Sliding bearing and preparation method

Abstract

The invention discloses a sliding bearing which comprises a static ring and a movable ring, and the static ring is arranged on the movable ring in a sleeving mode. At least one circle of multiple first blind holes are formed in the circumferential direction of the first inner cylindrical surface of the static ring, and a first friction part is fixed in each first blind hole; at least one circle of a plurality of second blind holes are formed in the circumferential direction of the second outer cylindrical surface of the movable ring; a second friction part is fixed in each second blind hole; all the first friction parts and the second friction parts are correspondingly arranged to form a sliding friction pair; wherein the first friction part and the second friction part are a TSP friction part, a PCD friction part, a nickel-plated TSP friction part, a nickel-plated PCD friction part, a coated TSP friction part or a coated PCD friction part. Through the application of TSP and PCD materials, the wear resistance and stability of the sliding bearing are remarkably improved, and the service life of the sliding bearing under the severe working conditions of high speed, heavy load, high temperature and the like is greatly prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of bearings, and particularly relates to a sliding bearing and a preparation method thereof. Background Art

[0002] With the increasing intensity of oil and gas exploration, rotary steerable drilling tools have been widely used in the drilling operations of complex structural wells such as horizontal wells, extended reach wells, and multi-branch wells due to their precise trajectory control ability and high drilling performance, providing strong technical support for improving the development efficiency and recovery rate of oil and gas fields. However, the harsh downhole environment poses a huge challenge to drilling work. Due to the limited downhole space, as a key component of the rotary steering system, the bearing usually adopts an open structure, which is directly exposed to the drilling fluid filled with solid particles, resulting in severe wear of the bearing. In addition, the direct contact of the bearing with corrosive formations such as salt-containing formations, high-sulfur formations, high-carbon dioxide formations, organic acid formations, and porous sandstone formations puts forward higher requirements for the corrosion resistance of the bearing friction pair materials.

[0003] Polycrystalline diamond compact (PDC) has both the high hardness and high wear resistance of diamond and the high impact resistance of cemented carbide, and is currently a commonly used material for the sliding friction pair of sliding bearings. However, the corrosion resistance of polycrystalline diamond compact is relatively limited. In particular, the cemented carbide part and cobalt binder are easily oxidized and corroded, resulting in the corrosion failure of the bearing. In addition, the preparation process of high-wear-resistant PDC is relatively cumbersome. The optimized design of multi-layer composite materials puts extremely high requirements on equipment accuracy, process parameter control, and material property matching. The preparation of high-wear-resistant PDC materials usually requires high costs, which further restricts the development of PDC bearings. Summary of the Invention

[0004] Aiming at the deficiencies in the prior art, the present invention provides a sliding bearing and a preparation method thereof, which use thermally stable polycrystal (TSP) and / or polycrystalline diamond (PCD) as the sliding friction pair of the sliding bearing.

[0005] The present invention discloses a sliding bearing, including: a stationary ring and a rotating ring, the stationary ring is sleeved on the rotating ring;

[0006] The stationary ring includes a first base body integrally in a circular ring shape, the first base body has a relative first inner cylindrical surface and a first outer cylindrical surface, a plurality of first blind holes are provided on the first inner cylindrical surface, and the plurality of first blind holes are arranged along the circumferential direction of the first base body for at least one circle and the plurality of first blind holes in each circle are spaced apart; a first friction part is fixed in each first blind hole, and one side of the first friction part exposes the first inner cylindrical surface;

[0007] The moving ring includes a second substrate that is integrally circular-ring-shaped. The second substrate has opposite second inner cylindrical surfaces and second outer cylindrical surfaces. A plurality of second blind holes are provided on the second outer cylindrical surface. The plurality of second blind holes are arranged along the circumferential direction of the second substrate for at least one circle, and the plurality of second blind holes in each circle are spaced apart. A second friction portion is fixed in each second blind hole, and one side of the second friction portion exposes the second outer cylindrical surface.

