Giant-amplitude negative thermal expansion coefficient material and preparation method thereof
By developing a huge negative thermal expansion material material, using multiple temperature memory points and liquid filling materials to realize the abnormal expansion structure of inflation and contraction at low temperatures at low temperatures, solving the limited application of existing materials, and the limited application of the existing materials is limited The problem improved the heating shock performance of the device.
Patent Information
- Application Number
- CN202411406809.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-10
- Publication Date
- 2025-01-28
AI Technical Summary
The existing negative thermal expansion material system is limited, there are fewer materials with engineering application value, and the understanding of the heat shrinkage mechanism is not deep enough. There are problems such as narrow negative thermal expansion temperature zone, high phase transition temperature or water absorption, which affects its application.
Develop a huge negative thermal expansion rate material and its preparation methods. By mixing the EVA and other organic memory materials of various melting points and glass -state points, it is mixed and melted. Squeeze at the temperature, so that the material has an abnormal expansion rate, and increases the heating reinforcement agent of the liquid filling material inside the material. It uses it to release the gas at low temperature to keep the insulation, and condenses into solids at high temperature for solid heating.
The abnormal expansion structure that expands at low temperature and shrinks at high temperatures, has the range of negative expansion rates with multiple temperature memory points and huge amplitude. , With higher engineering application value, improve the heat resistance impact performance of devices.
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of heat insulation structures, in particular to a material with a large negative thermal expansion coefficient and a preparation method thereof. Background Art
[0002] Negative thermal expansion materials are materials with negative average linear expansion coefficients or volume expansion coefficients within a certain temperature range. They have opposite thermal properties to conventional materials that expand with heat and contract with cold. The application value of these materials lies in their ability to reduce thermal stress caused by large or rapid temperature changes, which is of great significance for improving the thermal shock resistance of devices.
[0003] For example, in the aerospace field, negative thermal expansion materials can be used to prepare antennas and antenna bracket materials for spacecraft, thereby improving the high temperature resistance and thermal shock resistance of these devices. In optical devices, such as telescopes, laser communications, and optical fiber communication systems, the use of negative thermal expansion materials can greatly improve the thermal shock resistance of these devices and ensure their stable operation. In addition, in mechanical devices, such as analytical balances and precision clocks, negative thermal expansion materials can also improve the accuracy and stability of these devices.
[0004] The negative thermal expansion material systems discovered so far are still very limited, and even fewer have engineering application value. The understanding of the thermal contraction mechanism needs to be deepened. There are still some problems that affect their application, such as a narrow negative thermal expansion temperature range, a high phase change temperature, or water absorption.
[0005] To this end, we have developed a new material with a huge negative thermal expansion coefficient and its preparation method. Summary of the invention
[0006] 1. Technical issues to be resolved
[0007] In view of the shortcomings of the prior art, the present invention provides a material with a large negative thermal expansion coefficient and a preparation method thereof, which solves the problems that the negative thermal expansion material system in the prior art is still very limited, and there are even fewer with engineering application value. The understanding of the thermal shrinkage mechanism needs to be deepened, and there are still some problems that affect its application, such as a narrow negative thermal expansion temperature range, a high phase change temperature, or water absorption.
[0008] (II) Technical solution
[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions: a material with a large negative thermal expansion coefficient and a preparation method thereof, comprising a negative thermal expansion coefficient material body, wherein the negative thermal expansion coefficient material body has different abnormal expansion rates at different temperatures, and the negative thermal expansion coefficient material body expands at low temperatures and contracts at high temperatures.
[0010] A method for preparing a material with a large negative thermal expansion coefficient comprises the following specific steps:
[0011] Step 1: First prepare EVA with various melting points and glass points, as well as other organic memory materials, and then mix and melt the above materials;
[0012] Step 2: The melted material is drawn into wires, and then the wires are piled up. The material formed at this time has multiple temperature memory points. The material is then extruded at different temperatures to have different abnormal expansion rates at different temperatures.
[0013] Step 3: Add a liquid filling material as a thermal conductivity enhancer inside the material so that it adheres to and wraps around the surface of the fibers inside the material. Under low temperature conditions, it releases more gas to keep warm, and under high temperature conditions, it condenses into a solid to conduct heat.
[0014] Preferably, the liquid filling material includes liquid thermally conductive silicone oil and phase-change thermally conductive silicone oil.
[0015] Preferably, the liquid filling material has multiple freezing points, boiling points or dew points.
[0016] Preferably, in step 1, the mixing ratio of EVA with various melting points and glassy points and other organic memory materials is 1:1:1.
[0017] (III) Beneficial effects
[0018] The present invention provides a material with a large negative thermal expansion coefficient and a preparation method thereof. It has the following beneficial effects:
[0019] The material with a huge negative thermal expansion rate and the preparation method thereof, as a new negative thermal expansion rate material, has the function of having an abnormal expansion structure that expands at low temperatures and contracts at high temperatures. At the same time, it also has multiple temperature memory points, has different abnormal expansion rates at different temperatures, and realizes a huge negative expansion rate range. Moreover, in a low temperature state, it can release more gas for heat preservation, and condense into a solid in a high temperature state for heat conduction, which can reduce the thermal stress generated by large or rapid temperature changes, has a higher engineering application value, and is of great significance for improving the thermal shock resistance of devices. DETAILED DESCRIPTION
[0020] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0021] Embodiment: The embodiment of the present invention provides a material with a large negative thermal expansion coefficient and a preparation method thereof, including a negative thermal expansion coefficient material body, wherein the negative thermal expansion coefficient material body has different abnormal expansion coefficients at different temperatures, and the negative thermal expansion coefficient material body expands at low temperatures and contracts at high temperatures.
[0022] A method for preparing a material with a large negative thermal expansion coefficient comprises the following specific steps:
[0023] Step 1: First, prepare various EVAs with melting points and glassy points, and other organic memory materials, and then mix and melt the above materials. Specifically, the mixing ratio of various EVAs with melting points and glassy points, and other organic memory materials is 1:1:1;
[0024] Step 2: The melted material is drawn into threads, and then the threads are piled up, similar to making them into cotton. The material formed at this time has multiple temperature memory points. The material is then extruded at different temperatures to have different abnormal expansion rates at different temperatures. It expands at low temperatures, so it has a heat preservation effect at low temperatures and a heat conduction effect at high temperatures.
[0025] Step three, add a thermal conductivity enhancer of liquid filling material inside the material, so that it adheres and wraps around the surface of the fiber inside the material. Under low temperature conditions, it releases more gas to keep warm, and condenses into a solid under high temperature conditions to conduct heat. The liquid filling material includes liquid thermal conductive silicone oil and phase change thermal conductive silicone oil, that is, liquid thermal conductive silicone oil or phase change thermal conductive silicone oil can be selected to fill the inside of the material, and the above-mentioned liquid filling material has multiple freezing points, boiling points or dew points.
[0026] Specifically, the formation mechanism of the above materials is as follows:
[0027] For example, the thermal equilibrium salt formed by acetate and carbonate, the sodium acetate in it will crystallize at low temperature, and the crystallization will release the carbon dioxide gas contained in the solution. Then the lower the temperature of the overall material, the more carbon dioxide is released, and the more gas is filled. At high temperature, the sodium acetate will turn into liquid, and the carbon dioxide will dissolve into the solution in large quantities due to the acidity balance of the material. Then the overall gas phase will decrease, and the gas pressure of the whole material will decrease, so that more liquid phase will appear, making the thermal conductivity better. That is, the required material is formed through the above two mechanisms.
[0028] As a new negative thermal expansion material, the present invention has the function of having an abnormal expansion structure that expands at low temperatures and contracts at high temperatures. At the same time, it also has multiple temperature memory points, has different abnormal expansion rates at different temperatures, and realizes a huge range of negative expansion rates. In addition, in a low temperature state, it can release more gas for heat preservation, and condense into a solid in a high temperature state to conduct heat, which can reduce the thermal stress generated by large or rapid temperature changes, has higher engineering application value, and is of great significance for improving the thermal shock resistance of devices.
[0029] In summary, the present invention provides a comprehensive and systematic method to design and optimize negative thermal expansion materials. This method adds a thermal conductivity enhancer of liquid filling material inside the negative thermal expansion material body, so that it adheres to and wraps the surface of the fiber inside the material. At low temperatures, it releases more gas to keep warm, and at high temperatures, it condenses into a solid to conduct heat, thereby ensuring better resistance to thermal shock.
[0030] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the equivalents of the appended claims.
Claims
1. A material with a large negative thermal expansion coefficient, comprising a negative thermal expansion coefficient material body, characterized in that: The negative thermal expansion material body has different abnormal expansion rates at different temperatures. The negative thermal expansion material body expands at low temperatures and contracts at high temperatures.
2. The method for preparing a material with a large negative thermal expansion coefficient according to claim 1, characterized in that: The specific steps include: Step 1: First prepare EVA with various melting points and glass points, as well as other organic memory materials, and then mix and melt the above materials; Step 2: The melted material is drawn into wires, and then the wires are piled up. The material formed at this time has multiple temperature memory points. The material is then extruded at different temperatures to have different abnormal expansion rates at different temperatures. Step 3: Add a liquid filling material as a thermal conductivity enhancer inside the material so that it adheres to and wraps around the surface of the fibers inside the material. Under low temperature conditions, it releases more gas to keep warm, and under high temperature conditions, it condenses into a solid to conduct heat.
3. The method for preparing a material with a large negative thermal expansion coefficient according to claim 2, characterized in that: The liquid filling material includes liquid thermal conductive silicone oil and phase change thermal conductive silicone oil.
4. The method for preparing a material with a large negative thermal expansion coefficient according to claim 3, characterized in that: The liquid fill material has multiple freezing points, boiling points or dew points.
5. The method for preparing a material with a large negative thermal expansion coefficient according to claim 4, characterized in that: In the step 1, the mixing ratio of EVA with various melting points and glassy points and other organic memory materials is 1:1:1.