阅读说明：本技术 一种生物形态碳化硅陶瓷高温光热储存材料 (Biological form silicon carbide ceramic high-temperature photo-thermal storage material ) 是由 刘向雷 徐巧 宣益民 于 2020-11-27 设计创作，主要内容包括：本发明提出一种生物形态碳化硅陶瓷高温光热储存材料及其制备方法,该储热材料由生物形态碳化硅陶瓷骨架、氯化盐复合制成。生物形态碳化硅陶瓷是一种将熔融硅与木炭多孔前驱体高温反应生成的陶瓷材料,不同的木材前驱体可以获得具有不同孔隙率的碳化硅陶瓷骨架。相变储热材料是将氯化钠与氯化钾于球磨机中充分混合均匀并干燥制得氯化钠钾共晶盐。采用真空浸渍法将相变储热材料包覆于生物形态碳化硅陶瓷骨架使得陶瓷骨架孔隙中填充相变材料,即可得到生物形态碳化硅陶瓷高温光热储存材料。本发明制备的复合材料导热率高(116 W/mK)、光谱吸收性能高(92%)、储热密度高(453kg/kJ)的优良特性,有望推动构建清洁低碳、高效安全能源体系的发展。(The invention provides a biological form silicon carbide ceramic high-temperature photo-thermal storage material and a preparation method thereof. The biological form silicon carbide ceramic is a ceramic material generated by high-temperature reaction of molten silicon and a charcoal porous precursor, and different wood precursors can obtain silicon carbide ceramic frameworks with different porosities. The phase-change heat storage material is prepared by fully and uniformly mixing sodium chloride and potassium chloride in a ball mill and drying. And coating the phase-change heat storage material on the biological silicon carbide ceramic framework by adopting a vacuum impregnation method so as to fill the phase-change material in pores of the ceramic framework, thus obtaining the biological silicon carbide ceramic high-temperature photo-thermal storage material. The composite material prepared by the invention has the excellent characteristics of high thermal conductivity (116W/mK), high spectral absorption performance (92%) and high heat storage density (453 kg/kJ), and is expected to promote the development of constructing a clean, low-carbon, efficient and safe energy system.)

1. The biological silicon carbide ceramic high-temperature photo-thermal storage material is characterized in that: the composite phase-change heat storage material is prepared by compounding chloride salt and a porous silicon carbide framework, wherein the mass fraction of the porous silicon carbide ceramic framework accounts for 70%, the mass fraction of the chloride salt accounts for 30 +/-3%, the mass fraction of sodium chloride in the chloride salt accounts for 60 +/-1%, and the mass fraction of potassium chloride accounts for 40 +/-1%.

2. The biomorphic silicon carbide ceramic high temperature photothermal storage material of claim 1 wherein the porous biocarbon porosity is 50 ± 5%.

3. The method for preparing the biomorphic silicon carbide ceramic high-temperature photo-thermal storage material according to claim 1, which comprises the following steps:

the first step is as follows: preparing biological silicon carbide ceramic; primarily cutting wood, drying in a drying box, and then placing in a tubular furnace to heat to 900-1100 ℃ and preserving heat for 30-60 minutes; discharging, and finely cutting the carbonized precursor; placing the cut precursor in a high-temperature furnace, and reacting the cut precursor with excessive silicon for 1-4 hours at 1550-1650 ℃ in a vacuum atmosphere; then placing the ceramic in a vacuum atmosphere at 1900 +/-50 ℃ for heat preservation for 4-6 hours to obtain the porous silicon carbide ceramic in the biological form;

the second step is that: preparing a high-temperature phase-change heat storage material; weighing sodium chloride and potassium chloride according to a certain proportion, placing the mixture in a ball mill, fully mixing the mixture uniformly, and placing the mixture in a tubular furnace to be fully dried in a nitrogen atmosphere to obtain a phase-change heat storage material for later use;

the third step: preparing a biological silicon carbide ceramic high-temperature photo-thermal storage material; and (3) placing the phase change heat storage material obtained in the second step into a crucible to coat the biological silicon carbide ceramic obtained in the first step, heating to 665-675 ℃ in a tubular furnace in a vacuum atmosphere, and preserving heat for 3-4 hours to obtain the biological silicon carbide ceramic high-temperature photo-thermal storage material.

