Metal Printing Research Articles

Self-adjusting voxelated electrochemical three-dimensional printing of metallic microstructures

Abstract Microscale metallic structures enhanced by additive manufacturing technology have attracted extensive attention especially in microelectronics and electromechanical devices. Meniscus-confined electrodeposition (MCED) advances microscale 3D metal printing, enabling simpler fabrication of superior metallic microstructures in air without complex equipment or post-processing. However, accurately predicting growth rates with current MCED techniques remain challenging, which is essential for precise structure fabrication and preventing nozzle clogging. In this work, we present a novel approach to electrochemical 3D printing that utilizes a self-adjusting, voxelated method for fabricating metallic microstructures. Diverging from conventional voxelated printing which focuses on monitoring voxel thickness for structure control, this technique adopts a holistic strategy. It ensures each voxel’s position is in alignment with the final structure by synchronizing the micropipette’s trajectory during deposition with the intended design, thus facilitating self-regulation of voxel position and reducing errors associated with environmental fluctuations in deposition parameters. The method’s ability to print micropillars with various tilt angles, high density, and helical arrays demonstrates its refined control over the deposition process. Transmission electron microscopy analysis reveals that the deposited structures, which are fabricated through layer-by-layer (voxel) printing, contain nanotwins that are widely known to enhance the material’s mechanical and electrical properties. Correspondingly, in situ scanning electron microscopy (SEM) microcompression tests confirm this enhancement, showing these structures exhibit a compressive yield strength exceeding 1 GPa. The indentation tests provided an average hardness of 3.71 GPa, which is the highest value reported in previous work using MCED. The resistivity measured by the four-point probe method was (1.95 ± 0.01) × 10−7 Ω·m, nearly 11 times that of bulk copper. These findings demonstrate the considerable advantage of this technique in fabricating complex metallic microstructures with enhanced mechanical properties, making it suitable for advanced applications in microsensors, microelectronics, and micro-electromechanical systems.

Sejarah Perkembangan Penulisan Al-Qur’an dan Tafsir di Indonesia

After the Conference of Ulama Al-Qur'an in 1984 and the Decree of the Minister of Religion number 25, it was agreed that the copying of the Al-Qur'an standardized using Ratsm Usmani. The initial emergence of Indonesian standard Mushaf Al-Qur'an cannot be separated from the existence of "Lajnah Pentashih Mushaf Al-Qur'an" which in the 1970's was under the Indonesian Ministry of Religion. However, if look at previous history, the copying of Al-Qur'an was carried out by various levels of society, including Ulama, Santri, or profesional copyists with interest for teaching purposes. So, before Lajnah was established, several regions had classic mushaf with their own characteristics. This research is intended to describe the development of Al Qur'an writting and its interpretation in Indonesia. The aim of this research is to describe the development of Al Qur'an writing. The approach used in this research is a library research approach, which utilizes library sources such as books, scientific journals, ar,ticles and reports. The results of this research show that the development of Al-Qur'an writing in Indonesia is generally divided into two major categories. Some were copied by rasm Usmani and the others with a combination of rasm imlai. This is shows that the traces of the Ottoman Empire in copying the Al Qur'an in the Nusantara were at least known, even though there were no written works that could explain it. As time progressed, the tradition of Al-Quran writing in mushaf (handwritten) form began to innovate with the emergence of various offers in the matter of copying mushaf, including lithography (stone printing), hypography (metal printing)

Surface Quality as a Factor Affecting the Functionality of Products Manufactured with Metal and 3D Printing Technologies.

Surface engineering is one of the most extensive industries. Virtually all areas of the economy benefit from the achievements of surface engineering. Surface quality affects the quality of finished products as well as the quality of manufactured parts. It affects both functional qualities and esthetics. Surface quality affects the image and reputation of a brand. This is particularly true for cars and household appliances. Surface modification of products is also aimed at improving their functional and protective properties. This applies to surfaces for producing hydrophobic surfaces, anti-wear protection of friction pairs, corrosion protection, and others. Metal technologies and 3D printing benefit from surface technologies that improve their functionality and facilitate the operation of products. Surface engineering offers a range of different coating and layering methods from varnishing and painting to sophisticated nanometric coatings. This paper presents an overview of selected surface engineering issues pertaining to metal products, with a particular focus on surface modification of products manufactured by 3D printing technology. It evaluates the impact of the surface quality of products on their functional and performance qualities.

