Low-cost technologies used in corrosion monitoring

Globally, corrosion is the costliest cause of the deterioration of metallic and concrete structures, leading to significant financial losses and unexpected loss of life. Therefore, corrosion monitoring is vital to the assessment of structures’ residual performance and for the identification of pathologies in early stages for the predictive maintenance of facilities. However, the high price tag on available corrosion monitoring systems leads to their exclusive use for structural health monitoring applications, especially for atmospheric corrosion detection in civil structures. In this paper a systematic literature review is provided on the state-of-the-art electrochemical methods and physical methods used so far for corrosion monitoring compatible with low-cost sensors and data acquisition devices for metallic and concrete structures. In addition, special attention is paid to the use of these devices for corrosion monitoring and detection for in situ applications in different industries. This analysis demonstrates the possible applications of low-cost sensors in the corrosion monitoring sector. In addition, this study provides scholars with preferred techniques and the most common microcontrollers, such as Arduino, to overcome the corrosion monitoring difficulties in the construction industry.The authors are indebted to the projects PID2021‐126405OB‐C31 and PID2021‐126405OB‐C32 funded by FEDER funds—A Way to Make Europe and Spanish Ministry of Economy and Com‐petitiveness MICIN/AEI/10.13039/501100011033/, project PID2019‐106555RB‐I00 and project IDEAS 2.14 from Ports 4.0. It should also be noted that funding for this research was provided for Seyed‐milad Komarizadehasl by the European Social Fund and the Spanish Agencia Estatal de Investi‐gación del Ministerio de Ciencia Innovación y Universidades, grant (PRE2018‐083238).Peer ReviewedPostprint (published version

Galvanic Corrosion of Aluminum/Carbon Composite Systems

Aluminum/carbon composite systems can have outstanding mechanical properties. Aluminum and carbon fiber reinforced polymer matrix composites (CFRP) are typically considered corrosion resistant when used alone, but can develop severe galvanic corrosion when in physical contact in the same component or structure. General engineering practice is to avoid contact between aluminum and CFRP in any application where moisture may be present, but it is still of great importance to understand the consequences if the two materials accidentally become in contact. There may also be applications where a low rate of galvanic corrosion is acceptable. This dissertation contributes unique experimental and numerical approaches to improve the fundamental understanding of galvanic corrosion in aluminum/carbon composite systems, with particular focus on rate limiting control mechanisms in a high-temperature low-sag bare overhead transmission line conductor utilizing a CFRP load bearing core. The improved understanding was accomplished partially by the development of a novel assessment method for the in-situ galvanic corrosion testing of bare overhead conductors of various designs. The method allows for real-time measurements of galvanic corrosion currents while retaining the original geometry of the conductors. One of the most important findings is that the galvanic corrosion is under cathodic control, which means that the total galvanic corrosion rate is determined by the exposed carbon area, and independent of the exposed aluminum area. Another important finding is that the galvanic corrosion process is under diffusion control, which means that the total galvanic corrosion rate is mainly controlled by the rate at which oxygen arrives at the carbon surface. The implication of these findings is that the geometry of the component or structure can affect the galvanic corrosion rate by orders of magnitude. The dissertation work has also included the development of a structural health monitoring method for CFRP supported overhead conductors using Time Domain Reflectometry (TDR). This comprehensive research has significantly contributed to the increased acceptance of CFRP supported bare overhead conductors in both the United States and worldwide. The knowledge gained in this study is already aiding the evaluation of existing conductor designs and the development of future ones

Sustainable methodology of conserving historic military vehicles.

