Extensive research in the introduction of so-called “green fuels” in the space industry, generates the need to find appropriate and compatible structural materials. High-concentration hydrogen peroxide is an example of a green fuel whose decomposition leads to the production of steam and oxygen only. For this reason, it is an excellent candidate to replace the currently used toxic and carcinogenic hydrazine. Before this can happen, however, there is a need to verify the effects of hydrogen peroxide on the materials from which propellant storage tanks, refueling tanks and transfer systems are constructed, as well as other components in contact with the propellant. Contamination of hydrogen peroxide, due to leaching of metals into the solution, causes accelerated decomposition. The consequence of this is an increase in pressure and temperature, which can lead to a loss of system integrity. In addition, there is also a risk of poisoning the catalyst in the rocket engine or a decrease in its integrity. Since the durability of hydrogen peroxide depends on its purity, prior passivation of the tanks is necessary to prevent excessive corrosion of metals leading to liquid contamination.
A research project performed for the European Space Agency (ESA) is devoted to the optimization of passivation parameters for selected aluminum alloys. The aim of the project is to produce protective coatings by chemical methods and to check their durability in contact with hydrogen peroxide. The subject of research are mainly lightweight aluminum and lithium alloys with potential use in space industry. The material samples will be subjected to immersion and corrosion tests as well as electron microscopic (SEM) imaging of the surface. In addition, the influence of the passivated material on hydrogen peroxide will be examined, its stability will be determined and its metal content will be determined by Inductively Coupled Plasma Atomic Emission Spectrometry.