Key Engineering Materials Vol. 978

Abstract: Additive manufacturing (AM) has transformed the production of complex geometries and customized components.Powder Bed Fusion with Laser Beam (PBF-LB) is a popular AM technique known for its ability to produce parts with excellent mechanical properties. This study focuses on the characterization of AlSi10Mg, an aluminum alloy widely used in aerospace and automotive industries, manufactured through PBF-LB. The influence of printing orientation on the mechanical properties of the material is investigated. Previous research has shown that PBF-LB manufactured AlSi10Mg can exhibit superior mechanical properties compared to traditional material, but the anisotropic nature of parts produced by PBF-LB can significantly affect their properties. Tensile, impact, and fatigue testing are conducted to assess the mechanical behavior of the printed AlSi10Mg specimens under different loading conditions. Microstructural analysis is performed using Field-Emission Scanning Electron Microscopy (FESEM) equipped with Electron Backscatter Diffraction (EBSD) to examine the microstructural features introduced during the PBF-LB process. The results provide insights into the mechanical behavior of AlSi10Mg produced through PBF-LB and contribute to the design and utilization of components manufactured using this AM technique.

Abstract: Plasma Arc Machining is a metal cutting where conductor metal such as sheets metal are cut with plasma arc. Problem in plasma arc machining is the result of cutting has burr which is quite large due to the heat, resulting the surface roughness on the workpiece. This research aim to minimize the surface roughness of the stainless steel plate uses a design of experiment method with full factorial design. In this research, there are three factors, that are torch height, cutting speed, and electric current. Each factor has three levels. By using full factorial design, the number of treatments are 3³=27 trials. The results of the research on data processing analysis of variance show that the most influential factor on surface roughness is cutting speed with contribution value of 90.76% followed by two other factors, that is height torch with contribution value of 2.42% and electric current with contribution value of 0.23% and contribution value of noise by 6.59%. Then based on data processing robust design the optimum combination of parameters is obtained by using setting 1 mm torch height, 2400 mm/min cutting speed, and 30 A electric current. Based on the confirmation experiments, experiments with optimum parameter combinations can reach a gap noise of 2.283 dB. Therefore, the design of experiment for determining parameter setting plasma arc machining can determine the optimum combination of parameters to minimize the surface roughness.

Abstract: In the last twenty years, the manufacturing of titanium and its alloys for commercial use continued to expand. As this material has several very advantageous properties, leading to increasing applications in various industries, it is seldom used in mechanical engineering applications due to its tribological properties, which are unfavourable. The nitriding process is one of the most frequently used thermochemical processes designed to enhance the surface characteristics of titanium alloys and improve tribological properties. Various types of nitriding for titanium are studied, such as ion nitriding, plasma nitriding, laser nitriding and gas nitriding. This article provides a comprehensive examination of research papers on different advancements through a systematic literature review conducted in the period 2017-2023 about titanium nitriding for its process parameters, characteristics and functionalities of the product, particularly emphasising their contributions in surface characteristics and mechanical properties. The review seeks to offer an understanding of how the predominant processing factors, specifically temperature and time, affect the microstructure and the creation of novel phases. This review suggests a challenge for future researchers to investigate mechanisms of microstructure evolution and its impact on mechanical properties in conditioned environments to microhardness and ability to withstand rusting of titanium and its alloys.

Abstract: This study explored the capability of sheet forming of JIS ADC12 aluminum alloy, commonly used for die casting. Despite the poor ductility of ADC12, we attempted to improve this property by applying rapid solidification through an unequal diameter twin roll caster. A strip with a thickness of 3.7 mm was cast at a speed of 20 m/min. The as-cast strip was then cold rolled and annealed to investigate its sheet-formability by deep drawing, three-roll bending and V-bending. This research also investigated the elements of ADC12 that contribute to poor ductility, with a focus on the impact of Mg, Cu, Fe, and Zn during the deep drawing process.

Abstract: Polyether ether ketone (PEEK) was printed via FDM using gyroid, line, and tri-hexagon infill patterns. Its effect on the mechanical behavior (tensile, flexural and compression) and the investigation of void percentage and orientation angles within the internal structure were studied. The line pattern showed the highest tensile strength at 55.46 MPa due to its internal structure with a higher number of deposited layers oriented along the direction of the stress enabling higher stress absorption, the laminate theory. The angular lines on both tri-hexagon and gyroid patterns provided disadvantage as supported by Timoshenko's theory where the internal structures acted like a beam which is prone to easier deformation. Line pattern also demonstrated the highest flexural strength at 103.67 MPa. The continuity of the pattern along the internal structure perpendicular to the direction of the force provided more effective transfer of stress. However, the highest compressive load was observed in gyroid pattern with 8,266.89 N. The redundancies in the internal structure design of gyroid pattern enabled more compression load absorption. Symmetry and internal angles in gyroid and tri-hexagon patterns allowed more compressive force which are more susceptible to fractures due to higher strains created. Lastly, void percentage showed line pattern with the lowest at 1.53%. In addition, the mean void orientation angle showed that the closer it is to 0^o, the weaker the part.

