Composite materials for sliding bearings in high-speed wire rod mills and their preparation methods

Abstract

This invention relates to the field of metal matrix composites, and discloses a sliding bearing composite material for high-speed wire rod mills and its preparation method. The material comprises, from the outside to the inside, a load-bearing layer, an intermediate bonding layer, and a functional surface layer. The functional surface layer is composed of the following components by mass percentage: 60-75% copper-tin-zinc alloy powder, 15-25% a mixture of molybdenum disulfide and graphite powder, 5-15% nano-ceramic particles, and 0.5-3% rare earth additives. The method includes the following steps: a) surface pretreatment of the load-bearing layer matrix; b) laying copper-based alloy powder on the surface of the load-bearing layer and performing a first sintering to form the intermediate bonding layer; c) preparing the functional surface layer slurry; d) uniformly coating the functional surface layer slurry onto the surface of the intermediate bonding layer by flame spraying, drying, and then performing a second sintering; e) machining the sintered composite material. This invention can solve the problems of single performance and poor overall performance of existing bearing materials and composite structures.

Description

Technical Field

[0001] This invention relates to the field of metal matrix composites, and more specifically to a sliding bearing composite material for high-speed wire rod mills and its preparation method. Background Technology

[0002] High-speed wire rod mills are key equipment in the modern steel industry. During operation, they are characterized by high rolling speed, large load, and drastic temperature changes, which places extremely stringent requirements on the performance of their sliding bearings.

[0003] Traditional sliding bearing materials, such as Babbitt metal or copper-based alloys, are prone to fatigue spalling, accelerated wear, and excessive temperature rise leading to bearing seizure under high speed and high impact loads, which affect the stable operation of the rolling mill and the service life of the bearings.

[0004] While existing technologies offer various composite bearing material options, such as polymer-based composites, metal-based composites, and sandwich structures with a steel backing, copper alloy interlayer, and polymer surface layer, all have performance limitations. Polymer-based composites (such as PTFE and PEEK) have low coefficients of friction, but their load-bearing capacity and thermal conductivity are relatively limited, making them unsuitable for handling the high linear speeds and impact loads of rolling mills alone. Metal-based composites, while possessing high strength, lack sufficient self-lubricating properties, making them prone to adhesive wear during startup or inadequate lubrication. The sandwich structure with a steel backing, copper alloy interlayer, and polymer surface layer, while integrating some advantages of both metal and polymer materials, often struggles to balance high load-bearing capacity with a low coefficient of friction.

[0005] Therefore, developing a sliding bearing composite material that can simultaneously meet the requirements of high load-bearing capacity, high wear resistance, excellent self-lubrication, good heat dissipation, and fatigue resistance is of great significance for improving the operational reliability of high-speed wire rod mills and reducing maintenance costs. Summary of the Invention

[0006] The present invention aims to provide a sliding bearing composite material for high-speed wire rod mills and a method for preparing the same, in order to solve the problems of single performance and poor overall performance of existing bearing materials and composite structures.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The composite material for sliding bearings used in high-speed wire rod mills comprises, from the outside to the inside, a load-bearing layer, an intermediate bonding layer, and a functional surface layer. The functional surface layer consists of the following components by mass percentage: 60-75% copper-tin-zinc alloy powder, 15-25% mixed powder of molybdenum disulfide and graphite, 5-15% nano-ceramic particles, and 0.5-3% rare earth additives.

[0008] Preferably, as an improvement, the load-bearing layer is made of alloy steel.

[0009] Preferably, as an improvement, the intermediate bonding layer is a copper-based alloy.

[0010] Preferably, as an improvement, the mass ratio of molybdenum disulfide to graphite in the mixed powder is 1:1 to 3:1.

[0011] Preferably, as an improvement, the nano-ceramic particles are nano-Al2O3.

[0012] Preferably, as an improvement, the particle size of nano-Al2O3 is 50~200 nanometers.

[0013] The method for preparing the sliding bearing composite material for the above-mentioned high-speed wire rod mill includes the following steps: a) Perform surface pretreatment on the substrate of the bearing layer; b) Copper-based alloy powder is laid on the surface of the bearing layer and sintered for the first time to form an intermediate bonding layer; c) Prepare functional surface slurry; d) The functional surface layer slurry is uniformly coated onto the surface of the intermediate bonding layer by flame spraying, and then sintered a second time after drying; e) Machining the sintered composite material.

