Study of protection films on Al by means of optical reflection methods: silane films

摘要

Spectroscopic ellipsometry in the spectral range between the near UV and the near IR (250-1700 nm) (SE) and in the mid- and far-IR (1,6 - 43 μm) (IRSE) has been used for the characterisation of various thin coatings on aluminium. This method measures the polarisation change of the radiation due to the interaction with the sample surface. It is called spectroscopic if the measurement is performed at various wavelengths within the spectral range. Both spectroscopic ellipsometry (SE) and infra red spectroscopic ellipsometry (IRSE) provide information concerning the morphological features of the coating, but due to the presence of characteristic absorptions IRSE also reveals the chemical composition. The feasibility of using SE and IRSE for the characterisation of silane films deposited on different pretreated aluminium substrates is demonstrated in the case of the non-functional bis-1,2-(triethoxysilyl)ethane (BTSE). The effect of the concentration of BTSE present in the bath is given. Direct evidence of modification in BTSE layer structure, induced by the curing of the silane coated panels is underlined.