Effect of sodium molybdate and sodium tungstate in concrete rebar corrosion

2019 ◽  
Vol 66 (3) ◽  
pp. 253-263 ◽  
Author(s):  
Altaf Ahmad ◽  
Ranveer Kumar ◽  
Anil Kumar
Keyword(s):  
Sodium Tungstate ◽  
Sodium Molybdate ◽  
Corrosion Current ◽  
Open Circuit ◽  
Simple Method ◽  
Efficient Inhibitor ◽  
Content Type ◽  
Adverse Conditions ◽  
Cent Sodium ◽  
Rebar Corrosion

Purpose This paper aims to identify an inhibitor to protect rebar corrosion in concrete. Design/methodology/approach The authors use the simple method of polarization and calculate the change in open-circuit potential and corrosion current density. Findings Sodium molybdate is an efficient inhibitor compared with sodium tungstate for rebar corrosion in concrete. Research limitations/implications This paper has limitation of 0.0001 M concentration of inhibitors for 400 days of exposure in 3.5 per cent sodium chloride solution. Originality/value The research focused on the concentration of both inhibitors in the range from 0.1 to 0.0001 M, which resulted in greater structural protection from corrosion in adverse conditions, such as coastal areas.

Prediction of residual flexural strength of corroded reinforced concrete beams

2017 ◽  
Vol 64 (1) ◽  
pp. 69-74 ◽  
Author(s):  
Shamsad Ahmad
Keyword(s):  
Reinforced Concrete ◽  
Flexural Strength ◽  
Current Density ◽  
Empirical Model ◽  
Corrosion Current Density ◽  
Concrete Beams ◽  
Corrosion Current ◽  
Reinforced Concrete Beams ◽  
Content Type ◽  
Rebar Corrosion

Purpose This study aims to make an effort to develop a model to predict the residual flexural strength of reinforced concrete beams subjected to reinforcement corrosion. Design/methodology/approach For generating the required data to develop the model, a set of experimental variables was considered that included corrosion current density, corrosion duration, rebar diameter and thickness of concrete cover. A total of 28 sets of reinforced concrete beams of size 150 × 150 × 1,100 mm were cast, of which 4 sets of un-corroded beams were tested in four-point bend test as control beams and the remaining 24 sets of beams were subjected to accelerated rebar corrosion inducing different levels of corrosion current densities for different durations. Corroded beams were also tested in flexure, and test results of un-corroded and corroded beams were utilized to obtain an empirical model for estimating the residual flexural strength of beams for given corrosion current density, corrosion duration and diameter of the rebars. Findings Comparison of the residual flexural strengths measured experimentally for a set of corroded beams, reported in literature, with that predicted using the model proposed in this study indicates that the proposed model has a reasonably good accuracy. Originality/value The empirical model obtained under this work can be used as a simple tool to predict residual flexural strength of corroded beams using the input data that include rebar corrosion rate, corrosion duration after initiation and diameter of rebars.

scholarly journals Rebar corrosion in mortars with high limestone filler content

2013 ◽  
Vol 60 (1) ◽  
pp. 3-13 ◽  
Author(s):  
O.R. Batic ◽  
J.D. Sota ◽  
J.L. Fernández ◽  
N. Bellotti ◽  
R. Romagnoli
Keyword(s):  
Tap Water ◽  
Protective Layer ◽  
Corrosion Current ◽  
High Water ◽  
Passive Layer ◽  
Limestone Filler ◽  
Content Type ◽  
Corrosion Rates ◽  
Lime Water ◽  
Rebar Corrosion

PurposeThis research aims to study the influence of limestone filler on rebar corrosion.Design/methodology/approachMortar samples containing 35% calcareous filler and with a rebar inserted in the axis, were cast. Specimens were cured at the open air and during 28 days in lime water. After curing, they were submerged in two electrolytes (tap water and 3% NaCl) and corrosion parameters (corrosion potential and corrosion current) were monitored over time by d.c. techniques. Simultaneously, electrochemical noise measurements were carried out. After corrosion tests, rebars were pulled out by lateral compression, and their surface observed by scanning electron microscopy.FindingsIn general, carbonate additions impaired mortar protective properties, especially in the presence of chloride and changed the nature of the protective layer on rebars. The curing process did not introduce significant differences except for mortars with a high water cement ratio cured in lime water for which the beneficial effects of the simultaneous presence of carbonate and lime in the pore solution could be appreciated. The role of carbonate additions is to provide carbonate anions to passivate rebars. This passivation process caused corrosion rates not to be so high. Carbonate anions also deposited on oxide spots which were rendered passive but this process was not uniform. Certain areas on the rebar underwent intense carbonation while others showed increased corrosion rates.Originality/valueThere are not many corrosion studies about the influence of limestone filler on rebars corrosion. Particularly, this paper deals with mortars containing high percentages of carbonate additions. Results showed that the presence of this type of admixture changes the structure of the passive layer and, sometimes, may increase corrosion rates.

