Release Of Aluminum Research Articles

The corrosion of aluminium alloy and release of intermetallic particles in nuclear reactor emergency core coolant: Implications for clogging of sump strainers

Abstract Clogging of sump strainers that filter the recirculation water in containment after a loss-of-coolant accident (LOCA) seriously impedes the continued cooling of nuclear reactor cores. In experiments examining the corrosion of aluminium alloy 6061, a common material in containment equipment, in borated solutions simulating the water chemistry of sump water after a LOCA, we found that Fe-bearing intermetallic particles, which were initially buried in the Al matrix, were progressively exposed as corrosion continued. Their cathodic nature vis-a-vis the Al matrix provoked continuous trenching around them until they were finally released into the test solution. Such particles released from Al alloy components in a reactor containment after a LOCA will be transported to the sump entrance with the recirculation flow and trapped by the debris bed that typically forms on the strainer surface, potentially aggravating strainer clogging. These Fe-bearing intermetallic particles, many of which had a rod or thin strip-like geometry, were identified to be mainly the cubic phase αc-Al(Fe,Mn)Si with an average size of about 2.15 μm; 11.5 g of particles with a volume of about 3.2 cm3 would be released with the dissolution of every 1 kg 6061 aluminium alloy.

Aluminum alloy corrosion in boron‐containing alkaline solutions

Corrosion of aluminum alloy 1100 exposed to the boron‐containing alkaline solutions was studied. Test solutions were in the pH 7.5–8.2 range at 25, 55, and 85 °C. Both post‐tested aluminum alloy and alkaline solution were analyzed to characterize corrosion. The results indicate that the oxide layer at 25 and 55 °C was gibbsite Al(OH)3, and at 85 °C was boehmite AlOOH. Colloid deposits were found on the sample surface at 85 °C because of the phase transition of dissolved corrosion products with aging. The physics‐based aluminum release model for each test condition was developed to simulate the progression of aluminum concentration in the solution. Based on the model, the mass transfer coefficient of each test condition can be obtained.

Aluminium release by water-rock interaction during hydraulic tests in a siliciclastic aquifer in Berlin (Germany)

Two hydraulic tests of a Triassic sandstone aquifer were performed to determine hydraulic and geochemical parameters of the reservoir formation. Samples collected during all tests showed neutral and constant pH-value of about 7.5. During the initial step rate test, the aluminium concentration of the water remained below 0.005 mM, but it increased significantly during the production phase of the following single well push-pull test to 4.8 mM. Drill cuttings of the well, collected at reservoir depth (Exter Fm. and the overlaying Tertiary sand), were additionally characterized and used for leaching experiments. These experiments evidenced a strong release of aluminium from the Tertiary, pyrite containing sand, indicating processes of pyrite oxidation being responsible for aluminium mobilization.

Electrochemical Behavior of Hot Treated Ti-12Mo-8Nb Alloy

Several beta titanium alloys are finding ever-increasing applications in biomaterials, due to the combination of its mechanical properties including low elasticity modulus, high strength, fatigue resistance and good ductility with improved corrosion resistance. In this regard, a new beta titanium Ti-12Mo-8Nb alloy was developed as an alternative to the traditional alloy Ti-6Al-4V. Studies have shown that the release of vanadium (V) and aluminum (Al) ions in the human body may cause cytotoxic effects and neurological disorders, respectively. Additionally, this new alloy presented higher ratio of hardness to elastic modulus, as compared to the commercial Ti-6Al-4V alloy. This paper presents the electrochemical behavior and mechanical properties of the Ti-12Mo-8Nb heat treated at 950 oC for 1h under high vacuum and then water quenched. The electrochemical behavior was carried through potentiodynamic polarization curves using Ringer's solution to simulate the body fluid. The Ti-12Mo-8Nb alloy presented a microstructure consisting of β phase with good mechanical properties and a passive layer was formed.

