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"Glass Microstructure."
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Dynamical heterogeneities in glasses, colloids, and granular media
\"Most of the solid materials we use in everyday life, from plastics to cosmetic gels exist under a non-crystalline, amorphous form: they are glasses. Yet, we are still seeking a fundamental explanation as to what glasses really are and to why they form. In this book, we survey the most recent theoretical and experimental research dealing with glassy physics, from molecular to colloidal glasses and granular media. Leading experts in this field present broad and original perspectives on one of the deepest mysteries of condensed matter physics, with an emphasis on the key role played by heterogeneities in the dynamics of glassiness\"-- Provided by publisher.
Book
Experimental Study on Ultrasonic Vibration-Assisted WECDM of Glass Microstructures with a High Aspect Ratio
With the rapid development of micro-electro-mechanical systems (MEMSs), the demand for glass microstructure is increasing. For the purpose of achieving high quality and stable machining of glass microstructures with a high aspect ratio, ultrasonic vibration is applied into the micro-wire electrochemical discharge machining (WECDM), which is proposed as ultrasonic vibration-assisted WECDM with a micro helical electrode. Firstly, the formation of a gas film on the surface of the helical electrode in WECDM machining is simulated, meaning the thickness of the gas film can be reduced by adding suitable ultrasonic amplitude, thus reducing the critical voltage, then the machining localization and stability were enhanced. Then, the micro helical electrode with a diameter of 100 μm is used to carry out sets of experiments that study the influence of ultrasonic amplitude, machining voltage, duty factor, pulse frequency, and feed rate on the slit width. The experimental results show that the machining stability and quality are significantly improved by adding suitable ultrasonic amplitude. When the amplitude was 5.25 μm, the average slit width was reduced to 128.63 μm with a decrease of 20.78%. Finally, with the optimized machining parameters, micro planar coil structure and microcantilever structure with a high aspect ratio were fabricated successfully on the glass plate. It is proved that ultrasonic vibration-assisted WECDM with the micro helical electrode method can meet the requirements of high aspect ratio microstructure machining for hard and brittle materials.
Journal Article
Hollow Glass Microspheres for Plastics, Elastomers, and Adhesives Compounds
Hollow Glass Microspheres for Plastics, Elastomers, and Adhesives Compounds brings together, for the first time, all of the practical and theoretical aspects of glass bubble manufacturing, including its properties, processing, and applications, as well as regulatory, environmental, and health and safety aspects.The book enables the reader to.
eBook
Development of shrinkage model of micro structured vitreous carbon mold for glass molding
Carbonization of replicated furan precursors has been proposed as a low-cost large-area method for fabricating microstructured vitreous carbon (VC) molds to glass micromolding. During the carbonization of furan precursors, large anisotropic shrinkage occurs inherently owing to thermal decomposition of the material, and this anisotropic shrinkage should be compensated to obtain the designed profiles of microcavities on the VC mold. In this study, a linear gradual shrinkage ratio model (LGSRM) was developed to predict the anisotropic shrinkage characteristics associated with the fabrication of microstructured VC molds. To verify the shrinkage model, the shape change of the VC mold according to the LGSRM was simulated with ANSYS and compared with the experimental results. To determine the coefficients of LGSRM, a finite element analysis code, in which a gradual shrinkage ratio can be assigned to each individual mesh, was developed, and the coefficients of LGSRM were selected to minimize the errors between the simulated and measured geometrical properties of the VC mold.
Journal Article
Optical characteristics on practical verification for pico-laser-engraved glass light guide plate with concave microstructures
Recent increasing interest in light guide plates (LGPs) based on the advanced manufacturing towards optoelectronics applications has emerged as a potential technology. The aim of this study was to estimate the optical characteristics on practical verification of laser-engraved glass light guide plate with concave microstructures. The case study can use the industrial ability of picosecond laser (pico-laser) technique, a type of ultrafast laser pulses, to directly engrave a glass sheet (Corning Iris® Glass) with functional concave microstructures for fabricating an LGP. Eight small pieces of samples with array of microstructures engraved on different processing conditions were made for measuring optical characteristics before and after the samples were etched by hydrofluoric acid. Here, the engraved 6-inch LGP structures can make light exit from the LGP uniformly. Additionally, the two optimized LGPs were put in a 7.8-inch backlight module where the measured results showed the uniformity of spatial luminance was 0.9. The study demonstrated the one-step process utilizing pico-laser technique, yielding for the design of microstructures of thinner large-sized liquid crystal display (LCD) products in the manufacturing of LGPs for lighted-up in a backlight unit (BLU).
Journal Article
Morphological Studies on Microstructure of Thai Ancient Glass Beads
Various ancient glass beads in prehistorical - historical period (around 2500-1200 BP) from the collection of the Banraiprachasawan local museum (A. Pisalee, Nakhon Sawan) were studied to determine elemental compositions and morphologies using electron probe microanalysis (EPMA) and scanning electron microscopy/energy dispersive x-ray analysis (SEM/EDX). The colors of the beads range from blue to red brown. From the EPMA data, all beads contain copper in the glass matrices. The SEM/EDX showed differences in the microstructures of the glass beads. The transparent blue, greenish blue and light green beads contain small particles of tin oxide while the opaque orange or red brown beads contain both copper oxide and tin oxide particles. The forms of copper oxide in the orange and red brown beads were proposed from previous work: Cu2O in the orange glass and copper metal in the red brown glass.
