Preparation method of modified foam metal phase change composite material and product thereof

Abstract

The application relates to the technical field of phase change heat storage, in particular to a preparation method of a modified foam metal phase change composite material, which comprises the following steps: S1, stirring and mixing foam metal in a buffer solution containing hydrochloric acid dopamine, drying, and obtaining pretreated foam metal; S2, immersing the pretreated foam metal obtained in step S1 in a dispersion liquid containing carbon-based material, drying, and obtaining modified foam metal; S3, vacuum immersing the modified foam metal obtained in step S2 in a molten phase change material, and obtaining a modified foam metal phase change composite material after cooling. According to the preparation method, the foam metal is endowed with certain viscosity and hydrophilic performance through the treatment of polydopamine, so as to serve as a 'bridge' between the foam metal and carbon nanotubes, and the carbon-based material can be firmly attached to the foam metal through the treatment, the adsorption of the phase change material is enhanced, the anti-leakage capacity is improved, and the light-heat conversion capacity and the heat conduction performance of the material are also improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of phase change heat storage, in particular to a preparation method of modified foam metal phase change composite material and a product thereof. BACKGROUND

[0002] Compared with other renewable energy sources, solar energy stands out due to its unlimited supply and wide distribution. However, solar energy is an unstable, discontinuous and low energy density energy source. Latent heat storage (LHS) has a high heat storage density and a stable phase change temperature during charging and discharging. The use of LHS for solar energy conversion and storage can solve the above problems of solar energy, and the combination of the two has a broader application prospect.

[0003] Traditional organic solid-liquid phase change materials (PCMs) have been widely used in LHS. Organic solid-liquid phase change materials have the advantages of high heat storage density and stable temperature during phase change. Foam metal is widely used to enhance the heat transfer of phase change materials and improve the thermal conductivity due to its high thermal conductivity, high porosity, high specific strength and stiffness, and space interconnected porous structure. However, the pore size of foam metal is usually too large, which on the one hand cannot effectively prevent PCM leakage, resulting in low PCM loading capacity; on the other hand, the large pore size leads to a small contact area between the skeleton and the PCM, resulting in a large thermal resistance in the heat transfer process.

[0004] Therefore, it is necessary to provide a technical solution to solve the above problems. SUMMARY

[0005] One of the purposes of the present application is to provide a preparation method of modified foam metal phase change composite material to solve the problem that the current foam metal alone cannot prevent the leakage of organic solid-liquid phase change materials (PCMs) and has a large thermal resistance in the heat transfer process.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0007] A preparation method of modified foam metal phase change composite material, comprising the following steps:

[0008] S1, put the foam metal into a buffer solution containing dopamine hydrochloride and stir to mix, dry to obtain pretreated foam metal;

[0009] S2, immerse the pretreated foam metal obtained in step S1 in a dispersion liquid containing carbon-based material, dry to obtain modified foam metal;

[0010] S3, vacuum impregnate the modified foam metal obtained in step S2 in a molten phase change material, and cool to obtain a modified foam metal phase change composite material.

[0011] Preferably, the foamed metal is at least one of foamed nickel, foamed copper and foamed aluminum; and the phase change material is polyethylene glycol.

[0012] Preferably, in step S1, the concentration of dopamine hydrochloride is 3-9 g / mol; and the mass ratio of dopamine hydrochloride to the foamed metal is 3.55:(1.8-5.4).

[0013] Preferably, in step S1, the buffer in the dopamine hydrochloride-containing buffer is a tris-hydroxymethyl aminomethane-hydrochloric acid buffer; the pH value of the tris-hydroxymethyl aminomethane-hydrochloric acid buffer is 8-9; and the foamed metal is stirred and mixed in the dopamine hydrochloride-containing buffer for 10-20 h.

[0014] Preferably, the mass ratio of the carbon-based material to dopamine hydrochloride is 10:(9-27).

[0015] Preferably, in step S2, the carbon-based material-containing dispersion liquid comprises multi-walled carbon nanotubes and a surface dispersant, and the mass ratio of the multi-walled carbon nanotubes to the surface dispersant is (80-120):1; and the surface dispersant is at least one of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, cetyl trimethyl ammonium bromide and sodium cholate.

