FEASIBILITY DEMONSTRATION OF PYROLYTIC GRAPHITE COATED NOZZLES
Quarterly progress rept. no. 3, 1 Aug-31 Oct 1964
ATLANTIC RESEARCH CORP ALEXANDRIA VA
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The objective of this program is to demonstrate the feasibility of pyrolytic graphite coatings for use in uncooled solid propellant rocket nozzles in a size range of use for practical propulsion units under very severe operating conditions. In prior work, the excellent serviceability of pyrolytic graphite coatings in 12-inch diameter nozzles was demonstrated with propellants having flame temperatures from 5500F to 6500F. In current work, nozzles of 1.1- inch and 2.3-inch diameter are to be tested with a 6550F propellant. This report describes the work of the third quarter of this program. Improvements were made in preparing crack-free sub-scale coated inserts. Flaw-free coatings as thick as 54 mils were prepared. Application of this improved art to full- scale inserts is underway. Stress analysis indicated the merit of alternate substrate materials and deposition work with these is underway. A successful 35-second sub-scale firing was made but during a 60-second firing discrete coating losses were observed. In the first full-scale motor firing excessive erosion was observed from a coating containing a known separation. This behavior was analogous to early sub-scale experience.
- Ceramics, Refractories and Glass