Effects of yttrium on structure evolution of silicon oxycarbide derived from polysiloxane

Polymer-derived Silicon oxycarbide (SiOC) and yttrium-containing silicon oxycarbide (SiYOC) ceramics were obtained in the present work. To investigate their high temperature behaviors in low pressure atmosphere, these ceramics were further annealed at 1200 degrees C, 1300 degrees C, 1400 degrees C, and 1500 degrees C. The structure evolutions of SiOC and SiYOC ceramics through heat-treatment were studied. It was found that the carbothermal reductions of SiOC ceramics were activated at 1400 degrees C and almost finished at 1500 degrees C. The introduction of Y element played a major role on high temperature stability by influencing the structure evolution of SiOC and hindering the carbothermal reductions. The results show that introducing yttrium to modify the SiOC structure should be an effective way to enhance the thermal stability of SiOC ceramics.