Development of Agglomerated Talc. III. Comparisons of the Physical Properties of the Agglomerated Talc Prepared by Three Different Processing Methods

Agglomerated talc was prepared by the wet granulation method using a fluidized-bed granulator, a planetary mixer, and a high-speed, high-shear mixer. It was found that agglomerated talc produced by a fluidized-bed granulator is more porous, has a more irregular shape, has a lower bulk density, and has more binder-talc contacts. This higher surface area of binder-talc interface and the highly porous and irregular shape of the agglomerated talc produced by the fluidized- bed granulator result in stronger intergranular bonding. The resultant compact was harder. The compression force-time curve also showed that the time required to increase the upper punch force from 10% to 90% was greater for the compaction of the fluidized-bed granulated talc. The longer exposure to shear forces would enhance plastic flow and facilitate the formation of stronger bonds. Phenylpropanolamine HCl tablets containing 77.5 % agglomerated talc as the diluent were prepared. The properties of the tablet were found to be satisfactory. The agglomerated talc developed may be a promising direct compression diluent.     

Development of Agglomerated Talc. I. Evaluation of Fluidized Bed Granulation Parameters on the Physical Properties of Agglomerated Talc

Studies were conducted to develop agglomerated talc as a tablet diluent using the fluidized-bed granulation method. A complete 2³ factorial experiment was run using a Uniglatt fluidized bed granulator to determine the effects of atomizing air pressure (P), inlet air temperature (T), and the quantity of the granulating fluid (V) upon the characteristics of the resultant agglomerated talc. It was found that the atomization pressure was the most prevailing factor for controlling the growth of the agglomerates in the granulation process. With the decrease of the atomizing air pressure, the geometrical mean particle size and flowability of the agglomerates increased. The volume of the binder solution (dilution effect) affects the properties of the agglomerates in the same direction as did the atomizing air pressure. Droplet size distribution of the atomized binder solution was estimated. The result suggested that the dilution effect altered the properties of the product through its adhesivity. The flowability and hardness of talc were significantly improved by the fluidized bed granulation process.     

Development of Agglomerated Talc II: Optimization of the Processing Parameters for the Preparation of Granulated Talc

Agglomerated talc was prepared by the wet granulation method using a planetary mixer and a high speed mixer. The effect of the amount of water added and granulation time for the planetary mixer on the physical properties of the agglomerated talc were investigated by a response surface design. The speed of the agitator and granulation time for the high speed mixer were selected as the two independent variables to study the granulation processing using the same statistical design. Several characteristics of the product prepared by a planetary mixer or high speed mixer were well expressed as a quadratic function of the two independent variables studied in coded level. By superimposing contour plots of granule friability and percent fine of granule, a region was obtained where the requirements of friability and percent fines could be satisfied by controlling the processing variables. The optimal granulation condition was chosen from that region. The values of the measured responses of the agglomerated talc produced using the optimal granulation condition agreed well with the predicted values obtained from the regression equations.     

Electrical Properties of PbSnF4Materials Prepared by Different Methods

Data are presented on the electrical conductivity of fluorine ion conducting PbSnF₄solid electrolytes prepared by different methods—aqueous (precipitation from solution and hydrothermal synthesis) and nonaqueous (melt solidification).     

Effect of TiO2 Films Prepared by Different Methods on the Dye-sensitized Solar Cells' Properties

采用溶胶提拉法、粉末刮涂法以及将两种方法结合的混合涂覆法制备了TiO2薄膜,对不同工艺制备的TiO2薄膜进行了金相观察,并将薄膜组装成电池进行伏安曲线测试.Ⅰ-Ⅴ曲线表明,与溶胶提拉法和粉末刮涂法制备的TiO2薄膜相比,混合涂覆法综合了两者薄膜的结构优点,用此法制备出的TiO2薄膜组装成的染料敏化太阳能电池具有较大的光电流、光电压和最大输出功率.     

