Corrosion-resistant vertical grate and preparation method thereof

Abstract

The invention relates to the technical field of building materials, in particular to a corrosion-resistant vertical grate and a preparation method thereof.The corrosion-resistant vertical grate is prepared from, by weight, 100 parts of a vertical grate base material prepared from nodular cast iron, 8-12 parts of nickel-based alloy powder, 2-4 parts of graphene nanoplatelets, 6-8 parts of ceramic micro powder and 3-5 parts of a bonding accelerant; the adhesion promoter is a zirconium phosphate solution with the mass fraction of 10-15 wt%. According to the scheme, through collaborative design of materials and a process, the corrosion resistance and the structural stability of the vertical grate under severe working conditions are improved, so that the service life of the vertical grate is prolonged, and reliable performance is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, in particular to a corrosion-resistant vertical grate and a preparation method thereof. Background Art

[0002] With the continuous development of industrial equipment, vertical grates, as a key component, have been widely used in the fields of drainage, ventilation, cooling, etc. However, the existing vertical grates still have certain deficiencies in material selection and corrosion resistance. Especially when used for a long time under harsh working conditions, they are prone to rust, decreased structural strength and other problems, affecting their service life and performance stability. For example, the Chinese patent with publication number CN103526824B discloses a square three-dimensional rainwater grate. This patent effectively solves the problems of insufficient drainage and blockage through the combination of arc-shaped grates, drainage bridges, drainage holes, drainage gaps and drainage gaps, and uses vortex flow to separate debris in the water flow, significantly optimizing the drainage performance. However, this technical solution mainly focuses on the improvement of the drainage function, and has not made in-depth design on the rust and corrosion resistance of the vertical grate material. It may reduce the service life due to rust in long-term humid or acidic and alkaline environments. In addition, the solution does not mention the material modification treatment method for complex working conditions, and it is difficult to meet the application requirements of highly corrosive environments. Therefore, developing a vertical grate with ductile iron as the base material and optimized with targeted rust-proof and corrosion-resistant design and preparation process has become a technical problem that needs to be solved urgently. Summary of the Invention

[0003] The present invention proposes a corrosion-resistant vertical grate and a preparation method thereof. Through the coordinated design of materials and processes, the corrosion resistance and structural stability of the vertical grate under harsh working conditions are improved, thereby extending its service life and ensuring reliable performance.

[0004] The technical solutions of the present invention are as follows: The present invention provides a corrosion-resistant vertical grate, the raw materials of which include, by weight: 100 parts of vertical grate base material made of ductile iron, 8-12 parts of nickel-based alloy powder, 2-4 parts of graphene microsheets, 6-8 parts of ceramic micropowder, and 3-5 parts of adhesion promoter; The carbon content of the vertical grate base material made of ductile iron is 3.5wt%-3.8wt%, and the silicon content is 2.2wt%-2.6wt%; The particle size of the nickel-based alloy powder is 20-50 μm, the thickness of the graphene microsheet is 3-5 nm, the particle size of the ceramic micropowder is less than 10 μm, and the adhesion promoter is a zirconium phosphate solution with a mass fraction of 10 wt%-15 wt%.

[0005] This proposal also proposes a preparation method for the above-mentioned corrosion-resistant vertical grate. After preparing the raw materials according to the formula ratio, the preparation method includes the following steps: sandblasting the vertical grate substrate made of ductile iron, spraying a mixed slurry of nickel-based alloy powder, graphene microsheets and ceramic micropowder, sintering it once under the protection of inert gas after drying, and obtaining a pre-coated substrate after cooling; uniformly coating the surface of the pre-coated substrate with an adhesion promoter, drying it again, and sintering it a second time in a reducing atmosphere to obtain the corrosion-resistant vertical grate.

[0006] The vertical grate substrate made of ductile iron used in the present invention has a specific chemical composition range, in which the carbon content is 3.5wt%-3.8wt% and the silicon content is 2.2wt%-2.6wt%. The optimized design of this chemical composition can not only ensure the high strength and toughness of the substrate, but also provide a good foundation for its subsequent high-temperature sintering. Before use, the vertical grate substrate made of ductile iron needs to be sandblasted to remove the surface oxide layer and impurities, change the surface stress state, and improve the adhesion of subsequent coatings. The surface roughness of the substrate after sandblasting is controlled to be between Ra 1.6-3.2μm, which can ensure the bonding strength between the coating and the substrate without affecting the uniformity of the coating due to being too rough.

