The thesis is written in Latvian, contains an introduction, literature review, methodological part, experimental part, conclusions and bibliography with 140 references. The thesis consists of 129 pages, 72 figures and 31 tables. Literature review summarizes the most important investigations of silicon nitride-based ceramics. Compaction of plasma synthesized silicon nitride-based particulate nanocomposite with different sintering techniques, received ceramic structure and properties are investigated in the experimental part of the thesis. The relationships of Si3N4-Al2O3-Y2O3 nanopowders composites sintering by conventional sintering, hot pressing and sintering in solar furnace in comparison with composites prepared from the industrial powders are determinated. The influence of TiN, ZrO2 and SiC nanopowders additives on Si3N4-Al2O3-Y2O3 nanocomposite materials microstructure formation and mechanical properties improvement is established. The effect of introduction mode of sintering additives on the Si3N4-SiC nanopowders composites microstructure formation by hot pressing is found. The alpha -, beta - sialons compacting technique and mechanical properties of compacting materials are established. The advantages of using of silicon nitride-based nanopowders for manufacture of nanostructured ceramics are presented.