Method for improving wear resistance of steel material

Abstract

The invention provides a method for improving the wear resistance of a steel and iron material, and relates to the technical field of steel and iron material post-treatment, and the method comprises the following steps: taking the steel and iron material as a matrix, firstly carrying out pretreatment on the surface of the matrix, then carrying out preheating treatment on the matrix at the temperature of 150-280 DEG C, taking a hollow sphere as spraying powder, and carrying out ultrasonic thermal spraying equipment to prepare the wear resistance of the steel and iron material. The hollow sphere is heated to 1800-2200 DEG C, nitrogen and hydrogen serve as carrier gas, the hollow sphere is sprayed to the surface of the base body at the speed of 800-1000 m / s, namely, a wear-resistant coating with the thickness of 0.3-0.5 mm is formed on the surface of the base body, and then the wear resistance of the base body can be improved; the hollow sphere is prepared by taking copper smelting waste slag as a raw material through a plasma rapid heating method, the wall thickness of the hollow sphere is 1-3 microns, and the particle size of the hollow sphere is 45-75 microns. The wear-resistant coating is prepared on the surface of the steel and iron material, so that the steel and iron material has better wear resistance. The whole process of the method is simple and convenient, the economic cost is low, and meanwhile a good application prospect is created for industrial comprehensive recycling of the copper smelting waste residues.

Description

Technical Field

[0001] The invention relates to the technical field of post-processing of steel materials, in particular to a method for improving the wear resistance of steel materials. Background Art

[0002] With the rapid development of modern industrial technology, mechanical parts and equipment made of steel materials are required to work under harsh conditions such as high precision, high load, and high temperature. Parts will fail due to wear and corrosion, which puts higher requirements on the wear resistance of steel materials or surface protection materials. As the equipment manufacturing industry develops towards large-scale and high-speed operation, improving the service life of steel materials has become one of the important tasks to enhance the overall competitiveness of the national manufacturing industry.

[0003] Steel materials can be divided into two categories from the perspective of wear resistance: one is to use the high hardness of the matrix to resist wear, represented by austenitic manganese steel and martensitic wear-resistant steel; the other is to rely on the second phase to strengthen the wear, represented by high-chromium cast iron and high-vanadium high-speed steel. Taking the low-cost high-chromium cast iron as an example, its market price is close to 10,000 yuan / ton. However, the wear-resistant parts made of steel materials in crushing, grinding, excavation and other equipment are often affected by the impact and wear of materials, resulting in rapid failure of the wear-resistant parts. The annual consumption of wear-resistant parts is very large. How to achieve the unity of wear resistance and economic benefits is a problem that people are concerned about.

[0004] Therefore, in-depth research on low-cost methods to improve the wear resistance of steel materials has become one of the hot topics in the field of steel material research at present and in the future. Coating the surface of steel materials is an effective measure to improve wear resistance. Through the composite structure of soft and hard materials, the impact force during the wear process can be greatly alleviated, thus making the material have higher wear resistance. However, there are relatively few studies on the preparation of wear-resistant coatings on the surface of steel materials.

[0005] Copper smelting slag is the smelting tailings produced when copper is produced using copper sulfide concentrate. At present, there is a large amount of copper smelting slag accumulated in my country. Due to the different smelting processes of copper smelting, the composition and content of the substances contained in the copper slag are also different. The main application directions of copper smelting slag are: one is to purify valuable metal elements, and the other is to use it as a building material. However, the comprehensive application rate of these applications for copper smelting slag accounts for less than 22%, and there are still large amounts of copper smelting waste slag piled up and idle, endangering environmental safety.

[0006] Therefore, if a method can be provided to improve the wear resistance of steel materials by using copper smelting waste slag as raw material, the unity of wear resistance and economic benefits will be achieved. Summary of the invention

[0007] In order to solve the deficiencies in the prior art, the present invention provides a method for improving the wear resistance of steel materials. The present invention prepares a wear-resistant coating on the surface of the steel material, so that the steel material has better wear resistance. The overall process of the method is simple and the economic cost is low. At the same time, copper smelting waste slag is converted into high-value products, creating a good application prospect for the industrial comprehensive reuse of copper smelting waste slag.

