Si Nanoparticles: Its Stability in Aqueous Slurries and the Optimization of Oxide Layer Thickness for Optimal Electrochemical Performance

2018 ◽  
Keyword(s):  
Electrochemical Performance ◽  
Oxide Layer ◽  
Layer Thickness ◽  
Oxide Layer Thickness ◽  
Si Nanoparticles

Characterization of Inhomogeneity in Thermal Oxide SiO2 Films on 4H-SiC Epitaxial Substrates by a Combination of Fourier Transform Infrared Spectroscopy and Cathodoluminescence Spectroscopy

2018 ◽  
Vol 924 ◽  
pp. 273-276 ◽  
Author(s):  
Masanobu Yoshikawa ◽  
Keiko Inoue ◽  
Junichiro Sameshima ◽  
Hirohumi Seki
Keyword(s):  
Fourier Transform ◽  
Oxide Layer ◽  
Layer Thickness ◽  
Phonon Mode ◽  
Fourier Transform Infrared ◽  
Blue Shift ◽  
Peak Frequency ◽  
Oxide Layer Thickness ◽  
Thermal Oxide ◽  
Ft Ir

We measured Fourier transform infrared (FT-IR) and cathodoluminescence (CL) spectra of SiO2 films with a various thickness, grown on 4H-SiC substrates. The peak frequency of the transverse optical (TO) phonon mode was blue-shifted by about 5 cm−1 as the oxide-layer thickness decreased from 50-60 nm to 10 nm. The blue shift of the TO mode is considerd to be caused by interfacial compressive stresses in the oxide-layer. On the other hand, the TO phonon mode was found to dramatically decrease as the oxide-layer thickness decreased from 10 nm to 1.7 nm. The CL measurement indicates that the intensity of the CL peaks at about 460 and 490 nm attributed to oxygen vacancy centers (OVCs) for No.2 become stronger than that for No.1. From a comparison between FT-IR and CL measurements, we concluded that the red-shift of the TO phonon with decreasing the oxide-layer thickness can mainly be attributed to an increase in inhomogeneity at the SiO2/SiC interface with decreasing oxide-layer thickness.

The possibility to control the thickness of the oxide layer on the titanium Grade 2 by mechanical activation and heat treatment

2020 ◽  
Vol 2 (100) ◽  
pp. 70-77
Author(s):  
M. Szota ◽  
A. Łukaszewicz ◽  
K. Machnik
Keyword(s):  
Heat Treatment ◽  
Mechanical Activation ◽  
Oxide Layer ◽  
Layer Thickness ◽  
Pure Titanium ◽  
Medical Application ◽  
Oxide Layer Thickness ◽  
Surface Development ◽  
Titanium Grade ◽  
Practical Implications

Purpose: The paper presents the results of microstructure, surface development and thickness of the oxide layer on the pure titanium Grade 2 after mechanical activation and heat treatment (550°C/5h). Design/methodology/approach: Studies show that it is possible to control the thickness of the oxide layer by using different materials to change the roughness of surface - mechanical activation before heat treatment. After mechanical activation and heat treatment, the results of the thickness of the oxide layer as well as a level of surface development were obtained, presented and discussed. Findings: The conducted research have proved that mechanical activation of the surface which cause increase of surface development results in greater thickness of oxide layer which is formed during heat treatment. Nevertheless mechanical activation that results in decrease of surface development, such as polishing, results in decrease of oxide layer thickness. Research limitations/implications: The conducted research have showed up that mechanical activation of the surface which cause increase of surface development results in greater thickness of oxide layer which is formed during heat treatment. Nevertheless, mechanical activation that results in decrease of surface development, such as polishing, results in decrease of oxide layer thickness. Practical implications: are possible using similar method for passivation titanium alloys for medical application. Originality/value: The paper presents the possibility of using mechanical preactivation of surface before heat treatment passivation.

Effects of Pre-Oxide Layer Thickness on Thermal Cyclic Behavior of Thermal Barrier Coatings

2007 ◽  
Vol 336-338 ◽  
pp. 1746-1749 ◽  
Author(s):  
Dong Bo Zhang ◽  
Sheng Kai Gong ◽  
Hui Bin Xu
Keyword(s):  
Oxide Layer ◽  
Layer Thickness ◽  
Thermal Barrier Coatings ◽  
Failure Modes ◽  
Thermally Grown Oxide ◽  
Layer Growth ◽  
Cyclic Behavior ◽  
Thermal Barrier ◽  
Oxide Layer Thickness ◽  
Barrier Coatings

Conventional two-layered structure thermal barrier coatings (TBCs) with different pre-oxide layer thicknesses were produced by EB-PVD onto Ni-based superalloy. The pre-oxide layer with different thicknesses was formed after vacuum heat treatment for 2 hours and before ceramic deposition by heating the bond coat to 1323K in air for different times. It has been found that with pre-oxide layer thickness increasing from 1μm to 3.1μm, the growth rate of thermally grown oxide (TGO) increased during thermal cycling test and the thermal cyclic lifetime of TBCs decreased from 730hs to 400hs Two failure modes were observed for TBCs with different pre-oxide layer thicknesses and different TGO layer growth rates.

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