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Leading edge erosion is becoming increasingly important as wind turbine size and rainfall are predicted to increase. Understanding environmental conditions is key for laboratory testing, maintenance schedules and lifetime estimations to be improved, which in turn could reduce costs. This paper uses weather data in conjunction with a rain texture model and wind turbine RPM curve to predict and characterise rain erosion conditions across Ireland during rainfall events in terms of droplet size, temperature, humidity and chemical composition, as well as the relative erosivity, in terms of number of annual impacts and kinetic energy, as well as seasonal variations in these properties. Using a linear regression, the total annual kinetic energy, mean temperature and the mean humidity during impact are mapped geospatially. The results indicate that the west coast of Ireland and elevated regions are more erosive with higher kinetic energy. During rain events, northern regions tend to have lower temperatures and lower humidities and mountainous regions have lower temperatures and higher humidities. Irish rain has high levels of sea salt, and in recent years, only a slightly acidic pH. Most erosion likely occurs during winters with frequent rain infused with salt due to increased winds. After this analysis, it is concluded that Ireland’s largest wind park (Galway) is placed in a moderate-highly erosive environment and that RET protocols should be revisited.

Within renewable energy, challenging climates can impose great limitations on power generation. In wind energy, rain erosion on turbine blades can create major disruptions to air flow over the aerofoil, reducing the efficiency of the blade and immediately affecting the power output of the turbine. The defects in the materials that cause these inefficiencies are known and can be observed on turbines that have been in operation for extended periods. This work explores the transitions between different wear states for G10 Epoxy Glass under laboratory simulated wind turbine conditions in operation and measures the wear periodically to identify a progression of erosion. Mass loss data and micrographic analysis revealed samples at 45° and 60° displayed increasing erosion when examining erosion performance for angles between 15° and 90° over various exposure and velocities. Erosion maps were constructed, showing the variation of wastage and identifying the performance window of conditions where degradation is minimised.

Selection of a water deoxygenation method presents some challenges due to the broad range of options including physical, chemical, electrochemical and biological techniques. This communication presents the design of an apparatus developed for efficient and simple deoxygenation of water for the purpose of electrochemical corrosion studies in a lab environment. The design is modular and can be scaled to meet processing needs. The operation of the apparatus is based on the combination of nitrogen bubbling and surface absorption to achieve complete and uncontaminated deoxygenation of water. Tests conducted on this apparatus revealed that pressurisation of the apparatus enhances economy and performance while increasing nitrogen injection rate accelerates deoxygenation. However, a point was identified, at which a balance between economy and performance is achieved and further injection rate increase suffers from diminishing returns. Keywords: Deoxygenation, Deaeration, Water

This article presents a study of the erosion resistance of coated and uncoated polymer matrix composites for tidal turbine conditions. It focuses on the development of comparative erosive wear mode and mechanism maps for such materials. In our earlier work, testing of glass-fiber-reinforced polymer composites for tribological applications in marine simulated conditions, several erosion-related issues were highlighted. The combined effects of the NaCl solution and sand dramatically enhanced the erosive wear of the uncoated specimens. In order to address those issues, an erosion-resistant polymeric coating was applied to the composite and tested in marine simulated conditions with an extended range of sand particle size. The test results of the uncoated and coated composite have been compared in this research by erosive wear mode and mechanism maps techniques. These maps reveal that the coating has enhanced the erosion resistance. These findings provide significant progress toward materials selection approaches to manufacture of tidal turbine blades.

Hail impact-induced erosion has the potential to significantly affect the operational lifetime of structures exposed to extreme weathering environments such as hail events. Computational materials modelling can be used to better understand the erosion behaviour during a hailstone impact, and here the relevant background work is detailed. In this paper, an implementation of an ice impact model, utilising Smooth Particle Hydrodynamics along with a highly strain-rate-dependent material model, is shown, and its results and limitations discussed. An overview is given on the literature on modelling hail events, including the history of experimental work. The various potential modelling methods which have been developed is then given, along with an evaluation of the suitability of the methods to future work in this area.

