阅读说明：本技术 一种相变蓄热陶瓷及其制备方法 (Phase-change heat storage ceramic and preparation method thereof ) 是由 张美杰 韩藏娟 顾华志 黄奥 付绿平 于 2020-06-05 设计创作，主要内容包括：本发明涉及一种相变蓄热陶瓷及其制备方法。其技术方案是：将50～85wt％的电熔莫来石粉、10～45wt％的预处理铝硅合金粉和3～8wt％的球黏土混合,搅拌均匀,得到混合料。所述混合料在80～150MPa条件下压制成型,得到陶瓷坯体。将所述陶瓷坯体在温度为25～28℃、相对湿度为70～75RH的环境中养护24～36h,在80～120℃条件下干燥24～36h,然后在1100～1300℃条件下保温3～5h,得到相变蓄热陶瓷。所述预处理铝硅合金粉的制备方法是：将铝硅合金粉在压强为0.02～0.20MPa的水蒸气中保持0.5～3h,再置于碱性硅溶胶中浸渍,干燥后即得。本发明制备成本低、生产工艺简单和易于工业生产；制备的相变蓄热陶瓷能提高热量的利用率和利用效率,使用温度高。(The invention relates to a phase-change heat storage ceramic and a preparation method thereof. The technical scheme is as follows: mixing 50-85 wt% of electrofused mullite powder, 10-45 wt% of pre-treated aluminum-silicon alloy powder and 3-8 wt% of ball clay, and uniformly stirring to obtain a mixture. And pressing and forming the mixture under the condition of 80-150 MPa to obtain a ceramic blank. And curing the ceramic blank body for 24-36 h in an environment with the temperature of 25-28 ℃ and the relative humidity of 70-75 RH, drying for 24-36 h at the temperature of 80-120 ℃, and then preserving heat for 3-5 h at the temperature of 1100-1300 ℃ to obtain the phase-change heat storage ceramic. The preparation method of the pre-treated aluminum-silicon alloy powder comprises the following steps: keeping the aluminum-silicon alloy powder in water vapor with the pressure of 0.02-0.20 MPa for 0.5-3 h, then soaking in alkaline silica sol, and drying to obtain the aluminum-silicon alloy powder. The invention has low preparation cost, simple production process and easy industrial production; the prepared phase-change heat storage ceramic can improve the utilization rate and utilization efficiency of heat and has high use temperature.)

1. The preparation method of the phase-change heat storage ceramic is characterized by comprising the following steps: mixing 50-85 wt% of fused mullite powder, 10-45 wt% of pretreated aluminum-silicon alloy powder and 3-8 wt% of ball clay, and uniformly stirring to obtain a mixture;

pressing and molding the mixture under the condition of 80-150 MPa to obtain a ceramic blank; maintaining the ceramic body for 24-36 h in an environment with the temperature of 25-28 ℃ and the relative humidity of 70-75 RH, drying for 24-36 h at the temperature of 80-120 ℃, and then preserving heat for 3-5 h at the temperature of 1100-1300 ℃ to prepare the phase-change heat-storage ceramic;

the preparation method of the pre-treated aluminum-silicon alloy powder comprises the following steps:

placing aluminum-silicon alloy powder in a high-pressure reaction kettle, and keeping the aluminum-silicon alloy powder in water vapor with the pressure of 0.02-0.20 MPa for 0.5-3 h to obtain the aluminum-silicon alloy powder corroded by the water vapor;

secondly, placing the aluminum-silicon alloy powder subjected to water vapor corrosion into alkaline silica sol with the pH value of 8-12, keeping for 10-30 h, and filtering to obtain impregnated aluminum-silicon alloy powder;

step three, placing the aluminum-silicon alloy powder subjected to the dipping treatment in a drying oven at the temperature of 50-110 ℃, and drying for 12-24 hours to obtain pre-treated aluminum-silicon alloy powder;

the particle size of the nano particles in the alkaline silica sol is 10-20 nm.

2. The method for preparing the phase-change heat storage ceramic according to claim 1, wherein the electrically-fused mullite powder comprises the following chemical components in percentage by weight: al (Al)₂O₃68-73 wt% of SiO₂22 to 25 wt%; particle size of electrically fused mullite powder<58μm。

3. The method for preparing phase-change heat storage ceramic according to claim 1, wherein the ball clay comprises the following chemical components in percentage by weight: al (Al)₂O₃17 to 35 wt% of SiO₂45-74 wt%; particle size of ball clay<45μm。

4. The method for producing a phase change heat storage ceramic according to claim 1, wherein the aluminum-silicon alloy powder has a Si content of 1 to 44 wt% and a particle size of less than 74 μm.

