Ablative properties and mechanisms of hot vulcanised silicone rubber (HVSR) composites containing different fillers

Abstract

Hot vulcanised silicone rubber (HVSR) composites were prepared using silicon carbide (SiC), hafnium oxide (HfO₂), zirconium oxide (ZrO₂) and zirconium boride (ZrB₂) as fillers, respectively. The tensile properties and the ablative response of the composites were examined. Tensile tests indicated that the tensile strength of HVSR was increased by the incorporation of ZrB₂. The linear ablation rate of the composites increased in the order HVSR/ZrB₂ < HVSR/ZrO₂ < HVSR/SiC < HVSR/HfO₂ < blank HVSR. The maximum back-face temperatures of the composites acquired from the burnt specimens during the ablation test were 350 and 364 K for the HVSR/ZrB₂ and HVSR/ZrO₂, respectively, compared to that of 333 K for the blank HVSR. Scanning electron microscopy and X-ray diffraction results showed that the dense and rigid ceramic layer was hard to peel off under the high pressure and shearing forces of ablative gases. The HVSR/ZrB₂ specimens exhibited the best ablation resistance among all the composites involved in this work.

Keywords:

• Silicone rubber
• Oxyacetylene torch test
• Anti-ablation filler
• Zirconium boride
• Back-face temperatures

Acknowledgements

We thank the General Program of Natural Science Foundation of China (51472048), International Cooperation Project (F16-214-6-00) and General Project of Science and Technology Research Project (F15-199-1-18) from the Department of Science and Technology of the city of Shenyang for financial support. Partial support from Public-funded Projects Foundation (2015004001) of Liaoning Provincial Department of Science and Technology is also gratefully acknowledged. Y. Liu acknowledges Shenyang Ligong University for the award of an Open Fund of the Key Discipline for Materials Processing Engineering.