Composite coating bearing bush and preparation method thereof

Abstract

The invention belongs to the technical field of bearing bush manufacturing, and particularly relates to a composite coating bearing bush and a preparation method thereof. The composite coating bearing bush sequentially comprises a steel backing layer and a composite coating layer from a base body to the surface, wherein the steel backing layer is formed by steel with the thickness larger than 1 mm; the alloy layer is selected from a CuPbSn alloy or a CuSnZnFeS alloy, and the thickness of the alloy layer ranges from 0.2 mm to 1.0 mm; the Sputter coating is made of an AlSnCu material, and the thickness of the Sputter coating ranges from 10 microns to 30 microns; the Ni transition layer is made of a metal nickel material, and the thickness of the Ni transition layer is 0.05-2 microns; the thickness of the organic polymer composite coating is 4-10 microns, and the organic polymer composite coating comprises a base material, MoS powder and carbon powder, wherein the MoS powder and the carbon powder are uniformly dispersed. According to the composite coating bearing bush, through cooperation of the Ni transition layer and a multi-layer material, the problem that the binding force between the organic polymer coating and the Sputter coating is degraded due to exudation of Sn elements is effectively solved, and the composite coating bearing bush is particularly suitable for internal combustion engine application scenes under high-load and high-temperature working conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of bearing bush manufacturing, and in particular relates to a composite coating bearing bush and a preparation method thereof. Background Art

[0002] With the continuous development of the automobile industry, the performance requirements for internal combustion engines are increasing. In order to meet the needs of higher thermal efficiency and longer service life (such as B10 life), the design explosion pressure of the engine continues to rise, while the viscosity of the engine oil gradually decreases. In this case, the bearing, as a key component in the internal combustion engine, needs to have high load-bearing capacity, long life and good compliance to adapt to the harsh working environment.

[0003] In order to achieve these performance goals, the structure and materials of bearings have undergone many improvements. Early bearings were mostly made of single alloy materials, such as babbitt alloy, copper-based alloy or aluminum-based alloy. However, these single-material bearings have deficiencies in load-bearing capacity, fatigue resistance and compliance, and are difficult to meet the high performance requirements of modern internal combustion engines.

[0004] Subsequently, bearings with composite structures gradually became mainstream. A common improvement scheme is to add anti-friction materials, such as copper alloys or aluminum alloys, to the steel backing layer to improve the anti-friction performance and load-bearing capacity of the bearing. The steel backing layer provides high strength and rigidity, while the anti-friction material layer reduces friction and wear. Further improvements include adding a coating, such as an electroplating coating, to the anti-friction material layer to enhance the surface properties of the bearing. For example, plating a layer of lead-tin alloy or other alloys on the surface of the bearing through an electroplating process can improve the anti-friction performance and fatigue strength of the bearing.

[0005] In recent years, with the development of coating technology, magnetron sputtering thin film technology has been introduced into the field of bearing manufacturing. This technology improves the wear resistance and fatigue resistance of the bearing by sputtering various wear-resistant metal materials on the surface of the bearing, while improving its tribological properties. In addition, solid lubricating coatings are also applied to the surface of the bearing, and the wear resistance and self-lubricating properties of the bearing are further improved by spraying polymer coatings containing solid lubricants (such as molybdenum disulfide and graphite). However, these methods are gradually approaching technical bottlenecks in improving load-bearing capacity, long service life, and compliance.

[0006] Despite the above-mentioned various improvement schemes, there are still some technical problems with the existing bearing structure. For example, an optimized bearing structure includes a steel backing layer, an alloy layer, a Sputter coating and an organic polymer coating. The steel backing layer mainly provides the basic strength and stiffness of the bearing, the alloy layer and the Sputter coating are used to improve the friction reduction performance and load-bearing capacity of the bearing, and the organic polymer coating provides certain lubrication properties. However, the tin element in the Sputter coating will spontaneously seep out to the surface of the coating, especially in high humidity or high temperature environments, this seepage phenomenon will be aggravated. The seeped tin element will seriously weaken the bonding force between the Sputter coating and the organic polymer coating, and eventually cause the organic polymer coating to fall off over a large area. This not only affects the normal working performance of the bearing, but also greatly shortens its service life, and cannot meet the long-term stable operation requirements of modern internal combustion engines under high load and high temperature conditions. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a composite coating bearing and a preparation method thereof. The purpose of the present invention is to effectively solve the problem of organic polymer coating shedding in the existing bearing structure, improve the bearing capacity, service life and compliance of the bearing, and meet the long-term stable operation requirements of modern internal combustion engines under high load and high temperature conditions.

