Some Possibilities of Evaluation of Corrosive Resistance of Metal and Non-Metal Coatings

2015 ◽  
Vol 818 ◽  
pp. 133-136
Author(s):  
Mária Hagarová ◽  
Zuzana Fečková ◽  
Petra Lacková ◽  
Jana Cervová
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Corrosion Potential ◽  
Saturated Calomel Electrode ◽  
Organic Coating ◽  
Metal Coatings ◽  
Free Corrosion Potential ◽  
Metal Organic ◽  
Salt Fog

The study investigated the possibilities of determination of corrosion resistance of metal and non-metal (organic) coatings deposited to steel surface in the corrosion environment. To determine the corrosion rate of metal PVD coating based on Ti, we used the method involving measurement of polarization conductivity. Corrosion resistance of galvanic Ni or Ni-Co coatings was determined by measuring free corrosion potential ESCE (against that of saturated calomel electrode SCE), or by means of potentiodynamic polarization relationships according to Tafel. These methods provided the basic corrosion characteristics: corrosion potential Ecorr, instantaneous corrosion rate jcorr and polarization resistance Rp. Corrosion resistance of organic coating Woerodur, which was applied by pressure spray to the substrate pre-treated in various ways, was tested in a salt-fog environment. After the exposure to the respective environment we evaluated the appearance of coating. The aim of the study was to point out to the availability of methods suitable for evaluation of corrosion resistance of coatings, and to the possibilities of their application under real practical conditions.

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.

Corrosion Resistance of High-Alloyed Material UNS N08028 in Sodium Chloride Solution

2014 ◽  
Vol 893 ◽  
pp. 440-443
Author(s):  
Li Na Zhang ◽  
Jerzy A. Szpunar ◽  
Jian Xin Dong ◽  
Mai Cang Zhang
Keyword(s):  
Corrosion Resistance ◽  
Sodium Chloride ◽  
Corrosion Rate ◽  
Current Density ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Corrosion Potential ◽  
Ph Value ◽  
Chloride Concentration ◽  
Decreasing Ph

The influence of ions chloride concentration and pH value on the corrosion resistance of high-alloyed material UNS N08028 in the sodium chloride solution is investigated. Results show that the corrosion potential is active cathodically with the increase of chloride concentration. The current density and corrosion rate both increase with increasing chloride concentration and decreasing pH value.

scholarly journals Influence of Seawater Salinity on Corrosion of Austenitic Steel

2019 ◽  
Vol 26 (3) ◽  
pp. 219-225
Author(s):  
Robert Starosta
Keyword(s):  
Sodium Chloride ◽  
Corrosion Rate ◽  
Austenitic Steel ◽  
Current Density ◽  
Corrosion Current Density ◽  
Corrosion Potential ◽  
Saturated Calomel Electrode ◽  
Corrosion Current ◽  
Seawater Salinity ◽  
Corrosion Susceptibility

Abstract Due to the paramagnetic properties and the ability to passivation, for the production of hulls of some vessels (mainly warships), corrosion-resistant (stainless) steels with austenitic structure are used. This article describes the influence of seawater salinity on selected corrosion properties of high-alloy steel X5CrNi 18-10 (304). The average salinity of the seas is taken as 3.5% content of sodium chloride. Corrosion rate of the tested material was evaluated in an aqueous solution of sodium chloride was evaluated. The NaCl concentration in corrosive solutions was 0.7%, 1.4%, 2.1%, 2.8%, 3.5%, 4.2%. Corrosion tests were performed using the potentiodynamic method. The range of electrochemical potential changes was Ecorr ±150 mV. Corrosion rate was assessed on the basis of corrosion current density measurements. Corrosion potential values against the saturated calomel electrode were also determined. Based on the obtained measurement results and non-parametric significance tests carried out, a significant influence of seawater salinity on the value of corrosion current density and corrosion potential was found. The highest value of corrosion current density (jcorr), and thus the highest corrosion rate, was recorded for 3.5% NaCl solution. In the concentration range from 0.7 to 3.5% NaCl in solution, the corrosion rate of austenitic steel increases. A further increase in salinity of electrolyte results in the inhibition of corrosion rate of steel. There is almost a full negative, linear correlation between the proportion of sodium chloride in the corrosive solution and the value of corrosion potential. Along with the rise in the salinity of seawater, increase the electrochemical activity, and thus the corrosion susceptibility, thus the corrosion susceptibility, of the austenitic steel X5CrNi 18-10 was observed.

