Corrosion Resistance of Al-12Si Coatings on AZ91 Magnesium Alloy Prepared through Flame Spray

2013 ◽  
Vol 765 ◽  
pp. 639-643 ◽  
Author(s):  
Pei Hu Gao ◽  
Jian Ping Li ◽  
Zhong Yang ◽  
Yong Chun Guo ◽  
Yan Rong Wang
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Coating Thickness ◽  
Corrosion Potential ◽  
Treatment Temperature ◽  
Phase Changes ◽  
Flame Spray ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium

In this study, Al-12Si alloy coatings with different thickness were prepared through flame spray on the surface of the AZ91 magnesium alloy to improve its corrosion resistance. The corrosion resistance was characterized through corrosion potential using electrochemical methods. The Al-12Si alloy coatings were heat treated at 100 °C, 200 °C and 300 °C for 6, 12, 18 and 24 hours. The effects of heat treatment temperature and time on the coatings’ corrosion resistance were discussed. It was found that there were no phase changes during the deposition of Al-12Si coatings through flame spray and heat treatment. The greater the coating thickness was, the higher the corrosion potential was. After annealing, the inner microstructure of the Al-12Si coating was densified furtherly and the annealed coatings had higher corrosion potential and better corrosion resistance. The coating annealed at 100 °C for 18 hours had the highest corrosion potential and the best corrosion resistance in the same coating thickness.

Ceria Coatings Prepared by Sol-Gel Approach on AZ91 Magnesium Alloy

2017 ◽  
Vol 898 ◽  
pp. 1369-1380 ◽  
Author(s):  
Hui Min Han ◽  
Dan Tong Wang ◽  
Hua Qian Yu ◽  
Min Zuo ◽  
Li Hong Wang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Sol Gel ◽  
Electrochemical Corrosion ◽  
Chemical Conversion ◽  
Corrosion Current ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium

The ceria coatings on AZ91 substrates were successfully synthesized by chemical conversion and the corrosion resistance of AZ91 samples with and without ceria coatings were evaluated by means of electrochemical corrosion in 3.5 wt.% NaCl solution. According to the parameters derived from the polarization date, the Icorr (the corrosion current density) values of the coated samples are smaller than that of bare one, indicating that the corrosion resistance of AZ91 alloys has been improved to some extent. The influence of fluoridated pretreatment, inter-layer heat treatment, sintering temperature and the layer of films on the performance of ceria coatings were also investigated. It was found that the inter-layer heat treatment has no influence on improving the anticorrosion resistance of AZ91 alloy. In comparison with the bare one, the Icorr of optimal sample is about 0.0219mA/cm2, which decreases by two orders of magnitude, indicating that the ceria coatings could significantly improve the corrosion resistance of AZ91 magnesium alloy.

scholarly journals Effects Of Aluminum Sputtering On The Corrosion Resistance Of AZ91 Alloy

2015 ◽  
Vol 60 (2) ◽  
pp. 953-955 ◽  
Author(s):  
Y. Ishibashi ◽  
M. Nose ◽  
M. Hatakeyama ◽  
S. Sunada
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Eds Analysis ◽  
Heat Treated ◽  
Film Forming ◽  
Az91 Magnesium ◽  
Aluminium Film

Abstract The corrosion resistance of a Magnesium alloy is low and needs to be improved. This research aimed at corrosion-resistance improvement by supatterd deposition aluminium film, which is formed on the surface of AZ91 Magnesium-alloy. Corrosion resistance performed polarization curve measurement, was evaluated in quest of the corrosion rate using the Tafel extrapolation method, and conducted surface observation and EDS analysis by SEM. Although corrosion resistance is not improved only by film forming because of defects in film, corrosion resistance is improved by heat treatment for 3 hours by 553K after sputtering. In the case of heat treated at 623K and 673K for 3 hours, magnesium diffuses through the alminium film and reached the surface of the film. Thus, heat treatment at high temperature degrade the corrosion resistance of the film. The optimization of heat treatment after sputtering is important in this method.

