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Experimental strategy to determine nitrogen catalytic behavior of high‐temperature woven ceramics
Author(s) -
Meyers Jason M.,
Owens Walten P.,
Fletcher Douglas G.
Publication year - 2020
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.17160
Subject(s) - materials science , silicon carbide , ceramic , catalysis , porosity , nitrogen , composite material , atmospheric temperature range , chemical engineering , nanotechnology , chemistry , organic chemistry , engineering , biochemistry , physics , meteorology
New vehicle deceleration strategies have led to the development of deployable thermal protection systems with woven fabric outer layers that can withstand the harsh aerothermal environment of planetary entry. In this work, we present an experimental strategy for testing fabric samples and a method to determine nitrogen catalytic efficiency, γ N , from two‐photon laser‐induced fluorescence measurements of recombining nitrogen atoms near the sample surface. Measurements were made on other silicon carbide materials to better understand the influence of the fabric structure and porosity on catalytic recombination. The three test materials studied were a monolithic α‐SiC, a CVD β‐SiC, and a single‐ply, Hi‐Nicalon β‐SiC fabric layup. Extracted catalytic efficiencies for atomic nitrogen recombination for monolithic α‐SiC, CVD β‐SiC, and single‐ply β‐SiC fabric are (6.18 ± 1.55) × 10 −4 (at 1460 K), (3.59 ± 0.90) × 10 −3 (at 1500 K), and (8.34 ± 2.19) × 10 −4 (at 1675 K), respectively. This would categorize these materials as low‐catalytic materials for nitrogen atom recombination in this temperature range.