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

Abstract

The invention 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, putting foam metal into a buffer solution containing dopamine hydrochloride, stirring, mixing and drying to obtain pretreated foam metal; s2, the pretreated foam metal obtained in the step S1 is put into dispersion liquid containing a carbon-based material to be soaked and dried, and modified foam metal is obtained; and S3, the modified foam metal obtained in the step S2 is put into a molten phase change material for vacuum impregnation, and the modified foam metal phase change composite material is obtained after cooling. According to the preparation method, firstly, the foam metal is endowed with certain viscosity and hydrophilic performance through treatment of the polydopamine, the polydopamine serves as a bridge between the foam metal and the carbon nanotubes, the carbon-based material can be firmly attached to the foam metal through retreatment, adsorption of the phase-change material is enhanced, and the leakage-proof capacity is improved; meanwhile, the photo-thermal conversion capability and the heat-conducting property of the material are also improved.

Description

Technical Field

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

[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 the charging and discharging process. Using LHS to convert and store solar energy can solve the above problems of solar energy. The combination of the two has a broader application prospect.

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

[0004] In view of this, it is indeed necessary to provide a technical solution to the above problems. Summary of the invention

[0005] One of the purposes of the present invention is to provide a method for preparing a modified foam metal phase change composite material in view of the deficiencies in the prior art, so as to solve the problem that the current foam metal alone is not sufficient to prevent the leakage of organic solid-liquid phase change material (PCM) and the thermal resistance is also large during heat transfer.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing a modified foam metal phase change composite material comprises the following steps:

[0008] S1, placing the foamed metal into a buffer solution containing dopamine hydrochloride, stirring and mixing, and drying to obtain a pretreated foamed metal;

[0009] S2, immersing the pretreated foam metal obtained in step S1 into a dispersion of a carbon-based material, and drying to obtain a modified foam metal;

[0010] 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.

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

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

[0013] Preferably, in step S1, the buffer solution in the buffer solution containing dopamine hydrochloride is tris(hydroxymethylaminomethane)-hydrochloric acid buffer solution; the pH value of the tris(hydroxymethylaminomethane)-hydrochloric acid buffer solution is 8-9; and the time for stirring and mixing the foam metal in the buffer solution containing dopamine hydrochloride is 10-20 hours.

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

[0015] Preferably, in step S2, the dispersion of 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 dodecylbenzene sulfonate, sodium dodecyl sulfate, hexadecyltrimethylammonium bromide and sodium cholate.

[0016] Preferably, in step S2, the pretreated metal foam is repeatedly immersed and dried in the dispersion liquid containing the carbon-based material, the number of repetitions is 3 to 6 times, and the time of each immersion is 10 to 20 minutes.

[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 transformed into a molten state at 90-100° C., and the modified foam metal is vacuum impregnated at this temperature for 3-5 hours.

[0019] The second object of the present invention is to provide a modified metal foam phase change composite material, which is prepared by the above-mentioned preparation method of the modified metal foam phase change composite material.

[0020] The beneficial effects of the present invention are as follows: the preparation method provided by the present invention first treats the foam metal with polydopamine, and the polydopamine is rich in functional groups such as catechol, which gives the foam metal a certain viscosity and hydrophilicity, and can act as a "bridge" between the foam metal and the carbon nanotubes. Then, the carbon-based material is loaded on the foam metal for modification. Thanks to the aforementioned pretreatment of polydopamine, the carbon-based material can be firmly attached to the foam metal. The firm adhesion of the carbon-based material can, on the one hand, enhance the adsorption of the phase change material and improve the anti-leakage ability of the phase change composite material. On the other hand, the carbon-based material increases the contact area between the phase change material and the modified foam metal, which can enhance the light-to-heat conversion ability and thermal conductivity of the phase change composite material, and solves the current problem that the foam metal alone is not enough to prevent the leakage of the phase change material, and the thermal resistance is also large during the heat transfer process. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a morphology distribution diagram of the initial nickel foam in Example 1 of the present invention.

