Correlation of Surface Alloyed Microstructure of Pure Magnesium With its Corrosion Behavior

2012 ◽  
Vol 472-475 ◽  
pp. 161-164
Author(s):  
Yu Gao Liu
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Chloride Solution ◽  
Diffusion Time ◽  
Point Of View ◽  
Pure Magnesium ◽  
Corrosion Mechanism ◽  
Cross Sectional ◽  
Microstructure Characteristics ◽  
Solid Diffusion

This paper represents a summary of experimental results dealing with the time dependence of surface diffusion alloyed microstructure and its corrosion behavior at given temperature. The experiments were performed at 485°C for different solid diffusion time (6h, 12h, 18h ) and thus the surface alloyed microstructure of pure magnesium has been obtained. Optical and electrical microscopy and EDS compositions analysis were used to examine the cross sectional microstructure characteristics of alloyed layers of treated samples. It is shown that the new phases formed and its continuity, depending on the diffusion treated time at given temperature, have a noticeable influence on corrosion resistance and corrosion mechanism. The new formed phase Al5Mg11Zn4 was inert to the chloride solution compared with pure magnesium and acted as a corrosion barrier. It was concluded that the continuous Al5Mg11Zn4 phase was beneficial from the point of view of corrosion resistance.

Studies and Research on the Corrosion Behavior of Ni-Al2O3 Compound Coatings Obtained by Electrochemical Methods

2020 ◽  
Vol 43 (3) ◽  
pp. 21-25
Author(s):  
Simona BOICIUC ◽  
◽  
◽  
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Corrosion Behaviour ◽  
Composite Coatings ◽  
Point Of View ◽  
Electrochemical Methods ◽  
Dispersed Phase ◽  
Nickel Matrix ◽  
Technical Alumina ◽  
Compound Coatings

The undertaken research which is described in this paper aims at the corrosion behaviour of composite coatings in nickel matrix using as dispersed phase technical alumina with dimensions of 5 μm and their characterization from a microstructural point of view. The corrosion resistance in the saline fog of the coatings is influenced by the microstructure, the stresses developed in the layer and the roughness.

scholarly journals Effect of Oxide Scale Microstructure on Atmospheric Corrosion Behavior of Hot Rolled Steel Strip

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 517
Author(s):  
Bin Sun ◽  
Lei Cheng ◽  
Chong-Yang Du ◽  
Jing-Ke Zhang ◽  
Yong-Quan He ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Oxide Scale ◽  
Corrosion Product ◽  
Corrosion Behavior ◽  
Corrosion Test ◽  
Atmospheric Corrosion ◽  
Corrosion Mechanism ◽  
Type I ◽  
Rust Layer ◽  
Hot Rolled

The atmospheric corrosion behavior of a hot-rolled strip with four types (I–IV) of oxide scale was investigated using the accelerated wet–dry cycle corrosion test. Corrosion resistance and porosity of oxide scale were studied by potentiometric polarization measurements. Characterization of samples after 80 cycles of the wet–dry corrosion test showed that scale comprised wüstite and magnetite had strongest corrosion resistance. Oxide scale composed of inner magnetite/iron (>70%) and an outer magnetite layer had the weakest corrosion resistance. The corrosion kinetics (weight gain) of each type of oxide scale followed an initial linear and then parabolic (at middle to late corrosion) relationship. This could be predicted by a simple kinetic model which showed good agreement with the experimental results. Analysis of the potentiometric polarization curves, obtained from oxide coated steel electrodes, revealed that the type I oxide scale had the highest porosity, and the corrosion mechanism resulted from the joint effects of electrochemical behavior and the porosity of the oxide scale. In the initial stage of corrosion, the corrosion product nucleated and an outer rust layer formed. As the thickness of outer rust layer increased, the corrosion product developed on the scale defects. An inner rust layer then formed in the localized pits as crack growth of the scale. This attacked the scale and expanded into the substrate during the later stage of corrosion. At this stage, the protective effect of the oxide scale was lost.

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.

Study on Electroless Ni-P Deposit on W-Cu Alloy and its Anti-Corrosion Mechanism

2008 ◽  
Vol 373-374 ◽  
pp. 240-243 ◽  
Author(s):  
Long Hao ◽  
Ye Ming Zhang ◽  
Chao Yang ◽  
Hua Zhu ◽  
Xu Hui Mao ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Sodium Chloride ◽  
Potentiodynamic Polarization ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Alloy Coating ◽  
Corrosion Mechanism ◽  
Alloy Substrate ◽  
Cu Alloy ◽  
Electroless Ni

