Phase equilibria in the CaO·SiO2Na2O·SiO2Na2O·Al2O3·6SiO2 system

Equilibrium phase relations in the system CaO·SiO₂Na₂O·SiO₂Na₂O·Al₂O₃·6SiO₂ at 40–80 wt% Na₂O·Al₂O₃·6SiO₂ composition range have been experimentally studied at temperatures between 800 °C and 1200 °C. The liquidus temperature was determined with differential scanning calorimetry. The equilibrated samples were quenched with pressurized nitrogen, and examined with electron probe X-ray microanalysis and X-ray diffraction for identification of microstructure and phase relations. Five primary phase fields, CaO·SiO₂, Na₂O·SiO₂, Na₂O·2CaO·3SiO₂, 2Na₂O·CaO·3SiO₂ and Na₂O·Al₂O₃·6SiO₂ were established. The ternary eutectic point of CaO·SiO₂, Na₂O·2CaO·3SiO₂ and Na₂O·Al₂O₃·6SiO₂ was determined to be at 1030 °C with the composition of 29.0 wt% CaO·SiO₂, 12.0 wt% Na₂O·SiO₂ and 59.0 wt% Na₂O·Al₂O₃·6SiO₂. Peritectic reaction of Na₂O·2CaO·3SiO₂, 2Na₂O·CaO·3SiO₂ and Na₂O·Al₂O₃·6SiO₂ occurred at 930 °C with the composition of 13.0 wt% CaO·SiO₂, 29.0 wt% Na₂O·SiO₂ and 58.0 wt% Na₂O·Al₂O₃·6SiO₂. The liquidus surface projection of the ternary system has been constructed in the composition region important for the bottom ash application.     

Electrical Properties and the Structure of Glasses in the xNa2O–(1 – x)2PbO · B2O3 System

The temperature–concentration dependences of the electrical conductivity and the activation energy for electrical conduction of glasses in the Na₂O–B₂O₃ and Na₂O–2PbO · B₂O₃ systems are studied. The investigation into the nature of the electrical conduction in these glasses reveals that the contribution from the electronic component (10^–3%) of the conductivity is within the sensitivity of the Liang–Wagner technique. A considerable alkali conductivity is observed upon introduction of more than 12 mol % Na₂O. The true transport number of sodium _Na is as large as unity at [Na₂O] 15 mol %. It is shown that the observed temperature–concentration dependences of the electrical and transport properties are governed by the ratio between the concentrations of polar and nonpolar structural–chemical units of the Na⁺[BO_4/2]^–, Na⁺[O^–BO_2/2] Na⁺[O^–BO_2/2], Pb²⁺ _1/2[BO_4/2]^–, Pb²⁺ _1/2[O^–BO_2/2], and [BO_3/2] types.     

A Study of Ionic Conductivity of Glasses in the PbCl2–PbO · B2O3 and PbCl2–2PbO · B2O3 Systems

The steady-state electrical conductivity of oxychloride glasses in the PbCl₂–PbO · B₂O₃ and PbCl₂–2PbO · B₂O₃ systems is investigated. In the temperature range from 190 to 380°C, the dependence of log on the reciprocal of the temperature exhibits a linear behavior. The nature of charge carriers is studied using the Hittorf technique. It is demonstrated that protons and chlorine ions are charge carriers in solid glasses. The concentration dependence of the transport numbers of chlorine ions is examined by the Tubandt method. The contribution of the electronic component to the total electrical conductivity is estimated with the use of the Liang–Wagner technique. The concentration dependences of the electrical conductivity and the transport numbers of chlorine ions are interpreted in terms of the microinhomogeneous glass structure associated with the selective interaction of components during synthesis of glasses.     

(NH4)2C2O4·H2O和NH4HC2O4·0.5H2O 单晶的培养研究

利用六次甲基四胺缓慢水解产生的NH3和草酸反应,扩散法培养出(NH4)2C2O4·H2O和NH4HC2O4·0.5H2O两种单晶.     

