Corrosion Behavior of MAO-Treated Magnesium Alloy in Hank’s Solution

2011 ◽  
Vol 236-238 ◽  
pp. 1954-1957 ◽  
Author(s):  
Hong Chen ◽  
Jian Min Hao ◽  
Dong Xiao Li ◽  
Lian Ping Li

In this paper, the magnesium alloy AZ91D as biological implant material was treated by micro-arc oxidation. The effects on the coating growth of oxidation time and terminal voltages in zirconium solution and silicate solution were investigated respectively. Immersion and electrochemical tests were applied to study the corrosion behavior of AZ91D alloy in Hank’s solution. The results revealed that the coating thickness increases and the corrosion rate in immersion test decreases as the extension of oxidation time and the rising of terminal voltage. The corrosion rate of the alloy in the immersion test treated in zirconium solution varies with the terminal voltages and that in silicate solution depends on the coating thickness. In the polarization curves test, the corrosion current of the MAO treated alloy is two orders of magnitude lower than that of original samples and the polarization curves in zirconium solution show bigger anode and cathode polarizability which indicates that the MAO coating has a strong blocking effect of the corrosion. The corrosion resistance of MAO treated magnesium AZ91D improves significantly.

2016 ◽  
Vol 849 ◽  
pp. 121-127
Author(s):  
Ya Jie Chu ◽  
Xin Chen Han ◽  
Zong Hui Yang ◽  
Xiao Quan Li

The extruded AZ31B magnesium alloy plates of 4 mm thickness were butt welded using gas tungsten arc welding (GTA) process. The microstructure and corrosion behavior of the hot compressed welds were evaluated by conducting immersion test in NaCl solution at different immersion time and chloride ion concentrations. The specimens were exposed to immersion in order to characterize their corrosion rates. The corrosion morphology and pit morphology observation was carried out by scanning electron microscopy (SEM). The results showed that the corrosion rate of hot compressed magnesium alloy welds decreased with the increase in immersion time and the corrosion rate increased with the increase in chloride ion concentration, and the corrosion morphology was predominantly influenced by the distribution of β-phase.


2012 ◽  
Vol 268-270 ◽  
pp. 330-335
Author(s):  
Ying Ma ◽  
Zhong Ming Zhang ◽  
Ting Wang ◽  
Yang Guo ◽  
Chun Jie Xu

The corrosion behavior of extruded Mg-1Ca-0.5Mn(weight percent)alloy in 0.9% sodium chloride water solution was investigated by using mass-loss measurement and electrochemical method. The results show that filiform corrosion and pitting corrosion occur during immersion corrosion process. The average corrosion rate gradually decreases as immersion time increases; it is 0.53 mm/a after immersion at 37°C for 11 days. The corrosion current density icorr and corrosion potential Ecorr of the alloy is 0.042 mA/cm2 and -1.60V, respectively. The instantaneous corrosion rate is 0.88 mm/a. Mg-1Ca-0.5Mn alloy erodes by continuous dissolution. The corrosion product Mg(OH)2 layer surrounding the magnesium alloy can decrease the corrosion rate. The erosion process of the magnesium alloy is controlled by cathodic diffusion.


2015 ◽  
Vol 819 ◽  
pp. 331-336
Author(s):  
H.Y. Tok ◽  
Esah Hamzah ◽  
Hamid Reza Bakhsheshi-Rad

Magnesium and its alloys have great potential as biodegradable metallic implant materials with good mechanical properties. However, the poor corrosion rate and the production of hydrogen during degradation hindered its application. Binary alloy, Mg-3Ca and ternary alloy, Mg-3Ca-3Zn alloy were studied to investigate their bio-corrosion properties. Microstructure evolution and surfaces of corroded alloys were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The bio-corrosion behavior of the Mg alloys was investigated using immersion and electrochemical tests in Kokubo solution. Microstructural analysis showed that binary Mg-3Ca alloy consisted of α-Mg and Mg2Ca phases and ternary Mg-3Ca-3Zn alloy consisted of α-Mg, Ca2Mg6Zn3 and Mg2Ca phases. These phases had significant effect on the corrosion resistant of the alloy. Electrochemical test showed an improvement in ternary alloys where the corrosion current density reduced from 0.497 mA/cm2 in Mg-3Ca to 0.312 mA/cm2 in Mg-3Ca-3Zn alloy. Ternary Mg-3Ca-3Zn showed significant lower corrosion rate (1.1 mg/cm2/day) compared to binary Mg-3Ca (5.8 mg/cm2/day) alloy after 14 days immersion test.


