Why are Nano Al Powder surfaces coated?
Nano Al Powder’s activity is expected to be low and less affected by environmental factors, such as temperature and humidity. The product should be stable for a long period of time. However, aluminum, as an active metal, can react with oxygen in the air to form a layer of aluminum oxide, which reduces the energy released by Nano Al Powder. In order to avoid dispersion or homogenization in this system, researchers at home and overseas have used the technique of coating and modifying the surface of Nano-Aluminum powder in order to improve their results in the area of energetic materials.
Analysis on Nano Al Powder Surface Coating Technology
Nano Al Powder currently surfaces using a combination of in-situ coating and surface passivation.
1. Nano Al Powder surface passivation and coating
1.1 Passivation mechanism. The strong induced dipole/dipole interaction means that unpassivated, charged particles remain in dispersion media (Ar). The diffusion of uncharged particles with Ar results in electrons being transported from the metal surface to the oxidant. However, the oxidant (protonH+), is transported through the interface metal-oxide. Electrostatic fields are created when positive-charged particles accumulate and stop the redox reaction. The redox reaction is strengthened before the negative charge is fully compensated. The additional metal will be oxidized in order to stabilize and increase the electric field.
1.2 Significance and significance of passivation. Although passivation improves nano-aluminum’s oxidation resistance, this shell layer does not contribute to energy release. It is essential to fully consider the preparation of nano-aluminum dust, as well as the particle size, type, structure, thickness and so on. The shell layer of the surface coating is essential for determining the activity control performance and anti-oxidation performance.
2. Nano Al Powder in-situ coating
Method for 2.1 Electric Explosion
The electric explosion technique involves using a pulse current having an energy density of 1.0x (106109)A/cm2 upon the aluminum wire. This heats the wire instantly, melts it, then explodes. The product is then dispersed in an inert environment and cools down to form Nano-aluminum particle. In-situ coating with electric explosion is primarily concerned with the following three aspects. (1) The active aluminum content of the Nano-aluminum Powder must reach the micron level (95 to 98%); (2) The propellant’s performance will be significantly improved by the high nano-aluminum content. The propellant’s combustion performance is improved by coating modification. should have a promotion effect. Table 1 lists the most common coating materials used for surface modification on nano-aluminum particles.
2.2 The wet chemical method
The wet chemical procedure uses tertiary aluminum hydride to undergo decomposition under the control of titanium isopropoxide to create nano-aluminum. The solution will turn dark brown once the catalyst has been added. A coating can be added to stop nano-aluminum particles from agglomerating during the process of turning black. Finally, nano-aluminum particles composite particles are formed on the container walls.
This method allows for the safe processing of active aluminum powder in liquid. Decomposition rates of tertiary aluminum aluminum hydride and time for organic coating play a major role in the formation of aluminum powder as well as the morphology and size of composite particles. Other effects of organic matter may also be possible. The shell coating is responsible for forming a protective coating on nano-aluminum powder’s surface. It also plays an important part in chemical reactions. Different organic coatings may have different effects. Future research should focus on the mechanism of operation.
Tech Co., Ltd. is a professional Al powder supplier. It has over 12 years’ experience in chemical product development and research. We accept credit cards, T/T and Paypal payments. We will ship goods overseas via FedEx, DHL and by air or sea to our customers.