5. A phase change heat storage ceramic, characterized in that the phase change heat storage ceramic is prepared by the method for preparing a phase change heat storage ceramic according to any one of claims 1 to 4.

Technical Field

The invention belongs to the technical field of phase change heat storage materials. In particular to a phase change heat storage ceramic and a preparation method thereof.

Background

The heat storage technology is an energy storage technology which stores temporarily unnecessary heat by using a heat storage material and releases the heat when needed. The heat storage technology solves the time difference contradiction between heat supply and demand, improves the utilization of heat, and can be used for peak clipping and valley filling of power load, solar energy storage, industrial waste heat recovery and the like, so as to achieve the purposes of developing new energy and saving old energy.

The core problem of the heat storage technology is the preparation and application of the heat storage material, wherein the phase change heat storage material becomes a heat storage material with development potential due to high energy storage and adjustable phase change temperature. At present, the heat storage ceramic is generally porous heat storage ceramic taking sensible heat as a heat storage mode. However, the sensible heat storage ceramic has a limited heat storage capacity and the temperature of the ceramic fluctuates. The phase change heat storage material stores heat by using latent heat of solid-liquid phase change of the material, and temperature fluctuation is small. Therefore, it has become a hot point of research in recent years to add a phase change material to a ceramic and store heat by comprehensively utilizing sensible heat and latent heat of phase change.

In recent years, some researchers have conducted some studies on phase change heat storage ceramics, and some phase change heat storage ceramics containing a phase change material have been disclosed. For example, in the patent technology of 'a preparation method of ceramic heat storage balls wrapping phase-change materials' (CN201010119544.1), SiC powder, feldspar powder and kaolin are used as raw materials, and the raw materials are directly mixed, pressed, molded and roasted at high temperature to prepare SiC ceramic ball shells; then preparing packaging pug by adding SiC powder, low-temperature frit and polyvinyl alcohol; finally, the phase change material is placed in a spherical shell for packaging and sintering. However, the preparation process of the method is complex, and the packaging part of the spherical shell is easy to crack. The patent technology of 'a metal ceramic with phase change heat storage function and a manufacturing method thereof' (CN201310293700.X) adopts aluminum-silicon alloy powder and corundum powder as raw materials and magnesium oxide as a sintering aid, and prepares the metal ceramic with the phase change heat storage function through dry ball milling, molding and roasting. The phase-change material is directly used in the preparation of the composite phase-change heat storage material as a raw material, and the purpose of heat storage is realized by utilizing the heat absorption and heat release of the phase-change material during phase change. The aluminum-silicon alloy powder is easy to leak and overflow after being melted in the roasting process by the mixed forming method, and the high-temperature physical property of the material can be reduced by the liquid-phase aluminum-silicon alloy.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and aims to provide a preparation method of phase change heat storage ceramic, which has low preparation cost and simple production process and is easy to realize industrial production; the prepared phase change heat storage ceramic can improve the utilization rate and utilization efficiency of heat and has high use temperature.

In order to achieve the purpose, the invention adopts the technical scheme that:

mixing 50-85 wt% of electrofused mullite powder, 10-45 wt% of pretreated aluminum-silicon alloy powder and 3-8 wt% of ball clay, and uniformly stirring to obtain a mixture. And pressing and forming the mixture under the condition of 80-150 MPa to obtain a ceramic blank. And curing the ceramic body for 24-36 h in an environment with the temperature of 25-28 ℃ and the relative humidity of 70-75 RH, drying for 24-36 h at the temperature of 80-120 ℃, and then preserving heat for 3-5 h at the temperature of 1100-1300 ℃ to obtain the phase-change heat-storage ceramic.

The preparation method of the pre-treated aluminum-silicon alloy powder comprises the following steps:

step one, placing the aluminum-silicon alloy powder in a high-pressure reaction kettle, and keeping the aluminum-silicon alloy powder in water vapor with the pressure of 0.02-0.20 MPa for 0.5-3 h to obtain the aluminum-silicon alloy powder corroded by the water vapor.

And step two, placing the aluminum-silicon alloy powder subjected to the water vapor corrosion into alkaline silica sol with the pH value of 8-12, keeping for 10-30 h, and filtering to obtain the aluminum-silicon alloy powder subjected to dipping treatment.

