Microwave Assisted Self-propagating High-temperature Synthesis of Ti2AlC MAX phase
Anna Koniuszewska, Krzysztof Naplocha
Quarterly No. 2, 2016 pages 109-112
DOI:
keywords: MAX phases, SHS synthesis, microwave, porous structure
abstract A novel manufacturing method of Ti2AlC MAX phases with TiC carbides was elaborated. Compacted from elemental powders, the samples were heated and synthesized in a microwave field under atmospheric pressure. Microwave radiation selectively heats the reactant particles, though additional SiC support was required. Graphite can be classified as a good absorber whereas in Al, Ti metallic particle electric eddy currents are induced only on the surface. Microwaves heat material from the inside to the outside and usually concentrate on the interface between materials with a different dielectric loss factor. Therefore, it is possible to induce and conduct the reaction, on the microscale, at metal-ceramic or even metal-metal contact points. Energy was transferred from the magnetron through the waveguide and after a few seconds synthesis began and spread to the entire volume of the cylindrical sample. The initiated SHS synthesis first proceeded with the formation of Al-Ti intermetallic and TiC precipitates whose highly exothermic reactions resulted in a significant increase in temperature to ca. 1600°C. Next, these phases are almost completely transformed into plate-like Ti-Al-C MAX phases forming a porous structure of the samples. Such materials can be ideal for components working in extreme conditions (heat exchangers, catalyst substrates, filters) or for composite reinforcing.