YF_3助烧剂氮化硅的烧结及力学性能

Sintering and Mechanical Property of Si_3N_4 with YF_3 Sintering Aid

以不同含量的YF3和MgO作为烧结助剂,对Si3N4进行热压烧结,研究了烧结助剂含量对氮化硅陶瓷的相对密度、烧结反应、稀土元素分布以及硬度、强度和断裂韧性等力学性能的影响。实验结果表明,仅添加YF3的样品生成了YSiON四元化合物,而同时添加MgO的样品生成MgYSiO四元化合物;样品的抗弯强度随YF3和MgO添加量的增加而增加,最高可以达到959MPa;而硬度则随着YF3的增加从20GPa降低;添加2%YF3(质量分数)氮化硅陶瓷的断裂韧性在(5.5～5.8)×105MPa.m1/2之间,随MgO添加量变化不大。

Using YF3 and MgO with different contents as sintering aid Si3N4 ceramic was hot-pressed. The influences of the aid contents on the relative density, the sintering reaction, rare-earth element distribution, hardness, and mechanical properties including strength and fracture toughness of the Si3N4 ceramic were studied. Experimental results show that a quaternary compound YSiON was formed when only YF3 was added, while a quaternary compound MgYSiO was formed when both YF3 and MgO were added. The strength of the sample increased with increasing of YF3 and MgO content, whose max value could be up to 959 MPa. However, the hardness decrease starting from 20 GPa as the YF3 content increased. The fracture toughness of Si3N4 ceramic with 2% YF3（mass fraction） was in the range of 5.54-5.8 × 10^5 MPa·m^1/2, which did not change obviously with the MgO content