Why nano aluminum powder surface coating?

Overview of aluminum nanoparticles nano aluminum powder

Aluminum nanoparticle nano aluminum powder has the characteristics of small particle size, large specific surface area and high surface energy. At present, it is widely used in the formulation of thermite, propellant and pyrotechnic powder. With the development of nanotechnology, nano aluminum powder shows better performance than traditional aluminum powder, and has become a more active research hotspot.

Nano aluminum powder improves the sintering process of ceramics, has higher heat transfer performance, higher density, improves the thermal conductivity of sintered body, and has good sintering ability and sunlight.

In the process of powder storage, transportation and processing, nano aluminum powder is often expected to have low activity, which is less affected by external environmental factors (temperature, humidity, etc.), so that the product has stable performance for a long time. However, as an active metal material, aluminum is easy to react with oxygen and water in the air, forming an alumina film on the surface of nano aluminum powder, which affects the energy release effect of nano aluminum powder. Because of the dispersion and homogenization in the system, scholars at home and abroad have tried to improve these deficiencies by coating and modifying the surface of nano aluminum powder, in order to achieve satisfactory results in the field of energetic materials.

At present, the surface coating of nano aluminum powder mainly adopts the methods of surface passivation and in-situ coating.

Surface passivation and coating of nano aluminum powder

Passivation mechanism: due to the strongly induced dipole / dipole interaction, the non passivated charged particles remain in the dispersion medium (AR). Uncharged particles interact with AR through diffusion, electrons are transmitted from the metal surface to the oxidant through the oxide layer, and the oxidant (proton H +) itself is transmitted through the metal oxide interface. Positively charged particles gather in an electrostatic field sufficient to stop the redox process. The redox process is strengthened before the negative charge is fully compensated. In order to stabilize the electric field, the additional metal is oxidized to stabilize the nano aluminum powder and enhance the oxidation resistance of the nano aluminum powder.

Significance of passivation: the passivation treatment of nano aluminum powder improves the oxidation resistance of nano aluminum powder, but this shell does not contribute to the energy release of nano aluminum powder. It is necessary to comprehensively consider the preparation method of nano aluminum powder and the particle size, type, structure and thickness of surface coating shell, so it is meaningful to solve the problems of activity control and oxidation resistance.

In situ coating of nano aluminum powder

Electric explosion method

Electric explosion method refers to the application of energy density of 1.0 on aluminum wire × (106 ~ 109) a / cm2 pulse current makes the aluminum wire instantly heat and melt, vaporize in the form of explosion, and disperse the product in an inert atmosphere to cool to form nano aluminum particles. The in-situ coating by electric explosion method mainly considers the following three aspects: (1) ensure that the active aluminum content of nano aluminum powder reaches the micron level (95% ~ 98%); (2) High content of nano aluminum powder will significantly improve the performance of propellant. (3) The modified coating not only prevents the oxidation deactivation of nano aluminum powder, but also has a good effect on the combustion performance of propellant. It should have a certain promoting effect.

Wet chemical method

Wet chemical method uses tertiary amine aluminum hydride to decompose under the action of isopropanol titanium catalyst to form nano aluminum powder. After adding the catalyst, the solution is dark brown. In the blackening process, the addition of coating can prevent nano aluminum powder from caking in the process. Nano aluminum powder composite particles are finally formed on the surface of the container wall.

This method has the inherent safety of processing active aluminum powder in liquid. At the same time, the decomposition rate of tertiary amine aluminum hydride and the introduction time of organic coating have a very important influence on the formation of aluminum powder and the morphology of composite particles. Organic matter can produce different effects. To sum up, in addition to forming a coating on the surface of nano aluminum powder, the shell coating also plays a very important role in the whole chemical reaction process. Different organic coatings have different roles. The mechanism of action is the focus of future research.

Application of aluminum nanoparticles nano aluminum powder

High efficiency catalyst: nano aluminum powder is added to rocket solid fuel, which greatly improves the fuel combustion speed and combustion stability;

Active sintering aids: add 5-10% nano aluminum powder into AlN powder to reduce the sintering temperature and increase the density and thermal conductivity of the sintered body; If nano aluminum is used as the substrate of integrated components, the thermal conductivity will be increased by about 10 times. It can solve the integration problem of integration components.

Surface conductive coating treatment of metal and scrap metal: due to the high activation surface energy of nano aluminum, the coating construction can be carried out at a temperature lower than the melting point of the powder under the condition of no oxygen. This technology can be applied to the production of microelectronic devices.

It is widely used in high-grade metal pigments, composite materials (thermal spraying composite metal powder, ceramic composite steel pipe), military industry (filler), chemical industry (various chemical catalysts and pesticides), metallurgy (thermite metallurgy, steel deoxidizer), shipbuilding (conductive coating), refractory materials (magnesia carbon brick for steel furnace), new building materials (aerated concrete gas generator), anti-corrosion materials, etc.

Price of aluminum nanoparticles nano aluminum powder

The price of aluminum nanoparticles and nano aluminum powder will change randomly due to production cost, transportation cost, international situation, market supply and demand of aluminum nanoparticles and nano aluminum powder and other factors. Tanki new materials Co., Ltd. aims to help industries and chemical wholesalers find high-quality and low-cost nano materials and chemicals by providing a full range of customized services. If you are looking for aluminum nanoparticle nano aluminum powder, please feel free to send an inquiry to obtain the latest price of aluminum nanoparticle nano aluminum powder.

Supplier of nano aluminum powder

As a global supplier of aluminum nanoparticles and nano aluminum powder, tanki new materials Co., Ltd. has rich experience in the performance, application and cost-effective manufacturing of advanced and engineering materials. The company has successfully developed a series of powder materials (including boron carbide, aluminum carbide, titanium carbide, etc.), high-purity targets, functional ceramics and structural devices, and provided OEM services.