scholarly journals Effect of Structural Modification on Corrosion Behavior of Hypo Eutectic Al-Si Alloy

2018 ◽  
Vol 778 ◽  
pp. 16-21
Author(s):  
Muhammad Mansoor ◽  
Muhammad Kamran Yaseen ◽  
Shaheed Khan
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Earth Metal ◽  
Alloy System ◽  
Eutectic Phase ◽  
Al Alloy ◽  
General Corrosion ◽  
Corrosion Properties ◽  
Unmodified Alloy ◽  
Cast Alloys

Al-Si eutectic cast alloys are widely used in aeronautical and automobile industries where significantly high strength, toughness and wear resistance are required. This class of cast alloys exhibit relatively low corrosion resistance in brine environments. The mechanical properties of the alloy system mainly depend upon the shape of Si rich eutectic phase, which mainly has acicular geometry. In present research, the effect of modified microstructure of 12 wt. % Si-Al alloy on corrosion behavior was studied. The needle like Si rich eutectic phase was modified to disperse spherical structure using rare earth metal halides. The corrosion rate and pitting behavior of modified and unmodified alloy were evaluated in 3.5% NaCl solution by general corrosion for calculated time. It was observed that the corrosion rate and pitting tendency of modified alloy had been appreciably reduced as compare to unmodified alloy. The improvement of corrosion properties were the attributes of changed morphology and distribution of Si rich eutectic phase.

scholarly journals De-alloying Behavior of Mg–Al alloy in Sulphuric Acid and Acetic Acid Aqueous Solutions

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2046 ◽  
Author(s):  
Yonggang Li ◽  
Yinghui Wei ◽  
Shengqiang Yang
Keyword(s):  
Acetic Acid ◽  
Aqueous Solutions ◽  
Sulphuric Acid ◽  
Corrosion Behavior ◽  
Eutectic Phase ◽  
Al Alloy ◽  
General Corrosion ◽  
H2so4 Solution ◽  
Corrosion Characteristic ◽  
Selective Corrosion

The fabricated Mg–Al alloy consists of α-Mg phase and Mg–Mg17Al12 eutectic phase. The corrosion behavior of cast Mg–Al alloy in sulphuric acid (H2SO4) and acetic acid (HAc) aqueous solutions was investigated. The Mg–Al alloy shows general corrosion in H2SO4 solution, and the α-Mg dendrites revealed a slightly faster corrosion rate than that of the eutectics. In HAc solution, the alloy shows an obvious selective corrosion characteristic, with the α-Mg dendrites being corroded preferentially. Grain orientation plays an important role in corrosion behavior of the alloy in the HAc solutions.

Influences of Zinc Content and Solution Heat Treatment on Microstructure and Corrosion Behavior of Mg-Zn Binary Alloys

CORROSION ◽  
10.5006/3672 ◽  
2020 ◽  
Author(s):  
Dinh Pham ◽  
Sachiko Hiromoto ◽  
Equo Kobayashi
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Volume Fraction ◽  
Galvanic Corrosion ◽  
Zinc Content ◽  
Eutectic Cell ◽  
Zn Content ◽  
Cast Alloys

The influences of Zn content and heat treatment on microstructure and corrosion behavior of Mg-xZn (x=1, 3, 5 and 7 wt.%) alloys were studied. (α-Mg + MgZn) eutectic cells and Zn-segregated regions were formed in the as-cast alloys. The Zn-rich phases acted as micro-cathodes in galvanic corrosion. Volume fraction of the Zn-rich phases increased with Zn content of the as-cast alloys, leading to a decrease in corrosion resistance. The corrosion rate of the as-cast alloys increased by 4 times with an increase of the volume fraction of eutectic cell from 0.07 vol.% of Mg-1Zn alloy to 2.18 vol.% of Mg-5Zn alloy. The corrosion rate of Mg-7Zn alloy with 2.87 vol% eutectic cells was 2 times higher than that of Mg-5Zn alloy. The Zn-rich phases dissolved by the T4 treatment and only the T4-treated Mg-7Zn alloy obviously showed eutectic cells of 1.73 vol.%. The polarization resistance (Rp) of the T4-treated Mg-1, 3 and 5Zn alloys was 2-10 times higher than that of the as-cast alloys. The T4-treated Mg-7Zn showed similar Rp to the as-cast Mg-5Zn alloy. Consequently, the volume fraction of Zn-rich phases dominated the corrosion resistance of Mg-xZn alloys.

