A friction-reducing and wear-resistant polyamide-imide composite material and its preparation method and application

Abstract

The present invention discloses a friction-reducing and wear-resistant polyamide-imide composite material and its preparation method and application, which belong to the technical field of polymer materials. The friction-reducing and wear-resistant polyamide-imide composite material of the present invention is measured by mass, and its raw materials include the following components: 100 parts of base slurry, 0.1-20 parts of functional filler, 0-50 parts of diluent, 0.1-1 parts of defoamer, and 0.1-1 parts of dispersant; wherein, the base slurry is an aqueous polyamide-imide emulsion; the functional filler is a biomass carbon composite molybdenum disulfide material treated with a siloxane coupling agent, and the source of the biomass carbon is cattail-derived carbon fiber. The composite material has the advantages of low friction coefficient and wear, wide source of raw materials, environmental friendliness, and high dispersion stability; its preparation method is convenient and can meet the needs of planned production; as a friction-reducing and wear-resistant material, it has broad application prospects in mechanical engineering materials.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a friction-reducing and wear-resistant polyamide-imide composite material, a preparation method thereof, and applications thereof. Background Art

[0002] Polymer coatings offer excellent wear resistance and corrosion resistance. These materials are commonly used in machinery, ships, buildings, and other applications subject to high temperatures and chemical attack. In general industry, polyamide-imide coatings are used for bearings and wear-resistant components, as well as components requiring high strength and hardness. However, pure polyamide-imide coatings exhibit high friction coefficients and wear rates. By adjusting the composition and surface condition of the polymer coating, these friction coefficients and wear rates can be effectively controlled and optimized.

[0003] Molybdenum disulfide (MoS2) and carbon-based materials are highly effective in anti-friction lubrication. Both can form a lubricating film at the interface, significantly reducing the coefficient of friction. The introduction of carbon materials into a single MoS2 material can improve the surface morphology of the MoS2, forming a more uniform and continuous tribofilm. This helps reduce friction and wear, and increases the service life of the material. Furthermore, the corrosion resistance of carbon materials can enhance the overall corrosion resistance of composite materials, which is particularly important for applications in harsh environments.

[0004] Currently, the carbon materials used in these applications primarily come from high-purity graphite and carbon nanotubes purchased from laboratories. These raw materials often originate from non-renewable fossil fuels, such as methane and ethylene, and require high production processes and costs. In contrast, biomass carbon, derived from biomass waste, is a renewable resource with certain advantages in terms of cost and environmental friendliness. With technological advancements, the performance of biomass carbon is continuously improving, and it has the potential to replace traditional carbon materials in more areas.

[0005] For example, the Chinese invention patent with publication number CN107298442A discloses a biomass carbon / molybdenum disulfide nanocomposite material and a preparation method thereof, which uses corn stalks to prepare biomass carbon by a hydrothermal method and calcination, and then grows petal-shaped molybdenum disulfide nanomaterials on the porous biomass carbon by a one-step hydrothermal method. However, compared to traditional carbon materials, when general biomass carbon materials are used for polyamide-imide, the technical problem of poor dispersibility of the composite material in the polyamide-imide emulsion is prone to occur. General biomass carbon particles are prone to agglomeration under high specific surface areas, and the agglomerated particles form larger aggregates, which increases the difficulty of dispersion in the emulsion, and the Brownian motion effect of larger particles is weakened, making it more likely to settle, aggravating the difficulty of dispersion, thereby causing biomass carbon / molybdenum disulfide to be difficult to obtain the expected application effect in polyamide-imide, and its intuitive manifestation is that the lubrication performance is poor, and the friction coefficient and wear of the composite material are high.

[0006] Therefore, a friction-reducing and wear-resistant polyamide-imide composite material and a preparation method thereof are provided to give full play to the advantages of biomass carbon materials, solve the above-mentioned defects of the prior art, and improve the problems of high friction coefficient and wear of polyamide-imide materials in application, which has positive significance for expanding the application of polyamide-imide coatings. Summary of the Invention

[0007] In view of the above-mentioned defects of the prior art, in the first aspect of the present invention, a friction-reducing and wear-resistant polyamide-imide composite material with low friction coefficient and wear, wide raw material sources, environmental friendliness and high dispersion stability is provided. The raw materials include the following components, in parts by mass: 100 parts of base slurry, 0.1-20 parts of functional filler, 0-50 parts of diluent, 0.1-1 part of defoaming agent, and 0.1-1 part of dispersant; wherein the base slurry is an aqueous polyamide-imide emulsion; the functional filler is a biomass carbon composite molybdenum disulfide material treated with a siloxane coupling agent, and the source of the biomass carbon is cattail-derived carbon fiber.

