Corrosion Of Metallic Components Research Articles

(Invited) Energy Materials Development at Ceres: From Nanometers to Megawatts

Ceres’ unique metal supported SteelCell® SOC technology is increasingly establishing itself as the global standard for SOC, combining robustness, efficiency and low manufacturing cost. The technology is rapidly moving from demonstration to true volume production, with Robert Bosch GmbH in Germany and Doosan Fuel Cell in South Korea both having licenses to manufacture Ceres SteelCell® cells and stacks at the hundreds of MW per year scale with factories under construction. Ceres acts as design authority to licensees who manufacture Ceres-developed technology at scale. As such Ceres specifies the raw materials required for cell manufacture and has ultimate responsibility for the validation of any new suppliers of raw materials proposed by licensees.In addition to supporting the high-volume scale up of current generations of SteelCell technology, Ceres has an extensive R&D program to develop future technology generations which offer improved performance, lower cost and/or lower degradation. A very detailed understanding of the behavior of the materials used in cells, stacks and systems is required to enable future optimization and/or the development of novel materials. This particularly includes the challenges of understanding degradation phenomena, which due to the extended timescales involved are poorly characterized in academic literature. To enhance this understanding Ceres has a number of academic collaborations, most notably with Imperial College London to use leading-edge experimental and computational techniques to understand material behavior affecting initial performance, degradation (particularly changes at interfaces) and corrosion of metallic components. Information gained from these collaborations is used to enable reliable lifetime prediction for current-generation stacks and systems to be undertaken using computer models to predict performance through-life using degradation models derived from theoretical understanding. Theoretical understanding of materials behavior also drives innovation in new generations of materials offering enhanced performance and/or durability, enabling Ceres to maintain its competitive advantage in SOC technology.

Wpływ czynników mechanicznych na wydajność i proces starzenia się kiwona

"The paper discusses the influence of mechanical factors on the performance and aging process of rocking machines, specifically focusing on oilfield equipment such as the downhole rod pump jack. The authors emphasize the importance of analyzing the condition and aging process of oilfield equipment to ensure reliability, safety, and efficiency in oil production processes. The mechanical factors discussed in the paper include vibrations, loads, wear, and corrosion. Vibrations can be caused by improper balance, bearing failures, or other factors, and they have a negative impact on equipment performance and can lead to breakdowns. High mechanical loads associated with raising and lowering sucker rods can cause wear and damage to the pump jack. Operating in harsh environments with sand, abrasive particles, or chemicals can also cause wear on surfaces and equipment parts. Corrosion of metal components can occur due to moisture, chemical attack, or improper storage and maintenance, leading to deterioration and breakage of equipment. The consequences of these mechanical factors on the aging of an oil pump jack include accelerated aging, decreased performance, and an increased risk of accidents. Continuous exposure to vibration, stress, wear, and corrosion accelerates the aging process, resulting in deterioration and reduced equipment life. Damage and breakdowns caused by mechanical factors lead to decreased efficiency, negatively impacting oil production processes. Moreover, insufficient maintenance and failure to address mechanical influences increase the risk of accidents, downtime, and damage to other parts of the manufacturing process. To assess the health and aging status of an oil pump jack, various analysis and diagnostic methods are used, including visual inspection, strength testing, monitoring of parameters, and non-destructive testing. Visual inspection helps identify visible damage, wear, and defects. Strength testing evaluates the reliability of pump jack parts and identifies potential issues. Monitoring parameters like vibrations, temperature, and pressure allows for detecting deviations from normal operation and preventing breakdowns. Non-destructive testing methods such as ultrasonic testing, magnetic particle testing, and radiography help identify hidden defects and damage. The authors recommend several strategies to maintain the reliability and efficiency of an oil pump jack. These strategies include implementing a preventive maintenance program with regular inspection, testing, and parts replacement based on manufacturer’s recommendations and equipment condition analysis. Determining optimal service and part replacement intervals based on historical data, monitoring results, and manufacturer’s recommendations is crucial. Additionally, utilizing more durable materials, anti-corrosion coatings, improved designs, and technologies can increase equipment resistance to mechanical stress and improve performance. The paper also describes the device and components of a pump jack, such as the installation base, platform, balancer, electric motor, crank, connecting rod, and control station. It emphasizes the importance of considering various characteristics when selecting and evaluating the effectiveness of a pump jack, including working load, maximum plunger stroke, reducer dimensions, output torque, and swing frequency. The kinematics of the pump jack drive system are discussed, highlighting the need for reconfiguration to adapt to changing operating conditions and optimize oil production performance. Overall, the paper emphasizes the importance of analyzing mechanical factors, managing the aging process, and implementing maintenance strategies to ensure the reliable and efficient operation of oilfield equipment, specifically the pump jack used in oil production processes.

