<abstract xmlns="http://www.w3.org/1999/xhtml">

The topic of this work was the investigation of an alternative brassing technique consisting of electroless zinc plating of a copper object in a strongly alkaline solution and subsequent annealing to achieve a characteristic brass appearance. Within the scope of the work was the determination of the mechanism of zinc deposition on the copper surface, the optimisation of the NaOH concentration (30 and 40 wt. %), time of deposition (5-120 min), as well as temperature (150 and 200 °C) and annealing time (15 – 60 min). Electrochemical methods (potentiodynamic curves and open-circuit potential), metallography, X-ray diffraction (XRD), and glow-discharge optical emission spectroscopy (GD-OES) were used to study the brassing mechanism. Electrochemical measurements have shown that zinc powder significantly decreases the surface potential of copper to the value of zinc itself and also acts as a reducing agent. The diffusion of zinc in copper was found to occur during the primary deposition of zinc with the formation of the γ phase (Cu5Zn8). The optimal NaOH concentration is 40 wt.% and the deposition time is 60 min. The optimal conditions of annealing are 200 °C and 60 min. The primary γ phase is transformed during the annealing process into β and α phases.
</abstract>

Department of Metals and Corrosion Engineering

Electroless brassing of historical artefacts

<abstract xmlns="http://www.w3.org/1999/xhtml">
Organic corrosion inhibitors have been widely used to prevent and mitigate the damaging effects of corrosion on metal surfaces. However, their underlying mechanisms of action and effectiveness are still not fully understood. In recent years, the use of density functional theory (DFT) has emerged as a powerful tool to investigate the interaction between organic inhibitors and metal surfaces at the molecular level. This review article provides an overview of the principles of DFT, its advantages and limitations, and its application to the study of organic corrosion inhibitors. The factors affecting the performance of organic inhibitors, such as molecular structure, functional groups, and metal surface properties, are discussed in detail. The interaction between organic inhibitors and metal surfaces, including the adsorption and desorption of inhibitors, the role of intermolecular forces, and the effects of pH and temperature, are also explored. Finally, the challenges and future directions in the development of organic inhibitors using DFT are highlighted, including limitations and challenges in using DFT and potential avenues for further research. Overall, this review demonstrates the potential of DFT to provide valuable insights into the mechanism of organic corrosion inhibitors and to guide the development of new and more effective inhibitors for the protection of metal surfaces.
</abstract>

Faculty of Engineering and Built Environment

Understanding the mechanism of organic corrosion inhibitors through density functional theory

<abstract xmlns="http://www.w3.org/1999/xhtml">
The paper deals with the case studies of stainless steel piping corrosion in caustic soda transfer lines at a hydrocarbon processing plant, in the Asian region. The lines were in service of transferring the caustic soda solution from the storage tank farm to different process units, for subsequent use in reaction vessels. To maintain a minimum temperature of the fluid to avoid its precipitation, the lines were accompanied by a steam heat-tracer, throughout the line route. The material of construction (MOC) of the line was stainless steel type 316. After a period of about 3.5 years, 2” caustic line suffered fluid leakage, which was noticed through significant salt accumulation over insulation at one location. A valve was also noticed to leak through a weld at a 1.5” distribution line. The affected components were removed from service and subjected to detailed inspection and laboratory investigation, using advanced tools of metallurgical analysis and characterization. It was found that leakage in 2” line had occurred due to poor workmanship used during the repair of a manufacturing defect at the affected location and leakage of the valve had taken place due to the use of improper welding practice (in the case of subjected weld). In addition, the significant role of metallurgical defects in the parent metal was also disclosed to result in the observed failures. In addition, the contribution of process excursions can’t be completely ruled out. Finally, remedial measures are given to avoid the recurrence of such failure.
</abstract>

Corrosion failure of stainless-steel in caustic soda lines

<abstract xmlns="http://www.w3.org/1999/xhtml">
Galvanised steel serves as a base material for pipelines in fire protection systems. However, this system is known for its occasional corrosion failures. The Systems with residual water and oxygen access contribute to formation of macrocells due to different aeration, which can lead to severe damage of the pipes. The aim of this work was to investigate the cause of localized corrosion on the galvanised pipes designated for the fire protection system. The results proved that the main cause of the fire protection pipe system was the residual water in the pipe. The influence of differential aeration on the corrosion of zinc and steel was studied by resistometric technique and showed no effect on the failure of material.
</abstract>

Institute of Inorganic Technologies and Materials

University of Chemistry and Technology Prague

Localized corrosion attack on the galvanised steel pipes of the fire protection system

<abstract xmlns="http://www.w3.org/1999/xhtml">

Carbon steel has long been used in storing the saline water that results from oil washing in the oil industry. However, a high corrosion rate is reported, resulting in significant economic losses for oil companies. In the Middle East oil field, the temperature touches 50⁰C in Summer, causing increasing in corrosion rate for saline water steel storage tanks and pipes. In the present work, abundantly available wheat straw was used to prepare a cost-effective silicate inhibitor. The high inhibition efficiency of up to 94 % decreased the corrosion rate from severe corrosion for no-inhibitor specimen to close to low corrosion category for optimum inhibitor concentration specimen. The mechanism of the inhibition effect is the formation of a chemically adsorbed layer on the steel surface, which is successfully described by Langmuir isotherm. Additionally, at high concentrations of nano-silica, complex aggregates might form and be physically adsorbed on the surface of steel above the chemically adsorbed nano-silicate monolayer.
</abstract>

Mechanical Engineering department, Faculty of Engineering

Department of Materials Engineering, Faculty of Engineering

Department of Production Engineering & Metallurgy

Using green corrosion inhibitor to reduce maintenance cost for carbon steel saline water storage systems in the oil industry

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The journal is primarily focused on corrosion engineering and surface treatment of metallic materials. We accept also articles concerning degradation of paints, enamels and other non-metallic materials used for corrosion prevention of metals. Another field of interest is conservation and restoration of cultural heritage. In this case we accept contributions concerning all materials (metals, wood, paper, leather, textiles, stone, glass and ceramics).  Why subscribe and read   Official Journal of the Association of Czech and Slovak Corrosion Engineers, premier source of high quality research results from all over the world with special emphasis on Central and Eastern Europe;  over 55 years of experience in publishing original papers dealing with corrosion science, engineering and technology;  focused on research in corrosion and surface treatment as well as experiences in practice and „case studies“;  original papers that advance understanding of both the fundamentals of corrosion and its application;  excellent articles authored by researchers from all over the world, who appreciate our fast, fair and constructive peer review provided by experts in the field of corrosion engineering.   Why submit   Fast, fair and constructive peer review  Fast publication process („submission→published article“ takes usually 3-6 months)  High quality electronic publication technologies  Open access (simple and charge-free access for every researcher)   Rejection Rate   10%   Archiving  Sciendo archives the contents of this journal in Portico - digital long-term preservation service of scholarly books, journals and collections.  Plagiarism Policy  The editorial board is participating in a growing community of Similarity Check System's users in order to ensure that the content published is original and trustworthy. Similarity Check is a medium that allows for comprehensive manuscripts screening, aimed to eliminate plagiarism and provide a high standard and quality peer-review process. 