[0014] Preferably, as an improvement, in step b), the first sintering is carried out under a reducing atmosphere at a temperature of 800~900 ℃ and a holding time of 1~2 hours.

[0015] Preferably, as an improvement, in step d), the second sintering is carried out under vacuum or reducing atmosphere protection, with the temperature increased to 750-850 ℃ at a rate of 5-10 ℃ / min, and the holding time is 1-1.5 hours.

[0016] Preferably, as an improvement, in step c), the functional surface slurry is prepared by wet ball milling, and the ball milling time is 4 to 8 hours.

[0017] The beneficial effects of this invention are as follows: 1. The sliding bearing made using the materials and preparation method of this invention has high load-bearing capacity: the combination of the high-strength alloy steel load-bearing layer, the copper-based alloy intermediate bonding layer, and the functional surface layer with a copper-tin-zinc alloy metal matrix provides the sliding bearing with extremely high mechanical strength and load-bearing capacity, and can withstand the heavy load and impact load of the rolling mill.

[0018] 2. Compared with the existing double-layer sliding bearing structure, which mainly relies on the bearing layer to provide strength and stiffness and cannot achieve comprehensive performance of strength and deformation adaptability, the present invention uses an intermediate bonding layer to achieve hardness transition and provides comprehensive performance of strength and deformation adaptability.

[0019] 3. Excellent wear resistance and self-lubricating properties: The MoS2 and graphite in the functional surface layer can form a stable solid lubricating film during friction, effectively reducing the coefficient of friction without the need for external lubricant; the addition of nano-ceramic particles with a particle size of 50~200 nanometers, accounting for 5~15% of the controller mass, combined with the effect of the mixed powder of MoS2 and graphite, can effectively reduce the coefficient of friction to 0.02~0.05, effectively reducing wear; in addition, the addition of nano-ceramic particles can also significantly improve the hardness and abrasive wear resistance of the functional surface layer.

[0020] 4. Excellent heat dissipation performance: The intermediate bonding layer and functional surface layer of the copper base have excellent thermal conductivity, which can quickly dissipate the heat generated by friction and prevent the bearing temperature from rising too high.

[0021] 5. High bonding strength: Through two sintering processes, the functional surface layer slurry is uniformly coated onto the surface of the intermediate bonding layer by flame spraying and then sintered again, achieving metallurgical bonding or strong diffusion bonding between the load-bearing layer, intermediate layer and functional surface layer. The bonding strength is high, avoiding interlayer delamination under alternating loads.

[0022] 6. Long service life: The synergistic effect of composite materials significantly extends the service life of bearings under the harsh working conditions of high-speed wire rod mills compared to traditional Babbitt alloy bearings or single polymer bearings. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the sliding bearing bushing of the present invention.

[0024] The reference numerals in the accompanying drawings include: bearing bushing 1, bearing layer 2, intermediate joint layer 3, and functional surface layer 4. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the embodiments.

[0026] Solution Overview Composite materials for sliding bearings in high-speed wire rod mills, such as Figure 1 As shown, from the outside to the inside (outer side to inner side of bearing bushing 1), it includes a bearing layer 2, an intermediate bonding layer 3, and a functional surface layer 4.

[0027] The load-bearing layer 2 is made of high-strength alloy steel, such as 42CrMo or GCr15; The intermediate bonding layer 3 is a copper-based alloy, preferably a copper-tin-nickel (Cu-Sn-Ni) alloy or a copper-lead (Cu-Pb) alloy; Functional surface layer 4 is composed of the following components by mass percentage: 60-75% copper-tin-zinc alloy powder, 15-25% mixed powder of molybdenum disulfide and graphite, 5-15% nano-ceramic particles, and 0.5-3% rare earth additives (such as cerium (Ce) and yttrium (Y). The mass ratio of molybdenum disulfide and graphite in the mixed powder is 1:1 to 3:1; the nano-ceramic particles are nano-Al₂O₃ with a particle size of 50-200 nanometers.

