•The limits for LDX 2101® duplex stainless steel application in H2S-containing environments.•The susceptibility to SCC of LDX 2101® duplex stainless steel in the presence of Cl− and SO32-.•The ...possibility of substituting H2S with thiosulphate for the study of the SCC susceptibility.•The selective corrosion of ferrite phase during crack propagation process in the tested media.
SCC behaviour of a LDX 2101® stainless steel was studied through SSRT in a 20% NaCl solution at 80°C and in the standard NACE TM-0177 solution at 25°C in the presence of S2O32-. Some tests were also performed in the NACE solution at various pH or temperatures. The LDX 2101® was susceptible to SCC in the presence of small thiosulphate concentrations. The selective corrosion of the ferrite phase became the main cause of failure when the thiosulphate concentration was increased to 0.1M in the 20% NaCl at 80°C or when NACE solution temperature was raised to 80°C.
•New Schiff bases tested as bronze corrosion inhibitors in concentrated acid rain.•2-(Salicylideneimino) thiophenol (SITP) afforded η = 100% after 480 h immersion.•Duplex protective film formed: ...adsorbed SITP molecules over a Cu(I)-SITP layer.•Phosphates (P) added to SITP produced higher resistance against localized attack.•SITP and SITP + P hindered bronze decuprification in concentrated acid rain.
In this research, different Schiff bases were synthesized and tested as bronze corrosion inhibitors in concentrated synthetic acid rain at pH 3.3. Some of them showed good inhibiting effects, as detected by EIS and polarization curve recording. The most efficient inhibitor (2-(salicylideneimino) thiophenol, SITP) was also tested with addition of sodium dihydrogen phosphate (P). P improved the surface film resistance against breakdown phenomena. XPS and SEM investigations showed that SITP and SITP + P significantly hinder decuprification. Moreover, SITP forms a protective layer on bronze, composed of both Cu(I)-SITP complexes and adsorbed inhibitor molecules. Cu(II) phosphates were also detected with P addition.
► The effects of anionic surfactant on AZ31 Mg alloy corrosion inhibition is studied. ► The influence exerted towards the anodic and cathodic processes is evaluated. ► An interpretation of inhibition ...mechanism is proposed. ► The influence of a precipitated layer on the anodic Mg oxidation is determined.
Gravimetric and electrochemical measurements were applied to study the inhibiting action exerted by some anionic surfactants (sodium salt of N-lauroylsarcosine, N-lauroyl-N-methyltaurine, dodecylbenzensulphonic acid or sodium lauryl sulphate) towards AZ31 Mg alloy corrosion in electrolyte solutions. The influence of the additive concentration, immersion time and type of surfactant was evaluated.
Their inhibiting effects was attributed to a rapid adsorption on the metallic surface, which limited the cathodic reaction, followed by a precipitation stage with Mg++ ions that made the inhibiting layer thicker and less defective, so that, over time, the anodic oxidation was almost blocked in a wide potential interval.
This study concerns the corrosion behavior of steel in different room temperature cured alkali-activated fly ash mortars exposed to chloride solution. The corrosion process was monitored by ...polarization resistance and corrosion potential measurements and the results were interpreted in the light of a complete microstructural, mechanical and chemical characterization of the mortars. The most compact alkali-activated mortars have higher porosity and lower mechanical properties than a cement-based mortar (CEM), but the protectiveness afforded to the rebars is slightly higher than that obtained in CEM. The reason for this discrepancy is connected to a lower chloride content accumulated in the former mortar type and to a specific inhibition of the rebar corrosion afforded by the pore electrolyte in alkali-activated mortars.
•Study of the effect of brief-time aging within 650÷850°C on LDSS 2101 SCC resistance.•Thermal aging determined precipitation of chromium carbides and especially nitrides.•LDSS 2101 was susceptible ...to SCC in NACE TM-0177 without/with S2O32− ions.•SCC susceptibility in the presence of S2O32− increased after thermal aging.•Interstitial nitrogen impoverishment negatively affected SCC susceptibility.
