Nanometer core-shell-satellite structure CS (at) PDA / metal compound composite lubricating additive and preparation method and application of nanometer core-shell-satellite structure CS (at) PDA / metal compound composite lubricating additive

Abstract

The invention discloses a nanometer core-shell-satellite structure CS (at) PDA / metal compound composite lubricating additive and a preparation method and application thereof, and belongs to the technical field of nanometer materials, and the preparation method comprises the steps that the surface of nanometer core structure CS particles is evenly coated with a PDA layer through the self-agglutination-adhesion characteristic of dopamine, and a CS (at) PDA intermediate of a core-shell structure is formed; and ZnO nanoparticles or LDH nanosheets grow in situ on the surface of the CS (at) PDA intermediate through a hydrothermal synthesis and heat treatment process to obtain the CS (at) PDA / metal compound composite lubricant additive with the nano core-shell-satellite structure, the additive has good antifriction and antiwear effects, and after the additive is mixed with base oil to prepare mixed oil, the antifriction and antiwear properties of the material can be remarkably improved, and the service life of the material is prolonged. Meanwhile, the preparation process is simple, and the material stability is high.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials technology, and relates to a nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive, its preparation method and application. Background Technology

[0002] Lubricating additives are a core element in improving the performance of lubricating oils and ensuring the efficient and stable operation of mechanical systems. With the rapid development of modern industry, major equipment and key components are evolving towards higher speeds, heavier loads, higher precision, and longer service lives. Their operating conditions are becoming increasingly demanding, often facing multiple challenges such as extreme pressure, high temperatures, high loads, and complex chemical environments. This places unprecedentedly higher demands on the lubrication performance, stability, and durability of lubricants. Developing high-performance lubricating additives is of great strategic significance for significantly reducing equipment friction and wear, reducing energy consumption, extending equipment service life, and improving operational reliability under extreme conditions. It is also crucial for driving technological progress in key areas such as high-end equipment manufacturing, transportation, aerospace, and energy and chemical industries.

[0003] In the technological development of lubricant additives, numerous patents have proposed different solutions. Publication number CN120682630A discloses a black phosphorus-based composite material, its preparation method, and its application. This involves ultrasonically dispersing black phosphorus and nano-ferric oxide in an alkaline aqueous solution, followed by a hydrothermal reaction to form a primary composite. Then, dopamine is polymerized in situ under weakly alkaline conditions to coat the surface of the composite with a polydopamine layer, constructing a black phosphorus / ferric oxide / polydopamine composite structure with a three-component synergistic lubrication effect. Ferric oxide acts as a catalytic active center, promoting the formation of a protective film containing PC and CN bonds during friction. Black phosphorus provides layered slip properties, and polydopamine enhances interfacial bonding and dispersion stability. This results in a reduction of the friction coefficient by approximately 46% when the material is added to lubricating oil or grease at 0.1 wt%. However, the preparation of this composite material requires multiple steps of liquid-phase reaction and centrifugal separation, making process control complex. Furthermore, black phosphorus is easily oxidized and degraded during processing, affecting product stability and batch consistency.

[0004] Publication No. CN120758268A discloses an ionic liquid-modified conductive two-dimensional material @MoS2 lubricating additive, its preparation method, and its application. The method involves modifying a few-layer conductive two-dimensional material with hydroxyl groups on its surface with aminosilane, then using electrostatic and hydrogen bonding to directionally aggregate a molybdenum source on the material surface. MoS2 nanosheets are then grown in situ via a hydrothermal method to form a core-shell structure. Functional modification is achieved by combining the disulfide bonds of the thioctic acid ionic liquid with the sulfur vacancies in MoS2, ultimately obtaining a composite additive with both conductive and lubricating functions. When this material is added to polyurea grease at 0.5-1.0 wt%, the friction coefficient decreases by 51.0%, and the wear volume decreases by 99.1%. It can also effectively suppress bearing galvanic corrosion by forming a conductive network. However, this preparation process involves multiple surface modification steps and complex reaction processes, requiring extremely high control over the number of layers and dispersion stability of the two-dimensional material, increasing the difficulty of industrialization.

[0005] Publication No. CN119662326A discloses a self-repairing lubricating additive for wind turbine gearboxes. The core component is micron-sized particles formed by drying and grinding layered silicates such as montmorillonite and kaolinite. It is prepared by physical grinding or chemical modification with organotin siloxane. When added to lubricating oil at 0.5-5wt%, this additive can fill the micro-pits on the worn surface and form a silicate protective layer. Combined with antioxidants and extreme pressure anti-wear agents, it can achieve the self-repair function of wear. Four-ball machine tests show that it can reduce the diameter of wear scars by 12.3-25.6%, and effectively inhibit pitting corrosion propagation in field tests of wind turbine main shaft bearings. However, this technology has high requirements for the control of silicate particle size distribution and dispersion stability, and the repair efficiency is significantly affected by the actual working conditions of the gearbox.

[0006] In summary, although existing lubricant additive technologies have made breakthroughs in specific properties, they still generally face problems such as complex preparation processes, insufficient stability of key materials, and limited long-term lubrication performance under harsh working conditions. There is an urgent need to develop new lubricant additives that combine high-efficiency lubrication performance with good engineering applicability. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive, its preparation method and application. This additive has good friction reduction and anti-wear effects, and when mixed with base oil to form a mixed oil, it can significantly improve the friction reduction and wear resistance of the material. At the same time, the preparation process is simple and the material has high stability.

