Bioinspired and Multifunctional Tribological Materials for Sliding, Erosive, Machining, and Energy-Absorbing Conditions: A Review.

Friction, wear, and the consequent energy dissipation pose significant challenges in systems with moving components, spanning various domains, including nanoelectromechanical systems (NEMS/MEMS) and bio-MEMS (microrobots), hip prostheses (biomaterials), offshore wind and hydro turbines, space vehicles, solar mirrors for photovoltaics, triboelectric generators, etc. Nature-inspired bionic surfaces offer valuable examples of effective texturing strategies, encompassing various geometric and topological approaches tailored to mitigate frictional effects and related functionalities in various scenarios. By employing biomimetic surface modifications, for example, roughness tailoring, multifunctionality of the system can be generated to efficiently reduce friction and wear, enhance load-bearing capacity, improve self-adaptiveness in different environments, improve chemical interactions, facilitate biological interactions, etc.

Optimal mechanical properties of Hydroxyapatite gradient Voronoi porous scaffolds for bone applications - A numerical study.

Irregular Voronoi-based lattice (IVL) structures in tissue engineering (TE) have significant potential for bone regeneration. These scaffolds can mimic natural human bone interconnectivity by gradually altering strut thickness (ST) and seed point space (PS), which affects both mechanical and biological characteristics. This paper investigates the impact of design parameters, ST and PS, on Hydroxyapatite (HA) ILV structures' mechanical properties (elastic modulus (E) and maximum compressive strength (MCS)) and geometrical characteristics (pore number, size, and distribution, surface area (SA), and surface area-to-volume ratio (SA/VR)).

Cost-effective screen printing approach for Ce/Nd-doped ZnAlO films: tuning crystallinity induced by the substrate.

Near-infrared (NIR) emitting phosphors are currently receiving considerable attention owing to their high demand in various applications, such as light detection and ranging (LiDAR), short-range communications, security, biosensing and night vision lighting applications. The miniaturization of photonic components demands the integration of thin films into exploitable devices. In this context, NIR emitting ZnAlO:Ce/Nd films of hundreds of nanometer thickness are synthesized using a scalable and cost-efficient approach to screen printing.

Development of Yttrium-Doped BaTiO for Next-Generation Multilayer Ceramic Capacitors.

The use of electronic devices that incorporate multilayer ceramic capacitors (MLCCs) is on the rise, requiring materials with good electrical properties and a narrow band gap. This study synthesized yttrium-substituted barium titanate (Ba Y TiO, BYT) using a sol-gel process at 950 °C with varying concentrations of yttrium (0 ≤ ≤ 0.3).

Functionality and Activity of Sol-Gel-Prepared Co and Fe co-Doped Lead-Free BTO for Thermo-Optical Applications.

The BTO, BFTC, and BCTF compounds were synthesized by the sol-gel method. The XRD study revealed the formation of single-phase tetragonal perovskite structures with the space group (P4mm). The crystalline parameters were studied as a function of Fe and Co contents and occupation of Ba and/or Ti sites by Fe and Co in the BTO lattice.

Biomimetic design of implants for long bone critical-sized defects.

This computational study addresses new biomimetic load-bearing implants designed to treat long bone critical-sized defects in a proximal diaphysis region. The design encompasses two strategies: a Haversian bone-mimicking approach for cortical bone and lattices based on triply periodic minimal surfaces (TPMS) for trabecular bone. Compression tests are modeled computationally via a non-linear finite element analysis with Ti6Al4V alloy as a base material.

Deep-Ultraviolet Emitter: Rare-Earth-Free ZnAlO Nanofibers via a Simple Wet Chemical Route.

Deep-UV (180-280 nm) phosphors have attracted tremendous interest in tri-band-based white light-emitting diode (LED) technology, bio- and photochemistry, as well as various medical fields. However, the application of many UV-emitting materials has been hindered due to their poor thermal or chemical stability, complex synthesis, and environmental harmfulness. A particular concern is posed by the utilization of rare earths affected by rising price and depletion of natural resources.

PCL/Si-Doped Multi-Phase Calcium Phosphate Scaffolds Derived from Cuttlefish Bone.

Increasing attention is focused on developing biomaterials as temporary scaffolds that provide a specific environment and microstructure for bone tissue regeneration. The aim of the present work was to synthesize silicon-doped biomimetic multi-phase composite scaffolds based on bioactive inorganic phases and biocompatible polymers (poly(ε-caprolactone), PCL) using simple and inexpensive methods. Porous multi-phase composite scaffolds from cuttlefish bone were synthesized using a hydrothermal method and were further impregnated with (3-aminopropyl)triethoxysilane 1-4 times, heat-treated (1000 °C) and coated with PCL.

