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The interfacial behaviors between protective coatings and substrate single-crystal superalloys significantly impact their service performances. This work focuses on the elements interdiffusion and microstructural evolution at the interface between a NiCrAlY coating and a series of high-Mo Ni3Al-based single-crystal superalloys, through the coupled phase-field simulations and DICTRA kinetics calculations of their model systems. The critical roles of Al and Cr played in the microstructural evolution at coating/superalloy interface have been confirmed, which requires the appropriate content decreases of Al and Cr in the coating at 1100 °C. However, the addition of Mo reduces the driving force of element diffusion from coating to substrate by increasing the activities of Al and Cr in superalloy. Moreover, increasing the Mo content in superalloy from 8 wt% to 10 wt% could also counteract the promoting effect of Al on Ni mobility and mitigate the γ′ coarsening and detrimental TCP precipitation. Therefore, the effects of Mo enable the reasonable increase of Al content in coating to better balance the interfacial stability and oxidation resistance of coated superalloy, besides its advantage in reducing the anisotropy of TCP precipitate. The obtained interfacial evolution mechanisms resulting from the phase transformation thermodynamics and element interdiffusion kinetics are expected to aid the coating design for advanced single-crystal superalloys servicing at ultra-high temperature.

The hot corrosion and high temperature oxidation performance of the TiBw/TA15 composite were tested at 1073 K for up to 100 h. The final mass gain caused by the high temperature oxidation was only 16.9% of that caused by the hot corrosion, showing that the effect of hot corrosion is much larger than that of oxidation. After 100 h of high temperature oxidation testing, an approximately 50 μm-thick oxide scale formed on the substrate surface, consisting of mixed TiO2 and Al2O3 oxide. An approximately about 300 μm-thick hot corrosion scale, mainly composed of TiO2 and Al2O3 with holes and cracks, was generated after 100 h of hot corrosion testing. The change of acidity/basicity in the molten salt caused by the self-circulating sulfurization/chlorination–oxidation cycle and basic dissolution was the mean reasons for hot corrosion. [ABSTRACT FROM AUTHOR]

Based on the principles of mass conservation, chemical equilibrium, and electron charge neutrality, a thermodynamic equilibrium system was established for the nickel-cobalt-manganese sulfate leaching solution in the recovery process of spent lithium-ion batteries. By changing the ion concentration in the system, calculating the pH value, and identifying the complexes of Cu2+, Fe3+, PO43−, Al3+, and F− in the system, the results were obtained and used to draw the thermodynamic diagram. The solution thermodynamic calculation and experiment were combined to purify the nickel-cobalt-manganese-rich leachate. The results show that the main Cu2+, Fe3+, PO43−, Al3+, and F− impurity ions could all be reduced to less than 10 ppm under the optimized process parameters. [ABSTRACT FROM AUTHOR]

With an aim to use ammonia as a direct fuel in gas turbines, an investigation on the degradation of materials used in the turbine components in the ammonia flow environment is important. The present work investigated the surface reaction and degradation of Inconel 600 placed at different positions inside a furnace in the direction of ammonia flow at 400 °C to 600 °C. Severe surface damage and degradation was identified. The effect of specimen position on the extent of degradation and the damage mechanisms were elucidated utilizing XRD, TEM, and Optical Emission Spectroscopy (OES). [Display omitted] • Inconel 600 was exposed to an ammonia gas-flow environment to study the material degradation. • Position-dependent surface degradation was observed with a greater extent of damage at the upstream side. • Position-dependent degradation was explained based on thermodynamic and numerical modeling. • The degree of surface cracking is the highest at 500 °C. • Different damage mechanisms of the material under ammonia environment were elucidated. [ABSTRACT FROM AUTHOR]

Based on the principles of mass conservation, chemical equilibrium, and electron charge neutrality, a thermodynamic equilibrium system was established for the nickel-cobalt-manganese sulfate leaching solution in the recovery process of spent lithium-ion batteries. By changing the ion concentration in the system, calculating the pH value, and identifying the complexes of Cu2+, Fe3+, PO43−, Al3+, and F− in the system, the results were obtained and used to draw the thermodynamic diagram. The solution thermodynamic calculation and experiment were combined to purify the nickel-cobalt-manganese-rich leachate. The results show that the main Cu2+, Fe3+, PO43−, Al3+, and F− impurity ions could all be reduced to less than 10 ppm under the optimized process parameters.

