Metal Processing Research Articles

Digital Etching of Molybdenum Interconnects Using Plasma Oxidation

AbstractMolybdenum (Mo) has a high potential of becoming the material of choice for sub‐10 nm scale metal structures in future integrated circuits (ICs). Manufacturing at this scale requires exceptional precision and consistency, so many metal processing techniques must be reconsidered. In particular, present direct wet chemical etching methods produce anisotropic etching profiles with significant surface roughness, which can be detrimental to device performance. Here, it is shown that polycrystalline Mo nanowires can be etched uniformly using a cyclic two‐step “digital” method: the metal surface is first oxidized with isotropic oxygen plasma to form a layer of MoO3, which is then selectively removed using either wet chemical or dry isotropic plasma etching. These two steps are repeated in cycles until the intended metal recess is achieved. High uniformity of plasma oxidation defines the etching uniformity, and small metal recess per cycle (typically 1–2 nm) provides precise control over the etching depth. This method can replace wet etching where high etching precision is needed, enabling the reliable manufacturing of nanoscale metal interconnects.

Fractal Analysis of Mining Wastewater Time Series Parameters: Balkhash Urban Region and Sayak Ore District

The population life and health quality are significantly reduced due to water resources pollution caused by heavy metals, especially in urban agglomerations located close to metal ore mining and processing facilities. The greatest environmental pollution occurs during the extraction of Cu, Zn, and Pb. In this study, a fractal R/S analysis of wastewater discharge indicators time series from a metal ore mining facility located in the Sayak ore district in the Republic of Kazakhstan (turbidity, electrical conductivity, flow magnitude, and pH level) was carried out. A sharp increase in the flow rate was recorded from 10 to 15 July 2024 and an increase in the electrical conductivity from 4 to 26 July 2024. However, the latest type of indicator assessment does not exceed the critical level for life. The presence of electrical conductivity indicators time series long-term memory and persistence was also recorded (the Hurst exponent for the electrical conductivity time series is fixed in the 0.56 to 0.59 range and does not go below the threshold value for randomness according to the Anis-Lloyd formula). Thus, the value-changing process is controlled and stable, and minor changes in turbidity indicate that these releases do not significantly harm the environment. Despite this, the results obtained do not allow for a comprehensive analysis of the state of releases as the data from all deposits is not available. Therefore, due to the time constraints of the data provided for analysis, it is difficult to fully assess the impact of specific metal ore mining facilities on the environmental safety of the Balkhash urban region. In addition, many studies indicate very high risks of chronic diseases for the population living in this region. The findings of this study enable us to conclude that the application of fractal analysis and the calculation of fractal characteristics for time series of emissions can serve as an indicator of the environmental status within the given area. This information can be used by environmental services to build reliable environmental pollution monitoring systems.

The Effect of Cooling Rate on Solidification Characteristics and Grain Structure of Al-9Si Cast Alloy

A thermal analysis study is essential before the semisolid metal processing of a particular alloy. The surrounding environment, especially the cooling rate is also an important factor. This study investigated the influence of different cooling rates on the solidification characteristics and microstructure evolution of the Al-9Si cast alloy. Four cooling mediums were designed, and their cooling rates are 0.16 ℃/s, 1.0 ℃/s, 1.3 ℃/s, and 1.9 ℃/s, respectively. The results show that the primary dendrite size of the Al-9Si alloy was reduced from 162.61 μm to 86.86 μm as the cooling rate increased from 0.16 ℃/s to 1.9 ℃/s. Significant grain refinement was observed, however, the external cooling has a negligible impact on solid fraction. The optimal temperature range of the Al-9Si cast alloy for the semisolid metal processing at a solid fraction of 0.5 to 0.7 is between 554 ℃ and 563 ℃. With these thermal profiles provided, the relationship between the solid fraction and the solidification time could be expressed using the polynomial equation, which is also useful for point prediction in the subsequent semisolid metal processing.

