Gas Pressure Sintering of Arbitrary Porous Silicon Nitride Ceramics with High Mechanical Strength

Gas pressure sintering is applied to prepare arbitrary porous silicon nitride (Si(3)N(4)) ceramics using yttria (Y(2)O(3)) as the sintering additive and naphthalene powder as the pore-forming agent. The results obtained show that the porosity of the sintered porous Si(3)N(4) ceramics is 40%-54% when the Y(2)O(3) content is from 3 to 15 wt% and the sintering temperature is from 1700 degrees to 1850 degrees C. The bending strength is in the range of 60-226 MPa. The porosity of the porous Si(3)N(4) ceramics with Y(2)O(3) content of 9 wt%, sintered at 1800 degrees C, is increased to 51%-66% when the naphthalene powder content is 5-30 wt%. Finally, large and arbitrary porous Si(3)N(4) ceramics with a porosity of similar to 60% can be successfully fabricated by this method.