Flexible Thermal Protection Systems: Materials Characterization and Performance in Hypersonic Atmospheric Entry
University of Vermont/NASA Ames Research Center, Langley Research Center, Human Exploration & Operations and Space Technology Mission Directorates
This research used high-temperature aero-thermal heating in a 30 kW inductively coupled plasma torch to replicate the effects of harsh oxidizing environments during hypersonic atmospheric entry on fracture behavior and microstructure of two-dimensional woven silicon-carbide fibers. Silicon-carbide woven cloths were exposed to surface temperatures over 1400째C with different high-enthalpy dissociated oxygen and nitrogen plasma flows, and were mechanically deformed at room temperature. This research demonstrates that oxidizing plasmas play a more damaging role on fracture strength of 2-D woven SiC fibers than conventional static heating at equivalent temperatures. Our experiments showed that exposure to high oxygen atom concentration in air and oxygen plasmas results in a more severe embrittlement over shorter time scales, corresponding to degradation rates up to 200 times higher than those reported for static heating in conventional furnaces where only molecular oxygen is present. The origin of the accelerated embrittlement in oxidizing plasmas was found to be associated with the formation of a viscous silica surface layer leading to the development of gas bubbles, inter-filament adhesion, and critical flaws. These findings pave the way for establishing the viability of woven SiC fibers as an outer fabric material for new flexible thermal protection systems in NASA space applications.
Dr. Anthony Calomino, PhD, NASA Technical Monitor, Langley Research Center www.nasa.gov/epscor/stimuli
Prof. Frederic Sansoz, Science PI, University of Vermont
Aerothermal testing of 2-D woven SiC fibers for flexible thermal protection systems in hypersonic inflatable aerodynamic decelerators (HIAD) currently in development at NASA. (a) Crosssectional and (b) top views of Hi-Nicalon SiC woven fibers. (c) Woven Hi-Nicalon SiC lead-ply coupon in SiC sleeve. (d) Probe insertion in the 30 kW inductively coupled plasma torch facility.
NASA EPSCoR Stimuli 2014-15
Published on Dec 14, 2015
NASA Office of Education’s Aerospace Research & Career Development (ARCD) is pleased to release NASA EPSCoR Stimuli, a collection of univers...