Nano-alloy composite material for self-repairing surface of metal friction pair and preparation method and application of nano-alloy composite material

Abstract

The invention relates to the technical field of metal wear self-repairing materials, in particular to a nano-alloy composite material for metal friction pair surface self-repairing and a preparation method and application thereof. The method comprises the following steps: (1) dispersing nano boron carbide powder in an oxidizing agent, controlling the pH value of the mixture to be 0.5-3, carrying out stirring reaction at room temperature, washing to be neutral, and then carrying out vacuum drying to obtain modified boron carbide powder; (2) mixing iron-based alloy powder, modified boron carbide powder and nano graphite powder, adding ethanol as a dispersion medium, and performing ultrasonic dispersion and vacuum drying to obtain composite material powder; and (3) the composite material powder is put into a high-energy ball mill to be subjected to ball milling, and the nano-alloy composite material is obtained. The preparation method disclosed by the invention is simple, efficient and rapid, and the prepared composite material is controllable in particle size, good in uniformity, high in hardness, strong in wear resistance and good in adsorption lubricity.

Description

Technical Field

[0001] The present invention relates to the technical field of metal wear self-repairing materials, and in particular to a nano alloy composite material for self-repairing of metal friction pair surfaces, and a preparation method and application thereof. Background Art

[0002] During the continuous operation of mechanical equipment, the wear degree of vulnerable parts will gradually increase due to various loads and frictions for a long time, until they exceed the use limit and need to be scrapped and replaced. This phenomenon is one of the important reasons for equipment failure, affecting production efficiency and increasing maintenance costs. Although traditional repair methods such as welding and spraying can repair worn parts to a certain extent, they have many limitations. For example, welding may cause changes in material properties in the heat-affected zone, and spraying may cause peeling and other problems due to insufficient bonding strength between the coating and the substrate. More importantly, these traditional repair methods often require the dismantling of mechanical equipment, which not only increases maintenance costs, but also prolongs the downtime of the equipment, thereby affecting the continuous operation of the production line.

[0003] Metal wear self-repair technology provides a new way to solve the problem of parts wear. This technology adds self-repairing materials to lubricating oil or grease to form a stable and dispersed colloidal system in various types of lubricating oils. Under the action of friction and frictional heat, the self-repairing materials undergo chemical reactions or physical deposition on the worn surface, thereby forming a self-repairing protective layer on the worn surface. This protective layer can not only fill the pits and cracks caused by wear, but also restore the surface morphology and performance of the parts to a certain extent, realizing the self-repair of the worn parts.

[0004] In recent years, with the development of nanomaterials and composite materials, metal wear self-repair technology has made significant progress. Studies have shown that a variety of nano-scale self-repairing agents as lubricant additives have significant self-repairing functions and show the potential to achieve "zero wear". However, the repair materials used in the prior art, such as micron-sized metal powders or nano-ceramic particles, are prone to agglomeration in lubricants, resulting in uneven dispersion and difficulty in forming a good metallurgical bond with the friction pair surface. When the friction environment exceeds a certain threshold, the protective layer is prone to fall off and fail, which may have an adverse effect on mechanical equipment.

[0005] Therefore, developing a new self-healing agent is of great significance to improving the performance of the self-healing protective layer. Summary of the invention

[0006] The object of the present invention is to provide a nano-alloy composite material for surface self-repair of metal friction pairs, its preparation method and application. By introducing a compound system of iron-based alloy, boron carbide and graphite between the friction pairs, cracks and unevenness are filled, the contact surface between the friction pairs is rapidly increased, and under the action of frictional force and frictional heat, the composite material and the friction pair material undergo interfacial adsorption to form a film, reducing the frictional resistance and improving the anti-friction and anti-wear properties of the lubricating oil, thereby realizing self-repair of wear.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] The first aspect of the present invention provides a preparation method of a nano-alloy composite material for surface self-repair of metal friction pairs, and the method includes the following steps:

[0009] (1) Disperse nano-boron carbide powder in an oxidant, control the pH value of the mixture to be 0.5 - 3, stir and react at room temperature, wash with water until neutral, and then vacuum dry to obtain modified boron carbide powder;

[0010] (2) Mix iron-based alloy powder, modified boron carbide powder, and nano-graphite powder, add ethanol as a dispersion medium, ultrasonically disperse, and vacuum dry to obtain composite material powder;

[0011] (3) Put the composite material powder into a high-energy ball mill for ball milling to obtain the nano-alloy composite material.

[0012] In the above technical solution, further, the iron-based alloy is selected from one of Fe-Cr-C series alloys and FeNi alloys.

[0013] In the above technical solution, further, the mass of the nano-boron carbide powder accounts for 5% - 15% of the total mass of the boron carbide powder and the iron-based alloy powder; the mass ratio of the nano-graphite powder to the nano-boron carbide powder is 2:5.

