The Effect of Nano-B۴C Additive on Microstructure and Mechanical Properties of Pressureless Sintering SiC Bodies

In this study, the mechanical properties, microstructure, and fracture behavior of SiC-NanoB۴C composites have been investigated with different weight percentages of secondary phase including ۰, ۰.۲۵, ۰.۵, ۰.۷۵, ۱, ۲, and ۳ wt.% nanoB۴C produced by pressureless sintering. At least ۱ wt.% of phenolic resin was added to all samples as a carbon source (both as a binder and as a carbon additive). Samples were then sintered for ۲h at ۲۱۵۰˚C under an argon atmosphere. The results showed that the composite containing SiC-۰.۵wt% nanoB۴C, sintered at ۲۱۵۰˚C, had the best mechanical properties. In this sample, the relative density was ۹۸.۳۲%, the micro-hardness was ۲۸.۶ GPa, Young's modulus was ۴۷۱.۸ GPa and the fracture toughness was ۳.۷ MPa.√m. Also, the transgranular fracture was observed in the related SEM images. Larger amounts of additives reduced the properties. In order to compare the results better, the temperature and duration of the sintering, the micron-scale size of the B۴C additive, the amount of phenolic resin, and the amount of initial sample press were considered as variables.

کلیدواژه ها:

Mechanical properties ، Nanocomposite ، Silicon carbide ، Nano boron carbide ، Fracture behavior