DBS包覆钛盐水解制备纳米TiO2的研究

以Ti(SO_4)_2水溶液为前驱体,NH_3·H_2O为沉淀剂,以十二烷基苯磺酸钠(dodecyl benzene sulfonate,DBS)为表面活性剂,采用常温水解沉淀法制备出了纳米TiO_2粉体。用XRD测试粉体的晶相组成;用TEM分析粉末的晶体形貌。研究了溶液的pH、表面活性剂、煅烧温度等对纳米TiO_2颗粒尺寸的影响。结果表明:当溶液pH为2.0～4.0,分散剂质量分数为1.5％时,水解沉淀得到的TiO_2晶粒尺寸在10～20nm之间。研究烧结过程中晶粒的变化时发现:由于DBS的包覆,有效地抑制了煅烧过程中晶粒的长大。     

溶胶-乳化-凝胶法合成纳米TiO2颗粒尺寸影响因素研究

以钛酸丁酯为原料,通过溶胶-乳化-凝胶法合成了纳米TiO2粉末。探讨了表面活性剂浓度、溶胶的pH值、水含量对粒径的大小和粒度分布的影响。用XTEM对纳米二氧化钛粉体的形貌进行了分析。研究表明:当表面活性剂达到临界胶束浓度时颗粒尺寸较小且分布较均匀,当溶胶的pH值为8～9,水溶液浓度为0.5 mol/L时颗粒尺寸基本保持不变。在氮气气氛下,400℃煅烧可达到最好的实用效果。     

ZnO异质复合对纳米TiO2晶型转变和晶粒生长的影响

以TiCl4,ZnSO4溶液为原料,采用液相沉淀法制备了不同ZnO/TiO2摩尔比的纳米复合粉体.对合成的纳米复合晶的相变、晶粒生长过程以及紫外-可见光吸收性能进行了研究.结果表明:纳米TiO2经ZnO复合后,其晶型转变和晶粒生长均受到抑制.当ZnO为30%(摩尔分数)时,且采用氨水滴入TiCl4和ZnSO4溶液中的沉淀方式制备的ZnO/TiO2纳米复合晶的晶型转变和晶粒生长最缓慢.紫外-可见光吸收测试表明:800℃煅烧的ZnO/TiO2复合粉体的吸收强度比纯TiO2的高;900～1 050℃煅烧的复合粉体,虽然紫外区的吸收强度有所下降,但其光吸收带边比纯TiO2纳米晶的有显著红移.     

偏钛酸常温水解沉淀法制备纳米TiO2粉体的研究

以偏钛酸为原料通过常温水解-沉淀法制备了纳米TiO2粉体,用XRD和TEM等手段对粉体的晶型和形貌进行表征。用甲基橙为目标降解物,研究了其对甲基橙的降解性能,当分散剂加入量为13.5wt%,氨水溶液的pH值为4.0时得到的光催化剂粉体的晶粒尺寸均匀,粒径为10～20nm,其降解甲基橙的效率最高。     

低温制备金红石型纳米TiO2粉体

利用TiCl4低温水解法,添加TiO2溶胶制备了纳米TiO2粉体.用X射线衍射、透射电子显微镜和激光粒度仪研究了制备的纳米TiO2粉体的晶型、形貌、晶粒尺寸及粒径分布.结果表明:所得纳米TiO2粉体原始沉淀为金红石型,其粒径为10 nm左右的棒状粒子,经500℃煅烧2h,获得结晶完整、球形、粒径分布很窄的纳米TiO2粉体,其平均粒径为34 nm,粒径分布范围为20～50 nm.     

偏钛酸制备纳米TiO2粉体及其光催化性能研究

以偏钛酸为原料通过常温水解-沉淀法制备了纳米TiO2粉体,用XRD和TEM等手段对粉体的晶型和形貌进行表征,根据Scherrer方程计算得到晶粒尺寸与电镜照片结果吻合。用甲基橙为目标降解物,研究了其对甲基橙的降解性能,当分散剂加入质量分数为13.5%,氨水溶液的pH值为4.0时得到的光催化剂粉体的晶粒尺寸均匀,粒径为10—20 nm,降解甲基橙的效率最高。     

化学共沉淀法制备纳米氧化铝粉

以分析纯的硝酸铝和碳酸氢铵为主要原料，采用共沉淀法制备纳米氧化铝粉体，研究反应物的加料顺序和加料速度、表面活性剂种类、溶剂组成、晶种及前驱体的煅烧温度对产物的影响。采用X射线衍射仪分析粉体的物相组成，用谢乐公式计算晶粒尺寸，采用透射电子显微镜观测颗粒形貌。结果表明：原料的加料顺序对产物影响不明显，用PEG6000作表面活性剂，水和乙醇等体积混合液作溶剂，Al(NO₃)₃溶液直接倒入NH₄HCO₃溶液中制得前驱体，当煅烧温度为1135℃煅烧2 h时，制备了粒径为33 nm的α-Al₂O₃粉体，加入晶种后，煅烧温度可降低至1075℃。     

