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In this study, crack-free TiC/Ti composites with TiC content ranging from 0 to 15 wt.% were successfully fabricated using Direct Energy Deposition with a dual-feeder system that concomitantly delivered different amounts of both constituents into a high-power laser beam. The samples were investigated to evaluate the morphologies and distribution behavior of TiC. The microhardness values of the samples obtained under optimal processing conditions increased from 192 ± 5.3 HV0.2 (pure Ti) to 300 ± 14.2 HV0.2 (Ti + wt.% 15 TiC). Also, TiC has a significant impact on the Ti matrix, increasing the strength of TMCs up to 725 ± 5.4 MPa, while the elongation drastically decreased to 0.62 ± 0.04%. The wear rate is not proportionally affected by the rise content of TiC reinforcement; the hypoeutectic region of TMCs exhibited a wear rate of 2.45 mm3/N·m (Ti + wt.% 3 TiC) and a friction coefficient of 0.48 compared to the ones from the hypereutectic region, which measured a wear rate of 3.02 mm3/N·m (Ti + wt.% 15 TiC) and a friction coefficient of 0.63. The improved values of mechanical properties in the case of TMCs as compared to pure Ti are provided due to the solid solution strengthening of carbon and the fine grain strengthening. This work outlines a method for changing TiC morphologies to improve the hardness and tensile strength of TMCs fabricated starting from micro-scale powder. [ABSTRACT FROM AUTHOR]

This document is an editorial from the journal "Crystals" that provides an overview of recent developments in additive manufacturing (AM) and highlights the studies featured in a special issue of the journal. The studies cover various aspects of AM, including laser additive manufacturing, electrodeposition, and fused filament fabrication, and explore innovations in material properties, microstructural control, and overall performance. The editorial also identifies existing knowledge gaps in AM and suggests future research directions, such as multi-material AM techniques, advanced simulation and modeling tools, scalability, sustainability, and long-term durability and performance studies. The document emphasizes the importance of continued research in these areas to fully realize the potential of AM and drive industrial innovation. [Extracted from the article]

Carbon thin films of 50-100 nm thickness were synthesized by Pulsed Laser Deposition in vacuum at different laser fluences from 2 to 6 J/cm2. The deposited films were characterized by Raman spectroscopy for compositional assessment, scanning electron microscopy for morphology/thickness evaluations, and X-ray reflectivity for density, thickness, and roughness determinations. The films were ~100 nm thin, smooth, droplet-free, made of a-C:H type of diamond-like carbon. The mechanical properties of synthesized films were studied by nanoindentation and adhesion tests. The films that were obtained at low laser fluences (2, 3 J/cm2) had better mechanical properties as compared to those synthesized at higher fluences. The mean values of hardness were around 20 GPa, while the friction coefficient was 0.06. The deposition conditions of carbon thin films that displayed the best mechanical properties were further used to coat commercial drills. Both uncoated and coated drills were tested on plates that were made of three types of steel: Stainless steel 304, general use AISI 572 Gr 65 steel (OL60), and AISI D3 tool steel (C120). All of the drill edges and tips were studied by optical and scanning electron microscopes. The coated samples were clearly found to be more resistant, and displayed less morphological defects than their uncoated counterparts when drilling stainless steel and OL60 plates. In the case of C120 steel, carbon coatings failed because of the high friction between drill and the metal plate resulting in tip edges blunting that occurred during processing. [ABSTRACT FROM AUTHOR]

We report on a feedback mechanism for rapid identification of optimal laser parameters during welding of AlMg5 coupons using real-time monitoring by high-speed imaging. The purpose was to constrain the liquid movement in the groove in order to obtain pore-free welds in this otherwise difficult-to-weld alloy. High-speed imaging of the welding process via an optical microscope allowed for recording at millimeter level, providing new information on liquid-metal dynamics during laser irradiation as well as plausible explanations for spatter occurrence and pores formation. The pore formation and especially the position of these pores had to be controlled in order to weld 3 mm thick samples. By tuning both laser power and pulse duration, pores were aligned on a single line, at the bottom of the weld. A laser pass of reduced power on that side was then sufficient for removing all pores and providing a suitable weld. [ABSTRACT FROM AUTHOR]

We report a study on the biocompatibility vs. thickness in the case of titanium nitride (TiN) films synthesized on 410 medical grade stainless steel substrates by pulsed laser deposition. The films were grown in a nitrogen atmosphere, and their in vitro cytotoxicity was assessed according to ISO 10993-5 [1]. Extensive physical-chemical analyses have been carried out on the deposited structures with various thicknesses in order to explain the differences in biological behavior: profilometry, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction and surface energy measurements. XPS revealed the presence of titanium oxynitride beside TiN in amounts that vary with the film thickness. The cytocompatibility of films seems to be influenced by their TiN surface content. The thinner films seem to be more suitable for medical applications, due to the combined high values of bonding strength and superior cytocompatibility. [ABSTRACT FROM AUTHOR]

Hard carbon thin films were synthesized on Si (100) and quartz substrates by the Pulsed Laser Deposition (PLD) technique in vacuum or methane ambient to study their suitability for applications requiring high mechanical resistance. The deposited films' surface morphology was investigated by scanning electron microscopy, crystalline status by X-ray diffraction, packing and density by X-ray reflectivity, chemical bonding by Raman and X-ray photoelectron spectroscopy, adherence by "pull-out" measurements and mechanical properties by nanoindentation tests. Films synthesized in vacuum were a-C DLC type, while films synthesized in methane were categorized as a-C:H. The majority of PLD films consisted of two layers: one low density layer towards the surface and a higher density layer in contact with the substrate. The deposition gas pressure played a crucial role on films thickness, component layers thickness ratio, structure and mechanical properties. The films were smooth, amorphous and composed of a mixture of sp3-sp2 carbon, with sp3 content ranging between 50% and 90%. The thickness and density of the two constituent layers of a film directly determined its mechanical properties. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present the current status on animal-origin hydroxyapatite (HA) coatings synthesized by Pulsed Laser Deposition (PLD) technique for medical implant applications. PLD as a thin film synthesis method, although limited in terms of surface covered area, still gathers interest among researchers due to its advantages such as stoichiometric transfer, thickness control, film adherence, and relatively simple experimental set-up. While animal-origin HA synthesized by bacteria or extracted from animal bones, eggshells, and clams was tested in the form of thin films or scaffolds as a bioactive agent before, the reported results on PLD coatings from HA materials extracted from natural sources were not gathered and compared until the present study. Since natural apatite contains trace elements and new functional groups, such as CO32− and HPO42− in its complex molecules, physical-chemical results on the transfer of animal-origin HA by PLD are extremely interesting due to the stoichiometric transfer possibilities of this technique. The points of interest of this paper are the origin of HA from various sustainable resources, the extraction methods employed, the supplemental functional groups, and ions present in animal-origin HA targets and coatings as compared to synthetic HA, the coatings' morphology function of the type of HA, and the structure and crystalline status after deposition (where properties were superior to synthetic HA), and the influence of various dopants on these properties. The most interesting studies published in the last decade in scientific literature were compared and morphological, elemental, structural, and mechanical data were compiled and interpreted. The biological response of different types of animal-origin apatites on a variety of cell types was qualitatively assessed by comparing MTS assay data of various studies, where the testing conditions were possible. Antibacterial and antifungal activity of some doped animal-origin HA coatings was also discussed. [ABSTRACT FROM AUTHOR]