Carbon aluminum composite absorbing material three-stage emulsifier

The so-called absorbing material refers to a type of material that can absorb or significantly reduce the energy of vibration waves projected onto its surface. There are many kinds of microwave absorbing materials in common use, including graphite, ferrite, silicon carbide, conductive polymers that can absorb electromagnetic waves, and organic fiber materials, inorganic fiber materials, foam materials and microwave absorbing building materials that can absorb mechanical waves. However, the above-mentioned sound wave absorbing materials have poor noise reduction effect, short service life, easy deformation, and poor safety. The above-mentioned electromagnetic wave absorbing materials have high absorption density and poor high-temperature characteristics. At present, a comprehensive performance absorbing material with high absorption rates for both electromagnetic and sound waves has not been obtained.

To solve the technical problems existing in the existing technology, the present invention proposes a carbon aluminum composite absorbing material and its preparation method.To achieve the above-mentioned carbon aluminum composite absorbing material scheme, the present invention provides a method for preparing a carbon aluminum composite absorbing material, which specifically includes the following steps:

The plan uses carbon nanotubes and aluminum alloy as the main raw materials. Among them, the addition of carbon nanotubes increases the viscosity of the melt during the melting process, eliminating the need for thickening agents. On the other hand, it can significantly improve the specific strength of aluminum alloys, especially the chemical plating layer on the surface of carbon nanotubes, which can improve the compatibility and bonding strength between carbon nanotubes and aluminum alloys, further enhancing the strength of the aluminum alloy matrix. Under the same application conditions, the increase in material strength can provide higher porosity, thereby increasing the transmission distance of sound waves inside the material. At the same time, carbon nanotubes distributed on the surface of aluminum alloys have a nano scale open pore structure, which enables porous aluminum alloy materials to have a higher pore surface area. The combined effect of the above two aspects makes the propagation process of sound waves inside the material longer, thereby converting more vibration energy into heat energy and continuously consuming it, resulting in better absorption effect.

Meanwhile, the carbon aluminum composite absorbing material provided by the present invention introduces carbon nanotubes into the porous aluminum alloy matrix. The extremely high specific surface area and high proportion of surface atoms in carbon nanotubes can easily cause multiple scattering of incident waves; A large number of crystal defects and dangling bonds form intrinsic electric moments in carbon nanotubes, which easily lead to orientation polarization in a magnetic field and increase the dielectric loss of the material. The quantum size effect provides new channels for microwave absorption at the dispersed energy level intervals of electrons. Due to the combined effects of small size effect, surface effect, quantum size effect, and macroscopic quantum tunneling effect, carbon nanotubes exhibit excellent absorbing properties, and the porous aluminum alloy matrix introduced with carbon nanotubes is also endowed with excellent absorbing properties.

Specific implementation method

Below, a more detailed explanation of the present invention will be provided in conjunction with the embodiments.

Example 1

Load 8kg of 2024 aluminum alloy into a clean induction furnace and heat it to 710 ℃ under argon protection. After all the cold material is melted, remove the floating slag on the surface of the clean melt. Reduce the furnace temperature to 700 ℃ and introduce 0.2% to 0.4% hexachloroethane refining agent for refining inside the furnace. After refining, remove the floating slag on the surface of the melt.

Mechanically stir the aluminum alloy melt at a speed of 200rpm. Using powder spraying and argon gas as the carrier, 2kg of carbon nanotubes (with a carbon content of 50wt.%) prepared by surface chemical nickel phosphorus alloy plating were uniformly fed into the melt.

After the addition of materials is completed and the chemically plated carbon nanotubes are completely immersed, the melt is dispersed by ultrasound and stirred in sequence at 1000rpm for 20 minutes, 600rpm for 10 minutes, 1000rpm for 20 minutes, and 600rpm for 10 minutes. Mechanical stirring combined with ultrasound treatment is used to evenly disperse the carbon nanotubes in the aluminum alloy melt. At this time, as the carbon nanotubes are added and dispersed, the viscosity of the melt gradually increases. Then increase the stirring speed to 1500rpm, and use powder spraying to quickly disperse 100g of titanium hydride foaming agent (preheated at 300 ℃ for 2 hours) into the melt for foaming. After stirring evenly, remove the stirrer and let the ingot naturally cool and solidify in the furnace. After that, take out the ingot and process it mechanically to obtain carbon aluminum composite absorbing material.

After testing, the porosity of the absorbing material prepared in Example 1 was about 91%. A sample with a diameter of 5cm and a thickness of 3cm was taken for absorption performance testing, and the absorption coefficient for low-frequency noise at 200Hz was about 0.6.

Comparative Example

Load 8kg of 2024 aluminum alloy into a clean induction furnace and heat it to 710 ℃ under argon protection. After all the cold material is melted, remove the floating slag on the surface of the clean melt. Reduce the furnace temperature to 700 ℃ and introduce 0.2% to 0.4% hexachloroethane refining agent for refining inside the furnace. After refining, remove the floating slag on the surface of the melt.

Mechanical stirring was performed on the above aluminum alloy melt at a stirring speed of 200rpm, and elemental Ca was added to the melt. After the addition was completed, the melt was dispersed by ultrasound and stirred in sequence at 1000rpm for 20 minutes, 600rpm for 10 minutes, 1000rpm for 20 minutes, and 600rpm for 10 minutes. Through mechanical stirring combined with ultrasound treatment, CaAl2 and CaAl4 were fully dispersed in the aluminum melt. Then increase the mixing speed to 1500 rpm, spray powder to rapidly disperse 100g titanium hydride foaming agent (preheated at 300 ℃ for 2h) in the melt for foaming, stir evenly and then move out of the mixer. After the ingot is naturally cooled and solidified in the furnace, take out the ingot and machine it to obtain foam aluminum material.

A method for preparing a carbon aluminum composite absorbing material, comprising the following steps: (1) coating the surface of carbon nanotubes with metal elements or alloys through surface chemical plating treatment to obtain chemically coated carbon nanotubes; (2) Add the chemically coated carbon nanotubes coated with metal elements or alloys obtained in step (1) to the molten aluminum alloy by powder spraying, stir and disperse, so that the chemically coated carbon nanotubes are uniformly dispersed in the aluminum alloy melt; (3) Add foaming agent into the aluminum alloy melt obtained in step (2), stir to make the foaming agent evenly distributed, then rapidly pour it into the prepared mold, and after natural cooling, obtain carbon nanotube composite foam aluminum microwave absorbing material; (4) The surface of the above carbon nanotube composite foam aluminum absorbing material is ceramic treated to obtain the carbon aluminum composite absorbing material.

XRS2000 series three-stage emulsifier
The three-stage high shear emulsification machine is mainly used for the production of micro lotion and ultra-fine suspension lotion. Since three groups of dispersion heads (stator+rotor) in the working chamber work at the same time, after high shearing, the lotion drops are more delicate and the particle size distribution is narrower, so the stability of the generated mixed liquid is better. The three sets of dispersing heads are easy to replace and suitable for different process applications. The different models of machines in this series have the same line speed and shear rate, making it very easy to scale up production. It also meets the CIP/SIP cleaning standards and is suitable for food and pharmaceutical production.

High rotational speed and shear rate are important for obtaining ultrafine suspension lotion. According to some industry specific requirements, its shear rate can exceed 15000rpm, and the rotor speed can reach 44m/s. Within this speed range, turbulence caused by shear forces combined with specially developed motors can reduce the particle size range to the nanometer level. The shear force is stronger, and the particle size distribution of lotion is narrower.

The following is a model table for reference:

Carbon aluminum composite absorbing material three-stage emulsifier