Structural and corrosion characterization of pulse plated nanocrystalline zinc coatings

Electrodeposited Zinc Coatings for Biomedical Application: Morphology, Corrosion and Biological Behaviour

The improvement of biodegradable metals is currently an active and promising research area for their capabilities in implant manufacturing. However, controlling their degradation rate once their surface is in contact with the physiological media is a challenge. Surface treatments are in the way of addressing the improvement of this control. Zinc is a biocompatible metal present in the human body as well as a metal widely used in coatings to prevent corrosion, due to its well-known metal protective action. These two outstanding characteristics make zinc coating worthy of consideration to improve the degradation behaviour of implants. Electrodeposition is one of the most practical and common technologies to create protective zinc coatings on metals. This article aims to review the effect of the different parameters involved in the electrochemical process on the topography and corrosion characteristics of the zinc coating. However, certainly, it also provides an actual and comprehensive description of the state-of-the-art of the use of electrodeposited zinc for biomedical applications, focusing on their capacity to protect against bacterial colonization and to allow cell adhesion and proliferation.

Corrosion Behavior of ZnMn Coatings Magnetoelectrodeposited

The zinc–manganese alloy coatings have been obtained without and with superimposition of a 0.3 T magnetic field in a parallel direction to the working surface electrode. The electrodeposition during 30 min, for two applied potentials (E = −1.6 V/SCE and E = −1.8 V/SCE) in an electrochemical bath with the (Zn2+)/(Mn2+) concentration ratio equal to 0.5. The structural, the morphological, and the chemical composition characteristics of the deposits have been studied. It has been found that the applied potentials modify the structural properties of the deposits, η phase-rich deposits elaborated for E = −1.6 V/SCE, and MnZn3-rich deposits elaborated for E = −1.8 V/SCE. The magnetohydrodynamic convection favors the manganese content of the deposit. The corrosion behavior of these coatings has been analyzed in 3.5% NaCl solution by free corrosion potential measurements and electrochemical impedance spectroscopy. The different results show that the corrosion resistance of these zinc–manganese alloy coatings is linked to their structure, to their composition, and to the magnetic field amplitude used during the electrodeposition process.

Investigation on the Electrochemical Deposition of Nanocrystalline Zinc with Cationic Polyacrylamide (CPAM)-ZnSO4 Electrolyte

The electrochemical deposition of nanocrystalline zinc has high potential to deposit zinc coatings, which have improved wear and corrosion properties compared to conventional coating methods. Conventionally, two or more additives are used in the electrolyte for the formation nanocrystalline zinc; these electrolyte components are complex, and their maintenance is inconvenient, making it unstable and not suitable for industrial scale production. This paper proposes an electrochemical deposition technique for nanocrystalline zinc using a ZnSO₄ solution with cationic polyacrylamide (CPAM) as the unique additive. The results reveal that the cationic degree of CPAM has a significant influence on the deposition process and that the cationic degree of 20% enhances the electrolyte conductivity and improves the density of the deposited coating. The concentration of CPAM affects the electrolyte viscosity and conductivity. CPAM with a concentration of 20 g/L could simultaneously improve the electrolyte conductivity and maintain the viscosity at a low value, which promotes the formation of a bright deposited coating with a grain size of 87 nm. Additionally, the current density affects the grain structure of the deposited coating. With a current density of 0.5 A/dm², a dense coating with lamellar grains and a grain size of 54.5 nm was obtained, which has, and the surface roughness was reduced to 0.162 μm. Moreover, the corrosion resistant property of the deposited coating was also improved.

