TiB_(2)添加量对Si_(3)N_(4)-SiC耐火材料性能的影响  

Effects of TiB_(2)addition on performance of Si_(3)N_(4)-SiC refractories

作　　者：李铁军 邓军平[1] 廉晓庆 曹会彦[2] 王龙庆[2] 华小虎[1] 邓丽荣[1] Li Tiejun;Deng Junping;Lian Xiaoqing;Cao Huiyan;Wang Longqing;Hua Xiaohu;Deng Lirong(School of Materials Science and Engineering,Xi'an University of Science and Technology,Xi’an 710054,Shaanxi,China;不详)

机构地区：[1]西安科技大学材料科学与工程学院,陕西西安710054 [2]中钢集团洛阳耐火材料研究院有限公司先进耐火材料国家重点实验室,河南洛阳471039

出　　处：《耐火材料》2024年第6期486-490,共5页Refractories

基　　金：陕西省重点研发计划项目(2017GY-181);西安市先进制造业技术攻关项目(21XJZZ0040)。

摘　　要：以SiC颗粒和细粉、Si粉为原料,TiB_(2)细粉为添加剂,采用反应烧结法经1400℃保温2 h制备了Si_(3)N_(4)-SiC耐火材料,以期改善它的性能。通过MIP、XRD、SEM等研究了TiB_(2)细粉添加量(加入质量分数分别为0、0.2%、0.4%、0.6%和0.8%)对反应烧结Si_(3)N_(4)-SiC耐火材料致密性、抗折强度、物相组成和显微结构的影响,并分析了致密化机制。结果表明:1)添加适量TiB_(2)有助于提高试样体积密度和高温抗折强度(1200℃),增加≤1μm小孔比例;2)随着TiB_(2)添加量的增加,Si_(2)N_(2)O杂相含量减小,Si粉氮化率提高,Si_(3)N_(4)开始为晶须状,后演变为发育良好的长棒状,最后异常长大;3)致密化机制为:添加少量TiB_(2)可增加SiO气相分压,促进Si_(3)N_(4)晶须遵循气固机制生长;当TiB_(2)添加量为0.6%(w)时,Si_(3)N_(4)在适量高温液相作用下发育为长棒状,形成三维交叉网络结构,继续增加TiB_(2)添加量至0.8%(w),试样中液相再次增多,棒状Si_(3)N_(4)异常长大;4)当TiB_(2)添加量为0.6%(w)时,试样综合性能最佳,其体积密度为2.75 g·cm^(-3),显气孔率为11.6%,常温抗折强度为40.2 MPa,1200℃高温抗折强度为47.4 MPa。To improve the performance,reaction sintered Si_(3)N_4-SiC refractories were prepared by reaction sintering at 1400℃for 2 h using SiC(particles and fines)and Si powder as the raw materials,TiB_(2)fine powder as the additive.The effects of the TiB_(2)fine powder addition(0,0.2%,0.4%,0.6%,and 0.8%,by mass)on the bulk density,modulus of rupture,phase composition,and microstructure of the reaction sintered Si_(3)N_4-SiC refractories were studied using MIP,XRD,and SEM,and the densification mechanism was analyzed.The results show that:(1)adding an appropriate amount of TiB_(2)helps to improve the bulk density and hot modulus of rupture at 1200℃,increasing the proportion of small pores(≤1μm);(2)with the increasing TiB_(2)addition,the content of Si_(2)N_(2O)impurity phase decreases,the nitridation rate of silicon powder improves;Si_(3)N_(4)exists as a whisker structure at the beginning,then evolves into well-developed long rods,and finally grows abnormally;(3)the densification mechanism is as follows:a small amount of TiB_(2)can increase the partial pressure of SiO gasous phase and promote the growth of Si_(3)N_(4)whiskers,which follow the gas-solid growth mechanism;when increasing the TiB_(2)addition to 0.6%,Si_(3)N_(4)develops into long-rod shapes under moderate high-temperature liquid phase,forming a three-dimensional network structure;when continuing to increase the TiB_(2)addition to 0.8%,the liquid phase in the samples increases again,and the rod-shaped Si_(3)N_(4)grows abnormally;(4)when the TiB_(2)addition is 0.6%,the comprehensive performance of samples is the best,with the bulk density of 2.75 g·cm^(-3),apparent porosity of 11.6%,cold modulus of rupture of 40.2 MPa,and hot modulus of rupture at 1200℃of 47.4 MPa.

关 键 词：TiB_(2) Si_(3)N_(4)-SiC 致密化 气固生长机制 

分 类 号：TQ175.75[化学工程—硅酸盐工业]