Optical properties and thermal durability of copper cobalt oxide thin film coatings with integrated silica antireflection layer

Copper cobalt oxide (Cu2CoO3) thin film coatings integrated with silica (SiO2) antireflection (AR) layer have been deposited on the top of aluminum substrates using a simple sol–gel dip-coating method. Reflectance spectra of the coatings were generated using spectroscopic methods while the coatings were subjected to an accelerated thermal durability test. The addition of silica changed the reflectance spectra of coatings within the wavelength range of 0.3–15.4 µm. The absorptance decreased with the increase of the withdrawal rate in range of 10–40 mm/min, while the emittance increased with the increase of the withdrawal rate. The optimum optical parameters for this study were absorptance, αS=84.96%; emittance, εT=5.63% corresponding to the coating with a silica AR layer at withdrawal rate of 10 mm/min. The coatings with the silica AR layer were shown to be thermally durable in which no discernible ‘cracking’ phenomenon was observed. The degradation of the coatings with the silica AR layer was predominantly governed by temperature changes rather than exposure time.