[0008] In order to achieve the above object, the specific scheme adopted by the present invention is: A method for improving the wear resistance of steel materials mainly comprises the following steps: Step (1), using the steel material as the substrate, pre-treating the substrate surface; Step (2), preheating the substrate at a temperature of 150-280°C; Step (3), using the hollow sphere as spray powder, using supersonic thermal spraying equipment, heating the hollow sphere to 1800-2200° C., using nitrogen and hydrogen as carrier gases, spraying the hollow sphere onto the surface of the substrate at a speed of 800-1000 m / s, that is, forming a wear-resistant coating with a thickness of 0.3-0.5 mm on the surface of the substrate, thereby improving the wear resistance of the substrate; Among them, the hollow sphere is made by plasma rapid heating method using copper smelting waste slag as raw material, with a wall thickness of 1~3μm and a particle size of 45~75μm.

[0009] Furthermore, in step (1), the specific method for pre-treating the substrate surface is: first cleaning the surface of the substrate, then removing the surface grease with ethanol or acetone, and then sandblasting the substrate surface with a sandblasting machine to obtain a substrate with a rough surface.

[0010] Furthermore, in step (3), the chemical composition and mass percentage of the hollow spheres are: Fe3O4 21%, Fe2O3 15%, SiO 29%, CaO 3%, Al2O3 6%, ZnO 1-3%, and the balance is Fe2SiO4.

[0011] Furthermore, the preparation method of the hollow spheres used in step (3) is: using copper smelting waste slag as the original raw material, subjecting the copper smelting waste slag to ball milling treatment, and then mixing it evenly with alcohol to form a mixed liquid, and then spraying the mixed liquid through a plasma rapid heating method to form hollow spheres, and obtaining hollow spheres with a particle size of 45-75 μm by screening.

[0012] Furthermore, in step (3), during spraying, the oxygen flow rate is 600-800 L / min, the nitrogen flow rate is 8-20 L / min, the hydrogen flow rate is 6-10 L / min, the kerosene flow rate is 20-30 L / h, the combustion chamber pressure is 0.8-1.2 MPa, the spraying distance is 300-350 mm, and the horizontal movement speed of the spray gun is 5-8 mm / s.

[0013] Beneficial effects: (1) The wear-resistant coating prepared by hollow spheres has thinner stacked layers of deposited hollow spheres and finer micro-grain structures than those of solid spheres. From the perspective of material science principles, a thinner layer structure means that stress concentration is alleviated when the coating is worn. When wear occurs, thinner layers can disperse stress faster and reduce the generation and expansion of microcracks. The fine micro-grain structure increases the area of ​​grain boundaries, which have the effect of hindering dislocation movement, making it difficult for dislocations to move on a large scale when the coating is subjected to force, thereby increasing the hardness of the coating. At the same time, the grain boundaries can also absorb some energy and enhance the toughness of the coating. This good combination of hardness and toughness makes the coating more resistant to heavy load wear and has better wear resistance.

[0014] (2) During the coating spraying preparation process, the carrier contains nitrogen and hydrogen. The addition of hydrogen can prevent the divalent iron in the hollow sphere from being oxidized to trivalent iron. In a high-temperature spraying environment, oxidizing substances such as oxygen can easily cause the valence state of the iron element to change. However, there are differences in material properties between divalent iron and trivalent iron. The appearance of trivalent iron may change the microstructure and physical properties of the coating and affect the wear resistance of the coating. Hydrogen, as a reducing gas, can create a relatively reducing environment during the spraying process, inhibit the conversion of divalent iron to trivalent iron, ensure the stability of the coating composition, and thus provide a guarantee for the high wear resistance of the coating.

[0015] (3) The present invention makes copper smelting waste slag into hollow spheres for spraying to form wear-resistant coatings, which has significant economic and environmental benefits. From an economic point of view, copper smelting waste slag itself is a kind of waste with low economic cost. Converting it into a high-value wear-resistant coating raw material reduces the production cost of the wear-resistant coating. From an environmental protection point of view, the amount of copper smelting slag accumulated in my country is huge, and the comprehensive application rate is low. The large amount of waste slag accumulated and idle not only occupies land resources, but also endangers environmental safety. The present invention has opened up new application areas for copper smelting waste slag, realized the resource utilization of waste, and reduced the pressure of waste slag on the environment. At the same time, the wear-resistant coating prepared in this way is applied to the surface of steel materials, which improves the wear resistance of steel materials, reduces the consumption of steel wear-resistant parts, and indirectly reduces energy consumption and environmental pollution in the steel production process, with good comprehensive benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a microscopic morphology of the wear-resistant coating prepared in Example 1 of the present invention.

