The properties and the effect of operating parameters on nickel plating (review)

The energy required in an electroplating process and the material costs are important considerations in product manufacturing. The most important plating criteria, however, are quality and the uniformity of the deposited metals. The nickel plating process is used extensively for decorative, engineering, and electroforming purposes. Because of the appearance and other properties of the electrodeposited material, nickel deposition can be varied, over a wide range, by controlling the composition and the operating parameters of the plating solution. Decorative applications account for about 80% of the nickel consumed in plating; 20% is consumed for engineering and electroforming purposes. Autocatalytic (electroless) nickel plating processes are commercially important but are outside the scope of this review. In this review, the basic facts of nickel electroplating processes, thickness test and methods, are discussed. The properties of nickel and the different effects of the operating parameters on nickel plating, together with the simulation and design tools, are also reviewed. Simulation tools can help to obtain better plating results. Non-destructive techniques to evaluate the coatings on a microstructural and the technical evaluation with TEM, SEM, XRD and other techniques were also reviewed

Rapid tooling by integration of solid freedom fabrication and electrodepostion

Rapid tooling (RT) techniques based on solid freeform fabrication (SFF) are being studied worldwide to speed up the design-production cycle and thus keep manufacturers at a competitive edge. This dissertation presents a novel rapid tooling process that integrates SFF with electrodeposition to produce molds, dies, and electrical discharge machining (EDM) electrodes rapidly, accurately and cost effectively. Experimental investigation, thermornechanical modeling and analysis, as well as case studies reveal that integration of electroforming with solid freeform fabrication is a viable way for metal tool making. The major research tasks and results of this dissertation study are as follows: Rapid electroforming tooling (RET) process development and understanding. 3D CAD model design, metalization, electroforming, separation and backing are studied through experimental and analytical work. Methods of implementation based on the factors of tooling time, cost, and tooling accuracy are developed. Identification of inaccuracy factors in RET process and methods for improving tooling accuracy. The accuracy of the formed mold cavity or EDM electrode depends upon the material and geometry of the RP part, the properties of the electroformed metal, and process parameters. The thermal stress induced by the burnout process that removes the SFF part from the electroform is one of the major inaccuracy sources. Another one is the deformation generated by solidification of the molten metal that is used to back the electroform to form a solid mold cavity or an EDM electrode. FEM based thermomechanical modeling and analysis of the thermal stress during the SFF part burnout process has been performed. The model is implemented in ANSYS software. It is found that a stepped thermal load for the pattern burnout generates much smaller thermal stress than a ramped thermal load. The thermal stress is largely reduced when an SFF part is designed as a hollow or shelled structure\u27, or when the electroform thickness is increased. The wall thickness of SFF part is determined by two criteria. The wall thickness must be thin enough to guarantee that the thermal stresses are smaller than the yield strength of the electroformed metal. On the other hand, the wall thickness must also be large enough to resist the electroforming stress during the electroforming process. The electroform thickness is related to tooling time, cost and tool strength. Strain gage based thermal stress measurements demonstrate that the results obtained from the experiment accurately match the results obtained from the FEM-based thermornechanical analysis model. Thus the model can be used to predict the thermal stress induced during the burnout process. The established thermomechanical model and FEM based numerical simulation provide an effective method that determines the geometry of the SFF part and the electroform thickness for minimizing the manufacturing time and cost while satisfying the tooling accuracy requirement

Influence of Operation Parameters on Metal Deposition in Bright Nickel-plating Process

Bright nickel deposits were electrolytically applied on steel in the nickel Watts bath. The effect of some operational parameters on metal deposition in bright nickel plating was investigated. The investigation indicated that the weight of bright nickel deposited on metal during the process of electroplating was affected by plating temperature, voltage, current density, plating bath pH and plating time. The study established that the deposition of best bright nickel was obtained at a plating temperature of 56 oC, current density of 6 A/dm2 and plating time of 18 minutes. Brightener is used in applications requiring outstanding appearance with minimum thickness of applied nickel plating. It can also be used for heavy deposit applications because it exhibits unparalleled ductility and low stress. Brightener was used in this study to determine the best nickel plating in the process. Boric acid was added for fixing the bath pH. The compositions of the brightener and nickel solution used are included in the tex

