Preparation method of graphene cooling liquid for liquid-cooled radiator

Abstract

The invention relates to the field of graphene cooling liquids, and discloses a preparation method of a graphene cooling liquid for a liquid-cooled radiator, and the preparation method specifically comprises the following steps: mixing an acetic acid solution with deionized water, adding chitosan powder into the mixed solution, and stirring for dissolving; adding deionized water, ethylene glycol and a composite corrosion inhibitor into a reaction kettle for mixing, then adding the chitosan mixed solution obtained in the step S1 into the reaction kettle, and continuously stirring; s2, transferring the mixed solution obtained in the step S2 into a high-shear dispersion machine, slowly adding hydroxylation modified graphene powder in batches under the action of high-speed shearing, and continuously shearing and stirring; s3, the rotating speed in the dispersion machine is adjusted to 300-600 rpm, a defoaming agent is added into the mixed solution in the step S3, then a pH regulator is added, and the pH is adjusted to 9.0-9.5; the mixed solution obtained in the step S4 is transferred into a ball mill for ball milling, the graphene cooling liquid is obtained after ball milling is finished, and the body heat conductivity coefficient of the cooling liquid is remarkably increased.

Description

Technical Field

[0001] This invention relates to the field of graphene coolant, and more specifically to a method for preparing graphene coolant for liquid cooling radiators. Background Technology

[0002] As electronic devices (such as CPUs, GPUs, server chips, and power batteries) become more intelligent, lightweight, aesthetically pleasing, and integrated, their power density is also increasing, placing increasingly stringent demands on heat dissipation systems. Traditional water-glycol-based coolants have low thermal conductivity, which has become a bottleneck limiting further improvements in heat sink performance. Currently, adding high thermal conductivity materials is one of the effective ways to improve coolant performance. Graphene, composed of a single layer of dense sp2 carbon atoms, possesses excellent thermal conductivity (4840~5300 W / (m·K)), a large emissivity (>0.95), and an extremely high specific surface area (2630 m²). 2 g -1 With its excellent properties such as low coefficient of thermal expansion and stable chemical inertness, it is widely used as a new type of composite material to improve the thermal conductivity of composite materials.

[0003] However, graphene readily aggregates and settles in the liquid phase, leading to a decrease in the material's thermal conductivity and the risk of pipe blockage. Currently, existing technologies mostly employ organic polymeric dispersants (such as polyvinylpyrrolidone (PVP)) to aid dispersion; however, these substances may have poor biodegradability and provide insufficient etch protection for metal components, especially copper, aluminum, and their alloys commonly found in heat sinks. Furthermore, while graphene modified with strong acids or oxidants can improve dispersibility, it may damage the heat sink material and impose an environmental burden. Therefore, this paper proposes a method for preparing graphene coolant for liquid-cooled heat sinks to address the aforementioned problems. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing graphene coolant for liquid cooling heat sinks, which solves the problem that graphene is prone to agglomeration and sedimentation in the liquid phase, leading to a decrease in the thermal conductivity of the material and the risk of pipe blockage.

[0005] The objective of this invention can be achieved through the following technical solutions: A method for preparing graphene coolant for liquid-cooled heat sinks specifically includes the following steps: Step S1: Mix the acetic acid solution with deionized water, then add chitosan powder to the mixed solution and stir to dissolve; Acetic acid solution can be prepared by deionized water and weak acid (such as glacial acetic acid). The ratio of chitosan, deionized water and glacial acetic acid is 0.5~1.5 parts: 5~15 parts: 0.05~0.15 parts.

[0006] Step S2: Add deionized water, ethylene glycol and composite corrosion inhibitor to the reaction vessel and mix. After mixing, add the chitosan mixed solution obtained in step S1 to the reaction vessel and continue stirring. Step S3: Transfer the mixed solution obtained in step S2 to a high-shear disperser. Under this high-speed shearing action, slowly and batch-wise add hydroxylated modified graphene powder and continuously shear and stir. The amount of hydroxylated modified graphene powder used is 0.25~0.75 parts; Step S4: Adjust the speed of the disperser to 300-600 rpm, add defoamer to the mixed solution in step S3, and then add pH adjuster to adjust the pH to 9.0-9.5; The dosage of defoamer is 0.1 to 0.3 parts, and the dosage of pH adjuster is 0.1 to 0.2 parts; Furthermore, the defoamer is an organosilicon defoamer, specifically polydimethylsiloxane, and the pH adjuster is monoethanolamine; Step S5: Transfer the mixture obtained in step S4 to a ball mill for ball milling, and obtain graphene coolant after the process.

