Ytterbium Oxide Influence on the SHS Parameters and Phase Make-Up of Silicon Nitride Based Compositions

Self-propagating high-temperature synthesis (SHS) was used to prepare SHS compositions based on the system Si₃N₄–Yb₂O₃ system. Synthesis was conducted in a nitrogen atmosphere at 4 MPa in a 30 L reactor. The weight of the loaded charge was 3 kg. It was ascertained that the amount of ytterbium oxide in the charge affects the combustion temperature and the phase composition of the synthesis products. As the proportion of ytterbium oxide in the charge increases, the α-Si₃N₄ content decreases, and the secondary phases are represented by quaternary silicon ytterbium oxynitride and ytterbium disilicate.