Zinc-based Alloy Research Articles

Corrosion Behavior of Electrode Materials in the Production of Hydrogen

We study the corrosion behavior of electrode materials in the alkaline-water electrolysis within a broad range of electrolyte concentrations and for electrodes of different nature. It is discovered that the use of steel materials with low contents of chromium and vanadium impurities (0.1–0.3%) increases the corrosion resistance of the electrodes and weakens the dissolution of iron of steel anodes. The operation of anodes made of aluminum- and zinc-based alloys is accompanied by their dissolution. This fact makes it possible (due to the depolarization of the anodic process) to exclude the oxygen release by the mechanism of hydrogen depolarization, substantially simplify the technology of electrochemical synthesis of hydrogen, and to reduce the losses of materials and energy for the electrolysis.

The Prospects of Zinc as a Structural Material for Biodegradable Implants—A Review Paper

In the last decade, iron and magnesium, both pure and alloyed, have been extensively studied as potential biodegradable metals for medical applications. However, broad experience with these material systems has uncovered critical limitations in terms of their suitability for clinical applications. Recently, zinc and zinc-based alloys have been proposed as new additions to the list of degradable metals and as promising alternatives to magnesium and iron. The main byproduct of zinc metal corrosion, Zn2+, is highly regulated within physiological systems and plays a critical role in numerous fundamental cellular processes. Zn2+ released from an implant may suppress harmful smooth muscle cells and restenosis in arteries, while stimulating beneficial osteogenesis in bone. An important limitation of pure zinc as a potential biodegradable structural support, however, lies in its low strength (σUTS ~ 30 MPa) and plasticity (ε < 0.25%) that are insufficient for most medical device applications. Developing high strength and ductility zinc with sufficient hardness, while retaining its biocompatibility, is one of the main goals of metallurgical engineering. This paper will review and compare the biocompatibility, corrosion behavior and mechanical properties of pure zinc, as well as currently researched zinc alloys.

Morphological and Crystallographic Characterization of Primary Zinc-Rich Crystals in a Ternary Sn-Zn-Bi Alloy under a High Magnetic Field

Due to the unique capacity for structural control, high magnetic fields (HMFs) have been widely applied to the solidification process of alloys. In zinc-based alloys, the primary zinc-rich crystals can be dendritic or needle-like in two dimensions. For the dendritic crystals, their growth pattern and orientation behaviors under HMFs have been investigated. However, the three-dimensional crystallographic growth pattern and the orientation behaviors of the needle-like primary zinc-rich crystals under a high magnetic field have not been studied. In this work, a ternary Sn-Zn-Bi alloy was solidified under different HMFs. The above-mentioned two aspects of the needle-like primary zinc-rich crystals were characterized using the Electron Backscattered Diffraction (EBSD) technique. The results show that the primary zinc-rich crystals are characterized by the plate-shaped faceted growth in three dimensions. They grow in the following manner: spreading rapidly in the {0001} basal plane with a gradual decrease in thickness at the edges. The application of HMFs has no effect on the growth form of the primary zinc-rich crystals, but induces their vertical alignment. Crystallographic analysis indicates that the vertically aligned primary zinc-rich crystals orient preferentially with the c-axis perpendicular to the direction of the magnetic field.

Facile preparation of a zinc-based alloy composite as a novel anode material for rechargeable lithium-ion batteries

We report a new Zn-based nanocomposite anode material (Zn-Ti-C) for lithium-ion batteries synthesized by thermal treatment and a high energy mechanical milling process. X-ray diffraction and high-resolution transmission electron microscopy revealed the formation of active Zn nanoparticles finely dispersed in the hybrid titanium carbide (TiC) and carbon matrix. Electrochemical analyses show that the formation of the TiC and carbon buffer matrix significantly contributed to the improved performance of the Zn-based electrode by mitigating the volume changes of the Zn nanoparticles during the charge/discharge processes. Furthermore, we optimized the stoichiometric ratio of Zn and Ti in terms of specific capacity, cycling performance, and rate capability in the presence of carbon. The material with a 2:1 atomic ratio (ZnTi(2:1)-C) exhibited the best cycle life, with a gravimetric capacity of 363.6mAhg−1 and a volumetric capacity of 472.7mAhcm−3 after 300 charge/discharge cycles (78.1% retention). At this ratio, Zn-Ti-C consistently showed the best rate capability measurements up to 3000mAg−1 (85% of its capacity at 100mAg−1). Therefore, our Zn-Ti-C composite is a promising alternative negative electrode material for lithium-ion batteries.