[0022] Figure 2 This is a morphology distribution diagram of nickel foam after treatment with dopamine hydrochloride in Example 1 of the present invention.

[0023] Figure 3 This is a morphology distribution diagram of nickel foam modified by dopamine hydrochloride and carbon nanotubes in Example 1 of the present invention.

[0024] Figure 4 This is a comparison chart of the light-to-heat conversion test of Examples 1 to 3 of the present invention and Comparative Examples 1 to 2. DETAILED DESCRIPTION

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

[0026] The present invention provides a method for preparing a modified foam metal phase change composite material, comprising the following steps:

[0027] S1, placing the foamed metal into a buffer solution containing dopamine hydrochloride, stirring and mixing, and drying to obtain a pretreated foamed metal;

[0028] S2, immersing the pretreated foam metal obtained in step S1 into a dispersion of a carbon-based material, and drying to obtain a modified foam metal;

[0029] 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.

[0030] The phase change composite material provided by the present invention modifies the foam metal and then uses it to load the phase change material, which effectively enhances the stability of the load of the phase change material on the foam metal, and solves the problem that the conventional modified foam metal cannot effectively prevent the leakage of the phase change material due to the large pore size, resulting in a low load of the phase change material. Specifically, for the modification of the foam metal, it is first mixed with a buffer solution containing dopamine hydrochloride, so that the generated polydopamine is loaded on the foam metal. The polydopamine can give the foam metal a certain viscosity and hydrophilicity, and as a "bridge" between the foam metal and the carbon-based material, it can effectively firmly attach the carbon-based material to the foam metal, providing a basis for the subsequent loading of the phase change material.

[0031] Among them, the carbon-based material preferably uses multi-walled carbon nanotubes, which have abundant heat transfer channels, can achieve effective phonon transmission and extensive solar light absorption, thereby further improving the light-to-heat conversion capacity and thermal conductivity of the phase change composite material.

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

[0033] The present invention preferably uses polyethylene glycol as the phase change material, which has the advantages of large phase change latent heat, wide phase change range, and low price on the one hand, and good matching with the modified foam metal of the present invention on the other hand, effectively improving the anti-leakage ability of the phase change composite material.

[0034] The foam metal is cleaned and pre-treated, and the foam metal 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 to 9 g / mol; the mass ratio of dopamine hydrochloride to nickel foam is 3.55: (1.8 to 5.4). The higher the concentration of dopamine hydrochloride, the more polydopamine is generated, and more carbon-based materials can be adsorbed on the surface of the foam metal, and the load firmness of the carbon-based material is also better, which can not only increase the load of subsequent phase change materials, but also improve the photothermal conversion ability of phase change composite materials. Specifically, the concentration of dopamine hydrochloride includes but is not limited to 3g / mol, 4g / mol, 5g / mol, 6g / mol, 7g / mol, 8g / mol, 9g / mol; the mass ratio of dopamine hydrochloride to nickel foam can be 3.55: (1.8 to 2.7), 3.55: (2.7 to 3.6), 3.55: (3.6 to 4.5) or 3.55: (4.5 to 5.4).

[0036] The time for the foam metal to be stirred and mixed in the buffer solution containing dopamine hydrochloride is 10 to 20 hours. Relatively speaking, the longer the foam metal is mixed in the buffer solution, the better the pretreatment effect of the generated polydopamine on the foam metal.

[0037] The buffer solution in the buffer solution containing dopamine hydrochloride is a Tris-HCl buffer solution; the pH value of the Tris-HCl buffer solution is 8-9.

[0038] The mass ratio of dopamine hydrochloride to tris(hydroxymethyl)aminomethane may be (2.475-7.43):1, such as specifically including but 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 may 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 accept the load. However, excessive carbon-based material loading 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 experimentally verified that the mass ratio of the two is controlled within the above range. On the one hand, it avoids the problem of excessive carbon-based material loading affecting its firmness, and on the other hand, it also avoids the problem of too little carbon-based material failing to effectively improve the leakage of the phase change material.

