The influence of the agglomeration state of nanometric MgAl2O4 powders on their consolidation and sintering

This paper presents the results of investigations on the consolidation of nanometric magnesium–aluminum spinel powders through pressure filtration of their aqueous suspensions. A portion of the pressure-filtrated samples was subjected to cold isostatic pressing. To assess the effectiveness of the pressure filtration method, dry powders were uniaxially or isostically pressed under various pressures and the pore size distributions of all samples were compared. Samples were sintered in a dilatometer at temperatures up to 1550 °C and isothermally sintered in air at 1600 °C for 3 h. The agglomeration state of the powders was investigated using methods such as XRD, TEM, BET and laser diffraction, and the resulting characteristics were used to explain differences in the consolidation and sintering behavior of the powders. It was shown that the pressure filtration method was capable of consolidating nanometric spinel powders suspensions, leading to green samples with a narrow pore size distribution whose density exceeds 99% when sintered at 1600 °C.