Zinc Solid Solution Research Articles

ВОССТАНОВЛЕНИЕ ИЗНОШЕННЫХ ПОВЕРХНОСТЕЙ ТРЕНИЯ СКОЛЬЖЕНИЯ ГАЗОДИНАМИЧЕСКИМ НАПЫЛЕНИЕМ МЕДНО-ЦИНКОВЫХ ПОКРЫТИЙ

Preliminary studies of copper and copper-zinc coatings obtained by gas-dynamic spraying have shown high mechanical and tribological properties of the formed functional surfaces. The influence of the modes of spraying and subsequent heat treatment on copper-zinc gas dynamic coatings has been little studied. (Research purpose) The research purpose is investigating the effect of technological modes of spraying, as well as subsequent heat treatment of the coating on its phase composition, structure and properties. (Materials and methods) The coating was applied using a Dimet gas dynamic installation with different overlap of the sprayed layers and subsequent heat treatment of the resulting coating at different temperatures and exposure times. The structure of the coating was studied using an X-ray diffractometer and a spectrometer. Cohesive properties were determined on a bursting testing machine by the "ring separation" method, tribological properties were determined on the MT-8 stand during reciprocating sliding of flat mating bodies. (Results and discussion) It was determined that the chemical and phase composition of the copper-zinc coating applied with a displacement of the nozzle by two millimeters and an air flow temperature of 450 degrees Celsius, after heat treatment in the temperature range of 420-430 degrees Celsius and a holding time of 180 minutes corresponds to two-phase brass type L65. The study of the parameters of the copper lattice shows that after exposure in the furnace for 60 minutes, a two-phase structure is formed based on solid solutions of zinc in copper with different copper content and an electronic-type solid solution based on CuZn. (Conclusions) Tribological tests of the copper-zinc coating in the I-20A industrial oil medium revealed the presence of mutual mass transfer of copper and zinc from the coating to the counterbody and vice versa, which is accompanied by a wear-free effect at a load of up to 10 megapascals. The cohesive strength of the copper-zinc coating depends on the time of heat treatment (phase composition) and after 60 minutes of exposure exceeds the initial values (approximately 78 megapascals) and reaches approximately 93 megapascals.

Effect of Proportions of Γ and Iron–Zinc Solid Solution Phases on the Corrosion Prevention Performance of Mixed Coating Layers on Heated Galvannealed Steel Sheets

Coating layers having different ratios of a Γ phase to an Fe–Zn solid solution phase were produced on galvannealed steel sheets by heat treatment. The corrosion prevention characteristics of these layers were then investigated using combined cyclic corrosion test, electrochemical measurements and analyses of corrosion products. A coating layer with a larger proportion of the Γ phase showed better corrosion prevention properties along with a smaller corrosion mass loss. The Γ phase exhibited a sacrificial corrosion protection effect with regard to both the Fe–Zn solid solution and the steel substrate while the Fe–Zn solid solution showed a sacrificial corrosion protection effect on the steel substrate. The corrosion products formed from the Γ phase comprised Zn5(OH)8Cl2·H2O, Zn5(CO3)2(OH)6, ZnO and various amorphous compounds, while the Fe–Zn solid solution generated Zn-containing ferrihydrite and amorphous compounds. The presence of Zn evidently stabilized the ferrihydrite and delayed the formation of crystalline iron oxyhydroxide based on comparisons with corrosion products formed on cold-rolled steel sheets. These effects improved the corrosion prevention performance of the Fe–Zn solid solution. The zinc-based corrosion products formed from the Γ phase provided even better corrosion prevention performance by delaying the formation of crystalline iron oxyhydroxide and were also themselves resistant to reduction.

