Dispersão e estabilização de partículas submicrométricas de óxido de alumínio em sistemas líquidos destinados à produção de materiais refratários

• Ano de defesa: 2009
• Autor(a) principal: Viviane Faria Soares
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Potencial Zeta; Dispersão; Alumina; Físico-química; Potencial zeta; Química
• Link de acesso: http://hdl.handle.net/1843/BIRC-86FJ5F

Aluminum oxide is a material widely used in industry, especially in ceramics, due to its mechanical, thermal and refractory properties. For using this material in submicrometric size range it becomes necessary to disperse the particles which present great tendency to agglomerate. The state of dispersion of the particles is directly related to the electrostaticsurface potential, the presence of surfactants and the ionic concentration of the medium. The aim of this work was the evaluation and optimization of these variables, in order to obtain stable suspensions. The zeta potential, the viscosity of the suspensions, the sedimentationdegree and the agglomerate / aggregate sizes have been determined for four different commercial aluminas. Through a fractional factorial plan it was possible to determine the influence of the variables on the state of dispersion of the particles. Among the studied aluminas, T3000-SG/Almatis presented the higher degree of dispersion and stability The optimum system which was economically feasible corresponds to addition of 0,2% wt (dry basis) of citric acid for suspensions with low solids charge and 0,2% wt of ammonium polymethacrylate for suspensions with high solids charge, in pH around 9.