Search Results (99)

A novel and cost-effective methodology is introduced for the precise prediction of the melting time of metals and alloys in a 700 W domestic microwave oven, using a hybrid SiC–graphite susceptor to ensure efficient heating without direct interaction with microwaves. The study includes experimental trials with multiple alloys (Sn–Bi, Zn, Zamak, and Al–Si, among others) and variable masses, whose results made it possible to construct a dimensionless model, trained with XGBoost on easily measurable thermophysical properties (specific heat, density, thermal conductivity, mass, and melting temperature). The model achieves high accuracy, with a relative error below 5%, and metrics of MAE = 4.8 s, RMSE = 6.1 s, and R² = 0.9996. The generalization of the model to different microwave powers (600–1100 W) is also validated through analytical adjustment, without the need for additional experiments. The proposal is implemented as a Python application with a graphical interface, suitable for any academic or teaching laboratory, and its performance is compared with classical models. This approach effectively contributes to the democratization of thermal testing of metals in educational and research settings with limited resources, providing thermodynamic rigor and advanced artificial intelligence tools. Full article

The corrosion behaviors of newly developed solder alloys with excellent mechanical properties, Sn-2.5 Ag-1.0 Bi-0.8 Cu-0.05 Ni (SABC25108N) and Sn-1.5 Bi-0.75 Cu-0.065 Ni (SBC15075N), are analyzed to supplement the corrosion behavior of the limited corrosion data in Pb- and Zn-free solder compositions. A potentiodynamic polarization test is conducted on these compositions in a NaCl electrolyte solution, the results of which are compared with those of conventional Sn-3.0 (wt%) Ag-0.5Cu and Sn-1.2Ag-0.5Cu-0.05Ni alloys. The results indicate that SBC15075N exhibits the lowest corrosion potential and highest corrosion current density, thus signifying the lowest corrosion resistance. By contrast, SABC25108N exhibits the lowest corrosion current density and highest corrosion resistance. Notably, SABC25108N shows a slower corrosion progression in the active state and exhibits the longest passive state. The difference in corrosion resistance is affected more significantly by the formation and distribution of the Ag₃Sn intermetallic compound phase owing to the high Ag content instead of by the presence of Bi or Ni. This uniform dispersion of Ag₃Sn IMC phases in the SABC25108N alloy effectively suppressed corrosion propagation along the grain boundaries and reduced the formation of corrosion products, such as Sn₃O(OH)₂Cl₂, thereby enhancing the overall corrosion resistance. These findings provide valuable insights into the optimal design of solder alloys and highlight the importance of incorporating sufficient Ag content into multicomponent compositions to improve corrosion resistance. Full article

The current research introduces a cost-effective thermal coating process using a tinning surfacing technique to synthesize WO₃ nanoparticle-reinforced Sn-20Bi (S20B) alloy coating on low-carbon steel (LCS). A ball-milling machine was used for mechanical mixing and blending of Sn and Bi powders together with 0.25 wt.% WO₃ nanoparticles. The produced powders were mixed with a prefabricated flux in two different ratios to optimize the best surface coating morphology. The synthesized coatings were spread out on the surface of the LCS in a layer of 0.25 g cm⁻² and were heated for 3, 4, and 5 min at 370 °C. A series of corrosion tests was carried out to understand the effect of the different S20B and S20B-WO₃ coatings on the corrosion passivation of the LCS samples in 3.5% NaCl solution. The coating surface layer thickness increased by decreasing the percentage of flux in the synthesized coating. Increasing the heating time (from 3 min to 5 min) increases surface coating uniformity and slightly boosts the average Fe−Sn intermetallic (IMC) layer thickness (from 1.7 ± 0.3 µm to 3.3 ± 0.3 µm). By incorporating 0.25 wt.% WO₃ nanoparticles into the S20B coating surface layer, a uniform microstructure was achieved and the thickness of the Fe–Sn IMC layer was reduced to 2.6 ± 0.3 µm. This study found that the presence of WO₃ nanoparticles significantly improved the corrosion resistance of S20B-coated LCS. These results demonstrate that adding a small of WO₃ nanoparticles significantly enhances the microstructural integrity and corrosion resistance of S20B coatings on LCS. Full article

