Inhibition Effects of a Synthesized Novel 4-Aminoantipyrine Derivative on the Corrosion of Mild Steel in Hydrochloric Acid Solution together with Quantum Chemical Studies

Science.gov (United States)

Junaedi, Sutiana; Al-Amiery, Ahmed A.; Kadihum, Abdulhadi; Kadhum, Abdul Amir H.; Mohamad, Abu Bakar

2013-01-01

1,5-Dimethyl-4-((2-methylbenzylidene)amino)-2-phenyl-1H-pyrazol-3(2H)-one (DMPO) was synthesized to be evaluated as a corrosion inhibitor. The corrosion inhibitory effects of DMPO on mild steel in 1.0 M HCl were investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, open circuit potential (OCP) and electrochemical frequency modulation (EFM). The results showed that DMPO inhibited mild steel corrosion in acid solution and indicated that the inhibition efficiency increased with increasing inhibitor concentration. Changes in the impedance parameters suggested an adsorption of DMPO onto the mild steel surface, leading to the formation of protective films. The novel synthesized corrosion inhibitor was characterized using UV-Vis, FT-IR and NMR spectral analyses. Electronic properties such as highest occupied molecular orbital energy, lowest unoccupied molecular orbital energy (EHOMO and ELUMO, respectively) and dipole moment (μ) were calculated and discussed. The results showed that the corrosion inhibition efficiency increased with an increase in the EHOMO values but with a decrease in the ELUMO value. PMID:23736696

The effects of corrosion conditions and cold work on the nodular corrosion of zircaloy-4

International Nuclear Information System (INIS)

You, Gil Sung

1992-02-01

The nodular corrosion of Zircaloy-4 was investigated on the effects of corrosion conditions and cold work. Variation of steam pressures, heat-up environments and prefilms were considered and cold work effects were also studied. The corrosion rate of Zircaloy-4 was dependent on pressure between 1 and 100 atm and it followed the cubic law as W=16.85 x P 0.31 for plate specimens and W=12.69 x P 0.27 for tube specimens, where W is weight gain (mg/dm 2 ) and P is the steam pressure (atm). The environment variation in autoclave during heat-up period did not affect the early stage of nodular corrosion. The prefilm, which was formed at 500 .deg. C under 1 atm steam for 4 hours, restrained the formation of the initial small nodules. The oxide film formed under 1 atm steam showed no difference of electrical resistivity from the oxides formed under 100 atm steam pressure. Cold work specimens showed the higher resistivity against nodular corrosion than as-received specimens. The corrosion resistance arising from cold work seems to be due to the texture changes by the cold work. The results showed that cold work can affect the later stage of uniform corrosion and the early stage of nodular corrosion, namely, the nodule initiation stage

Inhibitory effect of konjac glucomanan on pitting corrosion of AA5052 aluminium alloy in NaCl solution.

Science.gov (United States)

Zhang, Kegui; Yang, Wenzhong; Xu, Bin; Chen, Yun; Yin, Xiaoshuang; Liu, Ying; Zuo, Huanzhen

2018-05-01

A natural carbohydrate polymer, konjac glucomanan, has been extracted from commercial product and studied as a green corrosion inhibitor for AA5052 aluminium alloy in 3.5 wt% NaCl solution by high-performance gel permeation chromatography (GPC), thermo gravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectra, electrochemical measurement and surface characterization techniques. The results of GPC measurements suggest the weight-average molecular weight and the number-average molecular weight of KGM with 98.2% purity are 1.61 × 10 5  g/mol and 1.54 × 10 5  g/mol, respectively. Potentiodynamic polarization curves show konjac glucomanan behaves as a mixed-type inhibitor with dominant anodic effect and that its maximum efficiency at 200 ppm is 94%. Electrochemical impedance spectroscopy (EIS) studies reveal the resistance of oxide film is approximately two orders of magnitude greater than the resistance of adsorbed inhibitor layer and that they both increase with KGM concentration. Moreover, in-situ electrochemical noise (EN) detection demonstrates that the growth and propagation stages of the pitting corrosion germinating on metal surface are blocked by polysaccharide additive, which is confirmed by the surface analysis of aluminium alloy using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and Raman spectroscopy. At last, it is found that the addition of KGM makes it harder for water droplet containing NaCl to wet the metallic substrate. Copyright © 2018 Elsevier Inc. All rights reserved.

Effective flow-accelerated corrosion programs in nuclear facilities

International Nuclear Information System (INIS)

Esselman, Thomas C.; McBrine, William J.

2004-01-01

Piping Flow-Accelerated Corrosion Programs in nuclear power generation facilities are classically comprised of the selection of inspection locations with the assistance of a predictive methodology such as the Electric Power Research Institute computer codes CHECMATE or CHECWORKS, performing inspections, conducting structural evaluations on the inspected components, and implementing the appropriate sample expansion and corrective actions. Performing such a sequence of steps can be effective in identifying thinned components and implementing appropriate short term and long term actions necessary to resolve flow-accelerated corrosion related problems. A maximally effective flow-accelerated corrosion (FAC) program requires an understanding of many programmatic details. These include the procedural control of the program, effective use of historical information, managing the activities performed during a limited duration outage, allocating resources based on risk allocation, having an acute awareness of how the plant is operated, investigating components removed from the plant, and several others. This paper will describe such details and methods that will lead to a flow-accelerated corrosion program that effectively minimizes the risk of failure due to flow-accelerated corrosion and provide full and complete documentation of the program. (author)

Antimicrobial action and anti-corrosion effect against sulfate reducing bacteria by lemongrass (Cymbopogon citratus) essential oil and its major component, the citral.

Science.gov (United States)

Korenblum, Elisa; Regina de Vasconcelos Goulart, Fátima; de Almeida Rodrigues, Igor; Abreu, Fernanda; Lins, Ulysses; Alves, Péricles Barreto; Blank, Arie Fitzgerald; Valoni, Erika; Sebastián, Gina V; Alviano, Daniela Sales; Alviano, Celuta Sales; Seldin, Lucy

2013-08-10

The anti-corrosion effect and the antimicrobial activity of lemongrass essential oil (LEO) against the planktonic and sessile growth of a sulfate reducing bacterium (SRB) were evaluated. Minimum inhibitory concentration (MIC) of LEO and its major component, the citral, was 0.17 mg ml-1. In addition, both LEO and citral showed an immediate killing effect against SRB in liquid medium, suggesting that citral is responsible for the antimicrobial activity of LEO against SRB. Transmission electron microscopy revealed that the MIC of LEO caused discernible cell membrane alterations and formed electron-dense inclusions. Neither biofilm formation nor corrosion was observed on carbon steel coupons after LEO treatment. LEO was effective for the control of the planktonic and sessile SRB growth and for the protection of carbon steel coupons against biocorrosion. The application of LEO as a potential biocide for SRB growth control in petroleum reservoirs and, consequently, for souring prevention, and/or as a coating protection against biocorrosion is of great interest for the petroleum industries.

Assessing Level and Effectiveness of Corrosion Education in the UAE

Directory of Open Access Journals (Sweden)

Hwee Ling Lim

2012-01-01

Full Text Available The consequences of corrosion can be minimized by an engineering workforce well trained in corrosion fundamentals and management. Since the United Arab Emirates incurs the second highest cost of corrosion after Saudi Arabia, this paper examined the quality of corrosion education in the UAE. Surveys with academia and industry respondents showed that dedicated corrosion courses and engineering courses that integrated corrosion into the curricula were available in UAE universities, but graduates had insufficient knowledge of corrosion engineering and superficial understanding of corrosion in real-life design contexts. The effectiveness of corrosion education is determined by both competence in corrosion knowledge/skills and availability of resources (faculty and research. Though most departments would not hire new corrosion-specialist faculty, department research efforts and industry partnerships in corrosion research were present. The paper concluded with recommendations for improving knowledge and skills of future engineers in corrosion and enhancing corrosion instruction to better meet industry needs.

Corrosion and corrosion control

International Nuclear Information System (INIS)

Khanna, A.S.; Totlani, M.K.

1995-01-01

Corrosion has always been associated with structures, plants, installations and equipment exposed to aggressive environments. It effects economy, safety and product reliability. Monitoring of component corrosion has thus become an essential requirement for the plant health and safety. Protection methods such as appropriate coatings, cathodic protection and use of inhibitors have become essential design parameters. High temperature corrosion, especially hot corrosion, is still a difficult concept to accommodate in corrosion allowance; there is a lack of harmonized system of performance testing of materials at high temperatures. In order to discuss and deliberate on these aspects, National Association for Corrosion Engineers International organised a National Conference on Corrosion and its Control in Bombay during November 28-30, 1995. This volume contains papers presented at the symposium. Paper relevant to INIS is indexed separately. refs., figs., tabs

INHIBITORY EFFECT OF SALVIA SCLAREA

African Journals Online (AJOL)

rakoe

2011-11-02

Nov 2, 2011 ... This study demonstrated anti-herpes simplex virus (HSV) activity of lavender, sage and ... Green monkey kidney cells were protected from HSV-2 infection by ... The highest inhibitory effect against HSV-2 was observed after treatment ..... some nuclear-replicating eukaryotic DNA viruses with large genomes.

Structural Effects of Reinforced Concrete Beam Due to Corrosion

Science.gov (United States)

Noh, Hamidun Mohd; Idris, Nur'ain; Noor, Nurazuwa Md; Sarpin, Norliana; Zainal, Rozlin; Kasim, Narimah

2018-03-01

Corrosion of steel in reinforced concrete is one of the main issues among construction stakeholders. The main consequences of steel corrosion include loss of cross section of steel area, generation of expansive pressure which caused cracking of concrete, spalling and delaminating of the concrete cover. Thus, it reduces the bond strength between the steel reinforcing bar and concrete, and deteriorating the strength of the structure. The objective of this study is to investigate the structural effects of corrosion damage on the performance of reinforced concrete beam. A series of corroded reinforced concrete beam with a corrosion rate of 0%, 20% and 40% of rebar corrosion is used in parametric study to assess the influence of different level of corrosion rate to the structural performance. As a result, the used of interface element in the finite element modelling predicted the worst case of corrosion analysis since cracks is induced and generate at this surface. On the other hand, a positive linear relationship was sketched between the increase of expansive pressure and the corrosion rate. Meanwhile, the gradient of the graph is decreased with the increase of steel bar diameter. Furthermore, the analysis shows that there is a significant effect on the load bearing capacity of the structure where the higher corrosion rate generates a higher stress concentration at the mid span of the beam. This study could predict the residual strength of reinforced concrete beam under the corrosion using the finite element analysis. The experimental validation is needed on the next stage to investigate the quantitative relation between the corrosion rate and its influence on the mechanical properties.

Inhibitory Effect of Corn Silk on Skin Pigmentation

OpenAIRE

Sang Yoon Choi; Yeonmi Lee; Sung Soo Kim; Hyun Min Ju; Ji Hwoon Baek; Chul-Soo Park; Dong-Hyuk Lee

2014-01-01

In this study, the inhibitory effect of corn silk on melanin production was evaluated. This study was performed to investigate the inhibitory effect of corn silk on melanin production in Melan-A cells by measuring melanin production and protein expression. The corn silk extract applied on Melan-A cells at a concentration of 100 ppm decreased melanin production by 37.2% without cytotoxicity. This was a better result than arbutin, a positive whitening agent, which exhibited a 26.8% melanin prod...

Corrosion and inhibition of stainless steel pitting corrosion in alkaline medium and the effect of Cl- and Br- anions

International Nuclear Information System (INIS)

Refaey, S.A.M.; Taha, F.; El-Malak, A.M. Abd

2005-01-01

The effect of carbonate anion on the pitting corrosion and inhibition behavior of stainless steel samples (304L SS and 316L SS) has been studied using potentiodynamic and scanning electron microscope (SEM) techniques. The effect of concentration of CO 3 2- ions, pH, potential scanning rate and the composition of stainless steel are discussed. Additions of Cl - and Br - ions into the carbonate solution increase the anodic dissolution of stainless steel and decrease its pitting corrosion resistance. The effect of CO 3 2- anion on the inhibition of chloride and bromide pitting corrosion of the two stainless steel types has been studied also. Pitting corrosion decrease with the increasing of sodium carbonate concentration, i.e. increases the resistance of stainless steels towards the chloride and bromide pitting corrosion. This inhibition effect argued to formation of [Fe,Cr]CO 3 film caused by preferential adsorption of the CO 3 2- ion, leading to instantaneous repair of weak sites for pit nucleation

Fatty Amides from Crude Rice Bran Oil as Green Corrosion Inhibitors

Directory of Open Access Journals (Sweden)

E. Reyes-Dorantes

2017-01-01

Full Text Available Due to its high oil content, this research proposes the use of an agroindustrial byproduct (rice bran as a sustainable option for the synthesis of corrosion inhibitors. From the crude rice bran oil, the synthesis of fatty amide-type corrosion inhibitors was carried out. The corrosion inhibitory capacity of the fatty amides was evaluated on an API X-70 steel using electrochemical techniques such as real-time corrosion monitoring and potentiodynamic polarization curves. As a corrosive medium, a CO2-saturated solution (3.5% NaCl was used at three temperatures (30, 50, and 70°C and different concentrations of inhibitor (0, 5, 10, 25, 50, and 100 ppm. The results demonstrate that the sustainable use of agroindustrial byproducts is a good alternative to the synthesis of environmentally friendly inhibitors with high corrosion inhibition efficiencies.

Lactoferricin B-derived peptides with inhibitory effects on ECE-dependent vasoconstriction.

Science.gov (United States)

Fernández-Musoles, Ricardo; López-Díez, José Javier; Torregrosa, Germán; Vallés, Salvador; Alborch, Enrique; Manzanares, Paloma; Salom, Juan B

2010-10-01

Endothelin-converting enzyme (ECE), a key peptidase in the endothelin (ET) system, cleaves inactive big ET-1 to produce active ET-1, which binds to ET(A) receptors to exert its vasoconstrictor and pressor effects. ECE inhibition could be beneficial in the treatment of hypertension. In this study, a set of eight lactoferricin B (LfcinB)-derived peptides, previously characterized in our laboratory as angiotensin-converting enzyme (ACE) inhibitory peptides, was examined for their inhibitory effects on ECE. In vitro inhibitory effects on ECE activity were assessed using both the synthetic fluorogenic peptide substrate V (FPS V) and the natural substrate big ET-1. To study vasoactive effects, an ex vivo functional assay was developed using isolated rabbit carotid artery segments. With FPS V, only four LfcinB-derived peptides induced inhibition of ECE activity, whereas the eight peptides showed ECE inhibitory effects with big ET-1 as substrate. Regarding the ex vivo assays, six LfcinB-derived peptides showed inhibition of big ET-1-induced, ECE-dependent vasoconstriction. A positive correlation between the inhibitory effects of LfcinB-derived peptides on ECE activity when using big ET-1 and the inhibitory effects on ECE-dependent vasoconstriction was shown. ECE-independent vasoconstriction induced by ET-1 was not affected, thus discarding effects of LfcinB-derived peptides on ET(A) receptors or intracellular signal transduction mechanisms. In conclusion, a combined in vitro and ex vivo method to assess the effects of potentially antihypertensive peptides on the ET system has been developed and applied to show the inhibitory effects on ECE-dependent vasoconstriction of six LfcinB-derived peptides, five of which were dual vasopeptidase (ACE/ECE) inhibitors. Copyright © 2010 Elsevier Inc. All rights reserved.

Degree of synchronization modulated by inhibitory neurons in clustered excitatory-inhibitory recurrent networks

Science.gov (United States)

Li, Huiyan; Sun, Xiaojuan; Xiao, Jinghua

2018-01-01

An excitatory-inhibitory recurrent neuronal network is established to numerically study the effect of inhibitory neurons on the synchronization degree of neuronal systems. The obtained results show that, with the number of inhibitory neurons and the coupling strength from an inhibitory neuron to an excitatory neuron increasing, inhibitory neurons can not only reduce the synchronization degree when the synchronization degree of the excitatory population is initially higher, but also enhance it when it is initially lower. Meanwhile, inhibitory neurons could also help the neuronal networks to maintain moderate synchronized states. In this paper, we call this effect as modulation effect of inhibitory neurons. With the obtained results, it is further revealed that the ratio of excitatory neurons to inhibitory neurons being nearly 4 : 1 is an economic and affordable choice for inhibitory neurons to realize this modulation effect.

Achievments of corrosion science and corrosion protection technology

International Nuclear Information System (INIS)

Fontana, M.; Stehjl, R.

1985-01-01

Problems of corrosion-mechanical strength of metals, effect of corrosive media on creep characteristics are presented. New concepts of the mechanism of corrosion cracking and its relation to hydrogen embrittlement are described. Kinetics and mechanism of hydrogen embrittlement effect on the process of corrosion cracking of different steels and alloys are considered. The dependence of such types of failure on various structural factors is shown. Data on corrosion cracking of high-strength aluminium and titanium alloys, mechanism of the processes and protective methods are given

The Effect of Homogenization on the Corrosion Behavior of Al-Mg Alloy

Science.gov (United States)

Li, Yin; Hung, Yuanchun; Du, Zhiyong; Xiao, Zhengbing; Jia, Guangze

2018-04-01

The effect of homogenization on the corrosion behavior of 5083-O aluminum alloy is presented in this paper. The intergranular corrosion and exfoliation corrosion were used to characterize the discussed corrosion behavior of 5083-O aluminum alloy. The variations in the morphology, the kind and distribution of the precipitates, and the dislocation configurations in the samples after the homogenization were evaluated using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The effects of the highly active grain boundary character distribution and the types of constituent particles on the corrosion are discussed on the basis of experimental observations. The results indicated that the corrosion behavior of 5083-O alloy was closely related to the microstructure obtained by the heat treatment. Homogenization carried out after casting had the optimal effect on the overall corrosion resistance of the material. Nevertheless, all samples could satisfy the requirements of corrosion resistance in marine applications.

Effects of prior cold work on corrosion and corrosive wear of copper in HNO3 and NaCl solutions

International Nuclear Information System (INIS)

Yin Songbo; Li, D.Y.

2005-01-01

Effects of prior cold work on corrosion and corrosive wear behavior of copper in 0.1 M HNO 3 and 3.5% NaCl solutions, respectively, were investigated using electrochemical tests, electron work function measurements, and sliding corrosive wear tests with and without cathodic protection. Optical microscope and SEM were employed to examine the microstructure and worn surfaces. It was shown that, in general, the prior cold work raised the corrosion rate, but the effect differed in different corrosive media. In both the solutions, pure mechanical wear decreased with an increase in cold work. The prior cold work had a significant influence on the corrosive wear of copper, depending on the corrosive solution and the applied load. In the 0.1 M HNO 3 solution, the ratio of the wear loss caused by corrosion-wear synergism to the total wear loss increased with the cold work and became saturated when the cold work reached a certain level. In the 3.5% NaCl solution, however, this ratio decreased initially and then became relatively stable with respect to the cold work. It was observed that wear of copper in the 3.5% NaCl solution was larger than that in 0.1 M HNO 3 solution, although copper showed lower corrosion rate in the former solution. The experimental observations and the possible mechanisms involved are discussed

Effects of climate and corrosion on concrete behaviour

Science.gov (United States)

Ismail, Mohammad; Egba, Ernest Ituma

2017-11-01

Corrosion of steel is a damaging agent that reduces the functional and structural responsibilities of reinforced concrete structures. Accordingly, reinforced concrete members in the environments that are prone to concrete carbonation or chloride attack coupled with high temperature and relative humidity suffer from accelerated corrosion of reinforcing material. Also, literature proves that climate influences corrosion of concrete, and suggests investigation of impact of corrosion on concrete based on climate zone. Therefore, this paper presents the effects of climate and corrosion on concrete behavior, using bond strength of concrete as a case study. Concrete specimens were prepared form concrete mix that was infested with 3.5 kgm-3 of sodium chloride to accelerate corrosion. The specimens were cured sodium chloride solution 3.5% by weight of water for 28 days before placing them in the exposure conditions. Pull-out tests were conducted at time intervals for one year to measure the impact of exposure condition and corrosion on bond strength of concrete. The results show reduction of bond strength of concrete by 32%, 28% and 8% after one year of subjection of the specimens to the unsheltered natural climate, sheltered natural climate, and laboratory ambient environment respectively. The findings indicate that the climate influences corrosion, which reduces the interlocking bond between the reinforcing bar and the adjacent concrete.

Effect of Wall Shear Stress on Corrosion Inhibitor Film Performance

Science.gov (United States)

Canto Maya, Christian M.

In oil and gas production, internal corrosion of pipelines causes the highest incidence of recurring failures. Ensuring the integrity of ageing pipeline infrastructure is an increasingly important requirement. One of the most widely applied methods to reduce internal corrosion rates is the continuous injection of chemicals in very small quantities, called corrosion inhibitors. These chemical substances form thin films at the pipeline internal surface that reduce the magnitude of the cathodic and/or anodic reactions. However, the efficacy of such corrosion inhibitor films can be reduced by different factors such as multiphase flow, due to enhanced shear stress and mass transfer effects, loss of inhibitor due to adsorption on other interfaces such as solid particles, bubbles and droplets entrained by the bulk phase, and due to chemical interaction with other incompatible substances present in the stream. The first part of the present project investigated the electrochemical behavior of two organic corrosion inhibitors (a TOFA/DETA imidazolinium, and an alkylbenzyl dimethyl ammonium chloride), with and without an inorganic salt (sodium thiosulfate), and the resulting enhancement. The second part of the work explored the performance of corrosion inhibitor under multiphase (gas/liquid, solid/liquid) flow. The effect of gas/liquid multiphase flow was investigated using small and large scale apparatus. The small scale tests were conducted using a glass cell and a submersed jet impingement attachment with three different hydrodynamic patterns (water jet, CO 2 bubbles impact, and water vapor cavitation). The large scale experiments were conducted applying different flow loops (hilly terrain and standing slug systems). Measurements of weight loss, linear polarization resistance (LPR), and adsorption mass (using an electrochemical quartz crystal microbalance, EQCM) were used to quantify the effect of wall shear stress on the performance and integrity of corrosion inhibitor

Chemical effects in the Corrosion of Aluminum and Aluminum Alloys. A Bibliography

Science.gov (United States)

1976-10-01

tances.II. Effect Of Pomegranate Juice And The Aqueous Extract Of Pomegranate Fruits And Tea leaves On The Corrosion Of Aluminum" The effect of the juices...T7651 tempers to exfoliation and stress- corrosion cracking . 1968-8 D.P. Doyle and H.P. Godard ,a) Tr. Mezhdunar. Kongr. Korroz. Metal, 4, 439-48, (1968...Tapper Brit. Corros. J., 3, 285-87, (1968) "Corrosion Of Aluminum" Summary of the literature of Al corrosion which includes stress- corrosion cracking

Effect of zinc injection on BWR fuel cladding corrosion. Pt. 1. Study on an accelerated corrosion condition to evaluate corrosion resistance of zircaloy-2 fuel cladding

International Nuclear Information System (INIS)

Kawamura, Hirotaka; Kanbe, Hiromu; Furuya, Masahiro

2002-01-01

Japanese BWR utilities have a plan to apply zinc injection to the primary coolant in order to reduce radioactivity accumulation on the structure. Prior to applying the zinc injection to BWR plants, it is necessary to evaluate the effect of zinc injection on corrosion resistance of fuel cladding. The objective of this report was to examine the accelerated corrosion condition for evaluation of BWR fuel cladding corrosion resistance under non-irradiated conditions, as the first step of a zinc injection evaluation study. A heat transfer corrosion test facility, in which a two phase flow condition could be achieved, was designed and constructed. The effects of heat flux, void fraction and solution temperature on BWR fuel cladding corrosion resistance were quantitatively investigated. The main findings were as follows. (1) In situ measurements using high speed camera and a void sensor together with one dimensional two phase flow analysis results showed that a two phase flow simulated BWR core condition can be obtained in the corrosion test facility. (2) The heat transfer corrosion test results showed that the thickness of the zirconium oxide layer increased with increasing solution temperature and was independent of heat flux and void fraction. The corrosion accelerating factor was about 2.5 times in the case of a temperature increase from 288degC to 350degC. (author)

Antimicrobial action and anti-corrosion effect against sulfate reducing bacteria by lemongrass (Cymbopogon citratus) essential oil and its major component, the citral

Science.gov (United States)

2013-01-01

The anti-corrosion effect and the antimicrobial activity of lemongrass essential oil (LEO) against the planktonic and sessile growth of a sulfate reducing bacterium (SRB) were evaluated. Minimum inhibitory concentration (MIC) of LEO and its major component, the citral, was 0.17 mg ml-1. In addition, both LEO and citral showed an immediate killing effect against SRB in liquid medium, suggesting that citral is responsible for the antimicrobial activity of LEO against SRB. Transmission electron microscopy revealed that the MIC of LEO caused discernible cell membrane alterations and formed electron-dense inclusions. Neither biofilm formation nor corrosion was observed on carbon steel coupons after LEO treatment. LEO was effective for the control of the planktonic and sessile SRB growth and for the protection of carbon steel coupons against biocorrosion. The application of LEO as a potential biocide for SRB growth control in petroleum reservoirs and, consequently, for souring prevention, and/or as a coating protection against biocorrosion is of great interest for the petroleum industries. PMID:23938023

Inhibitory effect of corn silk on skin pigmentation.

Science.gov (United States)

Choi, Sang Yoon; Lee, Yeonmi; Kim, Sung Soo; Ju, Hyun Min; Baek, Ji Hwoon; Park, Chul-Soo; Lee, Dong-Hyuk

2014-03-03

In this study, the inhibitory effect of corn silk on melanin production was evaluated. This study was performed to investigate the inhibitory effect of corn silk on melanin production in Melan-A cells by measuring melanin production and protein expression. The corn silk extract applied on Melan-A cells at a concentration of 100 ppm decreased melanin production by 37.2% without cytotoxicity. This was a better result than arbutin, a positive whitening agent, which exhibited a 26.8% melanin production inhibitory effect at the same concentration. The corn silk extract did not suppress tyrosinase activity but greatly reduced the expression of tyrosinase in Melan-A cells. In addition, corn silk extract was applied to the human face with hyperpigmentation, and skin color was measured to examine the degree of skin pigment reduction. The application of corn silk extract on faces with hyperpigmentation significantly reduced skin pigmentation without abnormal reactions. Based on the results above, corn silk has good prospects for use as a material for suppressing skin pigmentation.

Inhibitory Effect of Corn Silk on Skin Pigmentation

Directory of Open Access Journals (Sweden)

Sang Yoon Choi

2014-03-01

Full Text Available In this study, the inhibitory effect of corn silk on melanin production was evaluated. This study was performed to investigate the inhibitory effect of corn silk on melanin production in Melan-A cells by measuring melanin production and protein expression. The corn silk extract applied on Melan-A cells at a concentration of 100 ppm decreased melanin production by 37.2% without cytotoxicity. This was a better result than arbutin, a positive whitening agent, which exhibited a 26.8% melanin production inhibitory effect at the same concentration. The corn silk extract did not suppress tyrosinase activity but greatly reduced the expression of tyrosinase in Melan-A cells. In addition, corn silk extract was applied to the human face with hyperpigmentation, and skin color was measured to examine the degree of skin pigment reduction. The application of corn silk extract on faces with hyperpigmentation significantly reduced skin pigmentation without abnormal reactions. Based on the results above, corn silk has good prospects for use as a material for suppressing skin pigmentation.

Corrosion cracking

International Nuclear Information System (INIS)

Goel, V.S.

1985-01-01

This book presents the papers given at a conference on alloy corrosion cracking. Topics considered at the conference included the effect of niobium addition on intergranular stress corrosion cracking, corrosion-fatigue cracking in fossil-fueled-boilers, fracture toughness, fracture modes, hydrogen-induced thresholds, electrochemical and hydrogen permeation studies, the effect of seawater on fatigue crack propagation of wells for offshore structures, the corrosion fatigue of carbon steels in seawater, and stress corrosion cracking and the mechanical strength of alloy 600

The effect of recasting on corrosion of DUCINOX prosthetic alloy

Directory of Open Access Journals (Sweden)

L. Klimek

2009-07-01

Full Text Available The effect of recasting, up to two times, Ni-Cr (DUCINOX prosthetic alloy on its corrosion properties was carried out. The corrosion measurements were done in deoxygenated Fusayama Meyer artificial saliva solution at temperature of 37°C. In the study following electrochemical methods were used: measurement of free corrosion potential Ecor in open circuit, measurement of polarization resistance according to Stern-Geary's method and measurement of potentiodynamic characteristic in wide range of anodic polarization. In general, it can be stated that casting number weakly influence on corrosion properties of investigated alloy. At free corrosion potential there is no monotonic dependence of corrosion parameters versus casting number. However, at extreme anodic potentials monotonic changes of corrosion parameters with increasing casting number is observed. Obtained results and drawn conclusions are partially compatible with literature data.

Inhibitory Effect of Gamma-Irradiated Chitosan on the Growth of Denitrifiers

Directory of Open Access Journals (Sweden)

Javier Vilcáez

2009-01-01

Full Text Available In order to find an environmentally benign substitute to hazardous inhibitory agents, the inhibitory effect of -irradiated chitosans against a mixed culture of denitrifying bacteria was experimentally evaluated. Unlike other studies using pure aerobic cultures, the observed effect was not a complete inhibition but a transient inhibition reflected by prolonged lag phases and reduced growth rates. Raw chitosan under acid conditions (pH 6.3 exerted the strongest inhibition followed by the 100 kGy and 500 kGy irradiated chitosans, respectively. Therefore, because the molecular weight of chitosan decreases with the degree of -irradiation, the inhibitory properties of chitosan due to its high molecular weight were more relevant than the inhibitory properties gained due to the modification of the surface charge and/or chemical structure by -irradiation. High dosage of -irradiated appeared to increase the growth of mixed denitrifying bacteria in acid pH media. However, in neutral pH media, high dosage of -irradiation appeared to enhance the inhibitory effect of chitosan.

Effects of Chemical Treatments on Microbiologically Influenced Corrosion

Science.gov (United States)

Friedman, E. S.; Strom, M.; Dexter, S. C.

2008-12-01

Biofilms are known to have an effect on galvanic corrosion of alloys in seawater systems. In the Delaware Bay, biofilm formation on surface of cathodes has been shown to cause galvanic corrosion to occur up to 100 times more rapidly. Given the impacts that corrosion can have on structures, it is important to study how we can affect corrosion rates. One way of doing this is the application of chemical treatments to biofilms on metal samples. To investigate this, natural marine biofilms were grown on alloy 6XN stainless steel samples, and various chemical treatments were applied to discover their effects on open circuit potentials and corrosion currents. Another objective of this study was to determine if there was a threshold molecular weight above which molecules were unable to penetrate the biofilm. It was discovered that chemicals with molecular weights as high as 741.6 g/mol were able to penetrate at least some parts of the heterogeneous biofilm and reach the metal surface. No upper threshold value was found in this study. It was found that the reducing agents sodium L-ascorbate and NADH as well as the chelate ferizene caused a drop in open circuit potential of biofilmed 6XN samples. Also, glutaraldahyde, which is used as a fixative for bacteria, shifted the open circuit potential of biofilm samples in the noble direction but had no effect on the corrosion current. Sodium L- ascorbate was found to reach the metal surface, but in concentrations lower than those present in the bulk fluid. It was not determined in this study whether this was due to physical or chemical processes within the biofilm. A synergistic effect was observed when applying a mixture of ferizene and glutaraldahyde. It is thought that this was due to the death of the bacteria as well as the disruption of iron cycling in the biofilm. Finally, it was observed that NADH caused a reduction in current at potentials associated with iron reduction, leading us to believe that the iron was being reduced

Inhibitory effects of crude extracts from several plants on postharvest pathogens of citrus

Science.gov (United States)

Gong, Mingfu; Guan, Qinlan; Xu, Shanshan

2018-04-01

China is one of the most important origin of citrus. Enormous economic losses was caused by fungal diseases in citrus harvest storage every year. The effective antimicrobial substances of garlic, ginger, celery and pepper were extracted by ethanol extraction and water extraction respectively. The inhibitory effects of the crude extract on Penicillium sp. caused fungal diseases in citrus harvest storage were also determined. The results showed that the extracts of garlic, ginger and celery had inhibitory effect on P. sp., but the extracts of pepper had no inhibitory effect on P. sp.. The garlic ethanol extracts had the best inhibitory effect on P. citrinum.

Lactoferricin-related peptides with inhibitory effects on ACE-dependent vasoconstriction.

Science.gov (United States)

Centeno, José M; Burguete, María C; Castelló-Ruiz, María; Enrique, María; Vallés, Salvador; Salom, Juan B; Torregrosa, Germán; Marcos, José F; Alborch, Enrique; Manzanares, Paloma

2006-07-26

A selection of lactoferricin B (LfcinB)-related peptides with an angiotensin I-converting enzyme (ACE) inhibitory effect have been examined using in vitro and ex vivo functional assays. Peptides that were analyzed included a set of sequence-related antimicrobial hexapeptides previously reported and two representative LfcinB-derived peptides. In vitro assays using hippuryl-L-histidyl-L-leucine (HHL) and angiotensin I as substrates allowed us to select two hexapeptides, PACEI32 (Ac-RKWHFW-NH2) and PACEI34 (Ac-RKWLFW-NH2), and also a LfcinB-derived peptide, LfcinB17-31 (Ac-FKCRRWQWRMKKLGA-NH2). Ex vivo functional assays using rabbit carotid arterial segments showed PACEI32 (both D- and L-enantiomers) and LfcinB17-31 have inhibitory effects on ACE-dependent angiotensin I-induced contraction. None of the peptides exhibited in vitro ACE inhibitory activity using bradykinin as the substrate. In conclusion, three bioactive lactoferricin-related peptides exhibit inhibitory effects on both ACE activity and ACE-dependent vasoconstriction with potential to modulate hypertension that deserves further investigation.

Effect of Ti3+ ion on the Corrosion Behavior of Alloy 600

International Nuclear Information System (INIS)

Lee, Chang Bong; Lim, Han Gwi; Kim, Bok Hee; Kim, Ki Ju

1999-01-01

Alloy 600 has been widely used as a steam generator tubing material in pressurized water reactors(PWRs) nuclear power plants. Corrosion of steam generator tubing mainly occurs on the secondary water side. The purpose of this work is primarily concerned with examining the effect of Ti 3+ ion concentrations on the corrosion behavior of the Alloy 600 steam generator tubing material. Corrosion behavior of the Alloy 600 steam generator tubing material was studied in aqueous solutions with varying Ti 3+ ion concentration at room temperature. Potentiodynamic and potentiostatic polarization techniques were used to determine the corrosion and pitting potentials for the Alloy 600 test material. The addition of Ti 3+ ion to 1000ppm, showed inhibition effect on the corrosion of Alloy 600. But the corrosion of Alloy 600 was accelerated when the concentration of Ti 3+ ion exceeded 1000ppm, it is assumed that the effect of general corrosion of Alloy 600 is more sensitive than pitting corrosion. It is considered that the passive film which was formed on the Alloy 600 surface in the 100ppm Ti 3+ ion containing solution is mainly consisted of TiO 2

Effect of molybdate on phosphating of Nd-Fe-B magnets for corrosion protection

Directory of Open Access Journals (Sweden)

Adonis Marcelo Saliba-Silva

2005-06-01

Full Text Available Nd-Fe-B magnets are highly susceptible to corrosion and need protection against environment attack. The use of organic coatings is one of the main methods of corrosion protection of these materials. Data related to the effect of conversion coatings, such as phosphating, on corrosion performance of these magnets is still scarce. Studies about the effect of phosphating on the corrosion resistance of a commercial Nd-Fe-B sintered magnet indicated that it increases the corrosion resistance of these magnets, compared to non-phosphated magnets. In this study, the solution chemistry of a phosphating bath was altered with the addition of molybdate and its effect on the corrosion resistance of magnets investigated. Sintered magnet specimens were phosphated in solutions of 10 g/L NaH2PO4 (pH 3.8, either with or without molybdate [10-3 M MoO4(2-], to improve their corrosion resistance. The effect of phosphating time was also evaluated, and specimens were phosphated for 4 and 18 hours. To evaluate the corrosion performance of phosphated and unphosphated specimens, a corrosion test based on monitoring hydrogen evolution on the surface of the magnets was used. This technique revealed that the addition of molybdate to the phosphating solution improved the corrosion resistance of the magnets phosphated by immersion for short periods but had no beneficial effect if phosphated by immersion for longer periods.

Corrosion behavior of Zircaloy 4 cladding material. Evaluation of the hydriding effect

International Nuclear Information System (INIS)

Blat, M.

1997-04-01

In this work, particular attention has been paid to the hydriding effect in PIE and laboratory test to validate a detrimental hydrogen contribution on Zircaloy 4 corrosion behavior at high burnup. Laboratory corrosion tests results confirm that hydrides have a detrimental role on corrosion kinetics. This effect is particularly significant for cathodic charged samples with a massive hydride outer layer before corrosion test. PIE show that at high burnup a hydride layer is formed underneath the metal/oxide interface. The results of the metallurgical examinations are discussed with respect to the possible mechanisms involved in this detrimental effect of hydrogen. Therefore, according to the laboratory tests results and PIE, hydrogen could be a strong contributor to explain the increase in corrosion rate at high burnup. (author)

Astrakhan-Mangyshlak water main (pipeline): corrosion state of the inner surface, and methods for its corrosion protection. Part III. The effects of KW2353 inhibitor. Part IV. Microbiological corrosion

International Nuclear Information System (INIS)

Reformatskaya, I.I.; Ashcheulova, I.I.; Barinova, M.A.; Kostin, D.V.; Prutchenko, S.G.; Ivleva, G.A.; Taubaldiev, T.S.; Murinov, K.S.; Tastanov, K.Kh.

2003-01-01

The effect of the KW2353 corrosion inhibitor, applied on the Astrakhan-Mangyshlak water main (pipeline) since 1997, on the corrosion processes, occurring on the 17G1S steel surface, is considered. The properties of the surface sediments are also considered. The role of the microbiological processes in the corrosion behavior of the water main (pipeline) inner surface is studied. It is shown, that application of the polyphosphate-type inhibitors, including the KW2353 one, for the anticorrosive protection of the inner surface of the extended water main (pipelines) is inadmissible: at the temperature of ∼20 deg C this corrosion inhibitor facilitates the development of the local corrosion processes on the water main (pipeline) inner surface. At the temperature of ∼8 deg C the above inhibitor discontinues to effect the corrosive stability of the 17G1S steel. The optimal way of the anticorrosive protection of the steel equipment, contacting with the water media, is the increase in the oxygen content therein [ru

Effect of municipal liquid waste on corrosion susceptibility of ...

African Journals Online (AJOL)

This investigation studied the effect of municipal liquid waste discharged into the environment within Kano municipal area on the corrosion susceptibility of galvanized steel pipe burial underground. Six stagnant and six moving municipal liquid waste samples were used for the investigation. The corrosion rate of the ...

When is an Inhibitory Synapse Effective?

Science.gov (United States)

Qian, Ning; Sejnowski, Terrence J.

1990-10-01

Interactions between excitatory and inhibitory synaptic inputs on dendrites determine the level of activity in neurons. Models based on the cable equation predict that silent shunting inhibition can strongly veto the effect of an excitatory input. The cable model assumes that ionic concentrations do not change during the electrical activity, which may not be a valid assumption, especially for small structures such as dendritic spines. We present here an analysis and computer simulations to show that for large Cl^- conductance changes, the more general Nernst-Planck electrodiffusion model predicts that shunting inhibition on spines should be much less effective than that predicted by the cable model. This is a consequence of the large changes in the intracellular ionic concentration of Cl^- that can occur in small structures, which would alter the reversal potential and reduce the driving force for Cl^-. Shunting inhibition should therefore not be effective on spines, but it could be significantly more effective on the dendritic shaft at the base of the spine. In contrast to shunting inhibition, hyperpolarizing synaptic inhibition mediated by K^+ currents can be very effective in reducing the excitatory synaptic potentials on the same spine if the excitatory conductance change is less than 10 nS. We predict that if the inhibitory synapses found on cortical spines are to be effective, then they should be mediated by K^+ through GABA_B receptors.

Effect of mechanical treatment on intergranular corrosion of 6064 alloy bars

Science.gov (United States)

Sláma, P.; Nacházel, J.

2017-02-01

Aluminium Al-Mg-Si-type alloys (6xxx-series) exhibit good mechanical properties, formability, weldability and good corrosion resistance in various environments. They often find use in automotive industry and other applications. Some alloys, however, particularly those with higher copper levels, show increased susceptibility to intergranular corrosion. Intergranular corrosion (IGC) is typically related to the formation of microgalvanic cells between cathodic, more noble phases and depleted (precipitate-free) zones along grain boundaries. It is encountered mainly in AlMgSi alloys containing Cu, where it is thought to be related to the formation Q-phase precipitates (Al4Mg8Si7Cu2) along grain boundaries. The present paper describes the effects of mechanical working (extrusion, drawing and straightening) and artificial aging on intergranular corrosion in rods of the 6064 alloy. The resistance to intergranular corrosion was mapped using corrosion tests according to EN ISO 11846, method B. Corrosion tests showed dependence of corrosion type on mechanical processing of the material. Intergranular, pitting and transgranular corrosion was observed. Artificial ageing influenced mainly the depth of the corrosion.

Effect of aging on the corrosion of aluminum alloy 6061

International Nuclear Information System (INIS)

EL-Bedawy, M.E.M.

2010-01-01

Not only alloying additions may affect the corrosion resistance of aluminum alloys, but also practices that result in a nonuniform microstructure may introduce susceptibility to some forms of corrosion, especially if the microstructural effect is localized. This work was intended to study the effect of aging time at 225, 185 and 140 degree C and the effect of constant aging time ( 24 hrs ) in the temperature range 100 - 450 degree C as well as the influence of the solution ph on the corrosion characteristics of 6061 aluminum alloy, (Al-Mg-Si alloy) containing 0.22 wt% Cu. The investigation was performed by standard immersion corrosion test according to the British Standard BS 11846 method B and by applying potentiodynamic polarization technique in neutral deaerated 0.5 % M NaCl solution as well as in alkaline NaOH solution (ph = 10). The susceptibility to corrosion and the dominant corrosion type was evaluated by examination of transverse cross sections of corroded samples after the immersion test and examination of the corroded surfaces after potentiodynamic polarization using optical microscope. Analysis of the polarization curves was used to determine the effect of different aging parameters on corrosion characteristics such as the corrosion current density I (corr), the corrosion potential E (corr), the cathodic current densities and the passivation behavior.Results of the immersion test showed susceptibility to intergranular corrosion in the under aged tempers while pitting was the dominant corrosion mode for the over aged tempers after aging at 225 and 185 degree C.Analysis of the potentiodynamic polarization curves showed similar dependence of I (corr) and cathodic current densities on the aging treatment in the neutral 0.5 %M NaCl solution and in the alkaline NaOH solution. It was observed that E(corr) values in the NaCl solution were shifted in the more noble direction for the specimens aged before peak aging while it decreased again with aging time for

Corrosion inhibition of powder metallurgy Mg by fluoride treatments.

Science.gov (United States)

Pereda, M D; Alonso, C; Burgos-Asperilla, L; del Valle, J A; Ruano, O A; Perez, P; Fernández Lorenzo de Mele, M A

2010-05-01

Pure Mg has been proposed as a potential degradable biomaterial to avoid both the disadvantages of non-degradable internal fixation implants and the use of alloying elements that may be toxic. However, it shows excessively high corrosion rate and insufficient yield strength. The effects of reinforcing Mg by a powder metallurgy (PM) route and the application of biocompatible corrosion inhibitors (immersion in 0.1 and 1M KF solution treatments, 0.1M FST and 1M FST, respectively) were analyzed in order to improve Mg mechanical and corrosion resistance, respectively. Open circuit potential measurements, polarization techniques (PT), scanning electrochemical microscopy (SECM) and electrochemical impedance spectroscopy (EIS) were performed to evaluate its corrosion behavior. SECM showed that the local current of attacked areas decreased during the F(-) treatments. The corrosion inhibitory action of 0.1M FST and 1M FST in phosphate buffered solution was assessed by PT and EIS. Under the experimental conditions assayed, 0.1M FST revealed better performance. X-ray photoelectron spectroscopy, energy dispersive X-ray and X-ray diffraction analyses of Mg(PM) with 0.1M FST showed the presence of KMgF(3) crystals on the surface while a MgF(2) film was detected for 1M FST. After fluoride inhibition treatments, promising results were observed for Mg(PM) as degradable metallic biomaterial due to its higher yield strength and lower initial corrosion rate than untreated Mg, as well as a progressive loss of the protective characteristics of the F(-)-containing film which ensures the gradual degradation process. Copyright (c) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effect of menthol coated craft paper on corrosion of copper in HCl ...

Indian Academy of Sciences (India)

Administrator

The effect of menthol on copper corrosion was studied by gravimetric and ... lable for temporary protection of metals and alloys from corrosion, the use of volatile .... The corrosion kinetic parameters were obtained from the anodic and cathodic.

Effect of high temperature filtration on out-core corrosion product activity

International Nuclear Information System (INIS)

Horvath, G.L.; Bogancs, J.

1983-01-01

Investigation of the effect of high temperature filtration on corrosion product transport and out-core corrosion product activity has been carried out for VVER-440 plants. In the physico-chemical model applied particulate and dissolved corrosion products were taken into account. We supposed 100% effectivity for the particulate filter. It was found that about 0,5% 160 t/h/ of the main flow would result in an approx.50% reduction of the out-core corrosion product activity. Investigation of the details of the physico-chemical model in Nuclear Power Plant Paks showed a particle deposition rate measured during power transients fairly agreeing with other measurements and data used in the calculations. (author)

Inhibitory effects of Bacillus subtilis on plant pathogens of conservatory in high latitudes

Science.gov (United States)

Xue, Chun-Mei; Wang, Xue; Yang, Jia-Li; Zhang, Yue-Hua

2018-03-01

Researching the effect of three kinds of Bacillus and their mixed strains inhibitory on common fungal diseases of conservatory vegetables. The results showed that B. megaterium culture medium had a significant inhibition effect on Cucumber Fusarium wilt, and the inhibition rate was up to 84.36%; B. mucilaginosus and B. megaterium sterile superna-tant had an obvious inhibitory effect on brown disease of eggplant, and the inhibition rate as high as 85.49%; B. subtilis sterile supernatant had a good inhibitory effect on the spore germination of C. Fusarium wilt, and the inhibition rate was 76.83%. The results revealed that Bacillus had a significant inhibitory effect on five common fungal pathogens. Three kinds of Bacillus can be used for the prevention and control of common fungal diseases in conservatory vegetables.

An Experimental Investigation of the Effect of Corrosion on Dry Friction Noise

International Nuclear Information System (INIS)

Baek, Jongsu; Kang, Jaeyoung

2015-01-01

This study investigates the friction noise characteristic in relation to the corrosion of metal by using the frictional reciprocating and pin-on-disk system. From the experiments, it is found that the corrosion of metal advances the onset time and increases the magnitude of friction noise. Further, it is observed that the effect of corrosion on friction noise stems from the alteration of tribo-surface during repetitive frictional motion. The alteration of the corrosive contact surface induces a negative friction-velocity slope, by which the corrosion of metal can generate dynamic instability faster than non-corrosion of metal

Economic effects of full corrosion surveys for aging concrete structures

NARCIS (Netherlands)

Polder, R.B.; Peelen, W.H.A.; Raupach, M.; Reichling, K.

2013-01-01

This paper investigates the economic effects of full corrosion surveys of concrete structures. The background is that the existing concrete infrastructure is aging, while being exposed to aggressive influences, which increases the occurrence of corrosion and related concrete damage over time. The

Corrosion-Activated Micro-Containers for Environmentally Friendly Corrosion Protective Coatings

Science.gov (United States)

Li, Wenyan; Buhrow, J. W.; Zhang, X.; Johnsey, M. N.; Pearman, B. P.; Jolley, S. T.; Calle, L. M.

2016-01-01

This work concerns the development of environmentally friendly encapsulation technology, specifically designed to incorporate corrosion indicators, inhibitors, and self-healing agents into a coating, in such a way that the delivery of the indicators and inhibitors is triggered by the corrosion process, and the delivery of self-healing agents is triggered by mechanical damage to the coating. Encapsulation of the active corrosion control ingredients allows the incorporation of desired autonomous corrosion control functions such as: early corrosion detection, hidden corrosion detection, corrosion inhibition, and self-healing of mechanical damage into a coating. The technology offers the versatility needed to include one or several corrosion control functions into the same coating.The development of the encapsulation technology has progressed from the initial proof-of-concept work, in which a corrosion indicator was encapsulated into an oil-core (hydrophobic) microcapsule and shown to be delivered autonomously, under simulated corrosion conditions, to a sophisticated portfolio of micro carriers (organic, inorganic, and hybrid) that can be used to deliver a wide range of active corrosion ingredients at a rate that can be adjusted to offer immediate as well as long-term corrosion control. The micro carriers have been incorporated into different coating formulas to test and optimize the autonomous corrosion detection, inhibition, and self-healing functions of the coatings. This paper provides an overview of progress made to date and highlights recent technical developments, such as improved corrosion detection sensitivity, inhibitor test results in various types of coatings, and highly effective self-healing coatings based on green chemistry. The NASA Kennedy Space Centers Corrosion Technology Lab at the Kennedy Space Center in Florida, U.S.A. has been developing multifunctional smart coatings based on the microencapsulation of environmentally friendly corrosion

Strain rate effects in stress corrosion cracking

Energy Technology Data Exchange (ETDEWEB)

Parkins, R.N. (Newcastle upon Tyne Univ. (UK). Dept. of Metallurgy and Engineering Materials)

1990-03-01

Slow strain rate testing (SSRT) was initially developed as a rapid, ad hoc laboratory method for assessing the propensity for metals an environments to promote stress corrosion cracking. It is now clear, however, that there are good theoretical reasons why strain rate, as opposed to stress per se, will often be the controlling parameter in determining whether or not cracks are nucleated and, if so, are propagated. The synergistic effects of the time dependence of corrosion-related reactions and microplastic strain provide the basis for mechanistic understanding of stress corrosion cracking in high-pressure pipelines and other structures. However, while this may be readily comprehended in the context of laboratory slow strain tests, its extension to service situations may be less apparent. Laboratory work involving realistic stressing conditions, including low-frequency cyclic loading, shows that strain or creep rates give good correlation with thresholds for cracking and with crack growth kinetics.

Corrosion effects on friction factors

International Nuclear Information System (INIS)

Magleby, H.L.; Shaffer, S.J.

1996-01-01

This paper presents the results of NRC-sponsored material specimen tests that were performed to determine if corrosion increases the friction factors of sliding surfaces of motor-operated gate valves, which could require higher forces to close and open safety-related valves when subjected to their design basis differential pressures. Friction tests were performed with uncorroded specimens and specimens subjected to accelerated corrosion. Preliminary tests at ambient conditions showed that corrosion increased the friction factors, indicating the need for additional tests duplicating valve operating parameters at hot conditions. The additional tests showed friction factors of corroded specimens were 0.1 to 0.2 higher than for uncorroded specimens, and that the friction factors of the corroded specimens were not very dependent on contact stress or corrosion film thickness. The measured values of friction factors for the three corrosion films tested (simulating three operating times) were in the range of 0.3 to 0.4. The friction factor for even the shortest simulated operating time was essentially the same as the others, indicating that the friction factors appear to reach a plateau and that the plateau is reached quickly

Effects of Alloyed Carbon on the General Corrosion and the Pitting Corrosion Behavior of FeCrMnN Stainless Steels

Energy Technology Data Exchange (ETDEWEB)

Ha, Heon-Young; Lee, Tae-Ho; Kim, Sung-Joon [Korea Institute of Materials Science, Changwon (Korea, Republic of)

2011-10-15

The effects of alloyed carbon on the pitting corrosion, the general corrosion, and the passivity behavior of Fe{sub 1}8Cr{sub 1}0Mn{sub 0}.4Nx{sub C} (x=0 ⁓ 0.38 wt%) alloys were investigated by various electrochemical methods and XPS analysis. The alloyed carbon increased the general corrosion resistance of the FeCrMnN matrix. Carbon enhanced the corrosion potential, reduced the metal dissolution rate, and accelerated the hydrogen evolution reaction rate in various acidic solutions. In addition, carbon promoted the pitting corrosion resistance of the matrix in a chloride solution. The alloyed carbon in the matrix increased the chromium content in the passive film, and thus the passive film became more protective.

