Antifriction coating for shaft-bush friction pair assembly, preparation method of antifriction coating and shaft-bush friction pair assembly

Abstract

The invention relates to the technical field of coating preparation, in particular to an anti-friction coating for a shaft-bushing friction pair assembly, a preparation method of the anti-friction coating and the shaft-bushing friction pair assembly. The anti-friction coating comprises a composite coating sprayed on the outer surface of a shaft and a wear-resistant coating sprayed on the inner surface of a bushing; the composite coating comprises a non-porous coating sprayed on the outer surface of the shaft and a porous coating sprayed on the surface of the non-porous coating, and the porosity of the porous coating is 25-30%. The lubricating agent is adsorbed and stored by the pores of the porous coating, and the filling rate of the lubricating agent of the porous coating can reach 93-95% of the total pore volume, so that the porous coating is fully saturated, and the lubricating agent is not easy to run off from the porous coating in the friction interaction process, so that the lubricating agent has an excellent lubricating effect, and the service life of the lubricating agent is prolonged. The lower friction coefficient between the shaft and the bushing is ensured, and the influence of the stopping effect is relieved.

Description

Technical Field

[0001] The invention relates to the technical field of coating preparation, and in particular to a friction-reducing coating for a shaft-bushing friction pair component, a preparation method thereof, and a shaft-bushing friction pair component. Background Art

[0002] In manipulators, especially under low sliding speed and high specific load conditions, the friction coefficient of conventional "shaft-bushing" friction pair components increases sharply when restarting after load cessation, resulting in the so-called "stop effect". This phenomenon causes rapid wear of the sliding surfaces of the coupling, reducing equipment performance and life.

[0003] In the prior art, a variety of methods have been designed to reduce the "stop effect". For example, patent UA 65432U provides a method for improving the durability of a cloth-reinforced bakelite sliding support, which improves its durability by heat-treating the equipment cloth-reinforced bakelite support in industrial (lubricating) oil at a temperature of 150-160°C and maintaining it for 6-7 hours. The service life of the equipment cloth-reinforced bakelite support that has undergone such heat treatment is increased under specified working conditions, and the friction coefficient of the bearing working surface is also reduced.

[0004] However, this method has limited effect on improving the wear resistance of bearing shells (bearing pads) made of cloth-reinforced bakelite. The saturation of the dispersed anti-friction materials (graphite and bronze) in the cloth-reinforced bakelite is low, and only the surface layer can be fully saturated. During the friction interaction process, the anti-friction material will be gradually removed from the friction area, resulting in a decrease in its concentration, that is, the enrichment of the lubricant components in the friction zone becomes worse, the friction coefficient increases, and the temperature of the friction pair increases. In some cases, this may cause the bearing to malfunction or even fail. Summary of the invention

[0005] The present invention is made to solve the above-mentioned problems, and its purpose is to provide a friction-reducing coating with low friction coefficient and high wear resistance, and its preparation method, and to use the friction-reducing coating in the friction action area of ​​the shaft-bushing friction pair assembly, so as to reduce the temperature of the shaft-bushing friction pair assembly during operation and increase the service life of the shaft-bushing friction pair assembly.

[0006] The first aspect of the present invention provides a friction-reducing coating for a shaft-bushing friction pair assembly, characterized in that the friction-reducing coating comprises a composite coating sprayed on the outer surface of the shaft and a wear-resistant coating sprayed on the inner surface of the bushing, the composite coating comprises a non-porous coating sprayed on the outer surface of the shaft and a porous coating sprayed on the surface of the non-porous coating, wherein the porosity of the porous coating is 25-30%.

[0007] The present invention reduces the impact of the stopping effect by arranging a friction-reducing coating on the friction surface of the shaft and the bushing. The present invention also reduces the impact of the stopping effect by arranging a non-porous coating with a small porosity, and the non-porous coating has a large strength adhesive property, so that it can be tightly adhered to the shaft, providing a basis for the adhesion of the porous coating.