[0016] Preferably, in step S2, the pretreated foamed metal is sequentially immersed and dried in the carbon-based material-containing dispersion liquid for 3-6 times, and each time of immersion lasts for 10-20 min.

[0017] Preferably, in step S3, the mass ratio of the phase change material to dopamine hydrochloride is 275:(9-27).

[0018] Preferably, in step S3, the phase change material is converted into a molten state at 90-100℃, and is kept at the temperature for 3-5 h for vacuum immersion modification of the foamed metal.

[0019] The second object of the present application is to provide a modified foamed metal phase change composite material prepared by the above-mentioned method for preparing a modified foamed metal phase change composite material.

[0020] The application has the beneficial effects that: the preparation method provided by the application first treats the foamed metal by polydopamine, the polydopamine is rich in functional groups such as catechol, and can endow the foamed metal with certain tackiness and hydrophilic properties, and can serve as a 'bridge' between the foamed metal and the carbon nanotube, and then the carbon-based material is loaded on the foamed metal for modification, and thanks to the aforementioned pretreatment of the polydopamine, the carbon-based material can be firmly attached to the foamed metal, and on the one hand, the firm attachment of the carbon-based material can enhance the adsorption of the phase change material and improve the leakage prevention capability of the phase change composite material, and on the other hand, the carbon-based material increases the contact area between the phase change material and the modified foamed metal, and can improve the light-heat conversion capability and the heat conduction performance of the phase change composite material, and solves the problems that the current foamed metal alone is not enough to prevent the phase change material from leaking, and the thermal resistance is also large in the heat transfer process. BRIEF DESCRIPTION OF DRAWINGS

[0021] Fig. 1 The figure is the morphology distribution diagram of the initial foamed nickel in the embodiment 1 of the application.

[0022] Fig. 2 The figure is the morphology distribution diagram of the foamed nickel after being treated by the hydrochloric acid dopamine in the embodiment 1 of the application.

[0023] Fig. 3 The figure is the morphology distribution diagram of the foamed nickel after being modified by the hydrochloric acid dopamine and the carbon nanotube in the embodiment 1 of the application.

[0024] Fig. 4 The figure is the comparison diagram of the light-heat conversion test of the embodiment 1-3 and the comparative example 1-2 of the application. DETAILED DESCRIPTION

[0025] In order to make the technical solutions and advantages of the application clearer, the application and its beneficial effects are described in further detail below, but the embodiments of the application are not limited thereto.

[0026] The application provides a preparation method of a modified foamed metal phase change composite material, which comprises the following steps:

[0027] S1, foamed metal is put into a buffer solution containing hydrochloric acid dopamine, stirred and mixed, and dried to obtain pretreated foamed metal;

[0028] S2, the pretreated foamed metal obtained in step S1 is put into a dispersion liquid containing a carbon-based material for impregnation, and dried to obtain modified foamed metal;

[0029] S3, the modified foamed metal obtained in step S2 is put into a molten phase change material for vacuum impregnation, and after cooling, a modified foamed metal phase change composite material is obtained.

[0030] The phase change composite provided by the present application effectively enhances the stability of the phase change material loaded on the foam metal, solves the problem that the conventional modified foam metal cannot effectively prevent the leakage of the phase change material due to the excessively large pore size, and causes the low loading capacity of the phase change material. Specifically, for the modification of the foam metal, first, the foam metal is mixed with a buffer solution containing dopamine hydrochloride, so that the generated polydopamine is loaded on the foam metal. The polydopamine can endow the foam metal with certain viscosity and hydrophilic properties, and can effectively firmly attach the carbon-based material to the foam metal as a 'bridge' between the foam metal and the carbon-based material, thereby providing a basis for the subsequent loading of the phase change material.

[0031] The carbon-based material preferably adopts multi-walled carbon nanotubes, which have abundant heat transfer channels, can realize effective phonon transmission and extensive sunlight absorption, and thus can further improve the light-heat conversion capacity and heat conduction performance of the phase change composite.

