CN107523276A - A kind of high temperature microcapsules alusil alloy phase-change material and preparation method thereof - Google Patents

Abstract

The invention relates to a high-temperature microcapsule aluminum-silicon alloy phase change material and a preparation method thereof. The technical solution is: boil the aluminum-silicon alloy at 0.5-2 MPa for 0.1-5 hours, filter, and dry at 50-200°C for 12-24 hours; then put the dried aluminum-silicon alloy into a high-temperature furnace, Under an oxygen atmosphere, heat up to 700-1100°C at a rate of 1-30°C/min, keep warm for 0.5-6 hours, and cool with the furnace; out of the furnace, ultrasonically disperse, and dry at 50-100°C to obtain high-temperature microcapsules of aluminum-silicon alloy phase change materials. The aluminum-silicon alloy: the Al content is 60-95wt%, the Si content is 5-40wt%, the particle size is 1-100μm, and the purity is greater than 95wt%. The invention has the characteristics of simple process and low cost, and the prepared high-temperature microcapsule aluminum-silicon alloy phase change material has small particle size, high service temperature and high energy storage density.

Description

A kind of high-temperature microcapsule aluminum-silicon alloy phase change material and preparation method thereof

technical field

The invention belongs to the technical field of phase change energy storage materials. In particular, it relates to a high-temperature microcapsule aluminum-silicon alloy phase change material and a preparation method thereof.

Background technique

Phase change materials (PCMs) or phase change energy storage materials, which belong to the category of energy materials, are widely used in construction, textiles and solar power generation, and have received more and more attention in the field of energy storage. Because aluminum-based metal materials, especially aluminum-silicon alloy materials, have a suitable phase transition temperature, high energy storage density, good thermal stability and excellent thermal conductivity, they are very suitable as energy storage materials for solar power generation. But like other metal-based materials, the liquid phase at high temperature is highly corrosive and accompanied by high volume expansion, so it is very important to find suitable packaging materials. The silicon alloy phase and the microcapsule phase change material introduce microcapsule technology into the phase change material, which increases the heat transfer area, prevents the reaction of the phase change material with the surrounding environment, controls the volume change of PCMs during the phase transition, and improves the phase transition. The use efficiency of materials has broad application prospects.

Domestic preparation methods of high-temperature phase-change capsule materials include:

"A method for preparing a core-shell structure composite phase change material by modifying an aluminum alloy with a coupling agent" (CN 102746831 A), the scheme first uses aluminum sec-butoxide to prepare an alumina sol, and uses a silane coupling agent to prepare an aluminum-silicon alloy powder Perform surface modification. Then it is mixed with alumina sol and gelled, and the core-shell structure product is obtained after heat treatment, but the cost is high, and it is difficult to produce and apply on a large scale.

"A high-temperature metal phase-change heat storage material and its preparation method" (CN 103273062 A), in which the copper-based metal phase-change material is degreased and pickled, then placed in a barrel hard chromium plating device and taken out after chrome plating; cleaning , After pickling, put it into a barrel nickel plating device for nickel plating to obtain a core-shell material with a diameter of about 0.1-6mm and a shell thickness of about 10-4000um. However, the energy storage density of copper base is much smaller than that of aluminum base, and its latent heat value is difficult to increase.

"A preparation method of high-temperature phase-change heat storage material with core-shell structure" (CN 106367035 A), in this scheme, CH ₃ COONa, AlCl ₃ and NaOH are respectively dissolved in absolute ethanol, and then AlCl ₃ ethanol solution and NaOH ethanol _The solution was dropped into the CH3COONa ethanol solution at the same time, and the mixture was transferred to a high-pressure reactor to be heated. After cooling, the precipitate was filtered, washed, dried, and roasted to obtain the product of _Al2O3 coated _NaCl ; but the selectivity was poor, and the coated The rate is low and the process is not easy to control.

"A core-shell structure nano high-temperature heat storage material, its preparation method and application" (CN 103509528 A), the scheme first coats copper with silver to prepare Cu/Ag nanoparticles, and then coats Cu/Ag with SiO ₂ Cu/Ag- _SiO2 nanoparticles are prepared from the nanoparticles, and finally the silver in the Cu/Ag- _SiO2 nanoparticles is removed to obtain the Cu/ _SiO2 nanometer high-temperature heat storage material. But the latent heat value of the product is low, and the cost is very high.

