Electrodeposition method is used to deposit diamond-like carbon (DLC) films on copper substrates via anodic oxidation at low temperature. These films are characterized using Raman spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. Homogeneity of these films is studied using Raman spectroscopy and scanning electron microscopy. Scotch tape peel tests indicate adherent film on copper substrate. Carbon phase transformation is studied using thermal annealing experiments in conjunction with Raman spectroscopy and scanning electron microscopy. A cathodic electrochemical method is also studied to deposit diamond-like carbon films on copper substrates. However, films deposited by the cathodic route have poor adhesion and quality compared to anodically deposited films. It is also possible to grow diamond phase on copper substrates using acetylene in liquid ammonia via electrodeposition route. An electrochemical method is proposed for boron doping into DLC films.

Adherent Cu films were electrodeposited onto polycrystalline W foils from purged solutions of 0.05 M CuSO4 in H2SO4 supporting electrolyte and 0.025 M CuCO3∙Cu(OH)2 in 0.32 M H3BO3 and corresponding HBF4 supporting electrolyte, both at pH = 1. Films were deposited under constant potential conditions at voltages between -0.6 V and -0.2 V vs Ag/AgCl. All films produced by pulses of 10 s duration were visible to the eye, copper colored, and survived a crude test called "the Scotch tape test", which stick the scotch tape on the sample, then peel off the tape and see if the copper film peels off or not. Characterization by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray photon spectroscopy (XPS) confirmed the presence of metallic Cu, with apparent dendritic growth. No sulfur impurity was observable by XPS or EDX. Kinetics measurements indicate that the Cu nucleation process in the sulfuric bath is slower than in the borate bath. In both baths, nucleation kinetics do not correspond to either instantaneous or progressive nucleation. Films deposited from 0.05 M CuSO4/H2SO4 solution at pH > 1 at -0.2 V exhibited poor adhesion and decreased Cu reduction current. In both borate and sulfate baths, small Cu nuclei are observable by SEM upon deposition at higher negative overpotentials, while only large nuclei (~ 1 micron or larger) are observed upon deposition at less negative potentials.

Electrodeposition is a novel method for fabrication of diamond-like carbon (DLC) films on metal substrates. In this work, DLC was electrochemically deposited on different substrates based on an anodic oxidation cyclization of acetylene in liquid ammonia. Successfully anodic deposition was carried out for DLC onto nickel substrate at temperatures below -40°C. Comparative studies were performed on a series of different carbon sources (acetylene, sodium acetylide, and a mixture of acetylene and sodium acetylide). The films were characterized using a variety of methods including Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), XPS valence band spectra, and/or scanning electron microscopy (SEM). Raman spectroscopy is used as a bench mark technique to verify the presence of deposited DLC films, to access the films homogeneities, and to provide the ratio of the different carbon phases, mainly disordered graphite (D) and graphite (G) phases in the films. A combination of the Raman with FTIR and valence band spectra analysis allowed the distinction between hydrogenated DLC and unhydrogenated DLC films. Three different kinds of DLC [(1) hydrogenated DLC (a-C:H); (2) tetrahedral hydrogenated DLC (ta-C:H); and (3) graphitic-like DLC] were deposited depending upon the deposition conditions and substrates. Temperature and current density are the most important parameters to govern the quality of the deposited films, where adding of acetylide into the electrolyte led to films with a higher degree of graphitic phases. The proposed mechanism for acetylene anodic oxidation does not involve direct electron transfer but electrochemical cyclization of acetylene radical cations and hydrogen abstraction at the termination steps. Sodium acetylide, however, dissociates to an acetylenic ion, C2H-, in liquid ammonia. The electrochemistry heterogeneity also leads to island and two-dimensional (2D) nucleation growth of DLC films. Different bond formations of metal to carbon and different chemisorptions of acetylene on metal play important roles in governing the film properties. Using mixed C2HNa and C2H2 as electrolyte, polycrystalline diamond and hexagonal diamond are formed on Mo and stainless steel, respectively. This is the first time to report that polycrystalline diamond can be grown electrochemically at temperature below -40ºC. The preliminary studies on substrate pretreatment with diamond powder and SiC 600 are studied. The effect of the substrate on the film quality for the electrodeposited DLC films described herein is similar to that for diamond deposition via chemical vapor deposition (CVD).