[0007] Next comes the preparation process of the composite coating. The composite coating consists of nickel-based alloy powder, graphene microplatelets, ceramic micropowder, and an adhesion promoter. The nickel-based alloy powder provides excellent corrosion resistance while enhancing the mechanical strength of the coating. The graphene microplatelets further enhance corrosion resistance by forming a uniformly distributed conductive network. The ceramic micropowder and nickel-based alloy powder work synergistically to fill the micropores in the coating, thereby improving the coating's density and wear resistance. Furthermore, the adhesion promoter is a zirconium phosphate solution with a mass fraction of 10-15 wt%. At high temperatures, it decomposes to form active oxides, which form a strongly bonded composite coating with the nickel-based alloy powder and graphene microplatelets. After spraying, the substrate needs to be dried to remove moisture from the slurry before entering the primary sintering stage. This primary sintering stage is carried out under inert gas protection. Its main purpose is to initially bond the various components of the coating to form a pre-coated substrate with a certain degree of density.

[0008] After the primary sintering is completed, an adhesion promoter needs to be evenly coated on the surface of the pre-coated substrate. The coating thickness of the adhesion promoter is preferably 20-30 μm to ensure that it can fully play its role in the subsequent sintering process. After the coating is completed, it is dried again before entering the secondary sintering stage. The secondary sintering is carried out in a reducing atmosphere. The key to the secondary sintering is that the active oxide generated by the decomposition of zirconium phosphate at high temperature forms a strongly bonded composite coating with the nickel-based alloy powder and graphene microsheets, thereby achieving close adhesion between the coating and the substrate.

[0009] The actual operating principle of the above-mentioned preparation method can be explained from the following aspects. First, in the sandblasting stage, the oxide layer and impurities on the surface of the substrate are removed by physical means, which not only improves the adhesion of the coating, but also creates favorable conditions for the chemical reaction in the subsequent sintering process. Secondly, in the primary sintering stage, the nickel-based alloy powder and graphene microsheets partially diffuse and combine at high temperature, initially forming a coating structure with a certain mechanical strength. Ceramic micropowder plays the role of filling micropores in this process, further improving the density of the coating. Finally, in the secondary sintering stage, the active oxide generated by the decomposition of zirconium phosphate reacts chemically with other components in the coating to form a stable intermetallic compound layer. This step significantly enhances the corrosion resistance and mechanical strength of the coating.

[0010] Preferably, the primary sintering process is: heating to 400-500°C at a rate of 5-7°C / min, keeping warm for 1-2 hours, then heating to 800-900°C at a rate of 3-4°C / min, keeping warm for 2-3 hours.

[0011] Preferably, the secondary sintering process is: heating to 800-900°C at a rate of 5-7°C / min, then heating to 1000-1100°C at a rate of 3-4°C / min, and keeping the temperature for 1-2 hours.

[0012] Preferably, the coating thickness of the adhesion promoter is 20-30 μm.

[0013] Preferably, the surface roughness of the vertical grate substrate made of ductile iron after sandblasting is Ra 1.6-3.2 μm.

[0014] Preferably, the substrate is sintered once under inert gas protection, then cooled to 200-300° C., sandblasted, and cooled to obtain a pre-coated substrate with a surface roughness of Ra 2.0-4.0 μm.

[0015] Preferably, the reducing atmosphere is a nitrogen-hydrogen mixture with a volume ratio of 17-19:1.

[0016] Preferably, after secondary sintering in a reducing atmosphere, stress annealing treatment is performed: keeping the temperature at 600-700°C for 2-4 hours, cooling to room temperature with the furnace, and obtaining a corrosion-resistant vertical grate.

[0017] The working principle and beneficial effects of the present invention are: 1. In this invention, the component design of the corrosion-resistant vertical grate utilizes a multi-material synergistic approach to enhance corrosion resistance. The vertical grate substrate, made of ductile iron, provides mechanical support, while its carbon-silicon components stabilize the matrix structure. Nickel-based alloy powder, leveraging its inherent high corrosion resistance, forms a primary protective layer, resisting acid, alkali, and salt attack. Graphene microsheets, with their layered structure, block the penetration of corrosive media, delaying localized corrosion. Ceramic micropowders fill the coating pores and enhance hardness, inhibiting media penetration. Adhesion promoters form chemical bonds at the interface, tightly connecting the components and preventing coating delamination. This creates a multi-layered protection system comprised of "substrate support - alloy primary protection - layered barrier - ceramic reinforcement - interface bonding," comprehensively enhancing corrosion resistance and structural stability.