[0040] In some embodiments, in step S2, the dispersion liquid containing carbon-based materials 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 easy to form agglomerates, and the viscosity of the foamed metal increases after being treated with dopamine hydrochloride. Before the pre-treated foamed metal is impregnated, the surface dispersant is first added thereto to disperse it more evenly, which is more conducive to uniformly adsorbing the multi-walled carbon nanotubes on the surface of the foamed metal, so as to ensure that the subsequent phase change material is uniformly adsorbed on the surface of the modified foamed metal.

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

[0042] In some embodiments, in step S2, the pretreated foam metal is repeatedly immersed and dried in a dispersion containing carbon-based materials, the number of repetitions is 3 to 6 times, and the time of each immersion is 10 to 20 minutes. The present invention adopts a multiple immersion method to avoid the aggregation of more carbon-based materials at the same time and increase their agglomeration, and can more evenly load more carbon-based materials on the foam metal, which can not only further improve the thermal conductivity, but also lay the foundation for the subsequent uniform loading of more phase change materials. Thanks to the modification of polydopamine and carbon nanotubes, the phase change material load is more but can prevent its 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). On the basis of controlling the mass ratio of the carbon-based material to dopamine hydrochloride, the mass ratio of the phase change material to dopamine hydrochloride is adjusted within the above range to ensure that relatively more phase change material is firmly loaded on the foam metal without leakage.

[0044] In some embodiments, in step S3, the phase change material is transformed into a molten state at 90-100° C., and the modified foam metal is vacuum impregnated for 3-5 hours while maintaining the temperature. The molten phase change material increases its contact area with the foam metal by adopting the vacuum impregnation method under the above conditions, and with the modification of the aforementioned carbon-based material, more phase change material is firmly loaded on the foam metal. When the latent heat of solar energy is subsequently stored, the heat storage capacity is also stronger and more durable, which broadens the application field of solar energy.

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

[0046] Example 1

[0047] A method for preparing a modified foam metal phase change composite material comprises the following steps:

[0048] (1) Selecting a nickel foam with a size of 2.2 cm×2.2 cm×1.0 mm as the metal foam, using 40 ml of anhydrous ethanol and 40 ml of deionized water to ultrasonically clean the nickel foam to remove the oil stains that may exist on the surface or in the pores of the nickel foam, and then placing the nickel foam in a vacuum dryer at 80° C. to obtain the metal foam to be modified;

[0049] (2) Buffer containing dopamine hydrochloride: prepare a 10 mmol / L tris (hydroxymethyl)aminomethane (Tris) solution, adjust the solution pH to 8.5 with dilute hydrochloric acid to prepare a Tris-HCl buffer, then add 0.18 g of dopamine hydrochloride at a concentration of 3 g / mol and stir for 2 min to prepare 60 ml of solution; wherein the mass ratio of dopamine hydrochloride to Tris is 2.475:1;

[0050] (3) placing the foamed metal to be modified in a buffer solution containing dopamine hydrochloride, stirring and mixing at room temperature for 16 hours, and drying to obtain a pretreated foamed metal; wherein the mass ratio of the foamed metal to the dopamine hydrochloride is 3.55:1.8;

[0051] (4) preparing a dispersion of carbon-based materials: preparing 20 mL of a 10 g / L multi-walled carbon nanotube dispersion, adding 1 wt % sodium dodecylbenzene sulfonate thereto, and performing ultrasonic treatment for 1 min to uniformly disperse the dispersion; wherein the mass ratio of the multi-walled carbon nanotubes to the sodium dodecylbenzene sulfonate is 100:1; and the mass ratio of the multi-walled carbon nanotubes to dopamine hydrochloride is 10:9;

[0052] (5) placing the pretreated foamed metal into a dispersion of the carbon-based material and ultrasonically impregnating it for 15 min, then vacuum drying it at 85° C. for 30 min, and repeating the impregnation and drying steps four times in sequence to obtain a modified foamed metal;

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

[0054] Example 2

[0055] The difference from Example 1 is that the amount of dopamine hydrochloride added in the preparation of the dopamine hydrochloride-containing buffer solution is 0.36 g, the concentration is 6 g / mol, the corresponding mass ratio of the foam metal to dopamine hydrochloride is 3.55:3.6, the mass ratio of the multi-walled carbon nanotubes 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 in Example 1 and will not be described again here.

