THE INFLUENCE OF VARIOUS SUBSTRATE TREATMENTS ON MORPHOLOGY AND SELECTIVE ABSORBER CHARACTERISTICS OF ELECTROCHEMICAL BLACK CHROME

Various substrate treatments such as mechanical polishing, chemical et ching, and electropolishing prior to the electrochemical deposition of a black chrome solar selective absorber on a Cu substrate influence t he structure, morphology, chemical composition, and selective absorber characteristics of black chrome. The X-ray diffraction (XRD) and scan ning electron microscopy (SEM) analysis of the structure and morpholog y of black chrome showed that electropolishing of the substrates prior to film deposition results in coatings with more metallic chromium an d mechanical polishing favours the formation of more oxides of chromiu m. Those films on copper substrates treated by mechanical polishing fo llowed by electropolishing exhibited good solar selective characterist ics, whereas chemical etching of the substrates resulted in black chro me with poor solar selectivity.