Lead-free heavy-load copper-tin-silicon sliding bearing material and preparation method thereof

Abstract

The invention 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 the following components in percentage by mass: 10wt% of tin, 2wt%-6wt% of silicon and the balance of copper. The sliding bearing material only contains three elements of copper, tin and silicon, is simple in composition and free of lead element, and is non-toxic and environment-friendly. The material is prepared by adopting a spark plasma sintering process, powder particles are directly heated through pulse current, and the surfaces of the particles are activated through discharge plasma, so that rapid densification sintering can be realized at a relatively low temperature, grain growth, Sn element segregation and Si phase coarsening are effectively inhibited, and the compactness, the mechanical property and the wear resistance of the bearing are remarkably improved; and meanwhile, the process advantages of energy conservation and high efficiency are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of bearing alloy materials, and in particular relates to a lead-free heavy-load copper-tin-silicon sliding bearing material and a preparation method thereof. Background Art

[0002] As key components in mechanical transmission systems, bearings are widely used in various mechanical equipment, fulfilling the crucial task of supporting rotating parts and reducing friction and wear. Bearings can be categorized as sliding bearings or rolling bearings based on their frictional properties. Sliding bearings, due to their surface contact structure, offer high load-bearing capacity, excellent impact resistance and vibration absorption, smooth operation, and a simple and compact structure. These advantages make them particularly advantageous 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 extend its service life. Currently, sliding bearings are widely used in heavy-duty machinery and equipment, including automotive engine connecting rods and crankshafts, marine diesel engines, multi-roll steel mills, steam and hydroelectric generators, and aircraft engines.

[0003] However, with the rapid development of modern industrial technology, particularly in aerospace, energy equipment, precision machinery and other fields, the requirements for mechanical equipment are becoming increasingly stringent. Sliding bearings are required to withstand higher loads and adapt to more complex working environments. At the same time, new environmental protection requirements also require the selection of materials that meet green environmental protection requirements such as lead-free, which places higher demands on the materials used in sliding bearings.

[0004] Copper-based sliding bearing materials have an irreplaceable position in the field of high-speed and heavy-load engines due to their excellent load-bearing capacity and high fatigue strength. Among them, copper-lead alloy is the most important copper alloy bearing material. Copper-lead alloy has been widely used in the field of heavy-load sliding bearings due to its suitable hardness, large load-bearing capacity and high fatigue strength. With the continuous increase in the external load of heavy-load sliding bearings and the development of structural design towards compact miniaturization, the requirements for the load-bearing capacity of the materials are more stringent. Take CuSn, a typical representative of copper-lead alloys, as an example. 10 Pb 10 For example, if copper-lead alloy works for a long time under conditions close to or exceeding its ultimate load-bearing capacity, it will easily cause catastrophic accidents such as burning shafts and burning bearings, which may cause the entire engine or transmission system to jam and be scrapped. The harm is self-evident.

[0005] In addition, lead has always been an important strengthening component in copper-based sliding bearing materials. Its addition helps reduce friction and wear and improve the operating efficiency of bearings. Currently, the copper-lead materials and tin-based materials commonly used in heavy-duty sliding bearings both contain lead. In order to improve the embedding, compliance and anti-adhesion properties of such bearing materials on the shaft, the surface of the material often needs to be electroplated with a binary (PbSn) layer containing up to 90% lead. 10 ) or ternary (PbSn 10 Cu2) coating. Although lead plays an important role in copper-based sliding bearing materials, such as reducing friction, preventing adhesion, and improving cutting performance, lead and its compounds are highly toxic substances, and their use poses significant risks to the human living environment. Excessive lead content in copper-lead bearing materials, as well as lead plating on the surface, makes it difficult to meet the stringent requirements of current environmental standards. Lead-free materials have become a hot topic in copper-based sliding bearing material research.

[0006] In addition, the advancement of the preparation process is also one of the key factors in achieving high-performance lead-free bearing materials. Traditional sintering methods (such as conventional hot pressing sintering and vacuum hot pressing sintering) have problems such as long sintering cycle, high temperature, easy grain growth, and severe element segregation, which are not conducive to obtaining bearing materials with uniform structure and excellent performance. In recent years, Spark Plasma Sintering (SPS) technology has received 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 ability to effectively suppress grain coarsening and component segregation. This technology directly heats powder particles through pulsed current and uses arc plasma to activate the particle surface. It can achieve densification and forming in a short time, significantly improving the mechanical properties and organizational density of the material.