Influence of Alloying Element and Ageing on Microstructure and Dry Sliding Wear Behaviour of Cu-Zn-xNi Alloy

In this paper, we look at how different nickel concentrations (4, 8, and 12 percent) affect the microstructure, microhardness, and dry sliding wear behaviour of a Cu-Zn-xNi alloy. The alloy was created using a casting technique at 1100°C and a heat treatment method that included solution treatment at 600°C and ageing at 450°C for four hours each. Microstructure studies were performed on the developed alloys using a scanning electron microscope (SEM). To investigate alloy indentation resistance, an ASTM E384 microhardness test was performed. Tribological properties such as friction and wear were investigated using a pin on disc tribometer and a dry sliding wear test according to the ASTM G99 standard. SEM studies revealed α-phase (copper) and solid solution of zinc in cast alloys, while aged alloys revealed a similar structure but with the addition of Cu2NiZn precipitates. The microhardness values improved as the Ni content and ageing increased. The decrease in secondary dendrite arm spacing with increasing Ni content and ageing was attributed to the improvement. The coefficient of friction decreased as the load increased, but increased as the sliding velocity increased. However, as loads and sliding velocities increased, so did the wear rate. For the majority of loads and sliding velocities, the worn surface demonstrated abrasion as the dominant wear mechanism.

Structure and properties of rapidly solidifing foils Sn – 14 at.% In – 6.5 at.% Zn

The results of studies of the effect of ultra-high cooling rates of the melt equal to 10 5 K/s on the phase composition, microstructure, grain structure and mechanical properties of the Sn – 14 at.% In – 6.5 at.% Zn alloy are presented. To prepare the samples, the rapid quenching from the melt technique was used. A drop of melt was injected onto the inner surface of a rapidly rotating copper cylinder and solidifing in the form of a foil with a thickness of 30–90 μm. Investigations of the phase composition, carried out by the method of Х-ray diffraction analysis, made it possible to establish that the foil consists of a solid solution of zinc in the γ -phase (Sn4In) and zinc. Observations of the microstructure of the foil using scanning electron microscopy showed that the decomposition of a supersaturated solid solution proceeds at room temperature with the release of dispersed zinc particles. The character of the grain structure and texture of the foil is studied by the electron backscatter diffraction technique. A mechanism of the formation of elongated grains is proposed, which consists in the fact that at a high solidification rate, comparable to the rate of movement of the melt over the surface of the mold, grain growth can occur not only in the direction opposite to the direction of heat removal, but also in the direction of movement of the spreading. The formation of the preferred growth of grains, in which the most closely-packed plane (0001) is parallel to the foil surface, provides the maximum rate of decrease in the enthalpy of the alloy during crystallization. The features of the influence of the microstructure and grain structure on the mechanical properties of the foil are revealed. The microhardness of the rapidly solidifing Sn – 14 at.% In – 6.5 at.% Zn alloy is 105 MPa. The stress–strain curve of the Sn – 14 at.% In – 6.5 at.% Zn foil, obtained at room temperature, has a shape specific for the stress–strain curve of metals at high temperatures, which is due to the low melting point of the γ-phase.

Structural and Phase Transformations in a Coating Based on Copper and Zinc Particles Deposited by Gas Dynamic Spraying

The structure of a coating based on a mixture of particles of Cu and Zn deposited by the method of gas dynamic spraying is studied. An x-ray diffraction analysis and a microscopic spectrum analysis are used to determine the structure and the elemental composition of the coating. Development of diffusion after the formation of the coating is shown to yield a solid solution of copper and zinc in it. The phase composition of the coating after the heat treatment (a hold at 405 – 415°C) is shown to change for intermetallic compounds and a solid solution of zinc in copper.

The structure of rapidly solidified foil of the eutectic Sn – 8.8 wt. % Zn alloy

Microstructure of rapidly solidified eutectic alloy foil Sn – 8.8 wt. % Zn was studied. The alloy foil consists of solid solutions of zinc and tin. Dark equiaxed dispersed precipitates of zinc solid solution are uniformly interspersed in the matrix of tin solid solution. The parameters of the microstructure were determined. The average chord of a random secant at the sections of precipitates of a solid solution of zinc is 0.33 mm, and the specific interface surface is 0.81 mm–1. The precipitations of the tin solid solution have a microcrystalline structure. Specific surface of high angle boundaries less than 1 mm–1. The texture of the precipitates of solid solutions of tin and zinc in the foil was studied, and the pole densities of the diffraction lines of these phases are presented. The tin solid solution has the texture (100), and the zinc solid solution has the (0001) texture, which is explained by the predominant growth of grains, in which the crystalline planes of (100) tin and (0001) zinc are most closely packed and perpendicular to the heat flux. Eutectic alloy Sn – 8.8 wt. % Zn is in an unstable state. Annealing the foil causes the dissolution of small and coarsening of large particles of zinc solid solution, as well as the decomposition of a supersaturated tin solid solution. These processes cause an enlargement of the microstructure: an increase in the average particle size (dZn) of a solid solution of zinc and its volume fraction (VZn), a decrease in the specific surface (S ) of interphase boundaries.

