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Corrosion behavior of AZ31 magnesium alloy in NH4+-bearing chloride solution with controlled pH was investigated by weight loss experiment, hydrogen collection, and electrochemical test combined with surface morphology and topography observation. The results show that NH4+ and pH of the solution can affect the corrosion of AZ31 magnesium alloy. The existence of NH4+ affects the formation and dissolution of corrosion products, which makes the protective effect of the corrosion product layer weaker. The change of pH value not only affects the corrosion mechanism of AZ31, but also alters the concentration of NH4+ ions in the solution, which further influences the corrosion product layer of AZ31, and finally makes the corrosion of AZ31 change significantly.

Novel C/SiC core-shell fibers have been synthesized through incomplete conversion of carbon fibers by their siliconization with SiO gas. The synthesis was performed in the laboratory-made semi-closed batch-type reactor at 1380 °C for 3 h using a 9:1 M ratio mixture of Si and SiO2 powders as a solid source of SiO gas. The conversion rate of carbon into SiC was 34.0%. All synthesized fibers had a distinct C/SiC core-shell composite structure. The fiber product was of fairly good uniformity in respect of the shell thickness which varied approximately from 0.6 μm to 0.8 μm depending on the location of fibers inside the reactor. It was revealed that the formation of the shell was the result of inward growth of the SiC product layer. The effectiveness of the proposed semi-closed reactor for the synthesis of C/SiC core-shell fibers has been demonstrated.

An innovative continuous spin-freeze-drying technology for unit doses was recently developed. For this technology, a mechanistic primary drying model was developed allowing the calculation of the optimal dynamic drying trajectory for spin-frozen formulations. In this work, a model-based and experimentally verified comparison was made between conventional batch freeze-drying and spin-freeze-drying by analyzing the outputs (i.e., primary drying endpoint, optimal shelf temperature/power heater and product temperature profile) of both primary drying models. Input parameters such as dried product layer resistance (Rp) and heat input parameters (Kv,Ptot) were experimentally determined for both freeze-drying methods and compared. In addition, optimal dynamic process parameters were calculated for 3 model formulations by using both mechanistic models. Finally, model predictions were validated by measuring the product temperature and primary drying endpoint. It was observed that, when considering the same layer thickness, Rp was generally lower for continuous spin-frozen formulations compared to vials frozen in a conventional batch freeze-dryer. This observation contributes to the short primary drying times of spin-frozen formulations. In addition, as spin-freezing drastically increases the surface area of the product and lowers the dried layer thickness, drying times can be reduced even further while an excellent cake structure and appearance can still be obtained. The primary drying model for spin-frozen formulations proved to be equally accurate for the prediction of the primary drying endpoint and product temperature compared to the batch freeze-drying model.

The effect of undissociated acetic acid on the integrity of an iron carbonate (FeCO3) layer formed on platinum and X65 steel substrates is investigated. Experiments were conducted using buffered solutions with 0.8 mM to 5 mM undissociated acetic acid. For the platinum substrates, changes in the FeCO3 layer were monitored via in situ electrochemical quartz crystal microbalance (EQCM) measurements. This investigation was supported by performing electrochemical experiments, under comparable conditions, on the X65 steel specimens, linking the integrity of FeCO3 layer to its corrosion protection effect. The EQCM measurements revealed that the addition of acetic acid, at all concentrations tested here, caused partial dissolution of the FeCO3 layer. The dissolution occurred selectively, with the outer layer dissolving first, leaving behind an inner FeCO3 layer at the end of the immersion experiment. The electrochemical results revealed that introducing the acetic acid caused a sudden increase in the corrosion rate, which over time returned to a lower value similar in magnitude to that seen before addition of the acetic acid. This was attributed to the protection provided by the inner FeCO3 layer, which was only mildly affected by the addition of acetic acid and was able to repair over time. It was proven that the dissolution of the protective FeCO3 layer in the presence of acetic acid was not due to a small pH change but rather due to the formation of ferrous acetate complexes and changes in ionic strength, which decreases the FeCO3 saturation values.