"An inorganic non-metallic cladding high-temperature phase-change heat storage microcapsule and its preparation method" (CN 105855537 A), in which metal phase-change material microspheres with a diameter of 500-2000um are loaded into high-temperature fluidized bed chemical vapor deposition device, the reaction gas is a mixture of propylene and argon, and after heat treatment, a loose pyrolytic carbon layer with a density of 0.5-1.5/ ^cm3 is formed on the surface of the metal ball; then the reaction gas of the high-temperature fluidized bed chemical vapor deposition device is switched to The mixed gas of propylene and argon can obtain a dense pyrolytic carbon layer with a density of 1.8-2/cm ³ on the surface after heat treatment, and finally lower the temperature and switch the gas to argon to obtain the product. However, the process flow is complicated and the process control is poor.

Foreign researches on high-temperature phase-change capsule materials include:

For example, the method of boehmite-chemical aluminum-silicon alloy (T. Nomura, N. Sheng, C. Zhu, G. Saito, D.Hanzaki, T. Hiraki, T. Akiyama, Microencapsulated phase change materials with high heat capacity and high cyclic durability for high-temperature thermalenergy storage and transportation, Applied Energy, 188 (2017) 9-18), a microcapsule phase change material of α-Al ₂ O ₃ coated aluminum-silicon alloy was formed after heat treatment in a pure oxygen atmosphere; but the pure Oxygen atmosphere has a high risk factor, and it is difficult to popularize and use it at high temperature.

There are also methods using borate glass as shell material, nitrates and metallic lead as phase change materials and the use of hand glass blowing (P. Gimenez-Gavarrell, S. Fereres, Glass encapsulated phase change materials for high temperature thermal energy storage , RenewableEnergy, 107 (2017) 497-507), first prepared hollow glass spheres, and then filled them with liquid phase change materials and sealed them. The diameter of the spheres prepared by this method was about 20mm, and the phase change temperature was 300-400℃ , the change of state of matter during the phase transition process can be observed by using a transparent shell. However, this method is manually operated, has poor controllability and repeatability, and does not have the value of mass production.

Another example is Mathur (Mathur, A., Kasetty, R., Oxley, J., Mendez, J. &Nithyanandam, K. Using encapsulated phase change salts for concentrated solarpower plant. Energy Procedia 49, (2013)908–915) also uses Nitrate was used as a phase change material, and a sacrificial polymer method was used to leave a vacancy between the shell and the core to offset the volume expansion during the phase change, but the technology did not mention the energy storage of the capsule Density, no industrial promotion value.

Contents of the invention

The present invention aims to overcome the defects of the prior art, and the task is to provide a method for preparing high-temperature microcapsule aluminum-silicon alloy phase change materials with simple process and low cost; the particle size of high-temperature microcapsule aluminum-silicon alloy phase change materials prepared by this method is Small size, high operating temperature and high energy storage density.

In order to achieve the above purpose, the technical scheme adopted in this experiment is: boil the aluminum-silicon alloy at 0.5-2MPa for 0.1-5h, filter, and dry at 50-200°C for 12-24h; The silicon alloy is placed in a high-temperature furnace, and in an oxygen-containing atmosphere, the temperature is raised to 700-1100°C at a rate of 1-30°C/min, kept for 0.5-6 hours, and cooled with the furnace; out of the furnace, ultrasonically dispersed, at 50-100°C drying to obtain a high-temperature microcapsule aluminum-silicon alloy phase change material.

The aluminum-silicon alloy: the Al content is 60-95wt%, the Si content is 5-40wt%, the particle size is 1-100μm, and the purity is greater than 95wt%.

The water is one of deionized water, double distilled water and ultrapure water.

The oxygen-containing atmosphere is one or a mixture of oxygen and air.

Owing to adopting above-mentioned technical scheme, the present invention has following positive effect compared with prior art:

The present invention adopts the method of boiling the aluminum-silicon alloy to form boehmite (AlOOH) on the surface of the alloy, and the boehmite is transformed into α-Al ₂ O ₃ in the heat treatment process, which prevents a large amount of leakage of the aluminum-silicon liquid phase, and a small part The leaked aluminum-silicon alloy is oxidized and fixed on the surface of the shell layer, and a new α-Al ₂ O ₃ shell layer is formed on the surface of the aluminum-silicon alloy. The prepared high-temperature microcapsule aluminum-silicon alloy phase change material can effectively prevent The aluminum-silicon liquid phase condenses into agglomerates, and the process of simply heating the aluminum-silicon alloy without boiling will cause the heat-treated sample to condense severely at high temperature and have no dispersion.

The invention only needs to heat and boil the aluminum-silicon alloy, filter, dry and heat-treat, so the process is simple and the cost is low; the particle size of the prepared high-temperature microcapsule aluminum-silicon alloy phase change material is 1-100 μm, and the maximum energy storage density is 200J/ g, so the particle size is small and the energy storage density is large, which has high industrial promotion value.

