Co-Optimizing Insulative and Mechanical Properties of Quartz Fabric Reinforced Phenolic Composites by a Compromising Porous Structure for Thermal Insulation
Zhen Qian, Hongxiang Cai, Peng Wang, Liang Li, Xiaoyi Zhou, Yu Cao, Yayun Zhang, Bo Niu, Donghui Long
Abstract
Introducing porosity into structures is recognized as a practical strategy to achieve lightweightness and insulation for ablatives, but reduced matrix density leads to the weakening of mechanical and anti-ablation performances. Herein, a trade-off design of the porous structure is developed for integrating high-strength, insulation, and anti-ablation abilities into mid-density nanoporous phenolic composites (NPC). Benefiting from a narrow nanopore size (20–62 nm) of the matrix, thermal conductivity of NPC can be effectively limited within 0.079–0.115 W/(m·K), while showing a mid-density of 0.89–1.04 g/cm 3 . Meanwhile, NPC shows a considerable axial tensile strength of 130.2–177.8 MPa and out-of-plane compressive strength of ∼300 MPa due to the compromising porosity (34–62%) and reinforcing of the 3D needle-punched quartz fiber preform. Besides, NPC exhibits excellent oxidation resistance in static radiation heating (1000 °C) and outstanding insulation and ablation resistance under an oxy-acetylene heat flux of 1.76 and 4.18 MW/m 2 with the linear ablation rates of ∼0.102 and ∼0.185 mm/s, respectively. The results will further promote the development and application of phenolic ablatives in extreme re-entry environments.