Mechanical behavior of cordierite and cordierite-mullite materials evaluated by indentation techniques

Commercially available cordierite and mullite powders were used to obtain c ordierite and composite materials with mullite content up to 65 wt.% by att rition milling, uniaxial pressing and sintering. Cordierite powders were th e coarse, medium and fine single granulometric fractions and the binary mix tures of them with 30, 50 and 70 wt.% of the smaller component. Mullite pow der employed in composites was the 7 h-attrition milled one. The Vickers ha rdness (H-V) and fracture toughness (K-1C) were measured by Vickers indenta tion techniques. The Knoop hardness (H-K) and Youngs modulus (E-K) were est imated by Knoop indentation method. Fracture surfaces of sintered materials were analyzed using a scanning electron microscope (SEM). The indentation load to determinate the fracture parameters was previously determined. The influence of the porosity, increasing mullite and glassy phase contents and grain size on the mechanical parameters were analyzed and a fracture mecha nism was proposed. (C) 2001 Elsevier Science Ltd. All rights reserved.