Industrial Metal Finishing for Corrosion Control

Industrial Metal Finishing, which includes electro-deposition of metals and alloys, electroless plating, immersion plating, chemical and electropolishing of metals, anodizing etc. form a major component of surface engineering. Corrosion protection is one main reason for the existence of Industrial Metal finishing Although these processes began for decorative and aesthetic purposes, their contribution to corrosion prevention and engineering applications, especially in electronics,aerospace, auto-motive and agriculture industries is markedly increasing. The evolution of industrial metal finishing from an art to a science has been a gradual process. The ABC of corro-sion protection, principle and mechanism, and the latest developments in terms of 6 Es (Environment-friendly, Econ-omical, Excellent. Energy -saving, Extremely fast, and Expertsystem ) have been briefly introduced. Relevant references have been cited for ease of access to the original and detailed literature

Maintaining the consistencies in electropolishing results by characterizing the polishing bath state as a function of its instant key properties

Electropolishing is an advanced industrial metal finishing in practice commercially since the mid-20th century, to treat the metals with electricity and industrial chemicals. The process has grown remarkably in the last 50 years; the medical and pharmaceutical industry's growth is a strong driving force for the electropolishing industry now. The work detailed in this thesis focuses on maintaining the uniformities in electropolishing qualities by specifying the polishing bath state as an approximation of its fundamental properties. In light of the scarcity of precise information regarding the techniques to keep the electropolishing process in control as the polishing bath ages, this research will present the organized data for an ageing bath. A mathematical model constructed from the vital polishing bath properties measured on-the-spot is used to quantify the polishing deliverables concerning surface roughness as a function of its immediate critical bath properties. The work results demonstrate that the model can anticipate the polishing capabilities under selected polishing conditions for a given polishing bath state, fresh, aged or regenerated. This model-based technique reduces the trial and error-based efforts the polishing industry takes to figure out the suitable operating parameters to deliver the polishing results when the aged bath is no longer efficient

Assessment of Daphnia magna as a toxicity bioindicator for wastewaters

Toxicity tests on complex wastewater effluents have been considered as an important complement to emission limit values (ELV) based on physico-chemical and microbiological parameters in recent years. However, relatively few studies have been conducted so far evaluating the toxicity of effluents with aquatic organisms, and it remains unclear which test species should be used in such evaluations. The first aim of this dissertation was therefore to assess the potential of the crustacean Daphnia magna as a bioindicator for the toxicity of a domestic effluent disinfected with peracetic acid (PAA), a disinfect that has received increasing attention in recent years as an alternative disinfectant for chloride. To this end, bioassays were performed with D. magna on the secondary effluent from the WWTP of Beirolas, with and without disinfection by 5 mg.L-1, 10 mg.L-1 and 15 mg.L-1 PAA. These PAA concentrations were selected since they were shown in a parallel MSc study to have high removal efficacy of coliform and faecal bacteria. Exposure to the secondary effluent without disinfection caused no mortality or immobility on the organisms. Although the disinfected effluent adhered to all the standards set in current Legislation, even the lowest PAA concentration resulted in 100% daphnid mortality within 48h. Subsequently, efforts should be made to evaluate whether lower PAA concentrations or a longer residual time after PAA treatment may ensure disinfection efficacy without exerting toxicity to aquatic organisms like D. magna. The second aim of this dissertation was to compare the sensitivity of D. magna to wastewater with that of other species commonly used in bioassays. This was done to evaluate which test species are the most appropriate for use in wastewater toxicity testing. To this end, a literature search was conducted by collecting data from papers where the toxicity of effluents was tested to D. magna and at least one other species. This thus allowed to evaluate the relative tolerance (Trel) of these species as compared to D. magna. The taxonomic groups that appeared to be more sensitive to effluents than D. magna were bacteria and rotifers. On the other hand, macrophytes, insects and fish were found to be generally less sensitive than D. magna. Since no single species was aways the most sensitive species to the wide range of effluents (e.g. different sources, compositions and sampling periods) included in the dataset, a test battery including species from different taxonomic groups is recommended for effluent testing

Reverse Osmosis Optimization

This technology evaluation was prepared by Pacific Northwest National Laboratory on behalf of the U.S. Department of Energy’s Federal Energy Management Program (FEMP). ¬The technology evaluation assesses techniques for optimizing reverse osmosis (RO) systems to increase RO system performance and water efficiency. This evaluation provides a general description of RO systems, the influence of RO systems on water use, and key areas where RO systems can be optimized to reduce water and energy consumption. The evaluation is intended to help facility managers at Federal sites understand the basic concepts of the RO process and system optimization options, enabling them to make informed decisions during the system design process for either new projects or recommissioning of existing equipment. This evaluation is focused on commercial-sized RO systems generally treating more than 80 gallons per hour.