In the electroplating process, dissolved metal cations are reduced by electrical current to a form a coherent metal coating on an electrode. Therefore, electroplating is primarily applied to modify the surface properties of an object (e.g. abrasion and wear resistance, corrosion protection, lubricity, aesthetic qualities, etc.), but also be applied to build up high aspect ratio structures on undersized parts or to form devices by electroforming. Compared with other common MEMS (microelectromechanical systems) metal device fabrication techniques, such as vapor depositions, electroplating has several outstanding advantages. First, the fabrication process is cost-efficient because electroplating process can be set up easily without complex and expensive facilities. Second, the fabrication condition of electroplating is less demanding and does not require high temperature or low pressure. Furthermore, the process is applicable to making various features consisting of nanometer to millimeter scale particles, wires, and films. Thus, in this thesis, based on the design requirements of electrospray emitters and environmental sensors, the electroplating method was chosen to fabricate micro- and nanoscale structures for such applications. Electrospray is an atomization technique by which an electrically conductive liquid through a small capillary is charged with high voltage (kV) and ejected to a ground electrode. To minimize the electric field edge effect of the emitter nozzles to get even electro-hydrodynamic pulling force on the liquid among the nozzles and minimize variation from one emitter to another, the device needs to have the viscous pressure drop across each nozzle dominant over the electro-hydrodynamic pulling force. Therefore, embedded structures that can create high flow impedance are desirable to achieve uniform feeding of low flow rate of liquid to each emitter. We designed and fabricated in-plane metallic electrospray devices with an embedded array of micropillars within a microchannel by photolithography and electroplating. The novelty of the proposed research lies in its embedded flow restriction structure, scalability, and ease of fabrication. The formation of jets as well as the flexing capability of the emitter was achieved. The other application of electroplating was demonstrated in the fabrication of environmental sensors. Utilizing a pulsed electroplating method, Co-Cu metal alloy films were prepared and Cu was selectively etched to fabricate nanoporous electrodes which could be used to measure both absolute levels and changes of phosphate concentration in aqueous environments. The formation of cobalt phosphate compound could be used for the detection. The increased surface area and relatively simple fabrication protocols make the proposed method attractive and promising for many environmental sensing applications.

No description available.

Additive manufacturing introduces a new design paradigm that allows the fabrication of geometrically complex parts that cannot be produced by traditional manufacturing and assembly methods. Using a cellular heat exchanger as a motivational example, this thesis investigates the creation of a hybrid manufacturing approach that combines selective laser sintering with an electroforming process to produce complex, hollow, metal geometries. The developed process uses electroless nickel plating on laser sintered parts that then undergo a flash burnout procedure to remove the polymer, leaving a complex, hollow, metal part. The resulting geometries cannot be produced directly with other additive manufacturing systems. Copper electroplating and electroless nickel plating are investigated as metal coating methods. Several parametric parts are tested while developing a manufacturing process. Copper electroplating is determined to be too dependent on the geometry of the part, with large changes in plate thickness between the exterior and interior of the tested parts. Even in relatively basic cellular structures, electroplating does not plate the interior of the part. Two phases of electroless nickel plating combined with a flash burnout procedure produce the desired geometry. The tested part has a density of 3.16g/cm3 and withstands pressures up to 25MPa. The cellular part produced has a nickel plate thickness of 800µm and consists of 35% nickel and 65% air (empty space). Detailed procedures are included for the electroplating and electroless plating processes developed. / Master of Science

