This study considers the role of chloride and sulphate anions in the cathodic reduction of zinc ions from gluconate solutions (chloride, sulphate, chloride-sulphate). Cyclic potentiodynamic and potentiostatic polarization measurements, as well as chronoamperometric experiments, were performed. Electrochemical results were correlated with the speciation of the baths. The experiments revealed the inhibiting effect of sulphate ions on the cathodic process caused by the formation of stable neutral ZnSO4 complex in the sulphate-gluconate bath. It resulted in zinc deposition under a limiting current, with the release of metal cation as a rate-determining step. The less stable ZnGlu+ complex dominated both chloride-containing baths, thus the metal deposition ran under activation control. Independent of the solution composition, the nucleation of zinc occurred according to the instantaneous model.
The research on the dispersal of slag from the slurry process was carried out in a laboratory resistance furnace. Before declaring, the slag contained 13.62% copper. In the processes of reduction of slag samples with calcium carbide in the form of carbide with activating additives Na2CO3 and CaF2, the content of copper in the slag was reduced to a level of 0.28–0.63% Cu. The polymetallic melt formed after the decoupling of the slag contained 78.55–84.9% Cu, 10.8–16.48% Pb, and 0.08–0.39% Fe.
During research work on Non-Ferrous Metals Faculty concerning on the new corrosion inhibitors of iron alloy in magnetic field, Ho3+ ions were proposed as one of the new inhibitors. One of the methods to determine the rate of corrosion process is determination of concentration of Fe ions in solution. Due to required high precision of the determination of the concentration Fe ions in solution contains Ho3+ ions in a wide range of concentrations, the influence of matrix effect and interferences of Ho3+ ions must be known. The present work investigates the impact of Ho ions in rang 0 to 100 mg/L for the quantitation of Fe ions in 0.1 M HCl solution using MP-AES method. Obtained results were analyzed using single-factor ANOVA method. In range up to 40 mg/L Ho3+ ions is not significant factor to determination of Fe concentration by MP-AES.
The electrodeposition of silver from AgNO 3 solutions with the addition of L-tartaric acid was investigated. The cathodic reaction was accompanied by low electrode polarization and run under activation control for AgNO 3 concentrations of above 70 mM. Tartaric acid only slightly shifted the polarization curves towards more electronegative potentials (by approx. 50 mV), but it did not change the rate-determining step. The activation control of the process resulted in the formation of rough and coherent deposits, while the mixed or diffusion control of the process promoted the formation of dendritic-like structures and spongy deposits.
The effect of the initial texture on the deformation mode and mechanical properties was studied in magnesium and its AZ61 alloy. Both materials had a very similar initial texture. Two cases were investigated: samples with a texture where the basal slip system was blocked, and samples having a texture where the basal slip system was allowed to activate. The samples were deformed by compression at room temperature at a strain rate of 10 -3 s -1 . It was found that the initial texture had a very strong impact on the deformation mode in magnesium; however, there was no effect of the initial texture on the deformation mode in the case of AZ61. The investigations were compared to simulations of texture evolution using the Taylor model. From the simulations, the Taylor factor and slip system activity were obtained. It was found that, in the case of magnesium, twinning or slip (both basal and non-basal) are the two main deformation modes, while in the case of AZ61, slip is the only main deformation mechanism despite the initial texture. The impact of the initial texture is discussed in more detail in the present study.
This paper presents the numerical simulation results of the liquid steel flow in a six-strand tundish used for casting billets. The influence of using a ladle shroud, changing its immersion depth in liquid steel on the transition zone, and shaping the liquid steel volume flow were tested. Three positions of the ladle shroud immersion depth in liquid steel were checked. The computer calculation results have shown that the use and position change of the ladle shroud locally influences the shape of the liquid steel hydrodynamic structure in the tundish. The numerical simulations were carried out using the Ansys-Fluent computer program.
