Ablation Resistance and Spray-Ability of Nano-Magnesium Silicate Reinforced Sprayable Silicone-Based Thermal Insulation Materials

In order to satisfy the requirement for lightweight, highly reliable sprayable silicone rubber insulation material (SASI) in next-generation spacecraft, and to achieve a synergistic balance among the sprayability, mechanical properties and ablation resistance of SASI, this paper describes the preparation of nanostructured magnesium silicate (n-MS) via a hydrothermal method and systematically investigates its effects on the sprayability, mechanical properties and ablation resistance of sprayable SASI. The findings suggest that when the n-MS loading is set at 15 parts, the linear ablation rate and mass ablation rate of the SASI under oxy-acetylene conditions are as low as 0.10 mm/s and 0.07 g/s, respectively, representing reductions of 41.8% and 67.1% compared to the unmodified samples. Building upon this enhancement in ablation resistance, the tensile strength was also increased by 3.70 MPa, representing a 19.3% increase. It is crucial to note that during the spraying process, the viscosity of the silicone rubber system remained within a narrow range of 540–550 mPa·s following the addition of this filler. This finding indicates that the introduction of n-MS had no significant adverse effect on the spraying process. In summary, n-MS has been demonstrated to enhance the mechanical strength and ablation resistance of silicone rubber materials while maintaining adequate spray coating performance. In comparison with conventional filled silicone rubbers, the sprayable silicone rubber insulating material developed in this study provides a new material basis for the future lightweight and intelligent development of aerospace engines.