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采用溶胶-凝胶法,结合常压烧结工艺制备了Ca_3Co_4O_9陶瓷。通过热重-差示扫描量热法(thermogravimetric-differential scanning calorimetry, TG-DSC)、X射线衍射(X-ray diffraction,XRD)和扫描电镜(scanning electron microscope,SEM)等测试手段探讨了Ca_3Co_4O_9陶瓷的形成过程,分析了不同工艺参数对Ca_3Co_4O_9陶瓷显微结构及性能的影响,研究了晶粒尺寸与热传输性能之间的关系。结果显示:Ca_3Co_4O_9为取向无规则层片状结构,当煅烧温度为750～900℃时,能得到纯相Ca_3Co_4O_9。Ca_3Co_4O_9陶瓷的热导率(κ)较低,且随着温度的升高而逐渐增大。晶粒尺寸的减小对其晶格热导率(κ_1)影响显著,当平均晶粒由92 nm减小到63 nm时,κ_1由1.529W/(m·K)减小到0 959W/(m·K),但对载流子热导率(κ_c)的影响很小。Ca_3Co_4O_9陶瓷的κ随晶粒尺寸的减小而降低,主要是由于κ_1随晶粒尺寸的减小而降低所致。
Ca_3Co_4O_9 ceramics were prepared by sol-gel method and atmospheric sintering. The properties of Ca_3Co_4O_9 ceramics were investigated by means of thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM) The influence of different process parameters on the microstructure and properties of Ca_3Co_4O_9 ceramics was analyzed. The relationship between the grain size and heat transfer properties was also studied. The results show that: Ca_3Co_4O_9 is oriented randomly lamellar structure, when the calcination temperature is 750 ~ 900 ℃, can be pure phase Ca_3Co_4O_9. The thermal conductivity (κ) of Ca_3Co_4O_9 ceramic is lower and increases with the increase of temperature. When the average grain size decreases from 92 nm to 63 nm, the decrease of the grain size decreases from 1.529 W / (m · K) to 0 959 W / ( m · K), but little effect on the carrier thermal conductivity (κ_c). Κ of Ca_3Co_4O_9 ceramics decreases with the decrease of grain size, which is mainly attributed to the decrease of κ_1 with the decrease of grain size.