Oxide-enhanced fluorocoolant and method of making same
By modifying the surface of alumina with fluorosilane coupling agents, the problem of poor interfacial compatibility between alumina and fluorine coolant is solved, achieving high stable dispersion and improved thermal conductivity of alumina in fluorine coolant, making it suitable for high-end heat dissipation and cooling scenarios.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUJIAN INST OF RES ON THE STRUCTURE OF MATTER CHINESE ACAD OF SCI
- Filing Date
- 2026-02-06
- Publication Date
- 2026-06-09
AI Technical Summary
The poor interfacial compatibility between alumina and fluorine coolant, coupled with the insufficient compatibility of existing modifiers, leads to alumina particle agglomeration, sedimentation, and stratification, affecting thermal conductivity and normal equipment operation.
Alumina is surface modified using fluorosilane coupling agents. Covalent bonds are formed on the alumina surface through silane hydrolysis in-situ coating technology. The perfluoroalkyl chains are compatible with fluorine coolant, thus improving interfacial compatibility.
It significantly improves the dispersion stability and thermal conductivity of alumina in fluorine coolant, increasing the thermal conductivity of the coolant system by 20-40%, while retaining the insulation and high and low temperature resistance of fluorine coolant, making it suitable for cooling electronic devices and precision equipment.
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Abstract
Description
Technical Field
[0001] This application relates to an oxide-enhanced fluorine coolant and its preparation method, belonging to the field of heat dissipation. Background Technology
[0002] Fluorinated coolants (such as perfluoropolyethers, hydrofluoroethers, and perfluoroalkanes) are widely used in high-end electronic heat dissipation and aerospace precision equipment cooling due to their excellent thermal transfer, electrical insulation, and material compatibility. Alumina (Al₂O₃), as a low-cost, high-thermal-conductivity inorganic filler, is often used to prepare fluorinated coolant-based thermally conductive pastes to further improve the thermal conductivity of fluorinated coolants.
[0003] However, the surface of alumina and other oxide thermally conductive fillers is rich in hydroxyl groups, exhibiting strong hydrophilic polarity, while fluorinated coolant is a hydrophobic nonpolar medium. The two have extremely poor interfacial compatibility, and direct mixing easily leads to problems such as alumina particle agglomeration, sedimentation, and stratification. This not only fails to allow alumina to exert its thermal conductivity-enhancing effect but may also block heat dissipation channels and affect the normal operation of equipment. To solve these problems, surface modification technology is needed to treat alumina and construct an interfacial bridge connecting the alumina and fluorinated coolant.
[0004] In existing technologies, reagents used for surface modification of inorganic fillers mainly include silane coupling agents, titanate coupling agents, and surfactants. However, the compatibility groups of common silane coupling agents (such as KH-550 and KH-560) are polar groups such as amino and epoxy groups, which are completely incompatible with fluorinated coolants, and modification actually exacerbates agglomeration. Hydrocarbon coupling agents (such as stearic acid and common titanates) have hydrophobic hydrocarbon chains, which have extremely poor compatibility with fluorocarbon chains and cannot achieve long-term dispersion. Although some fluorinated surfactants can improve compatibility, they are mostly physically adsorbed, with weak anchoring force, and are prone to desorption under high temperature and long-term use, resulting in insufficient stability. Therefore, there is an urgent need to develop a targeted, stable modification method for alumina interface modification that is compatible with fluorinated coolant systems. Summary of the Invention
[0005] To address the problems of poor interfacial compatibility between alumina and fluorine coolant and insufficient compatibility of existing modifiers in the prior art, this invention provides an interfacial modification method for alumina and fluorine coolant. By screening specific types of modifiers and optimizing process parameters, molecular-level compatibility between alumina and fluorine coolant is achieved, thereby improving the dispersion stability of modified alumina in fluorine coolant and the overall performance of the thermally conductive slurry.
[0006] According to the first aspect of this application, an oxide-enhanced fluorine coolant is provided.
[0007] An oxide-reinforced fluorine coolant, the oxide-reinforced fluorine coolant comprising a fluorine coolant and a modified oxide; The modified oxide is an oxide modified with a fluorosilane coupling agent.
