Salt Immersion Research Articles

Isotopic concentration of uranium from alpha spectrum of electrodeposited source on 4H-SiC detector at 500 °C

4H-SiC alpha detectors were fabricated with a 21-μm thick depletion depth and were packaged into a stainless-steel casing with a mineral insulation cable and a standard BNC connector. The packaged detectors had a resolution of 0.624% FWHM at 5.486 MeV prior to salt immersion. The detectors were then immersed in a LiCl–KCl–UCl3 molten salt at 500 °C, from which a thin layer of depleted uranium was electrodeposited onto the detectors. Alpha particle emission spectra were collected from the electrodeposited source. The energy resolution of the surviving detector was 2.29% FWHM at 4.198 MeV and was sufficient to separate the 234U from 238U alpha emissions (577 keV difference). The 234U/238U activity ratio and the isotopic concentrations of 234U and 238U were determined and are representative of the uranium source used in the electrodeposition.

Experimental investigation on bonding property of asphalt-aggregate interface under the actions of salt immersion and freeze-thaw cycles

Abstract Snowmelt salts and deicing additives which are used to remove the snow/ice in winter make the pavement experience diverse and complex actions such as freeze-thaw (F-T) cycles and salt immersion. Meanwhile, interface damage of asphalt-aggregate is a major reason for the decay of mixture properties. So, the interface properties under the impacts of snowmelt salt and F-T cycles were investigated in this paper. Three factors including salt concentration, soaking time and F-T cycles were considered based on the service condition of the pavement. ‘Sandwich’ specimens of asphalt-aggregate were prepared in the laboratory. Also, pull-off tensile test was conducted by universal test machine. Digital image processing technology was employed to analyze the interface failure mode. Results indicated that the selected three factors presented significant effects on moisture absorption and pull-off tensile strength (POTS). All of the POTS at low, medium and high temperatures decreased after conditioning. And the pull-off tensile strength loss (POTSL) after salt solution soaking and F-T cycles were all higher than the pure water soaking one. The power model can be used to describe the composite damage degree imposed by different factors. The coupling actions of salt immersion and F-T cycles would induce the failure mode variety. Adhesive failure was prone to occur at low temperature under the condition of low salt concentration and F-T cycles. Erosion effect of high concentration solution would induce the adhesive failure at medium temperature.

Ảnh hưởng của ướp muối đến sự oxy hóa lipid và oxy hóa protein trong cơ thịt cá lóc (Channa striata) nuôi

The study was carried out to investigate lipid oxidation and protein oxidation of snakehead fish meat by changing the salt concentration (0, 4, 8, 12, 16, 20% NaCl, w/v) and pH adjustment (4, 5, 6, 7, 8 and 9) of soaking solution. The magnitude of oxidative changes was monitored by: (i) lipoxygenase enzyme activity (LOX), peroxide value (PV) and TBRAS (thiobarbituric acid reactive substances) value, (ii) protease activity, sulfhydryl index, and (iii) whiteness index, water holding capacity and drip loss (physicochemical properties). The results showed that salting process has limited the activity of lipoxygenase and protease enzymes, while improving the quality of fish meat. Salted fish in 12% NaCl (w/v) for 3 hours had significantly lower (p < 0.05) lipoxygenase and protease activity, PV and TBARS value and a higher sulfhydryl value when compared with control sample (no salt immersion) and salted fishes in lower salt concentration (4, 8% NaCl, w/v). In addition, lipid oxidation and protein oxidation of the snakehead fish meat was delayed at neutral pH of salt solution, which was most effective at pH 8. The quality of snakehead fish meat at this condition was also improved with whiteness index (WI) of 81.17, water holding capacity 72.39%, and drip loss 11.78%.