Identification and Evaluation of Synergy Between Carbon Emissions and Air Pollutants in Inter-Industrial Trade Among Provinces in China

With the vigorous promotion in China of efforts to reduce pollution and carbon emissions, examining their synergies becomes increasingly crucial. This study used the multi-regional input–output (MRIO) table to build the consumption-based industrial emissions inventories of CO2 and three major air pollutants (PM2.5, NOx, and SO2) and constructed synergistic emission indices of the intensity and magnitude to identify and evaluate the synergy between carbon emissions and air pollutants in inter-industrial trade among 30 provinces in mainland China. The results show that more than 85% and 40% of inter-provincial and inter-industrial trades have synergistic emissions between CO2 and air pollutants, respectively. We identified 77 inter-provincial trades and 84 inter-industrial trades among provinces with strong synergistic emissions. They are mainly reflected in the demand of the construction industry in Zhejiang and Guangdong for the nonmetal mineral products manufacturing industry in Henan, and the metal smelting and processing industry in Hebei, along with the demand of the service industry in Beijing for the electric power, steam, and hot water production and supply industry in Inner Mongolia. Our study provides new insights into the synergistic reduction of CO2 and air pollutants within the supply chain, thereby enriching the discourse on regional and industrial synergies in achieving sustainable development goals.

Central-Eastern Europe as a centre of Middle Ages extractive metallurgy

Central-eastern to southeastern Europe, from Bohemia to Greece is home to some of the richest ore deposits on earth, with archaeological evidence suggesting a long history of metal use. However, the exact timing and extent of past metal processing activities remains unclear. The Middle Ages and Early Modern period (c. 500–1800 common era (CE)) in Europe, saw the expansion of metal use at an unprecedented scale, continent-wide. Here we analysed rates of past atmospheric lead (Pb) deposition in six peat bogs from Romania, Serbia and Greece. We show that after 1000 CE, the redevelopment of central European mining industry was synchronous with Pb pollution in southeastern Europe, with the onset of metal pollution occurring in the area prior to central Europe. Therefore, southeastern Europe may have led regional mining developments, with technological advances rapidly shifting from east to west through the Middle Ages. This indicates how southeastern Europe should be included in future discussions of Middle Age metallurgy not simply as a contributor, but at times as a leader in metal production.

Spectral and optic-metric methods of monitoring parameters of plasma channels caused by discharge currents between metals granules in working liquids

Introduction. Spark-erosion processing of metals and alloys granules in working liquids is the basis of a several technological processes. Efficiency of energy use in them and parameters of the resulting product largely depend on the accuracy of stabilization and regulation of pulse power in each plasma channel between the granules. To achieve this, until now only the voltage and current of the discharge pulses in the entire layer of granules have been controlled. Problem. The measurement methods, which are used, are not effective enough for monitoring the parameters of individual plasma channels and predicting the size distribution of eroded metals particles at the stage of their formation. The aim of the work is to develop a method for determining the volumes of components of plasma channels in layers of metals granules during their spark-erosion treatment to predict the size distribution of eroded metal particles at the stage of their formation, as well as to simplify the method of spectrometric analysis of the elemental composition of substances surrounding plasma channels for the operational prediction of the chemical composition of resulting products. Methodology. A series of experiments were carried out on spark-erosion processing of Al and Ag granules layers in distilled water. Using a digital camera, images of the plasma channels in them were obtained. Based on the theory of pulsed electrical breakdown of liquid dielectrics, an analysis of the components of plasma channels was carried out. Using the specialized ToupView program, the volumes of equivalent ellipsoids of rotation were determined, approximating the halos of colored radiation likely arising from streamers, as well as the spark cores of plasma channels emitting white light. The shades of the resulting radiation were studied for several metals and working liquids. The obtained data were compared with the known results of spectrometric studies for the same elements excited by similar mechanisms. Results. The theory of discharge-pulse systems for spark-erosion processing of granular conductive media has been developed in the direction of new methods for monitoring the parameters of discharge pulses and predicting the chemical composition and size distribution parameters of eroded metal particles at the stage of their production. An optic-metric method has been developed for determining the volumes of halos and cores of plasma channels. A simplified spectral method for determining the chemical composition of erosion particles based on the shade of the resulting radiation was proposed. Originality. The developed new optic-metric method makes it possible to obtain information about almost every plasma channel, which refines predictions of the size distribution of erosion particles. To implement the method, general-purpose hardware and specialized software that is freely available are used. The developed method of simplified spectral analysis of excited atoms makes it possible to make preliminary predictions of the chemical composition of the obtained erosion particles already at the stage of their formation without the use of expensive specialized equipment. Practical significance. The ratio of the volumes of halos and cores of plasma channels between Al and Ag granules in distilled water was measured. An analysis of the emission spectra of plasma channel halos between Al, Ag and Cu granules in distilled water, Fe in ethyl alcohol, Ni-Mn-Ga and Ti-Zr-Ni alloys in liquid nitrogen, and Ti-Zr-Ni in liquid argon was carried out. Based on spectrometry data, the resulting shades of these radiations were substantiated and their description in the RGB system is given. References 56, table 1, figures 4.

