A lead-free heavy-duty copper-tin-silicon sliding bearing material and its preparation method

Abstract

The application discloses a lead-free heavy-load copper-tin-silicon sliding bearing material and a preparation method thereof, and belongs to the technical field of bearing alloy materials. The lead-free heavy-load copper-tin-silicon sliding bearing material comprises tin 10 wt.%, silicon 2 wt.%-6 wt.% and the balance of copper in terms of mass percentage. The sliding bearing material only contains three elements of copper, tin and silicon, has simple composition and does not contain lead element, and the obtained bearing material is non-toxic and friendly to the environment. The material is prepared by adopting a spark plasma sintering process, powder particles are directly heated by pulse current, the surface of the particles is activated by a spark plasma, rapid densification sintering can be realized at a lower temperature, grain growth, Sn element segregation and Si phase coarsening are effectively inhibited, and the density, mechanical properties and wear resistance of the bearing are significantly improved, and the process has the advantages of energy saving and high efficiency.

Description

Technical Field

[0001] This invention belongs to the technical field of bearing alloy materials, specifically relating to a lead-free heavy-duty copper-tin-silicon sliding bearing material and its preparation method. Background Technology

[0002] Bearings, as key components in transmission machinery systems, are widely used in various mechanical equipment, undertaking the important tasks of supporting rotating parts and reducing friction and wear. Based on the nature of friction, bearings can be divided into sliding bearings and rolling bearings. Sliding bearings, due to their surface contact form, have high load-bearing capacity and excellent impact resistance and vibration absorption performance, smooth operation, and a simple and compact structure. They offer significant advantages in high-speed, high-precision, and heavy-load applications. By providing necessary support and reducing friction, sliding bearings can significantly reduce energy loss, improve the overall operating efficiency and performance of equipment, and also help extend the service life of equipment. Currently, sliding bearings are widely used in heavy-duty mechanical equipment such as automotive engine connecting rod crankshafts, marine diesel engines, multi-roll rolling mills, steam turbine generators, hydroelectric generators, and aero engines.

[0003] However, with the rapid development of modern industrial technology, especially in fields such as aerospace, energy equipment, and precision machinery, the requirements for mechanical equipment are becoming increasingly stringent. Sliding bearings need to withstand higher loads and adapt to more complex working environments. Furthermore, in accordance with new green and environmentally friendly requirements, the selection of materials must also meet requirements such as lead-free production, which places even higher demands on the materials used in sliding bearings.

[0004] Copper-based sliding bearing materials hold an irreplaceable position in the field of high-speed, heavy-duty engines due to their excellent load-bearing capacity and high fatigue strength. Among them, copper-lead alloys are the most important copper alloy bearing materials. Copper-lead alloys are widely used in heavy-duty sliding bearings due to their suitable hardness, high load-bearing capacity, and high fatigue strength. With the continuous increase in the external load of heavy-duty sliding bearings and the trend towards compact and miniaturized structural designs, the requirements for the load-bearing capacity of materials are becoming increasingly stringent. A typical representative of copper-lead alloys is CuSn. 10 Pb 10 For example, if copper-lead alloys operate for extended periods under conditions close to or exceeding their ultimate load-bearing capacity, they are prone to catastrophic accidents such as bearing burnout or bearing failure, which could lead to the complete engine or transmission system jamming and scrapping. The dangers are self-evident.

[0005] Furthermore, lead has always been an important reinforcing component in copper-based sliding bearing materials. Its addition helps reduce friction and wear, and improves bearing operating efficiency. Currently, both copper-lead and tin-based materials commonly used in heavy-duty sliding bearings contain lead. To improve the shaft embedding, compliance, and anti-adhesion properties of these bearing materials, the surface is often electroplated with a binary (PbSn) alloy containing up to 90% lead. 10 ) or ternary (PbSn) 10 Coatings of Cu2). Although lead plays an important role in copper-based sliding bearing materials, such as reducing friction, preventing adhesion, and improving machinability, its use poses a significant threat to the human environment due to the highly toxic nature of lead and its compounds. Excessive lead content and surface lead plating in copper-lead bearing materials fail to meet the stringent requirements of current environmental standards. Therefore, lead-free materials have become a hot research topic in copper-based sliding bearing materials.