Therefore, the invention has the characteristics of simple process and low cost, and the prepared high-temperature microcapsule aluminum-silicon alloy phase change material has small particle size, high service temperature and high energy storage density.

Description of drawings

Fig. 1 is the XRD figure of a kind of high-temperature microcapsule aluminum-silicon alloy phase-change material prepared by the present invention;

Fig. 2 is the SEM picture of the high-temperature microcapsule aluminum-silicon alloy phase-change material shown in Fig. 1;

Fig. 3 is the SEM picture of the cross-section of the high-temperature microcapsule aluminum-silicon alloy phase-change material shown in Fig. 1;

Fig. 4 is a DSC-TG diagram of the high-temperature microcapsule aluminum-silicon alloy phase change material shown in Fig. 1 .

detailed description

The present invention will be further described below in combination with specific embodiments, which are not intended to limit the protection scope thereof.

In this specific embodiment, the aluminum-silicon alloy has an Al content of 60-95 wt%, a Si content of 5-40 wt%, a particle size of 1-100 μm, and a purity greater than 95 wt%. No more details will be given in the embodiments.

Example 1

A high-temperature microcapsule aluminum-silicon alloy phase change material and a preparation method thereof. The preparation method described in this example is: boil the aluminum-silicon alloy at 0.5-2 MPa for 0.1-2 hours, filter, and dry at 50-200°C for 12-24 hours; then place the dried aluminum-silicon alloy in high temperature In the furnace, in an oxygen-containing atmosphere, the temperature is raised to 700-950°C at a rate of 1-15°C/min, kept for 0.5-3 hours, and cooled with the furnace; out of the furnace, ultrasonically dispersed, and dried at 50-100°C to obtain high temperature Microcapsule aluminum-silicon alloy phase change material.

The water is deionized water.

The oxygen-containing atmosphere is oxygen.

The high-temperature microcapsule aluminum-silicon alloy phase change material prepared in this example has a particle size of 1-100 μm and an energy storage density of 50-130 J/g.

Example 2

A high-temperature microcapsule aluminum-silicon alloy phase change material and a preparation method thereof. The preparation method described in this example is: boil the aluminum-silicon alloy at 0.5-2 MPa for 1-3 hours, filter, and dry at 50-200°C for 12-24 hours; then place the dried aluminum-silicon alloy in high temperature In the furnace, in an oxygen-containing atmosphere, the temperature is raised to 750-1000°C at a rate of 5-20°C/min, kept for 1.5-4 hours, and cooled with the furnace; out of the furnace, ultrasonically dispersed, and dried at 50-100°C to obtain high-temperature Microcapsule aluminum-silicon alloy phase change material.

Described water is double distilled water.

The oxygen-containing atmosphere is air.

The high-temperature microcapsule aluminum-silicon alloy phase change material prepared in this embodiment: the particle size is 1-100 μm, and the energy storage density is 100-180 J/g.

Example 3

A high-temperature microcapsule aluminum-silicon alloy phase change material and a preparation method thereof. The preparation method described in this example is: boil the aluminum-silicon alloy at 0.5-2 MPa for 2-4 hours, filter, and dry at 50-200°C for 12-24 hours; then place the dried aluminum-silicon alloy in high temperature In the furnace, in an oxygen-containing atmosphere, the temperature is raised to 800-1050°C at a rate of 10-25°C/min, kept for 2.5-5 hours, and cooled with the furnace; out of the furnace, ultrasonically dispersed, and dried at 50-100°C to obtain high-temperature Microcapsule aluminum-silicon alloy phase change material.

The water is ultrapure water.

The oxygen-containing atmosphere is a mixed atmosphere of oxygen and air.

The high-temperature microcapsule aluminum-silicon alloy phase change material prepared in this embodiment: the particle size is 1-100 μm, and the energy storage density is 120-200 J/g.

Example 4

A high-temperature microcapsule aluminum-silicon alloy phase change material and a preparation method thereof. The preparation method described in this example is: boil the aluminum-silicon alloy at 0.5-2 MPa for 3-5 hours, filter, and dry at 50-200°C for 12-24 hours; then place the dried aluminum-silicon alloy in high temperature In the furnace, in an oxygen-containing atmosphere, the temperature is raised to 850-1100°C at a rate of 15-30°C/min, kept for 3.5-6 hours, and cooled with the furnace; out of the furnace, ultrasonically dispersed, and dried at 50-100°C to obtain high-temperature Microcapsule aluminum-silicon alloy phase change material.

The water is deionized water.

