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Graphical abstract Highlights • Thermodynamic parameters of Fe-based glasses hop as c Nb rises from 7 to 10 at.%. • Passive ability of these glasses increases drastically as c Nb rises from 7 to 10 at.%. • Netlike structure in these glasses associated with Fe 23 B 6 cell is verified with simulations. • Netlike structure explains the structure and passivation changes in these glasses. Abstract The atomic structure and corrosion behavior of Fe 87- x B 13 Nb x (x = 0, 7, 10 and 13) metallic glasses were investigated using various experimental techniques and simulations. The netlike (Fe, Nb) 23 B 6 structure units, which took root in the Nb-contained amorphous matrix, emerged after annealing and raised markedly corrosion resistance of as-spun amorphous samples as c Nb > 7 at.%, such as the occurrence of wider passive platform in the potentiodynamic polarization plots and the transformation from the porous holes to stable passive films on corrosion surfaces. [ABSTRACT FROM AUTHOR]

Abstract In this work, the passivation behavior of Nb in acid fluoride-containing solutions with pH of 4, 5 and 6 was investigated. Both electrochemical measurements and surface characterization were systematically used to explore the pH effect on the electrochemical stability of Nb in aggressive oral cavity environment. The point defect model (PDM) and surface charge approach (SCA) were used as theoretical basis to analyze the passive film growth and dissolution kinetics. As the pH value decreases, the passive film becomes more reactive and suffers more severe dissolution, leading to higher point defect density across the passive film and more pronounced surface charge behavior at the film/solution interface. Furthermore, the surface becomes rougher and the passive film is thinner with less amount of suboxide as the solution is more acid. Since high electrochemical stability of the passive films is desirable for Nb implants, the results from this work shed insight into the use of fluoride-containing prophylactic substances. Highlights • pH dependent passivation behavior of Nb in acid F−‒containing is examined. • The PDM and SCA are used to analyze the film growth and dissolution kinetics. • The pH effect is quantitatively characterized with kinetics parameters. • The decrease of pH promotes the dissolution reactivity of the passive film. • The decrease of pH leads to a rougher and thinner passive film with less suboxide. [ABSTRACT FROM AUTHOR]

The mechanism of passivity breakdown on Cu 2 O films was studied. The thickness and components of the film were estimated by EIS, AES and XPS analyses. The structural relaxations, energies, electronic properties and diffusion coefficients were calculated by first-principles calculations. Both the experimental and calculated results demonstrate that the film thinning is due to the adsorption of Cl − on the surface instead of a penetration process. The inner point defects facilitate the adsorption of Cl − , and the introduction of Cl − , in turn, increases the transport rate of point defects. A theoretical model was proposed, which is also applicable to local breakdown. [ABSTRACT FROM AUTHOR]

This paper investigates the carbonation of two low-calcium fly ash-based geopolymer concretes to assess the effect of alkali concentration in the activator, and the carbon dioxide concentration on the pH drop and passivity of the reinforcement. Chemical adsorption of carbon dioxide at different concentrations into an aqueous NaOH solution, as representative of the pore solution, is studied to predict the distribution of carbonate species and pH drop. pH profiles were obtained during the exposure period. X-ray diffraction (XRD) was conducted to identify the carbonate phases. Half-cell potential and polarization resistance of reinforced concrete samples were monitored to assess the passivity of embedded reinforcement. The carbonated binders remained rather highly alkaline during the accelerated carbonation test which was in agreement with the predicted values. No sign of depassivation of reinforcement was observed, even for the lower strength grade concrete, during the long exposure time of 500 days to 1% carbon dioxide. [ABSTRACT FROM AUTHOR]

This study addresses the influence of Na 2 B 10 O 16 , which may be used for criticality control of fuel debris in the Fukushima Daiichi Nuclear Power Station, on the corrosion behavior of carbon steel in diluted artificial seawater. The corrosion forms of carbon steel were categorized as uniform corrosion, localized corrosion, and passivity based on the balance between the dilution ratio of artificial seawater and the concentration of Na 2 B 10 O 16 . The changes in corrosion forms were arranged on a water quality region map. Passivity was maintained by adding 3.7 × 10 −2 M or more of Na 2 B 10 O 16 to artificial seawater with a dilution ratio of 100-fold or more. The criticality control of the fuel debris and corrosion mitigation of the carbon steel components may be achieved simultaneously in the water quality. The prediction of the corrosion form of carbon steel was attempted by the extended Larson–Skold Index (LSI) = ([Cl − ] + 2[SO 4 2− ])/([HCO 3 − ] + 2[B 10 O 16 2− ]). However, because the passivating action of B 10 O 16 2− was remarkably stronger than that of HCO 3 − , the prediction was difficult under the simple addition of equivalent concentrations. The localized corrosion of carbon steel under the addition of Na 2 B 10 O 16 preferentially occurred from the crevices of the test specimens, as was the case in stainless steel. [ABSTRACT FROM AUTHOR]

