Applying the Taguchi to Optimization the densification, and flexural strength of ZrB2–SiC–ZrC-CNFs

The purpose of this research is to optimize the densification, microstructure and flexural strength of ZrB2-25 vol% SiC composites reinforced by carbon nano fibers (CNFs) and zirconium carbide (ZrC). Spark Plasma Sintering (SPS) was applied for composites consolidation. Taguchi orthogonal array L9 as the design of statistical experiments (DOE) was evaluated to optimize the additives, as well as SPS parameters (temperature and time). Three levels were defined for each factor. The relative density (R.D%) and flexural strength of the samples were calculated based on Archimedes' law and the three-point bending test. Moreover, analysis of variance (ANOVA) was utilized to determine the importance of effective parameters and to optimize the SPS variables and compounds (the amount of CNFs and ZrC). The microscopic structure of surfaces was examined through field emission scanning electron microscopy equipped with energy dispersive spectroscopy (FE-SEM, EDS). The results showed that the best output of relative density and flexural strength was equal to 99.8% and 610 MPa, respectively, with an average ZrB2 grain size of 9.6 μm in a composite containing 15 vol% CNFs and 10 vol% ZrC and SPSed at 1875 °C for 7 min.