Pb Alloy Research Articles

Effects of Bi–Sn–Pb Alloy and Ball-Milling Duration on the Reactivity of Magnesium–Aluminum Waste-Based Materials for Hydrogen Production

In the present study, composite materials were elaborated of mixed scrap of Mg-based casting alloys and low melting point Bi–Sn–Pb alloy by high energy ball milling, and their reactivity in NaCl solution with hydrogen release was tested. The impacts of the additive content and ball milling duration on their microstructure and hydrogen generation performance were investigated. Scanning electron microscopy (SEM) analysis revealed significant microstructural transformations of the particles during milling, and X-ray diffraction analysis (XRD) proved the formation of new intermetallic phases Mg3Bi2, Mg2Sn, and Mg2Pb. The said intermetallic phases were anticipated to act as ‘microcathodes’ enhancing galvanic corrosion of the base metal. The dependency of the samples’ reactivity on the additive content and milling duration was determined to be nonmonotonic. For the samples with 0, 2.5, and 5 wt.% Rose alloy, ball-milling during 1 h provided the highest hydrogen generation rates and yields (as compared to 0.5 and 2 h), while in the case of the maximum 10 wt.%, the optimal time shifted to 0.5 h. The sample activated with 10 wt.% Rose alloy for 0.5 h provided the highest ‘metal-to-hydrogen’ yield and rapid reaction, thus overperforming those with lower additive contents and that without additives.

Electrochemical behavior of zinc anode in acidic zinc electrolyte -influence of lead as an impurity in zinc anodic dissolution

Zinc is common metal used for steel protection. In this work, an alloy Zn-1 % wt. Pb was prepared by fusion at 500°C. The analysis of the corrosion behavior was studied with pure Zn anode as control in aerated solution of 0.9 M ZnSO4.7H2O + 1.63 M H2SO4 at 38°C.The effect of lead impurity on corrosion resistance of zinc anode in zinc electrorefining process was investigated using open circuit potential (OCP), Tafel plots, chronoamperometry at imposed constant anodic potential and electrochemical impedance spectroscopy (EIS) techniques. Samples were characterized by chemical analysis, optic microscope (OM) and X-ray diffraction (XRD). The results show that the lead impurity leads to degradation of the behavior of the alloy due to negative effect on the microstructure. Lead increases the corrosion rate and decreases the corrosion resistance of Zn-1 % wt. Pb alloy.

Shielding Properties of Al- Cu- Pb Alloys by XCOM and Experimental Data

The current study, the efficiency of many binary and triple aluminum alloys was examined for the alloy’s samples consisting of (Al-Cu-Pb). These alloys were manufactured in the laboratories of the physics Department and the manufacture of melting furnaces as well as the design of casting molds, and then we used the gamma ray penetration technique to study the behavior of radiation attenuation by the manufactured alloys. The shielding properties of the prepared samples include mass attenuation coefficient ( ), radiation protection efficiency (RPE), half-value layer (HVL), and mean free path (MFP), Which were calculated theoretically using XCOM software. Experimental measurements were made at 60Co (1173, 1332 keV) 137Cs (662 keV) using a Gama spectrometer, which it contains the NaI (Tl) detector. It found that there is a good agreement between the experimental and theoretical values.

Flow-enhanced remelting of settling/floating globular crystals during mixed columnar-equiaxed solidification

Previously, the authors have used a mixed columnar-equiaxed solidification model, successfully ‘reproduced’ the solidification benchmark experiments on the Sn-10wt.%Pb alloy under natural/forced convections (travelling magnetic stirring) as performed at SIMAP laboratory [Int. J. Heat Mass Transf. 85 (2015) 438-54]. The current contribution is to address the flow-effect on the remelting of settling/floating crystals during the mixed columnar-equiaxed solidification. The re-melting or growth is controlled by diffusion of solute in the liquid boundary layer. The diffusion length due to the flow-effect is modelled as a function of Schmidt and Reynolds numbers. The modelling results show that remelting rate of the floating/settling crystals, which originate from fragmentation and then brought to the superheated region by the forced flow, can be enhanced by the flow. In turn the released latent heat can reduce the temperature locally (even globally), hence to speed up the solidification of the columnar structure. Additionally, the solidification-migration-remelting of equiaxed grains present an important macrosegregation mechanism. By solidification of a crystal in the cold region it rejects solute, while by remelting of the crystal it dilutes the surrounding melt. These phenomena are found critical in many engineering castings with mixed columnar-equiaxed solidification.

