Silicone rubber ablative composites improved with zirconium carbide or zirconia

Silicone rubber ablative composites with zirconium carbide (ZrC) or zirconia (ZrO2) were prepared and tested for thermal protection systems. The incorporation of ZrC or ZrO2 powders increased the tensile strength but reduced the elongation at break of the composites. The thermal stabilities of the composites were enhanced by adding ZrC or ZrO2. The ceramic layers containing ZrO2, SiO2 and SiC were formed on the ablated surface of the composites with ZrO2 or ZrC, and acted as effective oxygen and heat barriers. The ablated surface of the composite with ZrO2 was more uniform than that of the composite with ZrC in the experiment. The linear ablation rates of the composites were reduced by 40% and 72% by the incorporation of 40 phr ZrC and ZrO2, respectively.