Passivity breakdown and the pitting behavior of ultra-high strength 300 M and S280 steels, which are commonly employed for aircraft landing gear, in the presence of chloride has been explored and compared, and the data were interpreted using the point defect model (PDM). The breakdown behavior was studied using cyclic potentiodynamic polarization while SEM and digital confocal microscopy were employed to explore the micro morphology and depth distribution of pits. The cumulative distributions in the breakdown voltage are near-normal, which are consistent with the PDM, assuming the distributions of potential breakdown sites in terms of the cation vacancy diffusivity for different concentrations of chloride are normal. Compared to 300 M, S280 steel exhibits shallower pitting and is more resistant to breakdown. From the potential scan rate dependence of the breakdown potential, the critical areal cation vacancy concentration, ξ , resulting in passivity breakdown, is 8.6 × 10 13 No.cm −2 for 300 M and 2.4 × 10 13 No.cm −2 for S280. These values are structurally in close agreement with the calculated results, considering the vacancy condensation is either on the cation sublattice of the barrier layer or on the steels lattice. [ABSTRACT FROM AUTHOR]

Graphene, as a passivation layer, can be used to protect the black phosphorus (BP) from the chemical reaction with surrounding oxygen and water. However, BP and graphene heterostructures have low efficiency of heat dissipation due to its intrinsic high thermal resistance at the interfaces. The accumulated energy from Joule heat has to be removed efficiently to avoid the malfunction of the devices. Therefore, it is of significance to investigate the interfacial thermal dissipation properties and manipulate the properties by interfacial engineering on demand. In this work, the interfacial thermal conductance between few-layer BP and graphene is studied extensively using molecular dynamics simulations. Two important parameters, Pcr, the critical heat power density of maintaining thermal stability, and Pmax, the maximum heat power density with which the system can be loaded, are identified. Our results show that interfacial thermal conductance can be effectively tuned in a wide range by external strains and interfacial defects. The compressive strain can enhance the interfacial thermal conductance by one order of magnitude, while interface defects give a two-fold increase. These findings could provide guidelines in heat dissipation and interfacial engineering for thermal conductance manipulation of BP-graphene heterostructure-based devices. [ABSTRACT FROM AUTHOR]

The current work aims at studying passive and electrochemical behavior of tantalum in KOH solutions of varied concentrations ranging from 0.01 to 1 M using various electrochemical methods. Electrochemical impedance spectroscopy (EIS) results show that the passive film formed on tantalum loses its protectiveness upon addition of KOH concentration. Indeed, the passivity undergoes a drastic change moving toward higher KOH concentrations. The semiconductive behavior of the passive films formed on tantalum is also investigated by employing Mott–Schottky analysis in conjunction with point defect model (PDM). Although semiconducting behavior remains the same as n-type, KOH concentration greatly affects the levels of donor densities. Moreover, Mott–Schottky analysis showed that flat band potential is quite sensitive to KOH concentration. [ABSTRACT FROM AUTHOR]

In this paper we continue the exploration started in the joint paper Brockett and Willems (1978) with a view toward the further development of models for characterizing the limits on energy flow in mixed thermal–mechanical systems. We put the thermodynamic concept of exergy 1 1 The term exergy was coined by Zoran Rant in the 1950s. We choose to use it here instead of one of the other possible names such as available work, available energy, utilizable energy, etc. because it has a single precise meaning. Willems uses the term available energy in his major work on dissipative systems (Willems1972a, 1972b) but in a generic way. (available energy) in system theoretic terms and discuss its use as a storage function in the context of input–output models. In important cases the reachable sets for the systems considered here are not closed and of course this complicates any discussion of optimality. Only through the consideration of the closure of the reachable sets can the connection between optimal trajectories of dynamical systems and the basic results of classical thermodynamics be made tight. [ABSTRACT FROM AUTHOR]

