scholarly journals UNDERSTANDING CORROSION BEHAVIOR OF Zn AND Zn ALLOY GALVANIZED STEELS IN HUMID TROPICAL CLIMATE

2018 ◽  
Vol 55 (5B) ◽  
pp. 140 ◽  
Author(s):  
Nguyen Nhi Tru
Keyword(s):  
Corrosion Behavior ◽  
Environmental Parameters ◽  
Tropical Climate ◽  
Chloride Ions ◽  
Laboratory Observation ◽  
Cut Edge ◽  
Corrosion Rates ◽  
Galvanized Steels ◽  
Humid Tropical Climate ◽  
Tropical Conditions

The humid tropical climate parameters and airborne salinity are generally considered important factors affecting detrimental corrosion of zinc and its alloy coatings. To more thoroughly understand their corrosion performances, the five years weathering tests for zinc and Zn-Al galvanized steels in rural and coastal humid tropical areas were conducted. Corrosion rates and other performance characteristics of zinc and Zn-Al coated samples were determined and discussed in relation with climatic and environmental parameters. Behavior of the coatings in rural and coastal tropical conditions revealed a strong influence of time of wetness (TOW) and airborne salinity on corrosion rates. In both test conditions, the dependence of coating’s mass loss on exposure time shows that the corrosion process of zinc coatings mostly obeys the law of power model M = Atn. Corrosion is recorded considerably stronger in the coastal atmosphere containing higher chlorides. The laboratory observation in cut-edge area of zinc alloys coated steel was also conducted and their corrosion behavior was detailed in condition of chloride ions attack.

Effect of the Grain Size on Electrochemical Corrosion Behavior of Cu60Ni20Cr20 Alloys in Solutions Containing Chloride Ions

2012 ◽  
Vol 476-478 ◽  
pp. 16-20
Author(s):  
Guo De Li ◽  
Jing Bian ◽  
Zhong Qiu Cao ◽  
Ke Zhang ◽  
Ya Jun Fu
Keyword(s):  
Grain Size ◽  
Corrosion Behavior ◽  
Electrochemical Corrosion ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Coarse Grained ◽  
Protective Film ◽  
Ion Concentrations ◽  
Corrosion Rates ◽  
Electrochemical Corrosion Behavior

The two Cu60Ni20Cr20alloys with the different grain size were prepared by conventional casting (CA) and mechanical alloying (MA) through hot pressing. Effect of the grain size on electrochemical corrosion behavior of the two Cu60Ni20Cr20 alloys was also studied in solutions containing chloride ions. Results show that the free corrosion potentials of the two alloys move toward to negative values, corrosion current densities increase and therefore corrosion rates become faster with the increment of chloride ion concentrations. CACu60Ni20Cr20alloy and MACu60Ni20Cr20alloy have passive phenomena in 0.05mol/L Na2SO4 neutral solution, but passive phenomena become weak or disappear when the chloride ions are added. Corrosion rates of the nanocrystalline MACu60Ni20Cr20alloy become slower than those of the coarse grained CACu60Ni20Cr20alloy in solutions containing the same chloride ion concentrations because MACu60Ni20Cr20alloy is able to produce large concentrations of grain boundaries and passive elements is able to diffuse quickly to form the protective film.

scholarly journals The Influence of the Chemical Composition on the Corrosion Performances of Some Al-Fe-Si, Al-Mg-Si and Al-Mg-Mn Type of Alloys

2014 ◽  
Vol 20 (4) ◽  
pp. 217-234 ◽  
Author(s):  
Kemal Delijić ◽  
Boštjan Markoli ◽  
Iztok Naglič
Keyword(s):  
Chemical Composition ◽  
Corrosion Behavior ◽  
Total Content ◽  
Open Circuit ◽  
Chloride Ions ◽  
Nacl Solution ◽  
Aqueous Corrosion ◽  
Corrosion Rates ◽  
Alloy Chemistry ◽  
Aa5182 Alloy