Development and tribological characterisation of nanostructured Zn-Ni and Zn-Co coatings: a comparative study

ABSTRACTZn-Ni and Zn-Co alloy coatings were electrodeposited on mild steel from sulphate-based baths. The morphology, microstructure, microhardness and tribological behaviours of the coatings have been studied and discussed. While the Zn-5wt-% Co layers presented a nanocrystalline simple nodular structure (45 ± 5 nm), the Zn-14wt-% Ni showed a particular structure called cauliflower morphology (30 ± 7 nm). The X-ray diffraction analysis showed that each of the electrodeposits was formed from zinc solid solution with a uniform zinc-cobalt intermetallic phase γ2 (CoZn13) for Zn-5wt-% Co alloy. However, a single γ-phase (intermetallic compound Ni5Zn21) was presented for the Zn-14wt-% Ni alloys. The Zn-14wt-% Ni films were found to be harder and rougher than the Zn-5wt-% Co layers. Plastic deformation and oxide layers production were the main wear mechanisms for the investigated coatings. The Zn-14wt-% Ni coatings were found to have the best wear resistance due to their microhardness and particular structure.

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.

Thermal Diffusion Galvanizing in Ferriferous Zinc Powder

The features of the growth and the structure of diffusion zinc coatings in the process of galvanizing in powders with nanocrystallized surface area, alloyed with iron, are studied. It is established that the increase in the iron content in the powder substantially increases the area of the zinc solid solution in iron at a constant speed rate of the layer of zinc-iron phases. This effect is accompanied by the change in the morphology of powder particles as a result of iron saturation.

Initial stages of localized corrosion at cut-edges of adhesively bonded Zn and Zn-Al-Mg galvanized steel

The mechanisms of the initial stages of localized corrosion at cut edges were investigated for adhesively bonded Zn (Z) and Zn-Al-Mg (ZM) galvanized steel. The results provided strong evidence for the localized nature of corrosion of galvanized coatings at the cut edges and at the adhesive/zinc interface. In both cases a defined localized corrosion attack on zinc in Z sample was observed. On the contrary, in the case of the ZM specimen both zinc solid solution and eutectics exhibited local corrosion. The local attack at the adhesive/Z(ZM) interface was correlated with an anodic undermining process. It develops near the cut-edge surface and at the buried deep adhesive-zinc interface and results in adhesive disbonding in the buried interface. The electrochemical studies revealed that the corrosion kinetics at the metal cut-edges decreases during immersion, which could be due to formation of corrosion products on both steel and zinc surfaces.

A Mechanistic Study on the Inhibition of Zinc Behavior During Laser Welding of Galvanized Steel

The characteristics of zinc behavior that the zinc layer is vaporized and ionized during laser welding of galvanized steel are closely related to the stability of the molten pool, and the weld keyhole formation, easily leading to weld defects such as pores, splashes, cave, and incomplete fusion. In this paper, an experimental platform was built based on a multichannel spectrum signal acquisition to study spectral characteristics of zinc, plasma temperature, electron density, and bremsstrahlung absorption in laser welding of galvanized steel with the copper addition. The results show that, due to the formation of a copper–zinc solid solution during the laser welding of galvanized steel, the zinc content in the welding joints increased significantly. Meanwhile, by adding an appropriate amount of copper powder, the temperature and oscillation amplitude of the plasma plume during the laser welding of galvanized steel decreased significantly. Further, the inverse bremsstrahlung radiation absorption coefficient decreased, and there was less attenuation of the laser energy when passed through the plasma plume outside the keyhole. Therefore, the method implemented here improved the utilization of laser energy during welding.