[0008] All the first friction portions and all the second friction portions are correspondingly arranged to form a sliding friction pair. Among them, the corresponding first friction portion and second friction portion are a thermally stable polycrystalline diamond friction portion (TSP friction portion), a polycrystalline diamond friction portion (PCD friction portion), a nickel-plated thermally stable polycrystalline diamond friction portion (nickel-plated TSP friction portion), a nickel-plated polycrystalline diamond friction portion (nickel-plated PCD friction portion), an inserted thermally stable polycrystalline diamond friction portion (inserted TSP friction portion), or an inserted polycrystalline diamond friction portion (inserted PCD friction portion).

[0009] As a further improvement of the present invention, the moving ring includes a first base that is integrally circular-ring-shaped. The first base is sleeved on one end of the second substrate. When the stationary ring is sleeved on the moving ring, the bottom surface of the first substrate abuts against the top surface of the first base.

[0010] The bottom surface of the first substrate is provided with a plurality of third blind holes. The plurality of third blind holes are arranged along the circumferential direction of the first substrate for at least one circle, and the plurality of third blind holes in each circle are spaced apart. A third friction portion is fixed in each third blind hole, and one side of the third friction portion exposes the bottom surface of the first substrate.

[0011] The top surface of the first base is provided with a plurality of fourth blind holes. The plurality of fourth blind holes are arranged along the circumferential direction of the first base for at least one circle, and the plurality of fourth blind holes in each circle are spaced apart. A fourth friction portion is fixed in each fourth blind hole, and one side of the fourth friction portion exposes the top surface of the first base.

[0012] All the third friction portions and all the fourth friction portions are correspondingly arranged to form a sliding friction pair. Among them, the corresponding third friction portion and fourth friction portion are a thermally stable polycrystalline diamond friction portion (TSP friction portion), a polycrystalline diamond friction portion (PCD friction portion), a nickel-plated thermally stable polycrystalline diamond friction portion (nickel-plated TSP friction portion), a nickel-plated polycrystalline diamond friction portion (nickel-plated PCD friction portion), an inserted thermally stable polycrystalline diamond friction portion (inserted TSP friction portion), or an inserted polycrystalline diamond friction portion (inserted PCD friction portion).

[0013] As a further improvement of the present invention, the materials of the corresponding first friction portion and second friction portion are the same, and the materials of the corresponding third friction portion and fourth friction portion are the same.

[0014] As a further improvement of the present invention, the thermally stable polycrystalline diamond friction part is a silicon-based polycrystal, and the polycrystalline diamond friction part is a cobalt-based polycrystal.

[0015] As a further improvement of the present invention, the axial distance between two adjacent turns of the first friction part is the same as the axial distance between two adjacent turns of the second friction part, and the axial distance between two adjacent turns of the third friction part is the same as the axial distance between two adjacent turns of the fourth friction part.

[0016] As a further improvement of the present invention,

[0017] The difference between the first friction part of the stationary ring and the second friction part of the rotating ring is 10 μm to 50 μm;

[0018] The shape of the first friction part, the second friction part, the third friction part or the fourth friction part includes one of a cylindrical shape and a cubic shape. When formed into a cylindrical shape, the diameter of the first friction part, the second friction part, the third friction part or the fourth friction part is 2 mm to 20 mm, the total height is 1 mm to 10 mm, and the exposed height is 0 to 3 mm.

[0019] As a further improvement of the present invention,

[0020] The nickel-plated thermally stable polycrystalline diamond friction part (nickel-plated TSP friction part) or the nickel-plated polycrystalline diamond friction part (nickel-plated PCD friction part) includes a thermally stable polycrystalline diamond friction part or a polycrystalline diamond friction part, and a nickel-plated layer formed on the outside thereof; wherein, the thickness of the nickel-plated layer is 0.05 mm to 0.30 mm;

[0021] The encapsulated thermally stable polycrystalline diamond friction part (encapsulated TSP friction part) or the encapsulated polycrystalline diamond friction part (encapsulated PCD friction part) includes a thermally stable polycrystalline diamond friction part or a polycrystalline diamond friction part, and a metal encapsulation layer formed on the outside thereof; wherein, the thickness of the metal encapsulation layer is 0.50 mm to 5 mm.