[0008] Furthermore, the present invention sprays a porous coating on a non-porous coating to obtain a composite coating, and utilizes the pores of the porous coating to adsorb and store the lubricant, and the lubricant filling rate of the porous coating can reach 93-95% of the total pore volume, so that the porous coating is fully saturated. During the friction interaction process, the lubricant is not easy to lose from the porous coating, thereby having an excellent lubrication effect, ensuring a lower friction coefficient between the shaft and the bushing, and reducing the impact of the stop effect.

[0009] Furthermore, a wear-resistant coating is provided on the inner surface where the bushing rubs against the shaft to prevent the inner surface of the bushing from being severely worn during the friction process, thereby preventing problems such as expansion of the inner diameter of the bushing and friction jamming and detachment caused by incompatibility with the shaft.

[0010] In some embodiments of the present invention, the raw material of the non-porous coating includes bronze powder with a dispersion degree of 15-40 μm.

[0011] In the embodiment, the bronze powder of 15-40 μm is easier to disperse and coat, and the fine bronze powder can form a uniform coating, covering the surface of the shaft to form a dense non-porous coating. At the same time, the bronze powder of 15-40 μm can form a strong bonding force with the shaft, and the non-porous coating is not easy to fall off, laying a solid foundation for the preparation of the porous coating.

[0012] In some embodiments of the present invention, the raw materials of the porous coating include bronze powder with a dispersion of 50-315 μm and mixed particles with a dispersion of 40-63 μm, and the mixed particles include borides, carbides, and eutectoid alloys.

[0013] In the embodiment, the porosity of the porous coating is precisely controlled by mixing particles of different sizes. At the same time, borides and carbides have high hardness, strength and thermal stability, which can enhance the mechanical properties and thermal stability of the porous coating, so that it can remain stable even when the local heating temperature is high during friction.

[0014] In some embodiments of the present invention, the raw materials of the wear-resistant coating include carbon fiber, molybdenum disulfide, chromium oxide and epoxy resin.

[0015] Epoxy resin has good bonding properties and is easy to process. Using epoxy resin as a bonding base to prepare a wear-resistant coating can ensure that the wear-resistant coating has a strong bond with the bushing and is not easy to fall off. At the same time, carbon fiber has high strength and modulus, which can enhance the mechanical properties of the coating and make it tougher. Molybdenum disulfide has strong wear resistance, chromium oxide has high hardness, and both carbon fiber and chromium oxide can remain stable at high temperatures. The wear-resistant coating made of them has high thermal stability, mechanical strength, hardness and scratch resistance. Molybdenum disulfide is also an excellent solid lubricant that can form a lubricating film on the surface of the wear-resistant coating and cooperate with the porous coating to reduce the friction and wear of the porous coating and the wear-resistant coating during the friction process.

[0016] A second aspect of the present invention provides a method for preparing a friction-reducing coating for a shaft-bushing friction pair assembly, characterized in that it comprises the following steps:

[0017] (1) Spraying a non-porous coating on the outer surface of the shaft;

[0018] (2) spraying a porous coating onto the non-porous coating and grinding to obtain a composite coating;

[0019] (3) coating an anti-sticking layer on the composite coating, and spraying a carbon fiber layer on the anti-sticking layer;

[0020] (4) Assembling the bushing with the shaft, impregnating the gap between the carbon fiber layer and the inner surface of the bushing with an epoxy resin dispersed with molybdenum disulfide and chromium oxide, and after curing, heat treating at 120-125° C. for 2-2.5 hours to form a wear-resistant coating, and processing and removing the anti-sticking layer;

[0021] (5) The porous coating layer is subjected to an infiltration treatment.

[0022] In the present invention, in order to improve operational reliability, especially under the condition of the "stop effect" (i.e., a sharp increase in the friction coefficient when sliding is restarted) that may occur in the shaft-bushing friction pair assembly after the load stops, a high-speed multi-chamber explosion spraying technology is used to form a double-layer coating on the outer surface of the shaft, and a wear-resistant coating is arranged on the inner surface of the bushing to reduce the impact of the stop effect.

[0023] In some embodiments, the mass ratio of the epoxy resin, molybdenum disulfide and chromium oxide is 100:(10-12):(20-25).

