几种表面活性剂对Mn_3O_4生成形貌的影响

针对双氧水-乙醇体系与硫酸锰溶液反应制备四氧化三锰的过程中有颗粒团聚问题,研究了向反应体系中分别引入不同的表面活性剂(硬脂酸、十二烷基硫酸钠(SDS)、十二烷基苯磺酸钠(SDBS)、聚乙烯吡咯烷酮(PVP)和聚乙二醇(PEG)),考察了不同表面活性剂及投加量对生成的四氧化三锰形貌与物相的影响。结果表明:表面活性剂的加入对四氧化三锰的物相没有影响;对形貌影响较大,加入量不同,四氧化三锰形貌不同。正交试验结果表明,制备四氧化三锰的最佳条件为SDS质量0.4g,乙醇体积6mL,反应时间2h,反应温度为室温,搅拌速度400r/min。     

四氧化三锰粒度及微观形貌的控制

研究了以硫酸锰为原料,采用空气直接一步氧化法制备四氧化三锰.向反应体系加入不同类型表面活性剂,考察了表面活性剂种类及用量、反应物浓度、搅拌速度、反应温度及氨锰物质的量比等条件对所制备四氧化三锰粒度及形貌的影响.结果表明:表面活性剂对四氧化三锰的粒度和形貌有调控作用,以十二烷基苯磺酸钠(SDBS)为表面活性剂可得到类球形四氧化三锰;在SDBS加入量1.0 g、硫酸锰浓度1.0 mol/L、搅拌速度500 r/min、反应温度70℃、氨锰物质的量比2.6/1条件下,所得四氧化三锰的粒度D50=11.24μm,振实密度达2.47 g/cm3,比表面积为0.87 m2/g,锰质量分数为70.58％,产品质量较好.     

一步氧化法制备类球形四氧化三锰

研究了以硫酸锰、氨水为原料,空气为氧化剂,采用一步氧化法制备类球形四氧化三锰,考察了表面活性剂对四氧化三锰物相、粒度、振实密度、比表面积、锰质量分数及微观形貌的影响。结果表明:表面活性剂种类对四氧化三锰物相没有影响,但对粒度、振实密度、比表面积及微观形貌影响显著;以十六烷基三甲基溴化铵为表面活性剂,在硫酸锰浓度2.0 mol/L、硫酸锰加料速度15 mL/min、搅拌速度300 r/min、反应时间20 h条件下,可获得综合性能较优的类球形四氧化三锰。     

CTAB对水热合成纳米MoS_2颗粒的影响研究

以仲钼酸铵((NH4)6Mo7O24·4H2O)为钼源,硫脲(CS(NH2)2)为硫源和还原剂,阳离子表面活性剂CTAB为分散剂,采用水热法合成了纳米Mo S2。为防止产物团聚、抑制其长大并控制其形貌,添加了不同浓度的阳离子表面活性剂CTAB,对水热合成过程进行了控制研究,通过XRD和SEM对产物物相纯度和形貌进行表征,从微观结构理论的角度分析了CTAB加入对反应过程和产物形貌及分散性的影响。结果显示,阳离子表面活性剂CTAB的加入对产物Mo S2的结晶粒度和结晶度有影响,同时又起着模板和分散剂的作用。当其添加量为5倍的临界胶束浓度时,对抑制产物的团聚和形貌的修饰作用最强。     

表面活性剂对LiNi0.8Co0.1Mn0.1O2正极材料形貌和储锂性能的影响

表面活性剂在材料合成时具有形貌控制方面的重要作用,为提高镍三元正极材料LiNi_0.8Co_0.1Mn_0.1O₂的综合电化学性能,本文通过在正极材料前驱体Ni_0.8Co_0.1Mn_0.1(OH)₂合成过程中加入不同的表面活性剂来控制三元材料的形貌,并对煅烧后所得的高镍三元产物材料LiNi_0.8Co_0.1Mn_0.1O₂进行形貌和电化学性能分析,结果表明：利用表面活性剂合成的产物材料有着更加规整的形貌和晶体结构稳定性;分别添加十二烷基苯磺酸钠、蔗糖、十六烷基三甲基溴化铵以及聚乙二醇之后,首次充电比容量分别可以达到232.2 mAh·g^-1、248.1 mAh·g^-1、231.3 mAh·g^-1以及216.1 mAh·g^-1,其中十六烷基三甲基溴化铵的...     