Microcapsules of multilayered shell structure synthesized via one-part strategy and their application in self-healing coatings

Abstract The microcapsules of multilayered shells structure loaded with dicyclopentadiene (DCPD) were prepared via one-part strategy in Pickering emulsions stabilized by hydrolyzed poly(glycidyl methacrylate) (PGMA) nanoparticle. The target microcapsules had polyurethane (PU) inner shell layer, phenol-formaldehyde (PF) outer shell layer, and PGMA outermost layer. Meanwhile, in order to compare with the target microcapsules, the microcapsules of double layered shells (Sample 1) were both acquired. Size distribution, morphology, chemical structure and reaction heat of the capsules were studied by particle size analysis, scanning electron microscopy (SEM), fourier transform infrared spectra (FTIR), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC). It was found that the ingredients of PF, PU and PGMA were contained in the target microcapsules of multilayered shells, and the encapsulated core materials still kept high chemical reactivity. The resistant properties against thermal and solvent were evaluated by thermogravimetric analysis (TGA) and the solvent immersion test. When the IPDI content was suitable, the multilayered shells microcapsules (Sample 2, 3) possessed excellent thermal and solvent resistances comparing with Sample 1. In addition, the coatings embedded Sample 3 have displayed good self-healing performance by SEM, electrochemical impedance spectroscopy (EIS), salt immersion test and the tensile analysis of tapered double cantilever beam (TDCB) fracture specimens.

Corrosion behavior of aluminide diffusion coatings in low temperature molten carbonate electrolysis environments

Interest on low‐temperature molten carbonate electrolysis processes (T &lt; 600 °C) for advanced energy conversion and storage applications appears to be progressively growing in literature. However, the corrosion of metallic materials in molten carbonate salts in equilibrium with the acidic CO2‐rich electrolysis gas atmospheres has been scarcely studied. In this work, the corrosion stability of a low‐activity FeAl aluminide diffusion coated 316 L stainless steel has been tested in a ternary carbonate eutectic mixture Li2CO3‐Na2CO3‐K2CO3 by 48 h‐immersion tests at 500 °C under CO2 atmosphere. Before the corrosion testing, the coated steel samples were pre‐oxidized in air at 750 °C in order to generate a protective thin alumina film on the aluminide coating surface. The salt immersion results indicate that FeAl aluminide coatings are not stable in acid molten carbonate environments due to rapid transformation of the pre‐existing alumina film into a non‐protective mixed Fe‐Al oxide crystalline layer. Corrosion degradation has been found to consist of both general and localized forms of attack. Factors affecting FeAl aluminide coating corrosion have been analyzed and discussed in detail.

Osmotic dehydration kinetics of oyster mushroom

This research was carried out to study the effect of osmotic dehydration behavior of oyster mushroom. The effect of solution concentration, immersion time and temperature on mass transfer parameters were observed during osmotic dehydration of oyster mushroom at three different temperatures −12, 27 and 45°C. A number of process parameters on osmotic dehydration such as water loss (WL), solid gain (SG), and normalized solid content (NSC) were investigated. Results showed that increase in salt concentration and immersion time resulted in %WL, %SG and NSC. The highest NSC (4.09 g solids/100g of initial weight of sample) was achieved for product osmosed in 25% salt solution for 6 hr immersion time. The pseudo diffusion coefficient, k was determined by using Fick’s First Law of diffusion equation. Plotting k values against inverse absolute temperature an Arrhenius type relationship was developed from which the calculated activation energy values of 1.8 and 3.64 kcal/gm-mole were obtained for 20% and 15% salt solution respectively.

Concrete durability under different circumstances based on multi-factor effects

Concrete durability has become a hot research field in civil engineering. Concrete structures suffer salt-erosion damage to different degrees in the semi-arid region of North China. The environmental condition is one of the important factors affecting the durability of concrete constructions. To realize fully the interaction between various environmental factors, this paper researched concrete durability in the salt environment under combined actions (immersing, freeze–thaw cycles, and wet–dry cycles). According to the laboratory test data, the concrete-durability degradation law under coupling-effect factors was investigated. The results show that concrete's compressive strength decreases with the increase of salt concentration and immersion time. No matter what the environmental conditions were, the compressive strength-loss ratio increased with the test time. The compressive strength-test results indicate that sodium sulfate has the strongest corrosive effect on concrete durability, followed by calcium chloride, with sodium chloride having the weakest corrosion. Compared with the other two environmental factors, the wet–dry cycle is the key factor affecting concrete durability. Therefore, in engineering practice, the influence of environment conditions on the strength and durability of concrete should be taken into full consideration, especially in the wet–dry environment with salt conditions.

