An Electrochemical Impedance Spectroscopy Study of Al-Zn and Al-Zn-Sn Alloys in Tropical Seawater

Isa, M. C.; Daud, Abdul Razak; Ahmad, Musheer; Daud, Muhamad; Shamsudin, Shaiful Rizam; Yati, Mohd Subhi Din; Muhammad, Mustafa

doi:10.4028/www.scientific.net/kem.510-511.284

Cited by 3 publications

(3 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The corrosion characteristics of the Al and Al-5 Mg coating is assessed by OCP measurement with immersion duration, and the results are shown in Figure 6. During initial periods of immersion, both coatings exhibited electropositive OCP attributed to the formation of native oxide [45][46][47] and yet not observed in XRD on the Al coating, while Al-5 Mg coating exhibited uniform morphology and a high contact angle that does not allow the solution to ingress into the coating. This result is corroborated by other authors [48,49].…”

Section: Open Circuit Potential (Ocp) Measurementsmentioning

confidence: 96%

Role of 5 wt.% Mg Alloying in Al on Corrosion Characteristics of Al-Mg Coating Deposited by Plasma Arc Thermal Spray Process

Jeong

Singh

2023

Materials

View full text Add to dashboard Cite

The corrosion of steel structures in coastal areas is a major issue. Therefore, in the present study, the protection against the corrosion of structural steel is carried out by depositing 100 μm thick Al and Al-5 Mg coatings using a plasma arc thermal spray process, immersing them in 3.5 wt.% NaCl solution for 41 days (d). To deposit such metals, one of the best known processes, arc thermal spray, is frequently used, but this process has severe defects and porosity. Thus, to minimize the porosity and defects of arc thermal spray, a plasma arc thermal spray process is developed. In this process, we used normal gas to create plasma instead of argon (Ar) and nitrogen (N2) with hydrogen (H) and helium (He). Al-5 Mg alloy coating exhibited uniform and dense morphology, where it reduced more than four times the porosity compared to Al, where Mg fills the voids of the coating, resulting in greater bond adhesion and hydrophobicity. The open circuit potential (OCP) of both coatings exhibited electropositive values due to the formation of native oxide in Al, while in the case of Al-5 Mg, the coating is dense and uniform. However, after 1 d of immersion, both coatings showed activation in OCP, owing to the dissolution of splat particles from the corner where the sharp edges are present in the Al coating, while Mg preferentially dissolved in the Al-5 Mg coating and made galvanic cells. Mg is galvanically more active than Al in the Al-5 Mg coating. Due to the capacity of the corrosion products to cover the pores and defects, both coatings stabilized the OCP after 13 d of immersion. The total impedance of the Al-5 Mg coating is gradually increased and is higher than the Al, which can be attributed to the uniform and dense coating morphology where Mg dissolves and agglomerates to form globular corrosion products and deposit over the surface, thereby causing barrier protection. The defect bearing corrosion products on Al coating led to the cause having a higher corrosion rate than the Al-5 Mg coating. A total of 5 wt.% mg in the Al coating improved the corrosion rate by a rate of 1.6 times compared to the pure Al in the 3.5 wt.% NaCl solution after 41 d of immersion.

show abstract

Section: Open Circuit Potential (Ocp) Measurementsmentioning

confidence: 96%

Role of 5 wt.% Mg Alloying in Al on Corrosion Characteristics of Al-Mg Coating Deposited by Plasma Arc Thermal Spray Process

Jeong

Singh

2023

Materials

View full text Add to dashboard Cite

show abstract

“…35 Sn is selected as an alternative activator for the Al sacrificial anodes 36 which depends on the added amount 3 and on the type of heat treatment that the alloy undergoes. [37][38][39][40][41][42] Khireche et al 3 have shown that 0.1% to 0.4% tin addition acts as Al-Zn alloy deactivator. This is due to the decrease of grain size, an increase of their density, and shift of the Al alloys potential to more negative values.…”

mentioning

confidence: 99%

“…Although indium is a suitable candidate for activation, it is also an expensive material. 36,41,42 An additional motivation for this choice concerns the corrosion products of Al-Zn-Mg alloys which are similar to those already present in seawater, thus preventing the pollution of marine life 62 and considered as eco-friendly sacrificial anodes. 63 The selected systems, Al-5%Zn-0.5%Sn and Al-5%Zn-0.5%Sn-2.6% Mg alloys are based on the precipitation and distribution of fine intermetallic phases in the α-Al matrix generated by heat treatment.…”

mentioning

confidence: 99%

Development of Al-5%Zn-0.5%Sn-2.6%Mg Alloy as Sacrificial Anode for Cathodic Protection of Steel in 3 wt.% NaCl Solution

Oulmas

Mameri

Boughrara

et al. 2021

J. Electrochem. Soc.

View full text Add to dashboard Cite

In this work, two aluminum alloys, Al-5Zn-0.5Sn and Al-5Zn-0.5Sn-2.6Mg, were prepared by melting in an induction furnace to be used as sacrificial anodes for cathodic protection of marine structures. The alloys are characterized by scanning electron microscopy mapping coupled to energy dispersive X-ray analysis, X-ray photoelectron spectroscopy and X-ray diffraction. Afterwards, the corrosion behavior was studied in 3 wt.% NaCl solution through immersion tests, potentiodynamic polarization, electrochemical impedance spectroscopy and weight-loss measurements. Results display that active dissolution of Al-5%Zn-0.5%Sn-2.6%Mg alloy and its quasi-uniform corrosion is associated with the major precipitates MgZn2 and Mg2Sn particles formed during the melting process. Galvanic coupling measurements over 45 d were carried out on both alloys. The sacrificial cathodic protection of both anodes was successful but the couple efficiency was greater for Al-Zn-Sn-Mg owing to its more negative corrosion potential and uniform dissolution.

show abstract

Deposition and corrosion studies of plasma arc thermal sprayed Zn and 85Zn–15Al films on steel surface

Lee

Singh

2022

J Mater Sci

View full text Add to dashboard Cite

An Electrochemical Impedance Spectroscopy Study of Al-Zn and Al-Zn-Sn Alloys in Tropical Seawater

Cited by 3 publications

References 39 publications

Role of 5 wt.% Mg Alloying in Al on Corrosion Characteristics of Al-Mg Coating Deposited by Plasma Arc Thermal Spray Process

Role of 5 wt.% Mg Alloying in Al on Corrosion Characteristics of Al-Mg Coating Deposited by Plasma Arc Thermal Spray Process

Development of Al-5%Zn-0.5%Sn-2.6%Mg Alloy as Sacrificial Anode for Cathodic Protection of Steel in 3 wt.% NaCl Solution

Deposition and corrosion studies of plasma arc thermal sprayed Zn and 85Zn–15Al films on steel surface

Contact Info

Product

Resources

About