[0032] The modified foam metal of the present application uses polydopamine as a 'bridge' between the foam metal and the carbon nanotubes. Compared with the modification method of directly loading the carbon nanotubes on the foam metal, the present application solves the leakage problem of the phase change material after loading, has a higher loading capacity of the phase change material, has a stronger light-heat conversion capacity of solar energy, and has a larger latent heat storage capacity.

[0033] The present application preferably uses polyethylene glycol as the phase change material, which has the advantages of large phase change latent heat, wide phase change range, low price, etc. on the one hand, and good compatibility with the modified foam metal of the present application on the other hand, thereby effectively improving the leakage prevention capacity of the phase change composite.

[0034] The foam metal after the cleaning pretreatment is at least one of foam nickel, foam copper, and foam aluminum. Preferably, foam nickel is used as the carrier.

[0035] In some embodiments, in step S1, the concentration of dopamine hydrochloride is 3-9 g / mol; and the mass ratio of dopamine hydrochloride to foam nickel is 3.55:(1.8-5.4). The higher the concentration of dopamine hydrochloride, the more polydopamine is generated, which can adsorb more carbon-based materials on the surface of the foam metal, and the loading firmness of the carbon-based material is also better, which not only can improve the loading capacity of the subsequent phase change material, but also makes the carbon-based material more excellent in improving the light-heat conversion capacity of the phase change composite. Specifically, the concentration of dopamine hydrochloride includes but is not limited to 3 g / mol, 4 g / mol, 5 g / mol, 6 g / mol, 7 g / mol, 8 g / mol, and 9 g / mol; and the mass ratio of dopamine hydrochloride to foam nickel can be 3.55:(1.8-2.7), 3.55:(2.7-3.6), 3.55:(3.6-4.5), or 3.55:(4.5-5.4).

[0036] And the mixing time of the foamed metal in the dopamine hydrochloride-containing buffer solution is 10-20 h. Relatively speaking, the longer the mixing time of the foamed metal in the buffer solution, the better the effect of the generated polydopamine on the pretreatment of the foamed metal.

[0037] The buffer solution in the dopamine hydrochloride-containing buffer solution is a tris-hydroxymethyl aminomethane-hydrochloric acid (Tris-HCl) buffer solution; and the pH value of the tris-hydroxymethyl aminomethane-hydrochloric acid buffer solution is 8-9.

[0038] The mass ratio of dopamine hydrochloride to tris-hydroxymethyl aminomethane can be (2.475-7.43):1, and specifically includes but is not limited to 2.475:1, 3.3:1, 4.125:1, 4.95:1 or 7.43:1.

[0039] In some embodiments, the mass ratio of the carbon-based material to dopamine hydrochloride is 10:(9-27). Specifically, the mass ratio of the carbon-based material to dopamine hydrochloride can be 10:(9-12), 10:(12-15), 10:(15-18), 10:(18-23) or 10:(23-27). The higher the content of the generated polydopamine, the higher the carbon-based material that can be loaded, but excessive loading of the carbon-based material will reduce the firmness of the carbon-based material, which is not conducive to the subsequent loading of the phase change material. The inventors have verified through experiments that controlling the mass ratio of the two within the above range can avoid the problem of excessive loading of the carbon-based material affecting its firmness on the one hand, and also avoid the problem of too little carbon-based material that cannot effectively improve the leakage of the phase change material on the other hand.

[0040] In some embodiments, in step S2, the dispersion liquid containing the carbon-based material includes multi-walled carbon nanotubes and a surface dispersant, and the mass ratio of the multi-walled carbon nanotubes to the surface dispersant is (80-120):1. Preferably, the mass ratio of the multi-walled carbon nanotubes to the surface dispersant is 100:1. The multi-walled carbon nanotubes are prone to form agglomerates, and the foamed metal treated by dopamine hydrochloride has increased viscosity. Therefore, before impregnating and pretreating the foamed metal, the surface dispersant is added to the foamed metal to disperse the multi-walled carbon nanotubes more uniformly, which helps to uniformly adsorb the multi-walled carbon nanotubes on the surface of the foamed metal, so as to ensure that the phase change material is uniformly adsorbed on the surface of the modified foamed metal.