The impact of inclusion types on pitting corrosion behavior of high-nitrogen stainless bearing steels (HNSBSs) with different Ce contents was investigated combining electrochemical tests, microstructure characterization and thermodynamic analysis. The oxide (Al 2 O 3 /Ce 2 O 3) and sulfide (MnS/Ce 2 O 2 S) inclusions exhibited induction effect on pitting corrosion, while nitride (CeN) inclusion exhibited inhibition effect. Interestingly, CeN inclusion also acted as a protective armor wrapping around Ce 2 O 3 inclusion, alleviating its adverse effect. Moreover, the mechanism of inclusion evolution with Ce content was clarified, and the optimum Ce content in HNSBS was obtained (0.020 wt%). This work provides theoretical guidance for improving corrosion resistance of high-nitrogen steels. [Display omitted] • Cerium treatment improved the corrosion resistance of HNSBSs. • The optimum Ce content in HNSBS was approximately 0.020 wt%. • The oxide and sulfide inclusions exhibited induction effect on pitting corrosion. • The nitride (CeN) inclusion exhibited inhibition effect on pitting corrosion. • CeN inclusion acted as a protective armor wrapping around Ce 2 O 3 inclusion. [ABSTRACT FROM AUTHOR]

Inhibition of CO 2 corrosion of mild steel in 0.5 M NaCl under atmospheric pressure at 40 °C as well as high pressure (10 bar) at 120 °C by 2-[2-methyl-4(or 5)-alkylisoxazolidin-5(or 4)-yl)methyl]succinic acids, a new class of molecules having inhibitive motifs of succinic acid, isoxazolidine and hydrophobic alkyl chain assembled in a single entity, has been examined by gravimetric and electrochemical methods. Inhibitor molecule containing CH 3 (CH 2) 8 outperformed its counterpart with a shorter hydrophobe CH 3 (CH 2) 4 and two other commercial imidazoline-based inhibitors. The effectiveness of these new inhibitors was also evaluated by electrochemical impedance spectroscopy. The inhibition efficiency by EIS was found to be 75%, 91% and 98% in the presence of 1, 5 and 20 ppm, respectively, at 40 °C. The potentiodynamic polarization studies indicated that the new inhibitors act as anodic inhibitors. The adsorption of the synthesized inhibitors follows Temkin adsorption isotherm model with favorable high values of –Δ G ° ads and −Δ H ° ads pointing the inhibitors adsorbed on the metal surface by chemisorption process. The XPS study confirmed the adsorption of the inhibitors on the metal surface. [ABSTRACT FROM AUTHOR]

• Excessively high density of sub-grain boundaries accelerates the corrosion rate of ODS-FeCrAl. • Appropriate density of sub- grain boundaries promotes the formation of Cr and Al-rich spinel and Al 2 O 3. • The intergranular precipitation of W and Ti promotes the formation of Cr and Al-rich oxides. • The precipitation of Zr is conducive to the enrichment of Cr. Long-term corrosion behavior of ODS-FeCrAl tube was investigated in oxygen-saturated static liquid lead-bismuth eutectic (LBE) at 550 °C. Different densities of sub-grain boundaries (sub-GBs) lead to different corrosion behaviors on the inside and outside surfaces of the tube. The oxide film formed on the inside surface consists of Fe 3 O 4 , Fe-Cr-Al spinel and Al 2 O 3 , and on the outside surface consists of Fe-Cr-Al spinel rich in Cr&Al and Al 2 O 3. Excessively high density of sub-GBs accelerates the oxidation rate. The precipitation of W&Ti promotes the formation of Cr-rich and Al-rich oxides. The corrosion mechanism of ODS-FeCrAl in liquid LBE is discussed. [ABSTRACT FROM AUTHOR]

A simple example of an isothermal thermodynamic phase diagram for a quaternary system composed of a ternary A–B–C alloy reacting with a single oxidant (O) has been calculated assuming that oxides are insoluble and that they do not interact with each other. The 2D thermodynamic diagrams of the ternary metal–oxygen systems composed of the three types of binary alloys plus the oxidant are reviewed first, and then the 2D sections of the 3D phase diagram along planes of constant values of one of the variables involved are explored in detail. Finally, the structure of the 3D diagram is presented by means of appropriate figures and is discussed by examining in detail the connections between the critical curves, surfaces and volumes in 3D space with the corresponding critical features, including points, curves and surfaces, of the 2D sections. In addition, the possible application of thermodynamic diagrams to predict the nature of the oxidation products is briefly discussed in combination with the concept of oxidation maps. [ABSTRACT FROM AUTHOR]

