Ellipsometric study of optical properties and oxidation processes of compacted powders based on aluminum alloys

2019 ◽  
pp. 23-32
Author(s):  
L. A. Akashev ◽  
N. A. Popov ◽  
V. G. Shevchenko ◽  
A. I. Ananyev
Keyword(s):  
Oxide Film ◽  
Film Thickness ◽  
Optical Constants ◽  
Binary Alloys ◽  
Oxide Films ◽  
Silicon Alloys ◽  
Aluminum Silicon Alloys ◽  
Oxide Film Thickness ◽  
Ellipsometric Study ◽  
Aluminum Silicon

The paper presents the results of an ellipsometric study of compacted powders of aluminum-based binary alloys containing 1,5 wt.% of rare earth elements (Sc, La, Ce, Sm) and cast aluminum-silicon alloys with the following compositions: Al–10Si–0,5Mg– 0,3Fe–0,1Ca and Al–12Si–0,6Mg–0,5Fe–0,5Ca–0,45Na. An immersion method was used to determine the optical constants of massive polycrystalline alloys obtained by remelting these powders in vacuum, as well as their oxide films for a wavelength λ = 0,6328 μm. Using the optical constants of these alloys, the dependence of their reflectivity on the surface oxide film thickness was calculated. It was found that an increase in the amount of the alloying component and intermetallic phases in the alloy decreases its reflectivity. In addition, the optical constants were used in the construction of modified Δ–ψ nomograms calculated using the Maxwell-Garnett equation that make it possible to determine the thicknesses of oxide films on particles and the volume fractions of metal in compacted powders, and to study the processes of their oxidation in air. It was shown that oxidation of aluminum ASD-4 powders and Al–1,5% REM binary alloys at 600 °C is described by a simple model where a decrease in the metal fraction leads to an increase in the oxide film thickness. It turned out that the oxidation of aluminum-silicon alloys is much faster and not described by this model, which may be due to the appearance of a liquid phase in the powder. A large number of metal droplets on the surface of particles increase the amount of metal on the studied tablet surface in general. The high oxidation rate of aluminumsilicon alloys in air can be explained by the surface activity of magnesium in relation to liquid aluminum.

scholarly journals Surface Corrosion Resistance in Turning of Titanium Alloy

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Rui Zhang ◽  
Xing Ai ◽  
Yi Wan ◽  
Zhanqiang Liu ◽  
Dong Zhang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Oxide Film ◽  
Film Thickness ◽  
Titanium Alloys ◽  
Oxygen Concentration ◽  
Oxide Films ◽  
Surface Oxidation ◽  
Implant Surface ◽  
Surface Corrosion ◽  
Oxide Film Thickness

This work addresses the issues associated with implant surface modification. We propose a method to form the oxide film on implant surfaces by dry turning to generate heat and injecting oxygen-rich gas at the turning-tool flank. The morphology, roughness, composition, and thickness of the oxide films in an oxygen-rich atmosphere were characterized using scanning electron microscopy, optical profiling, and Auger electron spectroscopy. Electrochemical methods were used to study the corrosion resistance of the modified surfaces. The corrosion resistance trends, analyzed relative to the oxide film thickness, indicate that the oxide film thickness is the major factor affecting the corrosion resistance of titanium alloys in a simulated body fluid (SBF). Turning in an oxygen-rich atmosphere can form a thick oxide film on the implant surface. The thickness of surface oxide films processed at an oxygen concentration of 80% was improved to 4.6 times that of films processed at an oxygen concentration of 21%; the free corrosion potential shifted positively by 0.357 V, which significantly improved the corrosion resistance of titanium alloys in the SBF. Therefore, the proposed method may (partially) replace the subsequent surface oxidation. This method is significant for biomedical development because it shortens the process flow, improves the efficiency, and lowers the cost.

scholarly journals Photoluminescence of ion-synthesized 9R-Si inclusions in SiO2/Si structure: Effect of irradiation dose and oxide film thickness

2021 ◽  
Vol 118 (21) ◽  
pp. 212101
Author(s):  
Alena Nikolskaya ◽  
Alexey Belov ◽  
Alexey Mikhaylov ◽  
Anton Konakov ◽  
David Tetelbaum ◽  
...  
Keyword(s):  
Oxide Film ◽  
Film Thickness ◽  
Irradiation Dose ◽  
Structure Effect ◽  
Oxide Film Thickness

Residual Stress Measurement in Silicon Substrate After Local Thermal Oxidation Using Microscopic Raman Spectroscopy

1991 ◽  
Vol 226 ◽  
Author(s):  
Hideo Miura ◽  
Hiroshi Sakata ◽  
Shinji Sakata Merl
Keyword(s):  
Residual Stress ◽  
Raman Spectroscopy ◽  
Tensile Stress ◽  
Oxide Film ◽  
Film Thickness ◽  
Silicon Dioxide ◽  
Thermal Oxidation ◽  
Silicon Substrate ◽  
Nitride Film ◽  
Oxide Film Thickness

AbstractThe residual stress in silicon substrates after local thermal oxidation is discussed experimentally using microscopic Raman spectroscopy. The stress distribution in the silicon substrate is determined by three main factors: volume expansion of newly grown silicon–dioxide, deflection of the silicon–nitride film used as an oxidation barrier, and mismatch in thermal expansion coefficients between silicon and silicon dioxide.Tensile stress increases with the increase of oxide film thickness near the surface of the silicon substrate under the oxide film without nitride film on it. The tensile stress is sometimes more than 100 MPa. On the other hand, a complicated stress change is observed near the surface of the silicon substrate under the nitride film. The tensile stress increases initially, as it does in the area without nitride film on it. However, it decreases with the increase of oxide film thickness, then the compressive stress increases in the area up to 170 MPa. This stress change is explained by considering the drastic structural change of the oxide film under the nitride film edge during oxidation.

scholarly journals Effect of Silver Oxide Film Thickness on Some Optical Parameter

2014 ◽  
Vol 11 (2) ◽  
pp. 690-694
Author(s):  
Baghdad Science Journal
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Oxide Film ◽  
Film Thickness ◽  
Silver Oxide ◽  
Optical Parameter ◽  
Oxide Film Thickness ◽  
Chemical Spray ◽  
Transmission And Absorption ◽  
Different Thickness

Films of silver oxide of different thickness have been prepared by the chemical spray paralysis. Transmission and absorption spectra have recorded in order to study the effect of increasing thickness on some optical parameter such as reflectance, refractive index , and dielectric constant in its two parts . This study reveals that all these paramters affect by increasing the thickness .

Detection of Interfaces States Correlated with Layer-by-Layer Oxidation on Si(100)

1999 ◽  
Vol 592 ◽  
Author(s):  
T. Hattori ◽  
H. Nohira ◽  
Y Teramoto ◽  
N. Watanabe
Keyword(s):  
Surface Roughness ◽  
Oxide Film ◽  
Film Thickness ◽  
Interface State ◽  
State Density ◽  
Layer By Layer ◽  
Oxide Film Thickness ◽  
Maximum Value ◽  
State Densities ◽  
Atomically Flat

ABSTRACTThe interface state densities near the midgap were measured with the progress of oxidation of atomically flat Si(100) surface. It was found that the interface state distribution in Si bandgap changes periodically with the progress of oxidation. Namely, the interface-state density near the midgap of Si exhibits drastic decrease at oxide film thickness where the surface roughness of oxide film takes its minimum value, while that does not exhibit decrease at the oxide film thickness where the surface roughness takes its maximum value. In order to minimize interface state densities the oxide film thickness should be precisely controlled to within an accuracy of 0.02 nm.

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