Title : Refractory Chamber Materials for N2O4/Amine Propellants.
Descriptive Note : Technical rept. Oct 70-Feb 73,
Corporate Author : MARQUARDT CORP VAN NUYS CALIF
Personal Author(s) : Campbell,John G.
Report Date : MAY 1973
Pagination or Media Count : 83
Abstract : Oxidation resistant materials suitable for passively cooled thrust chambers for N2O4 Amine propellants were evaluated by nozzle test
firings at 400 psia to 600 psia. Thermal stress analysis was performed to establish designs capable of performing long duration, multiple restart duty
cycles. A nozzle insert made of edge oriented washers of zirconium pyrocarbide and hafnium pyrocarbide experienced high erosion rates comparable to
pyrolytic graphite washers. A pyrolytic graphite coated Carbitex nozzle experienced low erosion rates, about 1 mil/sec. The best erosion resistance
was demonstrated by a zirconium diboride insert made of Material VIII (18,10) from Man Labs, Inc. This insert, in the form of two segments, was
designed to resist thermal shock by free thermal expansion and by heat flux reduction through a preoxidized coating. This nozzle concept allows the
use of materials formerly prohibited from rocket nozzle applications because of thermal stress sensitivity.
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