[0008] The first aspect of the present invention is to provide a composite coating bearing, which comprises, from the substrate to the surface:

[0009] The steel backing layer (1) is made of steel material with a thickness greater than 1 mm;

[0010] The alloy layer (2) is selected from CuPbSn alloy or CuSnZnFeS alloy; the components of the CuPbSn alloy are as follows by mass percentage: Cu balance, Pb 18-25%, Sn 1.5-3.6%; the components of the CuSnZnFeS alloy are as follows by mass percentage: Cu balance, Sn 0.3-1.6%, Zn 0.4-1.5%, Fe0.3-1.5%, S 0.3-1.2%; the thickness is 0.2-1.0 mm;

[0011] The sputter coating (3) is made of AlSnCu material, wherein the components of the AlSnCu material are as follows by mass percentage: Al balance, Sn 15-23%, Cu 0.2-1.3%, and a thickness of 10-30 μm;

[0012] The Ni transition layer (4) is made of a metallic nickel material and has a thickness of 0.05-2 μm;

[0013] The organic polymer composite coating (5) has a thickness of 4-10 μm and comprises a base material and evenly dispersed MoS2 powder and carbon powder, wherein the base material is polyimide.

[0014] As a further optimization solution for the above composite coating bearing, the mass fraction of MoS2 powder in the organic polymer composite coating (5) is 40-50%.

[0015] As a further optimization solution for the composite coating bearing bush, the mass fraction of carbon powder in the organic polymer composite coating (5) is 18-28%.

[0016] As a further optimization solution for the composite coating bearing bushing, the thickness of the Ni transition layer (4) is 1.2±0.1 μm.

[0017] As a further optimization solution for the above-mentioned composite coating bearing, the thickness of the Sputter coating (3) is 20±2 μm.

[0018] As a further optimization solution for the composite coating bearing bushing, the purity of the metal nickel used to form the Ni transition layer (4) is ≥99.8%.

[0019] The second aspect of the present invention is to provide a method for preparing the composite coating bearing bush, comprising the following steps:

[0020] (1) Steel back pretreatment: Pre-treat the surface of the steel back material to form a dry, clean and flat surface;

[0021] (2) Alloy casting: casting molten CuPbSn or CuSnZnFeS alloy on the steel back surface; the components of the CuPbSn alloy are as follows by mass percentage: Cu balance, Pb18-25%, Sn 1.5-3.6%; the components of the CuSnZnFeS alloy are as follows by mass percentage: Cu balance, Sn 0.3-1.6%, Zn 0.4-1.5%, Fe0.3-1.5%, S 0.3-1.2%; forming a 0.2-1.0 mm alloy layer;

[0022] (3) Magnetron sputtering deposition: In a physical vapor deposition device, AlSnCu material is sputtered, and the composition of the AlSnCu material is calculated by mass percentage as follows: Al balance, Sn 15-23%, Cu 0.2-1.3%, to form a 10-30 μm Sputter coating;

[0023] (4) Nickel layer deposition: Sputter pure nickel on the surface of the Sputter coating to form a Ni transition layer with a thickness of 0.05-2 μm;

[0024] (5) Spraying of organic polymer composite coating: Spraying a polyimide material containing MoS2 powder and carbon powder on the surface of the Ni layer to form a coating with a thickness of 4-10 μm.

[0025] As a further optimization scheme of the preparation method of the above-mentioned composite coating bearing, the steel back pretreatment steps include degreasing, derusting, cleaning and drying.

[0026] As a further optimization scheme of the preparation method of the composite coating bearing, the nickel layer deposition step uses metal nickel with a purity of 99.9% as a target material, and magnetron sputtering is used to form a Ni transition layer with a thickness of 0.05-2 μm.