[0014] In the above technical solution, further, in the step (1), the oxidant is concentrated sulfuric acid or concentrated nitric acid.

[0015] In the above technical solution, further, in the step (1), the stirring time is 1 - 4 hours; the vacuum drying temperature is 40 - 60°C.

[0016] In the above technical solution, further, in the step (2), the ultrasonic power is 200 - 300W, the treatment time is 20 - 30 minutes; the vacuum drying temperature is 40 - 60°C.

[0017] In the above technical solution, further, in the step (3), the ball milling time is 12 - 24 hours, the ball-to-material ratio is 10:1, and the rotation speed is 200 - 300 rpm.

[0018] In the second aspect of the present invention, a nano-alloy composite material for surface self-repair of metal friction pairs prepared by the above preparation method is provided.

[0019] In the third aspect of the present invention, a lubricating oil is provided, and the above nano-alloy composite material is added to the lubricating oil, and the content of the composite material in the lubricating oil is 0.01 wt% to 1 wt%.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. The preparation method of the present invention is simple, efficient and fast. The prepared composite material has controllable particle size and good uniformity. The prepared composite material has high hardness, strong wear resistance and good adsorption lubricity, and forms a stable colloidal system in various lubricating oils.

[0022] 2. By modifying boron carbide, hydroxyl functional groups are introduced on its surface to increase the polarity of the boron carbide surface, so that it has a stronger interaction with polar molecules in the lubricating oil. On the one hand, the agglomeration between boron carbides is reduced, thereby improving its dispersibility in the lubricating oil. On the other hand, the interfacial adsorption strength is enhanced.

[0023] 3. The present invention uses graphite powder and boron carbide to form a stable lubricating film during the friction process, thereby reducing the direct contact between the friction pairs and reducing the friction coefficient. Specifically, boron carbide acts as a catalyst to accelerate the graphitization process, thereby forming a graphite-like lubricating film at the friction interface, improving its stability and durability. At the same time, the compounding of graphite powder and boron carbide can promote crack deflection and bridging effects, thereby enhancing the interfacial bonding strength.

[0024] 4. The composite material of the present invention does not chemically react with the lubricating oil, does not change the viscosity and properties of the lubricating oil, and has no toxic side effects, ensuring the safety and stability of the composite material in practical applications. Specific Embodiments

[0025] The following examples can enable those of ordinary skill in the art to understand the present invention more comprehensively, but do not limit the present invention in any way.

[0026] In the following examples, the particle size of the iron-based alloy powder is 1-10 μm. The Fe-Cr-C series alloy powder used is FeCr55C6.0 alloy powder, the FeNi alloy is FeNi36; the nano-boron carbide powder is purchased from Zhejiang Yamei Technology Co., Ltd., with a particle size of 60 nm and a purity of 99.9%; the nano-graphite powder is purchased from Shanghai Merck Biochemical Technology Co., Ltd., with a particle size of <400 nm and a purity of 99.95%.

[0027] Example 1

[0028] A preparation method of a nano-alloy composite material for surface self-repair of a metal friction pair, comprising the following steps:

[0029] (1) Disperse nano-boron carbide powder in concentrated nitric acid, control the pH value of the mixture to be 0.5 - 3, stir and react at room temperature for 2 hours, wash with water until neutral, and then vacuum dry at 60 °C to obtain modified boron carbide powder;

[0030] (2) Weigh FeCr55C6.0 alloy powder according to the mass of boron carbide powder accounting for 5% of the total mass of boron carbide powder and iron-based alloy powder, weigh graphite powder according to the mass ratio of nano-graphite powder to nano-boron carbide powder being 2:5, mix the FeCr55C6.0 alloy powder, modified boron carbide powder, and graphite powder, add ethanol as a dispersion medium, perform ultrasonic treatment at 200 W for 30 minutes, and then vacuum dry at 60 °C to remove ethanol to obtain composite material powder;

[0031] (3) Put the composite material powder into a high-energy ball mill for ball milling, with the ball milling time being 24 hours, the ball-to-material ratio being 10:1, and the rotation speed being 200 rpm to obtain the nano-alloy composite material.

