Corrosion and fouling are considered major factors affecting the performance of water-steam cycles (WSC). Flow-accelerated corrosion (FAC), present in feed and condensate systems, is a well known corrosion mechanism, eroding and dissolving the protective magnetite layers. Fouling of the boiler, by suspended magnetite particles, is partly controlled by forces arising due to surface charging. Film forming amines (FFA) are gaining acceptance as means to control FAC. However, its performance in low pH regions is unknown. In addition, despite FFA being a surfactant, its effect on the colloidal magnetite surface charge and point of zero charge (pzc) are unknown. This research set out to determine the effect of FFAs on the formation of a protective magnetite layer and its resistance against acidic FAC, and to determine the effect of FFAs on the surface charge of colloidal magnetite. This study focused on two FFAs, Octadecylamine (ODA) and Oleyl Propylenediamine (OLDA). In 48h 230-250 ºC immersion corrosion tests magnetite layers were formed on C1010 coupons, inside a high pressure high temperature autoclave under different treatments: untreated (blank), 2ppm ODA and 2ppm Ammonia, 2ppm OLDA and 2ppm Ammonia, and only 2ppm Ammonia. 48h 150 ºC re-immersion corrosion tests were performed to test the magnetite layer performance under acidic (acetate 0.08ppm) FAC. After the corrosion tests, the layers were verified using XRD, EDS + SEM and Weigh-loss measurements. Potentiometric titrations were employed to measure the proton induced surface charge of magnetite particles (10g/L) at an ionic strength of 0.01, and 0.1 mol/kg (KNO3) in the presence or absence of ODA, or OLDA (2ppm) over a wide pH range, at 25, and 150 ºC. This gave the magnetite surface charge density curves. The pzc was determined using the inflection point of titrations (pHinfl) and common intersection point (pHcip). XRD confirmed the presence of magnetite layers on all coupons after the immersion and re-immersion tests. The SEM measured magnetite layer decrease after the re-immersion tests was: 19.1%, 14.5%, 8.6%, and 23.3% for blank, ODA, OLDA, and ammonia treatment respectively. Weight loss determined corrosion rates taken over both immersion and re-immersion tests were: 0.070, 0.057, 0.060, and 0.073 mm/y for blank, ODA, OLDA, and ammonia treatment respectively. All magnetite surface charge density curves were unaffected by the presence of ODA, and OLDA, except for ODA at 0.1 mol/kg KNO3 and 25 ºC, which resulted in a raised/neutralized surface charge density curve in the alkaline pH region. Magnetite layers formed under ODA, and OLDA additions were smoother, thinner, and more uniform compared to layers formed under an ammonia only chemistry, and blank chemistry. Layers formed under the ODA, and OLDA chemistries were better resistant against acidic FAC and offered better protection, in terms of corrosion rate. At the applied concentration ratio, and ionic strength of 0.01M, ODA, and OLDA did not affect the magnetite colloid surface charge over pH. However, both caused magnetite particles to agglomerate. At higher ionic strengths of 0.1M, ODA neutralized the magnetite surface charge in the alkaline region.

Conversion coatings are generally required to enhance organic coating adhesion and corrosion resistance on galvanized steel. Until a few decades ago, chromate conversion coatings were the most common conversion coatings in the industry owing to their exceptional performance in this regard. However, the adverse effects associated with hexavalent chromium as found in chromate conversion coatings and certain corrosion inhibitor pigments are now widely known. As a result, various initiatives have been deployed around the globe to restrict and regulate the use of hexavalent chromium. Finding suitable alternatives for chromate conversion coatings has therefore become one of the most pertinent research topics of the moment in the field of corrosion protection. A number of chromium-free conversion coatings have been found to show comparable corrosion resistance relative to chromate conversion coatings. For galvanized steel, conversion coatings based on zirconium and titanium have been found to be suitable alternatives to chromium. Organic additives may be incorporated in these conversion treatment solutions for galvanized steel to enhance the adhesion of organic coatings to the substrate. The effect of a given organic additive is highly dependent on the surface composition of the substrate as has been observed with the polymers polyacrylic acid (PAA), polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) on hot-dip galvanized steel and a Zn-Mg-Al alloy coated steel studied in this project. The durability of corrosion protection may also be enhanced by embedding corrosion inhibitors in the organic coating. An increased concern for sustainability and environmental-friendliness, has resulted in a global effort toward developing and using corrosion inhibitors which are safe for the environment and for human health. The electrochemical behaviour of galvanized steel in electrolytes with green inhibitors based on silicates, phosphates, zinc oxide and calcium at various concentrations are investigated. This project considers a multi-layer corrosion protection coating system comprising a conversion layer based on Zr/Ti cations and adhesion-enhancing polymer additives, and an organic coating embedded with 'green' corrosion inhibitors. The overarching aim is to investigate and establish new knowledge regarding the effect of polymer additives in conversion coatings on the adhesion of organic coatings as well as the identification of suitable green corrosion inhibitors. The outcome is an indication of which types of polymer additives and corrosion inhibitors work best for the two substrates tested – MagiZinc® and hot-dip galvanized steel, both supplied by Tata Steel BV.

