scholarly journals Preparation of Ceria-Coated Silica Nanoparticles and Their Chemical Mechanical Planarization Performance on Si-Face 6H-SiC Substrates

2021 ◽  
Author(s):  
Zifeng Ni ◽  
Guomei Chen ◽  
Laijun Xu ◽  
Ping Zhang ◽  
Mengjiao Dai ◽  
...  
Keyword(s):  
Shell Structure ◽  
Chemical Mechanical Planarization ◽  
Precipitation Method ◽  
Core Shell ◽  
Aqueous Mixtures ◽  
Amorphous Sio2 ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Core Shell Structure

Abstract Ceria-coated silica (SiO2/CeO2) composite abrasives were prepared through a novel homogeneous precipitation method using commercial silica (SiO2) sol as the silicon resource and cerium nitrate (Ce(NO3)3) and hexamethylenetetramine (HMT) aqueous mixtures as coating precursors. The phase composition, nano-topography, size distribution, and chemical structure of as-prepared particles were characterized by X-ray diffraction, transmission electron microscopy, Zetasizer Nano ZS90 and Fourier infrared spectra. In addition, the possible coating mechanism was discussed. Then, chemical mechanical planarization behaviors of SiO2 sol, ceria (CeO2) sol, and the novel abrasives and on Si-face (0001) 6H-SiC were investigated by atomic force microscopy. The results indicated that the composite particles were mono-dispersed nano-spheres composed of amorphous SiO2 core and cubic fluorite CeO2 shell, possessing complete core-shell structure and particle size of about 110 nm. CeO2 shell (10 nm) grew on the surface of SiO2 core by formation of Ce-O-Si chemical bonds, forming stable core-shell structure. SiO2/CeO2 composite abrasives provided an exponentially high material remove rate (MRR) of 1207 nm/h and an impressive surface finish with roughness average (Ra) 0.216 nm due to its active chemical property and unique structure.

Preparation and Property Study of Core-Shell Ambient-Temperature Crosslinkable Polyacrylate Binder

2013 ◽  
Vol 469 ◽  
pp. 3-6 ◽  
Author(s):  
Mu Li ◽  
Xiao Song Lin ◽  
Xiao Yu Li ◽  
Hai Qiao Wang
Keyword(s):  
Ambient Temperature ◽  
Butyl Acrylate ◽  
Core Shell ◽  
Drying Time ◽  
Acrylic Polymer ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Film Forming ◽  
Water Based

As the binder of waterborne inks, the capability of acrylic polymer has great influences on the quality of inks. In this contribution, structured latex particles with a poly (stryrene-butyl acrylate-methacrylate) core and a poly (butyl acrylate-methyl methacrylate-methacrylic acid-diacetone acrylamide (DAAM)) shell, which can be used as binders of water-based ink, were prepared by emulsion polymerization. The emulsion can cure in the course of film forming at ambient temperature through the reaction between DAAM and the adipic acid dihydrazide (ADH). Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), transmission electron microscopy (TEM), atomic force microscopy (AFM) were used to characterize the structures and study the properties of the latices. The drying time of the crosslinking latices was investigated. In addition, influences of DAAM monomer dosage and the mole ratio of DAAM to ADH on the mechanical properties of self-crosslinkable core-shell latices were also discussed. It was found that the core-shell crosslinkable particles with a low glass transition temperature (Tg) core and a high Tg shell have better film properties and would be more applicable to binders of water-based ink for plastic film, in comparison with those particles with a high Tg core and a low Tg shell.

Preparation of Amorphous Calcium Phosphate/Triclcium Silicate Composite Powders

2009 ◽  
Vol 79-82 ◽  
pp. 1643-1646 ◽  
Author(s):  
Qing Lin ◽  
Yan Bao Li ◽  
Xiang Hui Lan ◽  
Chun Hua Lu ◽  
Zhong Zi Xu
Keyword(s):  
Calcium Phosphate ◽  
Shell Structure ◽  
Amorphous Calcium Phosphate ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
X Ray ◽  
Core Shell Structure

The amorphous calcium phosphate (ACP)/tricalcium silicate (Ca3SiO5, C3S) composite powders were synthesized in this paper. The exothermal behavior of C3S determined by isothermal conduction calorimetry indicated that the ACP could be synthesis by chemical precipitation method during the induction period (stage II) of C3S. The composite powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results indicated that nanosized ACP particles deposited on the surface of C3S particles to form core-shell structure at pH=10.5, and the nCa/nP of ACP could be controlled between 1.0 and 1.5. The core-shell structure is stable after sintered at 500 oC for 3 h to remove the β-cyclodextrin (β-CD). As compared with the irregular C3S particles (1~5 μm), the composite powders particles are spherical with a diameter of 40~150 μm. Therefore, to obtain the smaller size of composite powders, it is expected to avoid the aggregate of C3S particles in the aqueous solution by addition of dispersant. As compared with C3S, the composite powders may contribute better injectability, strength and biocompatibility.

