喷气纺纱机纺制Tencel纱的工艺实践

为了提高喷气纱产品档次与附加值,充分利用新型纤维纺制了Tencel 14.8 tex、HLF Lyocell 14 tex 及Tencel/C 14 tex喷气纱.介绍了喷气纱的特点以及针对原料特性纺纱时各工序采取的工艺技术措施.     

Improvement of thickness uniformity in nickel electroforming for the LIGA process

An effective method to improve thickness uniformity in nickel electroforming for the LIGA process to produce metallic microstructures is described. The deposited metal distribution is naturally a concave shape over the whole area of the plating base proved by experiments. The edge thickness of the plating area is usually twice or higher than the center of the plating area. A secondary cathode (guard ring) was applied to improve the electroform uniformity. The experimental result of a Joule–Thomson micro-cooler proved its feasibility. The thickness ratio of edge to center of a 500 μm sample decreased from 2.5 to 1.4. The thickness uniformity improvement is achieved without a loss in plating rate in the center of the features.     

电铸铜工艺与景观雕塑制作的相关性研究

通过正交试验研究了工艺参数对铸铜层性能的影响。结果表明:电铸铜工艺在景观雕塑制作领域有其独特优势。依据景观雕塑使用条件,在保证铸铜层硬度的前提下,确定了硫酸铜240g/L、硫酸60g/L、电流密度4A/dm~2、温度20℃为最佳的电铸铜工艺条件;在保证铸铜层拉伸强度的前提下,确定了硫酸铜220g/L、硫酸70g/L、电流密度6A/dm~2、温度20℃或30℃为最佳的电铸铜工艺条件;控制电流密度在6A/dm~2左右,铸铜层的硬度与拉伸强度良好。     

喷射式并流填料塔板流体力学和传质性能

提出一种新型高效塔板——喷射式并流填料塔板（ＪＣＰＴ），介绍１２００ｍｍ冷模塔流体力学实验结果和２００ｍｍ热模塔传质效率，给出了适用于工业设计性能参数的计算关联式。通过与新垂直筛板（ＮＶＳＴ）的比较表明，ＪＣＰＴ具有雾沫夹带小、处理能力大、塔板效率高等特点，是一种具有广泛应用前景的新型高效塔板。     

Permeability of soft porous media under one-dimensional compaction

A novel experimental approach to measure permeability of porous material samples under variable longitudinal compaction has been developed. The material has a non-linear structural behavior and exhibits a small hysteresis during mechanical loading and unloading experiments. The new permeameter includes a piston moving inside a Plexiglas cylinder with controllable speed and a test section where the porous material sample is placed under compaction by two grids with adjustable positions. Time-dependent pressure was recorded at four different locations along the sample together with the velocity of the piston. Experiments with two different sample lengths have been performed at three different Reynolds numbers based on the apparatus diameter. The results show that pressure gradient and permeability data do not depend on initial uncompacted sample length. All experiments included measurements at various compaction ratios of the material followed by measurements during relaxation/expansion of the material. No hysteresis was observed in the pressure gradient and permeability data during compaction and expansion of the material for a wide range of compaction ratio. The effects of small velocity fluctuations due to variable friction of the moving piston with cylinder’s wall were also considered. These velocity fluctuations cause pressure fluctuations within the sample which are high close to the inlet part of the material sample and are reduced almost completely towards its outlet. However these pressure fluctuations when scaled with the corresponding mean pressure retained their time-dependent amplitude and phase unchanged along the material. These relative pressure fluctuations cancelled out the flow velocity fluctuations resulting insignificant fluctuations in permeability. It was found that permeability, which is a material property, is drastically reduced with increased compaction ratio of the material while its solid fraction changes substantially but its porosity remains practically unchanged. A comparison with the Cármán–Kozeny expression for random porous media was also examined. Cármán–Kozeny expression predicts qualitatively the reduction of permeability with compaction. However, the predicted values of permeability are very sensitive to the initial value of porosity.     

Aluminide Diffusion Coatings on Ni-base Superalloys

In this report the research work supported by the grant awarded from the Bert Hayes Memorial Fund is detailed. This work was undertaken within a project sponsored by Diffusion Alloys Ltd, Hatfield. It was carried out by Ms. S. M. Ng as part of her Materials Engineering M.Sc. studies in the Institute of Polymer Technology and Materials Engineering (IPTME) at Loughborough University of Technology. Ms. Ng has now passed her M.Sc. degree, obtaining a distinction for her project. The results were summarised in the January 1996 issue of this journal in a symposium report by D. Ross.     

激光全息图像生产的电铸工艺

介绍激光全息图像生产的电铸工艺过程，故障和补救措施。     

以LOM原型为基础的电铸载体选择

本文以LOM原型为基础，分别制作环氧树脂模型、硅胶模型、吸塑件模型石膏模型，并对这四种模型做电铸载体的可行性进行分析，在不影响电铸质量的前提下，根据不同结构特征可以选择合适的电铸载体。     

气—固多相同轴射流的数值模拟和试验

本文提出了一个新的气-固多相湍流运动的模型(脉动频谱随机颗粒轨道模型),它计及了湍流涡团对颗粒扩散作用,并通过体平均方法求出颗粒的速度场和浓度场。同时建立了气-固多相射流试验台,采用激光衍射仪、高速变色频闪摄影法等对气-固多相同轴射流进行了实验研究。实验和上述模型模拟的结果吻合较好。