Semi-solid phase-change composite material for heat conduction of aerospace electronic device and preparation method of semi-solid phase-change composite material

Abstract

The invention is applicable to the technical field of phase-change materials, and provides a semi-solid phase-change composite material for heat conduction of aerospace electronic devices and a preparation method thereof.The composite material is prepared from modified paraffin, modified polyethylene glycol, modified pyroxene powder, modified graphene and heat-conducting fiber. Through nanometer confinement and carbon quantum dot grafting, by adding modified polyethylene glycol, a dynamic cross-linked network is formed, high latent heat and zero leakage are achieved, by adding modified pyroxene powder, the surface hydroxyl density is increased, the interface shear strength is improved, the coating provides an additional heat conduction path, and the heat conduction coefficient of single particles is improved; the heat conductivity coefficient and saturation magnetization are improved, the magnetic field induced orientation arrangement efficiency is improved, graphene / fiber three-dimensional ordered distribution is achieved through magnetic field-shearing cooperation, the heat conductivity of the material is remarkably improved, the phase change energy storage capacity of the phase material is combined with the high heat conductivity of the solid-phase filler, and efficient heat dissipation is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of phase change materials, and in particular relates to a semi-solid phase change composite material for thermal conductivity of aerospace electronic devices and a preparation method thereof. Background Art

[0002] When aerospace electronic devices operate at high power density, they generate a large amount of heat. If the heat cannot be dissipated in time, the device performance will be degraded or even fail.

[0003] Traditional thermally conductive materials, such as metals or ceramic-based composites, suffer from issues such as heavy weight and mismatched thermal expansion coefficients. Phase change materials are widely used in thermal management due to their high latent heat storage capacity, but their thermal conductivity is poor. Therefore, developing composite materials that combine high thermal conductivity with phase change energy storage is of great significance. Summary of the Invention

[0004] The present invention provides a semi-solid phase change composite material for thermal conductivity of aerospace electronic devices, aiming to solve the above-mentioned problems.

[0005] The present invention is achieved as follows: a semi-solid phase change composite material for thermal conductivity of aerospace electronic devices includes the following raw materials in parts by weight: 50-60 parts of modified paraffin wax, 30-40 parts of modified polyethylene glycol, 5-10 parts of modified pyroxene powder, 10-20 parts of modified graphene, and 1-5 parts of thermal conductive fiber.

[0006] Preferably, the following raw materials are included in parts by weight: 52-58 parts of modified paraffin wax, 33-37 parts of modified polyethylene glycol, 6-9 parts of modified pyroxene powder, 12-17 parts of modified graphene, and 2-4 parts of thermal conductive fiber.

[0007] Preferably, the following raw materials are included in parts by weight: 55 parts of modified paraffin wax, 35 parts of modified polyethylene glycol, 7.5 parts of modified pyroxene powder, 15 parts of modified graphene, and 3 parts of thermal conductive fiber.

[0008] Preferably, the preparation method of the modified paraffin wax is as follows: paraffin wax and mesoporous alumina (optional pore diameter 10-15 nm, pore volume 1.2-1.5 cm³ / g) are mixed in a mass ratio of 3-5:1, heated to 80-90°C under vacuum conditions of -0.3 to -0.1 MPa, and kept warm for 2-3 hours to allow the paraffin wax to penetrate into the mesoporous structure to obtain an intermediate product, carbon quantum dots (optional particle size 2-5 nm, containing -COOH on the surface) and the intermediate product are evenly mixed in a mass ratio of 1:40-50, and irradiated in a microwave reactor (power can be set to 300-500 W, 60-75°C) for 15-20 minutes to obtain modified graphene, and the carbon quantum dots are grafted to the paraffin molecular chain through an esterification reaction, providing an electronic heat conduction channel through the carbon quantum dots to inhibit the phase change leakage of the paraffin wax.

[0009] Preferably, the modified polyethylene glycol is prepared by the following method: polyethylene glycol (Mn=6000) and 4-hydroxyphenylboric acid are dissolved in dimethylformamide at a molar ratio of 9-12:1; the mixture is reacted at 80-90°C under nitrogen protection for 5-6 hours to generate a dynamically reversible cross-linked network; then, an organized montmorillonite (cation exchange capacity 100 mmol / 100 g) is added, wherein the mass ratio of the organized montmorillonite to polyethylene glycol is 1:18-24; and ultrasonic dispersion (40-50 kHz, 300-400 W) is performed for 1-1.5 hours to insert the organized montmorillonite flakes between the polyethylene glycol segments, thereby improving the mechanical properties of the composite material.

