摘要
以α-Si3N4为原始粉料,MgO-Y2O3-Re2O3为烧结助剂,采用热压烧结法制备氮化硅陶瓷。通过阿基米德排水法、XRD、SEM、三点弯曲法、压痕法和激光闪光法分别对氮化硅的致密度、相组成、显微结构、抗弯强度、断裂韧性和热导率进行检测。研究表明:添加MgO-Y2O3-Re2O3(Re=Er、Sm、Dy、La、Y、Yb)的样品中,Sm2O3、Y2O3、Yb2O3易促使Y2O3分别形成第二相Y2SiO3、Y2Si3O3N4和Y2SiO5。同时,添加MgO-Y2O3-Re2O3(Re=Sm、Dy、La、Yb)的Si3N4中,长柱状晶均匀地镶嵌在较小的基体晶粒中,起自增强增韧作用,其抗弯强度均在920 MPa以上,断裂韧性均在6.93 MPa·m^1/2以上。与传统二元烧结助剂MgO-Re2O3相比,MgO-Y2O3-Re2O3三元添加剂中Re^3+半径的改变,对Si3N4陶瓷显微结构、抗弯强度及断裂韧性未产生规律性的影响,但其热导率随添加剂Re^3+半径减小而增大。
Usingα-Si3N4 as raw powder and MgO-Y2O3-Re2O3 as sintering assistant,Si3N4 ceramics were prepared by hot-pressing sintering,and the density,phase composition,microstructure,thermal conductivity,bending strength and fracture toughness of Si3N4 were tested by archimedean drainage method,XRD,SEM,laser flash method,three-point bending method and indentation method.Studies show that in samples with MgO-Y2O3-Re2O3(Re=Er,Sm,Dy,La,Y,Yb)added,Sm2O3,Y2O3,Yb2O3 are easy to facilitate Y2O3 to form the second phase Y2SiO3,Y2Si3O3N4 and Y2SiO5,respectively.Meanwhile,in the Si3N4 with MgO-Y2O3-Re2O3(Re=Sm,Dy,La,Yb)added,the long columnar crystals are uniformly embedded in the smaller matrix grains,with self-strengthening and toughening.The bending strength is above 920 MPa,and the fracture toughness of indentation is above 6.93 MPa·m^1/2.Compared with traditional binary sintering assistant MgO-Re2O3,MgO-Y2O3-Re2O3 ternary additive has no regular influence on the microstructure,bending strength and fracture toughness of Si3N4 ceramics with the change of Re^3+ radius,but its thermal conductivity increases with the decrease of Re^3+ radius.
作者
鲁欣欣
刘伟
李林
李建斌
LU Xinxin;LIU Wei;LI Lin;LI Jianbin(Research Center for Advanced Machining Tools and High Technology Ceramics,Guangdong University of Technology,Guangzhou 510006,China)
出处
《粉末冶金材料科学与工程》
EI
北大核心
2019年第6期536-541,共6页
Materials Science and Engineering of Powder Metallurgy
基金
国家重点研发计划(2017YFB0310600)
