Improvement of thickness deposition uniformity in nickel electroforming for micro mold inserts

Thickness deposition is a crucial issue on the application of electroformed micro mold inserts. Edge concentration effect is the main source of the non-uniformity. The techniques of adopting a non-conducting shield, a secondary electrode and a movable cathode were explored to improve the thickness deposition uniformity during the nickel electroforming process. Regarding these techniques, a micro electroforming system with a movable cathode was particularly developed. The thickness variation of a 16 mm×16 mm electroformed sample decreased respectively from 150% to 35%, 12% and 18% by these three techniques. Combining these validated methods, anickelmold insert for microlens array was electroformed with satisfactory mechanical properties and high replication precision. It could be applied to the following injection molding process.

Effects of rare earth on microstructures and properties of Ni-W-P-CeO_2-SiO_2 nano-composite coatings

Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on common carbon steel surface by pulse electrodeposition of nickel, tungsten, phosphorus, rare earth （nano-CeO2） and silicon carbide （nano-SiO2） particles. The effects of nano-CeO2 concentrations in electrolyte on microstructures and properties of nano-composite coatings were studied. The samples were characterized with chemical compositions, elements distributions, microhardness and microstructures. The results indicated that when nano-CeO2 concentration was controlled at 10 g/L, the nano-composite coatings possessed higher microhardness and compact microstmctures with clear outline of spherical matrix metal crystallites, fine crystallite sizes and uniform distribution of elements W, P, Ce and Si within the Ni-W-P matrix metal. Increasing the nano-CeO2 particles concentrations from 4 to 10 g/L led to refinement in grain structure and improvement of microstructures, while when increased to 14 g/L, the crystallite sizes began to increase again and there were a lot of small boss with nodulation shape appearing on the nano-composite coatings surface.

Influence of SiO_2 Particles on Microstructures and Properties of Ni-W-P-CeO_2-SiO_2 Nano-Composite Coatings

Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on the carbon steel surface by pulse co-deposition of nickel, tungsten, phosphorus, nano-CeO2 and nano-SiO2 particles. The influence of nano-SiO2 particles concentrations in electrolyte on microstructures and properties of the nano-composite coatings were researched, and the characteristics were assessed by chemical compositions, element distribution, deposition rate, microhardness and microstructures. The results indicate that when nano-SiO2 particles concentrations in electrolyte are controlled at 20 g·L-1, the deposition rate with 27.07 μm·h-1 and the microhardness with 666 Hv of the nano-composite coatings are highest, element line scanning and area scanning analyses show that the average contents of elements W, P, Si and Ce in the nano-composite coatings are close, displaying that the distribution of every element within the nano-composite coatings is even. An increase in nano-SiO2 particles concentrations in electrolyte (when lower than 20 g·L-1) leads to refinement in grain structure of nano-composite coatings, but when it improved to 30 g·L-1, the crystallite sizes increase again and in the meantime there are a lot of small boss with nodulation shape appearing on the surface of nano-composite coatings.

Optical Absorption of Nano-Composite Thin Films of Au in Teflon

Nano-composite films of Au particles in Teflon were obtained by thermal vacuum deposition. The obtained films were characterized by the different shapes and dimensions of the inclusion particles. Absorption spectra of the films were measured in-situ. A model for the calculation of the optical properties of the nano-composite thin films with an inho-mogeneous distribution of the inclusions along the thickness of the film is proposed. Absorption properties of inclusions were analyzed by considering the local field interaction. The calculated absorption profiles are compared with the experimentally obtained absorption profiles. This comparison gives a possibility to draw conclusions about the concentration, shapes and shape distributions of the inclusion particles. For example, the films obtained by duration deposition are characterized by inclusions having the shape of prolate ellipsoids oriented normally to surface of the film.