Release of aluminium and thallium ions from uncoated food contact materials made of aluminium alloys into food and food simulant.

In order to investigate the release of aluminium ions from food contact materials, three different types of uncoated aluminium menu trays for single use were tested with the foodstuffs sauerkraut juice, apple sauce and tomato puree, as well as with the food simulants 5 g/L citric acid solution and artificial tap water. To mimic a consumer relevant exposure scenario, the aluminium trays were studied using time and temperature gradients according to the Cook & Chill method, also taking into account storage time at elevated temperatures during the delivery period. The release of aluminium was found to exceed the specific release limit (SRL) of 5 mg aluminium per kilogram of food specified by the Council of Europe by up to six times. Furthermore, a release of thallium was also detected unexpectedly.Kinetic studies showed a comparable behaviour in the release of aluminium, manganese and vanadium as components of the aluminium alloy itself. In contrast, thallium could be identified as a surface contaminant or impurity because of an entirely different kinetic curve. Kinetic studies also allowed activation energy calculations.Additional camping saucepans were tested as an article for repeated use. In three subsequent release experiments with citric acid (5 g/L), artificial tap water and tomato puree as benchmark foodstuffs, the results were comparable to those of the uncoated wrought alloy aluminium trays.

Fate of aluminium released by sacrificial anodes – Contamination of marine sediments by environmentally available compounds

To protect their steel structures from corrosion by cathodic protection, many harbours use aluminium sacrificial anodes, which induces aluminium release and potential contamination of the surrounding waters and sediments. To study the impact on Al mobility, a natural marine sediment was artificially contaminated with aluminium from different sources: sulphate or chloride salts, or sacrificial anodes. To estimate Al mobility in sediments, single (HCl) and sequential (F6) extractions were performed; they highlighted that aluminium is poorly mobile in natural sediment (HCl-leachable: 2% and F6-leachable: 9%). Contamination by aluminium salts inhibits HCl-leachability (≤2%), whereas the Al F6-leachability is intensified up to 18%, suggesting that the additional aluminium is scavenged in a mobile fraction that HCl is not able to solubilise. In case of aluminium anode contamination, sediments present surging Al HCl-leachable (15%) and F6-leachable (32%) fractions, which are related to aluminium mineralogical speciation. Indeed, contrary to the Al naturally present or introduced by salts, Al released by anodes is partly bound to the acid-soluble fraction, probably because of the integration of the released Al into the calcareous deposit produced at the anodes surfaces that finally comes away and gets mixed up with the sediment. The presence of aluminium in the acid-soluble fraction of sediments could have an important environmental impact as this fraction is easily available. Indeed, Al scavenged in the acid-soluble fraction of sediments participates in enhancing Al lability near the sacrificial anodes and may affect the surrounding ecosystems.

Tribocorrosion behavior of TiO2/Al2O3 nanolaminate, Al2O3, and TiO2 thin films produced by atomic layer deposition

Metallic materials are the most widely used for orthopedic applications and, their corrosion resistance is one of the main prerequisites for avoiding impairment of the material properties due to degradation. Ti-6Al-4V is one of the main medical titanium alloys. However, for permanent implant applications, this alloy may cause toxic effect due to release of vanadium and aluminum. Nanolaminates of alternatively ordered thin films of transition metal oxides with nanoscale thickness are known to have distinct properties of a single layer film. Atomic layer deposition (ALD) is a promising method for fabrication of thin sealing coatings for corrosion protection. These films can also be used as in vivo sensors to antedate the detection of diseases such as cancer, to inform the best treatments, and to understand the response to therapies. The ideal in vivo sensor should be non-toxic, biocompatible, stable, and very sensitive. In this work, TiO2/Al2O3 nanolaminate, Al2O3 and TiO2 thin films were deposited on Ti-6Al-4V substrates by using ALD and their structure, adhesion and tribocorrosion properties were analyzed. The tribocorrosion tests were performed in Ringer's solution. The coatings showed to protect the sample surface evidenced by the increase on the OCP both in static mode and in dynamic mode. The TiO2/Al2O3 nanolaminates presented lower friction coefficient.

