Search Results (46)

Zirconium-89 (⁸⁹Zr) is a widely used radionuclide in immune-PET imaging due to its physical decay characteristics. Despite its importance, the production of ⁸⁹Zr radiopharmaceuticals remains largely manual, with limited cost-effective automation solutions available. To address this, we developed an automated system for the agile and reliable production of radiopharmaceuticals. The system performs transmutations, dissolution, and separation for a range of radioisotopes. Steps in the production of ⁸⁹Zr-oxalate are used as an exemplar to illustrate its use. Three-dimensional (3D) printing was exploited to design and manufacture a target holder able to include solid targets, in this case an ⁸⁹Y foil. Spot welding was used to attach ⁸⁹Y to a refractory tantalum (Ta) substrate. A commercially available CPU chiller was repurposed to efficiently cool the metal target. Furthermore, a commercial resin (ZR Resin) and compact peristaltic pumps were employed in a compact (10 × 10 × 10 cm³) chemical separation unit that operates automatically via computer-controlled software. Additionally, a standalone 3D-printed unit was designed with three automated functionalities: photolabelling, vortex mixing, and controlled heating. All components of the assembly, except for the target holder, are housed inside a commercially available hot cell, ensuring safe and efficient operation in a controlled environment. This paper details the design, construction, and modelling of the entire assembly, emphasising its innovative integration and operational efficiency for widespread radiopharmaceutical automation. Full article

Resistance spot welding was performed to join a 2 mm thick TA2 titanium plate and Q235 steel plate using nickel foil with thicknesses of 0.02 mm, 0.04 mm, and 0.06 mm as interlayers. The microstructure of the nugget zone and the interface region of the joint were systematically observed and analyzed, and the tensile shear-bearing capacity of the joint was evaluated. As the welding current increased, the tensile shear load of the joint exhibited a trend of initially increasing and subsequently decreasing. When the welding current was 8 kA, the tensile shear load of the joints with an interlayer of 0.04 mm thickness reached a maximum value of 8.02 kN. The results indicate that employing a reduced welding current can effectively prevent the mixing of nuggets on both sides of the titanium and steel interface. This ensures that the intermetallic compounds formed in the interface region are confined to the Ti-Ni series, which is crucial for enhancing the tensile shear load of the joint. Full article

Electrolytic copper foil is one of the core materials in the fields of electronics, communications, and power. The cathode roller is the key component of the complete set of electrolytic copper foil equipment, and the quality of the titanium cylinder of the cathode roller directly determines the quality of the electrolytic copper foil. There typically exists a longitudinal weld on the surface of the cathode roller’s titanium cylinder sleeve manufactured by the welding method, which leads to the degradation of the quality of the electrolytic copper foil. Refining the grains in the weld zone and the heat-affected zone to close to those of the base material is a key solution for the manufacturing of welded cathode rollers. In order to effectively modify the microstructure and obtain an optimal refining effect in the weld zone of a TA1 cathode roller, a novel composite technology consisting of low-energy and fewer-pass welding combined with multi-pass rolling deformation and vacuum annealing treatment was primarily explored for high-purity TA1 titanium plates in this study. The microstructure of each area of the weld was observed using the DMI-3000M optical microscope, and the hardness was measured using the HVS-30 Vickers hardness tester. The research results show that the microstructure of each area of the weld can be effectively refined by using the novel composite technology of low-energy and fewer-pass welding, multi-pass rolling deformation, and vacuum annealing treatment. Among the explored experimental conditions, the optimal grain refinement effect is obtained with a V-shaped welding groove and four passes of welding with a welding current of 90 A and a voltage of 8–9 V, followed by 11 passes of rolling deformation with a total deformation rate of 45% and, finally, vacuum annealing at 650 °C for 1 h. The grain size grades in the weld zone and the heat-affected zone are close to those of the base material, namely grade 7.5~10, grade 7.5~10, and grade 7.5~10 for the weld zone, heat-affected zone, and base material, respectively. Meanwhile, this technology can also refine the grains of the base material, which is conducive to improving the overall mechanical properties of the titanium plate. Full article

Laser welding has become well established for joining Ni-Ti-based shape memory alloys and extends the manufacturability of highly functional components with complex geometries. Published studies on the effect of laser welding on alterations to microstructure and properties of these alloys, however, mainly deal with conventional component dimensions and linear laser beam movement. In view of the increasing importance of microtechnology, research into joining of thin-walled Ni-Ti components is therefore of interest. At the same time, studies comparing oscillating and linear beam movement on other materials and the authors’ own work on Ni-Ti materials suggest that oscillating beam movement has a more favorable effect on alterations in material properties and microstructure. Therefore, laser welding of foils made of Ni55/Ti45 with 125 µm thickness was systematically analyzed using a fiber laser and circular oscillation. Amplitude A and frequency f were varied from 0 to 200 µm and 0 to 2000 Hz, respectively. Microstructural analysis showed that by increasing the frequency, grain refinement could be achieved up to a certain value of f. An increasing amplitude led to decreasing hardness values of the weld seam, while the influence of f was less pronounced. The analysis of the weld material using chip calorimetry (Flash DSC) revealed that the beam oscillation had fewer effects on the change in transformation points compared to a linear beam movement. Full article