The corrosion behavior of brass H62 exposed to the atmosphere of Nansha Islands for 21 months was investigated by weight loss, scanning electron microscopy, x-ray diffraction and electrochemical techniques. The results showed that the average corrosion rate of brass H62 exposed for 1 year was approximately 13.47 g m−2 a−1, and the corrosion products were observed to be unevenly distributed, attributed to the dezincification corrosion. In addition to the zinc-containing compounds Zn5(OH)8Cl2·H2O and NaZn4(SO4)Cl(OH)6·6H2O, the copper-containing compounds Cu2O and Cu2Cl(OH)3 were also detected on the front side of the exposed sample, while only the zinc-containing compounds were detected on the back side. Both sides of brass H62 showed a decreasing corrosion rate, but the corrosion product layer on the back side appeared to be more protective for the same exposure time.

NH4HCO3 conversion followed by HCl leaching was performed and proven to be effective in extracting Pb and Sr from zinc extracted residual. The mechanism and operating conditions of NH4HCO3 conversion, including molar ratio of NH4HCO3 to zinc extracted residual, NH4HCO3 concentration, conversion temperature, conversion time, and stirring velocity, were discussed, and operating conditions were optimized by the orthogonal test. Experimental results indicate that NH4HCO3 conversion at temperatures ranging from 25 to 85°C follows the shrinking unreacted core model and is controlled by inner diffusion through the product layer. The extraction ratios of Pb and Sr under optimized conditions reached 85.15% and 87.08%, respectively. Moreover, the apparent activation energies of Pb and Sr were 13.85 and 13.67 kJ·mol−1, respectively.

Oxidative-alkaline leaching of vanadium from vanadium-chromium-reducing residues with K2Cr2O7 was investigated in this paper. The effects of processing parameters including dosage of NaOH, dosage of K2Cr2O7, reaction time, and reaction temperature on the leaching efficiency of vanadium were studied. The results simulated by response surface methodology indicated that vanadium leaching was affected significantly by the dosage of K2Cr2O7 and NaOH, and the processing parameters that affected the leaching efficiency of vanadium followed the order m(NaOH)/m(residue) > m(K2Cr2O7)/sssssm(residue) > reaction temperature > reaction time. The leaching efficiency of vanadium was up to 99.92% under optimal conditions: reaction temperature of 90 °C, reaction time of 60 min, liquid-to-solid ratio of 5:1 mL g-1, m(K2Cr2O7)/m(residue) = 0.10, and m(NaOH)/m(residue) = 0.30. The kinetics analysis indicated that diffusion through the product layer was the controlling step and the apparent activation energy for vanadium leaching was calculated to be 58.275 kJ·mol-1.

The ultra-high strength Cu-20Ni-20Mn alloy was prepared by vacuum melting and its mechanical property and corrosion behavior were investigated. After thermomechanical treatment, the alloy exhibited an ultra-high tensile strength of 1204 MPa and the applicable elongation of up to 6.2%. With the increasing exposure time in 3.5% NaCl solution, the corrosion current of the alloy decreased, while the polarization resistance and the charge-transfer resistance of the corrosion surface increased. The corrosion products formed on the surface of the alloy exposed for 1 d, and further corrosion made the corrosion product layer much dense, increasing the corrosion resistance and protecting the alloy from further corrosion.

Limestone is widely used as a sorbent in fluidized bed combustors. The study of limestone attrition characteristics is significant for mass balance and desulfurization efficiency. The present study...