The Corrosion Behavior of Niobium in Hydrochloric Acid Solutions

CORROSION ◽  
1980 ◽  
Vol 36 (10) ◽  
pp. 554-558 ◽  
Author(s):  
B. S. COVINO ◽  
J. P. CARTER ◽  
S. D. CRAMER
Keyword(s):  
Hydrochloric Acid ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Mineral Resources ◽  
The United States ◽  
General Corrosion ◽  
Ferric Ion ◽  
Acid Solutions ◽  
Corrosion Rates ◽  
Hydrochloric Acid Solutions

Abstract Studies to better understand the corrosion behavior of niobium in hydrochloric acid solutions have been conducted as part of the Bureau of Mines’ effort to conserve the United States’ mineral resources. A study of the general corrosion behavior of niobium as a function of acid concentration, time, oxygen, and added ferric ion is reported. Weight loss (corrosion) tests were performed in air saturated (agitated and static) and helium saturated (agitated) hydrochloric acid solutions ranging from 1N to 10N at temperatures from 35 to 100 C and exposures up to 60 days. The 30 day corrosion rates ranged from 0.0 μm/y in 35 C air saturated (agitated) 1N HCl to 230 μm/y in air saturated (static) 9.8N HCl at 85 C. Although the corrosion rates decreased rapidly for times up to 30 days, the rates for 30 and 60 days were essentially identical. The presence of air did not affect the corrosion rate of niobium, while the presence of only 70 ppm of ferric ion reduced the corrosion rate in most air saturated 5N and 10N HCl solutions.

Effect of coating parameters on microstructure, corrosion behavior, hardness and formability of hot-dip Galfan and galvanized coatings

2021 ◽  
Vol 112 (4) ◽  
pp. 321-332
Author(s):  
Amirreza Khezrloo ◽  
Farshid Rezazadeh ◽  
Mohammad Rajaee ◽  
Morteza Tayebi ◽  
Ermia Aghaie ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Process Parameters ◽  
Immersion Time ◽  
Process Temperature ◽  
Corrosion Properties ◽  
Steel Sheets ◽  
Mechanical And Corrosion Properties ◽  
Galvanized Coatings ◽  
Dipping Time

Abstract In the current study, zinc–aluminum (Galfan) and zinc (galvanized) coatings were coated on steel sheets using the hot-dip technique. The effect of process parameters on the microstructure, corrosion behavior, hardness, and formability of the coatings was assessed. The results demonstrated that both the corrosion area and corrosion rate of the galvanized coatings were reduced by increasing the immersion time. In contrast, the process temperature did not affect the corrosion behavior. Furthermore, by prolonging the dipping time, the hardness of the coatings decreased. The Galfan coatings showed higher formability and the superiority of mechanical and corrosion properties of Galfan coatings over conventional galvanized coatings was indicated.

A Study on Corrosion of Cast-On-Strap Alloys

2011 ◽  
Vol 194-196 ◽  
pp. 1361-1364
Author(s):  
Ai Ju Li ◽  
Hong Yu Chen ◽  
Long Chuan Dou ◽  
Hui Wang ◽  
Wei Zhang
Keyword(s):  
Weight Loss ◽  
Sulfuric Acid ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Intergranular Corrosion ◽  
Corrosion Layer ◽  
General Corrosion ◽  
Acid Solutions ◽  
Grain Refiner ◽  
Sulfuric Acid Solutions

The effects of different Sn or Se content on the corrosion behavior of lead-Sn or Pb-Sn_Se alloy in sulfuric acid solutions were investigated by metallurgical microscope, SEM, and weight loss tests. It was found that the addition Sn acts as grain coarser, but Se acts as grain refiner and Pb-Sn-Se alloys feature smaller grains. SEM for the corrosion layer indicated that the intergranular corrosion occurs on the surface of alloys with high Sn content (>1.wt%), but the general corrosion occurs on the surface of Pb-Sn alloys with low Sn content (<1.wt%) and all Pb-Sn-Se alloys. And The structure of corrosion layer and the eroded degree are relative to the height of the strap alloys above the plate. And the 1cm strap alloy above the plate was cathodically protected and almost no corrosion problems appeared. The corrosion rate of alloys containing Se is lower than Pb-Sn binary alloys. And the higher of Se content, the lower of corrosion rate. The results demonstrated that Pb-Sn-Se alloys show the potential for application as the negative strap in VRLA batteries.