[0006] Furthermore, advanced manufacturing processes are also a key factor in achieving high-performance lead-free bearing materials. Traditional sintering methods (such as conventional hot pressing and vacuum hot pressing) suffer from problems such as long sintering cycles, high temperatures, easy grain growth, and severe elemental segregation, which are detrimental to obtaining bearing materials with uniform microstructure and excellent performance. In recent years, spark plasma sintering (SPS) technology has attracted widespread attention in the preparation of high-performance metals and composite materials due to its advantages such as fast sintering rate, low sintering temperature, and effective suppression of grain coarsening and compositional segregation. This technology directly heats powder particles with pulsed current and activates the particle surface using arc plasma, achieving densification in a short time and significantly improving the mechanical properties and microstructure density of the material.

[0007] Therefore, developing a lead-free heavy-duty copper-based sliding bearing material that is green and environmentally friendly and prepared using advanced processes such as SPS can not only meet the needs of heavy-duty operation, but also effectively solve the environmental pollution and process limitations of traditional copper-lead bearing materials. It is one of the key technologies that urgently need to be broken through in the field of bearing materials. Summary of the Invention

[0008] In view of the above-mentioned prior art, the present invention provides a lead-free heavy-duty copper-tin-silicon sliding bearing material and its preparation method, so as to solve the technical problem that existing lead-containing sliding bearing materials are prone to adverse effects on the human living environment.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is to provide a lead-free heavy-duty copper-tin-silicon sliding bearing material, comprising the following components by mass percentage: 10 wt.% tin, 2 wt.% to 6 wt.% silicon, and the balance being copper.

[0010] Based on the above technical solution, the present invention can be further improved as follows.

[0011] Furthermore, the lead-free heavy-duty copper-tin-silicon sliding bearing material comprises the following components by mass percentage: 10 wt.% tin, 4 wt.% silicon, and the balance being copper.

[0012] This invention also discloses a method for preparing the above-mentioned lead-free heavy-duty copper-tin-silicon sliding bearing material, comprising the following steps:

[0013] S1: Copper powder, tin powder and silicon powder are ball-milled and mixed in an inert atmosphere to obtain composite powder;

[0014] S2: Load the mixed powder into the mold and press it with a pressure of 1-2 kPa for 5-15 minutes;

[0015] S3: The pressed powder is placed in a spark plasma sintering furnace along with the mold for sintering. The sintering program is to raise the furnace temperature to 650-700℃ at a heating rate of 50-100℃ / min, and adjust the sintering pressure to 25-35MPa. The temperature and pressure are held for 8-15 minutes, and then the powder is cooled to room temperature with the furnace to obtain the final product.

[0016] Furthermore, the copper and tin powders have a particle size of 300 mesh, and the silicon powder has a particle size of 500 nm.

[0017] Furthermore, the ball milling mixing method in S1 is as follows: copper powder, tin powder and silicon powder are added to the ball milling jar, then stainless steel grinding balls and process control agent are added, and then the air in the ball milling jar is replaced with inert gas. Then, the mixture is ball milled at 300 rpm for 20 hours, then vacuum dried and passed through a 100-mesh sieve to obtain composite powder. The mass ratio of the added stainless steel grinding balls to the powder is 5:1, and the stainless steel grinding balls include stainless steel grinding balls with diameters of 6 mm and 3 mm.

[0018] Furthermore, the process control agent is anhydrous ethanol; the inert gas is argon.

[0019] Furthermore, the mold is a graphite mold, and its inner wall is lined with carbon paper.

[0020] Furthermore, the pressure in S2 is 1 kPa, and the pressing time is 10 min.

[0021] Furthermore, the final temperature in S3 is 670℃, the sintering pressure is 30MPa, and the holding time is 10min.

[0022] The beneficial effects of this invention are:

[0023] 1. The sliding bearing material in this invention contains only three elements: copper, tin, and silicon. Its composition is simple, it does not contain lead, and the resulting bearing material is non-toxic and environmentally friendly.