Bi-metallic electrochemical deposition on 3D pyrolytic carbon architectures for potential application in hydrogen evolution reaction

ABSTRACT 3D printing has emerged as a highly efficient process for fabricating electrodes in hydrogen evolution through water splitting, whereas metals are the most popular choice of materials in hydrogen evolution reactions (HER) due to their catalytic activity. However, current 3D printing solutions face challenges, including high cost, low surface area, and sub-optimal performance. In this work, we introduce metal-deposited 3D printed pyrolytic carbon (PyC) as a facile and cost-effective HER electrode. We adopt an integrated approach of resin 3D printing, pyrolysis, and electrochemical metal deposition. 3D printing of a resin and its subsequent pyrolysis led to 3D complex architectures of the conductive substrate, facilitating the electrochemical metal deposition and leading to layered 3D metal architecture. Both monolayers of metals (such as copper and nickel) and bi-metallic 3D PyC structures are demonstrated. Each metal layer thickness ranges from 6 to10 µm. The metal coatings, particularly the bi-metallic configurations, result in achieving significantly higher mechanical properties under compressive loading and improved electrical properties due to the synergistic contributions from each metal counterpart. The metalized PyC structures are further demonstrated for HER catalysts, contributing to the development of highly efficient and durable catalyst systems for hydrogen production. Among the materials studied here, Ni@Cu bimetallic 3D PyC electrodes are particularly well-suited, demonstrating a low HER overpotential value of 264 mV (100 mA/cm2, KOH (1 M)) with corresponding Tafel slopes of 107 mV/dec, with exceptional stability during a 10 h operation at a high applied current of −50 mA/cm2.

Ultrathin α-Bi2O3 Thin-Film Transistor for Cost-Effective Oxide-TFT Inverters.

Electronics is advancing toward greater diversity and sustainability by prioritizing energy efficiency and cost-effectiveness. Metal oxide thin-film transistor (TFT) represents a technology at the forefront of advancing next-generation sustainable electronics, and exploring oxide channel compositions is a crucial step in opening opportunities for developing next-generation device applications. This study presents the first development of n-channel α-Bi2O3-TFTs using a 4 nm ultrathin channel prepared by a cost-effective vacuum-free and solvent-free liquid metal printing method in ambient air. Even the pristine device exhibited a clear TFT action but required a large negative gate bias to turn off due mainly to excess carriers from oxygen vacancy in the α-Bi2O3 channel. Oxygen-containing post-annealing reduced both channel carrier and subgap defect densities, enabling the development of depletion and enhancement-type α-Bi2O3-TFTs with the saturation mobility of 2-4 cm2 V-1 s-1. Two types of oxide-TFT-based inverter circuits, zero-VGS-NMOS and CMOS inverters, were fabricated by using α-Bi2O3-TFTs, operating in a high voltage gain of over 130. This work demonstrates the potential of oxide semiconductor materials toward the development of next-generation sustainable electronics.

Surface Activation of Cotton Fabric with Low-Temperature Air Plasma Treatment for Metallic Printing

In this investigation, air plasma treatment was utilised to activate the surfaces of 100% grey and bleached cotton fabrics in preparation for metallic pigment printing. The study delved into the surface morphology, wettability, and surface chemistry properties. Scanning electron microscopy (SEM) revealed roughness and grooves in the treated samples. The contact angle witnessed a 29% and 41% increase for grey and bleached fabrics, respectively, compared to their untreated counterparts. Surface chemistry analysis using FTIR and XPS provided crucial insights into the functional polar groups, such as OH and C=O, along with significantly elevated O1 peaks in both plasma-treated grey and bleached cotton fabrics. These findings contributed to the enhanced surface free energy of the fabrics, preparing them for the subsequent pigment printing process. The study explores the impact of plasma treatment on the colour fastness of grey and bleached cotton fabrics printed with gold and silver metallic pigments. Untreated fabrics exhibited poor durability, with low colour change and staining-resistance ratings, particularly for gold pigments. Plasma treatment significantly improved colour retention, adhesion, and resistance to staining for both metallic pigments, with silver outperforming gold. Rubbing fastness tests revealed that plasma treatment moderately enhanced durability, though gold remained susceptible to friction damage. Light fastness was excellent for both pigments, and plasma treatment further improved performance. Perspiration tests showed that plasma treatment bolstered resistance, particularly for gold. These findings suggest that plasma treatment enhances the stability of metallic pigments, offering potential applications in the textile industry for improved product quality and durability.