Toughening Modification of PA6 with Different Core-Shell Particles

2013 ◽  
Vol 750-752 ◽  
pp. 820-823
Author(s):  
Zhen Yu Liu ◽  
Yu Zhu Xiong ◽  
Wen Jie Mei ◽  
Li Wang
Keyword(s):  
Electron Microscopy ◽  
Impact Strength ◽  
Shell Structure ◽  
Performance Test ◽  
Mechanical Performance ◽  
Core Shell ◽  
Transmission Electron ◽  
Notch Impact Strength ◽  
Core Shell Structure ◽  
Shell Particles

(POE-g-MAH/OMMT) and (POE-g-MAH/SiO2) toughening particles of core-shell structure were prepared by ball grinding method and were used to modify toughness of PA6.The morphology of PA6 modified by these core-shell particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM),and were detected by mechanical performance test. The results show that both toughening particles could improved notch impact strength of PA6,and with toughening particle exceed 10%, composites notch impact strength is rapid increase.(POE-g-MAH/OMMT) particle of PA6 toughening effect is better than (POE-g-MAH/SiO2).When material under impact, OMMT produced slip effect in core-shell structure and SiO2 produced rolling effect.

Microstructures and Highly Accelerated Lifetime Test of X5R Type BaTiO3-Based Ni-MLCC with Ultra-Thin Active Layers

2014 ◽  
Vol 602-603 ◽  
pp. 695-699
Author(s):  
Hui Ling Gong ◽  
Xiao Hui Wang ◽  
Shao Peng Zhang ◽  
Xin Ye Yang ◽  
Long Tu Li
Keyword(s):  
Dielectric Properties ◽  
Shell Structure ◽  
Casting Process ◽  
Thin Layers ◽  
Core Shell ◽  
Active Layers ◽  
Transmission Electron ◽  
Lifetime Test ◽  
Accelerated Lifetime ◽  
Core Shell Structure

Microstructure control in thin-layer multilayer ceramic capacitors (MLCCs) is one of the challenges for increasing capacitive volumetric efficiency and high voltage dielectric properties. In this paper, the X5R-MLCCs with ultra-thin dielectric layers (~1.2 μm) owning uniform grain size distribution were prepared by wet casting process. The microstructures and dielectric properties of the MLCCs were investigated. The existence of core-shell structure was proved by transmission electron microscopy observation and energy dispersive spectroscopy analysis. The existence of core-shell structure makes the temperature coefficient of capacitance (TCC) performance meet X5R standard. Moreover, a highly accelerated lifetime test (HALT) result shows that MLCCs with ultra-thin layers under high electric field are more easily to fail with increasing test temperatures. And the results reveal that the activation energy is similar to the value reported for mid-dielectric constant dielectrics.

Atomic-force microscopy of a fractured rubber-toughened epoxy

1994 ◽  
Vol 52 ◽  
pp. 888-889
Author(s):  
O. Shaffer ◽  
J. Qian ◽  
V. Dimonie ◽  
R. Pearson ◽  
M. El-Aasser
Keyword(s):  
Atomic Force Microscopy ◽  
Crosslinking Agent ◽  
Core Shell ◽  
Physical Interaction ◽  
Latex Particles ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Rubber Toughened ◽  
Shell Particles

Atomic force microscopy (AFM) is a powerful scanning probe technique, which is capable of imaging polymer surfaces. This technique is complementary to the scanning electron microscope (SEM) but because of the AFM's sensitivity in the z direction surfaces that are too smooth to image by SEM can easily be imaged by AFM. This study utilizes transmission electron microscopy(TEM) to image the morphology of the latex rubber particles; SEM and AFM are used to study the degree of dispensability of the latex particles in the epoxy, and the fatigue-fracture surface of the rubber modified epoxy.Core-shell latex particles were prepared with a core of poly(butadiene-styreiie) |P(B-S)| and a shell Poly(methyl methacrylate)(PMMA). In order to study the interaction between the core/shell particles and the epoxy matrix, the shell is systematically varied in terms of chemical bonding, physical interaction and the extent of these interactions by incorporating acrylonitrile(AN). glycidyl-methacrylate(GMA). and crosslinking agent divinylbenzene(DVB) of varying concentrations in the shell.