The use of trivalent chromium bath to obtain a solar selective black chromium coating

Abstract Black chromium coatings were electrodeposited from a trivalent chromium bath using a ZnO additive as a second main component. Black chromium was electrodeposited on steel and copper plates and substrates plated with bright nickel prior to black chromium electrodeposition. The black chromium coatings were characterized by XRD and SEM. The XRD data suggest that the phase structure of black chromium may be defined as a zinc solid solution in chromium or a chromium solid solution in zinc depending on the chromium/zinc ratio in the deposit. The role of substrate finish was evaluated through the corrosion resistance and reflectance of black chromium. According to corrosion tests the samples plated with bright nickel prior to black chromium deposition have shown the highest corrosion resistance. The electrodeposited black chromium possesses good optical properties for the absorption of solar energy. The absorption coefficient of black chromium was found to be over 0.99 for the samples obtained without the Ni undercoat and below 0.99 for those obtained with the use of Ni undercoat. However, the use of nickel undercoat before black chromium plating is recommended because it remarkably improves the corrosion resistance of samples.

AFM and SEM investigation of a Zn-doped silicon surface

Atomic force microscopy (AFM) and scanning electron microscopy (SEM) combined with X-ray energy-dispersive microanalysis were used to investigate a silicon surface upon the decomposition of a super-saturated zinc solid solution in it. It was established that the created material was inhomogeneous and contained microdefects in the form of zinc precipitates that settled on dislocations or grain boundaries.

High-frequency induction soldering of magnesium alloy AZ31B using a Zn−Al filler metal

Magnesium alloy AZ31B plates were soldered by means of high-frequency induction soldering using a Zn−Al filler metal in argon gas shield condition. The interfacial microstructure and phase constitution of the soldered joint were investigated. The experimental results show that α-Mg solid solution and α-Mg + MgZn eutectoid structure were formed in soldering region. Moreover, the zinc solid solution and the aluminum solid solution in the original filler metal disappeared completely after the soldering process. Test results indicate that the shear strength of the soldered joint is 19 MPa. The fracture morphology of the soldered joint exhibits intergranular fracture mode and the crack originates from α-Mg + MgZn eutectoid structure.

Study on corrosion resistance of electroplating zinc–nickel alloy coatings

AbstractElectrodeposited zinc–nickel alloy coatings have been widely adopted for surface treatment of automobile body steel sheet for high corrosion resistance. The corrosion behavior of the coatings has been related with the components of nickel, and the zinc–nickel alloy passive coatings have much higher corrosion resistance than that of zinc–nickel alloy coatings. In the present paper, the corrosion resistance behavior of the zinc–nickel alloy coatings obtained by new process and formulation has been studied by means of the electrochemistry test and neutral salt spray test. And it is discovered that the properties of corrosion resistance of zinc–nickel alloy passive coatings were better than that of zinc passive coatings, Cadmium passive coatings and alloys of electrodeposited cadmium–titanium. The components of corrosion productions, in terms of X‐ray diffraction (XRD), are mainly ZnO, ZnCl2 · 4Zn(OH)2 and small quantity of 2ZnCO3· 3Zn(OH)2. The component of zinc–nickel alloy coatings has been investigated with Glow Discharge Optical Emission Spectrometry (GDA‐750). And it is found that as the thickness of zinc–nickel alloy coatings increases, the component of zinc increases from beginning to end, but the peak value of nickel appears and an enrichment of nickel in the coatings comes into being. Because the electrodeposited zinc–nickel alloy coatings exhibit different alloy phases as a function of their alloy composition, in this paper, the crystal structure changing with the different component of nickel has been studied in terms of XRD. The result shows that electrodeposited zinc–nickel alloy has different phases: α‐phase, a solid solution of zinc in nickel with an equilibrium solubility of about more than 79% nickel; γ‐phase, an intermediate phase with a composition Ni5Zn21; η‐phase, a solid solution of nickel in zinc with less than 5% nickel; and δ‐phase (Ni3Zn22) appeared from η‐phase to α‐phase with increasing content of nickel. Copyright © 2009 John Wiley & Sons, Ltd.