[0008] Optionally, the fluorinated coolant is selected from at least one of perfluoropolyether (PFPE), hydrofluoroether (HFE), perfluoroalkane (PFC), and high-viscosity fluorinated oil.
[0009] Optionally, the fluorosilane coupling agent is selected from at least one of heptadecafluorodecyltriethoxysilane (FAS-17), tridecafluorooctyltrimethoxysilane (FAS-13), and trifluoropropyldimethoxysilane.
[0010] When the fluorinated coolant is a perfluoropolyether or a hydrofluoroether, the fluorosilane coupling agent is selected from tridecylfluorooctyltrimethoxysilane (FAS-13) or trifluoropropyldimethoxysilane. When the fluorinated coolant is a perfluoroalkane or a high-viscosity fluorinated oil, the fluorosilane coupling agent is selected as heptadecafluorodecyltrimethoxysilane (FAS-17).
[0011] Optionally, the perfluoropolyether is from the DuPont Krytox® series or the Solvay Fomblin® series, and the hydrofluoroether is from the 3MNovec™ series.
[0012] Optionally, the oxide is selected from at least one of aluminum oxide, magnesium oxide, and silicon dioxide.
[0013] Optionally, the oxide is a nano-sized oxide with a particle size range of 50~200nm.
[0014] Optionally, the alumina is nano-sized alumina with a particle size range of 50~200nm.
[0015] Optionally, the alumina is α-Al₂O₃. It has a higher thermal conductivity and better chemical stability.
[0016] Optionally, the modified oxide has a mass fraction of 5-15%.
[0017] According to a second aspect of this application, a method for preparing an oxide-reinforced fluorine coolant is provided. This method uses a fluorosilane coupling agent as a modifier and achieves directional modification of the alumina surface through silane hydrolysis in-situ coating technology. The alkoxysilane groups of the fluorosilane coupling agent form covalent bonds with the hydroxyl groups on the alumina surface, and the perfluoroalkyl chains are compatible with the fluorine coolant, fundamentally solving the problem of poor interfacial compatibility. This interfacial modification method is process-controllable, simple to operate, and suitable for industrial production. The modified alumina exhibits excellent dispersion stability in the fluorine coolant, and the thermal conductivity of the prepared fluorine coolant is increased by 20-40%, while retaining the original excellent properties of the fluorine coolant. It can be widely used in scenarios such as heat dissipation of electronic devices and cooling of precision equipment.
[0018] The preparation method of the oxide-reinforced fluorine coolant described above includes: S1, fluorosilane hydrolysis The fluorosilane coupling agent was dissolved in a mixed solvent of ethanol and isopropanol, water was added, the pH value of the system was adjusted, and the mixture was stirred and hydrolyzed to obtain the fluorosilane sol precursor liquid. S2, Interface Modification Reaction The oxide powder was added to the fluorosilane sol precursor liquid, stirred and reacted, and then ultrasonically dispersed. S3, Post-processing The reaction mixture was separated, dried, cooled, and then ground to obtain surface-modified oxide powder. S4, Mixed Dispersion The surface-modified oxide powder was added to the fluorine coolant, and then ultrasonically dispersed and sheared to obtain the oxide-reinforced fluorine coolant.
[0019] Optionally, in step S1, the mass percentage of the components in the system is: Fluorosilane coupling agent: 0.5~5 parts; Ethanol: 40-55 parts; Isopropanol: 1-5 parts; Water: 40-55 parts.
[0020] Optionally, in step S1, acetic acid is used to adjust the pH of the system to a pH of 3.4 to 4.0.
[0021] Optionally, in step S1, the mixture is continuously stirred at room temperature for 12 to 48 hours.
[0022] Optionally, in step S2, 80-120 parts of oxide powder are added to 100 parts by mass of fluorosilane sol precursor liquid.
[0023] Optionally, in step S2, the mixture is placed in a constant temperature water bath at 60~70℃ and stirred for 1.5~2.5h, during which it is ultrasonically dispersed for 10~15min every 20~40min.
[0024] Optionally, in step S3, the particle size of the surface-modified oxide powder is 0.1 ~ 10 μm.
[0025] Optionally, in step S4, the mass fraction of the surface-modified oxide powder is 5-15%.
