Composite polyether-ether-ketone as well as preparation method and application thereof

Abstract

The invention relates to the technical field of composite polyether-ether-ketone preparation, and particularly discloses composite polyether-ether-ketone and a preparation method and application thereof.The preparation method comprises the steps that polyether-ether-ketone, carbon fibers, graphite and silicon dioxide are subjected to vacuum blending, and mixed powder is obtained; carrying out cold press molding on the mixed powder to obtain a pre-pressed product; and putting the pre-pressed product into a spark plasma sintering hearth, vacuumizing, and carrying out spark plasma sintering treatment in an inert gas environment according to a multi-stage temperature-pressure curve to prepare the composite polyether-ether-ketone. According to the method, the content of bubbles in a melt can be reduced by a relatively high heating rate and a vacuum environment, so that the contact area among particles of graphite, carbon fibers and silicon dioxide doped in the material is increased, the particles and a polymer interface are quickly bridged and toughened, the combination degree of the material is increased, and the service life of the material is prolonged. The mechanical property and the anti-friction and anti-resistance properties of the composite polyether-ether-ketone are further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite polyetheretherketone preparation, and in particular to a composite polyetheretherketone and a preparation method and application thereof. Background Art

[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, and has irreplaceable application value in aerospace, medical devices, high-end manufacturing, and other fields. Common molding methods include extrusion, injection molding, cold pressing, and conventional hot pressing, but all have significant limitations: Extrusion and injection molding: They need to be carried out at high temperatures (usually over 380°C) to ensure melt fluidity. However, high temperatures can easily lead to the decomposition of the PEEK matrix and the functional groups of the additives, destroying the material properties. At the same time, the PEEK melt viscosity is too high and the melt index is low, which can easily cause bonding defects between the matrix and the doping material, resulting in a decrease in the density and mechanical properties of the finished product. Cold pressing: The molding temperature is low (usually below 200°C), which can protect the functional groups to a certain extent. However, the powder only softens locally and cannot completely eliminate internal pores and cracks. The density is insufficient and the mechanical properties are poor. Conventional hot pressing: This method combines external heating (such as resistance wire) and pressure to form the part. However, it has low heat transfer efficiency. For PEEK materials with poor thermal conductivity, the actual powder temperature is much lower than the mold temperature, and there is a significant temperature gradient, resulting in an uneven internal structure of the material. At the same time, the heating rate is slow (usually 5-10°C / min), and prolonged heating can easily cause material aging, further degrading performance.

[0003] Spark plasma sintering (SPS) is a new rapid sintering technology. Its core principle is to achieve extremely rapid material heating and densification through the use of pulsed current to generate Joule heating and plasma activation. Compared with traditional molding technologies, SPS offers the following advantages: extremely rapid heating: heating rates can reach 20-30°C / min, significantly shortening heating time and reducing damage to material functional groups; internal heating: heat is generated within the material, resulting in uniform temperature distribution and avoiding the temperature gradient problems associated with traditional external heating; plasma activation: the plasma generated by the pulsed discharge cleans the powder surface, improves interparticle bonding, and promotes densification; and a vacuum / inert atmosphere environment: reduces material oxidation, lowers bubble content in the melt, and improves density. Existing research has confirmed the advantages of SPS in the preparation of polymers and composites: Oluwagbenga Tobi Adesina et al. reviewed that polymer-based composites prepared by SPS are superior to traditional methods in terms of thermal conductivity and crystallization rate. Maxime Schwertz et al. optimized SPS parameters (temperature, pressure, and holding time) to achieve an elastic modulus of polyimide (PI) of 3.43 GPa and a compression limit of 738 MPa, verifying the performance-enhancing effect of SPS on high-performance polymers.

[0004] However, a systematic solution for the SPS sintering process of composite polyetheretherketone has not yet been formed. The existing technology lacks research on the synergistic mechanism of PEEK and doped phases such as carbon fiber, graphite, and silica. The influence of SPS parameters (temperature gradient, pressure curve, holding time, etc.) on the microstructure and macroscopic properties of composite PEEK has not been clarified, resulting in the inability to fully realize the performance potential of composite PEEK.

[0005] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0006] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a composite polyetheretherketone and its preparation method and application, aiming to solve the problems of functional group destruction, bonding defects, insufficient density and poor performance stability in the existing preparation method of composite polyetheretherketone.

[0007] The technical solutions of the present invention are as follows: A method for preparing a composite polyetheretherketone, comprising the steps of: 70-80% of polyetheretherketone, 5-15% of carbon fiber, 5-10% of graphite, and 2.5-7.5% of silicon dioxide are added into a planetary centrifugal high-speed mixer and vacuum blended to obtain a mixed powder; placing the mixed powder into a mold and cold pressing the mold to obtain a pre-pressed product; The pre-pressed product is placed in a spark plasma sintering furnace and evacuated, and 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 at a heating rate of 20-30°C / min to a sintering temperature of 100-200°C, and a sintering pressure of 0.5-30MPa; then, the temperature is increased at a heating rate of 20-30°C / min to a sintering temperature of 200-300°C, and a sintering pressure of 0.5-5MPa, and the holding time is 20-40min; then, the temperature is increased at a heating rate of 5-10°C / min to a sintering temperature of 300-400°C, and the holding time is 20-40min. ℃, the sintering pressure is 0-0.5MPa, and the holding time is 30-60min; then the temperature is cooled 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 cooled 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 cooled to 100-170℃ at a cooling rate of 10-20℃ / min, the mold is taken out, and the mold is demoulded while hot to obtain a composite polyetheretherketone.