Erosion rates of wind turbine blades are not constant, and they depend on many external factors including meteorological differences relating to global weather patterns. In order to track the degradation of the turbine blades, it is important to analyse the distribution and change in weather conditions across the country. This case study addresses rainfall in Western Europe using the UK and Ireland data to create a relationship between the erosion rate of wind turbine blades and rainfall for both countries. In order to match the appropriate erosion data to the meteorological data, 2 months of the annual rainfall were chosen, and the differences were analysed. The month of highest rain, January and month of least rain, May were selected for the study. The two variables were then combined with other data including hailstorm events and locations of wind turbine farms to create a general overview of erosion with relation to wind turbine blades.

Erosion-corrosion maps rarely take into consideration the role the rebound velocity has in extending the transition boundaries. Furthermore, although impact angle is an important and widely studied variable in experimental erosion-corrosion mapping, there have been few studies on theoretical treatments of this variable on such maps. In addition, the role of pH in changing the transition boundaries has been rarely modeled. In this chapter, the effect of elastic rebound velocity and impact angle on erosion-corrosion maps are explored at various pH values. How such variables can be modeled are indicated and future directions in this field are suggested.

The effect of chloride on erosion-enhanced corrosion was studied experimentally and by a multiphysics algorithm developed to describe the erosion-corrosion interactions. API 5 L X65 steel was exposed to a slurry jet of different chloride content (0.005, 0.05 or 0.5 M) containing silica particles (250–350 μm). An electrochemical-transport-reaction model was used for numerical simulation of polarization curves. Visualization of the flow conditions was also carried out in this work. The effect of erosion on corrosion was found to be well described as a proportionality factor between the kinetics constants of the electrochemical reactions with and without the erodent. The presence of chloride was found to affect the system mainly through increased conductivity of the electrolyte.

The micro-abrasion wear mechanisms for CoCrMo against variable size alumina balls, representing typical artificial femoral head sizes, were investigated over a range of applied loads in foetal calf serum solution. SEM analysis of resulting wear scars displayed two-body and mixed-mode abrasion modes of wear. The wear factor, &kappa, was found to range between 0.86 and 22.87 (10&minus, 6 mm3/Nm). Micro-abrasion mechanism and wastage maps were constructed for the parameter range tested. A dominant two- to three-body abrasion regime was observed with an increasing load and ball diameter. The 28-mm ball diameter displayed the lowest wastage, with an increasing load. Proteins may act to reduce the severity of contact between abrasive particles and bearing surfaces. Wear volumes did not necessarily increase linearly with applied load and ball diameter, therefore, there is a need to develop more accurate models for wear prediction during micro-abrasion conditions. Wear mapping for hip replacements could provide a useful aid for pre-clinical hip wear evaluations and long-term performance.

Climate change is rapidly forcing the world to create renewable energy that is capable of sustaining future energy requirements globally. The generation of renewable energy at a comparatively lower cost is a major challenge for this industry. Unforeseen weather conditions and environments such as offshore conditions or involving acid rain have a significant effect on the degradation of structural materials of renewable energy devices. For the investigation of droplet erosion behavior of the advanced material for the wind turbine blades, experimental work was carried out on a glass fiber-reinforced epoxy (GFRE) composite in different environments. A whirling arm rig was used for this experimental work in a laboratory-simulated rainfall conditions at a constant tip speed of the rotor blade. Three types of rainwater were used for a range of angles of attack from 15 to 90 deg in an increment of 15 deg. Erosive wear maps have been constructed to show the weather, location, environment, and raindrop erosion effects on the degradation of the wind turbine blade material. This map predicts that erosion in saline and acidic rain conditions acts synergistically on the blade material, which results in delamination between the fiber layers, pit formation, and development of micro stresses leading to loss of adhesion of reinforcement fibers.

Chromium (Cr) containing steels were tested to analyse corrosion behaviour in carbon dioxide saturated water of varying salinities with extended exposure time. Both potentiodynamic and mass loss data were collected to gain a better understanding of the corrosion mechanisms. It was found that both the high Cr steels displayed degradation in the form of pitting with increasing salinities. However, the low alloy steel reference material showed uniform iron carbonate (FeCO3) precipitation. The use of high salinity precipitated layers to aid corrosion protection in lower salinity seawater environments was then established as an interesting area for greater examination. Subsequently, samples of the low alloy steel previously corroded in solutions of 7, 14 and 28% sodium chloride (NaCl) concentration were then tested in seawater salinities of 3.5% NaCl. It was found that both the 7 and 14% NaCl pre-corroded samples resulted in a significant reduction in the corrosion rate when compared with non-pre-corroded samples. The 7% NaCl pre-corroded sample showed the greatest reduction in corrosion rate, and through SEM analysis of the layer both on the surface and cross-section it was found to display an iron carbonate layer more densely packed and defect free. This indicated the potential benefits of high salinity pre-corrosion techniques to aid protection in seawater environments.

