A laser cladding copper-based self-lubricating material, its preparation method and application

Abstract

The present invention discloses a laser cladding copper-based self-lubricating material, its preparation method and application. By using the precursor combined with the laser cladding process, a well-structured copper-based self-lubricating cladding layer is prepared on the surface of the Q235 steel plate, enabling it to exhibit excellent anti-friction, anti-wear and anti-corrosion properties during service. It can avoid the disadvantages of traditional copper-based materials such as easy refraction, reflection and strong heat dissipation under laser, solve the defects of the cladding layer such as composition segregation, cracks, pores, inclusions, oxides, etc., and has the advantages of high energy density, dense cladding layer structure, high strength and hardness, good metallurgical bonding performance at the copper / steel interface, and easy automation, providing a feasible preparation method for the large-scale promotion of this material in the field of turnout slide plates.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of copper-based composite materials, and particularly relates to a laser cladding copper-based self-lubricating material, a preparation method thereof, and an application thereof. Background Art

[0002] As a key component of the railway track system, the slide plate has the characteristics of a large number, a short service life, a limited train speed, high safety performance requirements, and a large investment in maintenance. Its anti-friction performance directly affects railway transportation safety.

[0003] The slide plate and the switch rail form a friction pair. During service, lubricating oil is regularly applied manually to reduce friction. The friction coefficient must be less than 0.3, and the smaller the better for driving safety. With the increasing train operation speed and traffic density year by year, the annual cost for oiling and maintenance is as high as hundreds of millions of yuan, consuming a large amount of manpower and material resources. Moreover, the lubricating oil is easily emulsified and deteriorated by the erosion of rain, snow and other media outdoors, and accidents caused by poor lubrication and severe wear occur from time to time. The traditional slide plate relying on manual oiling to reduce friction can no longer meet the future railway development needs of our country. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a laser cladding copper-based self-lubricating material, a preparation method thereof, and an application thereof for the deficiencies in the above-mentioned prior art. A well-structured copper-based self-lubricating cladding layer is prepared on the surface of the Q235 steel plate by using a precursor and combining with the laser cladding method, so that it can exhibit excellent anti-friction, anti-wear, and anti-corrosion properties during service.

[0005] The present invention adopts the following technical solutions:

[0006] A preparation method of a laser cladding copper-based self-lubricating material, adding a binder to the graphite / copper composite powder; after the binder is completely dried, performing demolding treatment to obtain a precursor; processing the precursor by a laser cladding process to obtain a laser cladding copper-based self-lubricating material with a dense structure.

[0007] Specifically, in the graphite / copper composite powder, the graphite is 10Vol.% - 25Vol.%, and the copper is 75Vol.% - 90Vol.%.

[0008] Specifically, the binder is a water-soluble glue, and the mass-volume ratio of the binder to distilled water is 1:(5 - 10).

[0009] Specifically, adding the graphite / copper composite powder into a mold, then adding the binder. After the binder is completely dried, demolding the prefabricated precursor, and placing it on the Q235 steel plate for two laser cladding processes.

[0010] Further, the size of the mold is less than or equal to 30 cm * 30 cm * 1 cm.

[0011] Further, the addition amount of the binder is 0.1 - 0.2 mm higher than the height of the graphite / copper composite powder.

[0012] Specifically, the thickness of the prefabricated precursor is 0.2 - 0.6 mm, and the surface roughness is less than 50 μm.

[0013] Specifically, the laser cladding process is as follows:

[0014] The precursor is subjected to laser cladding with parameters of laser power 700 - 1200 W, scanning speed 50 - 300 mm / s, spot diameter 2 - 3 mm, and overlapping rate 30% - 70%. After the cladding is completed, the laser power is controlled at 800 - 1000 W, the scanning speed is 150 - 200 mm / s, the spot diameter is 2.2 - 2.7 mm, and the overlapping rate is 40% - 50% for secondary remelting.

[0015] Another technical solution of the present invention is a laser - clad copper - based self - lubricating material, the copper / steel interface bonding strength of the laser - clad copper - based self - lubricating material is greater than 200 MPa, the friction coefficient is 0.1 - 0.2, and the corrosion resistance is greater than or equal to the third level of the ten - level standard for metal corrosion.