Features, events and processes (FEP) analysis of the interactions between repository monitoring systems and multi-barrier systems

Abstract. In line with the European waste directive 2011/70/EURATOM, the European Joint Programme on Radioactive Waste Management (EURAD) was launched in June 2019. EURAD aims to make a step change in European collaboration between advanced and early-stage waste management programmes. Monitoring Equipment and Data Treatment for Safe Repository Operation and Staged Closure (MODATS) is Work Package (WP) 17 of the EURAD programme. This WP aims to address a range of research needs relating to repository monitoring data and technologies. This abstract summarises research relating to the interactions between repository monitoring systems and the multi-barrier systems in which they are emplaced. A detailed features, events and processes (FEP) analysis is being undertaken to identify and describe the manner in which monitoring systems may interact with multi-barrier systems. Monitoring system components are generically considered in this research; they include data acquisition technologies, power technologies, data transmission technologies and data loggers. No specific disposal concepts have been selected; however, a range of commonly engineered barrier system materials and typical host rocks are considered. This FEP analysis research will provide an understanding of the impacts of monitoring systems, which could be used to aid monitoring system design optimisation, for example by supporting the screening of monitoring technologies (White and Scourfield, 2019). It may also provide evidence to demonstrate that monitoring systems do not unacceptably impact the safety functions of the multi-barrier system. Potential interactions may include the creation of gas migration pathways along monitoring power or data transmission cables positioned in the multi-barrier system. This process has been observed in underground research laboratory experiments, such as the Large Scale Gas Injection Test (LASGIT) experiment in the Äspö Hard Rock Laboratory, which involved a series of gas injection tests in a full-scale KBS-3V deposition hole. Other possible interactions could include (non-exhaustive) corrosion of metallic components, degradation of non-metallic components, microbial activity, gas generation, void introduction and formation and volume changes. The final output of this research will be a catalogue of FEPs describing the interactions between generic monitoring systems and multi-barrier systems. Similar to the Nuclear Energy Agency FEP lists, this FEP catalogue is intended to be a starting reference for waste management organisations to use to understand the potential interactions between their specific monitoring systems and multi-barrier systems.

LASER AND INFORMATION TECHNOLOGIES FOR CONTROLLING DYNAMIC DISPLACEMENTS SPATIAL STRUCTURES OF OBJECTS UNDER THE INFLUENCE OF ACTIVE MAN-MADE AND NATURAL RISK FACTORS FOR ACCIDENTS

