摘要
以Na2CO3和α-Al2O3为原料,Na2CO3与α-Al2O3的物质的量比为1:6,采用固相合成法制备β″/β-Al2O3粉末。通过热力学计算原料粉末在不同温度下可能发生的化学反应的吉布斯自由能,并结合Na2CO3/α-Al2O3混合粉末的DTA曲线,研究可能发生的化学反应的温度条件。同时,用X射线衍射仪(XRD)对固相合成粉末的物相组成进行分析。结果表明,Na2CO3/α-Al2O3混合粉末在1 150℃左右开始发生反应生成β″/β-Al2O3;最适宜的反应温度为1 250℃,α-Al2O3全部转化为β/β″-Al2O3,并且β″-Al2O3含量最高;当温度升高到1 400℃时,β/β″-Al2O3发生分解,生成α-Al2O3和Na2O,并且随温度升高,更多的β/β″-Al2O3发生分解,而Na2O在高温下挥发会促进β/β″-Al2O3的分解。当煅烧温度超过1 500℃时,β″-Al2O3分解还生成微量的Na Al O2。
β″-Al2O3 powder was prepared by solid state method using Na2CO3 and α-Al2O3 as raw materials with a molar ratio of 1：6. The reaction temperature of different chemical reactions which might occur during calcination process was investigated by the calculation of Gibbs free energy and differential thermal analysis （DTA） curve of Na2CO3 and α-Al2O3 mixed powder. The phase composition of calcined powder was characterized by X-ray diffraction （XRD）. Results show that in the mixed powder, Na2CO3 begins to react with α-Al2O3 to form β″-Al2O3 at the temperature of 1 150 ℃. The optimum calcination temperature is 1 250 ℃, at which temperature all α-Al2O3 can transform into β″-Al2O3 and the content of β″-Al2O3 is the most. The β″-Al2O3 will decompose into α-Al2O3 and Na20, when calcining temperature increases to 1 400 ℃. The decomposition content of β″-Al2O3 increases with the increasing temperature and the evaporation of Na2O under high temperature accelerates the decomposition of β″-Al2O3. When the calcining temperature increases to 1 500 ℃, a small amount of NaAlO2 is produced by the decomposing of β″-Al2O3.
出处
《粉末冶金材料科学与工程》
EI
北大核心
2015年第3期338-343,共6页
Materials Science and Engineering of Powder Metallurgy