Temperature measurement in laser–metal processing using optical sensing: Radiometric calibration and validation of a multispectral camera

In laser–metal processing such as Laser-based Powder Bed Fusion of Metals (PBF-LB/M), the quality of the final product is significantly influenced by the thermal behaviour of the melt pool. Accurate temperature measurements are challenging due to high temperature gradients and rapid cooling. This study introduces Multispectral Imaging (MSI) as a highly effective thermometry technique to address these demanding conditions. MSI captures multiple bands of radiation, enabling the simultaneous determination of absolute temperature and surface emissivity. This capability is crucial for ensuring high-quality outcomes in laser–metal processing such as PBF-LB/M, contingent upon robust radiometric calibration.To enhance reliability, two radiometric calibration models were developed: an empirical model based on linear sensor data correlations and an analytical model leveraging sensor behaviour. An efficient calibration was found for both models across a range of signal-to-noise ratios in the black body calibrator, where the analytical model even performs robust under a high noise level.Additionally, the temperature accuracy in the solid-state case was tested with a thermo-mechanical simulator. Results showed that the empirical and analytical models achieved mean relative errors of 2.0% and 1.6%, respectively, outperforming the state-of-the-art. Further, laser irradiation experiments highlighted the analytical model’s ability to accurately determine the emissivity decrease during the solid-to-liquid transition, allowing for accurate melt pool temperature estimations. Conversely, the empirical model struggled to estimate temperature effectively in the liquid phase.This study not only proposed a robust methodology of MSI in temperature measurement but also confirmed the accuracy and reliability of the system, broadening the scope for further investigation into the intricate thermal dynamics involved in laser–metal interactions.

Analysis of noise characteristics of metal processing equipment

The management and prevention of industrial injuries among workers are crucial in the work environment. Industrial injuries occur in various forms and have diverse causes, and noise-induced hearing loss accounts for a significant proportion of workplace injuries. Therefore, this study aimed to measure the factory noise during engine-component (metal) processing for automobiles, where substantial noise-induced hearing loss is prevalent. The measurement results revealed that the 24-h equivalent continuous noise level (Leq) was approximately 83.8 dB(A), and the noise at two points was higher than the noise exposure standard of 89 dB(A). These points were identified as locations where 2,200- to 3,500-ton casting machines were positioned on both sides to melt iron to produce components. The noise generated from each machine is assumed to have combined at these points, resulting in elevated noise levels. The results were plotted on a noise rating (NR) curve. The NR values ranged from 81 to 83, surpassing the standard NR range of 60 to 70 that is commonly used in typical workplaces. The frequency band that determined the NR was 2 kHz. Therefore, measures such as the use of porous sound-absorbing materials should be considered to attenuate the frequency range based on the noise characteristics.