Laser Powder-Bed Fusion of Ceramic Particulate Reinforced Aluminum Alloys: A Review.

Aluminum (Al) and its alloys are the second most used materials spanning industrial applications in automotive, aircraft and aerospace industries. To comply with the industrial demand for high-performance aluminum alloys with superb mechanical properties, one promising approach is reinforcement with ceramic particulates. Laser powder-bed fusion (LPBF) of Al alloy powders provides vast freedom in design and allows fabrication of aluminum matrix composites with significant grain refinement and textureless microstructure.

Solid Lubrication at High-Temperatures-A Review.

Understanding the complex nature of wear behavior of materials at high-temperature is of fundamental importance for several engineering applications, including metal processing (cutting, forming, forging), internal combustion engines, etc. At high temperatures (up to 1000 °C), the material removal is majorly governed by the changes in surface reactivity and wear mechanisms. The use of lubricants to minimize friction, wear and flash temperature to prevent seizing is a common approach in engine tribology.

High-Temperature Wear Performance of hBN-Added Ni-W Composites Produced from Combustion-Synthesized Powders.

This work reports on the spark plasma sintering (SPS) of self-propagating high-temperature-synthesis (SHS)-derived Ni-W and Ni-W-2wt%hBN (4:1 molar ratio of metals) powders. The synthesis was carried out from a mixture of NiO and WO using Mg + C combined reducers through a thermo-kinetic coupling approach. Experiments performed in the thermodynamically optimal area demonstrated the high sensitivity of combustion parameters and product phase composition to the amount of reducers and hBN powder.

Rheological Properties of MWCNT-Doped Titanium-Oxo-Alkoxide Gel Materials for Fiber Drawing.

A strategy of doping by multi-walled carbon nanotubes (MWCNT) to enhance mechanical strength and the electrical conductivity of ceramic fibers has nowadays attracted a great deal of attention for a wide variety of industrial applications. This study focuses on the effect of MWCNTs on rheological properties of metal alkoxide precursors used for the preparation of nanoceramic metal oxide fibers. The rheological behavior of MWCNT-loaded titanium alkoxide sol precursors has been evaluated via an extensional rheometry method.

Sliding Wear Performance of AlCrN Coating on TiB/Ti Composites at High Temperatures.

The aim of the study was to investigate effect of Ti/TiB composite composition and manufacturing technology parameters on the tribological behaviour of AlCrN coating-composite system. The AlCrN coating was deposited by PVD (Physical Vapour Deposition) method. The composites were manufactured by spark plasma sintering (SPS) from three variants of powders mixtures: Ti with TiB, Ti6Al4V with TiB as well as Ti with B, using (five) different sintering temperatures.

Bioactive Ceramic Scaffolds for Bone Tissue Engineering by Powder Bed Selective Laser Processing: A Review.

The implementation of a powder bed selective laser processing (PBSLP) technique for bioactive ceramics, including selective laser sintering and melting (SLM/SLS), a laser powder bed fusion (L-PBF) approach is far more challenging when compared to its metallic and polymeric counterparts for the fabrication of biomedical materials. Direct PBSLP can offer binder-free fabrication of bioactive scaffolds without involving postprocessing techniques. This review explicitly focuses on the PBSLP technique for bioactive ceramics and encompasses a detailed overview of the PBSLP process and the general requirements and properties of the bioactive scaffolds for bone tissue growth.

SHS-Derived Powders by Reactions' Coupling as Primary Products for Subsequent Consolidation.

The capability of self-propagating high-temperature synthesis (SHS) to produce powders that are characterized by a high sintering ability, owing to high heating and cooling rates inherent to the exothermic reaction, is of a special interest for the industry. In particular, SHS-derived powders comprise a significant defect concentration in order to effectively enhance the mass transfer processes during the sintering, which allows for the successful consolidation of difficult-to-sinter materials at relatively low sintering temperatures. From this perspective, the design of precursors suitable for sintering, synthesis in a controlled temperature regime and the optimization of geometrical and structural parameters of SHS powders as a potential feedstock for the consolidation is of key importance.

Aluminate-Based Nanostructured Luminescent Materials: Design of Processing and Functional Properties.

Interest in luminescent materials has been continuously growing for several decades, looking for the development of new systems with optimized optical properties. Nowadays, research has been focused on the development of materials that satisfy specific market requirements in optoelectronics, radioelectronics, aerospace, bio-sensing, pigment applications, etc. Despite the fact that several efforts have made in the synthesis of organic luminescent materials, their poor stability under light exposure limits their use.

Thermal Transport and Thermoelectric Effect in Composites of Alumina and Graphene-Augmented Alumina Nanofibers.

