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Nano Al Powder Usually Requires Surface Coating

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Al Powder is characterized by small particles, high specific surface area, and high energy. It’s widely used for the manufacture of thermite as well propellant and other pyrotechnic products. The development of nanotechnology has made nano-aluminum powder a much more popular research tool. It is now capable of producing better results than conventional aluminum powder.
Why are Nano Al Powder surfaces coated?

Nano Al Powder’s activity is expected to be low and less sensitive than other environmental factors, such as temperature and humidity. The product should be stable for long periods of time. However, Aluminum as an active metal can readily react with oxygen in the atmosphere, and form a layer or aluminum oxide film that covers the Nano Al Powder. This reduces the powder’s energy release. In order to avoid the dispersion and homogenization of the system, researchers at home as well as abroad, have used the technique of coating or modifying the surface of Nano-Aluminum Powder to attempt to correct these shortcomings.

Analyse of Nano-Al Powder Surface Coating Technology

Nano Al Powder currently surfaces using a combination of in-situ or surface passivation.

1. Nano Al Powder surface coating

1.1 Passivation mechanism. The strong dipole/dipole interaction means that unpassivated, charged particles remain within the dispersion medium. Through diffusion, uncharged particles react with Ar. Electrons move from the metal layer through the oxide to the oxidant. While the proton H+ itself travels through the metal/oxide interface, electrons pass through the oxide layers to the metal. Electrostatic fields are created when positive-charged particles form and accumulate enough to stop the redox reaction. Redox is strengthened before the negative charge can be fully compensated. The additional metal must be oxidized in order to strengthen the electric field. This will allow the energy barrier effect to stabilize nano-aluminum and improve the anti-oxidation performance.
1.2 The significance of passivation. While nano-aluminum particles are more resistant to oxidation than other powders, this shell layer is not responsible for releasing energy. Consider the entire preparation of nano-aluminum dust, including the size, type, structure and thickness. The shell-coating surface layer is crucial for determining the activity control and antioxidation performance.

2. Nano Al Powder in-situ coating

2.2.1 Method for electric explosion
Electric explosion refers to the application of an electric current having an energy density of 1.x (106109) A/cm2 onto the aluminum wire. This causes the wire to be heated instantly and then melt in a microwave explosion. After that, the product is dispersed and cool to create Nano-aluminum particles. It is important to consider the following aspects when coating in situ with electric explosion: (1) to make sure that active aluminum levels of the nanoaluminum dust reach the micron level of activity (95 to 98%); (2) to improve propellant performance. This coating modifies the fuel’s ability to burn while also preventing its oxidation. should be promoted. Here is a list of common coating materials that can be used to modify the surface of nano-aluminum dust.
2.2 Chemical method using a wet chemical
For nano-aluminum, the wet chemical process uses Tertiary Amino Aluminum Hydride. It is decomposed under the influence of titanium Isopropoxide. Dark brown color is achieved after adding the catalyst. A coating prevents nano-aluminum from becoming agglomerated during the transformation to black. Nano-aluminum particles are finally formed on the container’s surface.
This process is safe because it uses liquid to produce active aluminum powder. Decomposition rates of tertiary ammonium aluminum hydride, as well as the time required to apply organic coating, have an important impact on aluminum powder formation and the shape of composite particles. Other effects of organic matter may also be possible. These effects can also be caused by different types of organic matter. Future research should focus on this mechanism.

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