[0018] 2. In the present invention, the preparation process optimizes coating performance through multiple coordinated steps. Sandblasting pretreatment roughens the substrate surface, increases the bonding area, and provides anchoring points for the adhesion promoter; mixed slurry spraying achieves uniform coverage of the components to avoid local defects; primary sintering completes initial solidification and interface reaction in an inert atmosphere to stabilize the coating structure; secondary sintering in a reducing atmosphere eliminates oxide interference, promotes metallurgical bonding between the alloy and the ceramic, and simultaneously forms a stable chemical bond between the adhesion promoter and the substrate; shot peening or heat treatment relieves sintering stress and reduces the risk of coating cracking, ultimately forming a composite coating system with a dense structure, strong bonding, and strong corrosion resistance, ensuring long-term service reliability. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0020] The mixed slurry used in the embodiments and comparative examples of this solution is prepared as follows: nickel-based alloy powder, graphene microplatelets, and ceramic micropowder are added to deionized water by weight, 3wt% sodium polycarboxylate is added as a dispersant, and adsorbed on the particle surface to reduce surface energy and inhibit agglomeration. Mechanical stirring is performed at 800 rpm for 30 minutes, followed by ultrasonic treatment at 40 kHz for 15 minutes using an ultrasonic disperser to uniformly suspend the components and form a slurry with good fluidity, ensuring uniform coating thickness and no particle agglomeration defects during spraying. The ceramic micropowder is composed of aluminum oxide, silicon dioxide, and silicon carbide in a mass ratio of 1:1:1; the nickel-based alloy powder is Inconel 625.

[0021] Example 1 A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of ductile iron with a carbon content of 3.6 wt% and a silicon content of 2.4 wt% were sandblasted to obtain a vertical grate substrate with a surface roughness of Ra 2.5μm, and then a mixed slurry is sprayed on the surface. After spraying, the composition of the dried coating is 10 parts of nickel-based alloy powder with a particle size of 35μm, 3 parts of graphene microsheets with a thickness of 4nm and 7 parts of ceramic micropowder with a particle size of less than 10μm. After drying, it is sintered once under nitrogen protection. The process of the first sintering is: heating to 450℃ at a rate of 6℃ / min, keeping warm for 1.5h, then heating to 850℃ at a rate of 3.5℃ / min, keeping warm for 2.5h, and cooling to obtain a pre-coated substrate; 4 parts of zirconium phosphate solution with a mass fraction of 13wt% as an adhesion promoter are uniformly coated on the surface of the pre-coated substrate, and after drying again, it is sintered twice in a nitrogen-hydrogen mixture of 18:1. The process of the secondary sintering is: heating to 850℃ at a rate of 6℃ / min, then heating to 1050℃ at a rate of 3℃ / min, keeping warm for 1.5h, and cooling to obtain a corrosion-resistant vertical grate.

[0022] Example 2 A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of ductile iron with a carbon content of 3.6wt% and a silicon content of 2.4wt% were sandblasted to obtain a surface roughness of Ra 2.5μm. The mixed slurry was then sprayed on the surface. The composition of the dried coating after spraying was 10 parts of nickel-based alloy powder with a particle size of 35μm, 3 parts of graphene microsheets with a thickness of 4nm, and 7 parts of ceramic micropowder with a particle size of less than 10μm. After drying, the coating was sintered once under nitrogen protection. The sintering process was as follows: heating to 450℃ at a rate of 6℃ / min, keeping warm for 1.5h, then heating to 850℃ at a rate of 3.5℃ / min, keeping warm for 2.5h, then cooling to 250℃, sandblasting, and cooling to obtain a surface roughness of Ra A 3.5 μm pre-coated substrate; 4 parts of a 13 wt% zirconium phosphate solution bonding promoter are uniformly coated on the surface of the pre-coated substrate, and after drying again, secondary sintering is carried out in a nitrogen-hydrogen mixture of 18:1. The secondary sintering process is as follows: heating to 850°C at a rate of 6°C / min, then heating to 1050°C at a rate of 3°C / min, keeping warm for 1.5 hours, and obtaining a corrosion-resistant vertical grate after cooling.