The nature of the hydrothermal reaction between arsenopyrite particles (FeAsS) and copper sulfate solution (CuSO4) was investigated in this study. The effects of temperature (443–523 K), CuSO4 (0.08–0.96 mol/L) and H2SO4 (0.05–0.6 mol/L) concentrations, reaction time (1–120 min), stirring speed (40–100 rpm) and particle size (10–100 μm) on the FeAsS conversion were studied. The FeAsS conversion was significant at >503 K, and it is suggested that the reaction is characterized by the formation of a thin layer of metallic copper (Cu0) and elemental sulfur (S0) around the unreacted FeAsS core. The shrinking core model (SCM) was applied for describing the process kinetics, and the rate of the overall reaction was found to be controlled by product layer diffusion, while the overall process was divided into two stages: (Stage 1: mixed chemical reaction/product layer diffusion-controlled) interaction of FeAsS with CuSO4 on the mineral’s surface with the formation of Cu1+ and Fe2+ sulfates, arsenous acid, S0, and subsequent diffusion of the reagent (Cu2+) and products (As3+ and Fe2+) through the gradually forming layer of Cu0 and molten S0; (Stage 2: product layer diffusion-controlled) the subsequent interaction of CuSO4 with FeAsS resulted in the formation of a denser and less porous Cu0 and S0 layer, which complicates the countercurrent diffusion of Cu2+, Cu1+, and Fe2+ across the layer to the unreacted FeAsS core. The reaction orders with respect to CuSO4 and H2SO4 were calculated as 0.41 and −0.45 for Stage 1 and 0.35 and −0.5 for Stage 2. The apparent activation energies of 91.67 and 56.69 kJ/mol were obtained for Stages 1 and 2, respectively.

The accelerated corrosion behavior of copper T2 and brass H62 exposed in simulated Nansha marine atmosphere for different periods were investigated by weight loss method, SEM, XRD and potentiodynamic polarization measurements. The results indicate that copper T2 and brass H62 underwent severe corrosion, and the final corrosion rates at 32 days of exposure were 0.24 μm/d and 0.10 μm/d, respectively. Moreover, the overall corrosion type of copper T2 was uniform and the corrosion products Cu2O and Cu2Cl(OH)3 played a vital role in the corrosion rate of copper. While the dezincification corrosion with zinc preferential dissolution was obvious in brass H62. The predominant phases were the zinc-rich compounds Zn5(OH)8Cl2·H2O, Zn12(SO4)3Cl3(OH)15·5H2O and NaZn4(SO4)Cl(OH)6·6H2O. There existed a large number of copper-rich holes with 20–50 μm depth beneath the corrosion product layer.

Both uranium and beryllium are very important strategic metals and have been applied to many fields, such as nuclear industries, atomic energy, metallurgical industries and telecommunications industries. When uranium and beryllium in the ore were leached simultaneously, a complicated downstream separation process was needed. Based on the different chemical stabilities of uranium and beryllium, an acid leaching method was employed in this work to selectively extract uranium from uranium–beryllium ore. The effects of sulfuric acid concentration, temperature, liquid–solid ratio and leaching time on the leaching efficiency were studied experimentally. Results indicated that treatment of the ores in 0.2 M sulfuric acid at 348.5 K for 50 min with the solid–liquid ratio of 0.25 g/mL is optimum. Under optimal conditions, the leaching efficiencies of uranium is 97.4% and the leaching efficiencies of beryllium is 1.78%, and the standard deviation of them are less than 2% and 0.06%, respectively. Results of kinetic study suggest that the leaching process of uranium was thermodynamically favorable and was controlled by the diffusion of the product layer, whereas the rate-determining step for beryllium leaching is the surface chemical reaction.