[0007] Furthermore, in step S1, the mixture is stirred and dissolved at 30~50℃ for 1-3 hours.

[0008] Furthermore, in step S2, the mixing conditions in the reactor are stirring at 200-500 rpm for 1-3 hours, and after adding the chitosan mixed solution obtained in step S1, stirring is continued for 20-40 minutes.

[0009] Furthermore, in step S3, the high-shear disperser is adjusted to a rotation speed of 6000-10000 rpm, and the continuous shearing and stirring time is 40-80 min.

[0010] Furthermore, the ball milling time in step S5 is 1-3 hours.

[0011] Further, the graphene coolant comprises, by weight, the following components: 40-60 parts deionized water, 40-50 parts ethylene glycol, 0.1-1.0 parts hydroxylated modified graphene, 0.5-2.0 parts chitosan, 1.0-3.0 parts composite corrosion inhibitor, 0.1-0.5 parts defoamer, and an appropriate amount of pH adjuster to make the pH of the system 9.0-9.5.

[0012] Furthermore, the hydroxylated modified graphene has a sheet diameter of less than 10 μm; Graphene was modified by hydroxylation, introducing hydroxyl groups (-OH) onto its surface. This not only enhanced the hydrophilicity of graphene, making it easier to disperse in the water-ethylene glycol system, but more importantly, the hydroxyl groups on its surface interacted strongly with the functional groups of chitosan, forming a stable "graphene-chitosan" composite structure and achieving exceptional dispersion stability.

[0013] Furthermore, the degree of deacetylation of the chitosan is not less than 90%; Chitosan, a biomass derivative, is used as a green dispersant and corrosion inhibitor for graphene. The amino and hydroxyl groups in chitosan molecules can effectively encapsulate graphene through electrostatic and adsorption interactions, preventing its aggregation. At the same time, it can form a protective film on the metal surface, enhancing the protection of the heat sink material.

[0014] Furthermore, the composite corrosion inhibitor is a borate-silicate composite corrosion inhibitor; Through the synergistic effect of borate-silicate composite corrosion inhibitors and chitosan, comprehensive protection is provided for commonly used metals in radiators such as aluminum, copper, and steel. Precise control of the pH value within the weakly alkaline range (9.0-9.5) satisfies corrosion inhibition requirements while avoiding potential corrosion of metals and sealing materials by strong alkalis.

[0015] The beneficial effects of this invention are as follows: The addition of hydroxylated modified graphene significantly improves the bulk thermal conductivity of the coolant, by more than 20% compared to traditional coolants. This allows for more efficient heat removal from the heat source, significantly reducing the operating temperature of the radiator. Through the synergistic dispersion mechanism of "hydroxylated graphene + chitosan," graphene can maintain long-term stability in the liquid phase (no visible sedimentation for more than 90 days), avoiding the risk of decreased heat dissipation performance and pipe blockage caused by sedimentation. It is particularly suitable for radiators in scenarios such as servers and data centers that require long-term stable operation. The combined action of chitosan and composite corrosion inhibitors exhibits excellent corrosion inhibition performance on metal materials such as copper, aluminum, and solder in the radiator flow channels, extending the life of the radiator system. Replacing some traditional synthetic chemical reagents with renewable chitosan reduces the environmental footprint of the product, which is in line with the development trend of green chemistry. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1: A method for preparing graphene coolant for liquid-cooled heat sinks, specifically including the following steps: Step S1: Slowly add 1.0 kg of chitosan (95% degree of deacetylation) to a mixed solution consisting of 10 kg of deionized water and 0.1 kg of glacial acetic acid, and magnetically stir for 30 min at 26°C and 600 rpm to obtain a chitosan mixed solution. Step S2: In a stirred reactor, add 40 kg of deionized water, 45 kg of ethylene glycol, and 1.5 kg of composite corrosion inhibitor, and stir at 300 rpm for 30 min at 26°C. Then add the chitosan solution from step S1 and continue stirring for 30 min.

[0018] Step S3: Transfer the mixed solution obtained in step S2 to a high-speed shear press, adjust the speed to 8000 rpm, and slowly add 0.5 kg of hydroxylated modified graphene (sheet diameter 5-8 μm) at 26°C. After the addition is complete, maintain this speed and disperse for 60 minutes. Step S4: Reduce the speed of the high-speed shearing machine in step S3 to 500 rpm, add 0.2 kg of polydimethylsiloxane and stir for 1 hour, then slowly add 0.15 kg of monoethanolamine and adjust the pH to 9.5. Step S5: Pump the slurry obtained in step S4 into a ball mill, and discharge it after ball milling at 26°C for 2 hours to obtain the final product.