[0010] Preferably, the preparation method of the modified pyroxene powder is as follows: natural pyroxene powder (particle size 1-3 μm) is immersed in a 5-10% HCl solution, stirred at 60-80°C for 1-2 hours to remove surface impurities; after washing to neutrality, it is calcined at 600-700°C for 1-1.5 hours to obtain pyroxene powder with a highly active surface; a mixed solution of sodium silicate (0.1-0.2 mol / L) and calcium chloride (0.15-0.3 mol / L) is prepared; activated pyroxene powder is added, and the mixture is reacted at pH = 9 and 60-70°C for 2-3 hours to form a nano-calcium silicate coating (thickness 50-100 nm) on the surface. The surface hydroxyl density of the pyroxene powder is increased through modification, the interfacial shear strength is increased, the coating provides an additional thermal conduction path, and the thermal conductivity of a single particle is increased.

[0011] Preferably, the preparation method of the modified graphene is as follows: 30-40 parts by weight of graphene oxide are dispersed in 10-15 times the weight of a mixed solution of ferric chloride and ferrous chloride (Fe 2＋ :Fe 3＋ =1:2); ammonia water was added to pH=10, and a hydrothermal reaction was carried out at 80-90°C for 3-5 hours to grow ferroferric oxide nanoparticles (particle size 10-20 nm) on the surface of the graphene oxide. The graphene oxide loaded with ferroferric oxide particles was placed in a hydrogen plasma reactor (power 200-300 W, H2 flow rate 50 sccm) for treatment for 30-40 minutes to obtain modified graphene, and the graphene oxide was reduced and partially oxidized to gamma-phase ferroferric oxide (retaining magnetism) simultaneously, thereby increasing the in-plane thermal conductivity and saturation magnetization of the graphene and improving the efficiency of magnetic field-induced orientation.

[0012] Preferably, the thermally conductive fibers include silicon carbide fibers.

[0013] The present invention also provides a method for preparing the aforementioned semi-solid phase change composite material for thermal conductivity of aerospace electronic devices, comprising the following steps: Weigh the raw materials according to the ratio; Mix the modified paraffin wax and modified polyethylene glycol in a vacuum kneader (speed 100-200 rpm) at 80-90°C for 30-50 minutes; Add modified pyroxene powder, modified graphene and thermal conductive fiber, and continue mixing for 15-25 minutes until the mixture is evenly dispersed; The mixture was transferred to a magnetic field-shear coupling device (magnetic field strength 0.8-1T, shear rate 500-600s -1 ) and treated at 80-90°C for 20-30 minutes to align the modified graphene along the magnetic field direction and distribute the thermal conductive fibers along the shear direction, significantly improving the heat flow conduction efficiency; After injection into the mold, the temperature was lowered to 55°C (semi-solid) at a rate of 5°C / min, pulse pressure was applied (peak value 30MPa, frequency 2Hz, pulse pressure curing to eliminate porosity) and the pressure was maintained for 10-15min. The mold was then demolded at 25°C to obtain a composite material with a three-dimensional thermal conductive network.

[0014] The difference from the prior art is that the embodiments of the present application have the following beneficial effects: The semi-solid phase change composite material for thermal conductivity of aerospace electronic devices provided by the present invention is added with modified paraffin, and through nano-confinement and carbon quantum dot grafting, the bottleneck of low thermal conductivity is broken through. By adding modified polyethylene glycol, a dynamic cross-linked network is formed to achieve high latent heat and zero leakage. By adding modified pyroxene powder, the surface hydroxyl density is increased, the interface shear strength is increased, the coating provides an additional thermal conduction path, and the thermal conductivity of single particles is increased. By adding modified graphene, the thermal conductivity and saturation magnetization intensity are increased, and the efficiency of magnetic field-induced orientation arrangement is improved. Through magnetic field-shear synergy, three-dimensional ordered distribution of graphene / fibers is achieved, and the thermal conductivity of the material is significantly improved. The phase change energy storage capacity of the phase material is combined with the high thermal conductivity of the solid phase filler to achieve efficient heat dissipation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention provides a flow chart of a method for preparing a semi-solid phase change composite material for thermal conductivity of aerospace electronic devices. DETAILED DESCRIPTION

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0017] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0018] Example 1 The embodiment of the present invention provides a semi-solid phase change composite material for thermal conductivity of aerospace electronic devices, comprising the following raw materials in parts by weight: 50 parts of modified paraffin wax, 30 parts of modified polyethylene glycol, 5 parts of modified pyroxene powder, 10 parts of modified graphene, and 1 part of silicon carbide fiber, such as Figure 1 As shown, the method for preparing the semi-solid phase change composite material for thermal conductivity of aerospace electronic devices comprises the following steps: Weigh the raw materials according to the ratio; Modified paraffin wax and modified polyethylene glycol were mixed in a vacuum kneader (speed 100 rpm) at 80 °C for 30 min; Add modified pyroxene powder, modified graphene and silicon carbide fiber, and continue mixing for 15 minutes until the mixture is evenly dispersed; The mixture was transferred to a magnetic field shear coupling device (magnetic field intensity 0.8 T, shear rate 500 s -1 ), treated at 80°C for 20 minutes, so that the modified graphene is arranged along the direction of the magnetic field and the thermal conductive fibers are distributed along the shear direction, which significantly improves the heat flow conduction efficiency; After injection into the mold, the temperature was lowered to 55°C (semi-solid) at a rate of 5°C / min, pulse pressure was applied (peak value 30MPa, frequency 2Hz, pulse pressure curing to eliminate porosity) and the pressure was maintained for 10 minutes. The mold was then demolded at 25°C to obtain a composite material with a three-dimensional thermal conductive network.