[0026] Optionally, in step S4, the ultrasonic dispersion time is 20-30 min; the shear dispersion rotation speed is 8000-10000 r / min, and the time is 15-20 min.
[0027] The beneficial effects that this application can produce include: (1) High stability of fluorine coolant system enhanced by oxide: Based on the molecular group characteristics of alumina and fluorine coolant, the present invention selects fluorosilane coupling agent to impart hydrophobic properties to the surface of alumina, forming covalent bonds at the interface of alumina and fluorine coolant, effectively improving the stability of the coolant system, with no obvious sedimentation or stratification after standing; significantly improving the cooling efficiency and performance of the coolant system.
[0028] (2) Low interfacial thermal resistance between oxide and fluorine coolant: The hydrolysis of fluorosilane coupling agent forms covalent bonds at the interface between alumina and fluorine coolant, which significantly reduces the interfacial thermal resistance between oxide and fluorine coolant. The thermal conductivity and cooling effect of the coolant system are improved by 20-40% compared with the unmodified system. At the same time, the original high insulation, chemical inertness and high and low temperature resistance of fluorine coolant are fully preserved, which can be directly adapted to high-end scenarios such as heat dissipation of electronic devices and cooling of precision equipment.
[0029] (3) Mass production process: The technology of surface modification of alumina by hydrolysis of fluorosilane has significant advantages in mass production compared with PVD, CVD and hydrothermal reaction technologies. Detailed Implementation
[0030] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0031] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.
[0032] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.
[0033] Example 1 (1) Preparation of fluorosilane sol precursor solution: Mix 55g ethanol and 5g isopropanol, add acetic acid to adjust the pH to 4.0, add 2g FAS-13 fluorosilane coupling agent and stir evenly, adjust the pH of water to 4.0 with acetic acid, keep stirring and gradually add 40g water (pH 4.0), stir continuously at room temperature for 12h to prepare fluorosilane sol precursor solution for later use.
[0034] (2) Surface modification of oxides: 100g of α-Al2O3 powder with a particle size of 100nm was added to 100g of fluorosilane sol precursor liquid and stirred in a constant temperature water bath at 60℃ for 1.5h. During the reaction, the mixture was ultrasonically dispersed for 10min every 20min. The mixture after the reaction was centrifuged, dried in an oven, cooled and then ground in a ball mill to obtain surface-modified oxide powder with an average particle size of 5μm.
[0035] (3) Preparation of fluorinated coolant: Modified alumina powder was added to perfluoropolyether (DuPont Krytox® 100) at a mass fraction of 10%. It was first ultrasonically dispersed for 25 min, and then sheared and dispersed for 18 min at a speed of 9000 r / min using a high-speed shear disperser to obtain a uniform and stable alumina / perfluoropolyether coolant.
[0036] Example 2 Except for replacing the nano-α-Al2O3 powder with nano-magnesium oxide powder, everything else is the same as in Example 1.
[0037] Example 3 Except for replacing the nano-α-Al2O3 powder with nano-silica powder, everything else is the same as in Example 1.
[0038] Example 4 Except for replacing 2g of FAS-13 fluorosilane coupling agent with 4g of FAS-13 fluorosilane coupling agent, everything else is the same as in Example 1.
[0039] Example 5 Except for replacing 10% of the modified alumina powder with 5% by mass, everything else is the same as in Example 1.
[0040] Example 6 Except for replacing 10% of the modified alumina powder with 15% by mass, everything else is the same as in Example 1.
[0041] Example 7 Except for replacing the FAS-13 fluorosilane coupling agent with trifluoropropyldimethoxysilane, everything else is the same as in Example 1.
[0042] Example 8 (1) Preparation of fluorosilane sol precursor solution: Mix 55g ethanol and 5g isopropanol, add acetic acid to adjust the pH to 4.0, add 2g FAS-17 fluorosilane coupling agent and stir evenly, adjust the pH of water to 4.0 with acetic acid, keep stirring and gradually add 40g water (pH 4.0), stir continuously at room temperature for 12h to prepare fluorosilane sol precursor solution for later use.