[0007] Therefore, the development of a lead-free heavy-load copper-based sliding bearing material that is green and environmentally friendly and prepared using advanced processes such as SPS can not only meet the use requirements under heavy-load conditions, 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 current bearing material field. Summary of the Invention

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

[0009] In order to achieve the above object, the technical solution adopted by the present invention is to provide a lead-free heavy-load copper-tin-silicon sliding bearing material, which includes the following components in mass percentage: 10wt.%, tin, 2wt.% to 6wt.%, and the balance is copper.

[0010] On the basis of the above technical solution, the present invention can also be improved as follows.

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

[0012] The present invention also discloses a method for preparing the lead-free heavy-load copper-tin-silicon sliding bearing material, which comprises the following steps:

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

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

[0015] S3: Place the pressed powder along with the mold into a spark plasma sintering furnace for sintering. The sintering procedure is to increase the furnace temperature to 650-700°C at a heating rate of 50-100°C / min, adjust the sintering pressure to 25-35MPa, maintain the temperature and pressure for 8-15 minutes, and then cool to room temperature with the furnace.

[0016] Furthermore, 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.

[0017] Furthermore, the ball milling mixing method in S1 is specifically as follows: copper powder, tin powder and silicon powder are added to a ball mill, and then stainless steel grinding balls and a process control agent are added, and then the air in the ball mill is replaced with an inert gas, followed by ball milling at a speed of 300 rpm for 20 hours, and then vacuum drying and passing through a 100-mesh sieve to obtain a 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; and the inert gas is argon.

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

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

[0021] Furthermore, the final temperature of the heating in S3 is 670°C, the sintering pressure is 30 MPa, and the heat and pressure holding time is 10 min.

[0022] The beneficial effects of the present invention are:

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

[0024] 2. The copper-tin-silicon bearing material of the present invention uses a copper-tin alloy as a base, and adds a hard component silicon to the base. The introduction of silicon can effectively reduce the precipitation of tin, and by controlling the particle size of silicon, 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 compressive strength of the obtained bearing material is 1100 MPa and the Young's modulus is 125 GPa), but also can effectively slow down the cutting effect of the grinding pair on the surface of the bearing material, thereby reducing the occurrence of adhesive wear, and further improving the wear resistance of the bearing material (the average friction coefficient is 0.26, the average wear rate is 1.5*10 -3 mm 3 ·N -1 ·m -1 ).

[0025] 3. The present invention adopts an advanced spark plasma sintering process to prepare the material. The powder particles are directly heated by pulse current, and the particle surface is activated by discharge plasma. Rapid densification sintering can be achieved at a lower temperature, effectively inhibiting grain growth, Sn element segregation and Si phase coarsening, significantly improving the density, mechanical properties and wear resistance of the bearing, while having the process advantages of energy saving and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 SEM images of bearing materials prepared using silicon powder of different particle sizes. DETAILED DESCRIPTION

[0027] The specific implementation methods of the present invention are described in detail below with reference to the embodiments.

[0028] Example 1

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

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

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

[0032] S2: 35 g of the mixed powder was placed into a 30 mm diameter graphite mold, the inner walls of which were separated by carbon paper. The powder was then compacted in the mold using an MS05-100 powder pre-pressing machine at a pressure of 1 kPa for 10 min.

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

[0034] Example 2

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

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

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

[0038] S2: 35 g of the mixed powder was placed into a 30 mm diameter graphite mold, the inner walls of which were separated by carbon paper. The powder in the mold was then compacted using an MS05-100 powder pre-pressing machine at a pressure of 2 kPa for 5 minutes.

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

[0040] Example 3

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

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

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

[0044] S2: 35 g of the mixed powder was placed into a 30 mm diameter graphite mold, the inner walls of which were separated by carbon paper. The powder was then compacted in the mold using an MS05-100 powder pre-pressing machine at a pressure of 1 kPa for 15 minutes.

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

[0046] The lead-free heavy-load copper-tin-silicon sliding bearing materials prepared in Examples 1 to 3 have similar performances. The performance of the bearing material in Example 1 is described below by taking it as an example.

