High-thermal-conductivity graphene composite material for self-lubricating coating and preparation process of high-thermal-conductivity graphene composite material

Abstract

The invention relates to the field of graphene composite materials, in particular to a high-thermal-conductivity graphene composite material for a self-lubricating coating, which is prepared from the following components in percentage by mass: 45 to 55 percent of matrix material, 10 to 15 percent of graphene, 20 to 25 percent of metal sulfide, 10 to 13 percent of high-thermal-conductivity filler, 3 to 5 percent of dispersing agent and 1 to 2 percent of interface modifier, in addition, the invention further discloses a preparation method of the high-thermal-conductivity graphene composite material for the self-lubricating coating, and the preparation method comprises the steps of raw material pretreatment, premixing, multi-stage jet mill compounding, post-treatment and the like. Stable and uniform dispersion of fluorinated graphene in a system is successfully realized, the problem of stress concentration caused by agglomeration is thoroughly avoided, and the mechanical integrity of the composite material and the consistency of tribological properties are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of graphene composite materials, specifically relating to a high thermal conductivity graphene composite material for self-lubricating coatings and its preparation process. Background Technology

[0002] Graphene, due to its excellent thermal conductivity and mechanical strength, is considered an ideal additive for constructing next-generation high-performance self-lubricating composite materials. Its thermal conductivity allows it to maintain stable operation even at high temperatures, while its superior mechanical strength provides excellent durability and resistance to damage. These properties make graphene a promising candidate for self-lubricating composite materials, significantly improving overall material performance and expanding its application range. Particularly in mechanical equipment operating under extreme conditions, the addition of graphene can effectively reduce friction and improve equipment lifespan and reliability.

[0003] Existing technologies typically employ physical-mechanical mixing (such as ball milling or high-speed stirring) or in-situ growth methods to combine graphene with layered solid lubricants such as molybdenum disulfide and tungsten disulfide, in order to obtain materials that possess both good thermal conductivity and friction-reducing and wear-resistant properties.

[0004] However, existing traditional methods have significant limitations. In current technologies, it is difficult to achieve uniform dispersion of graphene in the matrix through physical mixing, as it is prone to re-agglomeration, which becomes stress concentration points and impairs the material's mechanical properties and tribological consistency. Simultaneously, the interaction between graphene and lubricant particles is mostly simple physical adsorption, resulting in weak interfacial bonding. Under continuous frictional shear forces, the lubricant component is prone to detachment and failure, affecting the coating's lifespan. Furthermore, existing processes lack effective control over the microstructure of the composite material, failing to construct a superior thermally conductive network and thus failing to fully realize the material's high thermal conductivity potential. Therefore, overcoming these technical problems and shortcomings is a key issue that needs to be addressed. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects described in the background art, thereby realizing a high thermal conductivity graphene composite material for self-lubricating coatings, to solve the problems in the prior art such as weak interfacial bonding and poor compatibility between graphene and metal sulfide lubricants, resulting in unsatisfactory thermal conductivity of composite materials, easy failure of lubricating components, and the inability of traditional mixing processes to construct stable and ordered microstructures.

[0006] To achieve the above-mentioned objectives, the technical solution of this invention is: a high thermal conductivity graphene composite material for self-lubricating coatings, prepared from components comprising the following mass percentages: matrix material 45%-55%; graphene 10%-15%; metal sulfide 20%-25%; high thermal conductivity filler 10%-13%; dispersant 3%-5%; and interface modifier 1%-2%.

[0007] Specifically, the matrix material is epoxy resin or polyimide.

[0008] Specifically, the graphene is fluorinated graphene, with a fluorine atom content of 2.0wt%-3.0wt%, a carbon-fluorine bond content of more than 60% of the total fluorine content, 3-8 layers, and a specific surface area ≥500m² / g.

[0009] Specifically, the metal sulfide is a complex of molybdenum disulfide and tungsten disulfide, and preferably, the mass ratio of molybdenum disulfide to tungsten disulfide is 1:1-3.

[0010] Specifically, the high thermal conductivity filler is boron nitride or silicon carbide;

[0011] Specifically, the dispersant is a complex of polyetherimide and hydroxypropyl methylcellulose in a mass ratio of 1:1 to 2:1.

[0012] Preferably, the interface modifier is a silane coupling agent or a titanate coupling agent.

[0013] Preferably, the polyetherimide in the dispersant has a weight-average molecular weight range of 20,000-40,000 g / mol, the hydroxypropyl methylcellulose has a molecular weight range of 40,000-60,000 g / mol, and its 2% aqueous solution has a viscosity of 3,000-6,000 mPa·s at 20°C.

[0014] Preferably, the composite material is prepared by high-pressure air jet milling process to form a core-shell interlayer composite structure with metal sulfide as the core and fluorinated graphene embedded and coated by mechanochemical action; the tap density of the composite powder is 0.8-1.5 g / cm³, the thermal conductivity is ≥10 W / (m·K), and the friction coefficient is ≤0.15.

[0015] Preferably, the particle size distribution of the composite powder is: D10≥0.5μm, D50=1.0-2.5μm, D90≤5.0μm, and the particle size distribution span Span=(D90-D10) / D50≤2.0, where D10, D50, and D90 are the particle sizes corresponding to the volume cumulative distribution.

[0016] This invention also discloses a method for preparing the above-mentioned high thermal conductivity graphene composite material, comprising the following steps:

[0017] Step 1: Raw material pretreatment; fluorinated graphene is vacuum dried at 90-100℃ for 4-5 hours, and metal sulfides are dried at 110-120℃ for 2-3 hours.

[0018] Step 2: Premixing; According to the formula, the dried raw materials, dispersant, and interface modifier are mixed in a three-dimensional mixer at a speed of 20-50 rpm for 0.5-1.5 hours to obtain a premixed powder with preliminary dispersion.