[0043] (2) Surface modification of oxides: 100g of α-Al2O3 powder with a particle size of 100nm was added to 100g of fluorosilicone coupling agent precursor liquid and stirred in a constant temperature water bath at 60℃ for 1.5h. During the reaction, the mixture was ultrasonically dispersed for 10min every 20min. The mixture after the reaction was centrifuged, dried in an oven, cooled and then ground in a ball mill to obtain surface-modified oxide powder with an average particle size of 5μm.
[0044] (3) Preparation of fluorinated coolant: Add 10% by mass of modified alumina powder to perfluoroalkane (PFC-40), first ultrasonically disperse for 25 min, and then shear disperse for 18 min at 9000 r / min using a high-speed shear disperser to obtain a uniform and stable alumina / perfluoropolyether coolant.
[0045] Example 9 Except for replacing 100g of α-Al2O3 powder with a particle size of 100nm with 80g of α-Al2O3 powder with a particle size of 100nm, everything else is the same as in Example 8.
[0046] Example 10 Except for replacing 100g of α-Al2O3 powder with a particle size of 100nm with 120g of α-Al2O3 powder with a particle size of 100nm, everything else is the same as in Example 8.
[0047] Example 11 Except for replacing 100g of α-Al2O3 powder with a particle size of 100nm with 120g of silica powder with a particle size of 100nm, everything else is the same as in Example 8.
[0048] Example 12 Except for replacing 100g of α-Al2O3 powder with a particle size of 100nm with 120g of magnesium oxide powder with a particle size of 100nm, everything else is the same as in Example 8.
[0049] Comparative Example 1 Compared with Example 1, unmodified alumina powder (particle size of 100 nm) was added to perfluoropolyether (DuPont Krytox® 100) at a mass fraction of 10%. The mixture was first ultrasonically dispersed for 25 min, and then sheared and dispersed for 18 min at 9000 r / min using a high-speed shear disperser to obtain a uniform and stable alumina / perfluoropolyether coolant.
[0050] Comparative Example 2 (1) Preparation of silane coupling agent precursor solution: Mix 55g ethanol and 5g isopropanol, add acetic acid to adjust the pH to 4.0, add 2g KH-560 silane coupling agent and stir evenly, adjust the pH of water to 4.0 with acetic acid, keep stirring and gradually add 40g water (pH 4.0), stir continuously at room temperature for 12h to hydrolyze, and prepare silane coupling agent precursor solution for later use.
[0051] (2) Surface modification of oxides: 100g of α-Al2O3 powder with a particle size of 100nm was added to 100g of silicon coupling agent precursor liquid and stirred in a constant temperature water bath at 60℃ for 1.5h. During the reaction, the mixture was ultrasonically dispersed for 10min every 20min. The mixture after the reaction was centrifuged, dried in an oven, cooled and then ground in a ball mill to obtain surface-modified oxide powder with an average particle size of 5μm.
[0052] (3) Preparation of fluorinated coolant: Add 10% by mass of modified alumina powder to perfluoroalkane (PFC-40), first ultrasonically disperse for 25 min, and then shear disperse for 18 min at 9000 r / min using a high-speed shear disperser to obtain a uniform and stable alumina / perfluoropolyether coolant.
[0053] Performance testing: The water contact angle of the modified alumina powder surface was measured using a surface contact angle tester; the fluorine coolant was placed in a graduated cylinder and allowed to stand, and the stratification and sedimentation phenomena were observed to examine its stability; the thermal conductivity of the fluorine coolant was tested using a thermal conductivity tester or a laser flare tester.
[0054] The performance of Examples 1-12 (with Examples 1, 7, and 8 as typical examples) and Comparative Examples 1-2 is shown in Table 1.
[0055] Table 1 Performance of Fluorine Coolant
[0056] The fluorosilane coupling agent-modified alumina in Examples 1, 7, and 8 significantly improved the surface hydrophobicity, dispersion stability, and thermal conductivity of the enhanced fluorinated coolant compared to Comparative Examples 1 and 2. In Example 1, the alumina modified with FAS-13 fluorosilane coupling agent achieved a surface contact angle of 118°, exhibited good surface compatibility with the perfluoropolyether (DuPont Krytox® 100) fluorinated coolant, and showed a homogeneous system with no sedimentation. The thermal conductivity test showed a 38% improvement compared to Comparative Example 1 (unmodified alumina powder), reaching 0.08 W / (m·K). In Example 8, the alumina modified with FAS-17 fluorosilane coupling agent achieved a surface contact angle of 115°, exhibited good surface compatibility with the perfluoroalkane (PFC-40) fluorinated coolant, and showed a homogeneous system with no sedimentation. The thermal conductivity test showed a 20% improvement compared to Comparative Example 2 (alumina modified with KH-560 silane coupling agent), reaching 0.072 W / (m·K).
