Modeling and optimization of densification of nanocrystalline Al₂O₃ powder prepared by a sol–gel method using response surface methodology

Response surface methodology (RSM) based on central composite design (CCD) was successfully applied to the optimization and modeling of densification of nanocrystalline Al₂O₃ powder prepared by sol–gel method. The effects of three operating variables, sintering temperature, calcination temperature and milling time on the densification of nanocrystalline Al₂O₃ were systematically evaluated. A quadratic model for densification was proposed. Analysis of variance (ANOVA) indicated that the proposed quadratic model could be used to navigate the design space. The simulated values obtained from the statistical model were in conformity with the experimental results within an average error of ±1.5%. The optimum operating conditions for densification were found to be 1,579 °C of sintering temperature, 909 °C of calcination temperature and 117 min of milling time. The obtained density under the optimum conditions determined by RSM was 98.5%. The results confirmed that RSM based on central composite design was an accurate and reliable method to optimize the densification conditions of nanocrystalline Al₂O₃ powder.