Novel zinc-based alloys used to improve the corrosion protection of metallic substrates

Abstract The protection of metallic structural components against corrosion is fundamental to preserve their mechanical properties in aggressive environments. Zn-based coating represents one of the most used techniques to make protective coatings for metallic substrates. In the present paper, two types of novel zinc-based coating are proposed, by employing either a tin addition or an aluminium-tin-copper addition to the traditional zinc bath. The behaviour of steel-coated specimens under bending is experimentally and numerically investigated by considering different bath dipping times. A quite satisfactory agreement between experimental and numerical results is observed, especially under plastic behaviour regime.

Novel zinc-based alloys used to improve the corrosion protection of metallic substrates

Novel zinc-based alloys used to improve the corrosion protection of metallic substrates

A Critical Review on Corrosion and Runoff from Zinc and Zinc-Based Alloys in Atmospheric Environments

This critical review aims at addressing important issues concerning zinc corrosion and zinc runoff processes of zinc or zinc alloyed with aluminum or magnesium exposed to atmospheric environments. The evolution of the corrosion product (patina) layer is very important for both processes. While corrosion largely is controlled by electrochemical reactions at the metal/patina interface, runoff is predominantly governed by chemical reactions at the patina/atmosphere interface. The gradual evolution of compounds in zinc patina follows one of two main routes: one in more sulfur-dominated and one in more chloride-dominated environments. Because of climatic changes and reduction of sulfur-containing atmospheric species in many parts of the world, the chloride-route is expected to dominate over the sulfur-route. Alloying with aluminum and magnesium results in substantial improvement in corrosion protection, whereby several mechanisms have been proposed. The released amount of zinc is highly dependent on the amount of rainfall, also on sulfur dioxide concentration or deposition, and to only a low extent on chloride deposition. Based on all runoff data, a model is presented which predicts 70% of all observed zinc runoff rates within 40% from their measured value.

Wettability Behavior of Zinc-Based Alloys on Cast Iron

The wettability of two Zn–Al alloy coatings (called “McGill 2” and “McGill 3” with 27 and 10 wt% Al, respectively) on the compacted graphite cast iron substrate was studied using the static sessile drop method. The effects of wetting time and coating composition on the macrostructural and microstructural evolution of the system were investigated. It was found that although the contact angle was obtuse for both coating materials over the time, the interfacial reactions occurred between the drop and the substrate from the first stage of contact. The most significant result was the formation of a uniform and thick reaction layer (interlayer) with the diffusion-controlled property at the interface. The results showed that “McGill 2” coating is superior to “McGill 3” alloy as an intermediate material for the Al–Fe cast joining application. The “McGill 2” interlayer revealed a composite nature as it consisted of different layers of solid, in the form of stable AlxFeySiz intermetallic phases from the initial steps of the reactions.

Mechanical and Thermal Properties of Zn-xMg Solder Alloys

Zn based Lead-free solder is considered to be a promising alternatives of tin-lead solder because of its competitive price and mechanical properties. In this research zinc-based lead-free solder alloys were developed by addition of magnesium. Bulk mechanical and thermal properties of Zn-Mg alloys were investigated. The solder alloys were prepared by casting. Chemical composition of these prepared alloys were confirmed by XRF analysis. The microstructures of the solders changed significantly on increasing Mg content. FESEM images showed an increase in eutectic phase. These microstructural changes improved the mechanical properties like tensile strength and hardness of the newly developed alloy. The melting behavior of the solder alloys was studied by DTA analysis. TMA analysis revealed information on the co-efficient of thermal expansion (CTE) of these alloys at high temperature.