The oxygen-containing atmosphere is air.

The high-temperature microcapsule aluminum-silicon alloy phase-change material prepared in this example has a particle size of 1-100 μm and an energy storage density of 80-160 J/g.

Compared with the prior art, this specific embodiment has the following positive effects:

This specific embodiment adopts the method of boiling the aluminum-silicon alloy, so that boehmite (AlOOH) is formed on the surface of the alloy, and the boehmite is transformed into α-Al ₂ O ₃ during the heat treatment process, which prevents a large amount of leakage of the aluminum-silicon liquid phase. A small part of the leaked Al-Si alloy was oxidized and fixed on the surface of the shell, and a new α-Al ₂ O ₃ shell was formed on the surface of the Al-Si alloy. The prepared high-temperature microcapsule Al-Si alloy phase change material can effectively It is necessary to effectively prevent the aluminum-silicon liquid phase from agglomerating into agglomerates, and the process of simply heating the aluminum-silicon alloy without boiling will cause the heat-treated sample to agglomerate seriously at high temperature and have no dispersibility.

The microcapsule phase change material prepared in this specific embodiment is shown in the accompanying drawings. Fig. 1 is an XRD diagram of a high-temperature microcapsule aluminum-silicon alloy phase change material prepared in Example 4; The SEM image of the capsule Al-Si alloy phase change material; Figure 3 is the SEM image of the cross-section of the high-temperature microcapsule Al-Si alloy phase change material shown in Figure 1; Figure 4 is the DSC of the high-temperature microcapsule Al-Si alloy phase change material shown in Figure 1 -TG diagram. It can be seen from Figure 1 that the main components of the manufactured product are Al, Si and α-Al ₂ O ₃ ; it can be seen from Figure 2 and Figure 3 that the microscopic appearance of the manufactured product is spherical, and the particle size is about 10um , the particle size is small, the surface is composed of flaky α-Al ₂ O ₃ , and the content is simple Al and Si; it can be seen from the cross section that the thickness of the shell is about 300nm, so the energy storage density is large. It can be seen from Figure 4 that the quality of the manufactured product remains unchanged during the DSC-TG measurement process, indicating that the coating is good and there is no leakage. From the endothermic curve, it can be concluded that the phase transition temperature of the product is 580°C, so the service temperature is high; at the same time, the latent heat value of the product can be calculated, which is 80-200J/g, so the energy storage density is high.

This specific embodiment only needs to heat and boil the aluminum-silicon alloy, filter, dry and heat-treat, so the process is simple and the cost is low; the prepared high-temperature microcapsule aluminum-silicon alloy phase change material has a particle size of 1-100 μm and a maximum energy storage density of 200J/g, so the particle size is small and the energy storage density is high, which has high industrial promotion value.

Therefore, this specific embodiment has the characteristics of simple production process and low cost, and the microcapsule phase change material prepared by this method has small particle size, high service temperature and high energy storage density.

Claims (5)

1. A method for preparing a high-temperature microcapsule aluminum-silicon alloy phase-change material, characterized in that the preparation method is: boil the aluminum-silicon alloy at 0.5-2 MPa for 0.1-5 hours, filter, and heat at 50-200°C Dry for 12-24 hours; then put the dried aluminum-silicon alloy into a high-temperature furnace, raise the temperature to 700-1100°C at a rate of 1-30°C/min in an oxygen-containing atmosphere, keep it warm for 0.5-6 hours, and cool with the furnace; out of the oven, ultrasonically dispersed, and dried at 50-100°C to prepare a high-temperature microcapsule aluminum-silicon alloy phase change material. 2. according to the preparation method of the high-temperature microcapsule aluminum-silicon alloy phase change material described in claim 1, it is characterized in that described aluminum-silicon alloy: Al content is 60～95wt%, Si content is 5～40wt%; Particle diameter is 1～100μm, the purity is greater than 95wt%. 3. according to the preparation method of high-temperature microcapsule aluminum-silicon alloy phase-change material described in claim 1, it is characterized in that described water is a kind of in deionized water, double distilled water and ultrapure water. 4. According to the preparation method of high-temperature microcapsule aluminum-silicon alloy phase change material according to claim 1, it is characterized in that the oxygen-containing atmosphere is one or a mixed gas of oxygen and air. 5. A high-temperature microcapsule aluminum-silicon alloy phase change material, characterized in that the high-temperature microcapsule aluminum-silicon alloy phase change material is the high-temperature microcapsule aluminum-silicon alloy phase change material according to any one of claims 1 to 4 The preparation method of the material is a high-temperature microcapsule aluminum-silicon alloy phase change material.