[0032] Example 2

[0033] A preparation method of a nano-alloy composite material for surface self-repair of a metal friction pair, comprising the following steps:

[0034] (1) Disperse nano-boron carbide powder in concentrated nitric acid, control the pH value of the mixture to be 0.5 - 3, stir and react at room temperature for 2 hours, wash with water until neutral, and then vacuum dry at 60 °C to obtain modified boron carbide powder;

[0035] (2) Weigh FeCr55C6.0 alloy powder according to the mass of boron carbide powder accounting for 10% of the total mass of boron carbide powder and iron-based alloy powder, weigh graphite powder according to the mass ratio of nano-graphite powder to nano-boron carbide powder being 2:5, mix the FeCr55C6.0 alloy powder, modified boron carbide powder, and graphite powder, add ethanol as a dispersion medium, perform ultrasonic treatment at 200 W for 30 minutes, and then vacuum dry at 60 °C to remove ethanol to obtain composite material powder;

[0036] (3) Put the composite material powder into a high-energy ball mill for ball milling, with the ball milling time being 24 hours, the ball-to-material ratio being 10:1, and the rotation speed being 200 rpm to obtain the nano-alloy composite material.

[0037] Example 3

[0038] A preparation method of a nano-alloy composite material for surface self-repair of a metal friction pair, comprising the following steps:

[0039] (1) Disperse the nano-boron carbide powder in concentrated nitric acid, control the pH value of the mixture to be 0.5 - 3, stir and react at room temperature for 2 hours, wash with water until neutral, and then vacuum dry at 60 °C to obtain the modified boron carbide powder;

[0040] (2) Weigh the FeCr55C6.0 alloy powder according to 15% of the mass of the boron carbide powder in the total mass of the boron carbide powder and the iron-based alloy powder, weigh the graphite powder according to the mass ratio of the nano-graphite powder to the nano-boron carbide powder of 2:5, mix the FeCr55C6.0 alloy powder, the modified boron carbide powder, and the graphite powder, add ethanol as the dispersion medium, perform ultrasonic treatment at 200W for 30 minutes, and then vacuum dry at 60 °C to remove ethanol to obtain the composite material powder;

[0041] (3) Put the composite material powder into a high-energy ball mill for ball milling, with the ball milling time of 24 hours, the ball-to-material ratio of 10:1, and the rotation speed of 200 rpm to obtain the nano-alloy composite material.

[0042] Example 4

[0043] A preparation method of a nano-alloy composite material for surface self-repair of metal friction pairs, comprising the following steps:

[0044] (1) Disperse the nano-boron carbide powder in concentrated sulfuric acid, control the pH value of the mixture to be 0.5 - 3, stir and react at room temperature for 2 hours, wash with water until neutral, and then vacuum dry at 60 °C to obtain the modified boron carbide powder;

[0045] (2) Weigh the FeNi36 alloy powder according to 10% of the mass of the boron carbide powder in the total mass of the boron carbide powder and the iron-based alloy powder, weigh the graphite powder according to the mass ratio of the nano-graphite powder to the nano-boron carbide powder of 2:5, mix the FeNi36 alloy powder, the modified boron carbide powder, and the graphite powder, add ethanol as the dispersion medium, perform ultrasonic treatment at 300W for 20 minutes, and then vacuum dry at 60 °C to remove ethanol to obtain the composite material powder;

[0046] (3) Put the composite material powder into a high-energy ball mill for ball milling, with the ball milling time of 12 hours, the ball-to-material ratio of 10:1, and the rotation speed of 300 rpm to obtain the nano-alloy composite material.

[0047] Comparative Example 1

[0048] A preparation method of a nano-alloy composite material for surface self-repair of metal friction pairs, comprising the following steps:

[0049] (1) Weigh FeCr55C6.0 alloy powder according to 10% of the total mass of boron carbide powder and iron-based alloy powder, and weigh graphite powder according to the mass ratio of nano-graphite powder to nano-boron carbide powder of 2:5. Mix FeCr55C6.0 alloy powder, boron carbide powder, and graphite powder, add ethanol as a dispersion medium, and perform ultrasonic treatment at 200 W for 30 minutes. Then, vacuum dry at 60 °C to remove ethanol to obtain composite material powder;

[0050] (2) Put the composite material powder into a high-energy ball mill for ball milling. The ball milling time is 24 hours, the ball-to-material ratio is 10:1, and the rotation speed is 200 rpm to obtain a nano-alloy composite material.

[0051] Comparative Example 2

[0052] A preparation method of a nano-alloy composite material for surface self-repair of metal friction pairs includes the following steps:

[0053] (1) Disperse nano-boron carbide powder in concentrated nitric acid, control the pH value of the mixture to be 0.5 - 3, stir and react at room temperature for 2 hours, wash with water until neutral, and then vacuum dry at 60 °C to obtain modified boron carbide powder;

[0054] (2) Weigh FeCr55C6.0 alloy powder according to 10% of the total mass of boron carbide powder and iron-based alloy powder, mix FeCr55C6.0 alloy powder and modified boron carbide powder, add ethanol as a dispersion medium, perform ultrasonic treatment at 200 W for 30 minutes, and then vacuum dry at 60 °C to remove ethanol to obtain composite material powder;

[0055] (3) Put the composite material powder into a high-energy ball mill for ball milling. The ball milling time is 24 hours, the ball-to-material ratio is 10:1, and the rotation speed is 200 rpm to obtain a nano-alloy composite material.

