Optimizing the gel-casting parameters in synthesis of MgAl2O4 spinel

In this paper MgAl2O4 spinel powder with average particle size of 90 nm, purity of 99.99%, with stoichiometric ratio α-Al2O3 and MgO and only 0.8 %wt. LiF add-on was solid-state synthesized at a temperature of 1300 °C and used in gel suspension with 83% solid load. Using the optimal value of ISOBAM (0.9 %wt.) as both dispersion and gelation factors led to a significant increase in the relative density of green body from 48.5% to 62.2%. Relative density increased after sintering at 1550 °C for 1 h from 78% to 99.6% and pore size (40 nm) reduced to half the size of powder particles. Also, it resulted in appropriate pore distribution, because of the low number and value of the add-on in the gel system, and also optimization and preparation of nanopowders, as well as preparation and manufacture of suspension. XRD, BET, ICP, FESEM, FTIR analyses were done for synthesis and preparation of powder. Viscometery, Rheometery, Porosimetery, TG-DSC, Zeta potential, and sediment deposition analyses were done in order to optimize the parameters of the casting.