4. The method for preparing a biomorphic silicon carbide ceramic high-temperature photothermal storage material according to claim 3, wherein: in the first step, cut into length 70mm with wood, width 50mm, thickness 30 mm's cuboid, wood after preliminary cutting is placed in the drying cabinet 70 ℃ dry 2~3 days.

5. The method of claim 3, wherein the step of preparing the biomorphic silicon carbide ceramic high temperature photothermal storage material comprises: in the first step, the dried wood is placed in a tube furnace, the temperature is raised to 500 ℃ at the heating rate of 0.5 ℃/min under the protection of nitrogen, the temperature is raised to 900-1100 ℃ at the heating rate of 1 ℃/min, the temperature is kept for 30-60 minutes, and the temperature is lowered to room temperature at the cooling rate of 1 ℃/min.

6. The method of claim 3, wherein the step of preparing the biomorphic silicon carbide ceramic high temperature photothermal storage material comprises: in the first step, a punching machine and a wire cutting machine finely cut the carbonized precursor into wafers with the diameter of 12.7mm and the thickness of 3 mm; and (3) coating the cut precursor with sufficient silicon powder, placing the coated precursor in a high-temperature furnace, heating to 1550-1650 ℃ in a vacuum atmosphere, and keeping the temperature for 1-4 hours at the heating rate of less than or equal to 10 ℃/min.

7. The method of claim 3, wherein the step of preparing the biomorphic silicon carbide ceramic high temperature photothermal storage material comprises: in the first step, the silicon carbide ceramic and the redundant silicon are placed in a high-temperature furnace to be heated to 1900 +/-50 ℃, the temperature is kept for 4-6 hours in a vacuum atmosphere, and the heating rate is less than or equal to 10 ℃/min.

8. The method of claim 3, wherein the step of preparing the biomorphic silicon carbide ceramic high temperature photothermal storage material comprises: in the second step, the mass fraction of the sodium chloride and the potassium chloride accounts for 60 to 40 percent.

9. The method of claim 3, wherein the step of preparing the biomorphic silicon carbide ceramic high temperature photothermal storage material comprises: and in the second step, the rotating speed of the ball mill is 300r/min, the mixing time is 3 hours, the mixed chloride salt is placed in a tube furnace, and is dried for 2-6 hours at 90 ℃ in a nitrogen atmosphere, and then is heated to 350 ℃ and dried for 2-6 hours.

10. The method of claim 3, wherein the step of preparing the biomorphic silicon carbide ceramic high temperature photothermal storage material comprises: and in the third step, the chlorine salt obtained in the second step is placed in a crucible to coat the biological silicon carbide ceramic obtained in the first step, the biological silicon carbide ceramic is heated to 665-675 ℃ in a tubular furnace, the temperature is kept for 4 hours in a vacuum atmosphere, and the heating rate is less than or equal to 5 ℃/min.

Technical Field

The invention relates to the field of phase change heat storage materials, in particular to a heat storage material prepared by compounding biomorphic porous silicon carbide ceramic and chloride.

Background

Over 90% of the world's energy is associated with heat in the processes of mining, conversion, transportation and utilization. The heat storage can effectively relieve the problem that the heat energy supply and the demand are not matched in time, space and strength, the energy utilization rate is improved, and the energy utilization cost is reduced, so that the method is a key technology for constructing a clean, low-carbon, high-efficiency and safe energy system!

There are three types of heat storage technologies, of which the latent and sensible technologies are the most studied. However, both techniques have a problem that it is difficult to achieve both high heat storage density and high power density. Taking a sensible heat type ceramic material as an example, the specific heat capacity of the ceramic is small, and the heat storage density is low. The latent heat type phase-change material has large phase-change latent heat, high heat storage density, small heat conductivity coefficient, low power density (slow storage)! . How to simultaneously improve the heat storage density and the power density is not an effective method at present.