[0016] Another technical solution of the present invention is that the laser - clad copper - based self - lubricating material is applied to the switch slide plate.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects:

[0018] The preparation method of the laser - clad copper - based self - lubricating material of the present invention can avoid the disadvantages of traditional copper - based materials, such as easy refraction, reflection, and strong heat dissipation under laser, solve the defects of the cladding layer, such as composition segregation, cracks, pores, inclusions, oxides, etc. It has the advantages of high energy density, dense cladding layer structure, high strength and hardness, good metallurgical bonding performance at the copper / steel interface, and easy automation.

[0019] Further, the composition ratio of the graphite / copper composite powder is: graphite 10 Vol.% - 25 Vol.%, copper 75 Vol.% - 90 Vol.%, which can ensure that the cladding layer has good self - lubricating performance and meets the required service conditions.

[0020] Further, the binder is a water - soluble glue, and the binder and distilled water are mixed in a ratio of 1:(5 - 10), which can ensure that the precursor has a certain strength and is completely vaporized during the binder cladding process, having no influence on the cladding layer structure.

[0021] Furthermore, the mixed graphite / copper composite powder is subjected to EDS energy spectrum analysis to observe whether the powder is evenly dispersed in the powder. If it is not evenly dispersed, it needs to be remixed and the EDS energy spectrum analysis is carried out again for observation, so as to accurately control the dispersion of graphite in the composite powder and ensure the homogenization of the cladding layer structure.

[0022] Furthermore, the mold size does not exceed 30 cm * 30 cm * 1 cm, which can ensure that the prefabricated precursor is clean and flat, and easy to demold.

[0023] Furthermore, the binder should be 0.1 - 0.2 mm higher than the powder, which can ensure that the prefabricated precursor is clean and flat, and easy to demold.

[0024] Furthermore, the thickness of the prefabricated precursor is 0.2 - 0.6 mm, the surface roughness is less than 50 μm, the precursor is fixed on the Q235 steel plate, and the pore between the two should be controlled not to exceed 10 μm, which can avoid the disadvantages of traditional copper-based materials such as easy refraction, reflection, and strong heat dissipation under laser, ensure good metallurgical bonding between copper and steel, and the cladding layer structure is dense.

[0025] Furthermore, after the first cladding is completed, the cladding layer is remelted for the second time, which can ensure that the cladding layer has no defects such as composition segregation, cracks, pores, inclusions, oxides, etc., and has high strength and hardness.

[0026] In summary, the present invention effectively avoids the disadvantages of traditional copper-based materials such as easy refraction, reflection, and strong heat dissipation under laser, solves the defects of the cladding layer such as composition segregation, cracks, pores, inclusions, oxides, etc., has high energy density, dense cladding layer structure, high strength and hardness, good metallurgical bonding performance at the copper / steel interface, and is easy to realize automation, etc., providing a feasible preparation method for the large-scale promotion of this material in the field of turnout slide plates.

[0027] Next, through the drawings and embodiments, the technical solutions of the present invention will be further described in detail. Brief Description of the Drawings

[0028] Figure 1 is the macroscopic morphology diagram of the precursor;

[0029] Figure 2 is the macroscopic morphology diagram of the copper-based self-lubricating cladding layer;

[0030] Figure 3 is the microscopic morphology diagram of the copper-based self-lubricating cladding layer;

[0031] Figure 4 is the interfacial morphology diagram of the copper-based self-lubricating cladding layer and Q235 steel. Detailed Description of the Embodiments

[0032] The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] In the present invention, unless otherwise specified, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0034] In the present invention, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0035] In the present invention, unless otherwise specified, percentages (%) or parts refer to percentages by weight or parts by weight relative to the composition.

[0036] In the present invention, unless otherwise specified, the components involved or their preferred components can be combined with each other to form a new technical solution.

[0037] In this disclosure, unless otherwise specified, the numerical range "a-b" is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6-22" indicates that all real numbers between "6-22" are listed herein, and "6-22" is merely an abbreviation for these numerical combinations.

[0038] The "range" disclosed in the present invention is in the form of lower limit and upper limit, which can be one or more lower limits, and one or more upper limits respectively.

[0039] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0040] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the order. Preferably, the reaction method herein is carried out sequentially.

[0041] Unless otherwise indicated, the professional and scientific terms used herein are the same as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied to the present invention.

