自增韧氮化硅陶瓷的制备与性能研究  

Study on Preparation and Properties of Self-toughened Silicon Nitride Ceramics

作　　者：豆高雅 Dou Gaoya(Yulin Hanting Chemical Technology&Development Co.Ltd,Shaanxi,Yulin,718100)

机构地区：[1]榆林市瀚霆化工技术开发有限公司

出　　处：《陶瓷》2019年第9期53-62,共10页Ceramics

摘　　要：氮化硅陶瓷具有优异的物理机械性能和化学性能,被广泛应用于高温、化工、冶金、航空航天等领域.在结构陶瓷中氮化硅陶瓷虽具有相对较高的断裂韧性,但为了进一步拓宽氮化硅陶瓷的运用领域和提高其使用可靠性,改善其断裂韧性一直是该材料研究的重要课题.笔者通过利用氮化硅陶瓷的自增韧技术,使用复合烧结助剂和在氮化硅基体中添加长柱状β-Si3 N4晶种,制备高断裂韧性的氮化硅陶瓷.采用X射线衍射、扫描电镜、阿基米德法、三点抗弯曲强度、单边切口梁法等测试方法对陶瓷的组成、显微结构、显气孔率以及抗弯强度和断裂韧性等进行了分析与表征.首先研究了无压烧结制备氮化硅陶瓷过程中,烧结助剂(Y2 O 3和Al2 O 3)对其烧结性能和力学性能的影响,当Y2 O 3含量为8wt%,Al2 O 3含量为4wt%时,氮化硅陶瓷的相对密度达95%以上,抗弯强度为674 MPa,断裂韧性为6.34 MPa·m1/2.再通过引入La2 O 3提高氮化硅晶粒的长径比,使氮化硅陶瓷的抗弯强度和断裂韧性达到686 MPa和7.42 MPa·m1/2.笔者通过无压烧结工艺,在1750℃制备了长柱状的β-Si3 N4晶种,晶种的平均长度为2.82μm,平均粒径为0.6μm,平均长径比为4.7,着重研究了晶种对氮化硅陶瓷烧结性能和力学性能的影响.氮化硅陶瓷中加入晶种后,其烧结性能和抗弯强度略有降低,但断裂韧性得到了很大的提高;且随着晶种添加量的增加,断裂韧性先升高再降低,掺杂量为2wt%时,断裂韧性达到最大(7.68 MPa·m1/2),提高了20%以上.Silicon nitride ceramics,which possess excellent physical mechanical properties and chemical properties,were widely used in high-temperature industrial,chemicals,metallurgy,aerospace application and other field.Silicon nitride ceramics have the relatively high fracture toughness in the structural ceramics,but in order to further broadening application fields and improving the using reliability of ceramics,the increasing of fracture toughness was always the important problems in the study of the material.This work prepared high fracture toughness Si3 N4 ceramics by addition of composite sintering additives and elongatedβ-Si3 N4 seeds,which was called self-reinforced of Silicon nitride ceramics.Phase composition,microstructures,open-porosity,fracture toughness and flexural strength were tested by using XRD,SEM,Archinmedes,SENB and three-point bending test.At first,the effect of sintering additives(Y2 O3 and Al2 O3)on the sintering properties and mechanical properties was investigated by pressureless sintering.The experimental results showed that silicon nitride ceramics can achieve good mechanical properties,the relative density of Si3 N4 ceramics was more than 95%,flexural strength of 674MPa and fracture toughness of 6.34 MPa·m1/2.When the sintering additives of Y2 O3 and Al2 O3 were 8 wt%and 4 wt%.Then the introducing of La2 O3 to increase the aspect ratio of Si3 N4 grains,make the flexural strength and fracture toughness of Si3 N4 ceramics to 686MPa and 7.42 MPa·m1/2.The elongatedβ-Si3 N4 seeds were prepared by pressureless sintering at 1 750℃,the average length,diameter and aspect ratio were 2.82μm,0.6μm,and 4.7,respectively.The influence of seeds on Si3 N4 ceramics sintering properties and mechanical properties were studied by this article.The results demonstrated that the fracture toughness of silicon nitride was improved significantly with the addition of the seeds,while the relative density and bending strength are decreased slightly.In addition,the fracture toughness ini-tially increased and then d

关 键 词：氮化硅陶瓷 断裂韧性 显气孔率 抗弯强度 烧结性能 晶粒长径比 

分 类 号：TQ174.75[化学工程—陶瓷工业]