Preparation and Infrared Reflection Performance of Al/Cr2O3 Composite Particles

The composite pigments were prepared by co-precipitation coated Cr2O3 on the surface of flake alumi- num powders. Phase structure, surface morphology and reflectance spectra of the composite pigment were charac- terized by XRD, FE-SEM, UV/VIS/NIR spectroscopy and Fourier transform infrared spectrometer. The result shows that the influence of cover treatment with Cr2O3 on the reflectance spectra at various radiation wavelengths is different. The shorter the wavelength is, the stronger the influence is. When the molar ratio of Cr 3+ to Al is 0.2:1.0, compared with the uncoated flake aluminum powders, its average reflectance of visible spectrum and brightness (L*) drop to 50% and 15, respectively. However, the infrared emissivity of 8-14 μm waveband increases less than 10%. It mainly ascribes to the difference of surface roughness and absorption coefficient for different radiation wave- lengths. Thus, the composite particles play a vital role in designing the low infrared emissivity coating.