Ca2B2O5·H2O的热分解过程研究

采用水热法制备了片状Ca_2B_2O_5·H_2O水合硼酸盐前驱体,利用XRD、FI-IR及SEM等手段对样品进行了表征,利用TG-DTA热重分析法对Ca_2B_2O_5·H_2O的脱水热分解进行了分析。结合热分析结果和不同温度下焙烧产物的物相表征结果,研究上述硼酸钙的热分解过程,结果表明,热分解过程大致分为三个阶段:第一阶段硼酸钙失去表面的吸附水,第二阶段硼酸钙失去结晶水形成无定形的无水硼酸钙,第三阶段无水硼酸钙由无定形转化为结晶。     

氯化钡(BaCl_2·2H_2O)

正1)性质。无色单斜晶系结晶。冷结晶为扁平菱形,热结晶为无定形。工业品为白色片状或粉状结晶。结晶水在空气中稳定,加热到113℃时失去结晶水。易溶于水,溶解度随温度的升高而增大。有乙醇及氯离子(如氯化钙)存在时,溶解度显著降低。在乙醇及酸中的溶解度比在水中的溶解度小。在无水乙醇中失去结晶水,但并不溶解。不溶于丙酮。氯化钡的水溶液具苦咸味,并且因含氯离子而具有较强的腐蚀性。工业氯化钡有毒、不易燃、不易爆。     

分要对Na2O·CaO·2P2O5玻璃水解性的影响

运用化学分析和ＳＥＭ－ＥＤＸＡ等测试方法，研究了Ｎａ２Ｏ·ＣａＯ·２Ｐ２Ｏ５玻璃的分相形貌、分相组成与水解性关系。研究结果表明：玻璃分相形貌对玻璃的水解性有决定作用。分相有利于玻璃的生物活性．     

CaCl_2-HCl-H_2O体系中由CaSO_4·2H_2O制备CaSO_4·0.5H_2O的相转变过程研究

为了合理利用低浓度氯化钙废液,以浓硫酸与氯化钙废液反应制备的二水硫酸钙为原料,再以CaCl2-HClH2O混合电解质溶液为相转变介质,制备应用价值高的半水硫酸钙。文中研究了该体系中温度和HCl,CaCl2,Mg2+质量分数对CaSO4·2H2O脱水转变为CaSO4·0.5H2O所需的相转变时间、晶体形态变化的影响。以结晶水质量分数确定相转变时间,以晶体图片表征晶体形态的变化。结果表明:相转变时间随着温度以及HCl,CaCl2,Mg2+质量分数的增加而逐渐缩短;单因素实验研究中,温度高于343.15K,HCl,CaCl2,Mg2+质量分数分别超过3.65%,38.85%,0.001%时,相转变时间缩短趋势减缓;晶体形态逐渐由片状转变为针状。该方法可作为HCl法湿法磷酸工艺中低浓度氯化钙废液利用的有效途径。     

CaCl2-HCl-H2O体系中由CaSO4·2H2O制备CaSQ4·0.5H2O的相转变过程研究

为了合理利用低浓度氯化钙废液,以浓硫酸与氯化钙废液反应制备的二水硫酸钙为原料,再以CaCl2-HCl-H2O混合电解质溶液为相转变介质,制备应用价值高的半水硫酸钙.文中研究了该体系中温度和HCl,CaCl2,Mg2质量分数对CaSO4·2H2O脱水转变为CaSO4·0.5H2O所需的相转变时间、晶体形态变化的影响.以结晶水质量分数确定相转变时间,以晶体图片表征晶体形态的变化.结果表明:相转变时间随着温度以及HCl,CaCl2,Mg2+质量分数的增加而逐渐缩短;单因素实验研究中,温度高于343.15 K,HCl,CaCl2,Mg2+质量分数分别超过3.65％,38.85％,0.001％时,相转变时间缩短趋势减缓;晶体形态逐渐由片状转变为针状.该方法可作为HCl法湿法磷酸工艺中低浓度氯化钙废液利用的有效途径.     

