Navegando por Autor "Vasconcelos, Wander Luiz"
Agora exibindo 1 - 2 de 2
Resultados por página
Opções de Ordenação
Item Infrared spectroscopy of titania sol-gel coatings on 316L stainless steel.(2011) Vasconcelos, Daniela Cordeiro Leite; Costa, Vilma Conceição; Nunes, Eduardo Henrique Martins; Sabioni, Antônio Claret Soares; Gasparon, Massimo; Vasconcelos, Wander LuizSol-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.Item Optical characterization of 316L stainless steel coated with sol–gel titania.(2012) Vasconcelos, Daniela Cordeiro Leite; Nunes, Eduardo Henrique Martins; Sabioni, Antônio Claret Soares; Vasconcelos, P. M. P.; Vasconcelos, Wander LuizIn this work 316L stainless steel substrates were coated with sol–gel derived films by means of the dip-coating technique. Titanium isopropoxide and ethanol were used as chemical precursor and solvent, respectively. The dip-coating step was performed using withdrawal speeds of 6 mm/min, 30 mm/min, and 60 mm/min. Next, the samples were heat treated in air for 30 min at 100 °C, 300 °C, and 400 °C. The processed composites were examined by FTIR and UV–vis spectroscopies. We observed that thematerials prepared in this work can exhibit a variety of colors depending on the heat treatment temperature, withdrawal speed, and precursor:solvent molar ratio used in their processing. It is an important finding since this behavior could lead to architectural application of these materials. We believe that the changes observed in the UV–vis spectra and the colors of these samples could be related to the variation of the coating thickness as the processing conditions were modified. FTIR tests revealed that the ratio between the intensities of features ascribed to hydroxyl groups and Ti\O bonds decreased as the heat treatment temperature was increased. On the other hand, the ratio between bands related to Ti\O\Ti and Ti\O bonds decreased when the heating temperature was raised from 100 °C to 300 °C.