The carburization behavior of bare and pre-oxidized APMT has been assessed after long-term graphite exposure at 1000 °C. Bare coupons formed a thick scale after graphite exposure due to carbon interaction and chromium-rich carbides were detected, as predicted from thermodynamic calculations. Pre-oxidation of APMT was conducted in air, and oxidation kinetics were measured through thermogravimetry. The oxide layer formed at 800 °C failed to prevent carburization. However, increasing the pre-oxidation temperature to 1200 °C produced an oxide layer with good resistance to carbon diffusion indicating that the alpha-alumina formed at high temperatures is key in preventing carburization of the material. [Display omitted] • Carbide formation (Cr 23 C 6) increased with exposure time on bare APMT samples. • CALPHAD calculations confirmed the carbide formation in FeCrAl. • Pre-oxidation of APMT conducted in air at 800 °C failed to prevent carburization and carbide formation occurred in the bulk. • Pre-oxidation of APMT at 1200 °C produced an oxide layer with good resistance to carbon diffusion, thus protecting the sample from carburization. [ABSTRACT FROM AUTHOR]

The effect of Fe on the oxidation, sulfidation and carburization behaviors of alloys in CO 2 containing SO 2 at 1000 ℃ was investigated using multiple evaluation methods, including first-principles, molecular dynamics simulation, high-temperature corrosion experiment and thermodynamic analysis. The adsorption capacity of both gas molecules on FeCr alloy surface was stronger than that on NiCr alloy surface. The molar content of O, C and S atoms in Fe-25Ni-22Cr alloy was higher than that in Ni-25Fe-22Cr alloy. The increase of Fe content promoted the reactions between alloy elements and O, C, S atoms, which caused serious corrosion of Fe-Ni-Cr alloys. • The effect of Fe on the oxidation, sulfidation and carburization behaviors of alloys in CO 2 with SO 2 at 1000 ℃ was studied. • The adsorption capacity of CO 2 and SO 2 molecules on FeCr alloy surface was stronger than that on NiCr alloy surface. • The molar content of O, C and S atoms in Fe-25Ni-22Cr alloy was higher than that in Ni-25Fe-22Cr alloy. • The increase of Fe content caused serious corrosion of Fe-Ni-Cr alloys. • The accuracy of simulation and experimental results was verified by corrosion thermodynamics. [ABSTRACT FROM AUTHOR]

Oxidation of pure Ti coated with a thin Si layer was investigated to clarify the role of titanium silicide phases in improving oxidation resistance of titanium alloys. The system initially reacted to form a two-layer structure with Ti 5 Si 3 and SiO 2 . Oxidation proceeded by upward diffusion of Ti to form TiO 2 wedge-like crystals on the surface and inward oxidation of Ti 5 Si 3 into a mixed nanocrystalline TiO 2 and SiO 2 internal scale that was locally layered. The Ti 5 Si 3 phase inhibited oxygen inward diffusion, thereby limiting oxygen ingress into Ti and retarding inward Ti oxidation until the silicide layer was completely oxidized. [ABSTRACT FROM AUTHOR]

The physicochemical properties of the Ni-Co-Fe-O system are important to the high-temperature oxidation of the Ni-Co-Fe based alloy, such as superalloys and high-alloy steels. The equilibrium phase relations between the Ni-Co-Fe alloy and its oxide at elevated temperature were systematically investigated using experimental and assessment method. The iso- p O 2 lines and iso-concentration lines of oxides in the entire range of the oxygen partial pressure and composition at 1673 K were evaluated, and the high-temperature oxidation path of the Ni-Co-Fe alloy was qualitatively examined. Using the thermodynamic findings allows to ascertain the high-temperature oxidation phenomena of the Ni-Co-Fe based alloy. [ABSTRACT FROM AUTHOR]

The effect of sulfur on the carburization of three Fe–19Ni–21Cr–xAl (x = 0, 2, 6 at.%) alloys was studied at 900 °C in three CH4–H2–H2S gases providing different sulfur pressures. For all alloys, the carbon attack decreased with an increase in the sulfur pressure, even if it was never prevented completely. However, reaction with the gas richest in H2S produced also an external chromium sulfide scale. The overall corrosion rates were slower for Fe–19Ni–21Cr–6Al than for the other two alloys under each gas mixture due to the formation of some alumina in the external scales. [ABSTRACT FROM AUTHOR]