[0019] Step 3: Multi-stage air jet milling; The premixed powder is fed into a high-pressure air jet mill and sequentially compounded using at least two stages of process parameters.

[0020] The first-stage composite process is carried out under low airflow pressure and high feed rate to achieve preliminary crushing and macroscopic homogenization of each component. The second-stage composite process is carried out under high airflow pressure and low feed rate to achieve strong interfacial bonding between graphene and metal sulfides and to construct a core-shell interlayer composite structure.

[0021] Step 4: Post-processing; After collecting the composite powder, it is sieved to remove uncomposite free powder and obtain the high thermal conductivity graphene composite material.

[0022] Preferably, in the multi-stage airflow milling process of step three, during the first stage of the process, the grinding gas pressure is 0.6-0.9 MPa; the feed rate is 8-12 kg / h; the classifying wheel speed is 3000-5000 rpm; and the processing time accounts for 20%-30% of the total processing time.

[0023] During the second-stage compounding process, the grinding gas pressure is 1.0-1.5 MPa; the feed rate is 3-6 kg / h; the classifying wheel speed is 6000-8000 rpm; and the processing time accounts for 70%-80% of the total compounding time.

[0024] Specifically, in the multi-stage airflow milling process, the specific mechanical energy applied in each stage of the process... Satisfying the formula:

[0025] ;

[0026] In the formula, This refers to the installed power of the air jet mill. This is the processing time for this level. The quality of materials processed at this stage.

[0027] The first-level composite The concentration is controlled within the range of 2.0-4.0 kWh / kg for initial compounding, and for the second-stage compounding. It is controlled within the range of 8.0-15.0 kWh / kg and is used to enhance interfacial bonding and core-shell structure construction.

[0028] Preferably, during the air jet milling process, the nozzle pressure fluctuation range is controlled within ±0.2MPa; the gas temperature fluctuation range is controlled within ±5℃; the feed rate stability deviation is controlled within ±5%; and the classifier speed deviation is controlled within ±300rpm.

[0029] This invention also discloses a self-lubricating coating, prepared from the following components in parts by weight: 20-35 parts of the high thermal conductivity graphene composite material as described above; 25-45 parts of a high-temperature resistant binder, wherein the binder is a silicon-modified phenolic resin or a boron-modified polyimide; 30-50 parts of a solvent, wherein the solvent is N-methylpyrrolidone or dimethylacetamide; and 1-3 parts of an additive, wherein the additive includes a leveling agent BYK-333 and a defoamer BYK-055 compounded in a mass ratio of 2:1.

[0030] The high thermal conductivity graphene composite material for self-lubricating coatings of the present invention has the following beneficial effects:

[0031] 1. The high thermal conductivity graphene composite material for self-lubricating coating of the present invention, through a specially designed dispersant combination and a high-pressure air jet mill multi-stage composite process, successfully achieves stable and uniform dispersion of fluorinated graphene in the system, completely avoids the stress concentration problem caused by agglomeration, and significantly improves the mechanical integrity and tribological performance consistency of the composite material.

[0032] 2. This invention utilizes mechanochemical interaction to construct a strong interfacial chemical bond between graphene and metal sulfides, forming a stable composite structure with a lubricant core and graphene shell. This structure greatly enhances the interfacial bonding force, making the lubricating components less prone to detachment and failure under continuous friction, thereby significantly extending the service life of the coating.

[0033] 3. This invention, through the synergistic effect of optimized component ratios and composite processes, constructs a highly efficient and continuous three-dimensional thermally conductive network within the material. This fully leverages the potential of graphene and high thermal conductivity fillers, significantly improving the overall thermal conductivity of the composite material. It addresses the pain point of existing materials failing to meet expected thermal conductivity, providing a more efficient solution for thermal management of electronic devices and contributing to improved stability and reliability of electronic products. Furthermore, this material has wide applicability across multiple fields, demonstrating strong market potential and application value.

[0034] 4. This invention ensures the reliability and consistency of the composite material's microstructure by precisely controlling key process parameters in the preparation process, thereby exhibiting superior and stable comprehensive performance, significantly better than materials prepared by traditional simple physical mixing. The technical solution of this invention can fully meet the stringent requirements of high-end equipment for self-lubricating coating performance. Detailed Implementation

[0035] The high thermal conductivity graphene composite material for self-lubricating coating of the present invention will be described in more detail below through specific embodiments.

[0036] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship shown, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0037] Example 1

[0038] This embodiment discloses a high thermal conductivity graphene composite material for self-lubricating coatings. By optimizing its raw materials, proportions, and processes, it addresses the problems in existing technologies, such as weak interfacial bonding and poor compatibility between graphene and metal sulfide lubricants, leading to unsatisfactory thermal conductivity of the composite material, easy failure of the lubricating component, and the inability of traditional mixing processes to construct a stable and ordered microstructure. See below for details.

[0039] The high thermal conductivity graphene composite material for self-lubricating coating is prepared from the following components by mass percentage: matrix material 45%-55%; graphene 10%-15%; metal sulfide 20%-25%; high thermal conductivity filler 10%-13%; dispersant 3%-5%; interface modifier 1%-2%.

[0040] Specifically, the matrix material is epoxy resin or polyimide; the graphene is fluorinated graphene with a fluorine atom content of 2.0wt%-3.0wt%, a carbon-fluorine bond content of more than 60% of the total fluorine content, 3-8 layers, and a specific surface area ≥500m² / g.

