Structural, optical, and mechanical properties of cobalt copper oxide coatings synthesized from low concentrations of sol-gel process

摘要

Thin films of Co_xCu_yO_2 have been coaled on aluminum substrates via sol-gel route using low concentration of copper and cobalt precursors at annealing temperatures in range of 500-650℃. The coalings were characterized by X-ray diffraction (XRD), X-ray pholoeleclron spectroscopy (XPS), UV-Vis-NIR spectrophotometry, and nannindentntion. The XRD analysis in 2θ-rangc of 30°-42° revealed that the coatings exhibited low crystallinily of CoCu_2O_3. CoCuO_2. and CuCoO_2. The surface bonding structure analyzed using XPS indicated that the coaling contained: Cu (tetrahedral Cu~+ and octahedral Cu~(2+)), Co (octahedral Co~(3+) . tetrahetiral Co~(2+), and mixed Co~(2+) and Co~(3+)), and O (lattice, surface, and sub-surface oxygens). The optical properties characterized using UV-Vis-NIR showed that the reflectance spectra of coatings formed a spectrally solar selective absorber profile associated with the interference peaks and the absorption edges around wavelengths of below l.2μm. The maximum absorplancc (α-75.8%) was shown by coaling synthesized at 500 ℃. The mechanical properties of coatings showed that the increase of annealing temperature increased the coating's hardness (H) and the clastic modulus (E) due to the enhancement of the [CoCuO_2/CuCoO_2]:[CoCu_2O_3] oxide phases ratio, as the result, an excellent stability of the wear resistance (H/E) of around ～0.035 was recorded.