scholarly journals Corrosion Monitoring of Galvanized Steel in Simulated Wet-Dry Cyclic Condition in 0.05 M NaCl Solution

1970 ◽  
Vol 8 (8) ◽  
pp. 76-80 ◽  
Author(s):  
AP Yadav
Keyword(s):  
Corrosion Rate ◽  
Corrosion Potential ◽  
Early Stage ◽  
Ac Impedance ◽  
Galvanized Steel ◽  
Corrosion Mechanism ◽  
Corrosion Monitoring ◽  
Cyclic Condition ◽  
Impedance Technique ◽  
Time Of Wetness

The corrosion monitoring of galvanized steel in 1 h wet and 7 h dry cyclic condition in 0.05 M NaCl has been carried out using AC impedance technique. During the wet-dry cycles, the polarization resistance, Rp, and solution resistance, Rs, were continuously monitored. The instantaneous corrosion rate of the coating was estimated from the obtained Rp-1 and time of wetness (TOW) was determined from the Rs values. The corrosion potential, Ecorr, was measured twice a day during the immersion period of wet-dry cycle. The corrosion was accelerated by the wet-dry cycles in the early stage followed by a decrease in the final stage of wet-dry cycle. The corrosion potential shifted to more negative direction for the first 8 cycles due to dissolution of air formed oxide. A gradual shift in the corrosion potential with the progress of corrosion in the later stage of the wet-dry cycle was observed due to deposition of corrosion products. The corrosion mechanism of galvanized steel is discussed based on the results of corrosion monitoring and corrosion potential variation. Key words: Atmospheric corrosion; Galvanized steel; AC Impedance; Corrosion rate. DOI: 10.3126/sw.v8i8.3855 Scientific World Vol.8(8) 2010 pp.76-80

Multifunctional Sensors for Monitoring Corrosion of Mortar Specimens

2013 ◽  
Vol 753-755 ◽  
pp. 2107-2112
Author(s):  
Chung Kuk Jin ◽  
Jin A Jeong
Keyword(s):  
Corrosion Rate ◽  
Corrosion Potential ◽  
Experimental Tests ◽  
Galvanic Cell ◽  
Corrosion Monitoring ◽  
Testing Conditions ◽  
Cell Current ◽  
Multifunctional Sensor

This study examines the use of multifunctional sensors for corrosion monitoring in various conditions. Experimental tests were carried out on mortar specimens to verify the applicability of a multifunctional sensor. Single-functional sensors measuring the potential and current were also used for comparison. The factors measured were the corrosion potential, galvanic cell current, resistivity, and corrosion rate. The results show that at least under the present testing conditions, the multifunctional sensor is quite useful for detecting the corrosion severity.

Unique Autoclave Stress Induced Failure Mechanism

2005 ◽  
Author(s):  
John Butchko ◽  
Bruce T. Gillette
Keyword(s):  
Corrosion Rate ◽  
Grain Boundary ◽  
Failure Analysis ◽  
Failure Mechanism ◽  
Metal Corrosion ◽  
Corrosion Mechanism ◽  
Reliability Testing ◽  
Process Change ◽  
Transistor Reliability ◽  
Pass Through

Abstract Autoclave Stress failures were encountered at the 96 hour read during transistor reliability testing. A unique metal corrosion mechanism was found during the failure analysis, which was creating a contamination path to the drain source junction, resulting in high Idss and Igss leakage. The Al(Si) top metal was oxidizing along the grain boundaries at a faster rate than at the surface. There was subsurface blistering of the Al(Si), along with the grain boundary corrosion. This blistering was creating a contamination path from the package to the Si surface. Several variations in the metal stack were evaluated to better understand the cause of the failures and to provide a process solution. The prevention of intergranular metal corrosion and subsurface blistering during autoclave testing required a materials change from Al(Si) to Al(Si)(Cu). This change resulted in a reduced corrosion rate and consequently prevented Si contamination due to blistering. The process change resulted in a successful pass through the autoclave testing.

