This study investigates the fabrication, microstructural evolution, and mechanical properties of Al2O3-Cu-Cr ceramic-metal composites containing 2.5 vol.% metallic phase produced by uniaxial pressing followed by free sintering in a reducing atmosphere. The composites were sintered at temperatures ranging from 1200 degrees C to 1400 degrees C in order to evaluate the influence of thermal processing on densification behaviour, phase stability, and mechanical performance. The results demonstrated a strong dependence of physical properties on sintering temperature. Increasing the temperature from 1200 degrees C to 1400 degrees C improved the relative density from 82.85% to 97.99%, while open porosity decreased from 16.57% to 0.09%. Simultaneously, water absorption was reduced from 4.66% to 0.2%, indicating near-complete densification at 1400 degrees C. XRD analysis confirmed the presence of stable alpha-Al2O3, Cu, and Cr phases without formation of undesirable secondary reaction products. SEM/EDS observations revealed a homogeneous distribution of discrete Cu-Cr metallic regions within the alumina matrix and satisfactory ceramic-metal interfacial bonding. The composites sintered at 1400 degrees C exhibited a hardness of 13.8 +/- 1.6 GPa and fracture toughness of 4.41 +/- 0.78 MPa & centerdot;m0.5. Digital image correlation analysis during compression testing demonstrated localized strain evolution preceding brittle fracture. The results indicate that Cr addition may contribute to improved microstructural stability and densification behaviour of Al2O3-Cu composites processed by conventional powder metallurgy routes.
Additive manufacturing (AM) of precipitation-hardened stainless steels, particularly 17-4PH (AISI 630), has gained significant attention due to its ability to produce complex geometries combined with high mechanical performance. However, despite the advantages of Powder Bed Fusion (PBF) technologies such as Selective Laser Melting (SLM) and Direct Metal Laser Sintering (DMLS), components fabricated via AM exhibit inherent surface and microstructural imperfections, including porosity, unmelted particles, and anisotropic microstructures, which may significantly reduce fatigue, wear, and corrosion resistance. This review provides a comprehensive analysis of additive manufacturing techniques applied to 17-4PH steel, focusing on the relationship between processing parameters, microstructure evolution, and resulting mechanical properties. Particular emphasis is placed on post-processing strategies, especially heat treatment and surface modification methods. Among these, shot peening is identified as one of the most effective and economically viable techniques for improving surface integrity. It induces compressive residual stresses, grain refinement, and phase transformation, leading to significant improvements in hardness, wear resistance, corrosion resistance, and fatigue life. Recent studies, including those by Walczak and & Sacute;wietlicki, demonstrate that shot peening of additively manufactured 17-4PH steel can increase surface hardness by over 100% and significantly reduce wear rates while enhancing corrosion resistance. The synergistic combination of heat treatment and surface engineering is shown to be essential for achieving optimal performance. Overall, this work highlights that while AM enables superior design flexibility, the final performance of 17-4PH components is critically dependent on post-processing, particularly surface modification.
Over recent decades, carbon nano-onions and related nanomaterials have attained considerable research interests for wide ranging industrial purposes. In view of that, current review article is developed to highpoint three significant engineering characteristics (including radiation defense, friction/wear resistance, and corrosion resistance) of carbon nano-onions and derived multifunctional polymeric and inorganic hybrids. In all these scientifically and industrially promising fields, carbon nano-onion nanoadditives have enhanced the radiation absorption, tribological, and anticorrosion performance of the polymeric and inorganic matrices. Consequently, carbon nano-onions derived nanocomposites have fine interfacial links and percolation networks; thereby leading to efficient electron transfer and electromagnetic absorption or dissipation properties. In the case of antiscratch, antiwear, and antifriction performance, carbon nano-onions have been noted to act as microbearing between the desired metal surfaces. Furthermore, owing to the development of matrix-nanofiller interactions and electron conducting paths, carbon nano-onions and derivative multifunctional hybrids offer notable barrier effects towards the percolating corrosion species. Decisively, carbon nano-onions, modified carbon nano-onions, and derived hybrids depicted technological promise to enhance the electromagnetic, wear, and erosion resistance of space, automotive, defense, civil, medical, and other advanced structural materials. Nevertheless, limited research exertions seen up till now regarding carbon nano-onions nanocomposites in these technical areas and comprehensive future investigations may unfold their industrial potential.
