The development of a new sealant for molten carbonate fuel cells (MCFC) requires a study of the attack of molten carbonates on selected materials. Silica and Pyrex glasses have better corrosion resistance against molten carbonates than other glasses, but they have unsuitable thermal expansion coefficients. Comparisons have also been made between borosilicate glasses of suitable thermal expansion for sealants for MCFC and silica and Pyrex glasses. The corrosion kinetics in molten carbonates follows two limiting relations and involves two corrosion mechanisms. The weight loss varied linearly with time, indicating a dissolution of the glass network at short times. Longer times show corrosion, depending on the square root of time, typical of a diffusion mechanism and indicating formation of a protective layer on the surface of the glass.