Evaluation of Binder Activities on the Physical Properties and Compression Characteristics of Granules Prepared by Two Different Modes

Abstract

The effects of various binders and binder concentrations in production of granules by two different granulation modes were first investigated on the basis of the granule size distribution. Increasing the amount of binder produced larger and less friable granules associated with a decrease in flow rate and an increase in angle of repose. The strength of granules prepared by either the wet conventional or the fluidized bed was a function of its mean particle diameter and of binder-content with the later factor being more predominant. The inclusion of paracetamol into the placebo formula decreased the granule crushing strength. The effect was more pronounced with smaller granules and decreased with increasing granule size.

The rank order of the paracetamol-PVP granules crushing strength was reversed for the tensile strength of their corresponding tablets, viz., the paracetamol-PVP tablets prepared from fluidized granulation exhibited a higher tensile strength than that compressed from wet granules. A new parameter index “ø_b index” which combines tablet characteristics is presented. The index proposed allowed an overall simpler quantitative evaluation of a binder activity. Incorporated into this index are four tablet parameters, viz., tensile strength, percent porosity, median dissolution time, and percent friability. A higher “ø_b, index” infers better physical properties of tablets. Binders used in this study are then classified according to this index: PVP > gelatin > PEG 6000.     

Effect of Processing on Microstructure and Physical Properties of Three Nickel‐Based Superalloys with Different Hardening Mechanisms

The nickel‐based superalloys Inconel alloy 600, Udimet alloy 720, and Inconel alloy 718 were produced by electron beam melting (EBM), casting, and directional solidification (DS). The distance between dendrites and the size of the precipitates indicated the difference in solidification rates between the three processes. In this study, the solidification rate was fastest with EBM, closely followed by casting, whereas it was much slower with DS. In the directional solidified materials the <100> direction was the fastest and thus, preferred growth direction. The EBM samples show a sharp (001)[100] texture in the building direction and in the two scanning directions of the electron beam. Macrosegregation was observed in some cast and directionally solidified samples, but not in the EBM samples. The melting temperatures are in good agreement with literature and the narrow melting interval of IN600 compare to UD720 and IN718 might reduce the risk of incipient melting during EBM processing. Porosity was observed in the EBM samples and the reasons are discussed. However, EBM seems to be a feasible process route to produce nickel‐based superalloys with well‐defined texture, no macrosegregation and a rapidly solidified microstructure.     

不同加工成形方法对银靶微观组织性能的影响

目的 研究锻造和轧制两种不同加工成形方法对银靶微观组织的影响,解决纯银靶材内部晶粒粗大、分布不均匀的问题。方法 采用锻造和轧制方法分别对纯银靶材铸锭进行加工,通过对微观组织的观察和测试分析,研究两种不同加工方法对银靶微观组织的影响。结果 锻造加工的纯银靶材致密性更好;轧制加工的纯银靶材在冒口处存在大量缺陷。锻造加工的纯银靶材晶粒细小且分布均匀;轧制加工的纯银靶材晶粒较粗大、分布均匀性差,存在部分粗大晶粒。锻造加工的纯银靶材硬度值(73HV0.05)明显高于轧制加工的纯银靶材(55HV0.05)。结论 在晶粒细化及分布均匀性方面,锻造比轧制加工纯银靶材更具优势。     

Differences in Characteristics of Pellets Prepared by Different Pelletization Methods

Pellets are currently a very popular dosage form for oral application. They can be prepared by several pelletization techniques. Extrusion/spheronization, commonly used in the pharmaceutical industry, and modern agglomeration in a rotoprocessor were the methods chosen for pellet preparation in our study. Theophylline (in 10% to 65% concentration) was the model drug, lactose monohydrate was used as filler, microcrystalline cellulose Avicel® PH 101 was thespheronization enhancer, and the wetting agent was purified water. Both techniques led to the formation of pellets of appropriate shape and mechanical properties. Pellets of a higher density, hardness, lower friability, and slightly slower dissolution profiles were obtained by extrusion/spheronization. This method of pelletization also led to production of particles with narrower size distribution and bigger yield of pellets with the requested size.     

