scholarly journals Mechanical Fracturing of Core-Shell Undercooled Metal Particles for Heat-Free Soldering

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Simge Çınar ◽  
Ian D. Tevis ◽  
Jiahao Chen ◽  
Martin Thuo
Keyword(s):  
Phase Change Materials ◽  
Low Cost ◽  
Liquid Core ◽  
Oxide Shell ◽  
Core Shell ◽  
Ambient Conditions ◽  
Complex Shapes ◽  
Droplet Emulsion ◽  
Shell Particles ◽  
Poor Stability

Abstract Phase-change materials, such as meta-stable undercooled (supercooled) liquids, have been widely recognized as a suitable route for complex fabrication and engineering. Despite comprehensive studies on the undercooling phenomenon, little progress has been made in the use of undercooled metals, primarily due to low yields and poor stability. This paper reports the use of an extension of droplet emulsion technique (SLICE) to produce undercooled core-shell particles of structure; metal/oxide shell-acetate (‘/’ = physisorbed, ‘-’ = chemisorbed), from molten Field’s metal (Bi-In-Sn) and Bi-Sn alloys. These particles exhibit stability against solidification at ambient conditions. Besides synthesis, we report the use of these undercooled metal, liquid core-shell, particles for heat free joining and manufacturing at ambient conditions. Our approach incorporates gentle etching and/or fracturing of outer oxide-acetate layers through mechanical stressing or shearing, thus initiating a cascade entailing fluid flow with concomitant deformation, combination/alloying, shaping, and solidification. This simple and low cost technique for soldering and fabrication enables formation of complex shapes and joining at the meso- and micro-scale at ambient conditions without heat or electricity.

scholarly journals Thermal and Mechanical Stabilities of Core-shell Microparticles Containing a Liquid Core

2021 ◽  
Author(s):  
Nam-Trung Nguyen ◽  
Nam-Trung Nguyen ◽  
Nam-Trung Nguyen ◽  
Nam-Trung Nguyen
Keyword(s):  
Shell Thickness ◽  
Liquid Core ◽  
Maximum Temperature ◽  
Heating Process ◽  
Core Shell ◽  
Rupture Force ◽  
Compression Force ◽  
Operation Conditions ◽  
Mechanical Models ◽  
Shell Particles

Abstract Thorough understanding of the behaviour of core-shell microparticles with a liquid core is essential for determining their performance in applications under different operation conditions. This paper reports the behaviour of core-shell particles with a liquid core under thermal and mechanical loads. First, we formulated an analytical model for the heating process of a core-shell microparticle with a liquid core. Next, we utilised an axisymmetric model of an elastic spherical shell upon compression to describe the deformation of a core-shell microparticle. Finally, we conducted experiments to validate these models. Both thermal and mechanical models agree well with the experimental data. The maximum temperature a core-shell microparticle can withstand depends on the liquid, the geometry, and the material of the shell. The critical compression force before rupture of a core-shell microparticle depends on the Poisson’s ratio of the shell material and the shell thickness relative to the outer shell radius. The rupture force and rupture temperature increase with increasing shell thickness.

Synthesis of Liquid Core–Shell Particles and Solid Patchy Multicomponent Particles by Shearing Liquids Into Complex Particles (SLICE)

Langmuir ◽  
2014 ◽  
Vol 30 (47) ◽  
pp. 14308-14313 ◽  
Author(s):  
Ian D. Tevis ◽  
Lucas B. Newcomb ◽  
Martin Thuo
Keyword(s):  
Liquid Core ◽  
Core Shell ◽  
Shell Particles

scholarly journals Formation of core-shell droplets for the encapsulation of liquid contents

2021 ◽  
Author(s):  
Fariba Malekpour Galogahi ◽  
Yong Zhu ◽  
Hongjie An ◽  
Nam-Trung Nguyen
Keyword(s):  
Microfluidic Device ◽  
Liquid Core ◽  
Core Shell ◽  
Flow Focusing ◽  
The Core ◽  
Liquid Phases ◽  
Optical Electron ◽  
Computed Microtomography ◽  
Shell Particles ◽  
High Degree