Novel insight into the self-lubricating mechanism of Cu–Pb bearing alloy during sliding friction with the guidance of molecular dynamics

The self-lubricating mechanism of Cu–Pb bearing alloy is discussed by molecular dynamics (MD). MD friction tests are conducted on the pure Cu and Cu–Pb models. The Pb-rich secondary phases (PSPs) melt due to the frictional heat. The solid–liquid phase transition of Pb is characterized by the radial distribution function (RDF) and the potential energy. An obvious drop of motion resistance of the abrasive debris is observed in Cu–Pb alloy once the debris moves close to the soft PSP which protect the matrix from abrasion by embedding the debris and promoting the formation of a liquid lubricant film. The synchrotron radiation technology is employed to in-situ observe the phase transition of Pb, and the MD results match the experimental results well.

Effect of forced convection on the formation of the as-cast structure and macrosegregation of Sn-10wt.% Pb alloy: A numerical study

A series of solidification benchmark experiments based on Sn-10wt.% Pb alloy were performed at the SIMAP Laboratory in Grenoble, France (Hachani et al., 2015) to study the effect of different types of forced convection on the as-cast structure and macrosegregation. Forced convection was achieved by using a traveling magnetic field (TMF). Four cases were investigated: without TMF; TMF in the same direction as natural convection; TMF in the opposite direction as natural convection; and TMF periodically reversed with respect to natural convection. In the current study, a three-phase mixed columnar-equiaxed solidification model was used to “reproduce” the above experiments to understand the flow effect on the as-cast structure formation. The dendrite fragmentation is regarded as the only source of equiaxed grains. Remelting/destruction of equiaxed grains in the superheated melt is considered. The continuous growth of the surviving equiaxed grains and further competition with the as-developed columnar dendrites, leading to columnar-to-equiaxed transition (CET), are included. Except for Case III (i.e., a TMF in the opposite direction as natural convection), satisfactory simulation-experiment agreements in terms of the temperature field, as-cast structure and macrosegregation are obtained for the remaining three cases. Based on the simulation results, it is found that 1) TMF plays an important role in homogenizing the temperature field and promoting the formation of equiaxed grains via fragmentation, consequently facilitating the appearance of CET; 2) TMF tends to generally intensify macrosegregation and increase the number of channel segregations; and 3) the simultaneous solidification/remelting process represents a significant species/energy transport mechanism. Ignoring the remelting of equiaxed grains would lead to an overestimate of the local temperature in the remelting zone. The reason for the mismatch between the simulation and experimental results obtained for Case III is discussed.

First principle calculation of structural, electronic, magnetic, and elastic properties of ferromagnetic Cu2MnZ (Z = Pb, P, As, Bi, S, Se, and Te) Heusler alloys

We predicted new series of Heusler alloys from X2YZ type full Heusler Cu2MnZ (Z = Pb, P, As, Bi, S, Se, and Te) alloys, using density functional theory (DFT)-Projected Augmented Wave (PAW) pseudopotential method. We carried out detailed electronic structure and elastic properties calculations to find the suitability of this new series of Heusler alloys for device applications. From the structural, electronic, and magnetic calculations, we have found that Cu2MnZ (Z = Pb, P, As, Bi, S, Se, and Te) alloys are having a regular Heusler structure with ferromagnetic (FM) ground state. We explained the metallic and ferromagnetic nature of the proposed alloys with the help of spin-polarized density of states (DOS) and orbital-resolved DOS calculations. Interestingly, the contribution to the total magnetic moment in Cu2MnZ arises entirely from the Mn atoms. Further, elastic property calculation reveals that Cu2MnZ exhibit ductile nature and is found to be less compressible.

The fabrication of Pt–Pb alloy networks with high-density micropores by dealloying for enhanced oxygen reduction activity

Porous Pt-based nanomaterials possess intriguing properties for various important applications due to their abundant exposed active sites and highly accessible surfaces. Importantly, the pore size is a key factor that determines its specific applicability. With the advances of fabrication strategies, Pt-based nanomaterials with a variety of unique pore structure including mesopores and macropores have been extensive reported. However, so far, few effective methods have been reported to prepare the Pt-based nanomaterials with high-density micropores. In this work, we reported a facile method to prepare the high-density microporous Pt–Pb NWs via a chemical etching strategy by using the intermetallic PtPb networks (NWs) as the starting material. After dealloying, a large amount of microporous and defects were successfully introduced into the MP-PtPb NWs. The microporous networks can not only increase the active area both on the exterior and interior surface, but also provide efficient mass transfer and electron mobility for reactant molecules. As a result, the mass activity exhibited by MP-PtPb NWs catalyst is 0.83 A mg−1Pt, which is 5.8 and 1.9 times than that of commercial Pt/C and IM-PtPb NWs. Besides, even after 10,000 cycles of accelerated durability test, the MP-PtPb NWs and IM-PtPb NWs exhibit comparable drop of ∼10% in mass activity, against a big decrease of 46% for commercial Pt/C. We believe this work provides an efficient strategy to prepare metallic catalysts with high-density microporous nanomaterials for catalysis.