Multi-Response Optimization of Single Point Incremental Forming of Al 6061 Sheet Through Grey-Based Response Surface Methodology

The single point incremental forming process (SPIF) is materialized to form the desired shapes in low-cost sheet metal processing and well suited for low batch components and customized designs. Many modifications have been attempted in recent years to maximize the formability, geometric accuracy and quality of the SPIF formed parts. In this work, an attempt has been made to analyse the influence of process parameters namely ball tool diameter, step size, spindle speed and sheet thickness on final wall thickness, forming force and surface roughness. The optimized results exhibit the desirable formability when the roller ball tool diameter of the tool is 12 mm. The results also project that formability of the sheet metal is minimized when the spindle speed is increased and the ball diameter maximizes the accuracy and surface roughness. Also minimizing the step size increases the product quality features. Upon conducting this multi-response optimization by grey based response surface methodology (RSM) technique It is identified that 12 mm ball diameter of the tool, 0.25 mm step size, 2445 rpm spindle speed, and 2 mm sheet thickness are the obtained optimized SPIF process parameters as confirmed through confirmation experiments.

Preface: 13th Ranshofener Leichtmetalltage

Abstract What strategies are available to minimize resource consumption in the light metal industry through recycling and energy efficiency? How can lightweight design make mobility more sustainable? And what role will artificial intelligence play in future processes in the metal processing industry? These and other questions are addressed at the 13th Ranshofener Leichtmetalltage 2024, which take place on the 26th–27th of September 2024 at the Hotel Gut Brandlhof in Saalfelden, Austria, and are organized in accordance with the criteria of the Austrian Ecolabel for Green Events. Under the guiding theme of “Light Metals Innovations for Environmental and Economic Sustainability”, this year’s conference offers an exciting program in three sessions “Digitalization in the Context of Circularity”, “Sustainable Process Development” and “Innovative Light Metals and their Characterization”. The focus is on decarbonization and digitalization in process and material development as well as the material characterization of light metals. A balanced spectrum of international presentations from universities, RTOs and industry provides participants with an up-to-date overview of the latest scientific findings and successful light metal applications. The 13th Ranshofener Leichtmetalltage 2024 are thus clearly focused on decarbonization and digitalization – even in times of diverse challenges. The first session, “Digitalization in the Context of Circularity”, highlights best-practice examples from the aluminium industry, the balance between sustainability and performance in metal processing and the implementation of complex geometries using wire-based additive manufacturing. The second session, “Sustainable Process Development”, is dedicated to the decarbonization and reduced material consumption of industrial processes, for example through GigaCasting, or the use of innovative recycling technologies. The third session, “Innovative Light Metals and their Characterization”, addresses forward-looking topics such as the development of special aluminium alloys for additive manufacturing, the use of old car scrap for innovative alloys and the decarbonization of the magnesium industry. The conference proceedings contain scientific contributions to the conference. We would like to thank all the authors for their high-quality work and the participants of the 13th Ranshofener Leichtmetalltage 2024 for their interest. We wish you stimulating reading and creative impulses! List of Scientific committee, Organizing committee are available in this Pdf.

Technological Methods and Equipment for Plasma-Electrolytic Processing of Metals and Alloys

The proposed review presents the results of the analysis of the equipment and technological methods for implementing the plasma electrolytic chemical-thermal treatment and plasma electrolytic polishing. A group of methods based on the immersion of workpieces in an electrolyzer was considered, as well as a method of a local treatment by the jet feed of an electrolyte to the area of the surface being treated. The influence of the design and characteristics of the electrolyzer, the power source and the system for feeding the work-piece into the electrolyte on the specifics of plasma electrolytic treatment methods is shown. Technological methods improving the quality and productivity of treatment are considered. Limitations in the applicability of the existing equipment were revealed, and the prospects for the improvement in the field of development of equipment and technologies for plasma electrolytic treatment were determined.

