Experimental Study and Mechanism on the Corrosion of Stressed Reinforcement Bars

2020 ◽  
Vol 837 ◽  
pp. 109-115
Author(s):  
Ding Zeng ◽  
Hong Yu Lu ◽  
Bao Hong Hao ◽  
Hao Zheng Yu ◽  
Yu Mi
Keyword(s):  
Experimental Study ◽  
Corrosion Rate ◽  
Tensile Stress ◽  
Corrosion Current ◽  
Corrosion Mechanism ◽  
Tension Stress ◽  
Metallographic Examination ◽  
Corrosion Condition ◽  
Tensile Stresses ◽  
Reinforcement Bar

In order to understand the influence of the tensile stress on the corrosion of reinforcement bars in civil engineering, the reinforcement bars specimens were put into the liquid corrosion tank made of hydrochloric acid and distilled water by applying the tension stress on the reinforcing frame to carry out rapid corrosion. The corrosion of reinforcement bars under different tension stresses was tested by using electrochemical polarization method. The metallographic examination of reinforcement bars was carried out through the section of reinforcement bars. The corrosion mechanism of the stressed reinforcement bar was tested and analyzed. It can be known from the experimental study: First in the same corrosion condition, the larger the tensile stress is, the faster the corrosion of steel bar will be; Second corrosion current density or corrosion rate are index for evaluating corrosion rate of reinforcement bars with different tensile stresses. Corrosion potential can not be used as an index for evaluating corrosion rate of reinforcement bars with different tensile stresses; Third intercrystalline corrosion occurs inside the reinforcement bar due to micro-defects after rolling and moulding, which directly affects the mechanical properties of reinforcement bar.

Model Research of Concrete Reinforcement Corrosion Mechanism and Corrosion Rate under the Corrosion of Chloride Ion

2013 ◽  
Vol 470 ◽  
pp. 847-853 ◽  
Author(s):  
Bao Hong Hao ◽  
Ding Zeng ◽  
Hang Li ◽  
Yu Xue Cheng ◽  
Yan Tao Dou
Keyword(s):  
Weight Loss ◽  
Corrosion Rate ◽  
Corrosion Current ◽  
Quantitative Model ◽  
Corrosion Mechanism ◽  
Loss Ratio ◽  
Reinforcement Corrosion ◽  
Chloride Environment ◽  
Weight Loss Ratio ◽  
Concrete Reinforcement

This paper researches law of reinforcement corrosion under chloride environment based on method the simulated accelerated test. Test the self-corrosion current density and electrode potential quantitative index of concrete reinforcement under chloride environment and establish quantitative model of corrosion time and reinforcement corrosion quantity by means of advanced linear polarization method and electrochemical testing method. Corroded reinforcement weight loss ratio under chloride environment is detected in physical way, combined with reinforcement corrosion layer microstructure and composition characteristics detected by scanning electron microscope. Both of the above deeply reveals corrosion mechanism and corrosion characteristics of the reinforcement. Corrosion rate theoretical model and statistical model have been revised. The research results prove that reinforcement corrosion rate has increased by an average of 4-5 times under chloride environment, weight loss ratio has increased by 15% compared with that under no-chloride environment, and due to chlorine’s effect, partial and uneven corrosion rust layer appears on surface of the reinforcement, which will be the direct cause of inducing accelerating corrosion of reinforcement at the later stage.

AC Corrosion: Mechanism and Proposed Model

2004 ◽  
Author(s):  
Mark Yunovich ◽  
Neil G. Thompson
Keyword(s):  
Corrosion Rate ◽  
Cathodic Polarization ◽  
Research Work ◽  
Metal Loss ◽  
Corrosion Mechanism ◽  
Corrosion Condition ◽  
Diffusion Controlled ◽  
Proposed Model ◽  
Ac Current ◽  
Resistive Component