Electrodeposition of nickel-copper alloys and nickel-copper-alumina nanocomposites into deep recesses for MEMS

Electrodeposition is an important component in the fabrication of micro electro mechanical systems (MEMS). Nickel is the most commonly used material to produce three dimensional microstructures and few material alternatives have been demonstrated. In this dissertation, electrodeposited Ni-Cu alloys and nanocomposites are investigated as possible replacements for nickel in microsystems. Ni-Cu alloys are attractive for their corrosion resistance, magnetic and thermophysical properties. Alumina nanoparticulates included into metal matrices improve hardness and tribology of deposits. The Ni-Cu alloys and Ni-Cu-g-Al2O3 nanocomposites were electrodeposited from a citrate electrolyte, both at low and high pH. Electrodeposition experiments were performed in recessed microelectrodes 500 mm thick and also on rotating cylinder electrodes. Recessed electrodes were produced by x-ray synchrotron radiation at the Center for Advanced Microstructures and Devices (CAMD). The concentration of copper in the electrolyte was much lower than the nickel concentration to ensure diffusional control. In the microstructure, the copper concentration in the deposit increased along the height, leading to a graded microstructure. This is indicative of a changing boundary layer and a transient process. The addition of alumina nanoparticles in the electrolyte led to an enhancement of copper concentration in the deposit, resulting from an enhancement of its mass transport rate. Two numerical models were developed to describe the steady state and non-steady state deposition processes. The effect of alumina on the metal deposition partial currents and side reactions is simulated by using a surface coverage model. Rotating cylinder experiments and simulation are used to extract kinetic and diffusional parameters of the nickel and copper species. On the recessed electrodes a transient model taking into account the time dependence of concentration is developed. The rise of surface pH, concentration gradients and buffering effects of the complexing agents are explained by the non-steady state model

Integration of e-business strategy for multi-lifecycle production systems

Internet use has grown exponentially on the last few years becoming a global communication and business resource. Internet-based business, or e-Business will truly affect every sector of the economy in ways that today we can only imagine. The manufacturing sector will be at the forefront of this change. This doctoral dissertation provides a scientific framework and a set of novel decision support tools for evaluating, modeling, and optimizing the overall performance of e-Business integrated multi-lifecycle production systems. The characteristics of this framework include environmental lifecycle study, environmental performance metrics, hyper-network model of integrated e-supply chain networks, fuzzy multi-objective optimization method, discrete-event simulation approach, and scalable enterprise environmental management system design. The dissertation research reveals that integration of e-Business strategy into production systems can alter current industry practices along a pathway towards sustainability, enhancing resource productivity, improving cost efficiencies and reducing lifecycle environmental impacts. The following research challenges and scholarly accomplishments have been addressed in this dissertation: Identification and analysis of environmental impacts of e-Business. A pioneering environmental lifecycle study on the impact of e-Business is conducted, and fuzzy decision theory is further applied to evaluate e-Business scenarios in order to overcome data uncertainty and information gaps; Understanding, evaluation, and development of environmental performance metrics. Major environmental performance metrics are compared and evaluated. A universal target-based performance metric, developed jointly with a team of industry and university researchers, is evaluated, implemented, and utilized in the methodology framework; Generic framework of integrated e-supply chain network. The framework is based on the most recent research on large complex supply chain network model, but extended to integrate demanufacturers, recyclers, and resellers as supply chain partners. Moreover, The e-Business information network is modeled as a overlaid hypernetwork layer for the supply chain; Fuzzy multi-objective optimization theory and discrete-event simulation methods. The solution methods deal with overall system parameter trade-offs, partner selections, and sustainable decision-making; Architecture design for scalable enterprise environmental management system. This novel system is designed and deployed using knowledge-based ontology theory, and XML techniques within an agent-based structure. The implementation model and system prototype are also provided. The new methodology and framework have the potential of being widely used in system analysis, design and implementation of e-Business enabled engineering systems