In this paper, the effect of brief aging within the 650–850°C temperature range on the resistance of lean duplex stainless steel (LDSS) 2101 to stress corrosion cracking (SCC) was discussed. The thermal aging induced a decrease in Vickers microhardness and an increase in alloy ductility. This behaviour was connected to depletion of interstitial nitrogen in austenite. LDSS 2101 was found to suffer SCC in NACE TM-0177 solution, particularly under specific thermal aging and in the presence of thiosulphate ions (S2O32−) at 10−4 and 10−3M. Crack nucleation and propagation were linked to microstructural variations connected to thermal aging.
► Silane conversion coatings as possible alternative to Cr(VI) based pre-treatments. ► 3-mercapto-propyl-trimethoxysilane (PropS-SH) tested on Mg alloys. ► PropS-SH forms a porous conversion coating ...which allows a rapid electrolyte uptake. ► Ce(NO
3)
3 addition to pre-treatment bath improves PropS-SH coating performance. ► Ce
3+ ions presence provides self-healing feature to the coating.
This research investigates the effect of cerium ion addition on the efficiency of a 3-mercapto-propyl-trimethoxysilane (PropS-SH) coating formed on AZ31 magnesium alloy. The coating was obtained by dipping AZ31 coupons in a hydroalcoholic 3-mercapto-propyl-trimethoxysilane solution, added with cerium nitrate, in order to obtain a 5
×
10
−3 or 5
×
10
−4
M Ce
+3 ion concentration. The silane baths were regulated at pH 4 and utilized for filming treatment after 48
h following their preparation. The treated specimens were finally cured for 1
h at 100
°C.
The protective efficiency of cerium modified and unmodified PropS-SH coatings was evaluated by recording potentiodynamic polarization curves and electrochemical impedance spectra in a 0.1
M NaCl environment.
In comparison to PropS-SH coating, cerium nitrate modified silane layer exhibited noticeably improved performances, in particular in presence of a 5
×
10
−3
M Ce
3+ concentration. The increased protectiveness and stability of the modified coatings were attributed to a lower porosity and defectiveness and to self-healing ability provided by Ce
3+ ion presence.
•Cd2+ gill cell transport, a non-essential toxic metal, was characterized in a hypo-hyper-regulating mangrove crab Ucides cordatus.•Cd2+ enter gill cells through Ca2+ channels and is dependent of ...intracellular Ca2+ levels.•Route of entry in gill cells also involves a Cd2+/Ca2+ (2Na) exchanger.•Cd transport depends on Na+/K+-ATPase and gill cell electrochemical gradient.•Vanadate inhibits gill Cd2+ transport and ouabain increase gill Cd2+ transport.
Membrane pathway for intracellular cadmium (Cd2+) accumulation is not fully elucidated in many organisms and has not been studied in crab gill cells. To characterize membrane Cd2+ transport of anterior and posterior gill cells of Ucides cordatus, a hypo-hyper-regulating crab, a change in intracellular Cd2+ concentration under various experimental conditions was examined by using FluoZin, a fluorescent probe. The membrane Cd2+ transport was estimated by the augmentation of FluoZin fluorescence induced by extracellular application of CdCl2 and different inhibitors. Addition of extracellular calcium (Ca2+) to the cells affected little the fluorescence of FluoZin, confirming that Cd2+ was the main ion increasing intracellular fluorescence. Ca2+ channels blockers (nimodipine and verapamil) decreased Cd2+ influx as well as vanadate, a Ca2+-ATPase blocker. Chelating intracellular Ca2+ (BAPTA) decreased Cd2+ influx in gill cells, while increasing intracellular Ca2+ (caffeine) augmented Cd influx. Cd2+ and ATP added at different temporal conditions were not effective at increasing intracellular Cd2+ accumulation. Ouabain (Na+/K+-ATPase inhibitor) increased Cd2+ influx probably through a change in intracellular Na and/or a change in cell membrane potential. Routes of Cd2+ influx, a non-essential metal, through the gill cell plasma membrane of crabs are suggested.