Abstract: Metal particle reinforcement plays an important role in the mechanical properties and printability of composite materials for FDM 3D-printing technology. PLA/Iron composite filament is widely used in many applications, such as magnetic and biomedical devices. This research aims to study the effect of iron particles on the printability and mechanical properties of PLA/Iron composite and compare it with another PLA composite of PLA/Stainless steel composite. The PLA/Iron (Fe) and PLA/Stainless steel (SS) composites were printed at different printing temperatures between 260-290 °C, printing speeds between 30-90 mm/s, and infill density of 100%. The max stress and elongation of printed PLA/Fe composite were higher than that of printed PLA/SS composite about 1.5 and 1.2 times. Moreover, the highest max stress of printed PLA/Fe composite specimens was 40.20 MPa at a printing temperature of 280 °C and printing speed of 60 mm/s. The optical microscope observed the homogeneous iron and stainless-steel particle distribution in PLA composite matrix and revealed the printed structure.

Abstract: Intensive global research is focused on advanced conductive materials to meet the electrical requirements of the telecommunication and power industry. The primary aim is to enhance electrical conductivity, resulting of improved current-carrying capacity and reduced energy loss during transmission. Copper and its composites are vital for power transmission and telecommunications due to their electrical, thermal, and mechanical qualities. However, current methods have drawbacks, such as compromised conductivity with alloying. Graphene, an extraordinary carbon allotrope with exceptional properties and high conductivity, offers promising opportunities for the development of superior materials; such as graphene-incorporated copper (GrCu). The incorporation of graphene into copper wire holds significant potential for various industries, including electronics, energy transmission, and telecommunications, where high conductivity and reliability are paramount. This study investigates GrCu characteristics through mixing graphene and copper, vacuum melting, fine copper wire drawing, and GrCu coaxial cable manufacturing. Graphene infusion enhances conductivity and mechanical properties, altering microstructure and inducing twin boundaries in copper grains. Graphene's disruption during wire drawing triggers this effect, elevating wire conductivity to 103.5% by IACS. GrCu coaxial cable demonstrates performance coherence with HFSS simulation up to 6 GHz. Graphene's inclusion offers tailored material properties. Ongoing research promises further optimization and advancement of graphene-copper composites, paving the way for novel technological progress.

Abstract: We have studied magneto-conductive and magnetic properties of La_1-xSr_xMnO₃ (LSMO) thin films on a-SiO₂ substrates produced by the metal organic decomposition (MOD) method. LSMO thin films for x = 0, 0.15 and 0.3 have been produced in a pure O₂ gas atmosphere. Although LaMnO₃ (LMO) single crystal is an antiferromagnetic insulator (AFI), LMO thin films we have produced show ferromagnetic metal (FM) properties for suitable heat treatment conditions. We consider that the excess of O^2- ions in LMO thin films produced in a pure O₂ gas atmosphere induces the strong hole self-doping into those and the LMO thin films change from AFI to FM. Whereas, the ordinary hole doping is also occurred in LSMO thin films at x > 0. Thus, the carrier doping for LSMO thin films at x > 0 is caused by the hole self-doping by O^2- ions and the ordinary hole doping by the replacement of La³⁺ ions by Sr²⁺ ones. To investigate the crystallographic and surface structures of the LSMO thin films, X-ray diffraction and SEM measurements have been performed, respectively. From the X-ray diffraction measurement, we have found that all LSMO thin films have perovskite structure and are polycrystalline. From the SEM measurement, we have seen that the LSMO thin films are formed of the aggregation of LSMO fine particles. Electrical resistivities (ERs) and magneto-resistivity (MR) ratios of the LSMO thin films have been measured on the temperature dependence (4K-300K). From MR ratio measurements, the coercive forces of them have been obtained as a function of temperature, and the Curie temperatures have been estimated from the temperature dependences of the coercive forces. We have discussed the origin of the magneto-conductive and magnetic properties of LSMO thin films.

Abstract: Anisotropic conductive film (ACF) is frequently used in the packaging manufacture for fine-pitch conductivity and interconnection, maintaining the electrical and mechanical connections between micro-electrodes. A key determinant of good conductivity is the deformation, fatigue, and breakage of conductive particles within the ACF packaging. This study aims to measure the resistance changes of specific conductive channels and observe the microscopic fatigue damage of compressed ACF conductive particles through the fabrication of Flex Printed Circuits (FPC) / Indium Tin Oxide-coated Polycarbonate (ITO-coated PC) specimens and the setup of bending experiments. The results show that the deformation, fatigue, and breakage of conductive particles will quantitatively affect electrical conductivity performance. By microscopically observing the breakage morphology of conductive particles before and after bending, it can be found that bending in the ACF packaging area further exacerbates the previously compressed and broken conductive particles, with cracks continuing to grow and shatter.