[0057] Example 3

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

[0059] The rest is the same as in Example 1 and will not be described again here.

[0060] Example 4

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

[0062] The rest is the same as in Example 1 and will not be described again here.

[0063] Example 5

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

[0065] (1) A copper foam with a size of 2.2 cm×2.2 cm×1.0 mm was selected as the metal foam, and the copper foam was ultrasonically cleaned with 40 ml of anhydrous ethanol and 40 ml of deionized water to remove the oil stains that may exist on the surface or in the pores, and then vacuum dried at 80° C. to obtain the metal foam to be modified;

[0066] (2) Buffer containing dopamine hydrochloride: 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 at a concentration of 4 mol / L and stir for 2 min to prepare a 60 ml solution; wherein the mass ratio of dopamine hydrochloride to Tris is 3.3:1;

[0067] (3) placing the foamed metal to be modified in a buffer solution containing dopamine hydrochloride, stirring and mixing at room temperature for 20 hours, and drying to obtain a pretreated foamed metal; wherein the mass ratio of the foamed metal to the dopamine hydrochloride is 3.55:2.4;

[0068] (4) preparing a dispersion of carbon-based materials: preparing 20 mL of a 10 g / L multi-walled carbon nanotube dispersion, adding 1.25 wt % sodium dodecylbenzene sulfonate thereto, and performing ultrasonication for 1 min to uniformly disperse the dispersion; wherein the mass ratio of the multi-walled carbon nanotubes to the sodium dodecylbenzene sulfonate is 80:1; and the mass ratio of the multi-walled carbon nanotubes to dopamine hydrochloride is 10:12;

[0069] (5) placing the pretreated foamed metal into a dispersion of the carbon-based material and ultrasonically impregnating it for 20 min, then vacuum drying it at 85° C. for 30 min, and repeating the impregnation and drying steps three times in sequence to obtain a modified foamed metal;

[0070] (6) Polyethylene glycol was used as the phase change material. The mass ratio of polyethylene glycol to dopamine hydrochloride was 275:12. 5.5 g of polyethylene glycol was weighed into a beaker and heated to 90 °C in a heating box. When the polyethylene glycol was completely melted, the modified foam metal was put in. The mixture was vacuum filtered and taken out after immersion for 5 h. The mixture was 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 comprises the following steps:

[0073] (1) A foam aluminum with a size of 2.2 cm×2.2 cm×1.0 mm was selected as the foam metal, and 40 ml of anhydrous ethanol and 40 ml of deionized water were used to ultrasonically clean the foam aluminum to remove the oil stains that may exist on the surface or in the pores, and then the foam aluminum was placed in a vacuum dryer at 80° C. to obtain the foam metal to be modified;

[0074] (2) Buffer containing dopamine hydrochloride: prepare a 10 mmol / L tris (hydroxymethyl)aminomethane (Tris) solution, adjust the solution pH to 9 with dilute hydrochloric acid to prepare a Tris-HCl buffer, then add 0.30 g of dopamine hydrochloride at a concentration of 5 mol / L and stir for 3 min to prepare a 60 ml solution; wherein the mass ratio of dopamine hydrochloride to Tris is 4.125:1;

[0075] (3) placing the to-be-modified foamed metal into a buffer solution containing dopamine hydrochloride, stirring and mixing at room temperature for 10 hours, and drying to obtain a pretreated foamed metal; wherein the mass ratio of the foamed metal to the dopamine hydrochloride is 3.55:3.0;

[0076] (4) preparing a dispersion of carbon-based materials: preparing 20 mL of a 10 g / L multi-walled carbon nanotube dispersion, adding 0.83 wt % sodium dodecylbenzene sulfonate thereto, and performing ultrasonication for 1 min to uniformly disperse the dispersion; wherein the mass ratio of the multi-walled carbon nanotubes to the sodium dodecylbenzene sulfonate is 120:1; and the mass ratio of the multi-walled carbon nanotubes to dopamine hydrochloride is 10:15;

