High-temperature resistant and corrosion-resistant coating powder, coating, preparation method and application

Abstract

The present invention provides a high-temperature and corrosion-resistant coating powder, a coating, a preparation method and an application thereof. The high-temperature and corrosion-resistant coating powder comprises inorganic powder. The inorganic powder, by mass percentage, comprises: 36-60% of silica powder, 12-17% of Cr powder, 1-4% of Si powder, 17-23% of Mo powder, and 10-20% of Ni 80 Cr 20 powder. The coating is made of the high-temperature and corrosion-resistant coating powder. The high-temperature and corrosion-resistant coating powder provided by the present invention forms a three-component functional component. The high-temperature and corrosion-resistant coating has good compactness, a porosity lower than 1.5%, high hardness, a Vickers hardness reaching 500-850 HV, good wear resistance, excellent high-temperature and corrosion-resistant performance, a service temperature above 800 °C, good stability in a corrosive medium of an acid or a salt solution, and a high bonding strength between the coating and the substrate, reaching 100-200 MPa.

Description

Technical Field

[0001] The present invention belongs to the technical field of corrosion protection, and relates to a high-temperature and corrosion-resistant protective coating, in particular to a high-temperature and corrosion-resistant coating powder, coating, preparation method and application thereof. Background Art

[0002] Waste incineration power generation has the advantages of reduction, harmlessness, resource utilization, etc., and is recognized as the best way to treat waste. In waste incineration, the fuel sources are diverse and difficult to control. During the high-temperature combustion process, a large amount of alkali metal chlorides and sulfates, such as KCl, Na 2 SO 4 etc., as well as ash, and corrosive gases such as HCl, SO 2 etc. are generated. During the long-term operation of the waste incinerator, its key heating surfaces, including the water-cooled wall, superheater, boiler tube bundle and some heat exchange equipment in the furnace, are eroded by multiple factors such as high temperature, oxidation and corrosion. The high-concentration reducing H 2 S gas in the flue gas and the sulfides, sulfates, chlorides and other flue gases and dust adhering to the surface of the heating surface continuously damage the protective oxide film on the surface of the tube furnace, and directly undergo complex chemical reactions with the steel substrate of the tube furnace wall, continuously eroding the tube wall of the heating surface, resulting in too rapid thinning of the tube wall, frequent occurrence of tube explosion phenomena, shortening of the equipment life, seriously affecting the economy and safety of boiler operation, and increasing the maintenance cost. Therefore, the serious problem of high-temperature corrosion of materials during waste incineration will undoubtedly become the key problem restricting the effective operation of waste incinerators.

[0003] In order to improve the durability of the tube wall of the incinerator, the prior art usually uses surface coatings for protection. The coating processes of surface coatings mainly include laser cladding process, wire welding technology, thermal spraying technology, induction remelting technology, etc. The laser cladding process can form a cladding layer with excellent performance, but there are limitations such as expensive equipment and difficulty in construction for large-area and complex-shaped workpieces; the wire welding technology can achieve lower heat influence and higher deposition efficiency, but the residual stress after welding is large, which is easy to cause coating cracking, and the material dilution rate is high, so its corrosion resistance at high temperature needs to be improved; the thermal spraying technology is widely used and easy to construct, but the coating porosity is relatively high, about 1.5 - 5%, and the density is poor, resulting in poor protection effect and the bonding strength with the substrate (generally less than 70 MPa) needs to be improved; the induction remelting technology improves the bonding strength between the coating and the substrate, but the temperature gradient is large during the process, which is easy to cause uneven coating structure, and there are problems of insufficient protection performance and limited process adaptability.

[0004] In the current state of the art for coating materials, the Inconel625 alloy system or NiCr alloy system is mainly used for doping alloy elements such as Al, Si, and Ti. For example, CN108220857A discloses a double-layer alloy coating for preventing chlorine corrosion on the heating surface of a waste incinerator and its preparation method. A double-layer coating structure is adopted, with the bottom layer doped with Ni-based alloy and the surface layer using NiCr and Cr 3 C 2 components. The coating is prepared by thermal spraying; CN117265465A discloses a corrosion-resistant alloy coating for waste incineration boilers and its preparation method, which uses a Ni, Cr, Mo alloy coating and a multi-layer composite metal oxide layer. During preparation, an oxide film is formed by heating and melting corrosion in molten salt. The process is cumbersome, energy-consuming, and time-consuming, which is not conducive to practical applications; CN111778502A discloses a coating for high-temperature chlorine corrosion protection and its preparation method, which also uses a Ni-based alloy for doping multiple metals. The stability and applicable temperature of the coatings of the above materials in the oxidative corrosion environment of the waste incineration atmosphere still need to be improved.

[0005] Therefore, due to the deficiencies of the existing technology, there is a need to provide a high-temperature and corrosion-resistant coating powder, coating, preparation method, and application. Summary of the Invention

[0006] The purpose of the present invention is to provide a high-temperature and corrosion-resistant coating powder, coating, preparation method, and application. Aiming at the high-temperature incineration environment and the corrosion effect of high sulfur and chlorine concentrations in waste incinerators, the compactness and corrosion resistance of the coating are improved, and the protection of the incinerator tube wall is enhanced.

[0007] To achieve the purpose of this invention, the following technical solutions are adopted:

[0008] In the first aspect, the present invention provides a high-temperature and corrosion-resistant coating powder, and the high-temperature and corrosion-resistant coating powder includes inorganic powder;

[0009] The composition of the inorganic powder is calculated by mass percentage and includes: silica powder 36 - 60%, Cr powder 12 - 17%, Si powder 1 - 4%, Mo powder 17 - 23%, Ni 80 Cr 20 powder 10 - 20%.

[0010] The coating powder provided by the present invention uses silica powder as the main component, and the silica includes but is not limited to silicon dioxide, quartz, or cristobalite.

[0011] The components of the coating powder of the present invention mainly play the following roles:

[0012] (1) During the coating deposition process, molten SiO 2Particles impact on the substrate surface to form a dense amorphous SiO film stacked layer by layer, which serves as the basic framework of the coating. Other alloy components are filled in the interlayer stacking voids of the flattened particles in the form of adhesives or as mechanical mixtures. Compared with the coatings of all alloy components in the current technology, the coatings of the present invention have higher hardness and chemical stability, which can improve the erosion and wear resistance of the coatings during the waste incineration process. 2 film and serve as the basic framework of the coating. Other alloy components are filled in the SiO 2 interlayer stacking voids of the flattened particles. Compared with the coatings of all alloy components in the current technology, the coatings of the present invention have higher hardness and chemical stability, which can improve the erosion and wear resistance of the coatings during the waste incineration process.

[0013] (2) SiO 2 has stable chemical properties and good high-temperature resistance. As an acidic oxide, silicon dioxide does not react with common acids (such as hydrochloric acid, sulfuric acid, nitric acid, etc.) and has excellent corrosion resistance, playing a basic protective role in the coating, especially suitable for the acidic corrosive gas atmosphere of waste incineration flue gas. SiO 2 has a relatively well-matched thermal expansion coefficient with the metal matrix material (about 2×10 -6 / K), which is suitable for preparing coatings to ensure good adhesion between the coating and the substrate.

