Mechanical and microstructural evolution of solid graphite rocket nozzle throats in extreme temperature and pressure conditions

Kaygusuz, Burçin
Nigar, Barış
Ünlüsoy, Levent
Çöker, Demirkan
Özerinç, Sezer
Durability of the rocket nozzle and the throat component is one of the key aspects for the reliable operation of a rocket during its trajectory. Graphite is commonly used as a throat material due to its high temperature resistance, ablative characteristics and low cost. However, graphite can fracture due to the combined effects of thermal loading and pressure during rocket firing, which is catastrophic for the operation of the rocket. Therefore, there is a need to understand all aspects of graphite failure, which will enable the more reliable design of the throat. In this work, we investigated the changes to the microstructural and mechanical properties of graphite upon its testing in an actual motor in static firing configuration. The results indicate that for the operation of the graphite throat in the actual combustion environment up to 3 seconds, the throat microstructure does not change considerably. On the other hand, nanoindentation measurements indicate considerable hardening upon firing, which suggests an embrittlement undesirable for the reliable operation of the throat. The results emphasize the importance of longer exposure times for the characterization of fracture and related effects.


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Citation Formats
B. Kaygusuz, B. Nigar, L. Ünlüsoy, D. Çöker, and S. Özerinç, “Mechanical and microstructural evolution of solid graphite rocket nozzle throats in extreme temperature and pressure conditions,” Istanbul, Turkey, 2018, p. 490, Accessed: 00, 2021. [Online]. Available: