压力和温度对等离子活化烧结Si3N4陶瓷致密化及相变的影响

以Mg2Si为烧结助剂,采用等离子活化烧结制备了Si3N4陶瓷,研究了烧结过程中压力、烧结温度对Si3N4陶瓷致密化以及相变过程的影响。结果表明:适当地提高烧结压力有助于致密化以及相转变,其原因在于外加压力有助于粉体颗粒的重新排列,以及液相在空隙的填充,明显提升相转变程度以及缩短致密化温度。而压力超过了50MPa之后由于致密化温度提前使得液相与粉体颗粒的接触面积减小,导致相转变过程受到了一定程度的阻碍。另外温度对于Si3N4陶瓷的致密化以及相转变也有着重要的影响,30MPa压力下至少需要1400℃以上温度才能使得Si3N4陶瓷烧结致密以及相转变发生。

Effects of Pressure and Temperature on Densification and Phase Transformation of Si3 N4 Ceramics by Plasma Activated Sintering

Si 3 N 4 ceramics were prepared by plasma-activated sintering with Mg 2 Si as sintering aid, the effect of pressure and sintering temperature on the densification and phase transformation of Si 3 N 4 ceramics were studied. The results show that proper increase of pressure contributes to densification and phase transition, because the applied pressure facilitates the rearrangement of particles, and the dispersion of liquid phase insides the ceramics, which can significantly improve the extent of phase transition and shorten the temperature of densification. However, after the pressure exceeds 50 MPa, the phase transition process is somewhat hindered due to the decrease in the contact area of the liquid phase and the powder particles, induced by the advancement of temperature of densification. In addition, the temperature also has an important influence on the densification and phase transition of Si 3 N 4 ceramics, it was required at least temperature of 1400 ℃ for the densification and phase transition of Si 3 N 4 ceramics at pressure of 30 MPa.