原位反应生成TiB_2对B_4C/TiB_2复合陶瓷力学性能和结构的影响  

Effect of in-situ formed TiB_2 on mechanical properties and microstructure of B_4C/TiB_2 ceramic composites

作　　者：刘长霞[1] 孙军龙[1] 

机构地区：[1]鲁东大学先进制造与自动化技术重点实验室,山东烟台264025

出　　处：《材料热处理学报》2010年第7期34-39,共6页Transactions of Materials and Heat Treatment

基　　金：鲁东大学人才引进基金(LY20074303;LY20074302)

摘　　要：研究了原位反应生成TiB2对B4C/TiB2复合陶瓷维氏硬度、断裂韧度、抗弯强度和微观结构的影响。结果表明,适量TiB2的生成可以抑制B4 C/TiB2复合陶瓷晶粒的长大,可使材料获得均匀致密的显微组织结构;而且原位反应的发生促使B4 C/TiB2复合陶瓷断裂机制由穿晶断裂为主转变为穿晶与沿晶结合的断裂机制。B4 C和TiB2晶粒尺寸都随着原位生成TiB2含量的增加而降低。B4C/TiB2复合陶瓷的抗弯强度随晶粒增大而降低,其断裂韧度随晶粒尺寸的变化关系较为复杂,这种变化关系主要与断裂韧度对裂纹扩展路径长度的依赖性有关,本文利用裂纹扩展阻力(R)曲线的斜率解释了这种变化。The effect of TiB2 in-situ formed on mechanical properties and microstructure of B4C /TiB2 ceramic composites was researched.The grain growth of B4 C /TiB2 ceramic composites with homogeneous microstructure and high densification rate is suppressed due to in-situ formation of TiB2 during sintering process.The fracture mechanism for B4 C /TiB2 ceramic composites changes from transgranular fracture to the combination of transgranular and intergranular owing to the in-situ reaction.The grain size of B4 C and TiB2 decreases with increasing the content of TiB2 in-situ formed.The bending strength of B4 C /TiB2 ceramic composites decreases with the increasing of grain size,while the relation between fracture toughness and grain size is complex.This behavior is related to the dependence of fracture toughness on the length of crack extension route,particularly to the slope of R-curve.

关 键 词：B4C TIB2 原位反应 微观结构 

分 类 号：TQ174.1[化学工程—陶瓷工业]