Preparation and Characterization of a Novel Hydrogel-Based Fouling Release Coating

With the rapid development of marine transportation industry, biological fouling not only affects the speed of navigation but also highly increases fuel consumption. In the paper, a novel hydrogel-based fouling release coating is developed to address the issue by a combination of non-stick property with a low surface tension of the coating. A hydrogel-based silicone fouling release coating was synthesized and two kinds of different intermediate coatings were studied to give a proper match as the tie layer between the substrate coated with primer and the hydrogel silicone on the surface. The adhesion strength, surface tension as well as surface topography of the fouling release coating were studied. The corrosion resistance and anti-fouling performance of the substrates sprayed with the coating were characterized by salt spray test and immersion test in a simulated marine system. The results show that the adhesion between the substrate and the fouling release coating is grade two measured by grid test. The water contact angle of the coating is 104.8o and Rz of the coating is 10.71μm. The specimen is intact after 1000 hours under salt spray test. No diatom was found settled on the specimens in a simulated static marine system while a little diatom was observed on the specimens in a simulated dynamic marine system. It has been found that the intermediate coating comprising of epoxy resin gives proper match between the primer and the fouling release coating consisting of PDMS resin. The coating exhibits superior anti-fouling performance under stationary state.

Self-Healing Coatings to Mitigate Post-Impact Corrosion

Self-healing polymeric coatings have offered tremendous potential for repairing damage and extending the service life and safety of metallic structures. There have been many challenges associated with the catalyst activated version of the self-healing oligomer filled microcapsule coating additives (or microbeads) technology, but a non-catalyst version appears more promising. The objective of this study was to identify the effect of self-healing coatings in an epoxy coating system containing the non-catalyst microbeads on post-impact corrosion mitigation of water infrastructure. Experimental results showed that coatings containing microbeads did not fully prevent corrosion of the post-impact exposed metal substrate over the exposure period for this study, especially in salt fog and immersion conditions. However, this coating showed less coating degradation compared to the coating without the presence of microbeads.

Studies on surface treatment of electrodeposited Ni–Zn alloy coatings using saccharin additive

Ni–Zn alloy coatings were electrodeposited galvanostatically at room temperature. Saccharin (0 to 1.8 g L−1) was added in the deposition bath as an additive agent. The effects of varied saccharin content addition on the physical properties of Ni–Zn alloy coatings were studied. The Ni–Zn alloy coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic absorption spectroscopy (AAS), atomic force microscopy (AFM), contact angle, electrochemical impedance study (EIS), salt immersion test, friction coefficient, and wear resistance tribology techniques. The XRD study confirmed the formation of Ni–Zn alloys with mixed phases of Ni–Zn alloy depending upon the saccharin content addition. The AAS analyses based on varied saccharin addition confirmed Ni–Zn alloy composition between 64:36 and 22:78 at.%. The effects of varied saccharin addition on physical properties like stress, strain, microstructure, topography, wettability, wear, and corrosion resistance were studied. The optimized 1.6 g L−1 saccharin addition in the deposition bath with Ni–Zn composition as 25:75 at.% possesses highly enhanced surface properties like compact, smooth microstructure, and increased corrosion resistance with reduced friction coefficient value.

Electrolytic Production of Silicon Using Liquid Zinc Alloy in Molten CaCl2

A new electrolytic production process for solar-grade Si has been proposed utilizing liquid Si–Zn alloy cathode in molten CaCl2. To establish this process, the behavior of liquid Zn metal in molten CaCl2 at 1123 K was investigated. Evaporation of Zn metal was largely suppressed by immersion in the molten salt, which enabled the use of a Zn electrode despite its high vapor pressure. Cyclic voltammetry results suggested that the reduction of SiO2 on a Zn cathode proceeded at a more negative than 1.45 V vs. Ca2+/Ca. After potentiostatic electrolysis at 0.9 V, Si particles with sizes of 2–30 μm were precipitated in the solidified Zn matrix by a slow cooling process. The rate-determining step for electrochemical reduction of SiO2 on the Zn cathode was discussed on the basis of a measurement of the alloying rate between solid Si and liquid Zn.