Effect of Heat Treatment of AZ91 Magnesium Alloy on the Electroless Ni-P Deposition

2018 ◽  
Vol 1148 ◽  
pp. 122-127 ◽  
Author(s):  
Charu Singh ◽  
S.K. Tiwari ◽  
Raghuvir Singh
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Electrochemical Impedance ◽  
Cast Alloy ◽  
Az91 Magnesium Alloy ◽  
Heat Treated ◽  
Az91 Magnesium ◽  
Electroless Ni

Magnesium alloys are excellent choice for automobile, aerospace, and computer components owing to their light weight, unique physical and mechanical properties. However, poor corrosion resistance has restricted their applications in aggressive environments. The surface coating is one of the viable options to reduce the susceptibility of magnesium alloys to corrosion. The present study focuses on the effect of heat treatment of AZ91 magnesium alloy, for different durations at 400 °C, prior to electroless Ni-P deposition on corrosion resistance. The microstructure and elemental analysis of the heat-treated specimens are performed using SEM and EDS techniques respectively. It is observed that the duration of heat treatment has a significant effect on the surface morphology and microstructure of the alloy. The precipitates in the cast alloy (enriched with Mg and Al) fragmented and the transformed into a new Al and Zn rich phase, after 12 h heat treatment. The dissolution of precipitates, however, observed on heating further to 24 h and exhibited relatively a lesser corrosion current density. The dense electroless Ni-P deposition is formed on the alloy heat treated for 24 h. The corrosion behavior of the single Ni-P layer on the heat treated (for 12 h) and untreated alloy show a marked deterioration, as investigated by the anodic polarization and electrochemical impedance spectroscopy (EIS) techniques. Relatively a better corrosion performance is seen for the double-layer Ni-P deposition. The duplex layer coatings on the as cast and heat treated for 24 h at 400 °C substrates showed an improved corrosion resistance compared to that on the 12 h heat treated substrate.

Effects of Erbium Addition on the Corrosion Resistance and Microstructure of AZ91 Magnesium Alloy

2011 ◽  
Vol 194-196 ◽  
pp. 1221-1224 ◽  
Author(s):  
Zhong Jun Wang ◽  
Yang Xu ◽  
Jing Zhu
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Discontinuous Precipitation ◽  
Az91 Magnesium Alloy ◽  
Continuous Precipitation ◽  
Az91 Magnesium ◽  
Precipitation Phase

The microstructures and corrosion resistance of AZ91 and AZ91+0.5 wt.% erbium (Er) magnesium alloys were studied, respectively. The results show that the Er addition in scrap AZ91 magnesium alloy can improve the corrosion resistance, markedly. The discontinuous precipitation phase (DPP) for Mg17Al12was retarded and the amount of DPP was decreased by 41% due to the formation of Al8ErMn4phase during solidification. The amount of continuous precipitation phase (CPP) in grains was decreased by 8% because of the formation of Al7ErMn5phase during solidification.

Corrosion and Protection of Magnesium Alloys

2015 ◽  
Vol 1120-1121 ◽  
pp. 1078-1082 ◽  
Author(s):  
Yang Yang Lv ◽  
Ling Feng Zhang
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Automotive Industry ◽  
Physical And Mechanical Properties ◽  
Current Status ◽  
Strain Rates ◽  
Metallic Materials ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium

Magnesium alloy as a green material in the 21st century, because of its excellent physical and mechanical properties of metallic materials as an ideal in the automotive industry, electronic industry and aviation, aerospace and other industries[1]. However, poor corrosion resistance of magnesium alloys become an important issue hinder application of magnesium alloys[2]. So magnesium alloy corrosion problems and the current status of research paper reviews several magnesium alloy protection methods at home and abroad, and also highlighted with our latest laser shock (LSP) study of AZ91 magnesium alloy at high strain rates of corrosion resistance results.