With suitable pretreatment, a compact and even nickel-phosphorus alloy coating was obtained on W-Cu alloy by electroless deposition from solutions containing nickel sulphate as a source of nickel and sodium hypophosphite as the reducing agent and a source of phosphorus. The Ni-P coating was normally prepared from acidic baths at high temperature of the order of 90oC with the pH of 4.8 and it was smooth and uniform and exhibited high crystal refinement and high microhardness and superior corrosion resistance. The microhardness, adhesion and corrosion resistance mechanism of Ni-P deposit were studied. The microhardness of the Ni-P alloy deposit increases greatly by tempering at various temperatures. The Ni-P deposit has a strong adhesive force with W-Cu alloy substrate checked by thermal shock test and scribe test. The anti-corrosion ability of Ni-P coating and its anti-corrosion mechanism were measured using immersion experiment and potentiodynamic polarization techniques. The results showed that the corrosion resistance of Ni-P coating was higher than that of W-Cu alloy substrate in the 10vol.% sulfuric acid, monitoring sweat solution and 3.5wt.% sodium chloride solution. The anti-corrosion mechanism of electroless Ni-P coating immersed in 3.5wt.% sodium chloride solution was studied using potentiodynamic polarization techniques. The surface micromorphological morphology and structure of the Ni-P coating were investigated using Scanning Electronic Microscope (SEM) and X-ray Diffraction (XRD). The results indicated that the Ni-P alloy coating consisted of microcrystals and it was amorphous in structure, and the electrochemical measurement showed passive film formed on Ni-P coating during immersion test in the 3.5wt.% sodium chloride solution.

scholarly journals Corrosion Behavior of a WC/C Coated 7075-T6 Aluminum Alloy

2013 ◽  
Vol 577-578 ◽  
pp. 217-220
Author(s):  
Sergio Baragetti ◽  
M. Daurù ◽  
Riccardo Gerosa ◽  
Barbara Rivolta
Keyword(s):  
Surface Roughness ◽  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Corrosion Behavior ◽  
Experimental Tests ◽  
Point Of View ◽  
Surface Finishing ◽  
Polished Surface ◽  
Foreign Object ◽  
Final Thickness

In the present experimental work, a WC/C coated 7075-T6 aluminum alloy was considered from the corrosion point of view. The coating was deposited by PVD technique with a final thickness of about 2.5μm. In order to study the influence of the coating on the corrosion behavior of the aluminum alloy, the samples surfaces were partially coated and the interface among the metal and the coating was analyzed after the corrosion tests described into the ASTM G110 standard. Such experimental plan was decided in order to simulate the possible in-service local removal of the thin and hard coating. This kind of damage, due for example to a foreign object impact, can occur because of the great hardness difference between the coating and the substrate. The experimental tests were carried out on samples with different surface finishing, ranging from about 0.02μm Ra (mirror-polished surface) to about 0.8μm Ra (320 grit paper). The aim of such choice was to investigate the effect of a surface roughness different from the optimal one (mirror polished) on the coating deposition. Moreover a different corrosion resistance is expected.

Investigation on corrosion performance of multilayer Ni-P/TiO2 composite coating on steel

2016 ◽  
Vol 23 (3) ◽  
pp. 309-314
Author(s):  
M. Edwin Sahayaraj ◽  
J.T. Winowlin Jappes ◽  
I. Siva ◽  
N. Rajini
Keyword(s):  
Corrosion Resistance ◽  
Mild Steel ◽  
Corrosion Behavior ◽  
Steel Substrate ◽  
Composite Coatings ◽  
Multilayer Coating ◽  
Electroless Nickel ◽  
Corrosion Mechanism ◽  
Corrosion Performance ◽  
Electroless Ni

AbstractElectroless nickel coating treatment improves the corrosion resistance of mild steel. This work aims at studying the corrosion behavior of electroless Ni-P/TiO2 composite and multilayer coatings applied to the mild steel substrate as their as-plated state and furnace annealed at various temperatures and compared both the coatings’ corrosion performance. The corrosion behavior of the deposits was evaluated by potentiodynamic polarization studies in 3.5 wt% sodium chloride solution. The results showed that the corrosion resistance of the multilayer coating was two times higher compared to the composite coatings. Further, the corrosion mechanism was discussed in terms of microstructure, phase transformation, grain size, and microstrain.

Review of Copper Atmospheric Corrosion in H2S

2014 ◽  
Vol 548-549 ◽  
pp. 177-181
Author(s):  
Ping Wang ◽  
Zhao Hui Yin ◽  
Han Tao Ren ◽  
Song Xu ◽  
Dong Wei Ma
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Atmospheric Corrosion ◽  
Corrosion Inhibitors ◽  
External Factors ◽  
Corrosion Mechanism ◽  
Corrosive Environment ◽  
Copper Corrosion ◽  
Environment Factors ◽  
The Impact

The losses due to copper corrosion in H2S atmospheric corrosion have attracted much focus. It’s important to improve copper corrosion resistance that the corrosion law, corrosion mechanism and characteristics were studied in H2S environment. This paper reviewed the corrosion behavior of copper, analyzed the impact of environment factors and corrosion analysis tools. Through evaluating and improving corrosion by external factors, including improving corrosive environment, using coating protection and adding corrosion inhibitors, appropriate corrosion measures were taken to extend the life of the equipment.

