Binder Jetting and Infiltration of Metal Matrix Nanocomposites

The ability to produce a dense part of Al-based metal matrix nanocomposites using binder jetting followed by infiltration was investigated. A green density above 1.58 g/cm3 was determined to be necessary for spontaneous direct liquid infiltration to commence, and a press-compaction-assisted binder jetting process is needed to achieve this benchmark. A green density of 1.64±0.02 g/cm3 only resulted in a density of 1.65±0.03 g/cm3 by sintering at 1050 °C, which showed that densification is not possible with sintering alone. However, infiltration with Al-6061 produced specimens with a density of 2.74±0.04 g/cm3, which corresponded to a density improvement of 65%. Moreover, the infiltrated specimens had a low open porosity of 2.71±0.95% and a high hardness of 54 HRA. This study suggests that it is feasible to manufacture parts with complex shapes and superior mechanical properties using binder Jetting followed by infiltration.

N–Doped Porous Carbon Microspheres Derived from Yeast as Lithium Sulfide Hosts for Advanced Lithium-Ion Batteries

Lithium sulfide (Li2S) is considered to be the best potential substitution for sulfur-based cathodes due to its high theoretical specific capacity (1166 mAh g−1) and good compatibility with lithium metal-free anodes. However, the electrical insulation nature of Li2S and severe shuttling of lithium polysulfides lead to poor rate capability and cycling stability. Confining Li2S into polar conductive porous carbon is regarded as a promising strategy to solve these problems. In this work, N-doped porous carbon microspheres (NPCMs) derived from yeasts are designed and synthesized as a host to confine Li2S. Nano Li2S is successfully entered into the NPCMs’ pores to form N-doped porous carbon microspheres–Li2S composite (NPCMs–Li2S) by a typical liquid infiltration–evaporation method. NPCMs–Li2S not only delivers a high initial discharge capacity of 1077 mAh g−1 at 0.2 A g−1, but also displays good rate capability of 198 mAh g−1 at 5.0 A g−1 and long-term lifespan over 500 cycles. The improved cycling and high-rate performance of NPCMs–Li2S can be attributed to the NPCMs’ host, realizing the strong fixation of LiPSs and enhancing the electron and charge conduction of Li2S in NPCMs–Li2S cathodes.

A MULTIFUNCTIONAL AND RECONFIGURABLE MICROVASCULAR COMPOSITE

Fiber-reinforced polymer (FRP) composites, consisting of stiff/strong fibers embedded within a continuous matrix, are a lightweight structural platform supporting an array of modern applications. Bioinspired vascularization of fiber-composites can augment existing performance with dynamic functionalities via liquid infiltration of the internal micro-fluidic network. Some vascular-enabled capabilities include self-healing to repair delamination damage and active-cooling to prevent thermal degradation. While such attributes have been demonstrated in separate platforms, research investigations that combine functionalities within a single composite have been limited. Here we provide a recent study that highlights a promising pathway for achieving both multifunctional, and reconfigurable behavior in microvascular FRP composites. Specifically, we detail the ability to regulate temperature and modulate electromagnetic signature via fluid substitution within the same serpentine vasculature. Varying microchannel density alters both active-cooling efficiency by water circulation and polarized radio-frequency wave reflection by liquid metal infiltration. We control these bulk property pluralities by widespread vascularization, while minimizing impact on structural performance, and decode the effects of micro-vascular topology on macromechanical behavior. Our in-depth experimental and computational investigation provides a new benchmark for future design optimization and real-world translation of multifunctional and adaptive microvascular composites.

Antimicrobial Activity of MgB2 Powders Produced via Reactive Liquid Infiltration Method

We report for the first time on the antimicrobial activity of MgB2 powders produced via the Reactive Liquid Infiltration (RLI) process. Samples with MgB2 wt.% ranging from 2% to 99% were obtained and characterized, observing different levels of grain aggregation and of impurity phases. Their antimicrobial activity was tested against Staphylococcus aureus ATCC BAA 1026, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231. A general correlation is observed between the antibacterial activity and the MgB2 wt.%, but the sample microstructure also appears to be very important. RLI-MgB2 powders show better performances compared to commercial powders against microbial strains in the planktonic form, and their activity against biofilms is also very similar.

Research Progress on Preparation of SiC/Al for Electronic Packaging by Liquid Infiltration

High volume fraction SiC/Al composite material, with its excellent thermal properties and flexible preparation process, has been widely used in the field of electronic packaging. In the paprer, the development of SiC/Al materials for electronic packaging and their preparation methods are reviewed. The preparation processes for preparing SiC/Al by liquid infiltration are mainly introduced. The advantages and disadvantages of several important processes are analyzed. Finally, the development trend of SiC/Al for electronic packaging prepared by liquid infiltration is prospected.