Study on the In-situ Synthesis of Aluminum Titanate Sintered by Waste Aluminum Slag

Aluminum titanate was in-situ synthesized by using industrial waste-residue in the aluminum factory and TiO2 as the main raw materials and the influence of different reaction temperatures on the purity and microstructures of synthesized products were mainly discussed. The obtained Al2TiO5 was characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and relevant analytical software. The results show that elevating the sintering temperature can increase the content of aluminum titanate; and at 1420 ℃, it reaches the highest in the synthesized ceramic. When the sintering temperature continues to increase, the produced aluminum titanate will decompose resulting in the drop of its content. Therefore, the optimum sintering temperature of in-situ synthesis of aluminum titanate is determined as 1420 ℃, at which the grains of aluminum titanate grow completely, the purity of aluminum titanate is 89.3wt%., the highest density is 2.75 g/cm^3, and the porosity is 9%.     

Synthesis and Characterization of High-purity Aluminum Titanate with Water Quenching Method

High-purity aluminum titanate was synthesized via a water quenching method with waste-residue in the aluminum factory and industrial TiO2 as the main raw materials, which belongs to the comprehensive utilization of solid wastes. Compared with the conventional method, it can reduce synthesis temperature, effectively inhibit decomposition and raise the content of AT; the addition of tiny silicon powder can improve the sintering and optimize the properties of AT. The crystalline phase structure and microstructure of each sample were characterized with XRD and SEM methods; the content of each crystalline phase in each sample was confirmed with Rietveld Quantification method; the properties of each sample were also tested. The experimental results showed that No. 4 is the optimum specimen, with the corresponding mass ratio of Al2O3/TiO2 to be 1.27 and the content of AT of 97.2 wt%. The addition of optimum tiny silicon powder is confirmed to be 8wt%; its corresponding bulk density is 2.63 g/cm^3, bending strength is 46.34 MPa, and the retention of one thermal vibration bending strength is 71.5%.     

亚微米级四方相钛酸钡低温固相法制备及晶型控制

以八水合氢氧化钡和α-钛酸为原料,在相对低的焙烧温度下,制备出近似球形、亚微米级的钛酸钡。通过XRD、SEM、Raman和FTIR等手段对钛酸钡样品进行表征,样品具有高结晶度,颗粒均一性良好。晶型转变的初步探究表明,立方相为主的钛酸钡可以在400℃发生晶相转变,成为以四方相为主的钛酸钡。     

NaA,MAP和MAX高铝沸石的结构定向及其转晶

本文根据不同沸石的结构特点及其在晶化动力学上的差异,由化学组成相近的硅铝凝胶混合物(投料Si/Al比约为1)定向合成出具有不同骨架结构的高铝沸石—NaA,MAP和MAX。考察了沸石晶化过程中晶化导向剂、晶种以及金属阳离子在合成高铝沸石的结构导向作用以及上述三种高铝沸石间的转晶规律。同时本文首次发现了MAP沸石的“室温固相转晶”现象。     

Preparation of Barium Titanate Nanopowder through Thermal Decomposition of Peroxide Precursor and Its Formation Mechanism

H₂TiO₃ was dissolved in the mixture of hydrogen formed peroxide and ammonia under the pH range of 8–10 with a transparent yellow solution formed. When an equivalent mole of Ba²⁺ solution was added into the yellow solution, the precipitate produced was the peroxide precursor of barium titanate. The cubic nanopowder of barium titanate was obtained when the precipitate was washed, stoved, and then calcined at 600°C for 1 h. The peroxide precursor of barium titanate and barium titanate nanopowder prepared were characterized to be BaTi(H₂O₂)₂O₃ by TGA‐DTA, XRD, TEM, SEM, and XREDS. The peroxide precursor of barium titanate was determined to be BaTi(H₂O₂)₂O₃. The particle size of the barium titanate nanopowder, the calcined product of BaTi(H₂O₂)₂O₃, was in the range of 20–40 nm. A formation mechanism of the barium titanate nanopowder through thermal decomposition of its peroxide precursor was proposed and then validated.     