[0024] 2. The copper-tin-silicon bearing material of this invention uses a copper-tin alloy as a base and adds a hard component, silicon, to the base. The introduction of silicon effectively reduces tin precipitation, and by controlling the silicon particle size, uniformly distributed silicon clusters can be formed in the bearing material. The presence of silicon clusters not only effectively improves the strength and hardness of the material (the resulting bearing material has a compressive strength of 1100 MPa and a Young's modulus of 125 GPa), but also effectively slows down the cutting action of the grinding pair on the surface of the bearing material, thereby reducing adhesive wear and improving the wear resistance of the bearing material (average coefficient of friction is 0.26, average wear rate is 1.5*10). -3 mm 3 ·N -1 ·m -1 ).

[0025] 3. This invention uses an advanced discharge plasma sintering process to prepare the material. The powder particles are directly heated by pulsed current and the particle surface is activated by discharge plasma. Rapid densification sintering can be achieved at a lower temperature, which effectively inhibits grain growth, Sn element segregation and Si phase coarsening, significantly improves the density, mechanical properties and wear resistance of the bearing, and has the advantages of energy saving and high efficiency. Attached Figure Description

[0026] Figure 1 SEM images of bearing materials prepared using silicon powder with different particle sizes. Detailed Implementation

[0027] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0028] Example 1

[0029] A lead-free heavy-duty copper-tin-silicon sliding bearing material comprises the following components by mass percentage: 10 wt.% tin, 4 wt.% silicon, and the balance being copper.

[0030] The lead-free heavy-duty copper-tin-silicon sliding bearing material in this embodiment is prepared through the following steps:

[0031] S1: Copper powder, tin powder, and silicon powder are added to a stainless steel ball mill jar, wherein the particle size of copper powder and tin powder is 300 mesh, and the particle size of silicon powder is 500 nm; then stainless steel grinding balls and anhydrous ethanol as a process control agent are added, the mass ratio of stainless steel grinding balls to powder is 5:1, the stainless steel grinding balls used include stainless steel grinding balls with diameters of 6 mm and 3 mm (1:1), and the liquid-to-powder ratio of anhydrous ethanol to powder is 1 mL: 1 g; then the air in the ball mill jar is replaced with argon gas, and then the mixture is ball-milled at 300 rpm for 20 h; then the ball-milled mixture is dried in a vacuum drying oven for 6 h, and then passed through a 100-mesh sieve to obtain composite powder;

[0032] S2: Load 35g of mixed powder into a graphite mold with a diameter of 30mm. The inner wall of the graphite mold is separated by carbon paper. Then, use an MS05-100 powder pre-compressor to pre-compress the powder in the mold for 10 minutes under a pressure of 1KPa to compact the powder.

[0033] S3: The pressed powder is placed in a spark plasma sintering furnace along with the mold for sintering. The sintering program is to raise the furnace temperature to 670°C at a heating rate of 60°C / min, adjust the sintering pressure to 30MPa, hold the temperature and pressure for 10 minutes, and then cool it to room temperature with the furnace to obtain the lead-free heavy-duty copper-tin-silicon sliding bearing material.

[0034] Example 2

[0035] A lead-free heavy-duty copper-tin-silicon sliding bearing material comprises the following components by mass percentage: 10 wt.% tin, 2 wt.% silicon, and the balance being copper.

[0036] The lead-free heavy-duty copper-tin-silicon sliding bearing material in this embodiment is prepared through the following steps:

[0037] S1: Copper powder, tin powder, and silicon powder are added to a stainless steel ball mill jar, wherein the particle size of copper powder and tin powder is 300 mesh, and the particle size of silicon powder is 500 nm; then stainless steel grinding balls and anhydrous ethanol as a process control agent are added, the mass ratio of stainless steel grinding balls to powder is 5:1, the stainless steel grinding balls used include stainless steel grinding balls with diameters of 6 mm and 3 mm (1:1), and the liquid-to-powder ratio of anhydrous ethanol to powder is 1 mL: 1 g; then the air in the ball mill jar is replaced with argon gas, and then the mixture is ball-milled at 300 rpm for 20 h; then the ball-milled mixture is dried in a vacuum drying oven for 6 h, and then passed through a 100-mesh sieve to obtain composite powder;

[0038] S2: Load 35g of mixed powder into a graphite mold with a diameter of 30mm. The inner wall of the graphite mold is separated by carbon paper. Then, use an MS05-100 powder pre-compressor to pre-compress the powder in the mold for 5 minutes under a pressure of 2KPa to compact the powder.

