CN110894856A

CN110894856A - Sliding bearing with polyimide sliding layer

Info

Publication number: CN110894856A
Application number: CN201910932522.8A
Authority: CN
Inventors: 张国强; 苏荣锦; 龚颖; 倪志伟
Original assignee: COB PRECISION PARTS Inc
Current assignee: COB PRECISION PARTS Inc
Priority date: 2019-09-29
Filing date: 2019-09-29
Publication date: 2020-03-20
Also published as: WO2021056954A1; KR20210038282A

Abstract

The present invention discloses a sliding bearing having a polyimide sliding layer, the sliding bearing including: a. a substrate; b. an intermediate layer optionally disposed on the substrate; a polyimide sliding layer disposed on the substrate, the polyimide sliding layer comprising: i. a polyimide base resin; a primary lubricant dispersed within the polyimide matrix resin, the primary lubricant being an ultra high molecular weight polyethylene polymer; and optionally a filler dispersed within the polyimide matrix resin. The sliding bearing with the polyimide sliding layer provided by the invention contains the lubricant which is light in weight and high in toughness, effectively improves the bonding strength of the sliding layer, and can enable the sliding bearing to show excellent wear resistance.

Description

Sliding bearing with polyimide sliding layer

Technical Field

The invention relates to a bearing, in particular to a sliding bearing with a polyimide sliding layer.

Background

Plain bearings are often in the form of a layered structure comprising: a substrate (e.g., steel) that provides mechanical support; the sliding layer is arranged on the substrate, the sliding layer adopts polymer materials as a matrix and is compounded with other auxiliary agents, and the used polymers comprise polytetrafluoroethylene, polyvinylidene fluoride, polyether ether ketone, polyformaldehyde and the like. Polyimide is also gradually applied to the preparation of sliding bearings in recent years due to excellent self-lubricating and high temperature resistance properties.

Patent 200810166516.8 discloses a sliding bearing in which a sliding layer made of matrix resin of at least one of PAI resin, PBI resin and PI resin is formed on the surface of a bearing alloy by coating, wherein the sliding layer contains 3-15% by volume of film strength adjusting particles; the resin layer is also added with more than one solid lubricant of molybdenum disulfide, graphite and polytetrafluoroethylene resin with the volume ratio of 25-55%. But molybdenum disulfide (density 4.80 g/cm) added as a solid lubricant³) Graphite (density 2.25 g/cm)³) Polytetrafluoroethylene (density 2.20 g/cm)³) The density of the resin is higher, so that the addition amount of the resin is larger, the toughness of the resin is lower, the bonding strength of the resin layer is easy to reduce, and the wear rate is increased.

Disclosure of Invention

The inventors have unexpectedly found that the use of ultra-high molecular weight polyethylene as a main lubricant dispersed in the polyimide matrix resin makes it possible to provide a sliding bearing having a polyimide sliding layer which has not only excellent frictional wear properties but also low density and light weight characteristics. Compared with molybdenum disulfide, graphite, polytetrafluoroethylene and the like, the ultra-high molecular weight polyethylene has the advantages that the quality is greatly reduced under the condition of the same volume proportion adding amount, and meanwhile, the excellent frictional wear performance of the sliding bearing can be guaranteed. In addition, the toughness of the ultra-high molecular weight polyethylene is better than that of solid lubricants such as polytetrafluoroethylene, molybdenum disulfide and the like, so that the bearing capacity of the sliding bearing to impact load is improved.

Accordingly, a first object of the present invention is to provide a sliding bearing having a polyimide sliding layer, the sliding bearing including:

a. a substrate;

b. an intermediate layer optionally disposed on the substrate; and

c. a polyimide sliding layer disposed on the substrate, the polyimide sliding layer comprising:

i. a polyimide base resin;

a primary lubricant dispersed within the polyimide matrix resin, the primary lubricant being an ultra high molecular weight polyethylene polymer; and optionally a filler dispersed within the polyimide matrix resin.

According to a preferred embodiment of the invention, the substrate is a metal base material. The substrate comprises steel, stainless steel, aluminum, bronze or copper, and the substrate is preferably a steel plate.

According to another preferred embodiment of the present invention, the surface of the substrate may be subjected to a surface treatment (e.g., sand blasting, roughening, chemical etching, quenching, plating, corona treatment, or primer coating) for improving adhesion between the substrate and the sliding layer. The surface treatment is preferably sand blasting.

According to a preferred embodiment of the present invention, the surface roughness Ra of the substrate after the above surface treatment may be 0.5 to 3.0. mu.m, preferably Ra is 1.0 to 1.5. mu.m.

