MgO-Lu2O3-Re2O3三元添加剂对氮化硅陶瓷性能的影响

摘要

通过热压烧结方式制备Si3N4陶瓷,采用阿基米德排水法、SEM和四点弯曲法分别对样品的致密度、第二相、微观结构和力学性能进行测试.在添加MgO-Lu2O3-Re2O3三元添加剂的S3N4陶瓷中,(Sm2O3,Er2O3)易促使Lu2O3在晶界处形成第二相Lu4Si2N2O7.在添加MgO-Lu2O3-Re2O3(La2O3,Gd2O3,Er2O3)的Si3N4陶瓷中,长柱状晶均匀分布在较小的基体晶粒中,并弱化晶界,样品的四点抗弯强度均在900MPa以上,断裂韧性高于9 MPa·m1/2.而在添加MgO-Lu2O3-Sm2O3的Si3N4样品中,由于局部出现晶粒异常长大现象,强度和韧性提高较小.另外,与传统二元MgO-Re2O3添加剂相比,MgO-Lu2O3-Re2O3三元添加剂随着Re3+离子半径的改变,对Si3N4陶瓷微观结构、力学性能不会产生规律性的影响.%Si3N4 ceramics with high mechanical properties were prepared by an introduction of MgO-Lu2O3-Re2O3 (Re= La,Sm,Gd,Er) multiple additives. The effect of ternary additives on relative density,second phase,micro-structure and mechanical properties were studied. Results showed that the addition of MgO-Lu2O3-Re2O3 (Re= Sm,Er) into Si3N4 ceramics led to the formation of Lu4Si2N2O7. And the addition of MgO-Lu2O3-Re2O3 (Re= La,Gd,Er) into Si3N4 ceramics led to distinctly bimodal structure distributions,weak grain boundary,and then resulted in high flexure strength (above 900 Mpa) and high fracture toughness (above 9 MPa·m1/2). However,the introduction of MgO-Lu2O3-Sm2O3 led to some exaggerated grains growth,which resulted in low flexure strength and low fracture toughness.