[0008] To achieve the above objectives, this invention discloses a method for preparing a nano-core-shell-satellite structured CS@PDA / metal compound composite lubricant additive, comprising: uniformly coating a PDA layer on the surface of nano-core structured CS particles using the self-polymerization-adhesion properties of dopamine to form a CS@PDA intermediate with a core-shell structure; and then growing ZnO nanoparticles or LDH nanosheets in situ on the surface of the CS@PDA intermediate through hydrothermal synthesis and heat treatment processes to obtain a nano-core-shell-satellite structured CS@PDA / metal compound composite lubricant additive.

[0009] Furthermore, the specific steps include: 1) Obtain CS particles with nano-core structures; 2) Obtain Tris-HCl buffer; 3) At room temperature, add the nano-core structured CS particles obtained in step 1) to the Tris-HCl buffer obtained in step 2), and sonicate to disperse the nano-core structured CS particles uniformly to obtain suspension C; Dopamine hydrochloride was weighed and dissolved in the suspension C. After stirring, suspension D was obtained. The solution after the reaction was filtered to obtain a precipitate. Then, the precipitate was washed and dried to obtain a CS@PDA intermediate with a core-shell structure. 4) Prepare nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additives by using nano-core-shell structured CS@PDA particles.

[0010] Furthermore, the specific operation of step 2) is as follows: Tris-HCl buffer solution was prepared by adding tris(hydroxymethyl)aminomethane to deionized water and adjusting the pH to 8.5 to obtain a pH=8.5 solution.

[0011] Furthermore, in step 2), the concentration of tris(hydroxymethyl)aminomethane in the buffer solution B is 0.01-0.03 mol / L.

[0012] Furthermore, when the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant is a CS@PDA / ZnO composite lubricant, the specific process of step 4) is as follows: the nano-core-shell structure CS@PDA particles obtained in step 3) are added to deionized water and ultrasonically dispersed, then zinc acetate dihydrate is added, the pH value is adjusted and ultrasonic treatment is performed to obtain a mixed solution E; the mixed solution E is subjected to hydrothermal reaction in a reaction vessel, washed and dried to obtain the CS@PDA / ZnO composite lubricant.

[0013] Furthermore, the hydrothermal reaction was carried out at 80-100℃ for 2-4 h; the concentration of CS@PDA in the mixed solution E was 2-3 g / L, and the concentration of zinc acetate dihydrate was 0.03-0.05 mol / L.

[0014] Furthermore, when the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant is a CS@PDA / LHD composite lubricant, the specific process of step 4) is as follows: the nano-core-shell structure CS@PDA particles obtained in step 3) are added to deionized water and ultrasonically dispersed, then cobalt nitrate hexahydrate, aluminum nitrate nonahydrate and urea are added, and after ultrasonic treatment, a mixed solution F is obtained. The mixed solution F is subjected to hydrothermal reaction in a reaction vessel, washed and dried to obtain the CS@PDA / LHD composite lubricant.

[0015] Furthermore, the concentrations of CS@PDA, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, and urea in mixed solution F are 2-3 g / L, 0.005-0.02 mol / L, 0.01-0.04 mol / L, and 0.01-0.06 mol / L, respectively. The hydrothermal reaction was carried out at 90-110℃ for 20-25 hours.

[0016] This invention discloses a nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive, which is prepared based on the preparation method of the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive.

[0017] This invention discloses the application of a nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant in the field of lubricant additives.

[0018] The present invention has the following beneficial effects: The present invention relates to a nano-core-shell-satellite structured CS@PDA / metal compound composite lubricant additive, its preparation method, and its application. In specific operation, the PDA layer is uniformly coated onto the surface of the nano-core structured CS particles using the self-polymerization-adhesion properties of dopamine, forming a CS@PDA intermediate with a core-shell structure. Based on this, ZnO nanoparticles or LDH nanosheets are further grown in situ on the CS@PDA surface through controlled hydrothermal synthesis and subsequent heat treatment, ultimately constructing a CS@PDA / ZnO or CS@PDA / LDH lubricant additive with a core-shell-satellite three-level composite structure. The preparation process is simple, and in this composite structure, each component has a clear function and significant synergistic effect: the core C... S, as the rigid support core, endows the material with good mechanical strength and load-bearing capacity; the middle layer PDA not only enhances the interfacial compatibility and dispersion stability of the composite material, but its abundant functional groups also provide active sites for the heterogeneous nucleation and firm anchoring of the outer satellite particles; the outermost ZnO nanoparticles or LDH nanosheets, as "satellite" components, can effectively reduce the friction coefficient through the "micro-rolling bearing effect" during friction, while their own shear slip characteristics complement the fullerene-like carbon microspheres; in addition, the unique layered structure of LDH nanosheets enables them to adsorb and fill micro-wear pits on the friction pair surface, thereby achieving dynamic repair of the worn surface and further improving its wear resistance and extreme pressure performance. Furthermore, the core-shell-satellite composite nano-lubricant additive prepared in this invention combines the lubricity of carbon microspheres, the strong adhesion of polydopamine, and the surface repair and friction reduction capabilities of metal compounds. It exhibits excellent dispersion stability, tribological adaptability, and long-term wear resistance in base oils, and has broad application prospects in the field of high-performance lubrication. Adding 0.5wt% CS@PDA / metal compound composite lubricant additive to base oil can reduce the coefficient of friction of the base oil by 45.6-52.0% and the mating wear rate by 69.8-80.7%. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart of the method of the present invention; Figure 2 TEM image and EDS spectrum of CS particles prepared in Example 1; Figure 3 TEM image and EDS spectrum of CS@PDA particles prepared in Example 1; Figure 4a TEM image and EDS spectrum of CS@PDA / ZnO particles prepared in Example 1; Figure 4b The XRD patterns of CS, CS@PDA, and CS@PDA / ZnO prepared in Example 1 are shown. Figure 5a TEM image and EDS spectrum of CS@PDA / LDH particles prepared in Example 6; Figure 5b The XRD spectra of CS@PDA, LDH, and CS@PDA / LDH were prepared in Example 1; Figure 6 The graphs show the friction coefficient variation of Examples 1, 6, 1, 2 and 3. Figure 7 This is a schematic diagram showing the average friction coefficients of Example 1, Example 6, Comparative Example 1, Comparative Example 2, and Comparative Example 3; Figure 8 This is a schematic diagram of the wear rate for Example 1, Example 6, Comparative Example 1, Comparative Example 2, and Comparative Example 3. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0023] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0024] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0025] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0026] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0028] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0029] Carbon microspheres have attracted much attention in the field of lubricant additives due to their excellent mechanical strength, fullerene-like layered slip properties, and stable chemical inertness. However, individual carbon microspheres have high surface energy, are prone to aggregation, and have poor dispersion stability in base oils. At the same time, their smooth, chemically inert surfaces have weak interaction with friction pairs, resulting in limited anti-wear and load-bearing capacity under boundary lubrication conditions.