反应条件对氢氧化钇及氧化钇形貌的影响

以氨水和硝酸钇为原料制备氧化钇前驱体,考察表面活性剂及其用量对晶粒形貌和尺寸的影响;并在水热条件下研究体系pH、温度及时间对沉淀重整效果的影响.用XRD,SEM技术检测样品的晶型、尺寸和形貌.结果显示,阴离子型表面活性剂的浓度对一级晶粒的尺寸有较明显的影响,而阳离子型表面活性剂和非离子型表面活性剂的浓度对一级晶粒的尺寸的影响不明显.水热条件下对沉淀进行重整,可制备氢氧化钇纳米棒,溶液的碱浓度、温度及时间影响纳米棒的直径和长度.样品经600 ℃焙烧2 h,可制得立方晶相氧化钇,一级晶粒7～20 nm;氢氧化钇纳米棒焙烧后形成的氧化钇仍具有棒状结构.     

化学沉淀法制备纳米α-Al_2O_3粉体的研究

以Al(NO_3)_3和NH4HCO_3为主要原料,采用化学沉淀法制备纳米α-Al_2O_3粉末。研究了反应物的滴加顺序、滴定速度、溶剂中水与乙醇的体积比、表面活性剂及前驱体的煅烧温度和煅烧时间对纳米氧化铝粉体的晶粒尺寸和分散特性的影响,用XRD对粉末进行表征。结果表明,将硝酸铝溶液一次性加入到碳酸氢铵溶液中,可获得较小的纳米颗粒;反应体系中含有乙醇可以减轻团聚现象的产生。以PEG 6000为分散剂,硝酸铝与碳酸氢铵的物质的量之比为1∶8,采用将硝酸铝溶液一次性加入碳酸氢铵溶液的混合方式,溶剂中水与乙醇的体积比为1∶1的条件下制备的前驱体,在1135℃下煅烧2h,可获得平均晶粒尺寸为27.5 nm的纳米α-Al_2O_3粉末。     

TiO_2–ZnO复合薄膜的制备及光致双亲性能

采用溶胶-凝胶法制备了TiO2薄膜和ZnO掺杂的TiOr-ZnO复合薄膜.通过X射线衍射和原予力显微镜表征了样品的晶相、晶粒尺寸和形貌.以水(H2O)作为极性溶液参照物,苯(C6H6)作为非极性溶液参照物,研究了煅烧温度、煅烧时间、薄膜层数对薄膜光致双亲性的影响.结果表明:煅烧温度和煅烧时间的不同能够导致薄膜的晶粒粒径、晶型及薄膜表面的粗糙度发生变化.从页影响薄膜的双亲性能.当煅烧温度为550℃,煅烧时间 为2h,薄膜层数为3层时.TiO2由锐钛矿相向金红石转变,薄膜的双亲性最传.TiO2-ZnO复合薄膜的晶粒粒径约为25.2nm,薄膜表面粗糙度约1.815 nm,此时,亲水角和亲油角分别为5°和4°.ZnO掺杂的TiO2复合薄膜的双亲性明显高于纯TiO2薄膜.     

氢气纯度分析方法准确性的探讨

ONACCURACYOFANALYSISOFOFHYDROGEN1前言我公司目前应用的氢气纯度分析方法有两种,一种是爆炸反应法,另一种是焦性没食子酸吸收法。几年来,人们对两种分析方法的准确性曾有过褒贬不一的评论。这里我们也谈谈自己粗浅的观点。2爆炸法测定氢气纯度一定量的氢气样品与适量的空气之均匀混合物因反应后生成液体水而引起气体体积减少,减少的体积等于参加反应气体体积之和。其中l／3为氧气,2／3为氢气。根据氢气取样量和反应前后混气体体积之差,以及氢气在反应中的体积比例关系,可计算出样品的氢气纯度。计算公式式中：A一混…     

COMPARISON OF METHODS OF ANALYSIS OF GYPSUM1

The different analytical methods proposed for the evaluation of gypsum have been subjected to an experimental test. A combination method, consisting of a fusion with KHCO₃ and determination of CaO by KMnO₄ titration, the SO₃ by Andrews method of titration of BaCrO₄ has been found to give very reliable results with the least consumption of time.     

SEDIMENTATION OF BINARY MIXTURES OF PARTICLES OF UNEQUAL DENSITIES AND OF DIFFERENT SIZES

A model is developed for the sedimentation from a suspension of two particle species of unequal densities and of different sizes. The composition and the thickness of various layers in the sediments are predicted using graphical and analytical methods. The model predictions were in excellent agreement with experimental results, when the particle size ratio was ≥ 108. When size ratio of the particles was 2.60 and 4.31 the agreement occurred in about 50 percent of the cases.     

