Fracture toughness of Si3N4 - based ceramics measured by Vickers indentation

Fracture toughness of Si3N4 -based ceramics, obtained by means of sinter-HIP and HIP, was measured by Vickers indentation method. Using values of KIC and Young Modulus, obtained from four points bending, fracture energy was calculated. Differences on toughness values were related with grain size and type of fracture of the different compositions. The microstructural analysis carried out by scanning electron microscopy confirmed that high values of fracture toughness correspond to large grain sizes and to surfaces with more intergranular fracture