Universidade do Estado do Rio de Janeiro – BIBLIOTECAS DA UERJ
2017
Síntese e caracterização de óxidos mistos precursores de CexOy/Al2O3 por método sol-gel
HUGO DE SOUZA CALDEIRA

Abstract

The sol-gel method is based on the transition from the sol system to the gel system, through reactions in precursor materials, which can be metal alkoxides or inorganic salts. Among the reactions, since getting the sol until reach the gel, hydrolysis, condensation and polymerization are mentioned. This method is widely used because of its versatility and low temperature treatment. The lyophilized powder of CxOy/Al2O3 was obtained by the process of lyophilization of the properly frozen sol. The characterization of the powder was performed through the TG, DTA and DSC thermal analyzes for checking the behavior of the material when subjected to a programmed heating rate. The crystalline structures were evaluated by X-ray diffraction according to the Rietveld method, that do the refinement of the generated peaks making easy the interpretation of the results. Four types of samples were synthetized with different types of composition involving the mixed oxides. A portion of the sol generated by the initial reactions was aged and used for deposition on glass substrates. The deposition was done by the dip coating method, which is a simple and easy method of handling the substrates. The tests to assess the level of wettability of the substrates were done on the coated substrates of the mixed oxides obtained.

Keywords: Sol-gel; X-ray diffraction; Thermal analyzes; Dip coating; Wettability