[0041] The metal sulfide is a composite of molybdenum disulfide and tungsten disulfide, wherein the mass ratio of molybdenum disulfide to tungsten disulfide is 1:1-3. The high thermal conductivity filler is boron nitride or silicon carbide. The interface modifier is silane coupling agent KH-560 or titanate coupling agent NDZ-201.

[0042] The dispersant is a complex of polyetherimide and hydroxypropyl methylcellulose in a mass ratio of 1:1 to 2:1.

[0043] In this embodiment, epoxy resin or polyimide is selected as the matrix material, providing good film-forming properties and mechanical support, thus providing structural support and temperature resistance for the composite material. Fluorinated graphene, with its specific fluorine content and carbon-fluorine bond ratio, introduces lubricating properties while maintaining high thermal conductivity. A controlled layer count of 3-8 layers and a specific surface area ≥500 m² / g are achieved through an ultrasonic exfoliation-fluorination linkage process. Raman spectroscopy, BET specific surface area testing, and XPS analysis jointly verify that this material not only possesses an efficient heat transfer path but also excellent interlayer slip capability.

[0044] The metal sulfide material composed of molybdenum disulfide and tungsten disulfide, the ratio of which was determined through ball milling and friction and wear tests, can give full play to the synergistic lubrication effect of their layered structures.

[0045] High thermal conductivity fillers using boron nitride or silicon carbide possess excellent thermal conductivity. Their high thermal conductivity characteristics are verified by laser scintillation method, which can effectively improve the overall thermal management capability of composite materials and ensure their stable operation in high-temperature environments.

[0046] The dispersant is a compound of polyetherimide and hydroxypropyl methylcellulose. Polyetherimide acts as an anchoring agent and is adsorbed onto the powder surface through amino / ether bonds, while hydroxypropyl methylcellulose provides steric hindrance through its long-chain structure. The synergistic effect of the two can achieve efficient dispersion and prevent re-agglomeration, as demonstrated by Zeta potential and sedimentation experiments.

[0047] The interface modifiers selected were silane coupling agent KH-560 or titanate coupling agent NDZ-201. Infrared spectroscopy analysis and shear strength test results showed that the two coupling agents could significantly enhance the interfacial bonding force between the filler and the matrix.

[0048] The dispersant contains polyetherimide with a weight-average molecular weight range of 20,000-40,000 g / mol and hydroxypropyl methylcellulose with a molecular weight range of 40,000-60,000 g / mol. A 2% aqueous solution of these components has a viscosity of 3,000-6,000 mPa·s at 20°C. These molecular weight and viscosity ranges have been experimentally verified to optimally balance anchoring adsorption force and steric hindrance effect.

[0049] In this embodiment, multiple tests using gel permeation chromatography (GPC) verified that the weight-average molecular weight of polyetherimide was controlled within the range of 20,000-40,000 g / mol. This ensures that the molecular chain has sufficient anchoring group density and flexibility. A molecular weight below 20,000 g / mol will result in insufficient adsorption sites, reducing the coating effect on the powder; while a molecular weight above 40,000 g / mol is prone to chain entanglement, affecting the dispersion kinetics efficiency.

[0050] The molecular weight of hydroxypropyl methylcellulose was determined repeatedly using an Ubbelohde viscometer and a rheometer. The molecular weight range of hydroxypropyl methylcellulose was set to 40,000-60,000 g / mol, and the viscosity of its 2% aqueous solution at 20°C was controlled at 3,000-6,000 mPa·s. It was able to construct an effective three-dimensional hydration layer in the solvent, and successfully prevented particle re-aggregation by means of the steric hindrance effect.

[0051] When polyetherimide is compounded with hydroxypropyl methylcellulose, the polyetherimide forms a strong adsorption on the powder surface through ether bonds / amine groups, while the hydroxypropyl methylcellulose maintains the stability of the system through the high viscosity solution environment and the long chain structure.

[0052] The composite material is prepared by high-pressure air jet milling process, which utilizes the mechanochemical effect generated by the collision of particles carried by high-speed air jet to form a core-shell interlayer composite structure with metal sulfide as the core and fluorinated graphene embedded and coated by mechanochemical action; the tap density of the composite powder is 0.8-1.5 g / cm³, the thermal conductivity is ≥10 W / (m·K), and the friction coefficient is ≤0.15.

[0053] In this embodiment, the fluorinated graphene is exfoliated and activated under high-energy impact by the mechanochemical effect. The fluorine atoms on its surface bond with the dangling bonds or defect sites on the surface of the metal sulfide particles, thereby accurately constructing a core-shell interlayer composite structure with metal sulfide as the core and fluorinated graphene embedded and coated. This structure is clearly visible by SEM and TEM microscopy.

[0054] The coating of fluorinated graphene not only effectively inhibits the oxidation of metal sulfides, but also utilizes its two-dimensional sheet properties to form a continuous transfer film during friction, thereby significantly reducing the coefficient of friction (confirmed by ball-disc friction testing to be ≤0.15). Simultaneously, graphene and high thermal conductivity fillers together construct an efficient heat conduction network, ensuring that the thermal conductivity of the composite powder is consistently ≥10 W / (m·K) as measured by laser scintillation. Furthermore, the core-shell structure optimizes the powder's packing behavior, controlling its tap density within the range of 0.8-1.5 g / cm³ (measured according to GB / T 5162-2023 standard). This density range ensures both good flowability and compactness of the powder during coating preparation, while avoiding over-compaction that could affect dispersion stability.

[0055] The particle size distribution of the composite powder is as follows: D10 ≥ 0.5 μm, D50 = 1.0-2.5 μm, D90 ≤ 5.0 μm. The particle size distribution span is Span = (D90 - D10) / D50 ≤ 2.0; where D10, D50, and D90 are the particle sizes corresponding to the volumetric cumulative distribution.

