Oxygen production by electrolysis of molten lunar regolith

The goal of this study was threefold. First, the theoretical energy requirements of the process were to be defined. This includes studies of the relevant oxidation-reduction reactions in the melt, their kinetics and energies of reaction, and experimental determination of production efficiencies and melt resistivities as functions of melt composition and applied potential. Second, the product(s) of silicate electrolysis were to be characterized. This includes: (1) evaluating the phase relationships in the systems SiO2-TiO2-Al2O3-MgO-FeO-CaO and Fe-Si; (2) estimating the compositions of the metal products as a function of applied potential and feedstock composition based on phase equilibria in the Fe-Si system and free energy values for SiO2 and FeO reported in the literature; (3) definition of compositions of products in actual experiments; and (4) definition of the form the product takes (whether phases separate or remain fixed, whether crystals settle or float in the remaining melt, and how large crystals form). Third, materials for these highly corrosive high-temperature silicate melts were to be identified. This includes identifing materials that may be either inert or thermodynamically stable in these melts, and experimental testing of the materials to confirm that they do not deteriorate. The results are discussed within this framework.