Charring ablators, or charring ablative materials, are reinforced composite materials that undergo decomposition at elevated temperatures, causing organic resins to pyrolyze. Key characteristics of charring ablators: Pyrolysis process: Endothermic, absorbing a significant amount of energy. Formation of char: A layer of porous char forms on the surface, which has high porosity and permeability. Thermal conductivity: Char layers have low thermal conductivity but high emissivity, allowing them to maintain a high surface temperature and reradiate a significant portion of incident heat. Common examples: SLA-561 V (Super Light Weight Ablator); PICA (Phenolic Impregnated Carbon Ablator). Charring ablators are used in thermal protection systems for vehicles undergoing atmospheric re-entry or planetary entry, such as rocket nozzle linings and heatshields.