Oxidation Behavior of Spark Plasma Sintered HfB۲-SiC-Graphite Composite at ۱۴۰۰ °C

The current study aims to fabricate the HfB۲-SiC-graphite composite through Spark Plasma Sintering (SPS) method at ۱۹۵۰ °C for ۱۰ min. The oxidation behavior of the prepared composites was investigated at ۱۴۰۰ °C and different times of ۴, ۸, ۱۲, and ۱۶ 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 ۹۹.۳۹ %, ۱۰.۱۶ GPa, ۴.۷۳ MPa.m۱/۲, and ۴۶۴.۱۲ 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 ۸ h. Followed by oxidation for more ۱۲ 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.

Keywords:

HfB۲-SiC-Graphite Composite , Spark plasma sintering (SPS) , Ultra-High Temperature Ceramic (UHTC) Oxidation Behavior , Kinetic