[0039] S3: The pressed powder is placed in a spark plasma sintering furnace along with the mold for sintering. The sintering program is to raise the furnace temperature to 650°C at a heating rate of 50°C / min, and adjust the sintering pressure to 35MPa. The temperature and pressure are held for 15 minutes, and then the furnace is cooled to room temperature to obtain lead-free heavy-duty copper-tin-silicon sliding bearing material.

[0040] Example 3

[0041] A lead-free heavy-duty copper-tin-silicon sliding bearing material comprises the following components by mass percentage: 10 wt.% tin, 6 wt.% silicon, and the balance being copper.

[0042] The lead-free heavy-duty copper-tin-silicon sliding bearing material in this embodiment is prepared through the following steps:

[0043] S1: Copper powder, tin powder, and silicon powder are added to a stainless steel ball mill jar, wherein the particle size of copper powder and tin powder is 300 mesh, and the particle size of silicon powder is 500 nm; then stainless steel grinding balls and anhydrous ethanol as a process control agent are added, the mass ratio of stainless steel grinding balls to powder is 5:1, the stainless steel grinding balls used include stainless steel grinding balls with diameters of 6 mm and 3 mm (1:1), and the liquid-to-powder ratio of anhydrous ethanol to powder is 1 mL: 1 g; then the air in the ball mill jar is replaced with argon gas, and then the mixture is ball-milled at 300 rpm for 20 h; then the ball-milled mixture is dried in a vacuum drying oven for 6 h, and then passed through a 100-mesh sieve to obtain composite powder;

[0044] S2: Load 35g of mixed powder into a graphite mold with a diameter of 30mm. The inner wall of the graphite mold is separated by carbon paper. Then, use an MS05-100 powder pre-compressor to pre-compress the powder in the mold for 15 minutes under a pressure of 1KPa to compact the powder.

[0045] S3: The pressed powder is placed in a spark plasma sintering furnace along with the mold for sintering. The sintering program is to raise the furnace temperature to 700°C at a heating rate of 100°C / min, and adjust the sintering pressure to 25MPa. The temperature and pressure are held for 8 minutes, and then the furnace is cooled to room temperature to obtain lead-free heavy-duty copper-tin-silicon sliding bearing material.

[0046] The lead-free heavy-duty copper-tin-silicon sliding bearing materials prepared in Examples 1 to 3 have similar properties. Taking the bearing material in Example 1 as an example, its properties will be explained.

[0047] The hardness of the bearing material in Example 1 was measured using a Vickers hardness tester, yielding a Vickers hardness of 210 HV. The compressive strength of the bearing material was measured using a universal testing machine, finding it to be 1100 MPa (loading rate 2 mm / min). The Young's modulus of the bearing material was calculated to be 125 GPa using the Oliver-Pharr method. The bearing material in Example 1 was tested using an HT-1000 friction and wear testing machine under dry friction and ambient temperature conditions. GCr15 steel balls were used as the wear material. Under high load (50 N) and high speed (600 r / min) friction conditions, the average coefficient of friction of the bearing material was measured to be 0.26, and the average wear rate was 1.5 × 10⁻⁶. -3 mm 3 ·N -1 ·m -1 The results show that the bearing material prepared by the method of this invention has good friction reduction and wear resistance.

[0048] Example 4

[0049] A lead-free heavy-duty copper-tin-silicon sliding bearing material comprises the following components by mass percentage: 10 wt.% tin, 4 wt.% silicon, and the balance being copper.