Surface tension of liquid mixtures and metal alloys. Positive and negative temperature coefficients in alloys with remarkably high surface density

The effect of temperature on the surface tension is examined in liquid alloys that combine a positive or negative temperature coefficient with gravity limitation of the surface concentration in the surface-active metal constituent. This is a restriction that is likely to occur in alloys where the metal with lower surface tension is much denser than the other component. Since there is a surface tension increase due to diminished segregation, the resultant temperature coefficient will depend on the superposition of two independent effects. Working in the framework of Butler’s thermodynamics for ideal surface phases, equations and methods of analysis are obtained to describe both effects. These developments are illustrated with alloys where the surface density is likely to attain the bulk density at certain compositions, namely the Al–Zn alloys that exhibits a negative temperature coefficient and the Sn–Bi, Ga–Bi, Ga-Pb and Cu–Pb alloys that present composition ranges with positive temperature coefficients. The specific concave down dγ/dT curves of liquid alloys are theoretically predicted. Furthermore, good estimates are obtained for systems with positive and negative temperature coefficients, except within a 50 K interval of phase transitions, or for systems showing large deviations from ideal behaviour.

Study the effect of adding zirconia particles to nickel–phosphorus electroless coatings as product innovation on stainless steel substrate

Abstract Scholars have spent much time studying metal deposition procedures involving the deposition of electroless nickel, alloy, and composite coatings on various surfaces; the most current uses were feasible advantages of the coatings’ many good properties for achieving the final product innovation. Lately, these coatings have demonstrated intriguing wear and corrosion resistance features, resulting in several innovative macro-level developments. The notion of composite coating by co-deposition coating has been presented in this article. The characteristics of Ni–Pb alloy coatings were examined by inserting ZrO 2 {{\rm{ZrO}}}_{2} particles into the electroless deposited solution. The stainless steel (SS) specimens have been electroless coated with Ni–Pb and ZrO 2 {{\rm{ZrO}}}_{2} nanoparticles (size = 30–70 nm) at 0, 10, and 20 g/L amounts. The materials have been examined using scanning electron microscope and atomic force microscope, followed by wear-resistant and microhardness testing. According to the investigation findings, including inert particles improved the hardness magnitude and wearing resistance considerably. The base metal exhibited the highest wear rate at 10 N, while the wear rate decreased in the Ni–Pb– ZrO 2 {{\rm{ZrO}}}_{2} -coated SS316L by 34%. The Vickers hardness magnitudes of the Ni–Pb– ZrO 2 {{\rm{ZrO}}}_{2} -coated samples at different ZrO 2 {{\rm{ZrO}}}_{2} contents (0, 10, and 20 g/L) were 19, 50, and 81%, respectively.

Hybrid Composite Foams Based on Pb Alloys for Lightweight Batteries

Hybrid Composite Foams Based on Pb Alloys for Lightweight Batteries

Determination of As, Bi, Pb, Sb, and Sn in Copper, Nickel, and Alloys on Their Basis by Electrothermal Atomic Absorption Spectrometry

Determination of As, Bi, Pb, Sb, and Sn in Copper, Nickel, and Alloys on Their Basis by Electrothermal Atomic Absorption Spectrometry

Electrochemical performance of novel Pb alloys reinforced with Ni-coated fly ash microballoon composite foams in Lead Acid Battery

Novel Pb composite foams comprising hybrid gas pores and Ni-coated fly ash microballoons were produced by direct melt foaming method. Pb composite foams were designed to have a lower weight and larger surface area to be used in the Lead Acid Battery (LAB) as alternative to the traditional Pb grids, offering benefits in the transportation industry. The Ni-coated fly ash microballoons were added to Pb alloy melt to serve as thickening agent and pores, which were wholly enclosed within the microballoons, as well as reinforcements. The electrochemical performance of Pb grids used in traditional LAB and Pb composite foams produced in the present work was investigated for comparing purposes. The cured plates form positive and negative electrodes of Pb grid and Pb composite foams were characterized by X-ray diffraction to identify the different Pb compounds and phases. The morphology of the cured plate was found to contain flakes and dendritic structure. Zones were formed from a network of Pb particles in the negative electrode covered with PbSO4 crystals. The PbSO4 crystals exhibited miscellaneous morphology. The matrix of lead basic sulphate crystals was converted into aggregates of PbO2 particles in the positive electrode morphology, which maintained the form of the original substance. Cyclic voltammetry measurements (CV) were conducted in 3 M H2SO4 to study the anodic oxidation and cathodic reduction peaks of Pb, PbSO4 and PbO2. The galvanostatic polarization for oxidation and reduction steps was measured at different current densities. It revealed the benefit that the Pb matrix composite foam showed a longer period for oxidation of Pb into PbSO4. The composite foams exhibited a greater specific discharge electrical capacity than the Pb alloys used in traditional LAB.