Iron and its alloys acquire stability because of the phenomenon of passivity. Though several theories, models and experimental works on passivity have been published in the literature, the mechanisms underlying the stability of the passive oxide over the metals remain still a mystery. This review presents recent developments on theoretical and experimental results besides the literature available in other reviews and critically review selected experimental results on iron/electrolyte system and theoretical developments in general and specific to iron by invoking high field model, modified high field model, point defect model (PDM), variants of PDM (VPDM), diffusion Poisson coupled model (DPCM), density functional theory based atomistic model. The experimental and model-predicted dependencies on applied voltage, pH, chloride and temperature are also presented and discussed. [ABSTRACT FROM AUTHOR]

Time-of-flight secondary ion mass spectroscopy (ToF SIMS) analysis was performed on 316L stainless steel polarized potentiodynamically up to different potentials in NaCl solution. The surface film thickness increased with the ending potential of the potentiodynamic polarization, when estimated by the oxygen ion depth profiles. The chloride ion intensities at the film/metal interface were correlated with the ending potentials during the potentiodynamic polarization and cumulative anodic charge densities that govern the pit initiation. The results and analysis support the passivity breakdown mechanisms considering the role of chloride ions at the metal/film interface, rather than at the film/solution interface. [ABSTRACT FROM AUTHOR]

This paper provides an analysis of the benefits of passive cooling for High Concentrator Photovoltaic (HCPV) systems in terms of costs and kWh annual energy yields. For the first time, the performance of the heat sinks has been related to the calculated energy yield of a standard triple-junction GaInP/GaAs/Ge HCPV cell in a system deployed at several suitable locations across the globe. Copper and aluminium heat sinks have been considered and their merits have been compared. The finite element analysis software package COMSOL was employed to gain insights regarding a simple flat plate heat sink. The cell temperature was found to have a linear dependence on the geometric concentration with a characteristic slope that increases with cell size (ranging from 10 to 0.25 mm). The results show the advantages of miniaturisation, and that the cooling of smaller cells can be accomplished using flat heat sinks. Within the considered range of geometric concentration ratios (up to 1000×), aluminium heat sinks are, in general, found to be preferred over copper, because of their lower densities and costs for the same thermal management. Closed-form thermal models based on the Least-Material (LM) approach have been utilised to design more complex finned heat sinks (operated under natural convection) that yield the best compromise between thermal performance and weight. For a 60 °C cell operating temperature, a greater kWh output is obtained, but an LM heat sink designed for a cell temperature of 80 °C has a material cost per unit energy that is between 50% and 70% less than the one designed for 60 °C. Heat sink costs between $0.1 and 0.9 per W p were estimated for a geometric concentration above 500 suns, depending on the cell׳s temperature and size. There are strong reductions in HCPV installation costs by limiting the dimensions of the cooling system at high concentrations. [ABSTRACT FROM AUTHOR]

The electronic properties of the passive film formed on pure chromium in an acidic sulfate medium at 30 °C was studied by using the multi-frequency Mott–Schottky approach and the point defect model. Conversely to common Mott–Schottky experiments, the relevance of the multi-frequency Mott–Schottky analysis relies on the determination of the space charge capacitance from a large frequency range impedance diagram. To analyze the Constant-Phase-Element behavior commonly observed for the impedance diagrams which characterize the passive film, the power-law model was used and allowed to determine the space charge capacitance. The consistency of the results showed that it was relevant to combine the power-law model to the predictive point defect model. The aim of this study is to extract the semi-conductive parameters of a passive film from impedance measurements using a sensitive analytical method. [ABSTRACT FROM AUTHOR]

The effect of grain refinement on the corrosion resistance of the passive film formed on 2099 Al–Li alloy was investigated. The microscopic structures of cold rolled 2099 Al–Li aluminum alloy were characterized by Transmittance Electron Microscopy and surface activity was analysed by electron work function. The corrosion resistance of the passive film was studied by electrochemical techniques and Raman spectra. It was found that nano/ultrafine grained 2099 Al–Li alloy with refined precipitation phases was obtained by several plastic deformation process. The corrosion resistance of the 2099 Al–Li aluminum alloy was improved by grain refinement and refined precipitation phases. The improved corrosion resistance of 2099 Al–Li alloy after grain refinement was attributed to decreased electron work function. The grain refinement promoted the forming of thicker passive film and decreased acceptor concentration in passive film. [ABSTRACT FROM AUTHOR]