Corrosion in marine atmospheres. Effect of distance from the coast

International Nuclear Information System (INIS)

Chico, B.; Otero, E.; Morcillos, M.; Mariaca, L.

1998-01-01

In marine atmospheres the deposition of saline particles on the surface of metals intensifies the metallic corrosion process. However, quantitative information about the effect of atmospheric salinity on metallic corrosion is very scarce. This paper reports the relationship between salinity and metallic corrosion, where a clear linear relation (r=0.97) has been found for a broad interval of salinities (4-500 mg Cl''-/m''2.d), as well as the relationship between salinity (or metallic corrosion) and distance from the coast. A hyperbolic function seems to be established both variables; there is an exponential drop in salinity (or corrosion) as shoreline distance increases tending towards and asymptotic value. The study has been based on information obtained from field research conducted at a marine atmosphere in Tarragona (Spain) and data compiled from the literature. (Author) 14 refs

Effect of nitrogen alloying of stainless steels on their corrosion stability

International Nuclear Information System (INIS)

Chigal, V.; Knyazheva, V.M.; Pitter, Ya.; Babich, S.G.; Bogolyubskij, S.D.

1986-01-01

Results of corrosion tests and structural investigations of 03Cr18Ni10 and 03Cr18Ni10Mo3 steels without nitrogen and with nitrogen content of 0.15-0.3% are presented. Corrosion-electrochemical behaviour of Cr20Ni20 steel with ultralow carbon content (0.004-0.006%) and nitrogen content with 0-0.5% as well as Cr 2 N nitride behaviour are investigated. A conclusion is made on nitrogen and excessive nitride phase effect on corrosion stability of steel in corrosive media with different reduction-oxidation properties

The effects of argon ion bombardment on the corrosion resistance of tantalum

Science.gov (United States)

Ramezani, A. H.; Sari, A. H.; Shokouhy, A.

2017-02-01

Application of ion beam has been widely used as a surface modification method to improve surface properties. This paper investigates the effect of argon ion implantation on surface structure as well as resistance against tantalum corrosion. In this experiment, argon ions with energy of 30 keV and in doses of 1 × 1017-10 × 1017 ions/cm2 were used. The surface bombardment with inert gases mainly produces modified topography and morphology of the surface. Atomic Force Microscopy was also used to patterned the roughness variations prior to and after the implantation phase. Additionally, the corrosion investigation apparatus wear was applied to compare resistance against tantalum corrosion both before and after ion implantation. The results show that argon ion implantation has a substantial impact on increasing resistance against tantalum corrosion. After the corrosion test, scanning electron microscopy (SEM) analyzed the samples' surface morphologies. In addition, the elemental composition is characterized by energy-dispersive X-ray (EDX) analysis. The purpose of this paper was to obtain the perfect condition for the formation of tantalum corrosion resistance. In order to evaluate the effect of the ion implantation on the corrosion behavior, potentiodynamic tests were performed. The results show that the corrosion resistance of the samples strongly depends on the implantation doses.

Correlation between enzymes inhibitory effects and antioxidant ...

African Journals Online (AJOL)

... and phytochemical content of fractions was investigated. The n-butanol fraction showed significant α-glucosidase and α-amylase inhibitory effects (IC50 values 15.1 and 39.42 μg/ml, respectively) along with the remarkable antioxidant activity when compared to the other fractions. High performance liquid chromatography ...

Effect of Bi on the corrosion resistance of zirconium alloys

International Nuclear Information System (INIS)

Yao Meiyi; Zhou Bangxin; Li Qiang; Zhang Weipeng; Zhu Li; Zou Linghong; Zhang Jinlong; Peng Jianchao

2014-01-01

In order to investigate systematically the effect of Bi addition on the corrosion resistance of zirconium alloys, different zirconium-based alloys, including Zr-4 (Zr-l.5Sn-0.2Fe-0.1Cr), S5 (Zr-0.8Sn-0.35Nb-0.4Fe-0.1Cr), T5 (Zr-0.7Sn-l.0Nb-0.3Fe-0.1Cr) and Zr-1Nb, were adopted to prepare the zirconium alloys containing Bi of 0∼0.5% in mass fraction. These alloys were denoted as Zr-4 + xBi, S5 + xBi, T5 + xBi and Zr-1Nb + xBi, respectively. The corrosion behavior of these specimens was investigated by autoclave testing in lithiated water with 0.01 M LiOH or deionized water at 360 ℃/18.6 MPa and in superheated steam at 400 ℃/10.3 MPa. The microstructure of the alloys was examined by TEM and the second phase particles (SPPs) were analyzed by EDS. Microstructure observation shows that the addition of Bi promotes the precipitation of Sn as second phase particles (SPPs) because Sn is in solid solution in α-Zr matrix in Zr-4, S5 and T5 alloys. The concentration of Bi dissolved in α-Zr matrix increase with the increase of Nb in the alloys, and the excess Bi precipitates as Bi-containing SPPs. The corrosion results show that the effect of Bi addition on the corrosion behavior of different zirconium-based alloys is very complicated, depending on their compositions and corrosion conditions. In the case of higher Bi concentration in α-Zr, the zirconium alloys exhibit better corrosion resistance. However, in the case of precipitation of Bi-containing SPPs, the corrosion resistance gets worse. This indicates that the solid solution of Bi in α-Zr matrix can improve the corrosion resistance, while the precipitation of the Bi-containing SPPs is harmful to the corrosion resistance. (authors)

Effect of grain size on corrosion of nanocrystalline copper in NaOH solution

International Nuclear Information System (INIS)

Luo Wei; Xu Yimin; Wang Qiming; Shi Peizhen; Yan Mi

2010-01-01

Research highlights: → Coppers display an active-passive-transpassive behaviour with duplex passive film. → Grain size variation has little effect on the overall corrosion behaviour of Cu. → Little effect on corrosion may be due to duplex passivation in NaOH solution. → Bulk nanocrystalline Cu show bamboo-like flake corrosion structure. - Abstract: Effect of grain size on corrosion of bulk nanocrystalline copper was investigated using potentiodynamic polarization measurements in 0.1 M NaOH solution. Bulk nanocrystalline copper was prepared by inert gas condensation and in situ warm compress (IGCWC) method. The grain sizes of all bulk nanocrystalline samples were determined to be 48, 68 and 92 nm using X-ray diffraction (XRD). Results showed that bulk coppers displayed an active-passive-transpassive behaviour with duplex passive films. From polycrystalline to nanocrystalline, grain size variation showed little effect on the overall corrosion resistance of copper samples.

Shadow corrosion phenomenon. An out-of-pile study on electrochemical effects

Energy Technology Data Exchange (ETDEWEB)

Weber, Nadine

2017-04-28

The focus of the present thesis was the study of the enhanced corrosion phenomenon named ''Shadow Corrosion''. Within the context of researching based on the corrosion mechanism as well as the influencing parameters and driving forces, which cause or even intensify the corrosion, a variety of electrochemical characterization and surface analysis techniques were used. The first part of this thesis gives a short introduction with the definition of the term Shadow Corrosion and of the specific type called ''Enhanced Spacer Shadow Corrosion'' (ESSC). This is followed by a description of the involved materials being Zircaloy and Inconel 718. Chapter 2 introduces the background knowledge including fundamentals about environ-mental conditions under which Shadow Corrosion occurs as well as the oxidation behavior of Zircaloy and Inconel 718. Furthermore, the state of the art about the Shadow Corrosion mechanism is presented and a description of the influencing effects on the enhanced corrosion phenomenon, like galvanic corrosion, water radiolysis, and photo-effect, is given. Further information and parameters on the part of AREVA GmbH concerning water impurities and a used coating layer on Inconel 718 are listed, which are of interest for the issue concerning the phenomenon Shadow Corrosion. The last part of this chapter contains the experimental conditions and parameters for the laboratory experiments with focus on water chemistry, specimen geometry, and UV-light exposure for photoexcitation and water radiolysis. Three different working hypotheses of this thesis are described in chapter 3. One hypothesis regarding the Shadow Corrosion Phenomenon is based on a galvanic corrosion mechanism between Zircaloy and Inconel 718. In addition, it is supposed that the galvanic corrosion could be influenced by the deposition of silver on Zircaloy and Inconel 718 in the form of an increased galvanic current. A further assumption is that the

Shadow corrosion phenomenon. An out-of-pile study on electrochemical effects

International Nuclear Information System (INIS)

Weber, Nadine

2017-01-01

The focus of the present thesis was the study of the enhanced corrosion phenomenon named ''Shadow Corrosion''. Within the context of researching based on the corrosion mechanism as well as the influencing parameters and driving forces, which cause or even intensify the corrosion, a variety of electrochemical characterization and surface analysis techniques were used. The first part of this thesis gives a short introduction with the definition of the term Shadow Corrosion and of the specific type called ''Enhanced Spacer Shadow Corrosion'' (ESSC). This is followed by a description of the involved materials being Zircaloy and Inconel 718. Chapter 2 introduces the background knowledge including fundamentals about environ-mental conditions under which Shadow Corrosion occurs as well as the oxidation behavior of Zircaloy and Inconel 718. Furthermore, the state of the art about the Shadow Corrosion mechanism is presented and a description of the influencing effects on the enhanced corrosion phenomenon, like galvanic corrosion, water radiolysis, and photo-effect, is given. Further information and parameters on the part of AREVA GmbH concerning water impurities and a used coating layer on Inconel 718 are listed, which are of interest for the issue concerning the phenomenon Shadow Corrosion. The last part of this chapter contains the experimental conditions and parameters for the laboratory experiments with focus on water chemistry, specimen geometry, and UV-light exposure for photoexcitation and water radiolysis. Three different working hypotheses of this thesis are described in chapter 3. One hypothesis regarding the Shadow Corrosion Phenomenon is based on a galvanic corrosion mechanism between Zircaloy and Inconel 718. In addition, it is supposed that the galvanic corrosion could be influenced by the deposition of silver on Zircaloy and Inconel 718 in the form of an increased galvanic current. A further assumption is that the galvanic current could be decreased by a Cr

Effect of niobium element on the electrochemical corrosion behavior of depleted uranium

Energy Technology Data Exchange (ETDEWEB)

Wu, Yanping, E-mail: wuyanping-2@126.com; Wu, Quanwen; Zhu, Shengfa, E-mail: zhushf-306@163.com; Pu, Zhen; Zhang, Yanzhi; Wang, Qinguo; Lang, Dingmu; Zhang, Yuping

2016-09-15

Depleted uranium (DU) has many military and civilian uses. However, its high chemical reactivity limits its application. The effect of Nb content on corrosion behavior of DU is evaluated by scanning Kelvin probe and electrochemical corrosion measurements. The Volta potential value of DU and U-2.5 wt% Nb is about the same level, the Volta potential value of U-5.7 wt% Nb has a rise of 370mV{sub SHE} in comparison with DU. The polarization current of U-5.7 wt% Nb alloy is about an order of magnitude of that of DU. The Nb{sub 2}O{sub 5} is the protective layer for the U-Nb alloys. The negative potential of Nb-depleted α phase is the main reason of the poor corrosion resistance of DU and U-2.5 wt% Nb alloy. - Highlights: • New method (scanning Kelvin probe) was used to study the corrosion property. • Three types of corrosion morphologies were found after potentiodynamic polarization. • The effect of impurity elements on corrosion property was mentioned. • The corrosion mechanism of DU and U-Nb alloys was discussed.

Effect of heat treatment on the grooving corrosion resistance of ERW pipes

International Nuclear Information System (INIS)

Lee, Jong Kwon; Lee, Jae Young; Lim, Soo Hyun; Park, Ji Hwan; Seo, Bo Min; Kim, Seon Hwa

2002-01-01

The v-sharp grooving corrosion of ERW(electrical resistance welding) steel pipes limited their wide application in the industry in spite of their high productivity and efficiency. The grooving corrosion is caused mainly by the different microstructures between the matrix and weld that is formed during the rapid heating and cooling cycle in welding. By this localized corrosion reaction of pipes, it evolves economic problems such as the early damage of industrial facilities and pipe lines of apartment, and water pollution. Even though the diminishing of sulfur content is most effective to decrease the susceptibility of grooving corrosion, it requires costly process. In this study, improvement of grooving corrosion resistance was pursuited by post weld heat treatment in the temperature range between 650 .deg. C and 950 .deg. C. Also, the effect of heat input in the welding was investigated. By employing chromnoamperometry and potentiodynamic experiment, the corrosion rate and grooving corrosion index(α) were obtained. It was found that heat treatment could improve the grooving corrosion resistance. Among them, the heat treated at 900 .deg. C and 950 .deg. C had excellent grooving corrosion resistance. The index of heat treated specimen at 900 .deg. C and 950 .deg. C were 1.0, 1.2, respectively, which are almost immune to the grooving corrosion. Potential difference after the heat treatment, between base and weld metal was decreased considerably. While the as-received one measured 61∼71 mV, that of the 900 .deg. C heat treated steel pipe measured only 10mV. The results were explained and discussed

Effectiveness of resins/exudates of trees in corrosion prevention of ...

African Journals Online (AJOL)

Corrosion of steel reinforcement is one of the important factors that are responsible for the short service life of reinforced concrete members, in marine structures like bridges, piers and jetties. This study, investigated the effectiveness of resin/exuda tes in corrosion prevention of reinforcement in reinforced concrete cubes.

Assessment of the inhibitory effects of pyrethroids against human carboxylesterases

Energy Technology Data Exchange (ETDEWEB)

Lei, Wei [The Second Affiliated Hospital of Dalian Medical University, Dalian 110623 (China); Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Wang, Dan-Dan; Dou, Tong-Yi [Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Hou, Jie [Dalian Medical University, Dalian 116044 (China); Feng, Liang; Yin, Heng [Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Luo, Qun [Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Sun, Jie [The Second Affiliated Hospital of Dalian Medical University, Dalian 110623 (China); Ge, Guang-Bo, E-mail: geguangbo@dicp.ac.cn [Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Yang, Ling [Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

2017-04-15

Pyrethroids are broad-spectrum insecticides that widely used in many countries, while humans may be exposed to these toxins by drinking or eating pesticide-contaminated foods. This study aimed to investigate the inhibitory effects of six commonly used pyrethroids against two major human carboxylesterases (CES) including CES1 and CES2. Three optical probe substrates for CES1 (DME, BMBT and DMCB) and a fluorescent probe substrate for CES2 (DDAB) were used to characterize the inhibitory effects of these pyrethroids. The results demonstrated that most of the tested pyrethroids showed moderate to weak inhibitory effects against both CES1 and CES2, but deltamethrin displayed strong inhibition towards CES1. The IC{sub 50} values of deltamethrin against CES1-mediated BMBT, DME, and DMCB hydrolysis were determined as 1.58 μM, 2.39 μM, and 3.3 μM, respectively. Moreover, deltamethrin was cell membrane permeable and capable of inhibition endogenous CES1 in living cells. Further investigation revealed that deltamethrin inhibited CES1-mediated BMBT hydrolysis via competitive manner but noncompetitively inhibited DME or DMCB hydrolysis. The inhibition behaviors of deltamethrin against CES1 were also studied by molecular docking simulation. The results demonstrated that CES1 had at least two different ligand-binding sites, one was the DME site and another was the BMBT site which was identical to the binding site of deltamethrin. In summary, deltamethrin was a strong reversible inhibitor against CES1 and it could tightly bind on CES1 at the same ligand-binding site as BMBT. These findings are helpful for the deep understanding of the interactions between xenobiotics and CES1. - Highlights: • The inhibitory effects of six commonly used pyrethroids on human carboxylesterases were investigated. • Deltamethrin displayed strong inhibitory effects against human carboxylesterase 1 (CES1). • Deltamethrin was cell membrane permeable and could inhibit intracellular CES1 in living

Assessment of the inhibitory effects of pyrethroids against human carboxylesterases

International Nuclear Information System (INIS)

Lei, Wei; Wang, Dan-Dan; Dou, Tong-Yi; Hou, Jie; Feng, Liang; Yin, Heng; Luo, Qun; Sun, Jie; Ge, Guang-Bo; Yang, Ling

2017-01-01

Pyrethroids are broad-spectrum insecticides that widely used in many countries, while humans may be exposed to these toxins by drinking or eating pesticide-contaminated foods. This study aimed to investigate the inhibitory effects of six commonly used pyrethroids against two major human carboxylesterases (CES) including CES1 and CES2. Three optical probe substrates for CES1 (DME, BMBT and DMCB) and a fluorescent probe substrate for CES2 (DDAB) were used to characterize the inhibitory effects of these pyrethroids. The results demonstrated that most of the tested pyrethroids showed moderate to weak inhibitory effects against both CES1 and CES2, but deltamethrin displayed strong inhibition towards CES1. The IC 50 values of deltamethrin against CES1-mediated BMBT, DME, and DMCB hydrolysis were determined as 1.58 μM, 2.39 μM, and 3.3 μM, respectively. Moreover, deltamethrin was cell membrane permeable and capable of inhibition endogenous CES1 in living cells. Further investigation revealed that deltamethrin inhibited CES1-mediated BMBT hydrolysis via competitive manner but noncompetitively inhibited DME or DMCB hydrolysis. The inhibition behaviors of deltamethrin against CES1 were also studied by molecular docking simulation. The results demonstrated that CES1 had at least two different ligand-binding sites, one was the DME site and another was the BMBT site which was identical to the binding site of deltamethrin. In summary, deltamethrin was a strong reversible inhibitor against CES1 and it could tightly bind on CES1 at the same ligand-binding site as BMBT. These findings are helpful for the deep understanding of the interactions between xenobiotics and CES1. - Highlights: • The inhibitory effects of six commonly used pyrethroids on human carboxylesterases were investigated. • Deltamethrin displayed strong inhibitory effects against human carboxylesterase 1 (CES1). • Deltamethrin was cell membrane permeable and could inhibit intracellular CES1 in living cells

Corrosion/95 conference papers

International Nuclear Information System (INIS)

Anon.

1995-01-01

The papers in this conference represent the latest technological advances in corrosion control and prevention. The following subject areas are covered: cathodic protection in natural waters; materials for fossil fuel combustion and conversion systems; modern problems in atmospheric corrosion; innovative ideas for controlling the decaying infrastructure; deposits and their effects on corrosion in industry; volatile high temperature and non aqueous corrosion inhibitors; corrosion of light-weight and precoated metals for automotive application; refining industry corrosion; corrosion in pulp and paper industry; arctic/cold weather corrosion; materials selection for waste incinerators and associated equipment; corrosion measurement technology; environmental cracking of materials; advancing technology in the coating industry; corrosion in gas treating; green inhibition; recent advances in corrosion control of rail equipment; velocity effects and erosion corrosion in oil and gas production; marine corrosion; corrosion of materials in nuclear systems; underground corrosion control; corrosion in potable and industrial water systems in buildings and its impact on environmental compliance; deposit related boiler tube failures; boiler systems monitoring and control; recent developments and experiences in reactive metals; microbiologically influenced corrosion; corrosion and corrosion control for steel reinforced concrete; international symposium on the use of 12 and 13 Cr stainless steels in oil and gas production environments; subsea corrosion /erosion monitoring in production facilities; fiberglass reinforced pipe and tubulars in oilfield service; corrosion control technology in power transmission and distribution; mechanisms and methods of scale and deposit control; closing the loop -- results oriented cooling system monitoring and control; and minimization of aqueous discharge

Application of Moessbauer spectroscopy to the study of tannins inhibition of iron and steel corrosion

Energy Technology Data Exchange (ETDEWEB)

Jaen, Juan A., E-mail: jjaen@ancon.up.ac.pa [Universidad de Panama, CITEN, Depto. de Quimica Fisica (Panama); Obaldia, J. De; Rodriguez, M. V. [Universidad de Panama, Escuela de Quimica, Facultad de Ciencias Naturales, Exactas y Tecnologia (Panama)

2011-11-15

The inhibitory effect of tannins was investigated using, among others, potentiodynamic polarizations and Moessbauer spectroscopy. These techniques confirmed that the nature, pH and concentration of tannic solution are of upmost importance in the inhibitory properties of the solutions. It is observed that at low tannin concentration or pH, both, hydrolizable and condensed tannins, effectively inhibit iron corrosion, due to the redox properties of tannins. At pH Almost-Equal-To 0, Moessbauer spectra of the frozen aqueous solutions of iron(III) with the tannin solutions showed that iron is in the form of a monomeric species [Fe(H{sub 2}O){sub 6}]{sup 3 + }, without coordination with the functional hydroxyl groups of the tannins. The suspended material consisted of amorphous ferric oxide and oxyhydroxides, though with quebracho tannin partly resulted in complex formation and in an iron (II) species from a redox process. Other tannins, such as chestnut hydrolysable tannins, do not complex iron at this low pH. Tannins react at high concentrations or pH (3 and 5) to form insoluble blue-black amorphous complexes of mono-and bis-type tannate complexes, with a relative amount of the bis-ferric tannate generally increasing with pH. Some Fe{sup 2 + } in the form of hydrated polymeric ferrous tannate could be obtained. At pH 7, a partially hydrolyzed ferric tannate complex was also formed. The latter two phases do not provide corrosion protection. Tannin solutions at natural pH react with electrodeposited iron films (approx. 6 {mu}m) to obtain products consisting only on the catecholate mono-complex of ferric tannate. Some aspects of the mechanism of tannins protection against corrosion are discussed.

EFFECT OF RATIO OF SURFACE AREA ON THE CORROSION RATE

OpenAIRE

Dody Prayitno; M. Irsyad

2018-01-01

Aluminum and steel are used to be a construction for a building outdoor panel. Aluminum and steel are connected by bolt and nut. An atmosphere due to a corrosion of the aluminum. The corrosion possibly to cause the hole diameter of bolt and nut to become larger. Thus the bolt and nut can not enough strong to hold the panel. The panel may collapse. The aim of the research is first to answer a question where does the corrosion starts. The second is to know the effect of ratio surface area of st...

Inhibitory Effects of 5,6,7-Trihydroxyflavones on Tyrosinase

Directory of Open Access Journals (Sweden)

Jun Kawabata

2007-01-01

Full Text Available Baicalein (1, 6-hydroxyapigenin (6, 6-hydroxygalangin (13 and 6-hydroxy-kaempferol (14, which are naturally occurring flavonoids from a set of 14 hydroxy-flavones tested, exhibited high inhibitory effects on tyrosinase with respect to L-DOPA,while each of the 5,6,7-trihydroxyflavones 1, 6, 13 or 14 acted as a cofactor tomonophenolase. Moreover, 6-hydroxykaempferol (14 showed the highest activity andwas a competitive inhibitor of tyrosinase compared to L-DOPA. 5,6,7-Trihydroxyflavones 1, 6, 13 or 14 showed also high antioxidant activities. Hence, weconclude that the 5,6,7-trihydroxy-flavones are useful as good depigmentation agentswith inhibitory effects in addition to their antioxidant properties.

Dictionary corrosion and corrosion control

International Nuclear Information System (INIS)

1985-01-01

This dictionary has 13000 entries in both languages. Keywords and extensive accompanying information simplify the choice of word for the user. The following topics are covered: Theoretical principles of corrosion; Corrosion of the metals and alloys most frequently used in engineering. Types of corrosion - (chemical-, electro-chemical, biological corrosion); forms of corrosion (superficial, pitting, selective, intercrystalline and stress corrosion; vibrational corrosion cracking); erosion and cavitation. Methods of corrosion control (material selection, temporary corrosion protection media, paint and plastics coatings, electro-chemical coatings, corrosion prevention by treatment of the corrosive media); Corrosion testing methods. (orig./HP) [de

Effect of radiation on anaerobic corrosion of iron

International Nuclear Information System (INIS)

Smart, N.R.; Rance, A.P.

2005-01-01

To ensure the safe encapsulation of spent nuclear fuel elements for geological disposal, SKB of Sweden are considering using the Advanced Cold Process Canister, which consists of an outer copper canister and a cast iron insert. A programme of work has been carried out to investigate a range of corrosion issues associated with the canister, including measurements of gas generation due to the anaerobic corrosion of ferrous materials (carbon steel and cast iron) over a range of conditions. To date, all this work has been conducted in the absence of a radiation field. SKB asked Serco Assurance to carry out a set of experiments designed to investigate the effect of radiation on the corrosion of steel in repository environments. This report describes the experimental programme and presents the results that were obtained. The measurements were carried out in the type of gas cell used previously, in which the change in gas pressure was measured using a liquid-filled manometer. The test cells were placed in a radiation cell and positioned so that the received radiation dose was equivalent to that expected in the repository. Control cells were used to allow for any gas generation caused by radiolytic breakdown of the construction materials and the water. Tests were carried out at two temperatures (30 deg C and 50 deg C), two dose rates (11 Gray/hr and 300 Gray/hr), and in two different artificial groundwaters. A total of four tests were carried out, using carbon steel wires as the test material. The cells were exposed for a period of several months, after which they were dismantled and the corrosion product on one wire from each test cell was analysed using Raman spectroscopy. The report presents the results from the gas generation tests and compares the results obtained under irradiated conditions to results obtained previously in the absence of radiation. Radiation was found to enhance the corrosion rate at both dose rates but the greatest enhancement occurred at the

Inhibitory Effects of Daiokanzoto (Da-Huang-Gan-Cao-Tang on P-Glycoprotein

Directory of Open Access Journals (Sweden)

Yuka Watanabe

2012-01-01

Full Text Available We have studied the effects of various Kampo medicines on P-glycoprotein (P-gp, a drug transporter, in vitro. The present study focused on Daiokanzoto (Da-Huang-Gan-Cao-Tang, which shows the most potent inhibitory effects on P-gp among the 50 Kampo medicines studied, and investigated the P-gp inhibitory effects of Daiokanzoto herbal ingredients (rhubarb and licorice root and their components by an ATPase assay using human P-gp membrane. Both rhubarb and licorice root significantly inhibited ATPase activity, and the effects of rhubarb were more potent than those of licorice root. The content of rhubarb in Daiokanzoto is double that in licorice root, and the inhibition patterns of Daiokanzoto and rhubarb involve both competitive and noncompetitive inhibition, suggesting that the inhibitory effects of Daiokanzoto are mainly due to rhubarb. Concerning the components of rhubarb, concentration-dependent inhibitory effects were observed for (−-catechin gallate, (−-epicatechin gallate, and (−-epigallocatechin gallate. In conclusion, rhubarb may cause changes in the drug dispositions of P-gp substrates through the inhibition of P-gp. It appears that attention should be given to the interactions between these drugs and Kampo medicines containing rhubarb as an herbal ingredient.

Effect of microcrystallization on pitting corrosion of pure aluminium

International Nuclear Information System (INIS)

Meng Guozhe; Wei Liyan; Zhang Tao; Shao Yawei; Wang Fuhui; Dong Chaofang; Li Xiaogang

2009-01-01

A microcrystalline aluminium film with grain size of about 400 nm was prepared by magnetron sputtering technique. Its corrosion behaviour was investigated in NaCl containing acidic solution by means of potentiodynamic polarization curves and electrochemical noise (EN). The polarization results indicated that the corrosion potential of the sample shifted towards more positive direction, while its corrosion current density decreased compared with that of pure coarse-grain Al. The EN analysis based on stochastic model demonstrated that there existed two kinds of effect of microcrystallization on the pitting behaviour of pure aluminium: (1) the rate of pit initiation is accelerated, (2) the pit growth process was impeded. This leads to the enhancement of pitting resistance for the microcrystallized aluminium.

Humid-air and aqueous corrosion models for corrosion-allowance barrier material

International Nuclear Information System (INIS)

Lee, J.H.; Atkins, J.E.; Andrews, R.W.

1995-01-01

Humid-air and aqueous general and pitting corrosion models (including their uncertainties) for the carbon steel outer containment barrier were developed using the corrosion data from literature for a suite of cast irons and carbon steels which have similar corrosion behaviors to the outer barrier material. The corrosion data include the potential effects of various chemical species present in the testing environments. The atmospheric corrosion data also embed any effects of cyclic wetting and drying and salts that may form on the corroding specimen surface. The humid-air and aqueous general corrosion models are consistent in that the predicted humid-air general corrosion rates at relative humidities between 85 and 100% RH are close to the predicted aqueous general corrosion rates. Using the expected values of the model parameters, the model predicts that aqueous pitting corrosion is the most likely failure mode for the carbon steel outer barrier, and an earliest failure (or initial pit penetration) of the 100-mm thick barrier may occur as early as about 500 years if it is exposed continuously to an aqueous condition at between 60 and 70 degrees C

Effects of Cations on Corrosion of Inconel 625 in Molten Chloride Salts

Science.gov (United States)

Zhu, Ming; Ma, Hongfang; Wang, Mingjing; Wang, Zhihua; Sharif, Adel

2016-04-01

Hot corrosion of Inconel 625 in sodium chloride, potassium chloride, magnesium chloride, calcium chloride and their mixtures with different compositions is conducted at 900°C to investigate the effects of cations in chloride salts on corrosion behavior of the alloy. XRD, SEM/EDS were used to analyze the compositions, phases, and morphologies of the corrosion products. The results showed that Inconel 625 suffers more severe corrosion in alkaline earth metal chloride molten salts than alkaline metal chloride molten salts. For corrosion in mixture salts, the corrosion rate increased with increasing alkaline earth metal chloride salt content in the mixture. Cations in the chloride molten salts mainly affect the thermal and chemical properties of the salts such as vapor pressure and hydroscopicities, which can affect the basicity of the molten salt. Corrosion of Inconel 625 in alkaline earth metal chloride salts is accelerated with increasing basicity.

Galvanic corrosion -- Effect of environmental and experimental variables

International Nuclear Information System (INIS)

Roy, A.K.; Fleming, D.L.; Lum, B.Y.

1999-01-01

Galvanic corrosion behavior of A 516 steel (UNS K01800) coupled to UNS N06022 and UNS R53400, respectively was evaluated in an acidic brine (pH ∼ 2.75) at 30 C, 60 C and 80 C using zero resistance ammeter method. A limited number of experiments were also performed in a neutral brine involving A 516 steel/UNS N06022 couple. The steady-state galvanic current and galvanic potential were measured as functions of anode-to-cathode (A/C) area ratio and electrode distance. Results indicate that the galvanic current was gradually reduced as the A/C area ratio was increased. No systematic trend on the effect of A/C area ratio on the galvanic potential was observed. Also, no significant effect of electrode distance on the galvanic current and galvanic potential was evident. In general, increased galvanic current was noticed with increasing temperature. The limited data obtained in the neutral brine indicate that the galvanic current was reduced in this environment compared to that in the acidic brine. Optical microscopic examination was performed on all tested specimens to evaluate the extent of surface damage resulting from galvanic interaction. A 516 steel suffered from general corrosion and crevice corrosion in all environments tested. Very light crevice corrosion mark was observed with UNS N06022 and R53400 in the acidic brine at 60 C and 80 C. However, this mark appears to be a surface discoloration and no actual crevice was detected

Characterizing Corrosion Effects of Weak Organic Acids Using a Modified Bono Test

Science.gov (United States)

Zhou, Yuqin; Turbini, Laura J.; Ramjattan, Deepchand; Christian, Bev; Pritzker, Mark

2013-12-01

To meet environmental requirements and achieve benefits of cost-effective manufacturing, no-clean fluxes (NCFs) or low-solids fluxes have become popular in present electronic manufacturing processes. Weak organic acids (WOAs) as the activation ingredients in NCFs play an important role, especially in the current lead-free and halogen-free soldering technology era. However, no standard or uniform method exists to characterize the corrosion effects of WOAs on actual metallic circuits of printed wiring boards (PWBs). Hence, the development of an effective quantitative test method for evaluating the corrosion effects of WOAs on the PWB's metallic circuits is imperative. In this paper, the modified Bono test, which was developed to quantitatively examine the corrosion properties of flux residues, is used to characterize the corrosion effects of five WOAs (i.e., abietic acid, succinic acid, glutaric acid, adipic acid, and malic acid) on PWB metallic circuits. Experiments were performed under three temperature/humidity conditions (85°C/85% RH, 60°C/93% RH, and 40°C/93% RH) using two WOA solution concentrations. The different corrosion effects among the various WOAs were best reflected in the testing results at 40°C and 60°C. Optical microscopy was used to observe the morphology of the corroded copper tracks, and scanning electron microscopy (SEM) energy-dispersive x-ray (EDX) characterization was performed to determine the dendrite composition.

Effects of Alloying Elements (Cr, Mn) on Corrosion Properties of Carbon Steel in Synthetic Seawater

International Nuclear Information System (INIS)

Hyun, Youngmin; Kim, Heesan

2016-01-01

Effects of alloying elements, manganese and chromium, on corrosion resistance of carbon steel were examined using weight loss test and electrochemical tests (polarization test and electrochemical impedance spectroscopy (EIS)) in synthetic seawater at 60 ℃. The results from the weight loss test showed that chromium effectively improved corrosion resistance of carbon steel during the entire immersion time, but manganese improved corrosion resistance after the lowered corrosion resistance at the beginnings of immersion. Unlike the weight loss test, the electrochemical tests showed that the corrosion resistance did not increase with immersion time, in all the specimens. This disagreement is explained by the presence of rust involved in electrochemical reaction during electrochemical tests. The analysis of rust with transmission electron microscopy (TEM)−energy dispersive spectroscopy (EDS) showed that the amorphous-like rust layer located at the metal/rust interface with enriched alloying element (Cr, Mn) prevents diffusion of corrosive species into a metal/rust interface effectively, which leads to increased corrosion resistance. The initial corrosion behaviour is also affected by the rust types. In other words, manganese accelerated the formation of spinel oxides, negatively affecting corrosion resistance. Meanwhile, chromium accelerated the formation of goethite but impeded the formation of spinel oxides, positively affecting the corrosion resistance. From the above results, the corrosion resistance of steel is closely related with a rust type.

Effects of Alloying Elements (Cr, Mn) on Corrosion Properties of Carbon Steel in Synthetic Seawater

Energy Technology Data Exchange (ETDEWEB)

Hyun, Youngmin; Kim, Heesan [Hongik University, Sejong (Korea, Republic of)

2016-02-15

Effects of alloying elements, manganese and chromium, on corrosion resistance of carbon steel were examined using weight loss test and electrochemical tests (polarization test and electrochemical impedance spectroscopy (EIS)) in synthetic seawater at 60 ℃. The results from the weight loss test showed that chromium effectively improved corrosion resistance of carbon steel during the entire immersion time, but manganese improved corrosion resistance after the lowered corrosion resistance at the beginnings of immersion. Unlike the weight loss test, the electrochemical tests showed that the corrosion resistance did not increase with immersion time, in all the specimens. This disagreement is explained by the presence of rust involved in electrochemical reaction during electrochemical tests. The analysis of rust with transmission electron microscopy (TEM)−energy dispersive spectroscopy (EDS) showed that the amorphous-like rust layer located at the metal/rust interface with enriched alloying element (Cr, Mn) prevents diffusion of corrosive species into a metal/rust interface effectively, which leads to increased corrosion resistance. The initial corrosion behaviour is also affected by the rust types. In other words, manganese accelerated the formation of spinel oxides, negatively affecting corrosion resistance. Meanwhile, chromium accelerated the formation of goethite but impeded the formation of spinel oxides, positively affecting the corrosion resistance. From the above results, the corrosion resistance of steel is closely related with a rust type.

Inhibitory effect of some carbazides on corrosion of aluminium in hydrochloric acid and sodium hydroxide solutions

Energy Technology Data Exchange (ETDEWEB)

Fouda, A.S. [El-Mansoura Univ. (Egypt). Dept. of Chemistry; Madkour, L.H. [Tanta Univ. (Egypt). Dept. of Chemistry; Elshafei, A.A. [El-Mansoura Univ. (Egypt). Dept. of Chemistry; Elasklany, A.H. [El-Mansoura Univ. (Egypt). Dept. of Chemistry

1995-06-01

The dissolution of aluminium in hydrochloric acid and sodium hydroxide solutions in the presence of semicarbazide, thiosemicarbazide and sym.diphenylcarbazide as corrosion inhibitors has been studied using thermometric, weight-loss and polarization methods. The three methods gave consistent results. The higher inhibition efficiency of these compounds in acidic than in alkaline madia may be due to the less negative potential of aluminium in hydrochloric acid solution, favouring adsorption of the additive. The adsorption of these compounds were found to obey Frumkin adsorption isotherm. Cathodic polarization measurements showed that these compounds are cathodic inhibitors and their adsorption in the double layer does not change the mechanism of the hydrogen evolution reaction. The results are analysed in terms of both molecular and cationic adsorption. (orig.)

The effect of zinc addition on PWR corrosion product deposition on zircaloy-4

International Nuclear Information System (INIS)

Walters, W.S.; Page, J.D.; Gaffka, A.P.; Kingsbury, A.F.; Foster, J.; Anderson, A.; Wickenden, D.; Henshaw, J.; Zmitko, M.; Masarik, V.; Svarc, V.

2002-01-01

During the period 1995 to 2001 a programme of loop irradiation tests have been performed to confirm the effectiveness of zinc additions on PWR circuit chemistry and corrosion. The programme included two loop irradiation experiments, and subsequent PIE; the experiments were a baseline test (no added zinc) and a test with added zinc (10 ppb). This paper addresses the findings regarding corrosion product deposition and activation on irradiated Zircaloy-4 surfaces. The findings are relevant to overall corrosion of the reactor primary circuit, the use of zinc as a corrosion inhibitor, and activation and transport of corrosion products. The irradiation experience provides information on the equilibration of the loop chemistry, with deliberate injection of zinc. The PIE used novel and innovative techniques (described below) to obtain samples of the oxide from the irradiated Zircaloy. The results of the PIE, under normal chemistry and zinc chemistry, indicate the effect of zinc on the deposition and activation of corrosion products on Zircaloy. It was found that corrosion product deposition on Zircaloy is enhanced by the addition of zinc (but corrosion product deposition on other materials was reduced in the presence of zinc). Chemical analysis and radioisotope gamma counting results are presented, to interpret the findings. A computer model has also been used to simulate the corrosion product deposition and activation, to assist in the interpretation of the results. (authors)

Evaluation of corrosive behavior of SAE 5155 by corrosion environment

International Nuclear Information System (INIS)

An, Jae Pil; Park, Keyung Dong

2005-01-01

In this study, the influence of shot peening and corrosive condition for corrosion property was investigated on immersed in 3.5% NaCl, 10% HNO 3 + 3% HF, 6% FeCl 3 . The immersion test was performed on two kinds of specimen. The immersion periods was performed 30days. Corrosion potential, weight loss were investigated from experimental results. From test results, the effect of shot peening on the corrosion was evaluated

The effect of conditioning agents on the corrosive properties of molten urea

Energy Technology Data Exchange (ETDEWEB)

Nichols, D E; Nguyen, D T; Norton, M M; Parker, B R; Daniels, L E

1991-01-01

From the process case histories of the failure of several heat exchanger tube bundles, it was revealed that molten urea containing lignosulfonate as a granulation conditioning-hardening agent (Urea LS[trademark]) is corrosive to Types 304 and 316 stainless steel. The results of field and laboratory immersion corrosion tests indicated that the corrosivity of molten urea is strongly dependent on the process temperature rather than the conditioner composition. At temperatures below 295F, molten Urea LS[trademark] is not aggressive to these stainless steels. However, at temperatures above 300F, the corrosion of these stainless steels is extremely severe. The corrosion rate of Types 304, 304L, 316, and 316L is as high as hundreds of mils per year. The corrosion mechanism tends to be more general than localized. The results of the laboratory corrosion test also revealed that among alloying elements, copper is detrimental to corrosion resistance of stainless steel exposed to molten Urea LS[trademark], chromium is the most beneficial, and nickel has only a minor effect. Thus, copper-free and chromium stainless steels have superior corrosion resistance to the molten Urea LS[trademark] at a wide range of temperatures up to 345F.

The effect of corrosion on the structural reliability of steel offshore structures

International Nuclear Information System (INIS)

Melchers, Robert E.

2005-01-01

This paper considers essential theoretical concepts and data requirements for engineering structural reliability assessment suitable for the estimation of the safety and reliability of corroding ships, offshore structures and pipelines. Such infrastructure operates in a harsh environment. Allowance must be made for structural deterioration since protective measures such as paint coatings, galvanizing or cathodic protection may be ineffective. Reliability analysis requires accurate engineering models for the description and prediction of material corrosion loss and for the maximum depth of pitting. New probability-based models for both these forms of corrosion have been proposed recently and calibrated against a wide range of data. The effects of water velocity and of water pollution are reviewed and compared with recently reported field data for a corrosion at an offshore oil platform. The data interpreted according to the model show good correlation when allowance is made for the season of first immersion and the adverse effects of seawater velocity and of water pollution. An example is given to illustrate the application of reliability analysis to a pipeline subject to pitting corrosion. An important outcome is that good quality estimation of the longer-term probability of loss of structural integrity requires good modelling of the longer-term corrosion behaviour. This is usually associated with anaerobic corrosion. As a result, it cannot be extrapolated from data for short-term corrosion as this is associated with aerobic corrosion conditions

The effect of corrosion on the structural reliability of steel offshore structures

Energy Technology Data Exchange (ETDEWEB)

Melchers, Robert E. [Centre for Infrastructure Performance and Reliability, Department of Civil, Surveying and Environmental Engineering, School of Engineering, University of Newcastle, University Drive, Callaghan NSW 2300 (Australia)]. E-mail: rob.melchers@newcastle.edu.au

2005-10-01

This paper considers essential theoretical concepts and data requirements for engineering structural reliability assessment suitable for the estimation of the safety and reliability of corroding ships, offshore structures and pipelines. Such infrastructure operates in a harsh environment. Allowance must be made for structural deterioration since protective measures such as paint coatings, galvanizing or cathodic protection may be ineffective. Reliability analysis requires accurate engineering models for the description and prediction of material corrosion loss and for the maximum depth of pitting. New probability-based models for both these forms of corrosion have been proposed recently and calibrated against a wide range of data. The effects of water velocity and of water pollution are reviewed and compared with recently reported field data for a corrosion at an offshore oil platform. The data interpreted according to the model show good correlation when allowance is made for the season of first immersion and the adverse effects of seawater velocity and of water pollution. An example is given to illustrate the application of reliability analysis to a pipeline subject to pitting corrosion. An important outcome is that good quality estimation of the longer-term probability of loss of structural integrity requires good modelling of the longer-term corrosion behaviour. This is usually associated with anaerobic corrosion. As a result, it cannot be extrapolated from data for short-term corrosion as this is associated with aerobic corrosion conditions.

Effects of alloying elements on nodular and uniform corrosion resistance of zirconium-based alloys

International Nuclear Information System (INIS)

Abe, Katsuhiro

1992-01-01

The effects of alloying and impurity elements (tin, iron, chromium, nickel, niobium, tantalum, oxygen, aluminum, carbon, nitrogen, silicon, and phosphorus) on the nodular and uniform corrosion resistance of zirconium-based alloys were studied. The improving effect of iron, nickel and niobium in nodular corrosion resistance were observed. The uniform corrosion resistance was also improved by nickel, niobium and tantalum. The effects of impurity elements, nitrogen, aluminum and phosphorus were negligibly small but increasing the silicon content seemed to improve slightly the uniform corrosion resistance. Hydrogen pick-up fraction were not changed by alloying and impurity elements except nickel. Nickel addition increased remarkably hydrogen pick-up fraction. Although the composition of secondary precipitates changed with contents of alloying elements, the correlation of composition of secondary precipitates to corrosion resistance was not observed. (author)

Erosion-corrosion

International Nuclear Information System (INIS)

Aghili, B.

1999-05-01

A literature study on erosion-corrosion of pipings in the nuclear industry was performed. Occurred incidents are reviewed, and the mechanism driving the erosion-corrosion is described. Factors that influence the effect in negative or positive direction are treated, as well as programs for control and inspection. Finally, examples of failures from databases on erosion-corrosion are given in an attachment

The Effects of Corrosive Chemicals on Corrosion Rate of Steel Reinforcement Bars: II. Swamp Sludges

Directory of Open Access Journals (Sweden)

Henki Ashadi

2010-10-01

Full Text Available A polluted environment will influence the building age. The objective of this research was to find out the influence of corrosive chemicals within the sludge swamp area with the corrosion rate of steel concrete. Corrosion in steel concrete usually occur in acid area which contain of SO42-, Cl- and NO3-. The research treatment used by emerging ST 37 andST 60 within 60 days in 'polluted' sludge swamp area. Three variation of 'polluted' swamp sludge were made by increasing the concentration a corrosive unsure up to 1X, 5X and 10X. The corrosion rate measured by using an Immersion Method. The result of Immersion test showed that sulphate had a greatest influence to corrosion rate of ST 37 and ST 60 and followed by chloride and nitrate. Corrosion rate value for ST 37 was 17.58 mpy and for ST 60 was 12.47 mpy.

Corrosion of conductive polypyrrole: Effects of environmental factors, electrochemical stimulation, and doping anions

International Nuclear Information System (INIS)

Qi Kai; Qiu Yubing; Chen Zhenyu; Guo Xingpeng

2012-01-01

Highlights: ► Corrosive galvanic cells form on PPy film with the electrochemical reduction of O 2. ► Suitable electrochemical stimulation can inhibit the PPy’s corrosion. ► PPy film doped with larger sized anions has better corrosion resistance performance. - Abstract: The effects of environmental factors, electrochemical stimulation, and doping anions on the corrosion behaviour of conductive polypyrrole (PPy) films in alkaline aqueous media were studied with cyclic voltammetry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. High concentrations of electrolyte, low dissolved oxygen and low temperatures enhance the stability of PPy. Polarising PPy at a negative potential inhibits its corrosion obviously. PPy doped with large counter anions shows better corrosion resistance than PPy doped with small counter ions. The possible mechanism involved in PPy corrosion process is discussed.

The effect of urea on the corrosion behavior of different dental alloys.

Science.gov (United States)

Geckili, Onur; Bilhan, Hakan; Bilgin, Tayfun; Anthony von Fraunhofer, J

2012-01-01

Intraoral corrosion of dental alloys has biological, functional, and esthetic consequences. Since it is well known that the salivary urea concentrations undergo changes with various diseases, the present study was undertaken to determine the effect of salivary urea concentrations on the corrosion behavior of commonly used dental casting alloys. Three casting alloys were subjected to polarization scans in synthetic saliva with three different urea concentrations. Cyclic polarization clearly showed that urea levels above 20 mg/100 ml decreased corrosion current densities, increased the corrosion potentials and, at much higher urea levels, the breakdown potentials. The data indicate that elevated urea levels reduced the corrosion susceptibility of all alloys, possibly through adsorption of organics onto the metal surface. This study indicates that corrosion testing performed in sterile saline or synthetic saliva without organic components could be misleading.

Review on stress corrosion and corrosion fatigue failure of centrifugal compressor impeller

Science.gov (United States)

Sun, Jiao; Chen, Songying; Qu, Yanpeng; Li, Jianfeng

2015-03-01

Corrosion failure, especially stress corrosion cracking and corrosion fatigue, is the main cause of centrifugal compressor impeller failure. And it is concealed and destructive. This paper summarizes the main theories of stress corrosion cracking and corrosion fatigue and its latest developments, and it also points out that existing stress corrosion cracking theories can be reduced to the anodic dissolution (AD), the hydrogen-induced cracking (HIC), and the combined AD and HIC mechanisms. The corrosion behavior and the mechanism of corrosion fatigue in the crack propagation stage are similar to stress corrosion cracking. The effects of stress ratio, loading frequency, and corrosive medium on the corrosion fatigue crack propagation rate are analyzed and summarized. The corrosion behavior and the mechanism of stress corrosion cracking and corrosion fatigue in corrosive environments, which contain sulfide, chlorides, and carbonate, are analyzed. The working environments of the centrifugal compressor impeller show the behavior and the mechanism of stress corrosion cracking and corrosion fatigue in different corrosive environments. The current research methods for centrifugal compressor impeller corrosion failure are analyzed. Physical analysis, numerical simulation, and the fluid-structure interaction method play an increasingly important role in the research on impeller deformation and stress distribution caused by the joint action of aerodynamic load and centrifugal load.

Effect of Acidic Water on Strength, Durability and Corrosion of ...

African Journals Online (AJOL)

In this study, specimens of 108 cubes (150 mm x 150 mm x 150 mm), 36 cylinders (300 mm x 150 mm), and 72 cylinders (102 mm x 51 mm) were cast and cured in percentages of NaCl added water to find the workability, strength, durability and corrosion resistance characteristics concrete. The effect of corrosion of steel in ...

Isolation of proanthocyanidins from red wine, and their inhibitory effects on melanin synthesis in vitro.

Science.gov (United States)

Fujimaki, Takahiro; Mori, Shoko; Horikawa, Manabu; Fukui, Yuko

2018-05-15

The red wines made from Vitis vinifera were identified as skin-whitening effectors by using in vitro assays. OPCs in the wine were evaluated for tyrosinase activity and melanogenesis. Strong tyrosinase inhibitory activity was observed in fractions with high oligomeric proanthocyanidin (OPC) content. Among OPC dimers, a strong inhibitory effect on tyrosinase was observed with OPCs which contain (+)-catechin as an upper unit. Melanogenesis inhibitory effect was observed with OPCs which have (-)-epicatechin as upper units. Also, OPC trimers, upper and middle units joined with 4 → 8 bonds, showed stronger effects compared to trimers with 4 → 6 linkages. Interestingly, (-)-epicatechin-(4β → 8)-(-)-epicatechin 3-O-gallate, which is a unique component of grapes has potent inhibitory effects on both tyrosinase and melanogenesis. Our data provide structural information about such active compounds. These results suggest that red wines containing OPC, have high melanogenesis inhibitory effect and are supposed to have skin-whitening effect. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inhibitory effect of chitosan oligosaccharide on human hepatoma ...

African Journals Online (AJOL)

Background: Chitosan oligosaccharide, the degradation products of chitin, was reported to have a wide range of physiological functions and biological activities. In this study, we explored the inhibitory effect of Chitosan oligosaccharide on human hepatoma cells. Materials and Methods: MTT assay was applied to detect cell ...

Effects of chemical composition on the corrosion of dental alloys.

Science.gov (United States)

Galo, Rodrigo; Ribeiro, Ricardo Faria; Rodrigues, Renata Cristina Silveira; Rocha, Luís Augusto; de Mattos, Maria da Glória Chiarello

2012-01-01

The aim of this study was to determine the effect of the oral environment on the corrosion of dental alloys with different compositions, using electrochemical methods. The corrosion rates were obtained from the current-potential curves and electrochemical impedance spectroscopy (EIS). The effect of artificial saliva on the corrosion of dental alloys was dependent on alloy composition. Dissolution of the ions occurred in all tested dental alloys and the results were strongly dependent on the general alloy composition. Regarding the alloys containing nickel, the Ni-Cr and Ni-Cr-Ti alloys released 0.62 mg/L of Ni on average, while the Co-Cr dental alloy released ions between 0.01 and 0.03 mg/L of Co and Cr, respectively.The open-circuit potential stabilized at a higher level with lower deviation (standard deviation: Ni-Cr-6Ti = 32 mV/SCE and Co-Cr = 54 mV/SCE). The potenciodynamic curves of the dental alloys showed that the Ni-based dental alloy with >70 wt% of Ni had a similar curve and the Co-Cr dental alloy showed a low current density and hence a high resistance to corrosion compared with the Ni-based dental alloys. Some changes in microstructure were observed and this fact influenced the corrosion behavior for the alloys. The lower corrosion resistance also led to greater release of nickel ions to the medium. The quantity of Co ions released from the Co-Cr-Mo alloy was relatively small in the solutions. In addition, the quantity of Cr ions released into the artificial saliva from the Co-Cr alloy was lower than Cr release from the Ni-based dental alloys.