Acrylamide Reduction in Potato Crisps using: Asparaginase from Candida utilis, Commercial Asparaginase, Salt Immersion, and pH Treatment

This paper investigates the reduction of acrylamide formation in potato crisps as a result of asparaginase treatment, using calcium chloride and sodium chloride solutions with different concentrations, immersion in different pH solutions, and different frying conditions. The main aim is to compare the reduction of acrylamide in potato crisps using two kinds of asparaginase enzyme; the first enzyme is commercial but the second is an enzyme made from C. utilis specifically for food treatment. While commercial asparaginase reduces acrylamide formation by 39%, asparaginase obtained from C. utilis makes a higher reduction of 58% in potato crisps. However, both enzymes in combination with blanching inhibit much higher amount of acrylamide formation. Treatments with calcium chloride, sodium chloride, and citric acid have considerable effects on the content of acrylamide in fried potato. The maximum reduction of acrylamide is 95% caused by commercial treatment plus blanching.

Slurry aluminizing: A solution for molten nitrate salt corrosion in concentrated solar power plants

Molten nitrate salts (KNO3–NaNO3) are used extensively as heat transfer fluids in concentrated solar power (CSP) applications. The oxidative character of nitrate salts at high temperature conditions leads to challenges in the corrosion protection of CSP installations in contact with molten salts. This work reports efforts to protect low-cost ferritic–martensitic P91 (Cr9–Mo1) and austenitic stainless steel 304SS materials against molten salt corrosion using slurry aluminizing. The gravimetric results show a significant improvement for aluminized alloys up to 1700h immersion in molten nitrate salt at 600°C. The extent of protection in P91 becomes comparable with the most competitive resistant materials e.g. Inconel 625. Metallographic investigations and scanning electron micrographs reveal no sign of corrosion in the substrates beneath the aluminide coatings during the immersion test. Electron probe microanalysis results reveal Na(Fe,Al)O2 as the protective corrosion product forming on the surface of both aluminized steels.

Impact of Corrosion Test Container Material in Molten Fluorides

The effects of crucible material choice on alloy corrosion rates in immersion tests in molten LiF–NaF–KF (46.5–11.5-42 mol. %) salt held at 850 °C for 500 hrs are described. Four crucible materials were studied. Molten salt exposures of Incoloy-800H in graphite, Ni, Incoloy-800H, and pyrolytic boron nitride (PyBN) crucibles all led to weight-loss in the Incoloy-800H coupons. Alloy weight loss was ∼30 times higher in the graphite and Ni crucibles in comparison to the Incoloy-800H and PyBN crucibles. It is hypothesized galvanic coupling between the alloy coupons and crucible materials contributed to the higher corrosion rates. Alloy salt immersion in graphite and Ni crucibles had similar weight-loss hypothesized to occur due to the rate limiting out diffusion of Cr in the alloys to the surface where it reacts with and dissolves into the molten salt, followed by the reduction of Cr from solution at the molten salt and graphite/Ni interfaces. Both the graphite and the Ni crucibles provided sinks for the Cr, in the formation of a Ni–Cr alloy in the case of the Ni crucible, and Cr carbide in the case of the graphite crucible.

Corrosion Behavior of Tungsten Copper Alloy Produced by Infiltration Sintering

In this paper, W80CuNi0.3 alloy was prepared by cold isostatic pressing (CIP) and infiltration sintering, and its corrosion behavior was investigated by neutral salt spray accelerated test, immersion test and electrochemical measurement. It turned out that in the neutral salt spray and immersion test,the mass loss and corrosion rate of W80CuNi0.3 were far lower than those of 45 steel. The corrosion mainly occurs in the bonding phase of Cu, and the initial corrosion form of W80CuNi0.3 was pitting, the main reason of W80CuNi0.3 corrosion was Cl- erosion. The polarization curves analysis showed that compared with 45 steel, W80CuNi0.3 alloy had higher corrosion potential and lower corrosion current. Therefore, W80CuNi0.3 alloy are prone to stable passivation, so it has superior corrosion resistance.

