CN110041699B - Composite material for sliding bearing, sliding bearing and preparation method thereof - Google Patents

Abstract

The invention discloses a composite material for a sliding bearing, the sliding bearing and a preparation method thereof. The composite material for the sliding bearing comprises the following raw materials: titanium nitride, nylon, 1-3% of samarium oxide, aramid pulp, magnesium carbonate, polytetrafluoroethylene and graphite. The sliding bearing prepared by the raw materials and the method has obviously improved compression resistance, fatigue resistance, impact resistance, bearing capacity, friction and wear resistance, high temperature resistance and environmental protection requirements.

Description

Composite material for sliding bearing, sliding bearing and preparation method thereof

Technical Field

The invention belongs to the technical field of sliding bearings, and particularly relates to a composite material for a sliding bearing, which is used for the automobile industry, mining machinery, agricultural machinery, metallurgical machinery and the like, a sliding bearing using the composite material and a preparation method thereof.

Background

The sliding bearing is a wear-resistant part which is necessary to be used for rotation in various mechanical industries, and is particularly widely applied to industries such as automobile industry, logistics machinery, agricultural machinery, mining machinery, metallurgical machinery and the like. With the improvement of the requirements on mechanical properties, the requirements on the sliding bearing are higher and higher, and the original material cannot meet the requirements of modern industry, such as the high temperature resistance, frictional wear resistance, bearing performance, environmental protection and the like of the material, so that the replacement of the original material by the better material is the biggest task and challenge of manufacturers.

The surface wear-resistant layer materials used for the sliding bearing at present comprise copper alloy, modified polytetrafluoroethylene and modified polyformaldehyde, which have the following advantages and disadvantages: if the lubricating condition of the copper alloy material is poor, the friction coefficient is relatively large, and the frictional wear performance is poor; the wear-resistant layer of the modified Polytetrafluoroethylene (PTFE) is thin, and the service life is not very long; modified Polyoxymethylene (POM) is not high in polymerization degree and is susceptible to thermal depolymerization, and therefore is not high in heat resistance for a long period of time. Moreover, the above materials all contain lead in order to improve the fatigue resistance of the materials, and lead is a heavy metal material, is a toxic substance, and is limited in many mechanical manufacturing along with the increasing requirements of people on environmental protection. Therefore, the invention aims to solve the problems of high temperature resistance of the plastic surface of the sliding bearing, no deformation of the wear-resistant layer under the condition of cold nitrogen assembly, fatigue resistance and wear resistance of the wear-resistant layer, complete lead-free of the wear-resistant layer and the like.

Disclosure of Invention

The invention provides a composite material for a sliding bearing, which has obviously improved compression resistance, fatigue resistance, impact resistance, bearing capacity, frictional wear resistance and high temperature resistance, and the sliding bearing using the composite material and a preparation method thereof, and solves the problems in the prior art.

The technical scheme adopted by the invention for solving the technical problems is as follows:

on one hand, the invention provides a composite material for a sliding bearing, which comprises the following raw materials by taking the total mass of the raw materials as 100 percent:

0.3-1.0% of titanium nitride;

85-92% of nylon;

1-3% of samarium oxide;

3-8% of aramid pulp;

1-3% of magnesium carbonate;

3-10% of polytetrafluoroethylene;

0.5-1% of graphite.

Preferably, the titanium nitride is nano titanium nitride, the nylon is nylon 46, the magnesium carbonate is industrial magnesium carbonate, and the preferable mass percentages of the raw materials are as follows:

0.5 percent of nano titanium nitride;

the nylon 46 accounts for 89-91%;

1% of samarium oxide;

3-5% of aramid pulp;

1% of industrial-grade magnesium carbonate;

3-5% of polytetrafluoroethylene;

0.5 percent of graphite.

In another aspect, the present invention also provides a sliding bearing using the above composite material for a sliding bearing, comprising:

a load bearing substrate;

a surface composite layer made of the composite material for the sliding bearing.

Preferably, the load-bearing substrate comprises a steel backing layer and a bronze layer, the bronze layer is lead-free bronze, and the steel backing layer is cold-rolled carbon steel.

Furthermore, the thickness of the steel back layer is 0.60-0.65 mm smaller than that of the finished plate, the thickness of the bronze layer is 0.25-0.35 mm, and the thickness of the surface composite layer is 0.30-0.40 mm.

