The Thermal Stability, Ablation Properties, Creamization Mechanism of Graphite/Zirconia (ZrO2)/Silicone Rubber Composites Containing Carbon Multicomponent Systems

Abstract

It is urgent to improve the long-term ablation resistance of silicone rubber composites in order to meet the application requirements in the field of aerospace thermal protection. The graphite/ZrO2/silicone rubber (G/ZrO2/SR) composites prepared in this study were for that purpose. Firstly, the thermal stability and ablation properties of the G/ZrO2/SR composites were studied. The results showed that with the increase of graphite content, the initial decomposition temperature of the composites increased from 456.5 °C to 478.6 °C. The linear and mass ablation rates of the G/ZrO2/SR composite with 3 phr graphite were 0.048 mm/s and 0.0,220 g/s, respectively, which were decreased by 14.3% and 9.1%, compared with the ZrO2/SR composite without graphite. Moreover, the phase composition transformation and ceramization mechanism at high temperature of the G/ZrO2/SR composites containing carbon multicomponent system were studied. The results showed that the SR matrix completed the ceramic transformation during the ablation process and -Si-O-C pyrolysis products were formed and served as the skeleton of the ceramic layers. Finally, SiO2 and ZrO2 reacted with the graphite individually and the in-situ SiC and ZrC ceramic products formed enhanced the ceramic layers.