液体喷射抛光技术材料去除机理的有限元分析

实验研究了液体喷射抛光技术的材料去除量分布特征,并利用有限元分析方法,分析了抛光头(液体柱)与工件表面相互作用时流场的分布特点。实验结果及计算机模拟的结果表明,材料去除量与射流碰撞工件后流体沿工件表面的速度有关,即材料去除量的分布与抛光液在工件表面速度场的分布有关,速度分布最大的边缘部分,材料去除量最大;相互作用区外,速度逐渐减小,材料去除量也随之渐少。该现象说明,抛光液中磨料粒子的径向流动对工件产生的径向剪切应力是材料去除的关键。     

高硬度弱酸性氰化亚金钾电铸黄金工艺品的研制

在弱酸性氰化亚金钾电铸溶液中加入少量(0.3～0.6 g/L)氰化钴钾,电铸黄金工艺品的硬度达到155～185 HV,与传统产品相比增加了100 HV.电铸工艺品硬度及黄金成色都采用相关的国际标准测定.实验结果表明,黄金铸件的硬度先随氰化钴钾加入量的增加而提高,当氰化钴钾加入量为0.4 g/L时达最大值,而后趋于稳定;Co3 含量在0.008%～0.03%之间时,黄金产品的成色没有影响;加入钴离子后,产品成品率明显增加到76%～92%.该工艺可以显著提高黄金工艺品的质量与产量,节省黄金原料,具有很高的实用价值.     

Improved shape evolution of copper interconnects prepared by jet-stream etching

In the preparation of copper interconnects in the conductor pattern of a printed circuit board (PCB), wet etching processes are commonly adopted for creating patterns of high-density interconnects. Currently available techniques of immersion and spray etching could lead to poorly shaped wires due to complex flow fields or the disturbing puddling effect. A modified technique of arrayed jet-stream etching was developed in this work, aiming at producing well-defined copper interconnects on a PCB in a significantly shorter time. The results were appealing in that copper interconnects of 35/140 μm (thickness/width) exhibiting etching factors of greater than 6 were obtained in 20 s, much better than the conventional ones with etching factors of 3 to 5 and etching times of at least 2 min. In addition, uniformly etched copper interconnects with less than 20 μm undercuts were observed on one etching line. One additional point to note is that no banking agents or inhibitors as commonly seen in conventional etching techniques were needed in this new processing method.     

热水蒸煮大豆蛋白产品的功能性研究

研究了热水蒸煮时间对脱脂大豆粉、醇洗大豆浓缩蛋白、大豆分离蛋白的影响。热水蒸煮提高了浓缩蛋白和分离蛋白的起泡性和乳化性，对脱脂大豆粉的乳化性有所提高，但不能提高其起泡性。破坏胰岛素抑制剂和微生物的热水蒸煮对蛋白质的加工具有重要的意义。     

柴油压力喷射破碎特性试验研究

在压力喷雾试验中,观测到了一些液雾破碎现象：在喷嘴出口处,液射流旋转;液射流的完全破碎并不发生在与喷雾轴线相垂直的径向截面内,而是发生在某一螺旋截面上。据此作者提出了一种液射流破碎的物理模型。试验中还发现了一种新的破碎长测量方法,本文报告了这些试验结果。     

Three-dimensional vortex simulation of bubble dispersion in excited round jet

This study is concerned with the three-dimensional numerical simulation of a bubbly jet, injected vertically upward from a circular nozzle in still water, when the axial and helical disturbances are imposed. The water flow is simulated by a vortex method, and the equation of motion for a bubble is solved on the flow by the Lagrangian scheme. The disturbances markedly change the vortical structure of water in the developing region. Since the bubbles accumulate on the high vortical region, their dispersion remarkably varies owing to the disturbances. The single helical disturbance causes the larger dispersion of bubble. The combined two helical disturbances make the bubble concentrate on a line in the jet cross-section. The present simulation suggests the possibility of the active control for the bubble dispersion in bubbly jet.     

Fabrication of Fuze Micro-electro-mechanical System Safety Device

Fuze micro-electro-mechanical system(MEMS) has become a popular subject in recent years.Studies have been done for the application of MEMS-based fuze safety and arm devices.The existing researches mainly focused on reducing the cost and volume of the fuze safety device.The reduction in volume allows more payload and,thus,makes small-caliber rounds more effective and the weapon system more affordable.At present,MEMS-based fuze safety devices are fabricated mainly by using deep reactive ion ething or LIGA technology,and the fabrication process research on the fuze MEMS safety device is in the exploring stage.In this paper,a new micro fabrication method of metal-based fuze MEMS safety device is presented based on ultra violet(UV)-LIGA technology.The method consists of SU-8 thick photoresist lithography process,micro electroforming process,no back plate growing process,and SU-8 photoresist sacrificial layer process.Three kinds of double-layer moveable metal devices have been fabricated on metal substrates directly with the method.Because UV-LIGA technology and no back plate growing technology are introduced,the production cycle is shortened and the cost is reduced.The smallest dimension of the devices is 40 μm,which meets the requirement of size.To evaluate the adhesion property between electroforming deposit layer and substrate qualitatively,the impact experiments have been done on the device samples.The experimental result shows that the samples are still in good condition and workable after undergoing impact pulses with 20 kg peak and 150 μs duration and completely met the requirement of strength.The presented fabrication method provides a new option for the development of MEMS fuze and is helpful for the fabrication of similar kinds of micro devices.     

喷射早强钢纤维混凝土在补强矿区铁路公铁立交桥中的应用

矿区铁路沉降引起公铁立交桥产生裂缝 ,用喷射早强钢纤维混凝土来进行补强加固 ,体现了早强钢纤维混凝土具有初期强度高和优良的抗拉性、抗裂性和柔韧性等特点。通过试验和施工取得了良好的效果     

电火花加工工具电极耐电蚀性能的试验研究

电火花成形加工过程中，工具电极的损耗是影响工件几何形状精度的主要因素之一。从工具电极的制作工艺着手，分别利用直流和脉冲电流电铸工具电被，进行了电极放电损耗试验。通过试验和SEM形貌研究分析了工艺参数对电极耐电蚀性能的影响，并用正交试验法优化了工艺参数。结果表明，脉冲电铸铜电极可降低损耗，且在一定工艺条件下脉冲电铸电极具有优异的耐电蚀性能。     

微粉金刚石表面镀钛对钎焊磨具性能的影响

在微粉金刚石磨具的制备过程中,金刚石热损伤和磨粒与结合剂间界面特性是影响磨具性能的主要因素。利用电铸与钎焊相结合的工艺把表面镀钛和未镀钛两种微粉金刚石磨料制备成磨具,并将其用于氧化铝陶瓷的磨削试验。通过对钎焊后金刚石磨粒与钎料的界面分析,磨削力、磨粒脱落率以及工件表面粗糙度的比较,探讨磨粒表面镀钛对钎焊微粉金刚石磨具性能的影响。结果表明,镀钛微粉金刚石表面镀层在钎焊过程中对微粉金刚石起到包裹隔离的作用,可以降低微粉金刚石的热损伤和石墨化;在利用两种钎焊微粉金刚石磨具磨削氧化铝陶瓷时,镀钛微粉金刚石磨具的磨削力较小,磨料的脱落率也较少,且工件表面粗糙度值更低。综合比较,磨粒表面镀钛后,可以减弱微粉金刚石的热损伤,提高磨具的磨削性能。