Zinc Surface Research Articles

Study of the inhibition of the corrosion of copper and zinc in HNO3 solution by electrochemical technique and quantum chemical calculations

The corrosion inhibition of copper and zinc in 0.1M HNO3 by 1,2,3,4-tetrazole (TTZ) and some of its derivatives has been analysed in a comparative study. Two experimental techniques have been used such as weight-loss and electrochemical polarization measurements. The results obtained reveal that the addition of these compounds reduces preferentially the corrosion of Cu rather than that of Zn. The adsorption of tetrazolic compounds on a copper surface was more favourable than their adsorption on a zinc surface. Moreover the inhibition efficiency calculated for copper was found to attain 95% in the presence of 1-phenyl-5-mercapto-1,2,3,4-tetrazole (PMT) while it remains constant at 1% for all compounds tested using zinc as electrode. Relationship between molecular structure and their inhibition efficiency was elucidated by quantum chemical calculations using the density functional theory (DFT).

Influence of grain orientation on zinc enrichment and surface morphology of an AlZn alloy

AbstractZinc is an important alloying element in the 7000 series aluminium alloys. It is also an element that may enrich near the alloy surface during treatments of aluminium alloys by processes such as electropolishing, alkaline anodic etching and alkaline etching. The enrichment may occur since the change in Gibbs free energy per equivalent for formation of ZnO is less negative than that for formation of Al2O3. The enriched alloying element is present in an alloy layer up to ∼5 nm thick located immediately beneath the alloy/film interface. In the present study, the dependence of the enrichment of zinc on the grain orientation of the alloy is investigated for a solid solution Al‐1.1at.%Zn alloy. The enrichment of the zinc is developed by alkaline etching of the alloy. The grain orientation is determined by electron backscattering diffraction, with enrichments quantified on selected grains by Rutherford backscattering spectroscopy and medium energy ion scattering. The morphologies of the surfaces of the etched grains are characterised by scanning electron microscopy and atomic force microscopy. The findings reveal that the zinc enrichment ranges from 1.7 × 1015 atoms/cm2 to 3.9 × 1015 atoms/cm2, with the greatest enrichment occurring on a grain of (100) orientation, while differing surface topographical textures are developed on the various grains. Copyright © 2009 John Wiley & Sons, Ltd.

Influence of interface chemistry and network density on interfacial ion transport kinetics for styrene/acrylate copolymer coated zinc and iron substrates

n-Butyl acrylate/styrene copolymer films were applied on iron and zinc surfaces. The kinetics of interfacial ion transport and cathodic delamination were tracked by in situ Scanning Kelvin Probe (SKP) measurements. A destabilisation of the interface was detected for latex network structures with an increased degree of cross-linking. In contrast, a reduction of the average macromolecular chain length resulted in films with higher resistance to interfacial ion transport. No comparable effect of the polymer structure was detectable when latex films were applied on zinc. Calculated coefficients for water diffusion through the bulk polymer partially supported the SKP results obtained on iron.

Inhibition of corrosion-driven organic coating disbondment on galvanised steel by smart release group II and Zn(II)-exchanged bentonite pigments

Bentonite pigments exchanged with either zinc or group II cations are characterised as inhibitors of corrosion-driven cathodic disbondment of model polyvinylbutyral (PVB) coatings adherent to the intact zinc surface of hot dip galvanised steel. An in situ scanning Kelvin probe (SKP) technique is used to quantify rates of coating delamination as a function of pigment volume fraction ( ϕ pt) and draw up a ranking order of inhibitor efficiency. Group II cation-exchanged bentonites show a moderate degree of inhibition, where rates of coating disbondment are reduced by up to 60–70% compared to the unpigmented case. In contrast, bentonite pigments containing exchangeable Zn 2+ ions are markedly more effective, and no delamination is observed over periods of up to 24 h when ϕ pt ≥ 0.1. The efficiency of in-coating Zn 2+ is attributed to the ability to block underfilm cathodic oxygen reduction by reinforcing a pre-existing zinc (hydr)oxide layer.

The effects of Aloe vera extract on corrosion and kinetics of corrosion process of zinc in HCl solution

The effect of the extract of Aloe vera leaves on the corrosion of zinc in 2 M HCl solution was studied using weight loss technique. A. vera extract inhibited the corrosion of zinc in 2 M HCl solution and the inhibition efficiency increased with increasing concentration of the extract but decreased with increasing temperature. The adsorption of the inhibitor molecules on zinc surface was in accordance with Langmuir adsorption isotherm. A first-order kinetics relationship with respect to zinc was obtained with and without the extract from the kinetics treatment of the data.

Preparation of Superhydrophobic Coatings on Zinc, Silicon, and Steel by a Solution-Immersion Technique

Zinc, silicon, and steel superhydrophobic surfaces were prepared by a simple solution-immersion technique. In the case of zinc, the method consists of dipping of the substrate in a prehydrolyzed methanol solution of 1H,1H,2H,2H-(perfluorooctyl)trichlorosilane [CF(3)(CF(2))(5)(CH(2))(2)SiCl(3), PFTS] for 24 h at 50 degrees C. Micron-sized spheres (1.7-2 microm in diameter) were formed on the zinc substrate at 50 degrees C, while a featureless coating was obtained when the solution-immersion process was conducted at room temperature. When the reaction was performed at room temperature, the formation of superhydrophobic coatings took several days (up to 5 days). In contrast, immersion of silicon or steel substrates in the PFTS/methanol solution led to the formation of hydrophobic interfaces even for a prolonged immersion period at 50 degrees C. The formation of superhydrophobic surfaces on silicon and steel surfaces was only possible if a zinc foil was added in the PFTS/methanol solution containing the silicon or steel substrate. X-ray photoelectron spectroscopy analysis was used to characterize the resulting surfaces and to underline a plausible reaction mechanism.

Chelating the Surface of Zinc in Zinc Oxide Nanocrystals: Spectroscopic Characterization of ZnO Surface-Bound Eriochrome Black T and 8-Hydroxyquinoline

The surface binding of eriochrome black T (ErT) and 8-hydroxyquinoline (HQ) with zinc oxide nanocrystals is studied with UV−vis absorption and fluorescence spectroscopy. Stern−Volmer analysis of the quenching dynamics in neutral water leads to binding constants of 2.52(1) × 10−6 and 7.14(1) × 10−6 M−1 for the binding of HQ and ErT, respectively. ErT coordinates in a 1:1 tetrahedral geometry for about 10% of the surface zinc sites, while HQ occupies a similar coordination geometry for half of the available sites. A new transient species forms during the interaction of ErT with the zinc oxide nanocrystals which is characterized by an absorption at 680 nm.

Preparation of non‐chromium polymer films on zinc for corrosion protection due to a compound effect between silane and cerium salt

PurposeThe purpose of this paper is to study the compound effect between silane and cerium salts in the passivation process of chemical conversion treatment of zinc.Design/methodology/approachChemical conversion treatment using 3‐Glycidoxypropyltrimethoxysilane on zinc is investigated as an alternative treatment to chromate conversion. The surface chemistry of the silane‐treated samples is investigated with mass change measurements, polarization curves, electrochemical impedance spectroscopy (EIS) and the salt spray tests (SST). The surface morphology of samples was studied using a scanning electron microscope.FindingsThe polarization curves, EIS and SST data are in agreement. On the surface of zinc, the silane formed a compound with the cerium, thus enhancing the adhesion and corrosion resistance of the polymer film.Originality/valueThere have been few reports on the compound effects of silanes and cerium salts in the passivation process. The mechanism of this compound effect may be due to the ability of Ce3 + ions to gain access to the interface through tiny cracks or micropores in the cross‐linking structure of GPS polymer films on zinc, and the subsequent oxidation of Ce3 + to Ce4 + by H2O2 may result in a barrier effect between the electrolyte and the metallic substrate.

Undec-10-ene-1-thiol multifunctional molecular layer as a junction between metallic zinc and polymer coatings on steel

The present work provides the formation of a new duplex system by combination of different layers on steel. Electrodeposition of zinc coating is performed as a first step and serves as a platform for molecular self-assembly and polymer coatings. Undec-10-ene-1-thiol molecule is used as layer junction between zinc surface and the polydimethylsiloxane (PDMS) film. Thiol function interacts by chemisorption with Zn surface while the terminal double bond takes place in the hydrosylilation reaction and thus increases the adhesion of PDMS to the zinc coating. Improvement of corrosion inhibition is evaluated by electrochemical methods at each stage of modification and particularly for the multilayer coating.

Atmospheric corrosion of zinc induced by runoff

Atmospheric corrosion and runoff of zinc were investigated during two years in humid tropical climate on hot dip galvanized steel and zinc samples. The high zinc mass loss (14.70 g m −2) is induced by the intensive zinc release (12.40 g m −2). No corrosion phase containing chloride was detected on the zinc surface, while a variety of sulfates not dissolved by rains reveals the sensitivity of zinc to SO 2 pollutant. However, two chloride-containing corrosion products were detected on the galvanized steel. Exponential equation is proposed that fits well the experimental data for zinc mass loss induced by runoff process as a function of the time of wetness. The formula gives possibility to predict the mass loss even before a steady state in the corrosion process has been reached. This equation can converge to a Benarie lineal function ( C = At w), when the coefficient b = 1 for the corrosion which is accelerated with the partial removal of the corrosion layer during the runoff phenomena.

What really controls the atmospheric corrosion of zinc? Effect of marine aerosols on atmospheric corrosion of zinc

<title/>This paper reviews the processes that control the production, transportation and deposition of aerosols and examines how these parameters affect the atmospheric corrosion of zinc on which the aerosols have deposited. The factors that influence the size and chemistry of aerosols are summarised. It is shown that marine aerosols may be acidified through the absorption of gases and strong acids, and that they may attain very low pH values. Aerosol transportation and deposition are size dependent, with aerosol deposition increasing with aerosol size and decreasing with transportation distance. Acidified marine aerosols may be transported to considerable distances from the sources of the acid precursor gases. The review examines the differences in the electrochemical phenomena on zinc surfaces under fine acidified marine or industrial aerosols and under large near neutral aqueous droplets, and shows that the low pH, fine size and high dissolved ionic salt content of the acidified marine aerosols leads to significant oxide dissolution and higher corrosion rates. Acidified marine aerosols disrupt protective oxide films and establish electrochemical cells in which anodic corrosion separation and resistance through the solution are small and oxygen depletion is unlikely. The authors’ analysis shows that the susceptibility of zinc to chloride containing environments may in part be associated with the effect of acidified marine aerosols.

Effects of Preparation Conditions on Surface and Catalytic Properties of Copper and Zinc Mixed Oxides System

Copper-zinc mixed oxides treated with small amounts of alumina and having the formula 0.5 CuO: 0.5ZnO: 0.05 Al2O3 were prepared by coprecipitation of their mixed hydroxides from their mixed nitrates solutions using 1 M NaOH solution. The precipitation was carried out at different pH values varying between 7 to 9.5 and at 50 and 70 o C. The results revealed that the bulk of various solids consisted of CuO and ZnO having ratios varying between 0.91 and 1.20. While the surface Cu/Zn ratio was bigger than those present in the bulk and varied between 1.16 to 1.64 depending on the pH value and calcination temperature. The mixed oxide solids existed as nanocrystalline CuO and ZnO phases. The surface characteristics are strongly dependent on both the pH value and calcination temperature. The computed SBET val- ues varied between 21and 108 m 2 /g and all adsorbents are mesoporous solids. The prepared solids showed a good cata- lytic activity in CO oxidation by O2 which proceeds via first order kinetics in all cases. The activation energy of the cata- lyzed reaction was determined for various solids and the computed values were very small indicating the big catalytic ac- tivity of the investigated solids.