This study explored the possibility of forming a “stainless” Mg–Ti alloy. The electrochemical behavior of magnetron-sputtered Mg–Ti alloys was measured in a NaCl solution, and the surface films on the alloys were examined by XPS, SEM and TEM. Increased corrosion resistance was observed with increased Ti content in the sputtered Mg–Ti alloys, but passive-like behavior was not reached until the Ti level (atomic %) was higher than the Mg level. The surface film that formed on sputtered Mg–Ti based alloys in NaCl solution was thick, discontinuous and non-protective, whereas a thin, continuous and protective Mg and Ti oxide film was formed on a sputtered Ti–Mg based alloy. [ABSTRACT FROM AUTHOR]

A method is presented to test the persistence of inhibition of corrosion of copper in previously inhibited tap water. Cyclic voltammetry (CV) sweeps on copper were carried out in tap water both in the presence and in the absence of inhibitor to examine the state of passivity and of breakdown leading to localised corrosion of the metal in tap water in order to investigate the persistence of inhibitor. The results show that after prior inhibition and re-immersion in inhibitor-free tap water, inhibition is still observed and persists through several further potential cycles. These novel observations describe the persistence of the inhibitor on the surface after the supply of the inhibitor has been removed. [ABSTRACT FROM AUTHOR]

This article reviews recent research on the collective dynamical behavior of colloids with dipolar or multipolar interactions. Indeed, whereas equilibrium structures and static self-assembly of such systems are now rather well understood, the past years have seen an explosion of interest in understanding dynamicals aspects, from the relaxation dynamics of strongly correlated dipolar networks over systems driven by time-dependent, electric, or magnetic fields, to pattern formation and dynamical control of active, self-propelled systems. Unraveling the underlying mechanisms is crucial for a deeper understanding of self-assembly in and out of equilibrium and the use of such particles as functional devices. At the same time, the complex dynamics of dipolar colloids poses challenging physical questions and puts forward their role as model systems for nonlinear behavior in condensed matter physics. Here we attempt to give an overview of these developments, with an emphasis on theoretical and simulation studies. [ABSTRACT FROM AUTHOR]

In this contribution, stability and passivity properties of a class of thermodynamic processes are addressed from a thermodynamical point of view. These thermodynamic processes can be constituted by multiple spatially homogeneous dynamic subsystems modeled by ordinary differential equations. It is shown that the internal entropy production may be used as a Lyapunov function candidate to prove the isolated system stability properties and as a storage function to assess the passivity properties when the system interacts with the surroundings. In addition, it is shown that the stability condition depends on a matrix whose dimension is equal to the number of modeled dynamical phenomena taking place within the system, i.e. the number of phenomena can be smaller than the system dimension. Moreover, a port-controlled Hamiltonian representation of this class of systems based on the internal entropy production is developed. Finally, the theory proposed is applied to three study cases: a heat exchanger, a ideal gas adiabatic chemical reactor and a ideal gas jacketed chemical reactor. [ABSTRACT FROM AUTHOR]

Sulfur-induced degradation of the passive film on Alloy 800 in a simulated alkaline crevice (ACC) environment at 21–300 °C was evaluated using polarization curve, secondary ion mass spectrometry (SIMS) and Auger electron spectroscopy (AES). Experimental results indicated that sulfur has no noticeable detrimental effect on film properties at 21 °C and 90 °C, which is due to the formation of a negatively charged layer. However, sulfur has remarkable detrimental impact at 150 °C and 300 °C, which is attributed to the electrochemical reduction of the sulfur in thiosulphate and the subsequent incorporation of sulfur ions into the passive film. [ABSTRACT FROM AUTHOR]

The effects of Ca 2+ and Mg 2+ on passivity of UNS N08800 alloy at 300 °C are experimentally investigated in simulated crevice chemistries. In the Pb-free solutions, the impacts of Ca 2+ and/or Mg 2+ are similarly detrimental, but less in extent, as those caused by Pb-contamination, as indicated by the increased passive current density, the lower breakdown potential, the promoted incorporation of hydrogen into the passive films and the formation of the films with highly defective structures containing more M OH bonds. However, when Ca 2+ and/or Mg 2+ are/is concurrently present with Pb cation, they mitigate the detrimental impact of lead on the passivity. [ABSTRACT FROM AUTHOR]