[0027] Beneficial Effects

[0028] The composite coating bearing of the present invention effectively solves the problem of deterioration of the bonding strength between the organic polymer coating and the Sputter coating due to the leakage of Sn elements through the cooperation of the Ni transition layer and the multilayer material. In the 95°C water bath bonding test, the Ni layer significantly blocked the diffusion and migration of Sn in the AlSnCu coating, making the shedding area of ​​the organic polymer coating account for less than 0.2%. Compared with the scheme without Ni layer or other transition layer, the bonding strength is significantly improved, which is particularly suitable for internal combustion engine application scenarios under high load and high temperature conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the layered structure of the composite coating bearing bush of the present invention.

[0030] Figure 2 This is a diagram showing the surface state of the coating after the bonding strength test of the sample in the embodiment of the present invention.

[0031] Figure 3 This is a microscopic cross-sectional micrograph of the Ni transition layer of the example sample. DETAILED DESCRIPTION

[0032] The present invention is further illustrated by specific examples below. These examples are exemplary and are intended to illustrate the problem and explain the present invention, but are not intended to be limiting.

[0033] Example 1

[0034] Selection and pretreatment of the steel back layer: Select steel back material with a thickness greater than 1mm as the basic support structure of the bearing shell; degrease, rust and clean the steel back layer to ensure a clean and flat surface to facilitate the casting of the subsequent alloy layer.

[0035] Alloy layer casting: casting the molten CuSnZnFeS alloy onto the surface of the pretreated steel back layer, wherein the components of the CuSnZnFeS alloy are as follows by mass percentage: Cu balance, Sn 1.0%, Zn 1.0%, Fe 0.9%, S0.6%, and controlling the alloy layer to uniformly cover the steel back and form an alloy layer with a thickness of 0.5 mm.

[0036] Sputter coating deposition: The steel back with the cast alloy layer is placed in a physical vapor deposition device, and AlSnCu material is sputtered onto the surface of the alloy layer by magnetron sputtering. The components of the AlSnCu material are calculated by mass percentage as follows: Al balance, Sn19%, Cu 0.7%, forming a Sputter coating with a thickness of 20 μm.

[0037] Ni layer deposition: In a vapor deposition device, Ni material with a purity of 99.9% is sputtered onto the surface of the Sputter coating to form a Ni layer with a thickness of 1.2 μm.

[0038] Spraying of organic polymer coating: Finally, an organic polymer coating with a thickness of 6 μm is sprayed on the surface of the Ni layer; the organic polymer coating has a base material of polyimide and is evenly mixed with 45% by mass of MoS2 powder and 23% by mass of C powder.

[0039] Example 2

[0040] Selection and pretreatment of the steel back layer: Select steel back material with a thickness greater than 1mm as the basic support structure of the bearing shell; degrease, rust and clean the steel back layer to ensure a clean and flat surface to facilitate the casting of the subsequent alloy layer.

[0041] Alloy layer casting: Cast the molten CuPbSn alloy onto the surface of the pretreated steel back layer. The components of the CuPbSn alloy are as follows by mass percentage: Cu balance, Pb18%, Sn 1.5%. The alloy layer is controlled to evenly cover the steel back and form an alloy layer with a thickness of 0.2 mm.

[0042] Sputter coating deposition: The steel back with the cast alloy layer is placed in a physical vapor deposition device, and AlSnCu material is sputtered onto the surface of the alloy layer by magnetron sputtering. The components of the AlSnCu material are calculated by mass percentage as follows: Al balance, Sn15%, Cu 0.2%, forming a Sputter coating with a thickness of 10 μm.

[0043] Ni layer deposition: In a vapor deposition device, a Ni material with a purity of 99.9% is sputtered onto the surface of the Sputter coating to form a Ni layer with a thickness of 0.05 μm.

[0044] Spraying of organic polymer coating: Finally, an organic polymer coating with a thickness of 4 μm is sprayed on the surface of the Ni layer; the organic polymer coating has a base material of polyimide and is evenly mixed with 40% by mass of MoS2 powder and 18% by mass of C powder.

[0045] Example 3

[0046] Selection and pretreatment of the steel back layer: Select steel back material with a thickness greater than 1mm as the basic support structure of the bearing shell; degrease, rust and clean the steel back layer to ensure a clean and flat surface to facilitate the casting of the subsequent alloy layer.

