Corrosion resistance of MoS2-modified titanium alloy micro-arc oxidation coating

doi:10.1016/j.surfcoat.2022.128127

Surface and Coatings Technology

Volume 433, 15 March 2022, 128127

https://doi.org/10.1016/j.surfcoat.2022.128127 Get rights and content

Highlights

•
Porous films were grown on marine Ti-6Al-4V alloys by micro-arc oxidation.
•
MoS₂ was wrapped by molten metal into the micro-arc oxidation coating.
•
The basic composition of the film was composed by anatase, rutile TiO₂ and a small amount of SiO₂.
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The addition of MoS₂ effectively improved the corrosion resistance of the coating.

Abstract

To improve the corrosion resistance of the Ti-6Al-4V alloy treated by micro-arc oxidation (MAO), molybdenum disulfide (MoS₂) particles were added into the electrolyte and a composite oxide coating was formed with different MoS₂ contents on the surface of Ti-6Al-4V alloy. A scanning electron microscope and a handheld roughness meter were used to analyze the surface morphology and roughness of the coating, and the corrosion performance of the MAO-treated Ti-6Al-4V alloy was analyzed by galvanic corrosion meter and electrochemical workstation. The results show that MoS₂ can be successfully incorperated into the coating and block the micropores during the process of micro-arc oxidation. Electrochemical experiments showed that the coating has a higher resistance and a lower corrosion rate, while in the galvanic experiment, the galvanic potential and galvanic current of the coating also decreased. Under the experimental conditions, the addition of MoS₂ can significantly improve the corrosion resistance of the MAO coating, and the best corrosion resistance is obtained when the addition amount is 4g/L, this will expand the marine applications of Ti-6Al-4V alloy.

Introduction

Ti-6Al-4V alloy is widely used in aerospace, medical equipment and chemical industries because of its special features such as good biocompatibility, superconductivity and shape memory [1], [2], [3]. However, Ti-6Al-4V alloy has poor wear resistance and low hardness, and its surface oxide coating is not continuous, which cannot achieve the same passivation protection as Al₂O₃ [4], [5], [6]. The working environment of marine titanium alloy is complex, biological corrosion and electrochemical corrosion are the main corrosion methods of titanium alloy ship hulls, of which electrochemical corrosion is more harmful, and surface treatment of titanium alloy is needed to make it meet the requirements of engineering use [7]. Here are many methods commonly used to improve the surface properties of titanium alloys, such as plasma spraying [8], physical vapor deposition (PVD) and chemical vapor deposition (CVD) [9], but the preparation process of these methods are complicated, the cost is relatively high, and the bonding force between the coating and the substrate is poor. As a new surface treatment technology, micro-arc oxidation is simple, efficient and environmentally friendly. Micro-arc oxidation of alloys with appropriate process parameters can achieve excellent surface properties [10], [11], [12], [13]. It not only prolongs the service life of key components, but also allows the alloys to withstand harsher service environments, resulting in better engineering applications [14], [15], [16]. These are difficult to achieve with other surface treatment technologies.

As we all know, the performance of the micro-arc oxidation coating mainly depends on the composition of the electrolyte [17], [18]. So far, the common electrolyte systems are phosphate [19], aluminate [20], and silicate-based electrolytes [21]. However, a single electrolyte system has its shortcomings, mixed electrolytes (such as phosphoric acid-silicic acid electrolyte) can be used to improve the performance of the micro-arc oxidation coating [22]. Recent studies have tried to add tungsten trioxide (WO₃), magnesium oxide (MgO) [23], cerium oxide (CeO₂) [24], and sodium stannate (Na₂SnO₃) [25] to the micro-arc oxidation electrolyte to improve the surface properties of the coating, just as their research shows that these additives can improve the corrosion resistance and wear resistance of the micro-arc oxidation coating. MoS₂ has now been used to improve the performance of micro-arc oxidation coatings [26], studies [27], [28] have shown that after adding MoS₂ in the micro-arc oxidation process of aluminum alloys, the resulting coating has a dense and smooth surface, and its corrosion resistance has been significantly improved.

