A method for improving the wear resistance of steel materials

Abstract

The present invention provides a method for improving the wear resistance of steel materials, which relates to the technical field of post-treatment of steel materials. The method uses a steel material as the substrate. First, the surface of the substrate is pretreated, and then the substrate is preheated at a temperature of 150 - 280 °C. Then, using hollow spheres as the spraying powder and a supersonic thermal spraying device, the hollow spheres are heated to 1800 - 2200 °C, and with nitrogen and hydrogen as the carrier gases, the hollow spheres are sprayed onto the surface of the substrate at a speed of 800 - 1000 m / s, thereby forming a wear-resistant coating with a thickness of 0.3 - 0.5 mm on the surface of the substrate, and thus improving the wear resistance of the substrate; the hollow spheres are prepared from copper smelting slag as raw materials by a plasma rapid heating method, with a wall thickness of 1 - 3 μm and a particle size of 45 - 75 μm. The present invention enables the steel material to have better wear resistance by preparing a wear-resistant coating on the surface of the steel material. The overall process of this method is simple and the economic cost is relatively low. At the same time, it creates a good application prospect for the industrial comprehensive recycling of copper smelting slag.

Description

Technical Field

[0001] The present invention relates to the technical field of post-treatment of steel materials, and specifically to a method for improving the wear resistance of steel materials. Background Art

[0002] With the rapid development of modern industrial technology, mechanical components and equipment made of steel materials are required to work under harsh conditions such as high precision, high load, and high temperature. Due to reasons such as wear and abrasion, component wear failure will occur, which poses relatively high requirements for the wear resistance of steel materials or surface protection materials. With the development of the equipment manufacturing industry towards large-scale and high-speed operation, improving the service life of steel materials has become one of the important tasks for enhancing the overall competitiveness of the national manufacturing industry.

[0003] Steel materials can be divided into two categories from the perspective of the tissue phases resisting wear: one is to utilize 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 strengthening of the second phase to resist wear, represented by high-chromium cast iron and high-vanadium high-speed steel. Taking high-chromium cast iron with a relatively low cost as an example, its market price is close to 10,000 yuan per ton. However, wear-resistant parts made of steel materials in equipment such as crushing, grinding, and excavation are often subject to impact wear by 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 an issue that people are concerned about.

[0004] Therefore, in-depth research on low-cost methods for improving the wear resistance of steel materials has become one of the hotspots in the research field of steel materials at present and in the future. Coating the surface of steel materials with a coating is an effective measure to improve wear resistance. Through a composite structure of hard and soft phases, the impact force during the wear process can be greatly alleviated, so that the material has higher wear resistance. At present, relatively few studies have been conducted on the preparation of wear-resistant coatings on the surface of steel materials.

[0005] Copper smelting slag is the smelting tail slag generated during the production of copper using copper sulfide concentrate. At present, the accumulation of copper smelting slag in China is very large. Due to different copper smelting processes, the components and contents of 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 be used as building materials. However, the comprehensive utilization rate of these applications for copper smelting slag accounts for less than 22%, and there are still large quantities of copper smelting waste slag piled up and idle, endangering environmental safety.

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

[0007] To address the deficiencies in the prior art, the present invention provides a method for improving the wear resistance of steel materials. By preparing a wear-resistant coating on the surface of the steel material, the steel material exhibits better wear resistance. The overall process of this method is simple and has a relatively low economic cost. At the same time, it converts copper smelting waste slag into a high-value product, creating a good application prospect for the industrial comprehensive recycling of copper smelting waste slag.

[0008] To achieve the above object, the specific solution adopted by the present invention is as follows:

[0009] A method for improving the wear resistance of steel materials mainly includes the following steps:

[0010] Step (1): Using the steel material as the substrate, perform pretreatment on the surface of the substrate.

[0011] Step (2): Perform preheating treatment on the substrate, and the preheating temperature is 150 - 280 °C.

[0012] Step (3): Using hollow spheres as the spraying powder, with the help of a supersonic thermal spraying device, heat the hollow spheres to 1800 - 2200 °C, and use nitrogen and hydrogen as the carrier gases to spray the hollow spheres onto the surface of the substrate at a speed of 800 - 1000 m / s, thereby forming a wear-resistant coating with a thickness of 0.3 - 0.5 mm on the surface of the substrate, and further improving the wear resistance of the substrate.

