| 摘要 |
PURPOSE:To improve fracture toughness and mechanical strength by sintering Y2O3 and a powdery mixture of a specified amorphous mullite and a specified crystalline mullite. CONSTITUTION:With 0.25-1.5wt.% Y2O3, 5-25wt.% amorphous mullite having <=1.0mum average particle size and (71/29)-(75/25) weight ratio of Al2O3/SiO2 and a crystalline mullite having <=1.0mum average particle size and (73/27)-(77/23) weight ratio of Al2O3/SiO2 are blended and forming of the resultant mixture is carried out. The formed material is then sintered at 1600-1800 deg.C for >=2hrs to obtain the objective sintered mullite having a structure where prismatic crystals of >=3 average aspect ratio are dispersed in a spherical particle phase, 0.55-1.25 volume ratio of (prismatic crystal)/(spherical particle) and >=3.0g/cm<3> bulk density and satisfying a relation of (A)/(A+B)>=0.90, provided that A and B are the sum of peak areas at 2theta=26.3 deg. (d=3.390Angstrom ) and 2theta=25.9 (d=3.428Angstrom ) in powder X-ray diffractiometry and a peak area at 2theta=42.6 deg. (d=2.118Angstrom ) respectively. |
