1983 Volume 91 Issue 1052 Pages 164-170
The equimolar spinet powders have been synthesized by spray-pyrolysis of the water-methanol solutions of magnesium and aluminum nitrates, and their sinterability was studied. The specific surface area and pore volume of the powder depended on the calcination temperature and showed maximum values when calcined at 400°C. Although the primary particle size and the specific surface area of the powder calcined at 400°C were 150Å and 120m2/g, respectively, the lattice parameter of the powder was 8.081Å, suggesting that the particles are composed of the nearly perfect spinel lattice. The as-sprayed powder showed poor sinterability, but the grinding increased the sinterability to a great extent. As the methanol content in the solvent was increased, the agglomerated particles became fragile and tended to fracture more easily by compression. Censequently, the bulk density of the sintered body increased with decreasing of the ratio of water/methanol ratio in the solvent. A sintered body with 97% of theoretical density was obtained when the spinel powder was prepared under the optimum conditions and sintered at 1500°C for 4h. The sinterable powder was obtained when a water-methanol (1:1) solution containing 0.3mol/l Mg and Al was spray-pyrolyzed at 800°C, followed by grounding and calcination at 800°C for 1h. and calcined at 800°C for 1h.