Corrosion Behaviour of In Situ AlxNiy Reinforced AA6061 Composite

2021 ◽  
Vol 882 ◽  
pp. 96-103
Author(s):  
A.D. Vishwanatha ◽  
D.M. Shivanna ◽  
Bijayani Panda
Keyword(s):  
Corrosion Potential ◽  
Corrosion Behaviour ◽  
Corrosion Current ◽  
Open Circuit ◽  
Homogeneous Distribution ◽  
Initial Increase ◽  
Weight Percentage ◽  
Aa6061 Alloy ◽  
Ni Addition

In-situ AlxNiy reinforced aluminium matrix composites (AMCs) were produced by stir-casting route by adding 5, 10 and 15 weight percentage (wt.%) of Ni to AA6061 aluminum alloy. The density, porosity, microstructure, hardness and corrosion behaviour of the as-cast AMCs was studied and compared with that of the as-cast AA6061 alloy. The porosity in all the castings was found to be less than 0.1%. Further, the porosity was found to decrease with increase in Ni addition. Optical microscopy studies showed that in-situ formed AlxNiy was distributed along the dendritic arms. The distribution became non-homogeneous and coarse with increase in AlxNiy content. The coarse distribution of AlxNiy in the AA6061 matrix also resulted in the decrease in hardness of the composite, after an initial increase in hardness till 10 wt.% Ni addition. The open circuit potential (OCP) and corrosion potential (Ecorr) of the AMCs with 5, 10 and 15 wt. of % Ni addition was noble than that of the AA6061 alloy. This was understood to be due to the presence of AlxNiy intermetallic which is known to have a noble corrosion potential than the aluminium alloy. However, the corrosion current (icorr) increased while the polarization resistance (Rp) decreased with increase in Ni addition in the AMC. This indicates that the coarse non-homogeneous distribution of in-situ AlxNiy had a detrimental effect on the corrosion performance of the AMCs.

A collaborative application of design thinking and Taguchi approach in restaurant service design for food wellbeing

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
G. Rejikumar ◽  
Asokan-Ajitha Aswathy ◽  
Ajay Jose ◽  
Mathew Sonia
Keyword(s):  
Food Industry ◽  
Design Thinking ◽  
Service Design ◽  
Service Research ◽  
Taguchi Approach ◽  
Simple Method ◽  
Content Type ◽  
Wellbeing Index ◽  
Food Movement ◽  
Practical Implications

PurposeInnovative restaurant service designs impart food wellbeing to diners. This research comprehends customer aspirations and concerns in a restaurant-dining experience to develop a service design that enhances the dining experience using the design thinking approach and evaluates its efficiency using the Taguchi method of robust design.Design/methodology/approachThe sequential incidence technique defines diners' needs, which, followed by brainstorming sessions, helped create multiple service designs with important attributes. Prototype narration, as a scenario, acted as the stimulus for evaluators to respond to the WHO-5 wellbeing index scale. Scenario-based Taguchi experiment with nine foodservice attributes in two levels and the wellbeing score as the response variable helped identify levels of critical factors that develop better FWB.FindingsThe study identified the best combination of factors and their preferred levels to maximize FWB in a restaurant. Food serving hygiene, followed by information about cuisine specification, and food movement in the restaurant, were important to FWB. The experiment revealed that hygiene perceptions are critical to FWB, and service designs have a significant role in it. Consumers prefer detailed information about the ingredients and recipe of the food they eat; being confident that there will be no unacceptable ingredients added to the food inspires their FWB.Research limitations/implicationsTheoretically, this study contributes to the growing body of literature on design thinking and transformative service research, especially in the food industry.Practical implicationsThis paper details a simple method to identify and evaluate important factors that optimize FWB in a restaurant. The proposed methodology will help service designers and technology experts devise settings that consider customer priorities and contribute to their experience.Originality/valueThis study helps to understand the application of design thinking and the Taguchi approach for creating robust service designs that optimize FWB.

scholarly journals From Waste to Valuable Resource: Lignin as a Sustainable Anti-Corrosion Coating

Coatings ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 454 ◽  
Author(s):  
Arman Dastpak ◽  
Kirsi Yliniemi ◽  
Mariana de Oliveira Monteiro ◽  
Sarah Höhn ◽  
Sannakaisa Virtanen ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Steel Corrosion ◽  
Linear Sweep Voltammetry ◽  
Corrosion Current ◽  
Polymer Coatings ◽  
Open Circuit ◽  
Linear Sweep ◽  
Cyclic Potentiodynamic Polarization

