Enhanced densification of spark plasma sintered TiB₂ ceramics with low content AlN additive

In the present study, we incorporated AlN (5 wt%) with TiB₂ ceramic and consolidated the mixture by relatively low temperature sintering method, resulting in a near fully dense composite. Monolithic TiB₂ and TiB₂–AlN (5 wt%) were manufactured by spark plasma sintering (SPS) at 1900 °C for 7 min under 40 MPa. The prepared composites were precisely characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) analyses. In addition, possible chemical reactions during the sintering process were thermodynamically assessed using the HSC Chemistry software. The addition of AlN influenced the sinterability of titanium diboride, yielding a relative density of 99.7%. XRD results revealed the in-situ formation of h-BN during the sintering, whereas thermodynamic studies suggested the formation of both Al₂O₃ and h-BN. Furthermore, the microstructural investigation verified the synthesis of both Al₂O₃ and h-BN phases. Finally, the fractographical study revealed the effective role of AlN additive for refining the microstructure of TiB₂.