FeCl_2·2H_2O焙烧过程动力学研究

用固定床研究了FeCl_2·2H_2O焙烧过程的动力学行为,变量包括温度、物料颗粒尺寸、气流速度和气流中含水量,讨论了过程的控制步骤,估算了表观反应速率常数和表观活化能,并用热分析校核了结果.     

Na_2SO_4·10H_2O和Na_2HPO_4·12H_2O体系的相变特性

主要研究了Na2SO4.10H2O体系、Na2HPO4.12H2O体系及它们的复合体系的相变特性,测定了升温曲线和降温曲线,并初步探讨了体系中分层和过冷现象的解决措施。研究结果表明,Na2SO4.10H2O体系的相变温度为33℃左右,由于它是一个不一致溶化合物,易产生分层现象,采用的增稠剂CMC可以显著改善分层现象,有轻微的过冷现象存在。Na2HPO4.12H2O体系的相变温度约35℃,冷却过程中没有分层现象,但过冷现象严重,(3%硼酸 3%硼砂)对改善该体系的过冷度有一定作用,但效果不佳。结合两个体系的实验结果,尝试了将Na2SO4.10H2O体系和Na2HPO4.12H2O体系进行复合以期得到新的相变特征,(80%Na2SO4.10H2O 20%Na2HPO4.12H2O)复合体系的相变温度为28~29℃,重复实验结果表明该体系重复性好,相变温度稳定,分层和过冷现象基本消除。     

On the Possibility of Forming Complexes with the Participation of O2– Ions in Melts and Glasses of the Na2O–SiO2–Cu2O System

The structural role of copper ions in melts (glasses) of the Na₂O–SiO₂–Cu₂O–CuO system is analyzed in the framework of the acid–base concept with due regard for the geometric (the radius ratio for Cu²⁽¹⁾⁺ and O^2– ions) and energy (the mean enthalpies of the Cu²⁽¹⁾⁺–O bonds) factors. It is demonstrated that copper ions in the structure fulfill the function of modifier cations. In these melts, the Cu¹⁺–Cu²⁺ redox equilibrium can be described without regard for the formation of [Cu²⁽¹⁾⁺O_4/2]^2(3)– ionic complexes (which could be incorporated into the structure of silicon–oxygen anions) and [Cu²⁺O _b/k ]^{2 – b/k} polyhedra providing the interaction between Cu²⁺ ions and anions. The influence of the formation of these polyhedra on the redox equilibrium is considered within the formalism of chemical thermodynamics. The composition dependence of the oxygen ion exponent pO is measured by an electromotive force (emf) technique. The ratio between the numbers of copper atoms with different valences is determined by chemical analysis. The experimental data obtained are in agreement with the theoretical inferences.     

Experimental determination of the liquidus line in the high Bi2O3 region in the TiO2–Bi2O3 system

Liquidus line in the high-Bi₂O₃-containing region of the TiO₂–Bi₂O₃ system was determined experimentally. The equilibrating and quenching technique with subsequent electron probe microanalyser (SEM-EDS) microanalysis were employed. Based on the data, liquidus line was constructed between 60 and 92 mol% Bi₂O₃. The current results showed a higher solubility of Bi₂O₃ in the liquid phase in equilibrium with the Bi₄Ti₃O₁₂ compound compared with the existing phase diagram. In addition, differential scanning calorimetry (DSC) was used to estimate the transformations covering the composition range from 60 to 95 mol% Bi₂O₃. Further, the phase diagram of the TiO₂–Bi₂O₃ system was calculated using a quasichemical model for the liquid phase. The thermodynamic properties of the intermediate compounds were estimated from the data of TiO₂ and Bi₂O₃ pure solids.     

Stability in the system CaO–Al2O3–H2O

The solubility of AH₃, CAH₁₀, C₂AH_7.5, and C₃AH₆ was determined experimentally at 7 to 40 °C and up to 570 days. During the reaction of CA, at 20 °C and above initially C₂AH_7.5 formed which was unstable in the long-term. The solubility products calculated indicate that the solubilities of CAH₁₀, C₂AH_7.5 and C₄AH₁₉ increase with temperature while the solubility of C₃AH₆ decreases. Thus at temperatures above 20 °C, C₃AH₆ is stable, while at lower temperature also CAH₁₀ and C₄AH₁₉ are stable, depending on the C/A ratio.At early hydration times, CAH₁₀ can be stable initially at 30 °C and above, as the formation of amorphous AH₃ stabilises CAH₁₀ with respect to C₃AH₆ + 2AH₃. With time, as the solubility AH₃ decreases due to the formation of microcrystalline AH₃, CAH₁₀ becomes unstable at 20 °C and above.     

