以闪速燃烧合成的Si3N4(w(Si3N4)≥95%,粒度≤0.044mm)、α-Al2O3微粉(w(Al2O3)≥99%,d50=1.2μm)及SiO2微粉(w(SiO2)≥92%,粒度≤1μm)为原料,按照m(Si3N4):m(Al2O3):m(SiO2)=4:4:2比例混合,液压成型为620mm×20mm试样在埋炭(不接触焦炭)条件下分别于1300、1400、1500、1600℃保温6h处理后进行XRD分析。结果表明:1300℃的新生物相主要为Si2N2O和方石英,SiO2微粉方石英化明显;1400℃的新生物相主要为Si2N2O、方石英和O’-SiAlON;1500℃的新生物相为Si2N2O、方石英、O’-SiAlON、X相及莫来石;与1500℃相比,1600℃的新生物相没有变化,但是Si,N,0、0’SiAlON、X相及莫来石的生成量增加明显,方石英生成量显著减少。
The specimens in φ20 mm×20 mm were prepared by mixing flash combustion synthesized of Si3N4 ( w( Si3 N4 ) ≥95%, grain size ≤〈 0. 044 mm), active α-Al2O3 ( w( Al2 O3 ) ≥99%, d50 = 1.2 μm ) and SiO2 fume (w(SiO2)≥92% ,grain size ≤ 1 μm) based on m(Si3N4) : m(Al2O3) : m(SiO2) =4:4:2,shaping,carbonembedded firing (not contacting with carbon) at 1 300,1400, 1500 and 1600℃ for 6 h, respectively. The XRD analysis results show that. (])The formed phases are Si2N2O and cristobalite at 1 300℃ and the crys- tallization of silica fume is obvious; (2)The formed phases are Si2N2O,cristobalite and O'-SiAlON at 1400℃; (3) The formed phases are Si2N2O, cristobalite, O' -SiAlON, X phase and mullite at 1 500 ℃; (4) The formed phases at 1600 ℃ are the same with that at 1 500℃, but the forming amounts of Si2N2O, O'-SiAlON,X phase and mullite increase obviously and that of cristobalite decreases obviously.