Search Results (1,385)

Tungsten–diamond metal matrix composites (MMCs) fabricated via L-PBF show potential for applications in nuclear facility shielding, heat sinks, precision cutting/grinding tools, and aerospace hot-end components. In this paper, tungsten (W), diamond (D), and diamond with Ni coating (D-Ni) powders are used to fabricate W+D and W+(D-Ni) composites by L-PBF technology. The results show that at the interface of the W+D sample, the W powder melts while the D powder remains in a solid state during L-PBF processing, and W and C elements gradually diffuse into each other. Due to the high cooling rate of L-PBF processing, the C phase forms a diamond-like carbon (DLC) phase with an amorphous structure, and the W phase becomes a supersaturated solid solution of the C element. At the interface of the W+(D-Ni) sample, the diffusion capacity of Ni and W elements in the solid state is weaker than in the molten state. C and W elements diffuse into the Ni melt, forming a rich Ni area of the DLC phase, while Ni and W elements diffuse into the solid D powder, forming a lean Ni area of the DLC phase. In the rich Ni area of the DLC phase, Ni segregation leads to the precipitation of nanocrystals (several hundred nanometers), whereas in the lean Ni area of the DLC phase, the diffusion capacity of Ni and W elements in the solid D powder is limited, resulting in nanocrystalline sizes of only about tens of nanometers. During W dendrite growth, the addition of the Ni coating and the expelling of the C phenomenon leads to W grain refinement at the interface, which reduces the number and length of cracks in the W+(D-Ni) sample. This paper contributes to the theoretical development and engineering applications of tungsten–diamond MMCs fabricated by L-PBF. Full article

The miniaturization of smart materials has become a new trend in the modern manufacturing industry due to its enormous application in the aerospace, biomedical, and automobile sectors. Nickel–titanium (NiTi)-based binary shape memory alloys (SMAs) are one of the smart materials with certain supreme features like shape memory effect, pseudo-elasticity, high ductility, strong corrosion-resistance, and elevated wear resistance. For this, several micro-machining processes have been developed to machine NiTi SMAs. This paper summarizes all of the conventional and non-conventional micro-machining processes employed to machine NiTi SMAs. In this review process, the surface integrity, dimensional accuracy of the machined surface, cutting force and tool wear analysis during conventional and non-conventional micro-machining of NiTi SMA are evaluated mostly with the aid of input process variables like cutting speed, depth of cut, width of cut, types of coolants, tool coating, discharge voltage, capacitance, laser fluence, pulse duration, scan speed, electrolysis concentration and gap voltage. The optimization of process parameters using different methods during conventional and non-conventional micro-machining of NiTi SMAs is also analyzed. The problems faced during conventional micro-machining of NiTi SMAs are overcome by non-conventional micro-machining processes as discussed. The present study aims to recognize potential developments in the improvement of the micro-machinability of NiTi SMAs. Full article

To achieve efficient preparation of microfine tool electrodes with a large aspect ratio, a bipolar pulse vertical liquid membrane electrochemical etching technique was proposed. The difference in current density distribution on the surface of tungsten rods under single-ended and double-ended vertical liquid membrane methods was analyzed using COMSOL software. The effects of negative voltage and pulse width on the distribution of electrolytic products and electrode preparation were investigated. It was found that when a large number of hydrogen bubbles were generated on the surface of the electrode, the electrode lost the protection of the diffusion layer, and the length was drastically shortened. When the pulse width was large, the electrode surface was covered with a coating layer of insoluble electrolysis product, and the shortening of electrode length was suppressed. Subsequently, the effects of forward voltage and bias on electrode preparation were investigated for large pulse widths. The optimal parameters are as follows: electrolyte concentration of 0.5 M, forward voltage of 4 V, negative voltage of −2 V, pulse period of 50 microseconds, and pulse width of 40 microseconds. Finally, the tool electrode with an average diameter of about 23.8 μm and an aspect ratio of 91.2 was prepared. Full article

The selection of mining cutting tools used on the cutting heads of roadheaders and shearers in hard coal mines is primarily based on the uniaxial compressive strength (UCS) of the rock. However, selecting cutting tools solely on the basis of a single parameter characterizing the rock has proven to be insufficient. Therefore, the aim of the presented study was to develop guidelines for the selection of cutting tools with appropriate protective coatings on the working parts, based not only on the mechanical strength properties of rocks, but also on their abrasivity. For the study, twelve rock samples were collected from five different Polish hard coal mines. For each rock type, the UCS (uniaxial compressive strength), BTS (Brazilian tensile strength), and chemical composition (determined using wavelength-dispersive X-ray fluorescence, WD-XRF) were measured, along with the rock abrasivity index Wz, determined using a proprietary method developed at the AGH University of Krakow. The test results were compared with the calculated specific pick wear, defined as the number of picks consumed (replaced) per 1000 m³ of excavated material. As a result, a classification of rocks based on their UCS and abrasivity was developed, along with recommendations for selecting conical picks with suitable protective coatings on the working parts. Full article