On the other hand, the invention also provides a preparation method of the sliding bearing, which comprises the following steps:

s1, mixing the raw materials for preparing the surface composite layer in proportion to obtain powder;

s2, heating the bearing substrate to raise the temperature;

s3, paving the powder obtained in the step S1 on the surface of the bearing substrate heated in the step S2;

s4, sintering the bearing substrate coated with the coating powder in the step S3 to obtain a composite plate blank;

s5, rough rolling the composite plate blank obtained in the step S4;

s6, preheating the composite plate blank after rough rolling in the step S5;

s7, carrying out secondary sintering on the composite plate blank obtained in the step S6;

and S8, finish rolling to obtain a finished plate, and producing the shaft sleeve according to requirements.

Preferably, the mixing time in step S1 is not less than 60 minutes.

Preferably, in the step S2, the temperature of the bearing substrate is raised to 60-70 ℃;

in the step S4, the sintering temperature is 325-345 ℃, and the sintering time is 10-15 minutes;

in the step S6, the preheating temperature of the composite plate blank is 50-60 ℃;

in the step S7, the secondary sintering temperature is 320-340 ℃, and the sintering time is 10-15 minutes.

In the step S5, the thickness of the composite plate blank after rough rolling is 0.12-0.15 mm larger than that of the finished plate.

Further, the preparation method of the bearing matrix comprises the following steps:

s01, polishing and roughening one surface of the steel back layer, and paving bronze powder on the polished surface;

and S02, sintering the steel back layer coated with the bronze powder under the protection of hydrogen-nitrogen mixed gas, wherein the sintering temperature is 920-930 ℃, and cooling to obtain the bearing substrate.

The properties of the raw materials used in the invention are as follows:

nylon 46: (1) excellent short-term and long-term heat resistance, wherein the heat distortion temperature of the nylon 46 is 290 ℃, and the long-term use temperature is 170 ℃; (2) the high rigidity can be kept at high temperature, and the high rigidity can be still kept when the crystallinity of the nylon 46 is close to the melting point of the nylon, so that the safety coefficient of the nylon is higher in occasions with higher requirements; (3) high creep resistance, especially at high temperatures, engineering plastics with best performance and longest life have higher creep resistance under long-term loading; (4) excellent toughness, high crystallization rate, and forming a plurality of small crystal spherulites, which is better than the toughness of other engineering plastics; (5) excellent fatigue strength and wear resistance, the high crystallinity and good crystalline structure of nylon 46 make it have better fatigue strength than most engineering plastics and heat resistant plastics, nylon 46 also has excellent wear resistance, smooth and strong surface, and the rigidity at high temperature makes it an ideal material for sliding parts; (6) good chemical resistance.

Polytetrafluoroethylene: (1) the friction coefficient is small, and because the mutual attraction among the Polytetrafluoroethylene (PTFE) macromolecules is small and the attraction of the surface to other molecules is small, the friction coefficient is very small, the static friction coefficient is only 0.04, and the creeping phenomenon can not occur at an extremely low sliding speed; (2) excellent ageing resistance and radiation resistance, the performance is unchanged in a harsh environment, and 50% of the original tensile strength can be maintained in vacuum; (3) excellent chemical stability, acid and alkali resistance, and resistance to various organic solvents, and is almost insoluble in all solvents; (4) high temperature resistance, and the use temperature is from-250 ℃ to 260 ℃; (5) outstanding surface non-tackiness and good self-lubricity; (6) the thermal stability is very good, the fracture strength is about 5MPa at 260 ℃ and the yield strength reaches 1.4MPa, which is higher than that of other common high polymers.

Aramid pulp: the aramid pulp is obtained by performing surface fibrillation treatment on aramid fibers, has rich hairiness, high strength, good size stability, no brittleness, high temperature resistance, corrosion resistance, toughness, small shrinkage, good wear resistance, large surface area and strong holding power, can be well combined with other substances, and can be used as reinforcing fibers to be applied to friction and sealing products. The aramid pulp is used as a reinforcing material for reinforced plastics, can improve the tensile strength of materials with different characteristics by connecting the materials in series through fiber tissues, has the characteristics of good impact resistance, fatigue resistance, chemical stability, low expansion and the like, and has good heat resistance, and the strength is not influenced when the temperature reaches 300 ℃. Therefore, the aramid pulp can be added to greatly improve the bearing capacity, the heat resistance, the fatigue strength and the frictional wear performance of the sliding bearing material.

Graphite: graphite is an important solid lubricant and has high temperature resistance and chemical stability.