[0028] The method for preparing the sliding bearing composite material for the above-mentioned high-speed wire rod mill includes the following steps: a) Surface pretreatment of the substrate of bearing layer 2: high-strength alloy steel plate is machined to form a blank of bearing tile or bearing bushing, and then degreasing, derusting and sandblasting roughening treatment are performed to obtain bearing layer 2. b) The copper-based alloy powder is evenly spread on the surface of the bearing layer 2 after the treatment in step a) through tools such as a mesh screen. The first sintering is carried out in a sintering furnace under the protection of a reducing atmosphere (such as hydrogen-nitrogen mixture). The sintering temperature is 800~900℃ and the holding time is 1~2 hours, so that the copper-based alloy powder melts and forms a strong intermediate bonding layer 3 on the bearing layer 2. c) Preparation of functional surface layer 4 slurry: Weigh each component according to the above proportions, place them in a ball mill, add 3%~5% of the total mass of the functional surface layer 4 solid components of organic binder (such as polyvinyl butyral) and 40%~50% of solvent (such as ethanol), and perform wet ball milling for 4~8 hours to form a uniform and stable slurry. d) The functional surface layer 4 slurry is uniformly coated onto the surface of the intermediate bonding layer 3 by flame spraying at a temperature of 850-1200℃. After spraying, it is placed in a heating oven for drying to remove the solvent. Then, it is sintered for the second time in a sintering furnace under vacuum or a protective atmosphere (such as a hydrogen-nitrogen mixture). The temperature is increased to 750-850℃ at a rate of 5-10℃ / min and held for 1-1.5 hours. Then, it is cooled to room temperature with the furnace. e) Perform necessary machining (such as precision turning and scraping) on ​​the sintered composite material to achieve the final dimensional accuracy and surface roughness requirements. Finally, the functional surface layer 4 can be finely ground or polished to optimize its tribological properties.

[0029] Example 1 The sliding bearing bushing is prepared using the composite material and method of the present invention: Supporting layer: GCr15 bearing steel plate is selected, machined into bearing bushing blanks, and then subjected to degreasing, rust removal and sandblasting roughening treatment.

[0030] Intermediate bonding layer: Cu-5Pb-2Sn alloy powder was used, with each component in wt% (mass percentage): lead 5wt%, tin 2wt%, and balance copper; the powder thickness was 1.0 mm, and it was sintered at 820 °C for 1.5 hours under the protection of a hydrogen-nitrogen mixture (volume ratio 1:4).

[0031] Functional surface slurry ratio (wt%): Cu-10Sn-5Zn alloy powder: 65% A mixture of molybdenum disulfide (MoS2) and graphite powder (mixed in a 3:1 mass ratio): 22% Nano-Al2O3 particles (50nm diameter): 10% Rare earth additive (yttrium oxide Y2O3): 3% Slurry preparation and spraying: The above components were placed in a ball mill, and 4% polyvinyl butyral and 45% ethanol were added by mass of the total solid components. The mixture was wet-milled for 6 hours to form a uniform slurry. The slurry was then uniformly coated onto the surface of the intermediate bonding layer by flame spraying (spray gun temperature 1000℃), with a coating thickness of approximately 0.8 mm.

[0032] Second sintering: Place it in a vacuum furnace, heat it to 850 ℃ at a rate of 10 ℃ / min, hold it at that temperature for 1 hour, and then cool it to room temperature with the furnace.

[0033] Subsequent processing: The sintered parts are precision machined and scraped, and finally the functional surface layer is finely ground (surface roughness Ra≤0.2μm).

[0034] Test results: The composite material bearing made using the sliding bearing bushing of this embodiment has a stable friction coefficient of 0.03~0.04 under simulated high-speed wire rod mill conditions (linear speed 75 m / s, specific pressure 30 MPa), and the average wear rate is reduced by about 70% compared with traditional copper-lead alloy bearings.

[0035] Example 2 The difference between this embodiment and Embodiment 1 is that: Functional surface slurry ratio (wt%): Cu-8Sn-10Zn alloy powder: 60% A mixture of molybdenum disulfide (MoS2) and graphite powder (mixed in a 3:1 mass ratio): 25% Nano-Al2O3 particles (60nm diameter): 12% Cerium oxide (CeO2): 3% Process adjustments: The heating rate for the second sintering was reduced to 5 ℃ / min, and the holding temperature was changed to 750 ℃ ​​for 1.5 hours to allow the lubricating phase to be better dispersed and distributed.