Tribo-Corrosion addresses the interactions between tribology and corrosion. The synergy between mechanical degradation i.e. due to tribology and chemical degradation from corrosion has led to the interdisciplinary science of Tribo-Corrosion. Following formation of the international Tribo-Corrosion network in the UK in 2001, and the European Federation of Corrosion working party on Tribocorrosion in 2003, the 1st international symposium on Tribo-Corrosion was held in Hyderabad, India in 2006. The 2nd, 3rd and 4th symposiums were held in Wiener Neustadt, (Austria) 2009, Atlanta, (USA) 2012 and Glasgow, (UK) respectively 2014. The 5th symposium returned to Hyderabad, India in 201.

Wind turbine blade damage, particularly leading edge erosion, is a significant problem faced by the renewable energy industry. Wind turbines are subject to a wide range of environmental factors during a 20 + year lifespan, with hailstones often touted as a key contributor to the deterioration of the blade profile. An experimental campaign was carried out to investigate the effects of repeated impact of smaller diameter simulated hail ice (SHI) on composite materials, to correspond to those most prevalent at wind farm locations. Hailstones of four different diameters (5 mm, 10 mm, 15 mm and 20 mm) were fired at velocities in the range of 50 m s − 1 to 95 m s − 1 . Samples used for experimentation were manufactured from triaxial stitched glass fibre [0°/ − 45°/+45°] and epoxy resin. Damage was evaluated in terms of sample mass loss and microscopy of the composite surface. For all examples, mass loss was negligible and optical microscopy showed little evidence of surface damage. Surface degradation was discernible under scanning electron microscopy for the larger diameter SHI ( ≥ 15 mm ), with projectile velocity a notable factor in the extent of the damage. Even for large numbers of impacts, there was little noteworthy damage caused by smaller, more prevalent SHI ( ≤ 10 mm ). This suggests that hail is not a direct cause of wind turbine blade erosion.

This paper represents the investigation of rain erosion on wind turbine blade materials under load in the simulation of onshore and offshore environmental conditions. The experimental work was carried out on a whirling arm rig with the material under a static 3 point bend to simulate large multi-megawatt wind turbine blades flexing during operation. This experiment was run with both fresh water and salt water to simulate onshore and offshore turbines. The results showed that the effects of a pre-stress on the samples resulted in a higher degradation rate following rain drop erosion. The microscopic analysis of the samples exposed to pre-stress identified distinctive surface features which has been termed a surface impact circular deformation. These features showed signs of cracking which enhanced the erosion rate. The pre-stressed samples also encountered a larger crossover in erosive mechanisms of abrasion and direct impacts; this was theorised to be due to the material being close to its yield stress and more likely to plastically deform.

In renewable energy, wind capture has been expanding to now have one of the largest presences in the global green energy sector. With the drive to expand low carbon technologies; maintenance of the engineering components of wind turbines is crucial and in particular the monitoring of the leading edge of turbine blades which experience high impact velocities in service. Surface changes due to rain drop erosion can reduce energy conversion due to a loss of aerodynamic efficiency. This is one of the key areas of interest, as even small aerodynamic changes can lead to 2–3% loss in annual energy. Inspection methodologies of turbine blades are basic, involving an observation and high-definition photographs of the damage. Recent studies on the rain erosion of turbine blade materials show that this standard procedure often fails to characterise the loss of aerodynamic efficiency in these turbine blades in. With the industry moving in the direction of leading-edge profile samples, there is a consensus that whirling arm type test rigs are the most applicable testing regimes. Presently there is little overlap in the analysis used in different studies. This review considers various techniques which may be used to inspect and characterise the materials performance following exposure to rain drop erosion. These techniques will be evaluated based on their potential use within the industry. Findings conclude that a combination of techniques is optimal to analyse surface defects and that subsurface analysis is an important factor that must be considered in any investigation of long-term blade integrity.

