(中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083)
摘 要: 采用共沉淀法制備納米ZrO2-8%Y2O3(質(zhì)量分?jǐn)?shù))粉末，然后將其在大氣中于1 100~1 300 ℃范圍內(nèi)高溫煅燒處理2~32 h。利用XRD、SEM、TEM等方法研究納米ZrO2-8%Y2O3粉末高溫煅燒前后的相成分、形貌和晶粒粒徑變化，并分析納米ZrO2-8%Y2O3粉末的晶粒生長動力學(xué)及生長機(jī)制。結(jié)果表明：納米ZrO2-8%Y2O3經(jīng)高溫煅燒后，單斜相和四方相含量隨溫度的升高和時間的延長而減少，立方相含量隨溫度的升高和時間的延長而增加；隨溫度的升高和時間的延長晶粒粒徑逐漸增大；在1 250 ℃等溫煅燒時，其晶粒生長指數(shù)為6，晶粒生長速率常數(shù)為7.626×1011 nm3/min；等溫鍛燒溫度低于1 200 ℃時，晶粒生長活化能為 64.35 kJ/mol，晶粒生長表現(xiàn)為以表面擴(kuò)散為主的聚合生長；等溫鍛燒溫度高于1 200 ℃時，晶粒生長活化能為116.40 kJ/mol，晶粒生長表現(xiàn)為以晶格擴(kuò)散為主的聚合生長；另外，還可見晶粒旋轉(zhuǎn)驅(qū)動的聚合生長機(jī)制；低的晶粒生長激活能歸因于大量氧空位的引入和晶粒旋轉(zhuǎn)驅(qū)動的聚合生長機(jī)制。
關(guān)鍵字: 納米氧化鋯粉末；高溫煅燒；相轉(zhuǎn)變；晶粒生長；動力學(xué)
nanocrystalline 8% yttria stabilized zirconia powder
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The nanocrystalline ZrO2-8%Y2O3 (mass fraction) powder prepared by co-precipitation method was calcinated at high temperature from 1 100 ℃ to 1 300 ℃ for 2−32 h. The changes of the phase composition, morphology and particle size before and after the high temperature calcination were investigated by XRD, SEM and TEM，respectively. Both the grain growth kinetics and growth mechanism were analyzed. The results indicate that the contents of the monoclinic phase and tetragonal phase of ZrO2-8%Y2O3 powder decrease with increasing the temperature and time, the content of cubic phase increases with the increasing temperature and time. The grain size increases with increasing the temperature and time. At 1 250 ℃, the grain growth exponent is 6, and the kinetic rate constant is 7.626×1011 nm3/min. The grain growth is controlled by surface diffusion with lower activation energy (64.35 kJ) below 1 200 ℃, and controlled by lattice diffusion with higher activation energy (116.40 kJ) above 1 200 ℃. Grain-rotation-induced grain coalescence growth mechanism is also observed. Low growth activation energy is attributed to the introduction of large oxygen vacancies and grain-rotation-induced grain coalescence growth mechanism.
Key words: nanocrystalline zirconia powder; high temperature calcination; phase transition; grain growth; kinetics