[0013] Among them, the hollow spheres are obtained by the plasma rapid heating method using copper smelting waste slag as the raw material, with a wall thickness of 1 - 3 μm and a particle size of 45 - 75 μm.

[0014] Further, in step (1), the specific method for performing pretreatment on the surface of the substrate is: first clean the surface of the substrate, then remove the surface grease with ethanol or acetone, and then perform sandblasting on the surface of the substrate with a sandblaster to obtain a substrate with a rough surface.

[0015] Further, in step (3), the chemical components and the mass percentages of each component contained in the hollow spheres are: Fe3O4 21%, Fe2O3 15%, SiO2 9%, CaO 3%, Al2O3 6%, ZnO 1 - 3%, and the balance is Fe2SiO4.

[0016] Further, the preparation method of the hollow spheres used in step (3) is: using copper smelting waste slag as the original raw material, perform ball milling on the copper smelting waste slag, then mix it evenly with alcohol to form a mixed solution, and then spray the mixed solution through the plasma rapid heating method to form hollow spheres, and obtain hollow spheres with a particle size of 45 - 75 μm through screening.

[0017] Further, 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 moving speed of the spray gun is 5 - 8 mm / s.

[0018] Beneficial effects:

[0019] (1) The wear-resistant coating prepared by using hollow spheres has a thinner stacked layer of deposited hollow sphere flakes than that of solid spheres, and the microstructure of the grains is finer. Analyzed from the principles of materials science, a thinner flake structure means that when the coating is worn, the stress concentration is alleviated. When wear occurs, the thinner flakes can disperse stress faster, reducing the generation and propagation of microcracks. The fine microstructure of the grains increases the grain boundary area, and the grain boundaries have the effect of hindering the movement of dislocations, making it difficult for dislocations to move on a large scale when the coating is stressed, thereby improving the hardness of the coating. At the same time, the grain boundaries can also absorb part of the energy and enhance the toughness of the coating. This good combination of hardness and toughness makes the coating have a stronger ability to resist wear under large loads and better wear resistance.

[0020] (2) During the preparation process of the coating by spraying, the carrier contains nitrogen and hydrogen. The addition of hydrogen can prevent divalent iron in the hollow spheres from being oxidized to trivalent iron. In a high-temperature spraying environment, oxidizing substances such as oxygen are likely to cause a change in the valence state of iron elements. There are differences in the material properties between divalent iron and trivalent iron, and the appearance of trivalent iron may change the microstructure and physical properties of the coating, affecting the wear resistance of the coating. As a reducing gas, hydrogen can create a relatively reducing environment during spraying, inhibiting the conversion of divalent iron to trivalent iron, ensuring the stability of the coating composition, and thus providing guarantee for the high wear resistance of the coating.

[0021] (3) The present invention makes hollow spheres from copper smelting waste slag for spraying to form a wear-resistant coating, which has significant economic and environmental benefits. From an economic perspective, copper smelting waste slag itself is a kind of waste with low economic cost. Converting it into a high-value raw material for wear-resistant coatings reduces the production cost of wear-resistant coatings. From an environmental protection perspective, the accumulation of copper smelting slag in China is huge and the comprehensive utilization rate is low. The large amount of waste slag piled up not only occupies land resources but also endangers environmental safety. The present invention has opened up a new application field for copper smelting waste slag, realized the resource utilization of waste, and reduced the environmental pressure caused by waste slag. At the same time, the wear-resistant coating prepared in this way is applied to the surface of steel materials, improving the wear resistance of steel materials, reducing the consumption of steel wear-resistant parts, and indirectly reducing the energy consumption and environmental pollution in the steel production process, with good comprehensive benefits. Description of the drawings

[0022] Figure 1 This is the micrograph of the wear-resistant coating prepared in Example 1 of the present invention.