[0019] The preparation method of the modified paraffin is as follows: paraffin and mesoporous alumina (optional pore diameter of 10 nm, pore volume of 1.2 cm³ / g) are mixed in a mass ratio of 3:1, heated to 80°C under a vacuum condition of -0.3 MPa, and kept warm for 2 hours to allow the paraffin to penetrate into the mesoporous structure to obtain an intermediate product, carbon quantum dots (optional particle size of 2 nm, containing -COOH on the surface) and the intermediate product are evenly mixed in a mass ratio of 1:40, and irradiated in a microwave reactor (power can be set to 300 W, 60°C) for 15 minutes to obtain modified graphene, and the carbon quantum dots are grafted to the paraffin molecular chain through an esterification reaction, providing an electronic heat conduction channel through the carbon quantum dots to inhibit the phase change leakage of the paraffin.

[0020] Specifically, the preparation method of the modified polyethylene glycol is as follows: polyethylene glycol (Mn=6000) and 4-hydroxyphenylboric acid are dissolved in dimethylformamide at a molar ratio of 9:1; the mixture is reacted at 80°C under nitrogen protection for 5 hours to generate a dynamically reversible cross-linked network; then, organic montmorillonite (cation exchange capacity 100 mmol / 100 g) is added, wherein the mass ratio of the organic montmorillonite to polyethylene glycol is 1:18; and ultrasonic dispersion (40 kHz, 300 W) is performed for 1.5 hours to allow the organic montmorillonite flakes to be inserted between the polyethylene glycol segments, thereby improving the mechanical properties of the composite material.

[0021] In this embodiment, the preparation method of the modified pyroxene powder is as follows: natural pyroxene powder (particle size 1 μm) is immersed in a 5% HCl solution, stirred at 60°C for 1 hour to remove surface impurities; after washing to neutrality, it is calcined at 600°C for 1.5 hours to obtain pyroxene powder with a highly active surface; a mixed solution of sodium silicate (0.1 mol / L) and calcium chloride (0.15 mol / L) is prepared; activated pyroxene powder is added, and the mixture is reacted at pH = 9 and 60°C for 2 hours to generate a nano-calcium silicate coating (thickness 50 nm) on the surface. The surface hydroxyl density of the pyroxene powder is increased through modification, the interfacial shear strength is increased, the coating provides an additional thermal conduction path, and the thermal conductivity of a single particle is increased.

[0022] In a specific implementation, the preparation method of the modified graphene is as follows: 30 parts by weight of graphene oxide are dispersed in a mixed solution of 10 times the weight of ferric chloride and ferrous chloride (Fe 2＋ :Fe 3＋ =1:2); ammonia water was added to pH=10, and the mixture was hydrothermally reacted at 80℃ for 3h. Ferroferric oxide nanoparticles (particle size 10nm) grew on the surface of graphene oxide. The graphene oxide loaded with ferroferric oxide particles was placed in a hydrogen plasma reactor (power 200W, H2 flow rate 50sccm) for 30min to obtain modified graphene. The reduction of graphene oxide and partial oxidation of ferroferric oxide to gamma-phase ferric oxide (retaining magnetism) were simultaneously achieved, thereby increasing the in-plane thermal conductivity and saturation magnetization of graphene and improving the efficiency of magnetic field-induced orientation.

[0023] Example 2 The embodiment of the present invention provides a semi-solid phase change composite material for thermal conductivity of aerospace electronic devices, comprising the following raw materials in parts by weight: 52 parts of modified paraffin wax, 33 parts of modified polyethylene glycol, 6 parts of modified pyroxene powder, 12 parts of modified graphene, and 2 parts of silicon carbide fiber. Figure 1 As shown, the method for preparing the semi-solid phase change composite material for thermal conductivity of aerospace electronic devices comprises the following steps: Weigh the raw materials according to the ratio; Modified paraffin wax and modified polyethylene glycol were mixed in a vacuum kneader (speed 100 rpm) at 80 °C for 30 min; Add modified pyroxene powder, modified graphene and silicon carbide fiber, and continue mixing for 15 minutes until the mixture is evenly dispersed; The mixture was transferred to a magnetic field shear coupling device (magnetic field intensity 0.8T, shear rate 500s) and treated at 80°C for 20 minutes. This allowed the modified graphene to align along the magnetic field direction and the thermal conductive fibers to distribute along the shear direction, significantly improving the heat flow conduction efficiency. After injection into the mold, the temperature was lowered to 55°C (semi-solid) at a rate of 5°C / min, pulse pressure was applied (peak value 30MPa, frequency 2Hz, pulse pressure curing to eliminate porosity) and the pressure was maintained for 10 minutes. The mold was then demolded at 25°C to obtain a composite material with a three-dimensional thermal conductive network.

