Electrochemical characteristics of electroplating and impregnation Ni-P/SiC/PTFE composite coating on 316L stainless steel

Ni-P/SiC/PTFE coating was obtained on the surface of 316L stainless steel by electrodeposition of Ni-P/SiC coating and immersion of PTFE(polytetrafluoroethylene).The surface morphology and composition were analyzed by scanning electron microscope and energy dispersive spectrometer.The corrosion resistance of the coating in 0.5 mol/L H2SO4+2×10−6 HF solution was studied by electrochemical method.Surface contact angle was used to test the hydrophobic properties of the coating.The results indicated that the Ni-P/SiC/PTFE coating prepared on the surface of stainless steel was uniform and compact,which significantly improved the self-corrosion potential of stainless steel.The self-corrosion current density decreased from 7.62 to 0.008μA/cm2.The durability performance of coating was tested under 0.6 V voltage and the stable corrosion current density value was 0.19μA/cm2,then wetting angle was tested after durability experiment and the value is 134.5°.

Recovery of heavy metals from electroplating sludge and stainless steel pickle waste liquid by ammonia leaching method

A coordinative disposal process for treatment of electroplating sludge and stainless steel pickle waste liquid containing Cu, Ni, Zn, Cr and Fe etc., has been developed to recover valuable metals and to eliminate pollution. The recovery of Cu, Ni, Zn and Cr is 94%, 91%, 90% and 95%, respectively. The ammonia was recycled by the simplified process of CaO caustic distillation. The precipitated product of Cu, Ni and Zn obtained from caustic distillation of ammonia was separated by extraction or high\|pressure hydrogen reduction in an autoclave. The qualified metal salt products were obtained through extraction. The rich chromium residue from coordinative disposal was subjected to recover Cr by hydrothermal oxidation in NaOH medium and Fe\-3O\-4 was synthesized by wet methods from the residue produced by extracting Cr. Cr was a stable chemical fixed in Fe\-3O\-4 and harmless. The recovery process has been used in a pilot plant with sludge production capacity of 2000 t/a.

Erosion-corrosion behavior of Pd-Co and Pd-Cu films on 316L stainless steel in simulated PTA slurry environment

Pd-Co films with the Co content varying from 21.9% to 34.62%（mole fraction） and Pd-Cu（5% Cu, mole fraction） film were electrodeposited on 316 L stainless steel, and the erosion-corrosion resistance of the Pd-Co and Pd-Cu plated samples in a simulated boiling pure terephthalic acid（PTA） slurry environment was studied with methods of mass loss test, polarization measurement and scanning electron microscopy（SEM）. Under the static state condition, both the Pd-Cu and Pd-Co plated samples exhibit good corrosion resistance and the Pd-Cu film behaves slightly better. However, with increasing the stirring speed, the corrosion rate of the Pd-Cu plated samples increases obviously while that of the Pd-Co plated samples shows only slight increase. Higher microhardness and lower surface roughness of Pd-Co film than those of Pd-Cu film, as well as good corrosion resistance, may be the main reasons for better erosion-corrosion resistance in the strong reductive acid plus erosion environment.

Electrodeposition of multi-layer Pd-Ni coatings on 316L stainless steel and their corrosion resistance in hot sulfuric acid solution

Pd-Ni coating shows good corrosion resistance in strong corrosion environments.However,in complex aggressiveenvironments,the performance of the coatings is limited and further improvement is necessary.The effects of the applied platingcurrent density on the composition,structure and properties of Pd-Ni coatings were studied.By changing the current density in thesame bath,multi-layer Pd-Ni coatings were prepared on316L stainless steel.Scanning electronic microscopy,weight loss tests,adhesion strength,porosity and electrochemical methods were used to study the corrosion resistance of the films prepared bydifferent coating methods.Compared with the single layer Pd-Ni coating,the multi-layer coatings showed higher microhardness,lower internal stress,lower porosity and higher adhesive strength.The multi-layer Pd-Ni coating showed obviously better corrosionresistance in hot sulfuric acid solution containing Cl-.