This study aims to predict the compressive strength of mortars produced with GBFS and SMS. A total of 72 samples were prepared using six mixture ratios and four Na2SiO3 dosages and cured at 75 degrees C for 24 h. The dataset was analyzed using multivariate regression and machine learning models. Among regression approaches, the power function performed best (RMSE approximate to 4.9204 MPa, NSE approximate to 0.9284). However, the Gaussian Process (GP) model outperformed all other methodologies with the lowest prediction error and exceptional correlation (RMSE approximate to 1.4203 MPa, NSE approximate to 0.9920).
The aim of this study was to investigate the macrostructure, microhardness, and basic mechanical properties of AA6061-AA7075 FSW butt joints produced at different tool rotational speeds (600, 1000, and 1400 rpm) and with offsets toward the AA6061 alloy (0, 1, and 2 mm). The results of the study made it possible to demonstrate that sound, defect-free dissimilar AA6061-T6/AA7075-T6 FSW joints can be produced within the investigated parameter set. The HAZ of the lower-strength alloy was identified as the most critical region of the joint, as confirmed by both microhardness measurements and the fact that all tensile-tested specimens fractured in the HAZ of the 6061-T6 alloy. At the same time, the minimum hardness in this region remained essentially unchanged (approximately 60 HV0.1) across the investigated welding parameters. For joints produced at a constant tool rotational speed of 1000 rpm, increasing the tool offset toward AA6061-T6 reduced weld nugget microhardness due to the increased fraction of the softer alloy in the stirred region, while simultaneously improving elongation at fracture without a noticeable change in tensile strength. Overall, the produced joints exhibited highly repeatable mechanical properties, with joint efficiency in the range of 65-67%.
Electroless Ni-P-Zr films are deposited onto Al substrates. Effect of different pre-treatments on the subsequent chemical plating. XRD analysis shows that the Ni-P-Zr film is amorphous. Grey-Taguchi shows that the Ni-P-Zr coating exhibits a friction coefficient of 0.35, a corrosion potential of -0.60 V, a Vickers hardness of 582.9 HV, and a fatigue life of 52 times. A comparison of fatigue failure mechanisms for the uncoated substrate and the electroless Ni-P-Zr coating is conducted under high-strain low-cycle fatigue loading. The results confirm that the coating eliminates crack initiation and propagation and increases the fatigue life of the specimens.
Due to the limited camera depth of field, intense arc interference, and occlusion by fixed weld points, the accurate detection and recognition of the seam for gap-free butt joints confronts substantial technical difficulties. These difficulties are further exacerbated by the limited generalization capability of traditional image processing methods under such noisy and occluded conditions. In response, a vision sensor was designed based on the Scheimpflug imaging principle, utilizing a tilted lens structure to extend the range of clear imaging. The camera calibration process was simplified by modeling the Scheimpflug transformation as specific distortion parameters. An improved lightweight YOLOv3 network was developed, employing a MobileNetV1 backbone combined with an improved Bi-FPN structure, significantly enhancing inference speed while maintaining detection accuracy. Training results demonstrate that the proposed method achieves a mean Average Precision (mAP) of 96.74% for detecting weld seams and fixed points with an inference speed of 63.45 FPS. In the context of thin-sheet, gap-free butt welding with tack weld interference, the proposed method exhibits satisfactory robustness and practical utility. Furthermore, a trajectory fitting algorithm for the weld seam center was developed based on the grayscale distribution characteristics within the detection bounding boxes, enabling effective marking of the weld trajectory and thereby laying the foundation for weld seam tracking.
Abstract This study presents the fabrication and characterization of functionally graded Al 2 O 3 -Ni ceramic-metal composites using centrifugal gel casting with 2-carboxyethyl acrylate (CEA) as the monomer. Two Series of composites were produced under different centrifugal conditions to investigate their influence on nickel distribution, microstructure, and mechanical performance. The CEA-based gel system enabled the formation of dense green bodies with improved phase dispersion and sintering behavior. Microstructural analysis revealed that lower rotational speed and longer casting time (2500 rpm, 110 min) led to a more uniform radial distribution of nickel particles and reduced agglomeration. This microstructural improvement resulted in significantly higher compressive strength (1620 kN) compared to the faster cast series (977 kN). Digital image correlation confirmed more distributed strain fields and delayed fracture in the optimized samples. These findings demonstrate that casting parameters and monomer chemistry can be effectively tailored to engineer dense, robust, and gradient-structured ceramic–metal composites for high-performance applications.
