大气中金属阴极保护用-Al2O3粉体材料的制备与性质

研究了β－Ａｌ_２Ｏ_３粉体材料的制备工艺与性质,这种粉体材料可以采用慢速升温、分 阶段保温的工艺,煅烧Ｌｉ_２ＣＯ_３、Ｎａ_２ＣＯ_３和Ａｌ_２Ｏ_３的均匀混合物不经球磨直接制得．根据使用要求与生产条件,混合物可用干混、半湿混－过筛或喷雾干燥法来制备．粉体材料主要由β／β~＂－Ａｌ_２Ｏ_３组成,β~＂相的相对含量＞７０％,加入适当的粘结剂与溶剂,可将其制成大气环境 中金属管道外的固体电解质涂层．涂层中粉体的化学与电化学性能稳定,其阴极极化曲线有明显的平坦区,可用于阴极保护技术．     

电子雷管用电子控制模块的抗冲击性能研究

针对小断面爆破时电子雷管内电子控制模块易受冲击作用失效的问题,通过钢桶冲击实验,对工作状态的电子控制模块及其核心部件分别进行抗冲击性能研究。结果表明,电子控制模块受冲击作用后,相比于物理结构损坏,易出现内部储能电容失电现象。电子雷管用储能电容受冲击失电是固有特性。储能电容受冲击失电性能由强到弱的顺序为：固态铝电解电容、电解铝电容、固态钽电容。储能电容受冲击失电量与电容类型、受冲击强度以及管壳内部防护结构的设计相关。设计的钢桶冲击实验方案能定性研究电子控制模块及内部元器件的抗冲击性能,可用于生产实践中对雷管结构设计和元器件进行筛选,从根本上控制产品质量。     

铌电解电容器研究动态

铌电解电容器具有比铝电解电容器优越的性能,而价格比钽电解电容器便宜,在电解电容器领域颇有发展前途.综述了近年来国内外电容器用高比容铌粉和铌电解电容器最新研究发展动态、性能、制造方法及市场前景.     

酚醛树脂乳液的合成及在摩擦材料中的应用

:讨论了乳化剂用量对酚醛树脂乳液性能的影响 ,通过干燥工艺的研究和摩擦材料性能的比较表明 ,酚醛树脂乳液用于湿式摩擦材料是可行的     

世界钽粉生产工艺的发展

论述了国内外电容器级高压钽粉、中压钽粉、高比容钽粉的生产工艺发展过程。在钽粉生产工艺发展过程中,各种先进的装备被应用,各钽粉生产厂家围绕着钽粉比容的提高,杂质含量的降低,物理性能的优化等综合性能的改善,不断开发出新工艺、新技术,使钽粉适应并推动着钽电容器的发展。     

电容器级钽粉关键技术与开发研究

引述了Ta电容器与Al电容器、多层陶瓷电容器相比突出的性能与应用特征，分析了Ta电容器片式化、小型化促进电容器级Ta粉高比容化发展的新趋势，叙述了航空、航天和军工领域对高压电容器高可靠性能的需求，以及对中高压Ta粉向更高电压、更低SER方向发展的引领，回顾了电容器用高比容Ta粉、中高压Ta粉发展应用进程，介绍了经典氟钽酸钾（K2TaF7）金属Na还原法、电子束熔炼法、球磨片式化法生产的高比容Ta粉、高压Ta粉、中压（片状）Ta粉的性能、产品品级及关键技术，分析了30～80kμFV／gTa粉耐压性能影响因素，介绍了Ta粉高比容化、高压化新技术、装置、产品形貌、性能及优缺点，在此基础上提出了电容器级Ta粉高比容化、高压化创新进步的思路。     

Effect of Binder Concentration and Method of Addition on Granule Growth in a High Intensity Mixer

A model system consisting of microcrystalline cellulose and povidone was used to study the effect of binder concentration and method of addition on granule growth in a high intensity mixer. The methods of binder addition include blending the dry binder with the excipient prior to granulating with water and granulation of the excipient with an aqueous solution of the binder. When the binder was dry-mixed with excipient prior to wetting, a good correlation was obtained between granule size and binder level. The growth of granules prepared by this method also appears to be related to the mechanical “resistance” encountered by the mixing blade during wet massing. In general, granules prepared by the addition of aqueous binder solutions are smaller than granules prepared with corresponding concentrations of dry binder and demonstrate a lesser degree of granule growth with respect to increasing binder level. For the wet addition method, the mechanical resistance was found to be essentially constant with respect to binder level.     

