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The development of cobalt molybdenum and cobalt tungsten brush plating electrolytes is described. Their optimum compositions and operating conditions for commercial applications have been determined. The effects of composition, pH, applied voltage, stylus speed and pressure upon deposit composition and efficiency have been investigated. Transmission and Scanning Electron Microscopy have been employed to study the cobalt alloy deposits produced. Evaluation of the wear resistant properties of the cobalt alloys developed in this work was carried out in the laboratory using a pin and disc technique and a simulated hot forging test, and by industrial trials involving the "on site" plating of hot forging dies and cold pressing tools. It was concluded that the electrolytes developed in tl1is work enabled cobalt alloys containing 6% Mo or 8% W to be deposited at 17-20V. Brush plated cobalt deposits possessed a mixed CPU and FCC crystallographic structure at room temperature. The application of 13µm of either of the cobalt alloys resulted in improved wear performance in both pin and disc and simulated hot forging tests. The results of the industrial trials indicated that by the use of these alloys, the life of hot forging dies may be increased by 20-100%. A commercial forging organisation is using electrolytes developed in this work to coat dies prior to forging nimonic alloys. Reductions in forging temperature and improved forging qualities have been reported. Cold pressing tools coated with the alloys showed a reduced tendency to "pick-up" and scoring of the pressed panels. Reports of a reduced need for lubrication of panels before pressing have also been received.

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Thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Faculty of Engineering and the Built Environment, School of Mechanical, Industrial and Aeronautical Engineering, University of the Witwatersrand, Johannesburg, 2017 / Porous structures are increasingly becoming important engineering materials in aerospace, health, cooling of electronics, and several other areas. However, the supply of porous structures in these areas is still not being met because the conventional methods of manufacturing porous structures lack the modern requirements of competitiveness, quality, and exibility. Therefore, new meth- ods are required. One of these methods is the cold spray technology. However, studies do not give clear indications on how the cold spray technology could be used to fabricate porous structures. Consequently, this thesis uses various methods such as the control of cold spray parameters, powder mixtures, and the integration of the cold spray with alloy-de-alloy process to investigate the capability of cold spray technology to manufacture porous structures. The results of this investigation proved that the cold spray technology can be used to fabricate porous structures with varied amount of porosity for a number of applications. / MT 2018

