MgO助剂对高温高压合成Si_(3)N_(4)陶瓷的影响

Effect of MgO Additives on the Synthesis of Si_(3)N_(4)Ceramics at High Temperature and High Pressure

在高温高压合成过程中,适当的助剂含量可以促进液相生成,降低相变所需温度,减少晶格氧含量,提高材料硬度.本研究利用高温高压(HTHP)技术,在4.5 GPa和1500℃条件下烧结10 min,以α-Si_(3)N_(4)粉末为基础原料,添加少量β-Si_(3)N_(4)粉末作为晶种,调整MgO助剂的添加量,制备Si_(3)N_(4)陶瓷.使用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、热导率测试仪和维氏硬度仪对样品进行表征和分析,研究MgO助剂添加量对陶瓷合成的影响.结果表明,MgO助剂含量为5%时制备的Si_(3)N_(4)陶瓷结晶度较好,内部无明显缺陷,致密性较好,最大硬度可达22.27 GPa,热导率为24.598 W/m/K.

In the high-temperature and high-pressure synthesis process,an appropriate amount of additives can promote the formation of the liquid phase,lower the temperature required for the phase transition,reduce the content of lattice oxygen,and simultaneously increase the material hardness.This study utilized high-temperature and high-pressure(HTHP)technology,sintering the samples at 1500℃and 4.5 GPa for 10 minutes,usingα-Si_(3)N_(4)powder as the starting material and adding a small amount ofβ-Si_(3)N_(4)powder as the seed.The MgO additive was adjusted to control the amount added to prepare Si_(3)N_(4)ceramics.The samples were characterized and analyzed using X-ray diffraction(XRD),scanning electron microscopy(SEM),thermal conductivity tester,and Vickers hardness tester.The study investigated the influence of the MgO additive content on the synthesis of Si_(3)N_(4)ceramics.The results show that when the MgO additive content is 5%,the Si_(3)N_(4)ceramic has excellent crystallinity and no obvious defects within the material,and good density;the maximum hardness is 22.27 GPa,and at this time thermal conductivity is 24.598 W/m/K.