Compatibility of hydrocarbon fuels with booster engine combustion chamber liners

Abstract

This paper presents the results of material compatability experiments using Mil-Spec RP-1, /z-dodecane, propane, and methane fuels in contact with OFHC, NASA-Z, and ZrCu coppers. The objectives of the current research are 1) to define the corrosive interaction process that occurs between hydrocarbon fuels and copper combustion chamber liner materials, and 2) to develop and demonstrate protective measures against this corrosive process. Two distinct test methods were employed. Static tests, in which copper coupons were exposed to fuel for long durations at constant temperature and pressure, were used to provide compatability data in precisely controlled environments. Dynamic tests, using the Aerojet Carbothermal Test Facility, were used to expose copper specimens to fuel under realistic booster engine service conditions. Tests were conducted using 1) very pure grades of each fuel and 2) fuels to which a contaminant was added to define the role played by fuel impurities. The findings from metallurgical and chemical analyses of the copper specimens and chemical analysis of the hydrocarbon fuels are provided. Conclusions are reached as to corrosion mechanisms and effects, methods for the elimination of these mechanisms, selection of copper alloy combustion chamber liner and materials, and hydrocarbon fuel specifications as related to advanced booster engine systems.