[0047] The hardness of the bearing material in Example 1 was measured using a Vickers hardness tester, and its Vickers hardness was 210HV. The compressive strength of the bearing material was measured using a universal mechanical testing machine, and was 1100MPa (loading rate was 2mm / min). The Oliver-Pharr method was used to calculate the measured data and the Young's modulus of the bearing material was 125GPa. The bearing material in Implementation Plan 1 was tested using an HT-1000 friction and wear tester in a dry friction and room temperature environment. GCr15 steel balls were used as the grinding material. Under the friction conditions of high load (50N) and high speed (600r / min), the average friction coefficient of the bearing material was measured to be 0.26, and the average wear rate was 1.5*10 -3 mm 3 ·N -1 ·m -1 The results show that the bearing material prepared by the method of the present invention has good anti-friction and anti-wear capabilities.

[0048] Example 4

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

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

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

[0052] S2: 35 g of the mixed powder was placed into a 30 mm diameter graphite mold, the inner walls of which were separated by carbon paper. The powder was then compacted in the mold using an MS05-100 powder pre-pressing machine at a pressure of 1 kPa for 10 min.

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

[0054] Example 5

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

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

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

[0058] S2: 35 g of the mixed powder was placed into a 30 mm diameter graphite mold, the inner walls of which were separated by carbon paper. The powder was then compacted in the mold using an MS05-100 powder pre-pressing machine at a pressure of 1 kPa for 10 min.

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

[0060] Example 6

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

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

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

[0064] S2: 35 g of the mixed powder was placed into a 30 mm diameter graphite mold, the inner walls of which were separated by carbon paper. The powder was then compacted in the mold using an MS05-100 powder pre-pressing machine at a pressure of 1 kPa for 10 min.

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

[0066] The lead-free heavy-load copper-tin-silicon sliding bearing materials prepared in Examples 4 to 6 were subjected to SEM testing, and the results were as follows: Figure 1 As shown, Figure 1 Figures a, b, and c show SEM images of bearing materials prepared using silicon powders of varying particle sizes, while a, a1, and a2 show test results at different scales. As can be seen from the figure, as the silicon particle size decreases, tin precipitation decreases, while the number of silicon clusters increases significantly. While an appropriate amount of silicon clusters contributes to friction reduction and wear resistance, an excessive amount weakens the effect. Therefore, bearing materials prepared with silicon particles of 500 nm achieve the best balance between microstructural uniformity and strength and hardness, while also exhibiting excellent friction reduction and wear resistance.

[0067] Although the specific embodiments of the present invention have been described in detail in conjunction with the embodiments, this should not be construed as limiting the scope of protection of this patent. Within the scope described by the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A lead-free heavy-load copper-tin-silicon sliding bearing material, characterized in that: The invention comprises the following components in percentage by mass: 10 wt.% of tin, 2 wt.% to 6 wt.% of silicon, and the balance being copper.

2. The lead-free heavy-load copper-tin-silicon sliding bearing material according to claim 1, characterized in that: The invention comprises the following components in percentage by mass: 10 wt.% of tin, 4 wt.% of silicon, and the balance of copper.

3. The method for preparing the lead-free heavy-load copper-tin-silicon sliding bearing material according to claim 1 or 2, characterized in that: The following steps are involved: S1: Copper powder, tin powder and silicon powder are ball-milled in an inert atmosphere to obtain a composite powder; S2: Pour the mixed powder into a mold and press at a pressure of 1-2 kPa for 5-15 minutes; S3: Place the pressed powder along with the mold into a spark plasma sintering furnace for sintering. The sintering procedure is to increase the furnace temperature to 650-700°C at a heating rate of 50-100°C / min, adjust the sintering pressure to 25-35MPa, maintain the temperature and pressure for 8-15 minutes, and then cool to room temperature with the furnace.

4. The preparation method according to claim 3, wherein: 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.

5. The preparation method according to claim 4, characterized in that The ball milling mixing method in S1 is specifically as follows: copper powder, tin powder and silicon powder are added to a ball mill jar, and then stainless steel grinding balls and a process control agent are added. The air in the ball mill jar is replaced with an inert gas, and then the mixture is ball milled at a speed of 300 rpm for 20 hours. The mixture is then vacuum dried and passed through a 100-mesh sieve to obtain a 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.

6. The preparation method according to claim 5, characterized in that: The process control agent is anhydrous ethanol; the inert gas is argon.

7. The preparation method according to claim 3, wherein: The mold is a graphite mold, and the inner wall of the mold is paved with carbon paper.

8. The preparation method according to claim 7, characterized in that: The pressing pressure in S2 is 1 kPa and the pressing time is 10 min.

9. The preparation method according to claim 7, characterized in that: The final temperature of the heating in S3 is 670℃, the sintering pressure is 30MPa, and the heat and pressure holding time is 10min.

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