Abstract Accurate control of monodisperse core-shell droplets generated in a microfluidic device has a broad range of applications in research and industry. This paper reports the experimental investigation of flow-focusing microfluidic devices capable of producing size-tuneable and monodisperse core-shell droplets. The dimension of the core-shell droplets was controlled passively by the channel geometry and the flow rate of the liquid phases. The results indicate that microchannel geometry is more significant than flow rates. The highly controllable core-shell droplets could be subsequently employed as a template for generating core-shell micropaticles with liquid core. Optical, electron microscopy and X-ray computed microtomography showed that the geometry of the core-shell droplets remains unchanged after solidification, drying and collection. The present study also looks at the thermal stability of core-shell particles depending on the particle size. The larger core-shell partcles with a thicker shell provide a higher resistance to heating at elevated temperature. The high degree of control with a flow-focusing microfluidic device makes this a promising approach for the encapsulation, storage, and delivery of lipophilic contents.

scholarly journals On the Development of All-Cellulose Capsules by Vesicle-Templated Layer-by-Layer Assembly

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 589
Author(s):  
Alireza Eivazi ◽  
Bruno Medronho ◽  
Björn Lindman ◽  
Magnus Norgren
Keyword(s):  
Low Cost ◽  
Core Shell ◽  
Cellulose Derivatives ◽  
Layer By Layer ◽  
Reaction Conditions ◽  
Didodecyldimethylammonium Bromide ◽  
Shell Particles ◽  
Micrometer Scale ◽  
Oppositely Charged ◽  
Scale Deposition

Polymeric multilayer capsules formed by the Layer-by-Layer (LbL) technique are interesting candidates for the purposes of storage, encapsulation, and release of drugs and biomolecules for pharmaceutical and biomedical applications. In the current study, cellulose-based core-shell particles were developed via the LbL technique alternating two cellulose derivatives, anionic carboxymethylcellulose (CMC), and cationic quaternized hydroxyethylcellulose ethoxylate (QHECE), onto a cationic vesicular template made of didodecyldimethylammonium bromide (DDAB). The obtained capsules were characterized by dynamic light scattering (DLS), ζ potential measurements, and high-resolution scanning electron microscopy (HR-SEM). DLS measurements reveal that the size of the particles can be tuned from a hundred nanometers with a low polydispersity index (deposition of 2 layers) up to micrometer scale (deposition of 6 layers). Upon the deposition of each cellulose derivative, the particle charge is reversed, and pH is observed to considerably affect the process thus demonstrating the electrostatic driving force for LbL deposition. The HR-SEM characterization suggests that the shape of the core-shell particles formed is reminiscent of the spherical vesicle template. The development of biobased nano- and micro-containers by the alternating deposition of oppositely charged cellulose derivatives onto a vesicle template offers several advantages, such as simplicity, reproducibility, biocompatibility, low-cost, mild reaction conditions, and high controllability over particle size and composition of the shell.

scholarly journals Thermal and Mechanical Stabilities of Core-shell Microparticles Containing a Liquid Core

2021 ◽  
Author(s):  
Fariba Malekpour Galogahi ◽  
Hongjie An ◽  
Yong Zhu ◽  
Nam-Trung Nguyen
Keyword(s):  
Shell Thickness ◽  
Liquid Core ◽  
Maximum Temperature ◽  
Heating Process ◽  
Core Shell ◽  
Rupture Force ◽  
Compression Force ◽  
Operation Conditions ◽  
Mechanical Models ◽  
Shell Particles

Abstract Thorough understanding of the behaviour of core-shell microparticles with a liquid core is essential for determining their performance in applications under different operation conditions. This paper reports the behaviour of core-shell particles with a liquid core under thermal and mechanical loads. First, we formulated an analytical model for the heating process of a core-shell microparticle with a liquid core. Next, we utilised an axisymmetric model of an elastic spherical shell upon compression to describe the deformation of a core-shell microparticle. Finally, we conducted experiments to validate these models. Both thermal and mechanical models agree well with the experimental data. The maximum temperature a core-shell microparticle can withstand depends on the liquid, the geometry, and the material of the shell. The critical compression force before rupture of a core-shell microparticle depends on the Poisson’s ratio of the shell material and the shell thickness relative to the outer shell radius. The rupture force and rupture temperature increase with increasing shell thickness.

Engineering the nanostructure of a polymer-nanocomposite film containing Ti-based core–shell particles to enhance dielectric response

Nanoscale ◽  
2015 ◽  
Vol 7 (38) ◽  
pp. 15727-15733 ◽  
Author(s):  
Amoghavarsha Mahadevegowda ◽  
Neil P. Young ◽  
Patrick S. Grant
Keyword(s):  
Nanocomposite Film ◽  
Dielectric Response ◽  
Polymer Nanocomposite ◽  
Oxide Shell ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Shell Particles

A design-led approach that places Ag and Ti (core)–oxide (shell) nanoparticles at discrete positions in a polymer-based film offers enhanced dielectric response.