Although he was better known as a scientist than a reformer, Matthew Fontaine Maury’s influence as the latter was hardly negligible. Maury argued for institutional expansion and reform during a period of agitation and stagnation for the American navy. Published in Richmond’s Southern Literary Messenger between 1840 and 1841, Maury’s five ‘Scraps from the Lucky Bag’ agitated for wide-ranging reforms aimed at tackling the numerous inefficiencies and inadequacies of the navy. His proposed reforms served multiple purposes. Naval reform was, for Maury, a matter of necessity, and advocating for it permitted him to challenge the limited role that the navy occupied in 1840. It also served as a way for Maury to address the anxieties of the antebellum South’s maritime interests and make the case for real protection of Southern coastal waters. Lastly, Maury’s plan of reform was based in and allowed a re-imagination of the navy as the modern, powerful arm of an ambitious national project. This article considers Maury’s ‘Scraps from the Lucky Bag’ as both advocacy for naval reform and a specific vision of both the South and the nation. Situating Maury within American anxieties over expansion and international interference, this article argues that Maury leveraged, or attempted to leverage, those anxieties to achieve his goal of reform. Maury’s advocacy for naval reform was not only an argument for a larger, more technologically advanced and better organized force, but also for the territorial and maritime expansion of the United States. For Maury, these projects were fundamentally linked. A reconsideration of Maury’s efforts towards naval reform opens a window on the conflicting visions and anxieties of American expansion, both national and sectional, as well as the configuration of the American navy in the mid-19th century.

Wear and corrosion in artificial hip replacements are known to result in metal ion release and wear debris induced osteolysis. This may lead to pain and sensitivity for patients. This infers that pre-clinical testing is critical in determining the long-term performance, safety, and reliability of the implant materials. For this purpose, micro-abrasion-corrosion tests were carried out on a biocompatible material, Ti-6Al-4V ELI, using a T-66, Plint micro-abrasion test rig in conjunction with Gill Ac corrosion testing apparatus for the range of applied loads and electrical potentials in the hip joint simulated environment. A Ringer&rsquo, s solution, with and without an abrasive particle (silicon carbide), was used to enable the interactions between abrasion and corrosion. In this paper, the effects of applied load and electrochemical potential on the tribo-corrosion behaviour of Ti-6Al-4V in a bio-simulated environment are presented. The wastage, micro-abrasion-corrosion mechanisms, and synergy behaviour were identified and mapped. A significant difference in corrosion current densities was observed in the presence of abrasive particles, suggesting the removal of the protective oxide layer. The results also indicate that Ti-6Al-4V had significant abrasive wear loss when coupled with a ceramic counterpart. According to the mechanism, micro-abrasion plays a predominant role in the abrasion-corrosion behaviour of this material and the material losses by mechanical processes are substantially larger than losses, due to electrochemical processes.

This paper represents the investigation of liquid impacts on wind turbine blade materials in the simulation of onshore and offshore environmental conditions. G 10 epoxy glass laminate was used as a specimen material. The experimental work was carried out on a raindrop erosion test rig at the varying angles of attack for a range tip speed. Two solutions, i.e. pure and salt water, were used to highlight the effects of offshore environment on this material when it is being used as wind turbine blades. Test results show that the erosive wear increased with an increase in droplet impact velocity. Erosion mapping techniques were used to compare the erosive wear behaviour of this material for application to onshore and offshore applications as candidate wind turbine materials.

Synergistic effect between corrosion and wear has been widely recognized in many tribo-corrosion systems. In most wet application conditions, dissolved oxygen (DO) is a controlling factor to the dynamics of corrosion process and is therefore expected to have significant impact on the tribo-corrosion performance of materials. In this study, the effect of DO (0 - 24 ppm) on erosion-corrosion behaviour of En30B low alloy steel has been investigated using a slurry pot erosion-corrosion test apparatus in a slurry containing 35wt% silica sand and 3.5% NaCl solution at 30°C and 45°C. The synergistic effect and its contributing components, i.e., erosion-enhanced corrosion and corrosion-enhanced erosion, have been measured/analysed. The total erosion-corrosion loss and synergy of the En30B steel increases with DO in the slurry, initially rapidly at DO levels below ~5 ppm and then less rapidly at the higher DO levels. The synergistic effect is mainly due to corrosion-enhanced erosion with negligible contributions from erosion-enhanced corrosion. Temperature has a significant effect on the total erosion-corrosion loss. Total erosion-corrosion was 34% higher at 45°C (in still air) than at 30°C. Mechanisms for the observed phenomena have been discussed based on the concept of corrosion-accelerated micro-crack propagation.