硫酸铝钾热分解反应动力学模型

近年来,在热分析动力学研究领域内,已有许多动力学模式及相应数据处理方法来描述固相反应的最可能机理,如：aRCHAR微分法[1]Coats-Redfe积分法[2]相结合的方法和等温过程与非等过程相结合的方法[3]等。而最近Dollimore等人[4]提出了利用 TA曲线的特征来确定动力学模型的方法,从而避免了对 f(a)和 g(a)逐一尝试的麻烦。本文就是用该法来研究硫酸铝钾的热分解动力学。硫酸铝钾热分解过程虽然已有人研究[5],但其动力学则未见文献报道。1 实验部分 实验工作在美国PE公司TGA７热分析仪上完成,反应气氛为氮气,流速为40mL·min-1 ,…     

T-型氢键液晶复合物的制备与液晶行为

以不具有液晶行为的2,6-二[N,N′-二-(4-烷基苯甲酰基)]氨基吡啶(A系列)和4-正烷氧基苯甲酸(D系列)作为氢键液晶复合物的单体,组装成T-型氢键液晶系列复合物(AmDn)。用红外光谱对其结构进行了表征,用DSC及偏光显微方法对其液晶行为进行了研究。结果表明:所合成的21种复合物分子间存在氢键且都具有向列相。通过调整2,6-二[N,N′-二-(4-烷基苯甲酰基)]氨基吡啶分子上柔性烷基的长度和极性,可以有效地调节它与4-烷氧基苯甲酸形成的氢键复合物的液晶相变温度以及液晶态的稳定性;增加2,6-二[N,N′-二-(4-烷基苯甲酰基)]氨基吡啶分子上柔性烷基的长度,其复合物AmDn的液晶相温度范围趋于变窄,清亮点逐渐下降,其液晶态稳定性也逐渐下降;以2,6-二[N,N′-二-(4-烷基苯甲酰基)]氨基吡啶分子替代2,6-二[N,N′-二-(4-烷氧基苯甲酰基)]氨基吡啶分子,可以降低分子的极性,使其单体的熔点及其氢键复合物AmDn的相变温度下降。     

茶多酚铝盐热分解法制备氧化铝纳米微粉

以茶多酚为沉淀剂,在溶液中与AlCl3充分反应,生成茶多酚铝盐前驱体,沉淀的最佳pH值为5．6,后者在空气中1030℃左右热处理90—150min制得质量分数为99．51％的AlCl3。样品的TEM、XRD和DTA分析结果表明,所得氧化铝样品为α-AlCl3,粒径约50nm。     

Effects of Calcining Temperature and Holding Time on the Synthesis of Aluminum Titanate

We aim in this research at synthesizing high-purity aluminium titanate with sludge from the aluminium profile factory by shock cooling method, and mainly discuss the effect of calcining reaction temperature and holding time on crystalline, microstructure and content of aluminum titanate materials to determine the preferred calcining temperature and holding time. XRD and SEM methods were utilized to characterize the crystalline and microstructure of each specimen, Rietveld Quantification software was used for the determination of different crystalline contents of specimens, and Philips plus software was applied to determine the cell parameters of aluminium titanate in different specimens. According to the experimental results, preferred calcining temperature is determined as 1400℃ and preferred holding time is 2 h, at which the grains of aluminum titanate grow completely and the purity of aluminum titanate is 97.2wt%.     

