Self-lubricating porous copper-based oil-containing bearing material, preparation method and application thereof, and bearing containing the material

Abstract

The application discloses a self-lubricating porous copper-based oil-containing bearing material and a preparation method, application and bearing containing the material thereof, and the preparation method comprises the following steps: material pretreatment: reducing and drying treatment is performed on copper-tin binary alloy powder; mold pressing and sintering forming: the pretreated copper-tin binary alloy powder is sequentially subjected to mold pressing preforming and near-melting-point sintering treatment, and a porous copper-tin binary alloy blank is obtained; borax immersion treatment: the blank is placed in a container containing a borax aqueous solution, and is sequentially immersed under vacuum and normal pressure conditions, and is dried and solidified, so that a borax film is formed on the inner wall of the pores of the blank; gradient solid solution treatment: the blank after the borax immersion treatment is subjected to two-stage temperature rising heat treatment in a protective atmosphere, and is rapidly cooled to room temperature, and a self-lubricating porous copper-based oil-containing bearing material is obtained, the preparation method is simple and efficient, the heat energy consumption is greatly reduced, and the prepared bearing material has a stable porous gap structure and has the characteristics of self-lubrication and high strength and toughness.

Description

Technical Field

[0001] This invention belongs to the technical field of metallic materials, and particularly relates to self-lubricating porous copper-based oil-impregnated bearing materials, their preparation methods, applications, and bearings containing such materials. Background Technology

[0002] Porous tin bronze oil-impregnated bearings are widely used in micro motors, precision instruments, and other fields due to their self-lubricating properties and good wear resistance. The preparation of oil-impregnated bearing materials requires solution heat treatment. Existing solution heat treatment processes face three major bottlenecks in improving the performance of oil-impregnated bearing materials: First, traditional solution treatments (such as long-term high-temperature treatment at 650-750℃) easily lead to the collapse or deformation of the porous structure, significantly reducing the oil content and lubrication effect. For example, the homogenization treatment of tin-phosphorus bronze requires holding at 680-720℃ for 6-10 hours, causing deterioration of pore connectivity. Second, relying solely on solution strengthening has limited effect on hardness improvement. While adding alloying elements (such as Ni, Si, etc.) can improve hardness through aging precipitation strengthening, the precipitated phases may block pore channels, affecting oil storage performance. Third, existing solution heat treatment processes are energy-intensive and inefficient, only suitable for processing dense materials and cannot be applied to porous materials. Summary of the Invention

[0003] The purpose of this invention is to solve at least one problem in the prior art, and to propose a self-lubricating porous copper-based oil-impregnated bearing material, its preparation method, application, and bearings containing the material.

[0004] To achieve the above objectives, this invention proposes a method for preparing a self-lubricating porous copper-based oil-impregnated bearing material, comprising the following steps:

[0005] Material pretreatment: The copper-tin binary alloy powder is subjected to reduction and drying treatment;

[0006] Compression molding and sintering: The pretreated copper-tin binary alloy powder is sequentially subjected to compression molding and near-melting point sintering to obtain a porous copper-tin binary alloy billet.

[0007] Borax impregnation treatment: The porous copper-tin binary alloy billet is placed in a container containing a borax aqueous solution and impregnated under vacuum and normal pressure conditions in sequence, and then dried and cured, so that a borax film is formed on the inner wall of the pores of the porous copper-tin binary alloy billet.

[0008] Gradient solution treatment: The porous copper-tin binary alloy billet after borax impregnation is heated to 280℃-300℃ at a rate of 1℃ / min-5℃ / min under a protective atmosphere and held for 5min-15min. Then, the temperature is increased to 520℃-550℃ at a rate of 3℃ / min-5℃ / min and held for 15min-30min. Finally, it is cooled to room temperature at a rate of not less than 200℃ / s to obtain a self-lubricating porous copper-based oil-impregnated bearing material.

[0009] The copper-tin binary alloy powder contains 8 wt.% to 20 wt.% tin.

[0010] As an optional implementation, in the material pretreatment step, the particle size of the copper-tin binary alloy powder is 150-300 mesh, and the morphology of the copper-tin binary alloy powder is at least one of spherical, dendritic, or irregular shapes.