A phenomenological model is postulated to interpret the interactive impacts of dissolved Pb contamination, Ca 2+ and Mg 2+ on passivity of Alloy 800 in simulated crevice chemistries at 300 °C. Passivity degradation is characterized by the retarded dehydration during passivation and increased donor density in passive film. Ca 2+ and Mg 2+ can cause the passivity degradation in the Pb-free chemistries but, if the Pb-contamination concentration exceeds a critical value, would reduce the detrimental effect of Pb-contamination. This behavior may be related to the extremely strong adsorption capacity of Pb contamination. Finally, the applications in the water management strategy of nuclear power plants are discussed. [ABSTRACT FROM AUTHOR]

The characteristics of a synchronized pulse plasma using 60 MHz radio frequency as a source power and 2 MHz radio frequency as a bias power were investigated for the etching of SiO 2 masked with an amorphous carbon layer (ACL) in a C 4 F 8 /Ar/O 2 gas mixture. Especially, the effects of the pulse phase lag of the synchronized dual-frequency pulsing between source power and bias power on the characteristics of the plasma and SiO 2 etching were investigated. The results showed that the etch rates of SiO 2 was the highest and the etch profile was the most anisotropic when the pulse phase lag between the source power and bias power was 0° in the synchronized pulse plasma. Increasing the phase lag to 180° decreased the etch rates and degraded the etch anisotropy. The change in etch characteristics as a function of pulse phase lag was believed to be related to the difference in gas dissociation and fluorocarbon passivation caused by the variations in electron temperatures during the source pulse off-time. [ABSTRACT FROM AUTHOR]

A multilayered metallic structure, consisting of Cu foil and subsequently deposited Ag thin film covered with a passivation layer, was proposed to fabricate Ag micro/nanoparticles by stress migration. With employing a ductile Pt or brittle TiN thin film as passivation, Ag micro/nanoparticles were successfully fabricated by annealing the corresponding multilayered structure. The relationship between characteristics (average diameter, number and volume) of the formed Ag micro/nanoparticles and the annealing temperature was discussed. On this basis, the growth mechanism was developed, which indicates that the dimension of Ag particles was mainly dominated by the different pathways for the migration of diffused Ag atoms in the passivation layers of Pt and TiN and the annealing temperature. [ABSTRACT FROM AUTHOR]

The inhibitory effect of octadecylamine (ODA) on the corrosion and passivity breakdown of Type 316SS in acetic acid solution was characterized using potentiodynamic polarization, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The inhibition mechanism of ODA was defined by optimizing the Bi-layer Point Defect Model on the EIS data. The optimization results indicated that, as either the concentration of ODA or the immersion time increases, the inhibitor-modified outer layer resistance, the charge transfer resistance, and the Warburg coefficient for the transport of species through the porous outer layer of the passive film all increase, thereby accounting for the observed inhibition. [ABSTRACT FROM AUTHOR]

The electrochemical behavior and compositions of passive films formed on the constituent phases (α-phase, γ-phase) of 2205 duplex stainless steel (DSS) without coupling in neutral 3.5% NaCl solution were investigated, utilizing single-phase samples prepared by selective dissolution. The results demonstrate that, compared to γ-phase, Fe species in passive film of α-phase are more stable due to the higher content of Mo within α-phase. The superior stability of Cr (III) species in the passive layer of γ-phase may result from the higher content of Ni in γ-phase, which leads to the higher content of Cr, Cr/Fe ratio, and better passivity of passive layer. The beneficial effect of coupling of two phases on the passive behavior of 2205 DSS is also found. [ABSTRACT FROM AUTHOR]

To advance existing in vitro cell impedance spectroscopy and improve reliability of impedimetric sensors for cell analysis, we have electrically insulated interdigitated microelectrodes using the high- k biomaterial zirconium dioxide (ZrO 2 ). We report the smallest passivation thickness to electrode distance ratio of 10 −3 using atomic layer deposition resulting in electrically insulated metal oxide films of 15 nm thickness. For the first time the influence of the insulation on sensor performance is experimentally and theoretically analyzed using numerical simulations. In addition an equivalent electrical circuit model was established and validated using non-linear least square fitting. Results of the computational simulations revealed improved electrical current distribution across the electrically insulated interdigitated electrode structures in comparison to open (not passivated) electrodes. Furthermore, we found linear decrease of current density in z -direction within 5 μm distance from the sensor surface in the presence of ZrO 2 nanocoatings is ideally suited to assess confluent cell layers. Final practical application of the ZrO 2 nanolayer passivated impedimetric sensors is demonstrated for nanotoxicological investigations, where sensitivity and repeatability are crucial parameters for cell analysis. Results of our study show that the reproducible and standardizable deposition of a uniform metal oxide nanocoating improves current density distributions, has no performance drawbacks compared to open sensors and enables sensitive detection of protein-coating effects on cytotoxic silica nanoparticles. The presented novel sensor design allows for the integration of alternative electrode materials such as aluminum enabling cost-effective fabrication of large-volume sensor arrays. [ABSTRACT FROM AUTHOR]