[0023] Example 3 A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of ductile iron with a carbon content of 3.6wt% and a silicon content of 2.4wt% were sandblasted to obtain a surface roughness of Ra 2.5μm. The mixed slurry was then sprayed on the surface. The composition of the dried coating after spraying was 10 parts of nickel-based alloy powder with a particle size of 35μm, 3 parts of graphene microsheets with a thickness of 4nm, and 7 parts of ceramic micropowder with a particle size of less than 10μm. After drying, the coating was sintered once under nitrogen protection. The sintering process was as follows: heating to 450℃ at a rate of 6℃ / min, keeping warm for 1.5h, then heating to 850℃ at a rate of 3.5℃ / min, keeping warm for 2.5h, then cooling to 250℃, sandblasting, and cooling to obtain a surface roughness of Ra A 3.5 μm pre-coated substrate; 4 parts of a 13 wt% zirconium phosphate solution bonding promoter are uniformly coated on the surface of the pre-coated substrate, and then dried again and sintered for the second time in a nitrogen-hydrogen mixture of 18:1. The secondary sintering process is as follows: heating to 850°C at a rate of 6°C / min, then heating to 1050°C at a rate of 3°C / min, keeping warm for 1.5 hours, keeping warm at 650°C for 3 hours, and cooling to room temperature with the furnace to obtain a corrosion-resistant vertical grate.

[0024] Example 4 A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of ductile iron with a carbon content of 3.8 wt% and a silicon content of 2.6 wt% were sandblasted to obtain a surface roughness of Ra 3.2μm, and then a mixed slurry is sprayed on the surface. The composition of the dried coating after spraying is 12 parts of nickel-based alloy powder with a particle size of 40μm, 4 parts of graphene microsheets with a thickness of 5nm and 8 parts of ceramic micropowder with a particle size of less than 10μm. After drying, it is sintered once under nitrogen protection. The process of the first sintering is: heating to 500℃ at a rate of 7℃ / min, keeping warm for 1h, then heating to 900℃ at a rate of 4℃ / min, keeping warm for 2h, and cooling to obtain a pre-coated substrate; 5 parts of zirconium phosphate solution with a mass fraction of 15wt% as an adhesion promoter are uniformly coated on the surface of the pre-coated substrate, and after drying again, it is sintered for the second time in a nitrogen-hydrogen mixture of 19:1. The process of the secondary sintering is: heating to 900℃ at a rate of 7℃ / min, then heating to 1100℃ at a rate of 4℃ / min, keeping warm for 1h, and cooling to obtain a corrosion-resistant vertical grate.

[0025] Example 5 A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of ductile iron with a carbon content of 3.5wt% and a silicon content of 2.2wt% were sandblasted to obtain a vertical grate substrate with a surface roughness of Ra 1.6μm, and then a mixed slurry is sprayed on the surface. The composition of the dried coating after spraying is 8 parts of nickel-based alloy powder with a particle size of 20μm, 2 parts of graphene microsheets with a thickness of 3nm and 6 parts of ceramic micropowder with a particle size of less than 10μm. After drying, it is sintered once under nitrogen protection. The process of the first sintering is: heating to 400℃ at a rate of 5℃ / min, keeping warm for 1h, then heating to 800℃ at a rate of 3℃ / min, keeping warm for 2h, and cooling to obtain a pre-coated substrate; 3 parts of zirconium phosphate solution with a mass fraction of 10wt% as an adhesion promoter are uniformly coated on the surface of the pre-coated substrate, and after drying again, it is sintered for the second time in a nitrogen-hydrogen mixture of 17:1. The process of the second sintering is: heating to 800℃ at a rate of 5℃ / min, then heating to 1000℃ at a rate of 3℃ / min, keeping warm for 2h, and cooling to obtain a corrosion-resistant vertical grate.

[0026] Comparative Example 1 The difference from Example 1 is that the vertical grate substrate is directly prepared using ductile iron with a carbon content of 3.6 wt % and a silicon content of 2.4 wt %.

[0027] Comparative Example 2 The difference from Example 1 is that the carbon content and silicon content of the vertical grate base material made of ductile iron are very high: A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of ductile iron with a carbon content of 4.0wt% and a silicon content of 2.8wt% were sandblasted to obtain a vertical grate substrate with a surface roughness of Ra 2.5μm, and then a mixed slurry is sprayed on the surface. After spraying, the composition of the dried coating is 10 parts of nickel-based alloy powder with a particle size of 35μm, 3 parts of graphene microsheets with a thickness of 4nm and 7 parts of ceramic micropowder with a particle size of less than 10μm. After drying, it is sintered once under nitrogen protection. The process of the first sintering is: heating to 450℃ at a rate of 6℃ / min, keeping warm for 1.5h, then heating to 850℃ at a rate of 3.5℃ / min, keeping warm for 2.5h, and cooling to obtain a pre-coated substrate; 4 parts of zirconium phosphate solution with a mass fraction of 13wt% as an adhesion promoter are uniformly coated on the surface of the pre-coated substrate, and after drying again, it is sintered twice in a nitrogen-hydrogen mixture of 18:1. The process of the secondary sintering is: heating to 850℃ at a rate of 6℃ / min, then heating to 1050℃ at a rate of 3℃ / min, keeping warm for 1.5h, and cooling to obtain a corrosion-resistant vertical grate.