Deposition of RuO 4 on various surfaces in a nuclear reactor containment

During a severe nuclear reactor accident with air ingress, ruthenium can be released from the nuclear fuel in the form of ruthenium tetroxide. Hence, it is important to investigate how the reactor containment is able to reduce the source term of ruthenium. The aim of this work was to investigate the deposition of gaseous ruthenium tetroxide on aluminium, copper and zinc, which all appear in relatively large amounts in reactor containment. The experiments show that ruthenium tetroxide is deposited on all the metal surfaces, especially on the copper and zinc surfaces. A large deposition of ruthenium tetroxide also appeared on the relatively inert glass surfaces in the experimental set-ups. The analyses of the different surfaces, with several analytical methods, showed that the form of deposited ruthenium was mainly ruthenium dioxide.

Paramagnetic complexes of 9, 10-anthraquinone and 9-fluorenone on the metal oxide surface

Paramagnetic complexes of 9, 10-anthraquinone and 9-fluorenone adsorbed on the surface of calcium, magnesium, zinc, zirconium, and aluminum oxides and modified Al2O3 as well as on mixed oxides were studied by ESR and electron-nuclear double resonance. Radical anions that do not interact with Lewis acid sites are generated on the surfaces of oxides with electrondonating properties (CaO, MgO). Paramagnetic complexes of the anthraquinone or fluorenone radical anion with Lewis acid sites (coordinatively unsaturated metal cations) are formed in other cases. Several types of similar complexes can be formed. Mechanisms of interaction of the probe molecules with the metal oxide surface were proposed.

DFT periodic study of adsorption of glycine on the (0 0 0 1) surface of zinc terminated ZnO

Bio-inorganic interfaces attract attention due to numerous possible applications in industry. Following this interest, we performed a molecular modelling of glycine adsorption on Zincite (ZnO). Adsorption of neutral, zwitterionic and anionic glycine on zinc-terminated polar (0 0 0 1)-ZnO surface, was studied using a periodic Density Functional Theory based method. Several coverages were considered, from the limit of the isolated molecule to the monolayer and bilayer coverage. The interaction of each glycine function (carboxylate and amine) with the Zn–ZnO surface is investigated separately, and then the adsorption through both functions is studied. We found that glycine adsorbs on Zn–ZnO surface at low coverage preferentially in the anionic form with dissociation, in a parallel orientation to the surface. The carboxylate moiety forms a Zn–OCO–ZnO ring two surface Zn atoms, and an additional Zn–N bond is formed between the amine function and a surface Zn atom; the proton, product of dissociation, forms a hydride like Zn–H at the surface. The formation of OH groups with oxygens of the underlying layer was also considered, but is less stable. At higher coverage, (2.6 G/nm 2) the dissociation of glycine into a glycinate ion is again the most stable configuration. An organized glycinate layer is formed, in which the glycine molecules adopt the ZnO honeycomb structure. Still increasing the coverage leads to the formation of a Zn–glycinate bilayer as shown by ab initio molecular dynamics simulations. In the first layer glycine molecules adopt the honeycomb ZnO lattice. The second layer consists in a Zn–glycinate complex, with a Zn atom extracted from the surface.

Inhibition of the Corrosion of Zinc in H2SO4 by 9-deoxy-9a-aza-9a-methyl-9a-homoerythromycin A (Azithromycin)

Inhibition of the corrosion of zinc in various concentrations (0.01 to 0.05 M) of H 2SO 4 was studied using weight loss and hydrogen evolution methods of monitoring corrosion. The results revealed that various concentrations of azithromycin (0.0001 to 0.0005 M) inhibited the corrosion of zinc in H 2SO 4 at different temperatures (303 to 333 K). The concentration of H 2SO 4 did not exert significant impact on the inhibition efficiency of azithromycin, but inhibition efficiencies were found to decrease with increase in the concentration of the inhibitor. Values of inhibition efficiency obtained from the weight loss measurements correlated strongly with those obtained from the hydrogen evolution measurements. The activation energies for the corrosion of zinc inhibited by azithromycin were higher than the values obtained for the blank. Thermodynamic data revealed that the adsorption of azithromycin on the surface of zinc was endothermic (values of enthalpies of adsorption were positive), spontaneous (values of free energies of adsorption were negative) and was consistent with the adsorption model of Langmuir.

