Preparation And Properties Of HTV Ablative Composites

Rubber ablative composites were widely used in insulation layers of solid rocket motor. In this paper, silicone rubber based ablative composites were researched, aiming to get a better quality ablative composites. First, basic rubber composed by silicone rubber, carbon fiber and silica were studied by single factor experiment. Second, choice the best ablative fillers from SiC, ZrO2, ZrB2andB4C Finally, ZrO2/silicone rubber ablative composites were researched through orthogonal experiment, the optimum formulation was acquired, with the ablative layers were also analyzed.The result showed that:The ablation properties of basic rubbers were improved by increasing the content of PVMQ, with tiny effect on the mechanical properties. Increasing the content of silica were improved the mechanical properties, but no effect on improve the ablation properties. The ablation properties of basic rubbers were improved by adding Carbon fiber, but harmful to the mechanical properties, what is more, Carbon fibers with length of 6mm was better than 3mm.ZrO2 was the best ablative fillers from four kinds of inorganic fillers. The ablation rates of the basic rubbers reduced by increasing the contents of ZrO2, little influence on mechanical properties.The content of PVMQ was the main factor of the ablation properties of ZrO2/ silicone rubber ablative composites. Mechanical properties of composites was mainly affected by silica. The addition of ZrO2 played a positive role in composite material, the formula of the ZrO2/ silicone rubber ablative composites with the best properties is:100 Phr silicone rubber with (PVMQ)/[m(VMQ)+ra(PVMQ)]= 50%,30 Phr silica,12 Phr carbon fiber (6mm),30 Phr ZrO2. Mass ablation rate was 0.0528g/s, linear ablation rate was 0.044mm/s, tensile strength was 5.28MPa, density was 1.29g/cm3.Ablative layers of ZrO2/ silicone rubber ablative composites can divided into the surface layer, charring layer, pyrolysis layer, virgin layer. Surface layer is mainly formed by SiO2 layer, charring layer is formed by carbon, ZrO2, carbon fiber and SiO2 with compact structure. The SiC that produced in ablation process was distribution in the surface layer and charring layer. Part of SiO2 in the ablative layer was come from the decomposition of the silicone rubber.