[0041] The surface dispersant can be at least one of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, cetyltrimethylammonium bromide and sodium cholate; and preferably, the surface dispersant is sodium dodecyl benzene sulfonate, which has a more significant dispersing effect on the multi-walled carbon nanotubes.

[0042] In some embodiments, in step S2, the pretreated foamed metal is sequentially immersed and dried in the dispersion of carbon-based material, and the number of repetitions is 3-6, and the time of each immersion is 10-20 min. The method of multiple immersions adopted by the present application avoids the aggregation of too much carbon-based material at the same time, increases the agglomeration, and can more uniformly load more carbon-based material on the foamed metal. Not only can the thermal conductivity be further improved, but also the subsequent uniform loading of more phase change materials is based on the modification of polydopamine and carbon nanotubes. The phase change material has more loading capacity but can prevent leakage.

[0043] In some embodiments, in step S3, the mass ratio of the phase change material to dopamine hydrochloride is 275:(9-27). Specifically, 275:(9-12), 275:(12-15), 275:(15-18), 275:(18-23), or 275:(23-27). By controlling the mass ratio of the carbon-based material to dopamine hydrochloride and adjusting the mass ratio of the phase change material to dopamine hydrochloride within the above range, relatively more phase change material can be firmly loaded on the foamed metal without leakage problems.

[0044] In some embodiments, in step S3, the phase change material is converted into a molten state at 90-100°C and vacuum-impregnated into the modified foamed metal at this temperature for 3-5 h. The method of vacuum impregnation is used to load under the above conditions. The molten phase change material increases its contact area with the foamed metal, and the modification of the carbon-based material makes more phase change material firmly loaded on the foamed metal. When the latent heat of the solar energy is stored, the heat storage capacity is also stronger and more durable, which widens the application field of solar energy.

[0045] The present application and its beneficial effects will be described in further detail below with reference to specific embodiments and the accompanying drawings, but the embodiments of the present application are not limited thereto.

[0046] Example 1

[0047] A method for preparing a modified foamed metal phase change composite material, comprising the following steps:

[0048] (1) Selecting a foamed nickel with a size of 2.2 cm x 2.2 cm x 1.0 mm as the foamed metal, and cleaning the foamed nickel by ultrasonic cleaning with 40 ml of anhydrous ethanol and 40 ml of deionized water to remove possible oil stains on the surface or in the pores of the foamed nickel, and then placing it in a vacuum drying oven at 80°C to obtain a modified foamed metal;

[0049] (2) A buffer solution containing dopamine hydrochloride: A 10 mmol / L solution of tris-hydroxymethyl aminomethane (Tris) was prepared, and the pH of the solution was adjusted to 8.5 by dilute hydrochloric acid to prepare a Tris-HCl buffer solution. Then, 0.18 g of dopamine hydrochloride was added at a concentration of 3 g / mol, and the mixture was stirred for 2 min to prepare a 60 ml solution. The mass ratio of dopamine hydrochloride to Tris was 2.475:1.

[0050] (3) The foam metal to be modified was placed in the buffer solution containing dopamine hydrochloride, and stirred at room temperature for 16 h. After drying, a pretreated foam metal was obtained. The mass ratio of foam metal to dopamine hydrochloride was 3.55:1.8.

[0051] (4) A dispersion solution containing carbon-based material was prepared: 10 g / L of 20 mL of multi-walled carbon nanotube dispersion solution was prepared, and 1 wt% of sodium dodecylbenzenesulfonate was added thereto, and ultrasonic dispersion was performed for 1 min to obtain a uniform dispersion. The mass ratio of multi-walled carbon nanotube to sodium dodecylbenzenesulfonate was 100:1, and the mass ratio of multi-walled carbon nanotube to dopamine hydrochloride was 10:9.

[0052] (5) The pretreated foam metal was ultrasonically immersed in the dispersion solution containing carbon-based material for 15 min, and then vacuum dried at 85°C for 30 min. The immersion and drying steps were repeated 4 times in sequence to obtain a modified foam metal.

[0053] (6) Polyethylene glycol was used as a phase change material, and the mass ratio of polyethylene glycol to dopamine hydrochloride was 275:9. 5.5 g of polyethylene glycol was weighed into a beaker, heated to 95°C in a heating box, and then the modified foam metal was added when it was completely melted. After vacuum filtration and immersion for 4 h, it was taken out and cooled at room temperature for 2 h to obtain a modified foam nickel phase change composite material.

