Effect of aluminum oxide particle characteristics on polishing suspensions property

In this thesis, nano particle sized, high purity alumina (Al2O3) production which does not have any production in Turkey, stable suspension preparation from producing alumina and polishing performanses of alumina suspensions are considered. Sythesis of 1 µm average particle sized and high pure (%99.94 and higher) aluminum trihydroxide [Al(OH)3] is succeed from metallurgical grade 91 µm average particle sized Al(OH)3, with controlling the particle size by dissolution-precipitation method. After production, calcination of Al(OH)3 powders is occured in order to transform α-Al2O3. Characterizations of calcined alumina is performed. Then, similar commercial products are supplied and comparisations between producing alumina is occured. Stabilizations of commercial and calcined aluminas in a dispersion are performed with polielectrolyte (Darvan C-N) addition between 0 and 1.50 mg/m2 in order to understand the effective powder and dispersion properties for stable suspension. 0.001 mg/m2 polielectrolyte addition were enough for produced alumina particles which become unsettled. Obtained stable suspensions are used as a polishing paste on metal surfaces because of alumina's high hardness property. Then surface qualities of polishing samples are characterized and performance results of producing and commercial powders are compaired and presented. After polishing, producing powders included suspension provides %76 average surface quality increment. Therefore, the result becomes higher from 3 commercial powders included suspensions. Keywords: Heterogeneous precipitation, Alumina, Suspension, Sedimentation, Polishing