[0022] As a further improvement of the present invention, the first friction part, the second friction part, the third friction part or the fourth friction part is fixedly welded in the corresponding first blind hole, second blind hole, third blind hole or fourth blind hole; wherein, the welding method includes one of vacuum brazing, high-frequency brazing and flame spraying.

[0023] The present invention also discloses a preparation method of a sliding bearing, including:

[0024] Synthesizing thermally stable polycrystalline diamond (TSP) and polycrystalline diamond (PCD) by using a cubic press;

[0025] Nickel plating is carried out on thermally stable polycrystalline diamond (TSP) and polycrystalline diamond (PCD) to obtain nickel-plated thermally stable polycrystalline diamond (nickel-plated TSP) and nickel-plated polycrystalline diamond (nickel-plated PCD);

[0026] Bond the thermally stable polycrystalline diamond (TSP) or polycrystalline diamond (PCD) to the lower press head of the graphite mold and assemble it with the middle mold of the graphite mold; fill the gap between the thermally stable polycrystalline diamond (TSP) or polycrystalline diamond (PCD) and the middle mold with metal powders (such as WC, Ni powder, etc.). After filling, install the upper press head and sinter at 800 - 1200 °C in a hot press sintering machine for 1 - 30 min. After cooling, take out the synthesized sample to obtain the inserted thermally stable polycrystalline diamond (inserted TSP) or inserted polycrystalline diamond (inserted PCD);

[0027] Carry out machining on the thermally stable polycrystalline diamond (TSP), polycrystalline diamond (PCD), nickel-plated thermally stable polycrystalline diamond (nickel-plated TSP), nickel-plated polycrystalline diamond (nickel-plated PCD), inserted thermally stable polycrystalline diamond (inserted TSP) and inserted polycrystalline diamond (inserted PCD) to obtain the thermally stable polycrystalline diamond friction part (TSP friction part), polycrystalline diamond friction part (PCD friction part), nickel-plated thermally stable polycrystalline diamond friction part (nickel-plated TSP friction part), nickel-plated polycrystalline diamond friction part (nickel-plated PCD friction part), inserted thermally stable polycrystalline diamond friction part (inserted TSP friction part) and inserted polycrystalline diamond friction part (inserted PCD friction part) with the required sizes;

[0028] Drill holes and process the substrates of the stationary ring and the rotating ring, and weld and fix the thermally stable polycrystalline diamond friction part (TSP friction part), polycrystalline diamond friction part (PCD friction part), nickel-plated thermally stable polycrystalline diamond friction part (nickel-plated TSP friction part), nickel-plated polycrystalline diamond friction part (nickel-plated PCD friction part), inserted thermally stable polycrystalline diamond friction part (inserted TSP friction part) and inserted polycrystalline diamond friction part (inserted PCD friction part) in the corresponding blind holes to form the final sliding bearing.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] By applying TSP and PCD materials, the present invention significantly improves the wear resistance of the sliding bearing, greatly prolonging its service life under harsh working conditions such as high speed, heavy load, and high temperature; at the same time, the thermal stability of TSP enables the sliding bearing to maintain a good operating state in a high-temperature environment, broadening the application range of the sliding bearing.

[0031] The nickel plating treatment of the present invention enhances the corrosion resistance of the material, and the inserted treatment enables better combination of TSP and PCD with other materials, improving the structural stability of the sliding bearing. Brief Description of the Drawings

[0032] Figure 1 This is an exploded view of the sliding bearing disclosed in Embodiment 1 of the present invention;

[0033] Figure 2 This is an exploded view of the sliding bearing disclosed in Embodiment 2 of the present invention;

[0034] Figure 3 This is an exploded view of the sliding bearing disclosed in Embodiment 3 of the present invention.

