LABORATORY METHODOLOGIES FOR PROPELLANT CORROSION RESEARCH

Storable liquid propellants are stored for extended periods of time in metal tankage prior to usage in rocket engines. Knowing the chemical Interaction of the propellant and the tankage material is essential to evaluating the structural integrity of the tankage in service and det ermining if the propellant remains within specifications at the time o f use. Some of this information has been obtained through long duratio n storage studies for periods of over 20 years in some cases. It is de sirable to establish valid methods to obtain quantitative data to proj ect long-term corrosion rates in lieu of real-time storage experimenta tion. Experimental methods and techniques currently used in obtaining such corrosion data and their theoretical basis are described in this article. These include 1) electrochemical: de polarization and ac impe dance measurements; 2) weight loss; and 3) surface analytical: x-ray p hotoelectron spectroscopy, auger electron spectroscopy, and optical mi croscopy. This article presents a description of the fundamental metho ds used by two research organizations and a comparison of these method s and equipment. These techniques are valid for evaluation of corrosio n rates on various fuel and oxidizer propellants. The results of speci fic research with nitric acid based oxidizers with various aluminum al loys are presented in a companion article.