Nanometer core shell structure thermite and preparation method thereof

Abstract

The invention provides a nanometer core shell structure thermite and a preparation method thereof; the method uses nanometer aluminum powder as the Al source, and prepares the nanometer core shell structure thermite by a special reduction-oxidation method way. The general chemical formula of the thermite is MOX / 2@Al, wherein M is one of Fe, Co, Ni, Cu, W, Pb, Bi, and Mo; X is the valence state of M, X = 2-4; in the core shell structure, the particle size of the Al core is 10-500nm, the ratio between the MOx / 2 packaging layer thickness and the Al particle radius is 0.05-0.5; the specific surface area of the thermite MOX / 2@Al is 200-280m2 / g, the calorific value is 3126-4236J / g, the ignition temperature is 200-532 degrees centigrade. The provided preparation method has the advantages of simple and convenient to be implemented, economical and environment-friendly; the prepared nanometer core shell structure thermite has the performance characteristics of high in unit gross calorific value, good in dispersibility, low in ignition temperature, high in activity, and the like.

Description

technical field [0001] The invention relates to the preparation technology of nanocomposite materials, in particular to the preparation method of thermite with nanoscale core-shell structure. technical background [0002] After the phenomenon of thermite reaction was discovered by Russian scientists in the 18th century, after more than 200 years of continuous development, thermite has been widely used in military industry, smelting, pyrotechnics and other fields. The aluminothermic reaction usually releases a large amount of heat, forming more stable oxides and corresponding metals. The traditional thermite is a simple mixed system, which is composed of aluminum powder and metal oxide Fe 2 o 3 , CuO, MnO 2 Among them, aluminum powder and metal oxide are two relatively independent components, the degree of combination between each other is low, the contact area is also very limited, the reaction speed of the agent is slow, and the ignition temperature High and low actual ...

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Problems solved by technology

At present, the commonly used methods for preparing nano-scale thermite include solid-state reaction method, ball milling method, spray pyrolysis method, self-assembly method, sol-gel method, ultrasonic dispersion and compounding method, etc. Each has its own advantages and disadvantages. For example, although the solid phase reaction method is simple in process and convenient for mass production, it has high energy consumption, and the obtained thermite is prone to agglomeration and oxidation of aluminum components during the preparation process. The uniform compounding or mixing of oxides; the ball milling method has a simple preparation process and short processing time, but it is easy to cause damage to the crystal form of the particles and uneven coating during the ball milling process; although the self-assembly method and the sol-gel method can achieve aluminum Uniform compounding with metal oxides, but the synthesis cycle is long, the timeliness is poor, and often requires the introduction of toxic and harmful organic solvents, high cost, poor environmental protection, not suitable for large-scale production

In the literature Proceedings of the Combustion Institute, 2005, 30, 2071-2078, Schocnitz et al. prepared a series of aluminum-metal oxide thermites with high reactivity and high energy density by using the reaction inhibition grinding method; in the literature ACS Appl In .Mater.Interfaces 2013,5,239-242, Zhang Wenchao et al. used polystyrene microspheres as hard templates to prepare Fe with three-dimensional macroporous structure 2 o 3 , and then coated Al on Fe by thermal evaporation or magnetic sputtering 2 o 3 In addition to the skeleton structure, AlFe with a three-dimensional macroporous structure is formed 2 o 3 Nano-thermite film material, the experimental results show that the calorific value per unit mass is 2830J / g, which is significantly higher than the reported calorific value of thermite, but the process is complicated, and Al is in the outer layer of the oxide skeleton, so the long-term stability Poor, once the outer layer of aluminum is oxidized, it will directly affect its thermal performance indicators

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