Residual stresses and corrosion performance of plasma sprayed zinc-based alloy coating on mild steel substrate

Plasma spraying technique stands out among the various processes for enhancing the surface characteristics of engineering materials. Many authors have conducted research on different types of deposition technologies in relation to the corrosion performance of different coatings. However, not all aspects of these processes are fully understood. This study focused on the residual stresses and corrosion behaviour of plasma sprayed zinc-based alloy coatings on mild steel substrate. Characterization of coated surfaces was done using optical microscopy, X-ray diffraction, and scanning electron microscopy to observe the morphology, phases, grain sizes and probable defects. The residual stresses were measured by X-ray diffraction sin2Ψ techniques using Cu-Kα radiation. The corrosion and micro hardness properties were investigated using Auto lab potentiostat (PGSTAT30) linear potentiodynamic polarization and Emco Dura Scan tester. The experimental results revealed an improvement in the corrosion and micro hardness properties of the coated samples as compared to the substrate. The residual stresses of the as-sprayed coatings show compressive stresses. The magnitudes of the stresses in the as-sprayed condition were low, with slight variation due to the effect of cooling and difference in powder compositions. Overall, zinc-base coatings have significant positive effects on the corrosion performance, mechanical properties and residual stresses of the substrate.

Abrasive Wear Response of SiC<sub>p</sub> Reinforced ZA-43 Alloy Metal Matrix Composite

Objectives: The objectives of the present study are to synthesize the high aluminium content zinc based alloy and their composites by incorporating 5 and 10 wt% of SiC particles and to assess their two body abrasive wear response. Methods/ Analysis: The matrix alloy and their composites have been synthesized by liquid metallurgy route. High stress abrasive wear examiantion have been conducted on using a pin-on-disc wear tester as per ASTM G132-96 standard. The influence of abrading distance and applied load on the wear behaviour of the test materials have been studied. For understanding the wear mechanism of composite wear rate, friction coefficient and frictional heating have been determined. Findings: The zinc based matrix alloy exhibits dendritic structure comprising of α dendrites surrounded by α + η eutectoid and metastable ∈ phase. in interdendritic regions. The α+η is solid solution of zinc and aluminium in aluminium and zinc respectively are soft and ductile while ∈ phase is quite harder and transmits wear resistance to a slight range. The dispersed SiC particles are considerable harder than the base alloy and enhance the abrasion resistance of the matrix alloy. Increasing abrasive wear rate with test duration could be attributed to greater extent of materiel loss because of the cutting tendency of the abrasive. Higher wear rate with larger load was owing to relatively less deterioration in the cutting efficiency of the abrasive particles spread over fixed track area. Highest frictional heating of the matrix alloy could be because of a greater extent of penetration of the abrasive particles on the samples while dispersion of hard SiC particles reduces the severity of penetration. Higher frictional heating with increasing load may be acribed to a greater extent of penetration by the abrasive particles on the sample surface. The presence of hard SiC particles in the composite reduced the depth of cut by the abrasive leading to increase coefficient of friction than the base alloy. Novelty/Improvements: The present study evaluate the abrasive wear behavior of a lighter zinc-based alloy and their composites in order to substitute as an efficient material system to conventionally used materials in tribiological applications.

A Predictive Model for Zinc Runoff Rates from Zinc Sheet and Galvanized Steel in Outdoor Constructions

A survey of the most important findings related to atmospheric corrosion of zinc and zinc-based alloys in atmospheric environments is currently undertaken by the authors. The survey also includes the concomitant zinc dispersion (also named runoff) from the same materials. This survey includes the corrosion product formation in different environments, influence of the most important parameters on the atmospheric corrosion process and also the influence of the most important parameters on the runoff process. The whole effort is motivated both because of recent progress made in the mechanistic understanding of the corrosion and runoff processes and also because of environmental concerns and initiatives, e.g., as formulated by the White Paper Strategy for a Future Chemicals Policy from the Commission of the European Communities in Brussels (2001) and in the Brundland report Our Common Future (1987). This presentation shows some highlights from the compilation of zinc runoff rates from zinc and zinc-containing materials exposed to different urban, rural, marine and tropic atmospheric exposure sites. Based on the extensive amount of generated data (see, e.g., 1-16) an effort has been made to formulate a general model which is able to predict the annual runoff rates of zinc from zinc-containing materials. The aim has been to formulate the model with help of parameters that all have a physical meaning. They include the annual rain amount, the annual average rain acidity, and surface inclination. To provide better experimental support for developing the runoff model, the field exposures have been complemented with laboratory exposures with artificial rain water allowing the individual parameters to be better controlled and varied one by one. The zinc runoff rates have been used, among others, for environmental risk assessments, legislation and restrictions (e.g. 17-18). In this case it was also necessary to include the chemical speciation and dilution effects upon entry of zinc into the environment.