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•Protectiveness of organosilane coating (PropS-SH) on patinated bronze was assessed.•Patina of cuprous oxide and sulphide does not protect the bronze against corrosion.•Both sprayed ...PropS-SH and Incralac® offer a good protection to patinated bronze.•PropS-SH shows excellent performance under UV light and simulated outdoor exposure.•Higher wettability of PropS-SH favours its penetration in porous patina structure.
A 3-mercapto-propyl-trimethoxysilane coating (PropS-SH) applied on Cu-Si-Mn bronze, patinated by “liver of sulphur”, was investigated as a non-toxic alternative to Incralac®, usually applied on outdoor artistic bronzes. Electrochemical testing was performed in synthetic acid rain. Exposure to temperature/UV cycles and accelerated corrosion test simulating unsheltered exposure to rainwater was also carried out. The exposed samples were characterised by FEG-SEM coupled with EDS on FIB cross-sections and XPS on free surfaces. The black patina without protective coating was scarcely protective against bronze corrosion and easily transformed into cuprous oxide. PropS-SH coating fully preserved the black patina microstructure and phase constituents (cuprous oxide and cuprous sulphide). The PropS-SH coating also resulted more protective than Incralac® when aged under run-off conditions. Selective dissolution of copper from the silicon bronze alloy was observed on both uncoated and Incralac®-coated bronze, leading to the formation of an internal Si-rich corrosion layer.
•Corrosion protection of outdoor bronzes in urban atmosphere.•Coating with 3-mercapto-propyl-trimethoxy-silane (with/without CeO2, TiO2, La2O3).•Characterization of coated surfaces after natural and ...accelerated ageing tests.•Role of UV in the degradation process of studied coatings.•Influence of oxide particles on UV action.
3-Mercapto-propyl-trimethoxy-silane (PropS-SH) coatings, with or without the addition of three types of oxide particles (CeO2 (nano-sized), TiO2 (nano-sized) and La2O3 (micro-sized)), were applied on quaternary bronze (Cu-Sn-Zn-Pb) and tested through natural and artificial exposures. In particular, uncoated and coated samples were exposed both in the coastal town of Rimini (Italy) under sheltered/unsheltered conditions and in a climatic chamber where the samples underwent temperature/UV cycles, at constant humidity. The sample surfaces were periodically characterized by SEM, EDS, micro-Raman, FTIR and XRD techniques. Moreover, during natural exposures, runoff rainwater was collected monthly, in order to evaluate the release of the alloying metals from bronze by atomic absorption spectrometry (AAS). The results showed that micro-scale cracking and spalling phenomena took place during natural exposure, partly limiting the protective efficiency of the organosilane coating. In fact, UV radiation has a strong influence on coating performance, inducing structural modifications of the polymer. Oxide particle- and especially TiO2-charged coatings proved to be more resistant to UV degradation.
•-Thick-film modified electrodes are used to study the transfer of ionisable drugs.•-The half-wave potential of the electrochemical process can be predicted from models.•-The half-wave potential ...reveals information about degradation kinetics.•-We can determine pseudo-first order kinetic constants from mid-peak potentials.
Many organic compounds of pharmaceutical interest undergo unwanted reactions that reduce their effectivity or even generate harmful products. One of the many possible mechanisms for these degradation reactions is acid hydrolysis. We propose the use of the thick-film modified electrode setup to follow the acid hydrolysis reaction of water-soluble compounds that contain protonatable sites. We focus on the determination of the first order or pseudo-first order kinetic constant in the aqueous phase. The developed procedure is presented using a model for the transfer of protonated species at liquid|liquid interfaces coupled with an electron transfer process at the solid|liquid interface. Moreover, we experimentally validate this strategy by determining the kinetic constant for the degradation of tylosin A in acidic solutions.
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