[0056] Test Example 1

[0057] Adopt a Falex friction and wear testing machine to conduct wear performance tests. The test load range is 0.1 - 0.44 MPa, and a bearing specimen made of grade 45# steel is used. The lubricating oil is a SD / CC grade 15W40 gasoline / diesel engine universal oil. Add the nano-alloy composite materials prepared in Examples 1 - 4 and Comparative Examples 1 - 2 respectively according to 0.01 wt% in the engine oil. After 24 hours of bearing simulation tests, self-repairing films are formed on the surface of 45# steel. Table 1 shows the nano-hardness of the self-repairing film on the lower specimen after the 45# steel test.

[0058] Table 1

[0059] Example Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 <![CDATA[Nano-hardness / HV 0.2mN > 1257.7 1340.5 1325.6 1322.0 901.1 998.5

[0060] Taking the lubricating oil without added composite material as the control group, Table 2 shows the surface roughness of the shaft specimens of Examples 1-4 and Comparative Examples 1-2.

[0061] Table 2

[0062] Example Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Control Group Surface Roughness Ra / μm 0.3577 0.2358 0.3325 0.3017 0.5013 0.5220 0.5422

[0063] After the specimens were tested for 500 hours, all the lubricating oil was drained, so that the upper and lower specimens were in a boundary lubrication contact state. The testing machine was restarted, and the changes in the friction coefficient were recorded, as shown in Table 3.

[0064] Table 3

[0065] Example Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Coefficient of Friction 0.010 0.0057 0.0087 0.0088 0.054 0.079

[0066] Application Example 1

[0067] The composite material prepared in Example 2 was added to the lubricating oil of a commercial vehicle at a content of 0.3 wt% in the lubricating oil for testing. The vehicle had traveled 80,000 kilometers before the test, and the engine of this vehicle had a large noise, large vibration, and the lubricating oil had turned black. Before refueling, the engine cylinder pressure was tested, and the cylinder pressure was 50% lower than the standard cylinder pressure. After cleaning the original sludge in the engine cylinder block and replacing the lubricating oil, the composite material of Example 2 was added. After running for 30 minutes, the engine noise and vibration were significantly reduced, the power increased, and the blue smoke in the exhaust gas was also significantly reduced. When driving 1000 km, the engine cylinder pressure increased by 33.8%.

[0068] The above examples are only the preferred examples of the present invention and are not intended to limit the implementation manner. The protection scope of the present invention should be subject to the scope defined by the claims. Based on the above description, other different forms of changes or modifications can be made. The obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A preparation method of a nano-alloy composite material for surface self-repair of a metal friction pair, characterized in that, The method includes the following steps: (1) Disperse the nano-boron carbide powder in an oxidant, control the pH value of the mixture to be 0.5 - 3, stir and react at room temperature, wash with water until neutral, and then vacuum dry to obtain the modified boron carbide powder; (2) Mix the iron-based alloy powder, the modified boron carbide powder, and the nano-graphite powder, add ethanol as a dispersion medium, ultrasonically disperse, and vacuum dry to obtain the composite material powder; (3) Put the composite material powder into a high-energy ball mill for ball milling to obtain the nano-alloy composite material.

2. The preparation method according to claim 1, characterized in that, The iron-based alloy is selected from one of the Fe-Cr-C series alloys and FeNi alloys.

3. The preparation method according to claim 1, characterized in that, The mass of the nano-boron carbide powder accounts for 5% - 15% of the total mass of the boron carbide powder and the iron-based alloy powder; The mass ratio of the nano-graphite powder to the nano-boron carbide powder is 2:

5.

4. The preparation method according to claim 1, wherein In the step (1), the oxidant is concentrated sulfuric acid or concentrated nitric acid.

5. The preparation method according to claim 1, characterized in that, In the step (1), the stirring time is 1 - 4 hours; The vacuum drying temperature is 40 - 60 °C.

6. The preparation method according to claim 1, characterized in that, In the step (2), the ultrasonic power is 200 - 300 W, and the treatment time is 20 - 30 minutes; The vacuum drying temperature is 40 - 60 °C.

7. The preparation method according to claim 1, characterized in that, In the step (3), the ball milling time is 12 - 24 hours, the ball-to-material ratio is 10:1, and the rotation speed is 200 - 300 rpm.

8. A nano-alloy composite material for surface self-repair of a metal friction pair prepared by the preparation method according to any one of claims 1 - 7.

9. A lubricating oil, characterized in that, The nano-alloy composite material according to claim 8 is added to the lubricating oil, and the content of the nano-alloy composite material in the lubricating oil is 0.01 wt% - 1 wt%.