Advanced Engineering Materials最新文献

This research introduces a novel process for the direct metallization of the composite ceramic BN-AlN, a millable, high-temperature resistant material, using laser direct structuring (LDS). LDS is, for example, used for molded interconnect devices (MIDs), to integrate mechanical and electronic functions into a single 3D structure. Traditionally, MIDs have relied on polymers, but increasing thermal demands in electronics are shifting focus toward ceramic substrates like BN-AlN, which offer superior thermal stability and mechanical strength. Herein, electronic infrastructures are applied onto milled BN-AlN 3D components through a parameter study on laser activation and electroless copper deposition, followed by the development of a sequential copper–nickel–gold (CuNiAu) deposition process. The laser structuring reveals small grains of elemental aluminum on the surface, which directly catalyzes metal reduction in the electroless copper deposition. The duration and temperature of the copper electroplating process are found to influence the nuclei size and layer thickness. A palladium chloride treatment, as well as additional etching steps during the CuNiAu layer deposition, shows promising results. The metallized BN-AlN substrates are characterized for adhesion, contact reliability, resistivity, and thermal stability. The findings demonstrate the process's suitability for high-temperature applications, highlighting its potential for advancing electronic system integration.

Electrically Assisted Solidification

In article number 2401025, Hyun-Do Jung, Moon-Jo Kim, and co-workers present a method to refine primary Si in hypereutectic Al-Si alloys using electrically assisted solidification with phosphorus (P). Electric currents create flow in the melt, increasing cooling and nucleation, while phosphorus disperses AlP, enhancing silicon refinement.

Texture-Controlled Titanium Alloys

In article number 2400876, Jin Cui and co-workers explore the intricate relationship between processing techniques and the resulting texture and microstructure in α-Ti and β-Ti alloys, materials of choice in aerospace and biomedical sectors. This review delves into the effects of cold rolling, hot rolling, and annealing on the evolution of these properties. The study highlights the significant role texture plays in defining the mechanical properties, such as strength, fatigue resistance, and fracture toughness in α-Ti alloys, and the lower elastic modulus demanded by β-Ti alloys for biomedical applications.

Liquid Metal-Printed Semiconductors

In article number 2400029, Bangdeng Du, Jing Liu, and co-workers present emerging strategies for liquid-metal semiconductors manufacturing; these are expected to revolutionize electronic engineering and show potential for the use of liquid-metal printers to build semiconductors and functional devices as desired.

Ultrafast Lasers

In article number 2302262, Mindaugas Gedvilas, Andrius Žemaitis, and Paulius Gecˇys present a novel precision fabrication method for the creation of 3D cavities in metal. Fresnel lens molds designed for LED diffusers are created utilizing the state-of-the-art layer-by-layer laser milling technique and femtosecond burst irradiation. The findings open new opportunities for industrial applications of ultrafast lasers.

Electrochemically synthesized composites of vertically aligned titanium dioxide (TiO₂) nanotube arrays (TNAs) and cuprous oxide (Cu₂O) nanoparticles (CNPs) are used for studying gas phase CO₂ photoreduction behaviors. Anodized TNA surfaces with an average aperture size of 60 nm are decorated with CNPs using galvanostatic pulse electrodeposition. The nucleation and growth of CNPs are investigated with the help of cyclic voltammetry and potential-time transients. The number of CNPs and their distribution on TNA surfaces are widely altered by adjusting the ON/OFF time, the number of applied current pulse, and the bath temperature. After characterizing structural and physical properties of the prepared CNPs/TNAs samples, in situ observation of CO₂ photoreduction in gas phase over CNPs/TNAs is carried out in a high vacuum. The enhancement in CO₂ photoreduction over CNPs/TNAs samples is observed for the optimized size and the number of CNPs on TNAs. The reaction route of the same is ascertained from the reaction products. The experimental results indicate that the size of CNPs should be comparable to the average pore size of TNAs for promoting CO₂ photoreduction, and the relationship between CO₂ photoreduction and the structural properties of CNPs is further discussed.