[0035] In the figures:

[0036] 10. Stationary ring; 11. First base; 12. First blind hole; 13. Third blind hole; 14. First friction part; 15. Third friction part;

[0037] 20. Rotating ring; 21. Second base; 22. First base seat; 23. Second blind hole; 24. Fourth blind hole; 25. Second friction part; 26. Fourth friction part;

[0038] 30. Water channel. Detailed Description of the Invention

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] The present invention will be further described in detail below with reference to the accompanying drawings:

[0041] Embodiment 1:

[0042] As shown in Figure 1 , the present invention provides a sliding bearing, including: a stationary ring 10 and a rotating ring 20, with the stationary ring 10 sleeved on the rotating ring 20; wherein,

[0043] The stationary ring 10 includes a first base 11 that is integrally circular ring-shaped. The first base 11 has a relative first inner cylindrical surface and a first outer cylindrical surface. A plurality of first blind holes 12 are provided on the first inner cylindrical surface. The plurality of first blind holes 12 are arranged in three circles along the circumferential direction of the first base, and the plurality of first blind holes 12 in each circle are spaced apart. The blind holes 12 are cylindrical; a first friction part 14 is fixed in each first blind hole 12, and one side of the first friction part 14 exposes the first inner cylindrical surface.

[0044] The moving ring 20 includes a second base body 21 and a first base 22 that are integrally circular ring-shaped. The second base body 21 has a relative second inner cylindrical surface and a second outer cylindrical surface. A plurality of second blind holes 23 are provided on the second outer cylindrical surface. The plurality of second blind holes 23 are arranged in three circles along the circumferential direction of the second base body, and the plurality of second blind holes 23 in each circle are spaced apart. A second friction part 25 is fixed in each second blind hole 23, and one side of the second friction part 25 exposes the second outer cylindrical surface.

[0045] The first base 22 is sleeved on one end of the second base body 21. When the static ring 10 is sleeved on the moving ring 20, the bottom surface of the first base body 11 abuts against the top surface of the first base 22. A plurality of third blind holes 13 are provided on the bottom surface of the first base body 11. The plurality of third blind holes 13 are arranged in one circle along the circumferential direction of the first base body, and the plurality of third blind holes 13 in each circle are evenly spaced. A third friction part 15 is fixed in each third blind hole 13, and one side of the third friction part 15 exposes the bottom surface of the first base body 11. A plurality of fourth blind holes 24 are provided on the top surface of the first base 22. The plurality of fourth blind holes 24 are arranged in one circle along the circumferential direction of the first base 22, and the plurality of fourth blind holes 24 in each circle are evenly spaced. A fourth friction part 26 is fixed in each fourth blind hole 24, and one side of the fourth friction part 26 exposes the top surface of the first base 22.

[0046] All the first friction parts 14 and all the second friction parts 25 are correspondingly arranged to form a sliding friction pair; all the third friction parts 15 and all the fourth friction parts 26 are correspondingly arranged to form a sliding friction pair; wherein, the corresponding first friction part 14 and second friction part 25 are a TSP friction part, a PCD friction part, a nickel-plated TSP friction part, a nickel-plated PCD friction part, an inserted TSP friction part or an inserted PCD friction part; the corresponding third friction part 15 and fourth friction part 26 are a TSP friction part, a PCD friction part, a nickel-plated TSP friction part, a nickel-plated PCD friction part, an inserted TSP friction part or an inserted PCD friction part; preferably, the corresponding first friction part 14 and second friction part 25, the corresponding third friction part 15 and fourth friction part 26 are a nickel-plated TSP friction part, a nickel-plated PCD friction part, an inserted TSP friction part or an inserted PCD friction part.