[0077] (5) placing the pretreated foamed metal into a dispersion of the carbon-based material and ultrasonically impregnating it for 10 min, then vacuum drying it at 85° C. for 30 min, and repeating the impregnation and drying steps six times in sequence to obtain a modified foamed metal;

[0078] (6) Polyethylene glycol was used as the phase change material. The mass ratio of polyethylene glycol to dopamine hydrochloride was 275:15. 5.5 g of polyethylene glycol was weighed into a beaker and heated to 100 °C in a heating box. When the polyethylene glycol was completely melted, the modified foam metal was placed in the beaker and vacuum filtered. After immersion for 3 h, the modified foam aluminum phase change composite material was taken out and cooled at room temperature for 2 h 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 in Example 1 and will not be described again here.

[0082] Comparative Example 1

[0083] A phase change material is prepared by weighing 5.5 g of polyethylene glycol and pressing it into a rectangular tablet of 2.2 cm×2.2 cm×1.0 mm using a tablet press.

[0084] Comparative Example 2

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

[0086] (1) Selecting a nickel foam with a size of 2.2 cm×2.2 cm×1.0 mm as the metal foam, using 40 ml of anhydrous ethanol and 40 ml of deionized water to ultrasonically clean the nickel foam to remove possible oil stains on the surface or in the pores of the nickel foam, and then placing the nickel foam in a vacuum dryer at 80° C. to obtain the metal foam;

[0087] (2) Using polyethylene glycol as the phase change material, weigh 5.5 g of polyethylene glycol into a beaker, heat it to 95°C in a heating box, and put the cleaned foam metal into it when it is completely melted. Vacuum filter and soak it for 4 hours before taking it out. Cool it at room temperature for 2 hours to obtain a foam nickel phase change composite material.

[0088] Comparative Example 3

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

[0090] (1) Selecting a nickel foam with a size of 2.2 cm×2.2 cm×1.0 mm as the metal foam, using 40 ml of anhydrous ethanol and 40 ml of deionized water to ultrasonically clean the nickel foam to remove the oil stains that may exist on the surface or in the pores of the nickel foam, and then placing the nickel foam in a vacuum dryer at 80° C. to obtain the metal foam to be modified;

[0091] (2) Buffer containing dopamine hydrochloride: prepare a 10 mmol / L tris (hydroxymethyl)aminomethane (Tris) solution, adjust the solution pH to 8.5 with dilute hydrochloric acid to prepare a Tris-HCl buffer, then add 0.18 g of dopamine hydrochloride at a concentration of 3 mol / L and stir for 2 min to prepare a 60 ml solution; wherein the mass ratio of dopamine hydrochloride to Tris is 2.475:1;

[0092] (3) placing the to-be-modified foam metal in a buffer solution containing dopamine hydrochloride, stirring and mixing at room temperature for 16 hours, and drying to obtain a pretreated foam metal as a modified foam metal, wherein the mass ratio of the foam metal to the dopamine hydrochloride is 3.55:1.8;

[0093] (4) Polyethylene glycol was used as the phase change material. The mass ratio of polyethylene glycol to dopamine hydrochloride was 275:9. 5.5 g of polyethylene glycol was weighed into a beaker and heated to 95 °C in a heating box. When the polyethylene glycol was completely melted, the modified foam metal was put in. The mixture was vacuum filtered and taken out after immersion for 4 h. The modified foam nickel phase change composite material was obtained.

