A lead-free copper-based self-lubricating composite material and a preparation method thereof

Abstract

The application discloses a lead-free copper-based self-lubricating composite material and a preparation method thereof, and relates to the technical field of self-lubricating bearing materials.According to the weight percentage, the lead-free copper-based self-lubricating composite material comprises the following components: Sn 5% to 10%, Si 0.5% to 5%, selenium compound 1% to 6%, and the balance of Cu, wherein the selenium compound is selected from one or a combination of two of molybdenum diselenide and niobium diselenide.The application realizes significant improvement of the comprehensive performance of the lead-free copper-based self-lubricating composite material through material system design, and is outstanding in mechanical properties and service reliability, can effectively prolong the service cycle of the copper-based sliding bearing, has higher performance and environmental friendliness compared with traditional lead-containing materials, and is suitable for bearing application under extreme working conditions.

Description

Technical Field

[0001] This invention relates to the field of self-lubricating bearing materials, and in particular to a lead-free copper-based self-lubricating composite material and its preparation method. Background Technology

[0002] As an indispensable key component in mechanical equipment systems, sliding bearings primarily function to support the stable operation of rotating mechanisms, reduce frictional resistance between moving parts, and minimize energy loss. They are widely used in numerous industrial fields such as engineering machinery, aerospace, precision machine tools, and rail transportation. With the continuous iteration of modern industrial technology, equipment operating conditions are increasingly evolving towards high temperature, high pressure, high load, and complex and harsh environments. This places more stringent demands on the service durability, extreme condition adaptability, and self-lubricating capabilities of sliding bearings.

[0003] In terms of lubrication methods, traditional sliding bearings rely heavily on liquid lubricants to reduce friction. However, in high-temperature environments, liquid lubricants are prone to volatilization, oxidation, or carbonization, leading to lubrication film failure. In vacuum conditions, the fluidity and adhesion of liquid lubricants decrease significantly, and continuous replenishment is difficult. In high-dust or high-impurity environments, lubricants are easily contaminated, further exacerbating abrasive wear on the friction pair. All of these problems can lead to bearing lubrication failure, causing a sharp increase in the coefficient of friction, accelerated wear rate, and in severe cases, even bearing seizure and structural damage, directly affecting the operational reliability and service life of the entire equipment. Therefore, developing sliding bearing materials with self-lubricating capabilities and adaptability to extreme operating conditions has become a crucial area requiring breakthroughs in tribology and materials engineering.

[0004] In the field of bearing materials, the traditional copper-based bearing materials widely used in industry are mainly lead-containing systems. A typical example is the copper-tin-lead alloy with the grade CuSn10Pb10, whose lead content is usually not less than 10 wt%. This type of material has certain friction-reducing properties and anti-seizure capabilities due to the lubricating film formed by the lead phase during friction, and can meet basic usage requirements under medium and low loads and normal operating conditions.

[0005] Against this backdrop, the development of high-performance lead-free copper-based self-lubricating composite materials to replace traditional lead-containing materials, while simultaneously meeting the requirements of excellent tribological properties and service reliability, not only has significant engineering application value but also demonstrates broad market prospects. Summary of the Invention

[0006] The purpose of this invention is to provide a lead-free copper-based self-lubricating composite material and its preparation method, so as to solve the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] One of the technical solutions of this invention is to provide a lead-free copper-based self-lubricating composite material, comprising a matrix component, a reinforcing component, and a lubricating component; wherein the matrix component is Cu; the reinforcing component is Sn and Si; and the lubricating component is a selenide.

[0009] The lead-free copper-based self-lubricating composite material comprises the following components by mass percentage: Sn 5%~10%, Si 0.5%~5%, selenide 1%~6%, and the balance being Cu;

[0010] The selenide is selected from one or a combination of two of molybdenum diselenide and niobium diselenide.