This paper presents a comprehensive analysis of recent advancements in the application of thermal spraying techniques to enhance the durability and wear resistance of agricultural machinery components, with a particular focus on disc harrow assemblies. Given the harsh conditions under which tillage tools operate—characterized by abrasive wear, impact stresses, and chemical exposure from various soil types—thermal sprayed coatings have emerged as a viable solution to extend the service life of these components. The study discusses various deposition methods, particularly Atmospheric Plasma Spraying (APS), and evaluates their effectiveness in creating high-performance surface layers that resist wear, corrosion, and mechanical degradation. The review also summarizes experimental and field test results for coatings based on materials such as NiCrBSi, WC-Co-Cr, TiO₂, Al₂O₃, Cr₂O_3, and ceramic–metal composites, highlighting their significant improvements in hardness, friction reduction, and resistance to delamination and oxidation. The paper highlights research using thermal spraying techniques, especially APS for agricultural applications, with emphasis mostly on components intended for soil processing and requiring good resistance to abrasive wear. Full article

Inconel 617 is a nickel-based superalloy that is a primary candidate for use in next-generation nuclear applications such as the Gen IV Molten Salt Reactor (MSR) and Very-High-Temperature Reactor (VHTR) due to its corrosion and oxidation resistance and high strength in elevated temperatures. However, Inconel 617 machinability is poor due to its hardness and tendency to work harden during manufacturing. While the machinability of its sister grade, Inconel 718, has been widely studied and understood due to its applications in aerospace, there is a lack of knowledge regarding the behaviour of Inconel 617 in machining. To address this gap, this paper investigates the influence of cutting parameters in the turning of Inconel 617 and compares the impact of Minimum Quantity Lubrication (MQL) turning against conventional coolant. This investigation was performed through three distinct studies: Study A compared the performance of commercial coatings, Study B investigated the influence of cutting parameters on the surface finish, and Study C compared the performance of MQL to flood coolant. This work demonstrated that AlTiN coatings performed the best and doubled the tool life of a standard tungsten carbide insert compared to its uncoated form. Additionally, the feed rate had the largest impact on the surface roughness, especially at high feeds, with the best surface quality found at the lowest feed rate of 0.075 mm/rev. The utilization of MQL had mixed results compared to a conventional flood coolant in the machining of Inconel 617. Surface finish was improved as high as 47% under MQL conditions compared to the flood coolant; however, work hardening at the surface was also shown to increase by 10–20%. Understanding this, it is possible that MQL can completely remove the need for a conventional coolant in the machining of Inconel 617 components for the manufacturing of next-generation reactors. Full article

H13 steel, a widely used material in hot work tooling, faces premature failure due to insufficient hardness and wear resistance. To address this limitation, Mo₂FeB₂ cermet coatings were fabricated on H13 alloy steel via plasma spray welding, and subsequently quenched at 850 °C, 1000 °C, and 1150 °C. The effects of the quenching temperature on the microstructure and wear resistance were investigated using optical microscopy (OM) for cross-sectional morphology, scanning electron microscopy (SEM) for microstructural and wear surface analyses, energy-dispersive spectroscopy (EDS) for elemental composition analysis, and X-ray diffraction (XRD) for phase identification. The coating primarily consisted of α-Fe, Mo₂FeB₂, (Mo,Fe,Cr)₃B₂, and Fe₂₃(B,C)₆ phases. Increasing the temperature to 1150 °C increased the Mo₂FeB₂ hard phase and elevated microhardness by 32.04% (from 827 HV_0.5 to 1092 HV_0.5). Wear resistance improved by 46.38% (mass loss reduced from 6.9 mg to 3.7 mg). The main wear mechanism was identified as abrasive wear due to the spalling of hard phase particles. These results demonstrate that optimizing quenching temperature enhances the hardness and wear resistance in Mo₂FeB₂ coatings, offering a viable strategy to extend H13 steel service life in high-temperature industrial applications. Full article