A BIO-INSPIRED POLYDOPAMINE APPROACH TO PREPARATION OF GOLD-COATED Fe3O4 CORE–SHELL NANOPARTICLES: SYNTHESIS, CHARACTERIZATION AND MECHANISM

NANO ◽  
2013 ◽  
Vol 08 (06) ◽  
pp. 1350061 ◽  
Author(s):  
PENG AN ◽  
FANG ZUO ◽  
XINHUA LI ◽  
YUANPENG WU ◽  
JUNHUA ZHANG ◽  
...  
Keyword(s):  
Shell Structure ◽  
Room Temperature ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Stabilizing Agent ◽  
X Ray ◽  
Transmission Electron ◽  
Core Shell Structure ◽  
Core Shell Nanoparticles

A biomimetic and facile approach for integrating Fe 3 O 4 and Au with polydopamine (PDA) was proposed to construct gold-coated Fe 3 O 4 nanoparticles ( Fe 3 O 4@ Au – PDA ) with a core–shell structure by coupling in situ reduction with a seed-mediated method in aqueous solution at room temperature. The morphology, structure and composition of the core–shell structured Fe 3 O 4@ Au – PDA nanoparticles were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and X-ray photoelectron spectrometry (XPS). The formation process of Au shell was assessed using a UV-Vis spectrophotometer. More importantly, according to investigating changes in PDA molecules by Fourier transform infrared spectroscopy (FTIR) and in preparation process of the zeta-potential data of nanoparticles, the mechanism of core–shell structure formation was proposed. Firstly, PDA-coated Fe 3 O 4 are obtained using dopamine (DA) self-polymerization to form thin and surface-adherent PDA films onto the surface of a Fe 3 O 4 "core". Then, Au seeds are attached on the surface of PDA-coated Fe 3 O 4 via electrostatic interaction in order to serve as nucleation centers catalyzing the reduction of Au 3+ to Au 0 by the catechol groups in PDA. Accompanied by the deposition of Au , PDA films transfer from the surface of Fe 3 O 4 to that of Au as stabilizing agent. In order to confirm the reasonableness of this mechanism, two verification experiments were conducted. The presence of PDA on the surface of Fe 3 O 4@ Au – PDA nanoparticles was confirmed by the finding that glycine or ethylenediamine could be grafted onto Fe 3 O 4@ Au – PDA nanoparticles through Schiff base reaction. In addition, Fe 3 O 4@ Au – DA nanoparticles, in which DA was substituted for PDA, were prepared using the same method as that for Fe 3 O 4@ Au – PDA nanoparticles and characterized by UV-Vis, TEM and FTIR. The results validated that DA possesses multiple functions of attaching Au seeds as well as acting as both reductant and stabilizing agent, the same functions as those of PDA.

Effect of protamine on Fe3O4@CS@GFTN composite magnetic nanoparticles

2019 ◽  
Vol 13 (02) ◽  
pp. 2050001 ◽  
Author(s):  
Huiping Shao ◽  
Luhui Wang ◽  
Tao Lin ◽  
Yumeng Zhang ◽  
Zhinan Zhang
Keyword(s):  
Magnetic Nanoparticles ◽  
Shell Structure ◽  
Lung Diseases ◽  
Core Shell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Core Shell Structure ◽  
Average Size ◽  
Chemical Coprecipitation Method

Fe3O4@chitosan (CS)@Gefitinib (GFTN) core-shell structure composite magnetic nanoparticles (NPs) were prepared by chemical coprecipitation method in this study. In addition, protamine was doped in Fe3O4 cores to prepare Fe3O4@protamine@CS@GFTN core-shell structure composite NPs, in order to increase the loading of GFTN in composite NPs. They were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and spectrophotometer. The results show that the average size of Fe3O4@CS@GFTN and Fe3O4@protamine@CS@GFTN composite NPs is approximately 19 and 21[Formula: see text]nm, respectively. The saturation magnetizations of composite magnetic NPs and corresponding magnetic fluids are 57.20, 20.79, 59.58 and 19.75[Formula: see text]emu/g, respectively. The loading of GFTN in composite NPs was measured by a spectrophotometer to be about 13.5% and 27.6%, respectively. The addition of protamine increased the loading of GFTN two times, indicating that it will play an important role in the management of lung diseases.

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