Influence of heat treatment on corrosion behavior of laser welded Mg-Gd-Y fusion zones

2020 ◽  
Vol 67 (4) ◽  
pp. 337-343
Author(s):  
Lyuyuan Wang ◽  
Jian Huang ◽  
Yong Peng ◽  
Yang Jia ◽  
Rong Ni
Keyword(s):  
Corrosion Resistance ◽  
Fusion Zone ◽  
Corrosion Behavior ◽  
Corrosion Mechanism ◽  
Content Type ◽  
Treated Condition ◽  
Heat Treated ◽  
Protective Films ◽  
Heat Treated Condition ◽  
Treated State

Purpose This paper aims to evaluate the corrosion resistance of fusion zones in different heat treated condition from laser welded Mg-Gd-Y alloys and analyze their intrinsic corrosion mechanism. Design/methodology/approach The corrosion behavior of fusion zone from laser-welded Mg-Gd-Y alloy joints in the as-welded, ageing and solution + ageing conditions was investigated in the 3.5 wt.% NaCl solution by immersion tests. Findings The corroded surface of as-welded fusion zone consists of dark and bright regions, and the bright regions were composed of high-density needle-like products, whereas some different extended direction of the cracks with lots of long ultrafine needle-shaped corrosion products appeared in the dark regions. The corrosion resistance of the fusion zone is slightly decreased after the ageing treatment. Originality/value The solution + ageing treated fusion zone exhibits the highest corrosion resistance than that of the as-welded and ageing treated state because of the full dissolution of the cathodic coarse eutectic compound, grains growth and relatively compact protective films. The inhomogeneous distribution of the β′ can somewhat improve the corrosion rate of solution + ageing treated fusion zone when compared with base metal.

scholarly journals Corrosion Behavior of CoCrFeNiTax Alloys in 1 M Sodium Chloride Aqueous Solution

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5157
Author(s):  
Chun-Huei Tsau ◽  
Rong-Wei Hsiao ◽  
Tien-Yu Chien
Keyword(s):  
Aqueous Solution ◽  
Corrosion Resistance ◽  
Electrochemical Impedance Spectroscopy ◽  
Sodium Chloride ◽  
Corrosion Behavior ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Electrochemical Impedance ◽  
Eutectic Structure ◽  
Different Temperatures

This paper investigates the effects of Ta content on the microstructures, hardness and corrosion behavior of as-cast CoCrFeNiTax alloys. The results indicate that the addition of Ta can change the microstructures of these alloys to dual-phased structures (FCC + HCP), as well as increasing their hardness. This study uses constant galvanostatic/potentiometric methods to measure the polarization curves of CoCrFeNiTa0.1, CoCrFeNiTa0.3 and CoCrFeNiTa0.5 alloys in deaerated 1 M sodium chloride solution at different temperatures. Electrochemical impedance spectroscopy is also used to analyze these alloys in sodium chloride solution. The results indicate that the CoCrFeNiTa0.5 alloy has a eutectic structure and the highest hardness. Furthermore, although the CoCrFeNiTa0.5 alloy has the best corrosion resistance, the CoCrFeNiTa0.3 alloy has the best pitting resistance among these alloys.

scholarly journals Study on the Correlation between the Microstructure Characteristics and Corrosion Behaviors of 2A12-T4 Aluminum Alloy under Thermal Strain

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 924
Author(s):  
Shuaihao Qian ◽  
Timing Zhang ◽  
Yuhua Chen ◽  
Hongxiang Li ◽  
Jilin Xie ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Dynamic Recrystallization ◽  
Grain Boundaries ◽  
Corrosion Behavior ◽  
Tensile Strain ◽  
Thermal Strain ◽  
Peak Temperature ◽  
Microstructure Characteristics ◽  
Precipitated Phase

In this study, the welding thermal simulation technology was used to prepare samples under different peak temperatures and strain levels in order to reveal the effects of thermal strain on the microstructure characteristics and corrosion resistance of aluminum alloy. Furthermore, the correlation between microstructure evolution law and corrosion behavior was studied by analyzing the microstructure characteristics and performing electrochemical polarization curve tests. Results showed that the amount and distribution of the precipitated phase were the main factors affecting the corrosion behavior of aluminum alloy. The precipitated phase was distributed along the direction of tensile strain, and the grain size was coarsened from 152 to 260 μm (and even exceeded 280 μm) after experiencing peak temperatures of 300 and 400 °C. In addition, the risk of corrosion for the samples that experienced thermal strain was increased compared to those that did not undergo tensile strain. The samples that experienced a peak temperature of 300 °C presented the best corrosion resistance as the precipitated phase was evenly distributed in the matrix. However, when the peak temperature was 400 °C and the strain was 8%, the number and density of the precipitated phase increased due to the dynamic recrystallization, and the corrosion resistance of the sample became the worst. Finally, the microstructure analysis results showed that dynamic recrystallization occurred in the sample with a peak temperature of 400 °C, and the precipitated phase was mainly distributed along the grain boundaries. This led to the decrease of the corrosion resistance of grain boundaries, and the corrosion developed from pitting corrosion to intergranular corrosion.

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