Electron beam braze-welding of vanadium alloy to stainless steel with electroplated Cu/Ag coatings

Cracks may easily occur in the fusion weld between vanadium alloys and stainless steel due to the brittle intermetallics and welding stress. The high vacuum electron beam braze-welding has been successfully used to join vanadium alloy（V-5Cr-STi） to stainless steel （HR-2） with electroplated Cu and Ag coating. To investigate the effects of electroplated coating on the weldability, the joint appearaace, the microstrueture and the mechanical properties of the joints have been thoroughly analyzed. The results show that the joint surface configuration was good and root reinforcement was full and smooth. A reaction zone （RZ） was gained on the interface between the V-5 Cr-5 Ti alloy and HR-2 stainless steel base metals. The width of reaction zone at the top of the joint was up to O. 65 mm, wider than that in the bottom of the joint （ 0.46 mm）. The reaction zone consisted of considerably smaller dendritic structures with an average grain size of less than 10μm. Element Ag and Cu almost enriched the interface between V-SCr-5Ti alloy substrate and RZ, serving as a physical barrier which decreases or avoids the formation of intermetallics. The maximum tensile strength of vanadium alloy^stainless steel dissimilar alloy joint was more than 300 MPa. The joint was defects free.

Electrodeposition of Fe-Ni alloy coating on ferritic stainless steel

Fe-Ni alloy coatings were electrodeposited on ferritic stainless steel(FSS)in solutions containing FeSO4 and NiSO4.The effects of pH,[Fe2 +]/[Ni 2+](molar ratio)of electroplating solutions and cathode current density on deposition rate and surface appearances of the coatings were investigated.The results indicated that the deposition rate of the coating in solution with [Fe 2+ ]/[Ni 2+ ]of 0.4 slightly increased with increasing pH from 2.5 to 3.5 under the current density of 5.5 mA/cm 2 ,and then the deposition rate of the coating in solution with pH 4.0 began to decrease.The deposition rate also slightly increased with pH up to 3.5 under higher cathode current densities of 13.5 and 27 mA/cm2.Under 13.5 mA/cm 2,however,the coating deposited in solution with pH 4 was prone to crack or flake.The deposition rate increased and the surface of coatings became less smooth with increasing cathode current density.The effect of the ratio of[Fe2 +]to[Ni 2+]on deposition rate was not obvious.With increasing the ratio of [Fe2 +]to[Ni 2+]in plating solution,the content of Fe in the coatings increased;while the Ni content in the coatings decreased with the increase in the ratio of[Fe 2+ ]to[Ni 2+ ].The deposited coating consisted of Fe-Ni alloy phase.

Deposition processes and properties of coatings on steel fasteners——A review

Mechanical fastening is widely used in joining metals, particularly in automotive, aerospace, building and construction industries. However, the main concern on mechanical fastening is the issue of corrosion. An effective way to prolong the service life of steel fasteners is to apply protective coatings onto these components. This paper reviews and compares a few common coating deposition techniques, i.e., electroplating, hot-dip galvanizing, ion vapour deposition and mechanical plating, in terms of their characteristics. Compositional and microstructural properties including morphology and porosity, corrosion resistance performance and frictional performance of the coatings formed by each process are discussed in details. Hydrogen embrittlement, a premature failure often occurred on high strength steel fasteners, is also reviewed. The key results of recent studies of various metallic coatings on fasteners are presented to provide a fundamental understanding of the evolving topics, and the research gaps have been identified for further investigation.

Electrodeposition of Gold to Conformally Fill High-Aspect-Ratio Nanometric Silicon Grating Trenches: A Comparison of Pulsed and Direct Current Protocols

Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of X-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in sub-micron-width silicon trenches with an aspect ratio greater than 35 over a grating area of several square centimeters is challenging and has not been described in the literature previously. A comparison of pulsed plating and constant current plating led to a gold electroplating protocol that reliably filled trenches for such structures.

航空超高强度钢表面防护技术的研究进展

超高强度钢同时具有高强度和高韧性,是航空航天领域的重要承载构件,在飞机起落架、主梁、传动件、承力螺栓等领域有着广泛的应用。由于其使用时经常暴露在海洋大气环境下,腐蚀现象比较严重,通过对其进行表面保护,可以有效地改善其耐蚀、耐磨等性能,延长相关零件的使用寿命。针对目前常用的几种表面防护技术(热喷涂、真空镀、电镀、化学镀、表面组织转化、激光熔覆、离子注入等),综述了这些表面防护方法对不同超高强度钢耐磨、耐蚀、氢脆、疲劳等方面的影响,分析了这些防护方法的优缺点,并对其今后的发展方向进行了展望。