[0011] This invention relates to a lead-free copper-based self-lubricating composite material. Copper serves as the matrix, providing structural support for the reinforcing components (tin and silicon) and the lubricating components (selenides), ensuring that the material does not fail under high loads. The tin-silicon reinforcing components enhance the matrix hardness and load-bearing capacity, preventing the lubricating components from being squeezed out due to an overly soft matrix and ensuring the continued effectiveness of the lubricating film. Furthermore, the addition of silicon significantly refines the matrix grains, further improving the material's hardness, load-bearing capacity, and wear resistance. The selenide lubricating components not only reduce friction and wear and extend the material's service life but also reduce the softening of the reinforcing components due to frictional heat (frictional heat weakens the reinforcing effect). Simultaneously, they play an anti-wear and friction-reducing role during friction, improving the tribological properties of the material.

[0012] The second technical solution of the present invention provides a method for preparing the above-mentioned lead-free copper-based self-lubricating composite material, comprising the following steps:

[0013] According to the stoichiometric ratio of chemical composition, the raw material powder is weighed and ball-milled to obtain mechanically mixed powder;

[0014] The mechanically mixed powder is pressed into a blank to obtain a green body;

[0015] The blank is sintered to obtain the lead-free copper-based self-lubricating composite material.

[0016] As a further preferred embodiment of the present invention, the ball-to-material ratio in the ball milling process is 3:1 to 5:1, and the ball milling time is 6 to 8 hours.

[0017] As a further preferred embodiment of the present invention, the pressing is performed by cold pressing.

[0018] As a further preferred embodiment of the present invention, the pressure of the cold pressing is 300~500MPa.

[0019] As a further preferred embodiment of the present invention, the sintering treatment temperature is 700~850℃ and the time is 3~5h;

[0020] As a further preferred embodiment of the present invention, the process control agent used in the ball milling process is kerosene, which may be selected as aerospace kerosene; the amount of the process control agent added is 1 to 2 wt.% of the total mass of the raw material powder.

[0021] The third technical solution of this invention provides the application of the above-mentioned lead-free copper-based self-lubricating composite material in the field of sliding bearings.

[0022] The fourth technical solution of the present invention provides a lead-free copper-based sliding bearing, which is prepared using the above-mentioned lead-free copper-based self-lubricating composite material.

[0023] The present invention discloses the following technical effects:

[0024] This invention provides a lead-free copper-based self-lubricating composite material. Through material system design, the overall performance of the lead-free copper-based self-lubricating composite material is significantly improved, with outstanding performance in mechanical properties and service reliability.

[0025] The material of this invention uses a copper-tin alloy as the matrix. Thanks to the good processing performance of the matrix, it can ensure that the hard phase silicon is uniformly dispersed in the system and avoid performance fluctuations caused by silicon particle agglomeration. The introduction of silicon can effectively refine the alloy grains, greatly improve the wear resistance and fatigue resistance of the material, and lay the foundation for the material to adapt to high-load working conditions.

[0026] Through a precise sintering process, this invention can build a good interfacial bond between silicon particles and copper-tin matrix, which not only ensures the high hardness and high load-bearing capacity of the material, but also effectively avoids the risk of brittle fracture caused by poor interfacial bonding, further enhancing the overall service stability of the material and enabling it to maintain reliable performance under complex working conditions.

[0027] This invention significantly improves the friction-reducing and wear-resistant capabilities of materials and the service life of bearings through innovative lubrication component design. The selected selenides, such as molybdenum diselenide and niobium diselenide, have unique layered crystal structures that easily undergo interlayer slippage during friction. This allows for the rapid formation of a continuous and stable solid lubricating film on the friction surface, transforming traditional metal-to-metal direct friction into low-resistance friction within the lubricating film. This not only significantly reduces energy loss but also avoids adhesive wear, greatly improving the wear resistance of the material. Consequently, it effectively extends the service life of copper-based sliding bearings and reduces equipment maintenance frequency and costs.