Influence of SiC Content and Heat Treatment on the Corrosion Resis-Tance and Oxidation Resistance of Ni-P-SiC Composite Coating

2015 ◽  
Vol 817 ◽  
pp. 479-483
Author(s):  
Pan Li ◽  
Wan Chang Sun ◽  
Jun Gao ◽  
Quan Zhou ◽  
Pei Zhang
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Composite Coating ◽  
Oxidation Resistance ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
Treatment Temperature ◽  
Micro Hardness ◽  
Resis Tance ◽  
P Matrix

Ni-P alloy and SiC micron particles were codeposited on Q235 steel by electroless plating. The composition, microstructure, micro-hardness, corrosion resistance and oxidation resistance of the composite coating were studied. The results revealed that the deposited composite coating shows dispersed SiC particles and continuous Ni-P matrix. When the content of SiC was 8g/L and the heat treatment temperature was 300°C, the corrosion potential and corrosion current of Ni-P-SiC coating were-0.292V, and 8.2×10-7 A/cm2, respectively, while those of Ni-P composite coating were-0.501V, and 4.2×10-5 A/cm2, respectively. Ni-P-SiC composite coating with high content of SiC exhibits better oxidation resistance than Ni-P coating.

Effects of heat treatment on the wear behavior of surfacing AZ91 magnesium alloy

2017 ◽  
Vol 32 (11) ◽  
pp. 2161-2168 ◽  
Author(s):  
Qingqiang Chen ◽  
Kaiyue Li ◽  
Yuyang Liu ◽  
Zhihao Zhao ◽  
Kai Tao ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Magnesium Alloy ◽  
Wear Behavior ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium ◽  
Image Position

Abstract

Corrosion Resistance of RE-AZ91 Magnesium Alloys

2014 ◽  
Vol 933 ◽  
pp. 66-70
Author(s):  
Jun Jie Yang ◽  
Yao Li ◽  
Ping Xue
Keyword(s):  
Tensile Strength ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Mg Alloy ◽  
Constant Voltage ◽  
High Tensile Strength ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium ◽  
Good Heat Resistance ◽  
Good Heat

Rare Earth (RE) were added to industrial AZ91 magnesium alloy, so that RE-AZ91 Mg alloy was produced by the process of die casting, so as to study the effect of RE on corrosion resistance and tensile strength of Mg alloy. The experiment results show that RE addition could improve the tensile strength and corrosion resistance of magnesium alloy at a certain amount of RE. RE-AZ91 had a good heat resistance, corrosion resistance at a high temperature or in the environment applied constant voltage, with a high tensile strength.

scholarly journals Improvement of AZ91 Alloy Corrosion Properties by Duplex NI-P Coating Deposition

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1357 ◽  
Author(s):  
Jaromír Wasserbauer ◽  
Martin Buchtík ◽  
Jakub Tkacz ◽  
Stanislava Fintová ◽  
Jozef Minda ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Az91 Alloy ◽  
Neutral Salt ◽  
Az91 Magnesium Alloy ◽  
Corrosion Properties ◽  
Az91 Magnesium

The corrosion behavior of duplex Ni-P coatings deposited on AZ91 magnesium alloy was studied. The electroless deposition process of duplex Ni-P coating consisted in the preparation of low-phosphorus Ni-P coating (5.7 wt.% of P), which served as a bond coating and high-phosphorus Ni-P coating (11.5 wt.% of P) deposited on it. The duplex Ni-P coatings with the thickness of 25, 50, 75 and 100 µm were deposited on AZ91 magnesium alloy. The electrochemical corrosion behavior of coated AZ91 magnesium alloy was investigated by electrochemical impedance spectroscopy and potentiodynamic polarization method in 0.1 M NaCl. Obtained results showed a significant improvement in the corrosion resistance of coated specimens when compared to uncoated AZ91 magnesium alloy. From the results of the immersion tests in 3.5 wt.% NaCl, 10% solution of HCl and NaOH and 5% neutral salt spray, a noticeable increase in the corrosion resistance with the increasing thickness of the Ni-P coating was observed.

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