Study of melting of complex refractory ceramics by laser-pulse

There is a considerable lack of data on the melting properties of most refractory ceramics.They exhibit a complex melting behavior, in most cases, two-phase melting has to be considered involving a difficult analysis of the liquidus-solidus lines. For such binary systems, ordinary techniques are cumbersome and poorly accurate. Therefore, a melting technique based on laser heating (Nd-YAG laser pulse) was tested where a better control of the sample composition as well as a precise method for detection of the phase transition is ensured. This method was applied to non-stoichiometric uranium dioxide and to mixed uranium and zirconium oxides (Zr,U)O2 of various compositions, compounds which play a key role in cases of accidental melt down of a nuclear reactor core. (nevyjel)