[0028] Comparative Example 3 The difference from Example 1 is that no adhesion promoter is applied: A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of ductile iron with a carbon content of 3.6 wt% and a silicon content of 2.4 wt% were sandblasted to obtain a vertical grate substrate with a surface roughness of Ra 2.5μm, and then spray the mixed slurry on the surface. The composition of the dried coating after spraying is 10 parts of nickel-based alloy powder with a particle size of 35μm, 3 parts of graphene microsheets with a thickness of 4nm and 7 parts of ceramic micropowder with a particle size of less than 10μm. After drying, it is sintered once under nitrogen protection. The process of the primary sintering is: heating to 450℃ at a rate of 6℃ / min, keeping warm for 1.5h, then heating to 850℃ at a rate of 3.5℃ / min, keeping warm for 2.5h, and cooling to obtain a pre-coated substrate; secondary sintering is carried out in a nitrogen-hydrogen mixture of 18:1. The process of the secondary sintering is: heating to 850℃ at a rate of 6℃ / min, then heating to 1050℃ at a rate of 3℃ / min, keeping warm for 1.5h, and cooling to obtain a corrosion-resistant vertical grate.

[0029] Comparative Example 4 The difference from Example 1 is that the composition of the mixed slurry is abnormal: A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of ductile iron with a carbon content of 3.6 wt% and a silicon content of 2.4 wt% were sandblasted to obtain a vertical grate substrate with a surface roughness of Ra 2.5μm, and then a mixed slurry is sprayed on the surface. The composition of the dried coating after spraying is 15 parts of nickel-based alloy powder with a particle size of 35μm, 1 part of graphene microsheets with a thickness of 4nm and 7 parts of ceramic micropowder with a particle size of less than 10μm. After drying, it is sintered once under nitrogen protection. The process of the first sintering is: heating to 450℃ at a rate of 6℃ / min, keeping warm for 1.5h, then heating to 850℃ at a rate of 3.5℃ / min, keeping warm for 2.5h, and cooling to obtain a pre-coated substrate; 4 parts of zirconium phosphate solution with a mass fraction of 13wt% as an adhesion promoter are uniformly coated on the surface of the pre-coated substrate, and after drying again, it is sintered twice in a nitrogen-hydrogen mixture of 18:1. The process of the secondary sintering is: heating to 850℃ at a rate of 6℃ / min, then heating to 1050℃ at a rate of 3℃ / min, keeping warm for 1.5h, and cooling to obtain a corrosion-resistant vertical grate.

[0030] Comparative Example 5 The difference from Example 1 is that the parameters of the heavy component of the mixed slurry are abnormal: A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of ductile iron with a carbon content of 3.6 wt% and a silicon content of 2.4 wt% were sandblasted to obtain a vertical grate substrate with a surface roughness of Ra 2.5μm, and then the mixed slurry is sprayed on the surface. The composition of the dried coating after spraying is 10 parts of nickel-based alloy powder with a particle size of 60μm, 3 parts of graphene microsheets with a thickness of 8nm and 7 parts of ceramic micropowder with a particle size of 18μm. After drying, it is sintered once under nitrogen protection. The process of the first sintering is: heating to 450℃ at a rate of 6℃ / min, keeping warm for 1.5h, then heating to 850℃ at a rate of 3.5℃ / min, keeping warm for 2.5h, and cooling to obtain a pre-coated substrate; 4 parts of zirconium phosphate solution with a mass fraction of 13wt% as an adhesion promoter are uniformly coated on the surface of the pre-coated substrate, and after drying again, it is sintered twice in a nitrogen-hydrogen mixture of 18:1. The process of the secondary sintering is: heating to 850℃ at a rate of 6℃ / min, then heating to 1050℃ at a rate of 3℃ / min, keeping warm for 1.5h, and cooling to obtain a corrosion-resistant vertical grate.