[0024] In some embodiments of the present invention, in the step (1), the non-porous coating is prepared by a high-speed multi-chamber explosion spraying method, and specific parameters include: powder consumption 800-1200 g / hour, spray gun aspect ratio 25-32, the ratio of combustible gas to oxidant in the first chamber is 4.50-4.70, the ratio of combustible gas to oxidant in the second chamber is 4.70-4.90, and the thickness of the non-porous coating is 50-150 μm.

[0025] In some embodiments of the present invention, in the step (2), the porous coating is prepared by a high-speed multi-chamber explosion spraying method, and the specific parameters include: powder consumption 1500-2500 g / hour, spray gun aspect ratio 15-20, the ratio of combustible gas to oxidant in the first chamber is 4.85-5.10, the ratio of combustible gas to oxidant in the second chamber is 4.70-4.90, and the thickness of the porous coating is 500-1000 μm.

[0026] In the embodiment, in step (3), after the non-porous coating or the porous coating is sprayed, the coating is cylindrically ground to a desired thickness, and then the anti-sticking layer is coated onto the porous coating.

[0027] In the embodiment, step (3) specifically includes: spraying a carbon fiber layer on the anti-sticking layer of the shaft, and then impregnating it with an epoxy resin containing dispersed molybdenum disulfide and chromium oxide.

[0028] In some embodiments of the present invention, in step (4), the thickness of the wear-resistant coating is 125-150 μm.

[0029] In the embodiment, when assembling the shaft and the bushing, the axes of the shaft and the bushing need to be aligned, and the gap between the anti-sticking layer of the shaft and the inner surface of the bushing is 125-150 μm, so as to control the thickness of the wear-resistant coating. The wear-resistant coating is formed in this gap, and after the formation, the shaft and the bushing are separated, and the residue of the anti-sticking layer on the wear-resistant coating on the inner surface of the bushing is removed.

[0030] In some embodiments of the present invention, in step (5), the infiltration treatment specifically comprises: immersing the area of ​​the shaft with the porous coating in a closed container containing a lubricant, and performing a cyclic vacuum treatment for at least 3 times.

[0031] A third aspect of the present invention provides a shaft-bushing friction pair assembly, characterized in that the shaft-bushing friction pair assembly comprises the friction reduction coating described in any one of the first aspects or the friction reduction coating prepared by the preparation method described in any one of the second aspects.

[0032] By implementing the above technical solution, the present invention has the following beneficial effects:

[0033] 1. The present invention reduces the impact of the stopping effect by providing a friction-reducing coating on the friction surface of the shaft and the bushing. The present invention provides a non-porous coating with a small porosity so that the non-porous coating has a greater strength and bonding performance, so that it can be tightly bonded to the shaft, providing a basis for the adhesion of the porous coating.

[0034] 2. The present invention sprays a porous coating on a non-porous coating, utilizes the pores of the porous coating to absorb and store lubricants, and the lubricant filling rate of the porous coating can reach 93-95% of the total pore volume, making the porous coating fully saturated. The lubricant entering the friction interaction area achieves the ability to retain the lubricating oil film due to the additional interaction with the polar groups of the epoxy component of the epoxy composite material, reduces the temperature of the friction pair during operation, and can effectively improve the wear resistance of the friction pair components and reduce the friction coefficient. At the same time, during the friction interaction process, the lubricant is not easy to lose from the porous coating, thereby having an excellent lubrication effect and slowing down the impact of the stop effect.

[0035] 3. The present invention provides a wear-resistant coating on the inner surface of the bushing where the bushing and the shaft rub against each other, so as to avoid the inner surface of the bushing being seriously worn during the friction process, which may cause the inner diameter of the bushing to expand, and the friction jamming and separation caused by incompatibility with the shaft, thereby improving its service life.

[0036] 4. It has been calculated that only 25-30% of the lubricant in the pores of the porous coating is used during the operation of the friction component. The lubricant reserve in the pores can be replenished by a single vacuum pumping, which effectively reduces the equipment maintenance time compared with traditional lubrication solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A cross-sectional view of a shaft-bushing friction pair assembly provided by the present invention;

[0038] Figure 2 A cross-sectional view of a high-speed multi-chamber explosion spraying device provided by the present invention;

[0039] Figure 3 This is a schematic structural diagram of the composite coating on a shaft provided by the present invention.