Water treatment to reduce internal corrosion in the drinking water distribution system in Oslo

2001 ◽  
Vol 1 (3) ◽  
pp. 91-96 ◽  
Author(s):  
L.J. Hem ◽  
E.A. Vik ◽  
A. Bjørnson-Langen
Keyword(s):  
Water Treatment ◽  
Corrosion Rate ◽  
Distribution System ◽  
Water Distribution ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Corrosion Monitoring ◽  
Copper Corrosion ◽  
Iron Corrosion ◽  
Internal Corrosion

In 1995 the new Skullerud water treatment plant was put into operation. The new water treatment includes colour removal and corrosion control with an increase of pH, alkalinity and calcium concentration in addition to the old treatment, which included straining and chlorination only. Comparative measurements of internal corrosion were conducted before and after the installation of the new treatment plant. The effect of the new water treatment on the internal corrosion was approximately a 20% reduction in iron corrosion and a 70% reduction in copper corrosion. The heavy metals content in standing water was reduced by approximately 90%. A separate internal corrosion monitoring programme was conducted, studying the effects of other water qualities on the internal corrosion rate. Corrosion coupons were exposed to the different water qualities for nine months. The results showed that the best protection of iron was achieved with water supersaturated with calcium carbonate. Neither a high content of free carbon dioxide or the use of the corrosion inhibitor sodium silicate significantly reduced the iron corrosion rate compared to the present treated water quality. The copper corrosion rate was mainly related to the pH in the water.

scholarly journals Preparation and piezoresistivity of carbon nanotube-coated sand reinforced cement mortar

2020 ◽  
Vol 9 (1) ◽  
pp. 1445-1455
Author(s):  
Song Gao ◽  
Jianlin Luo ◽  
Jigang Zhang ◽  
Fei Teng ◽  
Chao Liu ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Cement Mortar ◽  
Aqueous Suspension ◽  
Ac Impedance ◽  
Stress Sensitivity ◽  
Multiwall Carbon Nanotube ◽  
Impedance Technique ◽  
Reinforced Cement ◽  
Coated Sand ◽  
Mechanical Strengths

Abstract Water and sand were used as the medium of multiwall carbon nanotube (MCNT) and prepared MCNT aqueous suspension and MCNT suspension-coated sand, respectively; afterwards, they were introduced into cement mortar (MNT/CM, MNTSM), respectively. Next, mechanical strengths and piezoresistive properties (DC resistivities (ρ v), AC impedances (Z r)) under cyclic loadings (σ c) of two types of MNT/CM and MNTSM nanocomposites were investigated to explore the intrinsic and self-sensing behaviors. Results reveal that MCNT can be evenly and well-coated on sand, which favors to achieve its intrinsic self-sensing property. Although the fraction changes in ρ v and Z r under the same σ c of MNTSM are both lower than those of MNT/CM, the stress sensitivity of MNTSM is only −1.16%/MPa (DC resistivity), −1.55%/MPa (AC impedance); its sensing linearity and stability (2.53, 2.45%; 2.73, 2.67%) are superior to those of MNT/CM (4.94, 2.57%; 3.78, 2.96%). Piezoresistivity using AC impedance technique is helpful to acquire balanced sensing sensitivity and stability while applied as intrinsic sensors in infrastructure.

Effect of Sn, Zn and Bi Addition on Corrosion Characteristics of Magnesium Alloys Sintered by Spark Plasma Sintering

2018 ◽  
Vol 941 ◽  
pp. 1760-1765
Author(s):  
Satoshi Sunada ◽  
Yoshitaka Matsui ◽  
Syogo Takeuchi ◽  
Taku Iwaoka ◽  
Koichi Sato ◽  
...  
Keyword(s):  
Melting Point ◽  
Corrosion Rate ◽  
Spark Plasma Sintering ◽  
Magnesium Alloys ◽  
Electrochemical Method ◽  
Corrosion Potential ◽  
Elemental Mapping ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Metallic Compounds