[0008] The preparation method of the composite polyetheretherketone, wherein the relative molecular weight of the polyetheretherketone is 30,000-80,000, the carbon fiber is one of filaments, short fibers and chopped fibers; the graphite is one of flakes, blocks and earth; and the silicon dioxide is one of crystalline and amorphous.

[0009] The preparation method of the composite polyetheretherketone, wherein the mesh number of the polyetheretherketone is 200-1000, the aspect ratio of the carbon fiber is 2-8:1, the particle size of the graphite is 1-10 μm, and the particle size of the silicon dioxide is 1-100 nm.

[0010] The preparation method of the composite polyetheretherketone comprises the following steps: adding 70-80% of polyetheretherketone, 5-15% of carbon fiber, 5-10% of graphite, and 2.5-7.5% of silicon dioxide, measured by mass percentage, to a planetary centrifugal high-speed mixer for vacuum blending; and achieving uniform blending under vacuum conditions by adjusting the difference between the rotational speed and the orbital speed. The first stage comprises: an orbital speed of 200-600 rpm, an autorotation speed of 100-300 rpm, and a time of 1-2 minutes; a second stage comprises: an orbital speed of 1500-1800 rpm, an autorotation speed of 800-1000 rpm, and a time of 30-60 seconds; and a third stage comprises: an orbital speed of 800-1200 rpm, an autorotation speed of 400-800 rpm, and a time of 10-30 seconds.

[0011] The preparation method of the composite polyether ether ketone, wherein the mixed powder is put into a mold coated with a release agent for cold pressing forming, the forming pressure is 10-30 MPa, and the time is 10-30 min.

[0012] The preparation method of the composite polyether ether ketone, wherein the pre-pressed product is put into a spark plasma sintering furnace and vacuumized, the vacuum degree in the spark plasma sintering furnace is 2x10 -2 -5x10 -4 Pa.

[0013] The preparation method of the composite polyether ether ketone, wherein the inert gas is one of argon and nitrogen.

[0014] A composite polyether ether ketone, wherein the preparation method of the composite polyether ether ketone is used.

[0015] The application of a composite polyether ether ketone, wherein the composite polyether ether ketone is used to prepare one of a hydrating lubricating bearing, a gearbox gear, a wafer carrier and a vacuum pump blade.

[0016] Beneficial effects: The present application provides a preparation method of a composite polyether ether ketone. The spark plasma sintering treatment (SPS) provides a faster heating rate and a vacuum environment, which can reduce the bubble content in the melt, make the groups in the polyether ether ketone material better react with the doped material, increase the contact area between the doped graphite, carbon fiber and silicon dioxide particles in the material, quickly bridge and toughen the interface between the polymer, increase the compatibility, increase the bonding degree of the material, and further improve the mechanical properties and wear resistance of the composite polyether ether ketone. The composite polyether ether ketone sample prepared by the method has uniform composite organization, good compatibility between phases, high strength, and the SPS sintering composite polyether ether ketone is simple to operate and easy to implement. Compared with ordinary composite polyether ether ketone materials, the sintered composite polyether ether ketone has effectively improved compression strength and friction performance. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a flowchart of the preparation method of the composite polyether ether ketone.

[0018] Figure 2 It is a ball-on-disc reciprocating friction and wear test result graph of the composite polyether ether ketone prepared in Examples 1-2 and Comparative Examples 1-2 in 15N, 5Hz, 3% NaCl solution and silicon nitride ball friction pair.

[0019] Figure 3 It is a compression performance test result graph of the composite polyether ether ketone prepared in Examples 1-2 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0020] The present invention provides a composite polyetheretherketone and its preparation method and application. To make the purpose, technical solution and effects of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only for the purpose of explaining the present invention and are not intended to limit the present invention.

[0021] As a high-performance engineering plastic, polyetheretherketone has the following key problems in traditional processing: Functional group destruction: The traditional molding method has a slow heating rate (<10℃ / min) and a long duration of high temperature, which causes the PEEK matrix and doping materials (such as carbon fiber surface functional groups) to oxidize or decompose, reducing the material interface bonding strength. Bonding defects: PEEK melt has high viscosity and poor fluidity. In traditional processes, it is difficult to evenly mix the matrix with doping phases such as carbon fiber and graphite, which easily produces interfacial voids, resulting in a decrease in mechanical properties. Insufficient density: Cold pressing cannot eliminate porosity. Ordinary hot pressing causes uneven densification of the material due to temperature gradients. The porosity of the finished product usually exceeds 5%, affecting strength and wear resistance. Poor performance stability: Fluctuations in traditional process parameters (such as temperature deviation and uneven pressure) can easily lead to discrete product performance and fail to meet the material consistency requirements of high-end equipment.

[0022] The core reason for these issues lies in the inability of traditional molding technologies to simultaneously address the three key requirements of rapid heating to protect functional groups, uniform heating to promote densification, and interfacial activation to enhance compatibility. Therefore, developing an SPS sintering process suitable for composite PEEK, and addressing these issues through precise control of sintering parameters, has become an urgent need in this field.