超声波对Ni-CeO_2纳米复合电铸层微观结构和性能的影响

采用扫描电镜和X射线衍射分析Ni-CeO2纳米复合电铸层的表面形貌和结晶取向,研究超声波对电铸层显微硬度和耐磨损性能的影响。结果表明:由于电铸过程中引入的超声波的强力搅拌作用、超声空化效应和声流扰动效应,可以有效抑制CeO2纳米颗粒在镀液中的团聚,并促使其在电铸层中均匀分布,进一步细化了Ni结晶晶粒;超声波的引入可促进Ni晶体沿(111)和(220)晶面方向的生长,改变电铸层的结晶取向;与无超声波作用相比,超声波作用下制备的纳米复合电铸层显微硬度高、耐磨损性能优良,在CeO2添加量为40g/L时所制备的纳米复合电铸层的显微硬度最高、磨损率最低。

镍-氧化镧纳米颗粒复合电铸的研究

采用复合电铸工艺制取了含La2 O3 纳米颗粒的镍基复合电铸层 ,研究了La2 O3 纳米颗粒共沉积量对复合电铸层微观组织及显微硬度的影响。结果表明 ,随着La2 O3 纳米颗粒共沉积量的增大 ,复合电铸层表面更加平整、组织也更加细致均匀 ,基质金属镍的晶粒得到进一步细化 ,因而复合电铸层的显微硬度也随之升高。

基于电铸技术的Ni-ZrO_2纳米复合材料制备工艺

在镀液的pH值、温度和搅拌速度一定的条件下 ,分析了镀液中纳米ZrO2 颗粒悬浮量和阴极电流密度等工艺参数对Ni ZrO2 复合电铸层中纳米ZrO2 复合量的影响。运用正交试验法优化了对复合沉积层中纳米ZrO2 复合量有较大影响的各工艺参数 ,同时用SEM对纳米复合电铸层进行了表面形貌和成分的能谱分析。结果表明 ,由优选工艺参数所制备的Ni ZrO2 纳米复合电铸层 ,表面平整光滑 ,组织均匀、致密 。

纳米晶精密电铸层微观结构的测试与研究

采用高速冲液电铸装置、高频脉冲电流等方法 ,制备出金属镍纳米晶粒电铸沉积层。运用TEM、SEM和XRD等现代分析手段对纳米晶沉积层微观结构进行了分析研究。结果表明 ,沉积电流密度对细化沉积层晶粒有着重要影响。随着沉积层晶粒细化 ,横断面上晶粒生长从树枝状晶向细小等轴—柱状晶方式转变 ,在 ( 2 0 0 )晶面存在着明显择优生长取向。

Ni-ZrO_2纳米复合电铸层耐蚀性的研究

用静态浸泡实验法研究了镍镀层和Ni ZrO2 纳米复合电铸层在质量分数分别为 10 %HCl溶液和 10 %H2 SO4 溶液中的耐蚀性。用SEM观察了各种样品腐蚀后的表面形貌 ,分析了纳米ZrO2 微粒复合量对复合电铸层耐蚀性的影响 ,同时对纳米复合电铸层的腐蚀机理进行了初步探讨。结果表明 ,脉冲纳米复合电铸层的耐蚀性明显优于相同条件下制备的镍镀层 ,镀液中纳米ZrO2 悬浮量对提高纳米复合电铸层耐蚀性有一定程度的影响。

用优化象形阳极改善合金电铸层的沉积分布

设计了一种可用于复杂回转形零件电铸的装置,为了改善合金电铸时沉积金属分布的均匀性,该装置采用了特殊结构的象形阳极并利用ANSYS有限元软件对象形阳极进行了精确的轮廓形状设计。对某喷管模拟件进行了镍锰合金的电铸试验,得到了较均匀的电铸层厚度及锰含量分布。该方法既可提高生产效率,又可降低成本。

脉冲电铸镍-氧化钕纳米复合沉积层的工艺研究

电化学沉积层的制备是电铸技术的关键环节。本文采用脉冲电铸技术制备N i-Nd2O3纳米复合沉积层,考察了镀液中Nd2O3纳米颗粒添加量、平均电流密度、占空比、脉冲频率对纳米复合沉积层中Nd2O3含量及纳米复合沉积层显微硬度的影响,并对纳米复合沉积层的表面形貌进行了分析。结果表明,在镀液中Nd2O3纳米颗粒添加量20 g/L^30 g/L、脉冲平均电流密度2 A/dm2~4 A/dm2、占空比0.2~0.4和脉冲频率1000 Hz的条件下,可获得Nd2O3含量大的高硬度复合沉积层,并且沉积层表面平整、光滑,晶粒细小,组织均匀致密。