[0008] Cattail-derived carbon fibers can be obtained by carbonizing clean cattail fibers. Cattail fibers have a high wax content. In practice, skilled artisans can clean them with suitable solvents such as water and ethanol (water removes solid impurities like sand and dust, while ethanol dissolves and removes organic impurities like grease and wax), dry them, and then carbonize them.

[0009] Preferably, the method for preparing cattail-derived carbon fibers comprises the following steps: removing impurities from the surface of cattail fibers, drying, and carbonizing at 700-900° C. for 2-4 h to obtain cattail-derived carbon fibers.

[0010] In actual operation, those skilled in the art can select the appropriate type of auxiliary agent according to actual needs and conditions.

[0011] Water, ethanol, and isopropyl alcohol are suitable diluents for the polyamide-imide emulsion of the present invention. Their addition and dosage can be adjusted based on parameters such as the viscosity of the base slurry to ensure good processability. Water excels in environmental friendliness, safety, and cost-effectiveness, while ethanol offers advantages in solubility, volatility, and antimicrobial properties. Isopropyl alcohol excels in high solubility, low toxicity, and good volatility.

[0012] Preferably, the diluent includes at least one of water, ethanol and isopropanol.

[0013] Among Silcona products, HLD-6, HLD-8ks, and HLD-11c are suitable dispersant types for the present invention. HLD-6 improves production efficiency with its wide applicability, HLD-8ks optimizes the dispersion effect of fillers through a special formula design, reducing process complexity, and HLD-11c is environmentally friendly and designed specifically for water-based systems. It should be noted that dispersants are a conventional additive for coatings. The addition of dispersants can improve the dispersibility of components to a certain extent. However, in the application scenarios of the present invention, the agglomeration and weak dispersion of biomass carbon materials cannot be fully resolved by increasing the amount of dispersant used.

[0014] Preferably, the dispersant includes at least one of HLD-6, HLD-8ks, and HLD-11c.

[0015] BYK defoamers, produced by BYK in Germany, are high-performance additives used to reduce foaming in coatings production. Defoamers such as BYK-012, BYK-014, and BYK-016 can quickly reduce the surface tension of mixed systems, disrupting foam structure and inhibiting the formation of new foam.

[0016] Preferably, the defoaming agent includes at least one of BYK-012, BYK-014, and BYK-016.

[0017] In a second aspect of the present invention, a method for preparing the friction-reducing and wear-resistant polyamide-imide composite material of the first aspect of the present invention is provided, which has a convenient process and comprises the following steps:

[0018] (1) mixing cattail-derived carbon fibers, ammonium molybdate tetrahydrate, and thiourea in water to obtain a mixed solution; subjecting the mixed solution to a hydrothermal reaction, recovering a crude product after completion and purifying it to obtain a biomass carbon composite molybdenum disulfide material;

[0019] (2) The biomass carbon composite molybdenum disulfide material is treated with a siloxane coupling agent and then added to an aqueous polyamide-imide emulsion, followed by adding a diluent, a dispersant, and a defoaming agent, mixing and dispersing to obtain a coating mixture;

[0020] (3) The coating mixture is applied to the surface of the substrate, and then cured after being surface-dried at room temperature. After completion, it is naturally annealed to obtain a friction-reducing and wear-resistant polyamide-imide composite material.

[0021] Preferably, in step (1), the amount of cattail-derived carbon fiber is 0.4-1.0 g; the amount of ammonium molybdate tetrahydrate is 0.6-1.0 g; the amount of thiourea is 1.8-3.0 g; the mass ratio of ammonium molybdate tetrahydrate to thiourea is 1:3; and the amount of water is 40-60 mL.

[0022] Preferably, in step (1), the temperature of the hydrothermal reaction is 150-200°C, and the reaction time is 6-12 h.

[0023] The biomass carbon composite molybdenum disulfide material can be treated with a siloxane coupling agent using conventional methods in the art and then added to an aqueous polyamide-imide emulsion. The siloxane coupling agent can act as a bridge between the inorganic filler and the organic polymer matrix, enhancing the chemical affinity between the two and reducing interface defects. As shown in the embodiment of the present invention, 2 g of biomass carbon composite molybdenum disulfide material was added to 1 mL of KH560 and 99 mL of ethanol, followed by heating and stirring at 60 ° C for 3 h. Those skilled in the art may also use other methods to complete the treatment.

[0024] Preferably, in step (3), the curing temperature is 270-320°C and the curing time is 3-8 hours.