A Review on the Corrosion Behaviour of Nanocoatings on Metallic Substrates

Growth in nanocoatings technology is moving towards implementing nanocoatings in many sectors of the industry due to their excellent abilities. Nanocoatings offer numerous advantages, including surface hardness, adhesive strength, long-term and/or high-temperature corrosion resistance, the enhancement of tribological properties, etc. In addition, nanocoatings can be applied in thinner and smoother thickness, which allows flexibility in equipment design, improved efficiency, lower fuel economy, lower carbon footprints, and lower maintenance and operating costs. Nanocoatings are utilised efficiently to reduce the effect of a corrosive environment. A nanocoating is a coating that either has constituents in the nanoscale, or is composed of layers that are less than 100 nm. The fine sizes of nanomaterials and the high density of their ground boundaries enable good adhesion and an excellent physical coverage of the coated surface. Yet, such fine properties might form active sites for corrosion attack. This paper reviews the corrosion behaviour of metallic, ceramic, and nanocomposite coatings on the surface of metallic substrates. It summarises the factors affecting the corrosion of these substrates, as well as the conditions where such coatings provided required protection.

An Electrochemical Synthesis of Reduced Graphene Oxide/Zinc Nanocomposite Coating through Pulse-Potential Electrodeposition Technique and the Consequent Corrosion Resistance

Pulse-potential coelectrodeposition of reduced graphene oxide/zinc (rGO-Zn) nanocomposite coating is directly controlled upon a steel substrate from a one-pot aqueous mixture containing [GO−/Zn2+]δ+ nanoclusters. GO nanosheets are synthesized by modified Hummer’s approach while Zn cations are produced in the solution and deposited on GO nanosheets using anodic dissolution technique. Eventually, nanoclusters are reduced to rGO-Zn film through an electrochemical process. Chemical composition, surface morphology, and corrosion resistance of the thin film are characterized. Results show that the corrosion resistance of rGO-Zn coating is approximately 10 times more than the bare steel.

Challenges and strategies of surface modification of electrogalvanized coatings for electron microscopy analysis

Despite wide usage of electrogalvanized coatings in various applications, characterization studies on their micro/crystal structure, and the understanding of how they correspondingly affect the properties, such as corrosion, are rather limited. This is mainly attributed to some difficulties in preparing and examining the zinc coating layers, owing to their intrinsically low corrosion resistance and refined nano-scaled crystallite size. This study aims to examine such challenges systematically and propose some mitigation strategies. Particularly, sample preparation processes, including surface finishing for metallography and sample thinning processes are explored. Furthermore, a range of electron microscopy techniques, including scanning electron microscopy (SEM), electron back scattered diffractometry (EBSD), and transmission electron microscopy (TEM) are investigated in relation to the achievable clarity of microstructural details of electrogalvanized coatings.

Understanding the low corrosion potential and high corrosion resistance of nano-zinc electrodeposit based on electron work function and interfacial potential difference

The corrosion behaviors of coarse-grained and nanocrystalline zinc coatings and correlated the corrosion potential with electron stability are investigated.

Corrosion mechanism of nanocrystalline Zn–Ni alloys obtained from a new DMH-based bath as a replacement for Zn and Cd coatings

Nanocrystalline Zn–Ni alloys obtained from a DMH-based bath can be used as replacement of Zn and Cd coatings. The mechanism of better corrosion resistance of Zn–Ni alloys compared to Zn and Cd coatings was analyzed by XPS and EIS.

Synergistic effects of passivation treatment and nano-electrodeposition technologies on corrosion protection performance of the electrogalvanized steel

A theoretical model of the passive film formation mechanism on coarse-grained (a) and nanocrystalline (b) zinc coatings is proposed.

Research on the tribological behavior of a nanocrystalline zinc coating prepared by pulse reverse electrodeposition

The change of tribological behavior of zinc coatings with the reduction of grain size from micro to nano-scale is investigated.

Deciphering the formation mechanism of a protective corrosion product layer from electrochemical and natural corrosion behaviors of a nanocrystalline zinc coating

A hydrophobic protective corrosion product film (NC-1) with a nano-wire structure is formed on the surface of a nanocrystalline zinc coating.

Pulse reverse electrodeposition and characterization of nanocrystalline zinc coatings

A nanocrystalline zinc coating is produced by pulse reverse electrodeposition in a sulfate bath with polyacrylamide as the only additive and the mechanical, wear and corrosion resistance properties are evaluated.