A fundamental study of wear transition regimes was carried out for a pin-on-disk sliding couple, involving titanium and steel. The sliding speed was varied from 0.38 to 1.5 m s−1 and the normal load from 10 to 50 N. Wear mapping approaches have been undertaken to represent the transitions in wear modes and wear mechanisms regimes, as a function of applied normal loads and sliding speeds and for both pin and disc separately on the basis of experimental results. Dry sliding wear behaviour of steel was characterized by tribo-oxidative wear with high material transfer from the titanium. In contrast, adhesive wear was more prevalent for the titanium and oxidative wear mechanisms led to formation of non-protective films on the surface.

Wind turbines are subject to a wide range of environmental conditions during a lifespan that can conceivably extend beyond 20 years. Hailstone impact is thought to be a key factor in the leading edge erosion and damage of wind turbine blades. Along with the size and density of the hailstone, the aggregated impact velocity components are crucial variables that characterise the kinetic energy associated with singular impact. These components include: the terminal velocity of the hailstone, the mean wind speed and the rotational speed of the turbine. Theorised values for the impact velocity may not truly reflect the conditions experienced by wind turbine blades. Using UK meteorological data, a greater representation of hail characteristics, occurrence probabilities and realistic impact component velocities is proposed, which will assist in the development of a realistic damage model for hailstone impact.

In this work, a fundamental study of the wear transition regimes with respect to sliding speed and normal load was carried out for a pin-on-disk sliding couple, involving hardened steel (disks) and titanium base titanium carbide composite coatings (pins). The coating was deposited using a Tungsten Inert Gas (TIG) welding torch melting process. The sliding speed was varied from 0.38 to 1.5m s-1, and the normal load was varied from 10 to 50N. Dry sliding wear behaviour of the disks was characterized by abrasive-oxidative wear at lower normal loads while adhesive-oxidative wear predominated at higher loads with iron oxide transfer to the TiC composite coated pins. In contrast, micro-polishing and adhesive wear predominated for the TiC composite coatings pins along with very mild abrasive wear in evidence. However, the wear regime depended on the conditions with a range of transitions observed over the sliding speeds and loads tested. Wear maps have been constructed to represent the wear mode transitions and the observed wear mechanisms have been discussed.

In this work, a study of the wear transition regimes was carried out for a pin-on-disk sliding couple, involving two steels of different hardness and Cr contents. Dry sliding wear behaviour of the more highly alloyed stainless steel was dominated by adhesive wear and tribo-oxidation at relatively low sliding speeds and by mixed and adhesive wear at high speeds and loads. In contrast, oxidative wear was more predominant for the lower alloyed steel. The individual wear maps generated for the individual components i.e. material and counterface are discussed in the context of the wear mechanisms observed in the tribological contact.

There has been significant progress in implant research during last the 10 years (2005–2015). The increase in the elderly population coupled with a lack of proper physical activity is a potential cause for the sudden increment in implant usage. Implant life and performance are influenced by several parameters; however, literature showed that corrosion, tribology, and tribocorrosion processes of implant materials are main concern and driving mechanisms in the degradation processes. There is currently a large need for research in this area. Furthermore, there has been no recent systematic literature review to analyze the progress of research and published work in this area. The objective of this work is to provide a trend in the published articles in the area of corrosion, tribology, and tribocorrosion during last century, with emphasis on the progress over the last 10 years. The paper also tries to report the current state-of-the-art research in the area of corrosion, tribology, and tribocorrosion research in bio-implants based on number of published articles. The reviews demonstrate that during the last 10 years, there has been significant progress in implant research, particularly in the tribocorrosion area, however, significantly lower than tribology and corrosion research.

Stainless steel can be used as a dental implant. However, there has been little work on the micro-abrasion of such materials in laboratory simulated oral environments, where abrasion, sliding wear can interact simultaneously. In this study, the effects of applied load, and exposure time were evaluated for a 316 stainless steel in a laboratory simulated artificial saliva. Polarization curves showed an enhancement of corrosion current density with increases in applied load. Wear maps were produced showing wear safety regimes at intermediate loads and exposure times. Possible reasons for such trends are interpreted in terms of the ability of the passive film in providing resistance against third body particle impact and the concentration of particles in the contact at higher loads.