Further, to improve adhesion between the substrate and the sliding layer, an intermediate layer (e.g., a porous copper powder layer) may also be provided on the substrate.

According to a preferred embodiment of the present invention, the thickness of the polyimide sliding layer may be 5 μm or more, preferably 20 to 50 μm.

According to a preferred embodiment of the present invention, the polyimide base resin may be formed by thermally curing a polyimide precursor.

According to another preferred embodiment of the present invention, the polyimide precursor may be a polyamic acid solution having a solid content of 10 to 80%, preferably 15 to 30%.

As used herein, the term "ultra-high molecular weight polyethylene (UHMWPE) refers to unbranched linear polyethylene having a molecular weight of 100 ten thousand or more and the molecular formula: - (-CH)₂-CH₂-, density: 0.920-0.964 g/cm³The heat distortion temperature (0.46MPa) is 85 ℃, and the melting point is 130-.

Ultra-high molecular weight polyethylene (UHMWPE) has been produced in the prior art as ropes, cables, fishing nets and various fabrics: bulletproof vests and clothes, cutting-resistant gloves and the like, wherein the bulletproof effect of the bulletproof vest is superior to that of aramid fiber. The ultra-high molecular weight polyethylene (UHMWPE) fibers are woven into ropes with different titer abroad, and the traditional steel cables, synthetic fiber ropes and the like are replaced. Composites of ultra-high molecular weight polyethylene (UHMWPE) fibers have been used in military as housings for armored weapons, protective housings for radars, helmets, and the like; sports articles have been made with bowstrings, skis, and aquaboards, among others.

The inventors have unexpectedly found that the use of an ultra-high molecular weight polyethylene polymer as a main lubricant dispersed in the polyimide matrix resin makes it possible to provide a sliding bearing having a polyimide sliding layer which has not only excellent frictional wear properties but also low density and light weight characteristics. Thus, according to a preferred embodiment of the present invention, the molecular weight of the ultra-high molecular weight polyethylene polymer may be 100 ten thousand or more, preferably the molecular weight of the ultra-high molecular weight polyethylene polymer is 100-500 ten thousand.

According to a preferred embodiment of the present invention, the polyimide sliding layer may further include, in addition to the above-described primary lubricant, a secondary lubricant dispersed in the polyimide matrix resin, the secondary lubricant being one or more selected from the group consisting of polytetrafluoroethylene, tungsten disulfide, molybdenum disulfide, and graphite.

According to a preferred embodiment of the invention, the lubricant may have an average particle size of 0.1 to 20 μm, preferably 1 to 5 μm.

According to another preferred embodiment of the present invention, the filler is selected from one or more of aramid powder, carbon fiber powder, calcium fluoride and lithopone.

According to a preferred embodiment of the invention, the filler may have an average particle size of 0.1 to 10 μm, preferably 0.1 to 0.5 μm.

According to a preferred embodiment of the present invention, the proportion of the primary lubricant and the secondary lubricant to the total volume of the polyimide sliding layer is 10 to 60%.

When the proportion of the ultra-high molecular weight polyethylene polymer to the total volume of the polyimide sliding layer is less than 10%, the wear amount (μm/km) of the produced sliding bearing and the resulting final friction temperature are not significantly reduced; and when the proportion of the ultra-high molecular weight polyethylene polymer to the total volume of the polyimide sliding layer is more than 45%, the wear amount (μm/km) of the produced sliding bearing and the resulting final friction temperature are not further decreased. Therefore, according to another preferred embodiment of the present invention, the proportion of the ultra-high-molecular-weight polyethylene polymer to the total volume of the polyimide sliding layer is 10 to 45%, preferably 20 to 35%.

According to a preferred embodiment of the present invention, the auxiliary lubricant accounts for 15% or less of the total volume of the polyimide sliding layer.

According to another preferred embodiment of the present invention, the filler accounts for 10% or less, preferably 3% or less, of the total volume of the polyimide sliding layer.

A second object of the present invention is to provide a method for producing a sliding bearing having a polyimide sliding layer, the method comprising the steps of:

(1) preparation of the substrate

The substrate is preferably a metal substrate, more preferably a steel plate, and the surface treatment of the steel plate is preferably sandblasting. The steel sheet is first cleaned and dried, and blasting materials (e.g., glass beads, steel grit, quartz grit, silicon carbide, iron grit, etc.) are sprayed onto the surface of the steel sheet at a high speed using compressed air as a motive force to produce a substrate having a surface roughness Ra of 0.5 to 3.0 μm, preferably 1.0 to 1.5 μm.