Nonlinear vibration analysis of sandwich plates with inverse-designed 3D auxetic core by deep generative model

Building on a deep generative model (DGM), this paper introduces an innovative sandwich plate structure featuring an inverse-designed auxetic 3D lattice core and conducts a detailed investigation of its nonlinear vibration characteristics and effective Poisson's ratios under various parameter settings. By incorporating a conditional estimator and quality loss evaluation functions, the enhanced conditional generative adversarial networks are capable of designing 3D truss auxetic topologies that achieve customized negative Poisson's ratios without reliance on subjective experience. Additionally, lattice specimens are created using 3D metal printing, and the mechanical properties of these DGM-based 3D auxetic structures are validated through vibration experiments and finite element models. These structures exhibit significantly superior natural frequencies compared to those obtained through conventional topology optimization methods reported in existing literature. The study also explores the impact of different functionally graded configurations, temperature variations, boundary conditions, and dimensional parameters on the natural frequency, nonlinear vibration response, and effective Poisson's ratio of the inverse designed auxetic sandwich plates.

Progress in the Application of Porous Tantalum Metal in Hip Joint Surgery.

Porous tantalum metal is a new orthopedic implant material made of tantalum metal that has been processed by porous treatment. This material has various advantages, including high hardness, good ductility, good biocompatibility, and strong bone integration ability. Porous tantalum metal has performed well in clinical application, demonstrating excellent medium- to long-term curative effects. The use of implant products made of porous tantalum metal, such as porous tantalum rods, porous tantalum hip prostheses, and porous tantalum augments (MAs), is gradually increasing in the clinical application of hip surgery, and these products have achieved excellent therapeutic effects in the middle and late stages of various hip diseases. In recent years, the combined application of porous tantalum metal and three-dimenional (3D) printing technology to create personalized 3D-printed porous tantalum metal has led to new development directions for the treatment of complex hip joint surgical diseases. This review presents a summary of the application of porous tantalum metal in hip surgery in recent years, including clinical treatment effects and existing problems. In addition, the prospect of progress in this field is promoted.

RESEARCH ABOUT M300 MARAGING STEEL METALLIC POWDER FOR USE IN SLM 3D PRINTING

A growing number of steel components are being fabricated by 3D metal printing. Using metallic powder as the material fed into the laser is selective laser melting (SLM), one of the most popular and precise techniques. The main focus of this article is the investigation that Renishaw conducted on the powder that was supplied. The powder is made using the gas atomization method, and the powder obtained from the SLM process is then examined. The powder's morphology is analysed using scanning electron microscopy (SEM). The particles were seen to have a spherical shape, with a notable number of satellites attached to their surface. The particle size distribution (PSD) was examined and ranged from 15 to 90 µm. In addition, the porosity exhibited a range of values between 0.03% and 0.12%, with an average value of 0.07%. Additionally, the surface wettability was tested, and it was seen to display a wetting behavior (under 90◦) which provided surface energy up to 46.21 mJ.m−2.

Comprehensive analysis of arc methods of 3D printing of metal products: assessment of the efficiency and prospects of using TIG as a heat source

In recent years, additive technologies have become increasingly important for the production of parts with complex geometries, enabling the rapid and efficient creation of objects with different shapes and configurations in industrial sectors such as medicine, aerospace and construction. The focus of the study was the analysis of arc processes for additive manufacturing, particularly through non-consumable electrode welding in an inert gas environment (TIG) and its applications as a heat source. Modern methods of 3D printing metal products, such as SLM (Selective Laser Melting), EBM (Electron Beam Melting), and LMD (Laser Metal Deposition), allow the production of parts with good quality indicators: accuracy, surface roughness, mechanical properties, and others. However, these methods are expensive due to the technological complexity of the equipment, and a weakness of these methods is their low productivity compared to arc methods. The results presented in this article show that the productivity of arc methods in additive manufacturing is several times higher than that of SLM, EBM, and LMD, and arc methods are more cost-effective due to lower equipment costs and reduced energy consumption. The article presents the schemes of arc methods of additive manufacturing. One of the promising directions in the development of hybrid technology, namely the use of the TIG heat source for sintering metal powders, offers an effective way to reduce the cost of additive manufacturing by replacing the laser as a heat source, while allowing the continued use of various types of metal powders, reinforcing materials, and metal-ceramic blends.