The Underwater Friction Stir Welding (UFSW) environment was proven to improve mechanical properties of the Friction Stir Welded (FSW) joints. However, carefully selected set of parameters is necessary to succeed. This study presents preliminary results of the research on water salinity level effect on the properties of the AA5754 aluminum alloy joints. For this purpose, the Plackett-Burman design was used. The design of experiment consists of ten attempts with process parameters as variables: welding speed, rotational speed, tool tilt angle and water salinity level. The following tests were proceeded: visual tests, tensile strength tests and fractography analysis. Thus, the response variable was ultimate tensile strength (UTS). Surface defects were found in joints performed with low heat input (i.e. low rotational speed, high welding speed). The highest UTS values - 100% of base metal were obtained for the joint made with process parameters: welding speed - 37.5 mm/min, rotational speed - 1235 rpm, tool tilt angle - 2 degrees, water salinity level - 10%. The fractography of the joint revealed precipitates formation and very small dimples. All of the investigated welding parameters were found to be statistically significant. However, the tool tilt angle was of drastically highest significance. The order of the other process parameters was as following: welding speed, rotational speed and water salinity level.
Laser welding, thanks to the use of oscillating heads, is finding increasing use in modern industry. Laser oscillating welding heads offer numerous advantages over traditional laser welding heads. Currently, industries where preparing components for laser welding was previously a significant challenge can now adopt this welding technique thanks to the use of oscillation. The ability to improve the properties of welded joints, autogenous welding, and a high level of process automation make laser welding technology a promising industry. Unfortunately, the complexity of multidimensional processes, already difficult to apply, combined with the wide range of possibilities for modifying beam oscillation, requires a deeper understanding of the impact of new laser welding parameters on the quality of welded joints for industrial implementation. This article presents the results of studies on the microstructure of austenitic stainless steel welded with a laser beam at various welding beam oscillation parameters. The welds were obtained using a ytterbium QCW (Quasi Continuous Wave) fiber laser autogenous (without the use of the filler material). The test material was 4 mm thick AISI 304 austenitic stainless steel sheets as delivered. The aim of this study was to investigate the effect of oscillation parameters such as frequency, amplitude, and shape used during laser welding on weld geometry. Statistical relationships between the studied variables were identified. Laser power exhibits strong positive correlations with key weld geometry parameters, particularly penetration depth (H: r = 0.66), weld face width (B: r = 0.79), and cross-sectional area (S: r = 0.80). In contrast, laser beam oscillation parameters show a negative correlation with penetration depth (H: r = -0.48) and a moderate correlation with weld face width (B: r = 0.56). Other oscillation related effects demonstrate only weak correlations (r <= 0.38) with weld geometry. Mathematical models describing these relationships were developed and their quality verified. The presented models enable the prediction of the transverse shape dimensions of welds based on known welding parameter values.
This study examines the influence of print orientation and printing speed on the mechanical strength and surface roughness of components fabricated from Polylactic Acid (PLA) using the Fused Deposition Modeling (FDM) process. The 3D-printed samples were produced with varying orientations (0 degrees, 90 degrees, and 45 degrees) and print speeds, while other parameters remained constant. All samples had a 100% infill density, a "Lines" infill pattern, and a printing temperature of 210 degrees C. The 0 degrees and 90 degrees samples were printed at 50 mm/s, whereas the 45 degrees samples were printed at 40, 60 and 80 mm/s. Each sample was printed three times to ensure repeatability and obtain an average result. The results indicate that raster angle plays a critical role in determining mechanical performance, with 0 degrees and 90 degrees orientations yielding the highest 72.31 MPa and lowest 56.26 MPa stress values, respectively. Additionally, a nuanced relationship was observed between printing speed, surface roughness, and tensile strength. Surface roughness metrics, including Ra, Rz, and Rq, improved with decreasing printing speed, indicating enhanced surface finishes. The optimal tensile strength of 57.95 MPa was achieved at a moderate printing speed of 60 mm/s, offering the best balance between mechanical strength and surface quality. This research enhances the understanding of parameter optimisation in FDM processes, providing practical insights for the production of high-performance PLA-based components.
This study examines the influence of psyllium husk flour (PF) on the structure and physical properties of thermoplastic starch (TPS) films. Films with 2 g and 6 g PF were produced using the casting method. Their morphology was analyzed by stereoscopic, scanning electron, and atomic force microscopy, while mechanical and wettability properties were evaluated. Increasing PF content improved impact strength but also increased brittleness. Higher PF concentration raised the water contact angle and reduced its change over time. The results indicate that psyllium husk flour effectively enhances the functional performance of TPS films, supporting their potential for sustainable packaging applications.