[0024] The preparation method of the modified paraffin is as follows: paraffin and mesoporous alumina (optional pore diameter of 10 nm, pore volume of 1.2 cm³ / g) are mixed in a mass ratio of 3:1, heated to 80°C under a vacuum condition of -0.3 MPa, and kept warm for 2 hours to allow the paraffin to penetrate into the mesoporous structure to obtain an intermediate product, carbon quantum dots (optional particle size of 2 nm, containing -COOH on the surface) and the intermediate product are evenly mixed in a mass ratio of 1:40, and irradiated in a microwave reactor (power can be set to 300 W, 60°C) for 15 minutes to obtain modified graphene, and the carbon quantum dots are grafted to the paraffin molecular chain through an esterification reaction, providing an electronic heat conduction channel through the carbon quantum dots to inhibit the phase change leakage of the paraffin.

[0025] Specifically, the preparation method of the modified polyethylene glycol is as follows: polyethylene glycol (Mn=6000) and 4-hydroxyphenylboric acid are dissolved in dimethylformamide at a molar ratio of 9:1; the mixture is reacted at 80°C under nitrogen protection for 5 hours to generate a dynamically reversible cross-linked network; then, organic montmorillonite (cation exchange capacity 100 mmol / 100 g) is added, wherein the mass ratio of the organic montmorillonite to polyethylene glycol is 1:18; and ultrasonic dispersion (40 kHz, 300 W) is performed for 1.5 hours to allow the organic montmorillonite flakes to be inserted between the polyethylene glycol segments, thereby improving the mechanical properties of the composite material.

[0026] In this embodiment, the preparation method of the modified pyroxene powder is as follows: natural pyroxene powder (particle size 1 μm) is immersed in a 5% HCl solution, stirred at 60°C for 1 hour to remove surface impurities; after washing to neutrality, it is calcined at 600°C for 1.5 hours to obtain pyroxene powder with a highly active surface; a mixed solution of sodium silicate (0.1 mol / L) and calcium chloride (0.15 mol / L) is prepared; activated pyroxene powder is added, and the mixture is reacted at pH = 9 and 60°C for 2 hours to generate a nano-calcium silicate coating (thickness 50 nm) on the surface. The surface hydroxyl density of the pyroxene powder is increased through modification, the interfacial shear strength is increased, the coating provides an additional thermal conduction path, and the thermal conductivity of a single particle is increased.

[0027] In a specific implementation, the preparation method of the modified graphene is as follows: 30 parts by weight of graphene oxide are dispersed in a mixed solution of 10 times the weight of ferric chloride and ferrous chloride (Fe 2＋ :Fe 3＋ =1:2); ammonia water was added to pH=10, and the mixture was hydrothermally reacted at 80℃ for 3h. Ferroferric oxide nanoparticles (particle size 10nm) grew on the surface of graphene oxide. The graphene oxide loaded with ferroferric oxide particles was placed in a hydrogen plasma reactor (power 200W, H2 flow rate 50sccm) for 30min to obtain modified graphene. The reduction of graphene oxide and partial oxidation of ferroferric oxide to gamma-phase ferric oxide (retaining magnetism) were simultaneously achieved, thereby increasing the in-plane thermal conductivity and saturation magnetization of graphene and improving the efficiency of magnetic field-induced orientation.

[0028] Example 3 The embodiment of the present invention provides a semi-solid phase change composite material for thermal conductivity of aerospace electronic devices, comprising the following raw materials in parts by weight: 55 parts of modified paraffin wax, 35 parts of modified polyethylene glycol, 7.5 parts of modified pyroxene powder, 15 parts of modified graphene, and 3 parts of silicon carbide fiber. Figure 1 As shown, the method for preparing the semi-solid phase change composite material for thermal conductivity of aerospace electronic devices comprises the following steps: Weigh the raw materials according to the ratio; Modified paraffin wax and modified polyethylene glycol were mixed in a vacuum kneader (speed 150 rpm) at 85 °C for 40 min; Add modified pyroxene powder, modified graphene and silicon carbide fiber, and continue mixing for 20 minutes until the mixture is evenly dispersed; The mixture was transferred to a magnetic field-shear coupling device (magnetic field intensity 0.9 T, shear rate 550 s -1 ), treated at 85°C for 25 minutes, so that the modified graphene is aligned along the magnetic field direction and the thermal conductive fibers are distributed along the shear direction, significantly improving the heat flow conduction efficiency; After injection into the mold, the temperature was lowered to 55°C (semi-solid) at a rate of 5°C / min, and pulse pressure (peak value 30MPa, frequency 2Hz, pulse pressure curing to eliminate porosity) was applied and maintained at pressure for 12.5min. The mold was then demolded at 25°C to obtain a composite material with a three-dimensional thermal conductive network.