石墨含量对铜-石墨-乳化沥青复合材料组织和性能的影响

以电解铜粉与石墨粉为原料,阴离子乳化沥青为粘结剂,采用粉末冶金技术制备了铜-石墨-乳化沥青复合材料,并通过XRD、EDS和SEM对石墨含量为2wt%~8wt%的铜-石墨-乳化沥青复合材料微观组织进行表征,研究了铜-石墨-乳化沥青复合材料的摩擦磨损性能、力学和电学性能,并与不含乳化沥青的铜-石墨复合材料进行比较。结果表明,乳化沥青可以有效防止石墨颗粒的聚集,对石墨和铜基体起粘结作用;在两相界面处几乎没有间隙,并且产生了层片状石墨;石墨含量为4wt%的试样磨损量最小,仅为0.0049 g,摩擦系数约为0.025;增加载荷和石墨含量会增大磨损量,但会降低摩擦系数;在滑动摩擦期间,磨损表面会出现裂纹、犁沟、凹陷、小颗粒和层片状结构,但其程度要比不含乳化沥青的复合材料低。      

Effect of Binder Concentration and Method of Addition on Granule Growth in a High Intensity Mixer

Abstract

A model system consisting of microcrystalline cellulose and povidone was used to study the effect of binder concentration and method of addition on granule growth in a high intensity mixer. The methods of binder addition include blending the dry binder with the excipient prior to granulating with water and granulation of the excipient with an aqueous solution of the binder. When the binder was dry-mixed with excipient prior to wetting, a good correlation was obtained between granule size and binder level. The growth of granules prepared by this method also appears to be related to the mechanical “resistance” encountered by the mixing blade during wet massing. In general, granules prepared by the addition of aqueous binder solutions are smaller than granules prepared with corresponding concentrations of dry binder and demonstrate a lesser degree of granule growth with respect to increasing binder level. For the wet addition method, the mechanical resistance was found to be essentially constant with respect to binder level.     

Optimal Massing Liquid Volume Determination by Energy Consumption Measurement: Study of the Influence of Some Physical Properties of Solvents and Products Used

This study tried to investigate, by the power comsumption technique, the influence of the powder's and solvent's properties on wet granulation.

It could be shown that the required amount of granulation liquid decreases when the particle size of the powder to be granulated increases. This relationship is however only true when the particle size distribution of the powder to be granulated is rather narrow.

Powders having the same solubility in different solvents require the same optimal liquid quantity for granulation, but the properties of resulting granules depend on surface tension and wetting properties of the solvent.

When the powder to be granulated contains crystallisation water, the temperature rising in the mixer can be sufficient to liberate this water, which must be taken into account in the optimal granulation liquid requirement.

The effect of a macromolecular binder (PVP, HPMC) has also been studied: the optimal liquid quantity required changes with the kind of binder used and the manufacturing process (binder used in solution or added as dry powder).

It was also shown that in the case of lactose, the optimal quantity of PVP or HPMC can be determined from the power consumption records and from the granules friability studies     

Comparison of Moisture-Activated Dry Granulation Profess with Conventional Granulation Methods for Sematilide Hydrochloride Tablets

During the development of a tablet formulation of a cohesive, fluffy investigational drug, a novel moisture-activated dry granulation (MADG) process was studied in comparison with two conventional granulation methods, i.e., wet granulation and dry granulation with a roller compactor, as well as with a direct compression formulation method. The MADG method produced granules with excellent flowability which were equivalent in a number of ways to those produced by either conventional wet granulation or dry granulation methods and which were much better than the powder blend from the direct compression formulation. The tablets prepared using the MADG method had better content uniformity than those made using material from wet and dry granulation processes. Other tablet properties, such as weight variation, friability and dissolution, were similar among the tablets produced by the four processes     

Optimal Massing Liquid Volume Determination by Energy Consumption Measurement: Study of the Influence of Some Physical Properties of Solvents and Products Used

Abstract

This study tried to investigate, by the power comsumption technique, the influence of the powder's and solvent's properties on wet granulation.

It could be shown that the required amount of granulation liquid decreases when the particle size of the powder to be granulated increases. This relationship is however only true when the particle size distribution of the powder to be granulated is rather narrow.

Powders having the same solubility in different solvents require the same optimal liquid quantity for granulation, but the properties of resulting granules depend on surface tension and wetting properties of the solvent.

When the powder to be granulated contains crystallisation water, the temperature rising in the mixer can be sufficient to liberate this water, which must be taken into account in the optimal granulation liquid requirement.

The effect of a macromolecular binder (PVP, HPMC) has also been studied: the optimal liquid quantity required changes with the kind of binder used and the manufacturing process (binder used in solution or added as dry powder).

It was also shown that in the case of lactose, the optimal quantity of PVP or HPMC can be determined from the power consumption records and from the granules friability studies     

Synthesis of compositionally homogeneous Pb(ZrxTi1−x)1−y(Mg1/3Ta2/3)yO3 by wet–dry combination method and its dielectric properties

Ternary perovskite-type solid solutions of Pb(Zr_xTi_1−x)_1−y(Mg_1/3Ta_2/3)_yO₃ (PZTMT) were synthesized by a wet–dry combination method in which a coprecipitation process was applied to B-site cations (Zr⁴⁺, Ti⁴⁺, Mg²⁺ and Ta⁵⁺). The compositional homogeneity in calcined powders and dielectric properties of sintered ceramics were investigated. The powder X-ray diffraction analysis revealed that PZTMT powders prepared by the wet–dry combination method had no compositional fluctuation unlike that prepared by a conventional dry method. The sintered PZTMT prepared by the wet–dry combination method exhibited much higher dielectric constant than that prepared by the conventional dry method. The improvement of the compositional homogeneity and the density led to the improvement of the dielectric properties.     