[0023] Based on this, the present invention provides a method for preparing a composite polyetheretherketone, such as Figure 1 As shown, it includes the steps of: S10, adding 70-80% of polyetheretherketone, 5-15% of carbon fiber, 5-10% of graphite, and 2.5-7.5% of silicon dioxide, by mass percentage, to a planetary centrifugal high-speed mixer for vacuum blending to obtain a mixed powder; S20, placing the mixed powder into a mold for cold pressing to obtain a pre-pressed product; S30, the pre-pressed product is placed in a spark plasma sintering furnace and vacuumized, and then subjected to spark plasma sintering treatment in an inert gas environment according to the following multi-stage temperature-pressure curve: first, the temperature is raised to 100-200℃ at a heating rate of 20-30℃ / min, and the sintering pressure is 0.5-30MPa; then, the temperature is raised to 200-300℃ at a heating rate of 20-30℃ / min, and the sintering pressure is 0.5-5MPa, and the holding time is 20-40min; then, the temperature is raised to 300-400℃ at a heating rate of 5-10℃ / min, and 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, and 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, and 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 taken out, and the product is demolded while hot to obtain the composite polyether ether ketone.

[0024] The present application adopts spark plasma sintering (SPS) technology, utilizes the advantages of extremely fast heating, internal heating, plasma activation and vacuum environment, realizes the performance improvement of composite PEEK through the following ideas: selecting PEEK, carbon fiber, graphite and silicon dioxide with specific ratio, utilizing the synergistic effect of each component (such as carbon fiber reinforcement, graphite lubrication and silicon dioxide wear resistance) to improve the comprehensive performance; precise mixing process: adopting a planetary centrifugal high-speed mixer, realizing uniform mixing of raw materials through three-stage speed control to avoid agglomeration; gradient sintering control: designing a multi-stage temperature-pressure curve to realize the continuous process of low-temperature pre-pressing, medium-temperature densification, high-temperature interface reaction and gradient cooling and shaping, considering both densification and functional group protection; inert atmosphere protection: sintering in argon or nitrogen environment to reduce material oxidation and reduce bubble content.

[0025] Specifically, the present application realizes the function synergy of bearing-reinforcing-lubricating-wearing resistance by accurately designing the mass percentage of polyether ether ketone, carbon fiber, graphite and silicon dioxide, wherein PEEK accounts for 70-80% as the matrix material, the benzene ring and ether bond structure contained in the molecular chain of PEEK endow the material with excellent high temperature resistance (melting point 343℃) and mechanical strength (pure PEEK compressive strength about 900MPa); wherein the carbon fiber accounts for 5-15%, the axial tensile strength (>3000MPa) of the carbon fiber is more than 10 times of PEEK, and the carbon fiber can cross the microcracks in the matrix through the bridging effect, when the material is loaded, the stress is transmitted to the carbon fiber through the interface, which significantly improves the anti-fracture ability of the composite polyether ether ketone; meanwhile, the high rigidity (elastic modulus >200GPa) of the carbon fiber can also limit the plastic flow of the PEEK matrix during friction, avoiding the aggravation of wear caused by local deformation; wherein the graphite accounts for 5-10%, the layered structure (weak interlayer van der Waals force) of the graphite is the core to realize low friction performance, during friction, the graphite layers slide along the basal plane under the action of shear force, and the friction coefficient can be reduced to below 0.2, and the particle size of 1-10μm ensures that the graphite can uniformly cover the friction interface to form a continuous lubricating film, reducing the direct wear of the PEEK matrix, the wear rate of the composite polyether ether ketone of the embodiment is reduced by one order of magnitude, and based on this mechanism, if the graphite accounts for less than 5%, the transfer film is discontinuous; if the graphite accounts for more than 10%, the strength of the matrix will be weakened; wherein the silicon dioxide (Mohs hardness 7) is uniformly dispersed in the PEEK matrix, which can resist the cutting action of abrasive particles; the particle size of 1-100nm of the silicon dioxide enables it to fill the micro gaps between PEEK and carbon fiber, and the pinning effect enhances the interfacial bonding force, avoiding the aggravation of wear caused by interfacial peeling during friction, and if the proportion is too high (>7.5%), the silicon dioxide is easy to agglomerate to form stress concentration points, which reduces the strength.

[0026] In the prior art, composite PEEK mainly focuses on single performance, such as adding only carbon fiber for reinforcement or adding only graphite for lubrication, while the present application first proposes a four-component synergistic design, which realizes the balance of strength-lubrication-wear resistance by limiting the proportion range of each component. In the traditional formula, the proportion of graphite is often more than 15% to pursue low friction, but it will cause the strength to decrease by more than 20%, while the present application synergizes 5-10% of graphite with 2.5-7.5% of silicon dioxide, which maintains low friction without sacrificing strength.

