Oxidation Behavior of Spark Plasma Sintered HfB2-SiC-Graphite Composite at 1400 °C

The current study aims to fabricate the HfB2-SiC-graphite composite through Spark Plasma Sintering (SPS) method at 1950 °C for 10 min. The oxidation behavior of the prepared composites was investigated at 1400 °C and different times of 4, 8, 12, and 16 h. In addition, the weight changes and thickness of the generated oxide layer were measured. The relative density, hardness, toughness, and strength of the composite made through the SPS method were calculated as 99.39 %, 10.16 GPa, 4.73 MPa.m1/2, and 464.12 MPa, respectively. The oxidation kinetic results of the composite exhibited linear-parabolic behavior. The chemical reaction during the oxidation process controlled the oxidation rate after 8 h. Followed by oxidation for more 12 h, the thickness of the oxide scale slowly increased, thus following a parabolic trend as a result of a decrease in the oxygen diffusion when HfOxCy and SiOxCy phases were formed. Therefore, it was concluded that the oxygen diffusion rate could control the oxidation process.