Ceramicizable phenolic resin matrix composites are widely used in aerospace fields, and their heat resistance rating can reach 1400 °C. To further improve heat resistance, HfB 2 -SiB 6 ceramicizable phenolic resin matrix composites were prepared, and their thermal properties and oxidative corrosion behaviour were studied. The results showed that the composites with 30 % SiB 6 had a ceramic yield of 69.69 % at 1600 °C, and their linear and mass ablation rates were as low as 0.004 mm/s and 0.043 g/s, respectively. XRD and thermodynamic calculation showed that there were complex reactions to form Hf ceramics and Si-B-N-O to prevent corrosion under high temperatures of about 2000–2400 °C. • HfB 2 -SiB 6 improves the heat resistance of ceramicizable phenolic resin composites. • Composites' linear and mass ablation rates are as low as 0.004 mm/s and 0.043 g/s. • The composites with 30 % SiB 6 have 69.69 % ceramic yield after 1600 °C treatment. • Complex reactions occur to form Hf ceramics and Si-B-N-O preventing corrosion. • Composites have heat resistance at 1600 °C and ablation resistance at 2000–2400 °C. [ABSTRACT FROM AUTHOR]

In the initial atom-scale corrosion stage, the formation of chemical bonds and the distribution of atoms were obtained by the molecular dynamics. The thermodynamic and experimental results indicated the distribution of oxides and carbides formed on T92 and TP347H steels. [Display omitted] • The corrosion mechanisms of steels in HTHP CO 2 and H 2 O were investigated by molecular dynamics, thermodynamics and experiments. • The combination between Cr and O was earlier than Cr and C. • The carbonization rate of T92 steel was lower than that of oxidation rate. • The Fe 3 O 4 oxides on T92 steel were coarsened and pulverized. • The volatile CrO 2 (OH) 2 were formed on the surface of TP347H steel. The corrosion mechanisms of T92 and TP347H heat-resistance steels in high-temperature and high-pressure (HTHP) CO 2 and H 2 O environments were investigated by molecular dynamics, thermodynamics and experiments. In the initial corrosion stage, the combination ability of Cr with O and C was stronger than that of Fe with O and C, which caused oxygen and carbon absorption capacity of TP347H steel was higher than that of T92 steel. In HTHP H 2 O environment, the Fe 3 O 4 oxides on T92 steel were coarsened and pulverized, which made the Fe 3 O 4 oxides become loose. The volatile CrO 2 (OH) 2 were formed on the surface of TP347H steel, which caused the coarsening of Cr 2 O 3 oxides. [ABSTRACT FROM AUTHOR]

A systematic investigation has been performed to study the oxidation response of Mo 76 Si 14 B 10 alloy doped with traceable amount of Ce and Al at temperature in the range of 900–1300 °C. The resistance to degradation of Mo 76 Si 14 B 10 ≥ 900 °C has increased due to the dissociation of Mo-oxides into Mo in protective glassy borosilicate layer. Addition of Ce aggrieves oxidation initially, but protection is achieved upon exposure within 3 h at all the different temperatures. No passivation has occurred in Al containing alloy due to the dissolution of Al 2 O 3 in the borosilicate scale leading to the precipitation of aluminum-borate and mullite along with unreacted cristoballite. [ABSTRACT FROM AUTHOR]

This paper analyzes the microelectrogravimetric aspects of CuSCN electrochemical deposition. Samples were prepared under conditions typically used during the first preparation step of the increasingly developed inverted photovoltaic cells , i.e ., an approach based on the deposition of a hole transporting layer (p-type semiconductor) as a starting film. Here, both CuSCN seed layers and nanowires are the result of an electrodepositon process that uses electrolytes rich in Cu(II) species, thiocyanate ions and additives such as triethanolamine (TEA) or ethylenediaminetetraacetic acid (EDTA). Gold (Au) reactivity was compared to that of Indium Tin Oxide (ITO) coated quartz electrodes in the presence of aqueous thiocyanate ions. Consequently, ITO was confirmed as a suitable substrate for microelectrogravimetric purposes under conditions in which gold becomes electrochemically corroded. Both the speciation and the solubility diagrams for Cu(II) were prepared considering the presence of either TEA or EDTA as additives to establish the possible electroactive species involved in the electrochemical formation of CuSCN and its solubility as it grows. Following a potentiodynamic study and regardless of the additive used, it can be stated that CuSCN is accumulated on the electrode and is then reoxidized. The latter is accompanied by an almost complete loss of the previously accumulated mass. During the elapsed time of the experiments, two Cu(II) insoluble species, namely Cu(SCN)TEA and Cu(SCN) 2 , were stabilized as colloids in the employed electrolytes. These colloids can also participate as electroactive species in the CuSCN electroformation. However, for a better interpretation of results, more complete speciation diagrams are also required, but thermodynamic information on these species is still not available. During both potentiostatic and galvanostatic CuSCN growth, a CuSCN solubility effect may explain the slightly low faradaic efficiency of this process. [ABSTRACT FROM AUTHOR]

