| 摘要 |
PURPOSE:To obtain silicon nitride powder producible sintered material having a large strength at high temperature useful for gas turbine, etc., by nitriding metallic silicon powder in nitrogen-containing atmosphere and in the presence of alkali (earth) metallic powder in gaseous state. CONSTITUTION:Metallic silicon is nitrided to obtain powder having following properties; oxygen content: <=0.6wt.%., gamma-phase content: >=80%, average granular diameter: 0.3-0.8mum, strength of the sintered material (used of MgO-Al2O3-Y2O3 three components-system sintering auxiliary) at 1200 deg.C: >=700MPa. Said powder is used as silicon nitride powder for producing high-temperature structural material. Said silicon nitride powder is produced by continuously, intermittently or temporarily supplying halogenated alkali metal or halogenated alkaline earth metal (especially fluoride of Ca, Mg or Li is preferable) to metallic silicon powder in an atmosphere containing nitrogen and/or ammonia at 1150-1450 deg.C. |