[0030] Polydopamine has strong adhesion and abundant surface functional groups (such as catechol and amino groups), which can form a strong and uniform coating layer with carbon microspheres through π-π stacking and strong adsorption. This effectively improves the dispersibility of carbon microspheres and introduces active sites. However, the mechanical strength and wear resistance of pure polydopamine layer are insufficient under high temperature and high pressure. The single shell structure is difficult to cope with complex extreme friction conditions.

[0031] Metal compounds, such as zinc oxide and cobalt-aluminum layered double hydroxides, can generate micro-rolling effects, shear slip, and form a protective deposition film on the friction surface during friction. They can be firmly bonded to the CS@PDA core-shell structure through coordination bonding and heterogeneous nucleation, constructing a stable "core-shell-satellite" multi-level structure. This structure can fully leverage the synergistic effect of each component: carbon microspheres act as the core to bear the main load, the polydopamine intermediate layer enhances interfacial stability and bonding force, and the external ZnO nanoparticles or LDH nanosheets significantly improve the friction reduction and wear resistance of the composite material through the "micro-bearing" effect and surface repair mechanism, thereby achieving a lubrication effect of "1+1+1>3".

[0032] Based on the above analysis, and referring to... Figure 1 The preparation method of the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive of the present invention includes the following steps: 1) Preparation of CS nanoparticles with nano-core structure; Glucose, oxalic acid, and sodium polyacrylate were added to deionized water to form solution A. Solution A was stirred evenly and then subjected to a hydrothermal reaction. After the reaction was completed, the product was collected. The product was washed and dried to obtain CS nano-core structure particles.

[0033] 2) Preparation of Tris-HCl buffer; Tris-HCl buffer solution B with pH=8.5 was prepared by adding tris(hydroxymethyl)aminomethane to deionized water and adjusting the pH to 8.5.

[0034] 3) Preparation of CS@PDA nanoparticles with core-shell structure; At room temperature, the nano-core structure CS particles obtained in step 1) were added to the Tris-HCl buffer B obtained in step 2) and ultrasonically dispersed to uniformly disperse the nano-core structure CS particles, resulting in suspension C. Weigh out dopamine hydrochloride and dissolve it in the suspension C. Stir the solution at room temperature using a magnetic stirrer to obtain suspension D. Filter the solution after the reaction using a vacuum filter to obtain a precipitate. Wash the precipitate repeatedly with deionized water until the filtrate is clear and transparent. Finally, dry the precipitate in an oven to obtain polydopamine-coated carbon microspheres (CS@PDA intermediate with a core-shell structure).

[0035] 4) Prepare nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additives by using nano-core-shell structured CS@PDA particles.

[0036] When the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant is a CS@PDA / ZnO composite lubricant, the specific process of step 4) is as follows: 41) The nano-core-shell structure CS@PDA particles obtained in step 3) are added to deionized water and ultrasonically dispersed, then zinc acetate dihydrate is added, and the pH of the solution is adjusted to 10 with NaOH solution. The mixture is ultrasonically dissolved to obtain a mixed solution E. The mixed solution E is subjected to hydrothermal reaction in a reactor, washed, and dried at 60 °C for 10 hours to obtain carbon microspheres@polydopamine / zinc oxide (CS@PDA / ZnO) composite lubricant.

[0037] When the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant is a CS@PDA / LHD composite lubricant, the specific process of step 4) is as follows: 42) The nano-core-shell structure CS@PDA particles obtained in step 3) are added to deionized water and ultrasonically dispersed. Then, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate and urea are added and ultrasonically mixed to obtain a mixed solution F. The mixed solution F is subjected to hydrothermal reaction in a reactor. After washing, it is dried at 60°C for 10 hours to obtain carbon microspheres@polydopamine / cobalt aluminum double hydroxide (CS@PDA / LDH) composite lubricant.