Further, in certain preferred embodiments, an intermediate porous copper powder layer may be provided between the substrate and the sliding layer: and uniformly spreading copper powder on the steel plate, and sintering and forming by using a 840-890 ℃ high-temperature furnace to obtain the porous copper powder composite plate.

(2) Mixing material

The main lubricant, the optional auxiliary lubricant and the filler and the polyamic acid solution are proportionally placed in a stirrer, and a proper solvent is added to adjust the viscosity of the solution, and then the solution is uniformly stirred.

(3) Applying a sliding layer: the solution mixture prepared above is applied to the substrate after the treatment of (1), and specific methods adopted include, but are not limited to, doctor blading, brushing, spraying, roll coating and the like.

(4) Drying and curing: drying the composite board treated in the step (3) at 80-100 ℃ for 30-60min, heating to 100-120 ℃ for drying for 30-60min, heating to 150-180 ℃ for drying for 30-60min, heating to 180-200 ℃ for drying for 20-40min, heating to 210-230 ℃ for curing for 20-40min, and finally heating to 240-260 ℃ for curing for 20-40 min. The drying and curing process of the present invention is not limited to this, and the drying temperature and time and the curing temperature and time may be properly adjusted within the temperature range of room temperature to 260 ℃.

(5) Rolling: rolling the cured composite board on a rolling mill to reach the required thickness;

(6) molding: and stamping, rolling, shaping and turning the composite plate to manufacture the sliding bearing.

The excellent technical effects of the invention are as follows:

1. the invention adopts the polyimide resin with excellent rigidity, self-lubricating property and wear-resisting property as the sliding layer, so that the sliding bearing has excellent wear-resisting property.

2. The invention uses the ultra-high molecular weight polyethylene lubricant as the main lubricant, not only has excellent friction and wear performance, but also has the characteristics of low density and light weight. Compared with molybdenum disulfide, graphite, polytetrafluoroethylene and the like, the ultra-high molecular weight polyethylene has the advantages that the quality is greatly reduced under the condition of the same volume proportion adding amount, and meanwhile, the excellent frictional wear performance of the sliding bearing can be guaranteed.

3. The toughness of the ultra-high molecular weight polyethylene is better than that of solid lubricants such as polytetrafluoroethylene, molybdenum disulfide and the like, and the bearing capacity of the sliding bearing to impact load is improved. By adding the filler as a wear-resistant modifier, the friction characteristic of the sliding layer can be effectively adjusted, and the wear resistance of the sliding bearing is improved.

4. In conclusion, the sliding bearing prepared by the invention has the excellent characteristics of good rigidity and high strength, can show excellent wear resistance, and is suitable for sliding bearings in the fields of windscreen wipers, hydraulic motors, gear oil pumps, vane oil pumps, automobile engines, aerospace, ships and the like.

Drawings

Fig. 1 is a comparison of wear amount and friction temperature data for sliding bearings having a polyimide sliding layer manufactured using ultra-high molecular weight polyethylene polymers as main lubricants in examples 1 to 10 of the present invention and sliding bearings having a polyimide sliding layer manufactured in comparative examples 1 to 4.

FIG. 2 is a microscopic structural view showing a cross-sectional view of a two-layer sliding bearing having a polyimide sliding layer, which is manufactured in example 1 of the present invention; wherein 1, a substrate; 2. and a sliding layer.

FIG. 3 is a microscopic structural view showing a cross-sectional view of a three-layer sliding bearing having a polyimide sliding layer, which is produced in example 8 of the present invention; wherein 1, a substrate; 2. a sliding layer; 3. a porous copper powder layer.

Detailed Description

The invention is further described below by means of the attached drawings and the detailed description:

example 1

The thickness of the polyimide sliding layer in example 1 was controlled to 20. + -.5. mu.m. The polyimide base resin in the polyimide sliding layer is formed by heat curing of a polyimide precursor, which is a polyamic acid (PAA) solution having a solid content of 17%. The sliding bearing structure prepared in this example is shown in fig. 2.

The sliding bearing of the embodiment is prepared by the following method:

(1) preparation of Metal substrates

The metal substrate is a steel plate, the steel plate is firstly cleaned and dried, compressed air is used as power, and spray materials (steel grit) are sprayed to the surface of the steel plate at a high speed, so that the surface roughness Ra of the steel plate is 1.5.

(2) Mixing material

The main lubricant and the polyamic acid solution were placed in a stirrer in the ratio of table 1, and dimethylacetamide was added to adjust the solution viscosity, followed by uniform stirring.

(3) Applying a polyimide sliding layer: and (3) applying the prepared solution mixture on the metal substrate treated in the step (1) by adopting a spraying mode.