Corrosion Resistance of Structural Steel Processed Using Electro-Plasma Methods

2001 ◽  
Author(s):  
Paul J. Schilling ◽  
Paul D. Herrington
Keyword(s):  
Corrosion Resistance ◽  
Structural Steel ◽  
Electrochemical Impedance ◽  
Metal Coatings ◽  
Linear Polarization Resistance ◽  
Steel Surfaces ◽  
Plasma Methods ◽  
Superior Corrosion Resistance ◽  
Salt Fog

Abstract Electro-plasma cleaning and deposition is a recently developed electrolytic method for cleaning mill scale and other debris from steel surfaces, and depositing protective metal coatings. Structural steel was processed using these methods and tested for corrosion resistance. Samples included freshly cleaned steel coupons and samples coated with a metallic zinc layer. Tests included linear polarization resistance, QUV weathering, salt fog exposure, and electrochemical impedance spectroscopy. Steel samples cleaned by electro-plasma methods exhibited superior corrosion resistance to those cleaned by shot-blasting. The zinc metal coatings demonstrated potential for long-term corrosion protection.

The Corrosion Characteristics of AlSi1MgMn

2015 ◽  
Vol 818 ◽  
pp. 125-128
Author(s):  
Petra Lacková ◽  
Mária Mihaliková ◽  
Jana Cervová ◽  
Anna Lišková
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Exposure Time ◽  
Polarization Resistance ◽  
Open Circuit Potential ◽  
Corrosion Potential ◽  
Open Circuit ◽  
Atmospheric Conditions ◽  
X Ray ◽  
Industrial Atmosphere

The paper presents the evaluation of corrosion resistance of aluminium alloy AlSi1MgMn. This alloy is used above all in any atmospheric conditions. The corrosion resistance of the alloy was evaluated by determining the open circuit potential (OCP) in solution SARS (this solution simulates the industrial atmosphere) after the 10 months of exposure time. The surface of aluminum alloys were analyzed by using energy dispersive X-ray analysis after the exposure time. The basic of corrosion characteristics (corrosion potential Ecorr, corrosion rate icorr and polarization resistance Rp) were determined by potenciodynamic measurements according to Tafel’s and Stern’s methods.

Effect of adding rare-earth cerium on the microstructure and acid rain corrosion resistance of the ADC12 alloy

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
LiJie Zhang ◽  
Hong Yan ◽  
YongCheng Zou ◽  
BaoBiao Yu ◽  
Zhi Hu
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Acid Rain ◽  
Corrosion Current Density ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
The Self ◽  
Electrochemical Tests ◽  
Immersion Corrosion ◽  
Eutectic Si

Abstract The effect of adding cerium on the microstructure and acid rain corrosion resistance of the AlSi11Cu3 alloy was investigated by means of optical microscopy, scanning electron microscopy, and energy dispersive spectroscopy. The AlSi11Cu3 alloy was doped with varying stoichiometries of cerium to generate AlSi11Cu3-xCe, where x = 0, 0.5, 1.0, and 1.5 wt.%. The results show that the α-Al, eutectic Si, and β-Al5FeSi phases in the AlSi11Cu3-1.0Ce alloy are significantly refined. Electrochemical tests demonstrated an increase in the self-corrosion potential value of the AlSi11Cu3-1.0Ce alloy from –670 mV to –628 mV relative to the untreated alloy. In addition, the AlSi11Cu3-1.0Ce alloy has the lowest corrosion current density (8.4 μA × cm–2). Immersion corrosion testing on the AlSi11Cu3-1.0Ce alloy revealed a corrosion rate of 0.71 mg × cm–2 × d–1, constituting a 72% reduction in the corrosion rate compared to the untreated alloy. These results indicate that the AlSi11Cu3-1.0Ce alloy has a high resistance to acid rain corrosion, which is the result of a refinement of the cathode phases.

High corrosion resistant ZrC films synthesized by ion-beamassisted deposition

1999 ◽  
Vol 14 (2) ◽  
pp. 615-618 ◽  
Author(s):  
Xiao-Ming He ◽  
Li Shu ◽  
Hai-Bo Li ◽  
Duan Weng
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Polarization Resistance ◽  
Corrosion Potential ◽  
Ion Beam ◽  
High Hardness ◽  
Corrosion Current ◽  
Experimental Results ◽  
Corrosion Resistant ◽  
Ion Beam Assisted Deposition

ZrC films with high hardness were deposited on A3 steel by ion-beam-assisted deposition and had a corrosion rate more than two orders less and a corrosion potential 0.19 V greater than those of the bare A3 steel. The corrosion current of ZrC films was 10 times less and the polarization resistance at least 7.82 times higher than those of both Teflon and ZrN films, respectively. The experimental results confirmed that ZrC films notably enhanced the corrosion resistance of steels.