[0023] Figure 2 This is the micrograph of the interface between the wear-resistant coating and the substrate in the product prepared in Example 1 of the present invention. Detailed implementation manners

[0024] 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 a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] The present invention provides a method for improving the wear resistance of steel materials. The specific steps are as follows:

[0026] Step (1): Using the steel material as the substrate, first clean the surface of the substrate, and then remove the surface grease with ethanol or acetone;

[0027] Step (2): Sandblast the surface of the substrate with a sandblasting machine to obtain a substrate with a rough surface; when sandblasting, the material of the sand used is alumina or silica, its particle size is 20 mesh to 60 mesh, and the air pressure is 0.3 to 1.0 MPa;

[0028] Step (3): Fix the sandblasted substrate on a fixture and preheat the surface of the substrate. The preheating temperature range is 150 to 280 °C;

[0029] Step (4): Using hollow spheres as the spraying powder, with a supersonic thermal spraying device, heat the hollow spheres to 1800 to 2200 °C, and use nitrogen and hydrogen as carriers to spray the hollow spheres onto the surface of the substrate at a speed of 800 to 1000 m / s, finally obtaining a steel material with high wear resistance, and the surface of the steel material has a wear-resistant coating with a thickness of 0.3 mm to 0.5 mm.

[0030] Specifically, in step (4), when spraying, the oxygen flow rate is 600 to 800 L / min, the nitrogen flow rate is 8 to 20 L / min, the hydrogen flow rate is 6 to 10 L / min, the kerosene flow rate is 20 to 30 L / h, the combustion chamber pressure is 0.8 to 1.2 MPa, the spraying distance is 300 to 350 mm, and the horizontal moving speed of the spray gun is 5 to 8 mm / s.

[0031] Among them, the wall thickness of the hollow spheres used in step (4) is 1-3 μm, and the particle size is 45-75 μm. The preparation method of the hollow spheres is as follows: using copper smelting slag as the raw material, ball-milling the copper smelting slag, then mixing it evenly with alcohol to form a mixed solution, and then spraying the mixed solution through the plasma rapid heating method to form hollow spheres, which are obtained by sieving. The chemical components contained in the hollow spheres and the mass percentage of each component are: Fe3O4 21%, Fe2O3 15%, SiO2 9%, CaO 3%, Al2O3 6%, ZnO 1-3%, and the balance is Fe2SiO4.

[0032] In the present invention, the hollow spheres are used as the spraying powder for supersonic thermal spraying, and the formed sheet-like stacked layer is thinner, so that the hardness of the coating reaches 57-60 HRC, and it has good wear resistance.

[0033] Example 1

[0034] This example provides a method for improving the wear resistance of steel materials. The specific steps are as follows:

[0035] Step (1): Select a Q235 steel plate of 200mm×200mm×2mm as the substrate. First, clean the surface of the substrate by milling to remove rust and debris, and then remove the surface grease with ethanol.

[0036] Step (2): Sandblast the surface of the substrate with a sandblaster. The sand is 30-mesh silica, and the pressure is 0.3 MPa. Then remove the residual sand on the surface.

[0037] Step (3): Fix the substrate on the fixture, move the spray gun, and preheat the surface of the substrate. The preheating temperature is 150°C.

[0038] Step (4): Use the hollow spheres as the spraying powder. The chemical components contained in the hollow spheres and the mass percentage of each component are: Fe3O4 21%, Fe2O3 15%, SiO2 9%, CaO 3%, Al2O3 6%, ZnO 3%, and the balance is Fe2SiO4; use a supersonic thermal spraying device to spray the hollow spheres onto the surface of the substrate. The particle size of the hollow spheres is 45 μm. The spraying process parameters are as follows: the oxygen flow rate is 600 L / min, the nitrogen flow rate is 8 L / min, the hydrogen flow rate is 6 L / min, the kerosene flow rate is 20 L / h, the combustion chamber pressure is 0.8 MPa, the spraying distance is 300 mm, and the horizontal moving speed of the spray gun is 5 mm / s; the number of spraying layers is 30 layers. After spraying every 5 layers, there is an interval of 3 minutes, and then the next layer is sprayed; finally, a steel material with high wear resistance is obtained, and the surface of the steel material has a wear-resistant coating with a thickness of 0.3 mm.

