Corrosion Resistance Of Zn Research Articles

Application of Small- and Ultra-Small-Angle Neutron Scattering for the Characterization of Mechanically Plated Coatings

Post-mechanical plating heat treatment induces the formation of an iron–zinc (Fe-Zn) rich intermetallic layer between Zn and ZnSn coatings and the substrate. Despite increased outer coating porosity, the corrosion resistance of Zn- and ZnSn-coated steels significantly improves after heat treatment, attributed to the formation of intermetallic phases. This study employs small- and ultra-small-angle neutron scattering (SANS and USANS) to investigate the behavior of mechanically plated Zn and ZnSn coatings pre- and post-heat treatment. In the presence of a relatively thick steel substrate, strong multiple scattering occurs. However, by identifying a specific high Q-range region where multiple scattering is negligible, we reveal small but significant differences. Porod’s slopes, denoted as ‘n’, are calculated for uncoated steel, and Zn- and ZnSn-coated steels (both with and without heat treatment). These slope values reflect contributions from different interfaces on the particles’ surface roughness. Despite the challenges of multiple scattering, our findings offer valuable insights into coatings’ behavior. The study lays a foundation for future investigations into coating behavior using SANS/USANS techniques.

Effect of Condensation Product on the Electrochemical Behaviour and Corrosion Resistance of Zn and Zn-Ni Deposits

Electrodeposition of Zn and Zn-Ni deposits were performed on steel substrates under various conditions from acid sulphate baths in presence of condensation product of 3, 4, 5-trimethoxybenzaldehyde and serine (TMBS). The electrochemical behavior of deposits was studied by polarization and electrochemical impedance techniques. The Zn-Ni-bright deposits obtained from the acid sulphate bath at 4 Adm-2 showed a lower corrosion current (Icorr) and a less negative corrosion potential (Ecorr) compared to Zn-dull, Zn-Ni-dull and Zn-bright deposits. The surface morphology and phase structure of the deposits was studied by Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis.

Organic-inorganic composite passivation and corrosion resistance of zinc coated NdFeB magnets

An organic-inorganic composite passivation of Zn coated NdFeB magnets was carried out using Ce-containing compound and organosilane as source materials. Effects of organosilane content on the microstructure of composite passivation layer were analyzed, and the corrosion resistance and corrosion mechanism of the passivated Zn/NdFeB specimens were deeply studied. Composition, elemental distribution, phase structure and morphology of the specimens were characterized by X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy. The corrosion resistance of the specimens was studied by polarization curves, electrochemical impedance spectroscopy, neutral salt spray text and mass gain test. Results show that adding an appropriate amount of organosilane during the passivating process can form a passivation layer composed of Ce, Si, and O. The optimized Zn(CS-1)/NdFeB achieves the longest NSS time of 840 h, which is twice that of Zn(Ce-5)/NdFeB specimens. Organosilane can build a framework for the passivation layer and make the passivation layer more compact. During the corrosion process, the corrosion medium invasion path is long due to the support of the organosilane frame on the surface, so the corrosion resistance of Zn(CS)/NdFeB is greatly enhanced.

Hardness and corrosion resistance of Zn−Mn/Al2O3 composite coatings produced by electrochemical deposition