表面活性剂强化铜矿石浸出

为了解决铜矿石浸出速度慢、浸出率低的问题,在浸出液中加入表面活性剂进行摇瓶试验.通过测量浸出前后溶液表面张力以及铜浸出率,考察了三种不同类型的表面活性剂对铜矿石浸出的影响.研究发现溶液表面张力对矿石浸出影响较大,阴离子表面活性剂的强化浸出作用最为明显,铜浸出率达62.5%.在柱浸试验中,添加阴离子表面活性剂使铜浸出率提高了近10%.利用物理化学和渗流力学对表面活性剂强化浸出机理的分析表明,溶液表面张力和表面活性剂在矿石表面的吸附对矿石表面润湿作用影响较大,表面活性剂在浸出液的持久性也是影响浸出的因素之一.      

WO3催化材料的制备及性能研究

以仲钨酸铵和盐酸为主要原料，采用水热法制备了100℃、120℃、140℃和160℃水热温度下的WO₃粉体并进行热处理。利用扫描电镜(SEM)对WO₃粉体进行表征分析，并进行光催化性能测试。研究结果表明：随着水热温度的升高，WO₃粉体形貌由颗粒团聚结构变成针状团聚结构，团聚程度下降，结构空隙增多，说明水热温度与热处理会影响WO₃粉体的晶体结构。由光催化测试结果可知，在100℃水热温度下制备的WO₃粉体经热处理对罗丹明B降解效率在50min时达到最高，约为50.06%，进而说明WO₃粉体晶体结构的结构空隙和团聚程度又会对其催化性能有一定影响。     

Sc2O3掺杂对ScSZ粉体制备过程的影响研究

本文以ZrOCl₂·8H2O和Sc₂O₃为原料,聚乙二醇(PEG800)为分散剂,氨水为沉淀剂,采用共沉淀法制备了不同钪掺杂量的氧化钪稳定氧化锆(ScSZ)复合粉体,并通过TG/DSC热分析、ICP、XRD、Raman和SEM等分析手段对样品进行表征,研究了Sc₂O₃掺杂对ZrO₂前驱体热稳定性和ZrO₂粉体物相、形貌等的影响,还探讨了洗涤方式对所制备的ScSZ粉体形貌的影响。结果表明:ZrO₂和ScSZ前驱体均为无定形状态,经煅烧后ScSZ前驱体的总失重量大于ZrO₂前驱体的总失重量;未掺杂钪所制备的ZrO₂粉体为单斜相,钪掺杂改变了物相,ScSZ粉体为四方和立方相的混合晶型;钪掺杂对ZrO₂粉体的粒径无明显影响,ZrO₂和ScSZ粉体均发生一定团聚,团聚体直径约为0.5~3μm;采用乙醇洗涤有利于减小ScSZ粉体的初级纳米颗粒粒径,减小团聚现象,粉末团聚较松散。     

用于YAG透明陶瓷的喷雾造粒改性粉体的制备

通过喷雾造粒方法对共沉淀合成的纳米粉体进行改性,制备出球形的纳米颗粒.用XRD对粉体进行物相分析;用TEM观察了改性前粉体的颗粒形状、尺寸大小和团聚情况;用SEM观察改性前后粉体的团聚体的颗粒形状、尺寸大小与分散性,以及陶瓷热腐蚀抛光后的表面形貌.结果表明:PVB添加质量分数1.0%为最优添加量;改性后粉体所制素坯的密度显著提高,从而影响陶瓷的致密度和晶界形貌;经真空烧结制备出相对密度达99.95%的无孔净晶界YAG透明陶瓷,陶瓷晶粒的平均尺寸为10μm左右,尺寸分布较均匀,晶界清晰,晶粒中与晶界处较干净,无杂质与气孔的存在.     

石墨表面改性工艺对镍包石墨粉末性能影响研究

本文采用热处理工艺和表面活性剂对石墨表面进行改性处理,采用氢还原包覆工艺制备镍包石墨粉末,对比了不同石墨热处理工艺和表面活性剂的添加对镍包石墨粉末表面形貌和物理性能的影响。研究表明,在热处理温度500℃,采用醇类活性剂表面处理石墨后,通过加压氢还原工艺制备的镍包石墨粉末具有较好的表面包覆完整性和优异的粉末松装密度和流动性。     

Superconducting Transition Temperature in YBa2Cu4O8/La2/3 Ca1/3 MnO3 / YBa2 Cu4O8 Heterostructure

YBa2Cu4O8/La2/3 Ca1/3 MnO3/YBa2Cu4O8 （ Y-124/LCMO/Y- 124） heterostructure was prepared by facing-target sputtering technique. The oscillatory superconducting transition temperature was observed when the thickness of LCMO d L is larger than critical thickness d L^CR. The metal-insulator transition temperature can only be detected at d L 〉 d L^CR. The dependence on the spacer layer in LCMO/Y-124 systems suggests strongly the interplay of ferromagnetic and superconducting couplings.     