Adsorption and Inhibitive Properties of Clarithromycin for the Corrosion of Zn in 0.01 to 0.05 M H2SO4

The corrosion of zinc in 0.01 to 0.04 M H 2SO 4 was studied using gravimetric and gasometric methods of monitoring corrosion. The results obtained indicate that clarithromycin is a good adsorption inhibitor for the corrosion of zinc in H 2SO 4. The inhibition efficiency of clarithromycin increases with increasing concentration but decreases with increasing temperature. There was no significant difference between the inhibition efficiencies of clarithromycin obtained at various concentrations of H 2SO 4 (P>0.5), but values of inhibition efficiency tend to decrease with increasing concentration of the acid. The adsorption of clarithromycin on zinc surface is endothermic, spontaneous and is best described by Langmuir adsorption isotherm. Calculated values of activation energies and free energies of adsorption indicate that the adsorption of clarithromycin on zinc surface supports the mechanism of physical adsorption.

亜鉛上の吸着亜鉛の自己表面拡散挙動のＤＦＴ計算

Ab initio molecular orbital (MO) and density functional theory (DFT) calculations were applied to surface diffusion analysis of a zinc adatom on a zinc (001) surface. An energetic contour map for surface diffusion of adatoms on surfaces of terrace, step, and kink sites were drawn to evaluate the activation energies for surface diffusion of each path. These sites' potential energies were higher in the order of terrace, step, and kink. The activation energy for surface diffusion on the terrace and through the step is considerably low. These results were consistent with the general terrace–step–kink model proposed for epitaxial growth during metal deposition. Validation of activation energy obtained by MO calculation is discussed along with remaining problems of MO calculation applied to electrochemical systems.

Zinc surface complexes on birnessite: A density functional theory study

Biogeochemical cycling of zinc is strongly influenced by sorption on birnessite minerals (layer-type MnO 2), which are found in diverse terrestrial and aquatic environments. Zinc has been observed to form both tetrahedral (Zn IV) and octahedral (Zn VI) triple-corner-sharing surface complexes (TCS) at Mn(IV) vacancy sites in hexagonal birnessite. The octahedral complex is expected to be similar to that of Zn in the Mn oxide mineral, chalcophanite (ZnMn 3O 7·3H 2O), but the reason for the occurrence of the four-coordinate Zn surface species remains unclear. We address this issue computationally using spin-polarized density functional theory (DFT) to examine the Zn IV–TCS and Zn VI–TCS species. Structural parameters obtained by DFT geometry optimization were in excellent agreement with available experimental data on Zn-birnessites. Total energy, magnetic moments, and electron overlap populations obtained by DFT for isolated Zn IV–TCS revealed that this species is stable in birnessite without a need for Mn(III) substitution in the octahedral sheet and that it is more effective in reducing undersaturation of surface O at a Mn vacancy than is Zn VI–TCS. Comparison between geometry-optimized ZnMn 3O 7·3H 2O (chalcophanite) and the hypothetical monohydrate mineral, ZnMn 3O 7·H 2O, which contains only tetrahedral Zn, showed that the hydration state of Zn significantly affects birnessite structural stability. Finally, our study also revealed that, relative to their positions in an ideal vacancy-free MnO 2, Mn nearest to Zn in a TCS surface complex move toward the vacancy by 0.08–0.11 Å, while surface O bordering the vacancy move away from it by 0.16–0.21 Å, in agreement with recent X-ray absorption spectroscopic analyses.

Manufacturing and mechanical properties of thermoplastic hybrid laminates based on DP500 steel

This paper investigates the manufacturing and mechanical properties of thermoplastic composite-metal hybrid laminates based on DP500 steel sheets bonded to a glass fiber-reinforced polypropylene (PP) or to a self-reinforced PP composite materials. Single cantilever beam (SCB) tests revealed that a good level of adhesion can be achieved by using a hot dip zinc surface treatment on the DP500 steel and incorporating an interlayer based on modified polypropylene at the interface between the composite and metal plies. In addition, SCB tests have shown that the interfacial fracture energy of the hybrid laminates increased with increasing crosshead displacement rate. Additional testing of a number of laminates has shown that the tensile properties of these composite-metal hybrid laminates are strongly dependant on the tensile properties of the constituent materials and that a modified rule of mixtures could be used to predict such properties.