The energy sources of heat storage mainly include solar energy and waste heat. The existing solar heat storage system is mostly surface type, solar energy is firstly absorbed by the surface and converted into heat, and then is transferred to working medium, so that the heat transfer link is multiple, and the heat loss is large. The traditional passive waste heat storage system is weak in self-adaptive control capacity and low in energy utilization rate. These bottlenecks have greatly restricted the development of technologies for efficient utilization of renewable energy and waste heat!

Therefore, the development of heat storage technology with fast response, large capacity, high efficiency and long service life is urgent! To accomplish this, we learn from nature! The specific idea is as follows: the hierarchical pore structure in the tree simulates the heat storage material, increases the load, improves the stability and improves the heat storage density.

Disclosure of Invention

The purpose of the invention is as follows: the composite phase-change heat storage material has higher heat conduction performance, higher spectral absorption performance and higher heat storage density.

The invention also aims to provide a preparation method of the heat storage material.

The other purpose of the invention is realized by the following technical scheme:

the biological silicon carbide ceramic high-temperature photo-thermal storage material is characterized in that: the composite phase-change heat storage material is prepared by compounding chloride salt and a porous silicon carbide framework, wherein the mass fraction of the porous silicon carbide ceramic framework accounts for 70%, and the mass fraction of the chloride salt accounts for 30%. The mass fraction of sodium chloride in the chlorate accounts for 60 +/-1 percent, and the mass fraction of potassium chloride accounts for 40 +/-1 percent. The porosity of the porous biological silicon carbide selected from the materials is 50 +/-5%.

In addition, the invention also discloses a biomorphic silicon carbide ceramic high-temperature photo-thermal storage material, which comprises the following steps:

the first step is as follows: and (3) preparing the biological silicon carbide ceramic skeleton.

Primarily cutting wood, drying in a drying box, and then placing in a tubular furnace to heat to 900-1100 ℃ and preserving heat for 30-60 minutes; discharging, and finely cutting the carbonized precursor; placing the cut precursor in a high-temperature furnace, and reacting the cut precursor with excessive silicon for 1-4 hours at 1550-1650 ℃ in a vacuum atmosphere; and then placing the ceramic in a vacuum atmosphere at 1900 +/-50 ℃ for heat preservation for 4-6 hours to obtain the porous silicon carbide ceramic in the biological form for later use.

The second step is that: and preparing the high-temperature phase-change heat storage material.

Weighing sodium chloride and potassium chloride according to a certain proportion, placing the mixture in a ball mill, fully mixing the mixture uniformly, and placing the mixture in a tube furnace to be fully dried in a nitrogen atmosphere to obtain the phase-change heat storage material for later use.

The third step: the biological silicon carbide ceramic high-temperature photo-thermal storage material.

And (3) placing the phase change heat storage material obtained in the second step into a crucible to coat the biological silicon carbide ceramic obtained in the first step, heating to 665-675 ℃ in a tubular furnace in a vacuum atmosphere, and preserving heat for 3-4 hours to obtain the biological silicon carbide ceramic high-temperature photo-thermal storage material.

The invention relates to a preparation method of a biological silicon carbide ceramic high-temperature photo-thermal storage material, which comprises the step of cutting wood into cuboids with the length of 70mm, the width of 50mm and the thickness of 30mm in the first step.

The invention relates to a preparation method of a biological silicon carbide ceramic high-temperature photo-thermal storage material, which comprises the step of drying primarily cut wood in a drying oven at 70 ℃ for 2-3 days.