[0056] Based on extensive laser diffraction particle size analysis experiments (using instruments such as the Malvern Mastersizer, with anhydrous ethanol as the dispersion medium, and strictly regulated ultrasonic dispersion for 3-5 minutes to eliminate agglomerate interference), the optimal setting of D10≥0.5μm can effectively avoid the generation of excessive ultrafine powder, thereby reducing the agglomeration tendency caused by high specific surface area and the clogging problem during the spraying process. D90≤5.0μm ensures that there are no excessively large particles in the powder, preventing the formation of stress concentration points or surface defects in the coating.

[0057] In addition, through experiments balancing the film-forming properties and functionality of the coating, the D50 was controlled within the range of 1.0-2.5μm. This particle size range ensures that the powder has good suspension stability in solvent-based slurries (observed by sedimentation experiments) and enables it to form a dense and uniform coating in subsequent spraying or scraping processes (verified by SEM analysis of the coating cross-section).

[0058] A particle size distribution span of ≤2.0 ensures excellent flowability and filling density of the composite powder in subsequent coating preparation. Tap density testing shows values ​​between 0.8-1.5 g / cm³, effectively guaranteeing the uniformity and reliability of the coating's thermal conductivity and lubrication functions. The particle size specification was established based on repeatability test data from laser diffraction and validated through correlation analysis with actual coating properties (such as friction coefficient and thermal conductivity), ensuring that the core-shell structure powder can exert a synergistic enhancement effect in the final application.

[0059] Example 2

[0060] The similarities to the above embodiments will not be repeated, the differences are as follows:

[0061] This embodiment discloses a method for preparing a high thermal conductivity graphene composite material, specifically including the following steps:

[0062] Step 1: Raw material pretreatment; Fluorinated graphene is vacuum dried at 90-100℃ for 4-5 hours, and metal sulfides are dried at 110-120℃ for 2-3 hours. The drying temperature and time in this step have been verified by TGA to ensure that the moisture content is reduced to below 0.5%, while avoiding the decomposition of fluorinated graphene or the oxidation of metal sulfides (XRD verification shows no change in crystal structure), thus providing a stable interface foundation for subsequent composite processing.

[0063] Step 2: Premixing; According to the formula, the dried raw materials, dispersant, and interface modifier are mixed in a three-dimensional mixer at a speed of 20-50 rpm for 0.5-1.5 hours to obtain a pre-dispersed premixed powder. Macroscopic homogenization is achieved through low-speed three-dimensional mixing, avoiding excessively high energy barriers that would affect the efficiency of subsequent air jet milling.

[0064] Step 3: Multi-stage air jet milling; The premixed powder is fed into a high-pressure air jet mill and sequentially compounded using at least two stages of process parameters. The specific mechanical energy applied at each stage of the process... Satisfying the formula:

[0065] ;

[0066] In the formula, This refers to the installed power of the air jet mill. This is the processing time for this level. The quality of materials processed at this stage.

[0067] The first-stage compounding process is conducted under low gas pressure and high feed rate to achieve preliminary crushing and macroscopic homogenization of the components. Specifically, in this stage of compounding, the grinding gas pressure is 0.6-0.9 MPa; the feed rate is 8-12 kg / h; the classifying wheel speed is 3000-5000 rpm; and the processing time accounts for 20%-30% of the total compounding time. The concentration is controlled within the range of 2.0-4.0 kWh / kg. This stage of compounding employs low airflow pressure and high feed rate to achieve gentle crushing and preliminary mixing, avoiding energy overload that could damage the components.

[0068] The second-stage lamination is carried out under high gas pressure and low feed rate to achieve a strong interfacial bond between graphene and metal sulfides and to construct a core-shell interlayer composite structure. In this stage of lamination, the grinding gas pressure is 1.0-1.5 MPa; the feed rate is 3-6 kg / h; the classifying wheel speed is 6000-8000 rpm; and the processing time accounts for 70%-80% of the total lamination time. The energy level is controlled within the range of 8.0-15.0 kWh / kg. High-pressure airflow increases particle kinetic energy, while low feed rate prolongs particle residence time in the grinding zone. Combined with high classifying wheel speed, this enhances particle classification and collision frequency, collectively promoting the exfoliation of fluorinated graphene sheets and their embedding and coating on metal sulfides and surfaces. High SME induces mechanochemical effects, providing sufficient energy for the exfoliation and activation of fluorinated graphene, which then forms chemical bonds such as CF-Mo / W with the surface of metal sulfides (verified by XPS), thereby constructing a robust core-shell structure (verified by TEM).

[0069] Compared with the single-stage air jet mill experiment, the two-stage process in this embodiment increases the core-shell structure formation rate of the composite powder from about 55% to over 95% (based on SEM statistics), and improves the composite efficiency by more than 40%. At the same time, it avoids the nano-agglomeration of particles caused by excessive grinding (particle size distribution Span value is stable ≤2.0), ensuring the dispersion stability and functional consistency of the powder in coating applications.

[0070] Step 4: Post-processing; The composite powder is collected and sieved to remove uncomposite free powder, obtaining the high thermal conductivity graphene composite material. Based on laser particle size analysis data, uncomposite free powder (accounting for <3%) is effectively removed to ensure that the final composite powder has consistent performance and reliability.

[0071] During the airflow milling process, the nozzle pressure fluctuation range is controlled within ±0.2MPa; the gas temperature fluctuation range is controlled within ±5℃; the feed rate stability deviation is controlled within ±5%; and the classifier speed deviation is controlled within ±300rpm.

[0072] In this embodiment, excessive nozzle pressure fluctuations can lead to significant changes in airflow kinetic energy, directly affecting particle collision energy and crushing efficiency. Through pressure sensor and statistical process control (SPC) analysis, it was verified that exceeding this range (±0.2MPa) can cause the particle size distribution span (Span value) of the composite powder to fluctuate by more than 15%, thereby affecting the coating uniformity.

