In this study, Sn and Ni powders were incorporated into the flux core of brass brazing filler metals, with alloying achieved via in situ synthesis during brazing. The effects of Sn/Ni single and composite additions on the microstructure, melting characteristics, wettability on Q235 steel, and tensile strength of corresponding brazed joints were systematically investigated. Sn addition increased the β-phase fraction, reduced the solidus temperature, and significantly improved wettability—with a maximum unit spreading area of 4.22 mm<sup>2</sup>/mg at 20 wt.% Sn (2.85 times that of the Sn/Ni-free baseline). However, coarse β-phase grains and their transformation to brittle β′-phase at room temperature resulted in no enhancement of joint tensile strength. Ni addition expanded the α-phase region, refined grains, and induced solid solution strengthening of the α-phase matrix; joint tensile strength peaked at 501 MPa at 20 wt.% Ni (65% higher than the baseline). Excessive Ni (≥40 wt.%) deteriorated wettability due to reduced molten superheat, and 50 wt.% Ni caused α-phase over-strengthening and embrittlement, leading to a sharp strength drop to 214 MPa. The composite addition of 3 wt.% Sn + 10 wt.% Ni reconstructed the filler metal into a refined, uniform grid-like (α + β) dual-phase structure without new phase formation, realizing synergistic optimization of wettability and mechanical properties. The co-added sample exhibited optimal performance, with a unit spreading area of 4.51 mm<sup>2</sup>/mg and joint tensile strength of 584 MPa (206% and 93% higher than the baseline, respectively). This improvement was attributed to the coupling of uniform stress dispersion by the grid-like microstructure and dual-element functional complementation (Sn for wettability and β-phase strengthening; Ni for grain refinement and α-phase strengthening). This work provides a feasible alloying modification strategy for brass flux-cored brazing filler metals, and the revealed microstructure-performance regulation mechanism offers a valuable reference for developing high-performance brass brazing filler metals.
Surface-enhanced Raman spectroscopy (SERS) has evolved from a laboratory technique to a practical tool for ultra-sensitive detection, particularly in the biomedical field, where precise molecular identification is crucial. Despite significant advancements, a gap remains in the literature, as no comprehensive review systematically addresses the high-precision construction of SERS substrates for ultrasensitive biomedical detection. This review fills that gap by exploring recent progress in fabricating high-precision SERS substrates, emphasizing their role in enabling ultrasensitive bio-medical sensors. We carefully examine the key to these advancements is the precision engineering of substrates, including noble metals, semiconductors, carbon-based materials, and two-dimensional materials, which is essential for achieving the high sensitivity required for ultrasensitive detection. Applications in biomedical diagnostics and molecular analysis are highlighted. Finally, we address the challenges in SERS substrate preparation and outline future directions, focusing on improvement strategies, design concepts, and expanding applications for these advanced materials.
This study investigated the relationship between the process parameters on the thickness of titanium aluminide (TiAl-γ) coatings deposited using the electro-spark deposition (ESD) method on Ti6Al4V substrates. Using the design of experiments (DOE) approach and the response surface methodology (RSM), a set of experiments were designed to evaluate the effects of peak voltage, spark frequency, and electrode rotation speed on the thickness of ESD coatings. Surface morphology and cross-sectional view of coatings were analyzed using scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS). To verify the phases formed during the deposition process, X-ray diffraction (XRD) was utilized. The microhardness of the surface and the cross-sectional profile of coatings were evaluated using a Vickers tester. Electrochemical tests were applied to analyze the corrosion behavior of the sample with the maximum coating thickness, the substrate, and the electrode in a 3.5 wt% NaCl solution. A second-order polynomial equation with interaction terms was developed to describe the relationship between deposition parameters and coating thickness, demonstrating high predictive accuracy (R2 = 0.984). The maximum coating thickness of 18 μm was achieved with higher peak voltage and lower spark frequency. The average surface microhardness of the coated samples (∼600 HV) was 1.5 times higher than that of the electrode (317 HV) and the substrate (360 HV). The maximum microhardness observed within the cross-section reached ∼1400 HV, decreasing gradually with depth. Surface cracks, inherent to ESD coatings, exhibited a calculated surface density of approximately 0.017 μm−1. Corrosion tests showed that the ESD coating remarkably improved the resistance of Ti6Al4V to local corrosion in chloride-rich environments.