[0040] The symbols in the figure represent:

[0041] 1. Shaft, 2. Bushing, 3. Composite coating, 4. Wear-resistant coating, 5. Non-porous coating, 6. Porous coating, 7. Pre-combustion chamber, 8. Cylindrical main combustion chamber, 9. Annular combustion chamber, 10. Cylindrical barrel, 11. Gas dynamic feeding device, 12. Explosion combustion mode initiation system; 13. First piezoelectric pressure sensor, 14. Second piezoelectric pressure sensor. DETAILED DESCRIPTION

[0042] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is described in detail below in conjunction with embodiments and drawings.

[0043] Example 1

[0044] In this embodiment, a friction-reducing coating for a shaft-bushing friction pair assembly is prepared, such as Figure 1 As shown, the following steps are included:

[0045] (1) Using bronze powder with a dispersion of 15-40 μm as raw material, a non-porous coating is sprayed on the outer surface of the shaft using a high-speed multi-chamber explosion spraying method, and the thickness is controlled at 50 μm to ensure the bonding strength between the non-porous coating and the shaft surface. The high-speed multi-chamber spraying device used is as follows: Figure 2 As shown, the specific parameters include: powder consumption 800 g / h, spray gun aspect ratio 25, the ratio of combustible gas to oxidant in the first chamber is 4.50, and the ratio of combustible gas to oxidant in the second chamber is 4.70;

[0046] (2) using 20 wt% bronze powder with a dispersion of 50-315 μm and 80 wt% mixed particles (boride, carbide, eutectoid alloy) with a dispersion of 40-63 μm as raw materials, spraying a porous coating on the non-porous coating using a high-speed multi-chamber explosion spraying method, the specific parameters include: powder consumption of 1500 g / h, spray gun aspect ratio of 15, the ratio of combustible gas to oxidant in the first chamber is 4.85, the ratio of combustible gas to oxidant in the second chamber is 4.70, the thickness is controlled at 500 μm, and the outer surface of the porous coating is ground by an external cylindrical machine to obtain a composite coating;

[0047] (3) applying an anti-sticking layer on the composite coating, and spraying a carbon fiber layer on the anti-sticking layer (the carbon fiber powder needs to be impregnated with anhydrous ethanol in advance and dried at 200-300°C for 15-30 minutes to remove oil stains that may exist in the carbon fiber production process.); (4) assembling the bushing with the shaft, the longitudinal axes of the shaft and bushing should be aligned, that is, the composite coating surface of the inner surface of the bushing and the outer surface of the shaft are equidistant, and using epoxy resin dispersed with molybdenum disulfide and chromium oxide (100g of epoxy resin is dispersed with 200g of molybdenum disulfide and chromium oxide). 10g of molybdenum disulfide and 20g of chromium oxide. The molybdenum disulfide powder and chromium oxide powder need to be impregnated with anhydrous ethanol in advance and dried at 200-300°C for 15-30 minutes to remove any oil residue that may exist on the surface. ) Impregnate the gap between the carbon fiber layer and the inner surface of the bushing, and after curing, heat treat at 120°C for 2 hours to form a wear-resistant coating with high bonding strength and friction reduction on the inner surface of the bushing, use a cutter to process the wear-resistant coating so that the boundary of the wear-resistant coating is flush with the boundary of the inner surface of the bushing, and remove the anti-sticking layer;

[0048] (5) Immerse the shaft with the composite coating in a closed reservoir with lubricating oil, evacuate the closed reservoir, and repeat the cycle three times to obtain a shaft-bushing friction pair assembly with a friction-reducing coating.