[0029] The preparation method of the modified paraffin is as follows: paraffin and mesoporous alumina (optional pore diameter of 12 nm, pore volume of 1.3 cm³ / g) are mixed in a mass ratio of 4:1, heated to 85°C under vacuum conditions of -0.2 MPa, and kept warm for 2.5 hours to allow the paraffin to penetrate the mesoporous structure to obtain an intermediate product, carbon quantum dots (optional particle size of 3 nm, containing -COOH on the surface) and the intermediate product are evenly mixed in a mass ratio of 1:45, and irradiated in a microwave reactor (power can be set to 400 W, 68°C) for 17.5 minutes to obtain modified graphene, and the carbon quantum dots are grafted to the paraffin molecular chain through an esterification reaction, providing an electronic heat conduction channel through the carbon quantum dots to inhibit the phase change leakage of the paraffin.

[0030] Specifically, the preparation method of the modified polyethylene glycol is as follows: polyethylene glycol (Mn=6000) and 4-hydroxyphenylboric acid are dissolved in dimethylformamide at a molar ratio of 10:1; the mixture is reacted at 85°C under nitrogen protection for 5.5 hours to generate a dynamically reversible cross-linked network; then, organic montmorillonite (cation exchange capacity 100 mmol / 100 g) is added, wherein the mass ratio of the organic montmorillonite to polyethylene glycol is 1:21; ultrasonic dispersion (45 kHz, 350 W) is performed for 1.25 hours to allow the organic montmorillonite flakes to be inserted between the polyethylene glycol segments, thereby improving the mechanical properties of the composite material.

[0031] In this embodiment, the preparation method of the modified pyroxene powder is as follows: natural pyroxene powder (particle size 2 μm) is immersed in 7.5% HCl solution, stirred at 70°C for 1.5 hours to remove surface impurities; after washing to neutrality, it is calcined at 650°C for 1.25 hours to obtain pyroxene powder with a highly active surface; a mixed solution of sodium silicate (0.15 mol / L) and calcium chloride (0.22 mol / L) is prepared; activated pyroxene powder is added, and the mixture is reacted at pH = 9 and 65°C for 2.5 hours to generate a nano-calcium silicate coating (thickness 75 nm) on the surface. The surface hydroxyl density of the pyroxene powder is increased through modification, the interfacial shear strength is increased, the coating provides an additional thermal conduction path, and the thermal conductivity of a single particle is increased.

[0032] In a specific implementation, the preparation method of the modified graphene is as follows: 30-40 parts by weight of graphene oxide are dispersed in a mixed solution of 12.5 times the weight of ferric chloride and ferrous chloride (Fe 2＋ :Fe 3＋=1:2); ammonia water was added to pH=10, and the mixture was hydrothermally reacted at 85℃ for 4h. Ferroferric oxide nanoparticles (particle size 15nm) grew on the surface of graphene oxide. The graphene oxide loaded with ferroferric oxide particles was placed in a hydrogen plasma reactor (power 250W, H2 flow rate 50sccm) for 35min to obtain modified graphene. The reduction of graphene oxide and partial oxidation of ferroferric oxide to gamma-phase ferric oxide (retaining magnetism) were simultaneously achieved, thereby increasing the in-plane thermal conductivity and saturation magnetization of graphene and improving the efficiency of magnetic field-induced orientation.

[0033] Example 4 The embodiment of the present invention provides a semi-solid phase change composite material for thermal conductivity of aerospace electronic devices, comprising the following raw materials in parts by weight: 58 parts of modified paraffin wax, 37 parts of modified polyethylene glycol, 9 parts of modified pyroxene powder, 17 parts of modified graphene, and 4 parts of silicon carbide fiber. Figure 1 As shown, the method for preparing the semi-solid phase change composite material for thermal conductivity of aerospace electronic devices comprises the following steps: Weigh the raw materials according to the ratio; Modified paraffin wax and modified polyethylene glycol were mixed in a vacuum kneader (speed 200 rpm) at 90 °C for 50 min; Add modified pyroxene powder, modified graphene and silicon carbide fiber, and continue mixing for 25 minutes until the mixture is evenly dispersed; The mixture was transferred to a magnetic field shear coupling device (magnetic field intensity 0.1 T, shear rate 600 s -1 ), treated at 90°C for 30 minutes, so that the modified graphene is arranged along the direction of the magnetic field and the thermal conductive fibers are distributed along the shear direction, which significantly improves the heat flow conduction efficiency; After injection into the mold, the temperature was lowered to 55°C (semi-solid) at a rate of 5°C / min, pulse pressure was applied (peak value 30MPa, frequency 2Hz, pulse pressure curing to eliminate porosity) and the pressure was maintained for 15 minutes. The mold was then demolded at 25°C to obtain a composite material with a three-dimensional thermal conductive network.