The corrosion behaviors of two types of FeCrAl alloys were investigated in static oxygen-saturated lead bismuth eutectic (LBE) at 550 °C for up to 8000 h. It was found that the oxide film consists of plumboferrite, Fe 3 O 4 and Fe-Cr-Al spinel. The thickness of the oxide film increased with increasing exposure time from 0 h to 4000 h, and then remained stable from 4000 h to 8000 h. Numerous layered Al-rich and Cr-rich spinel were observed in the Fe-Cr-Al spinel layer and layered α-Al 2 O 3 was observed at the oxide/matrix interface. The corrosion mechanism of FeCrAl alloys in liquid LBE is discussed. • The oxide film consists of plumboferrite layer, Fe 3 O 4 layer and Fe-Cr-Al layer. • Numerous layered Al-rich and Cr-rich spinel were observed in the IOL. • The α-Al 2 O 3 wasn't observed until the exposure time reached 2000 h. • The thickness of the oxide film increases firstly and then remains stable with time. • The Al and Cr preferentially diffuse and oxidize along grain boundaries and sub-boundaries. [ABSTRACT FROM AUTHOR]

Corrosion characteristics of hypo-eutectic Al–1Mg– x Si alloys, which can be used as insert metals of thermal compression bonding (TCB) joints in sodium sulfur cells, have been studied to enhance the corrosion resistance of the alloys in molten sodium at the cell operation temperature of 325 °C. The results showed that the major corrosion product was a NaAlSi compound, and corrosion kinetics decreased as silicon concentration decreased without compromising the bonding strength. The parabolic rate constant of Al–1Mg–3Si alloys was smaller by 25.5% than that of Al–1Mg–12Si alloys. [ABSTRACT FROM AUTHOR]

The technology that is being developed in Sweden for the disposal of high level nuclear waste calls for storage of the waste in copper canisters, which are encapsulated in a bentonite buffer contained in drill holes in the floors of drifts (tunnels) in a granitic rock repository. A controversial issue has arisen during the development of this technology: that copper, when in contact with pure water under anoxic conditions corrodes and hence is not immune as previously believed. This issue is resolved in the present paper by deriving corrosion domain diagrams as a means of presenting the thermodynamics of the system in the clearest form possible, when assessing the immunity and activation of copper. [ABSTRACT FROM AUTHOR]

The specific thermal enthalpy of a moist-air parcel is defined analytically following a method in which specific moist entropy is derived from the Third Law of Thermodynamics. Specific thermal enthalpy is computed by integrating specific heat content with respect to absolute temperature and including the impacts of various latent heats (i.e. solid condensation, sublimation, melting, and evaporation). It is assumed that thermal enthalpies can be set to zero at 0 K for the solid form of the main chemically inactive components of the atmosphere (solid- α oxygen and nitrogen, hexagonal ice). The moist thermal enthalpy is compared to already existing formulations of moist static energy (MSE). It is shown that the differences between thermal enthalpy and the thermal part of MSE may be quite large. This prevents the use of MSE for evaluating accurately the enthalpy budget of a moist atmosphere, a situation that is particularly true when dry air and cloud parcels mix because of entrainment/detrainment processes along the edges of cloud. Other differences are observed when MSE or moist-air thermal enthalpy is plotted on a psychrometric diagram or when vertical profiles of surface deficit are plotted. [ABSTRACT FROM AUTHOR]

Long-term corrosion behavior of T91 steel was investigated in 550 °C static liquid lead-bismuth eutectic (LBE) at different dissolved oxygen (DO) concentration. It was found that the oxide film formed in the oxygen-saturated LBE consists of iron-lead composite oxide, Fe 3 O 4 , Fe-Cr spinel and an inner oxidation zone (IOZ). The IOZ is composed of matrix and FeCr 2 O 4 which follows orientation relationships with the matrix. The thickness of oxide film significantly reduces at DO= 1.26 × 10−6 wt %. Dissolution corrosion and intergranular penetration of Pb-Bi were observed at DO≤ 1.41 × 10−8 wt %. The corrosion mechanism of T91 steel in liquid LBE is discussed. • The oxide film consists of Fe 3 O 4 layer, Fe-Cr spinel layer and inner oxidation zone. • The interface between FeCr 2 O 4 and matrix in the IOZ is semi-coherent. • The occurrence of dissolution and oxidation depends on oxygen concentration. • The optimal oxygen concentration for T91 steel in liquid LBE is about 10−6 wt %. [ABSTRACT FROM AUTHOR]