Visible luminescence of lanthanide ions in Ca3Sc2Si3O12 and Ca3Y2Si3O12

The crystalline materials Ca₃Sc₂Si₃O₁₂ and Ca₃Y₂Si₃O₁₂ were characterized by different crystal structures, as the former is a cubic garnet, while the latter is an orthorhombic compound. We investigated the optical spectroscopy of these materials doped with several trivalent lanthanide ions and compared the results for the two hosts. Polycrystalline samples were prepared by solid state reaction, both undoped and doped with the trivalent lanthanide ions Eu³⁺, Tb³⁺ and Sm³⁺. Emission, excitation and Raman spectra of these materials were measured at temperatures ranging from 300 to 10 K. The optical spectra were assigned and discussed, and the effects of the crystal structure of the host on the spectroscopic behaviour were addressed. The technological potential of these compounds in the field of optical materials and devices was discussed.     

Al2O3La2O3Y2O3/Cu复合材料的电弧侵蚀特性研究

采用喷射沉积和内氧化法制备出Al₂O₃La₂O₃Y₂O₃/Cu复合材料,研究该材料在直流20 V/20 A的工作条件下触点的电弧侵蚀特性,并与Al₂O₃/Cu材料进行了对比分析.利用电子天平、扫描电镜等方法分析电弧侵蚀后触点的质量变化和表面微观结构.结果表明,通过添加Y₂O₃、La₂O₃稀土氧化物颗粒,可有效降低触头材料的材料转移量.Al₂O₃La₂O₃Y₂O₃/Cu材料的抗熔焊性和抗烧损性优于Al₂O₃/Cu材料的性能.在直流阻性负载条件下Al₂O₃La₂O₃Y₂O₃/Cu阳极触头表面形成凹坑,阴极触头表面形成凸起,触点表面显示出浆糊状凝固物和喷发坑等电弧侵蚀形貌特征.      

CaO—SiO2—Na2O—CaF2—Al2O3—MgO保护渣系的Al2O3吸收速率和粘度

采用CaO-SiO2-Na2O-CaF2-Al2O3-MgO渣系,通过测定熔渣的粘度和Al2O3吸收速率,研究连铸保护渣的Al2O3吸收速率与粘度及化学成分之间的关系。在一定条件下,当CaO/SiO2为1.2左右时,粘度达到最小值,Al2O3吸收速率达到最大值,分别为0.10?Pa*s、8.403×10-4?kg*m-2*s-1。随着渣中Na2CO3含量、CaF2含量和MgO含量的增加,粘度减小,Al2O3吸收速率增大。随着渣中Al2O3含量的增加,粘度增大,Al2O3吸收速率减小。粘度为Al2O3吸收速率的主要控制因素。随着熔渣粘度的增加,连铸保护渣的Al2O3吸收速率逐渐减小。     

CaO-La2O3-B2O3-Eu2O3转光玻璃的合成及荧光性质

X射线衍射研究表明CaO-La2O3-B2O3-Eu2O3体系的玻璃化温度在1025℃附近.荧光光谱和ESR谱研究表明,在CaO-La2O3-B2O3-Eu2O3玻璃体系中存在着Eu2+和Eu3+两种价态离子. 316, 360, 379, 394, 413, 462和532nm锐线激发峰和592,616和650红区发射峰分别对应Eu3+的f-f激发跃迁和5D0-7FJ (J=1,2,3)跃迁发射;351nm和427nm宽带激发峰和蓝区发射分别对应Eu2+的5d-4f激发跃迁和发射.     

