Preparation of MgAl2O4 Spinel through Different Wet Chemical Methods and Study of its Densification Behavior.

Abstract

MgAl2O4 spinel was prepared through three different routes, i.e. Auto-Combustion process, Citrate sol-gel process and Co-precipitation process. Spinelization was studied at three different temperatures (6000C, 7000C, 8000C) for Auto-Combustion process and Citrate sol-gel process and two different temperature (6000C, 7000C) for Co-precipitation process. Optimization was done for all the three routes to achieve phase pure spinel at lowest possible calcination temperature. Phase pure spinel was achieved at 6000C in Co-precipitation process, whereas 7000C was required to prepare phase pure spinel in case of Auto-Combustion process and Citrate sol-gel process. Spinel powders prepared by Co-precipitation process shows relatively high average particle size(800nm).whereas spinel powders prepared by citrate sol-gel and auto combustion route, have an average particle size of around 300 nm. Spinel powders were made into pellet and sintered at three different temperatures i.e. 14500C, 15000C, 15500C . Higher density values were obtained for the citrate sol gel method. A highest density of 3.23 g/cc was obtained for this samples sintered at 1550oC. TiO2 was added as a sintering additive to Spinel powder samples made by all three processes and its effect on the densification behavior was studied. These samples were sintered at three different temperatures i.e. 14500C, 15000C, 15500C. TiO2 addition enhances the densification of spinel prepared through all three methods. Highest density achieved were 3.13 and 3.03 for Co-precipitation and Auto-combustion methods respectively. Again Higher density values were obtained for the citrate sol gel method. A highest density of 3.3 g/cc was obtained for this samples sintered at 1550oC.