[0047] Alloy layer casting: Cast the molten CuPbSn alloy onto the surface of the pretreated steel back layer. The components of the CuPbSn alloy are as follows by mass percentage: Cu balance, Pb25%, Sn 3.6%. The alloy layer is controlled to evenly cover the steel back and form an alloy layer with a thickness of 1.0 mm.

[0048] Sputter coating deposition: The steel back with the cast alloy layer is placed in a physical vapor deposition device, and AlSnCu material is sputtered onto the surface of the alloy layer by magnetron sputtering. The components of the AlSnCu material are calculated by mass percentage as follows: Al balance, Sn23%, Cu 1.3%, forming a Sputter coating with a thickness of 30 μm.

[0049] Ni layer deposition: In a vapor deposition device, Ni material with a purity of 99.9% is sputtered onto the surface of the Sputter coating to form a Ni layer with a thickness of 2 μm.

[0050] Spraying of organic polymer coating: Finally, an organic polymer coating with a thickness of 10 μm is sprayed on the surface of the Ni layer; the organic polymer coating has a base material of polyimide and is evenly mixed with 50% by mass MoS2 powder and 28% by mass C powder.

[0051] Example 4

[0052] Selection and pretreatment of the steel back layer: Select steel back material with a thickness greater than 1mm as the basic support structure of the bearing shell; degrease, rust and clean the steel back layer to ensure a clean and flat surface to facilitate the casting of the subsequent alloy layer.

[0053] Alloy layer casting: Cast the molten CuPbSn alloy onto the surface of the pretreated steel back layer. The components of the CuPbSn alloy are as follows by mass percentage: Cu balance, Pb22%, Sn 2.1%. The alloy layer is controlled to evenly cover the steel back and form an alloy layer with a thickness of 0.5 mm.

[0054] Sputter coating deposition: The steel back with the cast alloy layer is placed in a physical vapor deposition device, and AlSnCu material is sputtered onto the surface of the alloy layer by magnetron sputtering. The components of the AlSnCu material are calculated by mass percentage as follows: Al balance, Sn19%, Cu 0.7%, forming a Sputter coating with a thickness of 20 μm.

[0055] Ni layer deposition: In a vapor deposition device, Ni material with a purity of 99.9% is sputtered onto the surface of the Sputter coating to form a Ni layer with a thickness of 1.2 μm.

[0056] Spraying of organic polymer coating: Finally, an organic polymer coating with a thickness of 6 μm is sprayed on the surface of the Ni layer; the organic polymer coating has a base material of polyimide and is evenly mixed with 45% by mass of MoS2 powder and 23% by mass of C powder.

[0057] Comparative Example 1

[0058] Compared with Example 4, no Ni layer is provided between the Sputter coating and the organic polymer coating.

[0059] Selection and pretreatment of the steel back layer: Select steel back material with a thickness greater than 1mm as the basic support structure of the bearing shell; degrease, rust and clean the steel back layer to ensure a clean and flat surface to facilitate the casting of the subsequent alloy layer.

[0060] Alloy layer casting: Cast the molten CuPbSn alloy onto the surface of the pretreated steel back layer. The components of the CuPbSn alloy are as follows by mass percentage: Cu balance, Pb22%, Sn 2.1%. The alloy layer is controlled to evenly cover the steel back and form an alloy layer with a thickness of 0.5 mm.

[0061] Sputter coating deposition: The steel back with the cast alloy layer is placed in a physical vapor deposition device, and AlSnCu material is sputtered onto the surface of the alloy layer by magnetron sputtering. The components of the AlSnCu material are calculated by mass percentage as follows: Al balance, Sn19%, Cu 0.7%, forming a Sputter coating with a thickness of 20 μm.

[0062] Spraying of organic polymer coating: Finally, an organic polymer coating with a thickness of 6 μm is sprayed on the surface of the Sputter coating; the organic polymer coating has a base material of polyimide and is evenly mixed with 45% by mass of MoS2 powder and 23% by mass of C powder.

[0063] Comparative Example 2

[0064] Compared with Example 4, an Al layer is provided between the Sputter coating and the organic polymer coating.

[0065] Selection and pretreatment of the steel back layer: Select steel back material with a thickness greater than 1mm as the basic support structure of the bearing shell; degrease, rust and clean the steel back layer to ensure a clean and flat surface to facilitate the casting of the subsequent alloy layer.