The growth kinetics of tetragonal and monoclinic ZrO2 crystallites in 3 mol% yttria partially stabilized ZrO2 (3Y-PSZ) precursor powder has been investigated using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) specific surface area analysis, transmission electron microscopy (TEM) and high resolution TEM (HRTEM). After calcination of the 3Y-PSZ precursor powder between 773 and 1073 K for 2 h, the crystalline structures were composed of tetragonal and monoclinic ZrO2 as the primary and secondary phases, respectively. When the 3Y-PSZ precursor powder was calcined at 773 K for 2 h, the BET specific surface area was 97.13 m2/g, which is equivalent to a particle size of 10.30 nm. The crystallite sizes determined via XRD and BET agreed well, indicating that the powder was virtually non-agglomerated. The growth kinetics of tetragonal and monoclinic ZrO2 crystallite isothermal growth in the 3Y-PSZ precursor powder are described.

The phase transformation behavior of freeze-dried 3 mol% yttria–partially-stabilized zirconia (3Y–PSZ) precursor powder has been studied. When the freeze-dried 3Y–PSZ precursor powder was calcined at 773–1073 K for 2 h, the crystalline structure was composed of tetragonal and monoclinic ZrO2 as primary and secondary phases, respectively. The freeze-dried 3Y–PSZ precursor powder after calcination at 773 K, the monoclinic ZrO2 content abruptly increased from 8.00% to 31.51% and the tetragonal ZrO2 content suddenly decreased from 92.00% to 68.49%, with the duration increasing from 0.5 to 1 min. The activation energy of the isothermal transformation from tetragonal to monoclinic was 7.02 kJ/mol. The kinetics equation for the phase transformation from tetragonal to monoclinic in the freeze-dried 3Y–PSZ precursor powder between 773 K and 1273 K for various durations is described as ln(1/1−α)=1/2.61[t2.61(1.50×10−3)2.61exp(−7.02×310/RT)]; whereas, the HRTEM image shows a typical monoclinic ZrO2 domain because of the stress-induced tetragonal to monoclinic ZrO2 martensitic transformation that has occurred.

The object of this work is to investigate the micro-abrasion of Y-TZP in tea. This material is a candidate replacement veneer in dental restoration and to date there has been very little work carried out to investigate the wear behaviour in oral cavity conditions. Various additions such as milk and sugar, which affect the solution viscosity and pH, were assessed as part of this work and the results were compared to the performance of the material in aqueous conditions. Wear maps were generated showing the change in wear rate as a function of applied load, viscosity and exposure time.

Tidal energy, of all marine renewables energy, possesses higher persistency and predictability over long time scales. Moreover, the higher density of water than air also results in greater power output from a tidal turbine than a wind turbine with similar dimensions. Due to the aggressive marine environment, there are barriers in the development of tidal power generation technology. In particular, with regard to increased rotor diameter, the selection of material presents significant challenges to be addressed including the tribological environment, such as solid particle erosion, cavitation erosion, the effect of high thrust loading on the turbine blade tips, and the synergy between sea water conditions and such tribological phenomena. This research focuses on producing and testing a variety of composite materials with different fibres and reinforcement layouts to evaluate two main tribological issues in tidal environments: matrix cutting and reinforcement fracture. A slurry pot test rig was used to measures the effects of different impact angles and particles sizes at constant tip speeds.

In previous studies of erosion-corrosion, several different theories have been developed to produce a model which represents the relationship between particle erosion and chemical corrosion. Regimes in the models define how the two mechanisms behave relative to one another, whether it is erosion dominated, corrosion dominated. This paper investigates the effect of particle and target material on the erosion-corrosion mechanisms. The performance of Fe as the target material will be modelled when considering particle concentration and size. A comparison is made between the erosion-corrosion mechanisms of Fe, Ni, Al and Cu under different conditions of particle size and concentration. By producing several maps, the regimes and wastage rates predicted as functions of velocity and applied potential will be discussed.

In this study, the combined effects of erosion and corrosion on carbon steel were investigated in three environments containing crude oil, reservoir water, and a mixture of both solutions at a range of applied potentials, velocities and impact angle. The results indicate that the corrosion contribution was augmented with an increase in the percentage of reservoir water. Both the erosion and corrosion contributions increased with impact velocity for all three environments. Following exposure of the carbon steel in the crude oil, the extent of the erosion was greater than that of corrosion, whilst in the reservoir water, the erosion and corrosion contributions were similar. Mechanisms of erosion-corrosion were proposed based on the change in erosion behaviour at various impact angles and applied potentials in the various environments. Erosion-corrosion maps were constructed based on the results, showing the change in mechanisms and wastage rates as a function of impact velocity and applied potential at various impact angles.