[0014] (3) Ni and Cr act as metal bonding phases in the coating, playing a role in resisting sulfide and chloride corrosion. Mo mainly plays a role in high-temperature oxidation resistance and wear resistance. Nickel and chromium, as metal bonding phases, play the role of rivets for the flattened SiO 2 serving as the basic framework. During the service of the coating, nickel, chromium, and molybdenum mainly play a role in resisting high-temperature corrosion of sulfide and chloride flue gases. The addition of molybdenum can increase the high-temperature oxidation resistance and a certain degree of wear resistance of the coating. The high-temperature oxidation and corrosion resistance increase to a certain extent with the increase in the chromium element content. As the service time of the coating increases, the Cr metal alloy will be gradually oxidized into chromium oxide, increasing the density of the coating oxide film and improving and prolonging the effective protective effect of the coating; using Ni 80 Cr 20 alloy powder components in the powder has better corrosion resistance, oxidation resistance, wear resistance, and thermal stability compared with adding Cr powder and Ni powder separately. The working temperature of the Ni 80 Cr 20 alloy can be as high as 1200°C. The additional addition of Cr powder is to improve the corrosion resistance of the coating structure. At the same time, the proportion of Cr metal acting as the bonding phase is increased to improve the cohesion of the coating. The additional addition of Mo powder is to improve the high-temperature oxidation resistance of the coating structure; Si element is dissolved into the nickel, chromium, and molybdenum metal lattices during the spraying, melting, and condensation processes of the powder particles to form solid solution precipitation phases, which are dispersed and strengthened in the coating. Adding a certain amount of Si powder can thus overall improve the erosion and scouring resistance of the metal to high-temperature gases. At the same time, when the coating serves in a long-term oxidation and corrosion environment, Si will be oxidized into SiO2 , further increase the compactness of the oxide film.

[0015] The temperature of the high temperature is ≥800 °C.

[0016] Preferably, the particle size distribution D90 of the silica powder is 45 - 90 μm, for example, it can be 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm or 90 μm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0017] Preferably, the particle size distribution D90 of the Cr powder is 5 - 20 μm, for example, it can be 5 μm, 10 μm, 15 μm or 20 μm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0018] Preferably, the particle size distribution D90 of the Si powder is 1 - 5 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0019] Preferably, the particle size distribution D90 of the Mo powder is 1 - 5 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0020] Preferably, the Ni 80 Cr 20 The particle size distribution D90 of the powder is 5 - 25 μm, for example, it can be 5 μm, 10 μm, 15 μm, 20 μm or 25 μm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0021] In the present invention, coating powders with a specific particle size distribution are selected. During the mechanical coating preparation process of the coating powders, fine particles are uniformly coated on the surface of coarse particles, forming a powder composition with silica as the core and other component powders coated layer by layer, having good compositional uniformity and spraying processability.

[0022] The high-temperature corrosion-resistant coating powder further includes a binder.

[0023] The content of the binder is 1 - 10% of the inorganic powder, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0024] The binder includes any one or a combination of at least two of polyvinylpyrrolidone, polyvinyl alcohol, cyclodextrin, epoxy resin, carboxymethyl cellulose, sodium metasilicate or alkyd varnish. Typical but non-limiting combinations include the combination of polyvinylpyrrolidone and polyvinyl alcohol, the combination of cyclodextrin and epoxy resin, the combination of carboxymethyl cellulose and sodium metasilicate, the combination of polyvinylpyrrolidone, polyvinyl alcohol and cyclodextrin, or the combination of epoxy resin, carboxymethyl cellulose, sodium metasilicate and alkyd varnish.

[0025] In a second aspect, the present invention provides a method for preparing the high-temperature and corrosion-resistant coating powder described in the first aspect. The preparation method includes the following steps:

[0026] (1) Mix the component powders according to the composition of the inorganic powder and perform ball milling to obtain a premixed raw material;

[0027] (2) Perform mechanical coating powder making on the premixed raw material obtained in step (1) to obtain the high-temperature and corrosion-resistant coating powder.

[0028] The coating powder preparation method provided by the present invention uses mechanical coating powder making. For the multi-component composition of the coating powder, it can achieve particle coating in a short time and form a binder film layer on the surface, form composite particles according to the particle size distribution of the component powders, obtain coating powders with good composition uniformity, powder fluidity, particle size distribution and tight coating, and have good coating spraying processability.

[0029] Preferably, the time of the ball milling is 8 - 12 h. For example, it can be 8 h, 9 h, 10 h, 11 h or 12 h, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0030] Preferably, the rotation speed of the ball milling is 200 - 600 RPM. For example, it can be 200 RPM, 300 RPM, 400 RPM, 500 RPM or 600 RPM, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0031] Preferably, the ball-to-material ratio of the ball milling is 2:(4 - 10). For example, it can be 2:4, 2:5, 2:6, 2:7, 2:8, 2:9 or 2:10, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0032] Preferably, the medium of the ball milling includes silica.

[0033] Preferably, the mechanical coating powder making is two-stage mechanical coating powder making, including the first mechanical coating powder making and the second mechanical coating powder making carried out in sequence.

[0034] Preferably, the distance between the extrusion head and the kettle wall for the first mechanical coating and powder making is 0.5 - 3 cm. For example, it can be 0.5 cm, 1 cm, 1.5 cm, 2 cm, 2.5 cm or 3 cm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0035] Preferably, the rotational speed of the rotor for the first mechanical coating and powder making is 500 - 1200 r / min. For example, it can be 500 r / min, 600 r / min, 700 r / min, 800 r / min, 900 r / min, 1000 r / min, 1100 r / min or 1200 r / min, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0036] Preferably, the coating time for the first mechanical coating and powder making is 10 - 25 min. For example, it can be 10 min, 12 min, 15 min, 18 min, 20 min, 22 min or 25 min, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0037] Preferably, the distance between the extrusion head and the kettle wall for the second mechanical coating and powder making is 0.5 - 3 cm. For example, it can be 0.5 cm, 1 cm, 1.5 cm, 2 cm, 2.5 cm or 3 cm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0038] Preferably, the rotational speed of the rotor for the second mechanical coating and powder making is 1500 - 2000 r / min. For example, it can be 1500 r / min, 1600 r / min, 1700 r / min, 1800 r / min, 1900 r / min or 2000 r / min, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0039] Preferably, the coating time for the second mechanical coating and powder making is 5 - 10 min. For example, it can be 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0040] Preferably, a binder is also added in the mechanical coating and powder making.

[0041] Preferably, the binder includes any one or a combination of at least two of polyvinylpyrrolidone, polyvinyl alcohol, cyclodextrin, epoxy resin, carboxymethyl cellulose, sodium metasilicate or alkyd varnish. Typical but non-limiting combinations include the combination of polyvinylpyrrolidone and polyvinyl alcohol, the combination of cyclodextrin and epoxy resin, the combination of carboxymethyl cellulose and sodium metasilicate, the combination of polyvinylpyrrolidone, polyvinyl alcohol and cyclodextrin, or the combination of epoxy resin, carboxymethyl cellulose, sodium metasilicate and alkyd varnish.

[0042] Preferably, the dosage of the binder is 1-10% of the mass of the premixed raw materials. For example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0043] In the present invention, a two-stage mechanical coating preparation process is adopted. First, coating is carried out at a lower rotational speed to uniformly disperse the materials and the binder, and then the coating rotational speed is increased to achieve the coating of fine particle powder on the surface of coarse particle powder and the uniform coating of the binder.

[0044] Preferably, after the mechanical coating to make powder, drying and screening are carried out in sequence.

[0045] Preferably, the temperature of the drying is 100-120 °C. For example, it can be 100 °C, 105 °C, 110 °C, 115 °C or 120 °C, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0046] Preferably, the time of the drying is 2-6 h. For example, it can be 2 h, 3 h, 4 h, 5 h or 6 h, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0047] Preferably, the screening adopts the vibration screening method.

