In the work the research on properties of an yttria nanopowder obtained by solution combustion synthesis (SCS) in terms of its application in ceramic technology is presented. In order to characterize the SCS reaction the decomposition of yttrium nitrate, glycine and their solution was investigated using differential thermal analysis coupled with FT-IR spectrometry of the gases emitted during the measurements. The product obtained in the SCS process was characterized in terms of its microstructure, particle size distribution and BET specific surface. Although the obtained powders showed nanoscaled structures, only after calcination at a temperature of 1100 °C nanosized particles were revealed. The calcined powder occurred in an agglomerated state (cumulants mean Zave = 1.3 µm). After milling particle size was successfully decreased to Zave = 0.28 µm. The deagglomerated powder was isostatically densified and tested for sintering ability. The obtained nanopowder showed very high sintering activity as the shrinkage onset was detected already at a temperature of about 1150 °C.

The present research is focused on the characterization of the composites from Al 2 O 3-Cu-Mo system. The composites were prepared by slip casting method and subsequent sintering of green bodies in a reduced atmosphere. Two series of samples with different volume content of metallic powders were produced in the work: 10 vol% and 15 vol% of metal content with respect to the total solid-phase content. The sintering process of the composites was analyzed in detail. The linear shrinkage of the composites was measured. The shrinkage curves were obtained by dilatometry test in a heating mode. The composites were characterized by DTA/TG analyses and thermal conductivity. The composites were characterized by XRD, SEM, and EDX. The hardness was measured by Vickers hardness tester. Moreover, the Brazilian test was performed to determine the tensile mechanical properties of the composites. Fractography investigation was carried out as well. Dilatometric tests showed that the increase of the metallic phase volume in the ceramic matrix causes a decrease in the starting temperature of densification. Simultaneously, dilatometric experiments indicated that an increasing amount of metallic particles into the ceramic matrix increases the temperature of maximum densification and decreases the total shrinkage of the composites during sintering. The DTA/TG showed the characteristics of the dispersant decomposition to the atmosphere during thermal treatment and increase of mass connected with the oxidation of metals. Fractography results revealed good adhesion between Al 2 O 3 matrix and the metallic phase. The observation allowed to conclude that the Al 2 O 3 matrix surface is characterized by the brittle fracture mechanism.

Alumina-nickel composite samples (with 0, 10 and 20 vol.% of Ni) are prepared via slip casting method. Nickel and aluminium oxide powders were used as precursors and diammonium hydrocitrate and citric acid were used as dispersants. The obtained materials were analysed by dilatometry, X-ray diffraction and SEM. The densities were measured by Archimedes method and the hardness and fracture toughness were determined by using Vickers hardness tester. Special attention was paid to the linear shrinkage and the effective coefficient of thermal expansion measurements. The shrinkage curves were obtained by dilatometry test in a heating mode. It was shown that the increased amount of Ni particles in Al 2 O 3-Ni composite structure causes reduction of starting densification temperature, increasing temperature of maximum densification and decreasing total shrinkage of the sample during sintering.