烧结温度对无压液相烧结TiN陶瓷组织与性能的影响

Effect of Sintering Temperature on Microstructure and Properties of TiN Ceramics by Pressureless Liquid Phase Sintering

以微米级TiN粉体为原料,纳米级Y2O3和Al2O3粉体为液相烧结助剂,采用无压液相烧结工艺制备TiN陶瓷,研究了烧结温度(1700~1850℃)对TiN陶瓷显微组织、力学性能和电学性能的影响。结果表明:不同烧结温度下陶瓷均由TiN、YAG(Y3Al5O12)和YAM(Y4Al2O9)三相组成;当烧结温度低于1800℃时,TiN相分布均匀,YAG和YAM相较少,当烧结温度为1800℃时,TiN晶粒长大,YAG和YAM相增多。随着烧结温度的升高,TiN陶瓷的相对密度、维氏硬度、抗弯强度和断裂韧度均先增大后减小,开口气孔率和电阻率均先减小后增大。当烧结温度低于1800℃时,陶瓷的断裂方式以沿晶断裂为主,当烧结温度不低于1800℃时以穿晶断裂为主。当烧结温度为1800℃时,TiN陶瓷的综合性能最佳,其相对密度、维氏硬度、抗弯强度和断裂韧度均最大,分别为98.3%,13 GPa,420 MPa,6.1 MPa·m^(1/2),开口气孔率和电阻率均最小,分别为0.12%和3.04×10^(-7)Ω·m。

TiN ceramics were prepared by pressureless liquid phase sintering with micron TiN powder as raw material and nano Y2O3 and Al2O3 powders as liquid phase sintering additives.The effect of sintering temperatures(1700‒1850℃)on the microstructure,mechanical properties and electrical properties of TiN ceramics was studied.The results show that the ceramics consisted of TiN,YAG(Y3Al5O12)and YAM(Y4Al2O9)phases at different sintering temperatures.When the sintering temperature was lower than 1800℃,TiN phase was distributed evenly,and the content of YAG and YAM phases was low.When the sintering temperature was 1800℃,TiN grains grew up,and the content of YAG and YAM phases increased.The relative density,Vickers hardness,flexural strength and fracture toughness of TiN ceramics all increased first and then decreased with the increase of sintering temperature,while open porosity and resistivity both decreased first and then increased.The fracture mode of the ceramics was mainly intergranular fracture when the sintering temperature was lower than 1800℃,and was mainly transgranular fracture when the sintering temperature was not lower than 1800℃.The TiN ceramics sintered at 1800℃had the best comprehensive properties with the highest relative density,Vickers hardness,flexural strength and fracture toughness,which were 98.3%,13 GPa,420 MPa,6.1 MPa·m^(1/2),respectively,and the lowest open porosity and resistivity,which were 0.12%and 3.04×10^(-7)Ω·m,respectively.