The aim of this study is development and characterization of the novel Zn-Mn/Al2O3 composite coatings. The coatingswere electrodeposited with constant current density on steel, from chloride solution, without any commercial additives. TheZn−Mn alloy coatings that show high corrosion resistance, may be used in future as an alternative to cadmium coatings.However, the pure Zn and Zn alloy coatings are characterized with poor mechanical properties. Therefore, in this work thealumina particles were incorporated into the Zn-Mn matrix, and the hardness and corrosion resistance of the obtainedcomposite coatings were tested. The mechanical and ultrasound agitation were used to achieve good dispersion of platingsolution and homogeneous co-deposition of second phase. The goal was to examine the effect of the agitation type in bath,on the attributes of the deposited composite coatings. The incorporation of Al2O3 particles was enhanced when themechanical agitation of the solution was applied. However, in case that this agitation method was used, the agglomeration ofthe alumina particles occurred. In contrast, when an ultrasonic agitation of the plating solution was applied, the uniformdistribution of the alumina particles could be achieved. The presence of particles in the matrix, along with appliedultrasound, resulted in grain refinement and homogeneous microstructure. The Al2O3 nanoparticles incorporated in Zn-Mnalloy matrix, resulted in a significant increment in the indentation hardness and a modest increase in the coating corrosionresistance. However, the coating hardness increased with alumina addition, only in case when an ultrasonic agitation of theelectrodeposition solution was used.

Interfacial Investigation of St13/Molten Zn–5% Al and Corrosion Behavior of Formed Layer via Hot-Dip Process

In the present study, the effect of temperature and duration of hot-dipping on structural properties, hardness, and corrosion resistance of Zn–5% Al coatings on ST13 low-carbon steel has been investigated. The samples were dipped in a molten metal bath at temperatures of 440, 480 and 520°C, during 20, 50 and 70 seconds. To investigate the microstructure and properties of samples, scanning electron microscopy, energy dispersive X-ray spectrometry, microhardness measurements, and potentiodynamic polarization corrosion tests were used. The results showed that the coating structure is an eutectic layer at 440°C, and at the interface of the substrate and the coating a thin inhibitory layer is formed that prevents the diffusion of the substrate atoms into the coating and from the molten bath into the substrate. With an increase of temperature to 480 and 520°C, with the diffusion of iron atoms of the substrate and of the molten bath, a triple metallic layer of Al–Fe–Zn forms, and the thickness of the coating increases. As the dipping time increases, the number of intermetallic particles in the coating also increases. At higher temperatures, the hardness went up from 86 to 121.73 Hv and the corrosion rate—from 7.381 to 37.53 Mpy. hot dip, Zn–5% Al coating, microstructure, intermetallic, corrosion

Effect of a Zn Interlayer on the Adhesion Strength and Corrosion Resistance of Zn–Mg Coated TRIP Steel

Effect of a Zn Interlayer on the Adhesion Strength and Corrosion Resistance of Zn–Mg Coated TRIP Steel

The corrosion resistance of zinc coatings in the presence of boron-doped detonation nanodiamonds (DND)

The effect of detonation nanodiamonds, doped with boron (boron-DND) in detonation synthesis on the process of zinc electrochemical deposition from zincate electrolyte is investigated. It is shown that the scattering power (coating uniformity) increases 2-4 times (depending on the concentration of DND-boron electrolyte conductivity does not change, the corrosion resistance of Zn- DND -boron coating increases 2.6 times in 3% NaCl solution (corrosion currents) and 3 times in the climatic chamber.

Effect of WO3 nanoparticle loading on the microstructural, mechanical and corrosion resistance of Zn matrix/TiO2-WO3 nanocomposite coatings for marine application

In this study, for marine application purposes, we evaluated the effect of process parameter and particle loading on the microstructure, mechanical reinforcement and corrosion resistance properties of a Zn-TiO2-WO3 nanocomposite produced via electrodeposition. We characterized the morphological properties of the composite coatings with a Scanning Electron Microscope (SEM) equipped with an Energy Dispersive Spectrometer (EDS). We carried out mechanical examination using a Dura Scan hardness tester and a CERT UMT-2 multi-functional tribological tester. We evaluated the corrosion properties by linear polarization in 3.5% NaCl. The results show that the coatings exhibited good stability and the quantitative particle loading greatly enhanced the structural and morphological properties, hardness behavior and corrosion resistance of the coatings. We observed the precipitation of this alloy on steel is greatly influenced by the composite characteristics.