[0057] The comparison results show that the alumina modified by the fluorosilane coupling agent in this invention is significantly superior to existing modifier solutions in terms of hydrophobicity, dispersion stability and thermal conductivity.
[0058] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. An oxide-reinforced fluorine coolant, characterized in that, The oxide-enhanced fluorine coolant comprises a fluorine coolant and a modified oxide; The modified oxide is an oxide modified with a fluorosilane coupling agent.
2. The oxide-reinforced fluorine coolant according to claim 1, characterized in that, The fluorinated coolant is selected from at least one of perfluoropolyether, hydrofluoroether, perfluoroalkane, and high-viscosity fluorinated oil; The fluorosilane coupling agent is selected from at least one of heptadecafluorodecyltriethoxysilane, tridecafluorooctyltrimethoxysilane, and trifluoropropyldimethoxysilane.
3. The oxide-reinforced fluorine coolant according to claim 2, characterized in that, When the fluorinated coolant is a perfluoropolyether or a hydrofluoroether, the fluorosilane coupling agent is selected as tridecylfluorooctyltrimethoxysilane or trifluoropropyldimethoxysilane. When the fluorinated coolant is a perfluoroalkane or a high-viscosity fluorinated oil, the fluorosilane coupling agent is selected as heptadecafluorodecyltrimethoxysilane.
4. The oxide-reinforced fluorine coolant according to claim 1, characterized in that, The oxide is selected from at least one of aluminum oxide, magnesium oxide, and silicon dioxide; Preferably, the oxide is a nano-sized oxide with a particle size range of 50~200nm; Preferably, the alumina is α-Al₂O₃; Preferably, the modified oxide has a mass fraction of 5-15%.
5. The method for preparing the oxide-reinforced fluorine coolant according to any one of claims 1 to 4, characterized in that, The preparation method includes: S1, fluorosilane hydrolysis The fluorosilane coupling agent was dissolved in a mixed solvent of ethanol and isopropanol, water was added, the pH value of the system was adjusted, and the mixture was continuously stirred and hydrolyzed to obtain the fluorosilane sol precursor liquid. S2, Interface Modification Reaction The oxide powder was added to the fluorosilane sol precursor liquid, stirred and reacted, and then ultrasonically dispersed. S3, Post-processing The reaction mixture was separated, dried, cooled, and then ground to obtain surface-modified oxide powder. S4, Mixed Dispersion The surface-modified oxide powder was added to the fluorine coolant, and then ultrasonically dispersed and sheared to obtain the oxide-reinforced fluorine coolant.
6. The preparation method according to claim 5, characterized in that, In step S1, the mass percentage of the components in the system is as follows: Fluorosilane coupling agent: 0.5~5 parts; Ethanol: 40-55 parts; Isopropanol: 1-5 parts; Water: 40-55 parts; Preferably, acetic acid is used to adjust the pH of the system, wherein the pH of the system is 3.4 to 4.0; Preferably, the mixture is continuously stirred at room temperature for 12 to 48 hours.
7. The preparation method according to claim 5, characterized in that, In step S2, 80-120 parts of oxide powder are added to 100 parts by mass of the fluorosilane sol precursor liquid. Preferably, the mixture is placed in a constant temperature water bath at 60~70℃ and stirred for 1.5~2.5h, during which time it is ultrasonically dispersed for 10~15min every 20~40min.
8. The preparation method according to claim 5, characterized in that, In step S3, the particle size of the surface-modified oxide powder is 0.1 ~ 10 μm.
9. The preparation method according to claim 5, characterized in that, In step S4, the mass fraction of the surface-modified oxide powder is 5-15%.
10. The preparation method according to claim 5, characterized in that, In step S4, the ultrasonic dispersion time is 20-30 min; the shear dispersion speed is 8000-10000 r / min, and the time is 15-20 min.