Plastic Deformation of Nano-TiO2 Ceramics Prepared by Different Methods

1.IlltroductionThestudyofthesuperplasticdeformationofsub-micrograinceramicshasgotgreatprogress,buttheoperatingtemperatureswerestiIltoohigh(atleastabove1loo'C)forpracticalapplication[1].Inordertolowerthetemperatureofsuperplasticdeformationofceramics,onepossiblestepisusingthenanometerparticlesasstartingmaterialstomakenanograince-ramics.Soinrecentyearsthestudyofsuperplasticdeformationofnanograinceramicshasattractedmoreandmoreattention.Karcheta1.firstreportedtheductilityofunsillterednano-ceramics…     

不同聚合方法对AM/MADQUAT共聚物序列分布的影响

采用溶液聚合和反相微乳液聚合两种方法对丙烯酰胺(AM)、(2-甲基丙烯酰氧乙基)三甲基氯化铵(MADQUAT)在较低单体浓度下进行共聚合。计算得出两种方法中单体AM、MADQUAT的竞聚率,溶液中rAM=0.30,rMADQUAT=1.31;微乳液中rAM=0.63,rMADQUAT=1.12。并用测得的竞聚率数据,通过计算机程序计算了共聚物的瞬时组成、平均组成,在研究溶液和微乳液中共聚物的组成及序列分布的差异时,发现微乳液聚合得到的聚合物的平均组成更均一。     

Evaluation of Batch-To-Batch and Manufacturer-To-Manufacturer Variability in the Physical Properties of Talc and Stearic Acid

Magnesium stearate, talc and stearic acid are commonly used as lubricants in tablet formulations. Many studies on the batch-to-batch and manufacturer-to-manufacturer variability in the physical properties and lubricity of magnesium stearate have been reported in the literature. However, very few similar studies have been reported on talc or stearic acid. In this study, physical properties such as particle size, specific surface area, thermal behavior, moisture content, density, and particle shape and morphology of talc and stearic acid batches obtained from several manufacturers were examined. There was little batch-to-batch variability observed in the talc and stearic acid batches obtained from various manufacturers; however, differences in the particle size and specific surface area were seen in the two types of talc, USP samples obtained from one manufacturer. The scanning electron microscope photomicrographs of the stearic acid samples obtained from various manufacturers also showed some differences in the amount of flakes attached to the spherical particles.     

Evaluation of Batch-To-Batch and Manufacturer-To-Manufacturer Variability in the Physical Properties of Talc and Stearic Acid

Abstract

Magnesium stearate, talc and stearic acid are commonly used as lubricants in tablet formulations. Many studies on the batch-to-batch and manufacturer-to-manufacturer variability in the physical properties and lubricity of magnesium stearate have been reported in the literature. However, very few similar studies have been reported on talc or stearic acid. In this study, physical properties such as particle size, specific surface area, thermal behavior, moisture content, density, and particle shape and morphology of talc and stearic acid batches obtained from several manufacturers were examined. There was little batch-to-batch variability observed in the talc and stearic acid batches obtained from various manufacturers; however, differences in the particle size and specific surface area were seen in the two types of talc, USP samples obtained from one manufacturer. The scanning electron microscope photomicrographs of the stearic acid samples obtained from various manufacturers also showed some differences in the amount of flakes attached to the spherical particles.     

化学法合成莫来石粉料研究进展

对化学法制备莫来石粉料的研究现状进行了系统的总结，阐述了低温莫来石化的机理，从致密化和晶化的角度分析了化学法制备莫来石先驱体粉料的优缺点，提出了化学法尚需解决的问题。     

Comparative Study of Dense Bulk MgB2 Materials Prepared by Different Methods

We report on the results of a comparative investigation of highly dense bulk MgB₂ samples prepared by three methods: (i) hot deformation; (ii) high pressure sintering; and (iii) mechanical alloying of Mg and B powders with subsequent hot compaction. All types of samples were studied by AC susceptibility, DC magnetization, and resistivity measurements in magnetic fields up to μ₀ H = 160 kOe. A small but distinct anisotropy of the upper critical field $\psi {\rm H}_{c2}^{\alpha ,b} /H_{c2}^c \sim 1.2$ connected with some texture of MgB₂ grains was found for the hot deformed samples. The samples prepared by high pressure sintering as well as by mechanical alloying show improved superconducting properties, including high upper critical fields H _c2 (μ₀ H _c2 (0) ～ 23 T), irreversibility fields H _irr which are strongly shifted towards higher values H _irr(T) ～ 0.8 H _c2(T) and high critical current J _c (J _c = 10⁵ A/cm² at 20 K and 1 T).     

