Strengthening of Alumina-Based Ceramics with Titanium Nanoparticles

Abstract

In this study ceramic materials with a matrix of Al 2 O 3 strengthened with different amounts of Ti nanoparticles (0.0 wt%, 0.5 wt%, 1.0 wt%, 2.0 wt% and 3.0 wt%) were generated. High energy milling was used to mix the materials in a planetary mill type, in which powder particles were obtained with sizes of ~300 nm. These powders were uniaxially compacted in cylindrical samples using 350 MPa pressure. These samples were sintered at 1500°C for 1, 2 and 3 h and at 1400°C, 1500°C and 1600°C during 2 h. Microstructure observations were made with optical microscopy and scanning electron microscopy. Dense composites were identified with a homogeneous distribution of fine particles. Concerning the measurement results of fracture toughness, which were estimated by the indentation fracture method, it was shown that the composites made by mean procedure present higher values than the average of the monolithic alumina, up to 200%. Photographic evidence of arrest of crack growth by titanium particles was obtained, demonstrating that the reinforcement mechanism of these materials is due to the deflection of cracks owing to metallic bridges formed by the titanium used as alumina strengthener.