At the present stage of science development, for technological and technogenic energy-intensive systems, systematic methods of identification of structure, dynamics, and risk assessment are developed, while for spatial objects this problem is not fully solved. This applies to the construction and operation of such objects with a spatially distributed structure such as bridges, large pavilions, high-rise buildings, aggregate lines on a common foundation for color printing, which are subject to a large dynamic, non-uniform load-capacity, operating over a long period of operation. Their destruction with the combined action of dynamic and static heterogeneous flow factors in time of high power, leads to the accidents and human losses. The main factor that leads to cognitive errors in the design of spatial structures is that experts in the design process do not fully take into account the concepts of physical force, power and physical energy factors with stream random structure. In this aspect, the problem of dynamic structural stability under the influence of factors with a stochastic structure drew attention to Y. P. Dragan, introducing the notion of "stochastic process of finite energy" and "finite power of flows (sequences) of active physical force actions". Under certain conditions, the complex action of force factors leads to the emergence of solitons, that is, the formation of the peak of energy and power at a certain time in the weakest node of the structure that destroys it. If the designer, by virtue of his cognitive abilities and level of knowledge, does not take into account the energetic nature of the factors as destructive forces, then this leads to the destruction of infrastructure objects (cities in Genoa, Italy 2015, built in 1967) devastating floods, fires, transport disasters, tsunami. As for the steel construction bridges in the USA (New York), built on the basis of the methods of vibration calculations by S. Tymoshenko, they are operated for more than 100 years, with appropriate technical service.
 The assessment of the vibrational stability of spatial structures, both existing and new projects, remains a complex control problem that is not resolved to the fullest, and therefore the development of integrated intellectual methods for designing and controlling their state is relevant
 The intensive development of infrastructure, both social and technogenic, results from the impact of transport flows, power plants, harmful emissions, to the growth of force environmental load on spatial structures, corrosion of metal components, and the growth of vibrational effects on elements of objects. Further development of such negative processes leads to a decrease in the strength of structures, their stability, operational reliability and destruction. Reducing the quality of bearing structures, due to neglected negative influences, makes it impossible to forecast the moment of emergency situations. Accordingly, the development of methods for remote control of vibrations of spatial elements of bearing structures is a main problem for various industries.

Dynamic corrosion testing of metals in solar salt for concentrated solar power

Potassium nitrate and sodium nitrate in mixing proportion of KNO3–NaNO3 40-60 wt% (also called solar salt) has been successfully used for over a decade as heat storage medium for concentrated solar power parabolic-trough collector plants at temperatures up to 400 °C. At temperatures of 560 °C, reached in state-of-the-art solar tower systems, corrosion of metallic components in contact with solar salt can become an issue and has caused leaks and plant shut-downs in recently built tower projects. While the corrosion rates of several materials have been determined for different temperatures in static molten salt immersion experiments, there is a lack of corrosion data for dynamic in-service conditions. In this work, a dynamic corrosion test has been conducted on 19 different material types including protective coatings, mimicking flow-rate, temperature gradient and draining of in-service operation of a receiver in a concentrated solar power tower. The measured corrosion rates are presented and compared to static corrosion tests reported in literature.

Ground-Penetrating Radar Investigation of Salvaged Timber Girders from Bridges Along Route 66 in California

This study describes assessment of the internal conditions of timber bridge structural members along Route 66 in California. These timber bridges were exposed to desert climate conditions for several decades, which can lead to a variety of deterioration. Overtime, the deterioration may cause loss of structural integrity within the bridges and lead to potentially hazardous conditions for the motoring public. Members from dismantled bridges were brought to the Forest Products Laboratory in Madison, WI. Strength-reducing features including decay, splits and cracks insect attack, and corrosion of metal components were initially identified using visual inspection. Further assessment was then performed using several nondestructive testing technologies including ground=penetrating radar (GPR). GPR was used, among other nondestructive techniques, to identify and locate internal features and defects within the timbers. The tomographic output of the GPR known as radargrams, revealed deterioration. Based on the information contained within the radargrams, it was possible to classify some internal features and defects with a high degree of certainty, whereas others remained less clear. In this study, the potential of using GPR for inspection of bridge timbers is discussed and supported through interpretation of the radargrams.

Лазерні та інформаційні технології контролю динамічних зміщень просторових структур об'єктів за дії активних техногенних і природних чинників ризику аварій