Evaluation of Ion Release from Four Dental Sealants.

The purpose of this study was to determine the ion release from four commercially available pit-and-fissure sealants [3M Clinpro, 3M Concise™, BeautiSealant (BS), and GI FX-II)]. With each brand, 18 specimens were prepared. Their fluoride release in de-ionized water was measured by fluoride electrode, while the release of silicate (Si), aluminum (Al), sodium (Na), calcium (Ca), strontium (Sr), and phosphorus (P) was measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES) on days 1, 3, 7, 14, 21, and 28. The result showed that fluoride was not released from 3M Concise™. GI FX-II displayed the largest fluoride release, which, however, dropped rapidly on day 3. 3M Clinpro exhibited less fluoride release than GI FX-II and BS did. At any time during the 28-day experimental period, GI FX-II released more Na than the other sealants (P<0.001). BS ranked the second in Na release, and a small amount of Na ions was released from the 3M Clinpro and 3M Concise™ samples. Al ions were only detected from BS and GI FX-II, but not from the 3M Clinpro and 3M Concise™. Additionally GI FX-II had the largest Si release among the four brands at any time during the experimental period (P<0.001). Ca ions were detected from 3M Clinpro and 3M Concise™, but not from GI FX-II. BS released more Sr than the other sealants at any time during the experimental period (P<0.001). All the samples released similar amounts of P continuously during these 28 days. In conclusion, based on the type and the amount of ion release, BS is the best pit-and-fissure sealant among the four brands.

Development of Alkoxide Precursors-Based Hybrid Coatings on Ti-6Al-4V Alloy for Biomedical Applications: Influence of pH of Sol

The Ti-6Al-4V alloy, widely used in biomedical applications, is associated with cytotoxic effects due to the release of aluminum and vanadium ions in the human body. One of the most effective ways to control the release of cytotoxic ions is through anti-corrosive coatings. Among them, the alkoxysilanes stand out for their good barrier properties and the absence of toxicity. Aiming to improve the clinical success rate of metallic implants, this study sets out to evaluate the influence of the pH of the sol on the physico-chemical, morphological, mechanical and electrochemical characteristics of hybrid films based on 3-(trimethoxysilylpropyl)methacrylate (MAP) and tetraethoxysilane (TEOS) applied to Ti-6Al-4V. The film was prepared by using the sol–gel method for pH values of 3, 4, and 5. The results indicated that maintaining the pH of the sol at 4 favors the hydrolysis rate of alkoxide precursors, which results in a uniform, dense and adherent film with excellent anti-corrosion performance.

Use of high metal-containing biogas digestates in cereal production – Mobility of chromium and aluminium

Biogas digestate use as organic fertilizer has been widely promoted in recent years as a part of the global agenda on recycling waste and new sustainable energy production. Although many studies have confirmed positive effects of digestates on soil fertility, there is still lack of information on the potential adverse effects of digestates on natural soil heavy metal content, metal leaching and leaching of other pollutants. We have investigated the release of aluminium (Al) and chromium (Cr) from different soils treated with commercial digestates high in mentioned potentially problematic metals in a field experiment, while a greenhouse and a laboratory column experiment were used to address mobility of these metals in two other scenarios. Results obtained from the field experiment showed an increase in total concentrations for both investigated metals on plots treated with digestates as well as a significant increase of water-soluble Al concentrations. Factors that were found to be mostly affecting the metal mobility were dissolved organic carbon (DOC), pH and type of soil. Metal binding and free metal concentrations were modelled using the WHAM 7.0 software. Results indicated that the use of digestates with high metal content are comparable to use of animal manure with respect to metal leaching. Data obtained through chemical modelling for the samples from the field experiment suggested that an environmental risk from higher metal mobility has to be considered for Al. In the greenhouse experiment, measured concentrations of leached Cr at the end of the growing season were low for all treatments, while the concentration of leached Al from digestates was higher. The high irrigation column leaching experiment showed an increased leaching rate of Cr with addition of digestates.