An Influence of the Self-Ageing on the Hardness and Corrosion Resistance of the ZnAl22Cu3 and ZnAl40Cu3 Alloys

The purpose of the examination was to determination of influence of self - ageing on the hardness and corrosion resistance of Zn - Al - Cu alloys. Subject of test were ZnAl22Cu3 and ZnAl40Cu3 alloys. The scope of examinations included: Brinell hardness tests and corrosion resistance tests. Tests were carried out just after heat treatment and after duration of 1, 2, 3, 4 and 5 months after heat treatment. The scope of corrosion test included galvanostatic and potentiodynamic tests. It was found, that natural ageing causes significant decrease of the hardness of ZnAl22Cu3 and ZnAl40Cu3 alloys after solution heat treatment. Carried out tests pointed out, that natural ageing significantly influences on corrosion resistance of ZnAl22Cu3 and ZnAl40Cu3 alloys. During ageing process, corrosion resistance is significantly changed. The high aluminum ZnAl 40Cu3 alloy as a higher hardness and higher corrosion resistance than ZnAl22Cu3 alloy

Deformation mechanism during nanoindentation creep and corrosion resistance of Zn

Purpose – The study of nanoindentation as a reliable method to extract creep properties as well as for fundamental understanding of deformation mechanisms at small length scales is an open interesting field. The observed creep behavior is attributed to time-dependent plastic deformation based on loading rates. There is a lot of work in the field of nanoindentation in order to understand the dynamic effects on nanomechanical properties. The paper aims to discuss these issues. Design/methodology/approach – The deformation mechanism is investigated under two experimental approaches (high and low loading rates, respectively) during nanoindentation. The effect of loading rate in the nanomechanical properties, during nanoindentation creep of zinc layer on hot dip galvanized (HDG) steel, is discussed through nanoindentation. Findings – Analysis of this research effort is emphasized on nanoindentation stress exponent, a critical parameter for the life time and reliability of nano/micro-materials and systems. The corrosion resistance was studied by electrochemical impedance spectroscopy (EIS) and localized EIS. Originality/value – The study of nanoindentation as a reliable method to extract creep properties as well as for fundamental understanding of deformation mechanisms at small length scales is an open interesting field. The observed creep behavior is attributed to time-dependent plastic deformation based on loading rates. The deformation mechanism is investigated under two experimental approaches (high and low loading rates, respectively) during nanoindentation. The effect of loading rate in the nanomechanical properties, during nanoindentation creep of zinc layer on HDGsteel, is discussed through nanoindentation. Analysis of this research effort is emphasized on nanoindentation stress exponent, a critical parameter for the life time and reliability of nano/micro- materials and systems. The corrosion resistance was studied by EIS and localized EIS.

Effect of pH on nucleation mechanism of Zn–Mn coatings electrodeposited at different deposition potential

Zn–Mn alloy coatings were galvanostatically deposited from an acidic chloride bath at pH 2·0 and 4·9. Effects of pH on nucleation mode, surface morphology and corrosion resistance of Zn–Mn coatings were studied. Analysis of current-time transients indicated that the nucleation mode of Zn–Mn coatings at pH 2·0 is instantaneous. With increasing the pH to 4·9 at potentials of −1·08 and −1·59 V, the experimental data were observed to be near the theoretical instantaneous nucleation, but at higher potentials of −1·12 and −1·2 V, the progressive mode of nucleation was dominant. From AFM images, the average nuclei density N values for Zn–Mn deposition at pH 2·0 and 4·9 were 9·2×109 and 10×109 cm−2 respectively. At pH 2·0, this value was near that obtained by the model, but it was found to be far away at pH 4·9. Potentiodynamic polarisation indicated that the corrosion resistance of Zn–Mn coatings at pH 4·9 is slightly improved.

Enhanced corrosion performance of Zn coating by incorporating graphene oxide electrodeposited from deep eutectic solvent

The corrosion resistance of Zn–GO is much better than that of pure Zn.

