富Al2O3区域Al2O3—Na2O—CaO—SrO系固态反应的研究

本文,用理学X-射线衍射仪研究了富Al_2O_3区域Al_2O_3-Na_2O-CaO-SrO系的固态反应。实验结果表明,煅烧过程固态反应的最终物相组成为Na_2O·11Al_2O_3、CaO·6Al_2O_3、SrO·6Al_2O_3与α-Al_2O_3共存。     

ZrO_2界面相对3D-Al_2O_3/Al_2O_3复合材料性能的影响

实验主要采用溶胶凝胶法(sol-gel)制备3D-Al_2O_3/Al_2O_3复合材料,并在纤维和基体之间制备ZrO_2界面相,通过三点弯曲实验分析材料的力学性能;通过扫描电镜观察破坏规律。研究表明,所制备的3D-Al_2O_3/Al_2O_3复合材料,其基体的主要成分为α-Al_2O_3,引入ZrO_2界面相的复合材料弯曲强度达到75.2MPa,与无界面相复合材料弯曲强度(62.3 MPa)相比提高了20.7%,无界面相Al_2O_3/Al_2O_3复合材料断口平整,呈现脆性断裂,存在ZrO_2界面相的Al_2O_3/Al_2O_3复合材料断口有大量纤维拔出,表现出类似金属断裂的假塑性断裂特征。     

添加Al_2O_3对ZrO_2(Y_2O_3)粉末性能的影响

采用化学共沉淀法制备了ZrO_2(Y_2O_3)和ZrO_2(Y_2O_3)/Al_2O_3超细粉末,研究了添加Al_2O_3对粉末性能的影响.添加Al_2O_3.提高了t—ZrO_2的结晶化温度,抑制了ZrO_2晶粒生长.使ZrO_2粒子得以细化.添加Al_2O_3.还提高了介稳t—ZrO_2的稳定性,有效抑制了t—ZrO_2→m-ZrO_2相变.Al_2O_3添加量超过20wt%时.粉末烧结活性降低,烧结温度提高.     

Al2O3—ZrO2—SiO2系相图结构特征的研究

按照Al_2O_3/SiO_2比值,在Cevales给出的Al_2O_3-ZrO_2-3Al_2O_3·2SiO_2系的无变量点附近选择了6个组成,对其进行了熔体自然冷却、缓冷和淬冷析晶试验,并对析晶后的试样进行了XRD、SEM和EDAX分析,结果表明:(1)相平衡关系与Cevales给出的Al_2O_3-ZrO_2-3Al_2O_3·2SiO_2系相图的结构特征吻合得很好,其无变量点为低共熔点;(2)莫来石晶相的Al_2O_3/SiO_2比值波动于A_3S_2-A_(?-7)S之间,与Aramaki和Roy测定的Al_2O_3-SiO_2系莫来石稳态固溶体的Al_2O_3上限含量为74.3％是一致的;(3)析晶的单一莫来石晶相的EDAX能谱中不存在Zr谱线,ZrO_2在莫来石中的固溶问题,应进一步研究。     

Al_2O_3含量对ZrO_2/Al_2O_3复相陶瓷流变性能和抗弯强度的影响

采用有机泡沫浸渍法制备ZrO_2/Al_2O_3复相陶瓷,分析Al_2O_3添加量对泡沫陶瓷显微形貌、相结构、抗弯强度和浆料流变性能的影响,确定制备复相陶瓷的最佳工艺参数。实验结果表明,ZrO_2/Al_2O_3复相陶瓷由m-ZrO_2相、t-ZrO_2相和Al_2O_3相组成;当Al_2O_3的含量为20 wt%时,烧结的陶瓷颗粒致密均匀,陶瓷的抗弯强度最佳,浆料表观粘度增加;增加Al_2O_3的含量到40 wt%,陶瓷出现较多气孔,浆料的表观粘度增加幅度不大;Al_2O_3的添加影响了复相陶瓷的致密性、晶粒尺寸、相结构等因素;制备ZrO_2/Al_2O_3复相陶瓷时,最佳工艺参数为20 wt%Al_2O_3和80 wt%ZrO_2。     

