Multifunctional Quasi-Solid-State Zinc-Sulfur Battery.

The introduction of structural energy storage devices into emerging markets, such as electric vehicles, is predominately hindered by weak energy density, safety concerns, and immaturity of the field in materials. Herein, fabrication and testing of a freeze-resistant, multifunctional quasi-solid-state zinc-sulfur battery (ZnS) are reported. To this end, an electrostatic spray coating technique was used to deposit a thin layer of sulfur on the highly porous, unidirectional activated carbon nanofibers (A-CNFs) as a load-bearing cathode.

Development of a controlled-atmosphere, rapid-cooling cryogenic chamber for tribological and mechanical testing.

Mechanical testing of seals, bearing materials, and mechanisms in cryogenic environments is a rapidly growing field of research, as it promises improvements in equipment performance and reliability for applications such as space exploration, liquid hydrocarbon storage, and superconducting devices. Cooling of test equipment is usually performed within a well-insulated test chamber, via direct or indirect evaporation of liquid cryogen. State-of-the-art equipment is frequently insufficient for rigorous testing, being expensive and cumbersome, cooling slowly, struggling to replicate relevant environmental conditions, and/or failing to reach the temperature of the cryogen.

Impact of Ionic Liquid Additives and Inorganic Fullerene-Like Tungsten Disulfide on Friction and Wear under Aqueous Environments.

Aqueous lubricants are gaining attention due to significant advantages such as being environmentally friendly, tunable, and thermally stable. The oil and gas industry can use such additives to utilize in water-based fluids for applications where small sliding velocities and large lateral forces require enhanced lubrication. This investigation aims to compare the effects of two different additives: (i) inorganic fullerene-like tungsten disulfide (IF-WS) and (ii) an alkanolamine ionic liquid denoted as AA-IL.

Development of Fluorine-Free Tantalum Carbide MXene Hybrid Structure as a Biocompatible Material for Supercapacitor Electrodes.

The application of nontoxic 2D transition-metal carbides (MXenes) has recently gained ground in bioelectronics. In group-4 transition metals, tantalum possesses enhanced biological and physical properties compared to other MXene counterparts. However, the application of tantalum carbide for bioelectrodes has not yet been explored.

Enabling Selectively Tunable Mechanical Properties of Graphene Oxide/Silk Fibroin/Cellulose Nanocrystal Bionanofilms.

Enhancing and manipulating the mechanical properties of graphene oxide (GO)-based structures are challenging because the GO assembly is easily delaminated. We develop nacre-like bionanofilms whose in-plane mechanical properties can be manipulated through water vapor annealing without influencing their mechanical properties in the thickness direction. These bionanofilms are prepared from GO, silk fibroin (SF), and cellulose nanocrystals (CNCs) via a spin-assisted layer-by-layer assembly.

Effects of SiO content on the nanomechanical properties of CoCrPt-SiO granular films.

CoCrPt material is used for perpendicular magnetic recording media due to its high magneto-crystalline anisotropy that brings good thermal stability on the media. The addition of SiO between the CoCrPt grains offers benefits including lower noise and better thermal stability. It has been reported that the SiO content has strong effects on the media's recording performance such as coercivity, anisotropy and noise.

A microelectromechanical systems (MEMS) force-displacement transducer for sub-5 nm nanoindentation and adhesion measurements.

We present a highly sensitive force-displacement transducer capable of performing ultra-shallow nanoindentation and adhesion measurements. The transducer utilizes electrostatic actuation and capacitive sensing combined with microelectromechanical fabrication technologies. Air indentation experiments report a root-mean-square (RMS) force resolution of 1.

Fabrication and Deformation of 3D Multilayered Kirigami Microstructures.

Mechanically guided 3D microassembly with controlled compressive buckling represents a promising emerging route to 3D mesostructures in a broad range of advanced materials, including single-crystalline silicon (Si), of direct relevance to microelectronic devices. During practical applications, the assembled 3D mesostructures and microdevices usually undergo external mechanical loading such as out-of-plane compression, which can induce damage in or failure of the structures/devices. Here, the mechanical responses of a few mechanically assembled 3D kirigami mesostructures under flat-punch compression are studied through combined experiment and finite element analyses.

Fast Self-Healing of Polyelectrolyte Multilayer Nanocoating and Restoration of Super Oxygen Barrier.