[0027] This invention utilizes a planetary centrifugal high-speed mixer, which solves the problem of carbon fiber agglomeration through three-stage speed and time control and a vacuum environment. Specifically, the centrifugal force generated by the device's revolution causes the material to aggregate toward the container wall, forming a high-density mixing zone. The shear force generated by its rotation acts radially on the material, breaking up the entangled agglomeration of the carbon fibers (carbon fibers are prone to forming fiber balls due to their large aspect ratio). The invention limits the speed range of revolution and rotation to ensure a balance between shear and centrifugal forces: 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 optimizes functionality and device stability. The mixing process of the present invention is divided into three stages (1-2 minutes → 30-60 seconds → 10-30 seconds). The functions of each stage are as follows: the first stage (1-2 minutes): low-speed premixing (200-600 rpm orbital rotation / 100-300 rpm) ensures that the PEEK powder evenly wraps the carbon fiber and graphite, preventing fiber breakage caused by subsequent high shear. The second stage (30-60 seconds): high-speed intense shear (1500-1800 rpm orbital rotation / 800-1000 rpm axis axis) breaks up carbon fiber agglomerates through shear force, reducing the number of agglomerates by 60%. The third stage (10-30 seconds): medium-speed homogenization (800-1200 rpm orbital rotation / 400-800 rpm axis axis) eliminates local concentration differences and ensures that the silica nanoparticles evenly fill the gaps. This gradient design of predispersion, intense shear, and homogenization solves the problems of incomplete dispersion and fiber breakage in traditional single-speed mixing. Mixing is performed in a vacuum environment, which removes air and moisture, preventing interfacial defects caused by gas adsorption on the powder surface. It also inhibits oxidation of the carbon fibers during shearing, ensuring compatibility with PEEK. Existing technologies often use a single mixing speed, failing to balance dispersion and agglomeration with carbon fiber protection. The three-stage design of the present invention achieves a balance between these two through gradient shearing.

[0028] The multi-stage temperature, pressure and rate control of the SPS sintering process of the application is a precise control strategy designed for the material properties of the composite polyether ether ketone (high melting point, high melt viscosity, easy oxidation) and the defects of the traditional forming process (low density, poor interface bonding, functional group damage), which solves the contradiction between high temperature and long time required for densification in traditional hot pressing and functional group damage. 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 glass transition temperature is about 143℃) at this time, through the extremely fast heating of 20-30℃ / min (3-5 times of traditional hot pressing) to shorten the low temperature residence time and reduce the recondensation of water vapor adsorbed on the surface of the powder; at the same time, high pressure of 0.5-30MPa is applied to make PEEK, carbon fiber, graphite and other particles tightly packed, quickly expel the air in the interparticle gap (about 70% of the initial gas is expelled in this stage), and the relative density is increased from 60-70% after cold pressing to 75-80%. This stage can avoid the gas retention problem caused by slow heating (5-10℃ / min) in traditional hot pressing, laying a low porosity foundation for subsequent densification, and high pressure compaction can reduce the risk of melt overflow in the subsequent high temperature stage.

[0029] In the second heating stage (200-300℃, 20-30℃ / min, 0.5-5MPa, 20-40min), the temperature range of 200-300℃ makes the PEEK particle surface begin to soften (without reaching the melting state), and the carbon fiber and graphite particles preliminarily contact the PEEK surface due to thermal expansion; at this time, the pressure is reduced to 0.5-5MPa (medium pressure), which can promote the conversion of point contact to surface contact between particles through the viscous flow of the softened layer, and avoid powder splashing caused by high pressure; 20-40min of holding can improve the uniformity of softening and ensure consistent preliminary bonding in different regions. This stage can solve the defects of traditional cold pressing, such as mechanical force bonding and lack of adhesive effect at the interface, and achieve preliminary adhesion between particles through surface softening, providing a continuous structural basis for subsequent high-temperature densification; the extremely fast heating can still reduce the early oxidation of PEEK ether bonds.

[0030] In the third heating stage (300-400℃, 5-10℃ / min, 0-0.5MPa, 30-60min), 300-400℃ is close to the melting point of PEEK (343℃), and the powder enters a semi-melted-melted state. At this time, the heating rate is reduced to 5-10℃ / min and the pressure is kept low (0-0.5MPa), which can avoid the local overheating decomposition of the melt caused by fast heating, and provide reaction time for the core advantage of SPS, plasma activation: the plasma (Ar +, electronics, etc.) cleans the oxide layers on the PEEK and carbon fiber surfaces (such as the oxidation products of the carbon fiber surface hydroxyl groups), increasing the surface energy by 50% and promoting hydrogen bonding between the PEEK ether bonds and the carbon fiber hydroxyl groups. A 30-60 minute heat preservation ensures sufficient interfacial reaction and forms 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, the dual mechanical and chemical bonding between particles is achieved, significantly improving interfacial bonding strength. The low-pressure environment prevents melt overflow and reduces bubble encapsulation.

[0031] The cooling stage of the present invention is also divided into three steps, coordinated with pressure maintenance, to achieve densification and eliminate internal stress. In the first cooling stage (300-350°C, 10-20°C / min, 0.5-5MPa, and a hold time of 10-30 minutes), 300-350°C is the critical temperature range for PEEK's transition from molten to solid state (the crystallization temperature zone). During this period, a slow cooling rate of 10-20°C / min, combined with a pressure of 0.5-5MPa, suppresses microcracks caused by molecular chain rearrangement during PEEK crystallization. The 10-30 minute hold time ensures more uniform crystallization and avoids performance fluctuations caused by localized crystallinity differences. This stage solves the problems of insufficient crystallization and internal stress concentration associated with traditional rapid cooling. Pressure-assisted crystallization improves structural stability, laying the foundation for subsequent mechanical properties.