[0094] Comparative Example 4

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

[0096] (1) Selecting a nickel foam with a size of 2.2 cm×2.2 cm×1.0 mm as the foam metal, using 40 ml of anhydrous ethanol and 40 ml of deionized water to ultrasonically clean the nickel foam to remove the oil stains that may exist on the surface or in the pores of the nickel foam, and then placing it in a vacuum dryer at 80° C. to obtain the pretreated foam metal;

[0097] (2) preparing a dispersion of carbon-based materials: preparing 20 mL of a 10 g / L multi-walled carbon nanotube dispersion, adding 1 wt % sodium dodecylbenzene sulfonate thereto, and ultrasonicating for 1 min to disperse uniformly; wherein the mass ratio of the multi-walled carbon nanotubes to the sodium dodecylbenzene sulfonate is 100:1;

[0098] (3) placing the pretreated foamed metal into a dispersion of a carbon-based material and ultrasonically impregnating it for 10 min, then vacuum drying it at 85° C. for 30 min, and repeating the impregnation and drying steps four times in sequence to obtain a carbon nanotube-loaded foamed metal;

[0099] (4) Using polyethylene glycol as a phase change material, weigh 5.5 g of polyethylene glycol into a beaker, heat it to 95°C in a heating box, and put the carbon nanotube-loaded foam metal into it when it is completely melted. Vacuum filter, soak for 4 hours, then take it out and cool it at room temperature for 2 hours to obtain a modified nickel foam phase change composite material.

[0100] The modified nickel foam phase change composite materials obtained in the above examples 1 to 7 and comparative examples 1 to 4 were subjected to a light-to-heat conversion test. The samples were pressed into a rectangular square sheet of 1.0 cm × 1.0 cm × 1.0 mm and placed on a light-to-heat test platform. The light intensity was 400 mW / cm 2 The xenon lamp was used as a simulated sunlight source to test the temperature change in a 540s period. The test results are shown in Table 1 and Figures 1 to 4 shown.

[0101] Table 1 Photothermal conversion test results

[0102]

[0103]

[0104] From the above Table 1 and Figures 1 to 4 It can be seen that the phase change composite material prepared by the present invention improves the photothermal performance, thermal conductivity and anti-leakage ability of the phase change material by modifying the foam metal with polydopamine and carbon-based materials, and has stronger latent heat storage energy for solar energy. Among them, it can also be seen from the comparison of Examples 1 and 7 and Comparative Examples 1 to 4 that compared with other non-carbon-based thermal conductive materials, the preparation method of the present invention is treated with dopamine hydrochloride and carbon-based materials in sequence. Dopamine hydrochloride serves as a connecting bridge between the foam metal and the carbon-based material, and can stably adsorb more carbon-based materials on the surface of the foam metal; in particular, dopamine hydrochloride is used in combination with carbon nanotubes, and the phase change composite material finally obtained has more excellent photothermal and other properties.

[0105] Among them, it can be seen from the comparison between Examples 1 to 4 and Comparative Examples 1 to 2 and 4 that the higher the content of dopamine hydrochloride, the more polydopamine is generated, and more carbon nanotubes can be adsorbed on the surface of nickel foam, which not only improves the light-to-heat conversion performance, but also prevents the leakage of phase change materials, ensuring sufficient phase change materials for heat storage, and preferably the temperature can reach 85°C after 268s. However, it can be seen from the comparison of Example 4 that too much dopamine hydrochloride should also be avoided, which may be because too much dopamine hydrochloride makes the viscosity of the foam metal too large and increases the amount of carbon nanotube agglomeration, thereby affecting the subsequent load of the phase change material and affecting the latent heat storage performance.

[0106] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs can also change and modify the above embodiment. Therefore, the present invention is not limited to the above specific embodiment, and any obvious improvement, replacement or modification made by those skilled in the art on the basis of the present invention belongs to the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

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 into 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.

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 buffer solution containing dopamine hydrochloride is tris(hydroxymethylaminomethane)-hydrochloric acid buffer solution; the pH value of the tris(hydroxymethylaminomethane)-hydrochloric acid buffer solution is 8-9; and the time for stirring and mixing the foam metal in the buffer solution containing dopamine hydrochloride is 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 of 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 dodecylbenzene sulfonate, sodium dodecyl sulfate, hexadecyltrimethylammonium 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 foamed metal is repeatedly immersed and dried in the dispersion liquid containing the carbon-based material, the number of repetitions is 3 to 6 times, and the time of each immersion is 10 to 20 minutes.

8. A 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 the modified foam metal is vacuum impregnated at this temperature 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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