Paper presents the results on the corrosion behavior of some Al-Fe-Si, Al-Mg-Si and Al-Mg-Mn alloys in their final commercially usable tempered state. Durability of alloys was quantified and compared in the sense of corrosion rates in aqueous solutions while also having in mind the role of alloy chemistry. Open circuit corrosion potential (OCP) measurements, linear polarization and potentiodynamic anodic/cathodic polarization was employed in order to determine the corrosion behavior of samples in the mixture of chloride ions containing aqueous corrosion ambient. We found out that AlFe0.83Si0.18(AA8079), AlMg0.63Si0.72 (AA6005) and AlMg4Mn (AA5182) alloy exhibited the highest rates of passivation in 0.51 mol NaCl solution. The group of Al-Fe-Si alloys exhibited the greatest sensitivity to the changes in chemical composition under potentiodynamic polarization. Artificially aged Al-Mg-Si extruded profiles and fully annealed (after cold rolling) Al-Mg-Mn sheets exhibit very similar levels of equilibrium potentials E(I=0) in 0.51 mol NaCl solution. In the case of Al-Fe-Si alloys, we found that Fe/Si ratio also plays an important role, next to the total content of Fe and Si. Alloys with high Fe/Si ratios showed almost 30 % lower polarization resistance compared to the alloys with balanced Fe/Si, even in the case of the equal total content of alloying elements. The AlMg0.7Si1.2Mn0.8 alloy aged after quenching in the sprayed water and AlMg4Zn1.3Mn0.4 annealed sheet exhibit very similar levels of corrosion rates in 0.51 mol NaCl solution.

Electrochemical Corrosion Behavior of Cu-20Fe-12Cr Alloys with the Different Grain Size in Solutions Containing Chloride Ions

2011 ◽  
Vol 399-401 ◽  
pp. 655-661
Author(s):  
Zhong Qiu Cao ◽  
Rong Xue ◽  
Jing Bian ◽  
Ya Jun Fu
Keyword(s):  
Grain Size ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Ion Concentrations ◽  
Corrosion Rates ◽  
Electrochemical Corrosion Behavior ◽  
Different Grain Size

Electrochemical corrosion behavior of Cu-20Fe-12Cr alloys prepared by powder metallurgy (PM) and mechanical alloy (MA) with the different grain size was studied in solutions containing chloride ions. The free corrosion potentials move toward negative values and corrosion rates become faster with the increase of chloride ion concentrations for two alloys. Electrochemical impedance spectroscopy (EIS) plots of PMCu-20Fe-12Cr alloy are composed of a capacitive loop and a diffusion tail. Corrosion processes are controlled by diffusion. EIS plots of MACu-20Fe-12Cr alloy in Na2SO4 or 0.02mol.L-1NaCl solution are unable to have characteristics of Warburg impedance. Corrosion processes are controlled by electrochemical reactions. After chloride ion concentrations increase up to 0.05mol.L-1, their EIS plots are composed of double capacitive loops with a straight line induced Warburg resistance between two capacitive loops. The above EIS plots imply the existence of pitting corrosion. The corrosion rates of MACu-20Fe-12Cr alloy become faster than those of PMCu-20Fe-12Cr alloy because the reduction in the grain size of MACu-20Fe-12Cr alloy produces large concentrations of grain boundaries.

scholarly journals The Evaluation of the environmental parameters of battery-caged poultry house in the humid tropical climate

2020 ◽  
pp. e753
Author(s):  
Ayoola Olawole Jongbo
Keyword(s):  
Heat Stress ◽  
Relative Humidity ◽  
Environmental Parameters ◽  
Tropical Climate ◽  
Stress Index ◽  
Air Velocity ◽  
Humid Tropical Climate ◽  
Airflow Distribution ◽  
Hot Weather ◽  
Heat Stress Index

Heat stress is a key factor affecting the productions of the animals. In laying birds, it could cause loss of body weight and high mortality. To this end, a study was carried out in a naturally ventilated, tier-caged layer house to evaluate the environmental parameters and the heat stress index within the building during hot weather period. Throughout the study, the environmental parameters (air temperature, relative humidity and air velocity), inside and outside the experimental building were measured and recorded. The heat stress index using the temperature-humidity index (THI) was also estimated. The results of the study indicated that laying birds in this study were most of their lifetime subjected to hot conditions which could have a significant effect on their performances. It was also found out that the air velocity within the building was very low (0.07 ms-1 to 0.58 ms1) which could not provide a cool environment for the birds. The heat stress index (THI) inside laying bird building was found to be mostly influenced by high relative humidity compared to ambient temperature. Therefore, it would be appropriate if the airflow distribution inside the poultry building, in this study, could be evaluated using computational fluid dynamics to understand the velocity profile within the building. This could assist engineers to redesign the building and make it appropriate for laying birds in the humid tropical climate.