Sintered magnesium alloys, which were fabricated by Spark Plasma Sintering (SPS) method, were examined to study corrosion characteristics by electrochemical method, XRD and EPMA. The binary mixtures alloys of a low-melting-point metal powder (Sn, Bi, Sb) of1.0 vol.% and the pure magnesium powder were prepared. In the Mg-1.0vol.%Bi and Mg-1.0vol.%Sn, Mg3Bi2 and Mg2Sn precipitates was recognized by XRD, respectively. In addition, formation of oxide along powder particle boundaries was observed by EPMA elemental mapping in all specimens. In the case of Mg-1.0vol.%Zn, precipitation of metallic compounds was not recognized by these experiments. According to the results of polarization curve measurements, the Mg-1.0vol.%Bi shows highest corrosion potential. However, corrosion rate which was estimated by Tafel method is relatively larger than other alloys due to Mg3Bi2 precipitation. This result suggests that Mg3Bi2 acts as cathode site. The Mg-1.0vol.%Sn shows superior corrosion rale in these alloys.

A study of polymer-modified mortars by the AC impedance technique

2002 ◽  
Vol 32 (6) ◽  
pp. 979-982 ◽  
Author(s):  
Shiyun Zhong ◽  
Meilun Shi ◽  
Zhiyuan Chen
Keyword(s):  
Ac Impedance ◽  
Impedance Technique

scholarly journals Dissolution of chromium in sulfuric acid

2002 ◽  
Vol 67 (11) ◽  
pp. 777-782 ◽  
Author(s):  
Dragutin Drazic ◽  
Jovan Popic
Keyword(s):  
Corrosion Rate ◽  
Room Temperature ◽  
Corrosion Potential ◽  
Analytical Data ◽  
Electrochemical Corrosion ◽  
Spectrophotometric Analysis ◽  
Weight Loss Method ◽  
Loss Method ◽  
Anomalous Dissolution

By combining electrochemical corrosion rate measurements and spectrophotometric analysis of the electrolyte it was shown that at room temperature chromium dissolves in deaerated 0.1M Na2SO4 + H2SO4 (pH1) solution as Cr(II) and Cr(III) ions in he ratio Cr(II):Cr(III)?7:1. This process was stable over 4h without any detectable change. The total corrosion rate of chromium calculated from the analytical data is about 12 times higher, than that determined electrochemically by cathodic Tafel line extrapolation to the corrosion potential. This finding was confirmed by applying the weight-loss method for the determination of the corrosion rate. This enormous difference between these experimentally determined corrosion rates can be explained by the rather fast, "anomalous" dissolution process proposed by Kolotyrkin and coworkers (chemical reaction of Cr with H2O molecules) occurring simultaneously with the electrochemical corrosion process.

Effect of nickel content in the corrosion process of TiC/Cu-Ni composites immersed in synthetic seawater

MRS Advances ◽  
2019 ◽  
Vol 4 (63) ◽  
pp. 3475-3484
Author(s):  
Miguel A. Téllez-Villaseñor ◽  
Carlos A. León Patino ◽  
Ricardo Galván Martínez ◽  
Ena A. Aguilar Reyes
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Nickel Content ◽  
Corrosion Mechanism ◽  
Composite Surface ◽  
Synthetic Seawater ◽  
Ni Content ◽  
The Matrix ◽  
Static Conditions

ABSTRACTThe work presents an electrochemical study of the corrosion behaviour of two TiC/Cu-Ni metal matrix composites with a content of 10 and 20 wt.% Ni immersed in synthetic seawater. The composites were synthesized by a capillary infiltration technique, obtaining dense materials TiC/Cu-10Ni and TiC/Cu-20 Ni with a residual porosity of 1.8 and 1.7%, respectively. The corrosion rate (CR) was evaluated from the techniques of polarization curves (PC), linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). Electrochemical measurements were carried out under static conditions, ambient temperature and atmospheric pressure at 24 hours exposure in the electrolytic medium. The corrosion rate is affected by the Ni content in the matrix, with less corrosion in the composite with a higher Ni content. The higher content of Ni in the Cu-Ni alloy provides higher passivation and stability to the corrosion products film that are absorbed on the composite surface. Microscopic examination (SEM) showed a characteristic morphology of a corrosion mechanism of the localized type (pits and crevices) generated by a differential aeration, where the TiC/Cu-10Ni composite showed greater degradation.

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