书讯

<正>《电铸原理与工艺》(作者:陈钧武)定价:25元电铸是用金属电沉积的方法制备产品的一种特种加工工艺,主要用于某些特种产品的成型。本书对电铸技术的特点及其应用、需电铸的金属制品设计、芯模的设计与加工、多种金属和合金及复合材料的电铸工艺与性能、电铸质量控制与电铸层性能的检测、电铸设备及工艺装备均作了详细的叙述,并对多种电铸产品的实例进行了介绍。这是一本内容十分丰富的专业书籍,对从事电铸制品设计与加工的工程技术人员在日常工艺维护、新产     

精密模具电铸镍钴工艺的研究

研究了Ni-Co电铸溶液成分和工艺参数对Ni-Co电铸层内应力、硬度、抗拉强度及延伸率的影响,提出了电铸液各成分含量和工作条件的最佳值.由本电铸工艺所得电铸层的硬度≥752Hv,抗拉强度≥1533N/mm~2,延伸率≥2.8%,杯突值≥4.3mm.     

电铸技术的研究与发展

简述了电铸的基本原理及工艺方法。随着材料、工艺、设备的进步,电铸技术也得到了长足的发展,越来越多地和其它技术相结合,如组合电铸、微器械制造、喷涂电铸等;同时,也指出了现阶段我国电铸技术的缺陷。但是作为一门交叉性的学科,随着技术的发展,电铸的发展空间和应用前景是很广阔的。     

电铸镍网工艺实践

介绍了纺织印染系统应用的多色电铸镍网圆筒的制作工艺流程、电铸铜及电铸镍溶液组成与操作条件。对电铸铜与电镀铜工艺、电铸镍与电镀镍工艺进行了比较。提出了工艺中需要注意的几个问题,包括：电铸铜时毛刺产生的原因及解决办法、氯离子的控制、镍珠和钛篮的使用、添加剂含量控制、电源选择等。     

电铸工艺

通过多年电铸工艺经验,总结出一套操作简便、生产成本低、生产效率高、可得到广泛应用的电铸工艺技术,介绍了电铸芯模材料与制造的要求,以及该电铸工艺流程与工艺规范,并提出了电铸过程中的几点注意事项。     

微细电铸制造技术的研究进展

介绍了微细电铸技术的基本原理,阐述了超声微细电铸、磁电微细电铸、超临界微细电铸和屏蔽模板随动式微细电铸这4种新型制造工艺的原理及研究进展,指出了今后的研究重点。     

阳极使用不当引发的槽液故障探讨

0 前言 电铸是在芯模上电沉积金属,然后使两者分离来制取零件的工艺.它能够复制芯模表面的形貌,解决一些难以加工零件的制造问题,同时还能够大大提高加工零件的精度.我单位采用电铸镍工艺制造某机型的机翼前缘防护片.该工艺对杂质的敏感度很高,当溶液中混入有机或无机杂质后,将会影响电铸件的脆性以及出现外观质量问题.本文分析故障产生的原因,以及如何合理有效地使用阳极.     

铁(镍)复合电铸模的试制

一、言前随着工业生产的飞跃发展,模具制造在工业中所起的作用日益显得重要。电铸模具在我国是一门新兴的工艺,它不仅在国防、精密仪器仪表制造和一些轻工业产品制造上解决了几何形状特殊和形腔复杂模具的制造而且缩短了开模时间。目前一般常用的电铸工艺有电铸镍、铜等。电铸镍模不但光洁度、精密度好而且硬度高。可是由于价格昂贵,不能满足工业上的需要。如果采用先电铸一薄层(约0.8～1毫米)镍,再用镀铁来电铸加厚,则不但节约了大量贵重的镍,并且缩短了电铸周期,而且对模具硬度和耐磨度均无影响。如果不先电铸镍而直接以镀铁来电铸模具,然后进行热处理来提高硬度和耐磨度的话,那末其所起作用和经济意义就更大了。     

直流和脉冲Ni-ZrO2纳米复合电铸层显微硬度的研究

利用SEM分析了纯镍电铸层,以及用直流和脉冲工艺所制备纳米复合电铸层的表面形貌,分别研究了影响直流和脉冲纳米复合电铸层显微硬度的各种因素,同时对纳米复合电铸层的强化机理进行了探讨.结果表明,纳米复合电铸层的表面形貌不同于纯镍电铸层,并且其显微硬度得到明显提高.纳米复合电铸层的强化机理主要是细晶强化机制、弥散强化机制和高密度位错强化机制.     