(4) Drying and curing: and (3) drying the sprayed composite board at 80 ℃ for 30min, heating to 100 ℃ for 30min, heating to 150 ℃ for 30min, heating to 180 ℃ for 20min, heating to 220 ℃ for 20min, and finally heating to 250 ℃ for 20 min.

(5) Rolling: and rolling the cured composite plate on a rolling mill to reach the required thickness of 0.80 mm.

Example 2

Example 2 is different from example 1 in the content by volume of the main lubricant in the polyimide sliding layer and the addition of the auxiliary lubricant, and the specific compounding ratio is shown in table 1.

Example 3

Example 3 is different from example 1 in the content by volume of the main lubricant in the polyimide sliding layer, and the auxiliary lubricant and the filler are added, and the specific proportions are shown in table 1.

Example 4

Example 4 is different from example 1 in the content by volume of the main lubricant in the polyimide sliding layer, and the auxiliary lubricant and the filler are added, and the specific compounding ratio is shown in table 1.

Example 5

Example 5 is different from example 1 in the content by volume of the main lubricant in the polyimide sliding layer, and the auxiliary lubricant and the filler are added, and the specific compounding ratio is shown in table 1.

Example 6

Example 6 differs from example 1 in that:

(1) the surface roughness Ra after the blast treatment in the preparation of the metal substrate was 0.5.

(2) The volume contents of the main lubricant in the polyimide sliding layer are different, and the auxiliary lubricant and the filler are added, and the specific mixture ratio is shown in table 1.

Example 7

Example 7 differs from example 1 in that:

(1) the surface roughness Ra after the blast treatment in the preparation of the metal substrate was 3.0.

Example 8

The thickness of the polyimide sliding layer in example 8 was controlled to 30. + -.5 m. The polyimide base resin in the polyimide sliding layer is formed by thermally curing a polyimide precursor, which is a polyamic acid (PAA) solution having a solid content of 10%. The sliding bearing structure prepared in this example is shown in fig. 3.

The sliding bearing of the embodiment is prepared by the following method:

(1) preparation of Metal substrates

The metal substrate is a steel plate, copper powder is uniformly paved on the steel plate, and sintering molding is carried out in a 840-890 ℃ high-temperature furnace to obtain the porous copper powder composite plate.

(2) Mixing material

The main lubricant, the auxiliary lubricant, the filler and the polyamic acid solution were placed in a stirrer in the ratio of table 1, and dimethylacetamide was added to adjust the solution viscosity, followed by uniform stirring.

(4) Drying and curing: and (3) drying the sprayed composite board at 100 ℃ for 60min, heating to 120 ℃ for 60min, heating to 180 ℃ for 60min, heating to 200 ℃ for 40min, heating to 230 ℃ for 40min, and finally heating to 260 ℃ for 40 min.

(5) Rolling: the solidified composite board is rolled on a rolling mill to reach the required thickness of 2.15 mm;

Example 9

Example 9 was prepared in substantially the same manner as example 8, except that:

(1) the polyimide sliding layer has different volume contents of the main lubricant and the auxiliary lubricant and the filler, and the specific proportions are shown in table 1.

(2) The thickness of the polyimide sliding layer in this example was controlled to 15. + -.5. mu.m.

(3) The polyimide base resin in the polyimide sliding layer is formed by thermally curing a polyimide precursor, which is a polyamic acid (PAA) solution having a solid content of 80%.

(4) Drying and curing: drying the sprayed composite board at 80 ℃ for 45min, heating to 100 ℃ for 45min, heating to 170 ℃ for 45min, heating to 190 ℃ for 30min, heating to 220 ℃ for 30min, and finally heating to 240 ℃ for 30 min.

Example 10

Example 10 was prepared in substantially the same manner as example 8, except that:

(2) The thickness of the sliding layer in this embodiment is controlled to 5. + -. 1 μm.

(3) The polyimide base resin in the polyimide sliding layer is formed by thermally curing a polyimide precursor, which is a polyamic acid (PAA) solution having a solid content of 40%.

(4) Drying and curing: drying the sprayed composite board at 100 ℃ for 60min, heating to 120 ℃ for 60min, heating to 180 ℃ for 60min, heating to 200 ℃ for 40min, heating to 230 ℃ for 40min, and finally heating to 260 ℃ for 40 min.

To further illustrate the advantageous effects of the relevant technical features in the sliding bearing with a polyimide sliding layer and the method for manufacturing the same according to the present invention, the following six comparative examples were additionally carried out:

comparative examples 1 to 6

Comparative examples 1 to 6 are different from example 1 in the composition and volume content of the main lubricant, the auxiliary lubricant and the filler in the sliding layer, and the specific compounding ratio is shown in table 1, wherein the main lubricant in the sliding layer in comparative examples 5 to 6 is High Density Polyethylene (HDPE) having a molecular weight of 40 ten thousand.

