以不同含量的YF_3和MgO作为烧结助剂,对Si_3N_4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YF_3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YF_3和MgO添加量的增加而增加,最高可以达到959 Mpa;而硬度则随着YF3的增加从20 Gpa降低;添加2%YF_3(质量分数)氮化硅陶瓷的断裂韧性在(5.5～5.8)×10~5 Mpa·m~(1/2)之间,随MgO添加量变化不大.
Using YF_3 and MgO with different contents as sintering aid Si_3N_4 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 Si_3N_4 ceramic were studied. Experimental results show that a quaternary compound YSiON was formed when only YF_3 was added, while a quaternary compound MgYSiO was formed when both YF_3 and MgO were added. The strength of the sample increased with increasing of YF_3 and MgO content, whose max value could be up to 959 Mpa. However, the hardness decrease starting from 20 Gpa as the YF_3 content increased. The fracture toughness of Si_3N_4 ceramic with 2% YF_3(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
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