Investigation was conducted on the failure of the crankshaft made from 48MnV alloy steel used in automotive engines. Magnetic flaw defects were detected at the transition fillet between the third main journal and the counterweight of the crankshaft. Macroscopic examination, chemical composition analysis, metallographic analysis, and scanning electron microscopy observation were performed on the crankshaft samples. The testing results were summarized, and the causes of the crankshaft cracking were systematically analyzed. The results indicate that longitudinal cracks occurred on the surface of the crankshaft journal due to the combined effect of thermal stress and normal operating stress, exceeding its load-bearing capacity. These cracks propagated inward, forming magnetic flaw cracks, ultimately leading to crankshaft failure.
In this study, we investigated the electrochemical corrosion behavior and mechanisms of FeCrNi/WC alloys with varying contents of CTC-S (spherical WC) and CTC-A (angular WC) in a 3.5 wt.% NaCl solution, addressing the corrosion resistance requirements for stainless steel composites in marine environments. The electrochemical test results demonstrate that the corrosion resistance of the alloy initially increases with the CTC-A content, followed by a decrease, which is associated with the formation, stability, and rupture of the passivated film. Nyquist and Bode diagrams for electrochemical impedance spectroscopy confirm that the charge transfer resistance of the passivated film is the primary determinant of the composite’s corrosion performance. A modest increase in CTC-A contributes to the formation of a more heterogeneous second phase, providing a physical barrier and enhancing solid solution strengthening, and thus delaying the cracking and corrosion processes of the passivation film. However, excessive CTC-A content leads to significant dissolution of the alloy’s reinforcement phase and promotes decarburization, resulting in the formation of corrosion pits, craters, and cracks that compromise the passivation film and expose fresh alloy surfaces to further corrosion. When the CTC-A content is 10% and the CTC-S content is 30%, this combination results in minimal degradation in the corrosion performance (0.213 μA·cm<sup>2</sup>) while balancing the hardness and toughness of the alloy. Additionally, electrochemical evaluations reveal that incorporating angular CTC-A particles at 10 vol% effectively delays the breakdown of the passivation film by mitigating the interfacial galvanic coupling through enhancing the mechanical interlocking at the WC/FeCrNi interface. The CTC-A/CTC-S hybrid system exhibits a remarkable 62% reduction in the pitting propagation rate compared to composites reinforced solely with spherical WC, which is attributed to the preferential dissolution of angular WC protrusions that sacrificially suppress crack initiation at the phase boundaries.
Advancements in large language models (LLMs) have led to a surge of prompt engineering (PE) techniques that can enhance various requirements engineering (RE) tasks. However, current LLMs are often characterized by significant uncertainty and a lack of controllability. This absence of clear guidance on how to effectively prompt LLMs acts as a barrier to their trustworthy implementation in the RE field. We present the first roadmap-oriented systematic literature review of Prompt Engineering for RE (PE4RE). Following Kitchenham's and Petersen's secondary-study protocol, we searched six digital libraries, screened 867 records, and analyzed 35 primary studies. To bring order to a fragmented landscape, we propose a hybrid taxonomy that links technique-oriented patterns (e.g., few-shot, Chain-of-Thought) to task-oriented RE roles (elicitation, validation, traceability). Two research questions, with five sub-questions, map the tasks addressed, LLM families used, and prompt types adopted, and expose current limitations and research gaps. Finally, we outline a step-by-step roadmap showing how today's ad-hoc PE prototypes can evolve into reproducible, practitioner-friendly workflows.