2012 ◽  
Vol 19 (03) ◽  
pp. 1250025 ◽  
Author(s):  
JOTHI SUDAGAR ◽  
RUAN DEWEN ◽  
YAQIN LIANG ◽  
RASU ELANSEZHIAN ◽  
JIANSHE LIAN

Influence of surfactants on the corrosion properties of chromium-free electroless nickel deposit were investigated on AZ91D magnesium alloy. The corrosion tests were carried out by immersion test (1 M HCl) and electrochemical polarization test (3.5 wt% NaCl ). The surfactants in the electroless nickel bath increases the corrosion resistance properties of the deposit on the magnesium alloy. In addition, smoothness and amorphous plus nano-crystalline phase were increased and accounted for the significant corrosion resistance. As a consequence, the corrosion potential moved towards the positive direction and the corrosion current density decreased. The immersion tests also provided the same trend as that of electrochemical polarization test. On the whole, the study concluded that corrosion resistance was enhanced by including a surfactant in the electroless deposits on magnesium alloy.


2015 ◽  
Vol 814 ◽  
pp. 132-136 ◽  
Author(s):  
Xian Yang Hua ◽  
Mei Feng He ◽  
Xiao Qin Zhou

Magnesium is one of the elements necessary for the body, is the man behind the body’s content of potassium ions within the cell are involved in a series of metabolic processes in vivo, including the formation of bone cells , acceleration of bone healing ability. Resulting from the good mechanical properties and biocompatibility, magnesium alloy is used in medical intervention material, but the high corrosion rate of magnesium alloys is the main drawback to their widespread use, especially in biomedical applications. There is a need for developing new coatings that provide simultaneously corrosion resistance and enhanced biocompatibility. In this work the medical magnesium alloy surface are dipped and coated with polylactic acid, so that obtain a dense uniform polylactic acid coating. And the corrosion resistance of the coating is studied in order to obtain controlled degradable and corrosion resisted magnesium alloy biological material. This paper mainly studies the influence of different concentrations of polylactic acid coating on AZ91D magnesium alloy corrosion resistance. The coated samples were immersed in Hank’s solution and the coating performance was studied by electrochemical impedance spectroscopy and scanning electron microscopy. This research is about the influence of the coating on the corrosion resistance of magnesium alloy through the open circuit potential, polarization curves, electrochemical impedance spectroscopy and Mott-Schottky. The results confirmed that the polylactic acid slow down the corrosion rate of AZ91D magnesium alloys in Hank’s solution. And along with the increase of poly lactic acid concentration, the corrosion resistance of magnesium alloys is improved. There is a wide variation of the corrosion morphology magnesium alloy AZ91D specimens after the surface modification using polylactic acid coating, compared with the unmodified.


2021 ◽  
Vol 22 (15) ◽  
pp. 8301
Author(s):  
Iryna Kozina ◽  
Halina Krawiec ◽  
Maria Starowicz ◽  
Magdalena Kawalec

Chitosan coatings are deposited on the surface of Mg20Zn magnesium alloy by means of the spin coating technique. Their structure was investigated using Fourier Transform Infrared Spectroscopy (FTIR) an X-ray photoelectron spectroscopy (XPS). The surface morphology of the magnesium alloy substrate and chitosan coatings was determined using Scanning Electron Microscope (FE-SEM) analysis. Corrosion tests (linear sweep voltamperometry and chronoamperometry) were performed on uncoated and coated magnesium alloy in the Hank’s solution. In both cases, the hydrogen evolution method was used to calculate the corrosion rate after 7-days immersion in the Hank’s solution at 37 °C. It was found that the corrosion rate is 3.2 mm/year and 1.2 mm/year for uncoated and coated substrates, respectively. High corrosion resistance of Mg20Zn alloy covered by multilayer coating (CaP coating + chitosan water glass) is caused by formation of CaSiO3 and Ca3(PO4)2 compounds on its surface.


Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1552
Author(s):  
Chenxi Yang ◽  
Nikhil Gupta ◽  
Hanlin Ding ◽  
Chongchen Xiang

The improvement in corrosion resistance of WE43 was well realized by heat treatment. To study the influence of microstructure on the corrosion behavior of WE43 in as-cast and heat-treated conditions, an immersion test was employed with as-cast and heat-treated samples in the 3.5% NaCl solution. The corrosion rate and change of morphology were recorded and the corrosion behavior was further investigated by scanning electron microscopy (SEM). The results indicated that the corrosion rate of the WE43 alloy decreased after heat treatment. It was observed that the eutectic gradually damages the protective film on the surface of the as-cast WE43 in the process of corrosion, which further increases the corrosion rate. The Zr-rich phase formed a domed structure resulting in the adjacent area being further corroded. The Y-rich phase has little effect on the corrosion reaction.


2021 ◽  
Vol 882 ◽  
pp. 35-49
Author(s):  
A.D. Vishwanatha ◽  
Bijayani Panda ◽  
J.N. Balaraju ◽  
Preeti Prakash Sahoo ◽  
P. Shreyas

Corrosion behavior of three carbon steels with increasing galvanized coating thickness of 5.6, 8.4 and 19.2 μm named as T1, T2 and T3, respectively, was studied by immersion test, potentiodynamic polarization and electrochemical impedance spectroscopy in freely aerated 3.5% NaCl solution. The major phase in the corrosion product of all the samples after immersion test was found to be zincite, as determined by X-Ray Diffraction and Fourier Transform Infrared Spectroscopy techniques. The corrosion product on sample T1was well adhered and was compact in most regions. Samples T2 and T3 showed porous and non-adherent growth of corrosion product. Corrosion rates were found to increase with increasing coating thickness. The impedance provided by the coating as well as the substrate was the highest for the sample with thinnest coating (T1). The early exposure of the underlying steel in sample T1 resulted in higher corrosion resistance, which was probably due to the combined effect of zinc corrosion products and Fe-Zn alloy layer. Higher amount of protective γ-FeOOH as well as compact corrosion product could have also improved the corrosion resistance of sample T1. Although the average uniform corrosion resistance was higher for T1, the localized pitting corrosion was also observed, probably due to the thin galvanized layer.


2014 ◽  
Vol 554 ◽  
pp. 213-217 ◽  
Author(s):  
M.S. Noor Idora ◽  
M.M. Rahman ◽  
M. Ismail ◽  
W.B. Wan Nik

The application of zinc coating as a protective film to the mild steel against corrosion attack in atmospheric and seawater environment was studied. The objective of this study is to evaluate the corrosion performance of mild steel coated by different thickness of zinc under salt spray and also immersion test. The corrosion measurement test was performed by weight loss and potentiodynamic polarization. From the experimental study, it was found that the corrosion rate of mild steel is inversely proportional to the zinc coating thickness. The result also showed that the corrosion rate of mild steel in the salt spray test is higher than the immersion test.


2013 ◽  
Vol 850-851 ◽  
pp. 1326-1330 ◽  
Author(s):  
Seng Wang ◽  
Shu Jun Gao ◽  
Zhi Zhong Li ◽  
Ya Bo Hu ◽  
Hong Liang Ji ◽  
...  

The corrosion behavior of typical grounding materials Zn and Cu in Shanbei soil solution was studied by immersion test technique, galvanic corrosion current measurement and simulated stray current test. The results showed that Zn was seriously corroded with the corrosion product of ZnCO3, while Cu was slightly corroded with the main rust of Cu2(OH)2CO3 and copper oxides. The corrosion of Zn was accelerated and Cu was protected when coupled them together. Stray current can significantly increase the corrosion process of both Zn and Cu.


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