Influence of the vol% SiC on properties of pressureless Al₂O₃/SiC nanocomposites

Abstract

Al 2 O 3 /SiC nanocomposites were prepared by pressureless sintering with micron-sized Al 2 O 3 powders whose average ranged 5 mm in d 50 and nano-sized SiC powders whose average ranged 80 nm in d 50 as raw materials. The combined powders were then ball-milled in iso-propanol alcohol and then, the slurry was freeze granulated. Compressed samples were prepared by cold isostatic pressing of the granules. Pressureless sintering was carried out in an argon atmosphere at 1750 C for 4 h. The physical and mechanical properties, including density, hardness and fracture toughness of specimens as well as microstructural investigations were analyzed. The results showed that by increasing vol% of SiC up to 5, hardness and fracture toughness were improved, whereas by increasing more than 5 vol% of SiC, hardness increased but fracture toughness decreased. The scanning electron microscope micrographs showed that, SiC nanoparticles inhibited the grain growth of Al 2 O 3 and reduced the matrix grain size accordingly.

Effect of in situ VSi2 and SiC phases on the sintering behavior and the mechanical properties of HfB2-based composites

“…Hence, increasing compressive stresses around SiC particles enhanced the fracture toughness of HfB 2 –SiC–VSi 2 composite. These results were supported by other researchers 45 – 49 .…”

Improvement of mechanical properties of HfB2-based composites by incorporating in situ SiC reinforcement through pressureless sintering

“…They demonstrated that the addition of SiC up to 20 vol% enhances the fracture toughness of the composite. In a similar study, Ghadami et al 51 investigated the reinforced composite by SiC. They discovered the fracture toughness value diminished due to using the reinforcement more than a specific proportion.…”