Preparation and characterization of micro-copper flakes /nano-TiO2 composite particles

Micro-copper flakes were coated with nano-TiO2 in an ethanol-based colloid sol by chemical deposition, in order to improve their oxidation resistance. The as-prepared composites were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Results showed that TiO2 nanocrystals (predominantly anatase) of approximate 10 nm in size were successfully deposited on the surface of Cu flakes, forming a granular coating. The growth of titania on the copper flakes seems to be implemented by anchoring TiO2 through Ti-O-Cu bonds. The thermal stability of the composites was tested by thermogravimetric analysis (TGA) in an air atmosphere. The results showed that TiO2-coated copper flakes acquired better oxidation resistance compared to the pure copper flakes. Oxidation in air of pure copper flakes began at 190 °C, whereas the composites did not oxidize until 360 °C.