[0042] Laser cladding is to add a cladding material on the surface of a substrate, and use a high-energy density laser beam to melt and solidify it together with a thin layer on the substrate surface, and form a metallurgical-bonded cladding layer on the surface of the substrate. As a new surface strengthening technology, laser cladding can significantly improve the wear resistance, corrosion resistance, heat resistance, and oxidation resistance of the substrate material surface, and can save a large amount of material costs while meeting the specific performance requirements of the material surface. Compared with surfacing, spraying, electroplating, and vapor deposition, the cladding layer prepared by laser cladding technology has a dense structure, controllable cladding composition and thickness, and high bonding strength between the cladding layer and the substrate, and has broad application prospects.

[0043] Therefore, using laser cladding technology to prepare a turnout slide plate material with excellent friction reduction, wear resistance, and corrosion resistance on the surface of Q235 steel is expected to solve the above problems and meet the needs of railway development.

[0044] Please refer to Figure 1 , the present invention provides a laser-clad copper-based self-lubricating material, its preparation method and application. By adopting a precursor combined with a laser cladding process, a well-structured copper-based self-lubricating cladding layer is prepared on the surface of a Q235 steel plate, so that it can exhibit excellent friction reduction, wear resistance, and corrosion resistance during service, as shown in Figure 3 and Figure 4 . It can avoid the disadvantages of traditional copper-based materials such as easy refraction, reflection, and strong heat dissipation under laser, solve the defects of the cladding layer such as composition segregation, cracks, pores, inclusions, oxides, etc., and has the advantages of high energy density, dense cladding layer structure, high strength and hardness, good metallurgical bonding performance at the copper / steel interface, and easy automation, etc., providing a feasible preparation method for the large-scale promotion of this material in the field of turnout slide plates.

[0045] A preparation method of a laser-clad copper-based self-lubricating material of the present invention includes the following steps:

[0046] S1. Place the mixed graphite / copper composite powder in a mold, and pour a binder into the mold;

[0047] The composition ratio of the graphite / copper composite powder is: graphite 10Vol.% - 25Vol.%, copper 75Vol.% - 90Vol.%. Perform EDS energy spectrum analysis on the mixed graphite / copper composite powder to observe whether the powder is evenly dispersed in the powder. If it is not evenly dispersed, it needs to be remixed and the EDS energy spectrum analysis is performed again for observation. The binder is a water-soluble glue, and the binder and distilled water are mixed in a ratio of 1:(5 - 10). The mold size does not exceed 30cm * 30cm * 1cm. The binder should be fully infiltrated into the graphite / copper composite powder and be 0.1 - 0.2mm higher than the powder.

[0048] S2. After the binder is completely dry, demold the prefabricated precursor and place it fixed on the Q235 steel plate;

[0049] The prefabricated precursor is clean and flat, with a thickness of 0.2 - 0.6 mm and a surface roughness of less than 50 μm.

[0050] The precursor is fixed on the Q235 steel plate, and the pore between the two should be controlled not to exceed 10 μm.

[0051] S3. Use the laser cladding process to process and prepare the precursor to obtain a laser - cladded copper - based self - lubricating material with a dense structure.

[0052] The laser cladding parameters are laser power 700 - 1200 W, scanning speed 50 - 300 mm / s, spot diameter 2 - 3 mm, and overlapping rate 30% - 70% for laser cladding. After the first cladding is completed, the cladding layer is remelted for the second time, and the parameters are laser power 800 - 1000 W, scanning speed 150 - 200 mm / s, spot diameter 2.2 - 2.7 mm, and overlapping rate 40% - 50%.

[0053] The laser - cladded copper - based self - lubricating material prepared through the precursor processing has a denser cladding layer structure compared with the traditional laser - cladded copper - based material. The bonding strength of the copper / steel interface is above 200 MPa. Among them, the friction coefficient is maintained at 0.1 - 0.2, and the corrosion resistance is not lower than level three of the ten - level standard for metal corrosion. There are no defects such as composition segregation, cracks, pores, inclusions, oxides, etc.