[0073] To prevent changes in density and flow rate caused by thermal expansion and contraction of the gas, gas temperature fluctuations are limited to within ±5°C. Temperature sensor monitoring data shows that temperature fluctuations exceeding this limit can cause changes in gas dynamic viscosity exceeding 8%, leading to a decrease in particle transport and classification efficiency and triggering the degradation of heat-sensitive components (such as dispersants).

[0074] The stability deviation of the feed rate is controlled within ±5%. Experimental data shows that if the feed rate fluctuation exceeds ±5%, the mechanical energy input per unit material (SME) will deviate by more than 10%, resulting in different degrees of core-shell structure coverage (verified by SEM statistics).

[0075] The rotational speed deviation of the classifying wheel is controlled within ±300 rpm. Laser particle size analysis shows that rotational speed fluctuations exceeding this range will cause the target particle size (D50) to shift by more than 0.3 μm, which can easily lead to an imbalance in the overall gradation of the powder. By controlling process parameters to ensure the stability and repeatability of the mechanochemical interaction, the core-shell structure formation rate of the final composite powder is stabilized at over 95%, and the fluctuation range of thermal conductivity and frictional properties is less than 5%, significantly improving product consistency.

[0076] Example 3

[0077] The similarities with the above embodiments and their combinations will not be repeated, the differences being:

[0078] This embodiment discloses a self-lubricating coating, which is prepared from the following components in parts by weight: 20-35 parts of the high thermal conductivity graphene composite material as described above; 25-45 parts of the high temperature resistant binder; 30-50 parts of the solvent; and 1-3 parts of the additives.

[0079] The binder is a silicone-modified phenolic resin or a boron-modified polyimide, the solvent is N-methylpyrrolidone or dimethylacetamide, and the additives include leveling agent BYK-333 and defoamer BYK-055 compounded in a mass ratio of 2:1.

[0080] Example 4

[0081] The similarities with the above embodiments and their combinations will not be repeated, the differences being:

[0082] This embodiment provides a high thermal conductivity graphene composite material for self-lubricating coatings, prepared from the following raw materials by weight percentage:

[0083] The composition includes: 48% matrix material (epoxy resin); 13% fluorinated graphene; 20% metal sulfide (MoS2:WS2=1:1); 13% high thermal conductivity filler (boron nitride); 4% dispersant, of which the ratio of polyetherimide to hydroxypropyl methylcellulose is 1.5:1; and 2% interface modifier (KH-560).

[0084] In this embodiment, the proportion of high thermal conductivity filler (boron nitride) to graphene is 26%. Based on the theory of thermal conductivity pathways, this ratio can maximize the construction of a three-dimensional thermally conductive network. Boron nitride itself has a high in-plane thermal conductivity (300-600 W / (m·K)), and in synergy with graphene, it can effectively overcome the intrinsic low thermal conductivity of the polymer matrix to form an efficient thermally conductive pathway.

[0085] Fluorinated graphene provides both thermal conductivity and lubricity. Laser flare analysis (LFA) showed that when boron nitride content was increased to 13%, the thermal conductivity of the composite material significantly improved from 9.5 W / (m·K) to ≥11.5 W / (m·K). SEM images revealed that boron nitride and graphene interlocked to form a more continuous network.

[0086] In addition, with a metal sulfide content of 20%, the friction coefficient test results show that its friction coefficient is between 0.13 and 0.15, ensuring a certain level of lubrication performance while leaving room for high thermal conductivity fillers. Furthermore, this composite material uses a high content of dispersant and interface modifier to improve the compatibility between the filler and the resin matrix. Scanning electron microscopy (SEM) observation of the coating cross-section shows that the filler is uniformly dispersed and without large-scale agglomeration.

[0087] The preparation process of the high thermal conductivity graphene composite material with self-lubricating coating in this embodiment is as follows: First, fluorinated graphene is vacuum dried at 100°C for 5 hours, and molybdenum disulfide and tungsten disulfide are dried at 120°C for 3 hours; then, all the dried raw materials, dispersant, and interface modifier are added to a three-dimensional mixer according to the above ratio and mixed at 35 rpm for 1.2 hours to obtain premixed powder; then, the premixed powder is fed into a high-pressure air jet mill for two-stage compounding: the first stage is carried out at a grinding pressure of 0.8 MPa, a feed rate of 10 kg / h, and a grinding speed of 40... The first stage involves processing the material at a classifying wheel speed of 00 rpm (SME≈3.2 kWh / kg) to achieve initial dispersion and crushing. The second stage involves processing the material at a grinding air pressure of 1.3 MPa, a feed rate of 4.5 kg / h, and a classifying wheel speed of 7200 rpm (SME≈12.5 kWh / kg) to construct a dense core-shell structure with metal sulfides as the core and fluorinated graphene as the coating through high-energy mechanochemical action. Finally, the composite powder is sieved through a screen to remove a very small amount of uncomposite free large particles, resulting in the final high thermal conductivity graphene composite material.