USE OF ELECTRIC ARC METALLIZATION TO PROTECT METAL SURFACES FROM CORROSION: A STUDY ON THE EXAMPLE OF STEEL 45 AND 30HGSA WIRE

The effect of protective coating applied to steel 45 made of 30HGSA wire by electric arc metallization on corrosion resistance compared to untreated steel 45 was investigated. The test methodology included electrochemical analyses such as polarization curves. The results showed that steel 45 coated with 30HGSA wire shows significantly higher corrosion resistance compared to standard steel 45.The result of this study confirms the significance of electric arc metallization technology as an effective way to improve the corrosion resistance of steels. The application of protective coating of 30HGSA wire on steel 45 not only improves its characteristics, but also provides opportunities for more durable use in aggressive environments. Also, these methods can be adapted for other types of materials, which opens new perspectives in the field of steel structures protection. This research can serve as a basis for the development of new norms and standards in metal fabrication and processing. These results provide valuable scientific data that can contribute to the development of improved corrosion resistant materials for applications in critical industries such as oil and gas, marine and construction projects, and mechanical engineering, where material reliability is a key factor.

Advancements in Metal Processing Additive Technologies: Selective Laser Melting (SLM)

Nowadays, the use of metal processing additive technologies is a rapidly growing field in the manufacturing industry. These technologies, such as metal 3D printing (also known as additive manufacturing) and laser cladding, allow for the production of complex geometries and intricate designs that would be impossible with traditional manufacturing methods. They also offer the ability to create parts with customized properties, such as improved strength, wear resistance, and corrosion resistance. In other words, these technologies have the potential to revolutionize the way we design and produce products, reducing costs and increasing efficiency to improve product quality and functionality. One of the significant advantages of these metal processing additive technologies is a reduction in waste and environmental impact. However, there are also some challenges associated with these technologies. One of the main challenges is the cost of equipment and materials, which can be prohibitively expensive for small businesses and individuals. Additionally, the quality of parts produced with these technologies can be affected by factors such as printing speed, temperature, and post-processing methods. This review article aims to contribute to a deep understanding of the processing, properties, and applications of ferrous and non-ferrous alloys in the context of SLM to assist readers in obtaining high-quality AM components. Simultaneously, it emphasizes the importance of further research, optimization, and cost-effective approaches to promote the broader adoption of SLM technology in the industry.

A Review of Viscosity Measurement Techniques for Semi-Solid Metal Fluids in Thixoforming Processes

This paper critically reviews two viscometry techniques: capillary viscometers and parallel plate compression (PPC) viscometers, which are used in the viscosity measurement of semi-solid metal (SSM) fluids for thixo routes. Capillary and PPC viscometers have emerged as valuable viscometers in the study of thixo routes of SSM, with insights into their unique flow behavior being explored. Thixoprocessing of SSM is particularly suitable for specific alloys, especially those with specific solidification properties such as eutectics. It is a method of thixoforming that uses a material's non-dendritic microstructure. The thixo method's viscosity measurement is challenging, requiring sample preparation, sophisticated equipment, precise temperature, and pressure control. Previous studies have lacked sufficient information on measurement methods, viscometers, and limitations to measuring viscosity for the thixo route of SSM. Hence, this study thoroughly examines the principles, advantages, limitations, and application areas of viscometry methods. Several factors influencing viscosity measurements, such as temperature, shear rate, and sample preparation, are discussed in detail. A comparative analysis is conducted to evaluate the performance and accuracy of capillary viscometers and parallel plate compression viscometers. This review will provide a comprehensive understanding of SSM's viscometry techniques and assist researchers and practitioners in selecting the most appropriate method for their specific applications in semi-solid metal processing and characterization.

Calibration Method of Measuring Heads for Testing Residual Stresses in Sheet Metal Using the Barkhausen Method.

Among non-destructive testing methods, a group dedicated to the assessment of the state of residual stresses can be distinguished. The method of measuring residual stresses using the Barkhausen noise method has many advantages, as evidenced by the number of publications. The residual stresses in metal products are important for the further processing of such metal, such as laser cutting or bending. The results presented in this work are of an experimental nature, and the presented method of calibration of measuring heads shows how various research techniques can be used to correlate results. The research was carried out for structural steel due to the market share of this type of steel. The method can be used to measure the residual stresses in ferromagnetic metal products in order to assess their directions and quantify them. A prerequisite for the use of this measurement method is that the amplitude and geometry of the Barkhausen noise are adequately correlated to the specific values of the state of stress depending on the tested steel grade or other metals. In this study, a method for calibrating measuring sensors for the residual stress measurements is presented, as developed by the authors. The method involved conducting bending tests in both numerical modeling and experimental tests. During the bending tests, changes in the magnetic field (Barkhausen noise waveform) were recorded, taking into account the state of elastic stresses. Correlating the results of the numerical calculations and Barkhausen noise measurements made it possible to determine the quantitative values of the residual stresses in the steel sheets. Thanks to the method used, very accurate measurement is possible, and the obtained results are repeatable.