[0047] Further, the materials of the corresponding first friction part 14 and second friction part 25, the corresponding third friction part 15 and fourth friction part 26 are the same; that is, they are all nickel-plated TSP friction parts, all nickel-plated PCD friction parts, all inserted TSP friction parts or all inserted PCD friction parts; different combinations of nickel-plated TSP friction parts, nickel-plated PCD friction parts, inserted TSP friction parts and inserted PCD friction parts can also be adopted for the friction parts in different circles on the same static ring and moving ring, or different combinations of nickel-plated TSP friction parts, nickel-plated PCD friction parts, inserted TSP friction parts and inserted PCD friction parts can also be adopted for the friction parts in the same circle on the same static ring and moving ring.

[0048] Further, the heat-stable polycrystalline diamond friction part is a silicon-based polycrystal, and the polycrystalline diamond friction part is a cobalt-based polycrystal. The axial spacing between two adjacent turns of the first friction parts is the same as the axial spacing between two adjacent turns of the second friction parts, and the axial spacing between two adjacent turns of the third friction parts is the same as the axial spacing between two adjacent turns of the fourth friction parts.

[0049] Further, the difference between the first friction part of the stationary ring and the second friction part of the rotating ring is 10 μm to 50 μm; the shape of the first friction part, the second friction part, the third friction part or the fourth friction part includes one of a cylindrical shape and a cubic shape. When formed into a cylindrical shape, the diameter of the first friction part, the second friction part, the third friction part or the fourth friction part is 2 mm to 20 mm, the total height is 1 mm to 10 mm, and the exposed height is 0 to 3 mm.

[0050] Further, the nickel-plated TSP friction part or the nickel-plated PCD friction part includes a TSP friction part or a PCD friction part, and a nickel-plated layer formed on the outside thereof; wherein, the thickness of the nickel-plated layer is 0.05 mm to 0.30 mm; the inserted TSP friction part or the inserted PCD friction part includes a TSP friction part or a PCD friction part, and a metal inserted layer formed on the outside thereof; wherein, the thickness of the metal inserted layer is 0.50 mm to 5 mm.

[0051] Further, the first friction part, the second friction part, the third friction part or the fourth friction part is fixedly welded in the corresponding first blind hole, second blind hole, third blind hole or fourth blind hole; wherein, the welding method includes one of vacuum brazing, high-frequency brazing and flame spraying.

[0052] The present invention provides a preparation method of a sliding bearing, including:

[0053] S1. Synthesize TSP and PCD under high temperature and high pressure by using a cubic press;

[0054] S2. Nickel-plate the TSP and PCD to obtain nickel-plated TSP and nickel-plated PCD;

[0055] S3. Bond the TSP or PCD to the lower pressing head of a graphite mold, and assemble it with the middle mold of the graphite mold; fill metal powders (WC, Ni powder, etc.) into the gap between the TSP or PCD and the middle mold. After filling, install the upper pressing head, sinter at 800 - 1200 °C in a hot pressing sintering machine for 1 - 30 min, and take out the synthesized sample after cooling to obtain the inserted TSP or the inserted PCD;

[0056] S4. Machine process TSP, PCD, nickel-plated TSP, nickel-plated PCD, inserted TSP and inserted PCD to obtain TSP friction parts, PCD friction parts, nickel-plated TSP friction parts, nickel-plated PCD friction parts, inserted TSP friction parts or inserted PCD friction parts with required dimensions;

[0057] S5. Drill holes and process the bases of the stationary ring and the rotating ring, and weld and fix the TSP friction parts, PCD friction parts, nickel-plated TSP friction parts, nickel-plated PCD friction parts, inserted TSP friction parts or inserted PCD friction parts in the corresponding blind holes to form the final sliding bearing.

[0058] Embodiment 2:

[0059] As Figure 2 shown, the present invention provides a sliding bearing. Different from Embodiment 1, the first base 11 of the stationary ring 10 can be a split structure.

