摘要
以Sc2O3,Zr(NO3)4·3H2O和NH3·H2O为初始原料,加入少量PEG400作为分散剂,采用化学共沉淀法,经反复水洗、醇洗和干燥后,制备了钪锆陶瓷粉前驱体。运用差示扫描量热/热重(DSC/TG)技术研究了前驱体在空气中脱水分解反应的动力学过程。DSC/TG分析结果表明:390 K附近的吸热峰,源于前驱体表面物理吸附水和乙醇的脱附;560 K附近的放热峰,源于前驱体表面的有机官能团被氧化剧烈放热;650 K附近较明显的放热峰,源于前驱体中氢氧化物的脱水反应;690 K附近较明显的吸热峰与前驱体晶型转变有关。用Kissinger法和Doyle-Ozawa法计算了前驱体脱水分解反应的活化能(E)分别为144.053和110.008 k J·mol-1。用Kissinger法确定了反应级数(n)和频率因子(A)分别为1.2和2.74×1011s-1,确定了前驱体脱水分解阶段的动力学方程为dα/d T=2.74×1011e-127030.456/RT(1-α)1.2。根据动力学研究的结果,采用优化的焙烧工艺制备了钪锆陶瓷粉。扫描电镜(SEM)和X射线衍射(XRD)分析表明,合成的陶瓷粉体具有类球形形貌,衍射峰峰形尖锐,没有杂峰,具有良好的立方相结构。
With Sc2O3,Zr（ NO3）4·3H2O and NH3·H2O as starting materials,the precursor of scandia-doped zirconia ceramic powder was prepared by co-precipitation method using a little amount of PEG400 as surfactant,combined with repeatedly washing with deionized water and absolute ethanol. The thermal dehydration process and non-isothermal kinetics of the precursor of scandia-doped zirconia（ Sc SZ） ceramic powder were investigated by differential scanning calorimetry（ DSC） and thermo-gravimetric analysis（ TG） techniques in air atmosphere. As observed by DSC / TG,the endothermic peak around 390 K was attributed to the desorption of ethanol and water physicsorbed on the surface of the powder,the exothermic peak around 560 K on the DSC curve was caused by the oxidative removal of organic groups coordinated on the surface of the powder,the exothermal peak around 650 K could be attributed to the dehydration of hydroxide,and the endothermic peak around 690 K was connected with the crystal form transformation of the precursor. The activation energies（ E） of the dehydration reaction stage were calculated by Kissinger and Doyle-Ozawa methods as 144. 053 and 110. 008 k J·mol- 1,respectively. The reaction order（ n） and pre-exponential factor（ A） were also determined by Kissinger method as 1. 2 and2. 74 × 10- 11,respectively. The kinetics equation of the dehydration process was deduced as dα/d T = 2. 74 × 10^11e- 127030. 456 / RT（ 1-α）1. 2. Based on the results of dynamic study,the scandia-doped zirconia ceramic powder was prepared in optimized sintering condition. Scanning electron microscopy（ SEM） and X-ray diffraction（ XRD） results showed that the as-prepared materials were small microspheres and XRD peaks were sharp and corresponded well to the cubic structure.
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2015年第7期611-616,共6页
Chinese Journal of Rare Metals
基金
国家科技部高技术研究发展计划("863"计划)项目(2011AA03A409)资助
关键词
钪锆陶瓷粉
脱水分解
活化能
动力学
差示/热重
scandia-doped zirconia ceramic powder
dehydration decomposition
activation energy
kinetics
DSC/TG
