Synthesis and thermal stability of high-purity Cr2AlC MAX-phase for accident tolerant fuel cladding application

Cr 2 AlC MAX-phase ceramic is a promising candidate material for developing oxidation resistant coated Zirconium-based accident tolerant fuel cladding for water-cooled nuclear power reactors. In this study, high-purity Cr 2 AlC MAX-phase powder was synthesized from elemental Cr, Al, and C powders via pressure-less synthesis route with minimal pre-sintering treatments. Process parameters—such as synthesis temperature, holding time, and input materials composition—were optimized to obtain phase-pure Cr 2 AlC MAX-phase. The product exhibited ∼65 % theoretical density allowing easy pulverization into powder without utilizing any energy intensive milling. The productivity can be further enhanced by adding 2 wt% polyvinyl butyral as a binder, which greatly improves the strength of the green pellets. The yield per batch can also be improved by quartz encapsulation which eliminates the surface evaporation loss of Al during synthesis. The reaction pathway governing Cr 2 AlC MAX-phase formation was also elucidated through high-temperature differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. The thermal stability of Cr 2 AlC MAX-phase, evaluated up to 1530 °C temperature under flowing argon environment, showed that Cr 2 AlC is stable up to 1480 °C, beyond that decomposes into Cr-carbides and Cr-Al based intermetallic.