[0050] The lead-free heavy-duty copper-tin-silicon sliding bearing material in this embodiment is prepared through the following steps:

[0051] S1: Copper powder, tin powder, and silicon powder are added to a stainless steel ball mill jar, wherein the particle size of copper powder and tin powder is 300 mesh, and the particle size of silicon powder is 10 μm; then stainless steel grinding balls and anhydrous ethanol as a process control agent are added, the mass ratio of the added stainless steel grinding balls to the powder is 5:1, the stainless steel grinding balls used include stainless steel grinding balls with diameters of 6 mm and 3 mm (1:1), and the liquid-to-powder ratio of the added anhydrous ethanol to the powder is 1 mL: 1 g; then the air in the ball mill jar is replaced with argon gas, and then the mixture is ball-milled at 300 rpm for 20 h; then the ball-milled mixture is dried in a vacuum drying oven for 6 h, and then passed through a 100-mesh sieve to obtain composite powder;

[0052] S2: Load 35g of mixed powder into a graphite mold with a diameter of 30mm. The inner wall of the graphite mold is separated by carbon paper. Then, use an MS05-100 powder pre-compressor to pre-compress the powder in the mold for 10 minutes under a pressure of 1KPa to compact the powder.

[0053] S3: The pressed powder is placed in a spark plasma sintering furnace along with the mold for sintering. The sintering program is to raise the furnace temperature to 650°C at a heating rate of 60°C / min, adjust the sintering pressure to 30MPa, hold the temperature and pressure for 10 minutes, and then cool it to room temperature with the furnace to obtain lead-free heavy-duty copper-tin-silicon sliding bearing material.

[0054] Example 5

[0055] A lead-free heavy-duty copper-tin-silicon sliding bearing material comprises the following components by mass percentage: 10 wt.% tin, 4 wt.% silicon, and the balance being copper.

[0056] The lead-free heavy-duty copper-tin-silicon sliding bearing material in this embodiment is prepared through the following steps:

[0057] S1: Copper powder, tin powder, and silicon powder are added to a stainless steel ball mill jar, wherein the particle size of copper powder and tin powder is 300 mesh, and the particle size of silicon powder is 500 nm; then stainless steel grinding balls and anhydrous ethanol as a process control agent are added, the mass ratio of stainless steel grinding balls to powder is 5:1, the stainless steel grinding balls used include stainless steel grinding balls with diameters of 6 mm and 3 mm (1:1), and the liquid-to-powder ratio of anhydrous ethanol to powder is 1 mL: 1 g; then the air in the ball mill jar is replaced with argon gas, and then the mixture is ball-milled at 300 rpm for 20 h; then the ball-milled mixture is dried in a vacuum drying oven for 6 h, and then passed through a 100-mesh sieve to obtain composite powder;

[0058] S2: Load 35g of mixed powder into a graphite mold with a diameter of 30mm. The inner wall of the graphite mold is separated by carbon paper. Then, use an MS05-100 powder pre-compressor to pre-compress the powder in the mold for 10 minutes under a pressure of 1KPa to compact the powder.

[0059] S3: The pressed powder is placed in a spark plasma sintering furnace along with the mold for sintering. The sintering program is to raise the furnace temperature to 650°C at a heating rate of 60°C / min, adjust the sintering pressure to 30MPa, hold the temperature and pressure for 10 minutes, and then cool it to room temperature with the furnace to obtain lead-free heavy-duty copper-tin-silicon sliding bearing material.

[0060] Example 6

[0061] A lead-free heavy-duty copper-tin-silicon sliding bearing material comprises the following components by mass percentage: 10 wt.% tin, 4 wt.% silicon, and the balance being copper.

[0062] The lead-free heavy-duty copper-tin-silicon sliding bearing material in this embodiment is prepared through the following steps:

[0063] S1: Copper powder, tin powder, and silicon powder are added to a stainless steel ball mill jar, wherein the particle size of copper powder and tin powder is 300 mesh, and the particle size of silicon powder is 100 nm; then stainless steel grinding balls and anhydrous ethanol as a process control agent are added, the mass ratio of the added stainless steel grinding balls to the powder is 5:1, the stainless steel grinding balls used include stainless steel grinding balls with diameters of 6 mm and 3 mm (1:1), and the liquid-to-powder ratio of the added anhydrous ethanol to the powder is 1 mL: 1 g; then the air in the ball mill jar is replaced with argon gas, and then the mixture is ball-milled at 300 rpm for 20 h; then the ball-milled mixture is dried in a vacuum drying oven for 6 h, and then passed through a 100-mesh sieve to obtain composite powder;

[0064] S2: Load 35g of mixed powder into a graphite mold with a diameter of 30mm. The inner wall of the graphite mold is separated by carbon paper. Then, use an MS05-100 powder pre-compressor to pre-compress the powder in the mold for 10 minutes under a pressure of 1KPa to compact the powder.