Cross-scale characteristics and emission reduction pathways of trade-embodied carbon flows in the global supply Chains

In the context of the 1.5 °C warming target, there is a growing awareness of the increasingly frequent carbon flows between subregions. However, understanding the characteristics and pathways of cross-scale carbon flows between subregions and regions remains elusive and impedes achieving emission reduction targets. This study employs a nested multi-regional input–output model and the structural path analysis method, establishing the characteristics of the carbon emission transfer network within global supply chains and discerning the crucial structural pathways and nodes for carbon emissions. The study found that (1) in 36 major countries, the embodied carbon flows are predominantly influenced by the developed countries around China in Asia and the Pacific. (2) In 30 subregions, coastal subregions with large-scale foreign trade and energy-intensive subregions in China's central and western parts contribute significantly to the larger embodied carbon outflow due to exports. (3) “Manufacture of non-metallic mineral products (S09) → construction (S19)” and “manufacture and processing of metals (S10) → construction (S19)” are the two key pathways of paramount significance of embodied carbon emissions. (4) “R25 South Korea” has the highest number of key pathways and the greatest embodied carbon emissions from critical paths, followed by “R27 India” and “R22 United States.” These findings offer valuable insights for the development of regional emission reduction policies.

Mineralogical Insights into PGM Recovery from Middle Group (1–4) Chromite Tailings

Variations in the recovery of platinum group metals (PGMs) are often attributed to mineralogical and other natural ore-type variations. To increase the recovery of PGMs by the flotation process, a comprehensive understanding of gangue and valuable minerals is essential for optimising the extraction and processing of metals. Recoveries may be improved if the questions of how, where, and why losses occur can be answered with a certain degree of confidence. A requirement is the availability of statistically reliable mineralogical data. The PGMs of MG-1–4 chromite tailings dumps of the western limb of the Bushveld complex (BC) were studied in detail to unravel the PGMs and the nature of the platinum group minerals in the sample. Characterisation of the chromite tailings via deportment analysis revealed that the sample contained a significant amount of 3E PGM + Au (Pt, Pd, Ru, and Au) and was concentrated in the -25 µm fraction. The results of automated mineralogical analysis showed that the sample was composed of the PGE-sulphides group, comprising 63.6 vol%, PGE-sulfarsenides 10.4 vol%, PGE-arsenides 1.3 vol%, PGE-bismuth tellurides 3.3 vol%, PGMs-alloy 4.1 vol%, and Laurite comprising 17.3 vol% of the total PGE population. The sample was composed of 66.5 vol% of liberated PGMs, 0.2 vol% attached to liberated BMS, 27.3 vol% of PGMs attached to or locked within silicate or oxide gangue composite particles, 0.2 vol% of PGMs associated with BMS attached to silicate or oxide gangue particles, and a low proportion (5.8 vol%) of PGMs reported being locked within gangue or oxide particles. The majority of PGM grains observed were reported in the fast-floating category (64.4 vol%), 27.6 vol% in the slow-floating 1 category, 2.2 vol% in the slow-floating 2 category, and 5.8 vol% to the non-floating category. The results of the study revealed that the PGMs of MG 1–4 chromite tailings were liberated; however, the low liberation index (<0.2) suggested that a significant portion of PGMs remained trapped within gangue, hindering their recovery. This highlights the need for effective comminution (crushing and grinding) to achieve better liberation. The sample contained fine particles that were more prone to being lost in the tailings and to lowering recovery due to the slimes coating valuable minerals. The recovery of the PGMs from this complex’s polymetallic bodies of low-grade and complex mineralogy will be insufficient with traditional methods and thus innovation is needed. Innovation like advanced comminution, novel flotation equipment or reagents, selective leaching and bioprocessing can overcome these challenges.

