A Short Overview on Low-Density Ablators for Unmanned Vehicle

Abstract

With the development of small unmanned detector, unmanned reconnaissance aircraft, reusable unmanned testing machine to a higher speed, the thermal environment with high heat flux, high enthalpy and long aerodynamic heating time requires thermal protection system. Low density ablative materials with excellent ablative, thermal insulation and light structural weight have attracted much attention. This article summarizes the characteristics and development history of low-density ablation materials, and introduces the research progress and practical application status of low-density ablation materials reinforced by fibrotic porous matrix. The phenolic aerogels and silicon-doped phenolic aerogels are mainly introduced, which are representative lightweight ceramic ablation materials, including their design, performance optimization, ablative performance characterization and ablative mechanism evaluation. Compared with the traditional preparation method of supercritical drying, which has a long preparation cycle and high cost, an improved sol-gel polymerization method is developed with ambient pressure drying process. The as-synthesized novel phenolic aerogels are capable of efficient thermal insulation in the area of high-speed unmanned aerial vehicles.