[0011] As an optional implementation, in the material pretreatment step, the reduction drying treatment is carried out in a hydrogen furnace, and the reduction drying treatment process is as follows: the reduction temperature is 200℃-400℃, the holding time is 1h-3h, the heating rate is 5℃ / min-20℃ / min, the reduction atmosphere is high-purity hydrogen or ammonia decomposition hydrogen, the atmosphere dew point is ≤-25℃, and the furnace is cooled to room temperature.

[0012] As an optional implementation, in the molding and sintering step, the molding preforming adopts a uniaxial limiting cold pressing method for molding, and the height compression ratio is controlled to be between 1.55 and 1.8 during the molding process.

[0013] As an optional implementation, in the molding and sintering step, the near-melting-point sintering treatment is carried out in a sintering furnace, and the sintering process is as follows: first, the temperature is raised to 250℃-300℃ at 1℃ / min-5℃ / min and held for 2h-4h; then, the temperature is raised to 700℃-775℃ at 5℃ / min-10℃ / min and held for 1h-2.5h. The sintering atmosphere is high-purity hydrogen or ammonia decomposition hydrogen, and the atmosphere dew point is ≤-25℃. The furnace is then cooled to room temperature.

[0014] As an optional implementation, in the borax impregnation treatment step, the concentration of the borax aqueous solution is 3wt.%-8wt.%, and ion clusters or single ions with a diameter ≤100nm are formed in the borax aqueous solution. The borax impregnation process is as follows: first, impregnate for 10min-20min under vacuum conditions with a relative vacuum degree of -0.1MPa--0.05MPa, then impregnate for 20min-30min under normal pressure conditions, and finally dry and cure by holding at 80℃-100℃ for 30min-60min.

[0015] As an optional implementation, in the gradient solution treatment step, the protective atmosphere is a vacuum degree ≤ 5 × 10⁻⁶. -2 Pa, under hydrogen or argon atmosphere, the atmosphere dew point is ≤-25℃; cooling to room temperature at a cooling rate of not less than 200℃ / s is carried out by water cooling, and the water tank temperature is controlled between 4℃ and 25℃ during the water cooling process.

[0016] The present invention also proposes a self-lubricating porous copper-based oil-impregnated bearing material prepared according to the above preparation method.

[0017] The present invention also proposes an application of the above-mentioned self-lubricating porous copper-based oil-impregnated bearing material in bearing materials for short-term impact high load or medium-low speed continuous high load.

[0018] The present invention also proposes a bearing containing the above-mentioned self-lubricating porous copper-based oil-impregnated bearing material. The bearing includes any one of the following: micro servo motor spindle bearing, automotive EPS torque sensor bearing, precision stamping die guide pillar bearing, and industrial robot joint reducer bearing. The absolute load of the bearing is ≤35N / mm², and the critical point of PV value is ≤3N / mm²·m / s.

[0019] This application's preparation method achieves a leap in the performance of porous materials through structural control and thermodynamic design by employing raw material pretreatment and molding sintering. Utilizing borax impregnation pretreatment technology, followed by vacuum-assisted infiltration and drying dehydration, a dynamic molten protective film is formed in situ on the inner wall of the pores through in-situ self-wetting. Its high-temperature viscoelastic properties simultaneously achieve a triple function: oxidation inhibition (isolation of oxygen diffusion), thermal stress dissipation (buffering the thermal expansion difference stress between the matrix and pore gases), and capillary force maintenance (smoothing the pore walls and reducing the contact angle). Through a dual mechanism of chemical film formation and physical sealing, the pore structure integrity of the porous matrix is ​​ensured during subsequent solution strengthening treatment. The gradient solution heat treatment in the preparation process is based on the precise control of the phase transformation kinetics of copper-tin alloys. After eliminating residual stress, the slow heating balances the thermal expansion difference between the matrix and pores, allowing Sn atoms to fully dissolve in the α-Cu lattice to form a high-density distortion field. Combined with ultrafast cooling to lock the supersaturated solution state, this suppresses Sn atom segregation and δ-Cu... 41 Sn 11 The precipitation of brittle phases significantly improves dislocation pinning strength.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention employs a unique gradient solution treatment process, which requires a significantly lower heating temperature than traditional solution treatment, thereby greatly reducing heat energy consumption. At the same time, the heat treatment cycle is short, improving equipment turnover and increasing production efficiency.