Influence of TiO_2 Mineralizer on the Crystalline Structure of Cordierite Synthesized from Aluminum Slag

By adding small amount of TiO2, aluminum slag could be used to synthesize cor-dierite, α-Al2O3, TiO2 and dehydrated talc could generate solid solution to accelerate the solid-state reaction to form cordierite. The experimental results show that the content of cordierite increases with the increase of TiO2 added. 3.0% of TiO2 is determined to be the best amount, because all crystalline substances are converted into cordierite at this content. Philips X‘pert plus software analysis shows that when the content of TiO2 is from 0 to 1.0%, cordierite has the same hexagonal structure as the single crystal and the lattice parameters change slightly; when the content of TiO2 is from 1.0 to 2.0%, the cordierite still keeps hexagonal structure but the lattice parameters change greatly; when the content of TiO2 is from 2.0 to 3.5%, the cordierite is converted from hexagonal into rhombic and the lattice parameters change accordingly.     

Research of High Temperature Crystalline Structure and Property Evolution of Magnesium Aluminate Spinel

Magnesium aluminate spinel （MgAl2O4） with high purity has been prepared by using anodized waste slag from aluminum factory and （MgCO3）4Mg（OH）2.5H2O as the main raw materials to discuss the change laws and characteristics of crystalline structure, microstructures and properties. X-ray diffraction （XRD） and scanning electron microscopy （SEM）, together with relevant analysis software, were used to characterize the crystal phases and microstructures so as to get MgAl2O4. Results show that when increasing the holding time the amount of MgAl2O4 increases fwstly and then keeps stable, but bulk density and bending strength increase firstly and then decrease. The best holding time is determined to be 3 h because at this time the corresponding MgAl2O4 content is up to 93%, bulk density 3.23 g·cm^3, apparent porosity 4.6% and bending strength 122.4 MPa.     

Influence of Impurity Na2O on Crystalline Structure of Cordierite Synthesized from Aluminum Sludge

Waste aluminum sludge, talc powder and clay were used to synthesize cordierite in this research. The impurities, such as Fe2O3, CaO, K2O and Na2O, in the raw materials have some influence on the structures and properties of the materials. In this paper, we mainly discuss the impact of impurity Na2O on the structure of cordierite, based on which the permitted amount of Na2O was determined. The results show that Na2O with the amount less than 0.6% has little influence on the cordierite formation; while when its amount increasing from 0.6% to 0.7%, the content of cordierite decreases from 86% to 84% and the permitted amount for Na2O in the raw materials is less than 6% with the best amount less than 0.3%. X‘pert plus software analysis results show the impurity Na2O has no influence on the cordierite space group and only the lattice parameters vary slightly; but it has much influence on the structure of Mg-AI spinel and the lattice parameters are much changed.     

Ca改性钛酸铅纳米晶的制备及结构研究

用溶胶-凝胶工艺制备了Pb_1-xCa_xTiO₃(0≤x≤0.3)纳米晶,在不同焙烧条件下研究其粉体晶相结构的变化.研究结果表明,升温速度和焙烧温度对纳米粉的晶相、晶胞参数和晶粒尺寸有显著影响.讨论了晶胞参数、四方畸变度和晶胞体积与Ca含量的关系.     

Synthesis of Free-Standing Crystalline Barium Titanate Films at Vapor/Liquid or Liquid/Liquid Interface

Synthesis of free-standing crystalline barium titanate (BaTiO₃) films at vapor/liquid or liquid/liquid interface at room temperature has been investigated. High concentration Ba, Ti alkoxides precursor solution (1.2 mol/l) or pre-hydrolyzed precursor solutions by water vapor in a H₂O/Ba molar ratio of 0 to 6 were used as dropping solutions at the interfaces. Transparent gel films were formed when partially hydrolyzed precursors (H₂O/Ba = 2 to 3) were spread out on a N₂/liquid paraffin interface. The films shrank from syneresis and vaporization of the solvent during aging at room temperature. As a result, free-standing transparent films with a thickness of around 1 m and little stoichiometric deviation were obtained by separation from the liquid surface and rinse by hexane. The films consisted of crystalline BaTiO₃ particles of less than a few nanometers. Nanostructured dense BaTiO₃ free-standing films with a grain size less than 100 nm were obtained at 1030°C.     