Knowledge of the characteristics describing the technological properties of the material is the basis for correct numerical simulation and the design of new technological processes or the modernization of existing ones. For each technological process of plastic forming, a set of features should be defined that correctly describe the susceptibility of the material to its shaping in a given process.The paper presents the results of rheological tests of 6xxx series Al alloy, obtained for deformation parameters corresponding to the process of the extrusion of large-size profiles. The effect of deformation conditions on changes in yield stress was determined. Next, the true values of the mathematical model coefficients describing the rheological properties of the tested material were determined using the inverse method, which is the basis for conducting numerical tests.
Clinching is an effective joining technique for lightweight sheet materials that are difficult or impossible to weld. Clinching is a relatively new technology in which two to three sheet metal parts are joined together by a process of local plastic deformation without the use of any additional components with the application of a special tool. In this study, an experimental investigation of clinch joints was performed. A non-standardized technique was used to determine the optimal joint geometry for further experiments. The used material type was DP600 (dual-phase, advanced high strength steel).
The Al/Fe material was prepared by the powder metallurgy route with an additional intermediate stage which was a centrifuge of powder mixture. The application of the centrifuge stage was applied to obtain circular phase distribution of Al-rich phases in a sintered material. Iron powder with a particle size under 100 μm and aluminum powder with a particle size of about 25 μm, were used as starting materials. To determine the effect of centrifuging time on the distribution of Fe-Al particles, scanning electron microscopy (SEM, EDS) and XRD techniques were used. Microstructure observations show the influence of the centrifuging time on the distribution of Fe particles. It was observed that a longer centrifuging time caused changes in the ratio concentration of elements and allowed the growth of the intermetallic phase at the interface between solid Al and Fe particles.
Friction stir welding (FSW) technology allows for the welding of materials that differ in their chemical compositions, microstructures, and properties. When selecting the parameters, it is necessary to analyze the structure of a weld and eliminate the defects. The use of X-ray microtomography creates the possibility of precise imaging of a joint structure – especially when it contains defects (voids). The tests were carried out on an FSW joint made with both 2017A and AlSi9Mg aluminum alloys. The macrostructure was cross-sectional, and a defect was found in the middle part of the joint and on the advancing side. We used a conventional method of observation light microscopy. Then, an analysis was performed using X-ray microtomography, which revealed the shape of the defect in 3D. Individual cross-sections were extracted, which enabled us to measure the geometric quantities. A dependence was found for the shape of the defect on the welding parameters and the variability of its construction. The usefulness of this advanced material imaging technology for the analysis of FSW welds has been confirmed.
Changing market preferences regarding expectations in terms of the functionality, properties, and appearance of a finished product place excessive demands on manufacturers. The 6xxx-series alloys are the most commonly used in extrusion, and they have broad applications (e.g., the construction, electronics, automotive, and shipbuilding industries). The development of deformation technology at the design stage reaps unquestionable benefits when planning the production process. Under real conditions, the extrusion of hollow profiles requires the use of pocket dies, whose proper design is a complex process. This paper presents the results of preliminary numerical investigations of the extrusion process of structural panels from the 6005A aluminum alloy intended for the construction of transport car bodies. The influence of selected parameters of the extrusion process on the temperature distribution was analyzed in the material. The calculations were made using FEM for a three-dimensional deformation state, taking into account the thermal phenomena occurring during the applied deformation scheme in the extrusion process carried out in a flat die.
The presented study performs an analysis of the effect of thermal treatment on the microstructure and corrosion resistance of the commercial prosthetic alloy Wironit ExtraHart (Co-Cr-Mo). Experiments of thermal treatment, homogenization, oversaturation as well as oversaturation with ageing of the alloys were carried out. Metallographic tests, hardness measurements, EDS analyses and electrochemical investigations were performed. For the examined samples, the corrosion potential (OCP) and polarization curve (LSV) were determined, based on which the corrosion properties in the simulated solution of artificial saliva were established. The results of the obtained tests made it possible to evaluate the effect of the performed thermal treatment on the changes in the properties (hardness) as well as the microstructure and corrosion resistance of the examined alloy Co-Cr-Mo.
