Sacrificial Thermally Sprayed Aluminium Coatings for Marine Environments: A Review

Syrek-Gerstenkorn, Berenika; Paul, Shiladitya; Davenport, Alison J.

doi:10.3390/coatings10030267

Cited by 38 publications

(16 citation statements)

References 71 publications

(73 reference statements)

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“…Disadvantages of galvanization compared to thermal spraying processes are the limitation of the component dimensions to the size of the used electroplating as well as the formation of brittle Fe-Zn intermetallic phases [ 1 ], which are known to reduce the mechanical performance. In comparison, thermal spraying introduces less heat during the process and is less limited in terms of component dimensions [ 7 ]. Nevertheless, thermal sprayed coatings have higher porosity than galvanic coatings, a lamellar structure and thermally or kinetically induced residual stresses [ 8 ].…”

Section: Introductionmentioning

confidence: 99%

Fatigue Assessment of Twin Wire Arc Sprayed and Machine Hammer-Peened ZnAl4 Coatings on S355 JRC+C Substrate

et al. 2022

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Structural elements for applications in maritime environments, especially offshore installations, are subjected to various stresses, such as mechanical loads caused by wind or waves and corrosive attacks, e.g., by seawater, mist and weather. Thermally sprayed ZnAl coatings are often used for maritime applications, mainly due to good corrosion protection properties. Machine hammer peening (MHP) has the potential to increase fatigue and corrosion fatigue resistance of ZnAl coatings by adjusting various material properties such as hardness, porosity and roughness. This study investigates the fatigue behavior of twin wire arc sprayed and MHP post-treated ZnAl4 coatings. Unalloyed steel (S355 JRC+C) was selected as substrate material and tested as a reference. MHP achieved the desired improvements in material properties with increased hardness, decreased roughness and uniform coating thickness. Multiple and constant amplitude tests have been carried out to evaluate the fatigue capability of coating systems. In the high cycle fatigue regime, the additional MHP post-treatment led to an improvement of the lifetime in comparison to pure sandblasted specimens. The surface was identified as a crack initiation point. ZnAl coating and MHP post-treatment are suitable to improve the fatigue behavior in the high cycle fatigue regime compared to uncoated specimens.

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Section: Introductionmentioning

confidence: 99%

Fatigue Assessment of Twin Wire Arc Sprayed and Machine Hammer-Peened ZnAl4 Coatings on S355 JRC+C Substrate

et al. 2022

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“…Furthermore, sol-gel coatings have been shown to be good alternatives to hazardous and carcinogenic chromate coatings for metallic substrates, 4,6 and finite-lifetime sacrificial coatings which use another metal with lower electrode potential to keep the underlying substrate corrosion free by sacrificing itself. [7][8] Recently, there has been a great interest in developing hybrid sol-gel coatings. Hybrid inorganic-organic solgel coatings were established by attaching titanium or zirconium alkoxides to the silica matrix and it was shown to have improved adhesion, specifically on Magnesium substrate.…”