[0032] In the second cooling stage (200-300°C, 20-30°C / min, 0.5-10MPa, 10-60min hold), PEEK crystallizes at 200-300°C. Cooling at a rate of 20-30°C / min while applying 0.5-10MPa of pressure compensates for thermal shrinkage through mechanical force, reducing internal stress from >20MPa in traditional processes to <5MPa. A 10-60min hold allows for gradual stress release, preventing cracking caused by stress concentration. This stage addresses the high internal stress and low dimensional accuracy associated with traditional hot pressing without pressure cooling, keeping the finished product's dimensional deviation within ±0.02mm, meeting the requirements of precision components such as wafer carriers.

[0033] During the final cooling stage (100-170°C, 10-20°C / min, hot demolding), the temperature is above PEEK's glass transition temperature (143°C), allowing the material to retain a certain degree of plasticity. Demolding at this temperature avoids cracking caused by increased brittleness at lower temperatures (<100°C). A cooling rate of 10-20°C / min ensures uniform temperature and avoids deformation caused by local temperature differences. This stage addresses the cracking and dimensional deformation associated with traditional cold demolding, ensuring the integrity and dimensional accuracy of the finished product.

[0034] The above multi-stage control achieves multiple advantages that traditional processes cannot achieve through a closed-loop design of heating and compacting - plasma activation - cooling and shaping, which are as follows: Density Improvement: 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). Interface Bonding Enhancement: Through plasma activation and gentle heating, interface bonding is increased by 30%, 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 >95% retention of PEEK ether bonds and carbon fiber hydroxyl groups, avoiding functional group decomposition caused by traditional slow heating (>3h). Internal Stress Reduction: Step-by-step cooling and pressure compensation reduce internal stress to <5MPa, reducing batch performance fluctuation from 12-15% to 3-4%. This multi-stage SPS control method is not a simple addition of parameters; rather, it targets the material properties of composite PEEK. Through a synergistic mechanism of rapid heating to preserve functional groups, plasma to strengthen the interface, gradient pressure to promote densification, and step-by-step cooling to relieve stress, it systematically addresses the core shortcomings of traditional molding processes, ultimately achieving a comprehensive leap in material performance.

[0035] In some embodiments, the relative molecular weight of the polyetheretherketone is 30,000-80,000. As an example, the polyetheretherketone can be one of Zhongyan Co., Ltd., Junhua Special Plastics and Jida Special Plastics. For example, Zhongyan Co., Ltd. is divided into three main brands of 770, 550 and 330 according to melt fluidity from low to high; Junhua Special Plastics' AKSOPEEK series and Jida Special Plastics' PEEKGF30 product.

[0036] In some embodiments, the carbon fiber is one of filaments, short fibers, and chopped fibers, but not limited thereto; the graphite is one of flakes, blocks, and earth, but not limited thereto; and the silica is one of crystalline and amorphous, but not limited thereto.

[0037] In some embodiments, the mesh size of the polyetheretherketone is 200-1000. This range not only avoids the problem of agglomeration of overly fine powder (>1000 mesh) in the mixture, but also solves the densification difficulty caused by overly coarse powder (<200 mesh), laying the foundation for the uniformity of subsequent sintering.

[0038] In some embodiments, the carbon fibers have an aspect ratio of 2-8:1. If the aspect ratio is greater than 8:1, the carbon fibers tend to entangle and agglomerate; if the aspect ratio is less than 2:1, an effective reinforcement network cannot be formed. Therefore, limiting the carbon fiber aspect ratio to a range of 2:1-8:1 is key to balancing functionality and processability. Prior art lacks a clear correlation between PEEK mesh size and carbon fiber aspect ratio. The present invention finds that 200-1000 mesh PEEK and carbon fibers with an aspect ratio of 2-8:1 can form an optimal particle-fiber filling structure, resolving the conflict between coarse PEEK particles and long fiber agglomeration.

[0039] In some embodiments, in the step of placing the mixed powder into a mold coated with a release agent for cold pressing, the molding pressure is 10-30 MPa and the time is 10-30 min, but the present invention is not limited thereto.

[0040] In some embodiments, in the step of placing the pre-pressed product into a spark plasma sintering furnace and evacuating the vacuum, the vacuum degree in the spark plasma sintering furnace is 2×10 -2 -5×10 -4 Pa. In this embodiment, the furnace is pumped to 2×10 -2 -5×10 -4 Pa ultimate vacuum, its functions include: expelling air from the gaps between powder particles and adsorbing water vapor to prevent gas expansion and formation of bubbles during sintering temperature rise; reducing gas partial pressure to allow trace volatiles released during PEEK melting to be discharged smoothly; introducing inert gas after vacuum to replace residual air and inhibit the oxidation of PEEK and carbon fiber at high temperature (300-400℃). Argon, as an inert gas, can enhance the plasma intensity generated by SPS pulse discharge (Ar + The ionization energy is low), which promotes powder surface activation. Experiments show that the plasma density in an argon environment is 1.2 times that of nitrogen, resulting in more complete interfacial reactions.

[0041] In some embodiments, the inert gas is one of argon and nitrogen, but is not limited thereto.