[0017] Figure 2 This is a morphology diagram of the interface between the wear-resistant coating and the substrate in the product prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] The present invention provides a method for improving the wear resistance of steel materials, which comprises the following specific steps: Step (1), using the steel material as the substrate, first cleaning the substrate surface, and then removing the surface grease with ethanol or acetone; Step (2), using a sandblasting machine to sandblast the surface of the substrate to obtain a substrate with a rough surface; during the sandblasting, the sand used is made of aluminum oxide or silicon dioxide, the particle size of which is 20 mesh to 60 mesh, and the air pressure is 0.3 to 1.0 MPa; Step (3), fix the sandblasted substrate on a fixture, and preheat the substrate surface, the preheating temperature range is 150~280℃; Step (4), using the hollow sphere as spray powder, using supersonic thermal spraying equipment, heating the hollow sphere to 1800-2200° C., using nitrogen and hydrogen as carriers, spraying the hollow sphere onto the surface of the substrate at a speed of 800-1000 m / s, and finally obtaining a highly wear-resistant steel material, the surface of which has a wear-resistant coating with a thickness of 0.3 mm-0.5 mm.

[0020] Specifically, in step (4), during spraying, the oxygen flow rate is 600-800 L / min, the nitrogen flow rate is 8-20 L / min, the hydrogen flow rate is 6-10 L / min, the kerosene flow rate is 20-30 L / h, the combustion chamber pressure is 0.8-1.2 MPa, the spraying distance is 300-350 mm, and the horizontal movement speed of the spray gun is 5-8 mm / s.

[0021] The hollow sphere used in step (4) has a wall thickness of 1-3 μm and a particle size of 45-75 μm. The preparation method of the hollow sphere is as follows: copper smelting waste slag is used as the raw material, the copper smelting waste slag is subjected to ball milling treatment, and then mixed with alcohol to form a mixed liquid, and then the mixed liquid is sprayed by plasma rapid heating method to form hollow spheres, and then obtained by screening. The chemical composition and mass percentage of each component in the hollow sphere are: Fe3O4 21%, Fe2O3 15%, SiO 29%, CaO 3%, Al2O3 6%, ZnO 1-3%, and the balance is Fe2SiO4.

[0022] The present invention uses hollow spheres as spray powder for supersonic thermal spraying, and the formed flaky stacking layer is relatively thin, so that the coating hardness reaches 57-60HRC, and has good wear resistance.

[0023] Example 1 This embodiment provides a method for improving the wear resistance of steel materials, and the specific steps are: Step (1), select a Q235 steel plate of 200 mm × 200 mm × 2 mm as the substrate, first clean the surface of the substrate by milling to remove rust and debris, and then use ethanol to remove surface grease; Step (2), using a sandblasting machine to sandblast the surface of the substrate, the sand is 30 mesh silicon dioxide, the pressure is 0.3 MPa, and then the residual sand on the surface is removed; Step (3), fix the substrate on the fixture, move the spray gun, and preheat the surface of the substrate at a preheating temperature of 150°C; Step (4), using hollow spheres as spray powder, the chemical composition and mass percentage of each component in the hollow spheres are: Fe3O4 21%, Fe2O3 15%, SiO 29%, CaO 3%, Al2O3 6%, ZnO 3%, and the balance is Fe2SiO4; using supersonic thermal spraying equipment to spray the hollow spheres onto the surface of the substrate, the particle size of the hollow spheres is 45 μm, and the spraying process parameters are as follows: oxygen flow rate is 600 L / min, nitrogen flow rate is 8 L / min, hydrogen flow rate is 6 L / min, kerosene flow rate is 20 L / h, combustion chamber pressure is 0.8 MPa, spraying distance is 300 mm, and horizontal movement speed of the spray gun is 5 mm / s; the number of spray layers is 30, and the interval between each spraying of 5 layers is 3 minutes before spraying the next layer; finally, a high wear-resistant steel material is obtained, and the surface of the steel material has a wear-resistant coating with a thickness of 0.3 mm.

[0024] Figure 1 This is the microscopic morphology of the wear-resistant coating prepared in this embodiment. Figure 2 This is the morphology of the interface between the coating and the substrate in the product prepared in this example. Figure 1 and Figure 2It can be seen that the coating prepared by the method of the present invention is tightly combined with the substrate, and the coating is mainly composed of parallel lamellar structures superimposed on each other, containing some large particle structures in the middle. The thickness of the deposited lamellar layer is 2-10 μm, which is significantly smaller than the thickness of the lamellar structure in the coating prepared by solid spheres (usually 10-30 μm). The thinner lamellar structure makes the coating have better toughness and can significantly improve the wear resistance.