Surface layer effects on waste glass corrosion

International Nuclear Information System (INIS)

Feng, X.

1993-01-01

Water contact subjects waste glass to chemical attack that results in the formation of surface alteration layers. Two principal hypotheses have been advanced concerning the effect of surface alteration layers on continued glass corrosion: (1) they act as a mass transport barrier and (2) they influence the chemical affinity of the glass reaction. In general, transport barrier effects have been found to be less important than affinity effects in the corrosion of most high-level nuclear waste glasses. However, they can be important under some circumstances, for example, in a very alkaline solution, in leachants containing Mg ions, or under conditions where the matrix dissolution rate is very low. The latter suggests that physical barrier effect may affect the long-term glass dissolution rate. Surface layers influence glass reaction affinity through the effects of the altered glass and secondary phases on the solution chemistry. The reaction affinity may be controlled by various precipitates and crystalline phases, amorphous silica phases, gel layer, or all the components of the glass. The surface alteration layers influence radionuclide release mainly through colloid formation, crystalline phase incorporation, and gel layer retention. This paper reviews current understanding and uncertainties

Current state of knowledge in radiolysis effects on spent fuel corrosion

International Nuclear Information System (INIS)

Christensen, H.; Sunder, S.

1998-09-01

Literature data on the effect of water radiolysis products on spent fuel oxidation and dissolution have been reviewed. Effects of γ-radiolysis, α-radiolysis and dissolved O 2 or H 2 O 2 in unirradiated solutions have been discussed separately. Also the effect of carbonate in γ-irradiated solutions and radiolysis effects on leaching of spent fuels have been reviewed. In addition a radiolysis model for calculation of corrosion rates of UO 2 , presented previously, has been discussed. The model has been shown to give a good agreement between calculated and measured corrosion rates in the case of γ-radiolysis and in unirradiated solutions of dissolved oxygen or hydrogen peroxide. The model has failed to predict the results of α-radiolysis. In a recent study it was shown that the model gave a good agreement with measured corrosion rates of spent fuel exposed in deionized water

The effect of heat treatments on the corrosion behavior of Zircaloy-4

International Nuclear Information System (INIS)

Zhou Bangxin; Zhao Wenjin; Miao Zhi; Pan Shufang; Li Cong; Jiang Yourong

1996-06-01

The effect of penultimate annealing temperature and cooling rate on the corrosion behavior of Zircaloy-4 cladding tube has been investigated. Both nodular corrosion and uniform corrosion resistance can be improved obviously after changing the heat treatment from the original annealing at 650 degree C to quenching from 830 degree C (upper temperature of alpha phase region or lower temperature of beta phase region). Although the nodular corrosion resistance can be improved obviously after quenching from beta phase, there was a second transition in the variation between weight gain and exposure time, which shows a poor uniform corrosion resistance after a long exposure time during the autoclave tests. The main factor of affecting corrosion behavior is the solid solution contents of Fe and Cr in alpha zirconium rather than the size of second phase particles. About 200 μg/g Fe and Cr super saturated solid solution in alpha zirconium could get good uniform and nodular corrosion resistance, but much more solid solution contents of Fe and Cr in alpha zirconium could bring about a trend toward poor uniform corrosion resistance for long-term exposure time. (14 refs., 10 figs., 1 tab.)

Enzyme inhibitory and radical scavenging effects of some antidiabetic plants of Turkey

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Orhan, Nilüfer; Hoçbaç, Sanem; Orhan, Didem Deliorman; Asian, Mustafa; Ergun, Fatma

2014-01-01

Objective(s): Ethnopharmacological field surveys demonstrated that many plants, such as Gentiana olivieri, Helichrysum graveolens, Helichrysum plicatum ssp. plicatum, Juniperus oxycedrus ssp. oxycedrus, Juniperus communis var. saxatilis, Viscum album (ssp. album, ssp. austriacum), are used as traditional medicine for diabetes in different regions of Anatolia. The present study was designed to evaluate the in vitro antidiabetic effects of some selected plants, tested in animal models recently. Materials and Methods: α-glucosidase and α-amylase enzyme inhibitory effects of the plant extracts were investigated and Acarbose was used as a reference drug. Additionally, radical scavenging capacities were determined using 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) ABTS radical cation scavenging assay and total phenolic content of the extracts were evaluated using Folin Ciocalteu method. Results: H. graveolens ethanol extract exhibited the highest inhibitory activity (55.7 % ± 2.2) on α-amylase enzyme. Additionally, J. oxycedrus hydro-alcoholic leaf extract had potent α-amylase inhibitory effect, while the hydro-alcoholic extract of J. communis fruit showed the highest α-glucosidase inhibitory activity (IC50: 4.4 μg/ml). Conclusion: Results indicated that, antidiabetic effect of hydro-alcoholic extracts of H. graveolens capitulums, J. communis fruit and J. oxycedrus leaf might arise from inhibition of digestive enzymes. PMID:25140204

Enzyme inhibitory and radical scavenging effects of some antidiabetic plants of Turkey

Directory of Open Access Journals (Sweden)

Nilüfer Orhan

2014-06-01

Full Text Available Objective(s:Ethnopharmacological field surveys demonstrated that many plants, such as Gentiana olivieri, Helichrysum graveolens, Helichrysum plicatum ssp. plicatum, Juniperus oxycedrus ssp. oxycedrus, Juniperus  communis var. saxatilis, Viscum album (ssp. album, ssp. austriacum, are used as traditional medicine for diabetes in different regions of Anatolia. The present study was designed to evaluate the in vitro antidiabetic effects of some selected plants, tested in animal models recently. Materials and Methods: α-glucosidase and α-amylase enzyme inhibitory effects of the plant extracts were investigated and Acarbose was used as a reference drug. Additionally, radical scavenging capacities were determined using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid ABTS radical cation scavenging assay and total phenolic content of the extracts were evaluated using Folin Ciocalteu method. Results: H. graveolens ethanol extract exhibited the highest inhibitory activity (55.7 % ± 2.2 on α-amylase enzyme. Additionally, J. oxycedrus hydro-alcoholic leaf extract had potent α-amylase inhibitory effect, while the hydro-alcoholic extract of J. communis fruit showed the highest α-glucosidase inhibitory activity (IC50: 4.4 μg/ml. Conclusion:Results indicated that, antidiabetic effect of hydro-alcoholic extracts of H. graveolens capitulums, J. communis fruit and J. oxycedrus leaf might arise from inhibition of digestive enzymes.

Corrosion and corrosion fatigue of airframe aluminum alloys

Science.gov (United States)

Chen, G. S.; Gao, M.; Harlow, D. G.; Wei, R. P.

1994-01-01

Localized corrosion and corrosion fatigue crack nucleation and growth are recognized as degradation mechanisms that effect the durability and integrity of commercial transport aircraft. Mechanically based understanding is needed to aid the development of effective methodologies for assessing durability and integrity of airframe components. As a part of the methodology development, experiments on pitting corrosion, and on corrosion fatigue crack nucleation and early growth from these pits were conducted. Pitting was found to be associated with constituent particles in the alloys and pit growth often involved coalescence of individual particle-nucleated pits, both laterally and in depth. Fatigue cracks typically nucleated from one of the larger pits that formed by a cluster of particles. The size of pit at which fatigue crack nucleates is a function of stress level and fatigue loading frequency. The experimental results are summarized, and their implications on service performance and life prediction are discussed.

Corrosion resistance of Ni-Cr-Mo alloys. Chemical composition and metallurgical condition's effects

International Nuclear Information System (INIS)

Zadorozne, N.S.; Rebak, Raul B.

2009-01-01

Ni-Cr-Mo alloys offer an outstanding corrosion resistance in a wide variety of highly-corrosive environments. This versatility is due to the excellent performance of nickel in hot alkaline solutions and the beneficial effect of chromium and molybdenum in oxidizing and reducing conditions, respectively. Alloy C-22 (22 % Cr-13 % Mo-3% W) is a well known versatile member of this family. Due to its excellent corrosion resistance in a wide variety of environments, Alloy C-22 has been selected for the fabrication of the corrosion-resistant outer shell of the high-level nuclear waste container. The increasing demand of the industry for corrosion resistant alloys with particular properties of corrosion and mechanical resistance has led to the development of new alloys. Alloy C-22HS (Ni-21 % Cr-17 % Mo) is a new high-strength corrosion resistant material recently developed and introduced into the market. This alloy provides a corrosion resistance comparable with that of other C-type alloys, and it can also be age hardened to effectively double its yield strength. HASTELLOY HYBRID-BC1 (Ni-22 % Mo-15 % Cr) is a new development intended for filling the gap between Ni-Mo and Ni-Cr-Mo alloys. This novel alloy is able to withstand HCl and H 2 SO 4 , even in the presence of dissolved oxygen and other oxidizing species. Its resistance to chloride-induced pitting corrosion, crevice corrosion and stress corrosion cracking is also remarkable. Thermal aging of Ni-Cr-Mo alloys leads to microstructure changes depending on the temperature range and exposure time at temperature. A Long Range Ordering (LRO) reaction can occur in the range of 350 C degrees to 600 C degrees, producing an ordered Ni 2 (Cr,Mo) phase. This ordering reaction does not seem to affect the corrosion resistance and produces only a slight loss in ductility. LRO transformation is homogeneous and has proven to be useful to fabricate the age-hard enable Alloy C22-HS. Tetrahedral Close Packed (TCP) phases, like μ, σ and

Effect of partially purified angiotensin converting enzyme inhibitory ...

African Journals Online (AJOL)

This study evaluated the effect of partially-purified angiotensin converting enzyme (ACE) inhibitory proteins obtained from the leaves of Moringa oleifera on blood glucose, serum ACE activity and lipid profile of alloxaninduced diabetic rats. Twenty-five apparently healthy male albino rats were divided into five groups of five ...

Quantitative assessment of the effect of corrosion product buildup on occupational exposure

International Nuclear Information System (INIS)

Divine, J.R.

1982-10-01

The program was developed to provide a method for predicting occupational exposures caused by the deposition of radioactive corrosion products outside the core of the primary system of an operating power reactor. This predictive capability will be useful in forecasting total occupational doses during maintenance, inspection, decontamination, waste treatment, and disposal. In developing a reliable predictive model, a better understanding of the parameters important to corrosion product film formation, corrosion product transport, and corrosion product film removal will be developed. This understanding can lead to new concepts in reactor design to minimize the buildup and transport of radioactive corrosion products or to improve methods of operation. To achieve this goal, three objectives were established to provide: (1) criteria for acceptable coolant sampling procedures and sampling equipment that will provide data which will be used in the model development; (2) a quantitative assessment of the effect of corrosion product deposits on occupational exposure; and (3) a model which describes the influence of flow, temperature, coolant chemistry, construction materials, radiation, and other operating parameters on the transport and buildup of corrosion products

Inhibitory effect of non-ionic surfactants of the TRITON-X series on the corrosion of carbon steel in sulphuric acid

International Nuclear Information System (INIS)

Fuchs-Godec, R.

2007-01-01

The corrosion inhibition characteristics of non-ionic surfactants of the TRITON-X series, known as TRITON-X-100 and TRITON-X-405, on stainless steel (SS) type X4Cr13 in sulphuric acid were investigated by potentiodynamic polarisation measurements. It was found that these surfactants act as good inhibitors of the corrosion of stainless steel in 2 mol L -1 H 2 SO 4 solution, but the inhibition efficiency strongly depends on the electrode potential. The polarisation data showed that the non-ionic surfactants used in this study acted as mixed-type inhibitors and adsorb on the stainless steel surface, in agreement with the Flory-Huggins adsorption isotherm. Calculated ΔG ads values are -57.79 kJ mol -1 for TRITON-X-100, and -87.5 kJ mol -1 for TRITON-X-405. From the molecular structure it can be supposed that these surfactants adsorb on the metal surface through two lone pairs of electrons on the oxygen atoms of the hydrophilic head group, suggesting a chemisorption mechanism

The Effects of Alloy Chemistry on Localized Corrosion of Austenitic Stainless Steels

Science.gov (United States)

Sapiro, David O.

This study investigated localized corrosion behavior of austenitic stainless steels under stressed and unstressed conditions, as well as corrosion of metallic thin films. While austenitic stainless steels are widely used in corrosive environments, they are vulnerable to pitting and stress corrosion cracking (SCC), particularly in chloride-containing environments. The corrosion resistance of austenitic stainless steels is closely tied to the alloying elements chromium, nickel, and molybdenum. Polarization curves were measured for five commercially available austenitic stainless steels of varying chromium, nickel, and molybdenum content in 3.5 wt.% and 25 wt.% NaCl solutions. The alloys were also tested in tension at slow strain rates in air and in a chloride environment under different polarization conditions to explore the relationship between the extent of pitting corrosion and SCC over a range of alloy content and environment. The influence of alloy composition on corrosion resistance was found to be consistent with the pitting resistance equivalent number (PREN) under some conditions, but there were also conditions under which the model did not hold for certain commercial alloy compositions. Monotonic loading was used to generate SCC in in 300 series stainless steels, and it was possible to control the failure mode through adjusting environmental and polarization conditions. Metallic thin film systems of thickness 10-200 nm are being investigated for use as corrosion sensors and protective coatings, however the corrosion properties of ferrous thin films have not been widely studied. The effects of film thickness and substrate conductivity were examined using potentiodynamic polarization and scanning vibrating electrode technique (SVET) on iron thin films. Thicker films undergo more corrosion than thinner films in the same environment, though the corrosion mechanism is the same. Conductive substrates encourage general corrosion, similar to that of bulk iron

Effect of ageing time and temperature on corrosion behaviour of aluminum alloy 2014

Science.gov (United States)

Gadpale, Vikas; Banjare, Pragya N.; Manoj, Manoranjan Kumar

2018-03-01

In this paper, the effect of corrosion behaviour of aluminium alloy 2014 were studied by potentiodynamic polarization in 1 mole of NaCl solution of aged sample. The experimental testing results concluded that, corrosion resistance of Aluminum alloy 2014 degraded with the increasing the temperature (150°C & 200°C) and time of ageing. Corroded surface of the aged specimens was tested under optical microscopes for microstructures for phase analysis. Optical micrographs of corroded surfaces showed general corrosion and pitting corrosion. The corrosion resistance of lower ageing temperature and lower ageing time is higher because of its fine distribution of precipitates in matrix phase.

Effect of Sensitization on Corrosion-Fatigue Cracking in Al 5083 Alloy

Science.gov (United States)

2015-01-21

immediately ahead of the fatigue precrack in 0.001 and 0.01% NaCl solutions are transgranular ductile void coalescences. This observation suggests the 9...Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6355--15-9581 Effect of Sensitization on Corrosion- Fatigue Cracking in Al 5083 Alloy...area code) b. ABSTRACT c. THIS PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Effect of Sensitization on Corrosion- Fatigue Cracking in Al 5083

Effect of temperature, of oxygen content and the downstream effect on corrosion rate of structural materials in liquid sodium

International Nuclear Information System (INIS)

Ilincev, G.

1988-01-01

The effects were experimentally tested of temperature and of oxygen content on the corrosion rate of structural materials in liquid sodium and on reducing the corrosion rate down the sodium stream. The results of the experiments are shown in graphs and tables and are discussed in detail. The duration of all tests was standard 1,000 hours. The test parameters were set such as to determine the effect of temperature on corrosion of a quantity of various materials in sodium with a low oxygen content (1.2 to 2 ppm) at temperatures of 500 to 800 degC and in sodium with a high oxygen content (345 ppm) at temperatures of 500 to 700 degC. More experiments served the determination of the effect of a different oxygen content varying between 1.2 and 2 ppm at a constant temperature of 600 degC. The materials being tested included main structural materials used for fast reactor construction and materials allowing to establish the effect of main alloying elements on their corrosion in liquid sodium of different temperatures and purity grades. The relationships showing the effects of temperature and oxygen content in sodium on the rate of corrosion of various structural materials in hot parts of the installation and on the reduction in the rate of corrosion downstream due to sodium saturation with corrosion products were constructed using the experimental results. (Z.M.). 15 figs., 2 tabs., 7 refs

Simulated inhibitory effects of typical byproducts of biomass ...

African Journals Online (AJOL)

Aghomotsegin

2015-07-29

Jul 29, 2015 ... comparative inhibitory effects of acetic acid and vanillin on the ... Different concentrations of inhibitors were spiked in the fermentation ... hardwood and municipal solid wastes. ... done at the cost of an extended lag phase and reduces ..... Formation of acetic acid and lactic acid during fermentation and in ...

Effect of Biodiesel Concentration on Corrosion of Carbon Steel by Serratia marcescens

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Pusparizkita Yustina M

2018-01-01

Full Text Available Biodiesel come into being used as an alternative source of energy as the diminishing of petroleum reserves. This fuel is typically stored in tanks that are commonly made from carbon steel, which is easily corroded by microorganisms. Recent studies have shown that bacteria aside from SRB may also be involved in corrosion. Therefore, this research was aimed to evaluate the effect of biodiesel concentration (15%, 20% and 30% v/v mixed in diesel oil on the corrosion of carbon steel by S. marcescens that dominate biocorrosion on hydrocarbon products. In this study, the corrosion process was investigated by evaluation of biofilm morphology and composition, the rate of corrosion and the corrosion product of carbon steel which was exposed in the mixture of hydrocarbons and the presence of S. marcescens. It can be concluded that higher concentration of biodiesel in diesel oil leads to higher growth of bacteria in the biofilm and higher corrosion rate.

Potent Inhibitory Effect of Chinese Dietary Spices on Fatty Acid Synthase.

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Jiang, Bing; Liang, Yan; Sun, Xuebing; Liu, Xiaoxin; Tian, Weixi; Ma, Xiaofeng

2015-09-01

Dietary spices have been adopted in cooking since ancient times to enhance flavor and also as food preservatives and disease remedies. In China, the use of spices and other aromatic plants as food flavoring is an integral part of dietary behavior, but relatively little is known about their functions. Fatty acid synthase (FAS) has been recognized as a remedy target, and its inhibitors might be applied in disease treatment. The present work was designed to assess the inhibitory activities on FAS of spices extracts in Chinese menu. The in vitro inhibitory activities on FAS of 22 extracts of spices were assessed by spectrophotometrically monitoring oxidation of NADPH at 340 nm. Results showed that 20 spices extracts (90.9 %) exhibited inhibitory activities on FAS, with half inhibition concentration (IC(50)) values ranging from 1.72 to 810.7 μg/ml. Among them, seven spices showed strong inhibitory effect with IC(50) values lower than 10 μg/ml. These findings suggest that a large proportion of the dietary spices studied possess promising inhibitory activities on FAS, and subsequently might be applied in the treatment of obesity and obesity-related human diseases.

Provocative and inhibitory effects of a video-EEG neuropsychologic protocol in juvenile myoclonic epilepsy.

Science.gov (United States)

Guaranha, Mirian Salvadori Bittar; da Silva Sousa, Patrícia; de Araújo-Filho, Gerardo Maria; Lin, Katia; Guilhoto, Laura Maria Figueiredo Ferreira; Caboclo, Luís Otávio Sales Ferreira; Yacubian, Elza Márcia Targas

2009-11-01

Studies suggest that higher cognitive functions could precipitate seizures in juvenile myoclonic epilepsy (JME). The present study aimed to analyze the effects of higher mental activity on epileptiform discharges and seizures in patients with JME and compare them to those of habitual methods of activation. Seventy-six patients with JME (41 female) underwent a video-EEG (electroencephalography) neuropsychologic protocol (VNPP) and habitual methods of activation for 4-6 h. Twenty-nine of the 76 (38.2%) presented provocative effect, and inhibition was seen in 28 of 31 (90.3%). A mixed effect was observed in 11 (35.5%), and 30 patients (39.5%) suffered no effect of VNPP. Action-programming tasks were more effective than thinking in provoking epileptiform discharges (23.7% and 11.0% of patients, respectively, p = 0.03). Inhibitory effect was observed equally in the various categories of tasks, except in mental calculation, which had a higher inhibitory rate. Habitual methods of activation were more effective than VNPP in provoking discharges. Anxiety disorders were diagnosed in 24 of 58 patients (41.4%); anxious patients had greater discharge indexes and no significant inhibitory effect on VNPP. Praxis exerted the most remarkable provocative effect, in accordance with the motor circuitry hyperexcitability hypothesis in JME. Inhibitory effect, which had no such task specificity, might be mediated by a widespread cortical-thalamic pathway, possibly involving the parietal cortex. The frequent inhibitory effect found under cortical activation conditions, influenced by the presence of anxiety, supports nonpharmacologic therapeutic interventions in JME.

Effects of ion implantation on corrosion of zirconium and zirconium base alloys

International Nuclear Information System (INIS)

Zelenskij, V.F.; Petel'guzov, I.A.; Rekova, L.P.; Rodak, A.G.

1989-01-01

The influence of He and Ar ion bombardment on the corrosion of Zr and Zr-1%Nb and Zr-2.5%Nb alloys is investigated with the aims of finding the irradiation influence laws, obtaining the dependences of the effect of increasing the corrosiuon resistance on the type and dose of bombarding ions and of finding the conditions for the maximum effect. The prolonged corrosion test of specimens (3500 hours) have shown that the strongest effect is obtained for the irradiation with Ar ions up to the dose 1x10 16 ion/cm 2 . The kinetics of ion thermosorption after corrosion of irradiated materials is studied, the temperature threshold of implanted ion stability in zirconium and its alloys is found to be 400 deg C

Effect of acidity upon attrition-corrosion of human dental enamel.

Science.gov (United States)

Wu, Yun-Qi; Arsecularatne, Joseph A; Hoffman, Mark

2015-04-01

Attrition-corrosion is a synthesized human enamel wear process combined mechanical effects (attrition) with corrosion. With the rising consumption of acidic food and beverages, attrition-corrosion is becoming increasingly common. Yet, research is limited and the underlying mechanism remains unclear. In this study, in vitro wear loss of human enamel was investigated and the attrition-corrosion process and wear mechanism were elucidated by the analysis of the wear scar and its subsurface using focused ion beam (FIB) sectioning and scanning electron microscopy (SEM). Human enamel flat-surface samples were prepared with enamel cusps as the wear antagonists. Reciprocating wear testing was undertaken under load of 5N at the speed of 66 cycle/min for 2250 cycles with lubricants including citric acid (at pH 3.2 and 5.5), acetic acid (at pH 3.2 and 5.5) and distilled water. All lubricants were used at 37°C. Similar human enamel flat-surface samples were also exposed to the same solutions as a control group. The substance loss of enamel during wear can be linked to the corrosion potential of a lubricant used. Using a lubricant with very low corrosion potential (such as distilled water), the wear mechanism was dominated by delamination with high wear loss. Conversely, the wear mechanism changed to shaving of the softened layer with less material loss in an environment with medium corrosion potential such as citric acid at pH 3.2 and 5.5 and acetic acid at pH 5.5. However, a highly corrosive environment (e.g., acetic acid at pH 3.2) caused the greatest loss of substance during wear. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluation of austenitic stainless steels for transpassive corrosion by metal purification technology. Synergistic effect of Si and P on intergranular corrosion of Fe-18Cr-14Ni alloys

International Nuclear Information System (INIS)

Mayuzumi, Masami; Ohta, Joji; Kako, Kenji; Kawakami, Eishi

2001-01-01

The synergistic effect of Si, Mn, C, P, and S on the transpassive corrosion of HP18Cr-14Ni alloys was studied in 13N nitric acid. The specimens were fabricated using a cold crucible method in a high-vacuum chamber to reduce contamination. The additions of Si<1% and Mn<2% had no effect on the corrosion behavior of HP18Cr-14Ni alloys, and the addition of Si<1% also had no effect on the corrosion behavior of HP18Cr-14Ni-1Mn alloys, although 1% Si induced intergranular corrosion in both the alloys. Thus, HP18Cr-14Ni-1Mn-0.5Si alloys were selected to evaluate the effects of C, P and S (100 ppm each). The addition of P, and the co-addition of C, P, and S to HP18Cr-14Ni-1Mn-0.5Si induced intergranular corrosion of the same degree in the solution annealed condition. This result suggests the synergistic effect of Si and P to induce intergranular corrosion, since the single addition of Si or P to this level did not lead to intergranular corrosion of HP18Cr-14Ni alloys. HP18Cr-14Ni-1Mn-0.5Si alloys containing C, P, and S at the 100 ppm level each showed superior corrosion resistance compared to a commercial Type 304L in 13N nitric acid. (author)

Effect of temperature on corrosion of steels in high purity water

International Nuclear Information System (INIS)

Honda, Takashi; Kashimura, Eiji; Ohashi, Kenya; Furutani, Yasumasa; Ohsumi, Katsumi; Aizawa, Motohiro; Matsubayashi, Hideo.

1987-01-01

Effect of temperature on corrosion behavior of steels was evaluated in the range of 150 - 300 deg C in high purity water containing about 200 ppb oxygen. The exposure tests were carried out in actual and simulated reactor water of BWR plants. Through X-ray diffractometry, SIMS, XPS and chemical analyses, it was clarified that the chemical composition and morphology of oxide films formed on austenitic stainless steel changed above about 250 deg C. Chromium dissolved easily through corrosion above this temperature, and the oxide films primarily consisted of spinel type oxides containing high concentration of nickel. Further, as the protectivety of oxide films increased with temperature, the corrosion rate had a peak around 250 deg C after a long exposure period. A major phase of oxide films on carbon steel was magnetite in the whole temperature range. However, as the oxide films formed at high temperatures had very compact structures, the effect of temperature on the corrosion rate was similar to that observed on stainless steel. (author)

Effect of Inhibitors on Weld Corrosion under Sweet Conditions Using Flow Channel

OpenAIRE

Khaled Alawadhi; Abdulkareem Aloraier; Suraj Joshi; Jalal Alsarraf

2014-01-01

The aim of this paper is to compare the effectiveness and electrochemical behavior of typical oilfield corrosion inhibitors with previous oilfield corrosion inhibitors under the same electrochemical techniques to control preferential weld corrosion of X65 pipeline steel in artificial seawater saturated with carbon dioxide at a pressure of one bar. A secondary aim is to investigate the conditions under which current reversal takes place. A flow channel apparatus was used in the laboratory to s...

The composition effect on the long-term corrosion of high-level waste glass

Energy Technology Data Exchange (ETDEWEB)

Hrma, P. [Pacific Northwest National Laboratory, Richland, Washington (United States)

1997-07-01

Waste glass can be optimized for long-term corrosion behavior if the key parameters that control the rate of corrosion are identified, measured, and modeled as functions of glass composition. Second-order polynomial models have been used to optimize glass with respect to a set of requirements on glass properties, such as viscosity and outcomes of standard corrosion tests. Extensive databases exist for the 7-day Product Consistency Test and the 28-day Materials Characterization Center tests, which have been used for nuclear waste glasses in the United States. Models based on these tests are reviewed and discussed to demonstrate the compositional effects on the extent of corrosion under specified conditions. However, modeling the rate of corrosion is potentially more useful for predicting long-term behavior than modeling the extent of corrosion measured by standard tests. Based on an experimental study of two glasses, it is shown that the rate of corrosion can be characterized by simple functions with physically meaningful coefficients. (author)

Laboratory testing of waste glass aqueous corrosion; effects of experimental parameters

International Nuclear Information System (INIS)

Ebert, W.L.; Mazer, J.J.

1993-01-01

A literature survey has been performed to assess the effects of the temperature, glass surface area/leachate volume ratio, leachant composition, leachant flow rate, and glass composition (actual radioactive vs. simulated glass) used in laboratory tests on the measured glass reaction rate. The effects of these parameters must be accounted for in mechanistic models used to project glass durability over long times. Test parameters can also be utilized to highlight particular processes in laboratory tests. Waste glass corrosion results as water diffusion, ion-exchange, and hydrolysis reactions occur simultaneously to devitrify the glass and release soluble glass components into solution. The rates of these processes are interrelated by the affects of the solution chemistry and glass alteration phases on each process, and the dominant (fastest) process may change as the reaction progresses. Transport of components from the release sites into solution may also affect the observed corrosion rate. The reaction temperature will affect the rate of each process, while other parameters will affect the solution chemistry and which processes are observed during the test. The early stages of corrosion will be observed under test conditions which maintain dilute leachates and the later stages will be observed under conditions that generate more concentrated leachate solutions. Typically, water diffusion and ion-exchange reactions dominate the observed glass corrosion in dilute solutions while hydrolysis reactions dominant in more concentrated solutions. Which process(es) controls the long-term glass corrosion is not fully understood, and the long-term corrosion rate may be either transport- or reaction-limited

Inhibitory effects of Citrus hassaku extract and its flavanone glycosides on melanogenesis.

Science.gov (United States)

Itoh, Kimihisa; Hirata, Noriko; Masuda, Megumi; Naruto, Shunsuke; Murata, Kazuya; Wakabayashi, Keitaro; Matsuda, Hideaki

2009-03-01

The 50% ethanolic extract (CH-ext) obtained from the unripe fruit of Citrus hassaku exhibited significant tyrosinase inhibitory activity. The CH-ext showed antioxidant activity, such as superoxide dismutase (SOD)-like activity and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity. Activity-guided fractionation of the CH-ext indicated that flavanone glycoside-rich fractions showed potent tyrosinase inhibitory activity. Further examination revealed that the tyrosinase inhibitory activity and antioxidant activity of the CH-ext were attributable to naringin and neohesperidin, respectively. The CH-ext showed inhibition of melanogenesis without any effects on cell proliferation in cultured murine B16 melanoma cells after glucosamine exposure. The topical application of the CH-ext to the dorsal skin of brownish guinea pigs showed in vivo preventive effects against UVB-induced pigmentation.

The effect of notches and pits on corrosion fatigue strength

Science.gov (United States)

Tatner, Ian

An investigation has been undertaken to examine the fatigue behaviour of two martensitic steels in air and aggressive environments. The steels studied are, 18% Ni marageing steel and FV520B, the later being a stainless steel turbine blade material and the former being a marageing steel that suffers general corrosion in mild environments. Both steels were heat treated to give similar tensile strength.The design and manufacture of an autoclave allowed push-pull fatigue tests to be conducted in aggressive environments at elevated temperatures.Corrosion potential was monitored using a three electrode cell and was controlled during testing. Base-line fatigue tests were conducted with a range of constant corrosion potentials, using both notched and plain FV520B specimens. In addition fatigue tests with pulsed corrosion potential were performed to asses the effect of transient corrosion conditions on the corrosion fatigue strength. The pulsed tests were designed to simulate service transients in the oxygen content and general chemical hostility in the condensing steam environment during start-up and shut down of the steam turbine.Post test examination of fractured samples was performed using Scanning Electron Microscopy (SEM) and optical microscope techniques. The fractography results were used to quantify microstructural and fracture features of the steels.A model based on the size and geometry of the initial corrosion pitting has been proposed to asses the fatigue life of FV520B in an aggressive environment.The effect of pitting on the corrosion fatigue strength of FV520B has been modelled using linear elastic fracture mechanics (LEFM) type approach. The model has shown a good correlation between predicted fatigue lives with experimental results.The results suggest that the fatigue life is governed by the mechanical stress concentrating effect of the pits rather than the electrochemical damage caused by the environment.Finite Element Analysis (FEA) of the notch allowed

NASA's Corrosion Technology Laboratory at the Kennedy Space Center: Anticipating, Managing, and Preventing Corrosion

Science.gov (United States)

Calle, Luz Marina

2015-01-01

The marine environment at NASAs Kennedy Space Center (KSC) has been documented by ASM International (formerly American Society for Metals) as the most corrosive in North America. With the introduction of the Space Shuttle in 1981, the already highly corrosive conditions at the launch pads were rendered even more severe by the highly corrosive hydrochloric acid (HCl) generated by the solid rocket boosters (SRBs). Numerous failures at the launch pads are caused by corrosion. The structural integrity of ground infrastructure and flight hardware is critical to the success, safety, cost, and sustainability of space missions. NASA has over fifty years of experience dealing with unexpected failures caused by corrosion and has developed expertise in corrosion control in the launch and other environments. The Corrosion Technology Laboratory at KSC evolved, from what started as an atmospheric exposure test site near NASAs launch pads, into a capability that provides technical innovations and engineering services in all areas of corrosion for NASA, external partners, and customers.This paper provides a chronological overview of NASAs role in anticipating, managing, and preventing corrosion in highly corrosive environments. One important challenge in managing and preventing corrosion involves the detrimental impact on humans and the environment of what have been very effective corrosion control strategies. This challenge has motivated the development of new corrosion control technologies that are more effective and environmentally friendly. Strategies for improved corrosion protection and durability can have a huge impact on the economic sustainability of human spaceflight operations.

Evaluation of the flow-accelerated corrosion downstream of an orifice. 2. Measurement of corrosion rate and evaluation on the effects of the flow field

International Nuclear Information System (INIS)

Nagaya, Yukinori; Utanohara, Yoichi; Nakamura, Akira; Murase, Michio

2008-01-01

In this study, in order to evaluate the effects of flow field on corrosion rate due to flow accelerated corrosion (FAC), a corrosion rate downstream of an orifice was measured using the electric resistance method. The diameter of the pipe is 50 mm and that of the orifice is 24.3 mm, and flow velocity of the experimental loop was set at 5m/s, and the temperature of water was controlled within ±1 at 150deg-C. There were no significant circumferential difference in measured corrosion rate, and the maximum corrosion rate was observed at 1D or 2D downstream from the orifice. The ratios of the measured corrosion rate and the calculated wall shear stress at the 1D downstream from the orifice to the value at upstream under well developed flow agreed well. (author)

Radionuclide decay effects on waste glass corrosion and weathering

International Nuclear Information System (INIS)

Wronkiewicz, D.J.

1993-01-01

The release of glass components into solution, including radionuclides, may be influenced by the presence of radiolytically produced nitric acid, carboxylic acid, and transient water dissociation products such as ·OH and O 2 - . Under batch test conditions, glass corrosion has been shown to increase up to a maximum of three-to five-fold in irradiated tests relative to nonirradiated tests, while in other studies the presence of radiolytic products has actually decreased glass corrosion rates. Bicarbonate groundwaters will buffer against pH decreases and changes in corrosion rates. Under high surface area-to-solution volume (S/V) conditions, the bicarbonate buffering reservoir may be quickly overwhelmed by radiolytic acids that are concentrated in the thin films of water contacting the samples. Glass reaction rates have been shown to increase up to 10-to-15-fold due to radiation exposure under high S/V conditions. Radiation damage to solid glass materials results in bond damage and atomic displacements. This type of damage has been shown to increase the release rates of glass components up to four-fold during subsequent corrosion tests, although under actual disposal conditions, glass annealing processes may negate the solid radiation damage effects

The effect of single overloading on stress corrosion cracking

International Nuclear Information System (INIS)

Ito, Yuzuru; Saito, Masahiro

2008-01-01

In the normal course of nuclear power plant operation in Japan, proof testing has been performed after periodic plant inspections. In this proof test procedure, the reactor pressure vessel and pipes of the primary coolant loop are subjected to a specified overload with a slightly higher hydraulic pressure than during normal operation. This specified overload is so called a single overload' in material testing. It is well known that the fatigue crack growth rate is decreased after a single overload has been applied to the specimen. However, it is not clear whether the stress corrosion cracking rate is also decreased after a single overload. In this study, the effect of a single overload on the stress corrosion cracking rate under simulated boiling water reactor environment was evaluated by examining a singly overloaded WOL (wedge opening load) specimen. The WOL specimen for the stress corrosion cracking test was machined from sensitized 304 type austenitic stainless steel. Since the crack extension length was 3.2% longer in the case of a more severely overloaded specimen, it was observed than the stress corrosion cracking rate is also decreased after the single overload has been applied to the specimen. (author)

Effect of hydrogen on the corrosion behavior of the Mg–xZn alloys

Directory of Open Access Journals (Sweden)

Yingwei Song

2014-09-01

Full Text Available Hydrogen evolution reaction is inevitable during the corrosion of Mg alloys. The effect of hydrogen on the corrosion behavior of the Mg–2Zn and Mg–5Zn alloys is investigated by charging hydrogen treatment. The surface morphologies of the samples after charging hydrogen were observed using a scanning electron microscopy (SEM and the corrosion resistance was evaluated by polarization curves. It is found that there are oxide films formed on the surface of the charged hydrogen samples. The low hydrogen evolution rate is helpful to improve the corrosion resistance of Mg alloys, while the high hydrogen evolution rate can increases the defects in the films and further deteriorates their protection ability. Also, the charging hydrogen effect is greatly associated with the microstructure of Mg substrate.

Effect of Zr on the Corrosion Properties of Mg-Li-Al Alloy

International Nuclear Information System (INIS)

Kim, Soon Ho; Choi, Sang Hyun; Kim, In Bae; Kim, Kyung Hyun

1994-01-01

Effect of Zr on the electrochemical corrosion characteristics of Mg-Li-Al alloy has been investigated by means of potentiodynamic polarization study. The electrochemical behaviors were evaluated in 0.03% NaCl solution and the solution buffered with KH 2 PO 5 · NaOH at room temperature. It was found that the addition of very small quantity of Zr (0.03wt%) in Mg-Li-Al alloy increased corrosion rates and amount of corrosion products and decreased the pitting resistance of the alloy. From the results it was concluded that Zr which is added to increase the strength of Mg-Li-Al alloy is harmful to corrosion properties of the alloy

The Effects of Corrosive Chemicals on Corrosion Rate of Steel Reinforcement Bars: I. Swamp Water

Directory of Open Access Journals (Sweden)

Sulistyoweni Widanarko

2010-10-01

Full Text Available Most of infrastructures using steel concrete to reinforce the strength of concrete. Steel concrete is so vulnerable to chemical compounds that can cause corrosion. It can happen due to the presence of chemical compounds in acid environment in low pH level. These chemical compounds are SO42-, Cl-, NO3-. There are many swamp area in Indonesia. The acid contents and the concentration of ion sulphate, chlorides, and nitrate are higher in the swamp water than in the ground water .The objective of this research was to find out the influence of corrosive chemicals in the swamp water to the steel concrete corrosion rate. There were two treatment used: (1 emerging ST 37 and ST 60 within 60 days in the 'polluted' swamp water, (2 moving the ST 37 up and down periodically in the ' polluted' swamp water. Three variation of 'polluted' swamp water were made by increasing the concentration of corrosive chemical up to 1X, 5X and 10X respectively. The corrosion rate was measured by using an Immersion Method. The result of Immersion test showed that chloride had the greatest influence to corrosion rate of ST 37 and ST 60 and followed by sulphate and Nitrate. Corrosion rate value for ST 37 is 24.29 mpy and for ST 60 is 22.76 mpy. By moving the sample up and down, the corrosion rate of ST 37 increase up to 37.59 mpy, and chloride still having the greatest influence, followed by sulphate and nitrate.

In vivo hypotensive effect and in vitro inhibitory activity of some Cyperaceae species

Directory of Open Access Journals (Sweden)

Monica Lacerda Lopes Martins

2013-12-01

Full Text Available In 1820, French naturalist August Saint Hillaire, during a visit in Espírito Santo (ES, a state in southeastern Brazil, reported a popular use of Cyperaceae species as antidote to snake bites. The plant may even have a hypotensive effect, though it was never properly researched. The in vitro inhibitory of the angiotensin converting enzyme (ACE activity of eigth ethanolic extracts of Cyperaceae was evaluated by colorimetric assay. Total phenolic and flavonoids were determined using colorimetric assay. The hypotensive effect of the active specie (Rhychonospora exaltata, ERE and the in vivo ACE assay was measured in vivo using male Wistar Kyoto (ERE, 0.01-100mg/kg, with acetylcholine (ACh as positive control (5 µg/kg, i.v.. The evaluation of ACE in vivo inhibitory effect was performed comparing the mean arterial pressure before and after ERE (10 mg/kg in animals which received injection of angiotensin I (ANG I; 0,03, 03 and 300 µg/kg, i.v.. Captopril (30 mg/kg was used as positive control. Bulbostylis capillaris (86.89 ± 15.20% and ERE (74.89 ± 11.95%, ERE were considered active in the in vitro ACE inhibition assay, at 100 µg/mL concentration. ACh lead to a hypotensive effect before and after ERE's curve (-40±5% and -41±3%. ERE showed a dose-dependent hypotensive effect and a in vivo ACE inhibitory effect. Cyperaceae species showed an inhibitory activity of ACE, in vitro, as well as high content of total phenolic and flavonoids. ERE exhibited an inhibitory effect on both in vitro and in vivo ACE. The selection of species used in popular medicine as antidotes, along with the in vitro assay of ACE inhibition, might be a biomonitoring method for the screening of new medicinal plants with hypotensive properties.

The effects of the glass surface area/solution volume ratio on glass corrosion: A critical review

International Nuclear Information System (INIS)

Ebert, W.L.

1995-03-01

This report reviews and summarizes the present state of knowledge regarding the effects of the glass surface area/solution volume (SA/V) ratio on the corrosion behavior of borosilicate waste glasses. The SA/V ratio affects the rate of glass corrosion through the extent of dilution of corrosion products released from the glass into the leachate solution: glass corrosion products are diluted more in tests conducted at low SA/V ratios than they are in tests conducted at high SA/V ratios. Differences in the solution chemistries generated in tests conducted at different SA/V ratios then affect the observed glass corrosion behavior. Therefore, any testing parameter that affects the solution chemistry will also affect the glass corrosion rate. The results of static leach tests conducted to assess the effects of the SA/V are discussed with regard to the effects of SA/V on the solution chemistry. Test results show several remaining issues with regard to the long-term glass corrosion behavior: can the SA/V ratio be used as an accelerating parameter to characterize the advanced stages of glass corrosion relevant to long disposal times; is the alteration of the glass surface the same in tests conducted at different SA/V, and in tests conducted with monolithic and crushed glass samples; what are the effects of the SA/V and the extent of glass corrosion on the disposition of released radionuclides? These issues will bear on the prediction of the long-term performance of waste glasses during storage. The results of an experimental program conducted at ANL to address these and other remaining issues regarding the effects of SA/V on glass corrosion are described. 288 refs., 59 figs., 16 tabs

The effects of the glass surface area/solution volume ratio on glass corrosion: A critical review

Energy Technology Data Exchange (ETDEWEB)

Ebert, W.L. [Argonne National Lab., IL (United States). Chemical Technology Div.

1995-03-01

This report reviews and summarizes the present state of knowledge regarding the effects of the glass surface area/solution volume (SA/V) ratio on the corrosion behavior of borosilicate waste glasses. The SA/V ratio affects the rate of glass corrosion through the extent of dilution of corrosion products released from the glass into the leachate solution: glass corrosion products are diluted more in tests conducted at low SA/V ratios than they are in tests conducted at high SA/V ratios. Differences in the solution chemistries generated in tests conducted at different SA/V ratios then affect the observed glass corrosion behavior. Therefore, any testing parameter that affects the solution chemistry will also affect the glass corrosion rate. The results of static leach tests conducted to assess the effects of the SA/V are discussed with regard to the effects of SA/V on the solution chemistry. Test results show several remaining issues with regard to the long-term glass corrosion behavior: can the SA/V ratio be used as an accelerating parameter to characterize the advanced stages of glass corrosion relevant to long disposal times; is the alteration of the glass surface the same in tests conducted at different SA/V, and in tests conducted with monolithic and crushed glass samples; what are the effects of the SA/V and the extent of glass corrosion on the disposition of released radionuclides? These issues will bear on the prediction of the long-term performance of waste glasses during storage. The results of an experimental program conducted at ANL to address these and other remaining issues regarding the effects of SA/V on glass corrosion are described. 288 refs., 59 figs., 16 tabs.

Effect of Copper on Passivity and Corrosion Behavior of Fe-xC-5Cu ...

African Journals Online (AJOL)

... copper/microstructure is discussed. Alloying Cu showed a beneficial effect on hypoeutectoid steel and harmful effect on hypereutectoid steel. The improved corrosion resistance is related to cementite morphology and by a copper dissolution/re-deposition process. Keywords: Corrosion; Copper; cementite; EIS; Passivation ...

Corrosion and stress corrosion cracking in supercritical water

Science.gov (United States)

Was, G. S.; Ampornrat, P.; Gupta, G.; Teysseyre, S.; West, E. A.; Allen, T. R.; Sridharan, K.; Tan, L.; Chen, Y.; Ren, X.; Pister, C.

2007-09-01

Supercritical water (SCW) has attracted increasing attention since SCW boiler power plants were implemented to increase the efficiency of fossil-based power plants. The SCW reactor (SCWR) design has been selected as one of the Generation IV reactor concepts because of its higher thermal efficiency and plant simplification as compared to current light water reactors (LWRs). Reactor operating conditions call for a core coolant temperature between 280 °C and 620 °C at a pressure of 25 MPa and maximum expected neutron damage levels to any replaceable or permanent core component of 15 dpa (thermal reactor design) and 100 dpa (fast reactor design). Irradiation-induced changes in microstructure (swelling, radiation-induced segregation (RIS), hardening, phase stability) and mechanical properties (strength, thermal and irradiation-induced creep, fatigue) are also major concerns. Throughout the core, corrosion, stress corrosion cracking, and the effect of irradiation on these degradation modes are critical issues. This paper reviews the current understanding of the response of candidate materials for SCWR systems, focusing on the corrosion and stress corrosion cracking response, and highlights the design trade-offs associated with certain alloy systems. Ferritic-martensitic steels generally have the best resistance to stress corrosion cracking, but suffer from the worst oxidation. Austenitic stainless steels and Ni-base alloys have better oxidation resistance but are more susceptible to stress corrosion cracking. The promise of grain boundary engineering and surface modification in addressing corrosion and stress corrosion cracking performance is discussed.

Overview of Corrosion, Erosion, and Synergistic Effects of Erosion and Corrosion in the WTP Pre-treatment Facility

Energy Technology Data Exchange (ETDEWEB)

Imrich, K. J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2015-03-27

Corrosion is an extremely complex process that is affected by numerous factors. Addition of a flowing multi-phase solution further complicates the analysis. The synergistic effects of the multiple corrosive species as well as the flow-induced synergistic effects from erosion and corrosion must be thoroughly evaluated in order to predict material degradation responses. Public domain data can help guide the analysis, but cannot reliably provide the design basis especially when the process is one-of-a-kind, designed for 40 plus years of service, and has no viable means for repair or replacement. Testing in representative simulants and environmental conditions with prototypic components will provide a stronger technical basis for design. This philosophy was exemplified by the Defense Waste Processing Facility (DWPF) at the Savannah River Site and only after 15 plus years of successful operation has it been validated. There have been “hiccups”, some identified during the cold commissioning phase and some during radioactive operations, but they were minor and overcome. In addition, the system is robust enough to tolerate most flowsheet changes and the DWPF design allows minor modifications and replacements – approaches not available with the Hanford Waste Treatment Plant (WTP) “Black Cell” design methodology. Based on the available data, the synergistic effect between erosion and corrosion is a credible – virtually certain – degradation mechanism and must be considered for the design of the WTP process systems. Testing is recommended due to the number of variables (e.g., material properties, process parameters, and component design) that can affect synergy between erosion and corrosion and because the available literature is of limited applicability for the complex process chemistries anticipated in the WTP. Applicable testing will provide a reasonable and defensible path forward for design of the WTP Black Cell and Hard-to-Reach process equipment. These

The effect of recrystallization on corrosion and electrochemical behavior of 7150 Al alloy

Energy Technology Data Exchange (ETDEWEB)

Peng, G.S.; Chen, K.H.; Fang, H.C.; Chen, S.Y.; Chao, H. [State Key Laboratory for Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)

2011-01-15

By weight loss, potentiodynamic polarization, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) techniques complemented by optical and scanning electron microscopy observations, the effect of recrystallization on the corrosion, and electrochemical behavior of 7150 Al alloy was studied. The results indicated that the high recrystallization fraction 7150-1 was worse than the low recrystallization fraction 7150-2 on corrosion resistance. The analysis of EIS indicated that 7150-1 exhibited obvious pitting corrosion at 5 h immersion time, whereas 7150-2 showed no obvious pitting corrosion even at 33 h. The corrosion route developed along the grain boundary of recrystallization grains, not along the grain boundary of unrecrystallization grains. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Mechanism and degree of chemical elements effect on atmosphere corrosion resistance of steels

International Nuclear Information System (INIS)

Vu Din' Vuj

1991-01-01

It follows from the proposed regression equations that falourable effect of chemical elements on steel resistance to atmospheric corrosion is determined by their ability to increase interatom bond stability in iron crystal lattice and form corrosion products with high protection properties. Element positive influence on steel corrosion resistance decreases in the following order: S, P, Si, Mn, Cu, Cr, Ni, C in semiurban tropical atmosphere and S, Mn, Sr, Cu, Ni, Cr in coastal atmosphere. In the latter case C increases corrosion in a greater degree as compared to P. Small ammounts of Mo decrease steel resistance in semiurban atmosphere and almost do not influence it in the coastal one. Possible mechanisms of individual element influence on steel corrosion resistance are considered

Effect of Surface Precipitate on the Crevice Corrosion in HYBRID and Oxalic Acid Solution

International Nuclear Information System (INIS)

Park, S. Y.; Jung, J. Y.; Won, H. J.; Kim, S. B.; Choi, W. K.; Moon, J. K.; Park, S. J.

2015-01-01

In this study, we investigated the characteristics of the crevice corrosion for Inconel-600 and 304SS in OA solution according to the change in pH. The evaluation of the crevice corrosion with the chemical thermodynamic analysis identified the effect of the residual chemicals such as iron-oxalate and nickeloxalate to the crevice corrosion behavior. Test results were compared with those of HYBRID (HYdrizine Base Reductive metal Ion Decontamination). The crevice corrosion properties of 304 SS and Inconel-600 in HYBRID and oxalic acid solution were evaluated. In case of oxalic acid solution, the corrosion rate on 304SS was rapidly increased with a pH decrease of around 2, but there was no increase in the corrosion rate on Inconel-600

Inhibitory effect of trans-caryophyllene (TC) on leukocyte-endothelial attachment.

Science.gov (United States)

Zhang, Zhen; Yang, Chunfeng; Dai, Xinlun; Ao, Yu; Li, Yumei

2017-08-15

trans-Caryophyllene (TC) is a major component found in the essential oils of many spices and foods/medicinal plants. It is a natural sesquiterpene and has been the subject of numerous studies. However, the effects of TC on vascular inflammation remain unknown. In this study, we reported that TC treatment in human umbilical vein endothelial cells (HUVECs) prevented attachment of monocytic leukemia cell line THP-1 cells to endothelial cells. In addition, in vivo results indicate that TC inhibited macrophage infiltration to the aortic surface and reduced total serum levels of cholesterol and triglycerides. Importantly, administration of TC could inhibit the induction of vascular cell adhesion molecule-1 (VCAM-1) both in vitro and in vivo. Notably, our data indicate that the inhibitory effects of TC on the expression of VCAM-1 are mediated by the JAK2/STAT1/IRF-1 pathway. TC is a specific agonist of the type 2 cannabinoid receptor (CB2R). Importantly, we further verified that the inhibitory effects of TC on the expression of IRF-1 and VCAM-1 are dependent on activation of CB2R. Inhibition of CB2R by either specific inhibitors or RNA interference abolished the inhibitory effects of TC on the expression of IRF-1 and VCAM-1. Our results suggest that TC might have a capacity to suppress the development of atherosclerosis. Copyright © 2017 Elsevier Inc. All rights reserved.

Corrosion inhibition of carbon steel XC70 in H 2 SO 4 solution by ...