scholarly journals Corrosion of steel in ionic liquids

2003 ◽  
Vol 39 (1-2) ◽  
pp. 81-91 ◽  
Author(s):  
M.F. Arenas ◽  
R.G. Reddy
Keyword(s):  
Ionic Liquids ◽  
Carbon Steel ◽  
Corrosion Behavior ◽  
Anodic Polarization ◽  
Electrochemical Techniques ◽  
Chloride Ions ◽  
Steel Alloy ◽  
Passive Region ◽  
Corrosion Rates ◽  
Corrosion Of Steel

The corrosion behavior of 1018 carbon steel alloy has been investigated by electrochemical techniques. The ionic liquids studied were 1-butyl-3-methylimidazolium chloride ([C4mim]Cl), 1 hexyl-3-methylimidazolium hexafluorophosphate ([C6mim]PF6) 1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim]PF6), and 1-butyl-3-methylimidazolium bis-(trifluoromethanesulfonyl) imide ([C4mim][Tf2N]). Potentiodynamic polarization and Tafel plots were used to determine the corrosion behavior of the carbon steel. Results showed that corrosion resistance of 1018 carbon steel in ionic liquids is outstanding as indicated by the low corrosion rates obtained which ranged from 3-13 ?m/yr. Anodic polarization curves showed active/passive corrosion behavior of the alloy in most of the ionic liquids tested. However, ionic liquids containing chloride ions were unable to form a passive region.

Water Budget of Constructed Wetland System with Subsurface Vertical Flow in Sub-Humid Tropical Climate

2015 ◽  
Vol 1 (5) ◽  
pp. 235-242
Author(s):  
Édio Damásio da Silva Júnior ◽  
Rogério de Araújo Almeida ◽  
Elisa Rodrigues Siqueira ◽  
Ábio Roduvalho da Silva
Keyword(s):  
Constructed Wetland ◽  
Water Budget ◽  
Tropical Climate ◽  
Vertical Flow ◽  
Humid Tropical Climate ◽  
Wetland System

Effect of Formic Acid on Corrosion Behavior of STBA24 Low-Alloyed Steel and Its Weldment in Simulated Boiler Water Containing Chloride Ions

2020 ◽  
Vol 61 (9) ◽  
pp. 1775-1781
Author(s):  
Li-Bin Niu ◽  
Shoichi Kosaka ◽  
Masaki Yoshida ◽  
Yusuke Suetake ◽  
Kazuo Marugame
Keyword(s):  
Formic Acid ◽  
Corrosion Behavior ◽  
Chloride Ions ◽  
Alloyed Steel ◽  
Boiler Water ◽  
Low Alloyed Steel

Cut-edge corrosion behavior assessment of newly developed environmental-friendly coating systems using the Scanning Vibrating Electrode Technique (SVET)

2021 ◽  
pp. 109813
Author(s):  
Sina Sheikholeslami ◽  
Geraint Williams ◽  
H. Neil McMurray ◽  
Louis Gommans ◽  
Scott Morrison ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Behavior Assessment ◽  
Cut Edge ◽  
Environmental Friendly ◽  
Electrode Technique

scholarly journals Structure and Corrosion Behavior of Sputter-Deposited W-Mo Alloys

1970 ◽  
Vol 21 ◽  
pp. 19-25 ◽  
Author(s):  
Jagadeesh Bhattarai
Keyword(s):  
Corrosion Resistance ◽  
Magnetron Sputtering ◽  
Corrosion Behavior ◽  
Solid Solutions ◽  
Chemical Society ◽  
High Corrosion Resistance ◽  
Corrosion Rates ◽  
High Corrosion ◽  
Sputter Deposited

Nanocrystalline, single bcc solid solutions of W-Mo alloys have been successfully prepared by D. C. magnetron sputtering in a wide composition. The corrosion behavior of the sputter-deposited W-Mo alloys was studied. The W-Mo alloys showed significantly high corrosion resistance in 12 M HCl at 30o C. Their corrosion rates are about one and half orders of magnitude lower than that of sputter-deposited tungsten and lower than that of the sputter-deposited molybdenum even after prolonged immersion.DOI: 10.3126/jncs.v21i0.217Journal of Nepal Chemical Society Vol.21 2006 pp.19-25

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