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0055] Embodiment 1

[0056] Heavy - haul railway turnout slide base

[0057] 1) Place the mixed graphite / copper composite powder in a mold and pour a binder into the mold. The composition ratio of the graphite / copper composite powder is: graphite 10 Vol.%, copper 90 Vol.%. Conduct an EDS energy spectrum analysis on the mixed graphite / copper composite powder to observe whether the powder is evenly dispersed in the powder. If it is not evenly dispersed, it is necessary to remix and conduct the EDS energy spectrum analysis again for observation. The binder is a water-soluble glue, and the binder and distilled water are mixed in a ratio of 1:5. The mold size is 30 cm * 30 cm * 1 cm. The binder should fully infiltrate into the graphite / copper composite powder and be 0.1 mm higher than the powder.

[0058] 2) After the binder is completely dry, demold the prefabricated precursor and place it fixed on a Q235 steel plate. The prefabricated precursor is clean and flat, with a thickness of 0.6 mm and a surface roughness of 10 μm. The precursor is fixed on the Q235 steel plate, and the pore between the two is 2 μm.

[0059] 3) Use the laser cladding process to process the precursor to obtain a laser-clad copper-based self-lubricating material and its preparation method and application. The laser cladding parameters are laser power 1200 W, scanning speed 300 mm / s, spot diameter 3 mm, and overlap rate 70% for laser cladding. After the first cladding is completed, perform secondary remelting on the cladding layer, with parameters of laser power 1000 W, scanning speed 200 mm / s, spot diameter 2.7 mm, and overlap rate 50%.

[0060] Example 2

[0061] Slideway table board for high-speed railway turnout

[0062] 1) Place the mixed graphite / copper composite powder in a mold and pour a binder into the mold. The composition ratio of the graphite / copper composite powder is: graphite 25 Vol.%, copper 75 Vol.%. Conduct an EDS energy spectrum analysis on the mixed graphite / copper composite powder to observe whether the powder is evenly dispersed in the powder. If it is not evenly dispersed, it is necessary to remix and conduct the EDS energy spectrum analysis again for observation. The binder is a water-soluble glue, and the binder and distilled water are mixed in a ratio of 1:10. The mold size is 20 cm * 20 cm * 0.5 cm. The binder should fully infiltrate into the graphite / copper composite powder and be 0.2 mm higher than the powder.

[0063] 2) After the binder is completely dry, demold the prefabricated precursor and place it fixed on a Q235 steel plate. The prefabricated precursor is clean and flat, with a thickness of 0.2 mm and a surface roughness of 50 μm. The precursor is fixed on the Q235 steel plate, and the pore between the two is 10 μm.

[0064] 3) The precursor is processed and prepared by laser cladding technology to obtain a laser-clad copper-based self-lubricating material with a dense structure, as well as its preparation method and application. The laser cladding parameters are laser power 700 W, scanning speed 50 mm / s, spot diameter 2 mm, and overlapping rate 30%. After the first cladding is completed, the clad layer is remelted for the second time, with parameters of laser power 800 W, scanning speed 150 mm / s, spot diameter 2.2 mm, and overlapping rate 40%.

[0065] Example 3

[0066] Coastal / River Railway Switch Slide Plate

[0067] 1) Place the mixed graphite / copper composite powder in a mold, and pour a binder into the mold; the composition ratio of the graphite / copper composite powder is: graphite 15 Vol.%, copper 85 Vol.%. Perform EDS energy spectrum analysis on the mixed graphite / copper composite powder to observe whether the powder is evenly dispersed in the powder. If it is not evenly dispersed, it needs to be remixed and EDS energy spectrum analysis is performed again for observation. The binder is a water-soluble glue, and the binder and distilled water are mixed in a ratio of 1:5. The mold size does not exceed 20 cm * 20 cm * 1 cm. The binder should be fully infiltrated into the graphite / copper composite powder and be 0.1 mm higher than the powder.

[0068] 2) After the binder is completely dry, demold the prefabricated precursor and place it fixed on a Q235 steel plate; the prefabricated precursor is clean and flat, with a thickness of 0.3 mm and a surface roughness of 30 μm. The precursor is fixed on the Q235 steel plate, and the pore between the two is 5 μm.

[0069] 3) The precursor is processed and prepared by laser cladding technology to obtain a laser-clad copper-based self-lubricating material with a dense structure, as well as its preparation method and application. The laser cladding parameters are laser power 800 W, scanning speed 100 mm / s, spot diameter 2.5 mm, and overlapping rate 50%. After the first cladding is completed, the clad layer is remelted for the second time, with parameters of laser power 900 W, scanning speed 150 mm / s, spot diameter 2.5 mm, and overlapping rate 40%.

