The adjustment of microstructure and properties of TiC/Ni[sbnd]Cr composites by Mo addition applied for intermediate-temperature solid oxide fuel cell interconnects

Abstract

The TiC/NiCr composites, potential candidates for intermediate-temperature solid oxide fuel cell (IT-SOFC) interconnects, were fabricated by pressureless infiltration process and the adjustment of their microstructure and properties by Mo addition was investigated in this work. The results show that the core-rim structure, concave surfaces and coalescence of the particles were observed in the microstructure, which was resulted from the “dissolution-reprecipitation” process and coherent strain energy. The addition of Mo significantly changes the microstructure by refining the particles size and increasing the contiguity. Meanwhile the properties of composites with similar metal volume fraction could be adjusted by altering the microstructure. The large particle size and high contiguity is beneficial to decline the thermal expansion and electrical resistivity; the Vickers hardness increases as the particle size decreases, while the small particle size and high contiguity is detrimental to the flexure strength. The optimized content of Mo was 11 wt% for TiC/NiCr composites.