[0054] Example 2

[0055] The difference between Example 1 and Example 2 is that the amount of dopamine hydrochloride added in the preparation of the buffer solution containing dopamine hydrochloride is 0.36 g, and the concentration is 6 g / mol. The mass ratio of foam metal to dopamine hydrochloride is 3.55:3.6, the mass ratio of multi-walled carbon nanotube to dopamine hydrochloride is 10:18, and the mass ratio of polyethylene glycol to dopamine hydrochloride is 275:18.

[0056] The rest is the same as Example 1, which will not be repeated here.

[0057] Example 3

[0058] The difference between Example 1 is that the amount of dopamine hydrochloride added in the preparation of the buffer containing dopamine hydrochloride is 0.54 g, the concentration is 9 g / mol, the mass ratio of the corresponding foam metal to dopamine hydrochloride is 3.55:5.4, the mass ratio of the multi-walled carbon nanotube to dopamine hydrochloride is 10:27, and the mass of the polyethylene glycol to dopamine hydrochloride is 275:27.

[0059] The rest is the same as Example 1, which will not be repeated here.

[0060] Example 4

[0061] The difference between Example 1 is that the amount of dopamine hydrochloride added in the preparation of the buffer containing dopamine hydrochloride is 0.72 g, the concentration is 12 g / mol, the mass ratio of the corresponding foam metal to dopamine hydrochloride is 3.55:7.2, the mass ratio of the multi-walled carbon nanotube to dopamine hydrochloride is 10:54, and the mass of the polyethylene glycol to dopamine hydrochloride is 275:54.

[0062] The rest is the same as Example 1, which will not be repeated here.

[0063] Example 5

[0064] A method for preparing a modified foam metal phase change composite material, comprising the following steps:

[0065] (1) Selecting a 2.2 cm x 2.2 cm x 1.0 mm size foam copper as the foam metal, and using 40 ml of anhydrous ethanol and 40 ml of deionized water to ultrasonically clean the foam copper to remove possible oil stains on the surface or in the pores, and then placing it in a 80°C vacuum dryer to obtain a modified foam metal;

[0066] (2) Dopamine hydrochloride-containing buffer: prepare a 10 mmol / L tris-hydroxymethyl aminomethane (Tris) solution, adjust the solution pH to 8 with dilute hydrochloric acid to prepare a Tris-HCl buffer, then add 0.24 g of dopamine hydrochloride with a concentration of 4 mol / L, stir and mix for 2 min, and prepare 60 ml of solution; wherein the mass ratio of dopamine hydrochloride to Tris is 3.3:1;

[0067] (3) Put the modified foam metal into the buffer containing dopamine hydrochloride, stir and mix at room temperature for 20 h, dry, and obtain a pretreated foam metal; wherein the mass ratio of the foam metal to dopamine hydrochloride is 3.55:2.4;

[0068] (4) The dispersion liquid containing carbon-based material is configured: 20 mL of 10 g / L multi-walled carbon nanotube dispersion liquid is configured, and 1.25 wt% of sodium dodecyl benzene sulfonate is added thereto, and ultrasonic dispersion is performed for 1 min to uniformly disperse; wherein, the mass ratio of multi-walled carbon nanotube to sodium dodecyl benzene sulfonate is 80:1; the mass ratio of multi-walled carbon nanotube to dopamine hydrochloride is 10:12;

[0069] (5) The pretreated foam metal is immersed in the dispersion liquid containing carbon-based material for ultrasonic treatment for 20 min, and then vacuum dried at 85°C for 30 min, and the steps of immersion and drying are repeated for 3 times, to obtain modified foam metal;

[0070] (6) Polyethylene glycol is used as a phase change material, and the mass ratio of polyethylene glycol to dopamine hydrochloride is 275:12; 5.5 g of polyethylene glycol is weighed in a beaker, heated to 90°C in a heating box, and then the modified foam metal is put into the beaker after the polyethylene glycol is completely melted; vacuum filtration is performed, the modified foam metal is taken out after being immersed for 5 h, and cooled at room temperature for 2 h to obtain a modified foam copper phase change composite material.