[0039] Figure 1 This is the microscopic morphology diagram of the wear-resistant coating prepared in this example.Figure 2 This is the morphology diagram at the interface between the coating and the substrate in the product prepared in this embodiment. It can be seen from Figure 1 and Figure 2 that the coating prepared by the method of the present invention is closely combined with the substrate. The coating is mainly composed of superimposed parallel lamellar structures, and some large particle structures are included in the middle. The thickness of the deposited lamellae is 2 - 10 μm, which is significantly smaller than the thickness of the lamellar structure in the coating prepared with solid spheres (usually 10 - 30 μm). The thinner lamellar structure makes the coating have better toughness and can significantly improve the wear resistance.

[0040] Example 2

[0041] This embodiment provides a method for improving the wear resistance of steel materials. The specific steps are as follows:

[0042] Step (1): Select a Q235 steel plate with dimensions 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 remove the surface grease with ethanol.

[0043] Step (2): Sandblast the surface of the substrate with a sandblaster. The sand is 60 - mesh silica, and then remove the residual sand on the surface.

[0044] Step (3): Fix the substrate on the fixture and move the spray gun to preheat the surface of the substrate. The preheating temperature is 280 °C.

[0045] Step (4): Use hollow spheres as the spraying powder. The chemical components and mass percentages of each component in the hollow spheres are as follows: Fe3O4 21%, Fe2O3 15%, SiO2 9%, CaO 3%, Al2O3 6%, ZnO 1%, and the balance is Fe2SiO4. Spray the hollow spheres onto the surface of the substrate using a supersonic thermal spraying device. 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 the horizontal moving speed of the spray gun is 8 mm / s. The number of spray layers is 30 layers. After spraying every 5 layers, wait for 3 minutes and then proceed with the next layer of spraying. Finally, obtain a steel material with high wear resistance, and the surface of the steel material has a wear-resistant coating with a thickness of 0.5 mm.

[0046] Example 3

[0047] This embodiment provides a method for improving the wear resistance of steel materials. The specific steps are as follows:

[0048] Step (1): Select a Q235 steel plate with dimensions of 200mm×200mm×2mm as the substrate. First, clean the surface of the substrate by milling to remove rust and debris, and then remove the surface grease with acetone;

[0049] Step (2): Sandblast the surface of the substrate with a sandblaster. The sand is 30-mesh silica, and then remove the remaining sand on the surface;

[0050] Step (3): Fix the substrate on the fixture, move the spray gun, and preheat the surface of the substrate. The preheating temperature is 200°C;

[0051] Step (4): Use hollow spheres as the spraying powder. The chemical components and mass percentages of each component in the hollow spheres are as follows: Fe3O4 21%, Fe2O3 15%, SiO2 9%, CaO 3%, Al2O3 6%, ZnO 2%, and the balance is Fe2SiO4. Spray the hollow spheres onto the surface of the substrate using a supersonic thermal spraying device. The particle size of the hollow spheres is 55μm. The spraying process parameters are as follows: oxygen flow rate is 680L / min, nitrogen flow rate is 12L / min, hydrogen flow rate is 7L / min, kerosene flow rate is 24L / h, combustion chamber pressure is 1.0MPa, spraying distance is 320mm, and the horizontal moving speed of the spray gun is 6mm / s. The number of spray layers is 30 layers. After spraying every 5 layers, wait for 3 minutes and then spray the next layer. Finally, obtain a steel material with high wear resistance. The surface of the steel material has a wear-resistant coating with a thickness of 0.38mm.

[0052] Example 4

[0053] This example provides a method for improving the wear resistance of steel materials. The specific steps are as follows:

[0054] Step (1): Select a Q235 steel plate with dimensions of 200mm×200mm×2mm as the substrate. First, clean the surface of the substrate by milling to remove rust and debris, and then remove the surface grease with acetone;

[0055] Step (2): Sandblast the surface of the substrate with a sandblaster. The sand is 50-mesh silica, and then remove the remaining sand on the surface;

[0056] Step (3): Fix the substrate on the fixture, move the spray gun, and preheat the surface of the substrate. The preheating temperature is 240°C;

[0057] Step (4): Use hollow spheres as the spraying powder. The chemical components and their mass percentages in the hollow spheres are as follows: Fe3O4 21%, Fe2O3 15%, SiO2 9%, CaO 3%, Al2O3 6%, ZnO 2.5%, and the balance is Fe2SiO4. Spray the hollow spheres onto the surface of the substrate using a supersonic thermal spraying device. 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 the horizontal moving speed of the spray gun is 7 mm / s. The number of spray layers is 30. After spraying every 5 layers, there is an interval of 3 minutes before spraying the next layer. Finally, a steel material with high wear resistance is obtained, and the surface of the steel material has a wear-resistant coating with a thickness of 0.43 mm.