[0022] 2. The overall preparation method of this invention is simple and efficient, and can significantly reduce the overall production cost while ensuring the consistency of product performance.

[0023] 3. The self-lubricating porous copper-based oil-impregnated bearing material prepared by this invention has high hardness (hardness reaches 105HV-120HV), stable porous structure (porosity decay does not exceed 1%), and excellent wear resistance (volume wear rate does not exceed 0.15 mm³ / km). While retaining 20%-25% oil content, it also has self-lubricating and high strength and toughness characteristics. This material can be used in the field of oil-impregnated bearings with short-term impact high load or medium-low speed continuous high load.

[0024] The features and advantages of the present invention will be described in detail through embodiments and in conjunction with the accompanying drawings. Attached Figure Description

[0025] Figure 1 This is the self-lubricating porous Cu of Embodiment 1 of the present invention. 85 Sn 15 OM morphology diagram of bearing material.

[0026] Figure 2 This is the self-lubricating porous Cu of Embodiment 1 of the present invention. 85 Sn 15 SEM image of bearing material.

[0027] Figure 3 This is the self-lubricating porous Cu of Embodiment 1 of the present invention. 85 Sn 15 XRD pattern of bearing material. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0029] The present invention will now be described in detail with reference to the accompanying drawings.

[0030] Example 1

[0031] This embodiment provides a method for preparing a self-lubricating porous copper-based oil-impregnated bearing material, including the following steps:

[0032] S01. Material pretreatment: Cu with a particle size of 200 mesh and a dendritic morphology is pretreated. 85 Sn 15 The powder was placed in a hydrogen reduction furnace and heated to 250°C at a heating rate of 10°C / min under a reducing atmosphere of high-purity hydrogen with a dew point of -30°C. It was held at this temperature for 2 hours and then cooled to room temperature with the furnace to complete the reduction of Cu. 85 Sn 15 Powder reduction and drying treatment;

[0033] S02. Molding and sintering: The pretreated Cu... 85 Sn 15 The powder is first pre-formed by uniaxial limiting cold pressing at a high compression ratio of 1.65, and then the pre-formed Cu... 85 Sn 15 The block was placed in a sintering furnace and heated to 300°C in a high-purity hydrogen atmosphere with a dew point of -30°C. The temperature was then maintained at 5°C / min for 2 hours to eliminate residual stress from the pressing process and to further reduce and press the Cu. 85 Sn 15 The material is then heated to 750°C at a rate of 8°C / min, held at that temperature for 2 hours, and then cooled to room temperature in the furnace to complete near-melting-point sintering, yielding porous Cu. 85 Sn 15 billet;

[0034] S03. Borax impregnation treatment: Impregnation of porous Cu... 85 Sn 15 The blank was placed in a container containing a 5 wt.% borax aqueous solution with ion clusters ≤50 nm in diameter. First, a vacuum was applied to a relative vacuum of -0.05 MPa, and the blank was impregnated for 15 min, then impregnated under normal pressure for 25 min. Finally, it was dried and cured in a vacuum drying oven at 90℃ for 45 min, resulting in porous Cu. 85 Sn 15 A borax film forms on the inner wall of the pores of the billet;

[0035] S04. Gradient solution treatment: Porous Cu impregnated with borax 85 Sn 15 The billet is placed in a sintering furnace, under a vacuum degree ≤5×10 -2 Under Pa and argon conditions, the material is first heated to 300℃ at a heating rate of 3℃ / min and held for 10 min. Then, it is heated to 530℃ at a heating rate of 5℃ / min and held for 20 min. Finally, the billet is rapidly transferred from the furnace to a 20℃ cold water bath within 5 seconds and rapidly cooled to room temperature at a cooling rate of not less than 250℃ / s to obtain high-strength, wear-resistant, self-lubricating porous Cu. 85 Sn 15 Bearing materials.

[0036] Self-lubricating porous Cu 85 Sn 15 The bearing material has a hardness of 110HV-120HV, a porosity decay of ≤1%, a volumetric wear resistance of ≤0.15 mm³ / km, and can achieve an oil content of 20%-25%.