Corrosion Behavior of Anodized 2195 Al-Li Alloys with Different Sealing Methods

The influence of post-sealing treatment on corrosion behavior of anodized 2195 Al-Li alloys was studied by potentiodynamic polarization, Electrochemical Impedance Spectroscopy(EIS),salt spray test and immersion test in solution of phosphoric acid/chromic acid. The anodic films were post- treated with boiling water, potassium dichromate, nickel sulfate and cerium nitrate, respectively. The results show that the post- sealing can greatly enhance the corrosion resistance of the anodized 2195 Al- Li alloy. The corrosion resistance of the anodic oxide film after post- treatment with cerium nitrate is far better than that with boiling water, but slightly inferior to those with potassium dichromate and nickel sulfate. Finally long term spray test results reveal that the anodized 2195 Al-Li alloy after sealing treatment with potassium dichromate exhibits the highest corrosion resistance among the four post-sealing treatments.

Studies on enhancement of surface mechanical properties of electrodeposited Ni–Co alloy coatings due to saccharin additive

NiCo alloy coatings were galvanostatically electrodeposited at room temperature from sulfate bath using saccharin (0 to 12gL−1) as an additive agent. These alloy coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic absorption spectroscopy (AAS), contact angle, microhardness, Electrochemical impedance spectroscopy (EIS), salt immersion test and tribology techniques. The XRD study confirmed the formation of Ni–Co alloy with a face centered cubic (FCC) structure. Depending on saccharin addition, the Co content varied from 27 to 7at.%. The microhardness and corrosion resistance showed enhancement due to saccharin addition. Ni–Co alloy with a 12at.% Co content obtained from 10gL−1 saccharin addition showed reduced grain size (12nm) and hydrophobic surface (113°) with the highest corrosion and wear resistant values as compared to others. Such coating on medium carbon steel fasteners showed significant enhancement in corrosion protection during salt immersion test.

Aluminum electroplating on steel from a fused bromide electrolyte

A quaternary bromide bath (LiBr–KBr–CsBr–AlBr3) was used to electro-coat aluminum on steel substrates. The electrolyte was prepared by the addition of AlBr3 into the eutectic LiBr–KBr–CsBr melt. A smooth, thick, adherent and shiny aluminum coating could be obtained with 80wt.% AlBr3 in the ternary melt. The SEM photographs of the coated surfaces suggest the formation of thick and dense coatings with good aluminum coverage. Both salt immersion and open circuit potential measurement suggested that the coatings did display a good corrosion-resistance behavior. Annealing of the coated surfaces, prior to corrosion tests, suggested the robustness of the metallic aluminum coating in preventing the corrosion of the steel surfaces. Studies also indicated that the quaternary bromide plating bath can potentially provide a better aluminum coating on both ferrous and non-ferrous metals, including complex surfaces/geometries.

Evaluating the Air-Entraining Concrete Performance Decay Rule under Long-Term Salts Corrosion Using MATLAB Software

In the concrete salt-soaking durability test, the dynamic elastic modulus of concrete is more sensitive to the concrete damage than the mass, and can reflect the concrete durability better. In this paper,the relative dynamic elastic modulus of concrete is used as the evaluation index of concrete durability. Its attenuation law is made the multiple linear regression by using MATLAB software. The evaluation model and its applicable conditions of the relative dynamic elastic modulus of air-entraining concrete under the action of the long-term salt immersion are obtained, which can be used to evaluate and precast the durable degree of air-entraining concrete in the salt environment.

Waterborne Epoxy Nanocoatings Modified by Nanoemulsions and Nanoparticles

Electrically conductive coatings are required for static charge dissipation in power ground network. In the present investigation electrically conductive nanocoatings were prepared by the incorporation of graphite, nano-SiO2 concentrate, acrylic nanoemulsion and fluorocarbon emulsion onto the waterborne epoxy polymer. The nanosize distribution of nano-SiO2 concentrate and nanoemulsion was characterized with laser diffraction analyzer and scanning electron microscopy (SEM). From the results of SEM image, the graphite particles were well distributed in conductive coating. The corrosion resistance and thermal stability of nanocoatings were comparatively studied by SEM and thermogravimetry (TG). The corrosion-inhibiting properties of the conductive nanocoatings were investigated by salt immersion test. The measurements of contact angle, bonding strength and heat-freeze charge demonstrated that 1.5–2.0 wt% nanoparticles improve the resistance to pollution, adherence and resistance to heat-freeze charge of conductive nanocoatings. The measured results of surface electric resistance of nanocoatings demonstrated that a small amount of nano-SiO2 particles could enhance the conductivity in the corrosive environment.