На сучасному етапі розвитку науки для технологічних і техногенних енергоактивних систем вироблено системні методи ідентифікації структури, динаміки, оцінення ризику, тоді як для просторових об'єктів цю проблему повною мірою не вирішено. Це стосується будівництва та експлуатації таких об'єктів з просторово розподіленою структурою, як мости, великі павільйони, висотні будинки, агрегатні лінії на спільному фундаменті для кольорового друку, які піддаються великим динамічним неоднорідним за потужністю навантаженням, що діють упродовж тривалого часу експлуатації. Їх руйнація при сукупній дії динамічних і статичних неоднорідних потокових у часі чинників великої енергетичної потужності, призводить до аварій і людських втрат. Основний чинник, який призводить до когнітивних помилок у проектуванні просторових конструкцій, є те, що фахівці у процесі розроблення проекту не до кінця враховують поняття фізичної сили, енергії потужності та фізичної енергії чинників з потоковою випадковою структурою. На цей аспект проблеми динамічної стійкості конструкції за дії чинників із стохастичною структурою звернув увагу Я. П. Драган, ввівши поняття "стохастичного процесу скінченої енергії" і "скінченої потужності потоків (послідовностей) активних фізичних силових дій". За певних умов комплексна дія силових чинників призводить до виникнення солітонів, тобто формування піку енергії та потужності у певний момент часу у найслабшому вузлі конструкції, що її руйнує. Якщо проектант, через свої когнітивні здібності і рівень знань, не враховує енергетичну сутність чинників як руйнівних сил, тоді це призводить до руйнування інфраструктурних об'єктів (міст у Генуї (Італія 2018 р.)), збудований у 1967 р., Китай 2019 р.), руйнівних повеней, пожарів, транспортних катастроф, цунамі. Щодо мостів з металоконструкцій у США (Нью-Йорк), побудованих з урахуванням методів вібраційних розрахунків С. Тимошенко, то вони експлуатуються понад 100 років, за відповідного технічного обслуговування. Оцінка вібраційної стійкості просторових конструкцій, як наявних, так і нових проектів, залишається складною проблемою створення систем контролю і діагностики, не вирішеною повною мірою, і тому розроблення інтегрованих інтелектуальних методів проектування систем контролю методом дистанційного лазерного зондування є актуальною. Інтенсивний розвиток як соціальної, так і техногенної інфраструктури призводить, внаслідок дії транспортних потоків, електростанцій, виробництв з шкідливими викидами, до росту силового екологічного навантаження на просторові конструкції, корозію металевих складників, росту вібраційних впливів на елементи об'єктів. Подальший розвиток таких негативних процесів призводить до зменшення міцності конструкцій, їхньої стійкості, експлуатаційної надійності та руйнування. Зниження якості несучих конструкцій, через невраховані негативні впливи, унеможливлює прогноз моменту настання аварійних ситуацій. Відповідно, розроблення методів дистанційного контролю вібрацій просторових елементів несучих конструкцій є для різних галузей актуальною проблемою.

Properties of magnesium oxide boards used as sheathing in exterior walls

Sheathing boards based on magnesium oxide (MgO) became very popular in the Danish market around the year 2010. However, it was realized a few years later that they condensed humidity from ambient air. The leakage from the boards led to severe problems with corrosion of metallic components and moisture uptake and degradation of wooden members. The boards have been banned from use in the Danish market since 2015, while damage cases valuing around 370 million EUR still need to be reconciled [1]. The binder in MgO board is formed by a chemical reaction between MgO and MgCl2. However, MgSO4 is a possible alternative to MgCl2, and such boards may have smaller moisture uptake, to reduce this issue. This paper gives an account of recent activities to compare properties of MgO boards, based on chlorides or sulphates. The investigations comprise: (1) Analysis of elemental composition and crystalline components, (2) Examination in optical microscope and scanning electron microscope, (3) Determination of moisture retention and water vapour permeability, (4) Analysis of chemical composition of leaked salt water from boards, and (5) Visual observation of decomposition and determination of dry mass change after exposure to high humidity.

