Accession Number : AD0907191

Title :   Development of Large Diameter High Chamber Pressure Throat Insert Materials. Volume I.

Descriptive Note : Final rept. 15 Feb 70-1 Sep 72,

Corporate Author : ATLANTIC RESEARCH ALEXANDRIA VA

Personal Author(s) : Olcott,Eugene L.

Report Date : NOV 1972

Pagination or Media Count : 77

Abstract : The objectives of this program were the design, analysis, manufacture, non-destructive testing and sub-scale (seven inch) testing of PG coatings for use in large nozzles. Various problems were encountered with the scale-up of the deposition process, but after selective variation of such parameters as pyrolysis gas flow rates and concentration, injector position and geometry of the furnace and the exit ports, successful pyrolytic graphite coating depositions were achieved in sizes up to thirteen inch throat diameter nozzles. The characteristics of these coatings on the large nozzles were identical to those of smaller nozzles previously tested, insofar as could be determined. In the seven inch subscale tests performance was inferior to that previously achieved in the two inch nozzles. In all cases the post-firing conditions showed some damage, although in one case the damage was confined to a single axial crack and a small coating chip in the exit end crack termination. The other test nozzle components performed satisfactorily in all tests. The principal scale-up problem was identified as accomodating the radial growth of the throat insert caused by thermal strains while at the same time maintaining an acceptable stress state in the coated nozzle insert. It was concluded that excessive backside restraint was present in all of the tests. It was found that holographic interferometry was a useful NDT technique for detecting thin delaminations in the coating.

Descriptors :   (*NOZZLE INSERTS, *REFRACTORY COATINGS), (*PYROLYTIC GRAPHITE, NOZZLE INSERTS), (*ROCKET NOZZLES, COATINGS), MANUFACTURING, EROSION, GRAPHITE, SUBSTRATES, DEFECTS(MATERIALS), MECHANICAL PROPERTIES, TENSILE PROPERTIES, COMPRESSIVE PROPERTIES, NONDESTRUCTIVE TESTING, INTERFEROMETERS, MICROSTRUCTURE, CAPTIVE TESTS, ANNEALING, STRESSES, ELASTIC PROPERTIES, SOLID ROCKET PROPELLANTS, GELS, PHOTOGRAPHIC ANALYSIS, PYROLYSIS, STEREOSCOPIC DISPLAY SYSTEMS, LASERS

Subject Categories : Solid Propellant Rocket Engines

Distribution Statement : APPROVED FOR PUBLIC RELEASE