MnO 2 and ZnO additives, at three different weight percentages of 0.7, 1.4, and 2.1 wt%, were added to pure MgTiO 3 ceramic obtained by coprecipitation method. Effects of these additives on microstructure, density, and dielectric properties of bulk products were investigated. The density of sample prepared from the synthesized MgTiO 3 powder was 3.65 g/cm 3 after sintering at low temperature of 1050̊C. Results showed that the density of samples consolidated from MgTiO 3 submicrometer particles (less than 200 nm) containing 2.1 wt% MnO 2 and ZnO was increased to 3.71 g/cm 3 and 3.78 g/cm 3 , respectively, at low sintering temperature of 1050̊C. Also, the dielectric properties of sample containing 2.1 wt% ZnO were the best with e r of 16.9 and Q9f of 141000 GHz.

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Porous ceramic materials have found widespread technological and industrial applications from filtration, absorption, catalysts and catalyst supports to lightweight structural components. In the present work, processing is based on the generation of foam from an aqueous suspension of ceramic powder and the subsequent stabilization of the structure by in-situ polymerization of organic monomers. The process offers a number of advantages from other processes. It is shown here, the in-situ polymerization of organic monomers led to a fast solidification and strong, porous bodies. SEM results showed, that the ceramic foams had highly interconnected network of spherical cells with low densities. The cell size distribution was dependent on the density of the samples as well as the polymerization onset time. Good correlations were found between the green microstructure, rheology of the suspensions and the particle interaction forces.

Alumina foams with high mechanical strength were prepared by means of gel-casting. After preparation of gel-cast raw segments, they were dried in a controlled humidity chamber. Samples were sintered at a temperature of 1 350 °C held for 2 h. The effects of additives and alumina loading on the initial suspension behavior, ultimate porosity, relative density, and mechanical strength of sintered samples were investigated by means of different techniques including densitometry, scanning electron microscopy and compressive strength measurements. Results showed that the optimal conditions for the preparation of desired alumina foam are 0.03 wt.% of sodium dodecyl sulfate, 1 g L−1 of initiator and 8.3 mL L−1 of catalyst for suspensions with 0.8 – 1 wt.% of Tiron and 70 % of alumina loading. The value of compressive strength was measured as high as 25.62 MPa for alumina foam with very low relative density of 19.27 %.