[0071] Example 6

[0072] A method for preparing a modified foam metal phase change composite material, comprising the following steps:

[0073] (1) Foam aluminum with a size of 2.2 cm x 2.2 cm x 1.0 mm is selected as the foam metal, and the foam aluminum is ultrasonically cleaned with 40 ml of anhydrous ethanol and 40 ml of deionized water to remove oil stains possibly existing on the surface or in the pores of the foam aluminum, and then the foam aluminum is placed in a vacuum drying oven at 80°C to obtain a foam metal to be modified;

[0074] (2) A dopamine hydrochloride-containing buffer solution is prepared: a 10 mmol / L tris(hydroxymethyl)aminomethane (Tris) solution is prepared, the pH of the solution is adjusted to 9 by dilute hydrochloric acid to prepare a Tris-HCl buffer solution, and then 0.30 g of dopamine hydrochloride is added to the buffer solution to prepare a 60 ml solution; wherein, the mass ratio of dopamine hydrochloride to Tris is 4.125:1;

[0075] (3) The foam metal to be modified is placed in the dopamine hydrochloride-containing buffer solution, and stirred at room temperature for 10 h, and then dried to obtain a pretreated foam metal; wherein, the mass ratio of the foam metal to dopamine hydrochloride is 3.55:3.0;

[0076] (4) The dispersion liquid containing carbon-based material is configured: 20 mL of 10 g / L multi-walled carbon nanotube dispersion liquid is configured, and 0.83 wt% of sodium dodecyl benzene sulfonate is added thereto, and ultrasonic dispersion is performed for 1 min to uniformly disperse; wherein, the mass ratio of multi-walled carbon nanotube to sodium dodecyl benzene sulfonate is 120:1; the mass ratio of multi-walled carbon nanotube to dopamine hydrochloride is 10:15;

[0077] (5) Put the pretreated foam metal into the dispersion liquid containing carbon-based material for ultrasonic immersion for 10 min, and then vacuum dry at 85℃ for 30 min, and sequentially repeat the immersion and drying steps for 6 times, to obtain the modified foam metal;

[0078] (6) Take 5.5g of polyethylene glycol as the phase change material, and the mass ratio of polyethylene glycol to dopamine hydrochloride is 275:15, and place the polyethylene glycol in a beaker, heat to 100℃ in a heating box, and then put the modified foam metal into the beaker after complete melting, and then vacuum filter, take out after immersion for 3h, and cool at room temperature for 2h, to obtain the modified foam aluminum phase change composite material.

[0079] Example 7

[0080] The difference from Example 1 is that the carbon-based material used is graphene.

[0081] The rest is the same as Example 1, which will not be repeated here.

[0082] Comparative Example 1

[0083] A kind of phase change material, take 5.5g of polyethylene glycol and press it into a rectangular piece with the size of 2.2cm×2.2cm×1.0mm by a tablet press.

[0084] Comparative Example 2

[0085] A method for preparing a modified foam metal phase change composite material, comprising the following steps:

[0086] (1) Select a foam nickel with a size of 2.2cm×2.2cm×1.0mm as the foam metal, and use 40ml of absolute ethanol and 40ml of deionized water to ultrasonically clean the foam nickel to remove possible oil stains on the surface or in the pores, and then vacuum dry at 80℃ to obtain the foam metal;

[0087] (2) Take 5.5g of polyethylene glycol as the phase change material, and place it in a beaker, heat to 95℃ in a heating box, and then put the cleaned foam metal into the beaker after complete melting, and then vacuum filter, take out after immersion for 4h, and cool at room temperature for 2h, to obtain the foam nickel phase change composite material.

