In situ construction of fiber‐supported micro‐porous char structure to enhance anti‐ablative performance of silicone rubber composites

Abstract

Ablation‐resistant polymeric composites play a crucial role in the thermal protection system for the entire aerospace industry. Constructing a stable char layer especially with low thermal conductivity is essential to enhance the ablation resistant properties of polymer‐based ablatives. In this article, basic magnesium carbonate (MgCO3) and carbon fibers (CFs) were introduced to silicone rubber with an aim of building fiber‐supported micro‐porous char structure in situ, thereby improving ablation resistance properties. Thermogravimetric analyses revealed that the addition of MgCO3 significantly increased the char residue of the composites. Oxyacetylene torch tests indicated that the addition of MgCO3/CFs greatly improved the thermal insulation of the composites, and the linear ablation rates of the composites were reduced by 30.76% compared to the virgin silicone rubber. Shore A hardness and thermal conductivity tests revealed that composites with 10 phr MgCO3 exhibited a char structure with proper strength and low thermal conductivity. SiC, Mg2SiO4, and MgSiO3 were produced in the MgCO3/CFs‐modified composites, as characterized by X‐ray diffraction. Combined with macro lens and scanning electron misroscopy, it was proven that a fiber‐supported micro‐porous and thermally insulated char structure was conducive to the improvement of the ablation properties, which can be applied to aerospace systems for thermal shielding applications.

State-of-the-Art on Advancements in Carbon–Phenolic and Carbon–Elastomeric Ablatives

“…The charred structure of composites containing 10 parts per hundred parts of resin (phr) of MgCO 3 demonstrated both low thermal conductivity and satisfactory strength. Compared to the unaltered base material, the incorporation of MgCO 3 along with carbon fibers resulted in a decrease in the rate of linear ablation of the composites by 30.76% [ 74 ].…”

Local strain quantification of a porous carbon fiber network material

“…Low-density porous materials are used in a wide variety of applications due to their vast range of mechanical and functional properties not accessible through fully dense materials. Catalysis [ 1 ], energy storage [ 2 ], medicine [ 3 ], electronics [ 4 ], and aerospace [ 5 ] are just a few of the industries in which these materials are being used. Nanoporous metals and metal foams [ 6 ], polymer foams [ 7 ], and porous fiber networks [ 8 ] are some common types of low-density porous materials, with each exhibiting dissimilar mechanical behaviors under load.…”

Catalytic Graphitized Silicone Rubber Coatings with Highly Graphitized Ceramic Layer and Superior Ablation Resistance

“…Some composites containing inorganic zirconium compounds could form a thermal insulating layer composed of ZrC and ZrO 2 on the ablated surface, and acted as an effective thermal barrier, which had a good thermal protection effect on the inside of the composites. [12,13] In addition, there are several methods to tune the microstructure of the ceramic layer and increase the internal porosity, such as introducing microfoam systems, [14] various hollow microsphere fillers, [15] and fibrous materials to stack 3D network structures. [16] These porous structures could effectively improve the thermal insulation and ablation resistance of composites.…”