[0060] Embodiment 3:

[0061] As Figure 3 shown, the present invention provides a sliding bearing. Different from Embodiment 1, the blind holes on the first base 11 of the stationary ring 10 and the second base 21 of the rotating ring 20 are square holes, and the shapes of the corresponding friction parts are square; meanwhile, water channels 30 for facilitating the flow of lubricating oil can also be selected to be opened on the stationary ring 10 and the rotating ring 20.

[0062] The advantages of the present invention are as follows:

[0063] By applying TSP and PCD materials, the present invention significantly improves the wear resistance of the sliding bearing, greatly prolongs its service life under harsh working conditions such as high speed and heavy load; meanwhile, the metal binder of TSP is removed, reducing the internal stress caused by metal expansion at high temperature, so it is more stable in a high-temperature environment and not prone to delamination or failure, enabling the sliding bearing to maintain a good operating state in a high-temperature environment and broadening the application range of the sliding bearing.

[0064] The nickel-plating treatment of the present invention enhances the corrosion resistance of the material, and the inserted treatment enables better combination of TSP and PCD with other materials, improving the structural stability of the sliding bearing.

[0065] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A sliding bearing, characterized in that, Comprising: A stationary ring and a rotating ring, the stationary ring being sleeved on the rotating ring; The stationary ring includes a first base body which is integrally annular, the first base body having opposite first inner cylindrical surface and first outer cylindrical surface, a plurality of first blind holes being provided on the first inner cylindrical surface, the plurality of first blind holes being arranged along the circumferential direction of the first base body for at least one circle and the plurality of first blind holes in each circle being spaced apart; a first friction part is fixed in each of the first blind holes, one side of the first friction part exposing the first inner cylindrical surface; The rotating ring includes a second base body which is integrally annular, the second base body having opposite second inner cylindrical surface and second outer cylindrical surface, a plurality of second blind holes being provided on the second outer cylindrical surface, the plurality of second blind holes being arranged along the circumferential direction of the second base body for at least one circle and the plurality of second blind holes in each circle being spaced apart, a second friction part being fixed in each of the second blind holes, one side of the second friction part exposing the second outer cylindrical surface; All the first friction parts and all the second friction parts are arranged in correspondence to form a sliding friction pair; wherein, the corresponding first friction part and second friction part are a thermally stable polycrystalline diamond friction part, a polycrystalline diamond friction part, a nickel-plated thermally stable polycrystalline diamond friction part, a nickel-plated polycrystalline diamond friction part, an inserted thermally stable polycrystalline diamond friction part or an inserted polycrystalline diamond friction part.

2. The sliding bearing according to claim 1, wherein The rotating ring includes a first base which is integrally annular, the first base being sleeved on one end of the second base body, when the stationary ring is sleeved on the rotating ring, the bottom surface of the first base body abutting against the top surface of the first base; A plurality of third blind holes are provided on the bottom surface of the first base body, the plurality of third blind holes being arranged along the circumferential direction of the first base body for at least one circle and the plurality of third blind holes in each circle being spaced apart; a third friction part is fixed in each of the third blind holes, one side of the third friction part exposing the bottom surface of the first base body; A plurality of fourth blind holes are provided on the top surface of the first base, the plurality of fourth blind holes being arranged along the circumferential direction of the first base for at least one circle and the plurality of fourth blind holes in each circle being spaced apart; a fourth friction part is fixed in each of the fourth blind holes, one side of the fourth friction part exposing the top surface of the first base; All the third friction parts and all the fourth friction parts are arranged in correspondence to form a sliding friction pair; wherein, the corresponding third friction part and fourth friction part are a thermally stable polycrystalline diamond friction part, a polycrystalline diamond friction part, a nickel-plated thermally stable polycrystalline diamond friction part, a nickel-plated polycrystalline diamond friction part, an inserted thermally stable polycrystalline diamond friction part or an inserted polycrystalline diamond friction part.