In this study, we present a comprehensive machine learning-based approach for optimizing alloy compositions with the goal of simultaneously maximizing Ultimate Tensile Strength (UTS) and approaching a target Melting Completion temperature. Using a dataset comprising elemental compositions of various alloys and their corresponding mechanical properties, we developed predictive models based on the Random Forest Regressor algorithm. SHAP (SHapley Additive exPlanations) and LIME (Local Interpretable Model-agnostic Explanations) were employed to interpret the feature contributions and determine the most influential elements on both UTS and melting behavior. The analysis revealed that elements such as Fe, Mn, Co, and Mo significantly contribute to optimal alloy performance, while elements like C and V play a critical role in enhancing UTS. A multi-objective optimization was conducted using a Genetic Algorithm (GA), yielding an optimal composition that achieved a predicted UTS of 1520.7 psi and a Melting Completion temperature of 1407.4 degrees C, closely aligned with the target of 1460 degrees C. Our approach demonstrates the potential of combining interpretable machine learning with evolutionary optimization to accelerate intelligent alloy design and discovery.
Tungsten Inert Gas (TIG) welding constitutes a key process in the fabrication of welded structures, with widespread application across various sectors of modern industry. It continues to be the subject of extensive research due to its technical advantages and versatility. However, despite its industrial importance, TIG welding has not yet been the focus of a comprehensive bibliographic review. Therefore, the objective of this study is not only to present the current state of knowledge but also to identify key process directions and emerging research trends through a bibliometric analysis of 8,789 publications indexed in Web of Science. The analyses were performed mainly in VOSviewer 1.6.20 and Biblioshiny tools, determining the networks of connections between bibliometric entities: keywords, journals, authors, countries, and funding agencies. The analysis results were used to illustrate the dynamics of research topics over a 60-year publication history on the TIG process. Current research trends include, among others, the advancement of TIG welding variants to improve process efficiency, the application of artificial intelligence, the application of optimization methods, and deep learning. The most urgent research needs involve determining the weldability of special metals, assessing the environmental degradation of TIG-welded joints, and applying data mining techniques for the optimization of the TIG process. The study may serve as an objective, comprehensive, and author-unbiased complement to traditional systematic review articles on TIG welding and related processes.
The present review article is planned to systematically unfold salient worth of three dimensional graphene based polymeric nanocomposites for radiation shielding (electromagnetic, nuclear, gamma, fast neutrons) purposes. As per literature reports so far, we discuss polymer/three dimensional graphene nanocomposites for variety of thermoplastic, thermoset, and conjugated matrices employed for related high end material designs. Accordingly, multifunctional hybrids of three dimensional graphene have been fabricated via facile/resourceful fabrication techniques, including solution processing, in situ method, melt technique, freeze drying, hydrothermal tactic, printing, foaming, and allied synthesis procedures. The ensuing three dimensional graphene based hybrids/nanomaterials have been analyzed for microstructural, structural integrity, electron/charge conduction, dielectric features, permittivity, radiation shielding effectiveness, shielding efficiency, and other features desirable for nuclear/gamma/electromagnetic radiation protection application. Besides, underlying mechanisms of radiation attenuation have also been argued, as per scientific surveys. It seems that performance of hierarchical graphene nanoassmblies relies upon nanoarchitectural adaptability, interfacial interactions/wettability, and structure-property synergies. Eventually, inimitable polymer/three dimensional graphene nanocomposites have been found promising to meet technological demands of radiation shielding in aeronautics, devices, defense, and nuclear power plant industries. Despite practical success of radiation shielding three dimensional graphene hybrids, in spite of pristine graphene, future deployment in related industrial modules seems to be connected to focused experimental/theoretical endeavors by field researchers to overcome underlying design/property/performance challenges.
The machinability of two copper alloys with lead: CuZn40Pb2 and CuSn5Zn5Pb2, was assessed. Turning tests were performed based on the selection of parameters that will result in the tool being worn out after 1 minute. Tool wear was assessed by observing dimensional and microstructural changes in the blade. When assessing machinability, power consumption, chip shape, changes in the surface layer and surface roughness were taken into account. The research aims to determine the custom machinability index of materials used in SANHA Polska. A publicly available index must be adapted to a given application, and such adaptation is often quite time-consuming. Therefore, a 1-minute test was carried out as a quick and cheap alternative to a large fleet of machines with various machining properties. The developed methodology and the results obtained are the basis for further research conducted as part of the implementation doctorate, the aim of which is to implement the production of well-machinable lead-free materials for drinking water installations, characterized by good solderability and corrosion resistance. As a result of the conducted research, the role of lead in the machining of copper alloys was identified, which is important due to European restrictions on the elimination of this element and its replacement in a way that allows for precise removal processing.