[0088] Comparative Example 3

[0089] A method for preparing a modified foam metal phase change composite material, comprising the following steps:

[0090] (1) Select a foam nickel with a size of 2.2cm×2.2cm×1.0mm as the foam metal, and use 40ml of absolute ethanol and 40ml of deionized water to ultrasonically clean the foam nickel to remove possible oil stains on the surface or in the pores, and then vacuum dry at 80℃ to obtain the foam metal;

[0091] (2) A dopamine hydrochloride-containing buffer solution: a 10 mmol / L solution of tris(hydroxymethyl)aminomethane (Tris) was prepared, the pH of the solution was adjusted to 8.5 by dilute hydrochloric acid to prepare a Tris-HCl buffer solution, and then 0.18 g of dopamine hydrochloride was added at a concentration of 3 mol / L, stirred and mixed for 2 min to prepare 60 ml of solution; wherein the mass ratio of dopamine hydrochloride to Tris was 2.475:1;

[0092] (3) The modified foam metal was obtained by placing the foam metal to be modified into the dopamine hydrochloride-containing buffer solution, stirring and mixing at room temperature for 16 h, and drying, and the modified foam metal was used as the modified foam metal, wherein the mass ratio of the foam metal to dopamine hydrochloride was 3.55:1.8;

[0093] (4) Polyethylene glycol was used as a phase change material, the mass ratio of polyethylene glycol to dopamine hydrochloride was 275:9, 5.5 g of polyethylene glycol was weighed in a beaker, heated to 95°C in a heating box, and then the modified foam metal was placed in when completely melted, vacuum filtration, immersed for 4 h, taken out, and cooled at room temperature for 2 h to obtain a modified foam nickel phase change composite material.

[0094] Comparative Example 4

[0095] A method for preparing a modified foam metal phase change composite material, comprising the following steps:

[0096] (1) A foam nickel with a size of 2.2 cm x 2.2 cm x 1.0 mm was selected as the foam metal, and the foam nickel was ultrasonically cleaned with 40 ml of anhydrous ethanol and 40 ml of deionized water to remove possible oil stains on the surface or in the pores, and then was placed in a vacuum drying oven at 80°C to obtain a pretreated foam metal;

[0097] (2) A dispersion liquid containing a carbon-based material was prepared: a 10 g / L 20 mL dispersion liquid of multi-walled carbon nanotubes was prepared, and 1 wt% of sodium dodecyl benzene sulfonate was added thereto and ultrasonically dispersed for 1 min; wherein the mass ratio of the multi-walled carbon nanotubes to the sodium dodecyl benzene sulfonate was 100:1;

[0098] (3) The pretreated foam metal was placed in the dispersion liquid containing the carbon-based material and ultrasonically immersed for 10 min, and then vacuum dried at 85°C for 30 min, and the steps of immersion and drying were repeated 4 times in turn to obtain a carbon nanotube-loaded foam metal;

[0099] (4) Polyethylene glycol was used as a phase change material, 5.5 g of polyethylene glycol was weighed in a beaker, heated to 95°C in a heating box, and then the carbon nanotube-loaded foam metal was placed in when completely melted, vacuum filtration, immersed for 4 h, taken out, and cooled at room temperature for 2 h to obtain a modified foam nickel phase change composite material.

[0100] The modified foam nickel phase change composite materials obtained in the above embodiments 1-7 and comparative examples 1-4 were subjected to photothermal conversion test, the sample was pressed into a rectangular square piece of 1.0 cm x 1.0 cm x 1.0 mm, and was placed into a photothermal test platform, and a 400 mW / cm 2 heliostat with a light intensity of 400 mW / cm Figs. 1-4 was used as a simulated solar light source, and the temperature change was tested for 540 s. The test results are shown in Table 1 and

[0101] Table 1 Photothermal conversion test results

[0102]

[0103]

[0104] As can be seen from the above Table 1 and Figs. 1-4 , the phase change composite material prepared by the present application is modified by polydopamine and carbon-based material on the foam metal, which improves the photothermal performance, thermal conductivity and leakage prevention ability of the phase change material, and has stronger latent heat storage energy for solar energy. As can be seen from the comparison of embodiments 1, 7 and comparative examples 1-4, compared with other non-carbon-based thermal conductive materials, the preparation method of the present application is treated with hydrochloric acid dopamine and carbon-based material in turn, and hydrochloric acid dopamine is used as a connecting bridge between foam metal and carbon-based material, which can stably adsorb more carbon-based material on the surface of foam metal; in particular, hydrochloric acid dopamine is used with carbon nanotubes, and the final obtained phase change composite material has more excellent photothermal performance.