[0025] Example 2 This embodiment provides a method for improving the wear resistance of steel materials, and the specific steps are: Step (1), select a Q235 steel plate of 200 mm × 200 mm × 2 mm as the substrate, first clean the surface of the substrate by grinding to remove rust and debris, and then use ethanol to remove surface grease; Step (2), using a sandblasting machine to sandblast the surface of the substrate, the sand being 60 mesh silicon dioxide, and then removing the sand remaining on the surface; Step (3), fix the substrate on the fixture, move the spray gun, and preheat the surface of the substrate at a preheating temperature of 280°C; Step (4), using hollow spheres as spray powder, the chemical composition and mass percentage of each component in the hollow spheres are: Fe3O4 21%, Fe2O3 15%, SiO2 9%, CaO 3%, Al2O3 6%, ZnO 1%, and the balance is Fe2SiO4; using supersonic thermal spraying equipment to spray the hollow spheres onto the surface of the substrate, the particle size of the hollow spheres is 75 μm; the spraying process parameters are as follows: oxygen flow rate is 800 L / min, nitrogen flow rate is 20 L / min, hydrogen flow rate is 10 L / min, kerosene flow rate is 30 L / h, combustion chamber pressure is 1.2 MPa, spraying distance is 350 mm, and horizontal movement speed of the spray gun is 8 mm / s; the number of spray layers is 30, and the next layer is sprayed after 3 minutes of spraying every 5 layers; finally, a high wear-resistant steel material is obtained, and the surface of the steel material has a wear-resistant coating with a thickness of 0.5 mm.

[0026] Example 3 This embodiment provides a method for improving the wear resistance of steel materials, and the specific steps are: Step (1), select a Q235 steel plate of 200 mm × 200 mm × 2 mm as the substrate, first clean the surface of the substrate by milling to remove rust and debris, and then use acetone to remove surface grease; Step (2), using a sandblasting machine to sandblast the surface of the substrate, the sand being 30 mesh silicon dioxide, and then removing the sand remaining on the surface; Step (3), fix the substrate on the fixture, move the spray gun, and preheat the surface of the substrate at a preheating temperature of 200°C; Step (4), using hollow spheres as spray powder, the chemical composition and mass percentage of each component in the hollow spheres are: Fe3O4 21%, Fe2O3 15%, SiO 29%, CaO 3%, Al2O3 6%, ZnO 2%, and the balance is Fe2SiO4; using supersonic thermal spraying equipment to spray the hollow spheres onto the surface of the substrate, the particle size of the hollow spheres is 55 μm; the spraying process parameters are as follows: oxygen flow rate is 680 L / min, nitrogen flow rate is 12 L / min, hydrogen flow rate is 7 L / min, kerosene flow rate is 24 L / h, combustion chamber pressure is 1.0 MPa, spraying distance is 320 mm, and horizontal movement speed of the spray gun is 6 mm / s; the number of spray layers is 30, and the next layer is sprayed after 3 minutes of spraying every 5 layers; finally, a high wear-resistant steel material is obtained, and the surface of the steel material has a wear-resistant coating with a thickness of 0.38 mm.

[0027] Example 4 This embodiment provides a method for improving the wear resistance of steel materials, and the specific steps are: Step (1), select a Q235 steel plate of 200 mm × 200 mm × 2 mm as the substrate, first clean the surface of the substrate by milling to remove rust and debris, and then use acetone to remove surface grease; Step (2), using a sandblasting machine to sandblast the surface of the substrate, the sand being 50 mesh silicon dioxide, and then removing the sand remaining on the surface; Step (3), fix the substrate on the fixture, move the spray gun, and preheat the surface of the substrate at a preheating temperature of 240°C; Step (4), using hollow spheres as spray powder, the chemical composition and mass percentage of each component in the hollow spheres are: Fe3O4 21%, Fe2O3 15%, SiO 29%, CaO 3%, Al2O3 6%, ZnO 2.5%, and the balance is Fe2SiO4; using supersonic thermal spraying equipment to spray the hollow spheres onto the surface of the substrate, the particle size of the hollow spheres is 60 μm; the spraying process parameters are as follows: oxygen flow rate is 720 L / min, nitrogen flow rate is 16 L / min, hydrogen flow rate is 9 L / min, kerosene flow rate is 27 L / h, combustion chamber pressure is 1.1 MPa, spraying distance is 340 mm, and horizontal movement speed of the spray gun is 7 mm / s; the number of spray layers is 30, and the next layer is sprayed after 3 minutes of spraying every 5 layers; finally, a high wear-resistant steel material is obtained, and the surface of the steel material has a wear-resistant coating with a thickness of 0.43 mm.