Tribology of bio-implants is a major limiting issue in materials selection of the appropriate implant for the appropriate patient activity level [1]. For example, for wear of replacement hip joints, wear caused by the sliding action of the bearing surface of the femoral head against the counterface occurs in synovial fluid. Hence, the major challenge of materials scientists in replacement of such materials is to optimize the wear resistance, minimize any potential tribo-corrosion interaction and adverse biocompatibility effects caused by such interactions and reduce wherever possible any adsorption of wear debris into the surrounding tissue. In Tribology, and in Aqueous Corrosion, various mapping methodologies[1-7] have been developed to characterize the various interactions. The wear map developed by Lim and Ashby [2] classifies the wear regimes at ambient conditions in terms of applied load and velocity, illustrating significant temperature rises and attendant corrosion reactions as a function of the tribological variables. The Pourbaix diagram[8] considers various transitions in terms of potential and pH, therefore presenting corrosion regimes as a function of the driving force of the electrochemical reaction and the hydrogen ion concentration. In tribo-corrosion, there is an extensive recent literature combing the concepts of both approaches to construct tribo-corrosion maps [2-8]. Despite such work, there has been very little work carried out until very recently[9] on the construction of tribo-corrosion maps for application to bio-tribo-corrosion environments. This is despite the fact that such maps may have significant application in optimizing materials for specific patient activity/mass combinations, all of which are important in selection of the most appropriate material combination in total replacement joint procedures. In studies of wear of candidate hip joint materials, it has been observed that particle concentration of wear debris can have an adverse effect on loosening of the joint, leading to osteolysis and potential revision of the replacement joint material [10]. In such cases, it is important to identify the effects of wear debris on the tribo-corrosion mechanism [12]. Assessing the effects of such particle concentrations with load is also of significance as it will indicate what dependency, if any, particle concentration has at various body masses as defined by variation of applied load. Hence, in this paper, the effect of applied load and abrasive concentration were assessed at a range of applied loads for Ti rotating against an inert Zirconia ball, in which abrasive particles of SiC were entrained in Hanks solution. The results were used to construct micro-abrasion-corrosion maps for application to biological environments. The significance of the bio-tribo-corrosion map in identifying mechanisms of wastage and the extent of synergy between the tribological and corrosion processes is addressed in this paper.

The process of micro-abrasion–corrosion has been the subject of much research in recent years due to the fact that the action of micron sized particles, typically less than 10 μm in diameter, can cause significant degradation of materials in many diverse environments involving aqueous corrosion. Cermet based coatings are often used to combat micro-abrasion–corrosion, but there has been little work carried out to characterize the performance of such coatings exposed to micro-abrasion–corrosion or to provide a basis for coating optimisation. In addition, a basis for defining the various micro-abrasion–corrosion interactions has not been suggested to date. In this study, the micro-abrasion–corrosion performance of a Ni–Cr/WC coating was assessed and compared to the performance of the steel substrate. The results were used to identify regimes of micro-abrasive wear as a function of applied load and pH of the solution. In addition, micro-abrasion–corrosion maps were constructed based on the results, showing the variation between micro-abrasion–corrosion regimes, as a function of applied load and pH of the solution.

In this paper, a model is generated of the effect of temperature on the erosion–corrosion of Fe in aqueous conditions, for room temperature to 373 K. The results indicate how the transition from active to passivation dominated regimes for Fe is favoured as the temperature is increased. 2D and 3D maps are constructed showing the transitions between erosion–corrosion regimes.