The invention relates to a preparation method of a biological silicon carbide ceramic high-temperature photo-thermal storage material, which comprises the following steps of putting dried wood into a tube furnace, heating the wood to 500 ℃ at a heating rate of 0.5 ℃/min under the protection of nitrogen, heating the wood to 900-1100 ℃ at a heating rate of 1 ℃/min, preserving the heat for 30-60 minutes, cooling the wood to room temperature at a cooling rate of 1 ℃/min, and slowly heating and cooling the wood to ensure that a crack-free carbon precursor is obtained.

The invention relates to a preparation method of a biological form silicon carbide ceramic high-temperature photo-thermal storage material, which comprises the step of finely cutting a carbonized precursor into wafers with the diameter of 12.7mm and the thickness of 3mm by using a punching machine and a wire cutting machine in the first step.

The invention relates to a preparation method of a biological silicon carbide ceramic high-temperature photo-thermal storage material, which comprises the steps of putting a cut precursor coated with sufficient silicon powder into a high-temperature furnace, heating to 1550-1650 ℃ in a vacuum atmosphere, preserving heat for 1-4 hours, wherein the heating rate is less than or equal to 10 ℃/min, and the chemical reaction can be fully carried out under the condition.

The invention relates to a preparation method of a biological silicon carbide ceramic high-temperature photo-thermal storage material, which comprises the following steps of putting silicon carbide ceramic and redundant silicon into a high-temperature furnace, heating to 1900 ℃, keeping the temperature for 4-6 hours in a vacuum atmosphere, and keeping the temperature rise rate at or below 10 ℃/min, wherein the sample obtained under the condition has the optimal compactness and can effectively remove the residual silicon, and the sample obtained under the condition has inferior performance and appearance.

The invention relates to a preparation method of a biological silicon carbide ceramic high-temperature photo-thermal storage material, and in the second step, the mass fraction of sodium chloride and potassium chloride accounts for 60% to 40%.

The preparation method of the biological silicon carbide ceramic high-temperature photo-thermal storage material comprises the step of mixing the silicon carbide ceramic high-temperature photo-thermal storage material with a ball mill at a rotating speed of 300r/min for 2-3 hours, wherein the powder fineness eutectic effect obtained under the condition is better than that obtained under other conditions.

The invention relates to a preparation method of a biological silicon carbide ceramic high-temperature photo-thermal storage material, which comprises the following steps of placing mixed chloride salt in a tube furnace, drying the chloride salt for 1-2 hours at 90 ℃ in a nitrogen atmosphere, and then heating to 350 ℃ for drying for 1-2 hours, wherein the performance of a sample obtained under the condition is optimal.

The invention relates to a preparation method of a biological form silicon carbide ceramic high-temperature photo-thermal storage material, which comprises the third step of placing chlorine salt obtained in the second step into a crucible to coat the biological form silicon carbide ceramic obtained in the first step, heating the crucible to 665-675 ℃ in a tubular furnace, keeping the temperature for 3-4 h in a vacuum atmosphere, wherein the heating rate is less than or equal to 3 ℃/min, the sample obtained under the condition has the best impregnation performance, can effectively seal a phase change material from leaking, and the sample obtained under the condition has poor performance and appearance.

By adopting the technical scheme, the high-temperature composite phase-change material is prepared by compounding the biological silicon carbide ceramic skeleton and chloride. The composite phase-change heat storage material prepared by the invention has higher heat conductivity, higher spectral absorption performance and higher heat storage density, the heat conductivity of the ceramic framework is 113W/mK, the enthalpy value of the phase-change material is up to 411J/g, the melting temperature is 663 ℃, the heat conductivity of the composite material is up to 116W/mK, the average spectral absorption rate of the composite material is up to 92%, and the heat storage density of the composite material is up to 453 kg/kJ. The invention has the advantages of high thermal conductivity, large latent heat of phase change, low toxicity, low corrosivity and the like, and can be used as a phase change heat storage material to improve the energy conversion efficiency.