铝厂污泥在不同煅烧温度的晶相结构研究

铝厂污泥主要成分是-AlOOH,其中部分是晶体,部分是无定形体。将此污泥分别于450,600,800,1000,1050,1200和1300 ℃进行了煅烧,探讨污泥在不同温度下的晶相变化,为污泥的综合利用提供可靠的数据。采用XRD法和SEM法表征了污泥在不同温度下的晶相结构和显微结构。实验结果表明:随着煅烧温度的提高,污泥发生如下变化过程: 这与常规转化规律不同。在450,600,800,1000和1100 ℃的试样中均形成了-Al2O3和无定形体结构的微晶,随着温度的升高,-Al2O3含量增加而无定形体结构的微晶含量降低。当煅烧温度上升至1200和1300 ℃时, - Al2O3和无定形体结构的微晶全部转变为 - Al2O3。 -Al2O3是介稳态,高活性,-Al2O3是稳定态,低能态。     

CaO杂质对铝型材厂工业污泥合成堇青石材料晶相结构及其含量影响

探讨原料组成对铝型材厂工业污泥合成堇青石材料的影响是非常重要的。研究目的有助于确定不同杂质在原料中允许的存在量,为选择其他原料提供可靠的依据。采用XRD法和SEM法分析各试样的晶相结构:用半定量分析方法确定各晶相的含量:用philipsX抪ertplus软件确定试样中各晶相结构参数。实验结果表明:CaO杂质含量从1.2~2.5%对合成堇青石有利:从2.5~2.8%堇青石含量开始下降:确定2.5%为CaO杂质最佳存在量,其对应的堇青石含量为91%。经plus软件确定结果:CaO杂质含量为1.2%时,其结构与单晶相同,晶胞参数变化很小:CaO含量从1.2~2.8%,其晶系由六方转变为四方结构,晶胞参数发生较大变化。镁铝尖晶石结构与晶胞参数变化较大,由单晶的立方结构转变为四方结构。     

Influence of Fe_2O_3 Impurity on the Crystalline Structure of Cordierite Synthesized from Waste Aluminum Slag

1 INTRODUCTION Aluminum waste slag from aluminum factories isused as the main material to produce cordierite re-fractory material. The slag’s main composition is γ-AlOOH, which will convert into α-Al2O3 [1] at hightemperature, thus the product’s refractoriness can beimproved. Cordierite has good thermal stability andcan be widely served as high quality refractory ma-terial, electron encapsulating material, catalyst carrier,foamed ceramics, etc.[2]. Compared with th…     

焙烧处理下二氧化钛/钛酸盐纳米材料晶型和形貌的变化规律研究

通过调控酸碱浓度, 在水热条件下得到了金红石、锐钛矿、板钛矿、钛酸钠等一系列TiO₂/钛酸盐产物. 对上述TiO₂、酸洗处理后的钛酸盐等一系列不同晶型、不同形貌的样品进行焙烧处理, 系统性地研究焙烧温度的逐渐升高对产物晶型转变和形貌演化的规律性影响. 给出了水热酸碱浓度以及焙烧温度两个因素与TiO₂/钛酸盐纳米材料晶型和形貌变化行为关系的二维示意图. 依据奥斯特瓦尔德阶梯规则、经典热力学理论以及定向附着生长机理, 对TiO₂/钛酸产物的晶型晶体生长、晶型转变和形貌演化机理进行了探讨.     

分子动力学模拟在聚合物热解中的应用

分子动力学模拟作为分子模拟的重要分支已经在化学、化工、材料、生物等领域受到了广泛的关注。介绍了分子动力学模拟的基本原理,阐述了分子动力学模拟在高分子聚合物热解反应机理研究中的应用。实例表明:在研究物质化学反应机理方面,分子动力学模拟是一种有效的研究手段。