镍-氧化锆纳米复合电铸层微观形貌影响因素的分析

用SEM分析了诸如电铸时间、电流密度、镀液中纳米ZrO2颗粒悬浮量、电流形式和阴极表面粗糙度等因素对Ni ZrO2纳米复合电铸层微观形貌的影响。结果表明,电铸时间、阴极电流密度以及镀液中纳米ZrO2悬浮量对纳米复合电铸层微观形貌有一定程度的影响,采用脉冲电沉积工艺有助于获得表面光滑平整、显微组织均匀致密的纳米复合电铸层。

含纳米ZrO_2颗粒复合电铸层高温氧化行为研究

通过间歇式高温氧化实验,建立了纯镍电铸层和Ni-ZrO2纳米复合电铸层高温氧化动力学模型,分析了电铸层表面和横截面的形貌,测定了脉冲复合电铸层横截面中各组织成分的分布状态。结果表明,Ni-ZrO2纳米复合电铸层高温氧化性能明显优于纯镍铸层,复合电铸层表面生成的氧化膜晶粒细小且致密。复合电铸层表面的氧化膜与复合电铸层的黏附性较好,这是由于其较薄,并且所产生的内应力较小所致。

基于纳米氧化镧的精密电铸工艺试验研究

采用纳米稀土La2O3为添加剂,研究其对电铸镍溶液特性、铸层微观结构及其性能的影响。通过对沉积过程中阴极极化曲线的测定,探讨了纳米La2O3在电极表面的作用机理,并采用SEM、XRD等现代分析手段对电铸层微观结构进行了测试和分析。试验结果表明:纳米La2O3能够在阴极表面发生特性吸附,增大阴极极化,细化精密电铸层晶粒,提高铸层的均匀性;晶粒生长在(220)晶面方向上存在明显的择优取向;获得的电铸层显微硬度比普通电铸层有显著提高。

直流和脉冲Ni-ZrO_2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。

Ni-ZrO_2纳米复合电铸层抗高温氧化性能的研究

通过间歇式抗高温氧化实验,建立了纯镍电铸层和N i-ZrO2纳米复合电铸层高温氧化动力学模型,分析了电铸层表面和横截面的形貌,测定了电铸层的组织结构。结果表明,N i-ZrO2纳米复合电铸层抗高温氧化性能明显优于纯镍铸层,复合电铸层表面生成的氧化膜晶粒细小且致密,并且该氧化膜较薄,产生的内应力较小,与复合电铸层的黏附性较好。

复合电沉积工艺参数对镍晶微铸件表面性能的影响

目的将超声波、磁场引入到微电铸过程中,改善电沉积镍晶微构件的表面性能。方法改变电流密度、脉冲占空比、超声波功率、磁场强度的方向和强度,进行电沉积镍晶微铸件,分析这些工艺参数对微铸件表面形貌和显微硬度的影响。结果微铸件的显微硬度随磁场强度的增大而显著提高,随着阴极电流密度、超声波功率及脉冲占空比的增大呈现出先升高、后下降的规律,其中脉冲占空比对电铸层显微硬度的影响较弱。优选的工艺参数为:垂直磁场强度0.8 T,阴极电流密度2 A/dm2,超声波功率240W,脉冲占空比20%。结论引入超声波和磁场后可优化电沉积环境,细化电铸层晶粒尺寸,改善电铸层微观形貌,提高微铸件显微硬度。

热处理对Ni-ZrO2纳米复合电铸层显微硬度的影响

利用SEM分析纯镍电铸层,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,测定常温下和经过不同温度热处理后纳米复合电铸层的显微硬度,探讨纳米复合电铸层的强化机理。结果表明,纳米复合电铸层的表面形貌不同于纯镍铸层,并且其显微硬度明显提高。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。由于再强化效应的作用,经过热处理后的纳米复合电铸层,尤其是由脉冲电沉积所得纳米复合电铸层,其显微硬度的提高程度尤为明显。

基于化学复合镀的快速原型模具生产工艺研究

在快速原型熔融沉积产生的ABS零件芯模上,采用化学镀技术,镀覆一层Ni-P/PTFE合金层。使得利用零件芯模硅胶注塑和电铸成形,得以顺利、高效地进行。

基于化学复合镀的快速原型模具生产工艺研究

在快速原型熔融沉积产生的ABS零件芯模上,采用化学镀技术,镀覆一层Ni-P/PTFE合金层。使得利用零件芯模硅胶注塑和电铸成形得以顺利、高效地进行。