by Wong Suk Ying. / Thesis submitted in: November 2001. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 144-157). / Text in English; abstracts in English and Chinese. / by Wong Suk Ying. / Acknowledgments --- p.i / Abstract --- p.ii / Contents --- p.v / List of Figures --- p.x / List of Tables --- p.xvi / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 1.1 --- Electroplating Industry in Hong Kong --- p.1 / Chapter 1.1.1 --- Typical stages in electroplating process --- p.1 / Chapter 1.1.1.1 --- Pre-treatment --- p.1 / Chapter 1.1.1.2 --- Electroplating --- p.3 / Chapter 1.1.1.3 --- Post-treatment --- p.3 / Chapter 1.1.2 --- Typical characteristics of wastestreams from electroplating industry --- p.3 / Chapter 1.2 --- Chemical Specific Approach against Toxicity Based Approach --- p.6 / Chapter 1.3 --- Ecotoxicological Study on Electroplating Effluent --- p.7 / Chapter 1.4 --- Toxicity Identification Evaluation --- p.8 / Chapter 1.4.1 --- Phase I: Toxicity Characterization --- p.9 / Chapter 1.4.2 --- Phase II: Toxicity Identification --- p.10 / Chapter 1.4.3 --- Phase III: Toxicity Confirmation --- p.12 / Chapter 1.5 --- Toxicity Identification Evaluation on Electroplating Effluent --- p.14 / Chapter 1.6 --- Selection of Organisms for Bioassays --- p.15 / Chapter 1.6.1 --- Organism used for toxicity identification evaluation --- p.17 / Chapter 2. --- OBJECTIVES --- p.20 / Chapter 3. --- MATERIALS AND METHODS --- p.21 / Chapter 3.1 --- Source of Samples --- p.21 / Chapter 3.2 --- Toxicity Identification Evaluation: Phase I Baseline Toxicity Test --- p.21 / Chapter 3.2.1 --- Microtox® test --- p.23 / Chapter 3.2.2 --- Growth inhibition test of a marine unicellular microalga Chlorella pyrenoidosa CU-2 --- p.25 / Chapter 3.2.3 --- Survival test of a marine amphipod Hylae crassicornis --- p.28 / Chapter 3.2.4 --- Survival test of a marine shrimp juvenile Metapenaeus ensis --- p.31 / Chapter 3.3 --- Toxicity Identification Evaluation: Phase I Toxicity Characterization --- p.34 / Chapter 3.3.1 --- pH adjustment filtration test --- p.35 / Chapter 3.3.2 --- Aeration test --- p.36 / Chapter 3.3.3 --- C18 solid phase extraction test --- p.37 / Chapter 3.3.4 --- EDTA chelation test --- p.38 / Chapter 3.3.5 --- Graduated pH test --- p.40 / Chapter 3.4 --- Toxicity Identification Evaluation: Phase II Toxicity Identification --- p.41 / Chapter 3.4.1 --- Filter extraction test --- p.41 / Chapter 3.4.2 --- Total metal content analysis --- p.42 / Chapter 3.5 --- Toxicity Identification Evaluation: Phase III Toxicity Confirmation --- p.43 / Chapter 3.5.1 --- Chemicals --- p.44 / Chapter 3.5.2 --- Mass balance test --- p.44 / Chapter 3.5.3 --- Spiking test --- p.44 / Chapter 4. --- RESULTS --- p.46 / Chapter 4.1 --- Chemical Characteristics of the Electroplating Effluent Samples --- p.46 / Chapter 4.2 --- Toxicity Identification Evaluation: Phase I Baseline Toxicity --- p.46 / Chapter 4.2.1 --- Toxicity of electroplating effluent samples on Microtox® test --- p.46 / Chapter 4.2.2 --- Toxicity of electroplating effluent samples on growth inhibition test of microalga Chlorella pyrenoidosa CU-2 --- p.46 / Chapter 4.2.3 --- Toxicity of electroplating effluent samples on survival test of amphipod Hyale crassicornis --- p.52 / Chapter 4.2.4 --- Toxicity of electroplating effluent samples on survival test of shrimp juvenile Metapenaeus ensis --- p.52 / Chapter 4.3 --- Toxicity Identification Evaluation: Phase I Toxicity Characterization --- p.52 / Chapter 4.3.1 --- Toxicity Characterization of electroplating effluent samples using Microtox® test --- p.56 / Chapter 4.3.2 --- Toxicity Characterization of electroplating effluent samples using microalgal growth inhibition test of Chlorella pyrenoidosa CU-2 --- p.59 / Chapter 4.3.3 --- Toxicity Characterization of electroplating effluent samples using survival test of amphipod Hyale crassicornis --- p.65 / Chapter 4.3.4 --- Toxicity Characterization of electroplating effluent samples using survival test of shrimp juvenile Metapenaeus ensis --- p.68 / Chapter 4.4 --- Toxicity Identification Evaluation: Phase II Toxicity Identification --- p.73 / Chapter 4.4.1 --- Metal analysis on the electroplating effluents --- p.75 / Chapter 4.4.2 --- Effect of filter extraction test on toxicity recovery of the electroplating effluent samples --- p.75 / Chapter 4.4.2.1 --- Microtox® test --- p.75 / Chapter 4.4.2.2 --- Growth inhibition test of microalga Chlorella pyrenoidosa CU-2 --- p.75 / Chapter 4.4.2.3 --- Survival test of amphipod Hyale crassicornis --- p.81 / Chapter 4.4.2.4 --- Survival test of shrimp juvenile Metapenaeus ensis --- p.90 / Chapter 4.4.3 --- Effect of filter extraction test on metal ions recovery of the electroplating effluent samples --- p.90 / Chapter 4.5 --- Toxicity Identification Evaluation: Phase III Toxicity Confirmation --- p.96 / Chapter 4.5.1 --- Mass balance test results on Microtox® test --- p.96 / Chapter 4.5.2 --- Mass balance test results on survival test of amphipod Hyale crassicornis --- p.104 / Chapter 4.5.3 --- Spiking test results on Microtox® test --- p.106 / Chapter 4.5.4 --- Spiking test results on survival test of amphipod Hyale crassicornis --- p.113 / Chapter 5. --- DISCUSSION --- p.118 / Chapter 5.1 --- Toxicity Identification Evaluation: Phase I Baseline Toxicity --- p.118 / Chapter 5.2 --- Toxicity Identification Evaluation: Phase I Toxicity Characterization --- p.119 / Chapter 5.2.1 --- pH adjustment filtration test --- p.119 / Chapter 5.2.2 --- Aeration test --- p.120 / Chapter 5.2.3 --- C18 solid phase extraction test --- p.120 / Chapter 5.2.4 --- EDTA chelation test --- p.120 / Chapter 5.2.5 --- Graduated pH test --- p.121 / Chapter 5.3 --- Toxicity Identification Evaluation: Phase II Toxicity Identification --- p.122 / Chapter 5.3.1 --- Metal analysis on the electroplating effluents --- p.122 / Chapter 5.3.2 --- Effect of filter extraction test on toxicity and metal ions recovery of the electroplating effluent samples --- p.123 / Chapter 5.3.3 --- Comparison between the concentrations of the metal ions in the electroplating effluent samples with the Technical Memorandum on standards for effluent discharged --- p.124 / Chapter 5.3.4 --- Comparison between the concentrations of the metal ions in the electroplating effluent samples with the toxicity of the metal ions reported in the literature --- p.124 / Chapter 5.3.4.1 --- Microtox® test --- p.126 / Chapter 5.3.4.2 --- Microalga --- p.126 / Chapter 5.3.4.3 --- Amphipod --- p.126 / Chapter 5.3.4.4 --- Shrimp --- p.126 / Chapter 5.4 --- Toxicity Identification Evaluation: Phase III Toxicity Confirmation --- p.131 / Chapter 5.4.1 --- Mass balance test on Microtox® test --- p.132 / Chapter 5.4.2 --- Mass balance test on survival test of amphipod Hyale crassicornis --- p.133 / Chapter 5.4.3 --- Spiking test on Microtox® test --- p.133 / Chapter 5.4.4 --- Spiking test on survival test of amphipod Hyale crassicornis --- p.134 / Chapter 5.5 --- Toxicity of the Metal Ions Identified as the Toxicants in the Electroplating Effluent --- p.135 / Chapter 5.5.1 --- Copper --- p.135 / Chapter 5.5.2 --- Nickel --- p.137 / Chapter 5.5.3 --- Zinc --- p.138 / Chapter 5.6 --- Summary --- p.140 / Chapter 6. --- CONCLUSIONS --- p.142 / Chapter 7. --- REFERENCES --- p.144 / Chapter 7.1 --- APPENDIXES --- p.158