Effect of under layer metallic coating composition on phosphating and the corrosion performance for automobile applications

CORROSION ◽  
10.5006/3748 ◽  
2021 ◽  
Author(s):  
Chandrashekhar Savant ◽  
Poorwa Gore ◽  
VS Raja
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Zinc Coating ◽  
Organic Coating ◽  
Phosphate Coating ◽  
Corrosion Performance ◽  
Epoxy Primer ◽  
Phosphate Coatings ◽  
Galvanized Coating ◽  
Salt Fog

Automobile coating system consists of a metallic underlayer followed by a phosphate coating and, lastly, multilayer organic coating. In this work, the effect of the underlying metallic coatings, namely, a Mg-Al-Zn alloy coating (Magizinc) and a conventional galvanized Zn coating on the phosphate coatings formed thereon, and its corrosion performance was investigated. The corrosion resistance offered by the phosphate coating formed on the Magizinc coating was higher than the phosphate coating on the galvanized Zn coating (a reference coating employed in the study) in NaCl solution, as revealed by potentiodynamic polarization, electrochemical impedance spectroscopy, and salt-fog tests. In-depth characterization of the phosphate coatings was carried out using scanning electron microscopy and glow discharge optical emission spectroscopy. It was revealed that the phosphate crystals formed on the Magizinc coating were more fine-grained, compact, and crack-free as compared to that formed on the galvanized coating and contained Mg aiding 4-10 times increase in the corrosion resistance as determined by the electrochemical studies. However, it only improved marginally against the appearance of red rust in a salt-fog test over the unphosphated Magizinc coating. The phosphate coating on Magizinc marginally improved the adhesion of an epoxy primer coating applied on the phosphated Magizinc coating and significantly (>3.5 times longer exposure) retarded the deterioration of the epoxy primer coating in the salt-fog environment in comparison with the similar studies carried out on the phosphated conventional galvanized zinc coating. Notably, phosphating the Magizinc coating caused a ten times reduction in the H pickup compared to that in the galvanized coating under identical phosphating conditions, suggesting the former coating lowered the propensity for hydrogen embrittlement in the steel.

Effects of Cu and Sb on Corrosion Resistance of ZnAl27 Alloy

2012 ◽  
Vol 217-219 ◽  
pp. 400-404
Author(s):  
Cheng Gang Hao ◽  
Jian Min Zeng ◽  
Jun Chen ◽  
Ping Chen ◽  
Jian Qiang Xiao
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
Free Corrosion Potential ◽  
Corrosion Tests ◽  
Immersion Corrosion ◽  
Electrochemical Parameters ◽  
Current Shift ◽  
Surface Morphologies ◽  
Linear Polarisation

The corrosion behavior of ZnAl27 alloys in 35g/L NaCl solution has been studied by electrochemical and immersion corrosion tests. The effects of Cu and Sb on the Tafel curves, electrochemical parameters of free corrosion potential, linear polarisation resistance (LPR) and free corrosion current, of the ZnAl27 alloy have been investigated. The surface morphologies of the alloy after immersion corrosion tests have been observed through SEM. The results indicate that addition of proper Cu can improve its corrosion resistance of the alloy, or the free corrosion potential the corrosion current shift towards the positive and negative,respectively. However, excessive addition of Cu can deteriorate the corrosion resistance of the alloy. On the other hand, the corrosion resistance of the ZnAl27 alloy decreases with the increasing of Sb content.

The Effect of Trace Boron Element on Local Corrosion Resistance of Casted 0.04C-16Cr Ferritic Stainless Steel

2011 ◽  
Vol 415-417 ◽  
pp. 800-806 ◽  
Author(s):  
Tie Ming Guo ◽  
Ding Cang Zhang ◽  
Zhi Hui ◽  
Chang Song Han ◽  
Li Ming Zhao
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Nitric Acid ◽  
Corrosion Rate ◽  
Ferritic Stainless Steel ◽  
Pitting Corrosion ◽  
Intergranular Corrosion ◽  
Corrosion Potential ◽  
Chloride Ions ◽  
Curve Method

0.04C-16Cr and 0.04C-16Cr containing 26ppm B ferritic stainless steels were smelted by using a vacuum induction furnace. Then 65% boiling nitric acid method and the electrochemical potentiokinetic reactivation method (EPR) were used to research their intergranular corrosion sensitivity. Meanwhile, electrochemical test method (Tafel polarization curve method, the anode circular polarization curve method) and chemical immersion method were used to research their pitting corrosion resistance. The results showed that the corrosion rate of 0.04 C-16Cr stainless steel containing 26ppm B in 65% boiling nitric acid is lower than that of 0.04 C-16Cr stainless steel. The reactivation rate of 0.04C-16Cr containing 26ppm B in dilute sulphuric acid medium significantly reduced compared with that of 0.04C-16Cr. The pitting corrosion potential, self-corrosion potential and the value of (Eb-Ep) of the stainless steel containing with 26ppm B in chlorideions medium reduced, while the corrosion rate increased compared with the stainless steel without B addition. It indicates that trace boron addition improves the intergranular corrosion resistance and repair ability of the passive film of the 0.04C-16Cr ferritic stainless steel after pitting corrosion process in chloride ions medium, but it also promotes the pitting corrosion tendency of the steel. Besides, introduction B to 0.04C-16Cr ferritic stainless steel reduces the steel’s corrosion resistance in active dissolved zone and promotes its intergranular corrosion tendency in chloride ions medium. The electrochemical characteristics of local corrosion are consistent with the results of chemical immersion test.

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