[0070] Example 4

[0071] Intercity Railway Switch Slide Plate

[0072] 1) Place the mixed graphite / copper composite powder in a mold, and pour a binder into the mold. The composition ratio of the graphite / copper composite powder is: graphite 20 Vol.%, copper 80 Vol.%. Perform EDS energy spectrum analysis on the mixed graphite / copper composite powder to observe whether the powder is evenly dispersed in the powder. If it is not evenly dispersed, it needs to be remixed and the EDS energy spectrum analysis is performed again for observation. The binder is a water-soluble glue, and the binder and distilled water are mixed in a ratio of 1:10. The mold size does not exceed 25 cm * 25 cm * 1 cm. The binder should be fully infiltrated into the graphite / copper composite powder and be 0.15 mm higher than the powder.

[0073] 2) After the binder is completely dry, demold the prefabricated precursor and place it fixed on a Q235 steel plate; the prefabricated precursor is clean and flat, with a thickness of 0.4 mm and a surface roughness of 40 μm. The precursor is fixed on the Q235 steel plate, and the pore between them is 8 μm.

[0074] 3) Use the laser cladding process to process the precursor to obtain a laser cladded copper-based self-lubricating material, its preparation method and application. The laser cladding parameters are laser power 1000 W, scanning speed 250 mm / s, spot diameter 2.8 mm, and overlapping rate 60% for laser cladding. After the first cladding is completed, perform secondary remelting on the cladding layer, with parameters of laser power 900 W, scanning speed 180 mm / s, spot diameter 2.5 mm, and overlapping rate 50%.

[0075] In summary, for a laser cladded copper-based self-lubricating material, its preparation method and application of the present invention, the preparation process has strong controllability, is easy to realize automation, can be widely promoted and applied in the field of turnout slide plates, enabling it to exhibit excellent anti-friction, anti-wear, and anti-corrosion properties during service, and promoting the development of economic construction.

[0076] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a laser cladding copper-based self-lubricating material, characterized in that, A binder is added to the graphite / copper composite powder. In the graphite / copper composite powder, the content of graphite is 10 Vol.% - 25 Vol.%, the content of copper is 75 Vol.% - 90 Vol.%, the binder is a water-soluble glue, and the mass-volume ratio of the binder to distilled water is 1:(5 - 10); after the binder is completely dried, demolding treatment is carried out to obtain a precursor; then it is placed on a steel plate and the precursor is subjected to two laser cladding processes by laser cladding technology. After the binder is completely vaporized, a laser-clad copper-based self-lubricating material with a dense structure is obtained.

2. The preparation method of the laser cladding copper-based self-lubricating material according to claim 1, characterized in that, The size of the mold used for demolding treatment is less than or equal to 30 cm * 30 cm * 1 cm.

3. The method for preparing the laser cladding copper-based self-lubricating material according to claim 1, wherein The addition amount of the binder is 0.1 - 0.2 mm higher than the height of the graphite / copper composite powder.

4. The method for preparing a laser cladding copper-based self-lubricating material according to claim 1, characterized in that, The thickness of the prefabricated precursor is 0.2 - 0.6 mm, and the surface roughness is less than 50 μm.

5. The method for preparing a laser cladding copper-based self-lubricating material according to claim 1, characterized in that, The laser cladding process is specifically as follows: The precursor is laser-clad with parameters of laser power 700 - 1200 W, scanning speed 50 - 300 mm / s, spot diameter 2 - 3 mm, and overlapping rate 30% - 70%. After the cladding is completed, the laser power is controlled at 800 - 1000 W, the scanning speed is 150 - 200 mm / s, the spot diameter is 2.2 - 2.7 mm, and the overlapping rate is 40% - 50% for secondary remelting.

6. A laser cladding copper-based self-lubricating material, characterized in that, Prepared by the method for preparing a laser-clad copper-based self-lubricating material described in claim 1, the copper / steel interface bonding strength of the laser-clad copper-based self-lubricating material is greater than 200 MPa, the friction coefficient is 0.1 - 0.2, and the corrosion resistance is greater than or equal to the third level of the metal corrosion ten-level standard.

7. The laser-clad copper-based self-lubricating material described in claim 6 is applied to the switch slide plate.

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