[0037] This embodiment also provides a self-lubricating porous tin bronze oil-impregnated bearing made from the aforementioned self-lubricating porous Cu85Sn15 bearing material. This bearing is suitable for use in the spindle bearing of a micro servo motor with continuous high load at medium and low speeds. The continuous load of this bearing can reach 25 N / mm²-28 N / mm², and the critical point of the PV value reaches 2.3 N / mm². 2 ·m / s-2.5 N / mm 2 ·m / s.

[0038] Example 2

[0039] This embodiment provides a method for preparing a self-lubricating porous copper-based oil-impregnated bearing material, including the following steps:

[0040] S01. Material pretreatment: Pretreatment of Cu particles with a particle size of 150 mesh and spherical morphology... 92 Sn8 powder was placed in a hydrogen reduction furnace and heated to 400°C at a heating rate of 20°C / min under a reducing atmosphere of high-purity hydrogen with a dew point of -25°C. The temperature was held for 3 hours, and then cooled to room temperature with the furnace to complete the reduction of Cu. 92 Reduction and drying treatment of Sn8 powder;

[0041] S02. Molding and sintering: The pretreated Cu... 92 Sn8 powder is first pre-formed by uniaxial limiting cold pressing at a high compression ratio of 1.8, and then the pre-formed Cu... 92 Sn8 blocks were placed in a sintering furnace and heated to 300°C at a rate of 4°C / min under a high-purity hydrogen atmosphere with a dew point of -25°C. The temperature was then held for 4 hours to eliminate residual stress from the pressing process and to further reduce and press Cu. 92 The Sn8 material was then heated to 775°C at a rate of 10°C / min, held at that temperature for 2.5 hours, and then cooled to room temperature in the furnace to complete near-melting-point sintering, yielding porous Cu. 92 Sn8 billet;

[0042] S03. Borax impregnation treatment: Impregnation of porous Cu... 85 Sn 15 The blank was placed in a container containing an 8 wt.% borax aqueous solution with ion clusters ≤80 nm in diameter. First, a vacuum was applied to a relative vacuum of -0.03 MPa, and the blank was impregnated for 20 min, then impregnated again under normal pressure for 30 min. Finally, it was dried and cured in a vacuum drying oven at 100℃ for 60 min, resulting in porous Cu. 92 A borax film forms on the inner pore walls of the Sn8 billet;

[0043] S04. Gradient solution treatment: Porous Cu impregnated with borax 92 The Sn8 billet was placed in a sintering furnace under a vacuum degree ≤5×10-2 Under Pa and hydrogen conditions, the material is first heated to 300℃ at a heating rate of 5℃ / min and held for 15 min. Then, it is heated to 550℃ at a heating rate of 5℃ / min and held for 30 min. Finally, the billet is rapidly transferred from the furnace to a 10℃ cold water bath within 5 seconds and rapidly cooled to room temperature at a cooling rate of not less than 200℃ / s to obtain high-strength, wear-resistant, self-lubricating porous Cu. 92 Sn8 bearing material.

[0044] This embodiment also provides a self-lubricating porous Cu as described above. 92 A self-lubricating porous tin bronze oil-impregnated bearing made of Sn8 bearing material can be used as a bearing for automotive EPS torque sensors.

[0045] Example 3

[0046] This embodiment provides a method for preparing a self-lubricating porous copper-based oil-impregnated bearing material, including the following steps:

[0047] S01. Material pretreatment: Cu with a particle size of 300 mesh and a spherical morphology is pretreated. 80 Sn 20 The powder was placed in a hydrogen reduction furnace and heated to 200°C at a heating rate of 5°C / min under a reducing atmosphere of high-purity hydrogen with a dew point of -28°C. It was held at this temperature for 1 hour and then cooled to room temperature with the furnace to complete the reduction of Cu. 80 Sn 20 Powder reduction and drying treatment;