[0034] The preparation method of the modified paraffin is as follows: paraffin and mesoporous alumina (optional pore diameter of 15 nm, pore volume of 1.5 cm³ / g) are mixed in a mass ratio of 5:1, heated to 90°C under vacuum conditions of -0.1 MPa, and kept warm for 3 hours to allow the paraffin to penetrate the mesoporous structure to obtain an intermediate product, carbon quantum dots (optional particle size of 5 nm, containing -COOH on the surface) and the intermediate product are evenly mixed in a mass ratio of 1:50, and irradiated in a microwave reactor (power can be set to 500 W, 75°C) for 20 minutes to obtain modified graphene, and the carbon quantum dots are grafted to the paraffin molecular chain through an esterification reaction, providing an electronic heat conduction channel through the carbon quantum dots to inhibit the phase change leakage of the paraffin.

[0035] Specifically, the preparation method of the modified polyethylene glycol is as follows: polyethylene glycol (Mn=6000) and hydroxyphenylboric acid are dissolved in dimethylformamide at a molar ratio of 12:1; the mixture is reacted at 90°C under nitrogen protection for 6 hours to generate a dynamically reversible cross-linked network; then, organic montmorillonite (cation exchange capacity 100 mmol / 100 g) is added, wherein the mass ratio of the organic montmorillonite to polyethylene glycol is 1:24; and ultrasonic dispersion (50 kHz, 400 W) is performed for 1.5 hours to allow the organic montmorillonite flakes to be inserted between the polyethylene glycol segments, thereby improving the mechanical properties of the composite material.

[0036] In this embodiment, the preparation method of the modified pyroxene powder is as follows: natural pyroxene powder (particle size 3 μm) is immersed in a 10% HCl solution, stirred at 80°C for 2 hours to remove surface impurities; after washing to neutrality, it is calcined at 700°C for 1.5 hours to obtain pyroxene powder with a highly active surface; a mixed solution of sodium silicate (0.2 mol / L) and calcium chloride (0.3 mol / L) is prepared; activated pyroxene powder is added, and the mixture is reacted at pH = 9 and 70°C for 3 hours to generate a nano-calcium silicate coating (thickness 100 nm) on the surface. The modification increases the surface hydroxyl density of the pyroxene powder, improves the interfacial shear strength, provides an additional thermal conduction path, and improves the thermal conductivity of a single particle.

[0037] In a specific implementation, the preparation method of the modified graphene is as follows: 40 parts by weight of graphene oxide are dispersed in a mixed solution of 15 times the weight of ferric chloride and ferrous chloride (Fe 2＋ :Fe 3＋ =1:2); ammonia water was added to pH=10, and the mixture was hydrothermally reacted at 90℃ for 5h. Ferroferric oxide nanoparticles (particle size 20nm) grew on the surface of graphene oxide. The graphene oxide loaded with ferroferric oxide particles was placed in a hydrogen plasma reactor (power 300W, H2 flow rate 50sccm) for 40min to obtain modified graphene. The reduction of graphene oxide and partial oxidation of ferroferric oxide to gamma-phase ferric oxide (retaining magnetism) were simultaneously achieved, thereby increasing the in-plane thermal conductivity and saturation magnetization of graphene and improving the efficiency of magnetic field-induced orientation.

[0038] Example 5 The embodiment of the present invention provides a semi-solid phase change composite material for thermal conductivity of aerospace electronic devices, comprising the following raw materials in parts by weight: 60 parts of modified paraffin wax, 40 parts of modified polyethylene glycol, 10 parts of modified pyroxene powder, 20 parts of modified graphene, and 5 parts of silicon carbide fiber. Figure 1 As shown, the method for preparing the semi-solid phase change composite material for thermal conductivity of aerospace electronic devices comprises the following steps: Weigh the raw materials according to the ratio; Modified paraffin wax and modified polyethylene glycol were mixed in a vacuum kneader (speed 200 rpm) at 90 °C for 50 min; Add modified pyroxene powder, modified graphene and silicon carbide fiber, and continue mixing for 25 minutes until the mixture is evenly dispersed; The mixture was transferred to a magnetic field shear coupling device (magnetic field intensity 0.1 T, shear rate 600 s -1 ), treated at 90°C for 30 minutes, so that the modified graphene is arranged along the direction of the magnetic field and the thermal conductive fibers are distributed along the shear direction, which significantly improves the heat flow conduction efficiency; After injection into the mold, the temperature was lowered to 55°C (semi-solid) at a rate of 5°C / min, pulse pressure was applied (peak value 30MPa, frequency 2Hz, pulse pressure curing to eliminate porosity) and the pressure was maintained for 15 minutes. The mold was then demolded at 25°C to obtain a composite material with a three-dimensional thermal conductive network.