CO_2 methanation over TiO_2–Al_2O_3 binary oxides supported Ru catalysts

TiO_2 modified Al_2O_3 binary oxide was prepared by a wet-impregnation method and used as the support for ruthenium catalyst. The catalytic performance of Ru/TiO_2–Al_2O_3catalyst in CO_2 methanation reaction was investigated. Compared with Ru/Al_2O_3 catalyst, the Ru/TiO_2–Al_2O_3catalytic system exhibited a much higher activity in CO_2 methanation reaction. The reaction rate over Ru/TiO_2–Al_2O_3 was 0.59 mol CO_2·(g Ru)1·h-1, 3.1 times higher than that on Ru/Al_2O_3[0.19 mol CO_2·(gRu)-1·h-1]. The effect of TiO_2 content and TiO_2–Al_2O_3calcination temperature on catalytic performance was addressed. The corresponding structures of each catalyst were characterized by means of H_2-TPR, XRD, and TEM. Results indicated that the averaged particle size of the Ru on TiO_2–Al_2O_3support is 2.8 nm, smaller than that on Al_2O_3 support of 4.3 nm. Therefore, we conclude that the improved activity over Ru/TiO_2–Al_2O_3catalyst is originated from the smaller particle size of ruthenium resulting from a strong interaction between Ru and the rutile-TiO_2 support, which hindered the aggregation of Ru nanoparticles.     

Ru-Fe/Al_2O_3氧化-还原性能探究

以Al_2O_3为载体,RuCl_3·xH_2O和FeCl_3·6H_2O为活性组分前驱体,采用吸附-沉淀法制备了Ru-Fe/Al_2O_3和Ru/Al_2O_3催化剂,以马来酸二甲酯加氢合成丁二酸二甲酯为探针反应,结合H_2-TPR和XRD表征技术,考察Fe改性Ru基催化剂的氧化-还原性能及催化活性。经氧化-还原循环处理后,催化剂Ru-Fe/Al_2O_3上马来酸二甲酯加氢活性高于Ru/Al_2O_3。XRD结果显示,经处理的Ru-Fe/Al_2O_3上未见金属Ru的特征衍射峰,而Ru/Al_2O_3上出现了金属Ru的特征衍射峰。结合H_2-TPR结果推断,Ru与Fe之间发生了相互作用,这种协同作用可以改善Ru/Al_2O_3催化剂的热稳定性。     

ZrO2—Al2O3系陶瓷复合材料力学性质

本文研究了ZrO_2-Al_2O_3系统陶瓷复合材料的力学性质,发现有两个最佳区域存在:在Al_2O_3基的陶瓷中,添加第二相ZrO_2颗粒可以使Al_2O_3瓷得到增韧和强化;在ZrO_2基的陶瓷中,添加少量Al_2O_3则可以通过Al_2O_3晶粒的裂纹弯曲和分叉增韧,强化ZrO_2的相变增韧,使ZrO_2瓷的强度和断裂韧性得到进一步的提高。适宜地控制YMSZ(Y_2O_3亚稳定ZrO_2)中Y_2O_3和TZP(四方相氧化锆多晶瓷)中的Al_2O_3量,可以获得高韧性和高强度的ZrO_2-Al_2O_3系陶瓷复合材料。     

助剂Ba对Pd/Al_2O_3和Pt/Al_2O_3催化剂的C1-C3烷烃催化燃烧性能的影响

通过浸渍法制备了Al_2O_3负载的Pd和Pt催化剂,考察催化剂的甲烷、乙烷和丙烷催化燃烧活性,以及助剂Ba对催化性能的影响。对于Pd/Al_2O_3催化剂,加入Ba使活性物种PdO颗粒变大和还原温度升高,形成更稳定的PdO活性物种,是Pd-Ba/Al_2O_3催化剂活性提升的主要原因。对于Pt/Al_2O_3催化剂,加入Ba助剂使活性物种Pt0含量降低,PtO_x与Al_2O_3载体相互作用增强,使PtO_x物种更难被还原为Pt~0,导致Pt-Ba/Al_2O_3催化剂活性降低。Pd和Pt催化剂催化烷烃氧化反应活性规律一致:丙烷乙烷甲烷。Pd/Al_2O_3催化剂有利于C—H键活化,Pt/Al_2O_3催化剂有利于C—C键活化。Pt/Al_2O_3催化剂对C1-C3烷烃氧化活性的差别明显大于Pd/Al_2O_3催化剂。Pt/Al_2O_3催化剂对碳比例高的烷烃活性更高。     