[0065] S3: The pressed powder is placed in a spark plasma sintering furnace along with the mold for sintering. The sintering program is to raise the furnace temperature to 650°C at a heating rate of 60°C / min, adjust the sintering pressure to 30MPa, hold the temperature and pressure for 10 minutes, and then cool it to room temperature with the furnace to obtain lead-free heavy-duty copper-tin-silicon sliding bearing material.

[0066] SEM tests were performed on the lead-free heavy-duty copper-tin-silicon sliding bearing materials prepared in Examples 4-6, and the results are as follows: Figure 1 As shown, Figure 1 Figures a, b, and c show SEM images of bearing materials prepared with silicon powder of different particle sizes, and a1, a2, and a2 represent test results at different scales. The figures show that as the silicon particle size gradually decreases, tin precipitation decreases, while the number of silicon clusters increases significantly. An appropriate amount of silicon clusters is beneficial for friction reduction and wear resistance, while excessive silicon clusters weaken this effect. Therefore, the bearing material prepared with silicon particles of 500 nm exhibits the best balance between microstructure uniformity and strength / hardness, while also possessing good friction reduction and wear resistance.

[0067] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. A lead-free heavy duty copper-tin-silicon bearing material, characterized in that, 10 wt.% of tin, 4 wt.% of silicon, and the balance of copper. The lead-free heavy-load copper-tin-silicon sliding bearing material is prepared by the following steps: S1: copper powder, tin powder and silicon powder are mixed in a ball mill in an inert atmosphere to obtain a composite powder; the particle size of the copper powder and the tin powder is 300 mesh, and the particle size of the silicon powder is 500 nm; S2: the mixed powder is loaded into a mold and pressed at a pressure of 1-2 KPa for 5-15 min; S3: the pressed powder is placed in a discharge plasma sintering furnace with the mold, the sintering program is to raise the furnace temperature to 650-700℃ at a heating rate of 50-100℃ / min, and the sintering pressure is adjusted to 25-35 MPa, and the temperature and pressure are maintained for 8-15 min, and then the furnace is cooled to room temperature.

2. The lead-free heavy duty copper-tin-silicon bearing material of claim 1, wherein, 10 wt.% of tin, 4 wt.% of silicon, and the balance of copper.

3. The lead-free heavy duty copper-tin-silicon bearing material of claim 1, wherein, The ball milling method in S1 is as follows: the copper powder, the tin powder and the silicon powder are added into a ball mill tank, then stainless steel grinding balls and a process control agent are added, the air in the ball mill tank is replaced with an inert gas, then the ball mill is operated at a speed of 300 rpm for 20 h, then vacuum drying and passing through a 100 mesh screen are performed to obtain the composite powder; the mass ratio of the stainless steel grinding balls to the powder is 5:1, and the stainless steel grinding balls include stainless steel grinding balls with diameters of 6 mm and 3 mm.

4. The lead-free heavy duty copper-tin-silicon bearing material of claim 3, wherein: The process control agent is anhydrous ethanol, and the inert gas is argon.

5. The lead-free heavy duty copper-tin-silicon bearing material of claim 1 wherein: The mold is a graphite mold, and the inner wall of the mold is paved with carbon paper.

6. The lead-free heavy duty copper-tin-silicon bearing material of claim 5, wherein: The pressure of the pressing in S2 is 1 KPa, and the pressing time is 10 min.

7. The lead-free heavy duty copper-tin-silicon bearing material of claim 5, wherein: The final temperature of the temperature rising in S3 is 670℃, the sintering pressure is 30 MPa, and the temperature and pressure maintaining time is 10 min.

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