[0042] In some embodiments, a composite polyetheretherketone is also provided, wherein the composite polyetheretherketone is prepared using the preparation method of the composite polyetheretherketone described in the present invention.

[0043] In some embodiments, an application of a composite polyetheretherketone is also provided, wherein the composite polyetheretherketone of the present invention is used to prepare one of a hydrated lubricated bearing, a gearbox gear, a wafer carrier, and a vacuum pump blade.

[0044] The present invention will be further explained below by means of specific embodiments: Example 1 A method for preparing a composite polyetheretherketone comprises the following steps: 80% of polyetheretherketone, 10% of carbon fiber, 7% of graphite, and 3% of silicon dioxide, by mass percentage, were added to a planetary centrifugal high-speed mixer and vacuum blended to obtain a mixed powder, wherein the first stage: the revolution speed was 300 rpm, the rotation speed was 100 rpm, and the time was 2 min; the second stage: the revolution speed was 1600 rpm, the rotation speed was 800 rpm, and the time was 40 s; the third stage: the revolution speed was 1000 rpm, the rotation speed was 500 rpm, and the time was 20 s; wherein the mesh size of the polyetheretherketone was 1000 mesh, the aspect ratio of the carbon fiber was 5:1, the particle size of the graphite was 2 μm, and the particle size of the silicon dioxide was 10 nm; 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. The pre-pressed product is placed in a spark plasma sintering furnace and evacuated to 5×10 -4 Pa, and then spark plasma sintering treatment is carried out in an argon gas environment according to the following multi-stage temperature-pressure curve: first, the temperature is increased at a heating rate of 30°C / min to a sintering temperature of 200°C and a sintering pressure of 20 MPa; then the temperature is increased at a heating rate of 30°C / min to a sintering temperature of 300°C, a sintering pressure of 4 MPa, and a holding time of 30 min; then the temperature is increased to 400°C at a heating rate of 10°C / min, a sintering pressure of 0.5 MPa, and a holding time of 60 min; then the temperature is decreased at a cooling rate of 20°C / min to 300°C, a sintering pressure of 0.5 MPa, and a holding time of 30 min; then the temperature is decreased at a cooling rate of 30°C / min to 250°C, a sintering pressure of 5 MPa, and a holding time of 30 min; finally, the temperature is decreased at a cooling rate of 20°C / min to 150°C, the mold is taken out, and the mold is demoulded while hot to obtain a composite polyetheretherketone.

[0045] Example 2 A method for preparing a composite polyetheretherketone comprises the following steps: 70% of polyetheretherketone, 15% of carbon fiber, 10% of graphite, and 5% of silicon dioxide, by mass percentage, were added to a planetary centrifugal high-speed mixer and vacuum blended to obtain a mixed powder; wherein the vacuum blending step was the same as in Example 1; the mesh size of the polyetheretherketone was 300 mesh, the aspect ratio of the carbon fiber was 2:1, the particle size of the graphite was 5 μm, and the particle size of the silicon dioxide was 50 nm; 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 minutes. The pre-pressed product is placed in a spark plasma sintering furnace and evacuated to 2×10 -2Pa, and then spark plasma sintering treatment is carried out in an argon gas environment according to the following multi-stage temperature-pressure curve: first, the temperature is increased to a sintering temperature of 180°C at a heating rate of 20°C / min and a sintering pressure of 20 MPa; then the temperature is increased to a sintering temperature of 300°C at a heating rate of 30°C / min, the sintering pressure is 4 MPa, and the holding time is 30 min; then the temperature is increased to 380°C at a heating rate of 5°C / min, the sintering pressure is 2.5 MPa, and the holding time is 60 min; then the temperature is decreased to 300°C at a cooling rate of 20°C / min, the sintering pressure is 2.5 MPa, and the holding time is 10 min; then the temperature is decreased to 200°C at a cooling rate of 30°C / min, the sintering pressure is 7.5 MPa, and the holding time is 60 min; finally, the temperature is decreased to 170°C at a cooling rate of 10°C / min, the mold is taken out, and the mold is demoulded while hot to obtain a composite polyetheretherketone.

[0046] Comparative Example 1 (Vacuum Hot Press Sintering) The present comparative example provides a method for preparing composite polyetheretherketone by sintering in a vacuum hot pressing furnace. The composition of the composite polyetheretherketone is the same as that in Example 1, and the preparation steps of the mixed powder and the pre-pressed product are also the same as those in Example 1, except that a vacuum hot pressing furnace is used for sintering, and during the sintering process, the temperature is first increased to 250°C at a rate of 10°C / min under a constant pressure of 5MPa and kept warm for 45min; then kept warm at 250°C for 10min; then increased to 360°C at a rate of 5°C / min and kept warm for 180min; then cooled to 280°C and kept warm for 60min. The vacuum environment during the sintering process is 6×10 -3 Pa, and finally demoulding to obtain composite polyetheretherketone.

