A composite polyether ether ketone and a preparation method and application thereof

Abstract

The application relates to the technical field of composite polyether ether ketone preparation, and particularly discloses a composite polyether ether ketone, a preparation method thereof and application, wherein the preparation method comprises the following steps: vacuum blending of polyether ether ketone, carbon fibers, graphite and silicon dioxide to obtain mixed powder; cold pressing of the mixed powder to obtain a pre-pressed product; vacuumizing of the pre-pressed product in a discharge plasma sintering furnace, and then discharge plasma sintering treatment of the pre-pressed product in an inert gas environment according to a multi-stage temperature-pressure curve to obtain the composite polyether ether ketone. The fast heating rate and the vacuum environment provided by the method can reduce the bubble content in the melt, increase the contact area between the particles of the doped graphite, carbon fibers and silicon dioxide in the material, quickly bridge and toughen the interface between the particles and the polymer, increase the bonding degree of the material, and further improve the mechanical properties and the wear resistance and resistance of the composite polyether ether ketone.

Description

Technical Field

[0001] This invention relates to the field of composite polyether ether ketone (PEEK) preparation technology, and particularly to a composite PEEK, its preparation method, and its application. Background Technology

[0002] Polyetheretherketone (PEEK) is a specialty engineering plastic with a high melting point (approximately 343°C) and high molding temperature. It possesses excellent temperature resistance, mechanical strength, chemical stability, and biocompatibility, making it irreplaceable in aerospace, medical devices, and high-end manufacturing. Common molding methods include extrusion molding, injection molding, cold pressing, and conventional hot pressing, but all have significant limitations.

[0003] Extrusion molding and injection molding: These processes require high temperatures (usually exceeding 380°C) to ensure melt flowability. However, high temperatures can easily lead to the decomposition of functional groups in the PEEK matrix and additives, damaging material properties. At the same time, excessively high PEEK melt viscosity and low melt index can easily cause bonding defects between the matrix and dopants, resulting in a decrease in the density and mechanical properties of the finished product.

[0004] Cold pressing: The molding temperature is relatively low (usually below 200℃), which can protect the functional groups to a certain extent, but the powder only softens locally and cannot completely eliminate internal pores and cracks, resulting in insufficient density and poor mechanical properties.

[0005] Conventional hot pressing: This method combines external heating (such as resistance wire) and pressure to form the material. However, it has low heat transfer efficiency. For PEEK materials with poor thermal conductivity, the actual temperature of the powder is much lower than the temperature of the mold, and there is a significant temperature gradient, which leads to uneven internal structure of the material. At the same time, the heating rate is slow (usually 5-10℃ / min), and prolonged heating can easily cause material aging, further reducing performance.

[0006] Spark plasma sintering (SPS) is a novel rapid sintering technology. Its core principle is to achieve rapid heating and densification of materials through Joule heating and plasma activation effects generated by pulsed current. Compared with traditional forming technologies, SPS has the following advantages: Rapid heating: The heating rate can reach 20-30℃ / min, significantly shortening the heating time and reducing the destruction of functional groups in the material; Internal heating: Heat is generated from within the material, resulting in uniform temperature distribution and avoiding the temperature gradient problem of traditional external heating; Plasma activation: The plasma generated by pulsed discharge can clean the powder surface, improve the interparticle bonding force, and promote densification; Vacuum / inert atmosphere environment: It can reduce material oxidation, reduce the bubble content in the melt, and improve density. Existing research has confirmed the advantages of SPS in the preparation of polymers and composites: Oluwagbenga Tobi Adesina et al. reviewed and pointed out that SPS-prepared polymer-based composites are superior to traditional methods in terms of thermal conductivity and crystallinity; Maxime Schwertz et al. optimized SPS parameters (temperature, pressure, and holding time) to achieve an elastic modulus of 3.43 GPa and a compression limit of 738 MPa for polyimide (PI), verifying the performance-enhancing effect of SPS on high-performance polymers.

[0007] However, a systematic approach to the SPS sintering process for composite polyetheretherketone (PEEK) has not yet been developed. Existing technologies lack research on the synergistic mechanism between PEEK and doped phases such as carbon fiber, graphite, and silica. Furthermore, the influence of SPS parameters (temperature gradient, pressure curve, holding time, etc.) on the microstructure and macroscopic properties of composite PEEK is not clearly defined, resulting in the inability to fully realize the performance potential of composite PEEK.

[0008] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0009] In view of the shortcomings of the prior art, the purpose of this invention is to provide a composite polyether ether ketone, its preparation method and application, which aims to solve the problems of functional group destruction, binding defects, insufficient density and poor performance stability in the existing preparation methods of composite polyether ether ketone.

[0010] The technical solution of the present invention is as follows:

[0011] A method for preparing a composite polyetheretherketone, comprising the steps of:

[0012] 70-80% polyetheretherketone, 5-15% carbon fiber, 5-10% graphite, and 2.5-7.5% silica by mass percentage are added to a planetary centrifugal high-speed mixer for vacuum mixing to obtain a mixed powder.