Nano titanium nitride: the nano titanium nitride powder is used in thermoplastic engineering plastic nylon 46 and can be used as a crystallization nucleating agent, and the nano titanium nitride is better dispersed in the nylon 46 engineering plastic in a polymerization mode, so that the crystallization rate of the nylon 46 engineering plastic can be greatly accelerated, and the forming is simple. Meanwhile, a plurality of nano titanium nitride particles are dispersed in the nylon 46, and the wear resistance and the impact resistance of the nylon 46 engineering plastic can be greatly improved due to the nano effect.

Samarium oxide: the surface of the filler is subjected to activation treatment, so that the interface bonding effect between the filler and the base material is improved, the reinforcing effect is further improved, and the purposes of high strength and good wear resistance of the self-lubricating bearing material are achieved.

Chemical grade magnesium carbonate: the magnesium carbonate has excellent physical and chemical properties such as lubricity, anti-sticking property, flow aid, fire resistance, acid resistance, insulativity, high melting point, chemical inactiveness, softness, strong adsorbability and the like, and has the tendency of splitting into scales and special lubricity due to the layered crystal structure of the magnesium carbonate, so that the shape stability of products can be improved, the tensile strength, the shear strength, the flexural strength and the pressure strength can be increased, and the characteristics such as deformation, the elongation, the thermal expansion coefficient and the like can be reduced.

The invention adopts the structure and has the following advantages:

the sliding bearing prepared by the raw materials and the method has the advantages that the components of the raw materials are cooperated, so that the compression resistance, the fatigue resistance, the impact resistance, the bearing capacity, the friction and wear resistance, the high temperature resistance and the environmental protection requirement of the bearing are obviously improved.

The composite material for the sliding bearing is prepared by matching nylon 46 with raw materials with different proportions, the influence of the raw materials on the friction coefficient and the abrasion loss of the bearing is explored, and the problem that the normal production cannot be carried out due to the fact that the nylon 46 is particularly sticky and is stuck to a roller during rolling is solved through the matching of the raw materials. The nano titanium nitride is used as a crystallization nucleating agent, and is better dispersed in nylon 46 engineering plastic in a polymerization mode, so that the crystallization rate of nylon 46 can be greatly accelerated, and if the nano titanium nitride is not added, the abrasion loss is larger under the condition of bearing larger force. The aramid pulp can increase the bonding force among materials so as to enhance the plastic deformation of the modified nylon 46; if the materials such as common polytetrafluoroethylene, glass fiber and graphite are added, the abrasion loss is large under large force, which is not beneficial to the service life of the bushing; however, too large or too small addition amounts of magnesium carbonate and graphite cause an increase in the amount of wear of the bearing.

Drawings

FIG. 1 is a schematic structural diagram of a bearing manufactured by the present invention.

FIG. 2 is a schematic view showing the operation of the special fixture used in the bonding strength test of the present invention.

In the figure, 1, a surface composite layer, 2, a bronze layer, 3 and a steel back layer.

The specific implementation mode is as follows:

in order to more clearly explain the overall concept of the present application, the following detailed description is given by way of example in conjunction with the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the invention.

Unless otherwise specified, each raw material is commercially available in this specification.

In this embodiment, the composite material for a sliding bearing includes the following raw materials, based on 100% of the total mass of the raw materials:

0.3-1.0% of nano titanium nitride, and the granularity is 300 meshes;

the nylon 46 accounts for 85-92% and has the granularity of 200 meshes;

1-3% of samarium oxide and 300-mesh granularity;

aramid pulp accounts for 3-8%, and the granularity is 200 meshes;

1-3% of industrial magnesium carbonate, and the granularity is 300 meshes;

3-10% of polytetrafluoroethylene and 200-mesh granularity;

0.5-1% of graphite and 300-mesh granularity;

the sliding bearing using the composite material for the sliding bearing comprises a bearing substrate and a surface composite layer, wherein a lubricating oil hole is rolled on the surface composite layer, and the surface composite layer is made of the composite material for the sliding bearing, as shown in figure 1; the bearing substrate comprises a steel back layer and a bronze layer, the bronze layer is lead-free bronze, the steel back layer is cold-rolled carbon steel, and all the layers are tightly combined. Wherein, the thickness of the steel back layer is 0.60-0.65 mm less than that of the finished board, the thickness of the bronze layer is 0.25-0.35 mm, and the thickness of the surface composite layer is 0.30-0.40 mm.