African Journals Online (AJOL)

In this work, we studied the efficiency of corrosion inhibition of carbon steel XC70 in H2SO4 0.5 M aqueous solution using ferrocenyl derivatives synthesized in our laboratory, this compound is: 3-(ferrocenylmethylamine)benzonitrile. The inhibitory potential of this compound was determined by electrochemical techniques ...

Quantitative evaluation of inhibitory effect of various substances on anaerobic ammonia oxidation (anammox).

Science.gov (United States)

Nakamura, Tomotaka; Harigaya, Yuhki; Kimura, Yuya; Kuroiwa, Megumi; Kurata, Yuhri; Isaka, Kazuichi; Suwa, Yuichi

2017-09-01

The inhibitory effect of 20 substances of various chemical species on the anaerobic ammonia oxidation (anammox) activity of an enrichment culture, predominated by Candidatus Brocadia, was determined systematically by using a 15 N tracer technique. The initial anammox rate was determined during first 25 min with a small-scale anaerobic batch incubation supplemented with possible inhibitors. Although Cu 2+ and Mn 2+ did not inhibit anammox, the remaining 18 substances [Ni 2+ , Zn 2+ , Co 2+ , [Formula: see text] , Fe 2+ , 4 amines, ethylenediaminetetraacetic acid (EDTA), ethylenediamine-N,N'-bis (2-hydroxyphenylacetic acid) (EDDHA), citric acid, nitrilotriacetic acid (NTA), N,N-dimethylacetamide (DMA), 1,4-dioxane, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF) and tetrahydrofuran (THF)] were inhibitory. Inhibitory effect of NTA, EDDHA, THF, DMF, DMA and amines on anammox was first determined in this study. Inhibitory effects of metals were re-evaluated because chelators, which may interfere inhibitory effect, have been used to dissolve metal salts into assay solution. The relative anammox activities as a function of concentration of each substance were described successfully (R 2  > 0.91) either with a linear inhibition model or with a Michaelis-Menten-based inhibition model. IC 50 values were estimated based on either model, and were compared. The IC 50 values of the 4 chelators (0.06-2.7 mM) and 5 metal ions (0.02-1.09 mM) were significantly lower than those of the 4 amines (10.6-29.1 mM) and 5 organic solvents (3.5-82 mM). Although it did not show any inhibition within 25 min, 0.1 mM Cu 2+ completely inhibited anammox activity in 240 min, suggesting that the inhibitory effect caused by Cu 2+ is time-dependent. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Effects of amalgam corrosion products on human cells

Energy Technology Data Exchange (ETDEWEB)

Goldschmidt, P R; Cogen, R B; Taubman, S B [Departments of Periodontics and Pathology, University of Connecticut Health Center, Farmington, Connecticut, U.S.A.

1976-01-01

Using three independent criteria, we have found that 10/sup -4/,10/sup -6/M concentrations of ions presumably liberated from the corrosion of dental amalgam produce injurious effects on either human gingival fibroblasts or HeLa cells when the cells are grown in culture. Release of /sup 51/Cr and uptake of trypan blue dye were seen with 10/sup -5/M Hg/sup + +/ and Ag/sup +/. Inhibition of amino acid incorporation into protein-like material was seen with eluates of amalgam and with ionic solutions of most metals comprising dental amalgam. Stannous ion showed little if any cytotoxic potential. These results suggest that corrosion products of amalgam are capable of causing cellular injury or destruction.

Corrosion/96 conference papers

International Nuclear Information System (INIS)

Anon.

1996-01-01

Topics covered by this conference include: cathodic protection in natural waters; cleaning and repassivation of building HVAC systems; worldwide opportunities in flue gas desulfurization; advancements in materials technology for use in oil and gas service; fossil fuel combustion and conversion; technology of corrosion inhibitors; computers in corrosion control--modeling and information processing; recent experiences and advances of austenitic alloys; managing corrosion with plastics; corrosion measurement technology; corrosion inhibitors for concrete; refining industry; advances in corrosion control for rail and tank trailer equipment; CO 2 corrosion--mechanisms and control; microbiologically influenced corrosion; corrosion in nuclear systems; role of corrosion in boiler failures; effects of water reuse on monitoring and control technology in cooling water applications; methods and mechanisms of scale and deposit control; corrosion detection in petroleum production lines; underground corrosion control; environmental cracking--relating laboratory results and field behavior; corrosion control in reinforced concrete structures; corrosion and its control in aerospace and military hardware; injection and process addition facilities; progress reports on the results of reinspection of deaerators inspected or repaired per RP0590 criteria; near 100% volume solids coating technology and application methods; materials performance in high temperature environments containing halides; impact of toxicity studies on use of corrosion/scale inhibitors; mineral scale deposit control in oilfield related operations; corrosion in gas treating; marine corrosion; cold climate corrosion; corrosion in the pulp and paper industry; gaseous chlorine alternatives in cooling water systems; practical applications of ozone in recirculating cooling water systems; and water reuse in industry. Over 400 papers from this conference have been processed separately for inclusion on the data base

Corrosion of metallic materials. Dry corrosion, aqueous corrosion and corrosion by liquid metal, methods of protection

International Nuclear Information System (INIS)

Helie, Max

2015-01-01

This book is based on a course on materials given in an engineering school. The author first gives an overview of metallurgy issues: metallic materials (pure metals, metallic alloys), defects of crystal lattices (point defects, linear defects or dislocations), equilibrium diagrams, steels and cast, thermal processing of steels, stainless steels, aluminium and its alloys, copper and its alloys. The second part addresses the properties and characterization of surfaces and interfaces: singularity of a metal surface, surface energy of a metal, energy of grain boundaries, adsorption at a material surface, metal-electrolyte interface, surface oxide-electrolyte interface, techniques of surface analysis. The third chapter addresses the electrochemical aspects of corrosion: description of the corrosion phenomenon, free enthalpy of a compound and free enthalpy of a reaction, case of dry corrosion (thermodynamic aspect, Ellingham diagram, oxidation mechanisms, experimental study, macroscopic modelling), case of aqueous corrosion (electrochemical thermodynamics and kinetics, experimental determination of corrosion rate). The fourth part addresses the different forms of aqueous corrosion: generalized corrosion (atmospheric corrosion, mechanisms and tests), localized corrosion (galvanic, pitting, cracking, intergranular, erosion and cavitation), particular cases of stress cracking (stress corrosion, fatigue-corrosion, embrittlement by hydrogen), and bi-corrosion (of non alloyed steels, of stainless steels, and of aluminium and copper alloys). The sixth chapter addresses the struggle and the protection against aqueous corrosion: methods of prevention, scope of use of main alloys, geometry-based protection of pieces, use of corrosion inhibitors, use of organic or metallic coatings, electrochemical protection. The last chapter proposes an overview of corrosion types in industrial practices: in the automotive industry, in the oil industry, in the aircraft industry, and in the

The effects of Nitinol phases on corrosion and fatigue behavior

Science.gov (United States)

Denton, Melissa

The purpose of these studies was to provide a detailed understanding of Nitinol phases and their effects on corrosion and fatigue life. The two primary phases, austenite and martensite, were carefully evaluated with respect to material geometry, corrosion behavior, wear, and fatigue life. Material characterization was performed using several techniques that include metallography, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), x-ray photoelectron spectrum (XPS), and Auger electron spectroscopy (AES). Uniaxial tensile tests were conducted to determine the mechanical properties such as elongation, ultimate tensile strength, modulus, transformation strain, and plateau stress. In addition, accelerated wear testing and four point bend fatigue testing were completed to study the fatigue life and durability of the material. The corrosion of Nitinol was found to be dependent on various surface conditions. Electrochemical corrosion behavior of each phase was investigated using cyclic potentiodyamic polarization testing. The corrosion response of electropolished Nitinol was found to be acceptable, even after durability testing. Stress-induced martensite had a lower breakdown potential due to a rougher surface morphology, while thermally induced martensite and austenite performed similarly well. The surface conditioning also had a significant effect on Nitinol mechanical properties. Electropolishing provided a smooth mirror finish that reduced localized texture and enhanced the ductility of the material. Quasi-static mechanical properties can be good indicators of fatigue life, but further fatigue testing revealed that phase transformations had an important role as well. The governing mechanisms for the fatigue life of Nitinol were determined to be both martesitic phase transformations and surface defects. A new ultimate dislocation strain model was proposed based on specific accelerated step-strain testing.

Inhibitory effect of propolis on the development of AA amyloidosis.

Science.gov (United States)

Harata, Daichi; Tsuchiya, Yuya; Miyoshi, Tomoyuki; Yanai, Tokuma; Suzuki, Kazuhiko; Murakami, Tomoaki

2018-04-01

In the several types of amyloidoses, participation of oxidative stresses in the pathogenesis and the effect of antioxidants on amyloidosis have been reported. Meanwhile, the relationship between oxidative stresses and pathogenesis of amyloid A (AA) amyloidosis is still unclear. In this study, we used an antioxidant, Brazilian propolis, to investigate the inhibitory effects on AA amyloidosis. The results showed that AA deposition was inhibited by administration of propolis. Increased expression of antioxidant markers was detected in molecular biological examinations of mice treated with propolis. Although serum amyloid A (SAA) levels were strongly correlated with the immunoreactive area of AA deposits in the control group, the correlation was weaker in the propolis-treated groups. In addition, there were no changes in SAA levels between the control group and the propolis-treated groups. The results indicate that propolis, an antioxidant, may induce inhibitory effects against AA amyloidosis.

Inhibitory Effect of Polysaccharides from Scutellaria barbata D. Don ...

African Journals Online (AJOL)

Purpose: To investigate the inhibitory effect of polysaccharides from Scutellaria barbata (PSB) on invasion and metastasis of lung cancer, and study the possible mechanism. Methods: PSB was extracted with water and by alcohol precipitation, and purified by DEAE-52 column chromatography. A highly invasive and ...

Assessing Level and Effectiveness of Corrosion Education in the UAE

OpenAIRE

Lim, Hwee Ling

2012-01-01

The consequences of corrosion can be minimized by an engineering workforce well trained in corrosion fundamentals and management. Since the United Arab Emirates incurs the second highest cost of corrosion after Saudi Arabia, this paper examined the quality of corrosion education in the UAE. Surveys with academia and industry respondents showed that dedicated corrosion courses and engineering courses that integrated corrosion into the curricula were available in UAE universities, but graduates...

The Corrosion Inhibition Characteristics of Sodium Nitrite Using an On-line Corrosion Rate Measurement System

International Nuclear Information System (INIS)

Park, Mal-Yong; Kang, Dae-Jin; Moon, Jeon-Soo

2015-01-01

An on-line corrosion rate measurement system was developed using a personal computer, a data acquisition board and program, and a 2-electrode corrosion probe. Reliability of the developed system was confirmed with through comparison test. With this system, the effect of sodium nitrite (NaNO 2 ) as a corrosion inhibitor were studied on iron and aluminum brass that were immersed in sodium chloride (NaCl) solution. Corrosion rate was measured based on the linear polarization resistance method. The corrosion rates of aluminum brass and iron in 1% NaCl solutions were measured to be 0.290 mm per year (mmpy) and 0.2134 mmpy, respectively. With the addition of 200 ppm of NO 2 - , the corrosion rates decreased to 0.0470 mmpy and 0.0254 mmpy. The addition of NO 2 - caused a decrease in corrosion rates of both aluminum brass and iron, yet the NO 2 - acted as a more effective corrosion inhibitor for iron. than aluminum brass

Effect of load deflection on corrosion behavior of NiTi wire.

Science.gov (United States)

Liu, I H; Lee, T M; Chang, C Y; Liu, C K

2007-06-01

For dental orthodontic applications, NiTi wires are used under bending conditions in the oral environment for a long period. The purpose of this study was to investigate the effect of bending stress on the corrosion of NiTi wires using potentiodynamic and potentiostatic tests in artificial saliva. The results indicated that bending stress induces a higher corrosion rate of NiTi wires in passive regions. It is suggested that the passive oxide film of specimens would be damaged under bending conditions. Auger electron spectroscopic analysis showed a lower thickness of passive films on stressed NiTi wires compared with unstressed specimens in the passive region. By scanning electron microscopy, localized corrosion was observed on stressed Sentalloy specimens after a potentiodynamic test at pH 2. In conclusion, this study indicated that bending stress changed the corrosion properties and surface characteristics of NiTi wires in a simulated intra-oral environment.

The effect of Ti(CN/TiNb(CN coating on erosion–corrosion resistance

Directory of Open Access Journals (Sweden)

William Aperador Chaparro

2012-05-01

Full Text Available The goal of this work was to study electrochemical behaviour in corrosion-erosion conditions for Ti(CN/TiNb(CN multilayer coatings having 1, 50, 100, 150 and 200 bilayer periods on AISI 4140 steel substrates by using a multi-target magnetron reactive sputtering device, with an r.f. source (13.56 MHz, two cylindrical magnetron cathodes and two stoichiometric TiC and Nb targets. The multi-layers were evaluated by comparing them to corrosion, erosion and erosion corrosion for a 30º impact angle in a solution of 0.5 M NaCl and silica, analysing the effect of impact angle and the number of bilayers on these coatings’ corrosion resistance. The electrochemical characterisation was performed using electrochemical impedance spectroscopy for analysing corrosion surface; surface morphology was characterised by using a high-resolution scanning electron microscope (SEM. The results showed a de-creased corrosion rate for multilayer systems tested at 30°.

Effect of Equal-Channel Angular Pressing on Pitting Corrosion of Pure Aluminum

Directory of Open Access Journals (Sweden)

Injoon Son

2012-01-01

Full Text Available The effect of equal-channel angular pressing (ECAP on the pitting corrosion of pure Al was investigated using electrochemical techniques in solutions containing 0.1 m mol·dm−3 of Na2SO4 and 8.46 mol·dm−3 of NaCl (300 ppm Cl− and followed by surface analysis. The potential for pitting corrosion of pure Al was clearly shifted in the noble direction by the ECAP process indicating that this process improves resistance to pitting corrosion. The time dependence of corrosion potential and the anodic potential at 1 A·m−2 revealed that the rate of formation of Al oxide films increased due to a decrease in the grain size of the Al after ECAP. Since there exists a negligible amount of impurity precipitates in pure Al, the improvement in pitting corrosion resistance of pure Al by ECAP appears to be attributable to an increase in the rate of formation of Al oxide films.

Radiometric investigation of effect of decontamination agents on corrosion behavior of structural materials for nuclear power engineering

International Nuclear Information System (INIS)

Silber, R.; Ecksteinova, A.

1987-01-01

The tracer technique is used in monitoring corrosion behaviour of high-alloy steels used as structural materials in nuclear power engineering. Radioisotopes 59 Fe, 51 Cr, 58 Co and 60 Co produced by neutron irradiation of steel are mainly used for labelling steel components. The actual corrosion test proceeds in a facility whose description is given. The facility allows automatic sampling of corrosion medium fractions in preset intervals. The fractions are evaluated using a multi-channel analyzer with a Ge(Li) detector. The method can be applied in, e.g., monitoring extraction corrosion, the effect of decontamination agents on the corrosion of alloy steels and the effect of heat treatment of steels of their corrosion resistance in a model corrosion environment. (Z.M.). 2 fig., 1 tab., 5 refs

A High-Performance Corrosion-Resistant Iron-Based Amorphous Metal - The Effects of Composition, Structure and Environment on Corrosion Resistance

International Nuclear Information System (INIS)

Farmer, J.; Haslam, J.; Day, D.; Lian, T.; Saw, C.; Hailey, P.; Choi, J.S.; Rebak, R.; Yang, N.; Bayles, R.; Aprigliano, L.; Payer, J.; Perepezko, J.; Hildal, K.; Lavernia, E.; Ajdelsztajn, L.; Branagan, D.; Beardsley, B.

2007-01-01

The passive film stability of several Fe-based amorphous metal formulations have been found to be comparable to that of high-performance Ni-based alloys, and superior to that of stainless steels, based on electrochemical measurements of the passive film breakdown potential and general corrosion rates. Chromium (Cr), molybdenum (Mo) and tungsten (W) provide corrosion resistance; boron (B) enables glass formation; and rare earths such as yttrium (Y) lower critical cooling rate (CCR). The high boron content of this particular amorphous metal also makes it an effective neutron absorber, and suitable for criticality control applications, as discussed in companion publications. Corrosion data for SAM2X5 (Fe 49.7 Cr 17.7 Mn 1.9 Mo 7.4 W 1.6 B 15.2 C 3.8 Si 2.4 ) is discussed here. (authors)

The Effect of Fly Ash on the Corrosion Behaviour of Galvanised Steel Rebarsin Concrete

Science.gov (United States)

Tittarelli, Francesca; Mobili, Alessandra; Bellezze, Tiziano

2017-08-01

The effect of fly ash on the corrosion behaviour of galvanised steel rebars in cracked concrete specimens exposed to wet-dry cycles in a chloride solution has been investigated. The obtained results show that the use of fly ash, replacing either cement or aggregate, always improves the corrosion behaviour of galvanised steel reinforcements. In particular, the addition of fly ash, even in the presence of concrete cracks, decreases the corrosion rate monitored in very porous concretes, as those with w/c = 0.80, to values comparable with those obtained in good quality concretes, as those with w/c = 0.45. Therefore, fly ash cancels the negative effect, at least from the corrosion point of view, of a great porosity of the cement matrix.

NASA's Corrosion Technology Laboratory at the Kennedy Space Center: Anticipating, Managing, and Preventing Corrosion

Science.gov (United States)

Calle, Luz Marina

2014-01-01

Corrosion is the degradation of a material that results from its interaction with the environment. The marine environment at NASAs Kennedy Space Center (KSC) has been documented by ASM International (formerly American Society for Metals) as the most corrosive in the United States. With the introduction of the Space Shuttle in 1981, the already highly corrosive conditions at the launch pads were rendered even more severe by the 70 tons of highly corrosive hydrochloric acid that were generated by the solid rocket boosters. Numerous failures at the launch pads are caused by corrosion.The structural integrity of ground infrastructure and flight hardware is critical to the success, safety, cost, and sustainability of space missions. As a result of fifty years of experience with launch and ground operations in a natural marine environment that is highly corrosive, NASAs Corrosion Technology Laboratory at KSC is a major source of corrosion control expertise in the launch and other environments. Throughout its history, the Laboratory has evolved from what started as an atmospheric exposure facility near NASAs launch pads into a world-wide recognized capability that provides technical innovations and engineering services in all areas of corrosion for NASA and external customers.This presentation will provide a historical overview of the role of NASAs Corrosion Technology in anticipating, managing, and preventing corrosion. One important challenge in managing and preventing corrosion involves the detrimental impact on humans and the environment of what have been very effective corrosion control strategies. This challenge has motivated the development of new corrosion control technologies that are more effective and environmentally friendly. Strategies for improved corrosion protection and durability can have a huge impact on the economic sustainability of human spaceflight operations.

In vitro evaluation of inhibitory effect of Phoenix dactylifera bark ...

African Journals Online (AJOL)

investigate its in vitro inhibitory effects on lipid peroxidation in the brain, liver, and kidney tissues of rat, ... diseases associated with lipid peroxidation such as cancers and Alzheimer's disease, but further studies ... the family Arecaceae.

Adsorption behavior of caffeine as a green corrosion inhibitor for copper

International Nuclear Information System (INIS)

Souza, Fernando Sílvio de; Giacomelli, Cristiano; Gonçalves, Reinaldo Simões; Spinelli, Almir

2012-01-01

Electrochemical and impedance experiments were carried out to evaluate the corrosion behavior of copper in aerated 0.1 mol L −1 H 2 SO 4 solutions in the presence of three xanthine derivatives with similar chemical structures. The corrosion rate of copper was found to increase in the presence of theophylline and theobromine and decrease in the presence of caffeine. The adsorption and inhibitory effect of caffeine on copper surfaces in aerated 0.1 mol L −1 H 2 SO 4 solutions were then investigated in detail by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), contact angle measurements, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and fluorescence experiments. The data obtained indicate that caffeine behaves as a cathodic-type inhibitor adsorbing onto the copper surface according to the Temkin isotherm, with the negative ∆G° ads value of − 31.1 kJ mol −1 signifying a spontaneous adsorption process. The corrosion inhibition efficiency increased with caffeine concentration in the range of 1.0–10.0 mmol L −1 . Furthermore, the EIS results obtained at the open-circuit potential and surface analysis (SEM, EDS and fluorescence) clearly demonstrated the adsorption of the organic compound onto the copper electrode. The contact angle measurements revealed the formation of a hydrophobic protective film. This film covers up to 72% of the total active surface, acts as a protective barrier and prevents interaction between the metal, water and oxygen molecules. - Highlights: ► We have investigated the adsorption and corrosion inhibition of caffeine on copper surfaces. ► Caffeine behaves as a cathodic-type inhibitor. ► Caffeine adsorbs onto copper surface according to Temkin isotherm. ► There exists the formation of a hydrophobic film that acts as a protective barrier. ► This corrosion inhibitor covers up to 72% of the total active surface of copper.

Safe corrosion inhibitor for treating cooling water on heat power engineering plants

Science.gov (United States)

Nikolaeva, L. A.; Khasanova, D. I.; Mukhutdinova, E. R.; Safin, D. Kh.; Sharifullin, I. G.

2017-08-01

Heat power engineering (HPE) consumes significant volumes of water. There are, therefore, problems associated with corrosion, biological fouling, salt deposits, and sludge formation on functional surfaces of heat power equipment. One of the effective ways to solve these problems is the use of inhibitory protection. The development of new Russian import-substituting environmentally friendly inhibitors is very relevant. This work describes experimental results on the OPC-800 inhibitor (TU 2415-092-00206 457-2013), which was produced at Karpov Chemical Plant and designed to remove mineral deposits, scale, and biological fouling from the surfaces of water-rotation node systems on HPE objects. This reagent is successfully used as an effective corrosion inhibitor in the water recycling systems of Tatarstan petrochemical enterprises. To save fresh make-up water, the circulating system is operated in a no-blow mode, which is characterized by high evaporation and salt content coefficients. It was experimentally found that corrosion rate upon treatment of recycled water with the OPC-800 inhibitor is 0.08-0.10 mm/year. HPE mainly uses inhibitors based on oxyethylidene diphosphonic (OEDPA) and nitrilotrimethylphosphonic (NTMPA) acids. The comparative characteristic of inhibition efficiency for OPC-800 and OEDF-Zn-U2 is given. The results obtained indicate that OPC-800 can be used as an inhibitor for treatment of cooling water in HPE plants. In this case, it is necessary to take into account the features of water rotation of a thermal power plant.

Zinc Addition Effects on General Corrosion of Austenitic Stainless Steels in PWR Primary Conditions

International Nuclear Information System (INIS)

Qiao Peipeng; Zhang Lefu; Liu Ruiqin; Jiang Suqing; Zhu Fawen

2010-01-01

Zinc addition effects on general corrosion of austenitic stainless steel 316 and 304 were investigated in simulated PWR primary coolant without zinc or with 50 ppb zinc addition at 315 degree C for 500 h. The results show that with the addition of zinc, the corrosion rate of austenitic stainless steel is effectively reduced, the surface oxide film is thinner, the morphology and chemical composition of surface oxide scales are evidently different from those without zinc. There are needle-like corrosion products on the surface of stainless steel 304. (authors)

Effects of microbial redox cycling of iron on cast iron pipe corrosion in drinking water distribution systems.

Science.gov (United States)

Wang, Haibo; Hu, Chun; Zhang, Lili; Li, Xiaoxiao; Zhang, Yu; Yang, Min

2014-11-15

Bacterial characteristics in corrosion products and their effect on the formation of dense corrosion scales on cast iron coupons were studied in drinking water, with sterile water acting as a reference. The corrosion process and corrosion scales were characterized by electrochemical and physico-chemical measurements. The results indicated that the corrosion was more rapidly inhibited and iron release was lower due to formation of more dense protective corrosion scales in drinking water than in sterile water. The microbial community and denitrifying functional genes were analyzed by pyrosequencing and quantitative polymerase chain reactions (qPCR), respectively. Principal component analysis (PCA) showed that the bacteria in corrosion products played an important role in the corrosion process in drinking water. Nitrate-reducing bacteria (NRB) Acidovorax and Hydrogenophaga enhanced iron corrosion before 6 days. After 20 days, the dominant bacteria became NRB Dechloromonas (40.08%) with the protective corrosion layer formation. The Dechloromonas exhibited the stronger corrosion inhibition by inducing the redox cycling of iron, to enhance the precipitation of iron oxides and formation of Fe3O4. Subsequently, other minor bacteria appeared in the corrosion scales, including iron-respiring bacteria and Rhizobium which captured iron by the produced siderophores, having a weaker corrosion-inhibition effect. Therefore, the microbially-driven redox cycling of iron with associated microbial capture of iron caused more compact corrosion scales formation and lower iron release. Copyright © 2014 Elsevier Ltd. All rights reserved.

Determinants of aggressive behavior: Interactive effects of emotional regulation and inhibitory control.

Directory of Open Access Journals (Sweden)

I-Ju Hsieh

Full Text Available Aggressive behavior can be defined as any behavior intended to hurt another person, and it is associated with many individual and social factors. This study examined the relationship between emotional regulation and inhibitory control in predicting aggressive behavior. Seventy-eight participants (40 males completed self-report measures (Negative Mood Regulation Scale and Buss-Perry Aggression Questionnaire, a stop signal task, and engaged in a modified version of Taylor Aggression Paradigm (TAP exercise, in which the outcome was used as a measure of direct physical aggression. We used a hierarchical, mixed-model multiple regression analysis test to examine the effects of emotion regulation and inhibitory control on physical reactive aggression. Results indicated an interaction between emotion regulation and inhibitory control on aggression. For participants with low inhibitory control only, there was a significant difference between high and low emotion regulation on aggression, such that low emotion regulation participants registered higher aggression than high emotion regulation participants. This difference was not found among participants with high inhibitory control. These results have implications for refining and targeting training and rehabilitation programs aimed at reducing aggressive behavior.

Assessing resistance of stabilized corrosion resistant steels to intergranular corrosion

International Nuclear Information System (INIS)

Karas, A.; Cihal, V. Jr.; Vanek, V.; Herzan, J.; Protiva, K.; Cihal, V.

1987-01-01

Resistance to intergranular corrosion was determined for four types of titanium-stabilized steels from the coefficients of stabilization efficiency according to the degree the chemical composition was known. The ATA SUPER steel showed the highest resistance parameter value. The resistance of this type of steel of a specific composition, showing a relatively low value of mean nitrogen content was compared with steel of an optimized chemical composition and with low-carbon niobium stabilized, molybdenum modified steels. The comparison showed guarantees of a sufficient resistance of the steel to intergranular corrosion. The method of assessing the resistance to intergranular corrosion using the calculation of the minimum content of Cr', i.e., the effective chromium content, and the maximum effective carbon content C' giving the resistance parameter k seems to be prospective for practical use in the production of corrosion resistant steels. (author). 1 tab., 5 figs., 15 refs

Effects of surface condition on aqueous corrosion and environmental embrittlement of iron aluminides

Energy Technology Data Exchange (ETDEWEB)

Perrin, R.L.; Buchanan, R.A. [Univ. of Tennessee, Knoxville, TN (United States)

1996-08-01

Effects of retained high-temperature surface oxides, produced during thermomechanical processing and/or heat treatment, on the aqueous-corrosion and environmental-embrittlement characteristics of Fe{sub 3}Al-based iron aluminides (FA-84, FA-129 and FAL-Mo), a FeAl-based iron aluminide (FA-385), and a disordered low-aluminum Fe-Al alloy (FAPY) were evaluated. All tests were conducted at room temperature in a mild acid-chloride solution. In cyclic-anodic-polarization testing for aqueous-corrosion behavior, the surface conditions examined were: as-received (i.e., with the retained high-temperature oxides), mechanically cleaned and chemically cleaned. For all materials, the polarization tests showed the critical pitting potentials to be significantly lower in the as-received condition than in the mechanically-cleaned and chemically-cleaned conditions. These results indicate detrimental effects of the retained high-temperature oxides in terms of increased susceptibilities to localized corrosion. In 200-hour U-bend stress-corrosion-cracking tests for environmental-embrittlement behavior, conducted at open-circuit corrosion potentials and at a hydrogen-charging potential of {minus}1500 mV (SHE), the above materials (except FA-385) were examined with retained oxides and with mechanically cleaned surfaces. At the open-circuit corrosion potentials, none of the materials in either surface condition underwent cracking. At the hydrogen-charging potential, none of the materials with retained oxides underwent cracking, but FA-84, FA-129 and FAL-Mo in the mechanically cleaned condition did undergo cracking. These results suggest beneficial effects of the retained high-temperature oxides in terms of increased resistance to environmental hydrogen embrittlement.

Syllable Frequency and Spoken Word Recognition: An Inhibitory Effect.

Science.gov (United States)

González-Alvarez, Julio; Palomar-García, María-Angeles

2016-08-01

Research has shown that syllables play a relevant role in lexical access in Spanish, a shallow language with a transparent syllabic structure. Syllable frequency has been shown to have an inhibitory effect on visual word recognition in Spanish. However, no study has examined the syllable frequency effect on spoken word recognition. The present study tested the effect of the frequency of the first syllable on recognition of spoken Spanish words. A sample of 45 young adults (33 women, 12 men; M = 20.4, SD = 2.8; college students) performed an auditory lexical decision on 128 Spanish disyllabic words and 128 disyllabic nonwords. Words were selected so that lexical and first syllable frequency were manipulated in a within-subject 2 × 2 design, and six additional independent variables were controlled: token positional frequency of the second syllable, number of phonemes, position of lexical stress, number of phonological neighbors, number of phonological neighbors that have higher frequencies than the word, and acoustical durations measured in milliseconds. Decision latencies and error rates were submitted to linear mixed models analysis. Results showed a typical facilitatory effect of the lexical frequency and, importantly, an inhibitory effect of the first syllable frequency on reaction times and error rates. © The Author(s) 2016.

Radiolysis effects on fuel corrosion within a failed nuclear waste container

International Nuclear Information System (INIS)

Sunder, S.; Shoeshmith, D.W.; Christensen, H.C.

2003-01-01

The concept of geological disposal of used nuclear fuel in corrosion resistant containers is being investigated in several countries. In the Canadian Nuclear Fuel Waste Management Program (CNFWMP), it is assumed that the used fuel will be disposed of in copper containers. Since the predicted lifetimes of these containers are very long (>106 years), only those containers emplaced with an undetected defect will fail within the period for which radionuclide release from the fuel must be considered. Early failure could lead to the entry of water into the container and subsequent release of radionuclides. The release rate of radionuclides from the used fuel will depend upon its dissolution rate. The primary mechanism for release will be the corrosion of the fuel driven by radiolytically-produced oxidants. The studies carried out to determine the effects of water radiolysis on fuel corrosion are reviewed, and some of the procedures used to predict corrosion rates of used fuel in failed nuclear waste containers described. (author)

The inhibitory effect of Curcuma longa extract on telomerase activity ...

African Journals Online (AJOL)

STORAGESEVER

2010-02-08

Feb 8, 2010 ... curcumin, could have important effect on treatment of lung cancer. Curcumin ... study inhibitory effect of C. longa total extract on telomerase in A549 lung cancer cell line as in vitro model of ..... If A > 2× (OD of negative control), then, telomerase activity ... radiation, chemotherapy, laser therapy, photodynamic.

A STUDY OF CORROSION AND STRESS CORROSION CRACKING OF CARBON STEEL NUCLEAR WASTE STORAGE TANKS

International Nuclear Information System (INIS)

BOOMER, K.D.

2007-01-01

The Hanford reservation Tank Farms in Washington State has 177 underground storage tanks that contain approximately 50 million gallons of liquid legacy radioactive waste from cold war plutonium production. These tanks will continue to store waste until it is treated and disposed. These nuclear wastes were converted to highly alkaline pH wastes to protect the carbon steel storage tanks from corrosion. However, the carbon steel is still susceptible to localized corrosion and stress corrosion cracking. The waste chemistry varies from tank to tank, and contains various combinations of hydroxide, nitrate, nitrite, chloride, carbonate, aluminate and other species. The effect of each of these species and any synergistic effects on localized corrosion and stress corrosion cracking of carbon steel have been investigated with electrochemical polarization, slow strain rate, and crack growth rate testing. The effect of solution chemistry, pH, temperature and applied potential are all considered and their role in the corrosion behavior will be discussed

Atmospheric corrosion of uranium-carbon alloys; Corrosion atmospherique des alliages uranium-carbone

Energy Technology Data Exchange (ETDEWEB)

Rousset, P; Accary, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-07-01

The authors study the corrosion of uranium-carbon alloys having compositions close to that of the mono-carbide; they show that the extent of the observed corrosion effects increases with the water vapour content of the surrounding gas and they conclude that the atmospheric corrosion of these alloys is due essentially to the humidity of the air, the effect of the oxygen being very slight at room temperature. They show that the optimum conditions for preserving U-C alloys are either a vacuum or a perfectly dry argon atmosphere. The authors have also established that the type of corrosion involved is a corrosion which 'cracks under stress' and is transgranular (it can also be intergranular in the case of sub-stoichiometric alloys). They propose, finally, two hypotheses for explaining this mechanism, one of which is illustrated by the existence, at the fissure interface, of corrosion products which can play the role of 'corners' in the mono-carbide grains. (authors) [French] Les auteurs etudient la corrosion des alliages uranium-carbone de composition voisine du monocarbure; ils montrent que l'importance des effets de la corrosion observee augmente avec la teneur en vapeur d'eau du milieu gazeux ambiant et concluent que la corrosion atmospherique de ces alliages est due essentiellement a l'humidite de l'air, l'action de l'oxygene de l'air etant tres faible a la temperature ambiante. Ils indiquent que les conditions optimales de conservation des alliages U-C sont le vide ou une atmosphere d'argon parfaitement desseches. D'autre part, les auteurs etablissent que le type de corrosion mis en jeu est une corrosion 'fissurante sous contrainte', transgranulaire (pouvant egalement etre intergranulaire dans le cas d'alliages sous-stoechiometriques). Ils proposent enfin deux hypotheses pour rendre compte de ce mecanisme, dont l'une est illustree par la mise en evidence, a l'interface des fissures, de produits de corrosion pouvant jouer le role de 'coins' dans les grains de

The effect of magnetite on corrosion of stainless steel (SUS309S) in deaerated synthetic sea water

International Nuclear Information System (INIS)

Taniguchi, N.; Honda, A.

1999-10-01

The assessment of lifetime of carbon steel overpack needs to clear the effects of corrosion products on the corrosion rate of carbon steel. It is reported that the corrosion of carbon steel was accelerated under the presence of magnetite as simulated corrosion products. Therefore, it is important to clear the mechanism of the acceleration of corrosion under the presence of magnetite. If carbon steel overpack will not be able to avoid the acceleration of corrosion under repository condition, some countermeasures have to be taken. One of the countermeasures against the effect of magnetite is considered to be the addition of alloying elements to a steel. The immersion test of stainless steel (SUS309S) as the extreme case of alloying was conducted under the presence of magnetite on the metal surface in synthetic sea water. As the result of this test, the corrosion of stainless steel (SUS309S) was not accelerated by the presence of magnetite. Therefore, it is expected that the susceptibility to the effect of magnetite is able to be reduced by addition of alloying elements to a steel. (author)

The Spread of Corrosion in Cast Iron and its Effect on the Life Cycle of Transportation Vehicles

Directory of Open Access Journals (Sweden)

Tomáš Binar

2017-01-01

Full Text Available This article deals with the spread of corrosion in material at different exposure times, and its effect on the measured brittle fracture and notch impact strength under different temperature conditions. To assess the degradational effect of corrosion on the material characteristics represented by the measured impact strength, we conducted a fractographic analysis of fracture surfaces, the aim of which was to evaluate the spread of corrosion in the material. In the first part of the experiment, two corrosion tests are simulated with a duration time of 432 and 648 hours, to compare the degradation effect of corrosion on the notch impact strength, depending on the duration of the corrosion tests. The following part shows the results of the impact bending test, where the experiment was conducted in an area of reduced and increased temperatures. The final part summarizes the results of the fractographic analysis of sample fracture surfaces from the impact bending tests. Based on the measured the length of the corrosion cracks, we analyzed the sample at the notch and from the material surface after the impact bending test.

Catastrophes caused by corrosion

OpenAIRE

PETROVIC ZORAN C.

2016-01-01

For many years, huge attention has been paid to the problem of corrosion damage and destruction of metallic materials. Experience shows that failures due to corrosion problems are very important, and statistics at the world level shows that the damage resulting from the effects of various forms of corrosion is substantial and that, for example, in industrialized countries it reaches 4-5% of national incomes. Significant funds are determined annually for the prevention and control of corrosion...

Alpha-glucosidase inhibitory effect and inorganic constituents of Phyllanthus amarus Schum. & Thonn. ash

Directory of Open Access Journals (Sweden)

Malinee Wongnawa

2014-10-01

Full Text Available This study investigated the -glucosidase inhibitory effect and determined the concentration of some inorganic constituents in P. amarus ash. Oral glucose and sucrose tolerance test were performed on normal mice. In vitro -glucosidase inhibitory activity was evaluated by using yeast a-glucosidase. The element concentrations were measured by inductively coupled plasma (ICP spectroscopy. Single oral administration of P. amarus ash did not show antihyperglycemic effect after glucose administration, but decreased blood glucose level after sucrose administration. The ash showed -glucosidase inhibitory activity in vitro with IC50 of 982 mg/mL. The concentrations of K, Ca, Mg, Mn, Fe, Zn, Cu, Pb, Cr, Ni and Co in P. amarus ash were 35049.80±340.64, 3337.24±52.10, 1368.52±13.29, 90.81±1.34, 87.68±1.15, 18.28±0.22, 4.69±0.07, 1.07±0.15, 0.29±0.03, 0.20±0.04 and 0.10±0.02 mg/g, respectively. These results indicate that the antihyperglycemic effect of P. amarus ash might be partly due to the -glucosidase inhibitory activity of the inorganic constituents.

Effect of H2O2 on the corrosion behavior of 304L stainless steel

International Nuclear Information System (INIS)

Song, Taek Hoh; Kim, In Sub; Noh, Sung Kee

1995-01-01

In connection with the safe storage of high level nuclear waste, effect of H 2 O 2 on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H 2 O 2 . The experimental results show that H 2 O 2 increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H 2 O 2 concentration increased, indicating that pitting resistance was decreased by the existence of H 2 O 2 in the electrolyte. These effects of H 2 O 2 on corrosion of 304L stainless steel are considered to be similar to those of γ-irradiation. To compare the effects of H 2 O 2 with those of O 2 , cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H 2 O 2 on the corrosion behavior were very similar to those of O 2 such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. In acid and alkaline media, the corrosion potential shifts by H 2 O 2 were restricted by the large current density of proton reduction and by the le Chatelier's principle respectively. 13 figs., 1 tabs., 17 refs. (Author)

Novel implementation of the use of the EPR-in situ technique (Electrochemical potentiodynamic reactivation) to identify intergranular corrosion susceptability of stainless steels exposed to high temperatures

International Nuclear Information System (INIS)

Munoz, N.; Pineda, Y.; Vera, E.; Sepulveda, H.; Heyn, Andreas

2010-01-01

Austenitic stainless steels (18 % Cr), are often used in pieces that are exposed to temperatures of 450 o C to 900 o C (heat exchangers). At these temperatures sensibilization occurs on the grain boundaries, becoming a key factor in the appearance of intergranular corrosion. In order to prevent this phenomena from occurring 0.3% to 0.8% of niobium is added as an alloying element in the manufacturing process, which prevents the carbon present in the steel combines with the chromium, avoiding the formation of carbides. An electrochemical method for in-situ application was developed to evaluate the corrosive behavior of stainless steel and its susceptibility and degree of sensibilizaton to an intergranular attack. This work shows the effectiveness of this technique in evaluating niobium's inhibitory effect in preventing the formation of chromium carbides on the grain boundaries of 18% chromium steel, and also shows the technique's potentiality in determining how susceptible these steels are to intercrystalline corrosion

Exploratory shaft liner corrosion estimate

International Nuclear Information System (INIS)

Duncan, D.R.

1985-10-01

An estimate of expected corrosion degradation during the 100-year design life of the Exploratory Shaft (ES) is presented. The basis for the estimate is a brief literature survey of corrosion data, in addition to data taken by the Basalt Waste Isolation Project. The scope of the study is expected corrosion environment of the ES, the corrosion modes of general corrosion, pitting and crevice corrosion, dissimilar metal corrosion, and environmentally assisted cracking. The expected internal and external environment of the shaft liner is described in detail and estimated effects of each corrosion mode are given. The maximum amount of general corrosion degradation was estimated to be 70 mils at the exterior and 48 mils at the interior, at the shaft bottom. Corrosion at welds or mechanical joints could be significant, dependent on design. After a final determination of corrosion allowance has been established by the project it will be added to the design criteria. 10 refs., 6 figs., 5 tabs

Effect of surface modification on the corrosion resistivity in supercritical water

International Nuclear Information System (INIS)

Penttila, S.; Horvath, A.; Toivonen, A.; Zolnai, Z.

2011-01-01

This paper summarizes the results of high temperature corrosion studies of the candidate austenitic alloys at relevant operating conditions for SCWR. The high temperature and pressure above the thermodynamic critical point of water result in higher oxidation rate which might be critical for thin-wall components like fuel cladding. The goal of this work was to study the effect of surface preparation on the oxidation rate on Ti-stabilized austenitic alloy 1.4970. Surfaces were prepared with ion implantation using He"+- and N"+-ions. Samples were immersed in supercritical water at 650"oC/25 MPa, for up to 2000 hours. Added to this, conventional surface treatments were conducted for austenitic alloy 316L tube samples in order to study the effect of cold work in sample surface on corrosion resistance. The corrosion rate was evaluated by measuring the weight change of the samples. The compositions of the oxide layers were analyzed using scanning electron microscope (SEM) in conjunction with Energy Dispersive Spectroscopy (EDS). (author)

Nodular Corrosion Characteristics of Zirconium Alloys

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyun Gil; Jeong, Y. H.; Park, S. Y.; Lee, D. J

2003-01-15

This study was reported the effect of the nodular corrosion on the nuclear reactor environmental along with metallurgical influence, also suggested experimental scheme related to evaluate nodular corrosion characteristics of Zr-1 Nb alloy. Remedial strategies against the nodular corrosion should firstly develop plan to assess the effect of the water quality condition (Oxygen, Hydrogen) as well as the boiling on the nodular corrosion, secondarily establish plan to control heat treatment process to keep a good resistance on nodular corrosion in Zr-1Nb alloy as former western reactor did.

Effect of chlorides on the corrosion behaviour of mild steel

International Nuclear Information System (INIS)

Harada, Kazuyuki; Shimada, Minoru

1980-01-01

In PWR's steam generators, ''denting'' resulted from corrosion of support plate material, carbon steel is an important problem. The role of chlorides in corrosion acceleration of mild steel was studied. Corrosion tests were conducted at temperature from 100 0 C to 280 0 C in deaerated solutions of NaCl and MgCl 2 which are main content of sea water. 1) Solution of MgCl 2 was more corrosive than that of NaCl. The more increased in concentration of each chloride solution, the more corrosive in MgCl 2 soln. but the less corrosive in NaCl soln. 2) The rate of corrosion in the mixed solution of NaCl and MgCl 2 was governed by the concentration of MgCl 2 soln. The corrosion behaviour in sea water was suggested to be not controlled by NaCl but by MgCl 2 . 3) Acidification of MgCl 2 soln. could be evaluated by experiment at 100 0 C, the degree of acidification increased with increasing the concentration. However, the value of pH during corrosion was kept constant by the concentration of dissolved Fe 2+ ions. 4) The corrosion acceleration by MgCl 2 soln. was arised not only from acidification by the solution itself but from continuous supplementation of H + ions with the hydrolysis of dissolved Fe 2+ ions. This autocatalytic corrosion process not exhausting acid was characterized with the corrosion in closed system such as in crevice. In addition to acidification of MgCl 2 soln., the formation of non-protective magnetite film by Mg 2+ ion was estimated to be a reason of accelerated corrosion. (author)

Experimental study on the inhibitory effect of sodium cantharidinate ...

African Journals Online (AJOL)

Backgroud: Cantharidin, and its derivatives can not only inhibit the proliferation of tumor cells, but can also induce tumor cell apoptosis. It shows cantharidin exhibits a wide range of reactivity in anticancer. The objective of this paper was to study the inhibitory effect of sodium cantharidinate on human hepatoma HepG2 cells.

Investigations into the corrosion resistance of copper aluminium alloys. Effect of phosphorus as corrosion resistant third alloying element in the ternary system CuAl20P1

International Nuclear Information System (INIS)

Allwardt, A.

1997-01-01

The effect of phosphorus on the corrosion resistance of Al-bronzes is studied in detail in this work. A literature review showed that there are a lot of things known about the microstructure and the mechanical properties of Al-bronzes. In spite of their corrosion resistance the corrosion properties and the structure of the protective oxide films of Al-bronzes were seldom a matter of interest. Systematic studies of the influence of different alloying elements on the oxide film and the corrosion properties are rare. Therefore, it is not possible to predict the corrosion resistance of Al-bronzes, made by alloying particular elements. The high corrosion resistance of the new alloy CuAl 20 P 1 was the reason to investigate the influence of phosphorus on the corrosion properties of Al-bronzes in more detail. A systematic study of the microstructure and the corrosion properties of Cu, CuP x , CuAl 20 and CuAl 20 P x offers an insight into the effect of aluminium and phosphorus on the formation of the oxide film on Al-bronzes. It was found that there exists a critical amount of 1 at.-% of phosphorus. Above and below this amount the corrosion resistance becomes worse. This behaviour could be explained by XPS-and electrochemical measurements. Although there are still some questions about the influence of phosphorus on the corrosion resistance of Al-bronzes, this work has produced some important results, which in the future may be helpful to develop new high corrosion resistant Al-bronzes more efficiently: - on clean surface Al-bronze, the oxidation of Al and Cu takes place simultaneously, - Al promotes the formation of Cu 2 O but impedes the formation of Cu(II)-oxide/-hydride in neutral solutions, - P impedes the formation of Cu 2 O and as a consequence promotes the formation of aluminium oxide. This results in a higher amount of Al in the oxide film on the surface of the alloy, which leads to a better corrosion resistance. (author) figs., tabs., 106 refs

Relationship between microstructure, cytotoxicity and corrosion properties of a Cu-Al-Ni shape memory alloy.

Science.gov (United States)

Colić, Miodrag; Rudolf, Rebeka; Stamenković, Dragoslav; Anzel, Ivan; Vucević, Dragana; Jenko, Monika; Lazić, Vojkan; Lojen, Gorazd

2010-01-01

Cu-Al-Ni shape memory alloys (SMAs) have been investigated as materials for medical devices, but their biomedical application is still limited. The aim of this work was to compare the microstructure, corrosion and cytotoxicity in vitro of a Cu-Al-Ni SMA. Rapidly solidified (RS) thin ribbons, manufactured via melt spinning, were used for the tests. The control alloy was a permanent mould casting of the same composition, but without shape memory effect. The results show that RS ribbons are significantly more resistant to corrosion compared with the control alloy, as judged by the lesser release of Cu and Ni into the conditioning medium. These results correlate with the finding that RS ribbons were not cytotoxic to L929 mouse fibroblasts and rat thymocytes. In addition, the RS ribbon conditioning medium inhibited cellular proliferation and IL-2 production by activated rat splenocytes to a much lesser extent. The inhibitory effects were almost completely abolished by conditioning the RS ribbons in culture medium for 4 weeks. Microstructural analysis showed that RS ribbons are martensitic, with boron particles as a minor phase. In contrast, the control Cu-Al-Ni alloy had a complex multiphase microstructure. Examination of the alloy surfaces after conditioning by energy dispersive X-ray and Auger electron spectroscopy showed the formation of Cu and Al oxide layers and confirmed that the metals in RS ribbons are less susceptible to oxidation and corrosion compared with the control alloy. In conclusion, these results suggest that rapid solidification significantly improves the corrosion stability and biocompatibility in vitro of Cu-Al-Ni SMA ribbons.

Predicting Effects of Corrosion Erosion of High Strength Steel Pipelines Elbow on CO2-Acetic Acid (HAc) Solution

International Nuclear Information System (INIS)

Asmara, Y. P.; Ismail, M. F.; Chui, L. Giok; Halimi, Jamiludin

2016-01-01

Simultaneously effect of erosion combined with corrosion becomes the most concern in oil and gas industries. It is due to the fast deterioration of metal as effects of solid particles mixed with corrosive environment. There are many corrosion software to investigate possible degradation mechanisms developed by researchers. They are using many combination factors of chemical reactions and physical process. However effects of CO 2 and acid on pipelines orientations are still remain uncovered in their simulation. This research will investigate combination effects of CO 2 and HAc on corrosion and erosion artificial environmental containing sands particles in 45°, 90° and 180° elbow pipelines. The research used theoretical calculations combined with experiments for verification. The main concerns are to investigate the maximum erosion corrosion rate and maximum shear stress at the surface. Methodology used to calculate corrosion rate are Linear Polarization Resistance (LPR) and weight loss. The results showed that at 45°, erosion rate is the more significant effects in contributing degradation of the metal. The effects of CO 2 and HAc gave significant effects when flow rate of the solution are high which reflect synergism effects of solid particles and those chemical compositions. (paper)

The enhancing power of iodide on corrosion prevention of mild steel in the presence of a synthetic-soluble Schiff-base: Electrochemical and surface analyses

International Nuclear Information System (INIS)

Lashgari, Mohsen; Arshadi, Mohammad-Reza; Miandari, Somaieh

2010-01-01

The inhibitory action of N,N'-1,3-propylen-bis(3-methoxysalicylidenimine) {PMSI} on mild steel corrosion in sulfuric acid medium was investigated through electrochemical methods and evaluations based on infrared spectroscopy and scanning electron micrographs. The studies revealed that the molecule is a good mixed-type inhibitor (mostly anodic), acts as a multi-dentate ligand and repels the corrosive agents by hydrophobic forces. Its adsorption on metal surface has a physicochemical nature and obeys the Langmuir isotherm. At a critical (optimum) concentration, an anomalous inhibitory behavior was observed and interpreted at microscopic level by means of desorption/adsorption process and horizontal ↔vertical hypothesis. The addition of iodide into acid moreover causes a synergistic influence, a substantial enhancement on inhibitory performance. Finally, using isolated inhibitor calculations at B3LYP/6-31G + (d,p) level of theory, the equilibrium geometry of PMSI was determined and the energy required for hindrance avoidance was predicted.

Effect of flow velocity on erosion-corrosion behaviour of QSn6 alloy

Science.gov (United States)

Huang, Weijiu; Zhou, Yongtao; Wang, Zhenguo; Li, Zhijun; Zheng, Ziqing

2018-05-01

The erosion-corrosion behaviour of QSn6 alloy used as propellers in marine environment was evaluated by erosion-corrosion experiments with/without cathodic protection, electrochemical tests and scanning electron microscope (SEM) observations. The analysis was focused on the effect of flow velocity. The dynamic polarization curves showed that the corrosion rate of the QSn6 alloy increased as the flow velocity increased, due to the protective surface film removal at higher velocities. The lowest corrosion current densities of 1.26 × 10‑4 A cm‑2 was obtained at the flow velocity of 7 m s‑1. Because of the higher particle kinetic energies at higher flow velocity, the mass loss rate of the QSn6 alloy increased as the flow velocity increased. The mass loss rate with cathodic protection was lower than that without cathodic protection under the same conditions. Also, the lowest mass loss rate of 0.7 g m‑2 · h‑1 was acquired at the flow velocity of 7 m s‑1 with cathodic protection. However, the increase rate of corrosion rate and mass loss were decreased with increasing the flow velocity. Through observation the SEM morphologies of the worn surfaces, the main wear mechanism was ploughing with/without cathodic protection. The removal rates of the QSn6 alloy increased as the flow velocity increased in both pure erosion and erosion-corrosion, whereas the erosion and corrosion intensified each other. At the flow velocity of 7 m s‑1, the synergy rate (ΔW) exceeded by 5 times the erosion rate (Wwear). Through establishment and observation the erosion-corrosion mechanism map, the erosion-corrosion was the dominant regime in the study due to the contribution of erosion on the mass loss rate exceeded the corrosion contribution. The QSn6 alloy with cathodic protection is feasible as propellers, there are higher security at lower flow velocity, such as the flow velocity of 7 m s‑1 in the paper.