[0019] Example 2, a method for preparing graphene coolant for liquid cooling heat sinks, specifically includes the following steps: Step S1: Slowly add 2 kg of chitosan (95% degree of deacetylation) to a mixed solution consisting of 15 kg of deionized water and 0.15 kg of glacial acetic acid, and stir magnetically for 30 min at 26°C and 600 rpm to obtain a chitosan mixed solution. Step S2: In a stirred reactor, add 25 kg of deionized water, 40 kg of ethylene glycol and 3 kg of composite corrosion inhibitor, and stir at 300 rpm for 30 min at 26 °C. Then add the chitosan solution from step S1 and continue stirring for 30 min.

[0020] Step S3: Transfer the mixed solution obtained in step S2 to a high-speed shear press, adjust the speed to 8000 rpm, and slowly add 0.1 kg of hydroxylated modified graphene (sheet diameter 5-8 μm) at 26°C. After the addition is complete, maintain this speed and disperse for 60 minutes. Step S4: Reduce the speed of the high-speed shear machine in step S3 to 500 rpm, add 0.5 kg of polydimethylsiloxane and stir for 1 hour, then slowly add monoethanolamine dropwise to adjust the pH to 9.5; Step S5: Pump the slurry obtained in step S4 into a ball mill, and discharge it after ball milling at 26°C for 2 hours to obtain the final product.

[0021] Example 3: A method for preparing graphene coolant for liquid-cooled heat sinks, specifically including the following steps: Step S1: Slowly add 0.5 kg of chitosan (95% degree of deacetylation) to a mixed solution consisting of 5 kg of deionized water and 0.05 kg of glacial acetic acid, and stir magnetically for 30 min at 26°C and 600 rpm to obtain a chitosan mixed solution. Step S2: In a stirred reactor, add 55 kg of deionized water, 50 kg of ethylene glycol and 1 kg of composite corrosion inhibitor, and stir at 300 rpm for 30 min at 26 °C. Then add the chitosan solution from step S1 and continue stirring for 30 min.

[0022] Step S3: Transfer the mixed solution obtained in step S2 to a high-speed shear press, adjust the speed to 8000 rpm, and slowly add 1 kg of hydroxylated modified graphene (sheet diameter 5-8 μm) at 26°C. After the addition is complete, maintain this speed and disperse for 60 minutes. Step S4: Reduce the speed of the high-speed shear machine in step S3 to 500 rpm, add 0.1 kg of polydimethylsiloxane and stir for 1 hour, then slowly add monoethanolamine dropwise to adjust the pH to 9.5; Step S5: Pump the slurry obtained in step S4 into a ball mill, and discharge it after ball milling at 26°C for 2 hours to obtain the final product.

[0023] Example 4: A method for preparing graphene coolant for liquid-cooled heat sinks, specifically including the following steps: Step S1: Slowly add 1.0 kg of chitosan (95% degree of deacetylation) to a mixed solution consisting of 10 kg of deionized water and 0.1 kg of glacial acetic acid, and magnetically stir for 30 min at 26°C and 600 rpm to obtain a chitosan mixed solution. Step S2: In a stirred reactor, add 40 kg of deionized water, 45 kg of ethylene glycol and 1.5 kg of composite corrosion inhibitor, and stir at 300 rpm for 30 min at 26 °C. Then add the chitosan solution from step S1 and continue stirring for 30 min.

[0024] Step S3: Transfer the mixed solution obtained in step S2 to a high-speed shear press, adjust the speed to 8000 rpm, and slowly add 0.5 kg of graphene oxide at 26°C. After the addition is complete, maintain this speed and disperse for 60 minutes. Step S4: Reduce the speed of the high-speed shearing machine in step S3 to 500 rpm, add 0.2 kg of polydimethylsiloxane and stir for 1 hour, then slowly add 0.15 kg of monoethanolamine and adjust the pH to 9.5. Step S5: Pump the slurry obtained in step S4 into a ball mill, and discharge it after ball milling at 26°C for 2 hours to obtain the final product.

[0025] Example 5: A method for preparing graphene coolant for liquid-cooled heat sinks, specifically including the following steps: Step S1: Slowly add 1.0 kg PVP to a mixed solution consisting of 10 kg deionized water and 0.1 kg glacial acetic acid, and magnetically stir for 30 min at 26°C and 600 rpm to obtain a chitosan mixed solution. Step S2: In a stirred reactor, add 40 kg of deionized water, 45 kg of ethylene glycol and 1.5 kg of composite corrosion inhibitor, and stir at 300 rpm for 30 min at 26 °C. Then add the chitosan solution from step S1 and continue stirring for 30 min.