[0013] The mixed powder is placed in a mold and cold-pressed to obtain a pre-pressed product;

[0014] The pre-compressed product is placed in a spark plasma sintering furnace and evacuated. Then, spark plasma sintering is performed in an inert gas environment according to the following multi-stage temperature-pressure curve: first, the temperature is increased to 100-200℃ at a heating rate of 20-30℃ / min, with a sintering pressure of 0.5-30MPa; then, the temperature is increased to 200-300℃ at a heating rate of 20-30℃ / min, with a sintering pressure of 0.5-5MPa and a holding time of 20-40min; finally, the temperature is increased to 300-400℃ at a heating rate of 5-10℃ / min. The temperature is set at ℃, the sintering pressure is 0-0.5MPa, and the holding time is 30-60min; then the temperature is lowered to 300-350℃ at a cooling rate of 10-20℃ / min, the sintering pressure is 0.5-5MPa, and the holding time is 10-30min; then the temperature is lowered to 200-300℃ at a cooling rate of 20-30℃ / min, the sintering pressure is 0.5-10MPa, and the holding time is 10-60min; finally, the temperature is lowered to 100-170℃ at a cooling rate of 10-20℃ / min, the mold is removed, and the product is demolded while hot to obtain composite polyetheretherketone.

[0015] The method for preparing the composite polyether ether ketone (PEEK) includes the following: the relative molecular weight of the PEEK is 30,000-80,000; the carbon fiber is one of long filament, short fiber, and chopped fiber; the graphite is one of flake, block, and earthy; and the silica is one of crystalline and amorphous.

[0016] The method for preparing the composite polyetheretherketone (PEEK) includes the following: the PEEK has a mesh size of 200-1000, the carbon fiber has an aspect ratio of 2-8:1, the graphite has a particle size of 1-10 μm, and the silica has a particle size of 1-100 nm.

[0017] The method for preparing the composite polyetheretherketone includes a step in which 70-80% polyetheretherketone, 5-15% carbon fiber, 5-10% graphite, and 2.5-7.5% silica are added to a planetary centrifugal high-speed mixer for vacuum mixing. Uniform mixing is achieved under vacuum conditions through the difference between the rotational and revolution speeds. Specifically, the mixing process is as follows: first stage: revolution speed 200-600 rpm, rotation speed 100-300 rpm, time 1-2 min; second stage: revolution speed 1500-1800 rpm, rotation speed 800-1000 rpm, time 30-60 s; third stage: revolution speed 800-1200 rpm, rotation speed 400-800 rpm, time 10-30 s.

[0018] The method for preparing the composite polyether ether ketone includes a step in which the mixed powder is placed into a mold coated with a release agent for cold pressing, wherein the pressing pressure is 10-30 MPa and the time is 10-30 min.

[0019] In the preparation method of the composite polyetheretherketone, in the step of placing the pre-pressed product into a spark plasma sintering furnace and drawing a vacuum, the vacuum degree in the spark plasma sintering furnace is 2×10⁻⁶. -2 -5×10 -4 Pa.

[0020] In the method for preparing the composite polyether ether ketone, the inert gas is one of argon and nitrogen.

[0021] A composite polyether ether ketone, wherein the composite polyether ether ketone is prepared by the method described in this invention.

[0022] An application of a composite polyether ether ketone, wherein the composite polyether ether ketone of the present invention is used to prepare one of hydrated lubricated bearings, gearbox gears, wafer carriers and vacuum pump blades.

[0023] Beneficial effects: This invention provides a method for preparing composite polyetheretherketone (PEEK). The rapid heating rate and vacuum environment provided by spark plasma sintering (SPS) reduce the bubble content in the melt, allowing the groups in the PEEK material to react better with the doped materials. This increases the contact area between the doped graphite, carbon fiber, and silica particles, enabling rapid bridging and toughening at the polymer interface, increasing compatibility and bonding, and further improving the mechanical properties and friction-reducing properties of the composite PEEK. The composite PEEK samples prepared by this method have a uniform microstructure, good phase compatibility, and high strength. The SPS sintering of composite PEEK is simple and easy to implement. Compared with ordinary composite PEEK materials, the sintered composite PEEK exhibits significantly improved compressive strength and friction performance. Attached Figure Description

[0024] Figure 1 This is a flowchart of a method for preparing a composite polyether ether ketone according to the present invention.

[0025] Figure 2 The graph shows the results of ball-disk reciprocating friction and wear tests of the composite polyetheretherketone prepared in Examples 1-2 and Comparative Examples 1-2 at 15N, 5Hz, 3% NaCl solution, and silicon nitride ball friction pair.

[0026] Figure 3 The graph shows the results of compression performance testing of the composite polyether ether ketones prepared in Examples 1-2 and Comparative Examples 1-2. Detailed Implementation

[0027] This invention provides a composite polyether ether ketone, its preparation method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0028] Polyetheretherketone (PEEK), as a high-performance engineering plastic, faces the following key problems in traditional processing: Functional group destruction: Traditional molding methods involve slow heating rates (<10℃ / min) and long high-temperature durations, leading to oxidation or decomposition of the PEEK matrix and dopants (such as functional groups on the carbon fiber surface), reducing interfacial bonding strength. Bonding defects: PEEK melt has high viscosity and poor flowability, making it difficult to uniformly mix the matrix with dopants such as carbon fibers and graphite in traditional processes, easily generating interfacial voids and resulting in decreased mechanical properties. Insufficient density: Cold pressing cannot eliminate porosity, and ordinary hot pressing causes uneven densification within the material due to temperature gradients, with the finished product porosity typically exceeding 5%, affecting strength and wear resistance. Poor performance stability: Fluctuations in traditional process parameters (such as temperature deviations and pressure inconsistencies) easily lead to product performance dispersion, failing to meet the material consistency requirements of high-end equipment.

[0029] The core reason for the aforementioned problems is that traditional molding technologies cannot simultaneously meet the three major requirements of rapid heating to protect functional groups, uniform heating to promote densification, and interface activation to enhance compatibility. Therefore, developing an SPS sintering process suitable for composite polyetheretherketones (PEEK) to solve these problems through precise control of sintering parameters has become an urgent need in this field.