In recent years, the development of thin film systems for decorative applications has attracted significant attention in scientific research. These decorative coatings require, not only an attractive appearance for market applications, but also an ability to protect the surface underneath. Because of this, corrosion, wear and their combined effects (termed tribo-corrosion) are particularly important for lifetime prediction. The tribo-corrosion behaviour of a range of single layered titanium oxycarbide, TiCxOy,coatings, produced by DC reactive magnetron sputtering, has been studied and reported as a function of electrode potential (-0.9 V, -0.5 V, 0.0 V and +0.5 V) and applied load (3, 6 and 9 N). The study was conducted in a reciprocating sliding tribosystem (Plint TE 67/E) in a bio fluid (an artificial perspiration solution) at room temperature. During the wear tests, both the open-circuit potential and the corrosion current were monitored. The results showed that electrode potential and load have a significant influence on the total material loss. The variations in Rp (polarization resistance) and Cf(capacitance) before and after sliding, obtained by Electrochemical Impedance Spectroscopy (EIS) were evaluated in order to provide an understanding of the resistance of the film in such conditions. Tribo-corrosion maps were generated, based on the results, indicating the change in mechanisms of the tribological and corrosion parameters for such coatings.

The low-stress three body abrasion behaviour of a range of steels was investigated. The tests were carried out in a rubber wheel tester (according to ASTM G65-94, reapproved in 2000) at room temperature. The abrasive particles used were angular alumina particles of four different sizes. The results showed that, in general, the smaller particles (50 and 125 μm average size) caused more damage. With these particles, observations of surface morphology indicated a more intense cutting and ploughing action, leading to more damage, whereas bigger particles i.e. larger 250 and 560 μm particles produced less damage, and their action involved more plastic deformation type wear. The 304 SS had a lower abrasion resistance than the 310 SS. For the austentic and ferritic steels the subsurface deformation was larger for impact with the coarser particles. Variations in substrate hardness had no effect on the abrasive behaviour observed. On the whole, the hardest steel (mild steel in martensitic condition) showed the higher extent of damage, irrespective of particle size.

Erosion by solid particles in oil/water slurries is a technologically important area. In such conditions, it is necessary to distinguish between the effects of the sand, aqueous environment, and the oil. Erosion–corrosion maps provide a means of identification between erosion–corrosion regimes as a function of erosion and corrosion parameters. However, there has been no work carried out to map the effects of parameters in oil/water slurries. This paper investigates the effect of erosion–corrosion on carbon steel in oil field production and maps the results. Distinctions between “synergistic” and “additive” erosion–corrosion behaviour are superimposed on the maps in the various environments.

Erosion–corrosion of materials in aqueous environments is a complex phenomenon involving a very large number of variables. In such cases, characteristics of the target, particle and the environment affect the degradation mechanism. Predicting material behaviour may sometimes be a “black art” due to the parameter size which is involved in such processes. In studies of erosion–corrosion, there have been significant advances in the modelling of such processes in recent years. Various methodologies employed include quasi-static modelling, using CFD modelling and erosion–corrosion mapping. In such cases, the output of the various models can differ significantly. In this work, a methodology combining CFD modelling and erosion–corrosion mapping has been developed to model the erosion–corrosion behaviour of pure metals, which variously passivate and dissolve under a range of simulated conditions. This provides a means of mapping the component undergoing erosion–corrosion and thus is a step change on previous modelling work in this area as it enables superimposition of the erosion–corrosion map on real surfaces. The relative advantages and limitations of this approach are discussed in this paper.

Materials exposed to aqueous slurry environments must not only resist the impact of solid particles and the flowing environment but also the degradation caused by electrochemical corrosion. In this study, the combined effects of slurry particle concentration and velocity on the erosion-corrosion of a WC/Co-Cr coating were assessed at a range of electrochemical potentials in a synthetic sea water solution containing sand particles and compared to the performance of a mild steel exposed to similar conditions. The erosion and corrosion contributions and their interactions were evaluated for the materials. The results indicated that the erosion-corrosion mechanism of the coating and the mild steel showed significant differences when particle velocity and concentration were increased at various potentials. For both materials, degradation mechanisms were identified and superimposed on erosion-corrosion maps. Maps indicating levels of wastage, extent of synergy between the processes and the optimum material performance were also generated as part of this study. Scanning electron microscopy was used to confirm the degradation regimes and mechanisms of material removal during the erosion-corrosion process.

The fourth International Conference on Tribo-Corrosion was held in Glasgow from 9–11 April 2014 and had a distinctively Gaelic flavour, with the city of Glasgow being the gateway to the Gaelic traditions encapsulated in the Highlands and Islands of Scotland. An electic group of participants took part in the conference from 23 countries which was the first time the international conference series was held in Scotland (a 2 day workshop of the Tribo-Corrosion Network, TrI-CorrNet was held in Glasgow in 2002).