绝缘子引线腐蚀断裂研究

[目的]绝缘子作为微波组件内、外部的连接器件,其引线与玻璃封接处容易断裂。[方法]采用金相显微镜、扫描电镜、能谱仪等手段对上述断裂的原因进行分析。[结果]通过机理探讨与现场观察相结合,确定症结在于应力腐蚀开裂。绝缘子引线断裂分为3个阶段:点蚀过程及裂纹萌生,裂纹扩展,以及纯力学快速断裂。[结论]采用化学抛光与机械研磨相结合、镍金交叉镀覆的新工艺可以消除绝缘子引线封接处镀层应力敏感性和应力条件,令镀层的结合力、耐盐雾性能及焊接性能均达到工艺要求。

乙二胺添加剂对无氰亚硫酸盐体系电沉积金的影响

无氰亚硫酸盐电沉积金体系面临电流效率低、镀液稳定性差、循环周期短、镀层性能难以满足工业发展需求等问题。为了提高电流效率、镀液稳定性和镀层表面光泽度,改善电沉积金形貌及提高镀层性能,配制了亚硫酸金钠电镀液体系,通过添加不同质量浓度乙二胺(EDA)作为辅助添加剂,研究了EDA对镀液稳定性、电沉积产物表面形貌、元素组成和晶体晶面取向,以及金镀层光泽度、硬度和粗糙度的影响。采用电化学测试进一步研究EDA对溶液中Au+行为的影响。结果表明:EDA使吸附Au+的活性位点增加了2.8倍,同时增加了阴极表面的极化并促进晶粒细化,增强了Au(111)晶面的峰强度。EDA质量浓度为15 g/L时,电镀液能保存6个月以上,电流效率从54%提高到98%,金镀层表面均匀性、光泽度和硬度明显提高,镀层表面粗糙度、腐蚀速率明显降低,镀层综合性能最优。本研究有望为亚硫酸盐电镀体系开发新型高效添加剂提供借鉴,有助于推动电镀金行业的可持续发展。

高强钢零件镀锌镍合金的氢脆敏感性研究进展

为了防止钢铁材料表面在大气环境中发生氧化锈蚀,通常在钢铁零件表面镀锌或镀锌镍合金等防护层。但电镀过程可能会引起高强度材料的氢致开裂或氢脆延迟破坏,因此,探讨高强度材料电镀过程的氢脆敏感性至关重要。本文分析了电镀过程引起高强钢零件氢脆故障的案例和学者们的实验研究结果,探讨了电镀过程中氢的渗入过程,归纳了氢原子在零件内部的存在状态,对比了不同电镀溶液沉积过程中的氢脆敏感性,分析了镀层微观形貌对于氢原子逃逸和氢脆敏感性的影响,总结了热处理烘烤除氢工艺、材料氢脆敏感性评价方法等的研究现状。相关内容可为降低高强钢材料电镀氢脆敏感性的风险打下技术基础,更好的指导电镀高强度钢零件的应用。

亚硫酸盐无氰体系电镀金凸块性能的影响因素

[目的]鉴于先进封装技术向微型化和集成化发展,电镀金凸块成为液晶显示驱动芯片互连的首选。但纯金材料存在强度不足、易形变的问题,因此提升电镀金凸块的力学性能是该领域的研究重点之一。[方法]采用亚硫酸盐无氰体系在晶圆表面电镀金凸块,研究了镀液各组分浓度、工艺参数变化及镀液老化对金凸块性能的影响。[结果]晶圆表面各部位的金凸块外观均一,无漏镀、结瘤、针孔等缺陷,退火后的显微硬度约为90 HV,其力学性能可在较为宽泛的施镀工艺窗口、镀液组分浓度范围及镀液老化过程中保持稳定。[结论]该亚硫酸盐无氰电镀金工艺有望在高密度封装领域得到推广应用。

电镀电流密度对2×0.30HT钢帘线黏合及剥离性能影响

为研究电镀铜过程对钢帘线黏合和剥离性能的影响,以直径1.80 mm钢丝为基础,分别生产不同平均电流密度、槽间电流密度分布及最外层电流密度因素下电镀钢丝,以同机床、同工艺拉拔捻制为2×0.30HT钢帘线,分别考察3因素钢帘线的黏合和剥离性能。结果表明:电镀铜平均电流密度、各阳极架电流密度分布不均以及最外层电流密度在一定范围内变化对钢帘线黏合抽出性能影响较小,但随着电镀平均电流密度增大至17.07 A/dm~2,镀层致密性变差,从而使得钢帘线的剥离性能降低;同时,相比于钢丝最外层电流密度的设置,首节阳极架电流密度过高更容易导致钢帘线的剥离性能不良。

