Papers by Keyword: Magnesium

Abstract: The healing of bone defects is still challenging as therapies like autografts and allografts have limited benefits, especially in load-bearing positions. Bovine Hydroxyapatite (BHA) is a natural biological substance that can be used as a filler to replace damaged bones and overcome the low fracture toughness and brittleness of synthetic Hydroxyapatite (HA). This study presents the precipitation method of Magnesium (Mg)-doped Bovine Hydroxyapatite (Mg-BHA). FTIR analysis ensured the existence of phosphate (PO₄ ³), hydroxyl (OH) and carbonate (CO ^-2) groups of HA. After sintering, XRD analysis showed excellent stability in the BHA structure, represented by a slight change in Mg position. Vickers hardness showed a massive increment from ~4.6 GPa to ~7 GPa as the impurity rate increased. SEM analysis showed a denser microstructure with less porosity as the amount of Mg concentration increased. This research ensured that MgBHA could be potentially applied for medical applications due to the improvement in physical and mechanical properties of HA.

Abstract: An embedded system-based spin coating machine has been developed to grow thin films. Pure zinc oxide (ZnO) and magnesium-doped zinc oxide (ZnO: Mg) thin films with different doped samples have been prepared using the spin coating technique for LPG gas sensing application. The spin coating machine is fully controlled by a PIC microcontroller (PIC16f877A), which can drive a driver circuit to drive a spinning motor, and ZnO: Mg thin films are deposited using this machine. XRD results indicated that the movie has a hexagonal wurtzite structure with a preferred orientation, and the crystallite size increases with the increasing doping concentration of Mg. The surface morphology investigation shows that grains are irregular in shape, and doping concentrations do not influence the surface morphology. From the TEM image, particle sizes observed ranged between 23 and 28 nm, with an average value of ~25.8 nm. The maximum visible average transmittance was 96% for an optimum Mg doping concentration of 10 wt% %. The investigated DC electrical conductivity of Mg-doped ZnO thin films shows enhanced electrical conductivity compared to pure ZnO, and the AC conductivity is decreased with increasing Mg doping concentrations from 5 to 10 wt%. The operation and sensing mechanism of Pure ZnO and ZnO: Mg thin films behind their impressive results has been studied in depth.

Abstract: This study investigates a hybrid manufacturing route combining heat-assisted Single Point Incremental Sheet Forming (SPIF) with Tungsten Inert Gas welding (TIG)-based material deposition for the local reinforcement of Mg–Zn–Zr (ZK61) alloy thin sheets. Flat and curved substrates extracted from SPIF-formed geometries were used to examine the influence of substrate thickness, forming temperature, and geometry on TIG deposition morphology and thermal distortion. The results indicate that heat input and substrate thickness strongly affect deposition morphology and dimensional stability, while SPIF sheet forming temperature influences the repeatability of the deposition process. In addition, deposition behavior exhibited limited sensitivity to substrate curvature for single depositions, whereas successive depositions resulted in increased thermal distortion due to cumulative residual stresses. Overall, this work identifies key process sensitivities and constraints associated with TIG deposition on SPIF-formed magnesium alloy sheets, providing a basis for the development of hybrid forming-deposition process chains for localized reinforcement applications.

Abstract: Optimizing the performance and reliability of welding techniques for dissimilar aluminum (Al) to titanium (Ti) is a promising way to establish new applications in aerospace industry. Due to structural weight reduction, lightweight materials can help to minimize fuel consumption and save emissions. Solid-state welding technologies allow short joining cycles and metallurgical changes, residual stresses and severe intermetallic compound formation can be reduced by limited thermal exposure. Besides temperature and plastic deformation, intimate contact plays an important role for diffusion. In this work, AlMgSi alloys with systematic variations of Mg and Si alloying elements, were welded to Ti6Al4V (Ti64) by refill Friction Stir Spot Welding. The focus lays on the effect of Ti64 sheet surface roughness, varied by different surface preparations. Additionally, the influence of the plunge depth, the distance between the tool and the Ti64 sheet surface is analyzed. It was found that a reduced tool to interface spacing has a beneficial influence on joint integrity. Grinding trenches allowed better bonding compared to the pit-like surface structure generated by sandblasting, which led to an increase in mechanical lap-shear properties. Knurling the grinded surfaces resulted in high standard deviation, as most likely not the whole interface area was bonded. However, the partially outstanding properties showed that a beneficial effect can be expected due to mechanical interlocking mechanisms, when sufficient diffusion is ensured.