[0088] The performance test results of the high thermal conductivity graphene composite material with self-lubricating coating prepared by the above ratio are shown in Table 1:

[0089] Performance indicators Test methods / standards Data results of this solution Basis and Objectives thermal conductivity ASTM E1461(LFA) 12.5-14.0 W / (m·K) ≥10W / (m·K) coefficient of friction ASTM G99 (Ball-Disc) 0.12-0.14 ≤0.15 Tap density GB / T 5162-2023 1.30-1.45 g / cm³ 0.8-1.5g / cm³ D50 particle size ISO 13320 (Laser Diffraction) 1.8-2.2μm 1.0-2.5μm Span value Calculate: (D90-D10) / D50 1.6-1.9 ≤2.0 Coating surface temperature difference Infrared thermal imager <5 °C (50 x 50 mm area) Characterizing thermal conductivity uniformity

[0090] Table 1

[0091] Experimental evidence shows that the composite material finally obtained by the above formulation and process has excellent thermal conductivity, can quickly and effectively dissipate frictional heat and external environmental heat, prevent components from failing due to overheating, and can maintain good lubricity and mechanical strength. It is suitable for heat dissipation interface materials of high power density electronic devices (such as CPU / GPU heat dissipation coatings), high-speed precision bearings and other extreme working conditions that need to cope with high heat flow and friction.

[0092] Example 5

[0093] The similarities with the above embodiments and their combinations will not be repeated, the differences being:

[0094] This embodiment provides a high thermal conductivity graphene composite material for self-lubricating coatings, prepared from the following raw materials by weight percentage:

[0095] The composition includes: 48% matrix material (polyimide); 11% fluorinated graphene; 23% metal sulfide (MoS2:WS2=1:3); 11% high thermal conductivity filler (silicon carbide); 5% dispersant, wherein the ratio of polyetherimide to hydroxypropyl methylcellulose is 1:1; and 2% interface modifier (NDZ-201).

[0096] In this embodiment, a high metal sulfide with a content of 23% (MoS2:WS2=1:3) was used to test the material on a four-ball friction and wear tester. The material with this ratio has the highest ultimate load (PB value) (>800N), and the coefficient of friction can be stabilized at 0.07-0.10 under high pressure.

[0097] Furthermore, using a polyimide matrix and the interface modifier NDZ-201, TGA results showed that the weight loss of the polyimide-based composite material after 400°C was significantly less than that of the epoxy resin system. The interface modifier NDZ-201 exhibits better surface compatibility with metal sulfides, enhancing the bonding force between the lubricant and the matrix and preventing extrusion under heavy loads.

[0098] The preparation process of the high thermal conductivity graphene composite material with self-lubricating coating in this embodiment is as follows: First, fluorinated graphene is vacuum dried at 100℃ for 5 hours, and molybdenum disulfide and tungsten disulfide are dried at 120℃ for 3 hours. Then, all the dried raw materials, dispersant, and interface modifier are added to a three-dimensional mixer according to the above ratio and mixed at 40 rpm for 1 hour to obtain premixed powder. Next, the premixed powder is fed into a high-pressure air jet mill for two-stage compounding: the first stage is processed at a grinding air pressure of 0.7 MPa, a feed rate of 11 kg / h, and a classifying wheel speed of 3500 rpm (SME≈2.8 kWh / kg) to achieve preliminary dispersion and crushing; the second stage is processed at a grinding air pressure of 1.1 MPa, a feed rate of 5.5 kg / h, and a classifying wheel speed of 6500 rpm (SME≈9.0 kWh / kg); finally, the composite powder is sieved through a screen to obtain the final high thermal conductivity graphene composite material.

[0099] The performance test results of the high thermal conductivity graphene composite material with self-lubricating coating prepared by the above ratio are shown in Table 2:

[0100] Performance indicators Test methods / standards Data results of this solution Basis and Objectives coefficient of friction ASTM G99 0.07-0.10 ≤0.15 Wear rate ASTM G133 1.2 x 10⁻ 6 mm³ / N·m Extremely low wear rate Ultimate load (PB) ASTM D2596 >800N High load-bearing capacity thermal conductivity LFA 10.0-11.5 W / (m·K) ≥10W / (m·K) Thermal decomposition temperature <![CDATA[TGA(N2,10℃ / min)]]> >500℃ (5% wt loss) High temperature stability

[0101] Table 2

[0102] Experimental evidence shows that the composite material obtained through the above formulation and process has an extremely low coefficient of friction, extremely high load-bearing capacity, and excellent wear resistance. It exhibits stability under high pressure and low speed conditions and excellent high-temperature resistance. It is suitable for applications such as sliding bearings and gear surfaces in heavy machinery, and automotive chassis components that withstand extreme heavy loads and impact loads at relatively low speeds.

[0103] Example 6

[0104] The similarities with the above embodiments and their combinations will not be repeated, the differences being:

[0105] This embodiment provides a high thermal conductivity graphene composite material for self-lubricating coatings, prepared from the following raw materials by weight percentage:

[0106] The composition includes: 51% matrix material (epoxy resin); 12% fluorinated graphene; 20% metal sulfide (MoS2:WS2=1:2); 11% high thermal conductivity filler (boron nitride); 4% dispersant, of which the ratio of polyetherimide to hydroxypropyl methylcellulose is 1.8:1; and 2% interface modifier (KH-560).

[0107] In this embodiment, all performance indicators consistently fall within the excellent range under this formulation, with the best batch consistency, and the cost is more advantageous compared to higher content formulations. According to LFA (laser flare method) test results, the thermal conductivity remains stable between 10.5-12.0 W / (m·K). The coefficient of friction remains in the low range of 0.10-0.13. In the cross-cut adhesion test, this formulation successfully achieved the highest grade 5B, demonstrating excellent adhesion performance.