Estudo do processo de anodização por voltagem modulada do titanio e da liga Ti-6Al-7Nb

Orientadores : Celia Marina de Alvarenga Freire, Margarita Ballester CardonaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia MecanicaResumo: As características protetoras das superficies de aços galvanizados são geralmente intensificadas através da passivação por cromo hexavalente (Cr+6). Porém, por ser este um elemento tóxico, vários estudos visando a substituição do procedimento de cromatização vêm sendo realizados. As resinas de polissiloxanos e materiais híbridos organo-inorgânicos preparados pelo processo sol-gel, podem vir a ser um excelente substituinte ao processo de cromatização. Neste trabalho, filmes híbridos organo-inorgânico e filmes de silicone foram aplicados em aço galvanizado e em camadas de Zn-Fe. Os revestimentos foram então avaliados através de Espectroscopia de Impedância Eletroquímica. Os dados obtidos pela Espectroscopia foram modelados através de um circuito equivalente, permitindo a obtenção dos parâmetros eletroquímicos para os sistemas avaliados. Além disso, o potencial em circuito aberto, para os diferentes sistemas, foi monitorado durante processo de desgaste em sistema pino-disco em solução de NaCl 3%. Os revestimentos foram comparados em termos de resistência à corrosão e coeficiente de fricção. Os resultados mostram um bom desempenho para os revestimentos como protetores de corrosão e o comportamento destes mostraram-se dependente do tipo de revestimento metálico que foi aplicado no açoAbstract: Chromating pre-treatments have been widely used to improve galvanized steel corroslOn resistance. However, due to the high toxicity of chromate ions, chromatation pre-treatments tend to be banned and, in last years, altemative coating systems are under investigation. Recently, polysiloxanes and hybrids materiais by the sol-gel process have been extensively investigated. These materiaIs may be considered as promising substitutes for chromatation pre-treatments. In this work organic-inorganic hybrid materiais and silicone films have been prepared and applied on galvanized steel and on steel electroplated with a Zn-Fe alloy. Electrochemical Impedance Spectroscopy (EIS) was used as a technique for the evaluation of the corrosion mechanisms of the coating systems and the EIS data was fitted to an equivalent circuit from which the electrochemical parameters were obtained. AdditionaIly, the evolution of open circuit potential, for samples, was monitored during altemative reciprocating sliding against an alumina pin in a 3% NaCI solution. The behaviour of the coatings has been compared in terms of corrosion potential and friction coefficient. Results show the protective character of the hybrid films and silicon resin films, when compared with uncovered specimens. The overaIl performance of the coating systems appears to be highl dependent on the type of metaIlic coating applied to the steelMestradoMateriais e Processos de FabricaçãoMestre em Engenharia Mecânic

Some aspects of the high speed electrodeposition of metals

The literature concerning the fast electrodeposition of metals has been reviewed with particular attention to the electrodeposition of nickel. A study of the electrodeposition of nickel has been carried out in concentrated Ni sulphamate solutions at 50-70°C in parallel plate cells at Reynolds numbers of up to 15,000. The cell design was substantiated by a preliminary study of the electrodeposition of copper. Additional studies have been made of current distribution in both the nickel and acid copper systems using segmented electrodes. Additional studies of mass transport have been made in the nickel system, as have polarisation studies. It has been shown that in the case of acid copper the system performs under mass transport control and that the current distribution is as expected under these conditions. [continues…

Prospective Life Cycle Assessment in Surface Engineering: Case Studies on a Novel Thermal Spray Coating System and a Novel Coating Removal Method

Life Cycle Assessment (LCA) is a framework for quantifying the potential environmental impact of products from raw material extraction through materials processing, manufacturing, distribution, use, and end-of-life. Prospective LCA estimates the future environmental impacts of emerging technologies. It can be used to support eco-design, such as green surface engineering. Prospective LCA is used in this thesis to compare emerging surface engineering and incumbent technologies. The first case study compares a novel thermal sprayed multi-layered alumina-nickel chromium resistive heating coating to heat tracing cables for pipe freeze protection. The coating system’s impacts are higher for fabrication but lower for use, making it environmentally preferable in areas with colder climates and non-renewable electricity mixes. Specific life expectancy and efficiency improvements were identified to achieve environmentally preferability in most locations. Alternate strategies include reducing the environmental impact of fabrication by using alternate materials or deposition processes and developing strategies for recovering and recycling coating materials. The second case study compared a novel pulse water jet (PWJ) technology with alkaline electrochemical cleaning for removing hard chromium from aircraft landing gear. If the PWJ system can be designed to remove the coating from workpieces with complex geometry, its environmental impact is expected to be lower due to its lower electricity consumption, chemical use, and waste management. The case studies demonstrate the value of using prospective LCA during early development, adopting a range of techniques for addressing uncertainty, and breaking down the results to provide developers with strategies for reducing environmental impact