Fracture Behavior in Cu46.5Zr46.5Al7 and Cu46.5Zr41.5Al7Y5 Bulk Metallic Glasses

The interplay between chemical composition, plastic behavior, and fracture modes of Cu_46.5Zr_46.5Al₇ and Cu_46.5Zr_41.5Al₇Y₅ bulk metallic glasses (BMGs) was investigated by compression tests and fracture surfaces analyses. The aim was to explore the possibility of coupling physical, chemical, and hardness properties, with adequate macroscopic compressive plasticity. Cylindrical test samples, having a height-to-diameter ratio equal to 2, were machined and ground from as-cast bars and were tested in compression between lubricated plates, the displacement being measured by a clip-gage inserted between the plates. Y free BMG engineering stress-strain curves show a plastic behavior consisting of successive sudden stress drops and linear reloading segments. A detailed analysis of these features was performed to yield a correlation between the plastic deformation steps and the released elastic energy associated with each serration.     

CaO--TiO2--Fe2O3三元系中Ca3TiFe2O8的生成机理

钒钛磁铁矿是烧结矿重要的原料之一,Ca₃TiFe₂O₈作为钒钛烧结矿中矿物被发现之后,其生成机理尚不明确.本文采用X射线衍射分析、元素能谱分析和TG-DSC分析相结合的方法,研究了Ca₃TiFe₂O₈的生成机理以及不同温度、CaO与TiO₂含量下Ca₃TiFe₂O₈的生成规律.实验结果表明,Ca₃TiFe₂O₈由Ca₂ Fe₂O₅和CaTiO₃反应生成,即CaO和Fe₂O₃反应生成Ca₂ Fe₂O₅;其后,与CaTiO₃反应生成Ca₃TiFe₂O₈.反应时间越长,Ca₃TiFe₂O₈的生成量越大,但反应温度对Ca₃TiFe₂O₈生成的影响并不明显.另外,还发现CaO含量越高,Ca₃TiFe₂O₈越易于生成,而且等摩尔Fe₂O₃和CaO下只要存在TiO₂,就会有Ca₃TiFe₂O₈生成.      

Effect of Fe2O3 Loading Amount on Catalytic Properties of Monolithic Fe2O3/Ce0.67Zr0.33O2 -Al2O3 Catalyst for Methane Combustion

Ce0.67Zr0.33O2-Al2O3 solid solution was prepared by the co-precipitation method. Fe2O3-based catalysts supported on the solid solution were obtained by the impregnation method. The article revealed that the optimal loading amount of Fe2O3 on Ce0.67Zr0.33 O2-Al2O3 in our experimental condition for catalytic combustion of methane was 8% （ mass fraction）. The prepared catalysts were characterized by BET, TPR, XRD analyses, and their catalytic activity was investigated after being calcined at 873 K and after being aged in water gas at 1273 K. When the loading amount of Fe203 was 8% （ mass fraction）, the catalyst held the highest activity, and the best temperature speciality and thermal stability. The complete-conversion temperature of methane for fresh and aged sample was 788 and 838 K, respectively. The range between the light-off temperature and the complete-conversion temperature was only 15 K. The characterization results of XRD indicated that Fe2O3 was well dispersed on the Ce0.67Zr0.33O2-Al2O3 matrix. The results of BET and TPR were in good harmony with the catalytic activity results.     

Magnetocaloric Effect of Ni56Mn18.8Ga24.5 Gd0.7 Alloy

Inrecent years materials with high magnetocaloriceffect (MCE) have attracted considerable attention ow-ingto its potential application as a magnetic refriger-ant .Many material systemsthat underwentthefirst-or-der magnetic transition have been found to exhibit agiant MCE. Their typical representatives areGd5(SixGe1 -x)4[1 ,2]and La (FexSi1 -x)13[3 ,4]alloys .Ni MnGa is aferromagnetic shaped memory alloy whichundergoes a reversible first-order structural phase tran-sition (SPT) with the …     

Al2O3-V2O5体系的热力学优化

在对Al₂O₃-V₂O₅体系相图、热力学数据以及晶体结构数据进行综述与评估的基础上,采用相图计算方法对Al₂O₃-V₂O₅体系进行热力学优化.液相采用修正的似化学模型进行描述,利用对近似处理液相中存在的短程有序.将液相模型的最大短程有序设置在AlVO₄处,将VO₄3-当作液相中V₂O₅的基本组成单元.体系中AlVO₄相看作线性化合物.计算结果很好的重现了选定的实验数据,获得了一套合理、可靠、自洽的模型参数用来描述体系中各相的热力学性质,为Al₂O₃负载V₂O₅型催化剂催化性能的提高打下坚实的基础.