Computational study of structural stability, elastic, electronic, magnetic and thermodynamic properties of the Rh2-based full-Heusler compounds: Rh2MnZ (Z = Sn, Pb, Tl) by FP-LAPW method

The structural, elastic, electronic and thermodynamic properties as well as the magnetism of the ternary full-Heusler alloys Rh2MnZ (X = Sn, Pb and Tl) have been investigated by using full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) within the generalized gradient approximation (GGA). The AlCu2Mn-type structure is energetically more favorable than the CuHg2Ti-type structure for all the compounds studied here and found to be are ferromagnetic. The electronic structures calculations are found to exhibit a metallic character for all the herein studied compounds Rh2MnZ (X = Sn, Pb and Tl) alloys. The magnetic properties reveal that the Mn atom is responsible for large magnetic moment. Moreover, the mechanical behavior shows that all studied compounds are mechanically stable, ductile and anisotopic in nature. The elastic and thermodynamic properties for Rh2MnTl compound have not yet been established. The obtained results for various properties of the series of Rh2MnZ (X = Sn, Pb and Tl) are compared with those found experimentally and theoretically.

Mixing Enthalpies of Liquid Ag-Mg-Pb Alloys: Experiment vs. Thermodynamic Modeling.

A drop calorimetric method was used to measure liquid Ag–Mg–Pb alloys. The partial and integral mixing enthalpies of the investigated alloys were determined at a temperature of 1116 K. The experiments were performed for four separate series starting from binary alloys with a constant xMg/xPb ratio of 1/3, 1, 3 ((Mg0.25Pb0.75)1−xAgx, (Mg0.50Pb0.50)1−xAgx, (Mg0.75Pb0.25)1−xAgx) and xAg/xMg ratio of 1/3 (Ag0.25Mg0.75)1−xPbx. Next, the ternary interaction parameters were determined using the Muggianu model, the thermodynamic properties of binary systems in the form of the Redlich-Kister equations and the values of the mixing enthalpy changes, which were determined in this study. The partial mixing enthalpies of Ag, Mg, and Pb were calculated based on the binary and elaborated ternary interaction parameters for the same intersections in which the measurements were conducted. It was found that the ternary Ag-Mg-Pb liquid solutions are characterized by negative deviations from the ideal solutions, with a maximal value slightly lower than –13 kJ/mol for alloys with the ratio (Mg0.75Pb0.25) and xAg = 0.4166.

Realizing high-ranged thermoelectric performance in PbSnS2 crystals

Great progress has been achieved in p-type SnS thermoelectric compound recently, while the stagnation of the n-type counterpart hinders the construction of thermoelectric devices. Herein, n-type sulfide PbSnS2 with isostructural to SnS is obtained through Pb alloying and achieves a maximum ZT of ~1.2 and an average ZT of ~0.75 within 300–773 K, which originates from enhanced power factor and intrinsically ultralow thermal conductivity. Combining the optimized carrier concentration by Cl doping and enlarged Seebeck coefficient through activating multiple conduction bands evolutions with temperature, favorable power factors are maintained. Besides, the electron doping stabilizes the phase of PbSnS2 and the complex-crystal-structure induced strong anharmonicity results in ultralow lattice thermal conductivity. Moreover, a maximum power generation efficiency of ~2.7% can be acquired in a single-leg device. Our study develops a n-type sulfide PbSnS2 with high performance, which is a potential candidate to match the excellent p-type SnS.