On the fate of oxygen in a spent fuel emplacement drift in Opalinus Clay

Persistence of aerobic conditions after backfilling of a spent fuel emplacement drift is of high relevance for the selection of canister material and canister design, as well as for the prediction of the onset of H2 production. This paper presents the results of the O2 monitoring during the backfilling and early heating phases of the Full-scale Emplacement Experiment at the Mont Terri underground laboratory (Switzerland), as well as the first results of laboratory experiments and 3D reactive transport modelling which aim at identifying the processes controlling O2 concentrations. The monitoring shows the disappearance of gaseous O2 and onset of anaerobic corrosion in sections not affected by O2 inflow from the access tunnel within weeks after backfilling, and even before closure of the drift for the deepest parts of the experiment. The laboratory experiments show that O2 can significantly adsorb on granular bentonite exposed to high temperatures and might in principle also adsorb at ambient temperature and relative humidity as low as 55%. Thus, gas sorption should be considered in the balance of O2 in the experiment. These results are consistent with the numerical model indicating that the excavation damaged zone but also the bentonite backfill are the main sinks for O2, whereas corrosion of metallic components seems to play a negligible role. Previous studies estimated the duration of aerobic conditions in an emplacement drift between a few years and several decades; our results show that anaerobic conditions may be reached within a few weeks up to maximum a few months after closure of an emplacement drift for spent fuel.

Adsorption Behavior of Trace Beryllium (II) onto Metal Oxide Nanoparticles Dispersed in Water

Radioactive trace 7Be produced in cooling water systems for high-energy accelerators is known to be captured by metal-oxide colloidal nanoparticles generated through corrosion of metal components in water. This study is aimed at investigating the adsorption behavior of trace Be2+ onto various oxide nanoparticles (Al2O3, SiO2, TiO2, Fe2O3, CoO, and CuO) dispersed in water at 25 °C in order to clarify the tendency and features of the interaction of Be2+ with metal oxides. From pH dependence of the distribution ratio of Be2+ between the nanoparticle phase and the aqueous solution phase, the surface complexation constants (βs,n) have been determined for the reaction of Be2+ with the hydroxyl groups on the oxide surface (>S−OH), i.e., Be2+ + n >S−OH ⇄ (>S−O)nBe(2−n)+ + n H+. The n values are generally 1 and 2 and the sequences of the βs,n values are Fe2O3 > TiO2 » Al2O3 > SiO2 for βs,1 and Fe2O3 > TiO2 > SiO2 > Al2O3 >> CoO » CuO for βs,2. The dependences of the the βs,n values on the kind of oxide are explained based on the electronegativity of the metal (or Si) composing the oxide.

Microbial Diversity at Iron-Clay Interfaces after 10 Years of Interaction Inside a Deep Argillite Geological Formation (Tournemire, France)

In the context of a geological disposal of radioactive waste in clayey formations, the consequences of microbial activity are of concern regarding the corrosion of metallic components. The purpose of the present work was to characterize the microbial diversity that may have impacted corrosion processes at the interface between re-compacted argillite and steel coupons after 10 years of interaction inside the Toarcian argillite layer in Tournemire (France) under in situ conditions. Several types of steel coupons were introduced in 1999 in two boreholes (so-called CR6 and CR8) drilled in the geological formation and filled with re-compacted argillite. CR6 borehole was drilled horizontally from a century-old railway tunnel and coupons were placed in the undisturbed argillite. CR8 borehole was drilled vertically under the tunnel, in conditions influenced by the draining of the Cernon fault water. CR6 and CR8 boreholes were overcored 10 years later and steel coupons as well as re-compacted argillite samples were analyzed separately. The characterization of their microbial diversity was carried out using culture media and molecular methods using 16S rRNA genes cloning. Data resulting from both approaches were complementary. Isolates and clone sequences were affiliated to only 3 bacterial phyla: Firmicutes, Actinobacteria and Proteobacteria. The biodiversities differed depending on the steel type and the borehole considered, indicating the influence of both iron-clay interactions and in situ environmental conditions. This analysis has highlighted the presence of sulphate-reducing bacteria, iron-reducing bacteria and isolates capable to develop at high temperatures. These microorganisms can grow at the interfaces between materials in a very short period of time compared with planned durations of disposal. Thus, these results should be considered to assess the consequences of microbial activities on the evolution of the metallic components like overpacks.

Possible stibnite transformation at the friction surface of the semi-metallic friction composites designed for car brake linings

After a friction process several changes in phase composition of friction composites are often registered. High temperature, accompanied by high pressure induced during braking can cause initiation of chemical reactions which do not run at room or elevated temperatures under the atmospheric pressure. Most of the studies in the field of tribochemistry at friction surfaces of automotive semi-metallic brake linings deal with phenolic resin degradation and corrosion of metallic components. The paper addresses the formation of elemental antimony as well as the alloying process of iron with antimony observed on the surface of laboratory prepared semi-metallic friction composites containing stibnite. The role of alumina abrasives in the process of stibnite transformation is also discussed and mechanism of stibnite transformation was outlined.

