Spark plasma sintering (SPS) synthesis and tribological behaviour of MAX phase composite of the family Tin+1SiCn (n = 2)

Abstract

In this work we report on the spark plasma sintering (SPS) synthesis of Maxthal 312 (nominally-Ti3SiC2 but containing ancillary TiCX) and Maxthal 312-TiC composite as well as their dry sliding room-temperature tribological behaviour. The sintering procedure was further investigated to elucidate the decomposition of Ti3SiC2 by replicating the carbon-rich SPS sintering environment using DSC-TG analysis on the Maxthal 312 powder carried out in a graphite crucible. In the SPSed bulk products, Ti3SiC2 and TiCX were the major phases in the sintered Maxthal 312 disc whilst Ti3SiC2 and (TiCX + TiC) were the major phases in the sintered Maxthal 312-TiC composite disc. In addition, some traces of the compulsory intermediate phase (TiSi2) that has not been fully consumed coexisted in relatively small amounts in both bulk samples. Reconciling the SPS synthesis and the DSC-TG analysis, it appears that the formation of TiCX is attributed mainly to the intrinsic decomposition occurring at temperature above 1350 °C or partly due to the graphite paper used to wrap the powder during the SPS synthesis. Rotary dry sliding tribological behaviour of the sintered discs was then subsequently investigated using Al2O3 as a counterface at room temperature. The incorporation of TiC into the Ti3SiC2 matrix as well as the in-situ TiCX formed in the matrix during synthesis appears to improve the tribological behaviour of Ti3SiC2 for the tested conditions.