Densification improvement of spark plasma sintered TiB2-based composites with micron-, submicron- and nano-sized SiC particulates

Taguchi design of experiments methodology was used to determine the most influential spark plasma sintering (SPS) parameters on densification of TiB₂–SiC ceramic composites. In this case, four processing factors (SPS temperature, soaking time, applied external pressure and SiC particle size) at three levels were examined in order to acquire the optimum conditions. The statistical analysis identified the sintering temperature as the most effective factor influencing the relative density of TiB₂–SiC ceramics. A relative density of 99.5% was achieved at the optimal SPS conditions; i.e. temperature of 1800?°C, soaking time of 15?min and pressure of 30?MPa by adding 200-nm SiC particulates to the TiB₂ matrix. The experimental measurements and predicted values for the relative density of composite fabricated at the optimum SPS conditions and reinforced with the proper SiC particle size were almost similar. The mechanisms of sintering and densification of spark plasma sintered TiB₂–SiC composites were discussed in details.     

Investigating the effect of SPS‎ parameters on densification ‎and fracture toughness of ZrB2-SiC nanocomposite‎

In this study, the effect of sintering parameters on densification and fracture toughness of spark plasma sintering ZrB₂-SiC nanocomposites was evaluated. For this purpose, ZrB₂-??30?vol% SiC nanocomposites in the conditions of ?1600?°C-4?min, 1700?°C-4?min, 1800?°C-4?min, 1800?°C-8?min, 1800?°C-12?min? were sintered.? Scanning Electron Microscopy (SEM) was used in order to investigate the ?microstructural variations. The bulk density was measured accoring to ASTM C 373–88. Single edge notch beam (SENB) method was used to ?determine the fracture toughness of samples. Microstructural observations showed that ?an increase in sintering temperature led to slight ?increase in SiC grains size but no sensitive variation in ZrB₂. However, increasing the sintering time resulted to increase both ZrB₂ and SiC grain size. Also, it was found, temperature and time ascent always increases the relative density. In addition, it was concluded that optimal temperature and time to reach the highest fracture toughness are 1800?°C and 8?min, respectively. Investigation of SEM images of the Vickers indent and their path propagation showed that the deviation and branching of crack are the most important toughening ?mechanisms in ZrB₂-SiC nanocomposites.?