[0038] It should be noted that this invention uses glucose as a carbon source, catalyzes its carbonization process with oxalic acid, regulates the dispersibility of carbon microspheres with sodium polyacrylate, and promotes the formation of CS through hydrothermal reaction. The mild alkaline environment provided by the Tris-HCl buffer system induces controlled self-polymerization of dopamine on the surface of carbon microspheres, achieving uniform coating of PDA on the surface of carbon microspheres and successfully constructing a stable core-shell structure CS@PDA. Furthermore, by controlling the pH value, precursor concentration, and ratio of the hydrothermal reaction, uniform loading and firm anchoring of ZnO nanoparticles or LDH nanosheets on the CS@PDA surface are achieved, ultimately forming a "core-shell-satellite" type composite nanomaterial with high specific surface area, multi-level porous structure, and synergistic lubrication function.

[0039] The raw materials used in this invention include glucose, tris(hydroxymethyl)aminomethane, dopamine hydrochloride, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, urea, and zinc acetate dihydrate, all of which are commercially available common chemical reagents. They are inexpensive, widely available, and have advantages for large-scale production. The hydrothermal reaction, ultrasonic dispersion, magnetic stirring, and heat treatment processes all rely on conventional laboratory equipment, requiring no complex precision instruments or harsh reaction environments. The overall process is simple to operate, operates under mild conditions, has high reproducibility, and has a short batch preparation cycle, making it highly suitable for pilot-scale amplification and large-scale production.

[0040] The preparation method of carbon microspheres (CS) in step 1) directly adopts the authorized patent CN119505971A, which is as follows: prepare a solution with a glucose concentration of 0.2-0.8 mol / L and an oxalic acid mass concentration of 0.1-0.3%, and carry out a hydrothermal reaction at 160-200℃ for 8-12 h. After the reaction is completed, the microspheres are washed and dried to obtain the CS.

[0041] In step 2), the concentration of tris(hydroxymethyl)aminomethane in buffer B is 0.01-0.03 mol / L. This concentration range can provide a stable alkaline polymerization environment and avoid affecting the deposition efficiency of dopamine on the surface of carbon microspheres due to excessive pH buffering capacity.

[0042] In step 3), the concentration of carbon microspheres (CS) in suspension C is 3-5 g / L. This concentration provides sufficient active surface for polydopamine coating while ensuring adequate dispersion, thus avoiding agglomeration caused by excessive concentration.

[0043] In step 3), the concentration of dopamine hydrochloride in suspension D is 0.005-0.015 mol / L. This concentration can enable polydopamine to form a complete and appropriately thick coating layer on the surface of carbon microspheres, while avoiding homogeneous self-polymerization to form free polydopamine particles.

[0044] In step 4), the concentration of CS@PDA in mixed solution E is 2-3 g / L, and the concentration of zinc acetate dihydrate is 0.03-0.05 mol / L. This ratio provides sufficient carrier interface for heterogeneous nucleation of zinc oxide and effectively controls the supersaturation of the precursor, avoiding spontaneous precipitation of zinc species in the solution.

[0045] In step 41), the hydrothermal reaction is carried out at 80-100℃ for 2-4 h. This condition is conducive to the uniform growth of zinc oxide in nanoparticle form on the CS@PDA surface and to obtaining a good crystal structure.

[0046] In step 42), the concentration of CS@PDA in the mixed solution F is 2-3 g / L, and the concentration ranges of cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, and urea are 0.005-0.02 mol / L, 0.01-0.04 mol / L, and 0.01-0.06 mol / L, respectively. Within this concentration range, the cobalt source and aluminum source can fully co-precipitate to form the main framework of the LDH layer, while urea decomposes to provide the necessary nucleation basicity and intercalation anions. The three work together to ensure the uniform growth and good crystallization of the LDH satellite layer on the carrier surface.

[0047] In step 42), the hydrothermal reaction is carried out at 90-110℃ for 20-25 h. This condition provides the necessary time and energy for urea decomposition and sufficient nucleation and growth of LDH crystals, ultimately obtaining cobalt aluminum hydrotalcite satellite layers with good crystallinity and a well-defined layered structure.

[0048] This invention also provides a nano-core-shell-satellite structured CS@PDA / metal compound composite lubricant, such as... Figures 2-5b As shown, characterization by TEM images, EDS energy dispersive spectroscopy, and XRD patterns revealed that CS, CS@PDA, CS@PDA / ZnO, and CS@PDA / LDH were successfully prepared, and the composite materials exhibit a clear core-shell-satellite multi-level structure. This composite lubricant additive, while inheriting the high load-bearing capacity and fullerene-like slip properties of carbon microspheres, significantly enhances the interfacial bonding strength and the material's dispersion stability in lubricating oil by introducing a PDA interlayer. Furthermore, by leveraging the micro-bearing effect, surface repair, and shear-induced film-forming behavior of the outer metal compound (such as ZnO particles or LDH nanosheets) during friction, a synergistic enhancement of the friction-reducing and anti-wear properties of the carbon-based material and the metal compound is achieved, thereby significantly improving the lubrication performance of the composite system.