[0049] Performance Testing

[0050] Performance test 1:

[0051] In this test, a steel block with a diameter of 40 mm, a surface roughness of Ra = 0.32 μm, and HRC45-50 is used to simulate the shaft in the shaft-bushing friction pair assembly, and a steel plate coated with a wear-resistant coating is used to simulate the bushing in the shaft-bushing friction pair assembly. The steel block is rubbed against the wear-resistant coating on the surface of the steel plate to simulate the friction between the outer surface of the shaft and the inner surface of the bushing to conduct a friction and wear experiment;

[0052] Experiment 1: In the absence of lubrication, three sets of uncoated steel blocks and steel plates covered with wear-resistant coatings were tested three times, and the test results were:

[0053] In the three tests, the wear-resistant coating on the steel plate surface was destroyed after the steel block rubbed for 458m, 561m and 623m respectively. The temperature of the test friction zone rose to 130-135℃ within 15-20 minutes, and the friction coefficient was 0.45-0.50. It was observed that the surfaces of the three steel blocks were severely worn and oxidized, while the surfaces of the three steel plates had no obvious wear.

[0054] Experiment 2: The composite coating of the present invention was formed on the surface of a steel block by a high-speed explosion multi-chamber spraying method. Two sets of steel blocks covered with the composite coating and steel plates covered with the wear-resistant coating were used to conduct two repeated tests. The results showed that:

[0055] When the friction path was 3240 and 3600 m, the wear-resistant coating on the steel plate surface was damaged, the temperature of the friction zone rose to 135-140 ° C within 108-120 minutes, and the friction coefficient was 0.35-0.40. It was observed that the composite coating on the surface of the steel block was not worn, and there was no obvious wear on the steel plate surface.

[0056] In summary, according to Experiment 1, since the surface of the steel plate is coated with a wear-resistant coating, while the surface of the steel block is not coated, the degree of wear on the surface of the steel block is significantly greater than that on the surface of the steel plate, indicating that spraying a wear-resistant coating on the inner surface of the bushing can improve the wear resistance of the inner surface of the bushing.

[0057] Furthermore, according to Experiment 2, after the composite coating is sprayed on the surface of the steel block, the destruction rate and heating rate of the wear-resistant coating on the surface of the steel plate are greatly slowed down, indicating that the friction coefficient between the two is greatly reduced. The friction-reducing coating described in the present invention has a low friction coefficient and high wear resistance, and can reduce the temperature of the shaft-bushing friction pair assembly during operation, thereby increasing the service life of the shaft-bushing friction pair assembly.

[0058] Performance Test 2:

[0059] In this test, the composite coating of the present invention is formed on the surface of the steel block by a high-speed explosion multi-chamber spraying method to simulate a shaft sprayed with the composite coating, and the wear-resistant coating of the present invention is formed on the surface of the steel plate to simulate a bushing sprayed with a wear-resistant coating, and aviation lubricant MS-20 is used to fill the pores of the composite coating. The wear resistance of the anti-friction coating under different pore filling percentages is studied, and continuous tests are carried out. The monitoring conditions are that the experiment ends when the temperature rises to 130°C and the friction coefficient reaches 0.3. The experimental results are as follows:

[0060] Experiment 1: 30% pore filling:

[0061] The steel block covered with 30% pore filling of the composite coating and the steel plate covered with the wear-resistant coating can run stably for 91 hours (friction path 149400m). During the stabilization process, the temperature of the friction zone does not exceed 60-63℃, and the friction coefficient is 0.10-0.11.

[0062] The wear strength of the wear-resistant coating is 1.1-1.2×10 -8 No wear of the composite coating was detected within this range.

[0063] Experiment 2: 50% pore filling:

[0064] The steel block covered with 50% pore filling of the composite coating and the steel plate covered with the wear-resistant coating can be used in a stable operation for 131 hours (friction path 235800m). The temperature of the friction interaction zone during the stable process is 53-55℃ and the friction coefficient is 0.06-0.08.

[0065] The wear strength of the wear-resistant coating is 1.1-1.3×10 -10 No wear of the composite coating was detected within this range.

[0066] Experiment 3: 93-95% pore filling:

[0067] By vacuuming three times to fill 93-95% of the total pores with lubricating oil, the anti-friction coating can run stably for 655 hours (friction path is 1179200m).

[0068] The temperature of the friction interaction zone during the stable friction process is 48-50°C, and the friction coefficient is 0.05-0.06.