[0048] S02. Molding and sintering: The pretreated Cu... 80 Sn 20 The powder is first pre-formed by uniaxial limiting cold pressing at a high compression ratio of 1.55, and then the pre-formed Cu... 80 Sn 20 The block was placed in a sintering furnace and heated to 250°C at a rate of 1°C / min under a high-purity hydrogen atmosphere with a dew point of -28°C. It was then held at this temperature for 2 hours to eliminate residual stress from the pressing process and to further reduce and press the Cu. 80 Sn 20 The material is then heated to 700℃ at a rate of 5℃ / min, held at that temperature for 1 hour, and then cooled to room temperature in the furnace to complete near-melting-point sintering, yielding porous Cu. 80 Sn 20 billet;

[0049] S03. Borax impregnation treatment: Impregnation of porous Cu... 80 Sn 20The blank was placed in a container containing a 5 wt.% borax aqueous solution with ion clusters ≤100 nm in diameter. First, a vacuum was applied to a relative vacuum of -0.01 MPa, and the blank was impregnated for 10 min, then impregnated under normal pressure for 20 min. Finally, it was dried and cured in a vacuum drying oven at 80℃ for 30 min, resulting in porous Cu. 80 Sn 20 A borax film forms on the inner wall of the pores of the billet;

[0050] S04. Gradient solution treatment: Porous Cu impregnated with borax 80 Sn 20 The billet is placed in a sintering furnace, under a vacuum degree ≤5×10 -2 Under Pa and argon conditions, the material is first heated to 280℃ at a heating rate of 1℃ / min and held for 6 minutes. Then, it is heated to 520℃ at a heating rate of 3℃ / min and held for 18 minutes. Finally, the billet is rapidly transferred from the furnace to a 25℃ cold water bath within 5 seconds and rapidly cooled to room temperature at a cooling rate of not less than 200℃ / s to obtain high-strength, wear-resistant, self-lubricating porous Cu. 80 Sn 20 Bearing materials.

[0051] Example 4

[0052] This embodiment provides a method for preparing a self-lubricating porous copper-based oil-impregnated bearing material, including the following steps:

[0053] S01. Material Pretreatment: Pretreatment of Cu particles with a particle size of 180 mesh and an irregular morphology... 90 Sn 10 The powder was placed in a hydrogen reduction furnace and heated to 300°C at a heating rate of 15°C / min under a reducing atmosphere of high-purity hydrogen with a dew point of -25°C. The temperature was held for 2 hours, and then cooled to room temperature with the furnace to complete the reduction of Cu. 90 Sn 10 Powder reduction and drying treatment;

[0054] S02. Molding and sintering: The pretreated Cu... 90 Sn 10 The powder is first pre-formed by uniaxial limiting cold pressing at a high compression ratio of 1.7, and then the pre-formed Cu... 90 Sn 10 The block was placed in a sintering furnace and heated to 270°C at a rate of 4°C / min under a high-purity hydrogen atmosphere with a dew point of -25°C. It was then held at this temperature for 3 hours to eliminate residual stress from the pressing process and to further reduce and press the Cu. 90 Sn 10The material is then heated to 760°C at a rate of 8°C / min, held at that temperature for 2 hours, and then cooled to room temperature in the furnace to complete near-melting-point sintering, yielding porous Cu. 90 Sn 10 billet;

[0055] S03. Borax impregnation treatment: Impregnation of porous Cu... 90 Sn 10 The blank was placed in a container containing a 7 wt.% borax aqueous solution with ion clusters ≤100 nm in diameter. First, a vacuum was applied to a relative vacuum of -0.05 MPa, and the blank was impregnated for 20 min, then impregnated under normal pressure for 50 min. Finally, it was dried and cured in a vacuum drying oven at 90 °C for 40 min, resulting in porous Cu. 90 Sn 10 A borax film forms on the inner wall of the pores of the billet;

[0056] S04. Gradient solution treatment: Porous Cu impregnated with borax 90 Sn 10 The billet is placed in a sintering furnace, under a vacuum degree ≤5×10 -2 Under Pa and argon conditions, the material is first heated to 290℃ at a heating rate of 4℃ / min and held for 12 min. Then, it is heated to 540℃ at a heating rate of 5℃ / min and held for 24 min. Finally, the billet is rapidly transferred from the furnace to a 15℃ cold water bath within 4 seconds and rapidly cooled to room temperature at a cooling rate of not less than 250℃ / s to obtain high-strength, wear-resistant, self-lubricating porous Cu. 90 Sn 10 Bearing materials.