[0105] As can be seen from the comparison of embodiments 1-4 and comparative examples 1-2 and 4, the higher the content of hydrochloric acid dopamine, the more polydopamine is generated, which can adsorb more carbon nanotubes on the surface of the foam nickel, not only improving the photothermal conversion performance, but also preventing the leakage of the phase change material, ensuring enough phase change material for heat storage, and preferably the temperature can reach 85℃ after 268 s. But as can be seen from the comparison of embodiment 4, too much hydrochloric acid dopamine should also be avoided, which may be because too much hydrochloric acid dopamine makes the viscosity of the foam metal too large, which increases the agglomeration of carbon nanotubes, and then affects the subsequent loading of the phase change material, affecting the latent heat storage performance.

[0106] Based on the disclosure and teaching of the above specification, those skilled in the art of the present application can also make changes and modifications to the above embodiments. Therefore, the present application is not limited to the above specific embodiments, and any obvious improvements, replacements or modifications made by those skilled in the art on the basis of the present application all belong to the protection scope of the present application. In addition, although some specific terms are used in the specification, these terms are only for convenience of explanation and do not constitute any limitation on the present application.

Claims

1. A method for preparing a modified foam metal phase change composite material, characterized in that: The following steps are involved: S1. placing the foamed metal into a buffer solution containing dopamine hydrochloride, stirring and mixing, and drying to obtain a pretreated foamed metal; S2, immersing the pretreated foam metal obtained in step S1 in a dispersion of a carbon-based material, and drying to obtain a modified foam metal; S3, placing the modified foam metal obtained in step S2 into a molten phase change material for vacuum impregnation, and obtaining a modified foam metal phase change composite material after cooling; The carbon-based material is multi-walled carbon nanotubes or graphene.

2. The method for preparing a modified foam metal phase change composite material according to claim 1, characterized in that: The foam metal includes at least one of foam nickel, foam copper, and foam aluminum, and the phase change material is polyethylene glycol.

3. The method for preparing a modified foam metal phase change composite material according to claim 1, characterized in that: In step S1, the concentration of dopamine hydrochloride is 3-9 g / mol; the mass ratio of the foam metal to dopamine hydrochloride is 3.55:(1.8-5.4).

4. The method for preparing a modified foam metal phase change composite material according to claim 1 or 3, characterized in that: In step S1, the buffer solution in the dopamine hydrochloride-containing buffer solution is a tris-hydrochloric acid buffer solution; the pH value of the tris-hydrochloric acid buffer solution is 8-9; and the foam metal is stirred and mixed in the dopamine hydrochloride-containing buffer solution for 10-20 hours.

5. The method for preparing a modified foam metal phase change composite material according to claim 1, characterized in that: The mass ratio of the carbon-based material to dopamine hydrochloride is 10:(9~27).

6. The method for preparing a modified foam metal phase change composite material according to claim 1 or 5, characterized in that: In step S2, the dispersion liquid containing the carbon-based material includes multi-walled carbon nanotubes and a surface dispersant, and the mass ratio of the multi-walled carbon nanotubes to the surface dispersant is (80-120):1; the surface dispersant is at least one of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, cetyltrimethylammonium bromide and sodium cholate.

7. The method for preparing a modified foam metal phase change composite material according to claim 1 or 5, characterized in that: In step S2, the pretreated metal foam is repeatedly immersed in the dispersion of the carbon-based material and dried in sequence, the number of repetitions is 3 to 6 times, and the time of each immersion is 10 to 20 minutes.

8. The method for preparing a modified foam metal phase change composite material according to any one of claims 1 to 3, characterized in that: In step S3, the mass ratio of the phase change material to dopamine hydrochloride is 275:(9-27).

9. The method for preparing a modified foam metal phase change composite material according to claim 8, characterized in that: In step S3, the phase change material is transformed into a molten state at 90-100° C. and maintained at this temperature for vacuum impregnation of the modified foam metal for 3-5 hours.

10. A modified foam metal phase change composite material, characterized in that: The modified foam metal phase change composite material is prepared by the preparation method of any one of claims 1 to 9.

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