[0069] Considering the running-in of the wear-resistant coating, the wear intensity in the first 150 hours is 6.2×10 -12 -7.0×10 -12 The wear intensity of the last 300 hours of operation is 3.0×10 -12 .

[0070] The wear of the composite coating was observed to be within the experimental error. The linear wear of the composite coating was calculated to be less than 1 micron during the experiment (880 hours).

[0071] Research has confirmed that the stable operation of the friction reduction of the present invention is due to the fact that the pores of the composite coating can ensure that the lubricating oil can enter the friction interaction area as a lubricating liquid, and have additional interactions with the polar groups of the epoxy components in the wear-resistant coating, thereby achieving the ability to retain the lubricating film and thus reducing the friction coefficient and temperature between the shaft-bushing friction pair components during friction.

[0072] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A friction reducing coating for a shaft-bushing friction pair assembly, characterized in that: The anti-friction coating includes a composite coating sprayed on the outer surface of the shaft and a wear-resistant coating sprayed on the inner surface of the bushing, and the composite coating includes a non-porous coating sprayed on the outer surface of the shaft and a porous coating sprayed on the surface of the non-porous coating, wherein the porosity of the porous coating is 25-30%.

2. The anti-friction coating according to claim 1, characterized in that: The raw material of the non-porous coating includes bronze powder with a dispersion degree of 15-40 μm.

3. The anti-friction coating according to claim 1, characterized in that: The raw materials of the porous coating include bronze powder with a dispersion of 50-315 μm and mixed particles with a dispersion of 40-63 μm, and the mixed particles include boride, carbide and eutectoid alloy.

4. The anti-friction coating according to claim 1, characterized in that: The raw materials of the wear-resistant coating include carbon fiber, molybdenum disulfide, chromium oxide and epoxy resin.

5. A method for preparing a friction-reducing coating for a shaft-bushing friction pair assembly according to any one of claims 1 to 4, characterized in that: The following steps are involved: Spray a non-porous coating onto the outer surface of the shaft; Spraying a porous coating onto the non-porous coating and grinding to obtain a composite coating; Applying an anti-sticking layer on the composite coating, and spraying a carbon fiber layer on the anti-sticking layer; Assemble the bushing with the shaft, impregnate the gap between the carbon fiber layer and the inner surface of the bushing with epoxy resin dispersed with molybdenum disulfide and chromium oxide, after curing, heat treat at 120-125° C. for 2-2.5 hours to form a wear-resistant coating, and process and remove the anti-sticking layer; The porous coating layer is subjected to an infiltration treatment.

6. The preparation method according to claim 5, characterized in that: In the step (1), the non-porous coating is prepared by a high-speed multi-chamber explosion spraying method, and specific parameters include: powder consumption of 800-1200 g / hour, spray gun aspect ratio of 25-32, the ratio of combustible gas to oxidant in the first chamber is 4.50-4.70, the ratio of combustible gas to oxidant in the second chamber is 4.70-4.90, and the thickness of the non-porous coating is 50-150 μm.

7. The preparation method according to claim 5, characterized in that: In the step (2), the porous coating is prepared by a high-speed multi-chamber explosion spraying method, and the specific parameters include: powder consumption of 1500-2500 g / hour, spray gun aspect ratio of 15-20, the ratio of combustible gas to oxidant in the first chamber is 4.85-5.10, the ratio of combustible gas to oxidant in the second chamber is 4.70-4.90, and the thickness of the porous coating is 500-1000 μm.

8. The preparation method according to claim 5, characterized in that: In the step (4), the thickness of the wear-resistant coating is 125-150 μm.

9. The preparation method according to claim 5, characterized in that: In the step (5), the immersion treatment specifically comprises: immersing the area of ​​the shaft with the porous coating in a closed container containing a lubricant, and performing a cyclic vacuum treatment for at least 3 times.

10. A shaft-bushing friction pair assembly, characterized in that: The shaft-bushing friction pair assembly comprises the friction-reducing coating according to any one of claims 1 to 4 or the friction-reducing coating prepared by the preparation method according to any one of claims 5 to 9.

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