[0057] Example 5

[0058] This embodiment provides a method for preparing a self-lubricating porous copper-based oil-impregnated bearing material. Except for the use of an 8wt% borax aqueous solution in the SO3 borax impregnation treatment step, the other steps and process parameters are the same as in Example 1.

[0059] Example 6

[0060] This embodiment provides a method for preparing a self-lubricating porous copper-based oil-impregnated bearing material. Except for the second stage of the SO4 gradient solution treatment step, where the temperature is raised to 520°C and the holding time is extended to 30 min, the other steps and process parameters are the same as in Example 1.

[0061] Comparative Example 1

[0062] Compared to the preparation method of Example 1, this comparative example is identical to Example 1 except for the absence of the SO3 borax impregnation step.

[0063] Comparative Example 2

[0064] Compared to the preparation method of Example 1, the preparation method of this comparative example is the same as that of Example 1, except that the second stage of the SO4 gradient solution treatment step involves heating to 650°C, holding at that temperature for 1 hour, and then air cooling to room temperature.

[0065] Comparative Example 3

[0066] Compared to the preparation method of Example 1, this comparative example differs from Example 1 except that the step of directly heating to 530°C at a heating rate of 10°C / min in the SO4 gradient solution treatment step is omitted, and the step of heating to 300°C at a heating rate of 3°C / min and holding for 10min is omitted. The remaining steps and process parameters are the same as in Example 1.

[0067] Comparative Example 4

[0068] Compared to the preparation method of Example 1, this comparative example is identical to Example 1 except that the SO4 gradient solution treatment step only involves holding at 530°C for 20 minutes and then air cooling to room temperature.

[0069] Equal amounts of bearing materials were prepared using the preparation methods of Examples 1, 5, 6 and Comparative Examples 1-4. Under the same test conditions, the performance indicators such as hardness, porosity decay, oil content, and wear of each bearing material were tested, and the failure modes of each material were analyzed and recorded. The specific test results are shown in Table 1 below.

[0070] The testing methods for the above performance indicators are as follows:

[0071] Hardness: Referencing standard GB / T 4340.1-2009, the hardness of the samples was tested using a Vickers hardness tester with a load of 300gf and a holding time of 10s. Five points were tested for each group of samples, and the average value was taken.

[0072] Porosity decay and oil content: Referring to standard GB / T 5163-2006, the impregnation method was used to fill the material pores with impregnating oil. The dry weight w1, the weight w2 after oil impregnation, and the weight w3 in water were calculated. Based on the porosity formula (w2-w1) / (w2-w3)×100%, the porosity a1 of the sintered sample and the porosity a2 of the sample after sintering and solution treatment were obtained respectively. The porosity decay was calculated as (a1-a2) / a1×100%. The oil content was calculated using the formula (w2-w1) / (ρ... 油 ·V 材料 The oil content is obtained by multiplying the product by 100%.

[0073] Wear amount: Refer to the standard ASTM G65. The test conditions are: load 10 N, sliding speed 0.5 m / s, wear time 30 min, and abrasive is 100 μm quartz sand. The wear volume is calculated by measuring the mass of the sample before and after wear, and then divided by the total wear distance to obtain the wear amount.

[0074] Table 1 Comparison of Performance Indicators of Different Bearing Materials

[0075]

[0076] Compared with Comparative Examples 1-4, the bearing materials of Examples 1, 5, and 6 have less void ratio decay, less wear, higher oil content, and a hardness of over 105 HV.

[0077] The porous Cu of Example 1 was examined using an optical microscope and a scanning electron microscope, respectively. 85 Sn 15 The morphology of the bearing material was analyzed, and the specific OM morphology diagram is shown below. Figure 1 As shown, the SEM topography image is as follows: Figure 2 As shown.

[0078] Depend on Figure 1 It can be seen that the porous Cu in the image 85 Sn 15 The black, irregular areas in the bearing material are pores. These pores are numerous and relatively evenly distributed, without large aggregates, indicating good control over the powder mixing and pressing processes. The pores are irregularly shaped and distributed in a connected network, indicating the formation of typical powder metallurgy sintering pores, stemming from the incomplete filling of gaps between the original powder particles after sintering. This three-dimensional interconnected pore network is the basis for the penetration and storage of lubricating oil, giving the material excellent self-lubricating properties.

