Thermodynamic stability of oxide, nitride, and carbide coating materials in liquid Sn–25Li

Tin–lithium (Sn–Li) has been identified as a candidate liquid metal coolant for fusion power reactors. Sn–Li coolants offer a number of advantages compared with pure lithium. The vapor pressure of Sn–25Li (0.25 Li mol fraction) is a factor of ∼1000 lower than that of pure Li, which allows an increase in coolant temperatures by as much as 450 K. Experimental data of the stability of ceramic materials in Sn–Li is scarce. The thermodynamic stability of various oxides, carbides, and nitrides in Sn–Li is estimated as a function of lithium composition and temperature at saturated solute concentrations by evaluating the Gibbs free energy of reaction, (ΔrG). At 773 K most of the studied nitrides, carbides, and some oxides were found to be stable (ΔrG>0). However, oxides of Fe-based alloys, such as Cr2O3 and Fe2O3 were found to be unstable (ΔrG<0) for all lithium compositions.