environment.

[0014] Preferably, when the iron-based alloy powder is prepared by means of molten atomization in an inert gas or vacuum environment, nitrogen gas atomization, argon gas atomization or rotating electrode vacuum plasma atomization is adopted.

[0015] Preferably, the particle size of the ball-milled mixture is not greater than 150 μm.

[0016] Preferably, the methods of thermal spraying or cladding include: laser cladding or ultra-high speed laser cladding, plasma cladding or micro-beam plasma cladding, supersonic flame spraying or supersonic flame spraying plus post-spraying remelting, plasma spraying or plasma spraying plus post-spraying remelting.

[0017] Preferably, before preparing the coating on the surface of the substrate by using the ball-milled mixture by means of thermal spraying or cladding, the surface of the substrate is first subjected to surface treatment, and then the coating is prepared on the surface of the substrate. The process of surface treatment includes: cleaning and roughening the surface of the substrate by means of sandblasting so that the surface roughness of the substrate reaches 25 - 70 μm and the surface cleanliness reaches Sa3.0 level or above; then purging and cleaning the surface of the substrate by means of compressed air.

[0018] The present invention also provides a composite material, which is obtained by the preparation method of the composite material as described above for the present invention.

[0019] Preferably, in the composite material, the thickness of the coating on the surface of the substrate is 0.5 - 2.0 mm.

[0020] The present invention has the following beneficial effects:

[0021] The present invention prepares a coating with oxidation and chlorine corrosion resistance in high-temperature environments based on iron-based alloy powder, aluminum powder, and titanium powder. Compared with traditional nickel-based or cobalt-based alloy powders, the iron-based alloy powder is used in the preparation of the coating of the present invention, significantly reducing the coating preparation cost. At the same time, by reasonably designing the contents of precious metals such as Cr, Ni, and Mo, the chlorine corrosion resistance, oxidation resistance, high-temperature resistance of the alloy system, and the strength of the coating or cladding layer are effectively ensured. By strictly controlling the content of carbon elements in the alloy powder, the stability, plasticity, and toughness of the coating structure are significantly improved, and the decrease in local corrosion resistance caused by the generation of a large amount of carbides at the grain boundaries inside the coating, resulting in Cr depletion at the grain boundaries, is avoided. On the basis of the iron-based alloy powder, by adding a certain proportion of aluminum powder and a small amount of titanium powder, the formation of Cr, Al, and Ti oxides inside and on the surface of the coating is promoted, further enhancing the ability of the coating to resist chloride ion corrosion in high-temperature environments. Detailed implementation mode

[0022] The following further describes the present invention in detail with reference to the embodiments.

[0023] The coating material with oxidation and chlorine corrosion resistance in high-temperature environments of the present invention, in terms of mass percentage, its components include: 60%-70% iron-based alloy powder, 25%-35% aluminum powder, and 5%-10% titanium powder.

[0024] In terms of mass percentage, the composition of the iron-based alloy powder includes: Cr 19%-21%, Ni 17.5%-18.5%, Mo 6.0%-6.5%, Cu 0.5%-1.0%, N 0.15%-0.22%, Si≤0.8%, C≤0.02%, Mn≤1.0%, S≤0.01%, P≤0.02%, and the balance is Fe.

[0025] The aluminum powder is commercial pure aluminum or a mixture of commercial pure aluminum and alumina powder. In the mixed powder, the weight ratio of alumina powder does not exceed 30%; the titanium powder is any one or a mixture of two or more of commercial TA0 powder, TA1 powder, and TA2 powder.

[0026] The preparation method of the composite material of the present invention includes the following processes:

[0027] S100: Prepare iron-based alloy powder with specified composition by the method of melting and atomization in an inert gas or vacuum environment. The method of melting and atomizing to prepare iron-based alloy powder is nitrogen gas atomization, argon gas atomization, or rotating electrode vacuum plasma atomization.

[0028] S200: Weigh iron-based alloy powder, aluminum powder, and titanium powder in proportion, put the composite powder into a ball mill for mixing and grinding to obtain a composite powder with uniform composition. The composite powder obtained after grinding by the ball mill has a uniform composition and the powder particle size <150μm.

[0029] S300: Clean and roughen the surface to be sprayed by sandblasting, so that the roughness of the surface to be sprayed reaches 25 - 70 μm, and the surface cleanliness reaches Sa3.0 or above.

[0030] S400: Use compressed air to remove the excess sand or dust on the surface to be sprayed, and prepare the coating by thermal spraying or cladding. The thermal spraying or cladding methods for preparing the coating include: laser cladding or high - speed laser cladding, plasma cladding, supersonic flame spraying or supersonic flame spraying followed by remelting, plasma spraying or plasma spraying followed by remelting.