[0030] Based on this, the present invention provides a method for preparing composite polyetheretherketone, such as... Figure 1 As shown, it includes the following steps:

[0031] S10. By mass percentage, 70-80% of polyetheretherketone, 5-15% of carbon fiber, 5-10% of graphite, and 2.5-7.5% of silica are added to a planetary centrifugal high-speed mixer for vacuum mixing to obtain a mixed powder.

[0032] S20. The mixed powder is placed into a mold and cold-pressed to obtain a pre-pressed product;

[0033] S30. Place the pre-compressed product into a discharge plasma sintering furnace and evacuate it. Then, in an inert gas environment, perform discharge plasma sintering treatment according to the following multi-stage temperature-pressure curve: First, heat the product at a rate of 20-30℃ / min to a sintering temperature of 100-200℃, with a sintering pressure of 0.5-30MPa; then, heat the product at a rate of 20-30℃ / min to a sintering temperature of 200-300℃, with a sintering pressure of 0.5-5MPa and a holding time of 20-40min; finally, heat the product at a rate of 5-10℃ / min to 300-400℃. The temperature is 00℃, the sintering pressure is 0-0.5MPa, and the holding time is 30-60min; then the temperature is lowered to 300-350℃ at a cooling rate of 10-20℃ / min, the sintering pressure is 0.5-5MPa, and the holding time is 10-30min; then the temperature is lowered to 200-300℃ at a cooling rate of 20-30℃ / min, the sintering pressure is 0.5-10MPa, and the holding time is 10-60min; finally, the temperature is lowered to 100-170℃ at a cooling rate of 10-20℃ / min, the mold is removed, and the product is demolded while hot to obtain composite polyetheretherketone.

[0034] This invention employs spark plasma sintering (SPS) technology, leveraging its advantages of rapid heating, internal heating, plasma activation, and a vacuum environment to enhance the performance of composite PEEK through the following approaches: 1) Co-design of raw materials: Selecting specific ratios of PEEK, carbon fiber, graphite, and silica, utilizing the synergistic effects of each component (e.g., carbon fiber reinforcement, graphite lubrication, and silica wear resistance) to improve overall performance; 2) Precise mixing process: Employing a planetary centrifugal high-speed mixer, using three-stage speed control to achieve uniform mixing of raw materials and prevent agglomeration; 3) Gradient sintering control: Designing multi-stage temperature-pressure curves to achieve a continuous process of low-temperature pre-compression, medium-temperature densification, high-temperature interfacial reaction, and gradient cooling for shaping, balancing densification and functional group protection; 4) Inert atmosphere protection: Sintering in an argon or nitrogen environment to reduce material oxidation and lower bubble content.

[0035] Specifically, this invention achieves synergistic functions of load-bearing, reinforcement, lubrication, and wear resistance by precisely designing the mass percentages of polyetheretherketone (PEEK), carbon fiber, graphite, and silica. PEEK, as the matrix material, constitutes the largest proportion (70-80%). Its benzene rings and ether bonds in its molecular chain endow the material with excellent high-temperature resistance (melting point 343℃) and mechanical strength (pure PEEK compressive strength approximately 900 MPa). Carbon fiber accounts for 5-15%, and its axial tensile strength (>3000 MPa) is more than 10 times that of PEEK. It can bridge microcracks in the matrix through a bridging effect. When the material is under load, stress is transferred to the carbon fiber through the interface, significantly improving the fracture resistance of the composite PEEK. Simultaneously, the high rigidity of carbon fiber (elastic modulus >200 GPa) restricts the plastic flow of the PEEK matrix during friction, preventing increased wear due to localized deformation. Graphite accounts for 5-10%, and its layered structure... The weak interlayer van der Waals forces are the core of achieving low friction performance. During friction, the graphite sheets slide along the base surface under shear force, and the coefficient of friction can be reduced to below 0.2. The 1-10μm particle size ensures that the graphite can uniformly cover the friction interface, forming a continuous lubricating film and reducing the direct wear of the PEEK matrix. The wear rate of the composite polyether ether ketone in this embodiment is reduced by an order of magnitude. It is based on this mechanism that if the graphite content is low (<5%), the transfer film will be discontinuous; if the graphite content is too high (>10%), it will weaken the matrix strength. The silica (Mohs hardness 7) is uniformly dispersed in the PEEK matrix and can resist the cutting action of abrasive particles. The 1-100nm particle size of silica allows it to fill the micro gaps between PEEK and carbon fibers, enhancing the interfacial bonding force through the pinning effect and avoiding the aggravation of wear caused by interfacial peeling during friction. If the content is too high (>7.5%), the silica is prone to agglomeration, forming stress concentration points, which will reduce the strength.

[0036] In existing technologies, composite PEEK often focuses on a single property, such as adding only carbon fiber reinforcement or only graphite lubrication. This invention, however, proposes a quaternary synergistic design for the first time, achieving a balance between strength, lubrication, and wear resistance by limiting the proportions of each component. Traditional formulations often contain more than 15% graphite to pursue low friction, but this leads to a strength decrease of over 20%. This invention, however, uses 5-10% graphite and 2.5-7.5% silica synergistically to maintain low friction without sacrificing strength.