Corrosion caused by the discharge of 60 Hz AC current from a pipeline in a high voltage AC (HVAC) corridor has been discussed and studied over the past 20 or more years. More recent studies in Europe have specifically addressed these corrosion issues following several failures attributed to the presence of AC discharge from the pipeline. Very few corrosion failures in North America have been specifically attributed to what is termed AC-enhanced corrosion (ACEC). One missing area of research is well-controlled laboratory experiments in soil environments. This study proposed a mechanism of ACEC that is based on conventional electrochemistry using the same equivalent analog circuits used to discuss other corrosion processes. It was shown that only a small amount of the 60 Hz AC current discharge passes through the resistive component of the equivalent circuit, which results in corrosion (metal loss) reactions. The AC current passing through this resistive component produces both anodic and cathodic polarization shift (sine wave dependent) resulting in a net increase in the average corrosion rate as compared to the free-corrosion rate. The proposed model for ACEC does not invoke any new electrochemical concepts and is based on the conventional (DC) treatment of the corrosion processes; the model excludes treatment of cases with imposed cathodic protection current. The amount of ACEC is dependent on the magnitude of AC current that passes through the resistive component of the parallel resistive-capacitive electrochemical interface. ACEC is characterized by the rapid formation of a diffusion controlled (Warburg) process for corrosion in soils. Although diffusion controlled, the overall impedance decreases as the total AC current increases. The model suggests that AC currents (60Hz) cause anodic (positive) polarization shifts during the positive portion of the imposed AC sinewave along with cathodic polarization shifts in the negative portion of the AC sinewave; the net result is an increase in the average oxidation (metal loss) current as compared to the free-corrosion condition. The proposed model for the ACEC mechanism showed excellent correlation with the experimental results. The research work was made possible by the funding from PRCInternational.

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.

Corrosion Behavior of X70 Pipeline Steel and Corrosion Rate Prediction Under the Combination of Corrosive Medium and Applied Pressure

2017 ◽  
Author(s):  
Kaikai Li ◽  
Wei Wu ◽  
Guangxu Cheng ◽  
Yun Li ◽  
Haijun Hu ◽  
...  
Keyword(s):  
Natural Gas ◽  
Corrosion Rate ◽  
Tensile Stress ◽  
Partial Pressure ◽  
Corrosion Behavior ◽  
Pipeline Steel ◽  
Applied Pressure ◽  
Chloride Concentration ◽  
X70 Pipeline Steel ◽  
Co2 Partial Pressure

Natural gas transmission pipeline is prone to internal corrosion due to the combination of corrosive impurities in the pipe (such as CO2, H2S and chlorides) and applied pressure of the pipeline, which seriously affects the safe operation of the pipeline. In this work, the corrosion behavior of a typical X70 pipeline steel was investigated by using potentiodynamic polarization and electrochemical impendence spectroscopy (EIS). The polarization and EIS data under different CO2 partial pressures (0–1 atm), H2S concentrations (0–150 ppm), chloride concentrations (0–3.5 wt%) and tensile stress (0–400 MPa) were obtained. The results show that corrosion rate increases with the increase of CO2 partial pressure and chloride concentration, respectively, while first increases and then decreases with the increase H2S concentrations. The corrosion rate is less affected by elastic tensile stress. In addition, a quantitative prediction model for corrosion rate of natural gas pipeline based on adaptive neuro-fuzzy inference system (ANFIS) was established by fitting the experimental data which maps the relationship between the key influencing factors (i.e. CO2 partial pressure, H2S concentration, chloride concentration and tensile stress) and the corrosion rate. The prediction results show that the relative percentage errors of the predicted and experimental values are relatively small. The prediction accuracy of the model satisfies the engineering application requirement.

The Influence of Different Subbase Materials on the Crack of Cement Stabilized Macadam Base during Construction

2012 ◽  
Vol 591-593 ◽  
pp. 955-959 ◽  
Author(s):  
Xiao Feng Liao ◽  
Fen Xiao ◽  
Zhong Da Chen ◽  
Lei Xing
Keyword(s):  
Tensile Stress ◽  
Shrinkage Strain ◽  
Mechanical Parameters ◽  
Tensile Stresses ◽  
Shrinkage Crack ◽  
Dry Shrinkage ◽  
Base Course ◽  
Shrinkage Coefficient ◽  
Crack Space