Inhibitory effect of organotin compounds on rat neuronal nitric oxide synthase through interaction with calmodulin

International Nuclear Information System (INIS)

Ohashi, Koji; Kominami, Shiro; Yamazaki, Takeshi; Ohta, Shigeru; Kitamura, Shigeyuki

2004-01-01

Organotin compounds, triphenyltin (TPT), tributyltin, dibutyltin, and monobutyltin (MBT), showed potent inhibitory effects on both L-arginine oxidation to nitric oxide and L-citrulline, and cytochrome c reduction catalyzed by recombinant rat neuronal nitric oxide synthase (nNOS). The two inhibitory effects were almost parallel. MBT and TPT showed the highest inhibitory effects, followed by tributyltin and dibutyltin; TPT and MBT showed inhibition constant (IC 50 ) values of around 10 μM. Cytochrome c reduction activity was markedly decreased by removal of calmodulin (CaM) from the complete mixture, and the decrease was similar to the extent of inhibition by TPT and MBT. The inhibitory effect of MBT on the cytochrome c reducing activity was rapidly attenuated upon dilution of the inhibitor, and addition of a high concentration of CaM reactivated the cytochrome c reduction activity inhibited by MBT. However, other cofactors such as FAD, FMN or tetrahydrobiopterin had no such ability. The inhibitory effect of organotin compounds (100 μM) on L-arginine oxidation of nNOS almost vanished when the amount of CaM was sufficiently increased (150-300 μM). It was confirmed by CaM-agarose column chromatography that the dissociation of nNOS-CaM complex was induced by organotin compounds. These results indicate that organotin compounds disturb the interaction between CaM and nNOS, thereby inhibiting electron transfer from the reductase domain to cytochrome c and the oxygenase domain

COX-1 inhibitory effect of medicinal plants of Ghana

DEFF Research Database (Denmark)

Larsen, Birgitte HV; Soelberg, Jens; Jäger, Anna

2015-01-01

zanthoxyloides showed an inhibitory effect over 90% in the final concentration 0.1 μg/μL. The HPLC profiles indicated that the extracts of the four active species did not contain tannins. The observed in vitro activities support the use of some of the plant species in the traditional medicine system in Ghana....

Effect of compression deformation on the microstructure and corrosion behavior of magnesium alloys

International Nuclear Information System (INIS)

Snir, Y.; Ben-Hamu, G.; Eliezer, D.; Abramov, E.

2012-01-01

Highlights: ► Metallurgical features (mainly twinning, dislocation accumulation, and dynamic recrystallization). ► The thermo-mechanical state (amount of deformation and its temperature). ► The corrosion behavior of wrought Mg-alloys. This correlation was emphasized by the mechanical behavior measured through micro-hardness. ► Microstructural changes during deformation, and potentio-dynamic corrosion tests were correlated. - Abstract: The effect of deformation on the corrosion and mechanical behavior of wrought Mg-alloys AZ31, AM50, and ZK60 was investigated. The materials’ behavior was correlated to the changes in metallurgical features, during compression, into different amounts of deformation at three temperatures: 250° C, 280° C, and 350° C. The metallurgical features were monitored by optical microscope, scanning electron microscope (SEM), and transmission electron microscopy (TEM). It was observed that there is a very strong correlation between three features: 1. metallurgical features (mainly twinning, dislocation accumulation, and dynamic recrystallization); 2. The thermo-mechanical state (amount of deformation and its temperature); and 3. The corrosion behavior of wrought Mg-alloys. This correlation was emphasized by the mechanical behavior measured through micro-hardness. Microstructural changes during deformation, and potentio-dynamic corrosion tests were correlated. These results show that studies on the effect of thermo-mechanical state (related to the microstructure) on the corrosion behavior of wrought Mg-alloys are essential in order to optimize their applicability to plastic forming processes.

Effect of Heat treatment on Hardness and Corrosion Resistance of Super Cast Iron

Energy Technology Data Exchange (ETDEWEB)

Lee, Roun; Kim, Young Sik [Andong National University, Andong (Korea, Republic of)

2014-07-15

In fossil-fuel-fired power plants, a variety of pollutants are produced from the combustion of conventional fuels such as coal, oil and gas. Major component of such pollution are ash and corrosive chemicals, which also destroy pumps and piping; by causing erosion/corrosion, pitting, and wear. In order to over come such damage, materials with high hardness and high corrosion resistance are needed. In this work, we melted super-cast-iron with excellent corrosion resistance and high hardness. To elucidate the effect of heat treatment, microstructural analysis, hardness measurement, and corrosion tests were performed. Test results revealed that the super-cast-iron had several tens better corrosion resistance than 316 L stainless steel, and it also had a high surface hardness (> HRC45). High hardness, in spite of its low carbon content (0.74%C), could resulted from a hardening heat treatment to precipitate sufficient Cr{sub 7}C{sub 3} and Cr{sub 2}3C{sub 6}. Also, it was concluded that the excellent corrosion resistance of the super-cast-iron was due to the increase of the relative chromium content by minimizing the carbon content, and by the enhancement of passive film by the addition of Cr, Mo, Cu, and W.

Effect of nanograin-boundary networks generation on corrosion of carburized martensitic stainless steel.

Science.gov (United States)

Boonruang, Chatdanai; Thong-On, Atcharawadi; Kidkhunthod, Pinit

2018-02-02

Martensitic stainless steel parts used in carbonaceous atmosphere at high temperature are subject to corrosion which results in a large amount of lost energy and high repair and maintenance costs. This work therefore proposes a model for surface development and corrosion mechanism as a solution to reduce corrosion costs. The morphology, phase, and corrosion behavior of steel are investigated using GIXRD, XANES, and EIS. The results show formation of nanograin-boundary networks in the protective layer of martensitic stainless steel. This Cr 2 O 3 -Cr 7 C 3 nanograin mixture on the FeCr 2 O 4 layer causes ion transport which is the main reason for the corrosion reaction during carburizing of the steel. The results reveal the rate determining steps in the corrosion mechanism during carburizing of steel. These steps are the diffusion of uncharged active gases in the stagnant-gas layer over the steel surface followed by the conversion of C into C 4- and O into O 2- at the gas-oxide interface simultaneously with the migration of Cr 3+ from the metal-oxide interface to the gas-oxide interface. It is proposed that previous research on Al 2 O 3 coatings may be the solution to producing effective coatings that overcome the corrosion challenges discussed in this work.

Effect of fluoride additives on the corrosion of aluminum for lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Tsuyoshi, Nakajima; Mitsuhiro, Mori; Vinay, Gupta; Yoshimi, Ohzawa [Aichi Institute of Technology, Dept. of Applied Chemistry, Toyota-shi (Japan); Hiroyuki, Iwata [Aichi Institute of Technology, Technical Research Center, Toyata-shi (Japan)

2002-12-01

Effect of fluoride additives was investigated in organic solvents containing LiCF{sub 3}SO{sub 3} to prevent the corrosion of aluminum current collector for lithium ion batteries. LiClO{sub 4} was also examined for comparison. Among examined LiBF{sub 4}, LiPF{sub 6}, LiAsF{sub 6}, LiSbF{sub 6} and LiClO{sub 4}, LiBF{sub 4} was the best additive to suppress the corrosion of aluminum because its oxidation potential is close to that of CF{sub 3}SO{sub 3}{sup -} anion. Corrosion currents for aluminum in a complex fluoride- or LiClO{sub 4}-added solvents became smaller in the order, LiSbF{sub 6}>LiAsF{sub 6}>LiClO{sub 4}>LiPF{sub 6}>LiBF{sub 4}. Oxidation potential of ClO{sub 4}{sup -} is nearly the same as that of CF{sub 3}SO{sub 3}{sup -}. However, the corrosion currents were similar to or slightly larger than those observed in LiPF{sub 6}-added solvents. SEM images of electrochemically oxidized aluminum samples indicated that the level of corrosion well coincided with the observed corrosion currents. The corrosion mechanism of aluminum was also proposed. (authors)

Zinc corrosion after loss-of-coolant accidents in pressurized water reactors – Physicochemical effects

Energy Technology Data Exchange (ETDEWEB)

Kryk, Holger, E-mail: h.kryk@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics, P.O. Box 510119, D-01314 Dresden (Germany); Hoffmann, Wolfgang [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics, P.O. Box 510119, D-01314 Dresden (Germany); Kästner, Wolfgang; Alt, Sören; Seeliger, André; Renger, Stefan [Hochschule Zittau/Görlitz, Institute of Process Technology, Process Automation and Measuring Technology, Theodor-Körner-Allee 16, D-02763 Zittau (Germany)

2014-12-15

Highlights: • Physicochemical effects due to post-LOCA zinc corrosion in PWR were elucidated. • Decreasing solubility of corrosion products with increasing temperature was found. • Solid corrosion products may be deposited on hot surfaces and/or within hot-spots. • Corrosion products precipitating from coolant were identified as zinc borates. • Depending on coolant temperature, different types of zinc borate are formed. - Abstract: Within the framework of the reactor safety research, generic experimental investigations were carried out aiming at the physicochemical background of possible zinc corrosion product formation, which may occur inside the reactor pressure vessel during the sump circulation operation after loss-of-coolant accidents in pressurized water reactors. The contact of the boric acid containing coolant with hot-dip galvanized steel containment internals causes corrosion of the corresponding materials resulting in dissolution of the zinc coat. A retrograde solubility of zinc corrosion products with increasing temperature was observed during batch experiments of zinc corrosion in boric acid containing coolants. Thus, the formation and deposition of solid corrosion products cannot be ruled out if the coolant containing dissolved zinc is heated up during its recirculation into hot regions within the emergency cooling circuit (e.g. hot-spots in the core). Corrosion experiments at a lab-scale test facility, which included formation of corrosion products at a single heated cladding tube, proved that dissolved zinc, formed at low temperatures in boric acid solution by zinc corrosion, turns into solid deposits of zinc borates when contacting heated zircaloy surfaces during the heating of the coolant. Moreover, the temperature of formation influences the chemical composition of the zinc borates and thus the deposition and mobilization behavior of the products.

Zinc corrosion after loss-of-coolant accidents in pressurized water reactors – Physicochemical effects

International Nuclear Information System (INIS)

Kryk, Holger; Hoffmann, Wolfgang; Kästner, Wolfgang; Alt, Sören; Seeliger, André; Renger, Stefan

2014-01-01

Highlights: • Physicochemical effects due to post-LOCA zinc corrosion in PWR were elucidated. • Decreasing solubility of corrosion products with increasing temperature was found. • Solid corrosion products may be deposited on hot surfaces and/or within hot-spots. • Corrosion products precipitating from coolant were identified as zinc borates. • Depending on coolant temperature, different types of zinc borate are formed. - Abstract: Within the framework of the reactor safety research, generic experimental investigations were carried out aiming at the physicochemical background of possible zinc corrosion product formation, which may occur inside the reactor pressure vessel during the sump circulation operation after loss-of-coolant accidents in pressurized water reactors. The contact of the boric acid containing coolant with hot-dip galvanized steel containment internals causes corrosion of the corresponding materials resulting in dissolution of the zinc coat. A retrograde solubility of zinc corrosion products with increasing temperature was observed during batch experiments of zinc corrosion in boric acid containing coolants. Thus, the formation and deposition of solid corrosion products cannot be ruled out if the coolant containing dissolved zinc is heated up during its recirculation into hot regions within the emergency cooling circuit (e.g. hot-spots in the core). Corrosion experiments at a lab-scale test facility, which included formation of corrosion products at a single heated cladding tube, proved that dissolved zinc, formed at low temperatures in boric acid solution by zinc corrosion, turns into solid deposits of zinc borates when contacting heated zircaloy surfaces during the heating of the coolant. Moreover, the temperature of formation influences the chemical composition of the zinc borates and thus the deposition and mobilization behavior of the products

Inhibitory Effects of Respiration Inhibitors on Aflatoxin Production

Directory of Open Access Journals (Sweden)

Shohei Sakuda

2014-03-01

Full Text Available Aflatoxin production inhibitors, which do not inhibit the growth of aflatoxigenic fungi, may be used to control aflatoxin without incurring a rapid spread of resistant strains. A respiration inhibitor that inhibits aflatoxin production was identified during a screening process for natural, aflatoxin-production inhibitors. This prompted us to evaluate respiration inhibitors as potential aflatoxin control agents. The inhibitory activities of four natural inhibitors, seven synthetic miticides, and nine synthetic fungicides were evaluated on aflatoxin production in Aspergillus parasiticus. All of the natural inhibitors (rotenone, siccanin, aptenin A5, and antimycin A inhibited fungal aflatoxin production with IC50 values around 10 µM. Among the synthetic miticides, pyridaben, fluacrypyrim, and tolfenpyrad exhibited strong inhibitory activities with IC50 values less than 0.2 µM, whereas cyflumetofen did not show significant inhibitory activity. Of the synthetic fungicides, boscalid, pyribencarb, azoxystrobin, pyraclostrobin, and kresoxim-methyl demonstrated strong inhibitory activities, with IC50 values less than 0.5 µM. Fungal growth was not significantly affected by any of the inhibitors tested at concentrations used. There was no correlation observed between the targets of respiration inhibitors (complexes I, II, and III and their IC50 values for aflatoxin-production inhibitory activity. This study suggests that respiration inhibitors, including commonly used pesticides, are useful for aflatoxin control.

Inhibitory Effects of Respiration Inhibitors on Aflatoxin Production

Science.gov (United States)

Sakuda, Shohei; Prabowo, Diyan Febri; Takagi, Keiko; Shiomi, Kazuro; Mori, Mihoko; Ōmura, Satoshi; Nagasawa, Hiromichi

2014-01-01

Aflatoxin production inhibitors, which do not inhibit the growth of aflatoxigenic fungi, may be used to control aflatoxin without incurring a rapid spread of resistant strains. A respiration inhibitor that inhibits aflatoxin production was identified during a screening process for natural, aflatoxin-production inhibitors. This prompted us to evaluate respiration inhibitors as potential aflatoxin control agents. The inhibitory activities of four natural inhibitors, seven synthetic miticides, and nine synthetic fungicides were evaluated on aflatoxin production in Aspergillus parasiticus. All of the natural inhibitors (rotenone, siccanin, aptenin A5, and antimycin A) inhibited fungal aflatoxin production with IC50 values around 10 µM. Among the synthetic miticides, pyridaben, fluacrypyrim, and tolfenpyrad exhibited strong inhibitory activities with IC50 values less than 0.2 µM, whereas cyflumetofen did not show significant inhibitory activity. Of the synthetic fungicides, boscalid, pyribencarb, azoxystrobin, pyraclostrobin, and kresoxim-methyl demonstrated strong inhibitory activities, with IC50 values less than 0.5 µM. Fungal growth was not significantly affected by any of the inhibitors tested at concentrations used. There was no correlation observed between the targets of respiration inhibitors (complexes I, II, and III) and their IC50 values for aflatoxin-production inhibitory activity. This study suggests that respiration inhibitors, including commonly used pesticides, are useful for aflatoxin control. PMID:24674936

The Effect of Low-Quantity Cr Addition on the Corrosion Behaviour of Dual-Phase High Carbon Steel

Directory of Open Access Journals (Sweden)

Wilson Handoko

2018-03-01

Full Text Available Industrial application of high carbon low alloy steel with the dual-phase structure of martensite and austenite has increased drastically in recent years. Due to its excellent compression strength and its high abrasion resistance, this grade of steel has used as a high performance cutting tool and in press machinery applications. By increasing the usage of more corrosive media in industrial practice and increasing the demand for reducing the production cost, it is crucial to understand the effect of the small addition of Cr on the corrosion behaviour of this grade of steel. In this study, this effect was investigated using Secondary Electron Microscopy (SEM and in-situ Atomic Force Microscopy (AFM in the sodium chloride solution. Also, the corrosion rate was measured using the Tafel polarisation curve. It has been found that the small addition of Cr increased the stability of retained austenite, thus improving its corrosion resistance and reducing its corrosion rate. This effect has been acquired through in-situ high resolution topography images in which the samples were submerged in a corrosive solution. It has been demonstrated that the corrosion rate was reduced when the stability of austenite enhanced.

Effect of Nitrite Inhibitor on the Macrocell Corrosion Behavior of Reinforcing Steel

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Zhonglu Cao

2015-01-01

Full Text Available The effect of nitrite ions on the macrocell corrosion behavior of reinforcing steel embedded in cement mortar was investigated by comparing and analyzing the macrocell corrosion current, macrocell polarization ratios, and slopes of anodic and cathodic steels. Based on the experimental results, the relationship between macrocell potential difference and macrocell current density was analyzed, and the mechanism of macrocell corrosion affected by nitrite ions was proposed. The results indicated that nitrite ions had significant impact on the macrocell polarization ratios of cathode and anode. The presence of nitrite could reduce the macrocell current by decreasing the macrocell potential difference and increasing the macrocell polarization resistance of the anode.

Microbial exopolysaccharides: Effect on corrosion and partial chemical characterization

Digital Repository Service at National Institute of Oceanography (India)

Majumdar, I; DeSouza, F.P.; Bhosle, N.B.

gas chromatograph MICROBIAL EXOPOLYSACCHARIDES 543 Fig. I. Changes in the biofilm organic carbon (a) and EPS (b) associated with corrosion products and corrosion rate (c) of mild steel. Fig. 2. Linear correlation coeffiient (r) between EPS and organic... carbon (a), corrosion rate and organic carbon (b). and corrosion rate and EPS (c). (Chrompack model CP-9002) equipped with a fused silica capillary column coated with CP Sil-88 (25 m, i.d. = 0.32 mm) and flame ionization detector (FID) was used...

Monitoring Microbially Influenced Corrosion

DEFF Research Database (Denmark)

Hilbert, Lisbeth Rischel

and diffusional effects and unreliable corrosion rates, when biofilm and ferrous sulphide corrosion products cover the steel surface. Corrosion rates can be overestimated by a factor of 10 to 100 by electrochemical techniques. Weight loss coupons and ER are recommended as necessary basic monitoring techniques......Abstract Microbially influenced corrosion (MIC) of carbon steel may occur in media with microbiological activity of especially sulphate-reducing bacteria (SRB). The applicability and reliability of a number of corrosion monitoring techniques for monitoring MIC has been evaluated in experiments....... EIS might be used for detection of MIC as the appearance of very large capacitances can be attributed to the combined ferrous sulphide and biofilm formation. Capacitance correlates directly with sulphide concentration in sterile sulphide media. Keywords: Corrosion monitoring, carbon steel, MIC, SRB...

Corrosion and protection in reinforced concrete : Pulse cathodic protection: an improved cost-effective alternative

NARCIS (Netherlands)

Koleva, D.A.

2007-01-01

Corrosion and protection in reinforced concrete. Pulse cathodic protection: an improved cost-effective alternative. The aim of the research project was to study the possibilities for establishing a new or improved electrochemical method for corrosion prevention/protection for reinforced concrete.

Inhibitory Effect of Lactobacillus reuteri on Some Pathogenic Bacteria Isolated From Women With Bacterial Vaginosis

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Eslami

2014-08-01

Full Text Available Background Considering the high prevalence of bacterial vaginosis and its association with urinary tract infection in women and treatment of gynecologic problems occur when a high recurrence of bacterial vaginosis is often treated with antibiotics. Objectives The purpose of this study was to investigate the inhibitory effect of Lactobacillus reuteri on pathogenic bacteria isolated from women with bacterial vaginosis. Materials and Methods Ninety-six samples were obtained from vaginal discharge of women with bacterial vaginosis by a gynecologist with a Dacron swab and put in sterile tubes containing TSB broth and Thioglycollate broth. Then were immediately sent to the laboratory in cold chain for further assessment. Afterward, culture was transferred on blood agar, EMB, Palcam and differential diagnosis environments. Then cultures were incubated for 24 hours at 37 °C. Lactobacillus reuteri strains were cultured in MRS environment and transferred to laboratory. After purification of pathogenic bacteria, Lactobacillus reuteri inhibitory effect on pathogenic bacteria was evaluated by minimum inhibitory concentration (MIC and antibiogram. Statistical analysis was performed using SPSS software v.16. Results The results of this study demonstrated the inhibitory effect of Lactobacillus reuteri on some pathogenic bacteria that cause bacterial, including Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus, Streptococcus agalactiae, Enterococcus, Listeria monocytogenes and E. coli. Microscopic examination of stained smears of most Lactobacillus and pathogenic bacteria showed reduced. The prevalence of abnormal vaginal discharge, history of drug use, contraceptive methods and douching were 61%, 55%, 42% and 13%, respectively. Significant difference was observed between the use and non-use of IUD in women with bacterial. Conclusions Our findings indicated the inhibitory effect of Lactobacillus reuteri on pathogenic bacteria that

The effects of bacteria on the corrosion behavior of carbon steel in compacted bentonite

International Nuclear Information System (INIS)

Nishimura, T.; Wada, R.; Nishimoto, H.; Fujiwara, K.; Taniguchi, N.; Honda, A.

1999-10-01

As a part of evaluation of corrosion life of carbon steel overpack, the experimental studies have been performed on the effects of bacteria on the corrosion behavior of carbon steel in compacted bentonite using iron bacteria (IB) as a representative oxidizing bacteria and sulphur reducing bacteria (SRB) as a representative reducing bacteria. The results of the experimental studies showed that; The activity of SRB was low in compacted bentonite in spite of applying suitable condition for the action of bacteria such as temperature and nutritious solution. Although the corrosion behavior of carbon steel was affected by the existence of bacteria in simple solution, the corrosion rates of carbon steel in compacted bentonite were several μ m/year -10 μ m/year irrespective of coexistence of bacteria and that the corrosion behavior was not affected by the existence of bacteria. According to these results, it was concluded that the bacteria would not affect the corrosion behavior of carbon steel overpack under repository condition. (author)

Effects of annealing on tensile property and corrosion behavior of Ti-Al-Zr alloy

International Nuclear Information System (INIS)

Kim, Tae-Kyu; Choi, Byung-Seon; Jeong, Yong-Hwan; Lee, Doo-Jeong; Chang, Moon-Hee

2002-01-01

The effects of annealing on the tensile property and corrosion behavior of Ti-Al-Zr alloy were evaluated. The annealing in the temperature range from 500 to 800 deg. C for 1 h induced the growth of the grain and the precipitate sizes. The results of tensile tests at room temperature showed that the strengths and the ductility were almost independent of the annealing temperature. However, the results of corrosion test in an ammonia aqueous solution of pH 9.98 at 360 deg. C showed that the corrosion resistance depended on the annealing temperature, and the corrosion rate was accelerated with increasing annealing temperature. Hydrogen contents absorbed during the corrosion test of 220 days also increased with the annealing temperature. It could be attributed to the growth of Fe-rich precipitates by annealing. It is thus suggested that the lower annealing temperatures provide the better corrosion properties without degrading the tensile properties

Effect of antimony, bismuth and calcium addition on corrosion and electrochemical behaviour of AZ91 magnesium alloy

International Nuclear Information System (INIS)

Zhou Wei; Aung, Naing Naing; Sun Yangshan

2009-01-01

This study investigated the effect of antimony, bismuth and calcium addition on the corrosion and electrochemical behaviour of AZ91 magnesium alloy in 3.5% NaCl solution. Techniques including constant immersion, electrochemical potentiodynamic polarisation, scanning electron microscopy (SEM), energy dispersed spectroscopy (EDS) and X-ray diffraction (XRD) were used to characterise electrochemical and corrosion properties and surface topography. It was found that corrosion attack occurred preferentially on Mg 3 Bi 2 and Mg 3 Sb 2 particles while Mg 17 Al 8 Ca 0.5 and Mg 2 Ca phases showed no detrimental effect on corrosion. Combined addition of small amounts of bismuth and antimony to the AZ91 alloy resulted in significant increase in corrosion rate

Effect of reactor chemistry and operating variables on fuel cladding corrosion in PWRs

International Nuclear Information System (INIS)

Park, Moon Ghu; Lee, Sang Hee

1997-01-01

As the nuclear industry extends the fuel cycle length, waterside corrosion of zircaloy cladding has become a limiting factor in PWR fuel design. Many plant chemistry factors such as, higher lithium/boron concentration in the primary coolant can influence the corrosion behavior of zircaloy cladding. The chemistry effect can be amplified in higher duty fuel, particularlywhen surface boiling occurs. Local boiling can result in increased crud deposition on fuel cladding which may induce axial power offset anomalies (AOA), recently reported in several PWR units. In this study, the effect of reactor chemistry and operating variables on Zircaloy cladding corrosion is investigated and simulation studies are performed to evaluate the optimal primary chemistry condition for extended cycle operation. (author). 8 refs., 3 tabs., 16 figs

Some observations on phosphate based corrosion inhibitors in preventing carbon steel corrosion

International Nuclear Information System (INIS)

Anupkumar, B.; Satpathy, K.K.

2000-01-01

Among the various types of phosphonic acid based inhibitors assayed, namely HEDP, ATMP and a commercial corrosion inhibitor (code named Betz), it was found that Betz has the maximum amount of organic phosphate followed by HEDP and ATMP. The corrosion rate studies show that Betz gives the highest inhibition efficiency followed by HEDP and ATMP. This shows that organic phosphate plays a significant role in corrosion protection. However, it was observed that due to synergestic effect, HEDP in the presence of Zn 2+ gave a better corrosion protection than Betz. The results are discussed in the light of available literature. (author)

Effect of chloride concentration and pH on pitting corrosion of waste package container materials

International Nuclear Information System (INIS)

Roy, A.K.; Fleming, D.L.; Gordon, S.R.

1996-12-01

Electrochemical cyclic potentiodynamic polarization experiments were performed on several candidate waste package container materials to evaluate their susceptibility to pitting corrosion at 90 degrees C in aqueous environments relevant to the potential underground high-level nuclear waste repository. Results indicate that of all the materials tested, Alloy C-22 and Ti Grade-12 exhibited the maximum corrosion resistance, showing no pitting or observable corrosion in any environment tested. Efforts were also made to study the effect of chloride ion concentration and pH on the measured corrosion potential (Ecorr), critical pitting and protection potential values

New Mechanism on Synergistic Effect of Nitrite and Triethanolamine Addition on the Corrosion of Ductile Cast Iron

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K. T. Kim

2016-01-01

Full Text Available In general, we compared the different inhibition mechanisms of organic inhibitor with that of anodic inhibitor. When triethanolamine or nitrite was added separately to tap water for inhibiting the corrosion of ductile cast iron, large amounts of inhibitor were needed. This is because the corrosion inhibitors had to overcome the galvanic corrosion that occurs between graphite and matrix. In this work, we investigated the corrosion of ductile cast iron in tap water with/without inhibitors. The corrosion rate was measured using chemical immersion test and electrochemical methods, including anodic polarization test. The inhibited surface was analyzed using EPMA and XPS. Test solutions were analyzed by performing FT-IR measurement. When triethanolamine and nitrite coexisted in tap water, synergistic effect built up, and the inhibition effect was ca. 30 times more effective than witnessed with single addition. This work focused on the synergistic effect brought about by nitrite and triethanolamine and its novel mechanism was also proposed.

Current state of knowledge of water radiolysis effects on spent nuclear fuel corrosion

International Nuclear Information System (INIS)

Christensen, H.; Sunder, S.

2000-07-01

Literature data on the effect of water radiolysis products on spent-fuel oxidation and dissolution are reviewed. Effects of gamma radiolysis, alpha radiolysis, and dissolved O 2 or H 2 O 2 in unirradiated solutions are discussed separately. Also, the effect of carbonate in gamma-irradiated solutions and radiolysis effects on leaching of spent fuel are reviewed. In addition, a kinetic model for calculating the corrosion rates of UO 2 in solutions undergoing radiolysis is discussed. The model gives good agreement between calculated and measured corrosion rates in the case of gamma radiolysis and in unirradiated solutions containing dissolved oxygen or hydrogen peroxide. However, the model fails to predict the results of alpha radiolysis. In a recent study , it was shown that the model gave good agreement with measured corrosion rates of spent fuel exposed in deionized water. The applications of radiolysis studies for geologic disposal of used nuclear fuel are discussed. (author)

The effects of corrosion product colloids on actinide transport

International Nuclear Information System (INIS)

Gardiner, M.P.; Smith, A.J.; Williams, S.J.

1991-11-01

This report assesses the possible effects of colloidal corrosion products on the transport of actinides from the near field of radioactive waste repositories. The desorption of plutonium and americium from colloidal corrosion products of iron and zirconium was studied under conditions simulating a transition from near-field to far-field environmental conditions. Desorption of actinides occurred slowly from the colloids under far-field conditions. Measurements of particle stability showed all the colloids to be unstable in the near field. Stability increased under far-field conditions or as a result of the evolution of the near field. Migration of colloids from the near field is unlikely except in the presence of organic materials. (Author)

Alginate biopolymer as green corrosion inhibitor for copper in 1 M hydrochloric acid: Experimental and theoretical approaches

Science.gov (United States)

Jmiai, A.; El Ibrahimi, B.; Tara, A.; El Issami, S.; Jbara, O.; Bazzi, L.

2018-04-01

The anti-corrosion behavior of sodium alginate (SA) on copper in the 1 M hydrochloric medium was carried out using weight loss and electrochemical measurements. The obtained results show that the inhibition increases with SA concentration and then reaches a maximum of 83% at a concentration of 0.1 mg L-1. The effect of temperature on the reactions of copper corrosion inhibition and analyzing the thermodynamic parameters revealed that the mode of adsorption has a physical nature and obeys the Langmuir isotherm. The surface morphology was performed by scanning electron microscopy coupled with energy dispersive X-ray spectrometry and atomic force microscopy. To better understand the adsorption mechanism, describing the relationship between inhibitory ability and the molecular structure of SA, quantum calculations using density functional theory were performed. Monte Carlo simulation approache was performed to know well of the relationship between the inhibition ability and molecular structure of alginate.

Synthesis and Application of Phenyl Nitrone Derivatives as Acidic and Microbial Corrosion Inhibitors

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Shijun Chen

2015-01-01

Full Text Available Nitrone has drawn great attention due to its wide applications as a 1,3-dipole in heterocyclic compounds synthesis and the bioactivities. With the special structure, nitrone can also be used as ligand in inorganic chemistry. Based on the current research, the nitrones are anticipated to be effective inhibitors against acidic and microbial corrosion. The aim of this work is to investigate the inhibitory action of nitrones. In this work, a series of phenyl nitrone derivatives (PN was synthesized and used as acidic and microbial corrosion inhibitors. The results indicate that several compounds show moderate to high inhibition efficiency (IE in 3% HCl. Accompanied with HMTA or BOZ, the IEs greatly increase, and the highest efficiency of 98.5% was obtained by using PN4 + BOZ. Investigation of the antibacterial activity against oilfield microorganism shows that the nitrone derivatives can inhibit SRB, IB, and TGB with moderate to high efficiency under 1,000 mg/L, which makes them potential to be used as bifunctional oilfield chemicals.

Corrosion evaluation technology

International Nuclear Information System (INIS)

Kim, Uh Chul; Han, Jeong Ho; Nho, Kye Ho; Lee, Eun Hee; Kim, Hong Pyo; Hwang, Seong Sik; Lee, Deok Hyun; Hur, Do Haeng; Kim, Kyung Mo.

1997-09-01

A multifrequency ACPD system was assembled which can measure very small crack. Stress corrosion cracking test system with SSRT operating high temperature was installed. Stress corrosion cracking test of newly developed alloy 600 and existing alloy 600 was carried out in steam atmosphere of 400 deg C. No crack was observed in both materials within a test period of 2,000 hrs. Corrosion fatigue test system operating at high temperature was installed in which fatigue crack was measured by CDPD. Lead enhanced the SCC of the Alloy 600 in high temperature water, had a tendency to modify a cracking morphology from intergranular to transgranular. Pit initiation preferentially occurred at Ti-rich carbide. Resistance to pit initiation decreased with increasing temperature up to 300 deg C. Test loop for erosion corrosion was designed and fabricated. Thin layer activation technique was very effective in measuring erosion corrosion. Erosion corrosion of a part of secondary side pipe was evaluated by the Check Family Codes of EPRI. Calculated values of pipe thickness by Check Family Codes coincided with the pipe thickness measured by UT with an error of ± 20%. Literature review on turbine failure showed that failure usually occurred in low pressure turbine rotor disc and causes of failure are stress corrosion cracking and corrosion fatigue. (author). 12 refs., 20 tabs., 77 figs

Effects of porosity on corrosion resistance of Mg alloy foam produced by powder metallurgy technology

Energy Technology Data Exchange (ETDEWEB)

Aghion, E., E-mail: egyon@bgu.ac.il; Perez, Y.

2014-10-15

Magnesium alloy foams have the potential to serve as structural material for regular light-weight applications as well as for biodegradable scaffold implants. However, their main disadvantage relates to the high reactivity of magnesium and consequently their natural tendency to corrode in regular service conditions and in physiological environments. The present study aims at evaluating the effect of porosity on the corrosion resistance of MRI 201S magnesium alloy foams in 0.9% NaCl solution and in phosphate buffer saline solution as a simulated physiological electrolyte. The magnesium foams were produced by powder metallurgy technology using space-holding particles to control the porosity content. Machined chips were used as raw material for the production of Mg alloy powder by milling process. The microstructure of the foams was examined using optical and scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analysis. The corrosion behavior was evaluated by immersion test and potentiodynamic polarization analysis. The results obtained clearly demonstrate that the porosity has a significant effect on the corrosion resistance of the tested foams. Foams with 14–19% porosity have a corrosion rate of 4–10 mcd and 7–15 mcd in NaCl and phosphate buffer saline solution, respectively, compared to only 0.10 mcd for the same alloy in as cast conditions. This increased corrosion degradation of the Mg foams by more than one order of magnitude compared to the cast alloy may limit their potential application in regular and physiological environments. - Highlights: • Porosity has a detrimental effect on corrosion resistance of MRI 201S Mg foams. • 14–19% porosity increases the corrosion rate by more than one order of magnitude. • Accelerated corrosion limits the use of foams in regular/physiological environments.

Experimental and theoretical investigations on the inhibition of mild steel corrosion in the ground water medium using newly synthesised bipodal and tripodal imidazole derivatives

Energy Technology Data Exchange (ETDEWEB)

Gopi, D., E-mail: dhanaraj_gopi@yahoo.com [Department of Chemistry, Periyar University, Salem 636 011, Tamilnadu (India); Centre for Nanoscience and Nanotechnology, Periyar University, Salem 636 011, Tamilnadu (India); Sherif, El-Sayed M. [Center of Excellence for Research in Engineering Materials (CEREM), Advanced Manufacturing Institute, King Saud University, P.O. Box 800, Al-Riyadh 11421 (Saudi Arabia); Electrochemistry and Corrosion Laboratory, Department of Physical Chemistry, National Research Centre (NRC), Dokki, 12622 Cairo (Egypt); Surendiran, M. [Department of Chemistry, Periyar University, Salem 636 011, Tamilnadu (India); Jothi, M.; Kumaradhas, P. [Department of Physics, Periyar University, Salem 636 011, Tamilnadu (India); Kavitha, L. [Department of Physics, School of Basic and Applied Sciences, Central University of Tamilnadu, Thiruvarur 610 101, Tamilnadu (India)

2014-10-15

Two new imidazole derivatives, namely 1,4-bis(N-imidazolylmethyl)-2-5-dimethoxybenzene (BIDM) and 1,3,5-tris(N-imidazolylmethyl)-2,4,6-trimethoxybenzene (TITM), were synthesised and their effects on the inhibition of mild steel corrosion in ground water medium are reported. The study was carried out using gravimetric and electrochemical techniques in order to determine the corrosion inhibition efficiencies of the bipodal and tripodal structured imidazoles. Further, the quantum chemical calculations using density functional theory (DFT) gave a profound insight into the inhibitory action mechanism of BIDM and TITM and their calculation parameters, such as E{sub HOMO}, E{sub LUMO} and ΔE were in good agreement with the results of the experimental studies. BIDM and TITM exhibited lowest corrosion current densities of circa 7.5 μA cm{sup −2} and 4.1 μAcm{sup −2} at the optimum concentrations of 0.67 and 0.49 mM, respectively. All measurements thus confirmed that both BIDM and TITM behaved as good inhibitors for mild steel corrosion in ground water medium. - Highlights: • Synthesis of new imidazole derivatives-BIDM(bipodal) and TITM(tripodal) inhibitors. • Gravimetric analysis to investigate mild steel corrosion inhibition in ground water. • Electrochemical characterizations to substantiate results of weight loss method. • Quantum studies to analyse the chemical behavior, structure and substituent effect.

Experimental and theoretical investigations on the inhibition of mild steel corrosion in the ground water medium using newly synthesised bipodal and tripodal imidazole derivatives

International Nuclear Information System (INIS)

Gopi, D.; Sherif, El-Sayed M.; Surendiran, M.; Jothi, M.; Kumaradhas, P.; Kavitha, L.

2014-01-01

Two new imidazole derivatives, namely 1,4-bis(N-imidazolylmethyl)-2-5-dimethoxybenzene (BIDM) and 1,3,5-tris(N-imidazolylmethyl)-2,4,6-trimethoxybenzene (TITM), were synthesised and their effects on the inhibition of mild steel corrosion in ground water medium are reported. The study was carried out using gravimetric and electrochemical techniques in order to determine the corrosion inhibition efficiencies of the bipodal and tripodal structured imidazoles. Further, the quantum chemical calculations using density functional theory (DFT) gave a profound insight into the inhibitory action mechanism of BIDM and TITM and their calculation parameters, such as E HOMO , E LUMO and ΔE were in good agreement with the results of the experimental studies. BIDM and TITM exhibited lowest corrosion current densities of circa 7.5 μA cm −2 and 4.1 μAcm −2 at the optimum concentrations of 0.67 and 0.49 mM, respectively. All measurements thus confirmed that both BIDM and TITM behaved as good inhibitors for mild steel corrosion in ground water medium. - Highlights: • Synthesis of new imidazole derivatives-BIDM(bipodal) and TITM(tripodal) inhibitors. • Gravimetric analysis to investigate mild steel corrosion inhibition in ground water. • Electrochemical characterizations to substantiate results of weight loss method. • Quantum studies to analyse the chemical behavior, structure and substituent effect

Effect of Rice Straw Extract and Alkali Lignin on the Corrosion Inhibition of Carbon Steel

International Nuclear Information System (INIS)

Rabiahtul Zulkafli; Norinsan Kamil Othman; Irman Abdul Rahman; Azman Jalar

2014-01-01

A paddy residue based corrosion inhibitor was prepared by treating finely powdered rice straw with aqueous ethanol under acid catalyst (0.01 M H 2 SO 4 ). Commercial alkali lignin was obtained from Sigma-Aldrich. Prior to the corrosion test, the extraction yield and alkali lignin was characterized via FTIR to determine the functional group. The effect of paddy residue extract and commercial alkali lignin on the corrosion inhibition of carbon steel in 1 M HCl was investigated through the weight loss method, potentiodynamic polarization technique and scanning electron microscopy (SEM). The corrosion inhibition efficiency of the extract and alkali lignin at different immersion times (3 h, 24 h and 42 h) was evaluated. The results show that the paddy waste extract exhibited lesser weight loss of carbon steel in the acidic medium in comparison to the commercial alkali lignin, suggesting that the paddy residue extract is more effective than the commercial alkali lignin in terms of its corrosion inhibition properties. The results obtained proves that the extract from paddy residue could serve as an effective inhibitor for carbon steel in acidic mediums. (author)

Effects of iron content on microstructure and crevice corrosion of titanium Grade-2

International Nuclear Information System (INIS)

He, X.; Noel, J.J.; Shoesmith, D.W.

2003-01-01

The effects of iron content on microstructure and crevice corrosion of titanium Grade-2 (Ti-2) were studied using a galvanic coupling technique combined with optical microscopy and secondary ion mass spectrometry (SIMS) imaging. The study reveals that iron content has a significant effect on the microstructure and crevice corrosion behavior of Ti-2. The grain size decreases significantly with the increasing iron content. For Ti-2 material of medium iron content, crevice corrosion was readily initiated and exhibited extensive intergranular attack which could be associated with the more reactive iron-stabilized β-phase within the α-phase matrix as revealed by SIMS imaging. By contrast, Ti-2 materials with low and high iron content showed suppressed crevice attack. The small surface area of available grain boundaries in Ti-2 of low iron content accounted for this limited attack. For the material with high iron content, SIMS imaging suggest that some Ti x Fe intermetallic particles were formed. These particles may act as proton reduction catalysts and enhance crevice corrosion resistance. (author)

Growth-inhibitory effect of TGF-B on human fetal adrenal cells in primary monolayer culture.

Science.gov (United States)

Riopel, L; Branchaud, C L; Goodyer, C G; Adkar, V; Lefebvre, Y

1989-08-01

We examined the effects of transforming-growth factor-B (TGF-B) on growth ([3H]-thymidine uptake) and function (dehydroepiandrosterone sulfate [DHAS] and cortisol production) of human fetal zone adrenal cells. Results indicate that TGF-B significantly inhibits, in a dose-related manner, both basal and epidermal growth factor (EGF)-stimulated cell growth: IC50 = 0.1-0.25 ng/ml. EGF is ineffective in overcoming the inhibitory effect of TGF-B, suggesting a noncompetitive antagonism between the two factors. Also, the inhibitory effect of TGF-B is additive to that of adrenocorticotropic hormone (ACTH). On the other hand, TGF-B (1 ng/ml) does not significantly change basal or ACTH-stimulated DHAS or cortisol secretion. We conclude that, unlike its effect on other steroid-producing cells, TGF-B inhibits growth of fetal zone cells and does not appear to have a significant inhibitory effect on steroidogenesis.

Effects of porosity in a model of corrosion and passive layer growth

Directory of Open Access Journals (Sweden)

F.D.A. Aarão Reis

2017-12-01

Full Text Available We introduce a stochastic lattice model to investigate the effects of pore formation in a passive layer grown with products of metal corrosion. It considers that an anionic species diffuses across that layer and reacts at the corrosion front (metal-oxide interface, producing a random distribution of compact regions and large pores, respectively represented by O (oxide and P (pore sites. O sites are assumed to have very small pores, so that the fraction Φ of P sites is an estimate of the porosity, and the ratio between anion diffusion coefficients in those regions is D_r0 and D_r≪1, significant changes are observed in passive layer growth and corrosion front roughness. For small Φ, a slowdown of the growth rate is observed, which is interpreted as a consequence of the confinement of anions in isolated pores for long times. However, the presence of large pores near the corrosion front increases the frequency of reactions at those regions, which leads to an increase in the roughness of that front. This model may be a first step to represent defects in a passive layer which favor pitting corrosion.

Effects of chitosan inhibitor on the electrochemical corrosion behavior of 2205 duplex stainless steel

Science.gov (United States)

Yang, Se-fei; Wen, Ying; Yi, Pan; Xiao, Kui; Dong, Chao-fang

2017-11-01

The effects of chitosan inhibitor on the corrosion behavior of 2205 duplex stainless steel were studied by electrochemical measurements, immersion tests, and stereology microscopy. The influences of immersion time, temperature, and chitosan concentration on the corrosion inhibition performance of chitosan were investigated. The optimum parameters of water-soluble chitosan on the corrosion inhibition performance of 2205 duplex stainless steel were also determined. The water-soluble chitosan showed excellent corrosion inhibition performance on the 2205 duplex stainless steel. Polarization curves demonstrated that chitosan acted as a mixed-type inhibitor. When the stainless steel specimen was immersed in the 0.2 g/L chitosan solution for 4 h, a dense and uniform adsorption film covered the sample surface and the inhibition efficiency (IE) reached its maximum value. Moreover, temperature was found to strongly influence the corrosion inhibition of chitosan; the inhibition efficiency gradually decreased with increasing temperature. The 2205 duplex stainless steel specimen immersed in 0.4 g/L water-soluble chitosan at 30°C displayed the best corrosion inhibition among the investigated specimens. Moreover, chitosan decreased the corrosion rate of the 2205 duplex stainless steel in an FeCl3 solution.

The effect of fatigue on the corrosion resistance of common medical alloys.

Science.gov (United States)

Di Prima, Matthew; Gutierrez, Erick; Weaver, Jason D

2017-10-01

The effect of mechanical fatigue on the corrosion resistance of medical devices has been a concern for devices that experience significant fatigue during their lifespan and devices made from metallic alloys. The Food and Drug Administration had recommended in some instances for corrosion testing to be performed on post-fatigued devices [Non-clinical tests and recommended labeling for intravascular stents and associated delivery systems: guidance for industry and FDA staff. 2005: Food and Drug Administration, Center for Devices and Radiological Health], although the need for this has been debated [Nagaraja S, et al., J Biomed Mater Res Part B: Appl Biomater 2016, 8.] This study seeks to evaluate the effect of fatigue on the corrosion resistance of 5 different materials commonly used in medical devices: 316 LVM stainless steel, MP35N cobalt chromium, electropolished nitinol, mechanically polished nitinol, and black oxide nitinol. Prior to corrosion testing per ASTM F2129, wires of each alloy were split into subgroups and subjected to either nothing (that is, as received); high strain fatigue for less than 8 min; short-term phosphate buffered saline (PBS) soak for less than 8 min; low strain fatigue for 8 days; or long-term PBS soak for 8 days. Results from corrosion testing showed that the rest potential trended to an equilibrium potential with increasing time in PBS and that there was no statistical (p > 0.05) difference in breakdown potential between the fatigued and matching PBS soak groups for 9 out of 10 test conditions. Our results suggest that under these nonfretting conditions, corrosion susceptibility as measured by breakdown potential per ASTM F2129 was unaffected by the fatigue condition. 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2019-2026, 2017. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Inhibitory self-control moderates the effect of changed implicit food evaluations on snack food consumption.

Science.gov (United States)

Haynes, Ashleigh; Kemps, Eva; Moffitt, Robyn

2015-07-01

The current study used a modified implicit association test (IAT) to change implicit evaluations of unhealthy snack food and tested its effects on subsequent consumption. Furthermore, we investigated whether these effects were moderated by inhibitory self-control. A sample of 148 women (17-25 years) motivated to manage weight through healthy eating completed an IAT intervention, and pre- and post-intervention IATs assessing implicit evaluations of unhealthy food. The intervention IAT trained participants to pair unhealthy food stimuli with either positive or negative stimuli. A task disguised as a taste-test was used to assess consumption of unhealthy snack foods. Inhibitory self-control was measured using a self-report scale. As predicted, the implicit evaluation of unhealthy food became more negative from pre- to post-training among participants in the food negative pairing condition; however, there was no corresponding change in the food positive pairing condition. The effect of the training on snack consumption was moderated by inhibitory self-control with only participants low in inhibitory self-control having lower snack intake following the food negative training. This finding is consistent with dual-process models of behaviour which predict that self-control capacity renders impulses less influential on behaviour. Furthermore, it suggests that an intervention that retrains implicit food evaluations could be effective at reducing unhealthy eating, particularly among those with low inhibitory self-control. Copyright © 2015 Elsevier Ltd. All rights reserved.

Eye Gaze and Aging: Selective and Combined Effects of Working Memory and Inhibitory Control

Directory of Open Access Journals (Sweden)

Trevor J. Crawford

2017-11-01

Full Text Available Eye-tracking is increasingly studied as a cognitive and biological marker for the early signs of neuropsychological and psychiatric disorders. However, in order to make further progress, a more comprehensive understanding of the age-related effects on eye-tracking is essential. The antisaccade task requires participants to make saccadic eye movements away from a prepotent stimulus. Speculation on the cause of the observed age-related differences in the antisaccade task largely centers around two sources of cognitive dysfunction: inhibitory control (IC and working memory (WM. The IC account views cognitive slowing and task errors as a direct result of the decline of inhibitory cognitive mechanisms. An alternative theory considers that a deterioration of WM is the cause of these age-related effects on behavior. The current study assessed IC and WM processes underpinning saccadic eye movements in young and older participants. This was achieved with three experimental conditions that systematically varied the extent to which WM and IC were taxed in the antisaccade task: a memory-guided task was used to explore the effect of increasing the WM load; a Go/No-Go task was used to explore the effect of increasing the inhibitory load; a ‘standard’ antisaccade task retained the standard WM and inhibitory loads. Saccadic eye movements were also examined in a control condition: the standard prosaccade task where the load of WM and IC were minimal or absent. Saccade latencies, error rates and the spatial accuracy of saccades of older participants were compared to the same measures in healthy young controls across the conditions. The results revealed that aging is associated with changes in both IC and WM. Increasing the inhibitory load was associated with increased reaction times in the older group, while the increased WM load and the inhibitory load contributed to an increase in the antisaccade errors. These results reveal that aging is associated with

Eye Gaze and Aging: Selective and Combined Effects of Working Memory and Inhibitory Control.

Science.gov (United States)

Crawford, Trevor J; Smith, Eleanor S; Berry, Donna M

2017-01-01

Eye-tracking is increasingly studied as a cognitive and biological marker for the early signs of neuropsychological and psychiatric disorders. However, in order to make further progress, a more comprehensive understanding of the age-related effects on eye-tracking is essential. The antisaccade task requires participants to make saccadic eye movements away from a prepotent stimulus. Speculation on the cause of the observed age-related differences in the antisaccade task largely centers around two sources of cognitive dysfunction: inhibitory control (IC) and working memory (WM). The IC account views cognitive slowing and task errors as a direct result of the decline of inhibitory cognitive mechanisms. An alternative theory considers that a deterioration of WM is the cause of these age-related effects on behavior. The current study assessed IC and WM processes underpinning saccadic eye movements in young and older participants. This was achieved with three experimental conditions that systematically varied the extent to which WM and IC were taxed in the antisaccade task: a memory-guided task was used to explore the effect of increasing the WM load; a Go/No-Go task was used to explore the effect of increasing the inhibitory load; a 'standard' antisaccade task retained the standard WM and inhibitory loads. Saccadic eye movements were also examined in a control condition: the standard prosaccade task where the load of WM and IC were minimal or absent. Saccade latencies, error rates and the spatial accuracy of saccades of older participants were compared to the same measures in healthy young controls across the conditions. The results revealed that aging is associated with changes in both IC and WM. Increasing the inhibitory load was associated with increased reaction times in the older group, while the increased WM load and the inhibitory load contributed to an increase in the antisaccade errors. These results reveal that aging is associated with changes in both IC and

α-Amylase and α-glucosidase inhibitory effects of Sclerocarya birrea ...

African Journals Online (AJOL)

Inhibition of intestinal α-amylase and α-glucosidase is an important strategy to control post-prandial hyperglycemia associated with type 2 diabetes mellitus. In vitro inhibitory effects of crude Sclerocarya birrea stem bark (SBSB) extracts against human urinary α-amylase and Bacillus steatothermophilus α-glucosidase were ...

The effect of flow and chemical corrosion in reverse osmosis over desalinated water

Energy Technology Data Exchange (ETDEWEB)

Kim, Young Jae [Chunnam National Univ., Gwangju (Korea, Republic of); Pak, Byung Gu [Doosan Heavy Industry Co., Tongyoung (Korea, Republic of)

2015-12-15

Desalinated water produced by a reverse osmosis (RO) filtering method forms about 22% of total production of desalinated water in the world. However, the RO environment is very corrosive due to the presence of various chemicals for water treatment and the flow of sand particles leading to corrosion. Recently, there has been much effort to substitute cheaper and more corrosion resistant stainless steels for copper based alloys as a valve material in RO. Nevertheless, the effects of chemicals and particles on the corrosion of stainless steels have rarely been studied. Erosion phenomenon was detected under the condition with the flow rate of more than 8ms{sup -1} in spite of the absence of sand particles. In seawater containing sand particles, the erosion in stainless steels was accelerated further.