[0048] Preferably, the loose bulk density of the high-temperature and corrosion-resistant powder is 3.1-3.6 g / cm 3 , for example, it can be 3.1 g / cm 3 , 3.2 g / cm 3 , 3.3 g / cm 3 , 3.4 g / cm 3 , 3.5 g / cm 3 or 3.6 g / cm 3 , but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0049] Preferably, the particle size range of the high-temperature and corrosion-resistant powder is 60 - 125 μm. For example, it can be 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm or 125 μm, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0050] In a third aspect, the present invention provides a high-temperature and corrosion-resistant coating, which is made of the high-temperature and corrosion-resistant coating powder described in the first aspect.

[0051] The sources of solid waste are diverse, with high chlorine and sulfur concentrations and high elemental activity. Under the high-temperature conditions of incineration, it can react with almost all metals and form chlorides and sulfides with low melting points and high vapor pressures. At the same time, it increases the oxygen partial pressure required to form a protective oxide film, causing the oxide film to crack and become porous, reducing its effective adhesion and protection. As a result, the corrosion of the incinerator often starts with internal oxidation and selectively corrodes preferentially along the grain boundaries inside the alloy.

[0052] In the high-temperature and corrosion-resistant coating provided by the present invention, silica, as an amorphous oxide, forms a dense SiO 2 oxide film in the coating, which is the basic framework in the coating and has excellent corrosion resistance compared to the alloy components; nickel and chromium, as metal bonding phases, play the role of riveting and flattening SiO 2 as the basic framework phase. During the service of the coating, nickel, chromium, and molybdenum mainly play the role of resisting high-temperature corrosion of sulfide and chloride flue gases. The addition of molybdenum can increase the high-temperature oxidation resistance and a certain degree of wear resistance of the coating in the coating. The high-temperature oxidation and corrosion resistance increase to a certain extent with the increase in the chromium element content. As the service time of the coating increases, the Cr metal alloy will be gradually oxidized into chromium oxide, increasing the density of the coating oxide film and improving and prolonging the effective protection performance of the coating; the Si element is dissolved into the nickel, chromium, and molybdenum metal lattices during the spraying, melting, and condensation processes of the powder particles to form a solid solution precipitation phase and is dispersed and strengthened in the coating, thereby overall increasing the erosion and erosion resistance of the metal phase to high-temperature gases. At the same time, after the coating has been in service in an oxidation and corrosion environment for a long time, Si will be oxidized into SiO 2 to further increase the density of the oxide film.

[0053] In a fourth aspect, the present invention provides a preparation method for the high-temperature and corrosion-resistant coating described in the third aspect, and the preparation method includes the following steps:

[0054] After pre-treating the substrate, atmospheric plasma spraying is carried out using the high-temperature and corrosion-resistant coating powder, and then heat treatment is carried out to obtain the high-temperature and corrosion-resistant coating.

[0055] The coating preparation method provided by the present invention adopts atmospheric plasma spraying to achieve uniform coating of the coating, and is not limited by the size and shape of the workpiece, obtaining a spraying coating with good uniformity. Then, heat treatment is carried out. The heat treatment makes the Cr 2 O 3 , SiO 2 and other amorphous glass phases in the coating fill the pores of the coating to form a coating with a self-sealing structure, so as to reduce the coating porosity to achieve a self-sealing effect. At the same time, when not heat-treated, the coating components form an interlaced stacked coating structure and are mechanically combined with the substrate through a serrated interface. After heat treatment, a micro-metallurgical bonding effect is generated between the coating and the metal matrix, increasing the bonding strength between the coating and the substrate.

[0056] Preferably, the pretreatment includes cleaning, drying and sandblasting in sequence.

[0057] Preferably, the cleaning reagents include alcohol and / or acetone.

[0058] Preferably, the cleaning method includes using ultrasonic and / or manual wiping.

[0059] Preferably, the drying temperature is 60-90 °C, for example, it can be 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C or 90 °C, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0060] Preferably, the sandblasting pressure is 0.2-0.6 MPa, for example, it can be 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa or 0.6 MPa, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0061] Preferably, the sandblasting distance is 30-150 mm, for example, it can be 30 mm, 50 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm or 150 mm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0062] Preferably, the sandblasting abrasive includes 24# corundum sand.

[0063] Preferably, the surface roughness Sa of the substrate after sandblasting is ≥2.5, for example, it can be 2.5, 2.8, 3.0, 4.0, 5.0, 8.0, 10.0 or 15.0, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0064] Preferably, the main gas for the atmospheric plasma spraying is argon, and the auxiliary gas is hydrogen.

[0065] Preferably, the current of the atmospheric plasma spraying is 500 - 800 A. For example, it can be 500 A, 550 A, 600 A, 650 A, 700 A, 750 A or 800 A, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0066] In the present invention, the energy of the plasma jet is adjusted by adjusting the current and the auxiliary gas.

[0067] Preferably, the voltage of the atmospheric plasma spraying is 60 - 100 V. For example, it can be 60 V, 70 V, 80 V, 90 V or 100 V, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0068] Preferably, the main gas flow rate of the atmospheric plasma spraying is 40 - 120 L / min. For example, it can be 40 L / min, 50 L / min, 60 L / min, 80 L / min, 100 L / min or 120 L / min, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0069] Preferably, the main gas pressure of the atmospheric plasma spraying is 0.3 - 0.9 MPa. For example, it can be 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa or 0.9 MPa, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0070] Preferably, the auxiliary gas flow rate of the atmospheric plasma spraying is 1 - 25 L / min. For example, it can be 1 L / min, 5 L / min, 10 L / min, 15 L / min, 20 L / min or 25 L / min, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0071] Preferably, the auxiliary gas pressure of the atmospheric plasma spraying is 0.5 - 0.9 MPa. For example, it can be 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa or 0.9 MPa, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0072] In the present invention, reasonable amounts of primary gas and auxiliary gas are controlled to achieve the preparation of a coating with good performance. During atmospheric plasma spraying, the supply of the primary gas argon mainly serves to initiate the plasma arc and continuously form a plasma flame. Hydrogen, due to its high heat enthalpy value H, acts as the second gas to provide the thermal energy for a high-energy plasma flame. When the content of hydrogen increases, the Ni, Cr, and Mo metal materials in the powder material particles are more likely to be oxidized during the sputtering process, thereby forming their metal oxides in the coating. However, the content of metal oxides must be controlled within a certain range. Excessive oxides will reduce the bonding phase in the coating and easily lead to coating embrittlement. On the other hand, a decrease in the hydrogen content will result in too low a heat enthalpy value of the plasma flame, making it difficult for the powder material particles to melt and reducing the effective deposition rate of the coating, thus changing the effective proportion of each component in the coating and the original powder, and ultimately affecting the wear resistance, corrosion resistance, high-temperature oxidation resistance, and even mechanical properties of the coating.

[0073] Preferably, the powder feeding rate of the atmospheric plasma spraying is 20 - 150 g / min, for example, it can be 20 g / min, 40 g / min, 50 g / min, 60 g / min, 80 g / min, 100 g / min, 120 g / min, 140 g / min, or 150 g / min, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0074] Preferably, the powder feeding gas flow rate of the atmospheric plasma spraying is 2.0 - 18.0 L / min, for example, it can be 2.0 L / min, 4.0 L / min, 5.0 L / min, 6.0 L / min, 8.0 L / min, 10.0 L / min, 12.0 L / min, 14.0 L / min, 15.0 L / min, 16.0 L / min, or 18.0 L / min, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0075] Preferably, the powder feeding gas pressure of the atmospheric plasma spraying is 0.8 - 1.2 MPa, for example, it can be 0.8 MPa, 0.85 MPa, 0.9 MPa, 1.0 MPa, or 1.2 MPa, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0076] Preferably, the scanning speed of the atmospheric plasma spraying is 160 - 200 m / min, for example, it can be 160 m / min, 170 m / min, 180 m / min, 190 m / min, or 200 m / min, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0077] Preferably, the spraying distance of the atmospheric plasma spraying is 150 - 300 mm, for example, it can be 150 mm, 180 mm, 200 mm, 220 mm, 250 mm, 280 mm or 300 mm, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0078] Preferably, the spraying angle of the atmospheric plasma spraying is 70 - 90°, for example, it can be 70°, 75°, 80°, 85° or 90°, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0079] Preferably, during the atmospheric plasma spraying process, the surface temperature of the substrate is controlled to be 25 - 150 °C, for example, it can be 25 °C, 50 °C, 80 °C, 100 °C, 120 °C or 150 °C, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0080] Preferably, during the atmospheric plasma spraying process, compressed air is used for cooling.