Roles of Modeling and Artificial Intelligence in LPBF Metal Print Defect Detection: Critical Review

The integration of LPBF printing technologies in various innovative applications relies on the resilience and reliability of parts and their quality. Reducing or eliminating the factors leading to defects in final parts is crucial to producing satisfactory high-quality parts. Extensive efforts have been made to understand the material properties and printing process parameters of LPBF-printed geometries that trigger defects. Studies of interest include the use of various sensing technologies, numerical modeling, and artificial intelligence (AI) to enable a better understanding of the phenomena under investigation. The primary objectives of this article are to introduce the reader to the most widely read published data on (1) the roles of numerical and analytical models in LPBF defect detection; (2) AI algorithms and models applicable to predict LPBF metal defects and causes; and (3) the integration of modeling, AI, and sensing technology, which is commonly used in material characterization and has been proven efficient and applicable to LPBF metal part defect detection over extended periods.

Orthogonal cutting of 3D printed multi-material workpiece: numerical investigation of machining forces, stress, and temperature distribution

AbstractWith the development of 3D metal printers for rapid prototyping and industrial component production, heightened attention was directed towards post-processing operations for achieving precise surface quality and geometrical tolerances for these components. This paper investigated the orthogonal cutting of multi-material 3D printed workpieces using a coated cutting tool through finite element simulation. The workpieces featured different horizontal and vertical arrangements of layers composed of aluminum 7075-T6 alloy (Al), stainless steel 316 low alloy (SS), and Ti6Al4V alloy (Ti). The study explored the impacts of multi-material composition, coating thickness, and the rake angle of the cutting tool on machining forces, stress distribution, temperature distribution, and chip formation geometry. The results revealed a bimodal chip morphology in the machining process of horizontally arranged SS layers combined with other alloys. The SS layer resulted in a relatively uniform chip formation, while layers with two other materials exhibited a serrated chip formation. In contrast, a discontinuous chip formed when combining Al and Ti materials, as well as in the horizontally arranged layers made of Al, SS, and Ti alloys. The cutting force increased by 2.26 times when cutting workpieces with the horizontal arrangement of SS and Al layers compared to those with a single Al material. For the horizontal and vertical arrangement of layers made of Al and SS, von Mises stress values over the edge of the coated cutting tool significantly increased where the tool contacted the SS layer. Additionally, the horizontal arrangement of layers made of Al and SS materials caused the coated cutting tool to exhibit an extensive temperature distribution, with the maximum recorded temperature reaching 1448 °K. Increasing coating thickness led to a decrease in maximum principal stress at the surface of the tool and a rise in temperature at the cutting edge of the insert.

Mass reduction method for topology optimisation of a Ti6Al4V part for additive manufacturing

Abstract Additive manufacturing and topology optimization provide new possibilities to produce complex parts. They can be used separately but with joint applications as a mutually reinforcing solution in component development tasks. The results obtained using the design software can be refined even further depending on the specific goal set. This paper deals with mass reduction with stiffness-based topology optimization of a structural component. The effect of different design spaces, load cases, and design parameters were examined. Then, the new part was validated with FEA simulation. After the validation, the part was prepared for 3D metal printing. Based on the research results, we present a methodology that can be used as a solution considering the software’s limitations and the development of the specific component. Applying the methodology developed in the research makes it possible to achieve mass minimization on other parts with a similar method.