[0037] This invention employs a planetary centrifugal high-speed mixer, which solves the problem of carbon fiber agglomeration through three-stage speed, time control, and a vacuum environment. Specifically, the equipment uses centrifugal force generated by revolution to cause materials to aggregate towards the container wall, forming a high-density mixing zone; the shear force generated by rotation acts radially on the materials, breaking up the entanglement and agglomeration of carbon fibers (carbon fibers, due to their large aspect ratio, easily form fiber balls). This invention limits the speed range of revolution and rotation to ensure a balance between shear force and centrifugal force: if the revolution is too fast (>1800 rpm), the material is prone to splashing; if the rotation is too slow (<100 rpm), the agglomerates cannot be dispersed. This parameter range is the result of optimizing functionality and equipment stability. The mixing process of this invention is divided into three stages (1-2 min → 30-60 s → 10-30 s), with the following functions for each stage: Stage 1 (1-2 min): Low-speed premixing (200-600 rpm / 100-300 rpm), ensuring PEEK powder uniformly coats carbon fibers and graphite, preventing fiber breakage due to subsequent high shear; Stage 2 (30-60 s): High-speed strong shearing (1500-1800 rpm / 800-1000 rpm), tearing carbon fiber agglomerates through shear force, reducing the number of agglomerates by 60%; Stage 3 (10-30 s): Medium-speed homogenization (800-1200 rpm / 400-800 rpm), eliminating local concentration differences and ensuring silica nanoparticles uniformly fill the gaps. This gradient design of pre-dispersion-strong shearing-homogenization solves the contradiction of incomplete dispersion or fiber breakage in traditional single-speed mixing. The mixing process is carried out in a vacuum environment, which eliminates air and moisture, avoiding interfacial bonding defects caused by gas adsorption on the powder surface. It also inhibits the oxidation of carbon fibers during shearing, ensuring compatibility with PEEK. Existing technologies often employ single-speed mixing, failing to simultaneously address both dispersion and agglomeration while protecting the carbon fibers. The three-stage design of this invention achieves a balance between these two aspects through gradient shearing.

[0038] The multi-stage temperature, pressure, and rate control of the SPS sintering process in this invention is a precise control strategy designed to address the material characteristics of composite polyetheretherketone (high melting point, high melt viscosity, easy oxidation) and the defects of traditional molding processes (low density, poor interfacial bonding, and functional group destruction). It solves the contradiction that densification in traditional hot pressing requires high temperature and long time, which leads to the destruction of functional groups. Specifically, in the first heating stage (100-200℃, 20-30℃ / min, 0.5-30MPa), the composite PEEK powder is still in a solid state (PEEK's glass transition temperature is approximately 143℃). A rapid heating rate of 20-30℃ / min (3-5 times that of traditional hot pressing) shortens the low-temperature residence time, reducing the recondensation of adsorbed water vapor on the powder surface. Simultaneously, a high pressure of 0.5-30MPa is applied, using mechanical force to tightly pack PEEK, carbon fiber, graphite, and other particles, rapidly expelling air from the interparticle gaps (approximately 70% of the initial gas is expelled during this stage). The relative density increases from 60-70% after cold pressing to 75-80%. This stage avoids the gas retention problem caused by the slow heating rate (5-10℃ / min) of traditional hot pressing, laying a low-porosity foundation for subsequent densification. High-pressure compaction also reduces the risk of melt overflow in the subsequent high-temperature stage.

[0039] In the second heating stage (200-300℃, 20-30℃ / min, 0.5-5MPa, holding for 20-40min), the temperature range of 200-300℃ causes the surface of PEEK particles to begin to soften (before reaching the molten state). Carbon fibers and graphite particles initially contact the PEEK surface due to thermal expansion. At this point, reducing the pressure to 0.5-5MPa (medium pressure) promotes the transformation from point contact to surface contact between particles through the viscous flow of the softened layer, while avoiding powder splashing caused by high pressure. The 20-40min holding period improves the uniformity of softening, ensuring consistent initial bonding across different regions. This stage overcomes the shortcomings of traditional cold pressing, which relies solely on mechanical force for bonding and lacks interfacial adhesion. Surface softening achieves initial bonding between particles, providing a continuous structural foundation for subsequent high-temperature densification. Rapid heating also reduces early oxidation of PEEK ether bonds.

[0040] In the third heating stage (300-400℃, 5-10℃ / min, 0-0.5MPa, holding for 30-60min), the temperature of 300-400℃ approaches the melting point of PEEK (343℃), and the powder enters a semi-molten to molten state. At this point, reducing the heating rate to 5-10℃ / min and maintaining a low pressure (0-0.5MPa) avoids localized overheating and decomposition of the melt due to rapid heating, and also provides reaction time for the core advantage of SPS: plasma activation. The plasma generated by the pulsed current (Ar... +The process involves cleaning the oxide layer (such as oxidation products of hydroxyl groups on the carbon fiber surface) of PEEK and carbon fiber surfaces (e.g., by removing hydroxyl groups from the carbon fiber surface), increasing surface energy by 50% and promoting hydrogen bonding between PEEK ether bonds and carbon fiber hydroxyl groups. A 30-60 minute holding period ensures sufficient interfacial reaction, forming a stable chemical bond. This stage overcomes the problem of insufficient interfacial reaction caused by traditional hot pressing relying solely on external heating. Through the synergy of plasma activation and gentle heating, a dual effect of mechanical and chemical bonding between particles is achieved, significantly improving interfacial adhesion. The low-pressure environment prevents melt overflow and reduces bubble encapsulation.

[0041] The cooling stage of this invention is also divided into three stages of cooling combined with pressure maintenance. The purpose is to achieve dense solidification and eliminate internal stress. In the first cooling stage (300-350℃, 10-20℃ / min, 0.5-5MPa, holding for 10-30min), 300-350℃ is the critical range (crystallization temperature zone) for PEEK to transform from a molten state to a solid state. At this time, slow cooling at a rate of 10-20℃ / min, combined with a pressure of 0.5-5MPa, can suppress microcracks caused by molecular chain rearrangement during PEEK crystallization. Holding for 10-30min makes the crystallization more uniform and avoids performance fluctuations caused by local crystallinity differences. This stage can solve the problems of insufficient crystallization and internal stress concentration caused by traditional rapid cooling. Pressure-assisted crystallization improves structural stability and lays the foundation for subsequent mechanical properties.