The iron nanowire arrays (NWs) were fabricated by DC electrodeposition into hexagonally ordered alumina pores. With the use of X-ray diffraction analysis, the structure of iron wires was determined. The iron wires have the Body Centered Cubic structure. The influence of cathodic deposition potential and parameters of membrane on the magnetic properties of nanowire arrays was investigated. Magnetic properties analyzed by VSM measurements suggest that the easy axis of magnetization follows the nanowire axis, with coercivity increasing with a decrease of nanowire diameter and length. The dependence of the height of Fe wires on the electrodeposition potential was determined. The low cathodic potential and smaller pore diameter are the synthesis parameters most beneficial for large coercivity with easy axis along nanowires.
Our research focused on Inconel 625 weld overlays on 16Mo3 steel boiler pipes. The investigation focused on the characterization of changes in the microstructure and chemical composition after annealing. The annealing was performed for ten hours at temperatures from 600 to 1000°C. Changes in the microstructure were observed with a scanning and transmission electron microscope (SEM and TEM). The investigation was supplemented by hardness measurements.
This paper presents the results of the structural investigations and thermophysical properties of 904L steel parent material. Experimental studies on the structure of 904L steel proved a pure austenitic structure. Both the experimental research and analysis of the thermophysical properties of 904L steel were complemented with the results of the thermal conductivity calculations for the tested material. The paper presents a brief description of the measurements, the procedures for evaluating the data, and a set of the obtained results.
Basic electrochemical experiments on the kinetics of tin deposition from an acid sulfate solution containing organic additives were performed. The measurements showed that tin deposits with activation polarization in a narrow potential range. Organic additives like gelatin and β-naphtol inhibit the charge transfer stage of the cathodic reaction due to the formation of adsorption layers. In turn, the gluconate ions increase the rate of tin deposition due to the bonding of hydrogen ions and inhibiting hydrogen coevolution. This results in serious changes in the morphology of tin deposits from isolated polyhedron crystals (no additive) via rectangular plates (β-naphtol) and thin plates (sodium gluconate) to rounded grains (gelatin).
This article presents the results of the physical modeling of the continuous casting of steel slabs in a mold. The experiments focused on the assessment of the shape and stability of the liquid mold slag layer, which was reproduced in studies using silicone oil. The experimental tests were carried out for two different geometries of the submerged entry nozzle, two extreme submergence depths of the submerged entry nozzle (0.215 and 0.295 m), and two extreme casting speeds (1.0 and 1.6 m/min) used in industry. For each variant of the experiment, photographic documentation of the oil layer’s behavior was presented and discussed. The research was supplemented with a visualization of the flow structure using a marker for the selected variant of the experiment.
The present paper examines and compares the influence of austempering parameters such as temperature and time on the isothermal transformation and microstructural changes of ductile iron. To identify the compositional and structural changes during an isothermal transformation, a very wide austempering period is chosen at a transformation temperature for the precise determination of the process window. XRD, optical, and scanning electron microscopic techniques are exploited to identify and analyze the changes in the austempered structure, at austempering temperatures of 250°C and 400°C. The various structural parameters like austenite volume fraction (Vg, its carbon content (Cg), lattice parameter, and the average cell size of the ferrite are ascertained. Electron backscattered diffraction (EBSD) analysis is used to identify the carbide precipitation obtained due to the austempering Stage-II reaction. It is noticed that, at the end of the austempering Stage-II reaction, there is a significant reduction in the volume fraction of stabilized austenite and it’s carbon content, as the microstructure at this stage not only contains ausferrite but also additional precipitated iron carbides. With an increase in austempering time, the austenite and ferrite volume fraction increase until the austenite becomes stabilized with sufficient carbon. The increase in the lattice parameter of the austenite during austempering corresponds to the rise in carbon content within the austenite. A rise in the austempering temperature leads to a reduction in the volume fraction of the ferrite and an increase in the stabilized austenite volume fraction. The optimum isothermal transformation period for austempered ductile iron is established, based on the period during which the maximum content of the austenite volume fraction, its carbon, the lattice parameter, and the average cell size of the ferrite are maintained.
