scholarly journals A Study of Anodising Behaviour of Al-Si Components Produced by Rheocasting

2019 ◽  
Vol 285 ◽  
pp. 39-44
Author(s):  
Bai Wei Zhu ◽  
Salem Seifeddine ◽  
Anders E.W. Jarfors ◽  
Peter Leisner ◽  
Caterina Zanella
Keyword(s):  
Oxide Layer ◽  
Layer Thickness ◽  
Casting Machine ◽  
Treatment Method ◽  
Al Alloy ◽  
Oxide Layer Thickness ◽  
Liquid Segregation ◽  
Pre Treatment ◽  
Pressure Die Casting ◽  
The Relationship

This paper aims to investigate the anodising behaviour of Al-Si components produced by rheocasting, to understand the effect of the surface liquid segregation (SLS) on the anodising response. The material investigated was EN AC 42000 Al-alloy with an addition of 150 ppm Sr. The component was rheocast and conventionally liquid cast for benchmarking. The RheoMetalTM process was used to prepare slurry and subsequently cast using a vertical pressure die casting machine. Prior to anodising, mechanical grinding was used as pre-treatment method for selected samples as comparison with components in the as-cast state. Anodising was performed on the components using a constant controlled voltage at 25 V, in 1 M H2SO4, at room temperature. The duration of anodising was varied from 30 mins to 120 mins to examine the relationship between oxide layer thickness and the anodising time. The oxide layer was investigated and characterised. The results demonstrated that the presence of the SLS layer, which was enriched with alloying elements, had a significant influence on the anodising behaviour of the cast component. The oxide layer thickness of the components produced by rheocasting and fully liquid casting was measured and compared. The relations between the oxide layer thickness and anodising time, as well as the casting methods are presented and discussed in this paper.

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.

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