| 摘要 |
PURPOSE:To obtain ceramics of high toughness with a microstructure having a high aspect ratio, by adding beta-Si3N4 whiskers to silicon nitride sintered ordinary pressure. CONSTITUTION:The objective highly tough ceramics, obtained by mixing Si3N4 with Y2O3 and spinel in a ball mill, adding and mixing beta-Si3N4 whiskers dispersed with ultrasonic waves in the above-mentioned mixture, then isostatically pressing the resultant mixture under a prescribed forming pressure and sintering the pressed compact in an atmosphere at 1750 deg.C under 1atm of N2 for 3hr. Since alpha-Si3N4 which is starting substance for calcined silicon nitride is transformed into the beta-Si3N4 in a sintering process by the afore-mentioned method, the beta-Si3N4 is grown from the beta-Si3N4 whiskers which are added as nuclei. As a result, ceramics having a high fracture toughness and microstructure at a high aspect ratio are obtained. |