Alkaline injection is an effective way to control the emission of high concentration SO3 caused by the use of high-sulfur coal and selective catalytic reduction (SCR), but its performance is affected by the competitive absorption of SO2. A fixed-bed reactor was used to study the competitive absorption of SO3 and SO2 by Ca(OH)2. The dynamic absorption curves in different atmospheres were obtained, the intermediate products were characterized, and the competitive absorption mechanism was discussed. The absorption of SO3 and SO2 consists of the chemical kinetics-controlled and product layer diffusion-controlled stages. In the chemical kinetics-controlled stage, the SO3 and SO2 removal efficiencies were around 90% and 55% at first and then decreased; the SO3 selectivity was around 0.1 at first and then increased. In the product layer diffusion-controlled stage, the SO3 removal efficiency gradually decreased but kept greater than 10%, while the SO2 removal efficiency deceased to zero; the SO3 selectivity continued to increase and reached 0.31 at most when SO2 absorption ceased. There existed significant competition between SO3 and SO2 absorption. The increasing SO3 concentration promoted the SO3 absorption and the increasing SO2 concentration decreased it. The absorption of SO3 increased the intensity of the SO 4 2 - band, decrease the intensity of the SO 3 2 - band, and made the product layer more compact. The possibility of SO3 reacting with the components (CaSO3, CaSO4 and CaCO3) on the reacted Ca(OH)2 surface was analyzed. Ionic diffusion was proposed as the main mechanism of the continuous SO3 absorption after the formation of a dense product layer.

The article focuses on the study of microclimate conditions under bridge structures and their influence on the characteristics of corrosion products developed on the surface of structures designed from weathering steels. The development of a protective corrosion product layer on weathering steel is influenced mainly by the time of wetness, structural solution of the bridge and concentration of corrosion stimulators in the atmosphere. The main corrosion stimulators in the air are sulfur dioxide and chlorides. Since the 1990s, concentrations of sulfur dioxide in Central Europe have significantly decreased. Currently, chlorides are the main corrosive stimulator, primarily from deicing salts used in winter road maintenance. The extent and scope of corrosion damage to a steel structure located in an environment with high chloride deposition is not uniform across all exposed surfaces. The submitted article therefore focuses on monitoring the dependence between the amount of chlorides deposited and the location and orientation of typical surfaces of steel bridge structures.

Bastnaesite, monazite and xenotime are rare earth minerals (REMs) that are typical sources for rare earth elements (REEs). To advance the understanding of their leaching and precipitation behavior in different hydrometallurgical processes, Eh-pH diagrams were constructed and modified using the HSC 9.9 software. The aqueous stability of rare earth elements in H2O and acid leaching systems, i.e., the REE-Ligands-H2O systems, were depicted and studied based on the Eh-pH diagrams. This study considers the most relevant lixiviants, their resulting equilibrium states and the importance in the hydrometallurgical recovery of rare earth elements (REMs). A literature review was performed summarizing relevant Eh-pH diagrams and associated thermodynamic data. Shifting stability regions for REEs were discovered with additions of acid ligands and a narrow stability region for soluble REE-(SO4/Cl/NO3) complexes under highly acidic conditions. As such, the recovery of REEs can be enhanced by adjusting pH and Eh values. In addition, the Eh-pH diagrams of the major contaminants (i.e., Fe, Ca and Al) in leaching systems were studied. The resulting Eh-pH diagrams provide possible insights into potential passivation on the particle surfaces due to the formation of an insoluble product layer.

International audience; This paper summarizes the chemical effects that can occur during the corrosion process of carbon steel in a CO 2 saturated aqueous environment. Particularly, it focuses more on the results that small chemical contaminations in the environment have on the corrosion process. Underground waters present complex chemistry with several different dissolved ions (chlorides, carbonates) even in high concentrations that impact substantially on the corrosion rates of these materials. Moreover, gas impurities present in the gas mixture, such as oxygen in carbon capture and storage applications, constitute a supplementary form of significant contamination in the CO 2 saturated aqueous environment. In particular, the effect on both electrochemical reactions and corrosion product layer is examined for several chemical species that are commonly present either in the gas mixture or in underground waters.

Whilst monolithic models combine a whole chain of interacting modules, the modular research strategy focuses on individual modules and their improvement by abstracting the rest of the system to simple input and output signals. And as Nisan and Schocken emphasise in the context of computer science: “. . . a good modular design implies just that: You can work on the individual modules independently, while completely ignoring the rest of the system.”