Thermophysical structure-sensitive properties of Tin–Zinc alloys

Tin–zinc-based alloys are under intense consideration as alternative lead-free solders for consumer electronics and telecommunications. This is because of their excellent creep resistance and fatigue resistance as well as mechanical and tensile properties. In present work, the thermophysical structure-sensitive properties of the Sn–Zn alloys prepared in the traditional bulk form, and in the foil form (30 µm thick and 6 mm wide) by the rapid solidification technique were studied and compared. The electrical conductivity study of Sn–Zn alloys from the Sn-rich side was carried out in the solid and liquid states in a wide temperature range from the room temperature up to 900 K. Thermal conductivity and viscosity were measured in the liquid state. The thermal conductivity results are consistent with the values calculated from the electrical conductivity data according to the Wiedemann–Franz–Lorenz law. The concentration dependence of viscosity revealed a negative deviation from the additive values. The melting-solidification region was studied by XRD and DSC. The behavior of thermophysical properties of Sn–Zn melts in the concentration range close to the eutectic composition indicates the existence of the micro-regions of remaining Zn phase in the temperature range above the melting temperature. The micro-inhomogeneous structure with the short range order in the Sn–Zn alloys after melting was confirmed by the structure analysis.

Influence of surface pre-treatment on the cytocompatibility of a novel biodegradable ZnMg alloy

Degradable zinc-based alloys with an appropriate corrosion rate are promising materials for the preparation of temporary orthopaedic implants. Previously, we prepared and characterised a novel Zn1.5Mg alloy. This paper is focused on the characterisation of this alloy after a surface pre-treatment, which should mimic processes occurring in vivo.The samples of the Zn1.5Mg alloy were immersed in a simulated body fluid (SBF) at 37°C for 14days in order to form a protective layer of corrosion products. Thereafter, these samples were used for the corrosion rate determination, an indirect in vitro cytotoxicity test, as well as for a direct contact test and were compared with the non-treated samples. The protective layer was characterized by SEM and its chemical composition was determined by EDS and XPS analysis.The corrosion rate was significantly decreased after the pre-incubation. The protective layer of corrosion products was rich in Ca and P. The pre-incubated samples exhibited increased cytocompatibility in the indirect test (metabolic activity of L929 cells was above 70%) and we also observed osteoblast-like cell growth directly on the samples during the contact tests. Thus, the pre-incubation in SBF leading to improved cytocompatibility could represent more appropriate model to in vivo testing.

Novel method of fluxless soldering with self-abrasion for fabricating aluminum foam sandwich

The aluminum foam sandwich (AFS) with metallic bonding was fabricated by means of fluxless soldering with self-abrasion. The effects of abrasion forms on interfacial feature, the deformation and failure behavior of AFS are compared through microstructural observation and static three-point bending tests. The good wetting process was realized assisting with the abrasion. The self-abrasion of aluminum foam produced mechanical stirring to make the microstructure more uniform and reduce the defects of the soldering seam. The load–deflection curve of AFS with metallic bonding exhibited three distinct regions. Three failure modes with indentation, core shear and plastic hinge were identified during the bending tests. An excellent bonding has been informed between aluminum alloy face sheets and aluminum foam core due to the retained cohesion between them. Assisting with self-abrasion, fluxless soldering using a zinc-based alloy has been proven to be suitable for fabricating AFS.