The comparative breakdown of passivity of tin by fluorides and chlorides highlight the significant slower kinetics of attack by the kosmotrope fluoride when compared to the chaotrope chloride at pH 5.7 and 10. The origin of this difference is ascribed to the predominant halide-dependent mechanism of attack, pitting with chlorides and film thinning with fluorides, which is conditioned according to the anion-specific hydration properties. [ABSTRACT FROM AUTHOR]

In this contribution, the stability and passivity properties of a class of chemical reactors are addressed from a thermodynamical point of view. For this purpose, a thermodynamical consistent model is derived from a generic gas reactor model whose rate is based on the reaction progress at the mesoscopic scale. It is shown that the internal entropy production may be used as a candidate Lyapunov function to prove the isolated system stability properties and as a storage function to emphasize the passivity properties when the chemical reactor interacts with the surroundings. [ABSTRACT FROM AUTHOR]

The adhesion properties of a FeCrVN experimental tool alloy immersed in pure water and sodium chloride solution have been studied by Quantitative Nanomechanical Property Mapping to understand the influence of microstructure on corrosion initiation of this alloy. The approach used here allows early observation and identification of pre-pitting events that may lead to passivity breakdown of the alloy. Adhesion provides a good distinction between the different regions and we ascribe this to their vanadium and nitrogen contents. Finally, the prepitting is characterized by generation of small particles in specific regions of the surface with low chromium content. [ABSTRACT FROM AUTHOR]

Multi-element dissolution analysis of amorphous Fe 50 Cr 15 Mo 14 C 15 B 6 in 0.1 M H 2 SO 4 was investigated electrochemically and by coupled online mass spectrometry. We fully discuss the most important aspects of the application of the newly-developed methodology to study complex multi-elemental alloys. The resulting partial dissolution rates of Fe, Cr and Mo reflect the passive behavior and are compared to the measured total current density as function of time. The deviations between the added elemental dissolution currents and the measured total current density are discussed. Furthermore, the inferred growth of oxide thickness was correlated to results obtained from surface analysis. [ABSTRACT FROM AUTHOR]

Passivity breakdown and pitting on pure copper, the assumed material for the outer canisters for the isolation of high-level nuclear waste in Sweden and Finland, has been studied in simulated, sulfide- and chloride-containing granitic rock groundwater and the data are interpreted in terms of the Point Defect Model (PDM). The near normal distribution in the critical breakdown potential ( V c ) measured in deaerated sodium sulfide solutions with different chloride concentrations and for variable pH (= 8-10) is in satisfactory agreement with the quantitative prediction of the PDM. The critical areal concentration of condensed cation vacancies at the metal/film interface that leads to passivity breakdown, as predicted by the PDM from the experimental dependence of the V c on the square root of the voltage sweep rate, ξ < 1.09 × 10 15 cm −2 , is in excellent agreement with that calculated from the unit cell dimensions of the substrate Cu ( ξ ≈ 1.53 × 10 15 cm −2 ) and the barrier layer sulfide (Cu 2 S) ( ξ ≈ 7.66 × 10 14 cm −2 ) for vacancy condensation upon the metal lattice or upon the cation sublattice of the film, respectively. This observation provides convincing evidence for the validity of the PDM for modeling passivity breakdown on Cu sulfide- and chloride-containing granitic rock groundwater. [ABSTRACT FROM AUTHOR]

Highlights: [•] Phosphate from industrial phosphoric acid stabilized passive film of stainless steel. [•] A less protective polyphosphate film is formed at higher temperature. [•] Passive film thickness is obtained by the power law model from EIS measurements. [•] Passive film of Sanicro28 becomes more resistive toward corrosion with exposure time. [•] Resistance toward corrosion decreases with temperature without formation of pits. [ABSTRACT FROM AUTHOR]

