Papers by Keyword: XRR

Abstract: The NiTi shape memory alloy passivated for 90 min by autoclaving has been studied towards corrosion performance in the Tyrode’s simulated body fluid using open circuit potential and EIS measurements. The surface morphology and thickness of the oxide layer was determined by XRR. The HREM was used to observe the cross-section of the thin foil and to confirm the amorphous state of the TiO₂ layer and its thickness. Electrochemical measurements revealed a good corrosion resistance at the beginning of long-term (20 days) immersion. It was found that with the increase of immersion time, the corrosion resistance of the surface deteriorated after nearly 1 day of immersion due to occurence of pitting corrosion. The EIS method was used to detailed study on the electrolyte | passive layer interfacial properties. Equivalent electrical circuit for the pitting corrosion on the passivated NiTi alloy has been applied.

Abstract: In the study, an interlayer was observed in a nano-meter scale SiO2 overlayer on Si substrate by X-ray reflectivity(XRR) analysis and a new method is introduced for the XRR analysis of SiO2 ultra-thin films on Si substrate. The normalized reflectivity curves were analyzed by fitting with the calculated reflectivity curves which were also normalized with the same reference curves. The XRR analyses show that the variation of the positions of the thickness fringes in the measured reflectivity curve is caused by the interference effect from two oxide layers of different refractive indices and of different thicknesses with each other. The result indicates that there exists a SiO2 interlayer of a different refractive index between the SiO2 overlayer and the Si substrate. The analytical method used in the study determines the thickness of a ultra-thin SiO2 layer on Si with low uncertainty.