Introduction: Open tibial fractures carry a high risk of fracture-related infection (FRI), and prevention typically relies on early antibiotics and debridement. However, achieving optimum local antibiotic concentration remains challenging. Gentamicin-coated intramedullary nails (GCN) have been developed to prevent biofilm formation, showing short-term efficacy without interfering with fracture healing. Medium- and long-term data on GCN use are limited. This study aimed to assess the effectiveness and safety of GCN in medium-term follow-up. Methods: A prospective cohort study of patients with open tibial fractures was treated with GCN under a standardized protocol, with a minimum follow-up of 24 months. Patients with traumatic amputations, protocol infringement, or loss of follow-up were excluded. The analysis assessed overall FRI incidence by Gustilo–Anderson (GA) classification. Results: Of 907 patients, 139 were included, with 2 lost to follow-up. The overall FRI incidence was 8.8%, the average healing time was 34.3 weeks, and the non-union rate was 2.2%. FRI incidence by GA classification was 0% in GA I, 2.9% in GA II, 2.9% in GA IIIA, 44.4% in GA IIIB, and 33.3% in GA IIIC. External fixation (EF) was required in 45.2% of cases, with 16.1% developing FRI (14.3% in GA II, 2.8% in GA IIIA, 50% in GA IIIB, and 33.3% in GA IIIC). In non-EF cases, FRI occurred in 2.7% of patients (2.9% in GA IIIA and 25% in GA IIIB). No adverse effects were reported due to locally administered gentamicin. Conclusions: In the medium term, GCN has consistently demonstrated safety and efficacy in preventing FRI in open tibial fractures, particularly in GA IIIA cases, even with the use of temporary EF. These findings highlight its potential as a valuable tool in managing open tibial fractures. However, further studies with long-term outcomes are needed to evaluate its effectiveness in GA IIIB and IIIC fractures. Full article

To address the graphitization of diamond induced by high temperatures during laser cladding of diamond-reinforced composites, this study proposes a laser cladding method utilizing Inconel 718 (IN718) nickel-based alloy as a transition layer which has a lower melting point than the substrate of 45# steel. And then, in order to analyze the detailed characteristics of the samples, scanning electron microscopy (SEM), EDS, Raman spectral analyzer, super-depth-of-field microscope, and friction tests were used. Experimental study and the test results demonstrate that the IN718 transition layer enhances coating performance through dual mechanisms: firstly, its relatively low melting point (1392 °C) reduces the molten pool’s peak temperature, effectively suppressing thermal-induced graphitization of the diamond; on the other hand, simultaneously it acts as a diffusion barrier to inhibit Fe migration from the substrate and weaken Fe–C interfacial catalytic reactions. Microstructural analysis reveals improved diamond encapsulation and reduced interfacial sintering defects in coatings with the transition layer. Tribological tests confirm that samples with the transition layer L exhibit lower friction coefficients and significantly enhanced wear resistance compared to those without. This study elucidates the synergistic mechanism of the transition layer in thermal management optimization and interfacial reaction suppression, providing an innovative solution to overcome the high-temperature damage bottleneck in laser-clad diamond tools. Full article

Patients with chronic obstructive pulmonary disease (COPD) often experience acute exacerbations characterized by elevated neutrophilic inflammation in the lungs. Currently, this condition is diagnosed through visual inspection of sputum color and volume, a method prone to personal bias and unsuitable for patients who are unable to expectorate spontaneously. In this manuscript, we present a novel approach for measuring and monitoring exhaled myeloperoxidase (MPO), a biomarker of neutrophilic airway inflammation, without the need for sputum analysis. The method involves analyzing an unmodified surgical facemask worn by the patient for 30 min using biosensing decals that transfer antibody-coated nanoparticles. These colloids specifically interact with MPO trapped by the facemask in a dose-dependent manner, enabling the quantification of MPO levels, with a dynamic range up to 3 · 10¹ µg·mL⁻¹. The proposed diagnostic approach successfully differentiated patients with acute exacerbations from stable patients with 100% sensitivity and specificity. Healthy individuals also showed significantly lower MPO levels compared to COPD patients. Our results suggest that facemask analysis could be a non-invasive diagnostic tool for airway diseases, particularly in patients unable to expectorate. Full article

Wood–plastic composites (WPCs) are important materials used in interior architectural decorations and landscape construction products. Enhancing the cutting performance of WPCs is of great significance for improving both production efficiency and product quality in factories. This study aims to elucidate the impact of fluorine nano-coating technology on the cutting performance of cemented carbide tools during the milling of WPCs. The main results are given as follows. The cutting force and surface roughness showed similar trends with the varied parameters; both increased with increasing cutting depth and decreased with increasing cutting speed. The fluorine nano-coating technology exerts a positive influence on the cutting performance in terms of lower cutting forces and surface roughness. Meanwhile, based on the analysis of variance results, the experimental factors of cutting speed, depth, and surface treatment had a significant contribution to both cutting force and surface roughness, and cutting depth had the greatest impact on cutting force and surface roughness, followed by cutting speed and tool surface treatment. In general, the cutting performance of WPCs can be improved by higher cutting speed and lower depth, with the tool surface treated with fluorine nano-coating. Full article