[0028] The preparation process of this invention utilizes powder metallurgy technology, which has the advantages of simple process and controllable cost. It avoids material waste and processing losses in traditional casting, forging, and rolling processes. By flexibly adjusting sintering parameters, the hardness and strength of the material can be optimized. In addition, this material system is environmentally friendly, contains no harmful components, meets the requirements of lead-free and green manufacturing, and has good industrialization prospects and economic benefits. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The metallographic structure of the sintered sample obtained in Example 1 of this invention. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0032] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0034] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0035] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0036] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0037] Example 1

[0038] This embodiment provides a lead-free copper-based self-lubricating composite material, the composition of which is shown in Table 1:

[0039] Table 1

[0040]

[0041] The specific preparation process is as follows:

[0042] (1) Ball milling: Weigh copper powder, tin powder, silicon powder, molybdenum diselenide powder and niobium diselenide powder according to the above mass percentages, mix them and add aviation kerosene accounting for 1 wt.% of the total powder weight as a process control agent; load the mixed powder and grinding balls into a ball mill jar (the mass ratio of grinding balls to mixed powder is 3:1), and ball mill at a speed of 400 r / min for 6 h to obtain uniform mechanical alloyed powder.

[0043] (2) Press molding: Weigh an appropriate amount of the above alloy powder and place it in a mold. Press it under a pressure of 500MPa and obtain the blank after demolding.

[0044] (3) Sintering treatment: The blank is placed in a vacuum high-temperature furnace, sintered at 700°C and held for 5 hours, and then cooled with the furnace to finally obtain the sintered sample of lead-free copper-based self-lubricating composite material.

[0045] Figure 1 The image shows the metallographic structure of the sintered sample obtained in Example 1 of this invention. As can be seen from the image, uniformly distributed fine selenides are present, with no obvious aggregation or coarsening. Furthermore, elements such as silicon and tin are dissolved in the copper matrix, further strengthening the alloy matrix and contributing to improved overall material performance.

[0046] Example 2

[0047] This embodiment provides a lead-free copper-based self-lubricating composite material, the composition of which is shown in Table 2:

[0048] Table 2

[0049]

[0050] The specific preparation process is as follows:

[0051] (1) Ball milling: Weigh copper powder, tin powder, silicon powder, molybdenum diselenide powder and niobium diselenide powder according to the above mass percentages, mix them and add aviation kerosene accounting for 1 wt.% of the total powder weight as a process control agent; load the mixed powder and grinding balls into a ball mill jar (the mass ratio of grinding balls to mixed powder is 3:1), and ball mill at a speed of 400 r / min for 6 h to obtain uniform mechanical alloyed powder.

[0052] (2) Press molding: Weigh an appropriate amount of the above alloy powder and place it in a mold. Press it under a pressure of 500MPa and obtain the blank after demolding.

[0053] (3) Sintering treatment: The blank is placed in a vacuum high-temperature furnace, sintered at 750°C and held for 3.5 hours, and then cooled with the furnace to finally obtain the sintered sample of lead-free copper-based self-lubricating composite material.

[0054] Example 3

[0055] This embodiment provides a lead-free copper-based self-lubricating composite material, the composition of which is shown in Table 3:

[0056] Table 3

[0057]

[0058] The specific preparation process is as follows:

[0059] (1) Ball milling: Weigh copper powder, tin powder, silicon powder and molybdenum diselenide powder according to the above mass percentages, mix them and add aviation kerosene accounting for 1 wt.% of the total powder weight as a process control agent; load the mixed powder and grinding balls into a ball mill jar (the mass ratio of grinding balls to mixed powder is 3:1), and ball mill at a speed of 400 r / min for 6 h to obtain uniform mechanical alloyed powder.

[0060] (2) Press molding: Weigh an appropriate amount of the above alloy powder and place it in a mold. Press it under a pressure of 500MPa and obtain the blank after demolding.

[0061] (3) Sintering treatment: The blank is placed in a vacuum high temperature furnace, sintered at 800℃ and held for 4.5h, and then cooled with the furnace to finally obtain the sintered sample of lead-free copper-based self-lubricating composite material.

[0062] Example 4

[0063] This embodiment provides a lead-free copper-based self-lubricating composite material, the composition of which is shown in Table 4:

[0064] Table 4

[0065]

[0066] The specific preparation process is as follows:

[0067] (1) Ball milling: Weigh copper powder, tin powder, silicon powder and niobium diselenide powder according to the above mass percentages, mix them and add aviation kerosene accounting for 1 wt.% of the total powder weight as a process control agent; load the mixed powder and grinding balls into a ball mill jar (the mass ratio of grinding balls to mixed powder is 3:1), and ball mill at a speed of 400 r / min for 6 h to obtain uniform mechanical alloyed powder.