Research was conducted to analyse corros ion and tribological failures in The Tank Museum Bovington military tanks . Due to the age of the exhibits corrosion of vital components has become a significant issue, it is vitally important to preserve these artefa cts for future generations and so to do this effectively we need to monitor and reduce this corrosion as far as realistically possible. A case study of the historic military tanks followed by experimental research analyses is presented. Structural degradat ion through corrosion and engine wear has been i dentified and analysed . Materials were processed/manufactured during 2 nd Wor ld War, their composition was unknown. Therefore state - of - the - art characterisation techniques were performed on samples collected fr om the M10, Sherman, Centaur and Tiger 1 to obtain material compositions and to identify nearest standards . A bench mark of material loss due to corrosion so far, has been achieved in the M10, Sherman, Centaur, BT – R 60 and King Tiger t h rough ultrasonic c orrosion mapping . Material loss because of corrosion was high in the Centaur in comparison to the Sherman, M10, BT R – 60 and King Tiger s amples. C orrosion analyses techniques were conducted on samples from three tanks the M10, Sherman and Centaur to investigate corrosion m orphology on the tanks surfaces and corrosion propagation from surface to sub - surface level . During this experimental work various corrosion contaminants, sub - surf ace crack s and defects were identified. Corrosion layer/ residues we re relatively thick (approximately 250 μ m) on the surfaces of the M10, wherea s the phenomenon of corrosion pits was wide spread in the Centaur. C orrosion was influenced by the presence of surface contaminants and sub - surface defects such as slags, sulphide inclusions and corrosive pits. These factors alone and/o r in combination were observed to be a serious issue in limiting vehicles‟ longevity. Study of the environments both inside and outside the museum has been conducted to relate corrosion activity wit hin the conte xt. Based upon the data gathered simulated environmental corrosion tests were conducted to quantify corrosion accumulation under a controlled museum environment suitable for the museum visitors. Some degree of corrosion build - up was observed o n the samples under cont rolled environments. Prohesion test was conducted to evaluate viability of the material s , coating and primer. M aterial ability to resist adverse environmental conditions was negligible. These results are of particular interest for t he vehicles which are exposed in uncontrolled environment. Exposure of the primer an d coating to prohesion test showed, that the primer was able to resist failures during the entire test duration . However breakdown of th e coating was observed during the te st . Wear analyses of the o riginal piston which was designed before/during the 2 nd World War showed enhanced material composition and tribological pro perties than the new replacement piston . F ailures in the replacement piston and cylinder - liner could be att ributed to inadequate material selection and design. A sustainable model to extend longevity and to retard structural aging of the military tanks in The Tank Museum has been proposed

Under-deposit localised dissolution in simulated sour environments

Sour (H2S –containing) environments present a major problem for oil and gas industries; of particular concern, is Underdeposit Corrosion (UDC), which is a type of accelerated localised corrosion observed under deposits, creating a risk to the asset integrity. Iron sulfides, a typical deposit in the sour environment, are considered critical due to their complex nature. The kinetics and controlling factors of sour UDC are not fully understood and there is no consensus on the methods used to evaluate it in pipelines. The efficacy of inhibitors may vary in such a scenario and so the amounts and efficiencies required cannot be a priori decided. There is, therefore, an urgent need for a protocol that addresses the characteristics of deposits to provide kinetic and mechanistic information on UDC phenomena. In this work, both the general and localised corrosion kinetics of steel were studied in a simulated sour environment under ‘inert’ (sand) and ‘active’ (iron sulfide) deposits. Our multiscale investigation involved electrochemically measuring planar electrodes and 1- dimensional artificial pits to simulate actively dissolving interfaces with different geometries, followed by ex-situ surface analyses. In addition, the interfacial salt layer responsible for defining the stability of pits propagation was further investigated in-situ using synchrotron microfocus X-ray analyses. The study showed that deposits stabilise a pitting-like corrosion in mild steel by altering the ionic diffusion process, which perturbs the local environment in a way that maintains an active chemistry for pit propagation. The salt films on the active interface have properties that are found to be dependent on the deposit type and the environment medium: sulfur-containing species, such as H2S or iron sulfide deposits, form an additional sulfide film at the metal interface, stabilising the kinetics for a further continued, yet slow pitting corrosion. Troilite presented the most aggressive form of deposit under the studied conditions. Therefore, based on the mechanistic understanding of UDC developed in this work, a protocol for the development of representative deposits for in-line corrosion sensing can be established, opening avenues towards researching effective and reliable inhibition protocols.Open Acces

