Fracture Toughness Enhancement of Mullite-Ceramics Reinforced with Metals

Abstract

With the idea to determine ways of tailoring mullite-ceramics (3Al2O3∙2SiO2) in order that one or more toughening mechanisms are activated in service, investigations about the production of mullite-based composites with different reinforcement metals (Co, Ni, Ti) have been carried out. The synthesis of composites materials has been made by means of pressure less sintering of an intensive mechanical mixture of powders. With the use by separate of those metals in the chemical formulations, significant improvements in ceramic toughness have been obtained. From the fracture toughness measurements and microstructural observations, it can be commented that the toughening mechanism in mullite/metal reinforced composites is due to crack bridging and crack deflection, owed to the presence of ductile particles as metals in the ceramic matrix. On the other hand, the presence of metals in the composites helps to densities mullite.