[0025] In the third aspect of the present invention, there is provided an application of the friction-reducing and wear-resistant polyamide-imide composite material of the first aspect of the present invention or the friction-reducing and wear-resistant polyamide-imide composite material prepared by the preparation method of the second aspect of the present invention, specifically as a friction-reducing and wear-resistant material in mechanical engineering materials.

[0026] Based on the above technical solution, the design concept of the present invention is to use cattail-derived carbon fibers as biomass carbon materials. The structure and other properties of biomass carbon are highly correlated with its biomass materials. Compared with ordinary biomass carbon materials, cattail-derived carbon fibers have specific micro / nano structures. Structurally, cattail velvet fibers have a multi-cavity structure, which is light and structurally stable. The main fiber bundles are composed of thin-walled cells and solid stone cells, and have high tensile strength and specific modulus. The branch fiber bundles are composed of multiple "semi-honeycomb-shaped" special-shaped thin-walled cells. The internal diaphragm divides the special-shaped thin-walled cells into several open cavities. This structural feature makes the cattail velvet branch fiber bundles light, structurally stable, and have good oil adsorption and storage capabilities. The above structure can provide stable physical support, protect the nanoparticles from agglomeration, and help improve their dispersibility in polyamide-imide emulsions. The present invention introduces cattail-derived carbon fiber composite MoS2 material, utilizes the self-lubricating property of MoS2 itself and combines the advantages of stability and strong load-bearing capacity of the carbon material, and gives full play to the synergistic effect between cattail-derived carbon fiber and MoS2, thereby effectively controlling the friction coefficient and wear rate of the polymer coating.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] The invention provides a friction-reducing and wear-resistant polyamide-imide composite material, which has the advantages of low friction coefficient and wear, wide raw material sources, environmental friendliness and high dispersion stability.

[0029] The invention provides a method for preparing a friction-reducing and wear-resistant polyamide-imide composite material. The method has a convenient process and can meet the needs of planned production.

[0030] The present invention provides an application of a friction-reducing and wear-resistant polyamide-imide composite material, which has broad application prospects in mechanical engineering materials as a friction-reducing and wear-resistant material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a physical picture of wild cattail and cattail fluff fiber;

[0032] Figure 2 Scanning electron microscopy (a) and element distribution spectrum (b) of biomass carbon composite molybdenum disulfide material, scale is 10 μm;

[0033] Figure 3 The scanning electron microscope image and element distribution spectrum of the friction-reducing and wear-resistant polyamide-imide composite material prepared in Example 1;

[0034] Figure 4 Friction coefficient curves of Examples 1-3 and the comparative group under dry friction and white oil conditions at a load of 10 N;

[0035] Figure 5 Friction coefficient curves of Examples 1-3 and the comparative group under dry friction and white oil conditions at a load of 5 N;

[0036] Figure 6 White light images of the wear of Examples 1-3 under dry friction under a load of 10 N. (a), (b), (c), and (d) are the wear images of the pure polyamide-imide coating and Examples 1-3 under dry friction, respectively;

[0037] Figure 7 These are white light images of the wear of Examples 1-3 under dry friction under a load of 5 N. (a), (b), (c), and (d) are wear images of the pure polyamide-imide coating and Examples 1-3 under dry friction, respectively. DETAILED DESCRIPTION

[0038] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0039] In the following embodiments:

[0040] The actual pictures of wild cattail and cattail fluff fiber used are as follows: Figure 1As shown; the preparation method of cattail-derived carbon fiber is as follows: the cattail fluff fiber is washed with water and ethanol to remove surface impurities, and then heated to 800℃ for carbonization for 2 hours after drying to obtain cattail-derived carbon fiber.

[0041] Example 1

[0042] The friction-reducing and wear-resistant polyamide-imide composite material of this embodiment is made by the following method:

[0043] (1) 0.6 g of cattail-derived carbon fiber, 0.8 g of ammonium molybdate tetrahydrate, and 2.4 g of thiourea were added to 50 mL of deionized water, and magnetic stirring was performed for 30 min to mix them evenly to obtain a mixed solution. The mixed solution was then transferred to a reactor for hydrothermal reaction. The oven was heated and kept warm at 160 °C for 10 h. After the reaction was completed, the reactor was naturally cooled and the sample was taken out. After centrifugation, washing, and vacuum drying, a biomass carbon composite molybdenum disulfide material was obtained.