[0031] The composite material of the present invention comprises a matrix and the above - mentioned coating formed on the matrix, and the thickness of the coating is 0.5 - 2.0 mm.

[0032] Example 1

[0033] The coating material resistant to oxidation and chlorine corrosion under high - temperature environment in this example, by mass percentage, its components include: 65% iron - based alloy powder, 25% aluminum powder, 10% titanium powder.

[0034] By mass percentage, the composition of the iron - based alloy powder includes: Cr 20%, Ni 18%, Mo 6.0%, Cu 1.0%, N 0.20%, Si 0.6%, C 0.02%, Mn 1.0%, S 0.01%, P 0.01%, and the balance is Fe.

[0035] The aluminum powder is commercial pure aluminum, and the titanium powder is commercial TA2 powder.

[0036] The preparation method of the composite material in this example includes the following processes:

[0037] S100: Prepare the iron - based alloy powder with specified composition by the method of melting and atomization in an inert gas (argon) environment. The method of melting and atomizing to prepare iron - based alloy powder is argon gas atomization.

[0038] S200: Weigh the iron - based alloy powder, aluminum powder and titanium powder according to the proportion, put the composite powder into a ball mill and mix and grind it to obtain a composite powder with uniform composition. The composite powder obtained after grinding by the ball mill has uniform composition and the powder particle size < 150 μm.

[0039] S300: Clean and roughen the surface to be sprayed by sandblasting, so that the roughness of the surface to be sprayed reaches 25 - 70 μm, and the surface cleanliness reaches Sa3.0 or above.

[0040] S400: Use compressed air to remove the excess sand or dust on the surface to be sprayed, and prepare the coating by cladding. The cladding method for preparing the coating is laser cladding.

[0041] The composite material of this embodiment includes a matrix and the above-mentioned coating formed on the matrix. The thickness of the coating is 0.5 mm. The high-temperature oxidation resistance of the coating was tested at 700 °C based on the discontinuous weighing method. After 120 h, the mass change rate of the coating was 5.2 mg / cm 2 . In a chlorine gas atmosphere at 600 °C, 5 mg / cm 2 of the KCI:NaCl = 1:1 mixed chlorate was attached to the surface of the coating specimen. After 168 h, the mass change rate was 5 mg / cm 2 .

[0042] Example 2

[0043] The coating material with oxidation and chlorine corrosion resistance at high temperature in this embodiment, in terms of mass percentage, its components include: 65% iron-based alloy powder, 30% aluminum powder, and 5% titanium powder.

[0044] In terms of mass percentage, the composition of the iron-based alloy powder includes: Cr 21%, Ni 18%, Mo 6.2%, Cu 0.8%, N 0.15%, Si 0.5%, C 0.015%, Mn 0.8%, S 0.008%, P 0.006%, and the balance is Fe.

[0045] The aluminum powder is commercial pure aluminum, and the titanium powder is commercial TA1 powder.

[0046] The preparation method of the composite material of this embodiment includes the following processes:

[0047] S100: Prepare iron-based alloy powder with specified composition by the method of melting and atomization in an inert gas (argon) environment. The method of melting and atomizing to prepare iron-based alloy powder is argon gas atomization.

[0048] S200: Weigh iron-based alloy powder, aluminum powder and titanium powder according to the ratio, put the composite powder into a ball mill and mix and grind it to obtain a composite powder with uniform composition. The composite powder obtained after ball milling has uniform composition and the powder particle size < 150 μm.

[0049] S300: Clean and roughen the surface to be sprayed by sandblasting, so that the surface roughness of the surface to be sprayed reaches 25 - 70 μm, and the surface cleanliness reaches Sa3.0 level or above.

[0050] S400: Use compressed air to remove the excess sand or dust on the surface to be sprayed, and prepare the coating by the method of cladding. The cladding method used to prepare the coating is plasma cladding.

[0051] The composite material of this embodiment includes a matrix and the above-mentioned coating formed on the matrix, and the thickness of the coating is 0.8 mm. The high-temperature oxidation resistance of the coating was tested at 700 °C based on the discontinuous weighing method. After 120 h, the mass change rate of the coating was 4.5 mg / cm 2 . In a chlorine gas atmosphere at 600 °C, 5 mg / cm 2 of a KCI:NaCl = 1:1 mixed chlorate was attached to the surface of the coating specimen. After 168 h, the mass change rate was 6.5 mg / cm 2 .

[0052] Example 3

[0053] The coating material with oxidation and chlorine corrosion resistance at high temperature in this embodiment, in terms of mass percentage, its components include: 60% iron-based alloy powder, 30% aluminum powder, and 10% titanium powder.