[0042] In the second cooling stage (200-300℃, 20-30℃ / min, 0.5-10MPa, holding for 10-60min), PEEK has completed crystallization at 200-300℃. Cooling at a rate of 20-30℃ / min while applying a pressure of 0.5-10MPa compensates for thermal shrinkage through mechanical force, reducing internal stress from >20MPa in traditional processes to <5MPa. The 10-60min holding period allows for slow stress release, preventing cracking caused by stress concentration. This stage solves the problems of high internal stress and low dimensional accuracy caused by pressureless cooling in traditional hot pressing, controlling the dimensional deviation of the finished product to ±0.02mm, meeting the requirements of precision components (such as wafer carriers).

[0043] In the final cooling stage (100-170℃, 10-20℃ / min, demolding while hot), the temperature range of 100-170℃ is higher than the glass transition temperature of PEEK (143℃), and the material still retains a certain degree of plasticity. Demolding at this stage avoids demolding cracks caused by increased brittleness at low temperatures (<100℃). The cooling rate of 10-20℃ / min ensures uniform temperature and avoids deformation caused by localized temperature differences. This stage solves the problems of cracks and dimensional deformation that are easily generated by traditional cold demolding, ensuring the integrity and dimensional accuracy of the finished product.

[0044] The aforementioned multi-stage control, through a closed-loop design of heating and compaction-plasma activation-cooling and shaping, achieves multiple advantages that traditional processes cannot simultaneously provide, specifically manifested as follows:

[0045] Increased density: Porosity is reduced from 4-6% in traditional hot pressing to <1%, resulting in a 31.5% increase in compressive strength (from 800MPa to 1052MPa); Enhanced interfacial bonding: Interfacial bonding is increased by 30% through plasma activation and gentle heating, eliminating interfacial delamination during friction and reducing wear rate by an order of magnitude; Functional group protection: Rapid heating (total high-temperature time <2h) ensures that the retention rate of PEEK ether bonds and carbon fiber hydroxyl groups is >95%, avoiding functional group decomposition caused by traditional slow heating (>3h); Internal stress elimination: Stepped cooling and pressure compensation reduce internal stress to <5MPa, reducing batch performance fluctuation from 12-15% to 3-4%. The multi-stage SPS control of this invention is not a simple parameter superposition, but rather a systematic solution to the core defects of traditional molding processes by addressing the material characteristics of composite PEEK through a synergistic mechanism of rapid heating to preserve functional groups, plasma to strengthen the interface, gradient pressure to promote density, and stepped cooling to eliminate stress, ultimately achieving a comprehensive leap in material performance.

[0046] In some embodiments, the relative molecular weight of the polyetheretherketone is 30,000-80,000. For example, the polyetheretherketone can be one of Zhongyan Co., Ltd., Junhua Special Plastics, and Jida Special Plastics. For example, Zhongyan Co., Ltd. has three main grades of 770, 550 and 330 according to melt flowability from low to high; Junhua Special Plastics has the AKSOPEEK series; and Jida Special Plastics has the PEEKGF30 product.

[0047] In some embodiments, the carbon fiber is one of filaments, short fibers, and chopped fibers, but is not limited thereto; the graphite is one of flakes, blocks, and earthy forms, but is not limited thereto; and the silicon dioxide is one of crystalline and amorphous forms, but is not limited thereto.

[0048] In some embodiments, the polyetheretherketone has a mesh size of 200-1000. This range avoids the problem of agglomeration of excessively fine powder (>1000 mesh) in the mixture, and solves the densification difficulties caused by excessively coarse powder (<200 mesh), laying the foundation for the uniformity of subsequent sintering.

[0049] In some embodiments, the aspect ratio of the carbon fibers is 2-8:1. If the aspect ratio is >8:1, the carbon fibers are prone to entanglement and agglomeration; if the aspect ratio is <2:1, an effective reinforcing network cannot be formed. Therefore, limiting the aspect ratio of the carbon fibers to the range of 2:1-8:1 is key to balancing functionality and processability. Existing technologies do not clearly define the relationship between PEEK mesh size and carbon fiber aspect ratio. This invention discovers that 200-1000 mesh PEEK combined with carbon fibers of an aspect ratio of 2-8:1 can form an optimal particle-fiber filling structure, resolving the contradiction between coarse PEEK particles and long fiber agglomeration.

[0050] In some embodiments, the step of placing the mixed powder into a mold coated with a release agent for cold pressing is performed at a pressing pressure of 10-30 MPa for a time of 10-30 min, but is not limited thereto.

[0051] In some embodiments, in the step of placing the pre-pressed product into the spark plasma sintering furnace and evacuating it, the vacuum level in the spark plasma sintering furnace is 2 × 10⁻⁶. -2 -5×10 -4 Pa. In this embodiment, the furnace is evacuated to 2×10 Pa. -2 -5×10 -4 The ultimate vacuum of Pa serves several purposes: it removes air from between powder particles and adsorbs moisture, preventing gas expansion and bubble formation during sintering heating; it reduces gas partial pressure, allowing the trace amounts of volatiles released during PEEK melting to escape smoothly; and after vacuuming, it introduces inert gas to replace residual air, inhibiting the oxidation of PEEK and carbon fibers at high temperatures (300-400℃). Argon, as an inert gas, enhances the plasma intensity generated by SPS pulse discharge (Ar...). + The lower ionization energy promotes powder surface activation. Experiments show that the plasma density in an argon atmosphere is 1.2 times that of a nitrogen atmosphere, resulting in more complete interfacial reactions.

