碳热还原-常压烧结法制备多孔氮化硅陶瓷

POROUS SILICON NITRIDE CERAMICS PREPARED BY CARBOTHERMAL REDUCTION–PRESSURELESS SINTERING METHOD

釆用SiO2和α-Si3N4在氮气中通过碳热还原–常压反应烧结法,原位反应制备了氮化硅多孔陶瓷。由于反应中存在大量的质量损失,烧结的制品为高气孔的材料。通过改变原料中α-Si3N4与SiO2和C粉的相对含量,可以形成具有细小针状结构的β-Si3N4晶粒,以此获得气孔率可控的高性能的多孔氮化硅材料。随着原料中α-Si3N4含量的增大,烧结后,样品的总质量损失逐渐减小,收缩率逐渐降低,气孔率逐渐减小,弯曲强度逐渐增大。当α-Si3N4的质量分数为50%时,碳热还原–常压反应烧结的样品中的β-Si3N4晶粒具有更高的长径比,样品气孔率为68.7%,具有优良的力学性能,弯曲强度达到37.7MPa。

Porous silicon nitride ceramics were prepared directly by carbothermal reduction-pressureless reaction sintering in nitrogen using SiO2 and α-Si3N4 as raw materials. The high porosity of the materials occurs because there is a great mass loss in the reaction. The material has finer and needle-like α-Si3N4 grains when the relative content of α-Si3N4, SiO2 and C is changed. So high-performance and porosity-controlled porous silicon nitride could be obtained. With an increase in the α-Si3N4 content, its mass loss, linear shrinkage, and porosity decrease, and its flexural strength increases accordingly. The sample with the addition of 50% （in mass） α-Si3N4 has a higher aspect ratio of α-Si3N4 grains, a porosity of 68.7% and better mechanical properties, its flexural strength reaching to 37.7 MPa.