Effect of Secondary Phase Precipitation on the Corrosion Behavior of Duplex Stainless Steels.

Science.gov (United States)

Chan, Kai Wang; Tjong, Sie Chin

2014-07-22

Duplex stainless steels (DSSs) with austenitic and ferritic phases have been increasingly used for many industrial applications due to their good mechanical properties and corrosion resistance in acidic, caustic and marine environments. However, DSSs are susceptible to intergranular, pitting and stress corrosion in corrosive environments due to the formation of secondary phases. Such phases are induced in DSSs during the fabrication, improper heat treatment, welding process and prolonged exposure to high temperatures during their service lives. These include the precipitation of sigma and chi phases at 700-900 °C and spinodal decomposition of ferritic grains into Cr-rich and Cr-poor phases at 350-550 °C, respectively. This article gives the state-of the-art review on the microstructural evolution of secondary phase formation and their effects on the corrosion behavior of DSSs.

Corrosion characteristics of K-claddings

International Nuclear Information System (INIS)

Park, J. Y.; Choi, B. K.; Jung, Y. H.; Jung, Y. H.

2004-01-01

The Improvement of the corrosion resistance of nuclear fuel claddings is the critical issue for the successful development of the high burn-up fuel. KAERI have developed the K-claddings having a superior corrosion resistance by controlling the alloying element addition and optimizing the manufacturing process. The comparative evaluation of the corrosion resistance for K-claddings and the foreign claddings was performed and the effect of the heat treatment on the corrosion behavior of K-claddings was also examined. Corrosion tests were carried out in the conditions of 360 .deg. C pure water, PWR-simulating loop and 400 .deg. C steam, From the results of the corrosion tests, it was found that the corrosion resistance of K-claddings is superior to those of Zry4 and A claddings and K6 showed a better corrosion resistance than K3. The corrosion behavior of K-cladding was strongly influenced by the final annealing rather than the intermediate annealing, and the corrosion resistance increased with decreasing the final annealing temperature

Effects of secondary phase and grain size on the corrosion of biodegradable Mg-Zn-Ca alloys.

Science.gov (United States)

Lu, Y; Bradshaw, A R; Chiu, Y L; Jones, I P

2015-03-01

The bio-corrosion behaviour of Mg-3Zn-0.3Ca (wt.%) alloy in simulated body fluid (SBF) at 37°C has been investigated using immersion testing and electrochemical measurements. Heat treatment has been used to alter the grain size and secondary phase volume fraction; the effects of these on the bio-corrosion behaviour of the alloy were then determined. The as-cast sample has the highest bio-corrosion rate due to micro-galvanic corrosion between the eutectic product (Mg+Ca2Mg6Zn3) and the surrounding magnesium matrix. The bio-corrosion resistance of the alloy can be improved by heat treatment. The volume fraction of secondary phases and grain size are both key factors controlling the bio-corrosion rate of the alloy. The bio-corrosion rate increases with volume fraction of secondary phase. When this is lower than 0.8%, the dependence of bio-corrosion rate becomes noticeable: large grains corrode more quickly. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of Neuromodulation on Excitatory-Inhibitory Neural Network Dynamics Depend on Network Connectivity Structure

Science.gov (United States)

Rich, Scott; Zochowski, Michal; Booth, Victoria

2018-01-01

Acetylcholine (ACh), one of the brain's most potent neuromodulators, can affect intrinsic neuron properties through blockade of an M-type potassium current. The effect of ACh on excitatory and inhibitory cells with this potassium channel modulates their membrane excitability, which in turn affects their tendency to synchronize in networks. Here, we study the resulting changes in dynamics in networks with inter-connected excitatory and inhibitory populations (E-I networks), which are ubiquitous in the brain. Utilizing biophysical models of E-I networks, we analyze how the network connectivity structure in terms of synaptic connectivity alters the influence of ACh on the generation of synchronous excitatory bursting. We investigate networks containing all combinations of excitatory and inhibitory cells with high (Type I properties) or low (Type II properties) modulatory tone. To vary network connectivity structure, we focus on the effects of the strengths of inter-connections between excitatory and inhibitory cells (E-I synapses and I-E synapses), and the strengths of intra-connections among excitatory cells (E-E synapses) and among inhibitory cells (I-I synapses). We show that the presence of ACh may or may not affect the generation of network synchrony depending on the network connectivity. Specifically, strong network inter-connectivity induces synchronous excitatory bursting regardless of the cellular propensity for synchronization, which aligns with predictions of the PING model. However, when a network's intra-connectivity dominates its inter-connectivity, the propensity for synchrony of either inhibitory or excitatory cells can determine the generation of network-wide bursting.

Effect of Pseudomonas fluorescens on Buried Steel Pipeline Corrosion.

Science.gov (United States)

Spark, Amy J; Law, David W; Ward, Liam P; Cole, Ivan S; Best, Adam S

2017-08-01

Buried steel infrastructure can be a source of iron ions for bacterial species, leading to microbiologically influenced corrosion (MIC). Localized corrosion of pipelines due to MIC is one of the key failure mechanisms of buried steel pipelines. In order to better understand the mechanisms of localized corrosion in soil, semisolid agar has been developed as an analogue for soil. Here, Pseudomonas fluorescens has been introduced to the system to understand how bacteria interact with steel. Through electrochemical testing including open circuit potentials, potentiodynamic scans, anodic potential holds, and electrochemical impedance spectroscopy it has been shown that P. fluorescens increases the rate of corrosion. Time for oxide and biofilms to develop was shown to not impact on the rate of corrosion but did alter the consistency of biofilm present and the viability of P. fluorescens following electrochemical testing. The proposed mechanism for increased corrosion rates of carbon steel involves the interactions of pyoverdine with the steel, preventing the formation of a cohesive passive layer, after initial cell attachment, followed by the formation of a metal concentration gradient on the steel surface.

Effects of acute buspirone administration on inhibitory control and sexual discounting in cocaine users.

Science.gov (United States)

Strickland, Justin C; Bolin, B Levi; Romanelli, Michael R; Rush, Craig R; Stoops, William W

2017-01-01

Cocaine users display deficits in inhibitory control and make impulsive choices that may increase risky behavior. Buspirone is an anxiolytic that activates dopaminergic and serotonergic systems and improves impulsive choice (i.e., reduces sexual risk-taking intent) in cocaine users when administered chronically. We evaluated the effects of acutely administered buspirone on inhibitory control and impulsive choice. Eleven subjects with a recent history of cocaine use completed this within-subject, placebo-controlled study. Subjects performed two cued go/no-go and a sexual risk delay-discounting task following oral administration of buspirone (10 and 30 mg), triazolam (0.375 mg; positive control), and placebo (negative control). Physiological and psychomotor performance and subject-rated data were also collected. Buspirone failed to change inhibitory control or impulsive choice; however, slower reaction times were observed at the highest dose tested. Buspirone did not produce subject-rated drug effects but dose-dependently decreased diastolic blood pressure. Triazolam impaired psychomotor performance and increased ratings of positive subject-rated effects (e.g., Like Drug). These findings indicate that acutely administered buspirone has little impact on behavioral measures of inhibitory control and impulsive sexual decision-making. Considering previous findings with chronic dosing, these findings highlight that the behavioral effects of buspirone differ as a function of dosing conditions. Copyright © 2017 John Wiley & Sons, Ltd.

Effects of crystalline growth on corrosion behaviour of ...

Indian Academy of Sciences (India)

tron microscopy and transmission electron microscopy. The corrosion behaviours ... sity and high melting point.7,8 This compound often shows good corrosion and .... Figure 4. TEM image of as-deposited nanocrystalline NiAl coating. Figure 5.

Effect of water flow rate and water chemistry on corrosion environment in reactor pressure vessel bottom of BWRs

Energy Technology Data Exchange (ETDEWEB)

Ichikawa, Nagayoshi; Hemmi, Yukio; Takagi, Junichi; Urata, Hidehiro [Toshiba Corp., Kawasaki, Kanagawa (Japan)

1999-07-01

To evaluate the corrosion environment at the bottom of the reactor pressure vessel in a BWR and the effect of hydrogen water chemistry on the corrosion of materials in the region, measurements of the corrosion potential of Type-304 stainless steel and nickel base alloy were made in a laboratory test loop. The effect of water chemistry on the corrosion potential of nickel base alloy is found to be similar to the effect on Type-304 stainless steel. Flow analysis and precise evaluations of the corrosion potential of materials in the bottom region were implemented. Corrosion potentials throughout the region were evaluated from the flow analysis results. At the jet pump outlet and shroud support leg, a rather large amount of hydrogen had to be added to reduce the potential. Conversely, a small amount of hydrogen was enough in the case of the stub tube of the control rod drive guide tubing and the ICM housings located in the center of the bottom region. (author)

Effect of water flow rate and water chemistry on corrosion environment in reactor pressure vessel bottom of BWRs

International Nuclear Information System (INIS)

Ichikawa, Nagayoshi; Hemmi, Yukio; Takagi, Junichi; Urata, Hidehiro

1999-01-01

To evaluate the corrosion environment at the bottom of the reactor pressure vessel in a BWR and the effect of hydrogen water chemistry on the corrosion of materials in the region, measurements of the corrosion potential of Type-304 stainless steel and nickel base alloy were made in a laboratory test loop. The effect of water chemistry on the corrosion potential of nickel base alloy is found to be similar to the effect on Type-304 stainless steel. Flow analysis and precise evaluations of the corrosion potential of materials in the bottom region were implemented. Corrosion potentials throughout the region were evaluated from the flow analysis results. At the jet pump outlet and shroud support leg, a rather large amount of hydrogen had to be added to reduce the potential. Conversely, a small amount of hydrogen was enough in the case of the stub tube of the control rod drive guide tubing and the ICM housings located in the center of the bottom region. (author)

The size effect in corrosion greatly influences the predicted life span of concrete infrastructures.

Science.gov (United States)

Angst, Ueli M; Elsener, Bernhard

2017-08-01

Forecasting the life of concrete infrastructures in corrosive environments presents a long-standing and socially relevant challenge in science and engineering. Chloride-induced corrosion of reinforcing steel in concrete is the main cause for premature degradation of concrete infrastructures worldwide. Since the middle of the past century, this challenge has been tackled by using a conceptual approach relying on a threshold chloride concentration for corrosion initiation ( C crit ). All state-of-the-art models for forecasting chloride-induced steel corrosion in concrete are based on this concept. We present an experiment that shows that C crit depends strongly on the exposed steel surface area. The smaller the tested specimen is, the higher and the more variable C crit becomes. This size effect in the ability of reinforced concrete to withstand corrosion can be explained by the local conditions at the steel-concrete interface, which exhibit pronounced spatial variability. The size effect has major implications for the future use of the common concept of C crit . It questions the applicability of laboratory results to engineering structures and the reproducibility of typically small-scale laboratory testing. Finally, we show that the weakest link theory is suitable to transform C crit from small to large dimensions, which lays the basis for taking the size effect into account in the science and engineering of forecasting the durability of infrastructures.

Effect of boric acid on intergranular corrosion in tube support plate crevices

International Nuclear Information System (INIS)

Brunet, J.P.; Campan, J.L.

1993-10-01

Intergranular attack on steam generator tubing is one important phenomenon involved in availability of Pressurized Water Reactors. Boric acid appears to be a possible candidate for inhibiting the corrosion process. The program performed in Cadarache was supposed to give statistical informations on the boric acid effect. It was based on a large number of samples initially attacked during a program performed by BABCOCK ampersand WILCOX. These samples were sleeved onto Alloy 690 tubes, in order to prevent premature cracking. Unfortunately it was not possible to find chemical conditions able to produce significant additional corrosion; we postulated mainly due to a drastic reduction of the thermal flux resulting from the increase of the tube wall thickness under the tube support plates (TSP). The tests demonstrate that such sleeve could be a possible remedy of the corrosion when introduced under the TSP. The tests show indications of a possible beneficial effect of the boric acid, a large variability of the heats sensitivity to the IGA and a predominant effect of Na 2 CO 3 on IGA production

Corrosion studies on PREPP waste form

International Nuclear Information System (INIS)

Welch, J.M.; Neilson, R.M. Jr.

1984-05-01

Deformation or Failure Test and Accelerated Corrosion Test procedures were conducted to investigate the effect of formulation variables on the corrosion of oversize waste in Process Experimental Pilot Plant (PREPP) concrete waste forms. The Deformation or Failure Test did not indicate substantial waste form swelling from corrosion. The presence or absence of corrosion inhibitor was the most significant factor relative to measured half-cell potentials identified in the Accelerated Corrosion Test. However, corrosion inhibitor was determined to be only marginally beneficial. While this study produced no evidence that corrosion is of sufficient magnitude to produce serious degradation of PREPP waste forms, the need for corrosion rate testing is suggested. 11 references, 4 figures, 8 tables

The effects of inhibitory control training for preschoolers on reasoning ability and neural activity

DEFF Research Database (Denmark)

Liu, Qian; Zhu, Xinyi; Ziegler, Albert

2015-01-01

Inhibitory control (including response inhibition and interference control) develops rapidly during the preschool period and is important for early cognitive development. This study aimed to determine the training and transfer effects on response inhibition in young children. Children....../week, for 3 weeks. Several cognitive tasks (involving inhibitory control, working memory, and fluid intelligence) were used to evaluate the transfer effects, and electroencephalography (EEG) was performed during a go/no-go task. Progress on the trained game was significant, while performance on a reasoning...

Effect of ion implantation on the corrosion behavior of lead and a lead-antimony alloy

International Nuclear Information System (INIS)

Zhang, S.T.; Kong, F.P.; Muller, R.H.

1994-01-01

Ion implantation of different metals in Pb and Pb-4% Sb has been found to improve the open-circuit corrosion resistance of the two metals in 5M H 2 SO 4 . Titanium ions were implanted under different conditions of ion dose and ion energy. Optimum implantation conditions resulted in an up to 72-fold reduction of corrosion currents. The implantation of V, Cr, Ni, and W has been investigated for one implantation condition and has also resulted in decreased corrosion currents. The corrosion behavior was characterized by the current response to small anodic potential steps. Surface analysis and depth profiles have shown the importance of the spatial distribution of the implanted ions for their effects on the anodic and cathodic parts of the corrosion reactions

Effect of cold working on the stress corrosion cracking resistance of nickel-chromium-iron alloys

International Nuclear Information System (INIS)

Yonezawa, T.; Onimura, K.

1987-01-01

In order to grasp the stress corrosion cracking resistance of cold worked nickel base alloys in PWR primary water, the effect of cold working on the stress corrosion cracking resistance of alloys 600, X-750 and 690, in high temperature water, have been studied. Stress corrosion cracking tests were conducted at 360 0 C (633K) in a simulated PWR primary water for about 12,000 hours (43.2Ms). From the test results, it is concluded that the stress corrosion cracking resistance in the cold worked Alloy 600 at the same applied stress level increases with an increase in cold working ratio, and the cold worked alloys of thermally treated 690 and X-750 have excellent stress corrosion cracking resistance. (Author)

Synergistic Effect of Molybdate and Monoethanolamine on Corrosion Inhibition of Ductile Cast Iron in Tap Water

Energy Technology Data Exchange (ETDEWEB)

Kim, K. T.; Kim, Y. S. [Andong National University, Andong (Korea, Republic of); Chang, H. Y.; Lim, B. T.; Park, H. B. [KEPCO Engineering and Construction Company, Gimcheon (Korea, Republic of)

2017-02-15

A synergistic effect was observed in the combination of nitrite and ethanolamines. Ethanolamine is one of the representative organic corrosion inhibitors and can be categorized as adsorption type. However, nitrosamines can form when amines mix with sodium nitrite. Since nitrosamine is a carcinogen, the co-addition of nitrite and ethanolamine will be not practical, and thus, a non-toxic combination of inhibitors shall be needed. In order to maximize the effect of monoethanolamine, we focused on the addition of molybdate. Molybdate has been used to alternate the addition of chromate, but it showed insufficient oxidizing power relative to corrosion inhibitors. This work evaluated the synergistic effect of the co-addition of molybdate and monoethanolamine, and its corrosion mechanism was elucidated. A high concentration of molybdate or monoethanolamine was needed to inhibit the corrosion of ductile cast iron in tap water, but in the case of the co-addition of molybdate and monoethanolamine, a synergistic effect was observed. This synergistic effect could be attributed to the molybdate that partly oxidizes the metallic surface and the monoethanolamine that is simultaneously adsorbed on the graphite surface. This adsorbed layer then acts as the barrier layer that mitigates galvanic corrosion between the graphite and the matrix.

Multifrequency Eddy Current Inspection of Corrosion in Clad Aluminum Riveted Lap Joints and Its Effect on Fatigue Life

Science.gov (United States)

Okafor, A. C.; Natarajan, S.

2007-03-01

Aging aircraft are prone to corrosion damage and fatigue cracks in riveted lap joints of fuselage skin panels. This can cause catastrophic failure if not detected and repaired. Hence detection of corrosion damage and monitoring its effect on structural integrity are essential. This paper presents multifrequency eddy current (EC) inspection of corrosion damage and machined material loss defect in clad A1 2024-T3 riveted lap joints and its effect on fatigue life. Results of eddy current inspection, corrosion product removal and fatigue testing are presented.

Multifrequency Eddy Current Inspection of Corrosion in Clad Aluminum Riveted Lap Joints and Its Effect on Fatigue Life

International Nuclear Information System (INIS)

Okafor, A. C.; Natarajan, S.

2007-01-01

Aging aircraft are prone to corrosion damage and fatigue cracks in riveted lap joints of fuselage skin panels. This can cause catastrophic failure if not detected and repaired. Hence detection of corrosion damage and monitoring its effect on structural integrity are essential. This paper presents multifrequency eddy current (EC) inspection of corrosion damage and machined material loss defect in clad A1 2024-T3 riveted lap joints and its effect on fatigue life. Results of eddy current inspection, corrosion product removal and fatigue testing are presented

Effects of annealing on the corrosion behavior and mechanical properties of Ti-Al-V alloy

International Nuclear Information System (INIS)

Kim, T. K.; Choi, B. S.; Baek, J. H.; Choi, B. K.; Jeong, Y. H.; Lee, D. J.; Jang, M. H.; Jeong, Y. H.

2002-01-01

In order to determine the annealing condition after cold rolling, the effects of annealing on the corrosion behavior and mechanical properties of Ti-Al-V alloy were evaluated. The results of tensile tests at room temperature showed that the strengths and the ductility were almost independent of the annealing temperature. The results of hardness test also revealed that the hardness was independent of the annealing, However, the results of corrosion test in an ammoniated water of pH 9.98 at 360 .deg. C showed that the corrosion resistance depended on the annealing temperature, and the corrosion rate was accelerated with increasing annealing temperature. Hydrogen contents absorbed during the corrosion test of 120 days also increased with the annealing temperature. It may be attributed to the growth of α' precipitates by annealing. It is thus suggested that the lower annealing temperatures provide the better corrosion properties without degrading the tensile properties

Catalytic and inhibitory effects of thechnetium on reduction processes

International Nuclear Information System (INIS)

Grases, F.; Genestar, C.; March, J.G.; March, P.

1986-01-01

Interactions between technetium and some anthraquinones and tartrazin in the presence of tin(II) are described. It was found that whereas the reductive process between Sn(II) and 1-amino-4-hydroxyanthraquinone is catalyzed by technetium, the reduction of tartrazin is inhibited by this element. Study of such process seems to indicate that the catalytic effect of technetium on the reduction processes is due to Tc(V) action whereas the inhibitory effect is due to the Tc(IV) species. (author)

Localized Corrosion of Alloy 22 -Fabrication Effects-FY05 Summary Report

International Nuclear Information System (INIS)

Rebak, R B

2005-01-01

general and localized corrosion behavior both in the wrought and annealed condition and in the as-welded condition. The specimens for testing were mostly prepared from flat plates of material. It was important to determine if the process of fabricating a full diameter Alloy 22 container will affect the corrosion performance of this alloy. Specimens were prepared directly from a fabricated container and tested for corrosion resistance. Results show that both the anodic corrosion behavior and the localized corrosion resistance of specimens prepared from a welded fabricated container were the same as from flat welded plates. That is, rolling and welding plates using industrial practices do not hinder the corrosion resistant of Alloy 22. (3) Effect of Black Annealing Oxide Scale--The resistance of Alloy 22 to localized corrosion, mainly crevice corrosion, has been extensively investigated in the last few years. This was done mostly using freshly polished specimens. At this time it was important to address the effect an oxide film or scale that forms during the high temperature annealing process or solution heat treatment (SHT) and its subsequent water quenching. Electrochemical tests such as cyclic potentiodynamic polarization (CPP) have been carried out to determine the repassivation potential for localized corrosion and to assess the mode of attack on the specimens. Tests have been carried out in parallel using mill annealed (MA) specimens free from oxide on the surface. The comparative testing was carried out in six different electrolyte solutions at temperatures ranging from 60 to 100 C. Results show that the repassivation potential of the specimens containing the black anneal oxide film on the surface was practically the same as the repassivation potential for oxide-free specimens. (4) Heat-to-Heat Variability--Testing of Ni-Cr-Mo Plates with varying heat chemistry: The ASTM standard B 575 provides the range of the chemical composition of Nickel-Chromium-Molybdenum (Ni

Microbiologically induced corrosion

International Nuclear Information System (INIS)

Stein, A.A.

1988-01-01

Biological attack is a problem that can affect all metallic materials in a variety of environments and systems. In the power industry, corrosion studies have focused on condensers and service water systems where slime, barnacles, clams, and other macro-organisms are easily detected. Efforts have been made to eliminate the effect of these organisms through the use of chlorination, backflushing, organic coating, or thermal shock. The objective is to maintain component performance by eliminating biofouling and reducing metallic corrosion. Recently, corrosion of power plant components by micro-organisms (bacteria) has been identified even in very clean systems. A system's first exposure to microbiologically induced corrosion (MIC) occurs during its first exposure to an aqueous environment, such as during hydrotest or wet layup. Corrosion of buried pipelines by sulfate-reducing bacteria has been studied by the petrochemical industry for years. This paper discusses various methods of diagnosing, monitoring, and controlling MIC in a variety of systems, as well as indicates areas where further study is needed

Inhibitory Effect of Waste Glass Powder on ASR Expansion Induced by Waste Glass Aggregate

Directory of Open Access Journals (Sweden)

Shuhua Liu

2015-10-01

Full Text Available Detailed research is carried out to ascertain the inhibitory effect of waste glass powder (WGP on alkali-silica reaction (ASR expansion induced by waste glass aggregate in this paper. The alkali reactivity of waste glass aggregate is examined by two methods in accordance with the China Test Code SL352-2006. The potential of WGP to control the ASR expansion is determined in terms of mean diameter, specific surface area, content of WGP and curing temperature. Two mathematical models are developed to estimate the inhibitory efficiency of WGP. These studies show that there is ASR risk with an ASR expansion rate over 0.2% when the sand contains more than 30% glass aggregate. However, WGP can effectively control the ASR expansion and inhibit the expansion rate induced by the glass aggregate to be under 0.1%. The two mathematical models have good simulation results, which can be used to evaluate the inhibitory effect of WGP on ASR risk.

Stochastic theory of fatigue corrosion

Science.gov (United States)

Hu, Haiyun

1999-10-01

A stochastic theory of corrosion has been constructed. The stochastic equations are described giving the transportation corrosion rate and fluctuation corrosion coefficient. In addition the pit diameter distribution function, the average pit diameter and the most probable pit diameter including other related empirical formula have been derived. In order to clarify the effect of stress range on the initiation and growth behaviour of pitting corrosion, round smooth specimen were tested under cyclic loading in 3.5% NaCl solution.

Effect of temperature on structure and corrosion resistance for ...

Indian Academy of Sciences (India)

The effect of plating temperatures between 60 and 90◦C on structure and corrosion resistance for elec- troless NiWP coatings ..... which helps to form fine grain. At 80 .... [23] Zhang W X, Jiang Z H, Li G Y and Jiang Q 2008 Surf. Coat. Technol.

The effect of zinc thickness on corrosion film breakdown of Colombian galvanized steel

Science.gov (United States)

Sandoval-Amador, A.; E Torres Ramirez, J.; Cabrales-Villamizar, P. A.; Laverde Cataño, D.; Y Peña-Ballesteros, D.

2017-12-01

This work studies the corrosion behaviour of Colombian galvanized steel in solutions of chloride and sulphate ions. The effect of the thickness and exposure time on the film’s breakdown susceptibility and protectiveness of the corrosion products were studied using potentiodynamic polarization curves and electrochemical impedance spectroscopy. The corrosion products were analysed using SEM-EDS and XRD. The samples with a higher thickness level in the zinc film (Z180) have the lowest corrosion rate. In this case, one of the products that was formed by the chemical reactions that occurred was Zinc hydroxide, which exhibits a passive behaviour as observed in the Pourbaix curves of the obtained potentials and in how the different Ph levels of the solutions worked. The sheets with the highest thickness (Z180) had the best performance, since at the end of the study they showed the least amount of damage on the surface of the zinc layer. This is because the thickness of the zinc layer favours the formation of simonkolleite, which is the corrosion product that protects the material under the conditions of the study.

Effect of H2O2 on the corrosion behavior of 304L stainless steel

International Nuclear Information System (INIS)

Song, Taek Ho

1994-02-01

In connection with the safe storage of high level nuclear waste, effect of H 2 O 2 on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H 2 O 2 . The experimental results show that H 2 O 2 increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H 2 O 2 concentration increased, indicating that pitting resistance was decreased by the existence of H 2 O 2 in the electrolyte. These effects of H 2 O 2 on corrosion of 304L stainless steel are considered to be similar to those of γ-irradiation. To compare the effects of H 2 O 2 with those of O 2 , cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H 2 O 2 on the corrosion behavior were very similar to those of O 2 such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. Further, H 2 O 2 played much greater role in controlling cathodic reaction rate in neutral water environment. In acid and alkaline media, potential shifts by H 2 O 2 were restricted by the large current density of proton reduction and by the le Chatelier's principle respectively

A review on the effect of welding on the corrosion of magnesium alloys

Science.gov (United States)

Mohamed, N. S.; Alias, J.

2017-10-01

Welding is an important joining technique for lightweight alloys with their increasing applications in aerospace, aircraft, automotive, electronics and other industries. The applications of lightweight alloys particularly magnesium alloys increased rapidly due to their beneficial properties such as low density, high strength-to-mass ratio, good dimensional stability, electromagnetic shielding and good recyclability. The effect of welding on the corrosion of magnesium alloys are reviewed in this paper, which closely related to the developed microstructure by the welding process. The paper focuses particularly on friction stir and laser welding. The basic principles of friction stir and laser welding are discussed, to present the likelihood of defects which significantly affect the corrosion of magnesium alloy. The finding in corrosion demonstrated the morphology of corrosion occurrence on each welded region, and observation on the potential and current values are also included.

Effect of Secondary Phase Precipitation on the Corrosion Behavior of Duplex Stainless Steels

Directory of Open Access Journals (Sweden)

Kai Wang Chan

2014-07-01

Full Text Available Duplex stainless steels (DSSs with austenitic and ferritic phases have been increasingly used for many industrial applications due to their good mechanical properties and corrosion resistance in acidic, caustic and marine environments. However, DSSs are susceptible to intergranular, pitting and stress corrosion in corrosive environments due to the formation of secondary phases. Such phases are induced in DSSs during the fabrication, improper heat treatment, welding process and prolonged exposure to high temperatures during their service lives. These include the precipitation of sigma and chi phases at 700–900 °C and spinodal decomposition of ferritic grains into Cr-rich and Cr-poor phases at 350–550 °C, respectively. This article gives the state-of the-art review on the microstructural evolution of secondary phase formation and their effects on the corrosion behavior of DSSs.

Smart Coatings for Corrosion Protection

Science.gov (United States)

Calle, Luz Marina; Li, Wendy; Buhrow, Jerry W.; Johnsey, Marissa N.

2016-01-01

Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. It is essential to detect corrosion when it occurs, and preferably at its early stage, so that action can be taken to avoid structural damage or loss of function. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional, smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it.

The effects of water radiolysis on the corrosion and stress corrosion behavior of type 316 stainless steel in pure water

International Nuclear Information System (INIS)

Wyllie, W.E. II; Duquette, D.J.; Steiner, D.

1994-11-01

In the ITER Conceptual Design Activity, water will be used as coolant for the major reactor components, which will be made of solution-annealed 316 SS. A concern is that the radiolysis products may increase the stress corrosion cracking (SCC) susceptibility of 316 SS. The corrosion and stress corrosion of 316 SS was observed under irradiated and nonirradiated conditions. Gamma irradiation produced a 100 mV potential shift in the active direction, probably from the polarizing effect of reducing radiolysis products. The irradiation also resulted in nearly an order of magnitude increase in the passive current density of 316 SS, probably from increased surface reaction rates involving radiolysis products as well as increased corrosion rates; however the latter was considered insignificant. Computer simulations of pure water radiolysis at 50, 90, and 130 C and dose rates of 10 18 -10 24 were performed; effects of hydrogen, argon, and argon + 20% oxygen deaeration were also studied. Slow strain rate suggest that annealed and sensitized 316 SS was not suscepible to SCC in hydrogen- or argon-deaerated water at 50 C. Modeling of irradiated water chemistry was performed. Open circuit potential of senstizied and annealed 316 SS had a shift of 800 mV in the noble (positive) direction. Steady-state potentials of -0.180 V for sensitized 316 SS wire and -0.096 V vs Hg/HgSO 4 for annealed 316 SS wire were independent of oxygen presence. The -0.180 V shift is likely to promote SCC

Shadow Corrosion Mechanism of Zircaloy

International Nuclear Information System (INIS)

Ullberg, Mats; Lysell, Gunnar; Nystrand, Ann-Charlotte

2004-02-01

Local corrosion enhancement appears on zirconium-base alloys in-core in boiling water reactors when the zirconium alloy is in close proximity to another metal. The visual appearance often resembles a shadow of the other component. The phenomenon is therefore referred to as 'shadow corrosion'. Shadow corrosion has been known for more than 25 years. Mechanisms based on either galvanic corrosion or local radiolysis effects have been proposed as explanations. Both types of mechanism have seemed to explain some facets of the phenomenon. Normally, shadow corrosion is of no practical significance. However, an enhanced and potentially serious form of shadow corrosion was discovered in 1996. This discovery stimulated new experiments that fully supported neither of the longstanding theories. Thus, there is till now no generally accepted understanding of the shadow corrosion phenomenon. The aim of the present investigation was to analyse the available data and to identify, if possible, a plausible mechanism of shadow corrosion. It was found that the experimental evidence is, with a few exceptions, remarkably consistent with a galvanic mechanism. The main exception is that shadow corrosion may occur also when the two metals are nominally electrically insulated. One way to account for the main exception could be to invoke the effect of photoconductivity. Photoconductivity results when a semiconductor or an insulator is irradiated with photons of UV or higher energy. The photons elevate electrons from the valence band to the conduction band, thereby raising the electron conductivity of the solid. In particular, photoconductivity lowers the electrical resistance of the normally insulating oxide on zirconium base alloys. Photoconductivity therefore also has the potential to explain why shadow corrosion is only seen in, or in proximity to, a nuclear reactor core. The suggested mechanism of shadow corrosion can be tested in a reasonably simple experiment in a research reactor

Adsorption behavior of caffeine as a green corrosion inhibitor for copper

Energy Technology Data Exchange (ETDEWEB)

Souza, Fernando Silvio de [Grupo de Estudos de Processos Eletroquimicos e Eletroanaliticos, Departamento de Quimica, Universidade Federal de Santa Catarina, 88040-900, Florianopolis, SC (Brazil); Giacomelli, Cristiano [Departamento de Quimica, Universidade Federal de Santa Maria, Av. Roraima 1000, 97119-900, Santa Maria, RS (Brazil); Goncalves, Reinaldo Simoes [Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, 91501-970, Porto Alegre, RS (Brazil); Spinelli, Almir, E-mail: almir.spinelli@ufsc.br [Grupo de Estudos de Processos Eletroquimicos e Eletroanaliticos, Departamento de Quimica, Universidade Federal de Santa Catarina, 88040-900, Florianopolis, SC (Brazil)

2012-12-01

Electrochemical and impedance experiments were carried out to evaluate the corrosion behavior of copper in aerated 0.1 mol L{sup -1} H{sub 2}SO{sub 4} solutions in the presence of three xanthine derivatives with similar chemical structures. The corrosion rate of copper was found to increase in the presence of theophylline and theobromine and decrease in the presence of caffeine. The adsorption and inhibitory effect of caffeine on copper surfaces in aerated 0.1 mol L{sup -1} H{sub 2}SO{sub 4} solutions were then investigated in detail by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), contact angle measurements, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and fluorescence experiments. The data obtained indicate that caffeine behaves as a cathodic-type inhibitor adsorbing onto the copper surface according to the Temkin isotherm, with the negative Increment G Degree-Sign {sub ads} value of - 31.1 kJ mol{sup -1} signifying a spontaneous adsorption process. The corrosion inhibition efficiency increased with caffeine concentration in the range of 1.0-10.0 mmol L{sup -1}. Furthermore, the EIS results obtained at the open-circuit potential and surface analysis (SEM, EDS and fluorescence) clearly demonstrated the adsorption of the organic compound onto the copper electrode. The contact angle measurements revealed the formation of a hydrophobic protective film. This film covers up to 72% of the total active surface, acts as a protective barrier and prevents interaction between the metal, water and oxygen molecules. - Highlights: Black-Right-Pointing-Pointer We have investigated the adsorption and corrosion inhibition of caffeine on copper surfaces. Black-Right-Pointing-Pointer Caffeine behaves as a cathodic-type inhibitor. Black-Right-Pointing-Pointer Caffeine adsorbs onto copper surface according to Temkin isotherm. Black-Right-Pointing-Pointer There exists the formation of a hydrophobic film that acts as a

Corrosion in Electronics

DEFF Research Database (Denmark)

Ambat, Rajan; Gudla, Helene Virginie Conseil; Verdingovas, Vadimas

2017-01-01

Electronic control units, power modules, and consumer electronics are used today in a wide variety of varying climatic conditions. Varying external climatic conditions of temperature and humidity can cause an uncontrolled local climate inside the device enclosure. Uncontrolled humidity together...... and high density packing combined with the use of several materials, which can undergo electrochemical corrosion in the presence of water film formed due to humidity exposure and bias conditions on the PCBA surface. This article provides a short review of the corrosion reliability issues of electronics due...... to the use of electronics under varying humidity conditions. Important PCBA aspects, which are fundamental to the corrosion cell formation under humid conditions, are discussed. Effect of hygroscopic residues from the process and service and their role in assisting water film build up and corrosion...

Probing inhibitory effects of nanocrystalline cellulose: inhibition versus surface charge

Science.gov (United States)

Male, Keith B.; Leung, Alfred C. W.; Montes, Johnny; Kamen, Amine; Luong, John H. T.

2012-02-01

NCC derived from different biomass sources was probed for its plausible cytotoxicity by electric cell-substrate impedance sensing (ECIS). Two different cell lines, Spodoptera frugiperda Sf9 insect cells and Chinese hamster lung fibroblast V79, were exposed to NCC and their spreading and viability were monitored and quantified by ECIS. Based on the 50%-inhibition concentration (ECIS50), none of the NCC produced was judged to have any significant cytotoxicity on these two cell lines. However, NCC derived from flax exhibited the most pronounced inhibition on Sf9 compared to hemp and cellulose powder. NCCs from flax and hemp pre-treated with pectate lyase were also less inhibitory than NCCs prepared from untreated flax and hemp. Results also suggested a correlation between the inhibitory effect and the carboxylic acid contents on the NCC.

Effect Mo Addition on Corrosion Property and Sulfide Stress Cracking Susceptibility of High Strength Low Alloy Steels

International Nuclear Information System (INIS)

Lee, Woo Yong; Koh, Seong Ung; Kim, Kyoo Young

2005-01-01

The purpose of this work is to understand the effect of Mo addition on SSC susceptibility of high strength low alloy steels in terms of microstructure and corrosion property. Materials used in this study are high strength low alloy (HSLA) steels with carbon content of 0.04wt% and Mo content varying from 0.1 to 0.3wt%. The corrosion property of steels was evaluated by immersion test in NACE-TM01-77 solution A and by analyzing the growth behavior of surface corrosion products. SSC resistance of steels was evaluated using constant load test. Electrochemical test was performed to investigate initial corrosion rate. Addition of Mo increased corrosion rate of steels by enhancing the porosity of surface corrosion products. however, corrosion rate was not directly related to SSC susceptibility of steels

Effect of Additional Sulfide and Thiosulfate on Corrosion of Q235 Carbon Steel in Alkaline Solutions

Directory of Open Access Journals (Sweden)

Bian Li Quan

2016-01-01

Full Text Available This paper investigated the effect of additional sulfide and thiosulfate on Q235 carbon steel corrosion in alkaline solutions. Weight loss method, scanning electron microscopy (SEM equipped with EDS, X-ray photoelectron spectroscopy (XPS, and electrochemical measurements were used in this study to show the corrosion behavior and electrochemistry of Q235 carbon steel. Results indicate that the synergistic corrosion rate of Q235 carbon steel in alkaline solution containing sulfide and thiosulfate is larger than that of sulfide and thiosulfate alone, which could be due to redox reaction of sulfide and thiosulfate. The surface cracks and pitting characteristics of the specimens after corrosion were carefully examined and the corrosion products film is flake grains and defective. The main corrosion products of specimen induced by S2− and S2O32- are FeS, FeS2, Fe3O4, and FeOOH. The present study shows that the corrosion mechanism of S2− and S2O32- is different for the corrosion of Q235 carbon steel.

Emerging Corrosion Inhibitors for Interfacial Coating

Directory of Open Access Journals (Sweden)

Mona Taghavikish

2017-12-01

Full Text Available Corrosion is a deterioration of a metal due to reaction with environment. The use of corrosion inhibitors is one of the most effective ways of protecting metal surfaces against corrosion. Their effectiveness is related to the chemical composition, their molecular structures and affinities for adsorption on the metal surface. This review focuses on the potential of ionic liquid, polyionic liquid (PIL and graphene as promising corrosion inhibitors in emerging coatings due to their remarkable properties and various embedment or fabrication strategies. The review begins with a precise description of the synthesis, characterization and structure-property-performance relationship of such inhibitors for anti-corrosion coatings. It establishes a platform for the formation of new generation of PIL based coatings and shows that PIL corrosion inhibitors with various heteroatoms in different form can be employed for corrosion protection with higher barrier properties and protection of metal surface. However, such study is still in its infancy and there is significant scope to further develop new structures of PIL based corrosion inhibitors and coatings and study their behaviour in protection of metals. Besides, it is identified that the combination of ionic liquid, PIL and graphene could possibly contribute to the development of the ultimate corrosion inhibitor based coating.

Synergistic Effect of Potassium Iodide on Corrosion Inhibition of Mild ...

African Journals Online (AJOL)

MICHAEL

fruticans' wurmb extract on corrosion of mild steel in 0.1M and 0.5M HCl have been investigated using weight loss methods. ... efficient ways of combating the corrosion of metals. Among other ..... chloride ion on cold rolled steel corrosion.

Grain size effect in corrosion behavior of electrodeposited nanocrystalline Ni coatings in alkaline solution

International Nuclear Information System (INIS)

Wang Liping; Zhang Junyan; Gao Yan; Xue Qunji; Hu Litian; Xu Tao

2006-01-01

Effects of grain size reduction on the electrochemical corrosion behavior of nanocrystalline Ni produced by pulse electrodeposition were characterized using potentiodynamic polarization testing and electrochemical impedance spectroscopy; X-ray photoelectron spectroscopy were used to confirm the electrochemical measurements and the suggested mechanisms. The corrosion resistance of Ni coatings in alkaline solutions considerably increased as the grain size decreased from microcrystalline to nanocrystalline. The higher corrosion resistance of NC Ni may be due to the more rapid formation of continuous Ni(OH) 2 passive films compared with coarse-grained Ni coatings

Evaluation of microstructural effects on the corrosion behaviour of AZ91D magnesium alloy

DEFF Research Database (Denmark)

Ambat, Rajan; Aung, Naing Naing; Zhou, W.

2000-01-01

The effect of microconstituents on the corrosion and electrochemical behaviour of AZ91D alloy prepared by die-casting and ingot casting route has been investigated in 3.5% NaCl solution at pH 7.25. The experimental techniques used include constant immersion technique, in-situ corrosion monitoring....... The corrosion products for ingot consisted of Mg(OH)(2) with small amounts beta phase, magnesium-aluminum oxide and MgH2 while for die-cast, the product showed a highly amorphous structure. (C) 2000 Elsevier Science Ltd. All rights reserved....

Effect of yttrium chromite doping on its resistance to high-temperature salt and gas corrosions

International Nuclear Information System (INIS)

Oryshich, I.V.; Poryadchenko, N.E.; Rakitskij, A.N.; Bega, N.D.

1996-01-01

Effect of yttrium chromite doping with 2-4 group metal oxides on the corrosion resistance in the air at 1300 C during 5 hours and in sodium chloride and sulfate melts at 900 C during 20 hours is investigated. A notable increase of corrosion resistance is achieved under complex doping with zirconium and magnesium oxides in a quantity, close to solubility in yttrium oxide and solubility by aluminium oxide. Doping with calcium and strontium oxides in the quantities, dose to solubility in yttrium oxide does not produce any notable effect, and at higher concentrations it reduces the corrosion resistance in media indicated. Refs. 8, refs. 2, tabs. 1

Acid corrosion inhibitor

Energy Technology Data Exchange (ETDEWEB)

Chen, N G

1964-04-28

An acid corrosion inhibitor is prepared by a 2-stage vacuum evaporation of effluents obtained from the ammonia columns of the coking oven plant. The effluent, leaving a scrubber in which the phenols are removed at a temperature of 98$C, passes through a quartz filter and flows into a heated chamber in which it is used for preheating a solution circulating through a vacuum unit, maintaining the temperature of the solution at 55$ to 60$C. The effluent enters a large tank in which it is boiled at 55$ to 60$C under 635 to 640 mm Hg pressure. Double evaporation of this solution yields a very effective acid corrosion inhibitor. Its corrosion-preventing effect is 97.9% compared with 90.1% for thiourea and 88.5% for urotropin under identical conditions.

Anterograde effects of a single electroconvulsive shock on inhibitory avoidance and on cued fear conditioning

Directory of Open Access Journals (Sweden)

Oliveira M.G.M.

1998-01-01

Full Text Available A single electroconvulsive shock (ECS or a sham ECS was administered to male 3-4-month-old Wistar rats 1, 2, and 4 h before training in an inhibitory avoidance test and in cued classical fear conditioning (measured by means of freezing time in a new environment. ECS impaired inhibitory avoidance at all times and, at 1 or 2 h before training, reduced freezing time before and after re-presentation of the ECS. These results are interpreted as a transient conditioned stimulus (CS-induced anxiolytic or analgesic effect lasting about 2 h after a single treatment, in addition to the known amnesic effect of the stimulus. This suggests that the effect of anterograde learning impairment is demonstrated unequivocally only when the analgesic/anxiolytic effect is over (about 4 h after ECS administration and that this impairment of learning is selective, affecting inhibitory avoidance but not classical fear conditioning to a discrete stimulus.

Monitoring and modeling stress corrosion and corrosion fatigue damage in nuclear reactors

International Nuclear Information System (INIS)

Andresen, P.L.; Ford, F.P.; Solomon, H.D.; Taylor, D.F.

1990-01-01

Stress corrosion and corrosion fatigue are significant problems in many industries, causing economic penalties from decreased plant availability and component repair or replacement. In nuclear power reactors, environmental cracking occurs in a wide variety of components, including reactor piping and steam generator tubing, bolting materials and pressure vessels. Life assessment for these components is complicated by the belief that cracking is quite irreproducible. Indeed, for conditions which were once viewed as nominally similar, orders of magnitude variability in crack growth rates are observed for stress corrosion and corrosion fatigue of stainless steels and low-alloy steels in 288 degrees C water. This paper shows that design and life prediction approaches are destined to be overly conservative or to risk environmental failure if life is predicted by quantifying only the effects of mechanical parameters and/or simply ignoring or aggregating environmental and material variabilities. Examples include the Nuclear Regulatory Commission (NRC) disposition line for stress-corrosion cracking of stainless steel in boiling water reactor (BWR) water and the American Society of Mechanical Engineers' Section XI lines for corrosion fatigue

Effects of chloride ions on corrosion of ductile iron and carbon steel in soil environments.

Science.gov (United States)

Song, Yarong; Jiang, Guangming; Chen, Ying; Zhao, Peng; Tian, Yimei

2017-07-31

Chloride is reported to play a significant role in corrosion reactions, products and kinetics of ferrous metals. To enhance the understanding of the effects of soil environments, especially the saline soils with high levels of chloride, on the corrosion of ductile iron and carbon steel, a 3-month corrosion test was carried out by exposing ferrous metals to soils of six chloride concentrations. The surface morphology, rust compositions and corrosion kinetics were comprehensively studied by visual observation, scanning electron microscopy (SEM), X-Ray diffraction (XRD), weight loss, pit depth measurement, linear polarization and electrochemical impedance spectroscopy (EIS) measurements. It showed that chloride ions influenced the characteristics and compositions of rust layers by diverting and participating in corrosion reactions. α-FeOOH, γ-FeOOH and iron oxides were major corrosion products, while β-Fe 8 O 8 (OH) 8 Cl 1.35 rather than β-FeOOH was formed when high chloride concentrations were provided. Chloride also suppressed the decreasing of corrosion rates, whereas increased the difficulty in the diffusion process by thickening the rust layers and transforming the rust compositions. Carbon steel is more susceptible to chloride attacks than ductile iron. The corrosion kinetics of ductile iron and carbon steel corresponded with the probabilistic and bilinear model respectively.

Current status of studies on nodular corrosion

International Nuclear Information System (INIS)

Yasuda, Takayoshi; Kawasaki, Satoru; Echigoya, Hironori; Kinoshita, Yutaka; Kubota, Hiroyuki; Konishi, Takao; Yamanaka, Tuneyasu.

1993-01-01

The studies on nodular corrosion formed on the outer surface of BWR fuel cladding tubes were reviewed. Main factors affecting the corrosion behavior were material and environmental conditions and combined effect. The effects of such material conditions as fabrication process, alloy elements, texture and surface treatment and environmental factors as neutron irradiation, thermo-hydrodynamic, water chemistry, purity of the coolant and contact with foreign metals on the corrosion phenomena were surveyed. Out-of-reactor corrosion test methods and models for the corrosion mechanism were also reviewed. Suppression of the accumulated annealing temperature during tube reduction process improved the nodular corrosion resistance of Zircaloys. Improved resistance for the nodular corrosion was reported for the unirradiated Zircaloys with some additives. Detailed irradiation test under the BWR conditions is needed to confirm the trend. Concerning the environmental factors, boiling on the cladding surface due to heat flux reduces the nodular corrosion susceptibility, while oxidizing radical generated from dissolved oxygen accelerates the corrosion. Concerning corrosion mechanisms, importance of such phenomena as the depleted zone of alloying elements in zirconium matrix, reduction of H + to H 2 in oxide layer, electrochemical property of precipitates, crystallographic anisotropy of oxidation rates were revealed. (author) 59 refs

Effect of water chemistry on corrosion of stainless steel and deposition of corrosion products in high temperature pressurised water

International Nuclear Information System (INIS)

Morrison, Jonathan; Cooper, Christopher; Ponton, Clive; Connolly, Brian; Banks, Andrew

2012-09-01

In any water-cooled nuclear reactor, the corrosion of the structural materials in contact with the coolant and the deposition of the resulting oxidised species has long been an operational concern within the power generation industry. Corrosion of the structural materials at all points in the reactor leads to low concentrations of oxidised metal species in the coolant water. The oxidised metal species can subsequently be deposited out as CRUD deposits at various points around the reactor's primary and secondary loops. The deposition of soluble oxidised material at any location in the reactor cooling system is undesirable due to several effects; deposits have a porous structure, capable of incorporating radiologically active material (forming out of core radiation fields) and concentrating aggressively corrosive chemicals, which exacerbate environmental degradation of structural and fuel-cladding materials. Deposits on heat transfer surfaces also limit efficiency of the system as a whole. The work in this programme is an attempt to determine and understand the fundamental corrosion and deposition behaviour under controlled, simulated reactor conditions. The rates of corrosion of structural materials within pressurised water reactors are heavily dependent on the condition of the exposed surface. The effect of mechanical grinding and of electropolishing on the corrosion rate and structure of the resultant oxide film formed on grade 316L stainless steel exposed to high purity water, modified to pH 9.5 and 10.5 at temperatures between 200 and 300 deg. C and pressures of up to 100 bar will be investigated. The corrosion of stainless steel in water via electrochemical oxidation leads to the formation of surface iron, nickel and chromium based spinels. Low concentrations of these spinels can be found dissolved in the coolant water. The solubility of magnetite, stainless steels' major corrosion product, in high purity water will be studied at pH 9.5 to 10.5 at

Inhibitory Effect of Lactococcus lactis HY 449 on Cariogenic Biofilm.

Science.gov (United States)

Kim, Young-Jae; Lee, Sung-Hoon

2016-11-28

Dental caries is caused by cariogenic biofilm, an oral biofilm including Streptococcus mutans . Recently, the prevention of dental caries using various probiotics has been attempted. Lactococcus lactis HY 449 is a probiotic bacterium. The aim of this study was to investigate the effect of L. lactis HY 449 on cariogenic biofilm and to analyze its inhibitory mechanisms. Cariogenic biofilm was formed in the presence or absence of L. lactis HY 449 and L. lactis ATCC 19435, and analyzed with a confocal laser microscope. The formation of cariogenic biofilm was reduced in cultures spiked with both L. lactis strains, and L. lactis HY 449 exhibited more inhibitory effects than L. lactis ATCC 19435. In order to analyze and to compare the inhibitory mechanisms, the antibacterial activity of the spent culture medium from both L. lactis strains against S. mutans was investigated, and the expression of glucosyltransferases ( gtfs ) of S. mutans was then analyzed by real-time RT-PCR. In addition, the sucrose fermentation ability of both L. lactis strains was examined. Both L. lactis strains showed antibacterial activity and inhibited the expression of gtfs , and the difference between both strains did not show. In the case of sucrose-fermenting ability, L. lactis HY 449 fermented sucrose but L. lactis ATCC 19435 did not. L. lactis HY 449 inhibited the uptake of sucrose and the gtfs expression of S. mutans , whereby the development of cariogenic biofilm may be inhibited. In conclusion, L. lactis HY 449 may be a useful probiotic for the prevention of dental caries.

A New Corrosion Sensor to Determine the Start and Development of Embedded Rebar Corrosion Process at Coastal Concrete

Directory of Open Access Journals (Sweden)

Weiliang Jin

2013-09-01

Full Text Available The corrosion of reinforcements induced by chloride has resulted to be one of the most frequent causes of their premature damage. Most corrosion sensors were designed to monitor corrosion state in concrete, such as Anode-Ladder-System and Corrowatch System, which are widely used to monitor chloride ingress in marine concrete. However, the monitoring principle of these corrosion sensors is based on the macro-cell test method, so erroneous information may be obtained, especially from concrete under drying or saturated conditions due to concrete resistance taking control in macro-cell corrosion. In this paper, a fast weak polarization method to test corrosion state of reinforcements based on electrochemical polarization dynamics was proposed. Furthermore, a new corrosion sensor for monitoring the corrosion state of concrete cover was developed based on the proposed test method. The sensor was tested in cement mortar, with dry-wet cycle tests to accelerate the chloride ingress rate. The results show that the corrosion sensor can effectively monitor chloride penetration into concrete with little influence of the relative humidity in the concrete. With a reasonable corrosion sensor electrode arrangement, it seems the Ohm-drop effect measured by EIS can be ignored, which makes the tested electrochemical parameters more accurate.