[0036] Test results: The composite material bearing made using the sliding bearing bushing of this embodiment can maintain a friction coefficient of 0.02~0.03 under the same working conditions as in Example 1, and the wear rate is reduced by about 75%.

[0037] Comparative Example 1 Materials and Structure: The conventionally cast Cu-24Pb-4Sn copper-lead alloy bearing bushing (without delamination) was machined to the same dimensions and surface roughness (Ra≤0.2μm) as in Example 1. No surface modification or functional layer coating was performed.

[0038] Test results: Tests were conducted under the same conditions as in Example 1. The coefficient of friction initially was approximately 0.12, but after 5 minutes it rapidly increased to over 0.25, indicating significant adhesive wear. Compared to Example 2, the wear rate was approximately 400% higher.

[0039] Conclusion: Traditional copper-lead alloys cannot simultaneously meet the requirements of high load-bearing capacity and low friction. The three-layer composite structure of this application has significant advantages in comprehensive performance.

[0040] Comparative Example 2 Materials and Structure: It adopts a double-layer structure: the load-bearing layer is 42CrMo steel, and a layer of PTFE (polytetrafluoroethylene) + 30% carbon fiber polymer (1.0 mm thick) is directly laid on the surface, and then formed by hot pressing and sintering. There is no copper-based intermediate bonding layer.

[0041] Test results: Tests were conducted under the same conditions as in Example 1. The initial coefficient of friction was low (approximately 0.06), but after about 10 minutes of operation, due to the poor thermal conductivity of the polymer layer (<0.3 W / m·K), the interface temperature rapidly increased to 180°C, leading to PTFE softening and creep, and the coefficient of friction rose above 0.15. Under a specific pressure of 30 MPa, the polymer layer underwent significant extrusion deformation, resulting in uncontrolled bearing clearance. The wear rate was approximately 150% higher than in Example 1 (due to softening and peeling).

[0042] Conclusion: While the initial friction coefficient of the two-layer polymer structure is acceptable, its thermal conductivity and load-bearing capacity are insufficient, failing to meet the requirements of heavy-load, high-speed rolling mill operations. The three-layer structure of this application, through a copper-based intermediate layer, effectively conducts heat and transitions hardness, resulting in superior overall performance.

[0043] Comparative Example 3 Materials and structure: Except for the ratio of MoS2 to graphite in the functional surface layer, everything else is exactly the same as in Example 1.

[0044] Comparative Example 3a (ratio < 1:1): Formula: MoS 25% + Graphite 17% (mass ratio 0.3:1, total solid lubricant remains 22%) Results: Due to the excessive graphite content, the lubricating film strength was insufficient and it was quickly extruded under a specific pressure of 30 MPa. The coefficient of friction fluctuated between 0.06 and 0.10 and could not be stabilized below 0.04.

[0045] Comparative Example 3b (ratio > 3:1): Formula: 20% MoS2 + 2% Graphite (mass ratio 10:1, total solid lubricant remains 22%) Results: Due to the excessive MoS2 and insufficient graphite, the initial friction coefficient was slightly low (0.03). However, after 10 minutes of operation, due to the insufficient friction-reducing synergistic effect of graphite, the friction coefficient gradually increased to 0.07, and the wear rate was about 30% higher than that of Example 1.

[0046] Conclusion: A ratio that is too low (too much graphite) leads to failure of the bearing film; a ratio that is too high (too much MoS2) leads to a decrease in the synergistic friction reduction effect. The 1:1 to 3:1 range of this application simultaneously takes into account both the strength of the lubricating film and the stability of friction reduction.

[0047] Comparative Example 4 Materials and structure: Except for the particle size of nano-Al2O3 in the functional surface layer, everything else is exactly the same as in Example 1 (Al2O3 content is still 10%).

[0048] Comparative Example 4a (particle size <50 nm): Nano-Al2O3 with a particle size of 20 nm was used.

[0049] Results: During ball milling, the particles severely agglomerated and could not be uniformly dispersed in the slurry. After sintering, the functional layer contained a large number of micropores and particle agglomerates, resulting in an unstable coefficient of friction (0.05~0.08) and localized spalling. The wear rate was about 50% higher than that of Example 1.

[0050] Comparative Example 4b (particle size > 200 nm): Micron-sized Al2O3 with a particle size of 500 nm was used.