[0039] The preparation method of the modified paraffin is as follows: paraffin and mesoporous alumina (optional pore diameter of 15 nm, pore volume of 1.5 cm³ / g) are mixed in a mass ratio of 5:1, heated to 90°C under vacuum conditions of -0.1 MPa, and kept warm for 3 hours to allow the paraffin to penetrate the mesoporous structure to obtain an intermediate product, carbon quantum dots (optional particle size of 5 nm, containing -COOH on the surface) and the intermediate product are evenly mixed in a mass ratio of 1:50, and irradiated in a microwave reactor (power can be set to 500 W, 75°C) for 20 minutes to obtain modified graphene, and the carbon quantum dots are grafted to the paraffin molecular chain through an esterification reaction, providing an electronic heat conduction channel through the carbon quantum dots to inhibit the phase change leakage of the paraffin.

[0040] Specifically, the preparation method of the modified polyethylene glycol is as follows: polyethylene glycol (Mn=6000) and hydroxyphenylboric acid are dissolved in dimethylformamide at a molar ratio of 12:1; the mixture is reacted at 90°C under nitrogen protection for 6 hours to generate a dynamically reversible cross-linked network; then, organic montmorillonite (cation exchange capacity 100 mmol / 100 g) is added, wherein the mass ratio of the organic montmorillonite to polyethylene glycol is 1:24; and ultrasonic dispersion (50 kHz, 400 W) is performed for 1.5 hours to allow the organic montmorillonite flakes to be inserted between the polyethylene glycol segments, thereby improving the mechanical properties of the composite material.

[0041] In this embodiment, the preparation method of the modified pyroxene powder is as follows: natural pyroxene powder (particle size 3 μm) is immersed in a 10% HCl solution, stirred at 80°C for 2 hours to remove surface impurities; after washing to neutrality, it is calcined at 700°C for 1.5 hours to obtain pyroxene powder with a highly active surface; a mixed solution of sodium silicate (0.2 mol / L) and calcium chloride (0.3 mol / L) is prepared; activated pyroxene powder is added, and the mixture is reacted at pH = 9 and 70°C for 3 hours to generate a nano-calcium silicate coating (thickness 100 nm) on the surface. The modification increases the surface hydroxyl density of the pyroxene powder, improves the interfacial shear strength, provides an additional thermal conduction path, and improves the thermal conductivity of a single particle.

[0042] In a specific implementation, the preparation method of the modified graphene is as follows: 40 parts by weight of graphene oxide are dispersed in a mixed solution of 15 times the weight of ferric chloride and ferrous chloride (Fe 2＋ :Fe 3＋ =1:2); ammonia water was added to pH=10, and the mixture was hydrothermally reacted at 90℃ for 5h. Ferroferric oxide nanoparticles (particle size 20nm) grew on the surface of graphene oxide. The graphene oxide loaded with ferroferric oxide particles was placed in a hydrogen plasma reactor (power 300W, H2 flow rate 50sccm) for 40min to obtain modified graphene. The reduction of graphene oxide and partial oxidation of ferroferric oxide to gamma-phase ferric oxide (retaining magnetism) were simultaneously achieved, thereby increasing the in-plane thermal conductivity and saturation magnetization of graphene and improving the efficiency of magnetic field-induced orientation.

[0043] Comparative Example 1: The difference from Example 3 is that the modified paraffin wax is replaced by ordinary paraffin wax.

[0044] Comparative Example 2: The difference from Example 3 is that the modified polyethylene glycol is replaced by ordinary polyethylene glycol.

[0045] Comparative Example 3: The difference from Example 3 is that the modified pyroxene powder is replaced by ordinary pyroxene powder.

[0046] Comparative Example 4: The difference from Example 3 is that the modified graphene is replaced by ordinary graphene.

[0047] Comparative Example 5: The difference from Example 3 is that the modified paraffin is replaced by ordinary paraffin, the modified polyethylene glycol is replaced by ordinary polyethylene glycol, the modified pyroxene powder is replaced by ordinary pyroxene powder, and the modified graphene is replaced by ordinary graphene.

[0048] Comparative Example 6: The difference from Example 3 is that the mixture is not transferred to the magnetic field shear coupling device.

[0049] Performance Testing The composite materials of Examples 1-5 and Comparative Examples 1-6 were subjected to performance tests. The test results are shown in Table 1 below: Table 1 Test results of composite material phase change latent heat and thermal conductivity

[0050] From the above results, it can be seen that the composite material of the present invention has good phase change latent heat and thermal conductivity. By adding modified paraffin, modified polyethylene glycol, modified pyroxene powder and modified graphene, it has a synergistic effect, which can further improve the thermal conductivity of the composite material while ensuring good phase change latent heat performance.

[0051] It should be noted that, for the sake of simplicity, the aforementioned embodiments are described as a series of action combinations. However, those skilled in the art should be aware that the present invention is not limited by the order of the actions described, because according to the present invention, certain steps may be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in this specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present invention.