[0044] (2) Take 2 g of biomass carbon composite molybdenum disulfide material, add 1 mL of KH560 and 99 mL of ethanol, heat and stir at 60 ° C for 3 h, centrifuge, wash, and vacuum tube dry to complete the treatment; add 0.1 g of biomass carbon composite molybdenum disulfide material treated with siloxane coupling agent to 10 g of polyamide-imide emulsion, add 0.1 wt.% of polymer water-based defoaming agent and 0.1 wt.% of dispersant respectively, and mix the solution at 500 rpm to obtain a coating mixture;

[0045] (3) The coating mixture was poured into a spray gun and sprayed onto the sandblasted Al sheet at a uniform speed. After being dried at room temperature, it was placed in an oven. The oven heating and insulation conditions were set to 120 °C for 1 h, then raised to 270 °C for 1 h to complete the curing. It was then naturally annealed to form a film to obtain a friction-reducing and wear-resistant polyamide-imide composite material, named PAI-1% filler.

[0046] In this example, the prepared biomass carbon composite molybdenum disulfide material was first characterized by scanning electron microscopy and element distribution analysis. The scanning electron microscopy image and element distribution spectrum of the biomass carbon composite molybdenum disulfide material are shown in FIG. Figure 2 As shown in the figure, it can be seen that the three elements S, Mo, and C are evenly distributed in the figure, indicating that the MoS2 particles prepared by the hydrothermal method have successfully grown and dispersed evenly in the cattail-derived carbon. The same method was used to further analyze the friction-reducing and wear-resistant polyamide-imide composite material. The characterization results are shown in Figure 3 As shown. Figure 3 It can be seen that the biomass carbon composite molybdenum disulfide material is uniformly dispersed in the polyamide-imide material, and no obvious agglomeration phenomenon is observed.

[0047] Example 2

[0048] This example is basically the same as Example 1, except that 0.2 g of a biomass carbon composite molybdenum disulfide material treated with a siloxane coupling agent is added to 10 g of the polyamide-imide emulsion. The resulting friction-reducing and wear-resistant polyamide-imide composite material is named PAI-2 filler%.

[0049] Example 3

[0050] This example is basically the same as Example 1, except that 0.3 g of a biomass carbon composite molybdenum disulfide material treated with a siloxane coupling agent is added to 10 g of the polyamide-imide emulsion. The resulting friction-reducing and wear-resistant polyamide-imide composite material is named PAI-3% filler.

[0051] Example 4

[0052] This example studies the application effect of the friction-reducing and wear-resistant polyamide-imide composite material under dry friction and white oil working conditions.

[0053] Tribological Performance Testing: The polyamide-imide composites were subjected to tribological testing using a reciprocating friction and wear tester under dry and white oil conditions. The kinematic pair consisted of a GCr15 bearing steel ball with a diameter of 6.35 mm. Loads of 5 N and 10 N were applied at a frequency of 2 Hz for 20 minutes. Following the friction tests, the three-dimensional surface morphology of the wear marks was characterized using a white light copolymerization 3D topograph to analyze the width and depth of the wear scars.

[0054] In the tribological performance test, pure polyamide-imide samples were used as the control group. The preparation method was as follows:

[0055] After stirring 10 g of aqueous polyamide-imide emulsion at 500 rpm for 5 minutes, 2 drops of polymer defoamer were added to it. After stirring and defoaming, the material was poured into a spray gun and sprayed at a uniform speed on the sandblasted Al sheet. After natural surface drying, it was placed in an oven for curing; the oven temperature was increased to 280°C, and after curing for 3 hours, it was naturally annealed to room temperature. After the Al sheet was taken out, it was washed with ethanol and the surface was blown dry with a nitrogen gun to obtain a polyamide-imide material, named pure PAI.

[0056] The friction coefficient test results of three anti-friction and wear-resistant polyamide-imide composite materials with different filler contents under dry friction and white oil conditions are as follows: Figure 4 Correspondingly, the test results under 5 N load are as follows Figure 5As shown. MoS2 is a self-lubricating material. The introduction of biomass carbon material increases the hardness and overall stability of the material, so the friction coefficient of PAI-1% filler, PAI-2% filler, and PAI-3% filler is significantly reduced. When the load is 10N, the average friction coefficients of the control group and Examples 1-3 are 0.5585, 0.4427, 0.3272, and 0.3597, respectively, and the friction coefficient of Example 2 is reduced by more than 40%. When the load is 5N, the average friction coefficients of the control group and Examples 1-3 are 0.6654, 0.4924, 0.3649, and 0.4110, respectively, and the average friction coefficient of Example 2 is reduced by more than 45%. The different friction coefficients of Examples 1-3 are due to the different effects of different filler contents on the tribological properties of polyimide composites. At the same time, it can be seen that under white oil conditions, the friction coefficients of Examples 1-3 are all low, indicating that the prepared polyamide-imide composites have the potential to be used under high-temperature white oil conditions.