In this study, a waste of biorefinery—lignin—is investigated as an anticorrosion coating on stainless steel. Corrosion behavior of two lignin types (hardwood beech and softwood spruce) was studied by electrochemical measurements (linear sweep voltammetry, open circuit potential, potentiostatic polarization, cyclic potentiodynamic polarization, and electrochemical impedance measurements) during exposure to simulated body fluid (SBF) or phosphate buffer (PBS). Results from linear sweep voltammetry of lignin-coated samples, in particular, demonstrated a reduction in corrosion current density between 1 and 3 orders of magnitude cf. blank stainless steel. Furthermore, results from cross cut adhesion tests on lignin-coated samples demonstrated that the best possible adhesion (grade 0) of ISO 2409 standard was achieved for the investigated novel coatings. Such findings suggest that lignin materials could transform the field of organic coatings towards more sustainable alternatives by replacing non-renewable polymer coatings.

Hydrogen failure sensitivity of A516-Gr70 and API 5L-X70 steels in sour environments

2015 ◽  
Vol 62 (5) ◽  
pp. 294-300 ◽  
Author(s):  
H Taheri ◽  
A Dolati ◽  
Behrooz Beidokhti
Keyword(s):  
Oil And Gas ◽  
Corrosion Current ◽  
Technical Committee ◽  
Committee Report ◽  
Three Solutions ◽  
Content Type ◽  
Hydrogen Induced Cracking ◽  
Two Temperatures ◽  
Current Densities ◽  
Api 5L X70 Steel

Purpose – This paper aims to clarify the corrosion behavior of two famous structural steels in sour environment. These steels have a vast application in oil and gas industries. The study aims to find the effect of different concentrations of sour solution on the origin of crack in these steels. Design/methodology/approach – After preparation of specimens, different sour solutions were made using the synthetic brine (according to National Association of Corrosion Engineers [NACE], Technical Committee Report 1D182) and various amounts of Na2S.9H2O and CH3COOH. The polarization test was done by Potansiostat apparatus model Zahner-IM6 at two temperatures, 25°C and 50°C. The corrosion current densities were obtained from the polarization curves. Finally, the corrosion products and hydrogen-induced cracking (HIC) were investigated by Tescan Vega II XMU scanning electron microscope (SEM) linked to a Rontec energy-dispersive X-ray spectroscopy (EDS) system. Findings – API 5L-X70 steel showed smaller corrosion current values than A516-Gr70 steel. The HIC cracks propagated parallel to the surface of A516-Gr70 steel in three solutions and confirmed the inappropriateness of this steel for sour environment applications. Originality/value – This paper studies the effect of sour environment on the behavior of two famous industrial steels at two temperatures by new method.

Bilateral open-door cervical expansive laminoplasty with hydroxyapatite spacers and titanium screws

2002 ◽  
Vol 96 (1) ◽  
pp. 22-28 ◽  
Author(s):  
Masakazu Takayasu ◽  
Teruhide Takagi ◽  
Toshihisa Nishizawa ◽  
Koji Osuka ◽  
Takehiko Nakajima ◽  
...  
Keyword(s):  
Screw Fixation ◽  
Cervical Spinal Cord ◽  
Intraoperative Complications ◽  
Fixation Strength ◽  
Open Door ◽  
Quick Method ◽  
Simple Method ◽  
Content Type ◽  
Titanium Screws ◽  
Fine Print

Object. The authors report a simple method for bilateral open-door cervical expansive laminoplasty in which hydroxyapatite (HA) spacers are secured by titanium screws. A biomechanical study was also conducted to confirm the strength of the screw fixation. Methods. A unilateral posterior approach was used to allow preservation of the posterior supporting elements (the posterior tension band) until the laminae were cut at the base. A bilateral open-door expansive laminotomy was then performed in standard fashion. Appropriate-sized HA spacers were selected, held with a specially designed holder, and placed between the split laminae. The screw holes were made in the laminae along the direction of the screw holes in the spacer, and two screws were inserted ventrolaterally to the laminae, resulting in instantaneous fixation. This procedure was performed in 15 patients; clinical results were successful, and there were no significant intraoperative complications. Follow-up radiological studies revealed no evidence of displacement of the spacers or screw backout. The screw artifacts observed on magnetic resonance imaging were minimal, allowing evaluation of the cervical spinal cord. The sagittal alignment of the cervical spine was well preserved. In the biomechanical studies the authors found that the screw fixation was of satisfactory strength, compared with other methods of fixation. Conclusions. Bilateral open-door cervical expansive laminoplasty in which HA spacers are secured by titanium screws is a simple and quick method that yields sufficient fixation strength.

scholarly journals Corrosion investigations of Al-Si casting alloys in 0.6 M NaCl solution

