Infrared spectroscopy of titania sol-gel coatings on 316L stainless steel.

Abstract

Sol-gel titania films were deposited on 316L stainless steel using titanium isopropoxide as a chemical precursor. Dip- coating was performed at withdrawal speeds of 6 mm/min, 30 mm/min, and 60 mm/min. Deposited gel films were heat treated in air at 80°C, 100°C, 300°C, and 400°C. The structural evolution of the coatings was evaluated by infrared reflection-absorption spectroscopy. The influence of the withdrawal speed and the heat treatment temperature on the structure of the films was studied by varying the reflectance incidence angle during the infrared experiments and by Glow Discharge Spectrometry. Free functional groups were detected. The results indicate the formation of bidendate bridging coordination of carboxylic acid to titanium. Titanium atoms can also be pentacoordinated according to the processing conditions of the films. We observed a tendency of increasing amounts of OH groups with decreasing re- flectance incidence angle. The film hardness was measured via Knoop microindenation hardness test.