[0057] The wear characteristics of three anti-friction and wear-resistant polyamide-imide composites with different filler contents under dry friction conditions are shown in Figure 2 under a load of 10 N. Figure 6 Correspondingly, the test results under 5 N load are as follows Figure 7 As shown in the figure, pure polyamide-imide was worn through after the friction test under the above conditions. However, as can be seen from the two figures, after the introduction of composite fillers, the wear of Examples 1-3 was reduced and no wear through occurred.

[0058] In summary, the present invention, by incorporating cattail-derived carbon fibers into MoS2 composites, leverages the inherent self-lubricating properties of MoS2, combined with the stability and high load-bearing capacity of the carbon material. This synergistic effect between the cattail-derived carbon fibers and MoS2 effectively controls the friction coefficient and wear rate of the polymer coating. This friction-reducing and wear-resistant polyamide-imide composite material has broad application prospects in fields such as bearing outer coatings and mechanical engineering materials.

[0059] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A friction-reducing and wear-resistant polyamide-imide composite material, characterized in that: The raw materials include the following components, calculated by mass: 100 parts of base slurry, 0.1-20 parts of functional filler, 0-50 parts of diluent, 0.1-1 parts of defoamer, and 0.1-1 parts of dispersant; wherein the base slurry is a water-based polyamide-imide emulsion; the functional filler is a biomass carbon composite molybdenum disulfide material treated with a siloxane coupling agent, and the source of the biomass carbon is cattail-derived carbon fiber; The method for preparing cattail-derived carbon fibers comprises the following steps: removing impurities from the surface of cattail fibers, drying, and carbonizing at 700-900°C for 2-4 hours to obtain cattail-derived carbon fibers having a specific micro / nanostructure; The preparation method of the biomass carbon composite molybdenum disulfide material comprises the following steps: mixing cattail-derived carbon fibers, ammonium molybdate tetrahydrate, and thiourea in water to obtain a mixed solution; subjecting the mixed solution to a hydrothermal reaction, and after completion, recovering and purifying a crude product to obtain the biomass carbon composite molybdenum disulfide material.

2. The friction-reducing and wear-resistant polyamide-imide composite material according to claim 1, characterized in that: The diluent includes at least one of water, ethanol, and isopropanol.

3. The friction-reducing and wear-resistant polyamide-imide composite material according to claim 1, characterized in that: The dispersant includes at least one of HLD-6, HLD-8ks, and HLD-11c.

4. The friction-reducing and wear-resistant polyamide-imide composite material according to claim 1, characterized in that: The defoaming agent includes at least one of BYK-012, BYK-014, and BYK-016.

5. A method for preparing the friction-reducing and wear-resistant polyamide-imide composite material according to any one of claims 1 to 4, characterized in that: The steps include: (1) mixing cattail-derived carbon fibers, ammonium molybdate tetrahydrate, and thiourea in water to obtain a mixed solution; subjecting the mixed solution to a hydrothermal reaction, recovering a crude product after completion and purifying it to obtain a biomass carbon composite molybdenum disulfide material; (2) The biomass carbon composite molybdenum disulfide material is treated with a siloxane coupling agent and then added to an aqueous polyamide-imide emulsion, followed by adding a diluent, a dispersant, and a defoaming agent, mixing and dispersing to obtain a coating mixture; (3) The coating mixture is applied to the surface of the substrate, and then cured after being surface-dried at room temperature. After completion, it is naturally annealed to obtain a friction-reducing and wear-resistant polyamide-imide composite material.

6. The method for preparing the friction-reducing and wear-resistant polyamide-imide composite material according to claim 5, wherein: In the step (1), the amount of cattail-derived carbon fiber is 0.4-1.0 g; the amount of ammonium molybdate tetrahydrate is 0.6-1.0 g; the amount of thiourea is 1.8-3.0 g; the mass ratio of ammonium molybdate tetrahydrate to thiourea is 1:3; and the amount of water is 40-60 mL.

7. The method for preparing the friction-reducing and wear-resistant polyamide-imide composite material according to claim 5, wherein: In step (1), the temperature of the hydrothermal reaction is 150-200°C, and the reaction time is 6-12 h.

8. The method for preparing the friction-reducing and wear-resistant polyamide-imide composite material according to claim 5, wherein: In the step (3), the curing temperature is 270-320°C and the curing time is 3-8 hours.

9. Use of the friction-reducing and wear-resistant polyamide-imide composite material according to any one of claims 1 to 4 or the friction-reducing and wear-resistant polyamide-imide composite material prepared by the preparation method according to any one of claims 5 to 8, characterized in that: Application as anti-friction and wear-resistant material in mechanical engineering materials.

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