| 摘要 |
<p>A heat-resistant, high strength refractory composite produced by pressure sintering comprises by wt., 80-98.5 (pref. 86-94)% silicon nitride, 1-15 (pref. 3-7)% yttrium oxide and 0.5-10 (pref. 3-7)% thorium oxide, with total oxide is not >20% and with a density of >=90% theoretical. It is esp. useful in structural applications having a high mechanical strength at room temp. and elevated temp. It is resistant to thermal shock and oxidation and can be fabricated into complex shapes making it suitable for turbine rotors, stators and nozzles, for electrical insulators, forging dies, kiln furniture, crucibles, thermocouple envelopes etc.. The deviation from linearity during creep of the refractory is 26 (esp. 15)%. Typically, a compsn. of 84-87% Si3N4, 12-13% Y2O3 and 1.0-3% ThO2 has a density of >=98%, a room temp. strength of >=100,000 psi and a strength at 1375 degrees C of >=70,000 psi.</p> |