工艺参数对熔盐法合成铌酸锶钡粉体的影响

研究了工艺参数对熔盐法制备铌酸锶钡粉体晶粒尺寸和形貌的影响。发现合成温度、反应时间及盐的用量能较显著地影响晶粒的形貌和尺寸。在以K2SO4为熔盐中,晶粒随着温度的升高而增大,当盐料比大于1时,随着盐料比的增加合成晶粒尺寸增大。在1300℃时,重点讨论了不同反应时间所合成粉体--的形貌和尺寸大小差异。随着反应时间反应延长,晶体的各向异性先增大后减小,而所合成粉体的物相组成并未发生变化。     

Comparisons of the Microstructure and Magnetic Properties of Anisotropic NdFeB Magnets Prepared by Hot Pressing and Spark Plasma Sintering

Journal of Superconductivity and Novel Magnetism - NdFeB hot-pressed and hot-deformed magnets were prepared by hot-pressed (HP) sintering and spark plasma sintering (SPS). The effects of sintering...     

溶胶-凝胶法制备生物微晶玻璃的研究进展

溶胶-凝胶法是一种材料合成新工艺,现已广泛用作生物植入体、组织工程支架及药物载体的生物活性玻璃粉体、块体玻璃、多孔生物微晶玻璃与涂层的制备.简要介绍了溶胺-凝胶法制备生物微晶玻璃的工艺原理和优缺点,着重分析了其研究和应用现状,并阐述了其发展前景.     

Influence of Annealing on Physical Properties of CdO Thin Films Prepared by SILAR Method

Cadmium oxide (CdO) thin films were prepared by successive ionic layer adsorption and reaction (SILAR) method and annealed at 250-450℃ for 2 h. The prepared films were characterized by X-ray diffraction (XRD), optical spectroscopy, scanning electron microscopy (SEM) and Hall effect measurement. The XRD analysis reveals that the films were polycrystalline with cubic structure. Both crystallinity and the grain size were found to increase with increasing annealing temperature. SEM analysis shows the porous nature of the surface with spherical nanoclusters. Energy dispersive spectroscopic analysis (EDS) confirmed the presence of Cd and O elements without any additional impurities. The films exhibited maximum transmittance (82%-86%) in infra-red (IR) region. Transmittance was found to decrease with increasing annealing temperature and the estimated band gap energy (Eg) was in the range of 2.24-2.44 eV. Hall effect measurement shows an increase in carrier concentration and a decrease in resistivity with increasing annealing temperature. The carrier concentration (N) and resistivity (ρ) of about 1.26×1022 cm-3 and 8.71×10-3Ω cm are achieved for the film annealed at 450℃for 2 h.     

The Magnetic and Structural Properties of SiC-Doped MgB2 Bulks Prepared by the Standard Ceramic Processing

According to general formula MgB_2?x SiC _x (x=0,0.05,0.1,0.2), MgB₂ and SiC-doped bulk superconductors were prepared by the standard ceramic processing. The mixtures of the corresponding powders were sintered at 750?°C for 0.5 h under pressure of 8 bar Argon. X-ray diffraction patterns show that all the samples have MgB₂ as the main phase with a very small amount of MgO; further, with SiC-doped, the presence of Mg₂Si is also noted. The magnetization-temperature measurements showed a transition temperature of 37.5 K for the undoped sample which indicates the typical transition temperature of MgB₂. When the content of SiC increased in the sample, the transition temperatures decreased to the lower temperatures systematically. The M?CH loops measured using a VSM showed very large magnetization value at low temperature for SiC doped samples. The largest M?CH loops were taken from the sample contains 5% SiC. The critical current density of samples calculated from M?CH loops indicated a value of around 4×10⁵ A/cm², which is in good agreement with the literature.