[0052] In some embodiments, the inert gas is one of argon and nitrogen, but is not limited thereto.

[0053] In some embodiments, a composite polyether ether ketone is also provided, wherein it is prepared by the method for preparing the composite polyether ether ketone described in this invention.

[0054] In some embodiments, an application of the composite polyether ether ketone is also provided, wherein the composite polyether ether ketone of the present invention is used to prepare one of hydrated lubricated bearings, gearbox gears, wafer carriers and vacuum pump blades.

[0055] The present invention will be further explained and illustrated below through specific embodiments:

[0056] Example 1

[0057] A method for preparing a composite polyether ether ketone, comprising the following steps:

[0058] By weight percentage, 80% polyetheretherketone (PEEK), 10% carbon fiber, 7% graphite, and 3% silica were added to a planetary centrifugal high-speed mixer for vacuum mixing to obtain a mixed powder. The mixing process was as follows: first stage: revolution speed 300 rpm, rotation speed 100 rpm, time 2 min; second stage: revolution speed 1600 rpm, rotation speed 800 rpm, time 40 s; third stage: revolution speed 1000 rpm, rotation speed 500 rpm, time 20 s. The PEEK had a mesh size of 1000 mesh, the carbon fiber had an aspect ratio of 5:1, the graphite had a particle size of 2 μm, and the silica had a particle size of 10 nm.

[0059] The mixed powder is placed in a mold and cold-pressed to obtain a pre-pressed product. The molding pressure is 20 MPa and the time is 20 min.

[0060] The pre-pressed product was placed in a spark plasma sintering furnace and evacuated to a vacuum of 5 × 10⁻⁶. -4 Pa, and then discharge plasma sintering was performed in an argon atmosphere according to the following multi-stage temperature-pressure curve: First, the temperature was increased to 200℃ at a heating rate of 30℃ / min and the sintering pressure was 20MPa; then the temperature was increased to 300℃ at a heating rate of 30℃ / min and the sintering pressure was 4MPa, with a holding time of 30min; then the temperature was increased to 400℃ at a heating rate of 10℃ / min and the sintering pressure was 0.5MPa, with a holding time of 60min; then the temperature was decreased to 300℃ at a cooling rate of 20℃ / min and the sintering pressure was 0.5MPa, with a holding time of 30min; then the temperature was decreased to 250℃ at a cooling rate of 30℃ / min and the sintering pressure was 5MPa, with a holding time of 30min; finally, the temperature was decreased to 150℃ at a cooling rate of 20℃ / min, the mold was removed, and the product was demolded while hot to obtain composite polyetheretherketone.

[0061] Example 2

[0062] A method for preparing a composite polyether ether ketone, comprising the following steps:

[0063] 70% polyetheretherketone, 15% carbon fiber, 10% graphite, and 5% silica were added to a planetary centrifugal high-speed mixer by mass percentage and vacuum-blended to obtain a mixed powder; wherein, the vacuum blending step was the same as in Example 1; the polyetheretherketone had a mesh size of 300 mesh, the carbon fiber had an aspect ratio of 2:1, the graphite had a particle size of 5 μm, and the silica had a particle size of 50 nm.

[0064] The mixed powder is placed in a mold and cold-pressed to obtain a pre-pressed product. The molding pressure is 10 MPa and the time is 30 min.

[0065] The pre-pressed product was placed in a spark plasma sintering furnace and evacuated to a vacuum of 2×10⁻⁶. -2 Pa, and then discharge plasma sintering was performed in an argon gas environment according to the following multi-stage temperature-pressure curve: First, the temperature was increased to 180℃ at a heating rate of 20℃ / min and the sintering pressure was 20MPa; then the temperature was increased to 300℃ at a heating rate of 30℃ / min and the sintering pressure was 4MPa, with a holding time of 30min; then the temperature was increased to 380℃ at a heating rate of 5℃ / min and the sintering pressure was 2.5MPa, with a holding time of 60min; then the temperature was decreased to 300℃ at a cooling rate of 20℃ / min and the sintering pressure was 2.5MPa, with a holding time of 10min; then the temperature was decreased to 200℃ at a cooling rate of 30℃ / min and the sintering pressure was 7.5MPa, with a holding time of 60min; finally, the temperature was decreased to 170℃ at a cooling rate of 10℃ / min, the mold was removed, and the product was demolded while hot to obtain composite polyetheretherketone.

[0066] Comparative Example 1 (Sintering in a Vacuum Hot Press Furnace)

[0067] This comparative example provides a method for preparing composite polyetheretherketone by vacuum hot press sintering. The composition of the composite polyetheretherketone is the same as in Example 1, and the preparation steps of the mixed powder and pre-pressed product are also the same as in Example 1. The difference is that a vacuum hot press sintering is used, and during the sintering process, under a constant pressure of 5 MPa, the temperature is first raised to 250°C at a rate of 10°C / min and held for 45 min; then, it is held at 250°C for another 10 min; next, the temperature is raised to 360°C at a rate of 5°C / min and held for 180 min; then, it is cooled to 280°C and held for 60 min. The vacuum environment during the sintering process is 6 × 10⁻⁶. -3 Pa, and finally demolding to obtain composite polyether ether ketone.