快速测定β-Al_2O_3中钠的磷酸溶解法

一、前言β-Al_2O_3是钠——硫电池的隔膜材料,系层状结构,它可看做铝酸钠的盐类。一般人工合成的β—Al_2O_3是β′—Al_2O_3(Na_2O·11Al_2O_3)与β″—Al_2O_3(Na_2O·5Al_2O_3)两种β—Al_2O_3的混合物,其Na_2O含量介于5-11%之间。对于β—Al_2O_3中钠的分析测定,我们先后试用了“斯密斯”法、“贝齐里乌斯”法、“硼干”法和我们找到的“磷     

SO2-Na2S-H2O体系热力学分析

利用Na<,2>S溶液吸收SO<,2>是湿法烟气脱硫中具有良好应用前景的新方法.为了能更好地利用Na<,2>S溶液进行烟气深度脱硫,文中通过热力学计算,对Na<,2>S溶液吸收SO<,2>烟气所构成的SO<,2>-Na<,2>S-H<,2>O体系中气液固三相组成与pH值的关系进行了分析.结果表明,pH值大于6时,SO<...     

Li2O-Na2O-K2O-CaO-MgO-Al2O3-SiO2系统乳浊釉的研究

对Li2O-Na2O-K2O-CaO-MgO-Al2O3-SiO2系统釉进行了较全面的正交试验研究,找到了影响该系统釉乳浊及釉面质量的主次因素,获得了性能良好的乳浊釉及其较优乳浊釉配方.     

2-甲基-2-噁唑啉的合成研究

以N-(2-羟基乙基)乙酰胺为原料,在二水乙酸锌的催化作用下,脱水缩合生成2-甲基-2-噁唑啉,考察了温度、催化剂用量、压力、时间对反应的影响。最佳工艺条件为:m(催化剂):m(N-(2-羟基乙基乙酰胺))=0.15∶1,反应温度为185℃,压力为0.01 MPa,反应时间为2 h,收率可达到95%。并考察了催化剂的重复使用情况。产物经质谱进行了结构表征。     

2-甲基-1-丁烯的异构化

在酸性树脂催化剂上进行了2 甲基 1 丁烯(2MB1)的异构化,得到了高2 甲基 2 丁烯含量的异戊烯产品。在反应压力为0.62MPa,温度为30℃左右,空速在8～11h-1的条件下,2MB1的转化率大于70%,异戊烯收率大于97%,产物中2MB2与2MB1的比例大于10,可以满足下游工序对产品的要求。     

R2O-RO-Al2O3-B2O3-SiO2系统在骨质瓷中的应用

实验采用正交实验法和对比实验，通过对R2O-RO-AlO3-B2O3-SiO2系统的成釉机理分析及熔融特性、熔体的粘度和表面张力等性能的测试，探讨了该系统在骨质瓷中的应用。     

炉渣组分对CaO-Al2O3-SiO2-TiO2-MgO-Na2O渣系粘度的影响

针对高碱度高氧化铝含氧化钠的CaO-Al2O3-SiO2-TiO2-MgO-Na2O六元渣系,采用有限制的混料均匀设计方法设计实验,在1773 K温度熔融还原条件下测定了该渣系的粘度. 利用偏最小二乘法回归分析,建立了炉渣组分与粘度的回归方程,利用回归方程分析了炉渣碱度[w(CaO)/w(SiO2)], MgO, TiO2, Al2O3及Na2O对炉渣粘度的影响. 结果表明,回归方程拟合的关联系数RC2为0.9945,方程可很好地预测该渣系的粘度. 在实验范围内,炉渣粘度随碱度的增加而增加. 碱度一定时,炉渣粘度随MgO, Al2O3, Na2O含量的增加而逐渐降低,随着TiO2的增加先降低后增加. 当炉渣碱度小于3.1、MgO质量含量大于4%、Al2O3大于20%、TiO2在3.1%~6.1%、Na2O大于0.75%时,1773 K温度下炉渣粘度均小于2 Pa×s,此时渣系粘度完全满足实际冶炼要求.     