[0081] Preferably, the pressure of the cooling is 0.5 - 0.6 MPa, for example, it can be 0.5 MPa, 0.52 MPa, 0.55 MPa, 0.58 MPa or 0.6 MPa, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0082] Preferably, the temperature of the heat treatment is 900 - 1100 °C, for example, it can be 900 °C, 950 °C, 1000 °C, 1050 °C or 1100 °C, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0083] Preferably, the holding time of the heat treatment is 6 - 18 h, for example, it can be 6 h, 8 h, 10 h, 12 h, 14 h, 15 h, 16 h or 18 h, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0084] Preferably, the heat treatment is carried out in a vacuum environment, and the vacuum degree is 1×10 -2 -5×10 -3 Pa, for example, it can be 5×10 -3 Pa, 6×10 -3 Pa, 7×10 -3 Pa, 8×10 -3 Pa, 9×10 -3 Pa or 1×10 -2 , but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0085] As a preferred technical solution of the preparation method of the high-temperature and corrosion-resistant coating provided by the present invention, the preparation method comprises the following steps:

[0086] (a) Mix the component powders according to the composition of the inorganic powder and carry out ball milling;

[0087] The composition of the inorganic powder by mass percentage includes: silica powder 36-60%, Cr powder 12-17%, Si powder 1-4%, Mo powder 17-23%, Ni 80 Cr 20 powder 10-20%; wherein, the particle size distribution D90 of the silica powder is 45-90 μm, the particle size distribution D90 of the Cr powder is 5-20 μm, the particle size distribution D90 of the Si powder is 1-5 μm, the particle size distribution D90 of the Mo powder is 1-5 μm, and the particle size distribution D90 of the Ni 80 Cr 20 powder is 5-25 μm;

[0088] The time of the ball milling is 8-12 h, the rotation speed of the ball milling is 200-600 RPM, the ball-to-material ratio of the ball milling is 2:(4-10), the medium of the ball milling includes silica, and the pre-mixed raw material is obtained after the ball milling;

[0089] (b) Carry out two-stage mechanical coating powder making on the pre-mixed raw material obtained in step (a) and the binder. The dosage of the binder is 1-10% of the mass of the pre-mixed raw material. The distance between the extrusion head and the kettle wall in the first-stage mechanical coating powder making is 0.5-3 cm, the rotation speed of the rotor is 500-1200 r / min, the coating time is 10-25 min, the distance between the extrusion head and the kettle wall in the second-stage mechanical coating powder making is 0.5-3 cm, the rotation speed of the rotor is 1500-2000 r / min, and the coating time is 5-10 min to obtain the coated powder;

[0090] (c) Dry and screen the obtained coated powder. The drying temperature is 100-120 °C, the drying time is 2-6 h, and the high-temperature and corrosion-resistant coating powder is obtained. The particle size range of the high-temperature and corrosion-resistant coating powder is 60-125 μm, and the loose bulk density is 3.1-3.6 g / cm 3 ;

[0091] (d) Carry out cleaning, drying and sandblasting pretreatment on the substrate in sequence. The cleaning reagent includes alcohol and / or acetone, the drying temperature is 60-90 °C, the sandblasting pressure is 0.2-0.6 MPa, the sandblasting distance is 30-150 mm, the sandblasting abrasive includes 24# corundum sand, and the surface roughness Sa of the substrate after sandblasting is ≥2.5;

[0092] (e) Perform atmospheric plasma spraying using the high-temperature and corrosion-resistant coating powder.

[0093] The process parameters of the atmospheric plasma spraying include: the main gas is argon, the auxiliary gas is hydrogen, the current is 500 - 800 A, the voltage is 60 - 100 V, the main gas flow rate is 40 - 120 L / min, the main gas pressure is 0.3 - 0.9 MPa, the auxiliary gas flow rate is 1 - 25 L / min, the auxiliary gas pressure is 0.5 - 0.9 MPa, the powder feeding rate is 20 - 150 g / min, the powder feeding gas flow rate is 2.0 - 18.0 L / min, the powder feeding gas pressure is 0.8 - 1.2 MPa, the scanning speed is 160 - 200 m / min, the spraying distance is 150 - 300 mm, the spraying angle is 70 - 90°. During the atmospheric plasma spraying process, control the substrate surface temperature at 25 - 150 °C. During the atmospheric plasma spraying process, use compressed air for cooling, and the pressure of the cooling is 0.5 - 0.6 MPa to obtain a sprayed coating.

[0094] (f) Heat-treat the sprayed coating obtained in step (e). The temperature of the heat treatment is 900 - 1100 °C, the heat preservation time of the heat treatment is 6 - 18 h, and the heat treatment is carried out in a vacuum environment with a vacuum degree of 1×10 -2 -5×10 -3 Pa to obtain the high-temperature and corrosion-resistant coating.

[0095] In the fifth aspect, the present invention provides an application of the high-temperature and corrosion-resistant coating described in the third aspect, and the high-temperature and corrosion-resistant coating is used for a waste incinerator.

[0096] Compared with the prior art, the present invention has the following beneficial effects:

[0097] The high-temperature and corrosion-resistant coating powder provided by the present invention forms a three-component functional component with SiO 2 as the basic framework, nickel, chromium, and molybdenum metals as the bonding phase, and Si forming dispersion strengthening. The high-temperature and corrosion-resistant coating has good denseness, the porosity is lower than 1.5%, and it can produce a self-sealing effect during long-term service. It has high hardness, the Vickers hardness reaches 500 - 850 HV, good wear resistance, excellent high-temperature and corrosion-resistant performance, the use temperature is above 800 °C, and it has good stability in the corrosive medium of acid or salt solution. Moreover, the coating has a high bonding strength with the substrate, reaching 100 - 200 MPa. Description of the Drawings

[0098] Figure 1 is the morphology diagram of the high-temperature and corrosion-resistant coating powder prepared in Example 1;

[0099] Figure 2 is the SEM diagram of the high-temperature and corrosion-resistant coating prepared in Example 1;

[0100] Figure 3 is the SEM image of the high-temperature and corrosion-resistant coating prepared in Example 1 before heat treatment;

[0101] Figure 4 is the SEM image of the high-temperature and corrosion-resistant coating prepared in Example 1 after heat treatment;

[0102] Figure 5 is the SEM image of the high-temperature and corrosion-resistant coating prepared in Example 1 after oxidation corrosion. Detailed implementation manners

[0103] The technical solutions of the present invention will be further described below through specific implementation manners. Those skilled in the art should understand that the described embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0104] Example 1

[0105] This example provides a high-temperature and corrosion-resistant coating powder, and the high-temperature and corrosion-resistant coating powder includes inorganic powder;

[0106] The composition of the inorganic powder is calculated by mass percentage and includes: cristobalite 50%, Cr powder 14%, Si powder 2%, Mo powder 20%, Ni 80 Cr 20 14%;

[0107] The particle size distribution D90 of the cristobalite is 70 μm, the particle size distribution D90 of the Cr powder is 15 μm, the particle size distribution D90 of the Si powder is 2 μm, the particle size distribution D90 of the Mo powder is 4 μm, and the particle size distribution D90 of the Ni 80 Cr 20 is 15 μm.

