Materials Science Forum Vol. 1167

Abstract: Advances in additive manufacturing have facilitated the production of intricate geometries and customized components with high precision. This research focuses on the optimization of 3D printing parameters for H13 tool steel and Inconel powder using the InssTek MX-Mini metal 3D printer. Key parameters, including scanning speed and powder granulation, are systematically varied to assess their influence on print quality, while the laser power remains constant. The objective is to identify the optimal parameter combinations that enhance dimensional accuracy, reduce porosity, and achieve the desired hardness and tolerance levels in the printed specimens. An extended experimental analysis, using Design of Experiments (DOE), is conducted to evaluate the mechanical properties and microstructural characteristics of the printed parts. The findings provide essential insights into the correlation between the printing parameters and the overall performance and reliability of H13 and Inconel components produced via additive manufacturing. This study offers a valuable framework for manufacturers seeking to optimize 3D printing processes for high-quality H13 and Inconel applications.

Abstract: This study explores the comparative analysis of mixed Aly718 (INCONEL) and H13 (tool steel metal) powders versus layered structures, both fabricated using the Directed Energy Deposition (DED) method in 3D printing. The investigation focuses on the macro and microstructural properties of 3D printed materials, the mechanical performance and potential applications of 3D printed materials.

Abstract: This paper presents the dynamic impact properties of selective laser melted AlSi10Mg alloy Charpy test specimens under different building orientations. The study aimed to investigate the influence of dynamic properties on the building orientation, considering a good homogeneity in the microstructure of the specimens. The Charpy impact specimens were printed under the same laser velocity, energy density and gas flow for all four orientations. The experimental investigation was carried out on an Impact testing machine using a pendulum to determine the main mechanical and dynamic properties of the alloy. The results showed that the printing orientation has an extremely important role in terms of impact energy.

Abstract: The Fused Filament Fabrication (FFF) process plays a crucial role in additive manufacturing (AM), therefore the optimization of certain parameters has a significant impact on the performance of 3D-printed components. In this study, the flexural behavior of Polylactic Acid (PLA) samples manufactured by FFF process is investigated. The influence of the infill density (ID) and the outer shell (OS) on the main physical and mechanical characteristics is studied in detail. The used IDs are 10%, 30%, 50%, 70%, and 90%, and the samples are manufactured with and without OS. All samples are manufactured with rectilinear infill pattern. The geometry of the samples and the experimental program follow the ISO 178 standard. The tests were performed at room temperature, with a test speed of 5 mm/min. The results indicate that main flexural properties (stiffness, strength, strain and fracture energy) are significantly superior in OS samples. Moreover, an increase in properties is obtained with the increase of the ID, regardless of the OS configuration. It was found that specimens without OS exhibited plastic deformation at all IDs, while those with OS demonstrated a quasi-brittle fracture pattern at IDs below 50%. Further analysis of the specific properties (specific strength and specific modulus) showed that an ID of 10% is optimal for 3D-printed structures with OS, while an ID of 90% is optimal for structures without OS. Thus, the importance of ID and OS parameters should not be neglected in the design of 3D printed structural components.

Abstract: 3D printing, commonly referred to as Additive Manufacturing (AM), enables the creation of both simple and complex three-dimensional objects. While AM encompasses a variety of manufacturing techniques, Fused Filament Fabrication (FFF), is the most prevalent method. FFF constructs 3D models layer-by-layer by extruding molten material in a specified pattern. This paper examines the fracture properties of components produced through the FFF process. To achieve this, Single Edge Notched Bend (SENB) specimens were fabricated from polylactic acid (PLA) thermoplastic material. Various printing parameters were explored, including infill density (40, 70, and 100%), infill patterns (grid, cubic, and concentric), and printing directions (0, 45, and 90°). Three-point bending (3PB) tests were conducted at room temperature (25 °C) in accordance with ASTM D5045-14 standards. The 3PB results indicate that the mode I fracture toughness values are significantly affected by the printing parameters examined, with the greatest variations linked to infill density, followed by infill pattern and printing direction. Additionally, the fracture mechanisms associated with SENB specimens produced under different parameters exhibited distinct characteristics.

Abstract: It is commonly believed that stainless steel cannot rust. However, this erroneous assumption is very often disproved in practice. Either the stainless steel is chosen for the manufacture of a piece of equipment working in the conditions where its corrosion resistance is no longer satisfactory, or, more often, the prescribed procedures for its protection are not followed during operation. The article gives examples where an incorrectly chosen disinfecting procedure for a food processing plant with a chlorine-based product caused pitting corrosion of ceiling panels and low-quality weld joints caused crevice corrosion of cold drinking water pipes in food processing plants.

Abstract: Dezincification is one of the specific types of corrosion attack on brass, very often on brass fittings in particular and is caused by the selective removal of zinc from brass, resulting in the formation of areas of spongy and brittle copper, and eventually leading to the total destruction of the component. The dezincification process is greatly facilitated by the presence of chlorine in the water and is also aided by poor aeration, low fluid circulation rates, higher temperatures and permeable deposits or coatings on the surface. This paper describes the analyses of two cases of dezincification of brass fittings, one appearing in hot water distribution pipeline and another in the nozzle of a lion's head shaped urban fountain. Although each of these components operated under different operating conditions, both were confirmed to have been damaged from this specific form of corrosion attack, often permeating the entire wall thickness.

Abstract: The o-phenanthroline-acyl-amino acid praseodymium complex (Pr [CH₃(CH₂)₄CO NHC H(CH₃)COO]₃ꞏphen) has been synthesized by an in-solution chemical reaction method using H(hex-ala) and 1,10-phenanthroline (phen) as ligands with a view to obtaining rare-earth organic complexes with good optical properties. The molecular structure of the praseodymium complex was determined using CHN elemental analysis, ¹³C NMR testing, and FT-IR spectroscopic testing. We also perform wide-angle and small-angle XRD diffraction wave analysis, polarization microscopy observation, light absorption testing, fluorescence spectral analysis, fluorescence lifetime analysis, and fluorescence variable temperature spectral analysis. The results indicate that the introduction of the auxiliary ligand phen results in a periodic short-range ordered structure and better crystallinity of Pr (hex-ala)₃ꞏphen, which exhibits strong optical anisotropy in the molten state. Good light absorption in the UV-visible region (200 nm - 420 nm), switching from ligand luminescence to a rare earth centered luminescence mechanism, and photoluminescence shifting from the blue to the green region. High fluorescence intensity in the visible and near-infrared regions, good fluorescence lifetime (0.76 µs), and good thermal stability in the range of 25 °C - 200 °C.

Abstract: The Mach–Zehnder interferometers (MZIs) on a silicon-on-insulator (SOI) platform were designed, fabricated, and experimentally characterized to evaluate their performance and extract waveguide parameters. Two unbalanced MZI devices with arm length differences of approximately 103 µm and 149 µm were implemented using 220 nm-high, 500 nm-wide strip waveguides. The devices were measured with a broadband optical source and an automated fiber–chip test setup to obtain their transmission spectra. Distinct interference fringes were observed, with free spectral ranges (FSRs) of about 5.37 nm and 3.72 nm for the two MZIs. From these spectral measurements, a waveguide group index of ∼4.19 was extracted for both devices, in excellent agreement with design simulations. The results confirm the accuracy of the design and demonstrate a straightforward method to calibrate waveguide index parameters using on-chip MZI structures. The presented MZIs achieved the expected performance, and this work provides a practical pathway for integrating and verifying interferometric components in silicon photonic circuits.