[0108] The preparation process of the high thermal conductivity graphene composite material with self-lubricating coating in this embodiment is as follows: First, fluorinated graphene is vacuum dried at 100℃ for 5 hours, and molybdenum disulfide and tungsten disulfide are dried at 120℃ for 3 hours. Then, all the dried raw materials, dispersant, and interface KH-560 are added to a three-dimensional mixer according to the above ratio and mixed at 30 rpm for 1 hour to obtain premixed powder. Next, the premixed powder is fed into a high-pressure air jet mill for two-stage compounding: the first stage is processed at a grinding air pressure of 0.8MPa, a feed rate of 10kg / h, and a classifying wheel speed of 4500rpm (SME≈3.5kWh / kg) to achieve preliminary dispersion and crushing; the second stage is processed at a grinding air pressure of 1.2MPa, a feed rate of 5kg / h, and a classifying wheel speed of 7000rpm (SME≈11.0kWh / kg); finally, the composite powder is sieved through a screen to obtain the final high thermal conductivity graphene composite material.

[0109] The performance test results of the high thermal conductivity graphene composite material with self-lubricating coating prepared by the above ratio are shown in Table 3:

[0110] Performance indicators Test methods / standards Data results of this solution Basis and Objectives thermal conductivity LFA 10.5-12.0 W / (m·K) ≥10W / (m·K) coefficient of friction ASTM G99 0.10-0.13 ≤0.15 Abrasion resistance (volume loss) Ring-block test <![CDATA[<5×10⁻ 6 mm³ / N·m]]> Good wear resistance Adhesion (cross-cut test) ASTM D3359 5B Excellent coating adhesion Cost Index (Relative assessment) 1.0 (Baseline) Best value for money

[0111] Table 3

[0112] Experimental evidence shows that the composite material obtained through the above formulation and process achieves an optimal balance between thermal conductivity, lubrication, mechanical strength, adhesion, and cost, exhibiting excellent overall performance, good process stability, and suitability for mass production. It is applicable to most common working conditions, such as bearings in household appliances, joints in industrial robots, bearings for medium- and low-speed motors, and heat dissipation coatings for general electronic equipment, making it the most widely used general-purpose solution.

[0113] Example 7

[0114] The similarities with the above embodiments and their combinations will not be repeated, the differences being:

[0115] This embodiment provides a high thermal conductivity graphene composite material for self-lubricating coatings, prepared from the following raw materials by weight percentage:

[0116] The composition includes: 53% matrix material (epoxy resin); 10% fluorinated graphene; 20% metal sulfide (MoS2:WS2=1:1); 10% high thermal conductivity filler (boron nitride); 5% dispersant, of which the ratio of polyetherimide to hydroxypropyl methylcellulose is 1:1; and 2% interface modifier (KH-560).

[0117] In this embodiment, the graphene and boron nitride contents were maintained at a minimum of 10%, and the interfacial thermal resistance was optimized by setting the interface modifier to 2%. LFA test data confirmed that the thermal conductivity at this ratio was 10.0-11.0 W / (m·K).

[0118] Meanwhile, the 53% matrix content ensures the slurry has low viscosity (900-1200 mPa·s) and excellent leveling properties, facilitating coating of complex-shaped workpieces. The cross-cut adhesion test achieves a 5B rating. This formulation minimizes the use of expensive fillers, effectively reducing costs compared to the formulation in Example 6.

[0119] The preparation process of the high thermal conductivity graphene composite material with self-lubricating coating in this embodiment is as follows: First, fluorinated graphene is vacuum dried at 100℃ for 5 hours, and molybdenum disulfide and tungsten disulfide are dried at 120℃ for 3 hours. Then, all the dried raw materials, dispersant, and interface KH-560 are put into a three-dimensional mixer according to the above ratio and mixed at 45 rpm for 50 minutes to obtain premixed powder. Next, the premixed powder is fed into a high-pressure air jet mill for two-stage compounding: the first stage is processed at a grinding air pressure of 0.9 MPa, a feed rate of 12 kg / h, and a classifying wheel speed of 5000 rpm (SME≈4.0 kWh / kg) to achieve preliminary dispersion and crushing; the second stage is processed at a grinding air pressure of 1.0 MPa, a feed rate of 6 kg / h, and a classifying wheel speed of 6000 rpm (SME≈8.0 kWh / kg); finally, the composite powder is sieved through a screen to obtain the final high thermal conductivity graphene composite material.

[0120] The performance test results of the high thermal conductivity graphene composite material with self-lubricating coating prepared by the above ratio are shown in Table 4:

[0121] Performance indicators Test methods / standards Data results of this solution Basis and Objectives thermal conductivity LFA 10.0-11.0 W / (m·K) ≥10W / (m·K) Slurry viscosity Rotational viscometer (25℃) 900-1200 mPa·s Low viscosity, easy to apply Adhesion ASTM D3359 5B Excellent adhesion coefficient of friction ASTM G99 0.12-0.16 Meets general lubrication needs relative material cost (Taking Example 6 as Scheme 1) 0.85 Low cost

[0122] Table 4

[0123] Experimental evidence shows that the composite material obtained through the above formulation and process has low cost, good leveling and workability of the coating slurry, can be uniformly coated on complex shaped surfaces, has strong adhesion, and ensures that the thermal conductivity meets the standards. It is suitable for lightly loaded components that meet basic standards for heat dissipation and lubrication but are not extreme, internal structural components of some consumer electronics products, and protective coatings for complex-shaped workpieces that require good coverage.

[0124] It should be noted that, in actual implementation, the structure described in this specification is not a fixed or unchanging embodiment. The components of the embodiments of the present invention described and shown herein can be arranged and designed in various different configurations. These are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Furthermore, this specification is for illustrative purposes only and does not represent the specific structure or actual quantity in a concrete implementation.

[0125] Unless otherwise defined, the technical or scientific terms used herein should be understood in their ordinary sense as would be understood by one of ordinary skill in the art to which this invention pertains. The use of terms such as "a" or "an" in this specification and claims does not necessarily indicate a limitation of quantity. Terms such as "comprising" or "including" mean that the element or component preceding the word encompasses the element or component listed following the word and its equivalents, without excluding other elements or components. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0126] The exemplary embodiments of the present invention have been described in detail above with reference to preferred embodiments. However, those skilled in the art will understand that various modifications and alterations can be made to the above specific embodiments without departing from the concept of the present invention, and various combinations can be made to the various technical features and structures proposed in the present invention without exceeding the protection scope of the present invention.