Koo Kai Ming = 具有黑色及灰色外貌的Ti-C, Ti-O和Ti-Zr-O裝飾硬膜之研究 / 古啓明. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / Koo Kai Ming = Ju you hei se ji hui se wai mao de Ti-C, Ti-O he Ti-Zr-O zhuang shi ying mo zhi yan jiu / Gu Qiming. / Acknowledgements --- p.I / Abstract --- p.II / 論文摘要 --- p.IV / Table of Contents --- p.VI / List of Figures --- p.IX / List of Tables --- p.XIII / Chapter CHAPTER 1 --- Introduction --- p.1-1 / Chapter 1.1 --- Overview and objectives --- p.1 -1 / Chapter 1.2 --- Criteria for decorative coatings --- p.1 -2 / Chapter 1.2.1 --- Color appearance --- p.1 -2 / Chapter 1.2.2 --- Corrosion resistance --- p.1 -7 / Chapter 1.2.3 --- Tribological properties --- p.1-7 / Chapter 1.3 --- Coating techniques --- p.1 -8 / Chapter 1.3.1 --- Plasma activated e-beam evaporation --- p.1 -8 / Chapter 1.3.2 --- Cathodic arc deposition (CAD) --- p.1-10 / Chapter 1.3.3 --- Closed field unbalanced magnetron sputtering (CFUBMS) --- p.1-10 / Reference --- p.1-16 / Chapter CHAPTER 2 --- Instrumentation --- p.2-1 / Chapter 2.1 --- Film fabrication --- p.2-1 / Chapter 2.1.1 --- Deposition system --- p.2-1 / Chapter 2.1.2 --- Optical emission control in reactive sputtering --- p.2-3 / Chapter 2.1.3 --- Asymmetric bipolar pulsed DC biasing --- p.2-5 / Chapter 2.1.4 --- Two/Three axis rotation system --- p.2-5 / Chapter 2.1.5 --- Substrate --- p.2-8 / Chapter 2.1.6 --- Deposition procedure --- p.2-9 / Chapter 2.2 --- Characterization --- p.2-10 / Chapter 2.2.1 --- Thickness --- p.2-10 / Chapter 2.2.2 --- Structural information --- p.2-11 / Chapter 2.2.3 --- Chemical compositions and chemical state of the film elements --- p.2-11 / Chapter 2.2.4 --- Amorphous carbon phase structure --- p.2-14 / Chapter 2.2.5 --- Surface morphology --- p.2-14 / Chapter 2.2.6 --- Reflection in the visible light range --- p.2-14 / Chapter 2.2.7 --- Color impression --- p.2-15 / Chapter 2.2.8 --- Film mechanical properties --- p.2-19 / Chapter 2.2.9 --- Scratch resistance (Adhesion) measurement --- p.2-19 / Reference --- p.2-21 / Chapter CHAPTER3 E --- ngineering black decorative coatings with the Ti - C family by reactive ion plating --- p.3-1 / Chapter 3.1 --- Introduction --- p.3-1 / Chapter 3.2 --- Experiment --- p.3-2 / Chapter 3.3 --- Results --- p.3-5 / Chapter 3.3.1 --- Variations in color appearance --- p.3-5 / Chapter 3.3.2 --- Nanoindentation hardness --- p.3-10 / Chapter 3.3.3 --- Scratch resistance --- p.3-14 / Chapter 3.3.4 --- Composition and microstructure --- p.3-17 / Chapter 3.3.5 --- Amorphous carbon structure --- p.3-22 / Chapter 3.4 --- Conclusions --- p.3-31 / Reference / Chapter CHAPTER 4 --- Study on the colorimetric/optical properties of nonstoichiometric Ti - O thin films --- p.4-1 / Chapter 4.1 --- Introduction --- p.4-1 / Chapter 4.2 --- Experiment --- p.4-2 / Chapter 4.3 --- Results and discussions --- p.4-4 / Chapter 4.3.1 --- Variations in color appearance --- p.4-4 / Chapter 4.3.2 --- Nanoindentation hardness --- p.4-9 / Chapter 4.3.3 --- Composition and microstructure --- p.4-13 / Chapter 4.4 --- Conclusions --- p.4-29 / References --- p.4-30 / Chapter CHAPTER 5 --- Doping the nonstoichiometric Ti - O coatings with zirconium --- p.5-1 / Chapter 5.1 --- Introduction --- p.5-1 / Chapter 5.2 --- Experiment --- p.5-1 / Chapter 5.3 --- Results and discussions --- p.5-4 / Chapter 5.3.1 --- Reflectivity and hardness --- p.5-4 / Chapter 5.3.2 --- Composition and microstructure --- p.5-7 / Chapter 5.4 --- "Comparison of the optical properties for Ti-C, Ti-O and Ti-Zr-0" --- p.5-14 / Chapter 5.4.1 --- Black color --- p.5-14 / Chapter 5.4.2 --- Grey color --- p.5-14 / Chapter 5.5 --- Conclusions --- p.5-20 / References / Chapter CHAPTER 6 --- Conclusion --- p.6-1 / Chapter 6.1 --- Future works --- p.6-2

Physical vapour deposition at oblique angles produces coatings that have oriented internal structure, a consequence of self-shadowing and limited diffusion. Structured media have a number of useful properties, including form birefringence which affects the polarization of light. Whilst oblique deposition technology is mature, there is room for further exploration to open up new applications and provide further insight. One door only recently opened is lithographic patterning, and this thesis seeks to map out part of that frontier. Lithography allows rapid replication of a pattern, and is being extended to the nano-scale, via two routes identified as "top-down" and "bottom-up". In this thesis bottom-up processing is pursued as a secondary theme, developing computer programs for investigation of the effect of substrate patterning on growth and subsequent birefringence. The primary focus is the application of top-down patterning to obliquely-deposited polarizing elements, for the production of pixellated polarizing arrays. The growth of obliquely deposited coatings is well understood, and the process has been developed using dynamic substrate rotation to produce several interesting morphologies. Standard results of computer simulations are replicated for illustration. The relationship between morphology and optical properties has been extensively studied from an empirical standpoint, resulting in production of polarizing elements such as retarders, linear- and circular- polarizers. Surprisingly little study has focussed on simulation of the optical anisotropy of arbitrary structures, and here programs are developed for initial prediction of the birefringence of coatings deposited over patterned substrates. Top-down patterning approaches are directly applied to obliquely-deposited dielectric coatings. Standard reactive ion etching protocols are tested, particularly for silicon films, measuring the effect of deposition parameters on etch-rate. Lift-off patterning at significantly oblique angles requires special attention, and an undercut tri-layer process is developed, resulting in patterning of chiral oxide films. Additionally a novel masking process is developed, that allows the production of pixellated arrays comprised of different polarizers in a single coating operation. One such array is used as the essential component in the production of a space-multiplexed array polarimeter.

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Anette M. Karlsson, Dept. of Mechanical Engineering. Includes bibliographical references.