[0031] Comparative Example 6 The difference from Example 1 is that no mixed slurry layer is sprayed: A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of a vertical grate substrate made of ductile iron with a carbon content of 3.6wt% and a silicon content of 2.4wt% were sandblasted, and the surface roughness after sandblasting was Ra 2.5μm. The substrate was heated to 450℃ at a rate of 6℃ / min under nitrogen protection, kept warm for 1.5h, then heated to 850℃ at a rate of 3.5℃ / min, kept warm for 2.5h, and coated with 4 parts of a zirconium phosphate solution with a mass fraction of 13wt% as an adhesion promoter on the surface after cooling. After drying again, the substrate was sintered in a nitrogen-hydrogen mixture of 18:1. The sintering process was as follows: heating to 850℃ at a rate of 6℃ / min, then heating to 1050℃ at a rate of 3℃ / min, kept warm for 1.5h, and cooling to obtain a corrosion-resistant vertical grate.

[0032] Comparative Example 7 The difference from Example 1 is that the primary sintering temperature is too high: A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of ductile iron with a carbon content of 3.6 wt% and a silicon content of 2.4 wt% were sandblasted to obtain a vertical grate substrate with a surface roughness of Ra 2.5μm, and then the mixed slurry is sprayed on the surface. The composition of the dried coating after spraying is 10 parts of nickel-based alloy powder with a particle size of 35μm, 3 parts of graphene microsheets with a thickness of 4nm and 7 parts of ceramic micropowder with a particle size of less than 10μm. After drying, it is sintered once under nitrogen protection. The process of the first sintering is: heating to 450℃ at a rate of 6℃ / min, keeping warm for 1.5h, then heating to 1000℃ at a rate of 3.5℃ / min, keeping warm for 2.5h, and cooling to obtain a pre-coated substrate; 4 parts of zirconium phosphate solution with a mass fraction of 13wt% as an adhesion promoter are uniformly coated on the surface of the pre-coated substrate, and after drying again, it is sintered twice in a nitrogen-hydrogen mixture of 18:1. The process of the secondary sintering is: heating to 850℃ at a rate of 6℃ / min, then heating to 1050℃ at a rate of 3℃ / min, keeping warm for 1.5h, and cooling to obtain a corrosion-resistant vertical grate.

[0033] Comparative Example 8 The difference from Example 1 is that the secondary sintering temperature is too high: A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of ductile iron with a carbon content of 3.6 wt% and a silicon content of 2.4 wt% were sandblasted to obtain a vertical grate substrate with a surface roughness of Ra 2.5μm, and then a mixed slurry is sprayed on the surface. The composition of the dried coating after spraying is 10 parts of nickel-based alloy powder with a particle size of 35μm, 3 parts of graphene microsheets with a thickness of 4nm and 7 parts of ceramic micropowder with a particle size of less than 10μm. After drying, it is sintered once under nitrogen protection. The process of the first sintering is: heating to 450℃ at a rate of 6℃ / min, keeping warm for 1.5h, then heating to 850℃ at a rate of 3.5℃ / min, keeping warm for 2.5h, and cooling to obtain a pre-coated substrate; 4 parts of zirconium phosphate solution with a mass fraction of 13wt% as an adhesion promoter are uniformly coated on the surface of the pre-coated substrate, and after drying again, it is sintered twice in a nitrogen-hydrogen mixture of 18:1. The process of the secondary sintering is: heating to 850℃ at a rate of 6℃ / min, then heating to 1150℃ at a rate of 3℃ / min, keeping warm for 1.5h, and cooling to obtain a corrosion-resistant vertical grate.

[0034] Comparative Example 9 The difference from Example 1 is that the primary sintering temperature is too low: A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of ductile iron with a carbon content of 3.6 wt% and a silicon content of 2.4 wt% were sandblasted to obtain a vertical grate substrate with a surface roughness of Ra 2.5μm, and then a mixed slurry is sprayed on the surface. The composition of the dried coating after spraying is 10 parts of nickel-based alloy powder with a particle size of 35μm, 3 parts of graphene microsheets with a thickness of 4nm and 7 parts of ceramic micropowder with a particle size of less than 10μm. After drying, it is sintered once under nitrogen protection. The process of the first sintering is: heating to 450℃ at a rate of 6℃ / min, keeping warm for 1.5h, then heating to 750℃ at a rate of 3.5℃ / min, keeping warm for 2.5h, and cooling to obtain a pre-coated substrate; 4 parts of zirconium phosphate solution with a mass fraction of 13wt% as an adhesion promoter are uniformly coated on the surface of the pre-coated substrate, and after drying again, it is sintered twice in a nitrogen-hydrogen mixture of 18:1. The process of the secondary sintering is: heating to 850℃ at a rate of 6℃ / min, then heating to 1050℃ at a rate of 3℃ / min, keeping warm for 1.5h, and cooling to obtain a corrosion-resistant vertical grate.