The Relationship Between Surface Roughness and Corrosion

2013 ◽  
Author(s):  
Alisina Toloei ◽  
Vesselin Stoilov ◽  
Derek Northwood
Keyword(s):  
Surface Roughness ◽  
Laser Ablation ◽  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Major Influence ◽  
Nickel Surface ◽  
General Corrosion ◽  
Corrosion Properties ◽  
Pitting Potential ◽  
Laser Ablation Method

There are different parameters which can affect electrochemical reactions such as type of electrolyte, velocity, temperature, oxidizing agents, impurities, anode material type and surface treatment. It has been shown that pre-treatment of working electrode (anode) through abrasion techniques is one of the most important parameters affecting on Tafel slopes and consequently corrosion rate. Surface roughness of the metal surface is a major influence on general corrosion, nucleation of metastable pitting and pitting potential as well. In this study different surface roughnesses were created on nickel surface by SiC papers and corrosion properties were compared. Electrochemical impedance spectroscopy (EIS) and profilometry tests were carried out on all the samples and the results were compared with another sample prepared through laser ablation method. Corrosion rate values were calculated and were compared with EIS results for all the samples and a trend in the effect of roughness on corrosion protection of nickel was introduced. SEM and 3D roughness images were taken and compared for all of the samples before and after corrosion tests. Different mechanisms were distinguished for samples created through different methods. The lower the roughness values, the more the corrosion resistance. Sample with patterns created through laser ablation method showed the best protection properties compared to other samples.

scholarly journals Investigation on the Effect of Thermal and Mechanical Treatment to the Offshore Corrosion Behavior of 6351 Aluminum Alloy in Red Sea Environments

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Yahya Ali Fageehi ◽  
Rajasekaran Saminathan
Keyword(s):  
Red Sea ◽  
Corrosion Behavior ◽  
Artificial Aging ◽  
Sea Water ◽  
Aging Treatment ◽  
Hardness Test ◽  
Al Alloy ◽  
Corrosion Properties ◽  
Mechanical Attrition ◽  
Peak Aged

This study investigates the effect of artificial aging treatment and mechanical attrition treatment on the corrosion behavior of 6351 Al alloy in Red Sea environment. The artificial aging of the alloy is carried out at temperature range 140°C–240°C in steps of 20°C for various time periods after the solution heat treatment at 530°C for 1 hour. Based on the hardness measurements, the aged specimens are categorized into three, namely, underaged, peak aged, and overaged. The as received alloy specimens are subjected to mechanical attrition treatment in a vacuum chamber using steel balls. Vickers hardness test reveals that there is a remarkable improvement in hardness of mechanical attrition treated specimens compared to that of aged specimens. The aged and mechanical attrition treated specimens were subjected to the corrosion test in Red Sea water using the Autolab instrument. The corrosion tests reveal that the peak-aged composite corrodes more in Red Sea water when compared to that of other groups of specimens. XRD measurements and SEM analysis are carried out to study the surface nature of attrition treated specimens. It is observed that the mechanical attrition treated specimens exhibit a nanocrystalline surface and lead to a decrease in corrosion resistance. However, the annealing of the alloy after attrition treatment optimizes the mechanical and corrosion properties of the alloy.

scholarly journals Corrosion Behavior of Mg-Al/TiC Composites in NaCl Solution

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
L. A. Falcon ◽  
E. Bedolla B. ◽  
J. Lemus ◽  
C. Leon ◽  
I. Rosales ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Base Alloy ◽  
Electrochemical Techniques ◽  
Al Alloy ◽  
Nacl Solution ◽  
The Matrix ◽  
Diffusion Phenomena ◽  
Lower Corrosion Rate

The corrosion behavior of TiC particles reinforced Mg-Al alloy in 3.5% NaCl solution has been evaluated using electrochemical techniques. Tested alloys included an Mg-9Al (Mg AZ91E) alloy with and without 56 wt. % TiC particles. Electrochemical techniques included potentiodynamic polarization curves, linear polarization resistance, electrochemical noise, and electrochemical impedance spectroscopy measurements. All techniques showed that the composite exhibited a lower corrosion rate than the base alloy. Evidence of galvanic effects that increased the composite corrosion rate was found between the matrix and the TiC particles. Additionally, the tendency to suffer from pitting corrosion was higher for the base alloy than that for the composite. Electrochemical impedance results showed the importance of adsorption/diffusion phenomena in both materials.