The Development Of Mems-Based Implantable Oxygen Sensing Systems

Oxygen-based cues are direct assessments for a wide range of in vivo biological effects, ranging from mitochondrial disease to tissue engineering/regenerative medicine. Existing electrochemical oxygen sensors are permanent systems applicable to short-term intraoperative use; devices are extracted before wound closure. Development of biocompatible oxygen sensors for long-term, post-surgery monitoring are therefore, desirable for clinical trials where objective oxygen measures are lacking. A biodegradable oxygen sensor that can break down into non-toxic components after a targeted lifespan, reducing the risk of chronic inflammatory response frequently observed with permanent devices, is another promising approach to advance the postoperative monitoring of oxygen tension and provide an additional means to monitor a number of diseases and injuries that are transient in nature, such as bone fracture, traumatic brain injury and wound healing. In this dissertation, we improved the current oxygen sensing technology to the point that it could be used for long-term applications, and further developed a biodegradable oxygen sensor along with a transient energy source to support the design of completely biodegradable oxygen sensing systems. Specifically, a biocompatible oxygen sensor, integrated with a customized circuit and an off-the-shelf battery were designed, built and tested. Oxygen levels in mouse gluteus muscle and zebrafish trunk muscle were both investigated to examine the sensor’s ability to monitor dynamic oxygen tension in vivo. In addition, a biodegradable battery featuring long shelf life and stable performance in the presence of changing body conditions was designed, fabricated and examined in vitro. Finally, a completely biodegradable oxygen sensor featuring a Mg-Mo galvanic pair was demonstrated. This approach measures physiological oxygen tension in a transient, harmless manner in the body, while simultaneously acting as a potential energy source for additional devices. Additionally, such sensors may have application in transient monitoring of the environment, such as environmental spills and algal tides

Techniques for In Situ Monitoring the Performance of Organic Coatings and Their Applicability to the Pre-Finished Steel Industry: A Review

A review is carried out in this paper into techniques that currently exist for, of have the potential to be used for, monitoring the performance of organic coating. Specific attention is paid to the applicability of each method to pre-finished steel used in the construction industry as these are rarely monitored in situ and their expected performance is often only estimated from lab-based accelerated corrosion testing. Monitoring could allow more accurate estimates of building cladding lifespan and required maintenance schedules; provide customers with active performance data; additionally, with a better understanding of performance, more appropriate coatings or coating weights could be selected for a construction project, offering economic benefits as part of smart building developments. An introduction to coatings, their use for corrosion protection, failure mechanisms, and relevant monitoring techniques is given before current assessment techniques are described in terms of their working principles. Examples of recent work are presented for the techniques that have been investigated for monitoring or directly relatable purposes. The review concludes that there are several good reasons why an optimum corrosion monitoring technology does not currently exist, however, promising research is emerging in the field of wireless and embedded sensor design which is providing optimistic results