The article is devoted to the analysis of emergency management methods in storage tanks of crude oil and petroleum products in the territory of Ukraine. The peculiarities of reservoir operation, possible emergencies in reservoir parks, the nature of the destruction of reservoirs during the explosion of the air–vapor mixture, and the process of petroleum products combustion in them are considered. Methods of fire localization and extinguishing in oil and oil-product reservoirs are investigated. Their advantages and disadvantages are analyzed. The feasibility of using a “sublayer” method of fire extinguishing in liquid reservoirs has been determined. This method has significant advantages over traditional methods of ceasing combustion. The modernized installation of “sublayer” fire extinguishing with the use of self-powered foam pipeline for the submission of foam under the product layer, which, in comparison with other methods of fire extinguishing, allows to guarantee a high fire safety level and personnel security of fire and rescue units involved in the fire elimination. The practical significance of the analytical studies is formulated.

The influence of minor Nd substitution on the microstructure and corrosion resistance of Mg–Zn–Y alloy were investigated. Results indicate that the partial substitution of Nd for Y can effectively refine grains but deteriorate the corrosion resistance of extruded Mg–Zn–Y alloy. The corrosion rates, measured by immersion tests in 3.5% NaCl solution at 25°C, are 12 and 19 mm · y−1 for the Mg-5.6Zn-1.4Y and Mg-5.6Zn-1.0Y-0.4Nd alloys, respectively. The negative effect of Nd is associated with enhanced microgalvanic corrosion resulting from grain refinement and higher area of second phase, as well as to a degraded protectiveness of the corrosion product layer.

The influence of the Si content and corrosion temperature on the formation of the compact multiphase corrosion-product layer when Fe–B–Si alloys were corroded in liquid zinc, was studied. Si was enriched at the corrosion interface and dissolved in the corrosion product layer, thus, affecting the diffusion of Zn and Fe. The multiphase corrosion product layer composed of Fe–Zn compounds with residual Fe2B at the corrosion interface was formed. The Fe–Zn compounds are tightly occluded among the residual Fe2B phase, which can inhibit diffusion. The Fe–Zn compounds tend to dissolve at high temperatures. However, because the complete residual Fe2B skeleton structure was retained and a small number of compounds remained among the residual Fe2B skeletons, the inhibition of the multiphase corrosion product layer did not cease. When the Si content was 0.318 wt%, the corrosion product layer was the densest, and when the Si content was 0.196 wt%, the corrosion product layer had the weakest diffusion-inhibition effect.

Part of tin in the magnetite-type tin-bearing ores existed as isomorphous Sn4+ in the lattice of magnetite (Fe3-xSnxO4, X = 0–1.0), which was impossible to separate and recover by physical beneficiation methods In this study, a calcified roasting process under CO-CO2 atmosphere was applied to separate tin from the magnetite-type tin-bearing tailings, and the results indicated that the isomorphous Sn4+ in the magnetite was removed effectively. Then, Fe2.6Sn0.4O4 was synthesized to investigate the interface reaction mechanisms between CaO and Fe3-xSnxO4. The results indicated that the calcified roasting process can be divided into three stages: the ionic migration of Sn4+ on the interface between CaO and Fe3-xSnxO4 and formation of calcium stannates (Ca2SnO4/CaSnO3), diffusion of Sn4+ through the product layer (CaSnO4/Ca2SnO4), the oxidation of FeO to Fe3O4 by CO2. These findings can provide theoretical support for the utilization of magnetite-type tin-bearing tailings by the calcified roasting process.

A novel method for Na 2 SnO 3 preparation from SnO 2 and Na 2 CO 3 roasted under CO-CO 2 atmosphere in a solid state has been successfully developed. In this study, the formation kinetics of Na 2 SnO 3 was investigated. The formation of Na 2 SnO 3 was controlled by the first-order interfacial chemical reaction at 800 °C under 10 vol% CO content; as the temperature increased to 850 °C–900 °C, it was controlled by the three-dimension (Ginstling and Brounshtein) diffusion through the product layer at the early reaction stage. The rate constant increased with the increasing of temperature. Furthermore, the rate controlling characterizations of three-dimension diffusion were also discussed.

