Preparation Of Porous Silicon Nitride Based Ceramic Materials

The paper discussed that Silicon-nitride based porous ceramic was prepared by reaction-sintering and pressless-sintering with the powder of Si as raw material, Al2O3 and Y2O3 as sintering aids, carbon and carbamide as pore-forming agent.The results show that: At 1380℃, Silicon-nitride based porous ceramic was fabricated successfully by the complex technology. By studying several sintering aids, such as A12O3, Y2O3 , A12O3+Y2O3 , MgO, TiB2+MgO, Mg(NO3)2 . 6H2O and A1(NO3)3 . 9H2O, A12O3 and A12O3+Y2O3 as sintering aids are better, Y2O3 takes the second place. Although Si3N4 is obtained with Al, the CPS of Si3N4 is very low.Farther experiment was done for the system of A12O3 and A12O3+Y2O3. By comparison, 10% A1203 or 2 % Al2O3+8 %Y2O3 as sintering aids has obvious function for synthesizing Si3N4 .In the same condition of technology, silicon-nitride based porous ceramic, which is composed of P- Si3N4 and a -Si3N4 was obtained , C+10% A12O3 as additives. At the same time, the increasing amount of carbon is be propitious to a -to-B phase transformation. C+ (2% Al2O3+8% Y2O3) as additives have the same conclusion. The amount of impurities is increasing as the increasing amount of carbamide for carbon and carbamide as pore-forming agent.Silicon-nitride based porous ceramic was fabricated. Mean pore size is 30 um, ranging between 7.95um and 59.75um. The range of porosity is 16.2%~32.85%.Microstructure was observed by SEM and the composition of micro-area was analyzed by ED AX.In addition, development, preparation technology, applications of porous ceramic and silicon nitride were summarized. At one time, the latest development of silicon-nitride based porous ceramic was introduced.