In this work, different concentrations of MoS₂ were added to the phosphoric acid-silicic acid composite electrolyte in order to get the micro-arc oxidation coating with better corrosion resistance in a marine simulated environment.

Section snippets

Materials and device

The titanium alloy used for micro-arc oxidation is Ti6Al4V (non-ELI grade) with the main chemical composition (wt%): Al 5.5–6.8%, V 3.5–4.5%, Fe 0.3%, C 0.01%, O 0.03% and the balance of Ti. The Ti-6Al-4V alloy was laser cut into block specimens with a size of 20 × 15 × 3 mm. The sample was polished to smooth with #200 to #1800 water sandpaper to remove surface processing rust and oxide scale, and then ultrasonically cleaned with alcohol for 10 min to remove surface oil and impurities.

The

Effect of MoS₂ content on the MAO coating

It can be seen from Fig. 1 that the oxide coating in the basic electrolyte was porous. The discharge micropores with irregular shapes are uniformly distributed on the surface, and the largest micropore diameter exceeds 2 μm. With the increase of the amount of MoS₂, the size of the surface discharge micropores of the coating decreases to less than 1 μm. It can also be seen from the EDS results in Fig. 1 that as the amount of MoS₂ increases, the combination of MoS₂ and the coating becomes

Discussion

Electrocouple corrosion is the electrochemical corrosion that occurs when metals with different electrode potentials come into contact with each other in the same corrosive medium, and studies have shown that the three necessary conditions for the occurrence of electrocouple corrosion are [37]: the ion-conducting branches, the materials with different self-corrosive potentials, and the electron-conducting branches. In the electrochemical corrosion test, due to the action of the power source,

Conclusions

In this study, a micro-arc oxidation coating containing MoS₂ was successfully prepared on Ti-6Al-4V alloy by dispersing MoS₂ in a silicic acid-phosphoric acid composite salt solution. SEM examinations revealed that adding a small amount of MoS₂ will reduce the porosity and pore size of the coatings, while adding a large amount of MoS₂ will cause the blockage of the micro-arc discharge channel, forming sintered particles and increasing the roughness of the coating. The EDS and XRD results show

CRediT authorship contribution statement

X.W Chen: Investigation, Conducting a research and investigation process, specifically performing the experiments, or data/evidence collection, M.L Li: Investigation, Conducting a research and investigation process, specifically performing the experiments, or data/evidence collection, D.F Zhang: Visualization, L.P Cai: Writing – Review & Editing, P Ren: Writing – Review & Editing, J Hu:Writing – Review & Editing, D.D Liao: Writing – Original Draft.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

The author (Dr. Chen) is thankful to the National Natural Science Foundation of China (No 51774249) and the Open Fund (PLN2021-22) of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University) for carrying out this research investigation.

References (40)

G.Q. Xin et al.
Superhydrophobic Ti6Al4V alloy surface fabricated by laser micro-scanning to reduce adhesion and drag resistance
Surf. Coat. Technol.
(2020)
S.G. Zhang et al.
C-Al2O3 coatings prepared by cathode plasma electrolytic deposition on Ti6Al4V substrate for better high temperature oxidation resistance
Surf. Coat. Technol.
(2021)
R.Z. Xie et al.
Surface damage mitigation of Ti6Al4V alloy via micro arc oxidation for oil and gas exploitationapplication: characterizations of microstructure and evaluations on surface performance
Appl. Surf. Sci.
(2018)
Y.J. Wang et al.
Effect of microstructure evolution of Ti6Al4V alloy on its cavitation erosion and corrosion resistance in artificial seawater
J. Mater. Sci. Technol.
(2022)
P. Zhang et al.
Microstructure and tribological performance of CrTiSiCN coatings on 316L and TC4 in seawater
Tribol. Int.
(2021)
W.B. Dai et al.
Constitutive relations of micro-arc oxidation coated aluminum alloy
J. Surf. Coat. Technol
(2021)
H.B. Zhang et al.
The micro-arc oxidation (MAO) behaviors of in-situ TiB2/A201 composite
J. Appl. Surf. Sci.
(2017)
W.M. Xia et al.
Corrosion behavior of a sol-gel ZrO2 pore-sealing coating prepared on a micro-arc oxidized aluminum alloy
J. Ceram. Int.
(2019)
Q.Z. Chen et al.
Influence of graphene particles on the micro-arc oxidation behaviors of 6063 aluminum alloy and the coating properties
J. Appl. Surf. Sci.
(2017)
W. Yang et al.
Preparation and performance of alumina ceramic coating doped with aluminum nitride by micro arc oxidation
J. Ceram. Int.
(2020)