Optimization of Laser Cladding Parameters for High-Entropy Alloy-Reinforced 316L Stainless-Steel via Grey Relational Analysis

Laser cladding technology serves as a pivotal technique in industrial production, especially in the realms of additive manufacturing, surface enhancement, coating preparation, and the repair of part surfaces. This study investigates the influence of metal powder composition and processing parameters on laser cladding coatings utilizing the Taguchi orthogonal experimental design method. To optimize the laser cladding parameters, multi-response grey relational analysis (GRA) was employed, aiming to improve both the microhardness and the overall quality of the coatings. The optimal parameter combinations identified through GRA were subsequently validated through experimental tests. The results reveal that the microhardness and quality of the coatings are substantially influenced by several critical factors, including the powder feed rate, laser power, high-entropy alloy (HEA) addition rate, scanning speed, and substrate tilt angle. Specifically, the powder feed rate exerts the most significant effect on the microhardness, dilution rate, and average contact angle. In contrast, laser power primarily impacts the mean contact angle difference. The HEA addition rate notably affects the mean contact angle difference, while the scanning speed affects the microhardness and the substrate tilt angle influences the average contact angle. The results of the validation experiment showed a deviation of only 0.95% from the predicted values, underscoring the efficacy of the grey relational analysis (GRA) in optimizing the laser cladding process parameters. The methodology presented in this paper can be applied to determine the ideal processing parameters for multi-response laser cladding processes, encompassing applications such as surface peening and surface repair.

Biogenic Nanoparticles at the Forefront: Transforming Industrial Wastewater Treatment with TiO2 and Graphene

This review article comprehensively examines the potential of biosynthesized TiO2 and graphene nanoparticles in industrial wastewater treatment, highlighting their effectiveness, environmental benefits, and challenges. The review focuses on green synthesis methods, which enhance sustainability and reduce the toxicity of these nanoparticles while maintaining their high efficiency in degrading organic pollutants and adsorbing heavy metals across various industrial applications, including textile, pharmaceutical, chemical, and metal processing. The discussion also covers environmental and safety considerations, such as the toxicity of nanoparticles and the importance of recycling and reuse strategies to minimise their ecological impact. Additionally, the article addresses regulatory and ethical issues, emphasizing the need for robust frameworks to ensure the responsible use of nanotechnology. Future research directions are suggested, including improving biosynthesis methods and scaling up applications for broader industrial use. This review underscores the significant potential of biosynthesised TiO2 and graphene nanoparticles as sustainable and powerful tools for global environmental remediation.

Revealing the Protective Dynamics of an Ecologically Engineered Wetland against Acid Mine Drainage: A Case Study in South Africa

This study investigated the Zaalklapspruit valley bottom wetland in South Africa, an ecologically engineered site influenced by acid mine drainage (AMD) from a defunct coal mine upstream. Conducted in 2022, the research aimed to elucidate the dynamics of contaminant dispersal within this wetland, focusing on the sources, pathways, and receptors of metals and sulfur compounds. The analysis revealed that the wetland’s bottom sediment is rich in organic material, with pH values ranging from 6.05 to 6.59 and low oxidation-reduction potentials reaching −219.67 mV at Site S3. The significant findings included the highest adsorption rates of manganese, contrasted with iron, which was primarily absorbed by the roots of Typha capensis and the algae Klebsormidium acidophilum. The macrophyte rhizospheres were found to host diverse microbiota, including families such as Helicobacteraceae and Hydrogenophilaceae, pivotal in metal and sulfur processing. This study highlighted the complex biogeochemical interactions involving sediment, macrophyte root systems, periphyton, and microbial populations. These interactions demonstrate the efficacy of ecologically engineered wetlands in mitigating the impacts of acid mine drainage, underscoring their potential for environmental remediation. Importantly, the sustainability of such interventions highlights the need for community involvement and acceptance, acknowledging that local support is essential for the long-term success of ecological engineering solutions that address environmental challenges like AMD.