LIGA技术微电铸镍的电化学研究

微电铸工艺兼具掩膜电镀和厚膜结构电铸的双重特征.采用线性电位扫描和电化学交流阻抗等电化学测量技术,对高深宽比掩膜条件下微电铸镍的电极反应动力学过程进行了初步研究.结果显示,高深宽比掩膜使扩散传质过程更容易成为电极反应的控制因素,并由此导致深层微电铸结构疏松多孔等缺陷.提高电镀过程传质能力的改良工艺能够显著改善微电铸镍结构的整体品质.     

胶粘剂特性和厚度对劈裂载荷作用下胶接接头应力分布的影响

运用三维弹塑性有限元法对劈裂栽荷作用下的胶接接头(即劈裂接头)承载后的应力分布特征进行了分析，重点研究了胶粘剂层厚度对劈裂接头应力分布的影响。结果表明，胶粘剂的性能对应力分布有较大影响，提高胶粘剂强度和减小胶层厚度，均导致胶层应力集中加剧，各向正应力峰值呈上升趋势，各向剪切应力则正好相反；并且劈裂接头中应力分布以三向主应力为主，剪切应力的存在亦不可忽略。故在不引起过大应力集中和较大胶层缺陷条件下采用高强度的胶粘荆和较厚胶层对提高劈裂接头强度有利，实验结果与有限元分析相吻合。     

Yield Stress Measurement of Silicon Nitride Suspensions

Yield stress values of silicon nitride suspensions were measured via a novel slotted plate device and a constant stress rheometer and the results were compared. Test platform velocity, associated with the slotted plate method, was found to have a substantial effect on dynamic yield stress but not on static yield stress. The effects of suspension concentration and temperature on yield stress values were investigated. Yield stress measurements on mixtures of silicon nitride and alumina particles, as well as creep tests were performed.     

氮化硅轴承球表面层残余应力的形成机理及试验研究

本文论述了烧结热应力及研磨加工对氮化硅轴承球表面残余应力的影响机理.通过比容积测定,对氮化硅轴承球表面残余应力分布进行了分析计算,并就研磨加工对氮化硅轴承球表面残余应力的影响进行了试验研究.     

脆性材料哑铃形拉伸试样的应力分布及断裂位置研究

应用大型有限元分析软件ANSYS模拟分析了哑铃形拉伸试样在拉伸过程中的应力分布及应力集中的位置和应力集中系数,分析结果显示过渡圆弧处出现应力集中,应力集中系数达到了1.123。分别采用聚苯乙烯（PS）的压制和注射成型的两种哑铃形试样,研究了试样的拉伸断裂过程及断裂位置,并验证了模拟分析结果正确性。结果表明压制哑铃形试样是均质各向同性,其断裂发生在应力集中系数最大的圆弧过渡位置;对于各向异性的注塑哑铃形试样,断裂发生在表层和剪切层较薄的浇口远端平直段,应力集中对其影响较弱。     

料仓内粉体静态应力分布特性

料仓内的粉体静态应力分布是指导料仓设计和运行的重要参数之一。本文在三维有机玻璃料仓中，对料仓应力分布进行试验研究，利用应力传感器对料仓壁面及粉体内部水平、竖直应力进行研究，获得料仓中粉体内部应力的分布规律，并基于拱效应对料仓中的应力分布进行理论研究。结果表明：料仓内部水平应力与距出口及料仓中心的距离基本无关，壁面处的水平应力在筒锥结合处达到最大值且随加料高度的增加大幅度增加。料仓内部垂直应力的最大值出现在筒锥结合处近筒段的料仓中心位置。同一平面，从料仓中心至仓壁，垂直应力呈逐渐减小的趋势。随加料高度的增加，垂直应力均逐渐增加。在壁面处，侧压力系数随着距出口高度的增加出现先增大后减小的趋势，在筒锥结合处大于1。     

温度和固相粒径与浓度对水煤浆管内流动壁面滑移的影响

通过改变管径、温度、煤粉粒度和浓度,在中试规模的输送装置上研究水煤浆直管内的滑移流动规律,联合采用Mooney滑移修正方法和Tikhonov正则化方法确定浆体壁面滑移特性。结果表明,随温度和固相粒径的增大,临界剪切应力降低,壁面滑移速度显著增加;浓度越高,临界剪切应力及产生相同滑移速度所需的壁面剪切应力越大,温度升高对临界剪切应力和屈服应力的降低越显著;低壁面剪切应力下的滑移贡献率主要取决于临界剪切应力及屈服应力的相对大小,高壁面应力下主要取决于壁面滑移速度和浆体真实流变特性。     