Effect of Phase Composition on the Anodic Dissolution and Passivation of Zinc-based Alloys

The influence of phase composition on the anodic behavior of electrolytic zinc-based alloys in alkaline solutions was investigated. The following materials were studied: Zn-Sn alloys consisting solely of Zn and Sn crystallites in a mechanical mixture, Zn-Fe, Zn-Co, and Zn-Ni alloys consisting of both solid solutions and intermetallic compounds. The anodic behavior of low-alloy solid solutions is similar to that of pure Zn. Solid-solution alloys consisting of an-phase had a distinctive feature: the descent of the anode current prior to the complete passivation takes place at more positive potentials compared to pure zinc and its mechanical mixtures. The same sequence of anodic dissolution and passivation of zinc alloys as for the pure zinc anode polarization were observed during anodic polarization of both solid solutions and intermetallic phases of zinc alloys. Alloying led to a change in the thermodynamic and kinetic characteristics of anodic processes. Typical peaks of anodic behavior of Zn and Sn were observed on the voltammetry curves of a broad range of heterogeneous Zn-Sn alloys. Peak currents depended on the alloy composition. The dependence between the alloy phase composition and the corresponding electrochemical behavior can be used in determination of the phase composition.

Organization and Performance of the Novel High Aluminum Zinc-Based Alloy

The novel high aluminum zinc-based alloy is prepared by changing composition of the alloy and adding 0.05% mixed rare earth with lanthanum-rich. The microstructure, mechanical properties and thermal expansion coefficient are investigated under as casting condition. The results showed that the novel high aluminum zinc-based alloy had fine microstructure, higher mechanical properties and smaller thermal expansion coefficient compared to the ZA27 alloy.

Study on Mechanical Properties of High Aluminum Zinc-Based Alloys with Different Al Contents Ranging from 30 wt% to 50 wt%

The mechanical properties and microstructures of zinc-based alloys with different Al-contents ranging from 30 wt% to 50 wt% were studied by means of DSC, metallography and tensile testing under different temperatures in the present work. The experimental results show that the ZA40 is of the best comprehensive properties and ZA50 better high-temperature performance among the five alloys.

Structure Analysis of Zn-Al-Mg Coating on Steel Wire

Abstract The corrosion resistance of zinc coatings is determined primarily by the thickness of the coating but varies with the severity of environmental conditions. In case of zinc-based alloys for steel coating the phase type and its quantity developed upon solidification determines corrosion resistance as well. In this paper the phase quality and evolution along thickness of the Zn-Al-Mg coating layer was studied by x-ray diffraction analysis. During investigation the coating was removed in controlled manner in several steps. Each individual step of removal was followed with x-ray diffraction measurement and subsequent analysis of x-ray diffraction patterns.

Steel machining chips as reinforcements to improve sliding wear resistance of metal alloys: Study of a model Zn-based alloy system

Two new steel-reinforced, metal-matrix composites (MMCs), Kirksite+1080 and Kirksite+M2 are developed by adding 25wt% of AISI 1080/AISI M2 steel machining chips to a zinc-based alloy, Kirksite (4% Al and 3% Cu). The sliding wear resistance of the Zn alloy and the two MMCs, against AISI 52100 steel, is determined under increasing normal load (1–10N) and temperature (25–150°C), using a pin-on-disc configuration. The MMCs are found to exhibit superior wear performance under all test conditions. At room temperature, a maximum wear reduction in excess of 70% is obtained for the composites relative to the Zn-alloy at the highest load of 10N. This reduction is as much as 86% at 150°C and 1N for the Kirksite+M2. The wear-reducing ability of the steel reinforcements is generally greater at the more severe contact conditions. The stability of the MMC matrices and recommended limits to the MMC operating temperatures are established using deformation measurements made via dynamic mechanical analysis. The principal wear mechanisms are analysed based on the sliding wear measurements, complemented by optical microscopy and SEM observations, and EDX microanalysis. The results show that the steel chip reinforcements are effective in improving the wear resistance of Zn alloys under severe conditions. Implications for use of low-cost machining chips as reinforcements to create MMCs for improved wear performance, and for recycling/reuse of these chips in advanced structural material systems are discussed.