The challenges of 3D metal printing and the machinability characteristics of additively produced materials: a review of hybrid machining

Abstract Recently, 3D metal printing technologies are rapidly spreading. The various types of additive manufacturing (powder bed fusion, directed energy deposition, binder jetting, and sheet lamination) use very different approaches to produce materials/geometries. The material properties (e.g. porosity/density, strength, surface roughness, hardness) of additively manufactured materials differ from the traditional ones and strongly depend on the applied 3D printing parameters. Therefore, a crucial research direction is how the parameters affect the material properties. Currently, 3D metal printing technologies have limitations in the achievable geometrical accuracy and surface roughness. Therefore, they can rarely be used for part production without further machining. For high-quality requirements, an additional subtractive machining procedure is usually required. Consequently, another intensively researched topic is the machinability of 3D metal printed materials. The industry is increasingly demanding to integrate different manufacturing processes (additive and subtractive technologies) into one machine. These hybrid machines have the advantage that they can produce high-quality parts in one step.

Iterative printing of bulk metal and polymer for additive manufacturing of multi-layer electronic circuits

In pursuing advancing additive manufacturing (AM) techniques for 3D objects, this study combines AM techniques for bulk metal and polymer on a single platform for one-stop printing of multilayer 3D electronic circuits with two novel aspects. The first innovation involves the embedded integration of electronic circuits by printing low-resistance electrical traces from bulk metal into polymer channels. Cross-section grinding results reveal (92 ± 5)% occupancy of electrically conductive traces in polymer channels despite the different thermal properties of the two materials. The second aspect encompasses the possibility of printing vertical bulk metal vias up to 10 mm in height with the potential for expansion, interconnecting electrically conductive traces embedded in different layers of the 3D object. The work provides comprehensive 3D printing design guidelines for successfully integrating fully embedded electrically conductive traces and the interconnecting vertical bulk metal vias. A smooth and continuous workflow is also introduced, enabling a single-run print of functional multilayer embedded 3D electronics. The design rules and the workflow facilitate the iterative printing of two distinct materials, each defined by unique printing temperatures and techniques. Observations indicate that conductive traces using molten metal microdroplets show a 12-fold reduction in resistance compared to nanoparticle ink-based methods, meaning this technique greatly complements multi-material additive manufacturing (MM-AM). The work presents insights into the behavior of molten metal microdroplets on a polymer substrate when printed through the MM-AM process. It explores their characteristics in two scenarios: When they are deposited side-by-side to form conductive traces and when they are deposited out-of-plane to create vertical bulk metal vias. The innovative application of MM-AM to produce multilayer embedded 3D electronics with bulk metal and polymer demonstrates significant potential for realizing the fabrication of free-form 3D electronics.

Selective Laser Melting: A Novel Method for Surface Roughness Analysis

The present study introduces a novel approach to analyse the surface roughness of metal parts made by 3D selective laser melting (SLM). This technology, known for its ability to efficiently produce functional prototypes and limited-run series, is particularly effective when surface conditions directly meet usage requir ements. Thus, the suitability of surfaces is a critical factor, emphasizing the importance of new methods for predicting their quality. Here fractal geometry and network theory are integrated to delve into the complexities of SLM-produced surfaces, while machine learning and pattern recognition concepts are employed to evaluate the surface roughness. Specifically, genetic programming, artificial neural networks, support vector machine, random forest, k-nearest neighbors are compared in terms of accuracy demonstrating that only the first method provided valid estimation due to the presence of very little training data. Experimental work with EOS Maraging Steel MS1 and an EOS M 290 3D printer validates the method’s practicality and effectiveness. Then, the research offers a fresh perspective in surface analysis and has significant implications for quality control in additive manufacturing, potentially enhancing the precision and efficiency of 3D metal printing.

3D Printing of Metals with sub-10µm Resolution.

The ability to manufacture 3D metallic architectures with microscale resolution is greatly pursued because of their diverse applications in microelectromechanical systems (MEMS) including microelectronics, mechanical metamaterials, and biomedical devices. However, the well-developed photolithography and emerging metal additive manufacturing technologies have limited abilities in manufacturing micro-scaled metallic structures with freeform 3D geometries. Here, for the first time, the high-fidelity fabrication of arbitrary metallic motifs with sub-10µm resolution is achieved by employing an embedded-writing embedded-sintering (EWES) process. A paraffin wax-based supporting matrix with high thermal stability is developed, which permits the printed silver nanoparticle ink to be pre-sintered at 175°C to form metallic green bodies. Via carefully regulating the matrix components, the printing resolution is tuned down to ≈7µm. The green bodies are then embedded in a supporting salt bath and further sintered to realize freeform 3D silver motifs with great structure fidelity. 3D printing of various micro-scaled silver architectures is demonstrated such as micro-spring arrays, BCC lattices, horn antenna, and rotatable windmills. This method can be extended to the high-fidelity 3D printing of other metals and metal oxides which require high-temperature sintering, providing the pathways toward the design and fabrication of 3D MEMS with complex geometries and functions.