[0049] This invention also discloses the application of a nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive in the field of lubricant additives. The composite material can serve as a high-performance lubricant additive, widely used in various mineral oils, synthetic oils, or greases. Due to its excellent friction-reducing and anti-wear properties, good dispersion stability, and adaptive repair capability for worn surfaces, it maintains excellent lubrication performance even under harsh friction conditions such as extreme pressure and high temperature. It is suitable for lubrication protection and energy efficiency improvement in mechanical transmission systems such as engines, bearings, and gears. Specifically, adding 0.5 wt% CS@PDA / metal compound composite lubricant additive to base oil can reduce the coefficient of friction of the base oil by 45.6-52.0% and the mating wear rate by 69.8-80.7%.

[0050] Example 1 The preparation method of the CS@PDA / ZnO composite lubricant additive described in this embodiment includes the following steps: 1) Prepare a solution with a glucose concentration of 0.3 mol / L, an oxalic acid concentration of 0.02 mol / L, and a sodium polyacrylate mass content of 0.03%. After stirring evenly, add the solution to a polytetrafluoroethylene reactor and carry out a hydrothermal reaction at 180℃ for 10 h. After the reaction is completed, collect the product, wash it three times with anhydrous ethanol and deionized water, and dry it at 70℃ for 12 h to obtain CS. 2) Tris-HCl buffer solution B with pH=8.5 was prepared by adding tris(hydroxymethyl)aminomethane to deionized water to prepare a solution with a concentration of 0.02 mol / L and adjusting the pH to 8.5. 3) At room temperature, add the CS obtained in step 1) to the Tris-HCl buffer B in step 2), and sonicate to disperse the carbon microspheres uniformly, obtaining suspension C with a CS concentration of 4 g / L. Then, weigh out dopamine hydrochloride and dissolve it in suspension C. Stir the solution at room temperature using a magnetic stirrer to obtain suspension D with a dopamine hydrochloride concentration of 0.01 mol / g. Filter the reaction solution using a vacuum filter to obtain a precipitate. Wash repeatedly with deionized water until the filtrate is clear and transparent. Dry the precipitate in an oven to obtain CS@PDA. 4) Take the CS@PDA from step 3) and add it to deionized water for ultrasonic dispersion. Then add zinc acetate dihydrate and adjust the pH of the solution to 10 with NaOH solution. Ultrasonically obtain mixed solution E, in which the concentration of CS@PDA is 2.5 g / L and the concentration of zinc acetate dihydrate is 0.04 mol / L. Then carry out hydrothermal reaction of mixed solution E in a reactor at 80℃ for 3 h. After washing, dry at 60℃ for 10 h to obtain CS@PDA / ZnO composite lubricant additive.

[0051] Example 2 This embodiment discloses a method for preparing a CS@PDA / ZnO composite lubricant additive, which differs from Embodiment 1 in that: the concentration of tris(hydroxymethyl)aminomethane in step 2) is 0.01 mol / L; and the concentration of CS in step 3) is 5 g / L.

[0052] Example 3 This embodiment discloses a method for preparing a CS@PDA / ZnO composite lubricant additive, which differs from Embodiment 1 in that: the concentration of tris(hydroxymethyl)aminomethane in step 2) is 0.03 mol / L; and the concentration of CS in step 3) is 3 g / L.

[0053] Example 4 This embodiment discloses a method for preparing a CS@PDA / ZnO composite lubricant additive, which differs from Embodiment 1 in that: in step 3), the concentration of dopamine hydrochloride is 0.005 mol / L; in step 4), the concentration of CS@PDA is 2 g / L, the concentration of zinc acetate dihydrate is 0.05 mol / L, and the hydrothermal reaction is carried out at 90°C for 4 h.

[0054] Example 5 This embodiment discloses a method for preparing a CS@PDA / ZnO composite lubricant additive, which differs from Embodiment 1 in that: in step 3), the concentration of dopamine hydrochloride is 0.015 mol / L; in step 4), the concentration of CS@PDA is 3 g / L, the concentration of zinc acetate dihydrate is 0.03 mol / L, and the hydrothermal reaction is carried out at 100°C for 2 h.

[0055] Example 6 This embodiment discloses a method for preparing a CS@PDA / LDH composite lubricant additive, including the following steps: 1) Prepare a solution with a glucose concentration of 0.3 mol / L, an oxalic acid concentration of 0.02 mol / L, and a sodium polyacrylate mass content of 0.03%. After stirring evenly, add the solution to a polytetrafluoroethylene reactor and carry out a hydrothermal reaction at 180℃ for 10 h. After the reaction is completed, collect the product, wash it three times with anhydrous ethanol and deionized water, and dry it at 70℃ for 12 h to obtain CS. 2) Tris-HCl buffer solution B with pH=8.5 was prepared by adding tris(hydroxymethyl)aminomethane to deionized water to prepare a solution with a concentration of 0.02 mol / L and adjusting the pH to 8.5. 3) At room temperature, add the CS obtained in step 1) to the Tris-HCl buffer B obtained in step 2), and sonicate to disperse the carbon microspheres evenly, to obtain suspension C, in which the concentration of CS is 4 g / L. Then weigh dopamine hydrochloride and dissolve it in suspension C. Use a magnetic stirrer to stir the solution at room temperature to obtain suspension D, in which the concentration of dopamine hydrochloride is 0.01 mol / g. Filter the solution after the reaction using a vacuum filter to obtain the precipitate. Wash repeatedly with deionized water until the filtrate is clear and transparent. Place the precipitate in an oven to dry, to obtain CS@PDA.