[0051] Results: The larger particles created a furrowing effect at the friction interface, which actually exacerbated wear. The coefficient of friction increased to 0.07-0.09, and the wear rate was approximately 60% higher than in Example 1.

[0052] Conclusion: Particles that are too small are prone to agglomeration, while those that are too large damage the lubricating film and lead to abrasive wear. The 50–200 nm range in this application ensures good dispersibility and enhances the friction-increasing and friction-reducing effects.

[0053] Comparative Example 5 Materials and structure: Except for the content of nano Al2O3 in the functional surface layer, everything else is exactly the same as in Example 1 (particle size of 100 nm is selected).

[0054] Comparative Example 5a (content <5%): The content of nano-Al2O3 was set to 2%, and the Cu-10Sn-5Zn alloy powder was increased to 73% accordingly (keeping the solid lubricant at 22% and rare earth at 3%).

[0055] Results: Due to insufficient hard second phase, the functional layer has low hardness, the friction coefficient increases to 0.06~0.08, and the wear rate is about 80% higher than that of Example 1.

[0056] Comparative Example 5b (content > 15%): The content of nano-Al2O3 was set to 20%, and the Cu-10Sn-5Zn alloy powder was reduced to 55% accordingly (while keeping the lubricant content at 22% and the rare earth content at 3%).

[0057] Results: The functional layer exhibited increased brittleness and decreased toughness. Under an impact load of 30 MPa, microcracks appeared in the functional layer, and the coefficient of friction fluctuated drastically between 0.05 and 0.12. The wear rate was approximately 120% higher than that of Example 1 (due to brittle spalling).

[0058] Conclusion: Too low a content of nano-Al2O3 in the functional surface layer cannot effectively strengthen the matrix, while too high a content leads to brittle fracture. The 5-15% range in this application achieves the optimal balance between hardness and toughness.

[0059] The above five comparative examples systematically demonstrate that the selection of material system (three-layer structure), key ratios (MoS2 / graphite ratio, ceramic particle size, ceramic content) in this application have non-obvious technical effects.

[0060] Load-bearing capacity test: Tests were conducted on Examples 1-2 and Comparative Examples 1, 2, 3a, 3b, 4a, ab, 5a, and 5b, respectively.

[0061] Testing method: (1) Static compression test Reference standards: GB / T 1041-2008 (Plastics compression test) and load-bearing capacity assessment method for metal matrix composites.

[0062] Sample: Take the prepared sliding bearing bushing (outer diameter 100mm, inner diameter 80mm, width 50mm).

[0063] Equipment: Universal testing machine, loading speed 2 mm / min.

[0064] Procedure: Apply a compressive load radially to the bearing bushing and record the critical load value (i.e., the rated load compressive deformation requirement) when the permanent plastic deformation reaches 0.02 mm.

[0065] Environment: Room temperature, no lubrication.

[0066] (2) Dynamic impact bearing test Reference standard: Fatigue load assessment method in JB / T 7925.1-2013 (Sliding bearings, multilayer metal sliding bearings, part 1: dimensions, tolerances and material specifications).

[0067] Specimen: Same as static load test.

[0068] Equipment: High-frequency fatigue testing machine, loading frequency 10 Hz, force range 0 to maximum impact load.

[0069] Process: Apply periodic radial impact loads (simulating the impact of steel biting in a rolling mill) and record the number of cycles (corresponding specific pressure values) when the functional surface shows the first signs of microcracks or spalling.

[0070] The test results are shown in Table 1: Table 1

[0071]

[0072] Analysis of load-bearing test results: 1. The load-bearing advantages of Example 1 and Example 2: (1) The static rated load (≥320~330MPa) and dynamic fatigue limit (≥32~33MPa) are significantly higher than all comparative examples (the traditional copper-lead alloy is only 220MPa / 20MPa), with an increase of about 45~50%.

[0073] (2) The performance of Example 2 is slightly better than that of Example 1, indicating that lowering the sintering temperature (750°C) and extending the holding time (1.5h) helps the lubricating phase to disperse and further improve the load-bearing and fatigue performance.