3. The sliding bearing according to claim 2, characterized in that, The materials of the corresponding first friction part and second friction part are the same, and the materials of the corresponding third friction part and fourth friction part are the same.

4. The sliding bearing according to any one of claims 1 to 3, characterized in that, The thermally stable polycrystalline diamond friction part is a silicon-based polycrystal, and the polycrystalline diamond friction part is a cobalt-based polycrystal.

5. The sliding bearing according to any one of claims 1 to 3, wherein The difference between the first friction part of the stationary ring and the second friction part of the rotating ring is 10 μm to 50 μm; The shape of the first friction part, the second friction part, the third friction part or the fourth friction part includes one of a cylindrical shape and a cubic shape. When formed into a cylindrical shape, the diameter of the first friction part, the second friction part, the third friction part or the fourth friction part is 2 mm to 20 mm, the total height is 1 mm to 10 mm, and the exposed height is 0 to 3 mm.

6. The sliding bearing according to claim 5, wherein The nickel-plated thermally stable polycrystalline diamond friction part or the nickel-plated polycrystalline diamond friction part includes a thermally stable polycrystalline diamond friction part or a polycrystalline diamond friction part, and a nickel-plated layer formed on the outside thereof; wherein, the thickness of the nickel-plated layer is 0.05 mm to 0.30 mm; The encapsulated thermally stable polycrystalline diamond friction part or the encapsulated polycrystalline diamond friction part includes a thermally stable polycrystalline diamond friction part or a polycrystalline diamond friction part, and a metal encapsulation layer formed on the outside thereof; wherein, the thickness of the metal encapsulation layer is 0.50 mm to 5 mm.

7. The sliding bearing according to any one of claims 1 to 3, characterized in that, The first friction part, the second friction part, the third friction part or the fourth friction part is welded and fixed in the corresponding first blind hole, second blind hole, third blind hole or fourth blind hole; wherein, the welding method includes one of vacuum brazing, high-frequency brazing and flame spraying.

8. A method for manufacturing a sliding bearing according to any one of claims 1 to 7, characterized in that, Comprising: Synthesizing thermally stable polycrystalline diamond and polycrystalline diamond by using a cubic press; Nickel-plating the thermally stable polycrystalline diamond and the polycrystalline diamond to obtain nickel-plated thermally stable polycrystalline diamond and nickel-plated polycrystalline diamond; Gluing the thermally stable polycrystalline diamond or the polycrystalline diamond to the lower punch of the graphite mold, and assembling it with the middle mold of the graphite mold; filling metal powder in the gap between the thermally stable polycrystalline diamond or the polycrystalline diamond and the middle mold, installing the upper punch after filling, sintering at 800 - 1200 °C in a hot pressing sintering machine for 1 - 30 min, and taking out the synthesized sample after cooling to obtain the encapsulated thermally stable polycrystalline diamond or the encapsulated polycrystalline diamond; Machining the thermally stable polycrystalline diamond, the polycrystalline diamond, the nickel-plated thermally stable polycrystalline diamond and the nickel-plated polycrystalline diamond, the encapsulated thermally stable polycrystalline diamond and the encapsulated polycrystalline diamond to obtain thermally stable polycrystalline diamond friction parts, polycrystalline diamond friction parts, nickel-plated thermally stable polycrystalline diamond friction parts, nickel-plated polycrystalline diamond friction parts, encapsulated thermally stable polycrystalline diamond friction parts and encapsulated polycrystalline diamond friction parts with required sizes; Drilling and machining the substrates of the stationary ring and the rotating ring, and welding and fixing the thermally stable polycrystalline diamond friction part, the polycrystalline diamond friction part, the nickel-plated thermally stable polycrystalline diamond friction part, the nickel-plated polycrystalline diamond friction part, the encapsulated thermally stable polycrystalline diamond friction part and the encapsulated polycrystalline diamond friction part in the corresponding blind holes to form the final sliding bearing.

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