[0068] (2) Press molding: Weigh an appropriate amount of the above alloy powder and place it in a mold. Press it under a pressure of 500MPa and obtain the blank after demolding.

[0069] (3) Sintering treatment: The blank is placed in a vacuum high-temperature furnace, sintered at 850°C and held for 3 hours, and then cooled with the furnace to finally obtain the sintered sample of lead-free copper-based self-lubricating composite material.

[0070] Example 5

[0071] This embodiment provides a lead-free copper-based self-lubricating composite material, the composition of which is shown in Table 5:

[0072] Table 5

[0073]

[0074] The specific preparation process is as follows:

[0075] (1) Ball milling: Weigh copper powder, tin powder, silicon powder, molybdenum diselenide powder and niobium diselenide powder according to the above mass percentages, mix them and add aviation kerosene accounting for 1 wt.% of the total powder weight as a process control agent; load the mixed powder and grinding balls into a ball mill jar (the mass ratio of grinding balls to mixed powder is 3:1), and ball mill at a speed of 400 r / min for 6 h to obtain uniform mechanical alloyed powder.

[0076] (2) Press molding: Weigh an appropriate amount of the above alloy powder and place it in a mold. Press it under a pressure of 500MPa and obtain the blank after demolding.

[0077] (3) Sintering treatment: The blank is placed in a vacuum high-temperature furnace, sintered at 820°C and held for 4 hours, and then cooled with the furnace to finally obtain the sintered sample of lead-free copper-based self-lubricating composite material.

[0078] Comparative Example 1

[0079] This comparative example provides a lead-free copper-based composite material, the composition of which is shown in Table 6:

[0080] Table 6

[0081]

[0082] The specific preparation process is as follows:

[0083] (1) Ball milling: Weigh copper powder, tin powder and silicon powder according to the above component mass percentages, mix them and add aviation kerosene accounting for 1 wt.% of the total powder weight as a process control agent; load the mixed powder and grinding balls (grinding balls to mixed powder mass ratio 3:1) into a ball mill jar, and ball mill in a ball mill at 400 r / min speed for 6 h to obtain uniform mechanical alloyed powder.

[0084] (2) Press molding: Weigh an appropriate amount of the above alloy powder and place it in a mold. Press it under a pressure of 500MPa and obtain the blank after demolding.

[0085] (3) Sintering treatment: The blank is placed in a vacuum high-temperature furnace, sintered at 700℃ and held for 5 hours, and then cooled with the furnace to finally obtain the sintered sample.

[0086] Comparative Example 2

[0087] This comparative example provides a lead-free copper-based composite material, the composition of which is shown in Table 7:

[0088] Table 7

[0089]

[0090] The specific preparation process is as follows:

[0091] (1) Ball milling: Weigh copper powder, tin powder, silicon powder, molybdenum diselenide powder and niobium diselenide powder according to the above component mass percentages, mix them and add aviation kerosene accounting for 1 wt.% of the total powder weight as a process control agent; load the mixed powder and grinding balls (grinding balls to mixed powder mass ratio 3:1) into a ball mill jar, and ball mill in a ball mill at a speed of 400 r / min for 6 h to obtain uniform mechanical alloyed powder.

[0092] (2) Press molding: Weigh an appropriate amount of the above alloy powder and place it in a mold. Press it under a pressure of 500MPa and obtain the blank after demolding.

[0093] (3) Sintering treatment: The blank is placed in a vacuum high-temperature furnace, sintered at 700℃ and held for 5 hours, and then cooled with the furnace to finally obtain the sintered sample.

[0094] Effect verification example

[0095] To verify the performance of the lead-free copper-based self-lubricating composite material of the present invention, a reciprocating friction testing machine and a Vickers hardness testing device were used to test the tribological and mechanical properties of the lead-free copper-based composite materials prepared in Examples 1-5 and Comparative Examples 1-2, as well as commercially available traditional lead-containing copper-based bearing materials (Cu10Sn10Pb).

[0096] Test samples: The composite materials of Examples 1-5 and Comparative Examples 1-2 and commercially available Cu10Sn10Pb materials were wire-cut into 10mm×15mm square samples;

[0097] Friction pair: GCr15 steel balls with a diameter of 7.938mm, a hardness of HRC61~66, and a surface roughness Ra<1.6μm are selected.

