水铝石热分解的晶体形貌

借助场发射扫描电子显微镜和X射线衍射分析研究了水铝石在不同温度分解后的形貌特征。研究表明：铝土矿中水铝石晶体呈短柱状、粒状,晶粒尺寸小于30gm;经500℃,3h受热后该水铝石晶体形状基本不变,而此时已转化为α-A1203,被称为水铝石假象;700℃,3h受热后晶体开裂成更小的柱状;温度升高至1000℃恒温3h后可辨识...     

Transformation Mechanism of the Dehydration of Diaspore

The dehydration of diaspore to corundum was investigated by means of X-ray powder diffraction at reaction temperatures (400° and 600°C) as well as by transmission electron microscopy (TEM). The TEM studies were performed at the reaction interface of partially dehydrated natural diaspore crystals. The corundum produced consisted of thin dense regions which were separated by nanometer-sized pores forming lamellae with a periodicity of 3.7 nm. At the reaction front a transition phase (D') could be detected in electron diffraction patterns. The phase D' is isotypic to diaspore, but with a larger spacing of the close-packed (100) oxygen planes ( a _D' from 0.475 to 0.480 nm). The expansion with respect to diaspore is explained by breaking of the hydrogen bonds of diaspore, considered to be the initial step of the transformation. The spacing of the lamellar pore system in corundum is explained by the misfit of the (100) planes of D' and the (0003) planes of corundum. We conclude that at well-fitting regions of the closed-packed planes at the D'/C interface, dense corundum is formed, while at misfitting regions, the formation of corundum is not favored and the pores are produced. Hence, the transformation of the solid phases takes place as a two-step process, i.e., D → D'→ C.     

颜料的分散

介绍了颜料分散的一般过程,稳定机理与分散效果的鉴别。     

微波焙烧对一水硬铝石矿浸出性能的影响

研究了微波焙烧对一水硬铝石矿浸出性能的影响. 考察了微波辐射温度、微波辐射时间对矿物浸出性能的影响,在此基础上,对微波焙烧预处理的机理作了进一步的探讨. 结果表明,微波焙烧能够显著提高氧化铝的浸出率,降低浸出液的分子比. 微波焙烧在微波辐射温度为535℃、辐射时间为5 min时达到了最佳的效果. 微波辐射温度过高会造成矿物烧结,影响浸出效果. 延长微波辐射时间对浸出效果影响不大.     

电流变体的分散介质

简要介绍了电流变体中各种分散介质 ,包括无机化合物、高分子化合物 (天然高分子、高分子电解质和高分子半导体 )、液晶及复合型材料 ,并指出了分散介质在研究过程中应注意的问题     

纤维级二氧化钛分散性能分析

综述了纤维级二氧化钛的性能 ,介绍了影响二氧化钛分散性的各种因素及机理 ,详细分析了二氧化钛在实际生产中的应用     

Dispersing (Deflocculating) Aluminas

The rheological properties of aqueous suspensions of a reactive alumina and high-alumina cements have been studied, and a method for evaluating the thinning effect due to agents used to deflocculate ceramic casting systems has been developed; a classification of thinning agents is proposed. Alumina dispersants make it possible to decrease the moisture content of Al₂O₃ suspensions by 50 – 60 rel.% and increase their volume concentration from 0.50 to 0.65. The characteristics of dispersing aluminas used for the thinning (deflocculation) of new refractory castables containing Al₂O₃ (76 – 96%) and organic deflocculants are given. Suspensions based on four types of dispersants (with a moisture content of 19 – 25%) exhibiting a thixotropic flow behavior are considered.     

颜料在水性介质中的分散

叙述了在水性涂料中颜料的分散情况。     

The Selective Thinning Effect of Dispersing Aluminas

The results of a study of the thinning efficiency of dispersants of four types applied to a concentrated suspension of high-alumina cement, reactive aluminas, spinel, and complex mixtures are reported. The thinning effect is controlled by the chemical nature (composition) of the suspension's solid phase and may differ quite significantly from dispersant to dispersant.     