To address the issue of sealing failure of cement materials commonly used as wellbore plugging agents in CO₂ geological storage, this study proposes a composite wellbore plugging method that combines cement and Sn58Bi alloy. In this method, a composite sealing structure of “cement–Sn58Bi alloy–cement” is constructed within the wellbore. To evaluate the performance of this method, a series of pressure-bearing and gas-tightness experimental devices were designed, and experiments were conducted to assess the pressure-bearing capacity and gas sealing performance of the composite plugs. Additionally, optical microscopy was employed to observe and analyze the microstructure of the plugs. The effects of alloy proportion and temperature on the sealing performance of the composite plugs were systematically investigated. The experimental results indicate that both the pressure-bearing capacity and gas-tightness performance of the plugs are influenced by the alloy content and ambient temperature. Specifically, when the temperature increased from 30 °C to 60 °C, the pressure-bearing capacity decreased by an average of 28.3%; when further increased from 60 °C to 90 °C, it decreased by an average of 21.1%. In contrast, the gas-tightness performance exhibited an opposite trend, with the breakthrough pressure increasing by an average of 25.7% and 22.0%, respectively, over the same temperature intervals. Moreover, increasing the alloy proportion in the composite plugs enhanced both their pressure-bearing and gas-tightness performances. This study provides theoretical support for the application of composite plugs in CO₂ geological storage. Full article

In the fields of nuclear engineering and solar thermal utilization, low melting point alloys with excellent thermal conductivity and heat transfer performance have attracted extensive research as a new generation of heat transfer fluids, leading to many fundamental and important application issues. This study investigates the high-temperature corrosion behavior of Sn-50Bi-2Zn (wt.%) heat transfer alloy against 304 stainless steel (304), 310S heat-resistant steel (310S), and 20 carbon steel (20C) at 600 °C. Theoretical analysis, based on Fick’s diffusion law, and experimental measurements reveal significant differences in corrosion severity. After 473 h, 20 carbon steel exhibited the lowest corrosion layer thickness (0.07 mm), while 310S suffered the most severe corrosion (1.50 mm), exceeding 304SS (0.83 mm) by 81%. Diffusion coefficients derived from Sn penetration depths further quantified these trends: D310S = 2.51 × 10⁻⁷ mm²/s (6.8 × higher than 304: 3.7 × 10⁻⁸ mm²/s) and D20C = 2.87 × 10⁻¹⁰ mm²/s (128 × lower than 304SS). XRF analysis confirmed the dissolution of steel components into the molten alloy, with Fe, Cr, and Ni content increasing to 0.382 wt.%, 0.417 wt.%, and 0.694 wt.%, respectively, after 480 h. These results underscore the critical role of Ni content in accelerating Sn/Zn diffusion and pore formation, providing actionable insights for material selection in high-temperature heat transfer systems. Full article

As semiconductor packaging technologies face limitations, through-silicon via (TSV) technology has emerged as a key solution to extending Moore’s law by achieving high-density, high-performance microelectronics. TSV technology enables enhanced wiring density, signal speed, and power efficiency, and offers significant advantages over traditional wire-bonding techniques. However, achieving fine-pitch and high-density interconnects remains a challenge. Solder flip-chip microbumps have demonstrated their potential to improve interconnect reliability and performance. However, the environmental impact of lead-based solders necessitates a shift to lead-free alternatives. This review highlights the transition from Sn-Pb solders to lead-free options, such as Sn-Ag, Sn-Cu, Sn-Ag-Cu, Sn-Zn, and Bi- or In-based alloys, driven by regulatory and environmental considerations. Although lead-free solders address environmental concerns, their higher melting points pose challenges such as thermal stress and chip warping, which affect device reliability. To overcome these challenges, the development of low-melting-point solder alloys has gained momentum. This study examines advancements in low-temperature solder technologies and evaluates their potential for enhancing device reliability by mitigating thermal stress and ensuring long-term stability. Full article

In order to solve certain issues, such as brittle fracture corrosion and easy failure, which occur under high ambient temperatures and high breakthrough pressures when conventional cement is used to plug rock perforations, a method using a Sn58Bi alloy was adopted in this paper; it was utilized to melt and plug a perforation. Subsequently, the influence of the characteristics of the rock perforation (such as perforation length and diameter) on alloy plugging performance under different conditions and ambient temperatures was studied. The experimental results show that the plugging effect of the Sn58Bi alloy was affected by ambient temperature, plugging diameter, and length. When the plugging length was 100 mm and the perforation diameter was 10 mm, the mechanical plug performance decreased by 24.0% when the ambient temperature increased from 30 °C to 60 °C, and then decreased by 19.0% when the ambient temperature increased to 90 °C. At 30 °C, the mechanical plug performance decreased by 30.4% when the diameter decreased from 10 mm to 8 mm, and decreased by 28.0% when the diameter decreased to 6 mm. When the length was constant and the diameter was decreased from 10 mm to 8 mm and then to 6 mm, the hydraulic plugging effect became better, and the trend increased from 33.7% to 37.2%. Full article