HEASUREHENT OF INSTANTANEOUS RATES OF LOSS OF VOIATILE COMPOUNDS DURING DRYING OF DROPS

A novel technique serves to monitor instantaneous rates of loss of a volatile solute from a suspended drop during drying. A highly sensitive electron capture detector is used to monitor concentrations of SF6 released into a flowing gas stream from a suspended, drying drop. Simultaneously, the appearance and morphological development of the drop are monitored with a video camera. This provides the wherewithal of relating instantaneous rates of loss of the volatile solute to particular events during the development of particle morphology.

Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology.     

茶多酚提取方法进展

本文综述了国内外现有茶多酚提取方法的现状以及近期的研究进展，并对其优缺点进行了评价。这将有助于中低档茶的综合利用和茶多酚的进一步开发应用。     

几种针状焦性能对比

针状焦分石油系和煤系两大类,这主要取决于针状焦的原料来源。在同一系列中由于原料不同和工艺条件不同 ,针状焦的各自性能也不相同。针状焦是生产超高功率石墨电极和高功率石墨电极的主要原料 ,针状焦的性能对石墨电极的质量有至关重要的影响。所以对针状焦性能以及其对石墨电极质量影响的研究十分必要的。以下是常用的几种进口针状焦和国产针状焦的性能对比。１原料性能分析对比原料试样包括４种针状焦 ,其中两种为进口针状焦：三菱针状焦和新日化针状焦;另两种为国产针状焦：鞍山针状焦和锦州针状焦。其中除锦州针状焦是石油系针状焦外…     

ANALYSIS OF RECENT MEASUREMENTS OF THE VISCOSITY OF GLASSES

Viscosity of Simple Soda-Silicate 500° to 1400°C Comparison of the results given by English with those of Washburn, Shelton and Libman, indicates a discrepancy in the absolute values of log₁₀ viscosity amounting to 0.6, those of Washburn et al., being relatively too high. If correction for this is made, the isothermal curves of log₁₀ viscosity as a function of soda content are smooth up to 50% Na₂O, showing no inflection. The observations as a function of temperature T are all represented within accidental error by an equation of the type where all three constants vary regularly with the composition. Change of Viscosity of Glass (6SiO₂, 2Na₂O) due to Molecular Substitution of CaO, MgO and Al₂O₃ for Na₂O The effect is clearly brought out by plotting (from the results of English) the change of log₁₀η due to the substitution as a function of temperature. The curves each show a sharp bend at a temperature between 840° and 1050°C, which is designated the aggregation temperature T_a. If we divide these curves by the corresponding percentage substituted, we get curves for each oxide which are straight and parallel below the aggregation temperatures, the slopes (increase of change of log₁₀η per 100°C) being −0.056 (CaO), −0.055 (MgO), −0.018 (A1₂O₃) per per cent oxide substituted. For substitution of 1/2 molecule the slopes are −0.325 (CaO), −0.23 (MgO) and −0.18 (Al₂O₃) per 100°. At the aggregation temperature the change of log₁₀η per per cent is a minimum, 0.03 to 0.06 for CaO, 0.12 for MgO, 0.07 for Al₂O₃. Evidence of Aggregation in Glasses, from viscosity Measurements The sharp bends in the plots of change of log₁₀η due to substitution of an oxide for Na₂O, suggest the beginning of molecular aggregation at these temperatures. These aggregation temperatures are close to the devitrification temperatures, but the effect on the viscosity curves cannot be due to actual devitrification since it does not change with time. Taking the aggregation temperatures as equal to devitrification temperatures, additional isotherms are roughly sketched into the equilibrium triangle of the system Na₂O-CaO-SiO₂. Change of Viscosity of Glass (4SiO₂, 2Na₂O) due to of Substitution of B₂O₃ for SiO₂ The change of log₁₀η (from the results of English) is plotted as a function of temperature, and also the change of log₁₀η per per cent B₂O₃. The curves are more complex than for the substitution for Na₂O.     

环氧树脂羟基值测定方法的研究

利用乙酸酐、吡啶和浓硫酸混合的乙酰化试剂测定环氧树脂中羟基值含量的方法具有操作简便、滴定终点明显和分析结果误差小等优点。     

骑式摩托车油箱喷涂工艺的改进

面对日益激烈的市场竞争,摩托车油箱外观质量越来越成为影响销售的因素之一。文章介绍了改进工艺后的油箱涂装,该涂装体系提高了油箱外观的丰满度,降低了油箱涂装的生产成本。     

聚酰亚胺的合成法

本文评述了缩聚型聚酰亚胺的主要合成方法和近年来国际上在合成中所做的探索。