A mechanically robust flexible transparent conductor with high thermal and chemical stability was fabricated from welded silver nanowire networks (w-Ag-NWs) sandwiched between multilayer graphene (MLG) and polyimide (PI) films. By modifying the gas flow dynamics and surface chemistry of the Cu surface during graphene growth, a highly crystalline and uniform MLG film was obtained on the Cu foil, which was then directly coated on the Ag-NW networks to serve as a barrier material. It was found that the highly crystalline layers in the MLG film compensate for structural defects, thus forming a perfect barrier film to shield Ag NWs from oxidation and sulfurization. MLG/w-Ag-NW composites were then embedded into the surface of a transparent and colorless PI thin film by spin-coating. This allowed the MLG/w-Ag-NW/PI composite to retain its original structural integrity due to the intrinsic physical and chemical properties of PI, which also served effectively as a binder. In view of its unique sandwich structure and the chemical welding of the Ag NWs, the flexible substrate-cum-electrode had an average sheet resistance of ≈34 Ω/sq and a transmittance of ≈91% in the visible range, and also showed excellent stability against high-temperature annealing and sulfurization. Full article

Laser welding, widely used in industries such as automotive and aerospace, requires precise monitoring to ensure defect-free welds, especially when joining dissimilar metallic thin foils. This study investigates the application of machine learning techniques for defect detection in laser welding using photodiode signal patterns. Supervised models, including Support Vector Machine (SVM), k-Nearest Neighbors (kNN), and Random Forest (RF), were employed to classify weld defects into sound welds (SW), lack of connection (LoC), and over-penetration (OP). SVM achieved the highest accuracy (95.2%) during training, while RF demonstrated superior generalization with 83% accuracy on validation data. The study also proposed an unsupervised learning method using a wavelet scattering one-dimensional convolutional autoencoder (1D-CAE) network for anomaly detection. The proposed network demonstrated its effectiveness in achieving accuracies of 93.3% and 87.5% on training and validation datasets, respectively. Furthermore, distinct signal patterns associated with SW, OP, and LoC were identified, highlighting the ability of photodiode signals to capture welding dynamics. These findings demonstrate the effectiveness of combining supervised and unsupervised methods for laser weld defect detection, paving the way for robust, real-time quality monitoring systems in manufacturing. The results indicated that unsupervised learning could offer significant advantages in identifying anomalies and reducing manufacturing costs. Full article

Gleeble thermomechanical simulators are widely utilized tools for the investigation of high-temperature deformation behavior in materials. However, temperature gradients that develop within the specimen during Gleeble compression tests have the potential to result in non-uniform deformation, which may subsequently impact the accuracy of the measured mechanical properties. This study presents an experimental and numerical investigation of the temperature fields in 2017-T4 aluminum alloy specimens prior to Gleeble compression tests at temperatures ranging from $300 °\mathrm{C} \mathrm{to} 500 °\mathrm{C}$ utilizing uniform temperature distribution (ISO-T) tungsten carbide anvils. The use of multiple thermocouples, welded to both the specimen and anvils, offers valuable insights into the temperature gradients and their evolutions. A coupled thermal–electrical finite-element model was developed in Abaqus for the purpose of simulating the resistive heating process. A user amplitude subroutine (UAMP) is implemented to regulate the heating based on a proportional–integral–derivative (PID) algorithm that modulates the current density to follow the specified temperature profile. The numerical results demonstrate that the temperature gradients within the specimen at the end of the heating process, reaching a temperature of $400 °\mathrm{C}$, are minimal, with values below $1.9 °\mathrm{C}$. This is in accordance with the experimental observations. The addition of graphite foils between the specimen and anvils has been shown to effectively reduce the gradients. The use of the measured anvil temperature as a boundary condition, rather than a constant value of $20 °\mathrm{C}$, has been demonstrated to improve the agreement between the simulated and experimental cooling curves. The modeling approach provides a framework for quantifying temperature gradients in Gleeble compression specimens and for assessing their impact on the measured constitutive response of materials at elevated temperatures. Full article