[0047] Comparative Example 2 (Muffle Furnace Sintering + Die Casting) This comparative example provides a muffle furnace sintering preparation method for a composite polyetheretherketone. The composition of the composite polyetheretherketone is the same as that in Example 1, and the preparation steps of the mixed powder and the pre-pressed product are also the same as those in Example 1, except that a muffle furnace is used for sintering. During the sintering process, the temperature is first increased to 430°C at a rate of 10°C / min; then the temperature is kept at 430°C for 2h; then the temperature is cooled to 360°C at a rate of 2°C / min; thereafter, the mold is removed from the muffle furnace at 360°C, placed in a tablet press, and die-casted at 33MPa. After maintaining the pressure for 30min, the mold is placed in the air for natural cooling. There is no rare gas and vacuum environment during the sintering process to obtain a composite polyetheretherketone.

[0048] The results of the reciprocating friction and wear test 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 are shown in Tables 1 and Figure 2 shown.

[0049] Table 1 Friction and wear performance data

[0050] From Table 1 and Figure 2 The data shows that, compared with Comparative Example 1, the composite polyetheretherketone sintered by SPS in Examples 1-2 has a lower friction coefficient and wear rate under the same friction test conditions. Clearly, the tribological performance of Examples 1-2 is significantly better than that of Comparative Example 1. This is because in Examples 1-2, the plasma activation effect of SPS creates a pinning effect at the interface between PEEK and silica (1-100nm), allowing silica to be evenly embedded in the matrix, resisting the cutting action of abrasive particles. The wear surfaces of the Examples show shallow and uniform wear scars with no obvious furrows. However, in Comparative Example 1, due to the lack of plasma activation, micro-gaps (porosity 4.2%) exist at the interface between silica and PEEK. During friction, silica easily falls off the matrix and becomes abrasive particles, exacerbating wear. In addition, Example 1-2 can achieve a density of 99.2% (porosity 0.8%) through SPS gradient pressure (30MPa→0.5MPa), the stress concentration effect of the pores is suppressed, and there is no local plastic deformation aggravation during the friction process; while in Comparative Example 1, due to the single pressure (5MPa) of vacuum hot pressing, the porosity reaches 4.2%, plastic flow is easily generated around the pores, and the wear rate increases.

[0051] From Table 1 and Figure 2 The data show that the tribological properties of Comparative Example 2 are poor. This is because Comparative Example 2 was sintered in an air environment of a muffle furnace (430℃ for 2h), and the graphite underwent oxidation reaction, resulting in a sharp decrease in the content of the lubricating phase. At the same time, the hydroxyl groups (-OH) on the surface of the carbon fiber were oxidized to carboxyl groups (-COOH), and the compatibility with PEEK dropped sharply. The carbon fiber was easily broken and fell off during friction, forming abrasive particles ( Figure 2 The friction curve of Comparative Example 2 fluctuates dramatically, demonstrating the failure of the lubricating film. In contrast, Examples 1-2 utilize vacuum-argon protection to prevent oxidation of the graphite and carbon fibers. Graphite exhibits excellent stability in an inert environment and can maintain its lubricating function over time. Comparative Example 2 lacks vacuum treatment, and the air between the powders expands at high temperatures to form bubbles (porosity 5.8%). Furthermore, the die-casting pressure (33 MPa) is applied only in the later stages and cannot eliminate the bubbles. During friction, stress concentration occurs around the bubbles, leading to localized spalling of the PEEK matrix and a wear rate increase of 7.65*10 -6 cm 3 / (N·m); while Examples 1-2 utilize SPS extreme vacuum degassing to achieve a bubble content of <0.1%, resulting in uniform force at the friction interface. The external heating of the muffle furnace in Comparative Example 2 creates a temperature gradient (temperature difference >30°C), leading to localized graphite aggregation, oxidative embrittlement of the PEEK, and large fluctuations in the friction coefficient. In contrast, the internal heating of the SPS in Examples 1-2 achieves a uniform temperature distribution (temperature difference <5°C), resulting in consistent distribution of lubricating and wear-resistant phases.

[0052] The composite polyetheretherketone prepared in Example 1-2 and Comparative Example 1-2 was subjected to compression performance test, and the results are shown in Table 2 and Table 3. Figure 3 shown.

[0053] Table 2 Compression performance test data

[0054] From Table 2 and Figure 3 The data shows that the compressive strength of Example 1-2 is significantly higher than that of Comparative Example 1, which is mainly due to the optimization of density, interface bonding and functional group retention by SPS process. Example 1-2 uses SPS multi-stage pressure control: low temperature and high pressure (20-30MPa) to quickly compact the powder, high temperature and low pressure (0-0.5MPa) to promote diffusion welding ( Figure 3 The compression curve of the embodiment in the example has no obvious yield plateau, demonstrating a dense structure. However, the vacuum hot pressing in Comparative Example 1 uses a single pressure (5 MPa), which cannot achieve both compaction and diffusion. The porosity reaches 4.2%. The pores become a source of stress concentration during the compression process, leading to premature fracture. The plasma activation of the SPS in Examples 1-2 (300-400°C holding stage) increases the surface energy of the carbon fiber by 50%, forming hydrogen bonds between the PEEK ether bonds (-O-) and the carbon fiber hydroxyl groups (-OH), enhancing the interfacial shear strength. During compression, stress is effectively transferred through the interface to the high-strength carbon fiber (tensile strength >3000 MPa), exerting a bridging reinforcement effect. However, in Comparative Example 1, there is a gap at the interface between the carbon fiber and PEEK. During compression, the interface peels off first, preventing the carbon fiber from being fully stressed, weakening the reinforcement effect. In Example 1-2, the rapid heating of 20-30°C / min shortens the high-temperature time, the PEEK ether bond decomposition rate is <5%, and the molecular chain integrity is good; while in Comparative Example 1, the heating rate is 10°C / min, the high temperature is sustained for more than 3 hours, the ether bond decomposition rate is >30%, the molecular weight of the PEEK matrix decreases, resulting in a decrease in the strength of the matrix itself.

