Mesophase pitch modified silicone rubber coatings with fence-like ceramic layer structures and excellent ablation resistance performance

For ablation resistant silicone rubber composite materials, the strength of the ceramic layer is closely related to the ablation resistance of the composites. In this study, a series of mesophase pitch (MP) modified silicone rubber composites with superior ablation resistance performance were prepared. The ceramic layers of these composites have unique fence-like structures with good compressive strength. Characterization of ablation performance shown that the 20MP composite exhibited the best ablation resistance performance: a linear ablation rate of 0.072 mm/s and a mass ablation rate of 0.030 g/s. SEM and mercury intrusion measurements indicated that the ceramic layers of the composites formed porous and regular fence-like structures, which helped to resist flame ablation. The characterization of the compressive properties shows that the ceramic layers had excellent compressive strengths, and the compressive strength of the ceramic layer of the 20MP sample can reach 13.390 MPa. Observation by polarizing microscope shows that mesophase pitch left much ordered graphitic carbon in the ceramic layers, which helped to improve the strengths of the ceramic layers. XRD measurement confirmed that the ceramization reaction occurred and the ceramic substance SiC was produced during the ablation process. Mesophase pitch was proven to be a material that can improve the ablation performance of silicone rubber composites by increasing the ordered carbon content and strengths of the ceramic layers. These silicone rubber composites have the potential to be applied to ablation-resistant coatings on aircraft surfaces.