Highlights: [•] Passivity of Al–Ni–Y metallic glasses increase due to annealing at 150°C, 5min. [•] Synchrotron XRD or NMR do not reveal any changes in structure/ordering in glasses. [•] The surface segregation of Y is proposed for the improved passivity of the glasses. [ABSTRACT FROM AUTHOR]

Highlights: [•] A stiff solution dynamics model to study local chemistry near a corroding metal. [•] Time evolution of concentrations of metal ions, hydroxyl complexes, H+ and OH− ions. [•] Time of onset of passivity for Fe and Zn presented for 3 experimental conditions. [•] On Zn passivity sets in at much shorter time scales compared to Fe. [•] Good physical insight gained into corrosion and passivity of metals. [ABSTRACT FROM AUTHOR]

Highlights: [•] We propose a concept of Mg protection by alloys with resistant metals. [•] High passivity of Mg–Al–Zn–Cr alloys is achieved when Cr concentration is over 30%. [•] Effective protection of AZ31 is achieved by annealed multilayer Mg–Cr structures. [ABSTRACT FROM AUTHOR]

Highlights: [•] The metastable pitting potential E m is defined according to the testing conditions. [•] For four materials tested, linear relationship exists between E m and E b values. [•] As chloride concentration changes, the E m and E b values change in the same order. [•] The metal passivity determines the nucleation of both metastable and stable pitting. [•] The E m value can be taken as a parameter characterizing pitting tendency of metals. [ABSTRACT FROM AUTHOR]

Highlights: [•] Tensile stress is generated by the passive film during α-Ti corrosion in methanol solution. [•] Water reduces film-induced stress and passive film breaking load in methanol. [•] Water reduces α-Ti SCC susceptibility in methanol solution. [•] The easier passive film can be broken, the more likely SCC would happen. [•] Film residual stress is reasonably estimated. [Copyright &y& Elsevier]

Abstract: This paper reports thiosulfate-enhanced effect of chloride ions on the passivity degradation of Alloy 800 and discusses how thiosulfate influences the semiconductor properties as well as breakdown of the passive films. Experimental results reveal that in concentrations of 10−6 to 0.075mol/L, thiosulfate lowers the breakdown potential of Alloy 800 by 100–400mV in solutions containing 0.6mol/L chloride ions. This degradation is further verified by polarization resistance and noise resistance obtained from electrochemical impedance spectroscopy (EIS) and micro-nanoscale electrochemical noise (EN) data, respectively. Mott–Schottky analysis is employed to explore the corrosion mechanism and the results show that the passive film exhibits as p-type semiconductivity in a thiosulfate-only solution and n-type semiconductivity in a chloride-only solution, and the addition of thiosulfate into chloride solutions increases the concentration of oxygen vacancies in the passive film at the potential close to the pitting potential. Thiosulfate cannot be easily reduced on well-passivated surfaces in chloride-free solutions but can be readily reduced to sulfide in chloride solutions at active sites when the passive film breaks down – the reduced sulfur retards the healing process of repassivation, leading to an increase in oxygen vacancies. [Copyright &y& Elsevier]

Highlights: [•] UFG steel with a ferrite grain size of 200nm is processed with 16 passes of ECAP. [•] The Fe3C particles are dispersed in ferrite matrix of the UFG steel. [•] It corrupts relatively rapidly, but shows better anodic passivity properties in acid. [ABSTRACT FROM AUTHOR]

Abstract: The InN/GaN heterostructure with high sheet electron concentration was utilized to fabricate the ion-selective field-effect-transistor (ISFET) pH sensors. To improve the sensing performances of the InN/GaN-heterostructured ISFET pH sensors, the PEC passivation treatment was applied to reduce the surface states resided on the sensing membrane and to suppress the Fermi level pining effect. Consequently, the passivated InN/GaN-heterostructured pH sensors exhibited a linear pH response with a sensing sensitivity of 52.04mV/pH, while the unpassivated one showed a nonlinear behavior, especially in low pH (<7) region, with an average sensitivity of 34.75mV/pH. The improvement of the sensing response in acid solution was attributed to the decrease of the surface states density on the sensing membrane by the PEC passivation function. Furthermore, it was demonstrated that the experimental data can be well described by the site-binding model. Based on the model, the sensing parameters were derived. The resulting sensitivity parameter value for the passivated sensor was 1.18, obviously larger than the value 0.37 for the unpassivated one. The selectivity coefficients of the passivated InN/GaN-heterostructured pH sensors for interfering ions of sodium and potassium are −7.62 and −7.901, respectively. [Copyright &y& Elsevier]

