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° to 1850°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°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 ∼60% can be successfully fabricated by this method.