Multimode nature and magnetophonon resonance of quaternary solid solutions of zinc, cadmium, and mercury tellurides

The magnetophonon resonance in a multimode crystal of the solid solution ZnxCdyHg1−x−yTe (x=0.08, y=0.11) was investigated in the temperature interval from 77 to 200 K. To interpret the obtained structure of the magnetophonon resonance spectrum, the phonon modes of three compositions of this solid solution were studied by the Raman scattering method. The results presented confirm the three-mode behavior (excluding cluster modes) of the phonon spectrum of the solid solutions of this class. The complicated structure of the magnetophonon resonance bands is interpreted on the basis of the values obtained for the phonon frequencies. The characteristic features of electron transport in such a lattice are shown.

Effect of zinc sulphide concentrate composition and roasting temperature on magnesium distribution in zinc calcine

Magnesium is present in zinc calcine in two major forms. The first is a solid solution of zinc and magnesium oxides Zn 1− z Mg z O and the second one is a solid solution of zinc, magnesium and ferrous ferrites Zn x Mg y Fe 1− x− y Fe 2O 4. A thermodynamic analysis of equilibrium Zn and Mg distribution among the above oxide and ferrite phases as a function of temperature and relative Zn, Mg and Fe contents in the ZnS concentrates has been carried out. The derived relations are presented in the form of nomograms for 950, 1000 and 1050°C. These data have been found to be fairly close to those observed in industrial zinc calcine. The nomograms make it possible to assess the Zn and Mg distributions in the oxide and ferrite phases already at the stage of establishing the composition of ZnS concentrates. Taking into account that Zn−Mg oxide is easily soluble in H 2SO 4 solutions, whereas Zn−Mg−Fe ferrite is sparingly soluble, the nomograms may be helpful in optimizing the leaching parameters and in the selection of a method of controlling magnesium concentration in zinc electrolyte. Some data illustrating the solutions of the latter problems applied in Polish zinc refineries are presented.

Influence of the Structure and Temperature on the Extrusion Pressure of an Zn-20Al-2Cu Alloy

Abstract The feasibility of developing a method to successfully extrude the eutectoid Zn-Al alloy modified with 2 mass% Cu was studied. The best conditions found for extrusion are determined by the dendrite size of the extrusion ingot, the extrusion rate, and the extrusion temperature. Alloys extruded below the eutectoid temperature show high strength (380 MPa) and good ductility (25-35%). The microstructure of this alloy is composed of fine grains of aluminum solid solution a and zinc solid solution η and e phases. When the alloy is extruded between 280°C and 320°C, the resultant alloy is super plastic with microstructure formed by fine grains (0.5 μm to 2 μm). Higher extrusion temperatures, cause embrittlement of the material, likely caused by the presence of a low melting point Zn rich eutectic phase at the grain boundaries formed during the solidification.

Effect of temperature on the grain boundary movements during creep in copper and a copper-zinc alloy

Previous work by the present authors [1] showed that the presence of second phase particles of zinc at the boundaries of copper grains blocked the absorption of lattice dislocations by these boundaries during sliding at steady state creep. This was detected from measuring the sensitivity parameter of the steady creep rate to the applied stress at wide range, either for pure copper or for copper 28 wt% zinc solid solution. In this work we cansider the effect of temperature and accordingly the redistribution and diffusion of these zinc atoms at the copper grain boundaries on this blocking phenomenon. It was found that changing the temperature from 200°C to 400°C did not alter the suppression of grain boundary movements and, accordingly, their cooperation to creep deformation was also suppressed.

Effect of scandium on the decomposition of aluminium-zinc alloys

The effect of scandium on the hardness, structure and heat evolution of an aluminium-40% zinc alloy was investigated. It was found that contrary to its action in other aluminium-based alloys, scandium does not raise the maximum hardness during an ageing treatment. This may be explained by insufficient scandium redissolution at the rather low temperature necessary for achieving a solid solution of zinc in aluminium. Differential scanning calorimetry studies show a similar heat evolution in both alloys upon linear heating, starting with the reversion of modulated structures. An exothermal effect appears only in the scandium-bearing alloy due to increased heterogeneous precipitation of α′r, and β on Al3Sc particles. Above 200 °C, the dissolution of the α′r and β phases starts, followed by the monotectoid reaction.