Abstract: The use of out-of-furnace desulphurization of cast iron and various dispersed desulfurizing reagents is due to the desire to ensure the most complete removal of cast iron sulfur in the shortest period of time. The actual results of the industrial application of out-of-furnace desulfurization indicate that the practical results and application rates in a number of cases are not stable enough and are far from possible and expected. The studies were carried out on calculated and "cold" transparent physical models. Magnesium, lime, and calcium carbide were evaluated as desulfurizing reagents. Based on the actual results of physical modeling and subsequent calculations, an improved expression was formulated for determining the length of a gas jet in a liquid (L_str ) - the depth of the jet immersion, depending on the parameters of injection through a submerged lance. The processes of interaction between gas and solid phases in the near-lance zone during ladle desulphurization have been studied. It is shown that during the injection desulfurization of cast iron, the gas component of the flow stops its directional movement in the melt for up to 80 mm (practically 50–60 mm), solid particles continue to move in the bubble and hit the surface of this cavity. To assess the further movement of the particle through the "gas cavity-melt" boundary, the depth of penetration of particles into liquid iron was calculated. The motion of a particle in a melt can be described by an equation that is arranged for the conditions of vertical motion of a particle from top to bottom with a given initial velocity up to the complete stop of the particle. Nomograms are given to determine the specified parameters. Recommendations are given on the parameters of injection of magnesium and ground lime.

Abstract: This study focuses on the development of magnesium-zinc (Mg-Zn) matrix alloys enriched with rare earth elements (RE), aiming to evaluate both their structural characteristics and in vitro biological responses. The designed alloys incorporated varying amounts of Zn, Nd, Ce, Gd, Zr, and Ca. Two specific EZ43 alloy compositions were synthesized using an induction-heated furnace under a protective gas atmosphere, differing in their Nd-to-Ce weight ratios (1:2 and 2:1). Following casting, the alloys were homogenized at 400 °C for 24 hours to eliminate dendritic structures and minimize elemental segregation. X-ray fluorescence (XRF) was employed to assess the chemical compositions, while scanning electron microscopy (SEM) provided detailed insight into microstructural features and potential intermetallic phases. Biocompatibility was evaluated through cytotoxicity and genotoxicity tests, conducted in accordance with internationally recognized standards to ensure reliability. Results indicated no genotoxic effects and demonstrated high cell viability up to 142% particularly in Nd-enriched samples. Statistical analysis revealed significant differences in biological behavior between the Nd-rich and Ce-rich alloys, with Nd contributing positively to cellular responses. These findings emphasize the importance of RE composition in influencing biocompatibility and suggest that Nd-enriched Mg-Zn alloys hold strong promise for biomedical applications requiring both structural integrity and favorable biological interaction.

Abstract: Optimizing the mechanical properties of aluminum to titanium welds is crucial to establish applications for dissimilar lightweight structures in the aerospace industry. In this context, solid-state welding technologies have proven effective in terms of short joining cycles, allowing the combination of cost-effective production and structural weight optimization. However, metallurgical effects between aluminum and titanium in the joint interface are still not completely understood due to differences in physical as well as chemical characteristics. In this study, aluminum alloy 6013 was welded to Ti6Al4V by refill Friction Stir Spot Wel ding, including systematic variations of Mg and Si alloying element content in the used AA6013 sheets. In total five different Al alloys were welded to the titanium to investigate the influence of Mg and Si during processing. Apart from the material selection, the weld strength is mainly influenced by the intermetallic compound thickness at the interface, which in turn primarily depends on the exposed temperature cycle. Consequently, major interest during this study was given on the temperature evolution, interfacial features and the global mechanical properties.