基于高比容钽粉的聚合物片式电容器制备工艺研究

针对比容为50000～70000μF.V/g的较高比容钽粉,研究了导电聚合物聚3,4-乙烯基二氧噻吩(PE-DOT)作为阴极材料的有机片式固体钽电解电容器的制备工艺,通过调整阳极体制备及阴极被覆工艺等参数实现了PEDOT在高比容钽块表面的有效被覆,获得了各项性能参数良好的聚合物片式钽电解电容器。重点研究了压制密度、形成电流密度等参数及分段被膜工艺对聚合物片式固体钽电容器容量引出、等效串联电阻、漏电流等性能的影响,并讨论了相应的电容器工作机理。     

Special Features in Powder Preparation, Pressing, and Sintering of Uranium Dioxide

Nuclear ceramic grade UO₂ powders are usually prepared by the wet chemical ammonium diuranate route. The powders are pressed and sintered before incorporation into nuclear fuel assemblies. The processing is complex at all stages and the specifications are stringent. In powder preparation, slow addition of the precipitating reagent at a low temperature is recommended. The conditions for the drying of the precipitate, calcination and reduction are chosen to result in an agglomerate free, fine and porous powder that does not require milling or binder addition and is capable of being compacted and sintered to desired density with a homogeneous microstructure. The pressing conditions are chosen to give compacts that are free from defects such as cracking, chipping and end-capping. Sintering conditions are such that desintering, bloating, weathering and nitriding are avoided. Some insights that have been gained in powder preparation, pressing and sintering are presented in this paper. The relationship between powder characteristics and pressing and sintering properties is described.     

Ta-Ta2O5-电解液导电体系界面特性的实验研究

分析了阀金属钽氧化膜的形成过程,伏安特性测试结果表明Ta-Ta2O5-电解液体系具有单向导电性.电场作用下,电解液中O2-跃过氧化膜/电解液界面,在氧化膜中形成定向迁移,同时引发膜内二次电子场助发射是该体系的主要导电机理.实验表明,大量二次电子导致介质膜雪崩式击穿是该体系闪火的主要原因,在电解液中添加适量有机物,可以屏蔽O2-使电解液的闪火电压提高30V以上,从而提高液体钽电解电容器的性能.     

Aerodynamic dispersion of cohesive powders: A review of understanding and technology

Dispersion is the desired disintegration of particle clusters down to their primary constituents through the application of external forces, which overcome the interparticle attraction forces. This method is beneficial for many processes but especially for the characterisation of particulate systems and therapeutic drug delivery via the lungs from dry powder inhalers (DPIs). Dry powder dispersion is becoming increasingly popular as a method of sample preparation for a range of instruments such as a laser diffraction measurement device. There are many advantages for dry dispersion compared to wet methods. However, complete dispersion of fine cohesive powders is difficult due to the relatively large interparticle attraction forces compared to separating forces arising from fluid energy. This review identifies the current state of theoretical and experimental understanding of powder dispersing in a gaseous medium. The approaches to relate bulk powder properties to dispersion, the stresses produced on a particulate structure due to aerodynamic forces and possible approaches for linking the two are discussed. Furthermore, the available dispersion technology is reviewed with a discussion of individual dispersers and commercial devices used for dispersing bulk powder. Also, the review highlights the research needed in this field to gain a better understanding of how bulk powders interact with a dispersing fluid.     

Improving strength development of wastepaper sludge ash by wet-milling

Wastepaper sludge ash (WSA) requires relatively higher proportions of water than Portland cement (PC) when used as a single binder. This high water demand may be reduced by the addition of secondary binders such as ground granulated blastfurnace slag (GGBS), which improves the hydration properties of the mixes. Based on the already determined physico-chemical properties of WSA a new method of paste preparation is introduced which also enhances the cementitious properties of WSA. The method utilises a wet-grinding stage prior to mixing. Pre-treatment of WSA prior to the addition of GGBS enhances effectively the strength development of the blended binder. Higher compressive strengths are obtained for the paste cube samples made using the new method of paste preparation than those achieved by conventional dry mixing methods.     

Preparation of porous scaffold from hydroxyapatite powders

Hydroxyapatite (HA) powder was prepared by wet chemical method. The hydroxyapatite phase was stable up to 1250 °C without decomposition to beta-tricalcium phosphate. Interconnected porous hydroxyapatite scaffold resembling trabecular bone structure was developed from polymeric replica sponge method. The prepared scaffold has 60 vol.% porosity having a major fraction of ~ 50–125 μm pore diameter. The pore content, pore morphology, pore interconnectivity of scaffold and their compressive strength were dependent on the solid loading and binder content. In-vitro bioactivity and bioresorbability confirmed the feasibility of the developed scaffolds.     

用富勒烯残余烟灰制备炭分离膜的初步研究

以富勒烯残余烟灰为原料,采用粘结成型炭化法制备出炭分离膜,目的在于考察富勒烯残余烟灰的有效利用途径。实验结果表明,富勒烯残余烟灰可以用来制备炭分离膜,制备工艺条件对膜性能有较大影响。