Journal Article
MICROSTRUCTURE CONTROL
This chapter contains sections titled:
Solid‐State Reactions
Microstructure Design
Control of Key Properties
Methods and Measurements
Book Chapter
Effect of Interface Structure on the Hydrophobicity, Mechanical and Optical Properties of HfO2/Mo/HfO2 Multilayer Films
We report on the super-hydrophobicity and tunable and optical and mechanical properties of transparent HfO
2
(50 nm)/Mo(20 nm)/HfO
2
(50 nm) multilayer films facilitated by engineering the ceramic–metal interface microstructure. A comparative study of nano-columnar and glassy (dense) structured HfO
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/Mo/HfO
2
multilayer films demonstrate the remarkable effect of interface structure on their hydrophobicity and mechanical properties. The nano-columnar structured multilayer films exhibit the dominance over the glassy structured stack in terms of their enhanced characteristics, namely the mechanical characteristics, anti-reflection behavior, visible transmittance, and hydrophobicity. While hydrophobicity is derived from the combined effect of hierarchical surface roughness and nano-columnar structure of the top and bottom Hf-oxide ceramic layers, the enhanced mechanical response is derived from the columnar structure of Mo metallic interlayer vertically aligned with overall multilayer stack. The combination of super-hydrophobicity and enhanced mechanical properties of optically transparent HfO
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/Mo/HfO
2
multilayer films through HfO
2
–Mo interface structure control as demonstrated in this work may provide a pathway to further tune the efficiency and in the optimization of architectures for energy-saving applications.
Journal Article
Design of robust superhydrophobic surfaces
The ability of superhydrophobic surfaces to stay dry, self-clean and avoid biofouling is attractive for applications in biotechnology, medicine and heat transfer
1
–
10
. Water droplets that contact these surfaces must have large apparent contact angles (greater than 150 degrees) and small roll-off angles (less than 10 degrees). This can be realized for surfaces that have low-surface-energy chemistry and micro- or nanoscale surface roughness, minimizing contact between the liquid and the solid surface
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–
17
. However, rough surfaces—for which only a small fraction of the overall area is in contact with the liquid—experience high local pressures under mechanical load, making them fragile and highly susceptible to abrasion
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. Additionally, abrasion exposes underlying materials and may change the local nature of the surface from hydrophobic to hydrophilic
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, resulting in the pinning of water droplets to the surface. It has therefore been assumed that mechanical robustness and water repellency are mutually exclusive surface properties. Here we show that robust superhydrophobicity can be realized by structuring surfaces at two different length scales, with a nanostructure design to provide water repellency and a microstructure design to provide durability. The microstructure is an interconnected surface frame containing ‘pockets’ that house highly water-repellent and mechanically fragile nanostructures. This surface frame acts as ‘armour’, preventing the removal of the nanostructures by abradants that are larger than the frame size. We apply this strategy to various substrates—including silicon, ceramic, metal and transparent glass—and show that the water repellency of the resulting superhydrophobic surfaces is preserved even after abrasion by sandpaper and by a sharp steel blade. We suggest that this transparent, mechanically robust, self-cleaning glass could help to negate the dust-contamination issue that leads to a loss of efficiency in solar cells. Our design strategy could also guide the development of other materials that need to retain effective self-cleaning, anti-fouling or heat-transfer abilities in harsh operating environments.
Water-repellent nanostructures are housed within an interconnected microstructure frame to yield mechanically robust superhydrophobic surfaces.
Journal Article
Electric‐Field‐Driven Printed 3D Highly Ordered Microstructure with Cell Feature Size Promotes the Maturation of Engineered Cardiac Tissues
Engineered cardiac tissues (ECTs) derived from human induced pluripotent stem cells (hiPSCs) are viable alternatives for cardiac repair, patient‐specific disease modeling, and drug discovery. However, the immature state of ECTs limits their clinical utility. The microenvironment fabricated using 3D scaffolds can affect cell fate, and is crucial for the maturation of ECTs. Herein, the authors demonstrate an electric‐field‐driven (EFD) printed 3D highly ordered microstructure with cell feature size to promote the maturation of ECTs. The simulation and experimental results demonstrate that the EFD jet microscale 3D printing overcomes the jet repulsion without any prior requirements for both conductive and insulating substrates. Furthermore, the 3D highly ordered microstructures with a fiber diameter of 10–20 µm and spacing of 60–80 µm have been fabricated by maintaining a vertical jet, achieving the largest ratio of fiber diameter/spacing of 0.29. The hiPSCs‐derived cardiomyocytes formed ordered ECTs with their sarcomere growth along the fiber and developed synchronous functional ECTs inside the 3D‐printed scaffold with matured calcium handling compared to the 2D coverslip. Therefore, the EFD jet 3D microscale printing process facilitates the fabrication of scaffolds providing a suitable microenvironment to promote the maturation of ECTs, thereby showing great potential for cardiac tissue engineering. A simple, and efficient strategy using electric‐field‐driven jet microscale 3D printing to fabricate 3D highly ordered microstructures with both the fiber width and fiber spacing that match myocardial feature sizes is first developed to build engineered cardiac tissues (ECTs) with hiPSC‐CMs. The myocardial feature‐sized structure promoted the maturation of ECTs, thereby showing great potential for cardiac tissue engineering.
Journal Article