Section: Chapter 1: Introductionmentioning

confidence: 99%

Scalable Corrosion-Resistant Coatings for Thermal Applications

Khodakarami

Zhao

Rabbi

et al. 2021

ACS Appl. Mater. Interfaces

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Corrosion of metallic substrates is a problem for a variety of applications. Corrosion can be mitigated with the use of an electrically insulating coating protecting the substrate. Thick millimetric coatings, such as paints, are generally more corrosion-resistant when compared to nanoscale coatings. However, for thermal systems, thick coatings are undesirable due to the resulting decrease in the overall heat transfer stemming from the added coating thermal resistance. Hence, the development of ultrathin (<10 μm) coatings is of great interest. Ultrathin inorganic silicon dioxide (SiO2) coatings applied by sol–gel chemistries or chemical vapor deposition, as well as organic coatings such as Parylene C, have great anticorrosion performance due to their high dielectric breakdown and low moisture permeability. However, their application to arbitrarily shaped metals is difficult or expensive. Here, we develop a sol–gel solution capable of facile and controllable dip coating on arbitrary metals, resulting in a very smooth (<5 nm roughness), thin (∼3 μm), and conformal coating of dense SiO2. To benchmark our material, we compared the corrosion performance with in-house synthesized superhydrophobic aluminum and copper samples, Parylene C-coated substrates, and smooth hydrophobic surfaces functionalized with a hydrophobic self-assembled monolayer. For comparison with state-of-the-art commercial coatings, copper substrates were coated with an organo-ceramic SiO2 layer created by an elevated temperature and atmospheric pressure metal organic chemical vapor deposition process. To characterize corrosion performance, we electrochemically investigated the corrosion resistance of all samples through potentiodynamic polarization studies and electrochemical impedance spectroscopy. To benchmark the coating durability and to demonstrate scalability, we tested internally coated copper tubes in a custom-built corrosion flow loop to simulate realistic working conditions with shear and particulate saltwater flow. The sol–gel and Parylene C coatings demonstrated a 95% decrease in corrosion rate during electrochemical tests. Copper tube weight loss was reduced by 75% for the sol–gel SiO2-coated tubes when seawater was used as the corrosive fluid in the test loop. This work not only demonstrates scalable coating methodologies for applying ultrathin anticorrosion coatings but also develops mechanistic understanding of corrosion mechanisms on a variety of functional surfaces and substrates.

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“…In addition, the intense heating during this process can lead to the formation of brittle Fe-Zn intermetallic phases [8], which can negatively influence the corrosion fatigue behavior of the components. Thermal spraying such as Twin Wire Arc Spraying (TWAS), on the other hand, introduces significantly less heat into the components, imposes minor restrictions on the dimensions of components, and can be applied on-site [9]. Compared to other spraying techniques like cold spraying, flame spraying or plasma spraying, TWAS allows the highest deposition rates and, therefore, the lowest process times and costs [10].…”

Section: Introductionmentioning

confidence: 99%

Thermally Assisted Machine Hammer Peening of Arc-Sprayed ZnAl-Based Corrosion Protective Coatings

Wirtz

Abdulgader

Milz

et al. 2021

JMMP

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Structural elements of offshore facilities, e.g., offshore wind turbines, are subject to static and dynamic mechanical and environmental loads, for example, from wind, waves, and corrosive media. Protective coatings such as thermal sprayed ZnAl coatings are often used for protection, mainly against corrosive stresses. The Machine Hammer Peening (MHP) process is an innovative and promising technique for the post-treatment of ZnAl coating systems that helps reducing roughness and porosity and inducing compressive residual stresses. This should lead to an enhancement of the corrosion fatigue behavior. In this paper, the effect of a thermally assisted MHP process was investigated. The softening of the coating materials will have a direct effect on the densification, residual porosity and the distribution of cracks. The investigation results showed the influence of thermally assisted MHP on the surface properties, porosity, residual stresses, and hardness of the post-treated coatings. The best densification of the coating, i.e., the lowest porosity and roughness and the highest compressive residual stresses, were achieved at a process temperature of 300 °C. A further increase in temperature on the other hand caused a higher porosity and, in some cases, locally restricted melting of the coating and consequently poorer coating properties.

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Sacrificial Thermally Sprayed Aluminium Coatings for Marine Environments: A Review

Cited by 38 publications

References 71 publications

Fatigue Assessment of Twin Wire Arc Sprayed and Machine Hammer-Peened ZnAl4 Coatings on S355 JRC+C Substrate

Fatigue Assessment of Twin Wire Arc Sprayed and Machine Hammer-Peened ZnAl4 Coatings on S355 JRC+C Substrate

Scalable Corrosion-Resistant Coatings for Thermal Applications

Thermally Assisted Machine Hammer Peening of Arc-Sprayed ZnAl-Based Corrosion Protective Coatings

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