[0066] Alloy layer casting: Cast the molten CuPbSn alloy onto the surface of the pretreated steel back layer. The components of the CuPbSn alloy are as follows by mass percentage: Cu balance, Pb22%, Sn 2.1%. The alloy layer is controlled to evenly cover the steel back and form an alloy layer with a thickness of 0.5 mm.

[0067] Sputter coating deposition: The steel back with the cast alloy layer is placed in a physical vapor deposition device, and AlSnCu material is sputtered onto the surface of the alloy layer by magnetron sputtering. The components of the AlSnCu material are calculated by mass percentage as follows: Al balance, Sn19%, Cu 0.7%, forming a Sputter coating with a thickness of 20 μm.

[0068] Al layer deposition: In a vapor deposition device, Al material with a purity of 99.9% is sputtered onto the surface of the Sputter coating to form an Al layer with a thickness of 1.2 μm.

[0069] Spraying of organic polymer coating: Finally, an organic polymer coating with a thickness of 6 μm is sprayed on the surface of the Ni layer; the organic polymer coating has a base material of polyimide and is evenly mixed with 45% by mass of MoS2 powder and 23% by mass of C powder.

[0070] Comparative Example 3

[0071] Compared with Example 4, a SnCuSb layer is disposed between the Sputter coating and the organic polymer coating.

[0072] Selection and pretreatment of the steel back layer: Select steel back material with a thickness greater than 1mm as the basic support structure of the bearing shell; degrease, rust and clean the steel back layer to ensure a clean and flat surface to facilitate the casting of the subsequent alloy layer.

[0073] Alloy layer casting: Cast the molten CuPbSn alloy onto the surface of the pretreated steel back layer. The components of the CuPbSn alloy are as follows by mass percentage: Cu balance, Pb22%, Sn 2.1%. The alloy layer is controlled to evenly cover the steel back and form an alloy layer with a thickness of 0.5 mm.

[0074] Sputter coating deposition: The steel back with the cast alloy layer is placed in a physical vapor deposition device, and AlSnCu material is sputtered onto the surface of the alloy layer by magnetron sputtering. The components of the AlSnCu material are calculated by mass percentage as follows: Al balance, Sn19%, Cu 0.7%, forming a Sputter coating with a thickness of 20 μm.

[0075] SnCuSb layer deposition: In a vapor deposition device, a SnCuSb material is sputtered onto the surface of the Sputter coating. The components of the SnCuSb material are calculated by mass percentage as follows: Sn balance, Cu 10%, Sb 3%, forming a SnCuSb layer with a thickness of 1.2 μm.

[0076] Spraying of organic polymer coating: Finally, an organic polymer coating with a thickness of 6 μm is sprayed on the surface of the Ni layer; the organic polymer coating has a base material of polyimide and is evenly mixed with 45% by mass of MoS2 powder and 23% by mass of C powder.

[0077] Performance Testing

[0078] Adhesion test: Place the prepared bearing in water, heat to 95°C, and keep warm for 1 hour. Take out the bearing and test the adhesion of the organic polymer coating. Observe whether the coating has shedding or stratification, and calculate the shedding area ratio of the organic polymer coating. The test results are shown in Table 1.

[0079] Table 1 Performance test results

[0080]

[0081] The results show that Examples 1 to 4 of the present invention all achieved good results. Figure 2 As shown, samples a, b, c, and d correspond to Examples 1 to 4, respectively. The surface organic polymer coating shedding area accounts for less than 0.2%, and there is no stratification of the coating, only small spots of shedding occur, which meets the standard. This shows that the scheme of adding a Ni layer between the Sputter coating and the organic polymer coating can effectively prevent the organic polymer coating from shedding, and significantly improve the performance and service life of the bearing. Among them, the cross section of the sample of Example 4 shows a clear and uniform Ni coating under a microscope (such as Figure 3 shown).

[0082] In comparative example 1, the Ni layer was not provided, and the organic polymer coating was directly sprayed on the Sputter coating. The results showed that the coating peeling area accounted for more than 95%, indicating that in the absence of the Ni layer, the infiltration of the tin element seriously weakened the bonding force between the coatings, resulting in large-area peeling of the coating.