[0068] Comparative Example 2 (Muffle furnace sintering + die casting)

[0069] This comparative example provides a method for preparing composite polyetheretherketone by muffle furnace sintering. The composition of the composite polyetheretherketone is the same as that in Example 1, and the preparation steps of the mixed powder and pre-pressed product are also the same as in Example 1. The difference is that a muffle furnace sintering is used. During the sintering process, the temperature is first raised to 430°C at a rate of 10°C / min; then held at 430°C for 2 hours; then cooled to 360°C at a rate of 2°C / min; then the mold is removed from the muffle furnace at 360°C and placed in a tablet press for die casting at 33 MPa. After holding the pressure for 30 minutes, it is placed in air for natural cooling. There are no rare gases or vacuum environment during the sintering process, and composite polyetheretherketone is obtained.

[0070] The results of the ball-disc reciprocating friction and wear tests of the composite polyetheretherketone prepared in Examples 1-2 and Comparative Examples 1-2 at 15N, 5Hz, 3% NaCl solution, and silicon nitride ball friction pairs are shown in Table 1 and 2. Figure 2 As shown.

[0071] Table 1 Friction and Wear Performance Data

[0072]

[0073] From Table 1 and Figure 2 The data shows that, compared to Comparative Example 1, the composite polyetheretherketone (PEEK) sintered by SPS in Examples 1-2 exhibits a lower coefficient of friction and wear rate under the same friction test conditions. Clearly, the tribological properties of Examples 1-2 are significantly superior to those of Comparative Example 1. This is because in Examples 1-2, the plasma activation effect of SPS causes a pinning effect at the interface between PEEK and silica (1-100 nm), with silica uniformly embedded in the matrix to resist the cutting action of abrasive particles. The wear surface of these examples shows shallow and uniform wear tracks without obvious furrows. In contrast, Comparative Example 1, lacking plasma activation, has micro-gaps (porosity 4.2%) at the silica-PEEK interface. During friction, silica easily detaches from the matrix, becoming abrasive particles and exacerbating wear. Furthermore, Examples 1-2 achieved a density of 99.2% (porosity of 0.8%) through SPS gradient pressure (30MPa→0.5MPa), which suppressed the stress concentration effect of pores and prevented local plastic deformation from intensifying during friction. In contrast, Comparative Example 1, due to the single pressure (5MPa) of vacuum hot pressing, had a porosity of 4.2%, and plastic flow was easily generated around the pores, resulting in an increased wear rate.

[0074] From Table 1 and Figure 2The data shows that Comparative Example 2 has poor tribological properties. This is because Comparative Example 2 was sintered in an air environment in a muffle furnace (430℃ for 2 hours), during which the graphite underwent an oxidation reaction, resulting in a sharp decrease in the content of the lubricating phase. Simultaneously, the hydroxyl groups (-OH) on the carbon fiber surface were oxidized to carboxyl groups (-COOH), causing a sharp drop in compatibility with PEEK. Consequently, the carbon fibers were prone to breakage and shedding during friction, forming abrasive particles. Figure 2 The friction curve of Comparative Example 2 fluctuated drastically, indicating lubricant film failure. In contrast, Examples 1-2 employed vacuum-argon protection to prevent oxidation of graphite and carbon fiber. Graphite exhibits good stability in an inert environment, maintaining its lubricating function over a long period. Comparative Example 2 lacked vacuum treatment; air in the powder gaps expanded at high temperatures, forming bubbles (porosity 5.8%). Furthermore, the die-casting pressure (33 MPa) only applied in the later stages, failing to eliminate these bubbles. During friction, stress concentration occurred around the bubbles, leading to localized peeling of the PEEK matrix and a wear rate increasing to 7.65*10. -6 cm 3 / (N・m); In Examples 1-2, the bubble content was <0.1% due to SPS ultimate vacuum degassing, and the friction interface was uniformly stressed. In Comparative Example 2, the external heating of the muffle furnace resulted in a temperature gradient (temperature difference >30℃), which led to local graphite agglomeration, local PEEK oxidation and embrittlement, and large fluctuations in the coefficient of friction; while in Examples 1-2, the internal heating of the SPS resulted in a uniform temperature distribution (temperature difference <5℃) and a consistent distribution of the lubricating-wear-resistant phases.

[0075] The compressibility of the composite polyetheretherketones prepared in Examples 1-2 and Comparative Examples 1-2 was tested, and the results are shown in Table 2. Figure 3 As shown.

[0076] Table 2 Compression Performance Test Data

[0077]

[0078] From Table 2 and Figure 3 The data shows that the compressive strength of Examples 1-2 is significantly higher than that of Comparative Example 1, primarily due to the optimization of density, interfacial bonding, and functional group retention by the SPS process. Examples 1-2 utilize multi-stage pressure control via SPS: rapid powder compaction under low temperature and high pressure (20-30 MPa), followed by high temperature and low pressure (0-0.5 MPa) to promote diffusion welding. Figure 3The compression curve of the intermediate embodiment showed no obvious yield plateau, proving that the structure was dense. In contrast, the vacuum hot pressing of Comparative Example 1 used a single pressure (5 MPa), which could not balance compaction and diffusion, resulting in a porosity of 4.2%. The pores became stress concentration sources during compression, leading to premature fracture. In Examples 1-2, the plasma activation of SPS (300-400℃ holding stage) increased the surface energy of the carbon fiber by 50%. The PEEK ether bonds (-O-) and carbon fiber hydroxyl groups (-OH) formed hydrogen bonds, enhancing the interfacial shear strength. During compression, the stress was effectively transferred to the high-strength carbon fiber (tensile strength > 3000 MPa) through the interface, playing a bridging and reinforcing role. In contrast, Comparative Example 1 did not have plasma activation, and there was a gap between the carbon fiber and PEEK interface. During compression, the interface peeled off first, and the carbon fiber could not fully bear the stress, weakening the reinforcing effect. In Examples 1-2, the rapid heating rate of 20-30℃ / min shortened the high-temperature time, the PEEK ether bond decomposition rate was <5%, and the molecular chain integrity was good; while in Comparative Example 1, the heating rate was 10℃ / min, and the high temperature was maintained for more than 3 hours, the ether bond decomposition rate was >30%, the molecular weight of the PEEK matrix decreased, and the strength of the matrix itself was reduced.