高速激光熔覆马氏体不锈钢涂层与电镀层性能对比与研究

为对比研究不同液压缸服役工况下高速激光熔覆涂层替代电镀硬铬层的可行性,分别制备了马氏体不锈钢熔覆层XG-1、XG-2和电镀硬铬涂层,开展了三种涂层组织、硬度、腐蚀性能及模拟不同工况(划伤磨损、干砂摩擦磨损、滑动摩擦磨损)下磨损性能测试,探讨了涂层失效行为及其应用工况。结果表明:XG-1、XG-2涂层微观组织致密且均匀,平均显微硬度为720.5 HV、653 HV;电镀硬铬涂层分布孔隙和裂纹等缺陷,自腐蚀电流密度为10.45μA/cm^(2),耐腐蚀性能最差;三种磨损形式下电镀硬铬涂层均发生了开裂及剥落,高速激光熔覆涂层表现出更优异的耐磨性能,适用于活塞杆易拉伤、外界富集硬质颗粒污染物、大侧向载荷等液压缸服役工况。

电镀温度对钢板镀铬效果的影响研究

传统二步法电镀铬工艺要求镀液温度一般较高,需要控制在50℃-60℃,高温电镀带来许多不利影响。针对这一问题,本文研究了不同温度对二步法电镀铬效果的影响,开发了精准控温六价铬电镀技术,将温度控制在45℃~48℃,研究结果表明温度越低电流效率越高,即在镀铬层同样厚度的情况下,所需消耗的电镀电流减少,实现节能降耗,降低电镀成本,同时提高生产效率,减少镀铬污水排放。

应用于封装凸块的亚硫酸盐无氰电镀金工艺

[目的]在工业可持续发展战略下,环保无氰电镀金技术正逐步替代传统氰化物电镀金技术,并在微电子封装领域中得到推广应用。[方法]针对液晶驱动芯片封装晶圆电镀金凸块工艺制程,开发出一种新型亚硫酸盐无氰电镀金配方和工艺。[结果]自研无氰电镀金药水中添加了有机膦酸添加剂和晶体调整剂,前者能够充分抑制镍金置换,后者有助于形成低应力的等轴晶组织,可避免施镀过程中国产光刻胶挤出变形现象。该自研无氰电镀金工艺应用于晶圆时可获得微观表面平整均匀和无缺陷的金凸块。[结论]该自研无氰电镀金工艺能够满足晶圆级封装的要求,具备很好的推广应用潜力。

键合参数对电镀金键合性能的影响

采用超声波键合对由无氰电镀金和含氰电镀金制备的封装材料进行金丝键合测试,研究了键合工艺参数(超声功率、超声时间、键合压力)对键合性能的影响。结果表明,采用无氰电镀金液的底材材料硬度高,金丝焊球处发生失效的现象较多,而采用含氰电镀金液的底材材料硬度低,金丝焊球处发生失效的现象较少。对于低硬度的电镀金层,其焊球直径和键合高度都较低,有助于键合金丝和电镀金界面实现更好的融合。超声时间是影响键合性能的主要因素,当超声时间增加至300 ms,金丝焊球不再出现失效,有效解决了键合性能不良的问题。

氧化铝陶瓷封装外壳电镀爬金缺陷分析与解决

针对焊接框架引线类陶瓷封装外壳电镀后爬金缺陷,采用扫描电子显微镜和能谱仪对电镀前的陶瓷外壳进行了分析。结果表明,在烧结和钎焊过程分别在陶瓷表面上引入了钨粉和焊料,在显微镜下无法筛选去除导致电镀后爬金。在增加了烧结工装的清洗和电镀前处理以及退火后,爬金缺陷得到有效解决。

电镀玫瑰金拉丝不锈钢制品仓储腐蚀机理研究

该文对电镀玫瑰金拉丝不锈钢制品仓储腐蚀机理进行研究分析。结果表明,电镀玫瑰金拉丝不锈钢制品腐蚀原因是拉丝后不锈钢制品表面的富铬氧化膜致密性被破坏;裂纹缝隙的存在,使得水汽和空气(含有氧气)可藏于裂纹缝隙内,为不锈钢的缝隙腐蚀提供良好的基础,从而加速电镀玫瑰金拉丝不锈钢制品腐蚀生锈。