[0058] Comparative Example 1

[0059] The difference between Comparative Example 1 and Example 4 is only that: in step (4), solid spheres are sprayed onto the surface of the substrate using a supersonic thermal spraying device.

[0060] It should be noted that the solid spheres in Comparative Example 1 are made from copper smelting slag as the raw material. First, the copper smelting slag is subjected to ball milling and pulverization treatment, and then sieved.

[0061] Comparative Example 2

[0062] The difference between Comparative Example 2 and Example 4 is that: step (4) is not included.

[0063] The steel materials obtained from Examples 1 - 4 and Comparative Examples 1 - 2 are subjected to anti-friction and wear tests, and the results are shown in Table 1 below. Among them, a friction and wear test is carried out using an MFT-5000 friction and wear testing machine. The 95 zirconia beads fixed by the upper fixture (friction radius is 6.35 mm, surface roughness Ra is 0.25 μm, load is 6 N, time is 10 min, frequency is 5 Hz, length is 10 mm) move back and forth perpendicular to the surface of the coating.

[0064] Table 1 Anti-friction and wear test results of Examples 1 - 4 and Comparative Examples 1 - 2

[0065]

[0066] As can be seen from Table 1, no coating was prepared on the surface of the steel material in Comparative Example 2, and its overall anti-friction and wear resistance was poor. Compared with Comparative Example 2, a coating was prepared on the surface of the steel material in Comparative Example 1, and the overall anti-friction and wear resistance was improved, but it was still higher than that of the steel materials treated in Examples 1-4. This is because the hardness of the coating prepared with solid spheres in Comparative Example 1 (54.6 HRC) is less than that of the coating prepared with hollow spheres (57-60 HRC), which reduces the ability of the solid sphere coating to resist external wear loads. The friction pair can penetrate deeper into the coating, and the cross-sectional area of the wear scar is larger, so the anti-friction and wear resistance is less than that of the hollow sphere coating. Secondly, the lamellar structure of the solid sphere coating is thicker. When the microcracks generated by the wear stress propagate along the interface, the coating is prone to large-scale and large-area peeling; while the lamellar structure of the hollow sphere coating is thinner. The thinner lamellar structure can cause the wear microcracks to deflect quickly, effectively reduce crack concentration, delay the lamellar peeling of the coating, and thus improve the wear resistance.

[0067] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any equivalent transformation or modification made according to the essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for improving the wear resistance of steel materials, characterized in that, It mainly includes the following steps: Step (1): Using steel materials as the substrate, pre-treat the surface of the substrate; Step (2): Preheat the substrate, and the preheating temperature is 150~280°C; Step (3): Using hollow spheres as the spraying powder, with the help of a supersonic thermal spraying device, heat the hollow spheres to 1800~2200°C, using nitrogen and hydrogen as the carrier gases, spray the hollow spheres onto the surface of the substrate at a speed of 800~1000 m / s, thereby forming a wear-resistant coating with a thickness of 0.3~0.5 mm on the surface of the substrate, and thus improving the wear resistance of the substrate; Among them, the preparation method of the hollow spheres used in Step (3) is: using copper smelting slag as the original raw material, ball-mill the copper smelting slag, then mix it evenly with alcohol to make a mixed solution, and then spray the mixed solution through the plasma rapid heating method to form hollow spheres, and obtain hollow spheres with a wall thickness of 1~3 μm and a particle size of 45~75 μm through screening; In Step (3), the chemical components contained in the hollow spheres and the mass percentage of each component are: Fe3O4 21%, Fe2O3 15%, SiO2 9%, CaO 3%, Al2O3 6%, ZnO 1~3%, and the balance is Fe2SiO4; In Step (3), when 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 moving speed of the spray gun is 5~8 mm / s.

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 surface of the substrate is: first clean the surface of the substrate, then remove the surface grease with ethanol or acetone, and then use a sandblaster to sandblast the surface of the substrate to obtain a substrate with a rough surface.

Images