Since semiconductor fabrication processes require numerous steps, cost and yield are critical concerns. In-situ monitoring is therefore vital for process control. However, this goal is currently restricted by the shortage of available sensors capable of performing in this manner. The goal of this research therefore, was to investigate the use of acoustic signals for monitoring and control of semiconductor fabrication equipment and processes. Currently, most methods for process monitoring (such as optical emission or interferometric techniques) rely on "looking" at a process to monitor its status. What was investigated here involved "listening" to the process. Using acoustic methods for process monitoring enhances the amount and sensitivity of data collection to facilitate process diagnostics and control. A silicon acoustic sensor was designed, fabricated, and implemented as a process monitor. Silicon acoustic sensors are favorable because of their utilization of integrated circuit and micromachining processing techniques; thus, enabling miniature devices with precise dimensions, batch fabrication of sensors, good reproducibility, and low costs. The fabricated sensor was used for in-situ monitoring of nickel-iron electrochemical deposition processes. During this process, changes occur in its plating bath as the alloy is being deposited. It is known that changes in the process medium affect the acoustic response. Thus, the sensor was implemented in an electroplating set-up and its response was observed during depositions. By mapping the sensor response received to the film thickness measured at certain times, a predictive model of the plated alloy thickness was derived as a function of sensor output and plating time. Such a model can lead to real-time monitoring of nickel-iron thickness.