This study aims to investigate and optimize the thermal dissipation of a constant heat flux source by conducting a numerical analysis of four serpentine mini-channel heat sink configurations, each characterized by different inlet and outlet arrangements for the cooling fluid. The cooling system under study consists of an upper part made of ABS copolymer resin, incorporating the fluid inlets and outlets (water), and a lower part made of aluminum, which contains the serpentine mini-channel heat sink. The analyzed configurations included four cases: First: a single inlet and a single outlet, Second: two inlets and one outlet, Third: one inlet and two outlets, and Fourth: a variation of the third model with reversed inlet and outlet positions. Numerical simulations, performed using the finite volume method, cover a Reynolds number range from 200 to 600. The analysis focuses on flow behavior, temperature distributions, pressure drop, thermal resistance, the average Nusselt number and the performance evaluation factor (PEF). The results indicate that the configurations with two inlets and one outlet (Case 2) and the reversed inlet/outlet configuration (Case 4) significantly enhance cooling compared to the other configurations. However, the two-inlet, one-outlet case also results in a higher pressure drop. At a Reynolds number of 600, Case 2 achieves the best thermal performance with an average Nusselt number of 20.79 and a minimum thermal resistance of 0.228K/W, while Case 3 exhibits the lowest efficiency. These findings help identify optimal configurations for cooling high heat flux electronic components.
MAO processing of titanium biomaterials for long-term implants forms oxide layers resistant to mechanical stresses during surgery, making them among the best surface modifications. Bioactivity can be enhanced using electrolytes with calcium, phosphate, or apatite; mechanical and corrosion properties can be improved by adding other compounds. This study examines effects of voltage, current, deposition time, hydroxyapatite (HA) and multi-walled carbon nanotubes (MWCNTs) in the electrolyte on Ti13Nb13Zr alloy surface properties. Methods included SEM, EDS, profilometry, hardness, corrosion, and wettability tests. CNTs improved mechanical properties, reduced corrosion resistance, slightly affected wettability. Voltage controlled plasma oxidation intensity; current affected ion/molecule mass flux.
This work focuses on improving the mechanical strength and corrosion resistance of Aluminum (Al) AA6063 alloy, which is limited by its moderate hardness and exposure to acidic conditions. The main aim of this study is to examine the effect of Titanium Dioxide (TiO2) and Tungsten Carbide (WC) particles on the hardness and acidic immersion corrosion of AA6063 alloy-based monolithic and hybrid Metal Matrix Composites (MMCs), which were manufactured via stir casting with a fixed 5 wt.% TiO2 and varying wt.% of WC (0, 0.5, and 1 wt.%), followed by T6 heat treatment at different aging temperatures of 145 degrees C, 165 degrees C, and 185 degrees C. The microstructural exploration using Hi-Resolution Scanning Electron Microscopy (HRSEM) and Energy-Dispersive X-ray Spectroscopy (EDS) showed an even dissemination of reinforcements. X-ray Diffraction (XRD) observed the occurrence of Al, TiO2, WC, and Mg2Si phases. Taguchi's methodology optimized the Vicker's hardness and Corrosion Rate (CR), considering aging temperature and wt.% of WC as the input variables. Analysis of Variance (ANOVA) results indicated that the variation in WC content had a more significant effect on both hardness and CR than the aging temperature. The 165 degrees C aged samples produced high hardness and lower CR due to the Silicon (Si) spheroidization. The HRSEM examination of corroded surfaces revealed fewer signs of deep pits at lower CR conditions. The results indicate that the selective incorporation of WC and TiO2 can improve the performance of AA6063 composites in corrosive environments.
In this study, graphite (Gr) nano flakes dispersion with increasing number of passes (1, 2, and 3) inside the resultant aluminium ENAW-6061-O-Gr composites using Friction Stir Processing (FSP) has been accomplished successfully. The objectives were to embed the Gr nanoflakes inside ENAW-6061-O-Gr composites, investigate the effect of number of FSP passes on the mechanical properties of aluminium 6061/graphite composites. The ENAW-6061-O-Gr composite samples were evaluated with tensile tests and elemental analysis through SEM with EDX and mapping. The dispersion and presence of graphite particles is confirmed. Multi-pass FSP improved the tensile strength of the ENAW-6061-O-Gr composites. The UTS of C3-Composite processed with three passes is 153.65 MPa, that is 24% of improvement compared to the unreinforced aluminium ENAW-6061-O base metal alloy.