[0056] 4) Take the CS@PDA from step 3) and add it to deionized water for ultrasonic dispersion. Then add cobalt nitrate hexahydrate, aluminum nitrate nonahydrate and urea, and ultrasonically obtain a mixed solution F, in which the concentration of CS@PDA is 2.5 g / L, the concentration of cobalt nitrate hexahydrate is 0.01 mol / L, the concentration of aluminum nitrate nonahydrate is 0.03 mol / L and the concentration of urea is 0.04 mol / L. Then carry out a hydrothermal reaction in a reactor at 100℃ for 24 h. After washing, dry at 60℃ for 10 h to obtain the CS@PDA / LDH composite lubricant additive.

[0057] Example 7 This embodiment discloses a method for preparing a CS@PDA / LDH composite lubricant additive, which differs from Embodiment Six in that: in step 4), the concentration of CS@PDA is 2 g / L, the concentration of cobalt nitrate hexahydrate is 0.02 mol / L, the concentration of aluminum nitrate nonahydrate is 0.01 mol / L, and the concentration of urea is 0.02 mol / L; the hydrothermal reaction condition is a reaction at 90°C for 25 h.

[0058] Example 8 This embodiment discloses a method for preparing a CS@PDA / LDH composite lubricant additive, which differs from Embodiment Six in that: in step 4), the concentration of CS@PDA is 3 g / L, the concentration of cobalt nitrate hexahydrate is 0.005 mol / L, the concentration of aluminum nitrate nonahydrate is 0.02 mol / L, and the concentration of urea is 0.03 mol / L; the hydrothermal reaction conditions are 110℃ for 20 h.

[0059] Example 9 This embodiment discloses a method for preparing a CS@PDA / LDH composite lubricant additive. The difference from Embodiment Six is ​​that: in step 4), the concentration of aluminum nitrate nonahydrate is 0.04 mol / L and the concentration of urea is 0.01 mol / L; the hydrothermal reaction conditions are 23 h at 100 °C.

[0060] Example 10 This embodiment discloses a method for preparing a CS@PDA / LDH composite lubricant additive. The difference from Embodiment Six is ​​that: in step 4), the concentration of aluminum nitrate nonahydrate is 0.03 mol / L and the concentration of urea is 0.06 mol / L; the hydrothermal reaction conditions are 100°C for 22 h.

[0061] Comparative Example 1 Base oil with no additives.

[0062] Comparative Example 2 This embodiment discloses a method for preparing a CS lubricating additive, including the following steps: A solution with a glucose concentration of 0.3 mol / L, an oxalic acid concentration of 0.02 mol / L, and a sodium polyacrylate content of 0.03% was prepared, stirred evenly, and then added to a polytetrafluoroethylene reactor. The hydrothermal reaction was carried out at 180℃ for 10 h. After the reaction was completed, the product was collected, washed three times with anhydrous ethanol and deionized water, and dried at 70℃ for 12 h to obtain CS. Comparative Example 2 This comparative example discloses a method for preparing a CS@PDA lubricating additive, including the following steps: 1) Prepare a solution with a glucose concentration of 0.3 mol / L, an oxalic acid concentration of 0.02 mol / L, and a sodium polyacrylate mass content of 0.03%. After stirring evenly, add the solution to a polytetrafluoroethylene reactor and carry out a hydrothermal reaction at 180℃ for 10 h. After the reaction is completed, collect the product, wash it three times with anhydrous ethanol and deionized water, and dry it at 70℃ for 12 h to obtain CS. 2) Tris-HCl buffer solution B with pH=8.5 was prepared by adding tris(hydroxymethyl)aminomethane to deionized water to prepare a solution with a concentration of 0.02 mol / L and adjusting the pH to 8.5. 3) At room temperature, add the CS obtained in step 1) to the Tris-HCl buffer B obtained in step 2), and sonicate to disperse the carbon microspheres evenly, to obtain suspension C, in which the concentration of CS is 4 g / L. Then weigh dopamine hydrochloride and dissolve it in the above suspension C. Use a magnetic stirrer to stir the solution at room temperature to obtain suspension D, in which the concentration of dopamine hydrochloride is 0.01 mol / g. Filter the solution after the reaction using a vacuum filter to obtain the precipitate. Wash repeatedly with deionized water until the filtrate is clear and transparent. Place the precipitate in an oven to dry, to obtain CS@PDA.

[0063] Example 11 The preparation method of the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive of the present invention includes the following steps: 1) Obtain CS particles with nano-core structures; 2) Tris-HCl buffer solution was prepared by adding tris(hydroxymethyl)aminomethane to deionized water and adjusting the pH value to 8.5 to obtain Tris-HCl buffer solution with pH=8.5, wherein the concentration of tris(hydroxymethyl)aminomethane in buffer solution B is 0.01 mol / L; 3) At room temperature, add the nano-core structured CS particles obtained in step 1) to the Tris-HCl buffer obtained in step 2), and sonicate to disperse the nano-core structured CS particles uniformly to obtain suspension C; Dopamine hydrochloride was weighed and dissolved in the suspension C. After stirring, suspension D was obtained. The solution after the reaction was filtered to obtain a precipitate. Then, the precipitate was washed and dried to obtain a CS@PDA intermediate with a core-shell structure. 4) Prepare nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additives by using nano-core-shell structured CS@PDA particles.