[0098] 1. Friction coefficient test

[0099] The friction coefficient test parameters are as follows: loading pressure 30N, reciprocating stroke 10mm, operating frequency 4Hz, test duration 30min; according to Calculate the coefficient of friction (μ), where F is the frictional force (unit: N) and P is the working pressure (unit: N).

[0100] 2. Wear Rate Test

[0101] Under the same working conditions as the friction coefficient test, the same test sample was subjected to at least two repeated friction tests to form two independent friction scratches. The wear volume (V, unit: mm³) of the scratches was measured by a three-dimensional profilometer, and the wear rate (W) was calculated according to the formula W=V / (P×S), where P is the normal load (unit: N) and S is the total sliding distance of the test (unit: m).

[0102] 3. Vickers hardness test

[0103] After grinding and polishing the sample, HV was used. 0.5 (Load 4.9N), hold pressure for 30s, test each group of samples ten times, remove outliers and take the average value as the final hardness result.

[0104] Table 8. Test results of hardness and tribological properties of different composite materials

[0105]

[0106] Test results show that, compared with commercially available Cu10Sn10Pb bearing materials, the lead-free copper-based self-lubricating composite material prepared in this invention exhibits significant advantages in overall performance, as detailed below:

[0107] In terms of mechanical properties, the Vickers hardness of the material of this invention is significantly higher than that of commercially available lead-containing materials. Specifically, the hardness value of Example 5 reaches 245 HV, far exceeding the 117 HV of commercially available Cu10Sn10Pb, indicating that the material of this invention possesses superior resistance to deformation and load-bearing capacity, and can adapt to higher load conditions.

[0108] In terms of tribological properties, the average coefficient of friction of the material of this invention is stable between 0.25 and 0.31, which is comparable to or even lower than that of commercially available materials, ensuring low resistance characteristics during operation; more importantly, its wear rate is significantly reduced: the wear rate of Example 1 is only 1.10 × 10⁻⁶. -4 mm 3 / (N•m), compared to commercially available materials (2.95×10 -4 mm 3 The wear resistance (N•m) decreased by more than 60%, demonstrating excellent wear resistance.

[0109] In summary, the material of this invention has the synergistic advantages of high hardness, low coefficient of friction, and low wear rate, which can effectively extend the service life of bearings, reduce the frequency of replacement, thereby reducing equipment maintenance costs and improving operational reliability, ensuring the safe operation of bearings under complex working conditions, and meeting the technical requirements of modern industry for lead-free, long-life bearing materials.

[0110] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a lead-free copper-based self-lubricating composite material, characterized in that, The lead-free copper-based self-lubricating composite material comprises the following components by mass percentage: Sn 5%~10%, Si 0.5%~5%, selenide 1%~6%, and the balance being Cu; The selenide is selected from one or a combination of two of molybdenum diselenide and niobium diselenide. The preparation method includes the following steps: According to the stoichiometric ratio of chemical composition, the raw material powder is weighed and ball-milled to obtain mechanically mixed powder; The mechanically mixed powder is pressed into a blank to obtain a green body; The blank is sintered to obtain the lead-free copper-based self-lubricating composite material. The sintering process is carried out at a temperature of 700~850℃ for 3~5 hours. The pressing and molding process employs cold pressing; the pressure of the cold pressing is 300~500MPa.

2. The method for preparing the lead-free copper-based self-lubricating composite material according to claim 1, characterized in that, The ball-to-material ratio for the ball milling process is 3:1 to 5:1, and the milling time is 6 to 8 hours.

3. The method for preparing the lead-free copper-based self-lubricating composite material according to claim 1, characterized in that, The process control agent used in the ball milling process is kerosene; the amount of the process control agent added is 1 to 2 wt.% of the total mass of the raw material powder.

4. The application of the lead-free copper-based self-lubricating composite material prepared by the method described in claim 1 in the field of sliding bearings.

5. A lead-free copper-based sliding bearing, characterized in that, The lead-free copper-based self-lubricating composite material is prepared by the preparation method of the lead-free copper-based self-lubricating composite material according to claim 1.

Images