The effects of the presence of NaCl vapour on limestone SO 2 capture behaviour were examined. When NaCl was present in the sulphation atmosphere, the effects of the presence of H 2 O, reaction temperatures, particle sizes and NaCl concentrations on limestone SO 2 capturing were studied in a tailor-made three-section control horizontal furnace. The presence of NaCl in the sulphation atmosphere clearly improves the limestone SO 2 capturing capacities. H 2 O has a strong impact on the effect of NaCl vapour on limestone sulphation. In the absence of H 2 O, the enhanced effect of NaCl vapour on limestone sulphation is reinforced further. The presence of NaCl vapour changes the effects of reaction temperatures on limestone SO 2 capturing capacities. The optimum sulphation temperature for limestone in the presence of 1058 ppm NaCl is 1000 °C rather than the optimum temperature of 850 °C in the absence of NaCl. A higher limestone SO 2 capturing capacity is achieved with a smaller particle size in the presence of NaCl. The presence of NaCl vapour reduces differences in limestone SO 2 capturing capacities with different particle sizes. At 850 and 1000 °C, the SO 2 capturing capacity of limestone increases and later decreases with the Na/S mole ratio increasing. While, the SO 2 capturing capacity of limestone increases monotonically with the Na/S mole ratio increasing at 1200 °C. The Na + of NaCl vapour doped into the product layer during sulphation, which enhances the SO 2 capturing capacity of limestone. The reaction between NaCl vapour and SO 2 reduces SO 2 concentrations, negatively affecting limestone sulphation, while the generated HCl promotes limestone SO 2 capturing through changes in the surface morphology of the product layer. The effect of NaCl vapour on limestone sulphation is thus dependent on the extent of reactions between NaCl vapour and SO 2 .

In this study, the influence of NH 4 HF 2 activation on the leaching of low-grade complex copper ore in NH 3 -NH 4 Cl solution was studied. The related thermodynamic, optimization, and kinetic studies were investigated by an exponential computation method, orthogonal tests, and shrinking core model, respectively. The results indicate that NH 4 HF 2 can react with Fe 2 O 3 , SiO 2 and Al 2 O 3 , and the concentration of NH 4 HF 2 is the crucial factor on the digestion of the gangues combined with copper oxides. The optimum leaching conditions were established as 3 mol/L NH 4 Cl, 2.5 mol/L NH 3 ·H 2 O, 1 mol/L NH 4 HF 2 , 10 mL/g liquid to solid ratio, 60 °C, and 3 h. Under the conditions, the leaching efficiency of copper was 89.39%. The leaching process is controlled by the diffusion of reactants across product layer, and the activation energies corresponding to 0, 0.1, 0.3, and 0.5 mol/L NH 4 HF 2 were calculated as 27.9, 19.8, 30.7, and 32.6 kJ/mol, respectively.

In this work, a modified model was presented. The simulation results showed that the modified model was capable to predict the whole conversion-time curve of the carbonation reaction in long series of calcination-carbonation cycles, particularly at short reaction times, including the sudden transition between the first fast regime and the second product layer diffusion controlled slow regime. In comparison with the model of Grasa, to determine the value of conversion corresponding to the transition between regimes ( X k-D ) was unnecessary in the modified model. In addition, compared with the models of Sun and Benedett, the modified model proposed here was capable of predicting with a reasonably good accuracy the carbonation rates obtained in the relevant range of reaction times and conditions in long series of calcination- carbonation cycles, and concept to be successfully applied.