[0064] When the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant is a CS@PDA / ZnO composite lubricant, the specific process of step 4) is as follows: The nano-core-shell structure CS@PDA particles obtained in step 3) are added to deionized water and ultrasonically dispersed, then zinc acetate dihydrate is added, the pH value is adjusted, and ultrasonic treatment is performed to obtain a mixed solution E; the mixed solution E is subjected to hydrothermal reaction in a reaction vessel, washed, and dried to obtain the CS@PDA / ZnO composite lubricant, wherein the hydrothermal reaction is carried out at 80℃ for 2 hours; the concentration of CS@PDA in the mixed solution E is 2 g / L, and the concentration of zinc acetate dihydrate is 0.03 mol / L.

[0065] When the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant is a CS@PDA / LHD composite lubricant, the specific process of step 4) is as follows: The nano-core-shell structure CS@PDA particles obtained in step 3) are added to deionized water and ultrasonically dispersed. Then, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, and urea are added. After ultrasonic treatment, a mixed solution F is obtained. The mixed solution F is subjected to hydrothermal reaction in a reactor. After washing and drying, the CS@PDA / LHD composite lubricant is obtained. The concentrations of CS@PDA, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, and urea in the mixed solution F are 2 g / L, 0.005 mol / L, 0.01 mol / L, and 0.01 mol / L, respectively. The hydrothermal reaction is carried out at 90℃ for 20 h.

[0066] Example 12 The preparation method of the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive of the present invention includes the following steps: 1) Obtain CS particles with nano-core structures; 2) Tris-HCl buffer solution was prepared by adding tris(hydroxymethyl)aminomethane to deionized water and adjusting the pH value to 8.5 to obtain Tris-HCl buffer solution with pH=8.5, wherein the concentration of tris(hydroxymethyl)aminomethane in buffer solution B is 0.03 mol / L; 3) At room temperature, add the nano-core structured CS particles obtained in step 1) to the Tris-HCl buffer obtained in step 2), and sonicate to disperse the nano-core structured CS particles uniformly to obtain suspension C; Dopamine hydrochloride was weighed and dissolved in the suspension C. After stirring, suspension D was obtained. The solution after the reaction was filtered to obtain a precipitate. Then, the precipitate was washed and dried to obtain a CS@PDA intermediate with a core-shell structure. 4) Prepare nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additives by using nano-core-shell structured CS@PDA particles.

[0067] When the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant is a CS@PDA / ZnO composite lubricant, the specific process of step 4) is as follows: the nano-core-shell structure CS@PDA particles obtained in step 3) are added to deionized water and ultrasonically dispersed, then zinc acetate dihydrate is added, the pH value is adjusted and ultrasonic treatment is performed to obtain a mixed solution E; the mixed solution E is subjected to hydrothermal reaction in a reaction vessel, washed and dried to obtain the CS@PDA / ZnO composite lubricant, wherein the hydrothermal reaction is carried out at 100℃ for 4 h; the concentration of CS@PDA in the mixed solution E is 3 g / L and the concentration of zinc acetate dihydrate is 0.05 mol / L.

[0068] When the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant is a CS@PDA / LHD composite lubricant, the specific process of step 4) is as follows: The nano-core-shell structure CS@PDA particles obtained in step 3) are added to deionized water and ultrasonically dispersed. Then, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, and urea are added. After ultrasonic treatment, a mixed solution F is obtained. The mixed solution F is subjected to hydrothermal reaction in a reactor. After washing and drying, the CS@PDA / LHD composite lubricant is obtained. The concentrations of CS@PDA, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, and urea in the mixed solution F are 3 g / L, 0.02 mol / L, 0.04 mol / L, and 0.06 mol / L, respectively. The hydrothermal reaction is carried out at 110℃ for 25 h.

[0069] Example 13 The preparation method of the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive of the present invention includes the following steps: 1) Obtain CS particles with nano-core structures; 2) Tris-HCl buffer solution was prepared by adding tris(hydroxymethyl)aminomethane to deionized water and adjusting the pH value to 8.5 to obtain a Tris-HCl buffer solution with pH=8.5, wherein the concentration of tris(hydroxymethyl)aminomethane in the buffer solution B is 0.02 mol / L; 3) At room temperature, add the nano-core structured CS particles obtained in step 1) to the Tris-HCl buffer obtained in step 2), and sonicate to disperse the nano-core structured CS particles uniformly to obtain suspension C; Dopamine hydrochloride was weighed and dissolved in the suspension C. After stirring, suspension D was obtained. The solution after the reaction was filtered to obtain a precipitate. Then, the precipitate was washed and dried to obtain a CS@PDA intermediate with a core-shell structure. 4) Prepare nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additives by using nano-core-shell structured CS@PDA particles.

[0070] When the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant is a CS@PDA / ZnO composite lubricant, the specific process of step 4) is as follows: The nano-core-shell structure CS@PDA particles obtained in step 3) are added to deionized water and ultrasonically dispersed, then zinc acetate dihydrate is added, the pH value is adjusted, and ultrasonic treatment is performed to obtain a mixed solution E; the mixed solution E is subjected to hydrothermal reaction in a reaction vessel, washed, and dried to obtain the CS@PDA / ZnO composite lubricant, wherein the hydrothermal reaction is carried out at 90℃ for 3 h; the concentration of CS@PDA in the mixed solution E is 2.5 g / L, and the concentration of zinc acetate dihydrate is 0.04 mol / L.