Influence of the alloying component on the corrosion behaviour of zinc in neutral aerated sodium chloride solution

The effect of Zr alloying addition on the corrosion resistance of Zn has been investigated. In this work, the corrosion behaviour of Zn–1Zr (mass%) alloys has been assessed by open circuit potential and electrochemical impedance spectroscopy (EIS) measurements carried out in a 0.1M NaCl solution, at approximately neutral pH, without stirring and in contact with the air. For comparison, the electrochemical tests have also been performed on unalloyed Zn as well as on Zn–1Ti commercial alloy employed as a protective coating for steel. Both open circuit potential and EIS results indicate that Zn–1Zr alloy exhibits superior corrosion resistance as compared to unalloyed Zn and Zn–1Ti alloy. This improvement may be ascribed to the formation of a corrosion products layer, mainly composed of Zn5(OH)8Cl2⋅H2O and ZrO2, which shows higher protective effectiveness than the ones formed on Zn–1Ti alloy or on unalloyed Zn.

Influence of thermal treatment on the corrosion resistance of electrolytic Zn–Ni+Ni composite coatings

This study was undertaken in order to obtain and characterize the corrosion resistance of Zn–Ni+Ni composite coatings. The influence of thermal treatment on surface morphology, phase composition, and corrosion resistance of Zn–Ni+Ni coating was investigated. The Zn–Ni+Ni coating was deposited under galvanostatic conditions (j = 40 mA cm−2). Thermal treatment was carried out in argon atmosphere. The surface morphology of Zn–Ni+Ni coatings was carried using a scanning electron microscope (JEOL JSM-6480) and the surface chemical composition was determined by the EDS method. Structural investigations were conducted by X-ray diffraction method. The studies of electrochemical corrosion resistance were carried out in a 5% NaCl solution, using potentiodynamic and scanning vibrating electrode (SVET) methods. On the grounds of corrosion investigations, it was stated that thermal treatment improves both total and localized corrosion resistance of Zn–Ni+Ni coating in a 5% NaCl water solution. The higher corrosion resistance of the thermally treated Zn–Ni+Ni coating could be attributed to the increase in the amount of zinc bonded to nickel in the form of Ni2Zn11 and Ni5Zn21 intermetallic phases. The SVET analysis indicated that thermal treatment of Zn–Ni+Ni coating causes a decrease in the number of corrosion centers on their surface area.

Characterisation and corrosion resistance of Zn–Mn coatings electrodeposited from acidic chloride bath

Zn–Mn alloy coatings were galvanostatically electrodeposited from an acidic chloride bath. Effects of deposition current density, pH and temperature on surface morphology, microstructure and corrosion resistance of Zn–Mn coatings were studied. The coatings deposited at 10, 50 and 100 mA cm−2 had a single η-Zn phase structure. However, a dual phase structure of η-Zn and ϵ-Zn–Mn with higher Mn content was found for the coatings deposited at 200 mA cm−2. The dual structure degraded the corrosion resistance of the coatings. The highest corrosion resistance was achieved for the Zn–Mn coating deposited at 100 mA cm−2, pH 4·9 and 25°C. This coating contained 4·1 wt-%Mn and showed a unique surface morphology consisting of randomly arranged packs of very thin platelets, laid perpendicular to the surface and provided a high compactness deficient free structure.

Effect of phase transformation on corrosion behaviour of Zn–22Al alloys

The effect of phase transformation on the corrosion behaviour of Zn–22Al (wt-%) alloys immersed in NaCl solution (3·5 wt-%) at room temperature was investigated. As cast Zn–22Al alloys were isothermally heated at 300 and 250°C (the eutectoid point is 277°C) respectively and then cooled by various rates. Isothermally heated below the eutectoid point, the corrosion resistance of the alloys increased with the decreasing cooling rate. However, when the isothermal heating temperature was above the eutectoid point, the corrosion resistance of Zn–22Al alloys increased with the increasing cooling rate. It can be attributed to the existence of α2 phase, which may lead to smaller potential difference between the microgalvanic cells.

