Graphene nanoplatelets induce crystallographic texturing during reactive spark plasma sintering of titanium diboride

Abstract

Diborides of Zr, Ti and Hf have potential applications as ultrahigh temperature ceramics, armor material, MEMS, substrates for optoelectronic applications and solar absorbers. Previous reports suggest that crystallographically textured diboride compacts have better mechanical and functional properties. Current methods of fabricating textured compacts are either cumbersome or energy and time intensive. We demonstrate a novel method for fabrication of bulk textured TiB2 by reactive spark plasma sintering (RSPS) of Ti-B mixtures having graphene nanoplatelets (GNP) as reinforcement. GNP acted as a template resulting in formation of large TiB2 grains with plate type morphology. X-ray diffraction and Electron backscattered diffraction analysis revealed presence of basal texture in TiB2 – GNP compacts. In comparison to GNP, carbon nanotube addition is shown to result in randomly oriented equiaxed grains. The improvement in indentation fracture toughness indicates GNP is better toughening additive compared to CNT.