Corrosion Behavior of Alloy 22 and Ti Grade 7 in a Nuclear Waste Repository Environment

CORROSION ◽  
2004 ◽  
Vol 60 (8) ◽  
pp. 764-777 ◽  
Author(s):  
F. Hua ◽  
G. Gordon
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Nuclear Waste ◽  
Crevice Corrosion ◽  
Nuclear Waste Repository ◽  
General Corrosion ◽  
Corrosion Rates ◽  
Significant Difference ◽  
Alloy 22 ◽  
Waste Repository

Abstract Alloy 22 (UNS N06022) and Ti Grade 7 (UNS R52400) are the current corrosion-resistant materials of choice for fabricating the waste package outer barrier and the drip shield, respectively, for the proposed high-level nuclear waste repository at Yucca Mountain. In this work, the general and crevice corrosion behavior of annealed and welded Alloy 22 and Ti Grade 7 exposed in basic saturated water (BSW-12) for four and eight weeks at 60°C to 105°C were evaluated using the ASTM G78 method combined with surface analysis and statistical analysis of corrosion rate. The general corrosion rates for Alloy 22 and Ti Grade 7 were found to increase linearly with temperature but decrease with the exposure time. The mean corrosion rate was found to be 0.003 mpy (0.075 μm/y) at 60°C and 0.010 mpy (0.25μm/y) at 105°C for Alloy 22 and 0.008 mpy (0.20 μm/y) at 60°C and 0.022 mpy (0.56 μm/y) at 105°C for Ti Grade 7. No significant difference in corrosion behavior between the annealed and welded materials was observed. For both materials the surface imperfections inherited from materials processing did not seem to deteriorate the excellent corrosion resistance of the materials but might serve as the “traps” for corrosion products. The apparent activation energies for the temperature dependence of corrosion rates of Ti Grade 7 and Alloy 22 in BSW-12 environment were obtained as 25.3 (±5.5) KJ/mol and 23.7 (±4.5) KJ/mol, respectively. Although none of the materials was found susceptible to crevice corrosion under the test conditions, to conclude that these materials are immune to crevice corrosion in BSW-12 would require longer-term testing.

scholarly journals Corrosion Behavior of AlFeCrCoNiZrx High-Entropy Alloys in 0.5 M Sulfuric Acid Solution

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1471
Author(s):  
Yuhong Yao ◽  
Yaohua Jin ◽  
Wei Gao ◽  
Xiaoyu Liang ◽  
Jian Chen ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Potentiodynamic Polarization ◽  
General Corrosion ◽  
High Entropy Alloys ◽  
H2so4 Solution ◽  
High Entropy ◽  
Polarization Measurements ◽  
Selective Corrosion

AlCoCrFeNiZrx (x = 0, 0.1, 0.2, 0.3, and 0.5) high-entropy alloys (HEAs) were prepared by a non-consumable vacuum arc melting technology, and the microstructure and corrosion behavior were investigated by XRD, SEM, immersion tests, and electrochemical measurements. The results indicate that galvanic corrosion of the AlCoCrFeNiZrx alloys occurred in 0.5 M H2SO4 solution, and only 0.1 mol of the added Zr could greatly improve the corrosion resistance of the alloys. The corrosion properties of the AlCoCrFeNiZrx HEAs had similar change tendencies with the increase in the Zr content in the immersion tests, potentiodynamic polarization measurements, and electrochemical impedance analysis, that is, the corrosion resistance of the AlCoCrFeNiZrx alloys in a 0.5 M H2SO4 solution first increased and then decreased with the increase in the Zr content. The Zr0.1 alloys were found to have the best selective corrosion and general corrosion resistance with the smallest corrosion rate, whereas the Zr0.3 alloys presented the worst selective corrosion and general corrosion resistance with the highest corrosion rate from both the immersion tests and the potentiodynamic polarization measurements.

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