Al2O3-3Al2O3·2SiO-ZrO2耐火材料的相组成

Al<,2>O<,3>-SiO<,2>-ZrO<,2>系耐火材料应用范围广,特别被用作陶瓷辊,具有力学强度高、抗热震性能优良、耐碱类化合物侵蚀和高温蠕变率低的特性.Al<,2>O<,3>-SiO<,2>-ZrO<,2>系耐火材料性能很大程度上取决于其结晶相和玻璃相的总量和化学成分,采用定量XRPD和XRF研究了原料中Al<,2>O<,3>/SiO<,2>比和氧化铝颗粒尺寸分布对结晶相和玻璃相的总量及其化学成分的影响.耐火材料由莫来石、刚玉、ZrO<,2>的多晶体和总量各异的玻璃相组成.莫来石含量及其晶胞参数和成分随烧成温度改变,但主要受原料中Al<,2>O<,3>/SiO<,2>比的影响.     

Rh–Sr/Al2O3 Catalyst for N2O Decomposition in the Presence of O2

The improving effect of Sr in the catalytic activity of Rh for N₂O decomposition has been studied under 1,000 ppm N₂O/He and 1,000 ppm N₂O/5% O₂/He (GHSV = 10,000 h^?1). Different techniques have been used for catalysts characterization: TEM, SEM-EDX, XRD, N₂ adsorption at ?196 °C and in situ XPS. Sr favours the Rh dispersion and reduction under reaction conditions, and allows the low temperature removal of N₂O in the presence of O₂ (100% decomposition at 350 °C).     

Promotional effect of H2O on the activity of In2O3‐doped Ga2O3–Al2O3 for the selective reduction of nitrogen monoxide

Effect of metal oxide additives on the catalytic performance of Ga₂O₃–Al₂O₃ prepared by the sol–gel method for the selective reduction of NO with propene in the presence of oxygen was studied. Of several metal oxide additives, the addition of In₂O₃ enhanced drastically the activity of Ga₂O₃–Al₂O₃ for NO reduction by propene in the presence of H₂O. In addition, the activity of In₂O₃‐doped Ga₂O₃–Al₂O₃ catalyst was extremely intensified by the presence of H₂O below 350°C. The promotional effect of H₂O was interpreted by the suppression of undesirable propene oxidation and the removal of carbonaceous materials deposited on the catalyst surface. We also found that close interaction of In₂O₃ and Ga₂O₃ is necessary for the enhancement of activity by H₂O. A lot of hydrocarbons except methane and oxygenated compounds served as good reducing agents, among which propene and 2‐propanol were the most efficient ones. In₂O₃‐doped Ga₂O₃–Al₂O₃ catalyst was capable of reducing NO into N₂ quite efficiently in the presence of H₂O at a very high space velocity. This revised version was published online in July 2006 with corrections to the Cover Date.     

CaCl_2·2H_2O流态化脱水过程的研究

本研究建立了一套以卧式多室流化床干燥机（６００×１５０）为主体设备的ＣａＣｌ２·２Ｈ２Ｏ流化脱水实验装置,通过实验研究确定了ＣａＣｌ２·２Ｈ２Ｏ流化脱水的工艺条件。     

ZnO·Al2O3修饰Al2O3微滤膜的研究

以硝酸锌、硝酸铝、尿素为主要原料,采用均相沉淀法对Al2O3微滤膜进行了ZnO*Al2O3涂覆改性研究.实验结果表明,在适宜的涂覆液浓度、涂覆次数条件下,ZnO*Al2O3改性后可使微滤膜的水通量提高15～20%,且具有较高耐酸碱性能.