A self-healable gas barrier nanocoating, which is fabricated by alternate deposition of polyethyleneimine (PEI) and polyacrylic acid (PAA) polyelectrolytes, is demonstrated in this study. This multilayer film, with high elastic modulus, high glass transition temperature, and small free volume, has been shown to be a super oxygen gas barrier. An 8-bilayer PEI/PAA multilayer assembly (≈700 nm thick) exhibits an oxygen transmission rate (OTR) undetectable to commercial instrumentation (<0.

Influence of Graphene Reduction and Polymer Cross-Linking on Improving the Interfacial Properties of Multilayer Thin Films.

Graphene is a versatile composite reinforcement candidate due to its strong mechanical, tunable electrical and optical properties, and chemical stability. However, one drawback is the weak interfacial bonding, which results in weak adhesion to substrates. This could be overcome by adding polymer layers to have stronger adherence to the substrate and between graphene sheets.

Nanomechanical Behavior of High Gas Barrier Multilayer Thin Films.

Nanoindentation and nanoscratch experiments were performed on thin multilayer films manufactured using the layer-by-layer (LbL) assembly technique. These films are known to exhibit high gas barrier, but little is known about their durability, which is an important feature for various packaging applications (e.g.

Bacteria repelling on highly-ordered alumina-nanopore structures.

Bacteria introduce diseases and infections to humans by their adherence to biomaterials, such as implants and surgical tools. Cell desorption is an effective step to reduce such damage. Here, we report mechanisms of bacteria desorption.

Dynamic adhesive force measurements under vertical and horizontal motions of interacting rough surfaces.

An instrument to measure dynamic adhesive forces between interacting rough surfaces has been developed. It consists of four parts, namely, main instrument body, vertical positioning system with both micrometer and nanometer positioning accuracies, horizontal positioning system with nanometer positioning accuracy, and custom-built high-resolution, and high dynamic bandwidth capacitive force transducer. The vertical piezoelectric actuator (PZT) controls the vertical (approaching and retracting) motion of the upper specimen, while the horizontal PZT controls the horizontal (reciprocal) motion of the lower specimen.

An improved meniscus surface model for contacting rough surfaces.

Based on the Extended-Maugis-Dugdale (EMD) elastic theory, a single asperity capillary meniscus model considering asperity deformation due to both contact and adhesive forces was developed. Specifically included in the single asperity meniscus model was the solid surface interaction inside the contact area. Subsequently, the single asperity model was coupled with a statistical roughness surface model to develop an improved meniscus surface model applicable to a wide-range of humidity levels and adhesion parameter values.

An elastic-plastic hybrid adhesion model for contacting rough surfaces in the presence of molecularly thin lubricant.

The study of adhesion has received considerable attention in recent years, partly due to advances in the design and fabrication of micro/nano devices. Many adhesion investigations are centered on single-spherical-contact models, which include the classic Johnson-Kendall-Roberts (JKR), improved Derjaguin-Muller-Toporov (IDMT), and Maugis-Dugdale (MD) models. Based on the IDMT single-asperity model, adhesive rough surface contact models have also been developed, which are valid for elastic and elastic-plastic contact conditions.

Adhesive transition from noncontacting to contacting elastic spheres: extension of the Maugis-Dugdale model.

In this paper, an adhesion model for spherical noncontact is proposed based on the Maugis-Dugdale (MD) adhesive contact model. The proposed noncontact model is combined with the MD contact model, thus providing a full range adhesion model with analytical transition from noncontacting to contacting asperity geometry. The proposed model is favorably compared with the full range improved DMT model for low surface energy values.

Adhesive contact based on the Lennard-Jones potential: a correction to the value of the equilibrium distance as used in the potential.

A Lennard-Jones type surface law is commonly used in adhesive contact modeling; however, one of its parameters, namely the equilibrium distance z0, is not well defined. In this paper, a self-consistent method is used to derive the Lennard-Jones surface law from the interatomic Lennard-Jones potential. The parameters of the surface law are directly related to the material lattice parameter and surface energy, and the equilibrium distance z0 values are obtained for various materials.

Measuring mechanical properties of fine-wire cross-sections used in medical devices.

In this study, it was demonstrated that the nanoindentation technique can be used to measure the elastic modulus and hardness of fine-wire cross-sections with diameters ranging from 100-200 microm. Using miniature optics and a specially developed micrometer positioning system, measurements were successfully performed on the wire cross-sections with an accuracy of 1 microm. Homogeneous wire cross-sections, such as MP35N (high-strength nickel-cobalt alloy), composite wires such as MP35N with a silver core (MP35N/Ag-core), and platinum-clad tantalum (Pt-clad Ta) were studied.