Stability diagnostics for thin-film photovoltaic modules

Photovoltaic (PV) modules create electricity from solar radiation by converting photon energy to electrical potential energy. The use of photovoltaic electricity is growing rapidly particularly in building-integrated, grid-connected applications. The useful lifetime of PV modules is an important determinant of the competitiveness of PV electricity. Lifetime improvement and prediction requires detailed information on degradation mechanisms in the field and in accelerated aging tests. In this thesis, new methods for studying and predicting the stability of thin-film PV modules have been developed. Stability is a greater challenge for thin-film devices than for established PV technologies, and good stability diagnostics are therefore crucial for improvements in thin-film device lifetime. The diagnostics developed in this thesis focused on two areas of lifetime research. The first was the study of water transport in photovoltaic module encapsulants. It was shown that a TiO2 film of micrometer thickness can be used as a sensor structure to measure water transport in the encapsulant with high accuracy without affecting the transport process. The sensor concept was applied in a study of absorption and desorption of water in ethylene-vinyl-acetate (EVA) films laminated between two glass sheets. The rate of desorption at a temperature difference of 25°C between the sample and the surroundings was 16 times higher than the rate of absorption at ambient temperature. This result indicates that unframed, EVA-encapsulated modules are likely to dry out in sunny conditions. The degradation of thin-film modules in outdoor operation was the second area of interest in this thesis. A de-encapsulation method for characterizing field degradation in thin-film modules was presented and applied to CdTe modules. It was observed that small-area sampling is especially well suited for characterizing module fill factor degradation. A data filtering methodology was also developed to improve the accuracy of data analysis in field tests. The method was applied to CIGS modules and was found to be especially useful in the analysis of low-irradiance data and current parameters. Additionally, thermal modeling of building integrated a-Si modules was used to predict thermal stress in different European locations. The diagnostics developed in this thesis open up possibilities for improving thin-film module lifetime by enabling precise testing of the moisture-protection properties of encapsulants and by providing methods for identifying degradation mechanisms in field-tested modules.reviewe

