Seamless Joining of TaC‐SiC Composites Without Fillers by Spark Plasma Sintering

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The use of ultra‐high temperature ceramics necessitates an efficient joining technique to address the challenges related to the manufacturing of intricately formed components. This study describes a novel approach for efficient joining of pre‐sintered TaC‐SiC ceramic composites without filler material by spark plasma sintering. The effect of SiC addition (0, 35, 65 vol%) and joining temperature (1450, 1550, 1650°C) on the microstructural evolution and strength of the joint interface was investigated. A well‐bonded joint interface was observed with no apparent cracking and porosity at the joint interface. Joining mechanisms are primarily solid‐state diffusion, with grain‐boundary diffusion as the primary driver. A joint shear strength of >50% of composite flexural strength is achieved, revealing the durability of joints. Further, isothermal oxidation of joints at 800°C shows the highest mass gain of 12% for the monolithic TaC joint due to the formation of an oxide layer of tantalum, whereas composites with SiC addition show mass gain of <1% due to the formation protective passive layer of SiO 2 . Overall, the present study demonstrates the efficacy of spark plasma sintering for joining TaC‐SiC composites without fillers, highlighting the beneficial effect of SiC addition in obtaining robust oxidation‐resistant ceramic joints suitable for thermal barrier applications.