Magnetic Properties of Fe3O4/CoFe2O4 Composite Nanoparticles with Core/Shell Architecture

2020 ◽  
Vol 65 (10) ◽  
pp. 904
Author(s):  
V. O. Zamorskyi ◽  
Ya. M. Lytvynenko ◽  
A. M. Pogorily ◽  
A. I. Tovstolytkin ◽  
S. O. Solopan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Spinel Ferrite ◽  
Composite Nanoparticles ◽  
Core Shell ◽  
Cofe2o4 Nanoparticles ◽  
Core Diameter ◽  
The Core ◽  
Shell Particles ◽  
Interface Parameters ◽  
Shell Composite

Magnetic properties of the sets of Fe3O4(core)/CoFe2O4(shell) composite nanoparticles with a core diameter of about 6.3 nm and various shell thicknesses (0, 1.0, and 2.5 nm), as well as the mixtures of Fe3O4 and CoFe2O4 nanoparticles taken in the ratios corresponding to the core/shell material contents in the former case, have been studied. The results of magnetic research showed that the coating of magnetic nanoparticles with a shell gives rise to the appearance of two simultaneous effects: the modification of the core/shell interface parameters and the parameter change in both the nanoparticle’s core and shell themselves. As a result, the core/shell particles acquire new characteristics that are inherent neither to Fe3O4 nor to CoFe2O4. The obtained results open the way to the optimization and adaptation of the parameters of the core/shell spinel-ferrite-based nanoparticles for their application in various technological and biomedical domains.

Bromopropane as a Novel Bromine Precursor for the Completely Amine Free Colloidal Synthesis of Ultra-Stable and Highly Luminescent Green-Emitting Cesium Lead Bromide (CsPbBr3) Perovskite Nanocrystals

Nanoscale ◽  
2021 ◽  
Author(s):  
Syed Akhil ◽  
V.G.Vasavi Dutt ◽  
Nimai Mishra
Keyword(s):  
Optoelectronic Devices ◽  
Colloidal Synthesis ◽  
Ambient Conditions ◽  
Active Materials ◽  
Perovskite Nanocrystals ◽  
Lead Bromide ◽  
Halide Perovskite ◽  
Lead Halide ◽  
Poor Stability

Recently lead halide perovskite nanocrystals (PNCs) have attracted intense interest as promising active materials for optoelectronic devices. However, their extensive applications are still hampered by poor stability in ambient conditions....

Thermo-conductive phase change materials with binary fillers of core-shell-like distribution

2021 ◽  
Vol 144 ◽  
pp. 106326
Author(s):  
Sen Xue ◽  
Chuxin Lei ◽  
Dingyao Liu ◽  
Ke Wang ◽  
Kai Wu ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Core Shell ◽  
Conductive Phase

scholarly journals Facile Synthesis of Carboxymethyl Cellulose Coated Core/Shell SiO2@Cu Nanoparticles and Their Antifungal Activity against Phytophthora capsici

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 888
Author(s):  
Nguyen Thi Thanh Hai ◽  
Nguyen Duc Cuong ◽  
Nguyen Tran Quyen ◽  
Nguyen Quoc Hien ◽  
Tran Thi Dieu Hien ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Carboxymethyl Cellulose ◽  
Chemical Reduction ◽  
Low Cost ◽  
Phytophthora Capsici ◽  
Reduction Process ◽  
Spherical Shape ◽  
Core Shell ◽  
Cu Nanoparticles ◽  
Average Size

Cu nanoparticles are a potential material for creating novel alternative antimicrobial products due to their unique antibacterial/antifungal properties, stability, dispersion, low cost and abundance as well as being economical and ecofriendly. In this work, carboxymethyl cellulose coated core/shell SiO2@Cu nanoparticles (NPs) were synthesized by a simple and effective chemical reduction process. The initial SiO2 NPs, which were prepared from rice husk ash, were coated by a copper ultrathin film using hydrazine and carboxymethyl cellulose (CMC) as reducing agent and stable agent, respectively. The core/shell SiO2@Cu nanoparticles with an average size of ~19 nm were surrounded by CMC. The results indicated that the SiO2@Cu@CMC suspension was a homogenous morphology with a spherical shape, regular dispersion and good stability. Furthermore, the multicomponent SiO2@Cu@CMC NPs showed good antifungal activity against Phytophthora capsici (P. capsici). The novel Cu NPs-based multicomponent suspension is a key compound in the development of new fungicides for the control of the Phytophthora disease.

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