Electrochemical reduction of 2-chloro-2-cyclohexenones

The electrochemical reduction of the 2-chloro-2-cyclohexenones 2a–2c (mercury cathode, CH₃CN,Bu₄NBF₄) was studied by means of cyclic voltammetry, dc polarography, coulometry and chemical product analysis. The results were compared to those obtained with the analogous 2-cyclohexenones 1a–1c. Due to the chloro-substituent on C—2 the half wave potentials E_1/2 for the first electron transfer step become less cathodic and the overall mechanism of reduction of a chloro-substituent on C—6 is modified. In addition, strong inhibition effects were observed in the cyclic voltammograms of compound 2 and it was found that other 2-halogeno-2-cycloalkenones exhibit a similar behaviour.     

减少H2O2干扰测定稳定性ClO2含量的方法

用碘量法测定稳定性ClO2溶液中的ClO2含量时,当稳定液中过碳酸盐过量,测定结果会偏高.作者提出将待测样酸化后加入稍过量的K2Cr2O7与其中的H2O2反应以消除其影响,再用碘量法测定的新方法.方法操作简便,结果可靠,为较准确地检测含过量过碳酸盐的稳定性ClO2溶液中的ClO2真实含量提供了新的途径.     

Crystallization Hierarchy of CaO-P2O5-SiO2-Al2O3-TiO2 Glass-Ceramics

Glasses in the tricalcium phosphate-anorthite (Ca₃(PO₄)₂-CaAl₂Si₂O₈ or TCP-CAS₂) system with additional TiO₂ were melted. Crystallization was investigated using thermal analysis, X-ray diffraction, and transmission optical and electron microscopies. During the heat treatment, as the growth temperature increases, successive crystalline phases separate from the glass matrix. The phases present in the fully heat-treated glass-ceramic are ß-TCP, anor-thite (CAS₂), and rutile (TiO₂). Apart from TiO₂, these phases evolve from other polymorphs during the heat treatment. The metastable phases, pseudo-orthorhombic CAS₂ and alpha-TCP, appear first around 880°C and transform into the stable phases, triclinic anorthite CAS₂ and ß-TCP, around 940° and 1000°C, respectively. The material crystallizes in stages. The first stage is the separation from the glass matrix of rutile and what is believed to be a calcium phosphate phase, with crystal sizes varying from 20 to 200 nm. This is followed by the appearance of larger crystals (1-2 µm) of the metastable pseudo-orthorhombic CAS₂, surrounding the previously crystallized phases. Finally, this pseudo-orthorhombic CAS₂ phase transforms to anorthite (15-20 µm) spherulites. TiO₂ does not act as a direct nucleating agent in the glass composition studied: no sign of heterogeneous nucleation and growth from TiO₂ crystals has been found, and moreover, TiO₂-free base glass crystallizes in a manner similar to that of the glass containing TiO₂.     

KCl-MgCl2-LiCl 及 CaCl2-MgCl2-NaCl 熔盐系中MgCl2活度的简化亚正规模型

建立了一个描述KCl-MgCl2-LiCl及CaCl2-MgCl2-NaCl熔盐体系中MgCl2活度的溶液模型.模型假定将所讨论体系中的盐处理成独立的粒子而不是它们的离子形式,并对上述熔盐组元对之间的相互作用进行了分析,用随MgCl2成份变化的相互作用能可以较好地描述MgCl2的活度.与前人结果比较,本模型所用参数少且物理意义较明确.