Study on long term atmospheric corrosion of electrodeposited zinc and zinc alloys

Investigations of atmospheric corrosion of non-chromated Zn and Zn alloys, namely Zn–0·8%Fe, Zn–0·8%Co, Zn–0·8%Ni electrodeposited from acid electrolytes have been performed for the first time in urban, rural and marine sites in Lithuania. Corrosion rates of Zn alloys were studied by long term exposure in urban, rural and marine environments as well as via the accelerated test of normal salt spray. The results indicated that the corrosion rates of Zn–0·8%Co and Zn–0·8%Ni electrodeposited alloys are low in three different environments: urban, rural and marine. The corrosion resistance of Zn–0·8%Co alloy was higher in urban and rural atmospheres, while that of the Zn–0·8%Ni alloy was higher in rural and marine atmospheres. In all cases the corrosion resistance of the Zn–0·8%Fe alloy was lower than that of the Zn–0·8%Co and Zn–0·8%Ni.

Electrochemical evaluation of zinc and magnesium alloy coatings deposited on electrogalvanized steel by PVD

Zinc alloy coating attracted much attention due to its high anti-corrosive properties. Particularly, zinc alloy coatings containing magnesium was considered a promising metallic alloy due to a remarkable improvement of corrosion resistance. The proper magnesium content for Zn–Mg alloy coatings was studied. The samples were prepared using thermal evaporation method. The influence of Zn–Mg alloy coating on corrosion resistance was evaluated using immersion test, potentiodynamic test, and galvanic test in 3% NaCl solution at room temperature. The results show that the corrosion resistance of Zn–Mg alloy coatings is strongly dependent on magnesium content. Corrosion potential decreases with increasing magnesium content, whereas current density increases up to 15% magnesium content, and passivity region was found only in Zn–Mg coatings.

Corrosion Resistance of Zn and Zn-Ni Electrodeposits: Morphological Characterization and Phases Identification

Zinc alloys coatings formed with elements of group VIIIB are promising because they display similar properties and protect steel by galvanic action. The Zn-Ni alloy is remarkable by showing improved mechanical properties and better corrosion resistance when compared to zinc coatings of similar thickness, also can be applied at higher temperatures. In this work, electrodeposits of Zn, Zn-12%Ni, obtained upon SAE 1010 steel from commercial alkali baths, were treated by blue chromatization and characterized according to mechanical properties and morphology. Studies were carried out by using measures of hardness, roughness, SEM, EDS and XRD. Among the studied electrodeposits, alloys treated by chromatization showed higher corrosion resistance and Zn-Ni electrodeposits showed higher value of roughness and hardness, while zinc coating had results similar to the steel substrate By means of XRD, it was found that electrodeposits are crystalline, being identified in Zn-Ni alloy the presence of the phases g(Ni5Zn21) and d(Ni3Zn22), which are responsible for its higher corrosion resistance.

Corrosion resistance of Zn–Ni/Ni and Ni/Zn–Ni compositionally modulated multilayer coating

AbstractZn–Ni/Ni and Ni/Zn–Ni compositionally modulated multilayer (CMM) coatings were prepared by dual‐bath technique. The effects of layers number and sublayers order were studied. Specially, the effect of different sublayers thickness ratios with the same multilayer period (λ) on the corrosion resistance of the CMM coatings was investigated in detail. Results showed that the corrosion resistance of Ni/Zn–Ni (Zn–Ni alloy sublayer as the top layer) CMM coating was better than that of Zn–Ni/Ni (Ni sublayer as the top layer) CMM coating. The 6‐layer CMM coating with the layer thickness ratio of Ni/Zn–Ni = 0.8:1.2 (λ = 2 µm) has the best corrosion resistance.