Erosion and deposition of carbon-carbon nozzle inserts in low-thrust long-duration solid rocket motors

In order to study the erosion and deposition process of the carbon-carbon nozzle inserts in low-thrust, long-duration solid rocket applications, two motors using metallized and non-metallized propellants, respectively, were tested. The transient value of the throat diameter was obtained from the pressure and thrust measurements. It was indicated that for metallized propellant the throat experienced four stages as initial deposition, deposition melt, continuous erosion, alternately erosion and deposition, while no initial deposition and melt phenomena were observed in the non-metallized case. Some approaches to minimize throat variation were developed based upon the investigation of the effect of chamber pressure, propellant composition and nozzle configurations on the throat erosion and deposition.