2021 ◽  
Vol 41 (3) ◽  
Author(s):  
Sunčana Smokvina Hanza ◽  
Ladislav Vrsalović ◽  
Lovro Štic ◽  
Lovro Liverić
Keyword(s):  
Potentiodynamic Polarization ◽  
Electrochemical Behavior ◽  
Die Casting ◽  
Electrochemical Corrosion ◽  
Microstructural Characterization ◽  
Casting Process ◽  
Corrosion Current ◽  
Optical Microscope ◽  
Open Circuit ◽  
Polarization Measurements

This paper presents results of the corrosion investigations of specimens made from finished parts for the automotive industry, produced by high-pressure die casting and gravity die casting process of six Al-Si alloys (40000 series). Open circuit potential and potentiodynamic polarization measurements have been performed using a potentiostat with three-electrode set-up in 0.6 M NaCl naturally aerated solution. Microstructural characterization before and after electrochemical investigations has been carried out with optical microscope to establish the connection between microstructure and corrosion parameters of investigated alloys and to analyze and record surface changes of each sample due to electrochemical corrosion. All alloys show good corrosion resistance, which manifests with low values of corrosion rates, calculated from the corrosion current densities obtained from potentiodynamic polarization measurements. Differences in electrochemical behavior appear due to the distinctions in their chemical composition and microstructure. The type of casting process does not affect electrochemical behavior of Al-Si alloys.

scholarly journals Short and open circuit faults study in the PV system inverter

2021 ◽  
Vol 12 (3) ◽  
pp. 1764
Author(s):  
Mohammed Bouzidi ◽  
Abdelkader Harrouz ◽  
Tadj Mohammed ◽  
Smail Mansouri
Keyword(s):  
Short Circuit ◽  
Electric Utility ◽  
Open Circuit ◽  
Photovoltaic System ◽  
Pv System ◽  
Simple Method ◽  
Pv Systems ◽  
Pv Array ◽  
Main Component ◽  
Types Of Faults

<p>The inverter is the principal part of the photovoltaic (PV) systems that assures the direct current/alternating current (DC/AC) conversion (PV array is connected directly to an inverter that converts the DC energy produced by the PV array into AC energy that is directly connected to the electric utility). In this paper, we present a simple method for detecting faults that occurred during the operation of the inverter. These types of faults or faults affect the efficiency and cost-effectiveness of the photovoltaic system, especially the inverter, which is the main component responsible for the conversion. Hence, we have shown first the faults obtained in the case of the short circuit. Second, the open circuit failure is studied. The results demonstrate the efficacy of the proposed method. Good monitoring and detection of faults in the inverter can increase the system's reliability and decrease the undesirable faults that appeared in the PV system. The system behavior is tested under variable parameters and conditions using MATLAB/Simulink.</p>

scholarly journals Corrosion behaviour of an AlZnSnSrGa alloy in aqueous solutions of NaCl and Na2So4

2000 ◽  
Vol 65 (1) ◽  
pp. 73-81
Author(s):  
P. Zivkovic ◽  
J. Pjescic ◽  
S. Mentus
Keyword(s):  
Corrosion Rate ◽  
Aqueous Solutions ◽  
Polarization Resistance ◽  
Corrosion Current Density ◽  
Corrosion Behaviour ◽  
Base Material ◽  
Corrosion Current ◽  
Open Circuit ◽  
Base Metals ◽  
Aluminium Plant

The alloy composed of Al(95.53%), Zn(2.85%), Sn(0.515%), Ga(0.1%) and Sr(0.009%), with the weight percents in the parentheses, was prepared by melting, using Al(99.84%), a product of the Aluminium Plant-Podgorica, as the base material. The corrosion behaviour of this alloy was tested in relation to the behaviour of the base metals, by both open curcuit potential and polarization resistance methods, in aqueous solutions of both NaCl and Na2SO4, the concentration of which varied within the range 0.00051 - 0.51 mol dm -3. Over the whole salt concentration ranges, the corrosion parameters indicate that the corrosion rate of the alloy is significantly higher than the rate of the base material. For instance, for the concentration range 0.00051 - 0.51 mol dm -3 , the stationary open circuit potentials, related to SCE, in NaCl solutions were - 1.200 to - 1.460 V for the alloy and - 0.693 to - 0.920 V for Al, while in Na2SO4 solutions, the stationary open circuit potentials were - 1.190 to - 1.465V for the alloy and - 0.780 to - 0.860V for Al. At the same time, the corrosion current density in NaCl solutions varied within 11-89 mA cm -2 for the alloy and 0.35 - 0.80 for Al, while in Na2SO4 solutions it amounted to 5.7.52 mA cm -2 for the alloy and 0.28 - 0.88 mA cm -2 for Al.

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