In-situ formation, anti-corrosion and hardness values of Ti-6Al-4V biomaterial with niobium via laser deposition

Ti-6Al-4V alloy biomaterials have low hardness, wear resistance, high corrosion rate and toxicity as results of release of aluminium and vanadium ions that led to the premature failure of the implant. In order to overcome some of these problems, laser cladding of Ti6Al4V alloy with Niobium was conducted. Three laser parameters (laser power, beam diameter and laser scan speed) were used to ascertain the proper operating condition for this laser process. Rofin Nd: yag laser was used in the laser cladding. The electrochemical study was conducted using Hank's buffered salt solution an environment similar to the human body. The optimum improvement in corrosion resistance resulted to 81.79% when compared with substrate. It has been established that operating parameter for laser cladding of Nb on Ti6Al4V were obtained at: laser power (1,000 W), beam diameter (1 mm) and scan speed (0.3 m/min).

Study of a tropical soil in order to use it to retain aluminum, iron, manganese and fluoride from acid mine drainage

The Ore Treatment Unit (UTM-Caldas), in the city of Caldas, Minas Gerais, Brazil, nowadays in decommissioning stage, was the first uranium extraction mine in Brazil. Several negative environmental impacts in the area have occurred, because of mining, treatment and beneficiation processes. Waste rock pile 4 (WRP-4) generates acid mine drainage (AMD), which is discharged in the Nestor Figueiredo retention pond (NFP). However, leakage of acid water by the NFP dam foundation has been constantly observed. Therefore, this research aimed to investigate a typical tropical soil, in order to use it as mineral liner for the NFP to minimize the leakage of acid water through the dam foundation and to retain predominant chemical species. Geotechnical, chemical and mineralogical tests were performed to characterize the soil and a column test was carried out using the acid mine drainage as contaminant, which contained aluminum (Al), manganese (Mn), iron (Fe) and fluoride (F−). The soil presented micro aggregation, acid pH, and low values of organic matter content and cation exchange capacity, which are characteristics of highly weathered soils. Diffusion was the predominant transport mechanism in the column test. Effluent solutions with pH less than 6.0 indicated the formation of insoluble Al-F complexes in the soil and desorption of iron and manganese at concentrations above those allowed by the Brazilian legislation. At pH greater than 6.0, the desorption of iron and manganese and release of aluminum and fluoride in the free form occurred, with concentrations also higher than the allowed by the Brazilian legislation.

Aluminium Leaching by Heterotrophic Microorganism Aspergillus niger: An Acidic Leaching?

Bioleaching of aluminium mineral boehmite by filamentous fungus Aspergillus niger was compared to chemical leaching by citric, oxalic and hydrochloric acids to evaluate the significance of A. niger’s metabolites on aluminium mobilization from this natural component of the aluminium ore. Our results highlighted that leaching efficiency of hydrochloric acid at pH 2 was 2.7 times lower compared to fungal bioleaching efficiency. When the organic acids were compared, oxalic acid was a stronger aluminium leaching agent than citric acid. The results suggest that fungal metabolites significantly promoted the release of aluminium and that their acidic properties, despite being useful, were not the most critical factor in the bioleaching of aluminium.