Dispersing hairy nanoparticles in polymer melts

The dispersion of hairy nanoparticles in polymer melts of chemically identical chains was investigated as a function of both molecular weight and volume fraction. Here we provide conclusive evidence that the shape of the phase diagram is determined primarily by the ratio of the chain length of the polymer melt to the chain length of the polymeric shell structure (or hair) of the core/shell nanoparticles, and that the phase behavior of different hairy particles in various polymer melts can be superimposed into one universal graph. Other factors, including the hair density and the particle diameter, are not nearly as significant as the above-noted ratio in this phase separation. In addition, we show that there is a strong connection between the rheological dynamics of the particle-filled system and the thermodynamics of the phase separation behavior. The shear-induced nonlinearity in the particle-filled system appears to display features of a singularity near the phase transition point.     

二氧化钛在涂料中的分散技术进展

二氧化钛具有优异的光散射能力,其折射率也几乎是颜料中最出色的。但由于二氧化钛的表面物理化学性质以及涂料体系的复杂性使二氧化钛在涂料中并非均匀地分布,从而导致二氧化钛的遮盖效率降低。从二氧化钛的表面改性以及二氧化钛的阻隔分散两个方面综述了二氧化钛在涂料中的分散技术进展。     

丹尼尔流动点和分散剂的选择

介绍了丹尼尔流动点的测定方法及其在分散剂选择上的应用。     

氟碳涂料分散性能的研究

以氟碳树脂为基料,制得了具有优异分散稳定性能的氟碳涂料。研究了不同分散剂、湿润剂对氟碳涂料分散性能的影响,通过SEM、IR、分子量分布对氟碳涂料进行了表征。结果表明:当选用3#聚氨酯高分子分散剂和湿润剂A时,氟碳面漆有较好的分散稳定性能,涂膜表面无浮色发花现象,常温贮存12个月后仍具有良好抗浮色发花性能。     

Novel Condensed Ring Carboxylic Hydroxamic Acid Studied in the Flotation Behavior of Diaspore and Aluminosilicates

Flotation reagents are the critical technique in the flotation separation process for desilication. Aimed at the highly selective reagent for direct flotation of diasporic bauxite, a novel compound, dibenzo-1-(7-carboxyl-4-hydroxyl bicycle [2.2.2] octan-7,8-diyl) carboxamic acid (DBCA) with two functional groups carboxyl and hydroxamate in the same molecule, was synthesized through Diels-Alder reaction followed by oximation reaction. Subsequently, the floatability of diaspore, kaolinite, and illite was measured by using DBCA as a collector, the interaction mechanism between minerals and DBCA was investigated through zeta potential measurements and FT-IR spectrum, and the structure and property relationship of the collector were also discussed. The flotation experimental results showed that DBCA had a very strong collecting ability for diaspore, while poor activity was observed for kaolinite and illite. The interaction of DBCA on diaspore surfaces may be mainly dominated by chemical bonding as the formation of three chelation rings; however, those on the surfaces of kaolinite and illite are mainly hydrogen bonding or physical adsorption. Consequently, it is possible to separate diaspore from such aluminosilicates as kaolinte and illite employing DBCA as a collector.     

Quantification of Invertase Activity in Ants Under Field Conditions

Invertases (EC 3.2.1.26) are hydrolases that cleave sucrose into the monosacccharides, glucose, and fructose. They play a central role in carbohydrate metabolism of plants and animals. Methods presented so far to quantify invertase activity in ants or other animals have been hampered by the variability in both substrates and products of the enzymatic reaction in animals whose carbohydrate metabolism is highly active. Our method is based on a spectrophotometric quantification of the kinetics of glucose release. We first obtained an equilibrium state summarizing reactions of any carbohydrates and enzymes that are present in the extract. Sucrose was then added to quantify invertase activity as newly released glucose. Invertase activities differed significantly among species of ants. Variances were lowest among individuals from the same colony and highest among different species. When preparations were made from ants of the same species, invertase activity was linearly related to the number of ants used for extraction. Our method does not require ants to be kept on specific substrates prior to the experiment, or expensive or large equipment. It, thus, appears suitable for dealing with a broad range of physiological, ecological, and evolutionary questions.