[0054] In terms of mass percentage, the composition of the iron-based alloy powder includes: 19% Cr, 17.5% Ni, 6.5% Mo, 0.5% Cu, 0.22% N, 0.7% Si, 0.02% C, 0.9% Mn, 0.008% S, 0.01% P, and the balance is Fe.

[0055] The aluminum powder is a commercial pure aluminum and alumina mixed powder, in which the weight percentage of alumina is 10%, and the titanium powder is commercial TA2 powder.

[0056] The preparation method of the composite material of this embodiment includes the following processes:

[0057] S100: Prepare iron-based alloy powder with specified composition by the method of melting and atomization in an inert gas (argon) environment. The method of melting and atomizing to prepare iron-based alloy powder is rotary electrode vacuum plasma atomization.

[0058] S200: Weigh iron-based alloy powder, aluminum powder and titanium powder according to the ratio, and put the composite powder into a ball mill for mixing and grinding to obtain a composite powder with uniform composition. The composite powder obtained after ball milling has a uniform composition and the powder particle size < 150 μm.

[0059] S300: Clean and roughen the surface to be sprayed by sandblasting, so that the surface roughness of the surface to be sprayed reaches 25 - 70 μm, and the surface cleanliness reaches Sa3.0 level or above.

[0060] S400: Use compressed air to remove excess sand or dust on the surface to be sprayed, and prepare the coating by thermal spraying. The thermal spraying method used to prepare the coating is supersonic flame spraying.

[0061] The composite material of this embodiment includes a matrix and the above-mentioned coating formed on the matrix. The thickness of the coating is 1.2 mm. Based on the discontinuous weighing method, the high-temperature oxidation resistance of the coating was tested at 700 °C. After 120 h, the mass change rate of the coating was 4 mg / cm 2 . In a chlorine gas atmosphere at 600 °C, 5 mg / cm 2 of a KCI:NaCl = 1:1 mixed chlorate was attached to the surface of the coating specimen. After 168 h, the mass change rate was 5.5 mg / cm 2 .

[0062] Example 4

[0063] The coating material with oxidation and chlorine corrosion resistance at high temperature in this embodiment, in terms of mass percentage, its components include: 70% iron-based alloy powder, 25% aluminum powder, and 5% titanium powder.

[0064] In terms of mass percentage, the composition of the iron-based alloy powder includes: 20% Cr, 18% Ni, 6.0% Mo, 1.0% Cu, 0.15% N, 0.6% Si, 0.01% C, 0.6% Mn, 0.008% S, 0.01% P, and the balance is Fe.

[0065] The aluminum powder is commercial pure aluminum, and the titanium powder is a commercial TA0, TA1, TA2 mixed powder with a mixing ratio of 1:1:1.

[0066] The preparation method of the composite material of this embodiment includes the following processes:

[0067] S100: Prepare iron-based alloy powder with specified composition by the method of melting and atomization in an inert gas (argon) environment. The method of melting and atomizing to prepare iron-based alloy powder is nitrogen gas atomization.

[0068] S200: Weigh iron-based alloy powder, aluminum powder and titanium powder according to the ratio, and put the composite powder into a ball mill for mixing and grinding to obtain a composite powder with uniform composition. The composite powder obtained after grinding by the ball mill has uniform composition and the powder particle size < 150 μm.

[0069] S300: Clean and roughen the surface to be sprayed by sandblasting, so that the surface roughness of the surface to be sprayed reaches 25 - 70 μm, and the surface cleanliness reaches Sa3.0 level or above.

[0070] S400: Use compressed air to remove excess sand or dust on the surface to be sprayed, and prepare the coating by thermal spraying. The thermal spraying method used to prepare the coating is plasma spraying.

[0071] The composite material of this embodiment includes a matrix and the above-mentioned coating formed on the matrix. The thickness of the coating is 1.5 mm. Based on the discontinuous weighing method, the high-temperature oxidation resistance of the coating was tested at 700 °C. After 120 h, the mass change rate of the coating was 4.3 mg / cm 2 . In a chlorine gas atmosphere at 600 °C, 5 mg / cm 2 of the KCI:NaCl = 1:1 mixed chlorate was attached to the surface of the coating specimen. After 168 hours, the mass change rate was 6.5 mg / cm 2 .

[0072] Example 5

[0073] The coating material with oxidation and chlorine corrosion resistance in high-temperature environment of this embodiment, by mass percentage, its components include: 60% iron-based alloy powder, 35% aluminum powder, 5% titanium powder.

[0074] By mass percentage, the composition of the iron-based alloy powder includes: Cr 21%, Ni 18.5%, Mo 6.2%, Cu 0.8%, N 0.20%, Si 0.7%, C 0.02%, Mn 0.7%, S 0.005%, P 0.005%, and the balance is Fe.

[0075] The aluminum powder is commercial pure aluminum powder, and the titanium powder is commercial TA0 powder.

[0076] The preparation method of the composite material of this embodiment includes the following processes:

[0077] S100: Prepare iron-based alloy powder with specified composition by the method of melting and atomization in an inert gas (argon) environment. The method of melting and atomizing to prepare iron-based alloy powder is argon gas atomization.

[0078] S200: Weigh iron-based alloy powder, aluminum powder and titanium powder according to the ratio, and put the composite powder into a ball mill for mixing and grinding to obtain a composite powder with uniform composition. The composite powder obtained after ball milling has uniform composition and the powder particle size < 150 μm.

[0079] S300: Clean and roughen the surface to be sprayed by sandblasting, so that the surface roughness of the surface to be sprayed reaches 25 - 70 μm, and the surface cleanliness reaches Sa3.0 level or above.

[0080] S400: Use compressed air to remove excess sand or dust on the surface to be sprayed, and prepare the coating by thermal spraying. The thermal spraying method used to prepare the coating is supersonic flame spraying plus post-spraying remelting.

[0081] The composite material of this embodiment includes a matrix and the above-mentioned coating formed on the matrix, and the thickness of the coating is 2.0 mm. Based on the discontinuous weighing method, the high-temperature oxidation resistance of the coating was tested at 700 °C. After 120 h, the mass change rate of the coating was 3.5 mg / cm 2 . In a chlorine gas atmosphere at 600 °C, after 168 hours of attaching a KCI:NaCl = 1:1 mixed chlorate of 5 mg / cm 2 to the surface of the coating specimen, the mass change rate was 5.5 mg / cm 2 .

Claims

1. A coating material resistant to oxidation and chlorine corrosion in high-temperature environments, characterized in that, In terms of mass percentage, its components include: 60%-70% iron-based alloy powder, 25%-35% aluminum powder, and 5%-10% titanium powder; In terms of mass percentage, the composition of the iron-based alloy powder includes: Cr 19%-21%, Ni 17.5%-18.5%, Mo 6.0%-6.5%, Cu 0.5%-1.0%, N 0.15%-0.22%, Si≤0.8%, C≤0.02%, Mn≤1.0%, S≤0.01%, P≤0.02%, and the balance is Fe; The aluminum powder is a mixture of pure aluminum and alumina powder or pure aluminum powder. In the mixture of pure aluminum and alumina powder, the weight ratio of alumina does not exceed 30%.

2. A coating material resistant to oxidation and chlorine corrosion in a high-temperature environment according to claim 1, characterized in that, The titanium powder is a mixture of one or more of TA0 powder, TA1 powder, and TA2 powder.

3. A method for preparing a composite material, characterized in that, It includes the following process: Ball-mill the coating material resistant to oxidation and chlorine corrosion in a high-temperature environment described in Claim 1 or 2 to obtain a uniformly mixed ball-milled mixture; Use thermal spraying or cladding methods to prepare a coating on the substrate surface using the ball-milled mixture to obtain the composite material.

4. The preparation method of a composite material according to claim 3, characterized in that, Prepare the iron-based alloy powder by the method of melting and atomization in an inert gas or vacuum environment.

5. The preparation method of a composite material according to claim 4, characterized in that, When preparing the iron-based alloy powder by the method of melting and atomization in an inert gas or vacuum environment, use nitrogen gas atomization, argon gas atomization, or rotary electrode vacuum plasma atomization.

6. The preparation method of a composite material according to claim 3, characterized in that The particle size of the ball-milled mixture is not greater than 150 μm.

7. The preparation method of a composite material according to claim 3, characterized in that The thermal spraying or cladding methods include: laser cladding, plasma cladding, supersonic flame spraying or supersonic flame spraying plus post-spraying remelting, plasma spraying or plasma spraying plus post-spraying remelting.

8. The preparation method of a composite material according to claim 3, characterized in that, Before using thermal spraying or cladding methods to prepare a coating on the substrate surface using the ball-milled mixture, first perform surface treatment on the substrate, and then prepare a coating on the substrate surface. The surface treatment process includes: cleaning and roughening the substrate surface by sandblasting to make the surface roughness of the substrate reach 25-70 μm and the surface cleanliness reach Sa3.0 level or above; then use compressed air to blow and clean the substrate surface.

9. A composite material, characterized in that, This composite material is prepared by the preparation method of the composite material described in any one of Claims 3-8.

10. The composite material according to claim 9, characterized in that, The thickness of the coating on the substrate surface is 0.5-2.0 mm.