Coagulation effectiveness of graphene oxide for the removal of turbidity from raw surface water

This study presents the performance of graphene oxide (GO) as a coagulant in turbidity removal from naturally and artificially turbid raw surface water. GO is considered an excellent alternative to alum, the more common coagulant used in water treatment processes, to reduce the environmental release of aluminum. Effects of GO dosage, pH, and temperature on its coagulation ability were studied to determine the ideal turbidity removal conditions. The turbidity removal was ≥95% for all levels of turbid raw surface water (20, 100, and 200 NTU) at optimum conditions. The role of alkalinity in inducing turbidity removal by GO coagulation was much more pronounced upon using raw surface water samples compared with that using artificially turbid deionized water samples. Moreover, GO demonstrated high-performance removal of biological contaminants such as algae, heterotrophic bacteria, and fecal coliform bacteria by 99.0%, 98.8% and 96.0%, respectively, at a dosage of 40 mg/L. Concerning the possible environmental release of GO into the treated water following filtration process, there was no residual GO in a wide range of pH values. The outcomes of the study highlight the excellent coagulation performance of GO for the removal of turbidity and biological contaminants from raw surface water.

Migration of aluminum from food contact materials to food\u2014a health risk for consumers? Part I of III: exposure to aluminum, release of aluminum, tolerable weekly intake (TWI), toxicological effects of aluminum, study design, and methods

BackgroundIn spite of the prevalence of aluminum in nature, no organism has been found to date which requires this element for its biological functions. The possible health risks to human beings resulting from uptake of aluminum include detrimental effects to the hemopoietic system, the nervous system and bones. Aluminum is used in many fields and occurs in numerous foodstuffs. Food contact materials containing aluminum represent an anthropogenic source of dietary aluminum.ResultsAs a result of their frequent use in private households a study was undertaken to detect migration of this metal to foodstuffs from drink containers, coffee pots, grill pans, and camping cookware made of aluminum.ConclusionsAn estimate of the health risk to consumers is calculated, based on the tolerable weekly intake (TWI) specified by the European Food Safety Authority of 1 mg/kg body weight for all groups of people. In some instances the TWI is significantly exceeded, dependent upon the food contact material and the food itself.

Effect of the Al/O ratio on the Al reaction of aluminized RDX-based explosives

Aluminum (Al) powders are used in composite explosives as a typical reducing agent for improving explosion performance. To understand energy release of aluminum in aluminized RDX-based explosives, a series of thermal measurements and underwater explosion (UNDEX) experiments were conducted. Lithium fluoride (LiF) was added in RDX-based explosives, as a replacement of aluminum, and used in constant temperature calorimeter experiments and UNDEXs. The influence of aluminum powder on explosion heat () was measured. A rich supply of data about aluminum energy release rate was gained. There are other oxides (CO, CO, and HO) in detonation products besides alumina when the content of RDX is maintained at the same levels. Aluminum cannot fully combine with oxygen in the detonation products. To study the relationship between the explosive formulation and energy release, pressure and impulse signals in underwater experiments were recorded and analyzed after charges were initiated underwater. The shock wave energy (), bubble energy (), and total energy () monotony increase with the Al/O ratio, while the growth rates of the shock wave energy, bubble energy, and total energy become slow.

Experimental Study of Aqueous Chemical Trisodium Phosphate-Buffered Environment Under Post-LOCA Conditions With Head Loss Measurements

An integrated chemical effects test (ICET) was designed and executed to investigate the corrosion of materials in a hypothetical post-loss of coolant accident (LOCA) environment for pressurized water reactors (PWRs) and the resulting effects on the measured head loss in three vertical columns through multiconstituents debris beds. The head loss columns were isolated approximately after 72 h, as the measured head loss in all three columns approached or surpassed the maximum limit of the differential pressure (DP) cells. Additional bench scale tests were carried out to investigate the cause of high head loss in the three columns. Combination of epoxy agglomeration and adhesion to fiber resulted in subsequent blockage of the flow through the debris bed with no chemical precipitation was concluded as the most reasonable cause of high head loss observed in the test. The test continued thereafter up to 30 days as an integrated chemical effects test using the corrosion tank only. The results presented in this article demonstrate trends for zinc, aluminum, and calcium release that are consistent with separate bench scale testing and previous integrated tests conducted under trisodium phosphate (TSP)-buffered post-LOCA environmental conditions. In general, the total and filtered samples showed almost identical concentration of all metals (Al, Ca, Si, and Mg) except zinc which clearly indicate that no precipitation occurred. The release rate and maximum concentrations of the released materials were slightly different than the separate effect testing as a result of different experimental conditions (temperature, surface area-to-water volume ratio) and/or the presence of other metals and chemicals in the integrated test.