Ultrasonic additive manufacturing (UAM) is a process used for the three-dimensional printing of metal foil stock that can produce near-net-shaped metallic parts. This work details the development of an energy-based tool to identify the relationships between input energy, energy stored in the interface microstructure, and the strength of the weld interface in UAM. The stored energy in the grain boundaries of the crystallized grains in the interface microstructure are estimated using the Read–Shockley relationship. The energy stored in the interface is found to be positively correlated with the resulting weld strength. An energy flow diagram is developed to map the flow of energy from the welder to the workpiece and quantify the key participating energies such as the energy of plastic deformation, energy stored in the interface microstructure, energy required for asperity collapse, and heat generation. A better understanding of the flow of energy in UAM can assist in optimizing the process to maximize the portion of energy input by the welder that is used for bond formation. Full article

The need to manufacture components out of copper is significantly increasing, particularly in the solar technology, semiconductor, and electric vehicle sectors. In the past few decades, infrared laser (IR) and green laser (GL) have been the primary technologies used to address this demand, especially for small or thin components. However, with the increased demand for energy saving, alternative joint techniques such as blue diode laser (BDL) are being actively explored. In this paper, bead-on-plate welding experiments on 0.2 mm thick pure copper samples employing a BDL are presented. Two sets of parameters were carefully selected in this investigation, namely Cu-1: Power (P) = 200 W; Speed (s) = 1 mm/s; and angle = 0°, and Cu-2: P = 200 W; s = 5 mm/s; and angle = 10°. The results from both sets of parameters produced defect-free full penetration welds. Hardness test results indicated relatively softer weld zones compared with the base metal. Tensile test samples fractured in the weld zones. Overall, the samples welded with Cu-1 parameters showed better mechanical properties, such as strength and elongation, than those welded with the Cu-2 parameters. The tensile strength and elongation obtained from Cu-1 were marginally lower than those of the unwelded pure copper. The outcomes from this research provide an alternative welding technique that is able to produce reliable, strong, and precise joints, particularly for small and thin components, which can be very challenging to produce. Full article

Recent research focuses on replacing metal current collectors with metallized polymer foils. However, this introduces significant challenges during cell production, as manufacturing steps must be adapted. Currently, copper is used as the current collector on the anode side and aluminum on the cathode side. These current collectors are then joined within the cell with an arrester tab. This step, known as contacting, is carried out industrially in pouch cells using ultrasonic welding or laser beam welding. However, since the polymer foil is electrically insulating, the current contacting procedures cannot be directly transferred to the metal–polymer current collectors. In this work, ultrasonic welding, laser beam welding, and a mechanical contacting method are considered, and the challenges arising from the material properties are highlighted. The properties of the joints are discussed as a function of the number of foils and the coating thickness of the metallization. It is demonstrated that successful contacting by ultrasonic welding and mechanical clamping is possible, as both mechanical strength and electrical conductivity are ensured by the joint. Laser beam welding was unsuccessful. Additionally, the electrical resistance is one to two orders of magnitude higher than that of pure aluminum and copper foils, which necessitates further optimization. Furthermore, ultrasonic welding is limited to welding 16 foils or fewer. This does not match industrial requirements. Consequently, novel approaches for contacting metal–polymer current collectors are required. Full article

The microstructures and mechanical properties of laser penetration welded joints of overlap steel-on-aluminum were investigated. The structure of the intermetallic compound layer without interlayer consists of FeAl and FeAl₃ phases. After the Ni-foil was added, the thickness of the intermetallic compound layer and the content of the brittle and hard Al-Fe phase decreased significantly, and some new phases of Al_0.9Ni_1.1 and FeNi were formed. It was found that the Ni interlayer enhanced the tensile property of the joint by about 40% and decreased the microhardness of the intermetallic compounds, which is attributed to the improvement of the toughness of the welded joint made by the Ni interlayer. It is an effective way to improve the mechanical properties of the laser welding joint by adding a nickel interlayer to improve the metallurgical reaction. Full article