Rapid industrialization and use of carbon based fuels has caused a drastic increase in the atmospheric CO2 levels in the last few decades. The rising anthropogenic CO2 levels pose a significant threat to the environment as evidenced by the increase in the mean global temperature levels, and the rising ocean levels. To mitigate the challenges associated with rising CO2 levels, there is an urgent need to move towards carbon neutral sources of energy and to curb carbon emission from large scale point emitters such as industries. Additionally, emitted CO2 could be converted into energy dense organic fuels using carbon-neutral forms of energy. This not only helps in reducing the carbon emissions but also balances the intermittent nature of renewable energy supply. CO2 could also be converted into platform chemicals such as ethylene/CO, which can be further up-converted or directly used in industry. Ethylene is particularly interesting due to its high energy density and wide industrial usage as a precursor in the polymer industry. Electroreduction of CO2 provides one such approach to electrochemically convert CO2 produced at large scale emitters to useful organic compounds. Different metallic catalysts are known to catalyse the electrochemical reduction towards different products, which follows from Sabatier’s principle. In this study copper is used as the model catalyst due to its unique ability to electrochemically convert CO2 to multi-carbon products, such as ethylene. From a cell design perspective conventional electrochemical reduction of CO2 in aq. media suffers from low production rates due to the low solubility of CO2 in aq. electrolytes which makes it not feasible from an industrial standpoint. To overcome the low production rates, this study was carried out on novel gas diffusion electrodes. Another factor limiting the implementation of CO2 electrolysers on an industrial scale, is the scalability of the catalyst synthesis. To improve this, electrodeposition of copper catalysts was employed. Electrodeposition is a well-established industrial technique and integrable within the existing infrastructure. Electrodeposition facilitates in-situ growth of the catalyst on gas diffusion layers, thereby providing a facile alternative to the conventional multi-step process for catalyst synthesis. Different morphologies of copper were synthesized by varying the electrodeposition process parameters. Copper nanowires were also synthesized by using templated electro-deposition techniques. The catalysts were characterised before and after the CO2 reduction experiments by Scanning ElectronMicroscopy, and X- Ray Diffraction. CO2 reduction experiments using the synthesised copper catalysts were carried out over a range of potentials. A peak Faradaic Efficiency (FE%) of 15% was measured at -1.5 V vs RHE (uncompensated) for ethylene, 19% FE at -1.1 V vs RHE for formic acid, and 13% FE at -1.5 V vs RHE for methane. It was also seen that the catalyst suffered from stability issues which were overcome by using pulsed electrolysis. Using pulsed electrolysis the lifetime of the catalyst was increased from 30 minutes to 15 hours.

This book is about reviewing and exploring the opportunities for introducing increased functionality into coating systems. The intention is to not only provide an account of recent developments, such as other books of this genre, but to also review, in detail, the nature of the problems that we are trying to address in advancing the materials science of coating systems. To this end we examine the fundamentals of corrosion science, the materials science of coatings, and developments in characterisation methods that all help to give an overview of the field. Importantly, we also look at the needs of industry with respect to developments in the coatings field.@en