Aluminum Flake Surface Coating Of Sio <sub> 2 </ Sub> And Fe <sub> 2 </ Sub> The O <sub> 3 </ Sub>

The coating of SiO₂ and Fe₂O₃ on the surface of aluminum flake powder has been investigated. In the case of SiO₂ coating, tetraethyl orthosilicate(TEOS) was used as the precursor. The coating process involved the method of adding reactants, reaction time, reaction temperature, the addition of TEOS, the proportion of distilled water to TEOS, the type of the catalyst and its concentration. It was found that there are no hydrogen evolution in 0.5mol/L HC1 solution for the aluminum powder after coating by SiO₂ under the best condition: The TEOS and ammonia diluted individually in isopropanol were instilled gradually, the reaction temperature is from 35℃to 40℃, the addition of TEOS is 20%, the proportion of distilled water to TEOS is between 25 and 65, and the volume ratio of the catalyst-ammonia is between 0.016(vol)% and 0.024(vol)%. Then, the aluminum powder with SiO₂ was re-coated by Fe₂O₃ and it was found that the powder with purity excitation of 10.8% and luminance of 71.81 was prepared when the pH value is 3.0, the addition of FeCl₃ is 10%, and the reaction temperature is 70℃.The aluminum flake powder coated by SiO₂ and Fe₂O₃ was characterized by Scanning Electron Microscopy and Infrared Ray Spectroscopy. The results show that the surface of aluminum powder coated by SiO₂ is glossy, while some particulate granule was deposited on the surface after re-coating by Fe₂O₃. It was found that there are peaks of Si-O-Si & Si-OH and peak of Fe-O in the FIR chart of the aluminum powder coated by SiO₂ and re-coated by Fe₂O₃ respectively.