[0079] From Table 2 and Figure 3 The data shows that Comparative Example 2 exhibits the lowest compressive strength, primarily due to high defects caused by oxidation degradation and process incompatibility. Comparative Example 2 was sintered in air (430℃), resulting in oxidative degradation of PEEK and molecular chain breakage, leading to a decrease in matrix strength. Simultaneously, a thick oxide layer (12.5% ​​O content) formed on the carbon fiber surface, reducing the interfacial bonding with PEEK and making it prone to interfacial debonding during compression. In contrast, the vacuum-argon environment of Examples 1-2 suppressed oxidation, stabilizing the ether bonds and benzene rings in the PEEK molecular chain, and preventing an oxide layer on the carbon fiber surface. Comparative Example 2 lacked vacuum treatment, leading to air entrapment and bubble formation (porosity 5.8%). Furthermore, the muffle furnace was separated from the die-casting process (360℃ die-casting), causing thermal stress and microcracks. During compression, stress concentration (stress amplification factor > 5) occurred at the bubble and crack tips, resulting in premature material fracture. In contrast, Examples 1-2 utilized SPS ultimate vacuum to expel gas, combined with gradient pressure to eliminate bubbles, resulting in a more uniform stress distribution during compression. Figure 3 The compression curve of the Chinese embodiment has a large slope and high rigidity.

[0080] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a composite polyetheretherketone, characterized in that, Including the following steps: 70-80% polyetheretherketone, 5-15% carbon fiber, 5-10% graphite, and 2.5-7.5% silica by mass percentage are added to a planetary centrifugal high-speed mixer for vacuum mixing to obtain a mixed powder. The mixed powder is placed in a mold and cold-pressed to obtain a pre-pressed product; The pre-compressed product is placed in a spark plasma sintering furnace and evacuated. Then, spark plasma sintering is performed in an inert gas environment according to the following multi-stage temperature-pressure curve: first, the temperature is increased to 100-200℃ at a heating rate of 20-30℃ / min, with a sintering pressure of 0.5-30MPa; then, the temperature is increased to 200-300℃ at a heating rate of 20-30℃ / min, with a sintering pressure of 0.5-5MPa and a holding time of 20-40min; finally, the temperature is increased to 300-400℃ at a heating rate of 5-10℃ / min. The temperature is set at ℃, the sintering pressure is 0-0.5MPa, and the holding time is 30-60min; then the temperature is lowered to 300-350℃ at a cooling rate of 10-20℃ / min, the sintering pressure is 0.5-5MPa, and the holding time is 10-30min; then the temperature is lowered to 200-300℃ at a cooling rate of 20-30℃ / min, the sintering pressure is 0.5-10MPa, and the holding time is 10-60min; finally, the temperature is lowered to 100-170℃ at a cooling rate of 10-20℃ / min, the mold is removed, and the product is demolded while hot to obtain composite polyetheretherketone.

2. The method for preparing the composite polyetheretherketone according to claim 1, characterized in that, The polyether ether ketone has a relative molecular weight of 30,000-80,000, the carbon fiber is one of long filament, short fiber and chopped fiber; the graphite is one of flake, block and earthy; and the silicon dioxide is one of crystalline and amorphous.

3. The method for preparing the composite polyetheretherketone according to claim 1, characterized in that, The polyetheretherketone has a mesh size of 200-1000, the carbon fiber has an aspect ratio of 2-8:1, the graphite has a particle size of 1-10μm, and the silica has a particle size of 1-100nm.

4. The method for preparing the composite polyetheretherketone according to claim 1, characterized in that, In the vacuum mixing step, 70-80% polyetheretherketone (PEEK), 5-15% carbon fiber, 5-10% graphite, and 2.5-7.5% silica are added to a planetary centrifugal high-speed mixer by weight percentage. Uniform mixing is achieved under vacuum conditions by the difference between the rotation speed and the revolution speed. Specifically, the first stage has a revolution speed of 200-600 rpm and a rotation speed of 100-300 rpm for 1-2 minutes; the second stage has a revolution speed of 1500-1800 rpm and a rotation speed of 800-1000 rpm for 30-60 seconds; and the third stage has a revolution speed of 800-1200 rpm and a rotation speed of 400-800 rpm for 10-30 seconds.

5. The method for preparing the composite polyetheretherketone according to claim 1, characterized in that, In the step of cold pressing the mixed powder into a mold coated with a release agent, the molding pressure is 10-30 MPa and the time is 10-30 min.

6. The method for preparing the composite polyetheretherketone according to claim 1, characterized in that, In the step of placing the pre-pressed product into the spark plasma sintering furnace and evacuating it, the vacuum level in the spark plasma sintering furnace is 2 × 10⁻⁶. -2 -5×10 -4 Pa.

7. The method for preparing the composite polyetheretherketone according to claim 1, characterized in that, The inert gas is either argon or nitrogen.

8. A composite polyetheretherketone, characterized in that, It is prepared by the method described in any one of claims 1-7 for the preparation of composite polyether ether ketone.

9. An application of a composite polyetheretherketone, characterized in that, The composite polyether ether ketone of claim 8 is used to prepare one of the following: hydrated lubricated bearings, gearbox gears, wafer carriers, and vacuum pump blades.

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