D. Dzhurinskiy et al.

Characterization and corrosion evaluation of TiO2:n-HA coatings on titanium alloy formed by plasma electrolytic oxidation

Surf. Coat. Technol.

(2015)

J.M. Wheeler et al.

Evaluation of micromechanical behaviour of plasma electrolytic oxidation (PEO) coatings on ti-6Al-4V

Surf. Coat. Technol.

(2010)

J.T. Wang et al.

Effect of electrolyte composition on the microstructure and bio-corrosion behavior of micro-arc oxidized coatings on biomedical Ti6Al4V alloy

J. Mater. Res. Technol.

(2020)

Y.L. Cheng et al.

Comparison of plasma electrolytic oxidation of zirconium alloy in silicate- and aluminate-based electrolytes and wear properties of the resulting coatings

Electrochim. Acta

(2012)

Q.B. Li et al.

Correlations between the growth mechanism and properties of micro-arc oxidation coatings on titanium alloy: effects of electrolytes

Surf. Coat. Technol.

(2017)

M. Kaseem et al.

Y, G, ko, stabilization of AZ31 mg alloy in sea water via dual incorporation of MgO and WO3 during micro-arc oxidation

J. Alloys Compd.

(2021)

Z.R. Zheng et al.

Corrosion behavior of a self-sealing coating containing CeO2 particles on pure mg produced by micro-arc oxidation

Surf. Coat. Technol.

(2020)

W. Yang et al.

Stable preparation and characterization of yellow micro arc oxidation coating on magnesium alloy

J. Alloys Compd.

(2018)

B.S. Lou et al.

Mechanical property and corrosion resistance evaluation of AZ31 magnesium alloys by plasma electrolytic oxidation treatment: effect of MoS2 particle addition

Surf. Coat. Technol.

(2018)

F. Xu et al.

Pore structure analysis and properties evaluations of fly ash-based geopolymer foams by chemical foaming method

Ceram. Int.

(2018)

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Full length articleCorrosion resistance of MoS2-modified titanium alloy micro-arc oxidation coating

Highlights

Abstract

Introduction

Section snippets

Materials and device

Effect of MoS2 content on the MAO coating

Discussion

Conclusions

CRediT authorship contribution statement

Declaration of competing interest

Acknowledgements

Surf. Coat. Technol.

Surf. Coat. Technol.

Appl. Surf. Sci.

J. Mater. Sci. Technol.

Tribol. Int.

J. Surf. Coat. Technol

J. Appl. Surf. Sci.

J. Ceram. Int.

J. Appl. Surf. Sci.

J. Ceram. Int.

Surf. Coat. Technol.

Surf. Coat. Technol.

J. Mater. Res. Technol.

Electrochim. Acta

Surf. Coat. Technol.

J. Alloys Compd.

Surf. Coat. Technol.

J. Alloys Compd.

Surf. Coat. Technol.

Ceram. Int.

Full length article
Corrosion resistance of MoS₂-modified titanium alloy micro-arc oxidation coating

Effect of MoS₂ content on the MAO coating