[0052] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the invention. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on these embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field can still combine, add, delete or make other adjustments to the features in the various embodiments of the present invention according to the circumstances without conflict, without making creative work, so as to obtain different other technical solutions that do not deviate from the concept of the present invention in essence, and these technical solutions also fall within the scope of protection of the present invention.

Claims

1. A semi-solid phase change composite material for thermal conductivity of aerospace electronic devices, characterized in that: The invention comprises the following raw materials in parts by weight: 50-60 parts of modified paraffin wax, 30-40 parts of modified polyethylene glycol, 5-10 parts of modified pyroxene powder, 10-20 parts of modified graphene, and 1-5 parts of thermal conductive fiber.

2. The semi-solid phase change composite material for thermal conductivity of aerospace electronic devices according to claim 1, characterized in that: The invention comprises the following raw materials in parts by weight: 52-58 parts of modified paraffin wax, 33-37 parts of modified polyethylene glycol, 6-9 parts of modified pyroxene powder, 12-17 parts of modified graphene, and 2-4 parts of thermal conductive fiber.

3. The semi-solid phase change composite material for thermal conductivity of aerospace electronic components according to claim 2, characterized in that: The invention comprises the following raw materials in parts by weight: 55 parts of modified paraffin wax, 35 parts of modified polyethylene glycol, 7.5 parts of modified pyroxene powder, 15 parts of modified graphene, and 3 parts of thermal conductive fiber.

4. The semi-solid phase change composite material for thermal conductivity of aerospace electronic components according to claim 1, characterized in that: The preparation method of the modified paraffin wax is as follows: Paraffin wax and mesoporous alumina are mixed in a mass ratio of 3-5:1, heated to 80-90°C under vacuum conditions of -0.3 to -0.1 MPa, and kept warm for 2-3 hours to allow the paraffin wax to penetrate into the mesoporous structure to obtain an intermediate product. Carbon quantum dots and the intermediate product are evenly mixed in a mass ratio of 1:40-50, and irradiated in a microwave reactor for 15-20 minutes to obtain modified graphene.

5. The semi-solid phase change composite material for thermal conductivity of aerospace electronic components according to claim 1, characterized in that: The preparation method of the modified polyethylene glycol is as follows: Polyethylene glycol and 4-hydroxyphenylboric acid are dissolved in dimethylformamide at a molar ratio of 9-12:1; the mixture is reacted at 80-90°C under nitrogen protection for 5-6 hours, and then the organic montmorillonite is added, wherein the mass ratio of the organic montmorillonite to polyethylene glycol is 1:18-24; and the mixture is ultrasonically dispersed for 1-1.5 hours to obtain the modified polyethylene glycol.

6. The semi-solid phase change composite material for thermal conductivity of aerospace electronic components according to claim 1, characterized in that: The preparation method of the modified pyroxene powder is as follows: Immerse natural pyroxene powder in 5-10% HCl solution, stir at 60-80℃ for 1-2 hours to remove surface impurities; wash to neutrality, and calcine at 600-700℃ for 1-1.5 hours to obtain pyroxene powder with a highly active surface; prepare a mixed solution of sodium silicate and calcium chloride; Add activated pyroxene powder and react at pH = 9 and 60-70°C for 2-3 hours to obtain modified pyroxene powder.

7. The semi-solid phase change composite material for thermal conductivity of aerospace electronic components according to claim 1, characterized in that: The preparation method of the modified graphene is as follows: The method comprises dispersing 30-40 parts by weight of graphene oxide in a mixed solution of ferric chloride and ferrous chloride of 10-15 times its weight; adding ammonia water to a pH of 10, and performing a hydrothermal reaction at 80-90° C. for 3-5 hours to grow ferrosoferric oxide nanoparticles on the surface of the graphene oxide; and placing the graphene oxide loaded with ferrosoferric oxide particles in a hydrogen plasma reactor for 30-40 minutes to obtain modified graphene.

8. The semi-solid phase change composite material for thermal conductivity of aerospace electronic components according to claim 1, wherein: The thermally conductive fibers include silicon carbide fibers.

9. The method for preparing a semi-solid phase change composite material for thermal conductivity of aerospace electronic devices according to any one of claims 1 to 8, characterized in that: The steps include: Weigh the raw materials according to the ratio; Mix the modified paraffin wax and modified polyethylene glycol in a vacuum kneader at 80-90°C for 30-50 minutes; Add modified pyroxene powder, modified graphene and thermal conductive fiber, and continue mixing for 15-25 minutes until the mixture is evenly dispersed; The mixture was transferred to a magnetic field-shear coupling device and treated at 80-90°C for 20-30 min; After injection into the mold, the temperature was lowered to 55°C at a rate of 5°C / min, pulse pressure was applied and maintained for 10-15 minutes, and the mold was demoulded at 25°C to obtain a composite material.

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