The study focused on leaching complex copper–cobalt oxide ore from Zebesha Mine in Zambia. The chemical analysis indicated the presence of cobalt, copper, nickel, manganese and iron as base metals. Copper is predominantly found in malachite and a small portion in heterogenite mineral along with cobalt, iron, manganese and nickel. The leaching process involved using solutions containing iron: ferrous sulphate, FeSO4·7H2O; ferrous ammonium sulphate, (NH4)2Fe(SO4)2·6H2O; and ferric sulphate, Fe2(SO4)3. The effects of temperature and salt concentrations were studied alongside metal content determination through titration-atomic absorption spectroscopy techniques. It was observed that the preferential dissolution of copper occurred with Fe2 (SO4)3 while temperatures above 70°C leaching with FeSO4·7H2O resulted in the recovery of over 80% of manganese and cobalt. This study suggests that ferrous containing lixiviants can effectively promote the manganese and cobalt dissolution but are not efficient for extracting copper. Furthermore, using Fe2(SO4)3 may allow for selective leaching of copper.
Multispectral ZnS (M − ZnS) will inevitably introduce stresses during the chemical vapor deposition (CVD) polycrystalline growth and hot isostatic pressing (HIPping) stages. In this paper, the generation mechanism and elimination method of residual stresses in M − ZnS are analyzed by means of SEM, transmittance, XRD analysis and mechanical property characterization, and the effects of heat treatment temperature, time and material annealing structure on the apparent morphology, optical and mechanical properties of M − ZnS materials are investigated. The results show that the internal stresses of M − ZnS mainly originate from the CVD ZnS growth and HIPping stages, and the most effective method to reduce the stresses is heat treatment. The key factors affecting the effect of heat treatment include temperature, time, and annealing structure. Selecting a GZ(G) annealing structure combined with a suitable cooling rate for heat treatment of M − ZnS materials will significantly improve the heat treatment effect. More annealing time has a significant effect on the transmittance in the 0.38–3 μm band, and insignificant effect on the transmittance in the 3–5 μm and 8–10 μm bands. Heat treatment will bring some degree of structural changes to the material, often manifested including a trace of hexagonal phase structure, which will affect the optical imaging quality of the window material. Heat treatment contributes to secondary grain growth, with an increase in grain size and a decrease in grain boundaries. Excessive heat treatment accelerates the loss of hardness and bending strength, and also leads to the generation of micro-cracks and macro-cracks in the material, reducing the mechanical properties of the material. Heat treatment holding 200 h and 100 h compared to the unannealed, Vickers hardness decreased by 13.518 and 7.96, respectively, bending strength decreased by 4.77 MPa and 1.73 MPa, respectively. Therefore, in actual production, should not be selected excessive heat treatment time.
Controlling continuous cooling is considered an effective means of producing high-strength and high-toughness bainitic steel. A medium carbon bainite frog steel is designed. By combining a thermal dilatometer with in-situ high-temperature metallography, the influence of continuous cooling rate on the phase transformation of bainitic steel in the medium temperature range (500-365 °C) is studied. The microstructure and crystallographic orientation are characterized. The results indicate that with the increase of cooling rate in the temperature range for bainitic transformation, the initial temperature of bainitic transformation significantly decreases, and the transformation kinetics enhance, which causes the cooling rate for obtaining a maximum fraction of bainite significantly shifts to the left. As the cooling rate increases, the morphology of the bainite changes from a mixture of granular and coarse lath-like forms to fine lath-like forms. The volume fraction and average size of retained austenite as well as the size of bainite laths decrease with the increase of cooling rate. In addition, there are significant differences in the high-angle interface under different cooling rates, which is related to the variant selection mechanism of bainitic transformation at different cooling rates. The research results reveal the transformation process and microstructure evolution of bainite under different cooling rates in the medium temperature range, providing support for the microstructure control and performance optimization of bainite frog steel under continuous cooling control.
