Optimization of Fracture Toughness and Hardness by Taguchi Method in ZrB2-SiCnp-ZrC-CNFs

In this research, the effect of adding silicon carbide nanoparticles, zirconium carbide, and carbon nanofibers at different sintering temperatures and times on fracture toughness and hardness of ZrB2 ceramics has been investigated. Due to the high number of required samples (four variables in three levels) to optimize the fracture toughness and hardness, the design of the experiment (DOE) by the Taguchi method was used. The hardness and fracture toughness of the composites fabricated by spark plasma sintering (SPS) were evaluated by macro-Vickers and crack length measurement methods respectively. The results showed that sample 8 with the chemical composition of ZrB2-25Vol%SiC-15ZrC-10CNF sintered at 1875°C for 7 minutes has the maximum amount of HV hardness (400±33) and fracture toughness (7.3±0.4) Mpa.m1/2. Also, analysis of variance (ANOVA) indicated that temperature and time are the most effective variables on fracture toughness (with contributions of 84% and 10.5% respectively) and hardness (with contributions of 74.3% and 15.9% respectively).