[0074] 2. The significance of the comparison in examples 1 and 2: Comparative Examples 1 (conventional copper-lead alloy) and 2 (double-layer polymer structure) have significantly lower load-bearing capacities than this application (45% and 330% lower, respectively), demonstrating that the three-layer composite material structure of this invention represents a non-obvious technological advancement in load-bearing capacity.

[0075] 3. Comparison of the sub-items in Examples 3-5: (1) Comparative Examples 3a / 3b (MoS2:graphite ratio deviates from the range): the load-bearing capacity decreases by 15~25%, indicating that a ratio range of 1:1~3:1 is the key choice to balance load-bearing capacity and friction reduction.

[0076] (2) Comparative Examples 4a / 4b (nano Al2O3 particle size deviates from 50~200nm): the load-bearing capacity decreased by 35~40%, proving that the particle size of 50~200nm is indispensable for the compactness and enhancement effect of the functional layer.

[0077] (3) Comparative Examples 5a / 5b (mass percentage of nano-Al2O3 deviates from 5~15%): the load-bearing capacity decreases by 40~45%, proving that the content of nano-ceramic particles of 5~15% is the optimal range to ensure the hardness and toughness of the functional layer.

[0078] in conclusion: The composite material bearings of Examples 1 and 2 of this invention, under simulated high-speed wire rod mill conditions, achieve a static load capacity of 320-330 MPa and a dynamic fatigue limit of 32-33 MPa, far superior to traditional copper-lead alloys (220 MPa / 20 MPa) and double-layer polymer structures (120 MPa / 10 MPa). Simultaneously, their load-deformation characteristics meet the first-level bearing specifications (overall compressive strength ≥1300 MPa, deformation ≤0.02 mm). The comparative analysis of each example systematically verifies the optimization effect of the layer selection (MoS2 / graphite ratio, nano-ceramic particle size and content) of this invention in terms of load-bearing and wear resistance synergy.

[0079] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A composite material for sliding bearings used in high-speed wire rod mills, characterized in that: From the outside in, it includes a load-bearing layer, an intermediate bonding layer, and a functional surface layer. The functional surface layer consists of the following components by mass percentage: 60-75% copper-tin-zinc alloy powder, 15-25% mixed powder of molybdenum disulfide and graphite, 5-15% nano-ceramic particles, and 0.5-3% rare earth additives.

2. The composite material for sliding bearings in high-speed wire rod mills according to claim 1, characterized in that: The load-bearing layer is made of alloy steel.

3. The composite material for sliding bearings in high-speed wire rod mills according to claim 1, characterized in that: The intermediate bonding layer is a copper-based alloy.

4. The composite material for sliding bearings in high-speed wire rod mills according to claim 1, characterized in that: In a mixed powder of molybdenum disulfide and graphite, the mass ratio of the two is 1:1 to 3:

1.

5. The composite material for sliding bearings in high-speed wire rod mills according to claim 1, characterized in that: The nano-ceramic particles are nano-Al2O3.

6. The composite material for sliding bearings in high-speed wire rod mills according to claim 1, characterized in that: The particle size of nano-Al2O3 is 50~200 nanometers.

7. A method for preparing a sliding bearing composite material for a high-speed wire rod mill as described in any one of claims 1-6, characterized in that: Includes the following steps: a) Perform surface pretreatment on the substrate of the bearing layer; b) Copper-based alloy powder is laid on the surface of the bearing layer and sintered for the first time to form an intermediate bonding layer; c) Prepare functional surface slurry; d) The functional surface layer slurry is uniformly coated onto the surface of the intermediate bonding layer by flame spraying, and then sintered a second time after drying; e) Machining the sintered composite material.

8. The method for preparing the sliding bearing composite material for high-speed wire rod mills according to claim 7, characterized in that: In step b), the first sintering is carried out under a reducing atmosphere at a temperature of 800~900 ℃ and a holding time of 1~2 hours.

9. The method for preparing the composite material for sliding bearings in high-speed wire rod mills according to claim 8, characterized in that: In step d), the second sintering is carried out under vacuum or reducing atmosphere protection, with the temperature increased to 750-850 ℃ at a rate of 5-10 ℃ / min, and the holding time is 1-1.5 hours.

10. The method for preparing the sliding bearing composite material for high-speed wire rod mills according to claim 9, characterized in that: In step c), the functional surface slurry is prepared by wet ball milling for 4 to 8 hours.

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