Abstract: The noise and vibrations generated by equipment and machinery during everyday life and industrial activities can affect both human and machine operations. Specifically, research aimed at suppressing vibrations and noise to enhance the energy efficiency of machinery is becoming increasingly active. In this study, magnesium was selected as the material for vibration damping. The detrimental effects of magnesium are improved by the addition of small amounts of Mn and Zn. A composite material was fabricated using magnesium, which has excellent vibration damping properties, and carbon steel (S45), which has superior mechanical properties. Magnesium alloys with Zn additions of 1, 3, and 5 wt.% were produced to enhance the corrosion resistance and strength of magnesium. Contact angle experiments were conducted to measure the wettability of the magnesium alloys. The contact angle was measured using the sessile drop method. The magnesium alloys showed a decreasing trend in contact angle with increasing zinc content. To explain the decrease in contact angle in Mg-Zn alloys, microstructure and compositional analyses were performed. First, Mg-Fe and Zn-Fe phase diagrams were investigated. The Mg-Fe system was found to contain no intermetallic compounds. In Zn-Fe interactions, Zn appears to form a metallic bond with Fe. The presence of the Γ phase at the interface between the magnesium alloy and S45 indicates that Zn has diffused from the magnesium alloy into both the magnesium alloy and S45. The Γ phase, considered a compound of Fe₃Zn₁₀, improves wettability between particles due to the formation of intermetallic compounds. Therefore, it was inferred that the wettability of the magnesium alloy improved. Additionally, improved wettability is expected to contribute to better adhesion processes and potentially increase interfacial shear strength.

Abstract: Ideal physical and mechanical properties and lightweight materials are the main requirements in today's transportation and automotive industries. This research aims to determine variations in Mg composition and sintering temperature of aluminum matrix composites using moulds with a powder metallurgy process on the properties and microstructure of the composite. Magnesium particles with a size of 250 μm were added to the Al-Cu-Mg-matrix at different volume ratios (1%, 1.5%). The mixture of Al, Mg, and reinforcement (Cu, ) powder was mixed at 1,500 rpm for 2 hours for homogeneous dispersion. The mixed powder is compacted at 200 MPa and sintered at different temperatures (500°C, 550°C, 600°C) and then allowed to cool slowly in the furnace. Composite character research was then done by testing density using the Archimedes principle, porosity, microhardness, wear rate, SEM characterization, quantitative analysis and EDS mapping. The optimal composite condition is characterized by a relative density of 57.45%, the lowest porosity ratio measured at 7.48%, a microhardness level of 52.1 HV and the lowest wear rate of 0.58 /m in the Al-Cu-Alumina composite with the addition of 1.5% Mg and sintered at a temperature of 600°C. This composite character is supported by the results of microstructure observations using SEM-EDS. The use of micro-in the Al-Cu-Mg composite supports the optimization of physical and mechanical characteristics as a composite worthy of being considered as the material of choice for components of transportation and automotive modes.

Abstract: Aluminum matrix composites (AMCs) reinforced with carbon nanotubes (CNTs) are widely developed nowadays because they have superior properties. One method of manufacturing AMCs is stir-squeeze casting. This study investigated the effect of magnesium addition on 1% wt CNT reinforcement. Aluminum matrix composites made using Aluminum 6063 reinforced with 1% wt CNT added magnesium with variations (0%, 2%, 4%, 6% wt) were made by a casting method which combines stir-casting at 350 Rpm for 2 minutes with squeeze-casting at a pressure of 10 Mpa for 75 seconds, cast on a metal mold heated at 450°C and an AMC casting temperature of 750°C . The results of CNT-reinforced AMC casting were studied for physical properties, namely porosity and density, mechanical properties, namely tensile strength and hardness, and microstructure characterization, namely OM and SEM. The results showed that adding magnesium can reduce porosity and increase density. The results of hardness testing also show that increasing Mg can increase hardness, and the highest hardness value is 48.8 HV at the addition of 6% Mg, with an increase of 74% from the raw material. The microstructure observation results show that adding Mg functions as a wetting agent, which causes CNTs to be evenly distributed and no accumulation occurs.