Preparation of uitrafine α-Al2O3 powders by catalytic sintering of ammonium aluminum carbonate hydroxide at low temperature

The precursor of ammonium aluminum carbonate hydroxide was synthesized by using aluminum sulfate （Al2 （SO4）3 ） and ammonium carbonate（（NH4 ）2CO3 ）. The effects of α-Al2 O3 seeds and mixture composed of α- Al2O3 and ammonium nitrate, as well as multiplex catalysts （AT） on phase transformation of alumina in sintering process were investigated respectively. The results show that the α-Al2 O3 seeds and the mixture of α-Al2 O3 and ammonium nitrate can lower the phase transformation temperature of α-Al2O3 to different extents while the particles obtained agglomerate heavily. AT has great potential synergistic effects on the phase transformation of alumina and reduces the phase transformation temperature of α-Al2O3 and the trends of necking-formation between particles. Therefore the dispersion of powder particles is improved significantly.     

Industrial preparation and performance testing of property-modified prebaked carbon anodes for aluminum electrolysis

1　ＩＮＴＲＯＤＵＣＴＩＯＮＩｔｉｓｗｅｌｌｋｎｏｗｎｔｈａｔａｌｕｍｉｎｕｍｅｌｅｃｔｒｏｌｙｓｉｓｉｓａ“ｌａｒｇｅｆａｍｉｌｙ”ｏｆｅｌｅｃｔｒｏｅｎｅｒｇｙｃｏｎｓｕｍｐｔｉｏｎ .Ｉｎｔｈｅｍｅａｎｔｉｍｅ ,ｃａｒｂｏｎａｎｏｄｅｓａｒｅｕｓｅｄｕｐｃｏｎｔｉｎｕｏｕｓｌｙｉｎｔｈｅｐｒｏｃｅｓｓｏｆｅｌｅｃｔｒｏｌｙｓｉｓ ,ｓｏｔｈｅａｌｕｍｉｎｕｍｅｌｅｃｔｒｏｌｙｓｉｓｉｓａｌ ｓｏｃａｌｌｅｄ“ｌａｒｇｅｆａｍｉｌｙ”ｏｆｃａｒｂｏｎｃｏｎｓｕｍｐｔｉｏｎ .Ｆｏｒａｌｏｎｇｔｉｍｅ…     

罐式炉内石油焦排料行为的实验及仿真研究

罐式炉内石油焦下降运动行为对石油焦煅烧质量起着至关重要的作用。基于计算流体力学方法,建立了罐式炉排料过程的石油焦颗粒运动黏性流数学模型,并通过等比例缩小(1/15)的罐式炉冷态实验验证了模型的可靠性;利用该模型研究了罐式炉内石油焦下降运动行为。结果表明:随着排料运动的进行,示踪料层由直线型转变为"U"字型,石油焦在料罐区域基本符合活塞平推流运动特征,在冷却水套区域呈现漏斗流的特征;黏性流模型模拟结果与冷态物理实验结果比较吻合,表明黏性流模型可有效描述罐式煅烧炉内石油焦下降运动过程。     

尿素均匀沉淀法制备超细α-Al2O3粉体

以Al2（SO4）3和CO（NH2）2为原料,通过均匀沉淀法制备出前驱物Al（OH）3,并煅烧得到超细α-Al2O3粉体。研究CO（NH2）2和Al2（SO4）3的摩尔比、Al2（SO4）3起始摩尔浓度、反应温度、反应时间等对前驱物制备的影响。利用X射线衍射仪、扫描电镜、热重/差示扫描法（DTA/TGA）等多种现代分析检测技术对粉体的性能进行了表征。结果表明：在CO（NH2）2和Al2（SO4）3的摩尔比为10：1、Al2（SO4）3起始浓度为0.05mol/L、反应温度为90℃、反应时间为60min的条件下,能得到分散性能良好、粒径为2μm左右且粒度分布均匀的球形超细α-Al2O3粉体。     

Pilot study of mechanism of property-modified anode in aluminum electrolysis

1　INTRODUCTIONAluminummetallurgyadoptsthemethodofhightemperaturemeltsaltelectrolysisdevelopedonehun dredyearsago .Intheprocessofresearchanddevel opmentinthisfield ,physicalchemistry ,electro chemistry ,materialscience ,roboticizedtechnologyandsoonwerecombinedwithaluminummetallurgytechniques,makingthebasicprincipleoftheHall Heroultprocessbeingmoredeeplyrealizedbypeople .Furthermore ,thistechnologywasdevelopedcon stantlyandbecamemoreandmoreperfectinordertofurthersaveenergy ,reducerawmateri…     

碳酸铝铵热解法制备超细Al2O3

以Al2(SO4)3与(NH4)2CO3为原料,采用液相沉淀法,制备出前驱物碳酸铝铵(AACH),并烧结得到Al2O3粉末。通过分析前驱物的热重曲线,确定了前驱物的高温分解过程;并结合对前驱物在不同烧结温度下所得产物XRD图谱的分析,确定了前驱物的高温相变过程为:AACH→AlOOH→Al2O3(无定型)→γ-Al2O3→θ-Al2O3→α-Al2O3。同时,干燥方式对超细Al2O3分散性的影响在本文中也进行了研究。     

杂质对天然石墨电化学嵌/脱锂性能的影响

利用恒电流充放电、循环伏安等测试方法,研究了Fe、Si、Al的氧化物杂质对天然石墨嵌/脱锂性能的影响。实验结果显示,如SiO2之类的"惰性"杂质只影响材料的比容量,而诸如Fe2O3之类的"活性"杂质除了会降低锂离子电池的比容量外,还会消耗正极材料中的锂,造成电池的循环寿命缩短;但有的"活性"杂质能改善电池的大电流充放电性能。     

Effects of drying method on preparation of nanometer α-Al2O3

Ammonium aluminum carbonate hydroxide （AACH） precursor was synthesized by the precipitation reaction of aluminum sulfate and ammonium carbonate. Then the precursor was dealt with five drying methods including ordinary drying, alcohol exchange, vacuum freeze-drying, glycol distillation, n-butanol azeotropic distillation respectively and calcined at 1 200℃ for 2 h to get α-Al2O3. The effects of drying methods on preparation of nanometer α-Al2O3 were discussed, and the optimal drying method was confirmed. The structural properties of powders were characterized by XRD, SEM and BET measurements. The results show that vacuum freeze-drying, glycol distillation and n-butanol azeotropic distillation can prevent the powders from aggregating, and among them the n-butanol azeotropic distillation is the best method. The nanometer α-Al2O3 powder with non-aggregation can be manufactured using n-butanol azeotropic distillation and the average particle size is about 40 nm.     

片状超细α-Al2O3的制备研究

利用高能球磨对液相沉淀法合成的前驱物碱式碳酸铝铵（AACH）进行处理，研究了高能球磨对AACH晶型转变的影响，以及球磨条件对片状超细α-Al2O3粉末物理化学性能的影响。运用XRD、激光粒度分析仪、SEM等多种现代分析检测技术对粉体的性能进行了表征。结果表明：高能球磨能显著降低AACH完全转变为α-Al2O3的温度，在以无水乙醇为球磨介质。球磨转速为300r／min，球料比为20：1，球磨时间为4h的条件下，能得到无团聚、粒径为2μm左右，片层厚度为0．3μm左右的片状超细α-Al2O3粉末。