The preparation method of the sliding bearing comprises the following steps:

s1, mixing the raw materials for preparing the surface composite layer in proportion, and mixing in a material mixer to obtain material powder, wherein the mixing is uniform, and the mixing time is not less than 60 minutes;

s2, preheating the bearing substrate in a mesh belt drying furnace, wherein the temperature of the drying furnace is set to be 170-180 ℃, and the temperature of a discharging plate is controlled to be 60-70 ℃;

s3, uniformly paving the powder obtained in the step S1 on the surface of the bearing substrate heated in the step S2 by using a mold;

s4, putting the bearing substrate coated with the coating powder in the step S3 into a six-temperature-zone mesh belt heating furnace, heating the bearing substrate at 320-345 ℃ for 11-12 minutes until the powder is completely melted and adsorbed on the surface of a bronze layer of the bearing substrate, and discharging the bearing substrate to obtain a composite plate blank;

s5, uniformly rolling the melted powder in gaps and on the surface of a bronze layer of the bearing substrate by using a rolling mill to obtain a composite plate blank, wherein the thickness of the composite plate blank is 0.12-0.15 mm greater than the required thickness of a finished plate;

s6, preheating the composite plate blank after rough rolling in the step S5 in a mesh belt drying furnace, wherein the temperature of the drying furnace is set to be 160-170 ℃, and the temperature of the plate discharged from the furnace is controlled to be 50-60 ℃;

s7, placing the composite plate blank obtained in the step S6 into a six-temperature-zone mesh belt heating furnace, and performing secondary sintering, wherein the sintering temperature is 320-340 ℃, and the sintering time is 10 minutes;

and S8, after discharging, finely rolling the composite plate blank obtained in the step S7 into the thickness required by the finished shaft sleeve plate, and then producing the shaft sleeve according to the drawing requirements.

In the above method, the method for preparing the carrier substrate comprises:

s01, selecting a steel tape or a steel plate with the mark of SPCC as a substrate, rolling until the thickness required by the production of a finished plate is reduced by 0.60-0.65 mm, polishing and roughening one surface of the substrate by using an abrasive belt after leveling, cleaning and drying, paving lead-free bronze ball powder CuSn8Zn3 on the polished surface, wherein the granularity is 60-80 meshes, the paving thickness is 0.25-0.35 mm, and the furnace discharge thickness is 0.30-0.35 mm smaller than the thickness of the finished plate;

and S02, sintering the steel back layer coated with the bronze powder under the protection of tunnel type hydrogen-nitrogen mixed gas, wherein the sintering temperature is 920-930 ℃, and cooling for 80 minutes to obtain the bearing substrate. Wherein the hydrogen content in the mixed gas is 30 percent, and the nitrogen content is 70 percent.

Unless otherwise stated, the following examples all employ the above-described method, and differ only in specific treatment time and adjustment within the desired range. Wherein the proportions of the raw materials of the surface composite layers in examples 1-4 are shown in Table 1:

TABLE 1 proportions of the respective raw materials of the surface composite layer

In order to fully verify the performance of the composite material for a sliding bearing of the present invention, the following description will be made by taking the test results and investigating the influence of the kind and amount of the raw materials on the bearing performance.

1. Friction and wear test:

after the finished shaft sleeve plate is manufactured, a friction wear test is carried out by adopting a grease lubrication method according to the requirements of the Q/YH-3(PA46) type composite material sliding shaft sleeve technical conditions (trial) of 5.4 on the load of 24.5MPa and the time of 180 minutes.

The test termination conditions were: when the temperature exceeds 200 ℃, the system automatically alarms and stops.

The test result requires that: the average friction coefficient should not exceed 0.15 and the abrasion loss should not exceed 0.15 mm.

TABLE 2 results of frictional wear test of shaft sleeve plates obtained in examples 1 to 4

Grouping	Coefficient of friction	Amount of wear
			Example 1	0.018	0.028
Example 2	0.019	0.03
			Example 3	0.018	0.028
Example 4	0.019	0.028
			Standard requirements	≤0.15	≤0.15

As can be seen from the data in Table 2, the wear resistance of the shaft sleeve plate is excellent.