And step three, placing the aluminum-silicon alloy powder subjected to the dipping treatment in a baking oven at the temperature of 50-110 ℃, and drying for 12-24 hours to obtain the pretreated aluminum-silicon alloy powder.

The particle size of the nano particles in the alkaline silica sol is 10-20 nm.

The electric melting mullite powder comprises the following chemical components in percentage by weight: al (Al)₂O₃68-73 wt% of SiO₂22 to 25 wt%; particle size of electrically fused mullite powder<58μm。

The ball clay comprises the following chemical components in percentage by weight: al (Al)₂O₃17 to 35 wt% of SiO₂45-74 wt%; particle size of ball clay<45μm。

The content of Si in the aluminum-silicon alloy powder is 1-44 wt%, and the granularity of the aluminum-silicon alloy powder is less than 74 mu m.

Due to the adoption of the technical scheme, compared with the prior art, the invention has the following positive effects:

the invention takes mullite powder, pretreated aluminum-silicon alloy powder and ball clay as raw materials, and has low preparation cost; the raw materials are mixed, pressed, molded, maintained, dried and roasted at 1100-1300 ℃ to obtain the phase change heat storage ceramic, and the production process is simple and easy to realize industrial production.

The aluminum-silicon alloy adopted by the invention is easy to react with water vapor to generate aluminum hydroxide; the aluminum and the silicon in the aluminum-silicon alloy are distributed in a dispersed manner, so that the aluminum hydroxide generated by the reaction can not form a compact film to prevent the further reaction. Therefore, after the aluminum-silicon alloy is placed in water vapor for a period of time, aluminum hydroxide with adsorption effect is formed on the surface. When the aluminum-silicon alloy powder with the treated surfaces is placed in silica sol, nano silicon dioxide in the silica sol is adsorbed under a vacuum environment to form an initial shell layer of the silica sol and aluminum hydroxide. The initial shell layer of the ceramic enables pretreated aluminum-silicon alloy powder to be easily and uniformly mixed with mullite powder and ball clay, and under the high-temperature condition, silicon dioxide in silica sol and partial aluminum oxide formed by decomposing aluminum hydroxide are combined to generate a mullite shell layer which is wrapped on the surface of the aluminum-silicon alloy powder and sintered with mullite in raw materials to form a ceramic framework. The prepared phase-change heat storage ceramic can utilize the phase-change latent heat of the aluminum-silicon alloy and the sensible heat of the ceramic framework, and the utilization rate and the utilization efficiency of heat are high. Can meet the requirements of high-temperature heat exchange of solar power plants and industrial furnaces and heat recovery of high-temperature industrial waste gas.

The phase change heat storage ceramic prepared by the invention solves the problem that aluminum-silicon alloy is not easy to mix with ceramic powder directly, and effectively utilizes the phase change latent heat of the aluminum-silicon alloy. The prepared phase change heat storage ceramic has the advantages of high strength, high temperature resistance, cold and heat cycle resistance and the like, so that the melting loss of the aluminum-silicon alloy in a melting state and the reduction of latent heat of the phase change heat storage ceramic caused by the melting loss can be effectively prevented, the use temperature is high, and the heat utilization rate is high.

The phase change heat storage ceramic prepared by the invention is detected as follows: the apparent porosity is 31.5 to 34.0%; the bulk density is 2.13-2.34 g/cm³(ii) a The normal-temperature compressive strength is 50-120 MPa; the normal-temperature breaking strength is 10-45 MPa; the latent heat of phase change is 90-200J/g; the thermal conductivity is 3-25 W.m^-1·K^-1。

Therefore, the invention has low preparation cost, simple production process and easy realization of industrial production; the prepared phase change heat storage ceramic can improve the utilization rate and utilization efficiency of heat and has high use temperature.

Detailed Description

The invention is further described with reference to specific embodiments, without limiting its scope.

In order to avoid repetition, the materials related to this specific embodiment are described in a unified manner, which is not described in the embodiments again:

the electric melting mullite powder comprises the following chemical components in percentage by weight: al (Al)₂O₃68-73 wt% of SiO₂22 to 25 wt%; particle size of electrically fused mullite powder<58μm。

The ball clay comprises the following chemical components in percentage by weight: al (Al)₂O₃17 to 35 wt% of SiO₂45-74 wt%; particle size of ball clay<45μm。

The content of Si in the aluminum-silicon alloy powder is 1-44 wt%, and the granularity of the aluminum-silicon alloy powder is less than 74 mu m.

The particle size of the nano particles in the alkaline silica sol is 10-20 nm.