Influence of g-C3N4 on Phase Evolution and Microstructural Modifications in Spark Plasma Sintered TiB2-Based Ceramics

In this research, TiB₂-based ceramic was made by compacting the powder with g-C₃N₄ additive using spark plasma sintering (SPS) method. To manufacture the sample, first, a mixed suspension of g-C₃N₄ and TiB₂ powders with a mass ratio of 1–10 was prepared in 96% ethanol. Then, the particles of the secondary phase were properly distributed in the main matrix with an ultrasonic stirrer. The SPS step was performed at 1900°C for 7 min with an external load of 40 MPa. In the following, SEM images and XRD patterns were used to investigate the microstructural development and phase analysis of the manufactured composite sample. Also, for phase studies, HSC Chemistry software was employed to identify the possible reactions according to thermodynamics principles. The results showed that the use of g-C₃N₄ as an additive in the TiB₂-based composite resulted in a sample with lower relative density in such a way that the relative density decreased to 91.3% compared to the TiB₂ monolithic sample with a relative density of 96.7%. The g-C₃N₄ additive was fully consumed during the SPS and decomposed into its elements, causing the in situ synthesis of BN phase.