An in-situ dual morphology of Ti2AlC/TiB2 nanoparticles was refined and enhanced to fabricate Ti-47.7Al-7.1Nb-2.3V-1.1Cr composites via induction hot-pressing sintering with nano-B4C addition. The generation process of nanoparticles, lamellar refinement mechanism, and effect of nanoparticles on the microstructure evolution/mechanical properties were meticulously analysed. With 0.2 at% nano-B4C addition, Ti2AlC/TiB2 nanoparticles were uniformly distributed in the matrix following sintering. In addition, upon sintering at 1425 °C for 10 min under a pressure of 50 MPa, the lamellar colony size decreased from 280 ± 145 μm to 55 ± 16 μm, and the ultimate tensile strength (UTS) increased by 116 MPa, 142 MPa, and 176 MPa, when tested at room temperature, 800 °C, and 900 °C, respectively. The enhanced mechanical properties were attributed to the synergistic effects of grain refinement strengthening, solid solution strengthening, the Orowan mechanism, and twinning strengthening.
AbstractHaving seen significant improvements to accident rates in the last 40 years, companies in the Swedish mining industry now show a greater focus on the development of safety cultures throughout their organisations and workplaces. However, there is a lack of research examining the different safety initiatives and strategies practiced in the industry today. This study explores the potential influence and consequences such initiatives may have on the development of safety cultures in the Swedish mining industry. Twelve interviews with experts on safety initiatives from four different Swedish mining organisations were conducted and analysed in a process based on qualitative thematic analysis to identify notable connections to safety culture development. The results of these interviews highlight proclivities in the implementation and use of safety initiatives such as subjects of focus, methods and desired effects. This enables the interpretation of the conceptualisation and methods for the development of safety culture in these organisations based on their approaches to safety development. We believe the results of this study can serve as support for discussions on safety culture development in the Swedish mining industry, and be of interest for international mining industries, in addition to approaches to research in this field. However, we also believe it is important to emphasise the opportunities to approach safety culture in mining from different perspectives than those common today.
Sheila R. Ngwaku, Janine Pascoe, Wiehan A. Pelser
et al.
Several methodologies have been developed to manage diesel in open-cast mining due to its high demand and increasing diesel prices. Although the use of diesel-powered equipment in underground mines has increased over the years, effective management thereof has not received the same attention. With the advent of Industry 4.0, data can be utilised more effectively by modern businesses to identify and solve problems in a structured manner. In this study, an underground mine was used as a case study to determine whether a Data, Information, Knowledge, Wisdom (DIKW) method for diesel management could be coupled with the Six Sigma Define, Measure, Analyse, Improve, Control (DMAIC) tool to make more informed decisions and gain new insights to help reduce diesel wastage underground. The new integrated methodology identified diesel spillages and highlighted the biggest contributors to these underground spillages. The Six Sigma DMAIC domain utilised root cause analysis to determine the reason for recent systems failures, followed by the identification of practical solutions to eliminate up to 200 ML (megalitres) of diesel spillage. With this information, the case study mine stands to save over USD 175,000 per annum.
MXenes are an emerging class of new two-dimensional materials, which have been widely used in energy storage, catalysis, sensing, biology, and other fields due to their unique structure and properties. The distinct structure, low shear resistance, and easy-to-modify ability endow MXenes with particularly superior lubrication potentials. This review highlights the research status and applications of MXenes lubrication categorized into solid lubricants, lubricant additives, and reinforcement phase parts, summaries the influencing factors and lubrication mechanisms of MXenes lubrication, points out some unexplored research fields and unsettled questions, and then puts forwards possible solutions and prospects for the future research. The lubrication advances and potentials of MXenes are fully verified. Predictably, the emerging MXenes lubricants will exhibit remarkable application prospects in advanced manufacturing such as machining industries, automotive industries, micro/nano-electromechanical systems, and spacecraft components.