Synthesis and characterization of nanoamendment for effective remediation of soil acidity

Summary Industrialization and climate change had increased soil acidity which deteriorated the soil health and reduced crop productivity through release of toxic concentration hydrogen and aluminium, manganese and iron. Acid soils (pH < 5.5) are extensively found in region of high rainfall, temperature and hilly region. Liming of acid soils the changes (pH 5.5 to 6.5), rectifies adverse effects and also improves the soil fertility. But large quantity of lime used (7.2 tons per acre). In order to optimize the rate of lime nano technological approach was used. Naturally available micro-size conventional calcium carbonate particles were used for synthesis of nano crystals through physical method of top down approach, using high energy ball milling (HEBM) with different hours and encapsulated with non-ionic surfactant (1% chitosan). It produced uniform nano sized particles (nano-lime), which were characterised using particle size analyser (approximately 115 – 120 nm), zeta potential (-50 mV), powder X-ray diffraction (d spacing 3.13). It confirmed that presence of Ca and Mg with Raman Shifts (713, 1086 cm -1 ) and Fourier transform infrared spectroscopy (844.7 cm -1 ). Shape and structure was observed through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Synthesized of calcium carbonate nano crystalline particles were environment friendly. Reduced particle size and increased surface area where offered an opportunity for reclamation of soil acidity as an amendment and can be scaled up for agricultural production.

Corrosion of silicon nitride in high temperature alkaline solutions

The corrosion of silicon nitride (Si3N4) in alkaline solutions was studied at temperatures from 60 to 300 °C. Si3N4 experienced significant corrosion above 100 °C. The release rates of silicon and nitrogen follow zero order reaction kinetics and increase with increasing temperature. The molar ratio of dissolved silicon and nitrogen species in the high temperature solutions is the same as that in the solid phase (congruent dissolution). The activation energy for silicon and nitrogen release rates is 75 kJ/mol which agrees well with that of silica dissolution. At 300 °C, the release of aluminum is observed and follows first order reaction kinetics while other minor constituents including Ti and Y are highly enriched on the corrosion films due to the low solubility of their oxides.

Corrosion and solubility in a TSP-buffered chemical environment following a loss of coolant accident: Part 4 – Integrated chemical effects testing

This paper presents the results of an integrated chemical effects experiment executed under conditions representative of the containment pool following a postulated loss of coolant accident (LOCA) at the Vogtle nuclear power plant, operated by the Southern Nuclear Operating Company (SNOC). This test was conducted for closure of a series of bench scale experiments conducted to investigate the effect of the presence of trisodium phosphate (TSP) on the corrosion and release of aluminum (Howe et al., 2015) and zinc (Pease et al., 2015) from metallic surfaces, and calcium from NUKON fiberglass insulation (Olson et al., 2015) . The integrated test was performed in the Corrosion/Chemical Head Loss Experimental (CHLE) facility with representative amounts of zinc, aluminum, carbon steel, copper, NUKON fiberglass, and latent debris. The test was conducted using borated TSP-buffered solution under a post-LOCA prototypical temperature profile lasting for 30 days.The results presented in this article demonstrate trends for zinc, aluminum, and calcium release that are consistent with separate bench scale testing and previous integrated tests under TSP conditions. The release rate and maximum concentrations of the released materials were slightly different than the separate effect testing as a result of different experimental conditions (temperature, surface area-to-water volume ratio) and/or the presence of other metals and chemicals in the integrated test. Samples of metal coupons and fiberglass were selected for analysis using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS).