| 摘要 |
PURPOSE:To obtain the title sintered form of high density and high mechanical strength with reduced variation in characteristics, by granulation of a mixture comprising Si3N4 powder, a sintering aid and a binder so as to result in a specific size distribution, followed by forming and calcination. CONSTITUTION:Firstly, 100pts.wt. of Si3N4 powder 0.3-1.5wt.% in carbon con tent and >=90% in alpha-conversion rate is incorporated with 0.3-30pts.wt. of a sintering aid comprising 0.1-10pts.wt. of yttria, 0.1-10pts.wt. of alumina and 0.1-10pts.wt. of AlN followed by wet mixing grinding so that the resultant particle size distribution is such as D10=0.4-0.45mum, D50=1.0-1.5mum and D90=2.5-4.0mum, to prepare mixed powder 50-100mum in mean particle size. Thence, this mixed powder is spiked with a binder (e.g., PVA) followed by granulation so as to be <=25wt.% of particles <31mum in size, >=70wt.% of particles 31-125mum in size and <=10wt.% of particles >=125mum in size. The resulting granulated powder is then formed into a form <=30mm in thickness, which is then calcined at 1,700-1,850 deg.C. |