Traditionally high strength (σy ≥ 400 N/mm2) rolled sheet thicker than 50–60 mm of low-carbon structural steel is produced by hot rolling technology followed by normalizing or hardening and tempering. Contemporary equipment makes it possible to produce rolled product 50–140 mm thick of low carbon steel by thermomechanical rolling and to obtain a required set of properties without expenditure on production operations connected with additional metal heating such as normalizing and tempering. Results are given in this article for studying one of the thick sheet property indices, i.e., structure nonuniformity through plate thickness. The microstructure is compared for rolled sheet 100 mm thick of low-carbon microalloyed steel structural steel produced in the 4200 NLMK Dansteel mill by thermomechanical rolling technology (TMT) with the microstructure obtained as a result of hot rolling followed by normalizing (HT). Grain sizes are determined at different points of rolled product layer thickness, and histograms are plotted for their distribution, making it possible to compare the degree of inhomogeneity for the microstructure with respect to grain size. The type, size, and density of carbonitride particles are determined at distances of 1/2 and 1/4 through the thickness of 100 mm plate after TMT and HT.

Glass fogging is a phenomenon occurring in lyophilized drug products and can be described as a thin product layer deposited on the inner surface of the glass container, in the area not covered by the lyo cake itself. It is often considered a cosmetic defect; however, the loss of container closure integrity is a potential consequence of the fogging’s expansion to the vial neck region, making this a potential critical defect. Thus, a method for predicting the extent of vial fogging before the actual freeze-drying is of particular interest for the pharmaceutical industry. For that reason, we evaluated a simple method (“simulated fogging”) applicable to drug product formulations in a specific container closure system. Two different vial types with different surface hydrophilicity were tested using 3 model protein formulations, comparing the simulated fogging test and the degree of fogging after actual lyophilization. The simulated fogging method could predict fogging and showed a correlation to fogging in lyophilized drug product glass vials. We observed that all formulations showed fogging in the hydrophilic vials. By contrast, hydrophobic vials prevented fogging, however, interestingly with remaining defects of so-called droplet formation. Other than extent of fogging, no additional differences of lyophilized cake properties or other product quality attributes were observed between products using the different glass vial types tested.

The role of trace concentrations of O2 (ca. 20 ppb(w)) relating to pitting in marginally sour environments was investigated in this work. Laboratory experiments were conducted with X65 mild steel specimens at pH 5.00 ± 0.01, 30 °C, 0.97 bar CO2 and 0.04 mbar H2S with/without O2 for up to 7 days. Acquired corrosion rate, the composition of the corrosion product layer, and surface profile after the layer was removed were compared. As a result, only H2S chemisorption layer was formed without oxygen; this layer could be partially compromised when [O2]aq > 3 ppb(w), leading to pitting initiation.

Isothermal oxidation behavior of an HVAF-sprayed NiCoCrAlY coating on AISI 304L was studied in an Ar-10 %H-2-20 %H2O environment at 600 A degrees C. Techniques such as BIB/SEM, EDS, and XRD were used to comprehensively characterize the coating and the coating/substrate interface to investigate the oxidation mechanisms. Results were also compared with those obtained from an uncoated AISI 304L substrate. The alumina-forming NiCoCrAlY coating was found to exhibit superior oxidation behavior due to the formation of a slow-growing and protective Al2O3 scale, while the chromia-forming bare 304L substrate lost its protective capability due to the formation of a duplex [Fe3O4 on (Fe,Cr)(3)O-4 spinel oxide] corrosion product layer.

This work investigated the effect of steam concentration in carbonation on CO2 capture by carbide slag during the calcination/carbonation cycles in a dual-fixed bed reactor. Under severe calcination conditions, the pore structure of calcined carbide slag carbonated in the presence of 20 vol. % steam is better than that in the presence of 60 vol. % steam. In the presence of steam in carbonation, the drop of carbide slag in carbonation conversion under severe calcination conditions (950 °C, pure CO2) is relatively smaller than that without steam. Higher steam concentration results in significantly higher carbonation conversion of carbide slag for short carbonation duration (e.g., 5 min), because higher steam concentration leads to greater accelerating effect on CO2 diffusion through product layer. Steam exhibits a two-side effect on the carbonation performance of carbide slag, and the effect of high steam concentration on carbonation conversion is higher than that on pore structure.