The invention has the advantages that:

(1) the biological silicon carbide ceramic skeleton of the invention keeps the original shape of trees and has excellent quality transmission capability;

(2) the composite phase-change heat storage material prepared by the invention has higher heat-conducting property and faster heat absorption and release speed;

(3) the composite phase-change heat storage material prepared by the invention has higher spectral absorption performance and strong full-spectrum solar energy capturing capability;

(4) the composite phase-change heat storage material prepared by the invention has higher heat storage density and simultaneously has high heat storage density and high power density;

(5) the physical and chemical characteristics of each component of the composite phase-change heat storage material prepared by the invention have the characteristics of corrosion resistance and high phase-change enthalpy.

Drawings

FIG. 1 is a flow chart of the preparation of an embodiment;

fig. 2 is SEM photographs of different types of wood after carbonization according to an embodiment.

FIG. 3 shows the thermal conductivity at room temperature of different types of wood according to the embodiment.

Fig. 4 is a thermal conductivity of an embodiment biomorphic silicon carbide ceramic composite.

FIG. 5 is the average spectral absorbance of the biomorphic silicon carbide ceramic composite.

Detailed Description

The method for measuring each parameter in the implementation and proportion of the invention is as follows:

1. and measuring the thermal conductivity of the material by using a laser thermal conductivity meter.

2. The phase change latent heat value of the material was tested by DSC.

3. The specific heat capacity of the material was tested using DSC.

4. The spectral absorptance of the material was measured using a spectrophotometer.

Embodiments of the invention are further illustrated by the following examples:

the first step is as follows: and (3) preparing the bionic silicon carbide ceramic skeleton.

Cutting wood into cuboids with the length of 70mm, the width of 50mm and the thickness of 30 mm. And (3) drying the cut wood in a drying oven at 70 ℃ for 2-3 days. And (3) placing the mixture into a tube furnace, raising the temperature to 500 ℃ at the heating rate of 0.5 ℃/min under the protection of nitrogen, raising the temperature to 900-1100 ℃ at the heating rate of 1 ℃/min, and preserving the temperature for 30-60 minutes. The carbonized precursor was finely cut into a wafer having a diameter of 12.7mm and a thickness of 3mm by means of a punch and a wire cutter. And (3) coating the cut precursor with sufficient silicon powder, placing the coated precursor in a high-temperature furnace, heating to 1550-1650 ℃ in a vacuum atmosphere, and keeping the temperature for 1-4 h, wherein the heating rate is less than or equal to 10 ℃/min. And (3) placing the silicon carbide ceramic and the redundant silicon in a high-temperature furnace, heating to 1900 +/-50 ℃, keeping the temperature in a vacuum atmosphere for 4-6 hours, wherein the heating rate is less than or equal to 10 ℃/min, and removing the redundant silicon to obtain the biological porous silicon carbide ceramic.

The second step is that: and preparing the high-temperature phase-change heat storage material.

And (3) fully mixing 6g of sodium chloride and 4g of potassium chloride in a ball mill at the rotating speed of 300r/min for 2-3 hours. And (3) placing the mixed chloride in a tubular furnace in a nitrogen atmosphere at 90 ℃ for drying for 1-2 h, and drying at 350 ℃ for 1-2 h to obtain the phase-change heat storage material for later use.

The third step: the biological silicon carbide ceramic high-temperature photo-thermal storage material.

And (3) placing the phase change heat storage material obtained in the second step into a crucible to coat the biological silicon carbide ceramic obtained in the first step, heating to 665-675 ℃ in a tubular furnace in a vacuum atmosphere, and preserving heat for 3-4 hours to obtain the biological silicon carbide ceramic high-temperature photo-thermal storage material.

The performance parameters of the biological high-temperature phase change composite heat storage material prepared by the embodiment are as follows:

the heat conductivity of the ceramic framework is 113W/mK, the enthalpy value of the phase-change material is up to 411J/g, the melting temperature is 663 ℃, the heat conductivity of the composite material is up to 116W/mK, the average spectral absorption rate of the composite material is up to 92%, and the heat storage density of the composite material is up to 453 kg/kJ.

Although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions are not intended to limit the spirit and scope of the present invention to the particular embodiments described above.