[0079] Depend on Figure 2 It can be seen that porous Cu 85 Sn 15 The bearing material has a smooth, rounded grain profile and a coarse sintering neck. This is because the Sn content in the alloy is very high, and a large amount of liquid phase will appear during sintering. The structure shown in the picture is a typical result of transient liquid phase sintering. The appearance of the liquid phase greatly promotes atomic diffusion and particle rearrangement.

[0080] XRD analysis of porous Cu in Example 1 85 Sn 15 The bearing material was tested, and the corresponding XRD patterns were obtained. Specific XRD patterns are shown below. Figure 3 As shown.

[0081] Depend on Figure 3 It can be seen that the porous Cu prepared according to the method of this application 85 Sn 15 The bearing material contains no other harmful hard and brittle phases, and the XRD pattern shows no peaks.

[0082] The bearing material in Comparative Example 1, due to the omission of the borax impregnation step during preparation, has porous Cu... 85 Sn15 During solution heat treatment, the pore structure of bearing materials loses the protection of the borax film. The difference in thermal expansion between the copper matrix and the pore gas generates excessive stress concentration at the pore edges during gradient heating, causing microcracks to propagate along the pore network. At the same time, the pore walls without the support of the borax film undergo plastic rheology at the solution temperature, leading to irreversible collapse of the pore structure. This results in a reduction in oil storage volume and a decrease in oil content, ultimately leading to multi-dimensional failures such as thermal stress cracks, pore collapse, and oil film rupture during friction, resulting in deterioration of wear resistance.

[0083] In the preparation of the bearing material in Comparative Example 2, the solution treatment exceeded the upper limit of the α phase region in the alloy (586℃), initiating phase transformation instability and a eutectoid reaction at high temperature, resulting in γ(Cu) 31 The brittle Sn8 phase precipitates along the grain boundaries, disrupting the continuity of the matrix and forming stress concentration sources. At the same time, the high-temperature softening effect reduces the yield strength of the matrix, and the pore skeleton undergoes viscous rheology under thermal load, leading to porosity decay. This results in a sharp reduction in oil storage volume, insufficient lubrication causing local dry friction, and inducing adhesive wear, leading to a decrease in wear resistance. Furthermore, brittle spalling of the γ phase and macroscopic plastic collapse occur during the friction process.

[0084] In the preparation of the bearing material of Comparative Example 3, the temperature was directly and rapidly increased to the solution temperature without using a gradient heating method, which triggered severe thermal stress damage. The residual stress from sintering and the stress from rapid thermal expansion were coupled and superimposed at the pore edges, causing the local stress peak to exceed the tensile strength of the material and inducing the initiation of intergranular microcracks. At the same time, the thermal shock caused the borax film to peel off partially, and some pore structures became unstable. The crack propagation caused the pore communication channels to break, resulting in a decrease in oil content and a decrease in wear resistance. During the friction process, the crack edges fatigued and peeled off under cyclic load to form abrasive grains.

[0085] In the preparation of the bearing material in Comparative Example 4, the first-stage low-temperature stress relief was not performed, resulting in the retention of sintering residual stress. During the subsequent high-temperature holding, the superimposed thermal stress caused the accumulation of lattice distortion energy. At the same time, the air cooling rate was much lower than that of water cooling, and during the slow cooling process, Sn atoms diffused into the pore walls to form a tin-rich layer and precipitated needle-like δ-Cu. 41 In the Sn8 brittle phase, under frictional load, the residual stress and the brittle phase work together to trigger spalling along the phase interface, and the spalled hard particles act as abrasive grains, aggravating wear.

