Research Of Surface Modification Of ?-Al₂O₃ And Preparation Of UV-curable Ceramic Suspensions

Stereolithography of UV-curable ceramic suspension can benefit from the preparation of stable,low viscosity and high solid loading ceramic suspensions with low yield stress.Appropriately adding dispersants could optimize the rheological behaviour to meet the requirements of stereolithography.In this work,a simple method of preparation of UV-curable ceramic suspension was proposed for ceramic stereolithography,which was proved to be feasible for the 3D printer for stereolithography.This method can be divided into three steps:1.Preparation of UV-curable dispersion medium for the alumina suspension through ultrasonic and magnetic stirring.2.Dicarboxylic acids were utilized as dispersants to modify the suface of?-Al₂O₃ powder by roller mixer in the solvent of ethanol.3.The modified alumina powder was dispersed into UV-curable dispersion medium by ball-milling.In this work,the maximum adsorption capacity of dicarboxylic acids was determined by the method of High Performance Liquid Chromatography.The mechanism of surface modification was proved to be monolayer chemisorption and the adsorption curves can be depicted by Langmuir's isotherm.When the doses of dicarboxylic acids reach their maximum adsorption capacity,the alumina suspensions would achieve the lowest viscosity and yield stress.Dicarboxylic acids'mechanism of dispersion was also discussed.Dicarboxylic acids'influence on the rheology behavior was systematically studied by Yasuda's equation.The relationship between solid loading and viscosity can be well depicted by the Krieger-Dougherty model.The low curing density of monomers is a significant limiting factor for densification.45 vol%alumina suspensions with a viscosity?2 Pa·s at shear rate 30 s^-1 and the corresponding printing body were successfully formulated.A sintering density of 97%and homogeneous microstructure can be achieved for the dicarboxylic acids-modified alumina UV-curable suspensions and the sintered alumina possesses relatively fine grain size of 2-4?m.