Abstract: A thin, flexible monocrystalline germanium (c-Ge) heterojunction solar cell has been developed based on a novel kerfless exfoliation process and remote plasma-enhanced chemical vapor deposition (RPCVD) of hydrogenated amorphous silicon (a-Si:H). The performance of the exfoliated 50μm thick and bulk 500μm Ge heterojunction cells is compared in this paper. A superior conversion efficiency of 5.28% was achieved with the 50μm exfoliated Ge cell versus 1.78% for the bulk Ge cell, in agreement with simulation results. A record fill factor of 58.1% for an a-Si:H/c-Ge heterojunction cell was obtained with the exfoliated cell. Moreover, the conversion efficiency achieved with the 50μm exfoliated cell (without intrinsic a-Si:H passivation) is comparable to the best reported in literature with bulk Ge heterojunction cells and intrinsic a-S:H passivation. [Copyright &y& Elsevier]

Abstract: The objective of this work is to study the effect of Mo additions on film passive properties of three different stainless steels (SS) types (austenitic, ferritic and duplex alloys). A comparison between Mo containing (3wt% Mo) and free Mo (0wt% Mo) grades of highly controlled laboratory heats was done considering their passive film formed in different aggressive conditions, from neutral to alkaline pH. The presence of oxidized Mo on the passive layer was confirmed by X-ray photoelectron Spectroscopy (XPS). The presence of Mo within the passive film improved the passivity breakdown potential for the duplex and ferritic SS, but seemed to have no effect for austenitic SS. [Copyright &y& Elsevier]

Abstract: The discrete depth characteristics of thin passive oxide films were investigated using high-resolution electron microprobe and nanoscale secondary ion mass spectrometry (NanoSIMS). A novel NanoSIMS method involving a Cs layer deposition before Cs+ sputtering was employed for the first time to determine the elemental distribution at different sub-layers of a passive film. The film was formed in air on the surface of a multi-phase microstructure of high-chromium cast iron (HCCI). It was found that the film composition and thickness varied according to the underlying microstructure phase. Based on the microprobe and NanoSIMS results, the influence of the HCCI passive film thickness and composition on the localized passivity breakdown has been proposed. [Copyright &y& Elsevier]

Abstract: The corrosion resistances and passivation of austenitic 316L and duplex 2205 powder metallurgical (P/M) steels, produced by gas atomizing and hot isostatic pressing (HIP), have been compared with those of their conventional cast counterparts. P/M 316L steel is shown to have significantly higher pitting corrosion resistance than conventional 316L steel in 0.5M HCl. This effect is ascribed to the fine grained microstructure of the P/M 316L steel yielding an improved passive layer. The latter hypothesis is supported by photoelectron spectroscopy data demonstrating differences between the thickness and composition of the passive layers for the 316L steels. [Copyright &y& Elsevier]

Abstract: The effect of oxygen and biofilms on crevice corrosion of UNS S31803 and UNS N08825 in seawater was studied. Passivity breakdown occurred through crevice corrosion in UNS N08825 and through transpassive dissolution in UNS S31803 although both alloys displayed crevice corrosion under potentiodynamic conditions. The most severe crevice corrosion occurred in the absence of oxygen and the presence of a biofilm. Microbial adhesion as investigated by fluorescence microscopy occurred mainly outside the crevice and DNA sequencing revealed a shift in biofilm composition as a function of substratum surface and oxygen pressure. [Copyright &y& Elsevier]

Abstract: In this paper, a thermodynamically stable evolution criterion for homogeneous multi-component mixtures with chemical transformation is proposed. The approach is motivated and governed by physical considerations strongly related to the second law of the thermodynamics. More precisely we show that there exists some potential function directly defined on the space of the extensive and/or intensive variables for any transformation, and that meets the evolution criterion without any restriction on the chemical reaction kinetics. As a consequence the irreversibility degree or passivity of the mixture under mass transfer and transport phenomena is explicitly expressed. Some numerical simulations for a homogeneous binary mixture with chemical reaction under multiplicity are given to validate our theoretical developments. [Copyright &y& Elsevier]