Infrared reflection by alumina films produced on aluminum alloy by plasma electrolytic oxidation

Reflection of active or passive infrared waves is of practical interest and in this paper, we report the use of plasma electrolytic oxidation (PEO) to fabricate a porous and rough ceramic coating that is capable of reflecting active or passive infrared waves. The pore dimensions of the coatings are on the order of infrared wavelength. In addition to heat isolation, reduction in reflection by multiple scattering can be accomplished. According to results obtained from alumina coatings with different thicknesses prepared by PEO on LD31 Al alloy, obvious decrease in the reflection of infrared waves from 780 nm to 3000 nm is observed. Our results suggest that the porous and rough surface influences the infrared reflection efficiency.