MULTIANALYTICAL APPROACH FOR THE STUDY OF BRONZE AND GILDED BRONZE ARTEFACTS

This work focuses on one of the most common metal alloy used in the field of art: bronze. Bronze was discovered about 3500 years BC and was used in the antiquity to create tools, weapons, armour, and later coins, medals, sculptures and other works of art. Bronze objects were harder and more durable than stone or copper ones and easier to work than the iron ones. These characteristics contributed to render bronze a material largely widespread through millenniums. Of great interest are also the colourings that outdoor bronze exhibit. In fact, when exposed to atmosphere, copper and its alloys form a thin layer of corrosion products, called patina. The naturally formed patinas have different colours depending on the surrounding environment and its chemical composition: urban, rural, marine. A patina on a bronze artwork not only protects the metallic substrate, but also enhances the aesthetic of the artistic objects. Coloured patinas form spontaneously on copper alloys by very slow controlled corrosion either in the presence of moisture, carbon dioxide, and oxygen, or other chemical species present in the atmosphere. Patinas may also be created artificially by artists for aesthetic and protective reasons. Investigation of the corrosion behaviour of copper patinas is of utmost importance for understanding the atmospheric deterioration of bronze monuments as well as objects of cultural heritage. During this work, a multidisciplinary approach has been applied in order to thoroughly understand the degradation mechanisms of the patinas of corrosion products that naturally form over bronzes surface. Particular attention has been paid to the transformations connected to relative humidity variations. To further adorn and make more precious the artefacts, bronze statue were also gilded. The gilding of a bronze statue allows to obtain an object that has the same aspect of a statue made of pure gold, but that is less expensive and simultaneously presents certain resistance characteristics. Examples of gilded bronze artworks can be found in the Italian artistic patrimony, such as, for example, the horses of St. Mark in Venice, the statue of Marcus Aurelius in Rome and the Porta del Paradiso, the eastern portal of the Baptistery in Florence. The latter has been the starting point of this work. This important gilded bronze of the Italian Renaissance was damaged during the flood that devastated Florence in 1966 and since then a long process of restoration and characterization of the artwork started and it is still going on. The study of gilded bronze artworks is a difficult topic in the field of cultural heritage due to the complex structure (tri-layer) of the material. The structure, in fact, is composed by a metallic substrate (bronze), the gold and, between the two metals, a layer of corrosion products formed during time as a consequence of degradation processes. The presence of hygroscopic salts between the gilding and the bronze may lead to the detachment of the gold layer as a consequence of volume variation related to changes in the crystalline forms of the copper salts composing the patina. At the beginning of this work, the \u201cPorta del Paradiso\u201d was at the last stage of a long process of restoration carried out by the Opificio delle Pietre Dure and the door was almost ready to be finally unveiled to the public. At that stage of the research it was necessary to identify the best exposure option for this precious and unfortunately very unstable masterpiece of the Renaissance. The optimal display option for the \u201cPorta del Paradiso\u201d had to take into account two important factors: first, it was necessary to choose an environment that could assure the best preservation condition for the restored artwork and therefore able to block corrosion; second, a solution that could provide an enjoyable viewing experience for the public was also expected. To fulfil these requirements, three different showcases were tested: a) a closed showcase purged by nitrogen; b) a closed showcase with low and controlled relative humidity; c) an open showcase with controlled microclimate that should create the same local environmental conditions as the showcase with low RH, with the big advantage of avoiding a glass panel between the object and the visitor. To evaluate the resulting conditions of conservation imposed by the three different showcases, qualitative and quantitative studies were necessary. Unfortunately the techniques commonly used to obtain quantitative data regarding corrosion phenomenon from metallic artefacts (i.e. polarization resistance and electrochemical impedance spectroscopy) are not suitable for bimetallic artefacts such as the \u201cPorta del Paradiso\u201d. Initially some replicas of the \u201cPorta del Paradiso\u201d, with the same bronze alloy and the same gilding technique of the door, were produced by the OPD. It was then necessary to age these samples in order to obtain a system that reproduces the actual condition of the artwork. For this reason a new methodology was developed during this work for the electrochemical artificial ageing of gilded bronze specimens. Unfortunately, due to the unavoidable short circuit between gold and bronze, these aged samples were not suitable to obtain quantitative data concerning the corrosion rate of the door. An alternative solution appeared to be the realisation of galvanic sensors, used as replicas of corroded gilded bronzes, that were developed and used to measure the macrocouple current of the system \u201cBronze-Patina-Gold\u201d, that is directly correlated to the corrosion rate by Faraday\u2019s law. The most critical steps during the development of the galvanic sensors are: a) the preparation of an artificial patina of corrosion products and b) the gilding methodology. The realisation of an artificial patina proved to be a very crucial point, because the patina has to fulfil a series of important and specific requirements, such as: 1 \u2013 composition similar to the real cases, 2 \u2013 adequate thickness, 3 \u2013 good homogeneity, 4 \u2013 good adhesion to the substrate, 5 \u2013 adequate electrical resistance. The main constituents of natural patinas have been identified after a thorough literature review. Then a procedure for the realisation of artificial patinas with similar composition was developed. Different kind of patination techniques available in literature (such as chemical and electrochemical patination) have been tested to obtain the artificial layer of corrosion products. Unfortunately none of them allowed to obtain a patina with all the required characteristics. A new methodology was then developed for the patina used to realise the galvanic sensors. This method is inspired by the so-called \u201capplied paste\u201d and consists in spreading on the metallic surface a specific mixture of copper salts and water .This procedure allows to control precisely all the parameters previously mentioned. Concerning the second critical step, i.e. the gilding procedure, two different methodologies have been tested: sputtering and gold leaf application. The best one revealed to be the application of a gold leaf. A first set of galvanic sensors was realised and used for the solution of the \u201cPorta del Paradiso\u201d case. In that occasion they proved to be a very powerful tool and allowed the identification of the best display option for the doors. However these sensors presented some evident problems of durability and reproducibility. The methodology of preparations of the galvanic sensors has subsequently been completely revised and improved leading to the obtainment of new galvanic sensors, named \u201cgold leaf galvanic sensors\u201d, that proved to be much more durable and reproducible. The galvanic sensors can be used both for monitoring the corrosion rate of real objects and for testing new conservation or cleaning procedures

Index to NASA Tech Briefs, January - June 1966

Index to NASA technological innovations for January-June 196