To weaken the harm of Al–Si coating and increase the strength of welded joints, variable thicknesses of Ni foil (Ni, an austenitic formation element) were added to the lap laser welding Al–Si-coated 22MnB5 hot stamping steel/galvanized steel joints. The joints’ weld appearance, microstructure, and mechanical properties were explored. The weld altered from an X shape to a Y shape with an increased thickness of Ni foil. During welding, Al–Si coating was melted and diluted into the welding pool, forming δ-ferrite (a rich-Al phase with low toughness and strength) in the fusion zone (FZ) and fusion boundary (FB). This phase deteriorated the strength of the joints. After adding Ni, the amount and size of the δ-ferrite phase decreased. With a significant thickness of Ni foil, δ-ferrite disappeared. However, a new phase (fresh martensite (FM), which formed at low temperature and contained rich Ni) probably formed, except PM (previous martensite (PM), which formed at high temperature and contained little Ni or no Ni). The heat-affected zone (HAZ) on the side of 22MnB5 comprised a coarse martensite zone, refined martensite zone, martensite + ferrite zone, and tempered martensite zone from the FZ to the basic material. HAZ on the side of galvanized steel mainly contained ferrite and pearlite. After adding the Ni foil, the strength of the joint was greater than that without Ni. The maximum strength of the joint can be up to 679 MPa because of the disappearance of δ-ferrite. Meanwhile, the toughness of the joint increased. The fracture mode was from three mixed fractures (cleavage, quasi-cleavage, and dimple) to one fracture (dimple). Full article

Brittle intermetallic compounds, formed during the welding process of titanium/aluminum (Ti/Al), lead to a significant reduction in joint mechanical properties. The purpose of this study is to mitigate the formation of brittle phases during the laser welding of dissimilar Ti/Al metals, thereby enhancing the mechanical properties of the joints. In this investigation, an innovative approach is adopted, utilizing Nb foil as an interlayer to effectively minimize the formation of brittle intermetallic phases during dissimilar welding. A comprehensive analysis of the microstructure of the transition layer was conducted using material characterization methods, including scanning electron microscope equipped with an energy dispersive X-ray spectrometer. The mechanical performance of the welded joints was assessed using tensile testing. The results indicate that the effective welding width and joint penetration depth at the joint interface were reduced in Ti/Al dissimilar metals when Nb was added as an intermediate layer, under the same welding process parameters, when compared to unalloyed weld seams. Furthermore, the utilization of a 0.05 mm Nb foil as the intermediate layer results in a significant 25% increase in the average shear strength compared to the other condition, with the average shear strength of the joint reaching its peak value at 192 N/mm. The unalloyed Ti/Al weld joint usually fractured along the melting zone, displaying complete brittle fracture characteristics. After Nb microalloying, the joint typically fractures along the transition zone and interface, exhibiting both cleavage and ductile fracture characteristics, indicating the combination of a brittle and toughness fracture. This study provides experimental evidence and new insights for welding Ti/Al composite structures, with significant theoretical and practical applications. Full article

In this study, a fiber laser at a wavelength of 1070 nm with different beam shapes (spot, dough-nut, and spot-wobble) was used to weld thin 316 L stainless steel foils. The welding speed was varied from 400 to 1000 mm/s in the absence of shielding gas. The weld geometry, microstructure, lap shear strength, and crystallographic grain structure of the micro-joints were analyzed and correlated with the beam shape and welding speed. The results indicate that the laser beam shape significantly affected the weld width and penetration depth, and the best welding speed was 500 mm/s. This study proved for the first time that a spot-wobble laser beam could achieve better mechanical properties and microstructural characteristics than a doughnut beam during the high-power laser welding of thin-foil stainless steel plates. Full article

The welding titanium cathode roller has the obvious advantages of low cost, high efficiency, and no diameter restriction. Unfortunately, the longitudinal weld on the cathode roller adversely impacts the quality of the electrolytic copper foil due to the great difference between the microstructure of the weld zone and the base metal. Thus, it is crucial to reduce their difference by regulating the microstructure of the weld zone. In this study, a novel complex treatment of heat treatment and sandblasting is primarily developed for regulating the microstructure of the weld zone. The results show that the novel complex treatment has an efficient effect on regulating the microstructure of the weld zone and making the microstructure in the weld zone close to that of the base metal. During vacuum annealing, the microstructure of the weld zone is refined to some degree, and 650 °C annealing has the optimal effect, which can effectively reduce the ratio of α phase’s length to width and reduce the microstructure difference between the weld zone and the base metal. At the same time, with an increase in the annealing temperature, the tensile strength and yield strength decreased by about 10 MPa; the elongation after fracture increased by 20%; the average microhardness of the WZ and the HAZ decreased by about 10 HV_0.10; and that of the BM decreased by about 3 HV_0.10. The heat treatment after welding can effectively adjust the properties of the weld zone, reduce the hardness and strength, and improve the toughness. The subsequent sandblasting after annealing can further refine the grain size in the weld zone and make the microstructure in the weld zone close to that of the base metal. Sandblasting after annealing can further refine the grain in the weld zone and make the microstructure in the weld zone close to that of base metal. Meanwhile, an application test confirmed that the adverse impact of a longitudinal weld on the quality of electrolytic copper foil could be resolved by adopting this novel complex treatment. Therefore, this study provides valuable technical support for the “welding” manufacturing of the titanium sleeves of the cathode roller. Full article