Silicon Carbide Whiskers Interference on Silicon Nitride Based Composite

Silicon nitride based composite has been prepared, using a direct mixture process as alternative route. Silicon carbide whiskers were mixed directly to silicon nitride based powders containing yttrium and neodymium oxide as sintering aids. Uniaxial hot pressing was used to prepare sintered samples. Crystalline phases were identified using x-ray diffractometry. Intergranular phases were analyzed using Scanning Electron Microscopy. Some mechanical properties (microhardness and fracture toughness) were also evaluated. The obtained high values of fracture toughness were correlated to the activation of toughening mechanisms, such as crack bridging and crack deflection.