[0035] Comparative Example 10 The difference from Example 1 is that the secondary sintering temperature is too low: A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of ductile iron with a carbon content of 3.6 wt% and a silicon content of 2.4 wt% were sandblasted to obtain a vertical grate substrate with a surface roughness of Ra 2.5μm, and then a mixed slurry is sprayed on the surface. The composition of the dried coating after spraying is 10 parts of nickel-based alloy powder with a particle size of 35μm, 3 parts of graphene microsheets with a thickness of 4nm and 7 parts of ceramic micropowder with a particle size of less than 10μm. After drying, it is sintered once under nitrogen protection. The process of the first sintering is: heating to 450℃ at a rate of 6℃ / min, keeping warm for 1.5h, then heating to 850℃ at a rate of 3.5℃ / min, keeping warm for 2.5h, and cooling to obtain a pre-coated substrate; 4 parts of zirconium phosphate solution with a mass fraction of 13wt% as an adhesion promoter are uniformly coated on the surface of the pre-coated substrate, and after drying again, it is sintered twice in a nitrogen-hydrogen mixture of 18:1. The process of the secondary sintering is: heating to 850℃ at a rate of 6℃ / min, then heating to 950℃ at a rate of 3℃ / min, keeping warm for 1.5h, and cooling to obtain a corrosion-resistant vertical grate.

[0036] Comparative Example 11 The difference from Example 1 is that the secondary sintering is not carried out under a reducing atmosphere: A method for preparing the above-mentioned corrosion-resistant vertical grate, after preparing raw materials according to the formula ratio, the preparation method includes the following steps: 100 parts of ductile iron with a carbon content of 3.6 wt% and a silicon content of 2.4 wt% were sandblasted to obtain a vertical grate substrate with a surface roughness of Ra 2.5μm, and then the mixed slurry is sprayed on the surface. The composition of the dried coating after spraying is 10 parts of nickel-based alloy powder with a particle size of 35μm, 3 parts of graphene microsheets with a thickness of 4nm and 7 parts of ceramic micropowder with a particle size of less than 10μm. After drying, it is sintered once under nitrogen protection. The process of the first sintering is: heating to 450℃ at a rate of 6℃ / min, keeping warm for 1.5h, then heating to 850℃ at a rate of 3.5℃ / min, keeping warm for 2.5h, and cooling to obtain a pre-coated substrate; 4 parts of zirconium phosphate solution with a mass fraction of 13wt% as an adhesion promoter are uniformly coated on the surface of the pre-coated substrate, and then dried again and sintered twice in air at 18:1. The process of the secondary sintering is: heating to 850℃ at a rate of 6℃ / min, then heating to 1050℃ at a rate of 3℃ / min, keeping warm for 1.5h, and cooling to obtain a corrosion-resistant vertical grate.

[0037] Performance testing: Wear resistance: refer to GB / T 12444-2006; Corrosion resistance: Refer to GB / T 10125-2021; Mechanical properties: Refer to GB / T 228.1-2021; Coating test: Rapidly heat the sample from room temperature (25°C) to 600°C (10°C / min), keep warm for 10 minutes, and then rapidly cool to room temperature (10°C / min). Repeat the cycle five times to test the thermal shock stability. After the cycle, the coating should not crack or fall off. The number of cycles should be recorded.

[0038] The ductile iron used in Example 1, Example 4, Example 5 and Comparative Example 2 is slightly different. The remaining examples and comparative examples are the same as Example 1. The main components are shown in Table 1. In addition, the vertical grate base material prepared from the ductile iron in all examples and comparative examples, the process and heat treatment process are the same.

[0039] Table 1 Main components of the substrates of Examples and Comparative Examples

[0040] The performance test results are shown in Table 2.

[0041] Table 2 Performance test results of examples and comparative examples

[0042] Example 3 has the best comprehensive performance due to secondary sandblasting and stress annealing after pre-coating; Example 2 has the second best performance because the pre-coating sandblasting increases the bonding area but no annealing is performed; Example 1 has the third best performance without pre-coating sandblasting; all examples have a core design of substrate pretreatment + composite coating + adhesion promoter + step-by-step sintering, which is significantly better than the comparative example.