[0055] From Table 2 and Figure 3The data can see that the compressive strength of Comparative Example 2 is the lowest, which is caused by high defects due to oxidation deterioration and process inconsistency. Comparative Example 2 is sintered in air environment (430℃), PEEK is oxidized and degraded, the molecular chain is broken to cause the decrease of the matrix strength; at the same time, a thick oxidation layer (O element content 12.5%) is formed on the surface of the carbon fiber, the interfacial bonding force between the carbon fiber and PEEK is decreased, and the interface is easy to be debonded during compression; while the examples are in vacuum-argon environment to inhibit oxidation, the ether bond and benzene ring structure in the PEEK molecular chain are stable, and there is no oxidation layer on the surface of the carbon fiber. Comparative Example 2 is not treated in vacuum, air is involved to form bubbles (porosity 5.8%), and the muffle furnace is separated from the die casting process (360℃ die casting), and thermal stress causes microcracks; during compression, stress concentration (stress amplification coefficient > 5) is generated at the bubble and crack tip, which causes the material to be broken in advance; while in Examples 1-2, the SPS is in the limit vacuum to exhaust gas, and is matched with gradient pressure to eliminate bubbles, and the stress is uniformly distributed during compression Figure 3 The compressive curve of the middle example has a large slope and high rigidity.

[0056] It should be understood that the application of the present application is not limited to the above examples, and can be improved or changed according to the above description for those skilled in the art, and all these improvements and changes should belong to the protection scope of the appended claims of the present application.

Claims

1. A method for preparing a composite polyetheretherketone, characterized in that: Including steps: 70-80% of polyetheretherketone, 5-15% of carbon fiber, 5-10% of graphite, and 2.5-7.5% of silicon dioxide are added into a planetary centrifugal high-speed mixer and vacuum blended to obtain a mixed powder; placing the mixed powder into a mold and cold pressing the mold to obtain a pre-pressed product; The pre-pressed product is placed in a spark plasma sintering furnace and evacuated, and 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 at a heating rate of 20-30°C / min to a sintering temperature of 100-200°C, and a sintering pressure of 0.5-30MPa; then, the temperature is increased at a heating rate of 20-30°C / min to a sintering temperature of 200-300°C, and a sintering pressure of 0.5-5MPa, and the holding time is 20-40min; then, the temperature is increased at a heating rate of 5-10°C / min to a sintering temperature of 300-400°C, and the holding time is 20-40min. ℃, the sintering pressure is 0-0.5MPa, and the holding time is 30-60min; then the temperature is cooled 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 cooled 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 cooled to 100-170℃ at a cooling rate of 10-20℃ / min, the mold is taken out, and the mold is demoulded while hot to obtain a composite polyetheretherketone.

2. The method for preparing the composite polyetheretherketone according to claim 1, characterized in that: The relative molecular weight of the polyetheretherketone is 30,000-80,000, the carbon fiber is one of filaments, short fibers and chopped fibers; the graphite is one of flakes, blocks and earth; 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 mesh number of the polyetheretherketone is 200-1000, the aspect ratio of the carbon fiber is 2-8:1, the particle size of the graphite is 1-10 μm, and the particle size of the silicon dioxide is 1-100 nm.

4. The method for preparing the composite polyetheretherketone according to claim 1, characterized in that: In the step of adding 70-80% of polyetheretherketone, 5-15% of carbon fiber, 5-10% of graphite, and 2.5-7.5% of silicon dioxide by mass percentage into a planetary centrifugal high-speed mixer for vacuum blending, uniform blending is achieved under vacuum conditions by the difference between the rotation speed and the revolution speed, wherein the first section: the revolution speed is 200-600 rpm, the rotation speed is 100-300 rpm, and the time is 1-2 minutes; the second section: the revolution speed is 1500-1800 rpm, the rotation speed is 800-1000 rpm, and the time is 30-60 seconds; the third section: the revolution speed is 800-1200 rpm, the rotation speed is 400-800 rpm, and the time is 10-30 seconds.

5. The method for preparing the composite polyetheretherketone according to claim 1, characterized in that: The mixed powder is placed in a mold coated with a release agent and cold pressed to form the mixture. The forming pressure is 10-30 MPa and the forming time is 10-30 minutes.

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 a spark plasma sintering furnace and evacuating the vacuum, the vacuum degree in the spark plasma sintering furnace is 2×10 -2 -5×10 -4 Pa.

7. The method for preparing composite polyetheretherketone according to claim 1, characterized in that: The inert gas is one of argon and nitrogen.

8. A composite polyetheretherketone, characterized in that The composite polyetheretherketone is prepared by the preparation method according to any one of claims 1 to 7.

9. An application of a composite polyetheretherketone, characterized in that: The composite polyetheretherketone according to claim 8 is used to prepare one of a hydrated lubricated bearing, a gearbox gear, a wafer carrier and a vacuum pump blade.

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