Silver is a precious metal that has traditionally been used for jewellery and money. It also possesses desirable properties such as being corrosion resistant and having good electrical conductivity, resulting in its use for industrial applications. Furthermore, it is also recognised for its tribological properties in non-cost prohibitive applications. Silver can be used as a surface coating and can be deposited using an electroplating process. The utilisation of silver as a surface coating is advantageous and sustainable, as the substrate material properties are enhanced while usage of silver is kept to a minimum. On the other hand, electroplating has been used for over a century. It is a process which is able to produce a layer of uniform and dense coating that adheres well to the substrate metal, thus modifying the properties of the substrate. It benefits from being relatively low cost and is scalable. Silver is electroplated onto stainless steel threaded compression fittings to prevent galling. Traditional silver electroplating, which contains the use of cyanide as a complexing agent in the electroplating bath, is still in use within industry, even to this day. Cyanide, in its various forms can be poisonous, toxic and even lethal, which presents a risk during the silver electroplating process. Furthermore, the toxic wastes created during the cyanide silver electroplating process are detrimental to the environment. The aim of this work is to develop a self-lubricating non-cyanide silver PTFE composite coating suitable for use in threaded compression fittings of the ferruled type. The composite can be considered self-lubricating when a concentration of 8% or more by volume of the self-lubricating PTFE substance is incorporated. My original contribution to knowledge is firstly the successful development and characterisation of a self-lubricating non-cynanide Ag-PTFE coating on stainless steel without a strike resulting in improved CoF of 0.06 from the CoF of 0.6 based on an unlubricated surface. Secondly is the application of a non-cyanide Ag-PTFE MMC for threaded compression fittings. Thirdly is the characterisation of the make-up process of threaded compression fittings through the proposed use of the torque-angle slope in assessing coating performance for threaded compression fittings during make-up. Conclusions that can be drawn for the work are that the performance non-cyanide Ag-PTFE coating exceeded the performance of the pure Ag coating made using the same non-cyanide process. Moreover, the performance of the Ag-PTFE coating shows promising results when compared to the performance of the commercial silver cyanide coating. As a viable replacement to the current silver cyanide process, the self-lubricating non-cyanide Ag-PTFE coating, will improve the working conditions and have a positive contribution to the environment. Moreover, a thinner coating with has the potential to reduce raw material usage and electroplating waste disposal costs.

No description available.