[0026] Step S3: Transfer the mixed solution obtained in step S2 to a high-speed shear press, adjust the speed to 8000 rpm, and slowly add 0.5 kg of hydroxylated modified graphene at 26°C. After the addition is complete, maintain this speed and disperse for 60 minutes. Step S4: Reduce the speed of the high-speed shear machine in step S3 to 500 rpm, add 0.2 kg of polydimethylsiloxane and stir for 1 hour, then slowly add monoethanolamine dropwise to adjust the pH to 9.5; Step S5: Pump the slurry obtained in step S4 into a ball mill, and discharge it after ball milling at 26°C for 2 hours to obtain the final product.

[0027] Comparative Example 1: This comparative example does not add chitosan compared to Example 1, but uses an equal amount of deionized water instead, and the other steps are the same.

[0028] Performance testing: The products from Examples 1-5 were compared with the product from Comparative Example 1 in the following tests: The thermal conductivity of the graphene coolants obtained in Examples 1-5 and Comparative Example 1 at 85°C was measured using a DZDR-S transient thermal conductivity meter. The test results are as follows: Table 1 shows the thermal conductivity test results of the graphene coolant in Examples 1-5 and Comparative Example 1.

[0029] The stability of the coolants obtained in Examples 1-3 and Comparative Example 1 was tested, and the results are shown in Table 2 below:

[0030] Test results show that the coolant of this invention is significantly superior to the traditional formula in key performance indicators.

[0031] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing graphene coolant for liquid cooling radiator, characterized in that: Specifically comprising the following steps: Step S1: mixing acetic acid solution with deionized water, and then adding chitosan powder into the mixed solution to stir and dissolve; Step S2: adding deionized water, ethylene glycol and composite corrosion inhibitor into a reaction kettle to mix, and then adding the chitosan mixed solution obtained in step S1 into the reaction kettle to continue stirring after the mixing is completed; Step S3: transferring the mixed solution obtained in step S2 into a high-shear disperser, and then slowly and batchwise adding hydroxylated modified graphene powder under the high-speed shearing action, and continuously shearing and stirring; Step S4: adjusting the rotating speed of the disperser to 300-600 rpm, and then adding defoaming agent and pH regulator into the mixed solution in step S3 to adjust the pH value to 9.0-9.5; Step S5: transferring the mixed solution obtained in step S4 into a ball mill to perform ball milling, and then obtaining graphene coolant after the ball milling is completed.

2. The method for preparing graphene coolant for liquid-cooled heat sinks according to claim 1, characterized in that: The stirring and dissolving in step S1 is performed at 30-50℃ for 1-3h.

3. The method for preparing graphene coolant for liquid-cooled heat sinks according to claim 1, characterized in that: The mixing in the reaction kettle in step S2 is performed at a rotating speed of 200-500 rpm for 1-3h, and after the chitosan mixed solution obtained in step S1 is added, the stirring is continued for 20-40 min.

4. The method for preparing graphene coolant for liquid-cooled heat sinks according to claim 1, characterized in that: The rotating speed of the high-shear disperser in step S3 is adjusted to 6000-10000 rpm, and the continuous shearing and stirring time is 40-80 min.

5. The method for preparing graphene coolant for liquid-cooled heat sinks according to claim 1, characterized in that: The ball milling time in step S5 is 1-3h.

6. The method for preparing graphene coolant for liquid-cooled heat sinks according to claim 1, characterized in that: The graphene coolant comprises the following components in parts by weight: deionized water 40-60 parts, ethylene glycol 40-50 parts, hydroxylated modified graphene 0.1-1.0 parts, chitosan 0.5-2.0 parts, composite corrosion inhibitor 1.0-3.0 parts, defoaming agent 0.1-0.5 parts, and pH regulator in an appropriate amount to make the pH value of the system 9.0-9.

5.

7. The method for preparing graphene coolant for liquid-cooled heat sinks according to claim 6, characterized in that: The flake diameter of the hydroxylated modified graphene is less than 10μm.

8. The method for preparing graphene coolant for liquid-cooled heat sinks according to claim 6, characterized in that: The degree of deacetylation of the chitosan is not less than 90%.

9. The method for preparing graphene coolant for liquid-cooled heat sinks according to claim 6, characterized in that: The composite corrosion inhibitor is a borate-silicate composite corrosion inhibitor.

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