Properties and Processing of Porous Si₃N₄ Ceramics

Abstract

Porous silicon nitride (Si3N4) ceramics green were prepared by sol-gel and freeze drying processing. Al2O3and MgO were selected as sintering additives. Porous Si3N4ceramics were sintered at 1200~1300 °C. The porosity of porous Si3N4ceramics reached 60~80%, the pore size of porous Si3N4ceramics dried by freeze drying is less than 5μm. Two kinds of pores were formed, including open pores with pore size of 1~5μm and closed pores pore size with the nanometer level. The compression strength of porous Si3N4ceramics was 15~25MPa. Thermal conductivity of porous Si3N4ceramics was 0.08-0.1 W/m·K.

The preparation of highly-porosity materials on base of silicon nitride

“…При увеличении пористости материала от 40 до 60 % наблюдается снижение теплопроводности от 7-8 до 2 Вт/(м•К) [1]. Получен материал Si 3 N 4 -SiO 2 пористостью 60-80 %, имеющий теплопроводность 0,08-0,10 Вт/(м•К) [22]. Авторы статьи [23] методом замораживания суспензии изготовили пористый нитрид кремния, золь-гель методом импрегнировали в него диоксид кремния и в результате получили материал теплопроводностью при комнатной температуре 0,043 Вт/(м•К).…”