[0108] The preparation method of the high-temperature and corrosion-resistant coating powder includes the following steps:

[0109] (1) Mix the raw materials according to the composition of the inorganic powder and carry out ball milling. The ball milling speed is 400 rpm, the ball-to-material ratio is 3:8, the ball milling medium is silica balls, and the ball milling time is 10 h to obtain a pre-mixed raw material;

[0110] (2) Carry out two-stage high-speed mechanical coating and powder making on the pre-mixed raw material obtained in step (1) and the binder polyvinylpyrrolidone in an extrusion reaction kettle to obtain coated powder, wherein the dosage of the binder is 5% of the mass of the pre-mixed raw material;

[0111] The process conditions for the first-stage mechanical coating and powder making include: the distance between the extrusion head and the kettle wall is 2 cm, the rotor speed is 800 r / min, and the coating time is 15 min;

[0112] The process conditions for the second-stage mechanical coating powder making include: the distance between the extrusion head and the kettle wall is 2 cm, the rotor speed is 1800 r / min, and the coating time is 8 min;

[0113] (3) Dry the obtained coated powder at 110 °C for 4 h, and then screen it by the vibration screening method to obtain the high-temperature and corrosion-resistant coating powder. The loose bulk density of the powder is measured by a Hall flowmeter to be 3.3 g / cm 3 , and the particle size distribution range of the powder is 60 - 125 μm.

[0114] This embodiment also provides a high-temperature and corrosion-resistant coating, which is made of the above-mentioned high-temperature and corrosion-resistant coating powder.

[0115] The preparation method of the high-temperature and corrosion-resistant coating includes the following steps:

[0116] (Ⅰ) Using the waste incinerator tube as the substrate, clean the inner wall of the incinerator tube with alcohol and dry it at 75 °C. After drying, roughen and activate the surface to be sprayed by sandblasting. The sandblasting pressure is 0.4 MPa, the sandblasting distance is 100 mm, and the sand grain material is 24# corundum sand to make the surface roughness reach Sa2.5;

[0117] (Ⅱ) Perform atmospheric plasma spraying on the substrate with the high-temperature and corrosion-resistant coating powder;

[0118] The process parameters of the atmospheric plasma spraying include: the main gas is argon, the auxiliary gas is hydrogen, the current is 650 A, the voltage is 80 V, the main gas flow rate is 80 L / min, the main gas pressure is 0.6 MPa, the auxiliary gas flow rate is 15 L / min, the auxiliary gas pressure is 0.7 MPa, the powder feeding rate is 100 g / min, the powder feeding gas flow rate is 10.0 L / min, the powder feeding gas pressure is 0.9 MPa, the scanning speed is 180 m / min, the spraying distance is 200 mm, the spraying angle is 80°. During the spraying process, control the surface temperature of the substrate to be 140 °C, and use compressed air for cooling during the spraying process. The cooling pressure is 0.55 MPa to obtain the sprayed coating;

[0119] (Ⅲ) Heat-treat the sprayed coating in a vacuum environment with a vacuum degree of 8×10 -3 Pa at a heat treatment temperature of 1000 °C for 12 h, and then cool it naturally to obtain the high-temperature and corrosion-resistant coating.

[0120] Example 2

[0121] This embodiment provides a high-temperature and corrosion-resistant coating powder, and the high-temperature and corrosion-resistant coating powder includes inorganic powder;

[0122] The composition of the inorganic powder by mass percentage includes: cristobalite 60%, Cr powder 12%, Si powder 1%, Mo powder 17%, Ni 80 Cr 20 10%;

[0123] The particle size distribution D90 of the cristobalite is 45 μm, the particle size distribution D90 of the Cr powder is 10 μm, the particle size distribution D90 of the Si powder is 1 μm, the particle size distribution D90 of the Mo powder is 1 μm, and the Ni 80 Cr 20 has a particle size distribution D90 of 5 μm, and all the above particle size distributions are values under the D90 standard.

[0124] The preparation method of the high-temperature and corrosion-resistant coating powder includes the following steps:

[0125] (1) Mix the raw materials according to the composition of the inorganic powder and carry out ball milling. The ball milling speed is 600 rpm, the ball-to-material ratio is 2:8, the ball milling medium is silica balls, and the ball milling time is 8 h to obtain a premixed raw material;

[0126] (2) Carry out two-stage high-speed mechanical coating and powder making on the premixed raw material obtained in step (1) and the binder polyvinylpyrrolidone in an extrusion reactor to obtain coated powder. Among them, the dosage of the binder is 1% of the mass of the premixed raw material;

[0127] The process conditions for the first-stage mechanical coating and powder making include: the distance between the extrusion head and the reactor wall is 0.5 cm, the rotor speed is 500 r / min, and the coating time is 25 min;

[0128] The process conditions for the second-stage mechanical coating and powder making include: the distance between the extrusion head and the reactor wall is 0.5 cm, the rotor speed is 1500 r / min, and the coating time is 10 min;

[0129] (3) Dry the obtained coated powder at 100 °C for 6 h, and then carry out screening by the vibration screening method to obtain the high-temperature and corrosion-resistant coating powder. The loose bulk density of the powder measured by a Hall flowmeter is 3.1 g / cm 3 , and the particle size distribution range of the powder is 60 - 125 μm.

[0130] This embodiment also provides a high-temperature and corrosion-resistant coating made of the above high-temperature and corrosion-resistant coating powder.

[0131] The preparation method of the high-temperature and corrosion-resistant coating includes the following steps:

[0132] (Ⅰ) Using the waste incinerator tube as the substrate, clean the inner wall of the incinerator tube with alcohol and dry it at 60 °C. After drying, roughen and activate the surface to be sprayed by sandblasting. The sandblasting pressure is 0.2 MPa, the sandblasting distance is 30 mm, and the abrasive material is 24# corundum sand to make the surface roughness reach Sa2.5;

[0133] (Ⅱ) Conduct atmospheric plasma spraying on the substrate using the high-temperature and corrosion-resistant coating powder;

[0134] The process parameters of the atmospheric plasma spraying include: the main gas is argon, the auxiliary gas is hydrogen, the current is 500 A, the voltage is 100 V, the main gas flow rate is 40 L / min, the main gas pressure is 0.9 MPa, the auxiliary gas flow rate is 1 L / min, the auxiliary gas pressure is 0.9 MPa, the powder feeding rate is 20 g / min, the powder feeding gas flow rate is 18.0 L / min, the powder feeding gas pressure is 0.8 MPa, the scanning speed is 160 m / min, the spraying distance is 300 mm, the spraying angle is 70°. During the spraying process, control the surface temperature of the substrate at 120 °C, and use compressed air for cooling during the spraying process. The cooling pressure is 0.5 MPa to obtain the sprayed coating;

[0135] (Ⅲ) Heat-treat the sprayed coating in a vacuum environment with a vacuum degree of 1×10 -2 Pa at a heat-treatment temperature of 900 °C for a holding time of 18 h, and then cool it naturally to obtain the high-temperature and corrosion-resistant coating.

[0136] Example 3

[0137] This example provides a high-temperature and corrosion-resistant coating powder, and the high-temperature and corrosion-resistant coating powder includes inorganic powder;

[0138] The composition of the inorganic powder is calculated by mass percentage and includes: cristobalite 36%, Cr powder 17%, Si powder 4%, Mo powder 23%, Ni 80 Cr 20 20%;

[0139] The particle size distribution D90 of the cristobalite is 90 μm, the particle size distribution D90 of the Cr powder is 20 μm, the particle size distribution D90 of the Si powder is 5 μm, the particle size distribution D90 of the Mo powder is 5 μm, and the particle size distribution D90 of the Ni 80 Cr 20 is 25 μm.

