RADAR absorbing materials employing Fe3O4 nanoparticles
Stealth technology can in principle be either RAM (radar absorber material) or RAS (radar absorber structure) . RAMs are materials that have reflection loss of <-20 dB (equivalent to the absorption > 99%) with the absorption frequency band which is related to the width of radar waves. Using this technology, a moving object (aircraft, ships, rockets or missiles) enables to be undetectable by radar. With the performance, the concerned technology is becoming very important in the world of defense and security, especially defense equipments. One type of RAM made of raw material obtained from the Fe3O4 magnetic iron sand has been fabricated in this study.
1. Iron sand is first screened to obtain a Fe3O4 fine powder separated from non-magnetic materials and other impurities.
2. Through the process of coprecipitation by substitution of Ni and Zn in order to improve the properties of magnetism, the Fe3O4 starting material is converted into (Ni,Zn)Fe2O4 powders having size of about 25 nm.
3. The final absorbent system consists of the (Ni, Zn)Fe2O4 nanoparticles mixed with conducting materials (conductive polymers or metals) to form the “core-shell” structure that has increased absorbance in the frequency range of radar wave (microwave). The resulted powders are dissolved in a solvent and coated onto the object’s surface.