Microbial diversity of the 180 million-year-old Toarcian argillite from Tournemire, France

Even though the microbiology of various subsurface environments has been investigated for more than 30 a, the microbial diversity of deep argillaceous media is still poorly known. In the context of radioactive waste disposal in clayey formations, the consequence of microbial activity is of concern regarding e.g. the corrosion of metallic components. The purpose of the present work was to characterise the cultivable microbial diversity of different zones of the Toarcian argillite of Tournemire (France) as a preliminary indication regarding the potential of development of microbes in such subterrestrial environments. Cores were drilled in the Excavation Damaged Zone (EDZ) and in the deeper undisturbed zone of the argillite layer, as well as in a zone intersected by a geological fault. Samples from the wall of the drift were also collected. Microorganisms were cultivated from all samples, but the biodiversity differed depending mainly on the O2 and moisture content. Aerobic bacteria were identified on the wall, in the EDZ and in the wet faulted area, whereas SO4-reducing bacteria were isolated from the wet faulted area only. Anaerobic heterotrophs were cultivated from all zones. One hundred and twelve isolates were identified. Small ribosomal subunit gene sequences showed that bacteria of the undisturbed zone were affiliated to three genera only, whereas the three other sampled zones harbour more diverse microflora, including isolates closely related to taxons characterized from subsurface, deep marine and polar environments.

Computation of the Couplex-Gaz Exercise with TOUGH2-MP: Hydrogen Flow and Transport in the Pore Water of a Low-Permeability Clay Rock Hosting a Nuclear Waste Repository

Significant quantities of hydrogen can be produced by the corrosion of metal components. It is necessary to forecast gas migration and pressure buildup in the context of deep geological radioactive waste disposal. One of the major problems in representing gas migration in a radioactive waste repository is that of simultaneously modeling all gas sources and complex transfer pathways constituted by the network of underground drifts and the surrounding low-permeability rock. In 2006, the French National Agency for Radioactive Waste Management launched an international multiphase flow simulation benchmark exercise for modeling such a two-phase (gas and liquid) flow system. The exercise was designed to compare the performance of the numerical methods being used to resolve the designed problems. This paper presents the results of test case 2 of the exercise completed by the authors. The three-dimensional model represents a fraction of a repository for long-lived radioactive waste in a clay rock. The model simulates ambient pressure and flow conditions (considering influence of site evacuation on the flow system) after placement of wastes, with full consideration of two-phase initial and boundary conditions. Isothermal conditions are assumed. Time-dependent gas sources are applied to the model. Since the natural environment is unable to evacuate the entire amount of hydrogen in a dissolved state, a free gas phase is formed within the disposal structures. The model is used to study the dissipation of those gases to determine their influence on the transient phases throughout the lifetime of the repository, and to investigate possible pressure buildup, which may introduce a risk of damage to the host rock. We use the model to investigate how the presence of gas in the repository influences the nature of water flow around the disposal structures and the resaturation (process of saturation increasing) transient processes after closure of the repository. The TOUGH2-MP code, a parallel multiphase flow simulator, has been adopted for this study.

Molecular hydrogen: An abundant energy source for bacterial activity in nuclear waste repositories

A thorough understanding of the energy sources used by microbial systems in the deep terrestrial subsurface is essential since the extreme conditions for life in deep biospheres may serve as a model for possible life in a nuclear waste repository. In this respect, H 2 is known as one of the most energetic substrates for deep terrestrial subsurface environments. This hydrogen is produced from abiotic and biotic processes but its concentration in natural systems is usually maintained at very low levels due to hydrogen-consuming bacteria. A significant amount of H 2 gas will be produced within deep nuclear waste repositories, essentially from the corrosion of metallic components. This will consequently improve the conditions for microbial activity in this specific environment. This paper discusses different study cases with experimental results to illustrate the fact that microorganisms are able to use hydrogen for redox processes (reduction of O 2, NO 3 - , Fe III) in several waste disposal conditions. Consequences of microbial activity include: alteration of groundwater chemistry and shift in geochemical equilibria, gas production or consumption, biocorrosion, and potential modifications of confinement properties. In order to quantify the impact of hydrogen bacteria, the next step will be to determine the kinetic rate of the reactions in realistic conditions.

