Black Co oxides coatings for thermosensitive polymer surfaces by low-temperature DLI-MOCVD

Abstract

Black coatings are deposited at low temperature in order to enable the functionalization of thermosensitive substrates, such as epoxy-based carbon fiber reinforced polymers (CFRP). The direct liquid injection metalorganic chemical vapor deposition of Co oxide films is performed with the dicobalt octacarbonyl precursor, Co2(CO)8, in the temperature range 50°C–160°C, on Si substrates, first. Films morphology can be described by a dense sublayer on which the typical “cauliflower” microstructure grows, with a large amount of voids and open porosity. We obtain nanocrystalline CoO in the deposition temperature range 50°C–125°C, and nanocrystalline (CoO+Co3O4) above 125°C. The bulk composition of the films is Co(45)O(45)C(10). Over the deposition temperatures tested, films processed at 125°C repetitively show the lowest reflectivity in the visible range. An important role in the optical reflectivity is attributed to the carbon content, although it is not possible to decorrelate microstructural changes from the carbon elimination in calcination experiments. Finally, we reproduce the above-mentioned results with success on CFRP substrates, and demonstrate the applicability of the process on thermosensitive composite parts with results comparable to the state-of-the-art in the visible range.