YANG J F,OHJI T,NIIHARA K.Influence of yttria-alumina content on sintering behavior and microstructure of silicon nitride ceramics[J].J Am Ceram Soc,2000,83(8):2094–2096. [2]DIAZ A,HAMPSHIRE S.Characterisation of porous silicon nitride materials[J].J Eur Ceram Soc,2004,24(2):413–419. [3]KAWAI C,YAMAKAWA A.Effect of porosity and microstructure on the strength of Si3N4:designed microstructure for high strength,high thermal shock resistance,and facile machining[J].J Am Ceram Soc,1997,80(10):2705–2708 [4]MIYAGAWA N,SHINOHARA N.Fabrication of porous alumina ceramics with unidirectionally arranged continuous pores using a magnetic field[J].J Ceram Soc Jpn,1999,107(7):673–677. [5]FUKASAWA T,DENG Z Y,ANDO M.Synthesis of porous silicon nitride with unidirectionally aligned channels using freezing-drying process[J].J Am Ceram Soc,2002,85(9):2151–2155. [6]YANG J F,ZHANG G J,OHJI T.Porosity and microstructure control porous ceramics by partial hot-pressing[J].J Mater Res,2001,16(7):1916–1918. [7]YANG J F,SHAN S Y,JANSSEN R,et al.Synthesis of fibrousβ-Si3N4structured porous ceramics using carbothermal nitridation of silica[J].Acta Mater,2005,53(10):2981–90 [8]COBLE R L,KINGERY W D.Effect of porosity on physical properties of sintered alumina[J].J Am Ceram Soc,1956,39:377–385.