High-performance deep learning segmentation for non-destructive testing of X-ray tomography

For non-destructive testing (NDT) with X-ray computed tomography (XCT), the complex morphological segmentation of homogeneous defects is impossible for traditional threshold-based segmentation algorithm, due to their same absorbances. A variety of defect segmentation using convolutional neural networks (CNNs) has been suitable for such problems, and its accuracy is determined by image quality and comprehensiveness of training set. To achieve a high-performance measurement for quantitative defect evaluation, a modified U-Net-based segmentation model of XCT was proposed suitable for defects with various image quality resulting from different experimental efficiency. The dataset consisting of 24 subsets was acquired from the condition-varying measurements of aluminum alloy samples produced by laser 3D metal printing additive manufacturing. The structure and distribution of segmented pore and crack defects were accurately visualized by our model. Compared with traditional and main CNNs-based segmentation methods, our model exhibited a better recognition accuracy for pores and cracks, the Mean Intersection over Union and Pixel accuracy metrics reaching to 84.83 % and 98.87 % respectively. Practically, the option of efficiency or accuracy priority was quantitatively determined to carry out such a high-performance defect-related NDT. The proposed XCT-based segmentation mode has a great potential in fields of engineering, material science, biomedicine.

Free-space direct nanoscale 3D printing of metals and alloys enabled by two-photon decomposition and ultrafast optical trapping.

Nanoscale three-dimensional (3D) printing of metals and alloys has faced challenges in speed, miniaturization and deficiency in material properties. Traditional nanomanufacturing relies on lithographic methods with material constraints, limited resolution and slow layer-by-layer processing. This work introduces polymer-free techniques using two-photon decomposition and optical force trapping for free-space direct 3D printing of metals, metal oxides and multimetallic alloys with resolutions beyond optical limits. This method involves the two-photon decomposition of metal atoms from precursors, rapid assembly into nanoclusters via optical forces and ultrafast laser sintering, yielding dense, smooth nanostructures. Enhanced near-field optical forces from laser-induced localized surface plasmon resonance facilitate nanocluster aggregation. Our approach eliminates the need for organic materials, layer-by-layer printing and complex post-processing. Printed Mo nanowires show an excellent mechanical performance, closely resembling the behaviour of single crystals, while Mo-Co-W alloy nanowires outperform Mo nanowires. This innovation promises the customizable 3D nanoprinting of high-quality metals and metal oxides, impacting nanoelectronics, nanorobotics and advanced chip manufacturing.

Thermal Property Estimation of Thin-Layered Structures by Means of Thermoreflectance Measurement and Network Identification by Deconvolution Algorithm

Abstract Laser-induced forward transfer (LIFT) is a powerful tool for micro and nanoscale digital printing of metals for electronic packaging. In the metal LIFT process, the donor thin metal film is propelled to the receiving substrate and deposited on it. Morphology of the deposited metal varies with the thermodynamic responses of the donor thin film during and after the laser heating. Thus, the thermophysical properties of the multilayered donor sample are important to predict the LIFT process accurately. Here, we investigated thermophysical properties of a 100 nm-thick gold coated on 0.5 mm-thick sapphire and silicon substrates by means of the nanosecond time-domain thermoreflectance (ns-TDTR) analyzed by the network identification by deconvolution (NID) algorithm, which does not require numerical simulation or analytical solution. The NID algorithm enabled us to extract the thermal time constants of the sample from the nanosecond thermal decay of the sample surface. Furthermore, the cumulative and differential structure functions allowed us to investigate the heat flow path, giving the interfacial thermal resistance and the thermal conductivity of the substrate. After calibration of the NID algorithm using the thermal conductivity of the sapphire, the thermal conductivity of the silicon was determined to be 107–151 W/(m K), which is in good agreement with the widely accepted range of 110–148 W/(m K). Our study shows the feasibility of the structure function obtained from the single-shot TDTR experiments for thermal property estimation in laser processing and electronics packaging applications.