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Molten salt-graphite composite material and preparation method thereof

A composite material and graphite technology, applied in the field of molten salt graphite composite material and its preparation, can solve the problems of complex preparation process, unstable composite material, high cost, etc., and achieve good heat transfer efficiency

Active Publication Date: 2018-04-13
CHNA ENERGY INVESTMENT CORP LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The method uses carbon nanotubes, which are complex and costly to prepare
[0006] In addition, in the prior art, most of the composite materials made by adding heat-conducting graphite to molten salt have the problem of instability, and the added graphite is prone to sedimentation when the molten salt is in a molten liquid state.

Method used

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  • Molten salt-graphite composite material and preparation method thereof
  • Molten salt-graphite composite material and preparation method thereof

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preparation example Construction

[0019] The first aspect of the present invention provides a kind of preparation method of molten salt graphite composite material, and this method comprises: (1) carries out surface micro-oxidation with natural graphite or artificial graphite, obtains modified graphite, and the surface oxygen content of described modified graphite is 0.5-5% by weight; (2) heating the molten salt above the melting point of the molten salt, mixing it with the modified graphite evenly, and then cooling to obtain the molten salt graphite composite material.

[0020] In the present invention, the graphite is micro-oxidized on the surface to become modified graphite and then combined with the molten salt, which can help to improve the thermal conductivity of the molten salt. At the same time, when the composite material is used as a heat exchange medium in a molten liquid state, the modification Graphite can be stably dispersed in liquid molten salt, and does not settle after standing for more than 4...

Embodiment approach

[0022] In a preferred embodiment of the present invention, the method for surface micro-oxidation includes: mixing the natural graphite or artificial graphite with nitric acid and heating and reacting to obtain a product; sequentially filtering the product, first washing with water, Alkali washing, second water washing and drying to obtain modified graphite. The lye used in the lye washing is an aqueous solution of sodium hydroxide or potassium hydroxide with a concentration of 1-20% by weight.

[0023] According to the present invention, in the preferred embodiment above, the heating reaction temperature is 60-90°C, and the heating reaction time is 4-12h; the weight ratio of the natural graphite or artificial graphite to nitric acid is (0.5-10):10; The drying temperature is 60-100°C.

[0024] In another preferred embodiment of the present invention, the method for micro-oxidizing the surface includes: performing surface treatment on the natural graphite or artificial graphit...

Embodiment 1

[0040] Add natural graphite (50-100 mesh) into nitric acid (the weight ratio of graphite to nitric acid is 8:10, and the concentration of nitric acid is about 69% by weight), and react at about 85° C. for about 8 hours. The temperature of the reaction product was lowered, followed by filtration, first washing with water, washing with alkali (2% by weight of sodium hydroxide solution) and second washing with water. Dry the washed product at 80° C. to obtain modified graphite A. The surface oxygen element content of the modified graphite A was measured by EDS to be 2.5% by weight.

[0041] The molten salt of gross mass 20g, wherein contains the KNO of 53% by weight 3 , 40 wt% NaNO 2 and 7 wt% NaNO 3 , after heating to 200° C. to melt into a liquid state, add 1 g of modified graphite A, and stir for 0.5 h. Stop stirring, keep the temperature and let it stand for 24 hours, and observe that the modified graphite A is stably dispersed in the molten salt without delamination or s...

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Abstract

The invention relates to the field of molten salt-graphite composite materials, and discloses a molten salt-graphite composite material and a preparation method thereof. The method includes the following steps: (1) carrying out surface micro-oxidation on natural graphite or artificial graphite to obtain modified graphite with the surface oxygen content being 0.5-5 wt%; and (2) heating a molten salt to a temperature being same to or more than the melting point of the molten salt, uniformly mixing the heated molten salt with the modified graphite, and cooling the obtained mixture to obtain the molten salt-graphite composite material. The production of the graphite-molten salt composite material having a high heat conductivity from the graphite raw material in a manner of simple preparation and low cost is realized.

Description

technical field [0001] The invention relates to the field of molten salt graphite composite materials, in particular to molten salt graphite composite materials and a preparation method thereof. Background technique [0002] Molten salt is used as a medium-high temperature heat storage and heat transfer medium due to its advantages such as wide temperature range, low vapor pressure, large heat capacity, and low viscosity. However, traditional molten salt generally has the problem of low thermal conductivity, which will result in low heat transfer efficiency and long startup time after freezing at low temperature. Improving the thermal conductivity of the heat transfer medium can not only shorten the start-up time of low-temperature freezing, but also reduce the number of heat exchange tubes required per unit area, facilitate the design of compact heat exchangers, and save the cost of heat exchangers. [0003] At present, in order to use thermally conductive graphite to impr...

Claims

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Application Information

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IPC IPC(8): C09K5/08
CPCC09K5/08
Inventor 段春婷刘均庆徐文强郑冬芳王秋实梁朋
Owner CHNA ENERGY INVESTMENT CORP LTD