According to actual axle load data and the measured mechanical parameters of cement stabilized macadam material with different cement dosages, the bottom tensile stresses of different subbase structures are calculated and the results show that: to graded gravel subbase, the weight of construction vehicle is inadvisable to be more than 35t and the cement dosage of base course shall be more than 3.0%; and, the maximum bottom tensile stress of graded gravel subbase shall be much more than that of lime-flyash soil subbase. According to the measured dry shrinkage strain and dry shrinkage coefficient, the dry shrinkage crack space of base course is analyzed and the results show that: under the same cement dosage, the crack space of the base course with graded gravel subbase is smaller than that of lime-flyash soil subbase; with the increase of cement dosage, the crack space of base course increase first and then decrease, and when the cement dosage is 3.5%, the dry shrinkage strain and dry shrinkage coefficient is minimum and the crack space of base course is maximum.

Electrochemical and Salt Spray Corrosion Behavior of Copper Alloy Contact Wires in Chloride Solution

2014 ◽  
Vol 789 ◽  
pp. 622-626
Author(s):  
Peng Chao Zhang ◽  
Jian Zhang ◽  
Jin Chuan Jie ◽  
Yuan Gao ◽  
Yong Dong ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Corrosion Test ◽  
Chloride Solution ◽  
Copper Alloys ◽  
Salt Spray ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Corrosion Mechanism ◽  
Salt Spray Corrosion ◽  
Surface Morphologies

The effect of different alloying elements on corrosion behavior of copper alloys was investigated using electrochemical corrosion and salt spray corrosion test in NaCl solution. Cu-Ag has the most stable corrosion current in the potentiostatic scanning test, exhibiting a better corrosion resistant performance. It can be analyzed from corrosion surface morphologies that Cu-Ag presents exfoliation corrosion mechanism while Cu-Sn shows crevice corrosion mechanism. Cu-Mg has a complex corrosion process caused by multiple corrosion mechanism. In the salt spray corrosion test, the corrosion degree of Cu-Ag is lighter than those of Cu-Sn and Cu-Mg after 24h test. Therefore, the Cu-Ag alloy exhibits the best corrosion resistance in chloride solution.

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.

Experimental investigation and empirical modeling for corrosion rate prediction of biodegradable zinc based composite considering the effect of constituent materials

2021 ◽  
pp. 095440622110556
Author(s):  
Dayanidhi Krishana Pathak ◽  
Pulak Mohan Pandey
Keyword(s):  
Mechanical Properties ◽  
Corrosion Rate ◽  
Biomedical Applications ◽  
Microwave Sintering ◽  
Research Work ◽  
Simulated Body Fluid Solution ◽  
Corrosion Current ◽  
Essential Elements ◽  
Empirical Modeling ◽  
Corrosion Properties

Biodegradable zinc (Zn) has shown great potential in the area of biomedical applications. Though, the mechanical properties are decisive for the use of Zn for orthopedic and cardiovascular applications. Consequently, one needs to focus on improving the mechanical properties of Zn for its suitability in biomedical applications. Alloying of essential elements of the human body resulted in enhancement of Zn’s mechanical properties in recent years. The corrosion rate of pure Zn is ideal; however, the addition of other elements has resulted in a loss of its ideal corrosion rate. The inclusion of hydroxyapatite (HA) and iron (Fe) in Zn has also been reported in improving the mechanical properties. Hence, a need is raised for the development of a model which can predict the corrosion rate after adding HA along with Fe in Zn. In this research work, empirical based modeling is proposed to predict the corrosion rate, which incorporates the outcome of addition of Fe and HA in Zn. The Zn based materials were fabricated with the help of microwave sintering for developing the empirical model. The corrosion properties of the materials were assessed through a potentiodynamic polarization test in a simulated body fluid solution. The enhanced corrosion rate was attained with the rise in HA (wt%) and Fe (wt%) in Zn. An empirical correlation was established between the influencing controlling parameters (i.e., corrosion current, equivalent weight, and material density) of corrosion rate. Confirmation experiments were conducted to validate the developed model, and the highest error of 6.12% was obtained between the experimental and predicted values exhibiting the efficaciousness of the proposed model.

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