[0071] When the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant is a CS@PDA / LHD composite lubricant, the specific process of step 4) is as follows: The nano-core-shell structure CS@PDA particles obtained in step 3) are added to deionized water and ultrasonically dispersed. Then, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, and urea are added. After ultrasonic treatment, a mixed solution F is obtained. The mixed solution F is subjected to hydrothermal reaction in a reactor. After washing and drying, the CS@PDA / LHD composite lubricant is obtained. The concentrations of CS@PDA, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, and urea in the mixed solution F are 2.5 g / L, 0.01 mol / L, 0.02 mol / L, and 0.03 mol / L, respectively. The hydrothermal reaction is carried out at 100℃ for 23 h.

[0072] Figures 6-8 The friction coefficient curves, average friction coefficients, and wear rates of the samples obtained from Example 1 (CS@PDA / ZnO), Example 6 (CS@PDA / LDH), Comparative Examples 1, 2, and 3 are shown in the figures. As can be seen from the figures, the CS@PDA / ZnO and CS@PDA / LDH composite lubricating additives exhibit superior tribological properties compared to the base oils. Specifically, their average friction coefficients decreased from 0.125 for the base oil to 0.068 and 0.060, respectively, a reduction of 45.6%–52.0%; the wear rate decreased from 9.01 × 10⁻⁶ for the base oil. -6 mm³ / (N·m) decreased to 2.72×10 -6mm³ / (N·m) and 1.74×10 - 6 The friction coefficients of the two composite materials decreased by 69.8%-80.7% respectively, with a reduction of mm³ / (N·m). Furthermore, the friction coefficient curves of both composite materials exhibited smaller fluctuations and greater stability, indicating a more stable lubrication state and excellent anti-wear durability during friction. This demonstrates that the present invention can significantly improve the friction-reducing and anti-wear properties of base oils through a synergistic lubrication mechanism involving multiple components and multi-scale structures, while also possessing excellent operational stability. It has clear application potential and promotional value in the field of high-performance lubrication.

[0073] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0074] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0075] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a nano-core-shell-satellite structured CS@PDA / metal compound composite lubricant additive, characterized in that, include: By utilizing the self-polymerization-adhesion properties of dopamine, a PDA layer is uniformly coated on the surface of nano-core structured CS particles to form a CS@PDA intermediate with a core-shell structure; Then, through hydrothermal synthesis and heat treatment processes, ZnO nanoparticles or LDH nanosheets are grown in situ on the surface of the CS@PDA intermediate to obtain a nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive.

2. The preparation method of the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive according to claim 1, characterized in that, Specifically, the following steps are included: 1) Obtain CS particles with nano-core structures; 2) Obtain Tris-HCl buffer; 3) At room temperature, add the nano-core structured CS particles obtained in step 1) to the Tris-HCl buffer solution obtained in step 2), and sonicate to disperse the nano-core structured CS particles uniformly to obtain suspension C; Dopamine hydrochloride was weighed and dissolved in the suspension C. After stirring, suspension D was obtained. The solution after the reaction was filtered to obtain a precipitate. Then, the precipitate was washed and dried to obtain a CS@PDA intermediate with a core-shell structure. 4) Prepare nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additives by using nano-core-shell structured CS@PDA particles.

3. The preparation method of the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive according to claim 2, characterized in that, The specific operation of step 2) is as follows: Tris-HCl buffer solution was prepared by adding tris(hydroxymethyl)aminomethane to deionized water and adjusting the pH to 8.5 to obtain a pH=8.5 solution.

4. The preparation method of the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive according to claim 3, characterized in that, In step 2), the concentration of tris(hydroxymethyl)aminomethane in buffer B is 0.01-0.03 mol / L.

5. The preparation method of the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive according to claim 2, characterized in that, When the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant is a CS@PDA / ZnO composite lubricant, the specific process of step 4) is as follows: the nano-core-shell structure CS@PDA particles obtained in step 3) are added to deionized water and ultrasonically dispersed, then zinc acetate dihydrate is added, the pH value is adjusted and ultrasonic treatment is performed to obtain a mixed solution E; the mixed solution E is subjected to hydrothermal reaction in a reaction vessel, washed and dried to obtain the CS@PDA / ZnO composite lubricant.

6. The preparation method of the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive according to claim 5, characterized in that, The hydrothermal reaction was carried out at 80-100℃ for 2-4 h; the concentration of CS@PDA in the mixed solution E was 2-3 g / L, and the concentration of zinc acetate dihydrate was 0.03-0.05 mol / L.

7. The preparation method of the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive according to claim 2, characterized in that, When the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant is a CS@PDA / LHD composite lubricant, the specific process of step 4) is as follows: the nano-core-shell structure CS@PDA particles obtained in step 3) are added to deionized water and ultrasonically dispersed, then cobalt nitrate hexahydrate, aluminum nitrate nonahydrate and urea are added, and after ultrasonic treatment, a mixed solution F is obtained. The mixed solution F is subjected to hydrothermal reaction in a reaction vessel, washed and dried to obtain the CS@PDA / LHD composite lubricant.

8. The preparation method of the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive according to claim 7, characterized in that, The concentrations of CS@PDA, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, and urea in mixed solution F were 2-3 g / L, 0.005-0.02 mol / L, 0.01-0.04 mol / L, and 0.01-0.06 mol / L, respectively. The hydrothermal reaction was carried out at 90-110℃ for 20-25 hours.

9. A nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive, characterized in that, It was prepared based on the preparation method of the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant according to any one of claims 1-8.

10. The application of the nano-core-shell-satellite structure CS@PDA / metal compound composite lubricant additive as described in claim 9 in the field of lubricant additives.

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