The remarkable tunability of 2D carbon structures combined with their non-toxicity renders them interesting candidates for thermoelectric applications. Despite some limitations related to their high thermal conductivity and low Seebeck coefficients, several other unique properties of the graphene-like structures could out-weight these weaknesses in some applications. In this study, hybrid structures of alumina ceramics and graphene encapsulated alumina nanofibers are processed by spark plasma sintering to exploit advantages of thermoelectric properties of graphene and high stiffness of alumina.

Functionally Graded Tunable Microwave Absorber with Graphene-Augmented Alumina Nanofibers.

Graphene is currently attracting attention for radiation absorption particularly at gigahertz and terahertz frequencies. In this work, composites formed by graphene-augmented γ-AlO nanofibers embedded into the α-AlO matrix are tested for X-band absorption efficiency. Composites with 15 and 25 wt % of graphene fillers with shielding effectiveness (SE) of 38 and 45 dB, respectively, show a high reflection coefficient, while around the electrical percolation threshold (∼1 wt %), an SE of 10 dB was achieved.

Hot Sliding Wear of 88 wt.% TiB-Ti Composite from SHS Produced Powders.

Titanium alloys and composites are of great interest for a wide variety of industrial applications; however, most of them suffer from poor tribological performance, especially at elevated temperatures. In this study, spark plasma sintering was utilized to produce a fully dense and thermodynamically stable TiB-Ti composite with a high content of ceramic phase (88 wt.%) from self-propagating high temperature synthesized (SHS) powders of commercially available Ti and B.

Biomechanical Features of Graphene-Augmented Inorganic Nanofibrous Scaffolds and Their Physical Interaction with Viruses.

Nanofibrous substrates and scaffolds are widely being studied as matrices for 3D cell cultures, and disease models as well as for analytics and diagnostic purposes. These scaffolds usually comprise randomly oriented fibers. Much less common are nanofibrous scaffolds made of stiff inorganic materials such as alumina.

In Situ Mo(Si,Al)-Based Composite through Selective Laser Melting of a MoSi-30 wt.% AlSi10Mg Mixture.

The laser power bed fusion approach has been successfully employed to manufacture Mo(Si,Al)-based composites through the selective laser melting of a MoSi-30 wt.% AlSi10Mg mixture for high-temperature structural applications. Composites were manufactured by leveraging the in situ reaction of the components during printing at 150-300 W laser power, 500-1000 mm·s laser scanning speed, and 100-134 J·mm volumetric energy density.

Selective laser sintered bio-inspired silicon-wollastonite scaffolds for bone tissue engineering.

The scaffolds, which morphologically and physiologically mimic natural features of the bone, are of high demand for regenerative medicine. To address this challenge, we have developed innovative bioactive porous silicon- wollastonite substrates for bone tissue engineering. Additive manufacturing through selective laser melting approach has been exploited to fabricate scaffolds of different architecture.

Towards Blue Long-Lasting Luminescence of Eu/Nd-Doped Calcium-Aluminate Nanostructured Platelets via the Molten Salt Route.

Calcia-alumina binary compounds doped with rare earths and some transition metals cations show persistent luminescence from the visible to the infrared range. Specifically, the blue light can be obtained through the Eu activator center in a potential host, such as dodecacalcium hepta-aluminate (CaAlO) and monocalcium aluminate (CaAlO). By doping with Nd, the persistent luminescence can be substantially prolonged; for this reason, the Eu/Nd pair is a potential choice for developing long-lasting blue luminescence.

Graphene-Augmented Nanofiber Scaffolds Trigger Gene Expression Switching of Four Cancer Cell Types.

Three-dimensional (3D) customized scaffolds are anticipated to provide new frontiers in cell manipulation and advanced therapy methods. Here, we demonstrate the application of hybrid 3D porous scaffolds, representing networks of highly aligned self-assembled ceramic nanofibers, for culturing four types of cancer cells. Ultrahigh aspect ratio (∼10) of graphene augmented fibers of tailored nanotopology is shown as an alternative tool to substantially affect cancerous gene expression, eventually due to differences in local biomechanical features of the cell-matrix interactions.

Hybrid graphene-ceramic nanofibre network for spontaneous neural differentiation of stem cells.

A challenge in regenerative medicine is governed by the need to have control over the fate of stem cells that is regulated by the physical and chemical microenvironment and . The differentiation of the stem cells into specific lineages is commonly guided by use of specific culture media. For the first time, we demonstrate that human mesenchymal stem cells are capable of turning spontaneously towards neurogenic lineage when seeded on graphene-augmented, highly anisotropic ceramic nanofibres without special differentiation media, contrary to commonly thought requirement of 'soft' substrates for the same purpose.