[0083] Comparative Example 2 sets an Al layer instead of a Ni layer. The test results show that the coating peeling area accounts for more than 50%, and there is still a serious delamination phenomenon, which means that the Al layer cannot effectively block the leakage of tin elements and cannot achieve the same effect as the Ni layer.

[0084] Comparative Example 3 sets a SnCuSb layer instead of a Ni layer. The results show that the coating peeling area accounts for more than 95%, which is similar to Comparative Example 1, indicating that the SnCuSb layer is also unable to effectively prevent the organic polymer coating from falling off.

[0085] The above embodiments are exemplary, and their purpose is to illustrate the technical concept and features of the present invention so that people familiar with the technology in this field can understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite coated bearing bushing, characterized in that: From the substrate to the surface, it includes: The steel backing layer (1) is made of steel with a thickness greater than 1 mm; The alloy layer (2) is selected from a CuPbSn alloy or a CuSnZnFeS alloy; the components of the CuPbSn alloy are as follows by mass percentage: Cu balance, Pb 18-25%, Sn 1.5-3.6%; the components of the CuSnZnFeS alloy are as follows by mass percentage: Cu balance, Sn 0.3-1.6%, Zn 0.4-1.5%, Fe0.3-1.5%, S 0.3-1.2%; the thickness is 0.2-1.0 mm; Sputter coating (3), composed of AlSnCu material, the components of the AlSnCu material are as follows by mass percentage: Al balance, Sn 15-23%, Cu 0.2-1.3%, and a thickness of 10-30 μm; Ni transition layer (4), made of metallic nickel material, with a thickness of 0.05-2 μm; The organic polymer composite coating (5) has a thickness of 4-10 μm and comprises a base material and evenly dispersed MoS2 powder and carbon powder.

2. The composite coated bearing bush according to claim 1, characterized in that: The base material in the organic polymer composite coating (5) is polyimide.

3. The composite coated bearing bush according to claim 1, characterized in that: In the organic polymer composite coating (5), the mass fraction of MoS2 powder is 40-50%.

4. The composite coated bearing bush according to claim 1, characterized in that: In the organic polymer composite coating (5), the mass fraction of carbon powder is 18-28%.

5. The composite coated bearing bush according to claim 1, characterized in that: The thickness of the Ni transition layer (4) is 1.2±0.1 μm.

6. The composite coated bearing bush according to claim 1, characterized in that: The thickness of the Sputter coating (3) is 20±2 μm.

7. The composite coated bearing bush according to claim 1, characterized in that: The purity of the metal nickel used to form the Ni transition layer (4) is ≥99.8%.

8. A method for preparing a composite coated bearing bush according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Steel back pretreatment: pretreat the surface of the steel back material to form a dry, clean and flat surface; (2) Alloy casting: Casting molten CuPbSn or CuSnZnFeS alloy on the steel back surface; the composition of the CuPbSn alloy is as follows by mass percentage: Cu balance, Pb 18-25%, Sn 1.5-3.6%; the composition of the CuSnZnFeS alloy is as follows by mass percentage: Cu balance, Sn 0.3-1.6%, Zn 0.4-1.5%, Fe0.3-1.5%, S 0.3-1.2%; forming a 0.2-1.0 mm alloy layer; (3) Magnetron sputtering deposition: In a physical vapor deposition device, AlSnCu material is sputtered. The composition of the AlSnCu material is calculated by mass percentage as follows: Al balance, Sn 15-23%, Cu 0.2-1.3%, forming a 10-30μm Sputter coating; (4) Nickel layer deposition: Sputter pure nickel on the surface of the Sputter coating to form a Ni transition layer with a thickness of 0.05-2 μm; (5) Spraying of organic polymer composite coating: Spray polyimide material containing MoS2 powder and carbon powder on the surface of the Ni layer to form a coating with a thickness of 4-10 μm.

9. A method for preparing a composite coated bearing bush as claimed in claim 8, characterized in that: Steel back pretreatment steps include degreasing, rust removal, cleaning and drying.

10. A method for preparing a composite coated bearing bush as claimed in claim 8, characterized in that: The nickel layer deposition step uses metallic nickel with a purity of 99.9% as a target material, and magnetron sputtering is used to form a Ni transition layer with a thickness of 0.05-2 μm.

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