Soldering with Sn alloys has always been the essential assembly step of microelectronics. The conductive Sn whiskers, which can spontaneously grow from soldering surfaces, mean a considerable reliability risk for microelectronics due to possible short circuit formation between the leads of the components. Since their discovery in 1951, thousands of research studies have been conducted to unravel their growth mechanisms and find effective prevention methods against them. Till 2006, the Sn whisker problem was solved and partially forgotten due to the very effective whisker suppression effect of Pb alloying into the solder materials. The lead-free change gave new impetus to the problem, which was further enhanced by the application of new material systems, growing reliability requirements, and accelerating miniaturization in the 21st century. Our review would like to give an overview of the Sn whisker’s history from the beginning till the latest results, focusing on the suppression solutions by the modification of the solder alloy compositions. Recently, promising results have been reached by alloying Bi and In, which are metals that are the focus of low-temperature soldering, and by composite solders. Full article

Aiming at the problem of the cement hydration shrinkage phenomenon, which occurs when cement seals downhole casing in the process of Carbon Capture, Utilization, and Storage (CCUS) technology, this paper proposes a method of sealing the casing by combining threaded casing with bismuth–tin alloy. The effect of different types of grooves (square-, trapezoidal-, and screw-threaded grooves) set on the inner surface of the casing on the gas sealing performance of the alloy plug was analyzed. And the effect of the overlay pressure on the gas sealing performance of the alloy plug during the molding process was analyzed. The experimental results show that under 0.2 MPa overlay pressure, the gas breakthrough pressure values of alloy plugs in square-threaded, screw-threaded, trapezoidal-threaded, and smooth hole casings are 5, 3.7, 2.9, and 1 MPa, respectively. When the pitch in the screw-threaded casing is half of the original, the gas breakthrough pressure value of the alloy plugs in the casing is 4.7 MPa. And after the application of 0.2 MPa overlay pressure, the gas sealing performance of the alloy plugs in the screw-threaded, trapezoidal-threaded, and light hole casings was improved by 220%, 230%, and 100%, respectively. The experimental results show that when the grooves are set on the inner surface of the casing, the gas flow path per unit length of the alloy plug-casing interface is prolonged, and the grooves increase the degree of zigzagging on the inner surface of the casing. The gas sealing performance of the alloy plugs is greatly enhanced. This research can provide theoretical support for the application of downhole Carbon Storage using Sn58Bi in casing. Full article

Phase change materials (PCMs) offer promising solutions for efficient thermal management in electronic devices, energy storage systems, and renewable energy applications due to their capacity to store and release significant thermal energy during phase transitions. This study investigates the thermal and physical properties of Bi-In-Sn/WO₃ composites, specifically for their use as phase change thermal interface materials (PCM-TIMs). The Bi-In-Sn/WO₃ composite was synthesized through mechanochemical grinding, which enabled the uniform dispersion of WO₃ particles within the Bi-In-Sn alloy matrix. The addition of WO₃ particles markedly improved the composite’s thermal conductivity and transformed its physical form into a putty-like consistency, addressing leakage issues typically associated with pure Bi-In-Sn alloys. Microstructural analyses demonstrated the existence of a continuous interface between the liquid metal and WO₃ phases, with no gaps, ensuring structural stability. Thermal performance tests demonstrated that the Bi-In-Sn/WO₃ composite achieved improved thermal conductivity, and reduced volumetric latent heat, and there was a slight increase in thermal contact resistance with higher WO₃ content. These findings highlight the potential of Bi-In-Sn/WO₃ composites for utilization as advanced PCM-TIMs, offering enhanced heat dissipation, stability, and physical integrity for high-performance electronic and energy systems. Full article

With the development of electronic packaging technology toward miniaturization, integration, and high reliability, the diameter and pitch of solder joints continue to shrink. Adjacent solder joints are highly susceptible to electrochemical migration (ECM) due to the synergistic effects of high-density electric fields, water vapor, and contaminants. Dust has become one of the non-negligible causal factors in ECM studies due to air pollution. In this study, 0.2 mM/L NaCl and Na₂SO₄ solutions were used to simulate soluble salt in dust, and the failure mechanism of an Sn-58Bi solder ECM in the soluble salt in dust was analyzed by a water-droplet experimental method. It was shown that the mean failure time of the ECM of an Sn-58Bi solder in an NaCl solution (53 s) was longer than that in an Na₂SO₄ solution (32 s) due to the difference in the anodic dissolution characteristics in the two soluble salt solutions. XPS analysis revealed that the dendrites produced by the ECM process were mainly composed of Sn, SnO, and SnO₂, and there were precipitation products—Sn(OH)₂ and Na₂SO₄—attached to the dendrites. The corrosion potential in the NaCl solution (−0.351 V) was higher than that in the Na₂SO₄ solution (−0.360 V), as shown by a polarization test, indicating that the Sn-58Bi solder had better corrosion resistance in the NaCl solution. Therefore, an Sn-58Bi solder has better resistance to electrochemical migration in an NaCl solution compared to an Na₂SO₄ solution. Full article