[0043] Compared with Example 1, Comparative Example 1 completely lacks the composite coating, and the ductile iron substrate is exposed, resulting in the graphite phase becoming the cathode of the corrosion galvanic cell, accelerating electrochemical corrosion; Comparative Example 2 induces the precipitation of coarse graphite and the generation of brittle phase due to the ultra-high carbon silicon component of the substrate, weakening the continuity of the matrix, and at the same time causing the coating bonding force to decrease, resulting in a decrease in wear resistance and corrosion resistance; Comparative Example 3 does not use zirconium phosphate binder, so that the interface between the coating and the substrate only has mechanical interlocking and lacks chemical bond strengthening, and the bonding strength is significantly reduced; In Comparative Example 4, the excessive nickel-based alloy breaks the balance of the slurry components, and the insufficient graphene content causes The resulting dielectric barrier network is discontinuous; the use of oversized powder in Comparative Example 5 increases the coating porosity and shortens the permeation pathways for corrosive media; Comparative Example 6 retains only the zirconium phosphate coating but lacks the alloy-ceramic composite layer, losing its primary protective function; the abnormal sintering temperatures (too high or too low) in Comparative Examples 7-10, respectively, lead to coarsening of the nickel-based alloy grains, insufficient decomposition of the zirconium phosphate, and insufficient melting of the ceramic powder, impairing the coating's density and interfacial bonding; and Comparative Example 11 undergoes secondary sintering in air, generating brittle oxides such as nickel oxide and chromium trioxide, which increases the coating's defect density and reduces wear resistance. These deficiencies collectively result in the Comparative Examples being significantly inferior to Example 1 in terms of corrosion resistance, mechanical strength, and thermal stability.

[0044] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A corrosion-resistant vertical grate, characterized in that: The raw materials include by weight: 100 parts of vertical grate base material made of ductile iron, 8-12 parts of nickel-based alloy powder, 2-4 parts of graphene microsheets, 6-8 parts of ceramic micropowder, and 3-5 parts of adhesion promoter; The bonding promoter is a zirconium phosphate solution with a mass fraction of 10wt%-15wt%.

2. The corrosion-resistant vertical grate according to claim 1, characterized in that: The carbon content of the vertical grate substrate made of ductile iron is 3.5wt%-3.8wt%, and the silicon content is 2.2wt%-2.6wt%.

3. The corrosion-resistant vertical grate according to claim 1, characterized in that: The particle size of the nickel-based alloy powder is 20-50 μm, the thickness of the graphene microsheet is 3-5 nm, and the particle size of the ceramic micropowder is less than 10 μm.

4. A method for preparing a corrosion-resistant vertical grate according to any one of claims 1 to 3, characterized in that: After preparing the raw materials according to the formula ratio, the preparation method includes the following steps: sandblasting the vertical grate substrate made of ductile iron, spraying a mixed slurry of nickel-based alloy powder, graphene microsheets and ceramic micropowder, drying and sintering once under the protection of inert gas, and cooling to obtain a pre-coated substrate; uniformly coating the surface of the pre-coated substrate with an adhesion promoter, drying again and sintering a second time in a reducing atmosphere to obtain a corrosion-resistant vertical grate.

5. The method for preparing a corrosion-resistant vertical grate according to claim 4, wherein: The primary sintering process is as follows: heating to 400-500° C. at a rate of 5-7° C. / min, keeping the temperature for 1-2 hours, then heating to 800-900° C. at a rate of 3-4° C. / min, and keeping the temperature for 2-3 hours.

6. The method for preparing a corrosion-resistant vertical grate according to claim 4, wherein: The secondary sintering process is as follows: heating to 800-900° C. at a rate of 5-7° C. / min, then heating to 1000-1100° C. at a rate of 3-4° C. / min, and keeping the temperature for 1-2 hours.

7. The method for preparing a corrosion-resistant vertical grate according to claim 4, wherein: The surface roughness of the vertical grate substrate made of ductile iron after sandblasting is Ra 1.6-3.2 μm.

8. The method for preparing a corrosion-resistant vertical grate according to claim 4, wherein: The substrate is sintered once under the protection of inert gas, then cooled to 200-300°C, sandblasted, and cooled to obtain a pre-coated substrate with a surface roughness of Ra 2.0-4.0 μm.

9. The method for preparing a corrosion-resistant vertical grate according to claim 4, wherein: The reducing atmosphere is a nitrogen-hydrogen mixture with a volume ratio of 17-19:

1.

10. The method for preparing a corrosion-resistant vertical grate according to claim 4, wherein: After secondary sintering in a reducing atmosphere, stress annealing treatment is performed: keeping the temperature at 600-700°C for 2-4 hours, cooling to room temperature with the furnace, and obtaining a corrosion-resistant vertical grate.

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