Modeling and measurement of vapor-liquid equilibrium of In–Pb and In–Pb–Sn alloy systems in vacuum distillation

This study reports the measurement and modeling of vapor-liquid equilibrium (VLE) in In–Pb and In–Pb–Sn alloys subjected to vacuum distillation at a system pressure of 5–10 Pa in the temperature range of 1100–1280 K. Pb and In was satisfactorily separated by a single-stage distillation at 1180 K. Pb was thoroughly removed from In–Pb–Sn alloy by a single-stage distillation at 1220 K. Molecular interaction volume model (MIVM) was used to calculate the activities of components of In–Pb alloy. The deviations were small. The activities of components of In–Pb–Sn alloy were also predicted by MIVM. The VLE of In–Pb and In–Pb–Sn alloy systems were predicted by MIVM and VLE theory. The calculated results agree well with VLE data determined from experiments, which indicates that the calculated VLE is reliable. The VLE can be used to guide the separation of indium-based alloys by vacuum distillation. In this study, the model prediction was combined with vacuum distillation experiments, which not only verified the reliability of MIVM for indium-based alloys, but also optimized the process parameters of vacuum distillation of indium-based alloys, providing theoretical guidance for the separation and purification of indium-based alloys by vacuum distillation or the treatment of indium-containing complex materials.

Development and benchmarking of numerical model in OpenFOAM® for the prediction of channel segregation during columnar alloy solidification

• Benchmark sn-5 wt%Pb alloy solidification problem is simulated using OpenFOAM solver. • Mesh sensitivity analysis is performed to resolve the flow in channels segregates. • Effect of microsegregation and mushy zone models on channels formation is studied. • Scheil's model predicts more negative and positive segregation than Lever rule. • Inertial drag in mushy zone significantly affects the channel segregates formation. In the past, most of the numerical studies on the prediction of macrosegregation and mesosegregation (e.g. channel type segregation) were performed using in-house codes and commercial software, both of which have limitations such as huge license costs, non-availability for general public research etc. In this study, a dedicated CFD solver is developed in an open-source platform – OpenFOAM® for the prediction and characterization of channel segregates in castings. The solver accounts for the fluid flow, heat transfer, species transport, multiscale segregation, solidification and mushy zone drag phenomena that occur during alloy solidification. The developed solver is extensively validated with the reported benchmarked experimental and numerical results for the sn-Pb alloy solidification. Direct numerical simulations (DNS) are performed to resolve the flow field in and around the channels (which are of mesoscopic length scale) for the first time. It is observed that mesh size ≤ 2 d 2 (secondary dendritic arm spacing) is required to resolve the flow in channels and accurately predict their morphology and locations. Further, the effect of different microsegregation and mushy zone drag models on the segregation and morphology of channel segregates is thoroughly investigated. The predicted extent of negative and positive segregation is found to be more (negative segregation ∼ 7.7 wt%Pb and positive segregation ∼ 18.7 wt%Pb) in Scheil’s microsegregation model compared to Lever rule. Furthermore, the inertial drag in the mushy zone significantly affects the convective transport of solute and thereby the morphology and the number of channel segregates.

Separation of antimony from lead-antimony alloy by molten salt electrolysis

Lead-acid batteries (LABs) are widely used in electric motorcycles, uninterruptible power systems, and stationary energy storage devices. However, spent LABs should be recycled to reuse lead (Pb) and thereby close the Pb cycle and avoid Pb contamination. In order to reuse the recovered Pb, the purity of recovered Pb should meet the required standard. Since antimony (Sb) is a common alloying element in Pb alloy grid such as the Pb-Sb alloy, separating Sb from the recovered Pb is necessary. In this paper, we proposed a molten salt electrolysis method to separate Sb from liquid Pb-Sb alloys in terms of forming a solid Ca-Sb intermetallic at the top of the liquid Pb-Sb cathode. The electrochemical separation process was performed in molten NaCl-CaCl2. The content of Sb (atomic percent) in the Pb-Sb alloy was reduced from 1% to less than 0.01% (atomic ratio). The recovery principle lies in the different alloying potentials between Ca-Sb and Ca-Pb. Hence, molten salt electrolysis is a promising separation method to recover pure Pb from spent Sb-containing Pb alloys.

Effect of grain size on damage and failure in two-phase materials: Homogenized CuPb

It is well known that spall failure strongly depends on the microstructure of a material. There have been numerous studies to study the effect of grain size on the overall spall strength and the total amount of damage in single element metals like copper. However, such systematic studies remain rare in two-phase materials and alloys. In this work, two incipient spall experiments were performed on a Cu–1%Pb alloy to understand the effect of grain size on the damage and failure in a two-phase material. Overall, these results showed that even though the spall strength did not change as a function of grain size, there were significant differences in the total amount of damage as a function of grain size. A clear increase in the total damage present in the material was seen as the grain size was increased from 32 to either 70 or 75 μm in either of the experiments. This difference was attributed to variations in the void growth rate as the grain size was increased.