[0086] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Any simple modifications to the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing a self-lubricating porous copper-based oil-impregnated bearing material, characterized in that, It includes the following steps: Material pretreatment: The copper-tin binary alloy powder is subjected to reduction and drying treatment; Compression molding and sintering: The pretreated copper-tin binary alloy powder is sequentially subjected to compression molding and near-melting point sintering to obtain a porous copper-tin binary alloy billet. Borax impregnation treatment: The porous copper-tin binary alloy billet is placed in a container containing a borax aqueous solution and impregnated under vacuum and normal pressure conditions in sequence, and then dried and cured, so that a borax film is formed on the inner wall of the pores of the porous copper-tin binary alloy billet. Gradient solution treatment: The porous copper-tin binary alloy billet after borax impregnation is heated to 280℃-300℃ at a rate of 1℃ / min-5℃ / min under a protective atmosphere and held for 5min-15min. Then, the temperature is increased to 520℃-550℃ at a rate of 3℃ / min-5℃ / min and held for 15min-30min. Finally, it is cooled to room temperature at a rate of not less than 200℃ / s to obtain a self-lubricating porous copper-based oil-impregnated bearing material. The copper-tin binary alloy powder contains 8 wt.% to 20 wt.% tin.

2. The method for preparing the self-lubricating porous copper-based oil-impregnated bearing material as described in claim 1, characterized in that: In the material pretreatment step, the copper-tin binary alloy powder has a particle size of 150-300 mesh and a morphology of at least one of spherical, dendritic, or irregular shapes.

3. The method for preparing the self-lubricating porous copper-based oil-impregnated bearing material as described in claim 2, characterized in that: In the material pretreatment step, the reduction drying process is carried out in a hydrogen furnace. The reduction drying process is as follows: the reduction temperature is 200℃-400℃, the holding time is 1h-3h, the heating rate is 5℃ / min-20℃ / min, the reduction atmosphere is high-purity hydrogen or ammonia decomposition hydrogen, the atmosphere dew point is ≤-25℃, and the furnace is cooled to room temperature.

4. The method for preparing the self-lubricating porous copper-based oil-impregnated bearing material as described in claim 1, characterized in that: In the molding and sintering step, the molding pre-forming adopts a uniaxial limiting cold pressing method for molding, and the height compression ratio is controlled at 1.55-1.8 during the molding process.

5. The method for preparing the self-lubricating porous copper-based oil-impregnated bearing material as described in claim 1, characterized in that: In the molding and sintering process, the near-melting-point sintering treatment is carried out in a sintering furnace. The sintering process is as follows: first, the temperature is increased to 250℃-300℃ at a rate of 1℃ / min-5℃ / min, and held for 2h-4h; then, the temperature is increased to 700℃-775℃ at a rate of 5℃ / min-10℃ / min, and held for 1h-2.5h. The sintering atmosphere is high-purity hydrogen or ammonia decomposition hydrogen, with an atmosphere dew point ≤-25℃. The furnace is then cooled to room temperature.

6. The method for preparing the self-lubricating porous copper-based oil-impregnated bearing material as described in claim 1, characterized in that: In the borax impregnation treatment step, the concentration of the borax aqueous solution is 3wt.%-8wt.%, and ion clusters or single ions with a diameter ≤100nm are formed in the borax aqueous solution. The borax impregnation process is as follows: first, impregnate for 10min-20min under vacuum conditions with a relative vacuum degree of -0.1MPa--0.05MPa, then impregnate for 20min-30min under normal pressure conditions, and finally dry and cure by holding at 80℃-100℃ for 30min-60min.

7. The method for preparing the self-lubricating porous copper-based oil-impregnated bearing material as described in claim 1, characterized in that: In the gradient solution treatment step, the protective atmosphere is a vacuum degree ≤ 5 × 10⁻⁶. -2 Pa, under hydrogen or argon atmosphere, the atmosphere dew point is ≤-25℃; cooling to room temperature at a cooling rate of not less than 200℃ / s is carried out by water cooling, and the water tank temperature is controlled between 4℃ and 25℃ during the water cooling process.

8. A self-lubricating porous copper-based oil-impregnated bearing material prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the self-lubricating porous copper-based oil-impregnated bearing material as described in claim 8 in bearing materials for short-term impact high load or medium-low speed continuous high load.

10. A bearing, characterized in that: The bearing contains the self-lubricating porous copper-based oil-impregnated bearing material as described in claim 8. The bearing includes any one of the following: micro servo motor spindle bearing, automotive EPS torque sensor bearing, precision stamping die guide pillar bearing, and industrial robot joint reducer bearing. The absolute load of the bearing is ≤35N / mm², and the critical point of PV value is ≤3N / mm²·m / s.

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