Claims

1. A high thermal conductivity graphene composite material for self-lubricating coatings, characterized in that, It is prepared from the following components by mass percentage: matrix material 45%-55%; graphene 10%-15%; metal sulfide 20%-25%; high thermal conductivity filler 10%-13%; dispersant 3%-5%; interface modifier 1%-2%; The matrix material is epoxy resin or polyimide; The graphene is fluorinated graphene, with a fluorine atom content of 2.0wt%-3.0wt%, a carbon-fluorine bond content of more than 60% of the total fluorine content, 3-8 layers, and a specific surface area ≥500m² / g. The metal sulfide is a complex of molybdenum disulfide and tungsten disulfide, wherein the mass ratio of molybdenum disulfide to tungsten disulfide is 1:1-3; The high thermal conductivity filler is boron nitride or silicon carbide; The dispersant is a complex of polyetherimide and hydroxypropyl methylcellulose in a mass ratio of 1:1 to 2:

1. The interface modifier is a silane coupling agent or a titanate coupling agent.

2. The high thermal conductivity graphene composite material according to claim 1, characterized in that: The weight-average molecular weight of the polyetherimide in the dispersant ranges from 20,000 to 40,000 g / mol, and the molecular weight of the hydroxypropyl methylcellulose ranges from 40,000 to 60,000 g / mol. The viscosity of its 2% aqueous solution at 20°C is 3,000 to 6,000 mPa·s.

3. The high thermal conductivity graphene composite material according to claim 1, characterized in that, The composite material was prepared by high-pressure air jet milling process to form a core-shell interlayer composite structure with metal sulfide as the core and fluorinated graphene embedded and coated by mechanochemical action; The composite powder has a tap density of 0.8-1.5 g / cm³, a thermal conductivity ≥10 W / (m·K), and a friction coefficient ≤0.

15.

4. The high thermal conductivity graphene composite material according to claim 1, characterized in that, The particle size distribution of the composite powder is as follows: D10≥0.5μm, D50=1.0-2.5μm, D90≤5.0μm, Particle size distribution span Span = (D90 - D10) / D50 ≤ 2.0 Where D10, D50, and D90 are the particle sizes corresponding to the volumetric cumulative distribution.

5. A method for preparing a high thermal conductivity graphene composite material as described in any one of claims 1-4, characterized in that, Includes the following steps: Step 1; Raw material pretreatment involves vacuum drying of fluorinated graphene at 90-100℃ for 4-5 hours and metal sulfides at 110-120℃ for 2-3 hours. Step 2: Premixing. According to the formula, the dried raw materials, dispersant, and interface modifier are mixed in a three-dimensional mixer at a speed of 20-50 rpm for 0.5-1.5 hours to obtain a premixed powder with preliminary dispersion. Step 3: Multi-stage air jet milling: The premixed powder is fed into a high-pressure air jet mill and sequentially compounded using at least two stages of process parameters. The first-stage composite is carried out under low airflow pressure and high feed rate to achieve preliminary crushing and macroscopic homogenization of each component. The second-stage composite is carried out under high airflow pressure and low feed rate to achieve strong interfacial bonding between graphene and metal sulfides and construction of core-shell interlayer composite structure. Step 4: Post-processing. The composite powder is collected and sieved to remove uncomposite free powder, thus obtaining the high thermal conductivity graphene composite material.

6. The method for preparing the high thermal conductivity graphene composite material according to claim 5, characterized in that, In the multi-stage airflow milling process described in step three, during the first stage of the process, the grinding gas pressure is 0.6-0.9 MPa; the feed rate is 8-12 kg / h; the classifying wheel speed is 3000-5000 rpm; and the processing time accounts for 20%-30% of the total processing time. During the second-stage compounding process, the grinding gas pressure is 1.0-1.5 MPa; the feed rate is 3-6 kg / h; the classifying wheel speed is 6000-8000 rpm; and the processing time accounts for 70%-80% of the total compounding time.

7. The method for preparing the high thermal conductivity graphene composite material according to claim 6, characterized in that, In the multi-stage airflow milling process, the specific mechanical energy applied at each stage is... Satisfying the formula: ； In the formula, This refers to the installed power of the air jet mill. This is the processing time for this level. The quality of materials processed at this stage; The first-level composite The concentration is controlled within the range of 2.0-4.0 kWh / kg for initial compounding, and for the second-stage compounding. It is controlled within the range of 8.0-15.0 kWh / kg and is used to enhance interfacial bonding and core-shell structure construction.

8. The method for preparing the high thermal conductivity graphene composite material according to claim 5, characterized in that, During the airflow milling process, the nozzle pressure fluctuation range is controlled within ±0.2MPa; the gas temperature fluctuation range is controlled within ±5℃; the feed rate stability deviation is controlled within ±5%; and the classifier speed deviation is controlled within ±300rpm.

9. A self-lubricating coating, characterized in that, It is prepared from the following components in parts by weight: 20-35 parts of the high thermal conductivity graphene composite material as described in any one of claims 1-4; 25-45 parts of a high-temperature resistant adhesive, wherein the adhesive is a silicone-modified phenolic resin or a boron-modified polyimide; 30-50 parts of solvent, wherein the solvent is N-methylpyrrolidone or dimethylacetamide; 1-3 parts of additives, wherein the additives include leveling agent BYK-333 and defoamer BYK-055 compounded in a mass ratio of 2:1.

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