Leveraging the liquid-phase immiscibility effect and phase diagram calculations, a sequence of alloy powders with varying Fe content was designed and fabricated utilizing the gas atomization method. Microstructural characterizations, employing SEM, EDS, and XRD analyses, revealed the successful formation of an incomplete shell on the surfaces of Al-Bi-Fe powders, obviating the need for Sn doping. This study systematically investigated the microstructure, hydrolysis performance, and hydrolysis process of these alloys in deionized water. Notably, Al-10Bi-7Fe exhibited the highest hydrogen production, reaching 961.0 NmL/g, while Al-10Bi-10Fe demonstrated the peak conversion rate at 92.99%. The hydrolysis activation energy of each Al-Bi-Fe alloy powder was calculated using the Arrhenius equation, indicating that a reduction in activation energy was achieved through Fe doping. Full article

Aimed at the problem of gas flurries in carbon dioxide (CO₂) geologic sequestration in the wellbore, this paper proposes a sealing method in which the downhole casing is processed with threaded grooves and then plugged with a low-melting-point alloy plug. Based on this method, a small-scale experimental setup was developed for alloy plug molding and gas sealing in this study. Molding and gas sealing experiments with Sn58Bi alloy plugs inside casings with different surface morphologies were carried out. The gas leakage pathway was determined. The microstructure of the interface between the alloy plug and casing was analyzed using an optical microscope. The influence of the inner surface roughness, threaded groove, length-to-diameter ratio, and ambient temperature on the gas sealing performance of the alloy plugs was analyzed. The experimental results show that, with an increase in ambient temperature, the gas sealing performance of the casing increases significantly; when the inner surface of the casing is processed through threaded grooves, the gas sealing performance is better than with smooth hole casing; the gas sealing performance of the alloy plug presents an obvious linear positive correlation with their length-to-diameter ratio. This research provides theoretical support for downhole CO₂ plugging using Sn58Bi in the casing. Full article

As electronic packaging technology advances towards miniaturization and integration, the issue of electromigration (EM) in lead-free solder joints has become a significant factor affecting solder joint reliability. In this study, a Sn-3.0Ag-0.5Cu (SAC305) alloy was used as the base, and different Bi content alloys, SAC305-xBi (x = 0, 0.5, 0.75, 1.0 wt.%), were prepared for tensile strength, hardness, and wetting tests. Copper wire was used to prepare EM test samples, which were subjected to EM tests at a current density of approximately 0.6 × 10⁴ A/cm² for varying durations. The interface microstructure of the SAC305-xBi alloys after the EM test was observed using an optical microscope. The results showed that the 0.5 wt.% Bi alloy exhibited the highest ultimate tensile strength and microhardness, improving by 33.3% and 11.8% compared to SAC305, respectively, with similar fracture strain. This alloy also displayed enhanced wettability. EM tests revealed the formation of Cu₆Sn₅ and Cu₃Sn intermetallic compounds (IMCs) at both the cathode and anode interfaces of the solder alloy. The addition of Bi inhibited the diffusion rate of Sn in Cu₆Sn₅, resulting in similar total IMC thickness at the anode interface across different Bi contents under the same test conditions. However, the total IMC thickness at the cathode interface decreased and stabilized with increasing EM time, with the SAC305-0.75Bi alloy demonstrating the best resistance to EM. Full article

This study investigates the application of the vertical zone refining process to produce ultra-high-purity tin. Computational fluid dynamics (CFD) simulations were conducted using an Sn-1 wt.%Bi binary alloy to assess the effects of two key parameters—heater temperature and pulling rate—on Bi impurity segregation. The simulations revealed a dynamic evolution in molten zone height, characterized by an initial rapid rise, followed by a gradual increase and ending with a sharp decline. Despite these fluctuations, the lower solid–liquid interface consistently remained slightly convex. After nine zone passes, impurities accumulated at the top of the sample, with dual vortices forming a rhombus- or gate-shaped negative segregation zone. The simulations demonstrated that lower heater temperatures and slower pulling rates enhanced impurity segregation efficiency. Based on these results, experiments were performed using 6N-grade tin as the starting material. Glow discharge mass spectrometry (GDMS) analysis showed that the effective partition coefficients (k_eff) for impurities such as Ag, Pb, Co, Al, Bi, Cu, Fe, and Ni were significantly less than 1, while As was slightly below but very close to 1, and Sb was above 1. Under optimal conditions—405 °C heater temperature and a pulling rate of 5 μm/s—over 60% of impurities were removed after nine zone passes, approaching 6N9-grade purity. These findings provide valuable insights into optimizing the vertical zone refining process and demonstrate its potential for achieving 7N-grade ultra-high-purity tin. Full article