Behavior of NiTiNb SMA wires under recovery stress or prestressing

The recovery stress of martensitic shape-memory alloy [SMA] wires can be used to confine concrete, and the confining effectiveness of the SMA wires was previously proved through experimental tests. However, the behavior of SMA wires under recovery stress has not been seriously investigated. Thus, this study conducted a series of tests of NiTiNb martensitic SMA wires under recovery stress with varying degrees of prestrain on the wires and compared the behavior under recovery stress with that under prestressing of the wires. The remaining stress was reduced by the procedure of additional strain loading and unloading. More additional strains reduced more remaining stresses. When the SMA wires were heated up to the transformation temperature under prestress, the stress on the wires increased due to the state transformation. Furthermore, the stress decreased with a decreasing temperature of the wires down to room temperature. The stress of the NiTiNb wires was higher than the prestress, and the developed stress seemed to depend on the composition of the SMAs. When an additional strain was subsequently loaded and unloaded on the prestressed SMA wires, the remaining stress decreased. Finally, the remaining stress becomes zero when loading and unloading a specific large strain.     

Effects of short fiber tip geometry and inhomogeneous interphase on the stress distribution of rubber matrix sealing composites

The normal and interfacial shear stress distributions with flat fiber tip of short‐fiber‐reinforced rubber matrix sealing composites (SFRC) compared with the shear lag model were investigated by using the finite element method (FEM). The results indicate that stress values do not agree with those calculated by the shear lag model. The effect of different geometrical shapes of fiber tip on the stress distributions of SFRC was also investigated. The geometrical shapes of fiber tip under present investigation are flat, semi‐elliptical, hemispherical, and circular cone, respectively. The results show that the hemispherical fiber tip transfers the load with less stress concentration and is contributed to controlling the interface debonding failure more effectively than other shapes of fiber tip. Further study on the effect of the inhomogeneous interphase properties on the normal and interfacial shear stresses of hemispherical fiber tip was also conducted. The results indicate that the normal stress increases with the increase of the interphase thickness and interfacial shear stress remains unchanged, and the normal stress values of SFRC with interphase are higher than those without interphase. The interphase elastic modulus has no influence on the stress distributions along the direction to the fiber axis. The stress distributions along the radial direction in the interphase end are largely dependent on the interphase elastic modulus, and the interfacial shear stress is larger than the normal stress, which reveals that a significant part of the external load is transferred from the fiber to the matrix through shear stresses within the interphase. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41638.     

Uniaxial ratchetting behavior of vulcanized natural rubber

Most of rubber engineering components endure cyclic loading during their service, and a nonzero mean stress during cyclic loading may cause an accumulation of strain which is known as ratchetting phenomenon. In order to study the ratcheting effect of rubber, a series of uniaxial ratchetting experiments were conducted on vulcanized natural rubber (NR). The effects of cyclic stress amplitude, mean stress and their histories on ratchetting behavior were studied, respectively. The uniaxial ratchetting behavior of natural rubber depends greatly on the stress amplitude and mean stress. The ratchetting strain rate greatly increases with the stress amplitude or mean stress increased. Experimental results reveal that the rubber material exhibits a strong memory of the previous high loading history, and such memory plays a significant role on the subsequent ratchetting. The ratchetting behaviors of the rubber exhibit little sensitive to the applied cyclic stress rate except for the initial strain. POLYM. ENG. SCI., 48:191–197, 2008. © 2007 Society of Plastics Engineers     

不同冲击条件下微晶玻璃涂层冲蚀应力的有限元模拟

材料表面应力状态对材料的冲蚀磨损行为起着重要作用。本文利用有限元方法探讨了冲蚀角度、冲蚀速度、磨料粒径对微晶玻璃涂层冲蚀应力的影响,利用常温冲蚀试验机对微晶玻璃涂层在不同冲蚀角度下的体积磨损率进行了测定。结果表明,随冲蚀角度、冲蚀速度、磨料粒径增大,涂层的冲蚀应力均逐渐增大。在相同的冲蚀角度和冲蚀速度条件下,磨料粒径对涂层冲蚀应力的提升效果显著。微晶玻璃涂层冲蚀磨损率随冲蚀角度的增大而增加,其变化规律与冲蚀应力变化趋势基本一致,从而验证了有限元应力模拟的可靠性。