Thermal oxidative stability of yttrium containing oligomeric silazanes with organoelement substituents and multiceramics on their basis

Abstract

Characteristics of thermal transformations of oligomeric silazanes with organoelement substituents at the N atoms (M-OESs) containing one element M = Y, Zr, or Hf or a pair of elements, viz., Zr and Y or Hf and Y, in air in the temperature range 200–1500 °C were investigated. The introduction of yttrium into zirconium- or hafnium-containing oligosilazanes results in an increase in the mass loss at the stage of ceramization and to a decrease in the mass loss in the formed ceramics during subsequent stepwise heat treatment up to 1500 °C. The combination of yttrium with hafnium or zirconium in M-OESs results in a synergistic effect of overall mass loss reduction. The (Zr, Y)-OES and (Hf, Y)-OES multiceramics outperform ceramics modified with one metal in this parameter. The obtained multiceramics is characterized by high thermo-oxidative stability in the temperature range 1100–1500 °C. It is also found that yttrium-containing oligosilazane (Zr, Y)-OES exhibits oleophilic properties with respect to carbon materials.