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. (Δ r G). At 773 K most of the studied nitrides, carbides, and some oxides were found to be stable (Δ r G > 0). However, oxides of Fe-based alloys, such as Cr 2 O 3 and Fe 2 O 3 were found to be unstable (Δ r G < 0) for all lithium compositions.