Near-β titanium alloys are used as promising structural materials for aerospace, biomedical, and other advanced applications due to their excellent combination of high specific strength and superior corrosion resistance. Precise control of the microstructure and mechanical properties through thermomechanical processing and heat treatment is paramount for exploiting the full potential of these alloys. This review article provides a comprehensive and critical assessment of the state-of-the-art research on the microstructure evolution, deformation mechanisms, and oxidation behavior of near-β titanium alloys. Furthermore, the challenges and emerging opportunities in the development of near-β titanium alloys have also been identified, ranging from alloy design and processing optimization to multiscale characterization and integrated computational materials engineering. This review article provides a timely and comprehensive roadmap for the research and development of near-β titanium alloys, paving the way for unlocking their full potential in critical industries.

Herein, 3D chiral compression-twist metamaterials represent a novel class of materials capable of converting compression into twist. An isotactic compression-twist lattice cell (ICTLC), composed of two identical chiral compression-twist units, is investigated in this paper. By compactly arranging ICTLCs, a 3D chiral metamaterial with overall compression-twist deformation is achieved. The mechanical properties and deformation mechanisms of the 3D chiral metamaterial are analyzed. The twist angle and the equivalent stress-strain relationship of the ICTLC are derived based on the deformation of its inclined rods under compression. An analytical solution for the twist angle of the 3D chiral metamaterial under in-plane compression is also presented. Both experiments and numerical simulations are conducted to verify the compression-twist performance of the proposed 3D chiral metamaterial. Additionally, the effects of the geometric parameters and the number of the ICTLC on the mechanical behavior and twist performance of the 3D chiral metamaterial are also investigated. The results indicate that, with a constant ratio of longitudinal ICTLC layers to transverse ICTLC rows (and columns), the compressive strength of the metamaterial increases while maintaining efficient compression-twisting deformation performance as the number of ICTLCs increases. These findings provide insights for the design of metamaterials with enhanced compression-twist coupling deformation.

Tumor-on-chip (ToC) is crucial to bridge the gap between traditional cell culture experiments and in vivo models, allowing to recreate an in vivo-like microenvironment in cancer research. ToC use microfluidics to provide fine-tune control over environmental factors, high-throughput screening, and reduce requirements of samples and reagents. However, creating these microfluidic devices requires skilled researchers and dedicated manufacturing equipment, making widespread adoption cumbersome and difficult. To address some bottlenecks and improve accessibility to ToC technology, innovative materials and fabrication processes are required. Polystyrene (PS) is a promising material for microfluidics due to its biocompatibility, affordability, and optical transparency. Herein, a fabrication process based on direct laser writing on thermosensitive PS, allowing the swift and economical crafting of devices with easy pattern alterations, is presented. For the first time, a device for cell culture fabricated only by PS is presented, allowing customizing and optimization for efficient cell culture approaches. These biochips support 2D and 3D cultures with comparable viability and proliferation kinetics to traditional 96-well plates. The data show that gene and protein silencing efficiencies remain consistent across both chip and plate-based cultures, either 2D culture or 3D spheroid format. Although simple, this approach might facilitate the use of customized chip-based cancer models.

In this study, the influence of cold-spray processing on the integration of 1D boron nitride nanotubes (BNNTs) into aluminum (Al) matrix composite deposits is delved into. Successful deposition of Al-BNNT composite is achieved by pre-spray dispersion of BNNTs in Al powder via wet mixing aided by ultrasonication. Pure Al powder deposition at 380 °C is limited by nozzle clogging, restricting the deposit thickness to 0.2 mm, while the presence of BNNTs enables longer spraying due to nozzle cleaning and damping by hard BNNTs, allowing thicker Al-BNNT deposits of about 2 mm. Microstructural analysis reveals severely deformed Al splats decorated with a uniformly distributed network of BNNTs at the intersplat boundaries, reducing the porosity from 8% to 4% and increasing the splat flattening by 40%. Tribological testing demonstrates resistance of BNNTs to normal force, resulting in a 21% improvement in coefficient of friction and a 65% reduction in wear volume in the Al-BNNT composite. Additionally, incorporating 3 vol.% BNNTs enhances the neutron radiation shielding by 35%. These improvements in the composites are attributed to reduced porosity and the inherent properties of BNNTs, such as high strength, the ability to produce tribofilm lubrication during dry sliding wear, and their high neutron absorption cross-sectional area.