Evaluation of some farm structures in South Western Nigeria

A survey involving the use of questionnaires, personal communication, physical observation and photographic recording was undertaken in South western Nigeria comprising of Ekiti, Ogun, Ondo, Osun and Oyo states to identify the farm structures popularly used, materials used in their construction, their durability and maintenance culture adopted by the users. Farmhouses, cribs, barns, platforms, warehouses, silos, pens, yards and sheds, deep litter houses, palm fronds woven baskets, hutches and cages were the popular farm structures identified. Although a catalogue of materials is available for construction, cost was found to be a major factor in the selection of materials. There was extensive use of locally sourced materials such as wood, natural fibers and earth for the construction of the identified structures. The factors, which tend to reduce the service life and efficiency of these facilities, include roof leaks, abrasion of mud walls, decay and breakage of wooden members, corrosion of metal components, and pitting and cracking of concrete floors. Remedial measures taken include replastering of mud walls and cracked floors, addition of natural fibers to roofs and sealing of leaking points in galvanized roofing sheets, and replacement of broken wood components. These measures where adopted have proved quite useful in improving the efficiency and longevity of the structures. A culture of regular inspection and timely repair of damaged components to prolong the service life and reduce maintenance cost is recommended. Journal of Applied Science, Engineering and Technology Vol. 3(1) 2003: 31-38

Visualization of electrolyte volatile phenomenon in DIR-MCFC

Volatilization of molten salt is one of the factors that control the performance of molten carbonate fuel cells (MCFC). Volatilization of molten salt promotes cross-leakage and the corrosion of metallic components. Moreover, piping blockage is caused by the solidification of volatile matter. Because reforming catalysts filling the anode channel are polluted by molten salt volatile matter in direct internal reforming molten carbonate fuel cells (DIR-MCFC), the volatilization of molten salt is an especially serious subject. However, neither the behaviour nor the volatilization volume of molten salt volatile matter has heretofore been elucidated on. Because molten salt volatile matter that has strong alkalinity cannot be supplied directly to an analyzer, its volatilization volume is small, and analytical accuracy is poor. Therefore, an attempt has been made to elucidate about the electrolyte volatile phenomenon in an MCFC by using a non-contact image measurement technique. A 16 cm 2 MCFC single cell frame has an observation window and an irradiation window. The image of the volatile phenomenon is shown by irradiating a YAG laser light sheet 2 mm thick from an irradiation window into the anode channel, and taking measurements from an observation window with a high spatial resolution video camera (12 bit). As a result, though the volatile matter is not observed in an anode channel at OCV, the volatile matter flows in a belt-like manner from the inlet side near the electrode toward the outlet at a current density of 150 mA cm −2. In addition, volatile matter is difficult to observe with the conventional thickness of an anode electrode. Because the composition of these volatile matters is 15Li 2CO 3/85K 2CO 3 (the result of conversion into molten salt) by ion chromatography analysis, it is not an electrolyte (62Li 2CO 3/38K 2CO 3) but rather the volatile matter of potassium, such as KOH. Therefore, it is understood that the volatile matter K 2CO 3 is generated as KOH, comprising the water generated by the cellular reaction with an electrolyte, in a reaction with CO 2. Conversely, the volatile matter flows to the surface of the cathode electrode without regard to changes in current density. In addition, the volatile matter exists on the electrode surface, although it decreases more or less with the conventional thickness of the cathode electrode. Therefore, it is understood that the volatile matter, in order for it not to be related to the cellular reaction, does not comprise the dispersion of molten salt.