A new corrosion sensor to determine the start and development of embedded rebar corrosion process at coastal concrete.

Science.gov (United States)

Xu, Chen; Li, Zhiyuan; Jin, Weiliang

2013-09-30

The corrosion of reinforcements induced by chloride has resulted to be one of the most frequent causes of their premature damage. Most corrosion sensors were designed to monitor corrosion state in concrete, such as Anode-Ladder-System and Corrowatch System, which are widely used to monitor chloride ingress in marine concrete. However, the monitoring principle of these corrosion sensors is based on the macro-cell test method, so erroneous information may be obtained, especially from concrete under drying or saturated conditions due to concrete resistance taking control in macro-cell corrosion. In this paper, a fast weak polarization method to test corrosion state of reinforcements based on electrochemical polarization dynamics was proposed. Furthermore, a new corrosion sensor for monitoring the corrosion state of concrete cover was developed based on the proposed test method. The sensor was tested in cement mortar, with dry-wet cycle tests to accelerate the chloride ingress rate. The results show that the corrosion sensor can effectively monitor chloride penetration into concrete with little influence of the relative humidity in the concrete. With a reasonable corrosion sensor electrode arrangement, it seems the Ohm-drop effect measured by EIS can be ignored, which makes the tested electrochemical parameters more accurate.

A study of the effect of clinical washing decontamination process on corrosion resistance of Martensitic Stainless Steel 420.

Science.gov (United States)

Xu, Yunwei; Huang, Zhihong; Corner, George

2016-09-28

Corrosion of surgical instruments provides a seat for contamination and prevents proper sterilisation, placing both patients and medical staff at risk of infection. Corrosion can also compromise the structural integrity of instruments and lead to mechanical failure in use. It is essential to understand the various factors affecting corrosion resistance of surgical instruments and how it can be minimised.This paper investigates the effect on corrosion resistance from the clinical washing decontamination (WD) process, specifically by studying the changes in surface roughness and Cr/Fe ratio. Results indicate that the WD process provides a positive effect on smooth polished samples, while a lesser positive effect was observed on rough reflection reduced samples.

Stress corrosion in high-strength aluminum alloys

Science.gov (United States)

Dorward, R. C.; Hasse, K. R.

1980-01-01

Report describes results of stress-corrosion tests on aluminum alloys 7075, 7475, 7050, and 7049. Tests compare performance of original stress-corrosion-resistant (SCR) aluminum, 7075, with newer, higher-strength SCR alloys. Alloys 7050 and 7049 are found superior in short-transverse cross-corrosion resistance to older 7075 alloy; all alloys are subject to self-loading effect caused by wedging of corrosion products in cracks. Effect causes cracks to continue to grow, even at very-low externally applied loads.

Neurofeedback Training Effects on Inhibitory Brain Activation in ADHD: A Matter of Learning?

Science.gov (United States)

Baumeister, Sarah; Wolf, Isabella; Holz, Nathalie; Boecker-Schlier, Regina; Adamo, Nicoletta; Holtmann, Martin; Ruf, Matthias; Banaschewski, Tobias; Hohmann, Sarah; Brandeis, Daniel

2018-05-15

Neurofeedback training (NF) is a promising non-pharmacological treatment for ADHD that has been associated with improvement of attention-deficit/hyperactivity disorder (ADHD)-related symptoms as well as changes in electrophysiological measures. However, the functional localization of neural changes following NF compared to an active control condition, and of successful learning during training (considered to be the critical mechanism for improvement), remains largely unstudied. Children with ADHD (N=16, mean age: 11.81, SD: 1.47) were randomly assigned to either slow cortical potential (SCP, n=8) based NF or biofeedback control training (electromyogram feedback, n=8) and performed a combined Flanker/NoGo task pre- and post-training. Effects of NF, compared to the active control, and of learning in transfer trials (approximating successful transfer to everyday life) were examined with respect to clinical outcome and functional magnetic resonance imaging (fMRI) changes during inhibitory control. After 20 sessions of training, children in the NF group presented reduced ADHD symptoms and increased activation in areas associated with inhibitory control compared to baseline. Subjects who were successful learners (n=9) also showed increased activation in an extensive inhibitory network irrespective of the type of training. Activation increased in an extensive inhibitory network following NF training, and following successful learning through NF and control biofeedback. Although this study was only powered to detect large effects and clearly requires replication in larger samples, the results suggest a crucial role for learning effects in biofeedback trainings. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

Corrosion '98: 53. annual conference and exposition, proceedings

International Nuclear Information System (INIS)

Anon.

1998-01-01

This conference was divided into the following sections: Corrosion in Gas Treating; Problems and Solutions in Commercial Building Water Systems; Green Corrosion/Scale Inhibitors; Atmospheric Corrosion; AIRPOL Update/98; Rubber Lining--Answers to Many Problems; Interference Problems; Environmental Assisted Cracking: Fundamental Research and Industrial Applications; Corrosion in Nuclear Systems; New Developments in Scale and Deposit Control; Corrosion and Corrosion Protection in the Transportation Industries; What's All the Noise About--Electrochemical That Is; Refining Industry Corrosion; Corrosion Problems in Military Hardware: Case Histories, Fixes and Lessons Learned; Cathodic Protection Test Methods and Instrumentation for Underground and On-grade Pipelines and Tanks; Recent Developments in Volatile Corrosion Inhibitors; Corrosion in Supercritical Fluids; Microbiologically Influenced Corrosion; Advances in Understanding and Controlling CO 2 Corrosion; Managing Corrosion with Plastics; Material Developments for Use in Exploration and Production Environments; Corrosion in Cold Regions; The Effect of Downsizing and Outsourcing on Cooling System Monitoring and Control Practices; New Developments in Mechanical and Chemical Industrial Cleaning; Mineral Scale Deposit Control in Oilfield Related Operations; Biocides in Cooling Water; Corrosion and Corrosion Control of Reinforced Concrete Structures; Materials Performance for Fossil Energy Conversion Systems; Marine corrosion; Thermal Spray--Coating and Corrosion Control; Flow Effects on Corrosion in Oil and Gas Production; Corrosion Measurement Technologies; Internal Pipeline Monitoring--Corrosion Monitoring, Intelligent Pigging and Leak Detection; Cathodic Protection in Natural Waters; Corrosion in Radioactive Liquid Waste Systems; On-line Hydrogen Permeation Monitoring Equipment and Techniques, State of the Art; Water Reuse and Recovery; Performance of Materials in High Temperature Environments; Advances in Motor

Microencapsulation Technology for Corrosion Mitigation by Smart Coatings

Science.gov (United States)

Buhrow, Jerry; Li, Wenyan; Jolley, Scott; Calle, Luz M.

2011-01-01

A multifunctional, smart coating for the autonomous control of corrosion is being developed based on micro-encapsulation technology. Corrosion indicators as well as corrosion inhibitors have been incorporated into microcapsules, blended into several paint systems, and tested for corrosion detection and protection effectiveness. This paper summarizes the development, optimization, and testing of microcapsules specifically designed to be incorporated into a smart coating that will deliver corrosion inhibitors to mitigate corrosion autonomously. Key words: smart coating, corrosion inhibition, microencapsulation, microcapsule, pH sensitive microcapsule, corrosion inhibitor, corrosion protection pain

An apple oligogalactan potentiates the growth inhibitory effect of celecoxib on colorectal cancer.

Science.gov (United States)

Li, Yuhua; Niu, Yinbo; Sun, Yang; Mei, Lin; Zhang, Bangle; Li, Qian; Liu, Li; Zhang, Rong; Chen, Jianfa; Mei, Qibing

2014-01-01

Multiple studies have indicated that selective cyclooxygenase-2 (COX-2) inhibitors possess clinically chemopreventive and preclinically anticancer activities. Their long-term use, however, may be limited by the cardiovascular toxicity. This study tried to investigate whether an apple oligogalactan (AOG) could enhance the growth inhibitory effect of celecoxib on colorectal cancer. Caco-2 and HT-29 cell lines were exposed to different concentrations of AOG (0-1 g/L), celecoxib (0-25 μmol/L), and their combination. COX-2 levels were assessed by reverse transcription PCR and Western blot. COX-2 activity was evaluated by measuring prostaglandin E2 concentration. A colitis-associated colorectal cancer (CACC) mouse model was used to determine the effect of the combination in vivo. AOG (0.1-0.5 g/L) could potentiate the inhibitory effect of physiologic doses of celecoxib (5 μmol/L) on cell growth and decrease COX-2 expressions both at RNA and protein levels. In vivo, the combination (2.5% AOG plus 0.04% celecoxib, w/w) prevented against CACC in mice effectively. Our data indicate that AOG could potentiate the growth inhibitory effect of celecoxib on colorectal cancer both in vitro and in vivo through influencing the expression and function of COX-2 and phosphorylation of MAPKs, which suggests a new possible combinatorial strategy in colorectal cancer therapy.

To the corrosion of austenitic steels in sodium loops

International Nuclear Information System (INIS)

Schad, M.

1978-03-01

This report describes the comparison between experimental corrosion and calculated corrosion effects on austenitic steels exposed to liquid sodium. As basis for the calculations served a diffusion model. The comparison showed that the model is able to predict the corrosion effects. In addition the model was used to calculate the corrosion effect along an actual fuel rod. (orig.) [de

Effects of Cr, Mo, and W on Na2SO4 induced high temperature corrosion of Ni

International Nuclear Information System (INIS)

Reising, R.F.

1975-01-01

Operating gas turbine engines are susceptible to a phenomenon called hot corrosion. Hot corrosion is generally attributed to the interaction of nickel-base turbine blade alloys with ingested sodium sulfate. Two mechanism were presented previously to account for the surface and grain boundary corrosion of nickel metal. The effects of chromium, molybdenum, or tungsten, or their corrosion products on the corrosion of nickel metal were studied. The corrosion products considered are the oxides and sodium-oxygen compounds. The corrosion products of molybdenum and tungsten enhance the sodium sulfate-induced corrosion of nickel to the same degree as the metals themselves while those of chromium do not. The enhanced corrosion caused by sodium molybdate or tungstate suggests that more than a simple acid-base phenomenon is involved. The formation of a triable, porous film caused by the presence of nickel molybdate or tungstate is proposed as the mechanism responsible for this enhancement. This mechanism is consistent with that proposed by Lashka and Glezer who associated the intensified oxidation of molybdenum-containing nickel alloys with a sub-layer oxide scale containing nickel molybdate. (U.S.)

[The effect of bacteria reaction time on corrosion properties of Ni-Cr alloys pretreated with different proteins].

Science.gov (United States)

Qi, Han-quan; Zhang, Song-mei; Qian, Chao; Yuan-Li, Zheng

2015-12-01

To evaluate the corrosion properties of absorbed protein on the surface of NiCr alloys, and provide experimental base for corrosion resistance of dental casting alloys. NiCr alloy specimens were divided into 3 groups: one group was exposed to the artificial saliva(control group), and the other 2 groups were exposed to the artificial saliva with 1% bovine serum albumin(BSA), or 0.22% lysozyme(LSZ). Group of BSA and group of LSZ were the experimental group. Specimens in 3 groups were cultured in solution of Streptococcus mutans for 12 h, 24 h, 36 h and 48h, and investigated with electrochemical impedance spectroscopy measurement(EIS) and potentiodynamic polarization measurement(POT) to determine the corrosion resistance of the alloys. The data was analyzed with SPSS 17.0 software package. The results indicated that the corrosion resistance of both BSA group and LSZ group were higher than that of the control group (Pcorrosion resistance of BSA group and LSZ group had no significant difference (P>0.05), but was still higher than that of the control group. After 36 h culture time, the control group and the BSA group had no statistical difference in corrosion resistance （P>0.05), while the LSZ group had the poorest corrosion resistance. When the culture time extended to 48 h, the control group had a better corrosion resistance compared with the BAS group and the LSZ group(Pcorrosion properties than LSZ group. The potentiodynamic polarization curve and electrochemical impedance spectroscopy had similar results. The adhesion of BSA and LSZ on the surface of the NiCr alloys in the early time could effectively inhibit the corrosive effect of Streptococcus mutans. The LSZ had better effect than BSA. With the continuing role of bacteria and the consumption of the absorb protein, the corrosion resistance of NiCr alloys toward Streptococcus mutans becomes lower than the alloys without absorb protein, which demonstrated that the adhesion of protein would change the surface

Evaluation of Encapsulated Inhibitor for Autonomous Corrosion Protection

Science.gov (United States)

Johnsey, M. N.; Li, W.; Buhrow, J. W.; Calle, L. M.; Pearman, B. P.; Zhang, X.

2015-01-01

This work concerns the development of smart coating technologies based on microencapsulation for the autonomous control of corrosion. Microencapsulation allows the incorporation of corrosion inhibitors into coating which provides protection through corrosion-controlled release of these inhibitors.One critical aspect of a corrosion protective smart coating is the selection of corrosion inhibitor for encapsulation and comparison of the inhibitor function before and after encapsulation. For this purpose, a systematic approach is being used to evaluate free and encapsulated corrosion inhibitors by salt immersion. Visual, optical microscope, and Scanning Electron Microscope (with low-angle backscatter electron detector) are used to evaluate these inhibitors. It has been found that the combination of different characterization tools provide an effective method for evaluation of early stage localized corrosion and the effectiveness of corrosion inhibitors.

Effect of manufacturing process sequence on the corrosion resistance characteristics of coated metallic bipolar plates

Science.gov (United States)

Dur, Ender; Cora, Ömer Necati; Koç, Muammer

2014-01-01

Metallic bipolar plate (BPP) with high corrosion and low contact resistance, durability, strength, low cost, volume, and weight requirements is one of the critical parts of the PEMFC. This study is dedicated to understand the effect of the process sequence (manufacturing then coating vs. coating then manufacturing) on the corrosion resistance of coated metallic bipolar plates. To this goal, three different PVD coatings (titanium nitride (TiN), chromium nitride (CrN), zirconium nitride (ZrN)), with three thicknesses, (0.1, 0.5, 1 μm) were applied on BPPs made of 316L stainless steel alloy before and after two types of manufacturing (i.e., stamping or hydroforming). Corrosion test results indicated that ZrN coating exhibited the best corrosion protection while the performance of TiN coating was the lowest among the tested coatings and thicknesses. For most of the cases tested, in which coating was applied before manufacturing, occurrence of corrosion was found to be more profound than the case where coating was applied after manufacturing. Increasing the coating thickness was found to improve the corrosion resistance. It was also revealed that hydroformed BPPs performed slightly better than stamped BPPs in terms of the corrosion behavior.

Multilayer graphene as an effective corrosion protection coating for copper

Science.gov (United States)

Ravishankar, Vasumathy; Ramaprabhu, S.; Jaiswal, Manu

2018-04-01

Graphene grown by chemical vapor deposition (CVD) has been studied as a protective layer against corrosion of copper. The layer number dependence on the protective nature of graphene has been investigated using techniques such as Tafel analysis and Electroimpedance Spectroscopy. Multiple layers of graphene were achieved by wet transfer above CVD grown graphene. Though this might cause grain boundaries, the sites where corrosion is initiated, to be staggered, wet transfer inherently carries the disadvantage of tearing of graphene, as confirmed by Raman spectroscopy measurements. However, Electroimpedance Spectroscopy (EIS) reflects that graphene protected copper has a layer dependent resistance to corrosion. Decrease in corrosion current (Icorr) for graphene protected copper is presented. There is only small dependence of corrosion current on the layer number, Tafel plots clearly indicate passivation in the presence of graphene, whether it be single layer or multiple layers. Notwithstanding the crystallite size, defect free layers of graphene with staggered grain boundaries combined with passivation could offer good corrosion protection for metals.

effect of municipal liquid waste on corrosion susceptibility

African Journals Online (AJOL)

DR. AMINU

Kogo, A. A.. Department of Integrated Science, Federal College of Education, Kano, Nigeria. ... The corrosion rate of the galvanized steel pipe was measured using the gravimetric ... Key words: Liquid waste, galvanized steel, weight loss, gravimetric, corrosion, leaking ... the side of the test tubes, so that each side would be.

Corrosion on Mars: An Investigation of Corrosion Mechanisms Under Relevant Simulated Martian Environments

Science.gov (United States)

Calle, Luz M.; Li, Wenyan; Johansen, Michael R.; Buhrow, Jerry W.; Calle, Carlos I.

2017-01-01

, showed that there is an interaction between the small amount of oxygen present in the Mars gas and the alloy when there is a scratch that removes the protective aluminum oxide film. Further studies are needed to consider many other important components of the Mars environment that can affect this interaction such as: the effect of oxidants, the effect of radiation on their oxidizing properties and the possible catalytic effects of the clays present in the Martian regolith. The results of this one-year project provide strong justification for further investigation of the corrosion mechanism of materials relevant to long-term surface operations in support of future human exploration missions on Mars.

DPC materials and corrosion environments.

Energy Technology Data Exchange (ETDEWEB)

Ilgen, Anastasia Gennadyevna; Bryan, Charles R.; Teich-McGoldrick, Stephanie; Hardin, Ernest

2014-10-01

After an exposition of the materials used in DPCs and the factors controlling material corrosion in disposal environments, a survey is given of the corrosion rates, mechanisms, and products for commonly used stainless steels. Research needs are then identified for predicting stability of DPC materials in disposal environments. Stainless steel corrosion rates may be low enough to sustain DPC basket structural integrity for performance periods of as long as 10,000 years, especially in reducing conditions. Uncertainties include basket component design, disposal environment conditions, and the in-package chemical environment including any localized effects from radiolysis. Prospective disposal overpack materials exist for most disposal environments, including both corrosion allowance and corrosion resistant materials. Whereas the behavior of corrosion allowance materials is understood for a wide range of corrosion environments, demonstrating corrosion resistance could be more technically challenging and require environment-specific testing. A preliminary screening of the existing inventory of DPCs and other types of canisters is described, according to the type of closure, whether they can be readily transported, and what types of materials are used in basket construction.

Investigation of Non-Uniform Rust Distribution and Its Effects on Corrosion Induced Cracking in Reinforced Concrete

Directory of Open Access Journals (Sweden)

Sutrisno Wahyuniarsih

2017-01-01

Full Text Available Uniform corrosion still widely used by a lot of researchers and engineers to analyze the corrosion induced cracking. However, in practice, corrosion process occurred non-uniformly. The part nearest to the exposed surface is more likely to have faster corrosion initiation compared with other regions. This research is mainly focused on investigating the effect of non-uniform rust distribution to cover cracking in reinforced concrete. An experimental test performed using accelerated corrosion test by using 5% NaCl solution and applied a constant electric current to the concrete samples. The rust distribution and measurement were observed by using a digital microscope. Based on the experimental result, it was found that the rust was distributed in a non-uniform pattern. As a result, the cracks also formed non-uniformly along the perimeter of steel bar. At the last part of this paper, a simulation result of concrete cracking induced by non-uniform corrosion is presented. The result compared with a simulation using uniform corrosion assumption to investigate the damage pattern of each model. The simulation result reveals stress evolution due to rust expansion which leads to concrete cracking. Furthermore, a comparison of stresses induced by non-uniform corrosion and uniform corrosion indicates that non-uniform corrosion could lead to earlier damage to the structure which is specified by the formation and propagation of the crack.

The Inhibitory Effect of Prunella vulgaris L. on Aldose Reductase and Protein Glycation

Directory of Open Access Journals (Sweden)

Hong Mei Li

2012-01-01

Full Text Available To evaluate the aldose reductase (AR enzyme inhibitory ability of Prunella vulgaris L. extract, six compounds were isolated and tested for their effects. The components were subjected to in vitro bioassays to investigate their inhibitory assays using rat lens aldose reductase (rAR and human recombinant AR (rhAR. Among them, caffeic acid ethylene ester showed the potent inhibition, with the IC50 values of rAR and rhAR at 3.2±0.55 μM and 12.58±0.32 μM, respectively. In the kinetic analyses using Lineweaver-Burk plots of 1/velocity and 1/concentration of substrate, this compound showed noncompetitive inhibition against rhAR. Furthermore, it inhibited galactitol formation in a rat lens incubated with a high concentration of galactose. Also it has antioxidative as well as advanced glycation end products (AGEs inhibitory effects. As a result, this compound could be offered as a leading compound for further study as a new natural products drug for diabetic complications.

Effect of mixed alloy combinations on fretting corrosion performance of spinal screw and rod implants.

Science.gov (United States)

Mali, Sachin A; Singh, Vaneet; Gilbert, Jeremy L

2017-07-01

Spinal implants are made from a variety of materials to meet the unique mechanical demands of each application. However, the medical device community has raised concern about mixing dissimilar metals in an implant because of fear of inducing corrosion. There is a lack of systematic studies on the effects of mixing metals on performance of spinal implants, especially in fretting corrosion conditions. Hence, the goal was to determine whether mixing stainless steel (SS316L), titanium alloy (Ti6Al4V) and cobalt chromium (CoCrMo) alloy components in a spinal implant leads to any increased risk of corrosion degradation. Spinal constructs consisting of single assembly screw-connector-rod components were tested using a novel short-term cyclic fretting corrosion test method. A total of 17 alloy component combinations (comprised of SS316L, Ti6Al4V-anodized and CoCrMo alloy for rod, screws and connectors) were tested under three anatomic orientations. Spinal constructs having all SS316L were most susceptible to fretting-initiated crevice corrosion attack and showed higher average fretting currents (∼25 - 30 µA), whereas constructs containing all Ti6Al4V components were less susceptible to fretting corrosion with average fretting currents in the range of 1 - 6 µA. Mixed groups showed evidence of fretting corrosion but they were not as severe as all SS316L group. SEM results showed evidence of severe corrosion attack in constructs having SS316L components. There also did not appear to be any galvanic effects of combining alloys together. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1169-1177, 2017. © 2016 Wiley Periodicals, Inc.

Atmospheric corrosion of uranium-carbon alloys

International Nuclear Information System (INIS)

Rousset, P.; Accary, A.

1965-01-01

The authors study the corrosion of uranium-carbon alloys having compositions close to that of the mono-carbide; they show that the extent of the observed corrosion effects increases with the water vapour content of the surrounding gas and they conclude that the atmospheric corrosion of these alloys is due essentially to the humidity of the air, the effect of the oxygen being very slight at room temperature. They show that the optimum conditions for preserving U-C alloys are either a vacuum or a perfectly dry argon atmosphere. The authors have also established that the type of corrosion involved is a corrosion which 'cracks under stress' and is transgranular (it can also be intergranular in the case of sub-stoichiometric alloys). They propose, finally, two hypotheses for explaining this mechanism, one of which is illustrated by the existence, at the fissure interface, of corrosion products which can play the role of 'corners' in the mono-carbide grains. (authors) [fr

Critical Study of Corrosion Damaged Concrete Structures

OpenAIRE

Sallehuddin Shah Ayop; John Cairns

2013-01-01

Corrosion of steel reinforcement in concrete is one of the major problems with respect to the durability of reinforced concrete structures. The degradation of the structure strength due to reinforcement corrosion decreases its design life. This paper presents the literature study on the influence of the corrosion on concrete structure starting from the mechanism of the corrosion until the deterioration stage and the structural effects of corrosion on concrete structures.

Effect of elevated lithium on the waterside corrosion of zircaloy-4: Experimental and predictive studies

International Nuclear Information System (INIS)

Pecheur, D.; Giordano, A.; Picard, E.; Billot, P.; Thomazet, J.

1997-01-01

Lithium and boron content in the coolant are known to influence the oxidation behaviour of the fuel cladding. Since new PWR operating conditions could consist in an increase of the lithium and the boron concentration in the coolant early in the cycle, a specific study has been conducted to analyze and to predict the effect of such new water chemistry conditions on the oxidation kinetics of the Zircaloy-4 material. Experimental studies have been performed in out-of-pile loop tests, under one and two phase flow heat transfer in various water chemistry conditions (0≤Li≤350 ppm, 0≤B≤1000 ppm, 0≤K≤56 ppm). A simulation of the effect of elevated lithium on the corrosion has been made using the semi-empirical COCHISE corrosion code. Under one phase flow heat transfer conditions, the addition of lithium hydroxide in the coolant increases the oxidation rate, essentially in the post-transition regime for low lithium levels (≤ 75 ppm) and immediately in the pre-transition phase for very high lithium level (350 ppm). Under two phase flow heat transfer, an enhancement of the corrosion is observed in the area of the rod submitted to boiling. Based on the out-of-pile loop test performed in presence of KOH instead of LiOH, such an enhancement of the corrosion appears to be due to a lithium enrichment in the oxide layer induced by boiling and not to a pH effect. The simulation of the increase of lithium content in the coolant from 2.2 to 3.5 ppm leads to an enhancement in corrosion rates which becomes only significant at high burn up. This predictive result of elevated lithium effect on corrosion is then compared with oxidation data derived from reactors operating under an elevated lithium regime. (author). 14 refs, 9 figs, 3 tabs

Effect of elevated lithium on the waterside corrosion of zircaloy-4: Experimental and predictive studies

Energy Technology Data Exchange (ETDEWEB)

Pecheur, D; Giordano, A; Picard, E; Billot, P [CEA Centre d` Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France); Thomazet, J [FRAMATOME, Nuclear Fuel Div., Lyon (France)

1997-02-01

Lithium and boron content in the coolant are known to influence the oxidation behaviour of the fuel cladding. Since new PWR operating conditions could consist in an increase of the lithium and the boron concentration in the coolant early in the cycle, a specific study has been conducted to analyze and to predict the effect of such new water chemistry conditions on the oxidation kinetics of the Zircaloy-4 material. Experimental studies have been performed in out-of-pile loop tests, under one and two phase flow heat transfer in various water chemistry conditions (0{<=}Li{<=}350 ppm, 0{<=}B{<=}1000 ppm, 0{<=}K{<=}56 ppm). A simulation of the effect of elevated lithium on the corrosion has been made using the semi-empirical COCHISE corrosion code. Under one phase flow heat transfer conditions, the addition of lithium hydroxide in the coolant increases the oxidation rate, essentially in the post-transition regime for low lithium levels ({<=} 75 ppm) and immediately in the pre-transition phase for very high lithium level (350 ppm). Under two phase flow heat transfer, an enhancement of the corrosion is observed in the area of the rod submitted to boiling. Based on the out-of-pile loop test performed in presence of KOH instead of LiOH, such an enhancement of the corrosion appears to be due to a lithium enrichment in the oxide layer induced by boiling and not to a pH effect. The simulation of the increase of lithium content in the coolant from 2.2 to 3.5 ppm leads to an enhancement in corrosion rates which becomes only significant at high burn up. This predictive result of elevated lithium effect on corrosion is then compared with oxidation data derived from reactors operating under an elevated lithium regime. (author). 14 refs, 9 figs, 3 tabs.

Effects of grain size on the corrosion resistance of pure magnesium by cooling rate-controlled solidification

Science.gov (United States)

Liu, Yichi; Liu, Debao; You, Chen; Chen, Minfang

2015-09-01

The aim of this study was to investigate the effect of grain size on the corrosion resistance of pure magnesium developed for biomedical applications. High-purity magnesium samples with different grain size were prepared by the cooling rate-controlled solidification. Electrochemical and immersion tests were employed to measure the corrosion resistance of pure magnesium with different grain size. The electrochemical polarization curves indicated that the corrosion susceptibility increased as the grain size decrease. However, the electrochemical impedance spectroscopy (EIS) and immersion tests indicated that the corrosion resistance of pure magnesium is improved as the grain size decreases. The improvement in the corrosion resistance is attributed to refine grain can produce more uniform and density film on the surface of sample.

Evaluating the effects of hydroxyapatite coating on the corrosion behavior of severely deformed 316Ti SS for surgical implants

International Nuclear Information System (INIS)

Mhaede, Mansour; Ahmed, Aymen; Wollmann, Manfred; Wagner, Lothar

2015-01-01

The present work investigates the effects of severe plastic deformation by cold rolling on the microstructure, the mechanical properties and the corrosion behavior of austenitic stainless steel (SS) 316Ti. Hydroxyapatite coating (HA) was applied on the deformed material to improve their corrosion resistance. The martensitic transformation due to cold rolling was recorded by X-ray diffraction spectra. The effects of cold rolling on the corrosion behavior were studied using potentiodynamic polarization. The electrochemical tests were carried out in Ringer's solution at 37 ± 1 °C. Cold rolling markedly enhanced the mechanical properties while the electrochemical tests referred to a lower corrosion resistance of the deformed material. The best combination of both high strength and good corrosion resistance was achieved after applying hydroxyapatite coating. - Highlights: • Cold rolling markedly increases the hardness of SS 316Ti from 125 to 460 HV10. • Higher deformation degrees lead to lower corrosion resistance. • Application of HA-coating leads to significant improvement of the corrosion resistance

Corrosion probe. Innovative technology summary report

International Nuclear Information System (INIS)

1999-05-01

Over 253 million liters of high-level waste (HLW) generated from plutonium production is stored in mild steel tanks at the Department of Energy (DOE) Hanford Site. Corrosion monitoring of double-shell storage tanks (DSTs) is currently performed at Hanford using a combination of process knowledge and tank waste sampling and analysis. Available technologies for corrosion monitoring have progressed to a point where it is feasible to monitor and control corrosion by on-line monitoring of the corrosion process and direct addition of corrosion inhibitors. The electrochemical noise (EN) technique deploys EN-based corrosion monitoring probes into storage tanks. This system is specifically designed to measure corrosion rates and detect changes in waste chemistry that trigger the onset of pitting and cracking. These on-line probes can determine whether additional corrosion inhibitor is required and, if so, provide information on an effective end point to the corrosion inhibitor addition procedure. This report describes the technology, its performance, its application, costs, regulatory and policy issues, and lessons learned

The effect of surface treatment and gaseous rust protection paper on the atmospheric corrosion stability of aluminium alloy

International Nuclear Information System (INIS)

Gao Guizhong

1992-03-01

The experimental results of atmospheric corrosion of 166 aluminium alloy of Al-Mg-Si-Cu system and 167 aluminium alloy of Al-Mg-Si-Cu-Fe-Ni system for different surface treatment and different wrapping papers used are introduced. The results show: 1. The composition of aluminium alloy has some effect on the performance of atmospheric corrosion stability and the local corrosion depth for 167 aluminium alloy specimen is considerable. 2. After 8 years storage, the 167 aluminium alloy tubular specimen, which was treated with surface treatment in deionized water at 100 ∼ 230 C degree, has no spot of atmospheric corrosion found. 3. Within the test period, the performance of atmospheric corrosion stability by sulphuric-acid anodization film is remarkable. 4. The No. 19 gaseous rust protection paper has no effect of atmospheric corrosion stability on the 166 and 167 aluminium alloys which were treated with quenching and natural ageing method

Corrosion effect of fast reactor fuel claddings on their mechanical properties

International Nuclear Information System (INIS)

Davydov, E.F.; Krykov, F.N.; Shamardin, V.K.

1985-01-01

Fast reactor fuel cladding corrosion effect on its mechanical properties was investigated. UO 2 fuel elements were irradiated in the BOP-60 reactor at the linear heat rate of 42 kw/m. Fuel cladding is made of stainless steel OKh16N15M3BR. Calculated maximum cladding temperature is 920 K. Neutron fluence in the central part of fuel elements is 6.3x10 26 m+H- 2 . To investigate the strength changes temperature dependence of corrossion depth, cladding strength reduction factors was determined. Samples plasticity reduction with corrosion layer increase is considered to be a characteristic feature

Corrosion behavior of corrosion resistant alloys in stimulation acids

Energy Technology Data Exchange (ETDEWEB)

Cheldi, Tiziana [ENI E and P Division, 20097 San Donato Milanese Milano (Italy); Piccolo, Eugenio Lo; Scoppio, Lucrezia [Centro Sviluppo Materiali, via Castel Romano 100, 00128 Rome (Italy)

2004-07-01

In the oil and gas industry, selection of CRAs for downhole tubulars is generally based on resistance to corrosive species in the production environment containing CO{sub 2}, H{sub 2}S, chloride and in some case elemental sulphur. However, there are non-production environments to which these materials must also be resistant for either short term or prolonged duration; these environments include stimulation acids, brine and completion fluids. This paper reports the main results of a laboratory study performed to evaluate the corrosion and stress corrosion behaviour to the acidizing treatments of the most used CRAs for production tubing and casing. Laboratory tests were performed to simulate both 'active' and 'spent' acids operative phases, selecting various environmental conditions. The selected steel pipes were a low alloyed steel, martensitic, super-martensitic, duplex 22 Cr, superduplex 25 Cr and super-austenitic stainless steels (25 Cr 35 Ni). Results obtained in the 'active' acid environments over the temperature range of 100-140 deg. C, showed that the blend acids with HCl at high concentration and HCl + HF represented too much severe conditions, where preventing high general corrosion and heavy localised corrosion by inhibition package becomes very difficult, especially for duplex steel pipe, where, in some case, the specimens were completely dissolved into the solution. On the contrary, all steels pipes were successfully protected by inhibitor when organic acid solution (HCOOH + CH{sub 3}COOH) were used. Furthermore, different effectiveness on corrosion protection was showed by the tested inhibitors packages: e.g. in the 90% HCl at 12% + 10 CH{sub 3}COOH acid blend. In 'spent' acid environments, all steel pipes showed to be less susceptible to the localised and general corrosion attack. Moreover, no Sulphide Stress Corrosion Cracking (SSC) was observed. Only one super-austenitic stainless steel U-bend specimen showed

Effects of Different Working Modes of Ultrasound on Structural Characteristics of Zein and ACE Inhibitory Activity of Hydrolysates

Directory of Open Access Journals (Sweden)

Xiaofeng Ren

2017-01-01

Full Text Available Ultrasound was used as a new technology to pretreat protein prior to proteolysis to improve enzymolysis efficiency. The effects of different working modes of ultrasound on the angiotensin I-converting enzyme (ACE inhibitory activity of zein hydrolysates and the structural characteristics of zein were investigated. The solubility, surface hydrophobicity (H0, ultraviolet-visible (UV-Vis spectra, intrinsic fluorescence spectra, and circular dichroism (CD spectra of zein pretreated with ultrasound were determined. All ultrasound pretreatments significantly improved the ACE inhibitory activity of zein hydrolysates (p<0.05. The highest ACE inhibitory activity, representing an increase of 99.21% over the control, was obtained with dual sweeping frequency ultrasound of 33±2 and 68±2 kHz. The effects of single sweeping frequency and dual fixed frequency ultrasound were stronger than those of single fixed frequency ultrasound for improving the ACE inhibitory activity of zein. Structural changes in zein were induced by ultrasound, as confirmed by changes in the solubility, H0, UV-Vis spectra, intrinsic fluorescence spectra, and CD spectra of zein, and these were consistent with the corresponding ACE inhibitory activities of zein hydrolysates. Thus, ultrasound working mode and frequency have significant effects on the structure of zein and the ACE inhibitory activity of zein hydrolysates.

Effect of mechanical pre-loadings on corrosion resistance of chromium-electroplated steel rods in marine environment

Science.gov (United States)

Shubina Helbert, Varvara; Dhondt, Matthieu; Homette, Remi; Arbab Chirani, Shabnam; Calloch, Sylvain

2018-03-01

Providing high hardness, low friction coefficient, as well as, relatively good corrosion resistance, chromium-plated coatings (∼20 μm) are widely used for steel cylinder rods in marine environment. However, the standardized corrosion test method (ISO 9227, NSS) used to evaluate efficiency of this type of coatings does not take into account in-service mechanical loadings on cylinder rods. Nevertheless, the uniform initial network of microcracks in chromium coating is changing under mechanical loadings. Propagation of these microcracks explains premature corrosion of the steel substrate. The aim of the study was to evaluate relationship between mechanical loadings, propagation of microcracks network and corrosion resistance of chromium coatings. After monotonic pre-loading tests, it was demonstrated by microscopic observations that the microcracks propagation started at stress levels higher than the substrate yield stress (520 MPa). The microcracks become effective, i.e. they have instantly undergone through the whole coating thickness to reach the steel substrate. The density of effective microcracks increases with the total macroscopic level, i.e. the intercrack distance goes from 60 ± 5 μm at 1% of total strain to approximately 27 ± 2 μm at 10%. Electrochemical measurements have shown that the higher the plastic strain level applied during mechanical loading, the more the corrosion potential of the sample decreased until reaching the steel substrate value of approximately ‑0.65 V/SCE after 2 h of immersion. The polarization curves have also highligthed an increase in the corrosion current density with the strain level. Therefore, electrochemical measurements could be used to realize quick and comprehensive assesment of the effect of monotonic pre-loadings on corrosion properties of the chromium coating.

Comparison of the inhibitory effects of tolcapone and entacapone against human UDP-glucuronosyltransferases

Energy Technology Data Exchange (ETDEWEB)

Lv, Xia [Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); State Key Laboratory of Organ Failure Research, Guangdong Provincial Institute of Nephrology, Southern Medical University, Guangzhou 510515 (China); Wang, Xin-Xin [RSKT Biopharma Inc., Dalian 116023 (China); Hou, Jie [Dalian Medical University, Dalian 116044 (China); Fang, Zhong-Ze [RSKT Biopharma Inc., Dalian 116023 (China); Wu, Jing-Jing [Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); State Key Laboratory of Organ Failure Research, Guangdong Provincial Institute of Nephrology, Southern Medical University, Guangzhou 510515 (China); Cao, Yun-Feng [RSKT Biopharma Inc., Dalian 116023 (China); Liu, Shu-Wen [State Key Laboratory of Organ Failure Research, Guangdong Provincial Institute of Nephrology, Southern Medical University, Guangzhou 510515 (China); Ge, Guang-Bo, E-mail: geguangbo@dicp.ac.cn [Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); State Key Laboratory of Organ Failure Research, Guangdong Provincial Institute of Nephrology, Southern Medical University, Guangzhou 510515 (China); Yang, Ling, E-mail: ylingdicp@gmail.com [Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Jiangxi University of Traditional Chinese Medicine, Nanchang 330006 (China)

2016-06-15

Tolcapone and entacapone are two potent catechol-O-methyltransferase (COMT) inhibitors with a similar skeleton and displaying similar pharmacological activities. However, entacapone is a very safe drug used widely in the treatment of Parkinson's disease, while tolcapone is only in limited use for Parkinson's patients and needs careful monitoring of hepatic functions due to hepatotoxicity. This study aims to investigate and compare the inhibitory effects of entacapone and tolcapone on human UDP-glucosyltransferases (UGTs), as well as to evaluate the potential risks from the view of drug-drug interactions (DDI). The results demonstrated that both tolcapone and entacapone exhibited inhibitory effects on UGT1A1, UGT1A7, UGT1A9 and UGT1A10. In contrast to entacapone, tolcapone exhibited more potent inhibitory effects on UGT1A1, UGT1A7, and UGT1A10, while their inhibitory potentials against UGT1A9 were comparable. It is noteworthy that the inhibition constants (K{sub i}) of tolcapone and entacapone against bilirubin-O-glucuronidation in human liver microsomes (HLM) are determined as 0.68 μM and 30.82 μM, respectively, which means that the inhibition potency of tolcapone on UGT1A1 mediated bilirubin-O-glucuronidation in HLM is much higher than that of entacapone. Furthermore, the potential risks of tolcapone or entacapone via inhibition of human UGT1A1 were quantitatively predicted by the ratio of the areas under the plasma drug concentration-time curve (AUC). The results indicate that tolcapone may result in significant increase in AUC of bilirubin or the drugs primarily metabolized by UGT1A1, while entacapone is unlikely to cause a significant DDI through inhibition of UGT1A1. - Highlights: • Tolcapone and entacapone exhibited preferential inhibition against UGT1A enzymes. • In contrast to entacapone, tolcapone exhibited more potent inhibitory effects on human UGT1A1, 1 A7 and 1 A10. • Tolcapone may lead to significant increase in AUC of bilirubin. �

GMP reverses the facilitatory effect of glutamate on inhibitory avoidance task in rats.

Science.gov (United States)

Rubin, M A; Jurach, A; da Costa Júnior, E M; Lima, T T; Jiménez-Bernal, R E; Begnini, J; Souza, D O; de Mello, C F

1996-09-02

Previous studies have demonstrated that post-training intrahippocampal glutamate administration improves inhibitory avoidance task performance in rats. Antagonism of the agonist actions of glutamate by guanine nucleotides has been shown at the molecular and behavioural level. In the present investigation we demonstrate that intrahippocampal co-administration of GMP (guanosine 5'-monophosphate) reverses the facilitatory effect of glutamate on the inhibitory avoidance learning paradigm and inhibits [3H]glutamate binding in hippocampal synaptic plasma membranes. These results suggest that guanine nucleotides may modulate glutamate actions.

Annealing Effect on Corrosion Behavior of the Beta-Quenched HANA Alloy

International Nuclear Information System (INIS)

Kim, Hyun Gil; Kim, Il Hyun; Choi, Byung Kwan; Park, Sang Yoon; Park, Jeong Yong; Jeong, Yong Hwan

2009-01-01

The advanced fuel cladding materials named as HANA cladding have been developed at KAERI for application of high burn-up and that cladding showed an improved performance in both in-pile and out-of-pile conditions. However, the cladding performance could be changed by the annealing conditions during the tube manufacturing process. Especially, the corrosion resistance is considerably sensitive to their microstructure which is determined by a manufacturing process in the high Nb-containing zirconium alloys. They reported that the corrosion properties of the Nb-containing Zr alloys were considerably affected by the microstructure conditions such as the Nb concentration in the matrix and the second phase types. Therefore, the corrosion behavior of HANA cladding having the high Nb could be considerably affected by the annealing time and temperatures. The purpose of this study is focused on the annealing effect of the beta quenched HANA alloy to obtain the optimum annealing conditions

Effects of pH and chloride concentration on pitting corrosion of AA6061 aluminum alloy

International Nuclear Information System (INIS)

Zaid, B.; Saidi, D.; Benzaid, A.; Hadji, S.

2008-01-01

Effects of pH solution and chloride (Cl - ) ion concentration on the corrosion behaviour of alloy AA6061 immersed in aqueous solutions of NaCl have been investigated using measurements of weight loss, potentiodynamic polarisation, linear polarisation, cyclic polarisation experiment combined with open circuit potential transient technique and optical or scanning electron microscopy. The corrosion behaviour of the AA6061 aluminum alloy was found to be dependant on the pH and chloride concentration [NaCl] of solution. In acidic or slightly neutral solutions, general and pitting corrosion occurred simultaneously. In contrast, exposure to alkaline solutions results in general corrosion. Experience revealed that the alloy AA6061 was susceptible to pitting corrosion in all chloride solution of concentration ranging between 0.003 wt% and 5.5 wt% NaCl and an increase in the chloride concentration slightly shifted both the pitting E pit and corrosion E cor potentials to more active values. In function of the conditions of treatment, the sheets of the alloy AA6061 undergo two types of localised corrosion process, leading to the formation of hemispherical and crystallographic pits. Polarisation resistance measurements in acidic (pH = 2) and alkaline chloride solutions (pH = 12) which are in good agreement with those of weight loss, show that the corrosion kinetic is minimised in slightly neutral solutions (pH = 6)

Effects of cold working on the pitting corrosion behavior s of AISI 304 stainless steels

Energy Technology Data Exchange (ETDEWEB)

Jung, Kee Min; Kim, Jong Soo; Kim, Young Jun; Kwon, Houk Sang [KAIST, Daejon (Korea, Republic of)

2015-12-15

These microstructural changes by cold working can lead improvement of mechanical properties, however from a corrosion resistant point of view, the effects of cold working on the corrosion resistance of stainless steel have been argued. Several studies has been focused on the influence of cold working on the localized corrosion resistance of stainless steels. However, the opinions about the role of cold working on the localized corrosion resistance are highly in consistence. Some studies report that the pitting potential of austenitic stainless steels decreased with cold working level, on the other hands, other studies claimed that the pitting resistance was increased by cold working. Therefore it is necessary to verify how cold working affects pitting corrosion behavior of austenitic stainless steels. In the present work, the influence of cold working on the localized corrosion of AISI 304stainless steel in the neutral chloride solution was studied based on point defect model (PDM). The fraction of deformation-induced martensite was linearly increased with cold rolling level. Through cold rolling, the pitting potential was decreased, the metastable pitting event density was significantly increased and the repassivation potential was decreased. The overall localized corrosion resistance was decreased with cold working, however cold working level increased from 30 % to 50 %, localized corrosion resistance was recovered. The accumulated cation vacancy generates a void at metal/film interface, therefore film breakdown accelerates for cold worked alloys.

Effects of cold working on the pitting corrosion behavior s of AISI 304 stainless steels

International Nuclear Information System (INIS)

Jung, Kee Min; Kim, Jong Soo; Kim, Young Jun; Kwon, Houk Sang

2015-01-01

These microstructural changes by cold working can lead improvement of mechanical properties, however from a corrosion resistant point of view, the effects of cold working on the corrosion resistance of stainless steel have been argued. Several studies has been focused on the influence of cold working on the localized corrosion resistance of stainless steels. However, the opinions about the role of cold working on the localized corrosion resistance are highly in consistence. Some studies report that the pitting potential of austenitic stainless steels decreased with cold working level, on the other hands, other studies claimed that the pitting resistance was increased by cold working. Therefore it is necessary to verify how cold working affects pitting corrosion behavior of austenitic stainless steels. In the present work, the influence of cold working on the localized corrosion of AISI 304stainless steel in the neutral chloride solution was studied based on point defect model (PDM). The fraction of deformation-induced martensite was linearly increased with cold rolling level. Through cold rolling, the pitting potential was decreased, the metastable pitting event density was significantly increased and the repassivation potential was decreased. The overall localized corrosion resistance was decreased with cold working, however cold working level increased from 30 % to 50 %, localized corrosion resistance was recovered. The accumulated cation vacancy generates a void at metal/film interface, therefore film breakdown accelerates for cold worked alloys

Corrosion

Science.gov (United States)

Slabaugh, W. H.

1974-01-01

Presents some materials for use in demonstration and experimentation of corrosion processes, including corrosion stimulation and inhibition. Indicates that basic concepts of electrochemistry, crystal structure, and kinetics can be extended to practical chemistry through corrosion explanation. (CC)

Effect of microstructure on corrosion behavior of Ag-30Cu-27Sn alloy in vitro media

International Nuclear Information System (INIS)

Salehisaki, Mehdi; Aryana, Maryam

2014-01-01

Highlights: • High cooling rates decrease the number of Ag intermetallic particles in Cu-rich phase. • Increasing cooling rate improves corrosion behavior of Ag-30Cu-27Sn dental alloy. • Cathode/anode ratio in Cu-rich phases determines the corrosion behavior of alloy. - Abstract: In the present work, three simple heat treatment cycles were used to study the effects of microstructure on electrochemical corrosion behavior of Ag-30Cu-27Sn dental alloy. The electrochemical impedance spectroscopy (EIS) measurements and potentiodynamic polarization tests were carried out to investigate the corrosion behavior of as-cast and heat treated samples in synthetic saliva solution. The presence of intermetallic compounds were studied by X-ray diffraction method (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray detector (EDAX). The microstructural observations and electrochemical corrosion results revealed that, increasing the cooling rate improves the corrosion behavior of under investigation samples. Improvement of the corrosion behavior is attributed to reducing the area of fine distributed Ag 3 Sn islands in the Cu-rich matrix which decrease the cathode/anode ratio of microgalvanic cells

Future and benefits of corrosion research

International Nuclear Information System (INIS)

Staehle, Roger W.

2002-01-01

The subject of corrosion is a design science. The subject of stress analysis is a design science as is the subject of heat transfer. When the subject of corrosion is considered in the framework design a clear framework of the priorities and objectives becomes apparent. Further, corrosion becomes a more explicit and important subject in the overall design, manufacturing, and operation phases of equipment: in this framework, the funding and support of corrosion work is necessary to the designers and users of equipment. The subject of corrosion is usually less important in the early stages of operation of equipment: in these early stages, the subjects. Corrosion becomes important to the longer term reliability and safety of equipment. Corrosion is often a principal determiner of design life. Corrosion is often more important after the manufacturing warranty is expired: therefore the subject is often more important to the user than to the manufacturer. In order that the subject of corrosion is considered and incorporated in the design as well as in user specifications, there must be a language and means of easily understood communication between the design-operation community and the corrosion community. For example, the designers do not understand the language of 'pitting potential': rather, they understand design life and permissible stress. Thus, corrosion must be put into terms that can be understood and utilized by designers and operators. Two methodologies have been developed for communicating effectively between the corrosion and the design communities: these are the 'Corrosion Based Design Approach' and the 'Location for Analysis Matrix.' These provide simple check off lists to designers for asking questions and assuring that credible answers have been obtained on issues that affect reliable and economic performance. Both of these subject are discussed in this presentation. The future of corrosion research is its effective linkage with design and operation of

Effect of Ethanolamines on Corrosion Inhibition of Ductile Cast Iron in Nitrite Containing Solutions

International Nuclear Information System (INIS)

Kim, K. T.; Kim, Y. S.; Chang, H. Y.; Lim, B. T.; Park, H. B.

2016-01-01

In this work, synergistic corrosion inhibition effect of nitrite and 3 kinds of ethanolamines on ductile cast iron using chemical and electrochemical methods was evaluated. This work attempts to clarify the synergistic effect of nitrite and ethanolamines. The effects of single addition of TEA, DEA, and MEA, and mixed addition of nitrite plus TEA, DEA or MEA on the corrosion inhibition of ductile cast iron in a tap water were evaluated. A huge amount of single addition of ethanolamine was needed. However, the synergistic effect by mixed addition was observed regardless of the combination of nitrite and triethanolamines, but their effects increased in a series of MEA + nitrite > DEA + nitrite > TEA + nitrite. This tendency of synergistic effect was attributed to the film properties and polar effect; TEA addition couldn't form the film showing high film resistance and semiconductive properties, but DEA or MEA could build the film having relatively high film resistance and n-type semiconductive properties. Moreover, it can be explained that this behaviour was closely related to electron attractive group within the ethanolamines, and thus corrosion inhibition power depends upon the number of the electron attractive group of MEA, DEA, and TEA.

Effect of Ethanolamines on Corrosion Inhibition of Ductile Cast Iron in Nitrite Containing Solutions

Energy Technology Data Exchange (ETDEWEB)

Kim, K. T.; Kim, Y. S. [Andong National University, Andong (Korea, Republic of); Chang, H. Y.; Lim, B. T.; Park, H. B. [KEPCO Engineering and Construction Company, Gimcheon (Korea, Republic of)

2016-08-15

In this work, synergistic corrosion inhibition effect of nitrite and 3 kinds of ethanolamines on ductile cast iron using chemical and electrochemical methods was evaluated. This work attempts to clarify the synergistic effect of nitrite and ethanolamines. The effects of single addition of TEA, DEA, and MEA, and mixed addition of nitrite plus TEA, DEA or MEA on the corrosion inhibition of ductile cast iron in a tap water were evaluated. A huge amount of single addition of ethanolamine was needed. However, the synergistic effect by mixed addition was observed regardless of the combination of nitrite and triethanolamines, but their effects increased in a series of MEA + nitrite > DEA + nitrite > TEA + nitrite. This tendency of synergistic effect was attributed to the film properties and polar effect; TEA addition couldn't form the film showing high film resistance and semiconductive properties, but DEA or MEA could build the film having relatively high film resistance and n-type semiconductive properties. Moreover, it can be explained that this behaviour was closely related to electron attractive group within the ethanolamines, and thus corrosion inhibition power depends upon the number of the electron attractive group of MEA, DEA, and TEA.

Effect of boron control of environment on corrosion and resistance to low-cycle corrosion fatigue in structural steels

International Nuclear Information System (INIS)

Babej, Yu.I.; Zhitkov, V.V.; Zvezdin, Yu.I.; Liskevich, I.Yu.; Nazarov, A.A.

1982-01-01

Tests of the specimens on total, contact and crevice corrosion, corrosion cracking and low-cycle fatigue are conducted for determination of corrosion and corrosion-fatigue characteristics in the 15Kh3NMFA, 10N3MFA, 10Kh16N4B, 05Kh13N6M2 structural steels, used in energetics. The environment is subjected to boron control and contacting with atmosphere for simulation of stop and operation modes of the facility. The experiments are carried out in the distilled water with 12g/l H 3 BO 3 and 10 mg/l Cl' at 25, 60, 100 deg C under contacting with atmosphere. It is established, that the pearlitic steels 15Kh3NMFA, 10N3MFA, as well as transition and martensitic 05Kh13N6M2 and 10Kh16N4B steels are highly stable to total, crevice and contact corrosion at the high parameters of aqueous boron-containing medium. Steel resistance to low-cycle fracture decreases slightly under the conditions similar to the operation ones, in the water with 12 g/l H 3 BO 3 . Durability of the pearlitic steels at the simulation of stop conditions decreases more noticeably, crack formation as a rule, initiating from corrosion spots

Studies on the biosynthesis of macrophage migration inhibitory factor in delayed hypersensitivity, 1. Effects of inhibitors of nucleic acid and protein synthesis on the production of macrophage migration inhibitory factor

Energy Technology Data Exchange (ETDEWEB)

Mizoguchi, Y; Yamamoto, S; Morisawa, S [Osaka City Univ. (Japan). Faculty of Medicine

1973-03-01

Specific antigenic stimulation of sensitized lymphocytes leads to the production of macrophage migration inhibitory factor (MIF). Production of MIF is inhibited by mitomycin C, actinomycin D, and puromycin. These inhibition effects are studied by using thymidine-/sup 3/H. The first two of these antibiotics only inhibit MIF production when added to the culture medium at a very early stage of antigenic stimulation. In contrast, puromycin exerts its inhibitory effect several hours after the antigenic stimulation, but not at an earlier stage. MIF behaves like a protein, so it seems likely that synthesis of RNA is necessary for MIF formation and MIF synthesis may start as early as a few hours after specific antigenic activation of the sensitized lymphocytes. The inhibitory effects of the antibiotics are discussed in relation to the kinetics of MIF production.

Contradictory effect of chromate inhibitor on corrosive wear of aluminium alloy

International Nuclear Information System (INIS)

Pokhmurskii, V.I.; Zin, I.M.; Vynar, V.A.; Bily, L.M.

2011-01-01

Research highlights: → Corrosive wear of aluminium alloy in inhibited artificial acid rain was studied. → Tribometer with linear reciprocating ball-on-flat geometry was used.→ Corrosion potential, polarization current and friction coefficient were measured. → Chromate decreases corrosion of aluminium alloy under wear conditions. → Chromate in general accelerates corrosive wear of the alloy in acid rain. - Abstract: The corrosive wear of D16T aluminium alloy in artificial acid rain was studied. A special tribometer with the linear reciprocating ball-on-flat geometry was used. The setup allows to measure simultaneously an open circuit potential, to carry out potentiostatic and potentiodynamic polarization studies of the alloy corrosion and to record the friction coefficient. It was established that the addition of strontium chromate inhibitor to the working environment decreases an electrochemical corrosion of the aluminium alloy under wear conditions, but in general accelerates its destruction due to insufficient wear resistance of a formed surface film.

Predicting the Performance of Organic Corrosion Inhibitors

Directory of Open Access Journals (Sweden)

David A. Winkler

2017-12-01

Full Text Available The withdrawal of effective but toxic corrosion inhibitors has provided an impetus for the discovery of new, benign organic compounds to fill that role. Concurrently, developments in the high-throughput synthesis of organic compounds, the establishment of large libraries of available chemicals, accelerated corrosion inhibition testing technologies, and the increased capability of machine learning methods have made discovery of new corrosion inhibitors much faster and cheaper than it used to be. We summarize these technical developments in the corrosion inhibition field and describe how data-driven machine learning methods can generate models linking molecular properties to corrosion inhibition that can be used to predict the performance of materials not yet synthesized or tested. We briefly summarize the literature on quantitative structure–property relationships models of small organic molecule corrosion inhibitors. The success of these models provides a paradigm for rapid discovery of novel, effective corrosion inhibitors for a range of metals and alloys in diverse environments.

Effect of calcium on the microstructure and corrosion behavior of microarc oxidized Mg-xCa alloys.

Science.gov (United States)

Pan, Yaokun; Chen, Chuanzhong; Feng, Rui; Cui, Hongwei; Gong, Benkui; Zheng, Tingting; Ji, Yarou

2018-01-16

Magnesium alloys are potential biodegradable implants for biomedical applications, and calcium (Ca) is one kind of ideal element being examined for magnesium alloys and biodegradable ceramic coatings owing to its biocompatibility and mechanical suitability. In this study, microarc oxidation (MAO) coatings were prepared on Mg-xCa alloys to study the effect of Ca on the microstructure and corrosion resistance of Mg-xCa alloys and their surface MAO coatings. The electrochemical corrosion behavior was investigated using an electrochemical workstation, and the degradability and bioactivity were evaluated by soaking tests in simulated body fluid (SBF) solutions. The corrosion products were characterized by scanning electron microscopy, x-ray diffractometry, and Fourier transform infrared spectrometry. The effects of Ca on the alloy phase composition, microstructure, MAO coating formation mechanism, and corrosion behavior were investigated. Results showed that the Mg-0.82Ca alloy and MAO-coated Mg-0.82Ca exhibited the highest corrosion resistance. The number and distribution of Mg 2 Ca phases can be controlled by adjusting the Ca content in the Mg-xCa alloys. The proper amount of Ca in magnesium alloy was about 0.5-0.8 wt. %. The pore size, surface roughness, and corrosion behavior of microarc oxidized Mg-xCa samples can be controlled by the number and distribution of the Mg 2 Ca phase. The corrosion behaviors of microarc oxidized Mg-Ca in SBF solutions were discussed.

Effect of H{sub 2}O{sub 2} on the corrosion behavior of 304L stainless steel

Energy Technology Data Exchange (ETDEWEB)

Song, Taek Hoh; Kim, In Sub [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of); Noh, Sung Kee [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1995-08-01

In connection with the safe storage of high level nuclear waste, effect of H{sub 2}O{sub 2} on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H{sub 2}O{sub 2}. The experimental results show that H{sub 2}O{sub 2} increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H{sub 2}O{sub 2} concentration increased, indicating that pitting resistance was decreased by the existence of H{sub 2}O{sub 2} in the electrolyte. These effects of H{sub 2}O{sub 2} on corrosion of 304L stainless steel are considered to be similar to those of {gamma}-irradiation. To compare the effects of H{sub 2}O{sub 2} with those of O{sub 2}, cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H{sub 2}O{sub 2} on the corrosion behavior were very similar to those of O{sub 2} such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. In acid and alkaline media, the corrosion potential shifts by H{sub 2}O{sub 2} were restricted by the large current density of proton reduction and by the le Chatelier`s principle respectively. 13 figs., 1 tabs., 17 refs. (Author).

The effect of mucin, fibrinogen and IgG on the corrosion behaviour of Ni-Ti alloy and stainless steel.

Science.gov (United States)

Chao, Zhang; Yaomu, Xiao; Chufeng, Liu; Conghua, Liu

2017-06-01

In this study, Ni-Ti alloy and stainless steal were exposed to artificial saliva containing fibrinogen, IgG or mucin, and the resultant corrosion behavior was studied. The purpose was to determine the mechanisms by which different types of protein contribute to corrosion. The effect of different proteins on the electrochemical resistance of Ni-Ti and SS was tested by potentiodynamic polarization, and the repair capacity of passivation film was tested by cyclic polarization measurements. The dissolved corrosion products were determined by ICP-OES, and the surface was analyzed by SEM and AFM. The results showed fibrinogen, IgG or mucin could have different influences on the susceptibility to corrosion of the same alloy. Adding protein lead to the decrease of corrosion resistance of SS, whereas protein could slow down the corrosion process of Ni-Ti. For Ni-Ti, adding mucin could enhance the corrosion stability and repair capacity of passivation film. The susceptibility to pitting corrosion of Ni-Ti and stainless steal in fibrinogen AS is not as high as mucin and IgG AS. There are different patterns of deposition formation on the metal surface by different types of protein, which is associated with their effects on the corrosion process of the alloys.

Mobile evaporator corrosion test results

International Nuclear Information System (INIS)

Rozeveld, A.; Chamberlain, D.B.

1997-05-01

Laboratory corrosion tests were conducted on eight candidates to select a durable and cost-effective alloy for use in mobile evaporators to process radioactive waste solutions. Based on an extensive literature survey of corrosion data, three stainless steel alloys (304L, 316L, AL-6XN), four nickel-based alloys (825, 625, 690, G-30), and titanium were selected for testing. The corrosion tests included vapor phase, liquid junction (interface), liquid immersion, and crevice corrosion tests on plain and welded samples of candidate materials. Tests were conducted at 80 degrees C for 45 days in two different test solutions: a nitric acid solution. to simulate evaporator conditions during the processing of the cesium ion-exchange eluant and a highly alkaline sodium hydroxide solution to simulate the composition of Tank 241-AW-101 during evaporation. All of the alloys exhibited excellent corrosion resistance in the alkaline test solution. Corrosion rates were very low and localized corrosion was not observed. Results from the nitric acid tests showed that only 316L stainless steel did not meet our performance criteria. The 316L welded interface and crevice specimens had rates of 22.2 mpy and 21.8 mpy, respectively, which exceeds the maximum corrosion rate of 20 mpy. The other welded samples had about the same corrosion resistance as the plain samples. None of the welded samples showed preferential weld or heat-affected zone (HAZ) attack. Vapor corrosion was negligible for all alloys. All of the alloys except 316L exhibited either open-quotes satisfactoryclose quotes (2-20 mpy) or open-quotes excellentclose quotes (<2 mpy) corrosion resistance as defined by National Association of Corrosion Engineers. However, many of the alloys experienced intergranular corrosion in the nitric acid test solution, which could indicate a susceptibility to stress corrosion cracking (SCC) in this environment

Effect of Adenine Concentration on the Corrosion Inhibition of Aisi ...

African Journals Online (AJOL)

This gave a surface coverage of 0.8956 and corrosion penetration rate of 0.022132mm/yr. Hence, the best adenine concentration for the corrosion inhibition of alloys 304L in 1.0M sulphuric acid solution to obtain optimum inhibition efficiency is 0.011M. Keywords: Corrosion, AISI 304L Steel, Inhibition efficiency, Degree of ...

Electrochemical analysis of the corrosion inhibition effect of trypsin complex on the pitting corrosion of 420 martensitic stainless steel in 2M H2SO4 solution.

Science.gov (United States)

Loto, Roland Tolulope

2018-01-01

Inhibition effect of trypsin complex (TC) on the pitting corrosion of martensitic stainless steel (type 420) in 1M H2SO4 solution was studied with potentiodynamic polarization, open circuit potential measurement and optical microscopy. TC reduced the corrosion rate of the steel with maximum inhibition efficiency of 80.75%. Corrosion potential shifted anodically due to the electrochemical action of TC. The pitting potential increased from 1.088VAg/AgCl (3M) at 0% TC to 1.365VAg/AgCl(3M) at 4% TC. TC shifts the open circuit corrosion potential from -0.270s at 0% TC concentration to -0.255V at 5% TC. The compound completely adsorbed onto the steel according to Langmuir, Frumkin and Temkin isotherms. ATF-FTIR spectroscopy confirmed the inhibition mode to be through surface coverage. Thermodynamic calculations showed physisorption molecular interaction. Corrosion pits are present on the uninhibited 420 morphology in comparison to TC inhibited surface which slightly deteriorated.

In situ synchrotron X-ray diffraction study of the effect of microstructure and boundary layer conditions on CO2 corrosion of pipeline steels

International Nuclear Information System (INIS)

Ko, M.; Ingham, B.; Laycock, N.; Williams, D.E.

2015-01-01

Highlights: • We studied the effects of steel microstructures and local conditions on CO 2 corrosion. • Microstructure influences the development of surface roughness during corrosion. • The effects of Cr alloying, on average, dominate over the effects of microstructure. • Spatial segregation of Cr between the phases in the steel may result in localised corrosion. - Abstract: This study demonstrates that the nucleation of crystalline scales of siderite and chukanovite onto the surface of low-alloy steels under CO 2 corrosion at elevated temperature is critically dependent on initial surface roughness, on microstructure-related surface roughness developed during corrosion, and on stirring in the solution. This study confirms that effects due to chromium micro-alloying in the steel are extremely important for siderite nucleation. On average, these effects dominate over the effects of microstructure. However, spatial variation of the corrosion deposit thickness indicates an interdependence between microstructure and chromium-enhanced siderite nucleation with the possibility of localised corrosion developing as a result

Possible effects of external electrical fields on the corrosion of copper in bentonite

Energy Technology Data Exchange (ETDEWEB)

Taxen, Claes (Swerea KIMAB (Sweden))

2011-12-15

External potentials that develop across a repository may interact with the copper canister. A study was undertaken to investigate the potential corrosion effects of voltage differences in a repository. A set of experiments was performed to study the tendency of copper in bentonite to corrode under influence of an externally applied electrical field. A model study was made to estimate possible corrosion effects of an external electrical field on a full-scale canister in the KBS-3 concept. The interaction between the repository represented by a copper canister in bentonite, and an external electrical field is illustrated with an example

The effect of functionalized polycarboxylate structures as corrosion inhibitors in a simulated concrete pore solution

Science.gov (United States)

Fazayel, A. S.; Khorasani, M.; Sarabi, A. A.

2018-05-01

In this study, the effects of polycarboxylate derivatives with different comonomers and functional groups on the control or reduction of corrosion in steel specimens were evaluated through electrochemical impedance spectroscopy (EIS) and potentiodynamic analysis. A highly alkaline contaminated concrete pore solution (CPS) containing chlorides was used to simulate the pitting corrosion, and according to the results, the mechanism of inhibitive action was determined. Both the inhibition efficiency and pitting corrosion inhibition of methacrylate-copolymers were in the order of poly methacrylate-co acrylamide > poly methacrylate-co-2-acrylamido-2 methylpropane sulfonic acid > poly methacrylate-co-hydroxyethyl methacrylate. In addition, the corrosion potential of steel specimens in all studied concentrations of NaCl with different concentrations of polymethacrylate-co acrylamide (as the best inhibitor in this study) in saturated Ca(OH)2 solution showed almost an identical trend. Polymethacrylic acid-co-acrylamide showed a 92.35% inhibitor efficiency in the saturated Ca(OH)2 solution containing 1.8 wt.% chlorides and could effectively reduce the corrosion rate. Even at 3.5 wt.% of NaCl, this inhibitor could remarkably reduce the destructive effect of chloride ion attacks on the steel surface and passive film. The inhibition effect of these polymeric inhibitors seemed to be due to the formation of a barrier layer on the metal surface, approved by the well-known adsorption mechanism of organic molecules at the metal/solution interface. The results of SEM, EDS and AFM investigations were also in agreement with the outcomes of electrochemical studies.

Effect of Sulfide Concentration on Copper Corrosion in Anoxic Chloride-Containing Solutions

Science.gov (United States)

Kong, Decheng; Dong, Chaofang; Xu, Aoni; Man, Cheng; He, Chang; Li, Xiaogang

2017-04-01

The structure and property of passive film on copper are strongly dependent on the sulfide concentration; based on this, a series of electrochemical methods were applied to investigate the effect of sulfide concentration on copper corrosion in anaerobic chloride-containing solutions. The cyclic voltammetry and x-ray photoelectron spectroscopy analysis demonstrated that the corrosion products formed on copper in anaerobic sulfide solutions comprise Cu2S and CuS. And the corrosion resistance of copper decreased with increasing sulfide concentration and faster sulfide addition, owing to the various structures of the passive films observed by the atomic force microscope and scanning electron microscope. A p-type semiconductor character was obtained under all experimental conditions, and the defect concentration, which had a magnitude of 1022-1023 cm-3, increased with increasing sulfide concentration, resulting in a higher rate of both film growth and dissolution.

Mechanisms underlying electrical and mechanical responses of the bovine retractor penis to inhibitory nerve stimulation and to an inhibitory extract.

Science.gov (United States)

Byrne, N. G.; Muir, T. C.

1985-01-01

The response of the bovine retractor penis (BRP) to stimulation of non-adrenergic, non-cholinergic (NANC) inhibitory nerves and to an inhibitory extract prepared from this muscle have been studied using intracellular microelectrode, sucrose gap and conventional mechanical recording techniques. Both inhibitory nerve stimulation and inhibitory extract hyperpolarized the membrane potential and relaxed spontaneous or guanethidine (3 X 10(-5) M)-induced tone. These effects were accompanied by an increase in membrane resistance. Following membrane potential displacement from an average value of -53 +/- 7 mV (n = 184; Byrne & Muir, 1984) inhibitory potentials to nerve stimulation were abolished at approximately -30 mV; there was no evidence of reversal. Displacement by inward hyperpolarizing current over the range -45 to -60 mV increased the inhibitory response to nerve stimulation and to inhibitory extract; at more negative potential values (above approximately -60 mV) the inhibitory potential decreased and was abolished (approximately -103 mV). There was no evidence of reversal. Removal of [K+]o reversibly reduced hyperpolarization to nerve stimulation and inhibitory extract. No enhancement was observed. Increasing the [K+]o to 20 mM reduced the inhibitory potential to nerve stimulation but this was restored by passive membrane hyperpolarization. Inhibitory potentials were obtained at membrane potential values exceeding that of the estimated EK (-49 mV). [Cl-]o-free or [Cl-]o-deficient solutions reduced and abolished (after some 20-25 min) the hyperpolarization produced by inhibitory nerve stimulation or inhibitory extract. The inhibitory potential amplitude following nerve stimulation was not restored by passive displacement of the membrane potential from -26 to -104 mV approximately. Ouabain (1-5 X 10(-5) M) reduced then (45-60 min later) abolished the inhibitory potential to nerve stimulation. The effects of this drug on the extract were not investigated. It is

Area effect on galvanic corrosion of condenser materials with titanium tubes in nuclear power plants

International Nuclear Information System (INIS)

Hwang, Seong Sik; Kim, Joung Soo; Kim, Uh Chul

1993-01-01

Titanium tubes have recently been used in condensers of nuclear power plants since titanium has very good corrosion resistance to seawater. However, when it is connected to Cu alloys as tube sheet materials and these Cu alloys are connected to carbon steels as water box materials, it makes significant galvanic corrosion on connected materials. It is expected from electrochemical tests that the corrosion rate of carbon steel will increase when it is galvanically coupled with Ti or Cu in sea water and the corrosion rate of Cu will increase when it is coupled with Ti, of this couple is exposed to sea water for a long time. It is also expected that the surface area ratios, R 1 (surface area of carbon steel/surface area of Ti) and R 2 (surface area of carbon steel/surface area of Cu) are very improtant for the galvanic corrosion of carbon steel and that these should not be kept to low values in order to minimize the galvanic corrosion on the carbon steel of the water box. Immersed galvanic corrosion tests show that the corrosion rate of carbon steel is 4.4 mpy when this ratio is 10 -2 . The galvanic corrosion rate of this carbon steel is increased from 4.4 mpy to 13 mpy at this area ratio, 1, when this connected galvanic specimen is galvanically coupled with a Ti tube. This can be rationalized by the combined effects of R 1 and R 2 on the polarization curve. (Author)

Inhibitory effects of silver zeolite on in vitro growth of fish egg pathogen, Saprolegnia sp.

Directory of Open Access Journals (Sweden)

Seyed Ali Johari

2014-05-01

Full Text Available Objective: To investigate the effects of powdered silver zeolite (SZ on the in vitro growth of the fish pathogen Saprolegnia sp. Methods: The antifungal activity of SZ was evaluated by determining the minimum inhibitory concentrations using two-fold serial dilutions of powdered SZ in a glucose yeast extract agar at 22 °C. The growth of Saprolegnia sp. on the SZ agar treatments was compared to that on SZ-free agar controls. Results: The results showed that SZ had an inhibitory effect on the in vitro growth of the tested fungi. The minimum inhibitory concentration of SZ for Saprolegnia sp. was also calculated at 600 mg/L, which is equal to 0.06 percent. Conclusions: SZ is a potential good candidate to replace teratogenic and toxic agents, such as malachite green in aquaculture systems.

Fundamental studies of aluminum corrosion in acidic and basic environments: Theoretical predictions and experimental observations

International Nuclear Information System (INIS)

Lashgari, Mohsen; Malek, Ali M.

2010-01-01

Using quantum electrochemical approaches based on density functional theory and cluster/polarized continuum model, we investigated the corrosion behavior of aluminum in HCl and NaOH media containing phenol inhibitor. In this regard, we determined the geometry and electronic structure of the species at metal/solution interface. The investigations revealed that the interaction energies of hydroxide corrosive agents with aluminum surface should be more negative than those of chloride ones. The inhibitor adsorption in acid is more likely to have a physical nature while it appears as though to be chemical in basic media. To verify these predictions, using Tafel plots, we studied the phenomena from experimental viewpoint. The studies confirmed that the rate of corrosion in alkaline solution is substantially greater than in HCl media. Moreover, phenol is a potential-molecule having mixed-type inhibition mechanism. The relationship between inhibitory action and molecular parameters was discussed and the activity in alkaline media was also theoretically anticipated. This prediction was in accord with experiment.

Effect of the Type of Surface Treatment and Cement on the Chloride Induced Corrosion of Galvanized Reinforcements

Science.gov (United States)

Tittarelli, Francesca; Mobili, Alessandra; Vicerè, Anna Maria; Roventi, Gabriella; Bellezze, Tiziano

2017-10-01

The effect of a new passivation treatment, obtained by immersion of the galvanized reinforcements in a trivalent chromium salts based solution, on the chlorides induced corrosion has been investigated. To investigate also the effect of cement alkalinity on corrosion behaviour of reinforcements, concretes manufactured with three different European cements were compared. The obtained results show that the alternative treatment based on hexavalent chromium-free baths forms effective protection layers on the galvanized rebar surfaces. The higher corrosion rates of zinc coating in concrete manufactured with Portland cement compared to those recorded for bars in concrete manufactured with pozzolanic cement depends strongly on the higher chloride content at the steel concrete interface.

The effect of Electro Discharge Machining (EDM) on the corrosion resistance of dental alloys.

Science.gov (United States)

Ntasi, Argyro; Mueller, Wolf Dieter; Eliades, George; Zinelis, Spiros

2010-12-01

The aim of the present study was to evaluate the effect of Electro Discharge Machining (EDM) on the corrosion resistance of two types of dental alloys used for fabrication of implant retained superstructures. Two groups of specimens were prepared from a Co-Cr (Okta-C) and a grade II cpTi (Biotan) alloys respectively. Half of the specimens were subjected to EDM with Cu electrodes and the rest were conventionally finished (CF). The corrosion resistance of the alloys was evaluated by anodic polarization in Ringer's solution. Morphological and elemental alterations before and after corrosion testing were studied by SEM/EDX. Six regions were analyzed on each surface before and after corrosion testing and the results were statistically analyzed by paired t-test (a=0.05). EDM demonstrated inferior corrosion resistance compared to CF surfaces, the latter being passive in a wider range of potential demonstrating higher polarization resistance and lower I(corr) values. Morphological alterations were found before and after corrosion testing for both materials tested after SEM analysis. EDX showed a significant decrease in Mo, Cr, Co, Cu (Co-Cr) and Ti, Cu (cpTi) after electrochemical testing plus an increase in C. According to the results of this study the EDM procedure decreases the corrosion resistance of both the alloys tested, increasing thus the risk of possible adverse biological reactions. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Chemical and structural effects of phosphorus on the corrosion behavior of ion beam mixed Fe-Cr-P alloys

International Nuclear Information System (INIS)

Demaree, J.D.; Was, G.S.; Sorensen, N.R.

1992-01-01

An experimental program was conducted to determine the mechanisms by which phosphorus affects the corrosion and passivation behavior of Fe-Cr-P alloys. To identify separately the effects of structure and chemistry on the corrosion behavior, thin films of Fe-10Cr-xP (0≤x≤35 at.%) were prepared by ion beam mixing. Films with a phosphorus content greater than approximately 20at.% were found to be entirely amorphous. Devitrification of the amorphous phase was accomplished by heating the samples to 450degC in an inert environment. Standard polarization tests of the sulfuric acid (with and without Cl - ) indicated that the films containing phosphorus were more corrosion resistant than Fe-10Cr, at both active and passive potentials. There was a monotonic relationship between the amount of phosphorus in the alloy and the corrosion resistance, with the open-circuit corrosion rate of Fe-10Cr-35P nearly four orders of magnitude lower than that of Fe-10Cr. Devitrification of the alloys had no significant effect on the corrosion rate, indicating that the primary effect of phosphorus is chemical in nature, and not structural. The passive oxides were depth-profiled using X-ray photoelectron spectroscopy, which indicated that phosphorus was a primary constituent, as phosphate. The presence of phosphate in the passive oxides reduced the overall corrosion rate directly, by suppressing anodic dissolution. The presence of phosphorus did enhance chromium enrichment in the oxide, but that was not thought to be the primary mechanism by which phosphorus increased the corrosion resistance. (orig.)

Inhibitory effect of flavonoids from citrus plants on Epstein-Barr virus activation and two-stage carcinogenesis of skin tumors.

Science.gov (United States)

Iwase, Y; Takemura, Y; Ju-ichi, M; Ito, C; Furukawa, H; Kawaii, S; Yano, M; Mou, X Y; Takayasu, J; Tokuda, H; Nishino, H

2000-06-01

To search for possible anti-tumor promoters, thirteen flavones (1-13) obtained from the peel of Citrus plants were examined for their inhibitory effects on the Epstein-Barr virus early antigen (EBV-EA) activation by a short-term in vitro assay. Of these flavones, 3,5,6,7,8,3',4'-heptamethoxyflavone (HPT) (13) exhibited significant inhibitory effects on the EBV-EA activation induced by the tumor promoter, 12-O-tetradecanoylphorbol 13-acetate (TPA). Further, compound 13 exhibited remarkable inhibitory effects on mouse skin tumor promotion in an in vivo two-stage carcinogenesis test.

Corrosion-product transport, oxidation state and remedial measures

International Nuclear Information System (INIS)

Sawicki, J.A.; Brett, M.E.; Tapping, R.L.

1998-01-01

The issues associated with monitoring and controlling corrosion-product transport (CPT) in the balance-of-plant (BOP) and steam generators (SG) of CANDU stations are briefly reviewed. The efforts are focused on minimizing corrosion of carbon steel, which is used extensively in the CANDU primary and secondary systems. Emphasis is placed on the corrosion-product oxidation state as a monitor of water chemistry effectiveness, and as a monitor of system corrosion effects. The discussion is based mostly on the results and observations from Ontario Hydro plants, and their comparisons with PWRs. The effects of low oxygen and elevated hydrazine chemistry are reviewed, as well as the effects of lay-up and various start-up conditions. Progress in monitoring electrochemical potential (ECP) at Ontario Hydro plants and its relationship to the oxidation state of corrosion products is reviewed. Observations on corrosion-product transport on the primary side of steam generators are also discussed. (author)

Effects of the Solid Solution Heat Treatment on the Corrosion Resistance Property of SSC13 Cast Alloy

Energy Technology Data Exchange (ETDEWEB)

Kim, Kuk-Jin [Hi-Sten Co., Ltd., Gimhae (Korea, Republic of); Lim, Su Gun [Gyeongsang National University, Jinju (Korea, Republic of); Pak, S. J. [Gachon BioNano Research Institute, Gachon University, Sungnam (Korea, Republic of)

2015-04-15

Recently, Stainless steels have been increasingly selected as the fitting or the valve materials of water pipes as the human health issue is getting higher and higher. Therefore, the connectors attached at pipes to deliver water are exposed to more severe environments than the pipes because crevice or galvanic corrosion is apt to occur at the fittings or the valves. Effects of the solid solution annealing, cooling rate after this heat treatment, and passivation on the corrosion properties of the shell mold casted SSC13 (STS304 alloy equivalent) were studied. The heating and quenching treatment more or less reduced hardness but effectively improved corrosion resistance. It was explained by the reduction of delta ferrite contents. Independent of heat treatment, the chemical passivation treatment also lowered corrosion rate but the improvement of corrosion resistance depended on temperature and time for passivation treatment indicating that the optimum conditions for passivation treatment were the bath temperature of 34 .deg. C and operating time of 10 minutes. Therefore it is suggested that the corrosion resistance of SSC13 can be effectively improved with the heat treatment, where SSC13 is heated for 10 minutes at 1120 °C and quenched and passivation treatment, where SSC13 is passivated for at least 10 seconds at 34 °C nitric acid solution.

Self-DNA inhibitory effects: Underlying mechanisms and ecological implications.

Science.gov (United States)

Cartenì, Fabrizio; Bonanomi, Giuliano; Giannino, Francesco; Incerti, Guido; Vincenot, Christian Ernest; Chiusano, Maria Luisa; Mazzoleni, Stefano

2016-01-01

DNA is usually known as the molecule that carries the instructions necessary for cell functioning and genetic inheritance. A recent discovery reported a new functional role for extracellular DNA. After fragmentation, either by natural or artificial decomposition, small DNA molecules (between ∼50 and ∼2000 bp) exert a species specific inhibitory effect on individuals of the same species. Evidence shows that such effect occurs for a wide range of organisms, suggesting a general biological process. In this paper we explore the possible molecular mechanisms behind those findings and discuss the ecological implications, specifically those related to plant species coexistence.

High temperature corrosion of metals

International Nuclear Information System (INIS)

Quadakkers, W.J.; Schuster, H.; Ennis, P.J.

1988-08-01

This paper covers three main topics: 1. high temperature oxidation of metals and alloys, 2. corrosion in sulfur containing environments and 3. structural changes caused by corrosion. The following 21 subjects are discussed: Influence of implanted yttrium and lanthanum on the oxidation behaviour of beta-NiA1; influence of reactive elements on the adherence and protective properties of alumina scales; problems related to the application of very fine markers in studying the mechanism of thin scale formation; oxidation behaviour of chromia forming Co-Cr-Al alloys with or without reactive element additions; growth and properties of chromia-scales on high-temperature alloys; quantification of the depletion zone in high temperature alloys after oxidation in process gas; effects of HC1 and of N2 in the oxidation of Fe-20Cr; investigation under nuclear safety aspects of Zircaloy-4 oxidation kinetics at high temperatures in air; on the sulfide corrosion of metallic materials; high temperature sulfide corrosion of Mn, Nb and Nb-Si alloys; corrosion behaviour or NiCrAl-based alloys in air and air-SO2 gas mixtures; sulfidation of cobalt at high temperatures; preoxidation for sulfidation protection; fireside corrosion and application of additives in electric utility boilers; transport properties of scales with complex defect structures; observations of whiskers and pyramids during high temperature corrosion of iron in SO2; corrosion and creep of alloy 800H under simulated coal gasification conditions; microstructural changes of HK 40 cast alloy caused by exploitation in tubes in steam reformer installation; microstructural changes during exposure in corrosive environments and their effect on mechanical properties; coatings against carburization; mathematical modeling of carbon diffusion and carbide precipitation in Ni-Cr-based alloys. (MM)

Corrosion in airframes

OpenAIRE

PETROVIC ZORAN C.

2016-01-01

The introductory chapter provides a brief reference to the issue of corrosion and corrosion damage to aircraft structures. Depending on the nature and dimensions of this non uniformity, three different categories of corrosion are defined: uniform, selective and localized corrosion. The following chapters present the forms of corrosion that can occur in three defined categories of corrosion. Conditions that cause certain types of corrosion in various corrosive environments are discussed. Examp...

Corrosion Control in the Aerospace Industry

Science.gov (United States)

Calle, Luz Marina; Li, Wenyan; Buhrow, Jerry W.; Johnsey, Marissa N.

2016-01-01

Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. It is essential to detect corrosion when it occurs, and preferably at its early stage, so that action can be taken to avoid structural damage or loss of function. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional, smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it..

Corrosion engineering

Energy Technology Data Exchange (ETDEWEB)

Fontana, M.G.

1986-01-01

This book emphasizes the engineering approach to handling corrosion. It presents corrosion data by corrosives or environments rather than by materials. It discusses the corrosion engineering of noble metals, ''exotic'' metals, non-metallics, coatings, mechanical properties, and corrosion testing, as well as modern concepts. New sections have been added on fracture mechanics, laser alloying, nuclear waste isolation, solar energy, geothermal energy, and the Statue of Liberty. Special isocorrosion charts, developed by the author, are introduced as a quick way to look at candidates for a particular corrosive.

Effect of soil compositions on the electrochemical corrosion behavior of carbon steel in simulated soil solution

Energy Technology Data Exchange (ETDEWEB)

Liu, T.M. [College of Materials Science and Engineering, Chongqing University (China); Luo, S.X. [Department of Chemistry, Zunyi Normal College, Zunyi (China); Sun, C. [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang (China); Wu, Y.H.

2010-04-15

In this study, effect of cations, Ca{sup 2+}, Mg{sup 2+}, K{sup +}, and anions, SO{sub 4}{sup 2-}, HCO{sub 3}{sup -}, NO{sub 3}{sup -} on electrochemical corrosion behavior of carbon steel in simulated soil solution was investigated through potentiodynamic polarization curves and electrochemical impedance spectroscopy. The results indicate that the Ca{sup 2+}and Mg{sup 2+} can decrease the corrosion current density of carbon steel in simulated soil solution, and K{sup +}, SO{sub 4}{sup 2-}, HCO{sub 3}{sup -}, and NO{sub 3}{sup -} can increase the corrosion density. All the above ions in the simulated soil solution can decrease its resistivity, but they have different effect on the charge transfer resistivity. This finding can be useful in evaluating the corrosivity of certain soil through chemical analysis, and provide data for construction engineers. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Corrosion investigations of high-alloyed steels carried out in different marine area organized by European Federation of Corrosion

International Nuclear Information System (INIS)

Birn, J.; Skalski, I.

1999-01-01

Research works arranged by EFC Working Party on Marine Corrosion are described. The research was performed in sea areas of Norway, Finland, Sweden, France, Italy, Poland and Netherlands. Subjected to test were three corrosion resistant steel grades; 316, 904 and UNS S 31524. Two corrosion tests were carried out in the years 1993 and 1994 each of min. 6 month duration. The results show that chemical composition of water at salinity level of more than 0.7% has not great effect on corrosion aggressivity in relation to corrosion resistant steels. On the other hand temperature of sea water has great influence on corrosion process. (author)

EFFECTS OF CHEMISTRY AND OTHER VARIABLES ON CORROSION AND STRESS CORROSION CRACKING IN HANFORD DOUBLE SHELL TANKS

Energy Technology Data Exchange (ETDEWEB)

BROWN MH

2008-11-13

Laboratory testing was performed to develop a comprehensive understanding of the corrosivity of the tank wastes stored in Double-Shell Tanks using simulants primarily from Tanks 241-AP-105, 241-SY-103 and 241-AW-105. Additional tests were conducted using simulants of the waste stored in 241-AZ-102, 241-SY-101, 241-AN-107, and 241-AY-101. This test program placed particular emphasis on defining the range of tank waste chemistries that do not induce the onset of localized forms of corrosion, particularly pitting and stress corrosion cracking. This document summarizes the key findings of the research program.

EFFECTS OF CHEMISTRY AND OTHER VARIABLES ON CORROSION AND STRESS CORROSION CRACKING IN HANFORD DOUBLE-SHELL TANKS

International Nuclear Information System (INIS)

Brown, M.H.

2008-01-01

Laboratory testing was performed to develop a comprehensive understanding of the corrosivity of the tank wastes stored in Double-Shell Tanks using simulants primarily from Tanks 241-AP-105, 241-SY-103 and 241-AW-105. Additional tests were conducted using simulants of the waste stored in 241-AZ-102, 241-SY-101, 241-AN-107, and 241-AY-101. This test program placed particular emphasis on defining the range of tank waste chemistries that do not induce the onset of localized forms of corrosion, particularly pitting and stress corrosion cracking. This document summarizes the key findings of the research program

Effects of cold work, sensitization treatment, and the combination on corrosion behavior of stainless steels in nitric acid

International Nuclear Information System (INIS)

Mayuzumi, M.; Ohta, J.; Arai, T.

1998-01-01

In a reprocessing process, spent nuclear fuels from light-water reactors are dissolved in nitric acid (HNO 3 ) to separate and recover the fissile materials such as uranium and plutonium from the radioactive fission products. Corrosion behavior of two stainless steels (SS) was investigated in nitric acid (HNO 3 ) for the effect of cold work (CW), sensitization heat treatment (Sens.), and a combination (CW + Sens.). The corrosion rate of the solution-treated type 304 SS (UNS S30400) with extra-low carbon (type 304ELC SS (UNS S30403)) increased with time and reached constant values after 1,000 h of immersion. However, constant corrosion rates were obtained for 25% Cr-20% Ni-Nb (type 310Nb SS [UNS S31040]) from the initial stage of immersion. CW mitigated corrosion of the solution-treated SS. The effect of CW was different on the two types of SS, with the sensitization heat-treated type 304 ELC SS showing higher corrosion rates and type 310Nb SS lower corrosion rates by CW. Corrosion resistance of type 310Nb SS was superior to type 304 ELC SS after all treatments. Chromium concentration of the sensitization-treated type 304 ELC SS was lower in the grain-boundary region than of the solution-treated one, although no chromium carbide precipitation was observed. This may have been the cause of intergranular corrosion enhancement by sensitization treatment

Biotribocorrosion-an appraisal of the time dependence of wear and corrosion interactions: I. The role of corrosion

International Nuclear Information System (INIS)

Yan, Y; Neville, A; Dowson, D

2006-01-01

With the increasing interest in metal-on-metal (MoM) joint implants, studies have been focused on their wear and corrosion behaviour. Integrated electrochemical tests have been conducted and are reported in this paper. The corrosion, wear and wear-corrosion behaviour for three materials (high carbon CoCrMo, low carbon CoCrMo and UNS S31603) have been discussed. Corrosion effects on the overall performance for the three materials are analysed. Two distinct regimes have been found for the three materials: (a) the running-in regime and (b) the steady state regime, in line with other research. Even in the steady state regime, 20%-30% of the material degradation can be attributed to corrosion-related damage. High carbon CoCrMo showed excellent corrosion, wear and corrosion-wear resistance and therefore it delivered the best overall performance in terms of a lower wear rate, a lower friction coefficient and a higher resistance to corrosion

Corrosion of porous silicon in tetramethylammonium hydroxide solution

International Nuclear Information System (INIS)

Lai, Chuan; Li, Xue-Ming; Zou, Li-Ke; Chen, Qiang; Xie, Bin; Li, Yu-Lian; Li, Xiao-Lin; Tao, Zhi

2014-01-01

Highlights: • The corrosion of porous silicon in (CH 3 ) 4 NOH solution was studied. • The residue of corrosion products was a mixture of [(CH 3 ) 4 N] 2 SiO 3 and SiO 2 . • The effect factors for porous silicon corrosion were elaborately investigated. • The additive of ethanol in (CH 3 ) 4 NOH solution could reduce the corrosion rate. • The 1.0 M (CH 3 ) 4 NOH could act as an applicable and novel corrosion solution. - Abstract: Corrosion of porous silicon in tetramethylammonium hydroxide (TMAH) solution was studied using weight loss measurements and scanning electron microscope. The effects of temperature, concentration of TMAH and volume ratio of ethanol in 1.0 M TMAH on corrosion rate and corrosion time were elaborately investigated. The residue of corrosion products were characterized as a mixture of [(CH 3 ) 4 N] 2 SiO 3 and SiO 2 . A comparative test among TMAH, KOH and NaOH illustrated that the 1.0 M TMAH could act as an applicable and novel corrosion solution to remove porous silicon layer for determining the porosity of porous silicon

Mechanism research on coupling effect between dew point corrosion and ash deposition

International Nuclear Information System (INIS)

Wang, Yun-Gang; Zhao, Qin-Xin; Zhang, Zhi-Xiang; Zhang, Zhi-Chao; Tao, Wen-Quan

2013-01-01

In order to study the coupling mechanism between ash deposition and dew point corrosion, five kinds of tube materials frequently used as anti-dew point corrosion materials were selected as research objects. Dew point corrosion and ash deposition experiments were performed with a new type experimental device in a Chinese thermal power plant. The microstructures of the materials and the composition of ash deposition were analyzed by X-ray diffraction (XRD) and Energy Dispersive Spectrometer (EDS). The results showed that the ash deposition layer could be divided into non-condensation zone, the main condensation zone and the secondary condensation zone. The acid vapor condensed in the main condensation zone rather than directly on the tube wall surface. The dew point corrosion mainly is oxygen corrosion under the condition of the viscosity ash deposition, and the corrosion products are composed of the ash and acid reaction products in the outer layer, iron sulfate in the middle layer, and iron oxide in the inner layer. The innermost layer is the main corrosion layer. With the increase of the tube wall temperature, the ash deposition changes from the viscosity ash deposition to the dry loose ash deposition, the ash deposition rate decreases dramatically and dew point corrosion is alleviated efficiently. The sulfuric dew point corrosion resistance of the five test materials is as follows: 316L > ND > Corten>20G > 20 steel. -- Highlights: ► Dew point corrosion and ash deposition tests of five materials were performed. ► Acid vapor condensed in the ash deposit rather than directly on the tube surface. ► Dew point corrosion resistance is as follow: 316L > ND > Corten>20G > 20 steel. ► Dew point corrosion mainly is oxygen corrosion under viscosity ash deposition

Anti-corrosive Effects of Multi-Walled Carbon Nano Tube and Zinc Particle Shapes on Zinc Ethyl Silicate Coated Carbon Steel

Energy Technology Data Exchange (ETDEWEB)

Jang, JiMan; Shon, MinYoung; Kwak, SamTak [Pukyong National University, Busan (Korea, Republic of)

2016-01-15

Zinc ethyl silicate coatings containing multi walled carbon nanotubes (MWCNTs) were prepared, to which we added spherical and flake shaped zinc particles. The anti-corrosive effects of MWCNTs and zinc shapes on the zinc ethyl silicate coated carbon steel was examined, using electrochemical impedance spectroscopy and corrosion potential measurement. The results of EIS and corrosion potential measurement showed that the zinc ethyl silicate coated with flake shaped zinc particles and MWCNT showed lesser protection to corrosion. These outcomes were in agreement with previous results of corrosion potential and corrosion occurrence.

Erosion–corrosion and corrosion properties of DLC coated low temperature Erosion–corrosion and corrosion properties of DLC coated low temperature

DEFF Research Database (Denmark)

Jellesen, Morten Stendahl; Christiansen, Thomas; Hilbert, Lisbeth Rischel

2009-01-01

of AISI 316 as substrate for DLC coatings are investigated. Corrosion and erosion–corrosion measurements were carried out on low temperature nitrided stainless steel AISI 316 and on low temperature nitrided stainless steel AISI 316 with a top layer of DLC. The combination of DLC and low temperature...... nitriding dramatically reduces the amount of erosion–corrosion of stainless steel under impingement of particles in a corrosive medium....

Effect Of Age And Concrete Cover Thickness On Steel Reinforcement Corrosion At Splash Zone In Reinforced Concrete Hydraulic Structures

Directory of Open Access Journals (Sweden)

Nada M. Al- Galawi

2015-08-01

Full Text Available Corrosion of reinforcing steel bars in reinforced concrete is considered as one of the biggest problems that face countries overlooking to the Arabian Gulf including Iraq. The research aims to study the effect of the corrosion of steel bars in concrete structures that are exposed to wetting and drying via waves. Reinforced concrete samples were exposed to marine simulated environment for 90 days using prepared system for this purpose. At the end of exposure period polarization test was implemented to measure the actual corrosion rate in each sample. After that the corrosion process was accelerated using impressed current technique by applying a constant electric current DC to the reinforcing bars. Depending on the corrosion current in natural conditions which was measured in polarization test periods of exposing samples to accelerated corrosion current so as to maintain virtual exposure ages of 5 and 25 years of exposure to natural corrosion were calculated. The results showed a remarkable increase in the corrosion current of steel bars in samples that had lower concrete cover thickness. The increase in the cover thickness from 20mm to 40 and 65 mm had a significant effect on reducing the corrosion current at the age of 90 days to about 70 of its original value in both cases. At the virtual exposure age of 5 years the reduction percentage in the corrosion current resulted from increasing cover thickness from 20mm to 40 and 65 mm were 43 and 79 respectively.

Effects of metallurgical factors on stress corrosion cracking of Ni-base alloys in high temperature water

International Nuclear Information System (INIS)

Yonezawa, T.; Sasaguri, N.; Onimura, K.

1988-01-01

Nickel-base Alloy 600 is the principal material used for the steam generator tubes of PWRs. Generally, this alloy has been proven to be satisfactory for this application, however when it is subjected to extremely high stress level in PWR primary water, it may suffer from stress corrosion cracking. The authors have systematically studied the effects of test temperature and such metallurgical factors as cold working, chemical composition and heat treatment on the stress corrosion cracking of Alloy 600 in high temperature water, and also on that of Alloy 690 which is a promising material for the tubes and may provide improved crrosion resistance for steam generators. The test materials, the stress corrosion cracking test and the test results are reported. When the test temperature was raise, the stress corrosion cracking of the nickel-base alloys was accelerated. The time of stress corrosion cracking occurrence decreased with increasing applied stress, and it occurred at the stress level higher than the 0.2 % offset proof stress of Alloy 600. In Alloy 690, stress corrosion cracking was not observed at such stress level. Cold worked Alloy 600 showed higher resistance to stress corrosion cracking than the annealed alloy. (Kako, I.)

Effects of Welding Parameters on Strength and Corrosion Behavior of Dissimilar Galvanized Q&P and TRIP Spot Welds

Directory of Open Access Journals (Sweden)

Pasquale Russo Spena

2017-12-01

Full Text Available This study investigates the effects of the main welding parameters on mechanical strength and corrosion behavior of galvanized quenching and partitioning and transformation induced plasticity spot welds, which are proposed to assemble advanced structural car elements for the automotive industry. Steel sheets have been welded with different current, clamping force, and welding time settings. The quality of the spot welds has been assessed through lap-shear and salt spray corrosion tests, also evaluating the effects of metal expulsion on strength and corrosion resistance of the joints. An energy dispersive spectrometry elemental mapping has been used to assess the damage of the galvanized zinc coating and the nature of the corrosive products. Welding current and time have the strongest influence on the shear strength of the spot welds, whereas clamping force is of minor importance. However, clamping force has the primary effect on avoiding expulsion of molten metal from the nugget during the joining process. Furthermore, clamping force has a beneficial influence on the corrosion resistance because it mainly hinders the permeation of the corrosive environment towards the spot welds. Although the welded samples can exhibit high shear strength also when a metal expulsion occurs, this phenomenon should be avoided because it enhances the damage and vaporization of the protective zinc coating.

Corrosion-Resistant High-Entropy Alloys: A Review

Directory of Open Access Journals (Sweden)

Yunzhu Shi

2017-02-01

Full Text Available Corrosion destroys more than three percent of the world’s gross domestic product. Therefore, the design of highly corrosion-resistant materials is urgently needed. By breaking the classical alloy-design philosophy, high-entropy alloys (HEAs possess unique microstructures, which are solid solutions with random arrangements of multiple elements. The particular locally-disordered chemical environment is expected to lead to unique corrosion-resistant properties. In this review, the studies of the corrosion-resistant HEAs during the last decade are summarized. The corrosion-resistant properties of HEAs in various aqueous environments and the corrosion behavior of HEA coatings are presented. The effects of environments, alloying elements, and processing methods on the corrosion resistance are analyzed in detail. Furthermore, the possible directions of future work regarding the corrosion behavior of HEAs are suggested.

A Multifunctional Coating for Autonomous Corrosion Control

Science.gov (United States)

Calle, Luz M.; Li, Wenyan; Buhrow, Jerry W.; Jolley, Scott t.

2011-01-01

Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it. The multi-functionality of the coating is based on microencapsulation technology specifically designed for corrosion control applications. This design has, in addition to all the advantages of existing microcapsulation designs, the corrosion controlled release function that triggers the delivery of corrosion indicators and inhibitors on demand, only when and where needed. Microencapsulation of self-healing agents for autonomous repair of mechanical damage to the coating is also being pursued. Corrosion indicators, corrosion inhibitors, as well as self-healing agents, have been encapsulated and dispersed into several paint systems to test the corrosion detection, inhibition, and self-healing properties of the coating. Key words: Corrosion, coating, autonomous corrosion control, corrosion indication, corrosion inhibition, self-healing coating, smart coating, multifunctional coating, microencapsulation.

Corrosion and Wear Analysis in Marine Transport Constructions

OpenAIRE

Urbahs, A; Savkovs, K; Rijkuris, G; Andrejeva, D

2018-01-01

Corrosion is one of the most common naturally occurring processes studied by thermodynamics, which includes oxidation process, metal disruption, and its chemical and electrochemical effects under environmental influence. Corrosion of metal and equipment accounts for a considerable proportion of total corrosion losses, thus providing the impetus for further investigation and developments related to corrosion protection in order to provide transport systems and industry with corrosion preventiv...

Effect of N-Terminal Acylation on the Activity of Myostatin Inhibitory Peptides.

Science.gov (United States)

Takayama, Kentaro; Nakamura, Akari; Rentier, Cédric; Mino, Yusaku; Asari, Tomo; Saga, Yusuke; Taguchi, Akihiro; Yakushiji, Fumika; Hayashi, Yoshio

2016-04-19

Inhibition of myostatin, which negatively regulates skeletal muscle growth, is a promising strategy for the treatment of muscle atrophic disorders, such as muscular dystrophy, cachexia and sarcopenia. Recently, we identified peptide A (H-WRQNTRYSRIEAIKIQILSKLRL-NH2 ), the 23-amino-acid minimum myostatin inhibitory peptide derived from mouse myostatin prodomain, and highlighted the importance of its N-terminal tryptophan residue for the effective inhibition. In this study, we synthesized a series of acylated peptide derivatives focused on the tryptophan residue to develop potent myostatin inhibitors. As a result of the investigation, a more potent derivative of peptide A was successfully identified in which the N-terminal tryptophan residue is replaced with a 2-naphthyloxyacetyl moiety to give an inhibitory peptide three times (1.19±0.11 μm) more potent than parent peptide A (3.53±0.25 μm). This peptide could prove useful as a new starting point for the development of improved inhibitory peptides. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Corrosion resistant cemented carbide

International Nuclear Information System (INIS)

Hong, J.

1990-01-01

This paper describes a corrosion resistant cemented carbide composite. It comprises: a granular tungsten carbide phase, a semi-continuous solid solution carbide phase extending closely adjacent at least a portion of the grains of tungsten carbide for enhancing corrosion resistance, and a substantially continuous metal binder phase. The cemented carbide composite consisting essentially of an effective amount of an anti-corrosion additive, from about 4 to about 16 percent by weight metal binder phase, and with the remaining portion being from about 84 to about 96 percent by weight metal carbide wherein the metal carbide consists essentially of from about 4 to about 30 percent by weight of a transition metal carbide or mixtures thereof selected from Group IVB and of the Periodic Table of Elements and from about 70 to about 96 percent tungsten carbide. The metal binder phase consists essentially of nickel and from about 10 to about 25 percent by weight chromium, the effective amount of an anti-corrosion additive being selected from the group consisting essentially of copper, silver, tine and combinations thereof

Functionalizable Sol-Gel Silica Coatings for Corrosion Mitigation

Science.gov (United States)