[0140] The preparation method of the high-temperature and corrosion-resistant coating powder includes the following steps:

[0141] (1) Mix the raw materials according to the composition of the inorganic powder and carry out ball milling. The ball milling speed is 600 rpm, the ball-to-material ratio is 2:4, the ball milling medium is silica balls, and the ball milling time is 12 h to obtain the pre-mixed raw materials;

[0142] (2) Carry out two-stage high-speed mechanical coating and powder making on the pre-mixed raw materials obtained in step (1) and the binder polyvinylpyrrolidone in an extrusion reactor to obtain the coated powder. Among them, the dosage of the binder is 10% of the mass of the pre-mixed raw materials;

[0143] The process conditions for the first-stage mechanical coating and powder making include: the distance between the extrusion head and the reactor wall is 3 cm, the rotor speed is 1200 r / min, and the coating time is 10 min;

[0144] The process conditions for the second-stage mechanical coating and powder making include: the distance between the extrusion head and the reactor wall is 3 cm, the rotor speed is 2000 r / min, and the coating time is 5 min;

[0145] (3) Dry the obtained coated powder at 120 °C for 2 h, and then screen it by the vibration screening method to obtain the high-temperature and corrosion-resistant coating powder. The loose bulk density of the powder is measured by a Hall flowmeter to be 3.6 g / cm 3 , and the particle size distribution range of the powder is 60 - 125 μm.

[0146] This example also provides a high-temperature and corrosion-resistant coating made of the above high-temperature and corrosion-resistant coating powder.

[0147] The preparation method of the high-temperature and corrosion-resistant coating includes the following steps:

[0148] (Ⅰ) Take the waste incinerator tube as the substrate, clean the inner wall of the incinerator tube with alcohol and dry it at 90 °C. After drying, carry out roughening and activation treatment on the surface to be sprayed by sandblasting. The sandblasting pressure is 0.6 MPa, the sandblasting distance is 150 mm, and the sand particle material is 24# corundum sand to make the surface roughness reach Sa2.5;

[0149] (Ⅱ) Carry out atmospheric plasma spraying on the substrate with the high-temperature and corrosion-resistant coating powder;

[0150] The process parameters of the atmospheric plasma spraying include: the main gas is argon, the auxiliary gas is hydrogen, the current is 800 A, the voltage is 60 V, the main gas flow rate is 120 L / min, the main gas pressure is 0.3 MPa, the auxiliary gas flow rate is 25 L / min, the auxiliary gas pressure is 0.5 MPa, the powder feeding rate is 150 g / min, the powder feeding gas flow rate is 20.0 L / min, the powder feeding gas pressure is 1.0 MPa, the scanning speed is 200 m / min, the spraying distance is 150 mm, the spraying angle is 90°. During the spraying process, the surface temperature of the substrate is controlled at 150 °C, and compressed air is used for cooling during the spraying process, and the cooling pressure is 0.6 MPa to obtain a sprayed coating;

[0151] (III) Heat-treat the sprayed coating in a vacuum environment with a vacuum degree of 5×10 -3 Pa at a heat-treatment temperature of 1100 °C for a holding time of 6 h, and then cool it naturally to obtain a high-temperature corrosion-resistant coating.

[0152] Example 4

[0153] This example provides a high-temperature corrosion-resistant coating powder, and the high-temperature corrosion-resistant coating powder includes inorganic powder;

[0154] The composition of the inorganic powder by mass percentage includes: cristobalite 50%, Cr powder 14%, Si powder 2%, Mo powder 20%, Ni 80 Cr 20 14% (the same as in Example 1);

[0155] The cristobalite, Cr powder, Si powder, Mo powder and Ni 80 Cr 20 have a particle size distribution D90 of 40 μm.

[0156] The preparation method of the high-temperature corrosion-resistant coating powder is the same as that in Example 1.

[0157] This example also provides a high-temperature corrosion-resistant coating made of the above high-temperature corrosion-resistant coating powder.

[0158] The preparation method of the high-temperature corrosion-resistant coating is the same as that in Example 1.

[0159] Example 5

[0160] This example provides a high-temperature corrosion-resistant coating powder, and the composition and particle size distribution of the high-temperature corrosion-resistant coating powder are the same as those in Example 1.

[0161] The preparation method of the high-temperature and corrosion-resistant coating powder is the same as that in Example 1, except that in step (2), one-stage high-speed mechanical coating powder making is carried out, the distance between the extrusion head and the kettle wall is 2 cm, the rotor speed is 1800 r / min, and the coating time is 8 min. The rest are the same as those in Example 1.

[0162] This example also provides a high-temperature and corrosion-resistant coating made of the above high-temperature and corrosion-resistant coating powder.

[0163] The preparation method of the high-temperature and corrosion-resistant coating is the same as that in Example 1.

[0164] Example 6

[0165] This example provides a high-temperature and corrosion-resistant coating powder, and the composition and particle size distribution of the high-temperature and corrosion-resistant coating powder are the same as those in Example 1.

[0166] The preparation method of the high-temperature and corrosion-resistant coating powder is the same as that in Example 1, except that in step (2), the rotor speed of the first-stage mechanical coating powder making is 1800 r / min, and the rotor speed of the second-stage mechanical coating powder making is 800 r / min. The rest are the same as those in Example 1.

[0167] This example also provides a high-temperature and corrosion-resistant coating made of the above high-temperature and corrosion-resistant coating powder.

[0168] The preparation method of the high-temperature and corrosion-resistant coating is the same as that in Example 1.

[0169] Example 7

[0170] This example provides a high-temperature and corrosion-resistant coating powder, and the composition and particle size distribution of the high-temperature and corrosion-resistant coating powder are the same as those in Example 1.

[0171] The preparation method of the high-temperature and corrosion-resistant coating powder is the same as that in Example 1, except that in step (2), the rotor speed of the second-stage mechanical coating powder making is 2500 r / min. The rest are the same as those in Example 1.

[0172] This example also provides a high-temperature and corrosion-resistant coating made of the above high-temperature and corrosion-resistant coating powder.

[0173] The preparation method of the high-temperature and corrosion-resistant coating is the same as that in Example 1.

[0174] Example 8

[0175] This example provides a high-temperature and corrosion-resistant coating made of the high-temperature and corrosion-resistant coating powder provided in Example 1.

[0176] The preparation method of the high-temperature and corrosion-resistant coating is the same as that of Example 1, except that in step (III), the heat treatment temperature is 800 °C, and the rest are the same as those of Example 1.

[0177] Example 9

[0178] This example provides a high-temperature and corrosion-resistant coating, which is made of the high-temperature and corrosion-resistant coating powder prepared in Example 1.

[0179] The preparation method of the high-temperature and corrosion-resistant coating is the same as that of Example 1, except that in step (III), the heat treatment temperature is 1200 °C, and the rest are the same as those of Example 1.

[0180] Comparative Example 1

[0181] This comparative example provides a coating powder, which includes inorganic powder. The composition of the inorganic powder by mass percentage includes: cristobalite 50%, Cr powder 8%, Si powder 2%, Mo powder 25%, Ni 80 Cr 20 15%; the particle size distribution of the inorganic powder is the same as that of Example 1.

[0182] The preparation method of the coating powder is the same as that of Example 1.

[0183] This comparative example also provides a coating, which is made of the above coating powder.

[0184] The preparation method of the coating is the same as that of Example 1.

[0185] Comparative Example 2

[0186] This comparative example provides a coating powder, which includes inorganic powder. The composition of the inorganic powder by mass percentage includes: cristobalite 50%, Cr powder 21%, Si powder 2%, Mo powder 12%, Ni 80 Cr 20 15%; the particle size distribution of the inorganic powder is the same as that of Example 1.

[0187] The preparation method of the coating powder is the same as that of Example 1.

[0188] This comparative example also provides a coating, which is made of the above coating powder.

[0189] The preparation method of the coating is the same as that of Example 1.

[0190] Comparative Example 3

[0191] This comparative example provides a coating powder, which includes inorganic powder. The composition of the inorganic powder by mass percentage includes: cristobalite 50%, Cr powder 15%, Mo powder 20%, Ni 80 Cr 20 15%; the particle size distribution of the inorganic powder is the same as that in Example 1.

[0192] The preparation method of the coating powder is the same as that in Example 1.

[0193] This comparative example also provides a coating made from the above coating powder.

[0194] The preparation method of the coating is the same as that in Example 1.

[0195] Comparative Example 4

[0196] This comparative example provides a coating powder. Compared with Example 1, Ni 80 Cr 20 are replaced by Ni powder and Cr powder in equal amounts, and the rest are the same as those in Example 1.

[0197] The preparation method of the coating powder is the same as that in Example 1.

[0198] This comparative example also provides a coating made from the above coating powder.

[0199] The preparation method of the coating is the same as that in Example 1.

[0200] Comparative Example 5

[0201] This comparative example provides a high-temperature corrosion-resistant coating powder, and the composition and particle size distribution of the coating powder are the same as those in Example 1.

[0202] For the preparation method of the high-temperature corrosion-resistant coating powder, compared with Example 1, in step (2), mechanical coating powder preparation is replaced by ball milling and mixing with an equal amount of binder, and the ball milling time is 30 min, and the rest are the same as those in Example 1.

[0203] This comparative example also provides a high-temperature corrosion-resistant coating made from the above high-temperature corrosion-resistant coating powder.

[0204] The preparation method of the high-temperature corrosion-resistant coating is the same as that in Example 1.

[0205] Comparative Example 6

[0206] This comparative example provides a high-temperature corrosion-resistant coating made from the high-temperature corrosion-resistant coating powder prepared in Example 1.

[0207] The preparation method of the high-temperature and corrosion-resistant coating is the same as that of Example 1 except that step (Ⅲ) heat treatment is not carried out.

[0208] Performance Characterization

[0209] Figure 1 Figure showing the morphology of the high-temperature and corrosion-resistant coating powder prepared in Example 1. It can be seen that after the powder preparation process, the Ni, Cr, and Mo metal components are evenly coated on the outer surface with SiO 2 as the core, showing a metallic luster. There are a small amount of fine silicon powder (black) adhering to the outer surface of the large particles, forming powder with a particle size of 45 - 125 μm. This powder structure enables the powder to first melt the metal layer on the surface as an adhesive during the spraying and melting process, and then melt the internal core SiO 2 quartz until it impacts the workpiece surface to form a coating, which is beneficial for the riveting of the powder core SiO 2 core skeleton, realizing good cohesion and adhesion of the coating.

[0210] Figure 2 SEM image of the high-temperature and corrosion-resistant coating prepared in Example 1. It can be seen that the coating structure is composed of flattened powder particles stacked interactively. The coating structure is dense and the components are evenly distributed, forming a flattened mechanical mixture. Among them, the Ni, Cr, and Mo metal components mainly act as adhesives to carry out riveting on the flattened SiO 2 There are metal oxides such as Cr 2 O 3 generated during the atmospheric plasma spraying process and oxides of Si in the coating, further enhancing the density and continuity of the oxide film.

[0211] Figure 3 and Figure 4 Comparison of the SEM morphologies of the high-temperature and corrosion-resistant coating prepared in Example 1 before and after the heat treatment in step (Ⅲ). It can be seen that the metal phase of the coating gradually diffuses from the original distinct and flattened interface structure to form an amorphous structure with a blurred interface. The diffusion and dispersion distribution of metal elements are beneficial for the coating to be oxidized to form a more uniform and dense oxide film during subsequent service, enhancing the high-temperature oxidation resistance and acid corrosion resistance of the coating. Before heat treatment, the coating and the substrate are mainly mechanically combined in a sawtooth-like biting manner with a relatively low bonding strength. It can be observed that after heat treatment, a continuous bonding interface of metallurgical reaction occurs between the coating and the substrate, forming a metallurgical bonding strength of more than 150 MPa.

[0212] Figure 5The SEM morphology diagram after high-temperature oxidation corrosion of the high-temperature and corrosion-resistant coating prepared in Example 1 at 980 °C for 460 h is shown. It can be seen that the gray part at the bottom of the figure is the stainless-steel substrate that has been fully protected in the long-term high-temperature oxidation environment and no obvious oxidation has occurred.

[0213] The performance parameters of the high-temperature and corrosion-resistant coatings prepared in the examples and comparative examples were measured, and the obtained results are listed in Table 1.

[0214] The coating porosity was measured by metallographic analysis.

[0215] The coating hardness was measured by the micro-Vickers hardness method; test conditions: HV0.3, that is, a test load of 300 g was used, and the test standard was GB / T 6462.

[0216] The method for the coating grinding test is as follows: Alumina ring blocks with a diameter of 45 mm were respectively rubbed against the coating and the stainless-steel substrate of the waste incinerator tube under a load of 30 kg and a rotation speed of 180 r / min for 6000 times. Among them, the loss of the alumina grinding block was 7 - 8 mg / cm 3 , and the wear of the stainless-steel substrate was 35 - 40 mg / cm 3 .

[0217] The bonding strength between the coating and the substrate was measured by the tensile method using a tensile testing machine, and the test standard was GB / T 8642 - 2002.

[0218] Coating corrosion resistance test: The substrates with coatings were respectively placed under different medium conditions for corrosion resistance tests. The medium conditions were as follows: ① 10% H 2 SO 4 , 50 °C, soaked for 20 h; ② 30% H 2 SO 4 , 50 °C, soaked for 20 h; ③ 96% H 2 SO 4 , 50 °C, soaked for 20 h; ④ 5% HCl, 25 °C, soaked for 1 h; ⑤ 10% HCl, 25 °C, soaked for 1 h; ⑥ 37.5% NaCl, 50 °C, sprayed for 3000 h; The following medium conditions are represented by serial numbers. Among them, the stainless-steel substrates all suffered severe corrosion under different conditions, and the weight losses were respectively: ① 5 g / 100 g; ② 20 g / 100 g; ③ 10 g / 100 g; ④ 5 g / 100 g; ⑤ 15 g / 100 g; ⑥ 0.5 g / 100 g.

[0219] Table 1

[0220]

[0221] Table 2

[0222]

[0223]

[0224] "None" in the table indicates that no corrosion occurred, and the numbers in the table represent the weight loss due to corrosion, with the unit of g / 100g.

[0225] It can be seen from Table 1 and Table 2 that Example 1 is the optimal solution, and changes in the parameters of the other solutions will affect the performance of the coating.

[0226] In Comparative Example 1 and Comparative Example 2, the Mo material can still maintain the characteristics of high strength and high hardness at high temperatures. If the content of Mo powder is too high, it will cause a lower melting state of the powder particles during the coating deposition process, resulting in a reduced degree of flattening when impacting the material surface. The insufficient content of Cr powder leads to a decrease in the Cr content as a binder component in the coating. Both of these will increase the porosity and looseness of the coating and reduce the mechanical properties of the coating such as cohesion. In Comparative Example 3, the absence of Si powder reduces the high-temperature resistance and erosion resistance of the coating. In Comparative Example 4, the use of Ni powder and Cr powder reduces the corrosion resistance, high-temperature resistance, wear resistance, etc. of the coating.

[0227] The present invention prepares powders with a specific structure by setting a reasonable powder particle size distribution and a process scheme and parameters for mechanical coating powder making, so that a specific SiO 2 and metal layer structure are formed during the coating preparation, improving the hardness, wear resistance and other properties of the coating. During the coating preparation, the bonding strength between the coating and the substrate is significantly improved through the heat treatment step.

[0228] In summary, the high-temperature corrosion-resistant coating provided by the present invention has a uniform and dense structure. The open pores of the coating are less than 1.5%, the closed pores are less than 2.5%, and the porosity is less than 1.5%. The coating density is about 6 - 8 g / cm 3 , the thickness of the coating that can be prepared is 0.10 - 2.0 mm, the fiber Vickers hardness HV0.3 is as high as 500 - 850, it has good wear resistance, the service temperature is as high as 800 °C, it is stable under various corrosion medium conditions, and the bonding force with the substrate is as high as 100 - 200 MPa.

[0229] The applicant declares that the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A high temperature and corrosion resistant coating powder, characterized in that: The high temperature and corrosion resistant coating powder comprises inorganic powder; The composition of the inorganic powder is calculated by mass percentage, including: silica powder 36-60%, Cr powder 12-17%, Si powder 1-4%, Mo powder 17-23%, Ni 80 Cr 20 Powder 10-20%; The particle size distribution D90 of the silica powder is 45-90 μm; The particle size distribution D90 of the Cr powder is 5-20 μm; The particle size distribution D90 of the Si powder is 1-5 μm; The particle size distribution D90 of the Mo powder is 1-5 μm; The Ni 80 Cr 20 The particle size distribution D90 of the powder is 5-25 μm.

2. A method for preparing high temperature and corrosion resistant coating powder according to claim 1, characterized in that: The preparation method comprises the following steps: (1) mixing the component powders according to the composition of the inorganic powder and performing ball milling to obtain a premixed raw material; (2) The premixed raw material obtained in step (1) is subjected to mechanical coating and powdering to obtain the high temperature and corrosion resistant coating powder.

3. The preparation method according to claim 2, characterized in that: The mechanical coating powder making is a two-stage mechanical coating powder making, including a first mechanical coating powder making and a second mechanical coating powder making carried out sequentially; The distance between the extrusion head and the kettle wall of the first mechanical coating powder making is 0.5-3 cm, the rotor speed is 500-1200 r / min, and the coating time is 10-25 min; The distance between the extrusion head and the kettle wall of the second mechanical coating powder making is 0.5-3 cm, the rotor speed is 1500-2000 r / min, and the coating time is 5-10 min; A binder is also added during the mechanical coating powder making process; The amount of the binder used is 1-10% of the mass of the premixed raw materials.

4. A high temperature and corrosion resistant coating, characterized in that: The high temperature and corrosion resistant coating is made of the high temperature and corrosion resistant coating powder according to claim 1.

5. A method for preparing a high temperature and corrosion resistant coating as claimed in claim 4, characterized in that: The preparation method comprises the following steps: After pre-treating the substrate, the high temperature and corrosion resistant coating powder is used for atmospheric plasma spraying, and then heat-treated to obtain the high temperature and corrosion resistant coating.

6. The preparation method according to claim 5, characterized in that: The main gas of the atmospheric plasma spraying is argon, and the auxiliary gas is hydrogen; The current of the atmospheric plasma spraying is 500-800A; The main gas flow rate of the atmospheric plasma spraying is 40-120L / min; The auxiliary gas flow rate of the atmospheric plasma spraying is 1-25L / min; The powder feeding rate of the atmospheric plasma spraying is 20-150g / min; The powder feeding gas flow rate of the atmospheric plasma spraying is 2.0-18.0 L / min; During the atmospheric plasma spraying process, the surface temperature of the substrate is controlled to be 25-150°C.

7. The preparation method according to claim 5, characterized in that: The temperature of the heat treatment is 900-1100°C; The heat treatment holding time is 6-18h; The heat treatment is carried out in a vacuum environment with a vacuum degree of 1×10 -2 -5×10 -3 Pa.

8. The preparation method according to claim 5, characterized in that: The preparation method comprises the following steps: (a) mixing component powders according to the composition of the inorganic powder and performing ball milling; The composition of the inorganic powder is calculated by mass percentage, including: silica powder 36-60%, Cr powder 12-17%, Si powder 1-4%, Mo powder 17-23%, Ni 80 Cr 20 Powder 10-20%; wherein the particle size distribution D90 of the silica powder is 45-90μm, the particle size distribution D90 of the Cr powder is 5-20μm, the particle size distribution D90 of the Si powder is 1-5μm, the particle size distribution D90 of the Mo powder is 1-5μm, and the Ni 80 Cr 20 The particle size distribution D90 of the powder is 5-25 μm; The ball milling time is 8-12 hours, the ball milling speed is 200-600 RPM, the ball-to-material ratio of the ball milling is 2:(4-10), the ball milling medium includes silicon dioxide, and the premixed raw material is obtained after ball milling; (b) subjecting the premixed raw material obtained in step (a) and a binder to two-stage mechanical coating and powdering, wherein the amount of the binder is 1-10% of the mass of the premixed raw material, the distance between the extrusion head and the kettle wall in the first stage of mechanical coating and powdering is 0.5-3 cm, the rotor speed is 500-1200 r / min, and the coating time is 10-25 min, and the distance between the extrusion head and the kettle wall in the second stage of mechanical coating and powdering is 0.5-3 cm, the rotor speed is 1500-2000 r / min, and the coating time is 5-10 min, to obtain coated powder; (c) drying and sieving the obtained coated powder at a drying temperature of 100-120° C. for a drying time of 2-6 hours to obtain a high temperature and corrosion resistant coating powder having a particle size range of 60-125 μm and a bulk density of 3.1-3.6 g / cm 3 ; (d) the substrate is sequentially cleaned, dried and sandblasted, wherein the cleaning agent comprises alcohol and / or acetone, the drying temperature is 60-90° C., the sandblasting pressure is 0.2-0.6 MPa, the sandblasting distance is 30-150 mm, the sand material for sandblasting comprises 24# corundum sand, and the surface roughness of the substrate after sandblasting is Sa≥2.5; (e) using the high temperature and corrosion resistant coating powder to perform atmospheric plasma spraying; The process parameters of the atmospheric plasma spraying include: the main gas is argon, the auxiliary gas is hydrogen, the current is 500-800A, the voltage is 60-100V, the main gas flow rate is 40-120L / min, the main gas pressure is 0.3-0.9MPa, the auxiliary gas flow rate is 1-25L / min, the auxiliary gas pressure is 0.5-0.9MPa, the powder feeding amount is 20-150g / min, the powder feeding gas flow rate is 2.0-18.0L / min, the powder feeding gas pressure is 0.8-1.2MPa, the scanning speed is 160-200m / min, the spraying distance is 150-300mm, the spraying angle is 70-90°, during the atmospheric plasma spraying process, the surface temperature of the substrate is controlled to be 25-150°C, during the atmospheric plasma spraying process, compressed air cooling is used, and the cooling pressure is 0.5-0.6MPa to obtain a spray coating; (f) heat treating the spray coating obtained in step (e), wherein the temperature of the heat treatment is 900-1100°C, the holding time of the heat treatment is 6-18h, and the heat treatment is carried out in a vacuum degree of 1×10 -2 -5×10 -3 Pa in a vacuum environment to obtain the high temperature and corrosion resistant coating.

9. An application of the high temperature and corrosion resistant coating as claimed in claim 4, characterized in that: The high temperature and corrosion resistant coating is used in a garbage incinerator.

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