Table 1: compositions of polyimide sliding layers of examples 1 to 10 of the present invention and comparative examples 1 to 6

The wear resistance of the sliding bearing plates prepared in the above examples 1 to 10 and comparative examples 1 to 6 was tested by using GB/T27553-2011 under the following test conditions, and the performance data are shown in FIG. 1.

And (3) testing conditions are as follows:

loading: 5MPa

Linear rotating speed: 0.4m/s

Time: 1h

Lubrication conditions: dry friction

And (3) grinding a part: 45# steel, hardness HRC50-55, Ra ≤ 0.80

As can be seen from fig. 1, the wear amounts (μm/km) and the resulting final friction temperatures of the sliding bearings manufactured using the ultra-high molecular weight polyethylene polymers of examples 1 to 10 of the present invention as the main lubricant were significantly less than those of the sliding bearings manufactured using PTFE of comparative examples 2 to 4 and HDPE of comparative examples 5 to 6 as the main lubricant, and thus the sliding bearings manufactured using examples 1 to 10 of the present invention had excellent wear resistance during sliding in each case.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

Claims

1. A sliding bearing having a polyimide sliding layer, the sliding bearing comprising:

a. a substrate;

b. an intermediate layer optionally disposed on the substrate; and

i. a polyimide base resin;

2. A sliding bearing with a polyimide sliding layer according to claim 1, characterized in that the thickness of the polyimide sliding layer is ≥ 5 μm, preferably 20-50 μm.

3. A sliding bearing having a polyimide sliding layer according to claim 1, characterized in that the surface of the substrate is subjected to surface treatment.

4. A sliding bearing with a polyimide sliding layer according to claim 3, characterised in that the surface treatment is selected from sandblasting, roughening, chemical etching, quenching, electroplating, corona treatment or primer coating.

5. A sliding bearing with a polyimide sliding layer according to claim 1, characterized in that the surface roughness Ra of the substrate is 0.5-3.0 μm, preferably Ra is 1.0-1.5 μm.

6. A sliding bearing with a polyimide sliding layer according to claim 1, characterised in that the intermediate layer optionally provided on the substrate is a porous copper powder layer.

7. A sliding bearing having a polyimide sliding layer according to claim 1, characterized in that the polyimide base resin is formed by heat curing of a polyimide precursor.

8. A sliding bearing with a polyimide sliding layer according to claim 7, characterised in that the polyimide precursor is a solution of a polyamic acid with a solids content of 10-80%, preferably 15-30%.

9. A sliding bearing with a polyimide sliding layer according to claim 1, characterized in that the molecular weight of the ultra-high molecular weight polyethylene polymer is equal to or more than 100 ten thousand, preferably the molecular weight of the ultra-high molecular weight polyethylene polymer is 100-500 ten thousand.

10. A sliding bearing having a polyimide sliding layer according to claim 1, characterized in that the polyimide sliding layer further comprises an auxiliary lubricant dispersed in the polyimide matrix resin, the auxiliary lubricant being selected from one or more of polytetrafluoroethylene, tungsten disulfide, molybdenum disulfide, and graphite.

11. A sliding bearing with a polyimide sliding layer according to claim 1, characterised in that the lubricant has an average particle size of 0.1-20 μm, preferably 1-5 μm.

12. A sliding bearing with a polyimide sliding layer according to claim 1, characterised in that the filler is selected from one or more of aramid powder, carbon fibre powder, calcium fluoride and lithopone.

13. A sliding bearing with a polyimide sliding layer according to claim 1, characterised in that the average particle size of the filler is 0.1-10 μm, preferably 0.1-0.5 μm.

14. A sliding bearing having a polyimide sliding layer according to any one of claims 1 to 13, characterized in that the proportion of the primary lubricant and the secondary lubricant to the total volume of the polyimide sliding layer is 10 to 60%.

15. A sliding bearing with a polyimide sliding layer according to any one of claims 1-13, characterised in that the proportion of ultra high molecular weight polyethylene polymer to the total volume of the polyimide sliding layer is 10-45%, preferably 20-35%.

16. A sliding bearing having a polyimide sliding layer according to any one of claims 1 to 13, characterized in that the proportion of the auxiliary lubricant to the total volume of the polyimide sliding layer is 15% or less.

17. A sliding bearing with a polyimide sliding layer according to any of claims 1-13, characterised in that the proportion of the filler to the total volume of the polyimide sliding layer is 10% or less, preferably 3% or less.