[0028] Comparative Example 1 The difference between Comparative Example 1 and Example 4 is that in step (4), a supersonic thermal spraying device is used to spray the solid sphere onto the surface of the substrate.

[0029] It should be noted that the solid spheres in Comparative Example 1 are made from copper smelting waste slag as raw material, which is firstly subjected to ball milling treatment and then sieving.

[0030] Comparative Example 2 The difference between Comparative Example 2 and Example 4 is that step (4) is not included.

[0031] The steel materials obtained in Examples 1-4 and Comparative Examples 1-2 were subjected to friction and wear resistance tests, and the results are shown in Table 1. The friction and wear test was conducted using an MFT-5000 friction and wear tester, and a 95 zirconia bead (friction radius of 6.35 mm, roughness Ra of 0.25 μm, load of 6 N, time of 10 min, frequency of 5 Hz, length of 10 mm) fixed by an upper fixture made a reciprocating motion perpendicular to the coating surface.

[0032] Table 1 Anti-friction and wear test results of Examples 1-4 and Comparative Examples 1-2 As can be seen from Table 1, Comparative Example 2 did not prepare a coating on the surface of the steel material, and its overall anti-friction and wear performance was poor. Compared with Comparative Example 2, Comparative Example 1 prepared a coating on the surface of the steel material, and the overall anti-friction and wear performance was improved, but it was still higher than the steel material treated by Examples 1-4. This is because the hardness of the coating prepared by solid spheres in Comparative Example 1 (54.6HRC) is less than the hardness of the coating prepared by hollow spheres (57-60HRC), which reduces the ability of the coating of the solid sphere to resist external wear loads, the friction pair can be pressed deeper into the coating, the cross-sectional area of ​​the wear scar is larger, and the anti-friction and wear performance is lower than that of the coating of the hollow sphere. Secondly, the lamellar structure of the solid sphere coating is thicker, resulting in the microcracks generated by wear stress extending along the interface, and the coating is prone to large-scale shedding; while the lamellar structure of the hollow sphere coating is thinner, and the thinner lamellar structure can quickly deflect the wear microcracks, effectively reduce the crack concentration, and delay the shedding of the lamellar layer of the coating, thereby improving the wear resistance.

[0033] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any equivalent changes or modifications made according to the essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for improving the wear resistance of steel materials, characterized in that: The main steps are as follows: Step (1), using the steel material as the substrate, pre-treating the substrate surface; Step (2), preheating the substrate at a temperature of 150-280°C; Step (3), using the hollow sphere as spray powder, using supersonic thermal spraying equipment, heating the hollow sphere to 1800-2200° C., using nitrogen and hydrogen as carrier gases, spraying the hollow sphere onto the surface of the substrate at a speed of 800-1000 m / s, that is, forming a wear-resistant coating with a thickness of 0.3-0.5 mm on the surface of the substrate, thereby improving the wear resistance of the substrate; Among them, the hollow sphere is made by plasma rapid heating method using copper smelting waste slag as raw material, with a wall thickness of 1~3μm and a particle size of 45~75μm.

2. A method for improving the wear resistance of steel materials according to claim 1, characterized in that: In step (1), the specific method for pre-treating the substrate surface is: first, the surface of the substrate is cleaned, then the surface grease is removed with ethanol or acetone, and then the surface of the substrate is sandblasted with a sandblasting machine to obtain a substrate with a rough surface.

3. A method for improving the wear resistance of steel materials according to claim 1, characterized in that: In step (3), the chemical composition and mass percentage of the hollow sphere are: Fe3O4 21%, Fe2O3 15%, SiO2 9%, CaO 3%, Al2O3 6%, ZnO 1-3%, and the balance is Fe2SiO4.

4. A method for improving the wear resistance of steel materials according to claim 1, characterized in that: The preparation method of the hollow spheres used in step (3) is as follows: copper smelting waste slag is used as the original raw material, the copper smelting waste slag is ball-milled, and then evenly mixed with alcohol to form a mixed liquid, and then the mixed liquid is sprayed by plasma rapid heating method to form hollow spheres, and hollow spheres with a particle size of 45~75μm are obtained by screening.

5. The method for improving the wear resistance of steel materials according to claim 1, characterized in that: In step (3), during spraying, the oxygen flow rate is 600-800 L / min, the nitrogen flow rate is 8-20 L / min, the hydrogen flow rate is 6-10 L / min, the kerosene flow rate is 20-30 L / h, the combustion chamber pressure is 0.8-1.2 MPa, the spraying distance is 300-350 mm, and the horizontal movement speed of the spray gun is 5-8 mm / s.

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