It is of direct and great significance for increasing the economic benefits of mining by improving the production capacity of open-pit coal mines. Based on the mining status of an open-pit coal mine in Zhundong of Xinjiang, in view of the development goal of expanding its production capacity from 20 Mt/a to 50 Mt/a, the development requirements of the mining areas in line with the 50 Mt/a production capacity well be studied, as well as the optimal mining areas division and development relationship will be determined affected by capacity increase. The technically feasible and economically reasonable working face length of the open-pit coal mine is calculated as 2300~2500 m for the capacity expansion, and according to the optimal working face length and the contour map of the stripping ratio of the whole mining areas, four reasonable mining areas division schemes are proposed. By analyzing and determining the disadvantage and advantage of various mining area division schemes, mine indicators are adopted as impact indicators for evaluating mining areas division, such as the average working face length, the secondary stripping amount, the variation trend of the stripping ratio of each mining area, the stripping ratio of the first mining area, the early external-dumping transportation distance, and the difficult degree of internal-dumping, the numbers of mining areas connection, the exploration degree of the first mining area, and the difficult degree of mining areas connection. While the set-valued iterative method is combined for calculating index weight, a comprehensive evaluation model of the mining area division scheme is developed by adopting the method of TOPSIS. The research results show that the mining area is gradually advanced to the southwest for about 4000 m with the current mining position as the first, and then advances to the east through a 90° fan-shaped turning to the east boundary, which is the second mining area, and then the remaining unexploited mining fields are divided into third and fourth mining areas arranged in parallel Area. The stripping ratios from the first mining area to the fourth mining area are 1.85 m3/t, 3.04 m3/t, 3.68 m3/t, and 5.06 m3/t, respectively. The stripping ratio gradually increases with the continuous advance of the mining area, and the stripping ratio is evenly distributed in the four mining areas. In addition, the mining area division scheme can achieve small secondary stripping volume and early discharge distance, less connection times, high exploration degree in the first mining area and uniform working line length in each mining area under the condition of meeting the production capacity of 50 Mt/a, and has the minimum impact on the overall development of the mine and the economy.
Cloud compute adoption has been growing since its inception in the early 2000's with estimates that the size of this market in terms of worldwide spend will increase from \$700 billion in 2021 to \$1.3 trillion in 2025. While there is a significant research activity in many areas of cloud computing technologies, we see little attention being paid to advancing software engineering practices needed to support the current and next generation of cloud native applications. By cloud native, we mean software that is designed and built specifically for deployment to a modern cloud platform. This paper frames the landscape of Cloud Native Software Engineering from a practitioners standpoint, and identifies several software engineering research opportunities that should be investigated. We cover specific engineering challenges associated with software architectures commonly used in cloud applications along with incremental challenges that are expected with emerging IoT/Edge computing use cases.
Jocelyn Ahmed Mazari, Antoine Reverberi, Pierre Yser
et al.
In this work, we propose a built-in Deep Learning Physics Optimization (DLPO) framework to set up a shape optimization study of the Duisburg Test Case (DTC) container vessel. We present two different applications: (1) sensitivity analysis to detect the most promising generic basis hull shapes, and (2) multi-objective optimization to quantify the trade-off between optimal hull forms. DLPO framework allows for the evaluation of design iterations automatically in an end-to-end manner. We achieved these results by coupling Extrality's Deep Learning Physics (DLP) model to a CAD engine and an optimizer. Our proposed DLP model is trained on full 3D volume data coming from RANS simulations, and it can provide accurate and high-quality 3D flow predictions in real-time, which makes it a good evaluator to perform optimization of new container vessel designs w.r.t the hydrodynamic efficiency. In particular, it is able to recover the forces acting on the vessel by integration on the hull surface with a mean relative error of 3.84\% \pm 2.179\% on the total resistance. Each iteration takes only 20 seconds, thus leading to a drastic saving of time and engineering efforts, while delivering valuable insight into the performance of the vessel, including RANS-like detailed flow information. We conclude that DLPO framework is a promising tool to accelerate the ship design process and lead to more efficient ships with better hydrodynamic performance.