Evaluation of volatile behaviour and the volatilization volume of molten salt in DIR-MCFC by using the image measurement technique

The volatilization of molten salt is one of the factors that control the performance of molten carbonate fuel cells (MCFC). Volatilization of molten salt promotes the cross-leakage and corrosion of metallic components. Moreover, pipe blockage is caused by the solidification of volatile matter. Especially, because reforming catalysts filling the anode channel are polluted by molten salt volatile matter in direct internal reforming molten carbonate fuel cells (DIR-MCFC), volatilizing of the molten salt is a weighty subject. However, neither the behaviour nor the volatilization volume of molten salt volatile matter has been elucidated, because molten salt volatile matter that has strong alkalinity cannot be supplied directly to an analyzer, its volatilization volume is small, and the analytical accuracy is poor. Therefore, an attempt was made to elucidate the behaviour of vaporized alkali hydroxide by using a non-contact image measurement technique. The DIR-MCFC electrolyte is generally 62Li 2CO 3/38K 2CO 3. Consideration was given to the DIR-MCFC catalyst pollution mechanism as follows. Molten salt volatile matter is KOH generated as water generated in the cell reacts with the electrolyte. The generated KOH returns to K 2CO 3 again in high CO 2 concentration regions, and catalyst pollution is caused by the adherence of the K 2CO 3 to the catalyst. Moreover, the K 2CO 3 particles mutually cohere when the generated water assists bonding and blocks the piping. The present report experimentally evaluates the volatilization volume of KOH, the change from KOH to K 2CO 3, and the particulate growth of K 2CO 3, using the image measurement technique. In measuring the KOH volatilization volume, K 2CO 3 is generated as KOH volatilized by heating it in a crucible in an electric furnace reacts with CO 2, and is then injected into a reaction tube. The amount of K 2CO 3 is measured by measuring the image of the K 2CO 3 particle with a YAG laser and a CCD camera, thereby obtaining the KOH volatilization volume from the calculation of the stoichiometry of the amount of K 2CO 3. In order to study the change from KOH to K 2CO 3, the particulate growth of K 2CO 3 can be monitored by taking a picture of a K 2CO 3 particle generated with KOH and CO 2 for an extended period. As a result, a conglomerate is generated by the mutual adhesion small particles, causing piping blockage.

A preliminary investigation into airborne salinity adjacent to and within the envelope of Australian houses

Corrosion of metal components within the building envelope depends primarily on the levels of wetness and pollutants (in Australia the prime pollutant is sea salt) at the components' surface. This paper addresses the levels of airborne salinity within the envelope of a number of Australian buildings. Airborne salinity was measured using the salt candle technique. Salinity levels in the immediate vicinity of, adjacent to, and within the building envelope of six buildings were measured over periods up to one year. The factors affecting the rate of salt deposition are outlined. It is shown that the salt deposition is highly dependent on the distance from the coast. The effect of building structure in reducing airborne salinity levels is estimated. Estimates of corrosion rates in wall cavities resulting from the measured salinity levels are presented.

Thermochemical diagrams for metal-oxygen-sulfur systems: An aid in corrosion research

The corrosion of metallic components is a significant problem in many high temperature processes. In studying such corrosion phenomena, the scientist must identify simpler laboratory environments which can reproduce the corrosion product composition and morphology found in the more complex service environments. The present work was undertaken to develop a graphical method to aid in accomplishing the above objective. A predominantly oxidizing-sulfidizing environment which also contains some carbon was selected as an example. Such an environment is characteristic of processes such as coal gasification and can be produced by mixing CO2, H2, and H2S in appropriate quantities. Starting from selected initial compositions of such gas mixtures, an approach based upon free energy minimization was used to determine which condensed corrosion product phases will be stable for selected metals, temperatures, and total pressure. Graphs with initial CO2/H2 and H2S/H2 ratios as axes were then constructed; in these graphs, areas represent single condensed phases, lines represent two condensed phases in equilibrium, and triple points represent three condensed phases in equilibrium. The graph indicates at a glance the product phases which are possible for a given initial gas composition. When dealing with alloys, diagrams for the component pure metals must be combined.