TABLE 3 influence of the type and amount of raw materials on the Properties of the Sleeve plates

As can be seen from the data in Table 3, the addition of different raw materials and the proportion of the raw materials have direct influence on the friction coefficient and the abrasion loss of the material. Because nylon 46 is particularly sticky and is stuck to a roller during rolling, normal production cannot be carried out, and if the materials such as common polytetrafluoroethylene, glass fiber and graphite are added, the abrasion loss of the materials is larger when the materials are stressed by larger force, which is not beneficial to the service life of the bushing. In the case where the glass fiber is changed to aramid pulp, the amount of abrasion of the material is remarkably reduced. When magnesium carbonate is added singly, the proportion of 3 percent is best, and cannot be more than 5 percent, otherwise, the abrasion loss is increased; after the magnesium carbonate is mixed with polytetrafluoroethylene, aramid pulp and nano titanium nitride, the abrasion loss of 3 percent of magnesium carbonate is larger than that of 1 percent of magnesium carbonate. When 3% of graphite is added, the abrasion loss of the graphite, 5% of polytetrafluoroethylene and 5% of aramid pulp is larger than that of the graphite added with 1%. The amount of wear is also greater without the addition of titanium nitride if subjected to large forces. Repeated experiments finally show that the abrasion loss of the raw materials used in the invention is minimum under the conditions of larger force and smaller force.

2. Bond strength test

The bushing plates obtained in examples 1 to 4 were manufactured into samples of 120mm × 20mm × the actual thickness of the plate material with reference to GB/T27553.2-2011, clamped in a special fixture as shown in fig. 2, and then the samples were first bent at an angle of 60 ° toward the plastic and then bent at an angle of 60 ° toward the steel back once, for a total of five times. The samples were observed to have no delamination, flaking, or falling off at every bend.

3. Other non-specified items are executed according to GB/T27553.2-2011 relevant requirements.

The above-described embodiments should not be construed as limiting the scope of the invention, and any alternative modifications or alterations to the embodiments of the present invention will be apparent to those skilled in the art.

The present invention is not described in detail, but is known to those skilled in the art.

Claims (9)

1. The composite material for the sliding bearing is characterized by comprising the following raw materials by taking the total mass of the raw materials as 100 percent:

0.5 percent of nano titanium nitride;

the nylon 46 accounts for 89-91%;

1% of samarium oxide;

3-5% of aramid pulp;

1% of industrial-grade magnesium carbonate;

3-5% of polytetrafluoroethylene;

0.5 percent of graphite.

2. A sliding bearing using the composite material for a sliding bearing according to claim 1, characterized by comprising:

a load bearing substrate;

a surface composite layer made of the composite material for the sliding bearing.

3. A sliding bearing according to claim 2, wherein the load-bearing substrate comprises a steel backing layer and a bronze layer, the bronze layer being a lead-free bronze and the steel backing layer being cold-rolled carbon steel.

4. The plain bearing according to claim 3, wherein the thickness of the steel backing layer is 0.60 to 0.65mm smaller than that of the finished plate, the thickness of the bronze layer is 0.25 to 0.35mm, and the thickness of the surface composite layer is 0.30 to 0.40 mm.

5. A method of manufacturing a plain bearing according to claim 2, comprising the steps of:

s1, mixing the raw materials for preparing the surface composite layer in proportion to obtain powder;

s2, heating the bearing substrate to raise the temperature;

s3, paving the powder obtained in the step S1 on the surface of the bearing substrate heated in the step S2;

s4, sintering the bearing substrate coated with the coating powder in the step S3 to obtain a composite plate blank;

s5, rough rolling the composite plate blank obtained in the step S4;

s6, preheating the composite plate blank after rough rolling in the step S5;

s7, carrying out secondary sintering on the composite plate blank obtained in the step S6;

and S8, finish rolling to obtain a finished plate, and producing the shaft sleeve according to requirements.

6. The method for producing a plain bearing according to claim 5, wherein the mixing time in step S1 is not less than 60 minutes.

7. The method for producing a sliding bearing according to claim 5, wherein the temperature of the bearing substrate is raised to 60 to 70 ℃ in step S2;

in the step S4, the sintering temperature is 325-345 ℃, and the sintering time is 10-15 minutes;

in the step S6, the preheating temperature of the composite plate blank is 50-60 ℃;

in the step S7, the secondary sintering temperature is 320-340 ℃, and the sintering time is 10-15 minutes.

8. The method for manufacturing a sliding bearing according to claim 5, wherein the thickness of the composite slab after rough rolling in step S5 is 0.12 to 0.15mm greater than that of the finished plate.

9. A method of manufacturing a sliding bearing according to claim 5, wherein the carrier substrate comprises a steel backing layer and a bronze layer, the method of manufacturing the carrier substrate comprising:

s01, polishing and roughening one surface of the steel back layer, and paving bronze powder on the polished surface;

and S02, sintering the steel back layer coated with the bronze powder under the protection of hydrogen-nitrogen mixed gas, wherein the sintering temperature is 920-930 ℃, and cooling to obtain the bearing substrate.

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