Effect of intermittent cathodic protection on potential and corrosion rate of carbon steel in soil simulating solution

Carbon steel in aerated soil operates in cathodic protection (CP) condition if the IR-free potential is more negative than –0.850 V CSE, which corresponds to a corrosion rate lower than 0.01 mm·a-1. CP is applied by a stationary current, which effectiveness depends on a thermodynamic effect, which reduces (or stops) corrosion rate, and on a chemical effect due to the alkalinisation at the metal-to-electrolyte interface. The increase of pH is promoted by the cathodic reactions (oxygen reduction and, at lower potential, hydrogen evolution) occurring on the polarized metal and can promote passive condition. In this paper, a preliminary study of intermittent CP has been carried out in order to investigate the effect of a temporary current interruption on potential monitoring and on residual corrosion rate of steel in soil simulating solution. Test has been performed applying two cathodic current densities (0.2 and 1.0 A·m-2), varying the current-off period daily duration (6, 12 and 16 hours) and monitoring weekly the potential. During the on period (i.e. CP on), oxygen is consumed and alkaline pH is established; during the off period (i.e. when CP is interrupted), the alkalinity and the slow oxygen replacement assure corrosion rates lower than in free corrosion condition, especially if high cathodic current density is previously applied

Surface treatment to improve corrosion resistance of pure titanium

The corrosion behavior of pure titanium UNS R50250 and UNS R50400 were investigated and compared with electrochemical behavior of Ti-0.2Pd and Ti-0.3Mo-0.8Ni alloys (UNS R52400 and UNS R53400 respectively). Surface treatments, especially anodic oxidations, were conducted in order to enhance the corrosion resistance of pure titanium up to the corrosion resistance of titanium alloys one. Samples were then tested with potentiodynamic analyses in chloride and fluoride containing solutions, in order to find critical pitting potentials for each condition and treatment. The results show that, despite all anodization treatments increased titanium corrosion resistance to different extents, no treatment was able to increase it up to UNS R52400 level. A suggestion on the best anodization procedure to increase corrosion resistance while maintaining ease of treatment is given based on potentiodynamic test results

Caratterizzazione della resistenza a corrosione di leghe ferrose in liquidi ionici a base imidazolo,

The possibility to use ionic liquids (ILs) in several industrial applications, from galvanic to electronics, to CO2 capture in combustion processes, requires a deeper understanding of the compatibility of the ILs of major interest with metallic materials that currently compose industrial plants. This work proposes the evaluation of the corrosion behavior of a carbon steel (API 5L X52) and a stainless steel (AISI 316) in presence of methyl imidazolium based ILs. The analysis focuses on the dependence of ILs corrosiveness on their chemical formulation, with particular reference to the anion composition and to the chain length of the imidazolium cation

Impianti di ionizzazione Cu-Ag per la di disinfezione delle acque e rischi di corrosione per spostamento

The copper and silver ionization system is one of the water sanitation treatments. Effective ionization occurs if the content of copper ions in solution is 0.2-0.4 mg/L and that of silver ions is 0.02-0.04 mg/L. An excess of copper and silver ions can react with other metal surfaces, triggering a deposition reaction, allowing the formation of deposits of more noble metals, and then promoting a localized corrosion phenomenon due to galvanic coupling. In the present paper, two case histories will be presented: one related to a legionella sanitizing plant system of a hospital; the second related to a system of water purification of a vessel on a boat. In both cases, working conditions are illustrated, corrosion morphology is described, focusing on the presence of copper and silver deposits, and the cause of corrosion is presented, estimating a reliable corrosion rate

Functional materials for Design

The main problematic of the research is to connect the stimuli-responsive behaviour of functional material to the end-user experience. To make this connection, the research was divided in layers, from the most technical at the bottom, to the most designerly at the top. The objective is to propose a set of chained tools that will eventually allow a seamless journey through all the layers and provide support for designers to use functional material in their projects

Selection Framework for the Implementation of Functional Materials in Product Design

Concept Functional materials, also called “smart materials”, are materials that can “sense environment events, process that sensory information and then act on the environment” [1]. These materials are able to transform a given stimulus into a response. We use the general term “transition phenomenon” to describe this process. These transitions can be as diverse as, e.g.: mechanoluminescence, which is a light emission produced by the application of a strain [2], or thermoelectricity, the convertion of a temperature difference into an electric potential [3]. We designed a specific database and selection process for functional materials. The data structure is organized around their main functionality: the transition phenomenon. This database is implemented in the Cambridge Engineering Selector software, using the “constructor” functionality. Motivations and Objectives The standard selection framework proposed by Ashby [4] relies on 4 successive stages : translation, limits, objectives, documentation. It is not entirely suited to the selection of functional materials, which has to account for the relation between stimuli and responses. Results and Discussion In our database prototype, we introduce a table of transition phenomena, which is organized by families and sub-families of outputs (Fig 1). The relationship between materials and transition phenomena is made by linking the tables together and providing specific attributes that describe the stimuli-responsive properties of the materials. Future developments include tables of existing products and processes used to implement functional materials or functionalize existing ones. In this work, as the entry point to the information system is the stimuli responsive behaviour of functional materials, rather than their structure and properties. The emphasis is thus put on user experience and interaction with materials and products. References [1] M. Addington, D. Schodek, Smart Materials and technologies for the architecture and design professions, Elsevier, 2005 [2] S. M. Jeong, S. Song, K.-I. Joo, J. Kim, S.-H. Hwang, J. Jeong, H. Kim, Bright, wind-driven white mechanoluminescence from zinc sulphide microparticles embedded in a polydimethylsiloxane elastomer [3] A. da Rosa, Thermoelectricity, Fundamentals of Renewable Energy Processes, Elsevier, 2013, 149–212 [4] M. Ashby, Materials Selection in Mechanical Design, Elsevier, 1992-2005(Third edition

La realcalinización y la extracción electroquímica de los cloruros en las construcciones de hormigón armado

Realkalisation and electrochemical chloride removal techniques, developed for rehabiliting carbonated and chloride-containing structures, are presented. Electrolysis and electromigration mechanisms and consequences as well as electrochemical conditions at the reinforcement surface are discussed and compared with cathodic protection ones. Furthermore, possible side effects are commented

Heat-Seal Ability and Fold Cracking Resistance of Kaolin-Filled Styrene-Butadiene-Based Aqueous Dispersions for Paper-Based Packaging

Dispersion coatings are offered as alternative solutions to extrusion coating technology for paper-based packaging. In addition to providing barrier properties, waterborne dispersions may implement the processing and converting properties of coated substrates, which are of extreme interest for an effective transfer to the industry. In this work, styrene-butadiene-based aqueous dispersions were formulated considering different amounts of kaolin as pigment. The authors assessed the heat-seal ability, fold cracking resistance, and blocking tendency, comparing the results against commercial dispersion coating grades. Kaolin content dominated the sealing behavior of experimental formulations, changing the minimum heat-seal temperature from 80 °C to >140 °C for 0% and 60% kaolin solid content, respectively. On the contrary, commercial grades were mostly affected by temperature. Additionally, despite the low latex glass temperature (0 °C), experimental formulations generally showed little, if any, blocking. On the downside, increasing kaolin content eases fold cracking, showing a different magnitude according to fold direction and coat orientation yet achieving a higher moisture barrier compared to commercial grades for both folded and unfolded samples