The rapid growth of the dairy sector requires advanced monitoring tools to ensure sustainable practices that benefit the environment, economy, and human health. Current monitoring devices often lack multi-parametric capabilities, limiting their ability to provide comprehensive data on critical chemical and biochemical parameters. To address this challenge, this work presented the integration of a real-time multi-parametric device with sensors for pH, temperature, nitrate, and nitrite, providing a comprehensive solution to dairy cattle health monitoring. This solution included an electrochemical platform, Portable Unit for Lab-on-Site Electrochemistry (PULSE), and an application for data processing and display. In-house fabricated flexible gold-printed electrodes demonstrated accurate detection of nitrite and nitrate when integrated with the PULSE, achieving sensitivities of 6.32 $\mathsf{\mu }$A/ppm/${\mathrm{cm}}^2$ in artificial interstitial fluid and 1.92 $\mathsf{\mu }$A/ppm/${\mathrm{cm}}^2$ in phosphate buffered saline, respectively. The PULSE achieved 65.83% and 58.3% lower limits of detection in phosphate buffered saline than a benchtop potentiostat, for nitrate and nitrite, respectively, along with a 24.5% increase in nitrite sensitivity, enhancing its ability to detect lower analyte concentrations. pH sensing was carried out with a commercial screen-printed electrode coated with a layer of iridium oxide. The pH was tested in ruminal complex fluid, obtaining a pH sensitivity of −59.63 mV/pH and an accuracy of 98.9%. These findings highlighted the potential of this technology as an effective tool for dairy cattle health monitoring and its deployment in real-world scenarios. Full article

Reverse osmosis (RO) desalination technology offers a promising solution for mitigating water scarcity. However, one of the major challenges faced by RO membranes is biofouling, which significantly increases the desalination costs. Traditional simulation models often overlook environmental variability and do not incorporate the effects of membrane-surface modifications. This paper develops a bacterial growth model for the prediction of seawater desalination performance, applicable to commercial RO membranes, which can be either uncoated or coated with iron nanoparticles (FeNPs or nZVI). FeNPs were selected due to their known antimicrobial properties and potential to mitigate biofilm formation. The native seawater bacterium Bacillus halotolerans MCC1 was used as a model biofouling bacterium. Growth kinetics were determined at different temperatures (from 26 to 50 °C) and pH values (from 4 to 10) to obtain growth parameters. Microbial growth on RO membranes was modeled using the Monod equation. The desalination performance was evaluated in terms of hydraulic resistance and permeate flux under clean and biofouled conditions. The model was validated using desalination data obtained at the laboratory scale. Bacteria grew faster at 42 °C and pH 10. The pH had a more significant effect than temperature on the bacterial growth rate. The FeNP-coated membranes exhibited lower resistance and maintained a higher long-term water flux than the commercial uncoated membrane. This modeling approach is useful for improving the monitoring of feed water parameters and assessing the operational conditions for minimum biofouling of RO membranes. In addition, it introduces a novel integration of environmental parameters and membrane coating effects, offering a predictive tool to support operational decisions for improved RO performance. Full article

Improving building thermal energy performance is essential to reducing energy consumption, minimizing carbon emissions, and enhancing occupants’ thermal comfort. For this purpose, there is an increasing research interest in this field of building energy performance. This review aims to present a precise and systematic overview of the sensitivity analysis in optimizing the thermal energy performance of buildings. The investigation covers various aspects, including sensitivity analysis techniques, key measures and variables, objectives and criteria, software tools, optimization methods, climate zones, building typology, and climate change effects. The findings reveal that sensitivity analysis is a powerful technique for optimizing energy performance and identifying adaptive strategies such as dynamic shading, reflective coatings, and efficient HVAC set points to address climate change. Most of the study also highlights that the temperature set point is the key influential parameter in both heating-dominant and cooling-dominant climate zones. This review offers critical insights on advancing sustainable building design, informing policy, and guiding future research in energy-efficient building solutions. Full article

PVD hard coatings improve the wear and frictional properties in metal cutting and, therefore, extend the lives of cutting tools. Cutting fluids, including the novel use of liquid carbon dioxide (LCO₂), are crucial for reducing tool wear and enhancing machining efficiency. This experimental research is focused on ball-on-disc wear tests of TiAlN hard coatings in environmental, N₂ and CO₂ atmospheres. In the latter case, the experiments were also performed by adding LCO₂ directly into the contact zone. In order to achieve the same temperatures as real cutting conditions, tests were performed at 250 °C, 500 °C and 700 °C, in addition to room temperature. Results show that the TiAlN coating had the highest wear rate in room-temperature tests, regardless of the atmosphere. The wear significantly dropped with the test temperature. It was the lower in the CO₂ atmosphere at all temperatures than in all gas-only atmospheres. When LCO₂ was introduced to the contact, the wear was at its highest at 500 °C, which is the opposite of all other gas-only atmospheres, where it was at its lowest. In all tribological LCO₂ tests, we noticed increased friction coefficient fluctuations. In all gas-only atmospheres, adhered material was observed on the wear tracks, but in LCO₂, wear debris was not detected either on the disk or on the ball. Full article