Papers by Keyword: Passivation

Abstract: The behavior of chrome alloyed steel in various combinations of inorganic media has been studied. Steel samples were processed by electrochemical discharge grinding in nitrates (KNO₃, NaNO₃), chlorate solution (NaClO₃) and nitrates with various additives (KNO₃+Na₂CO₃, NaNO₃ +NaClO₃). In inorganic solutions, the presence of a great number of negative ions (NO₃^-, ClO₃^- HO^-) resulted by electrolytic dissociation of the salts, increases the metal oxidation as well as anodic dissolution. The rate of metal dissolution increased with the increasing NO₃^- ions that accelerate the anodic dissolution

Abstract: Chalcopyrite ternary and kesterite quaternary thin films, such as Cu (In,Ga)(S,Se)₂ and Cu₂ZnSn (S,Se)₄ generically referred to as CIGSSe and CZTSSe, respectively, have become the subject of considerable interest and study for semiconductor devices in recent years [1,2]. These materials are of particular interest for use as an absorber layer in photovoltaic devices. In thin film solar cells, the p-type CIGSSe or CZTSSe layer is combined with an n-type semiconductor thin film such as CdS buffer layer to form the p-n heterojunction of the device. The synthesis process of the CIGSSe or CZTSSe absorber layer requires temperatures ranging between 400 and 600 °C to form the photoactive chalcopyrite or kesterite phases [3,4]. During the synthesis process, the formation of trace amounts of binary/ternary compositions (i.e., undesirable secondary or impurity phases consisting of selenides, oxides, carbonates, etc.) may occur. These trace amounts of impurity phases may form at the nascent absorber surfaces, which could negatively affects the photovoltaic conversion efficiencies of solar cells [5-7]. Therefore, prior to the deposition of the CdS buffer layer, there is a need to clean the CIGSSe or CZTSSe surfaces to remove any possible traces of such impurities.

Abstract: Interface performance investigations of turbine rotor alloy (30Cr₂MoV) in 0.01M Na₂MoO₄ have been performed by means of Electrochemical Impedance Spectroscopy (EIS) under step potential change conditions. A general equivalent circuit was employed to analysis the polarization behavior of that turbine rotor. It has been shown that EIS measurements under potentiodynamic conditions allow simultaneous investigation of changes in interface structure, ions transport process through the interface and electrode process kinetics on interface. The result verified the adsorption principle on metal passivation.

Abstract: The influence of molybdenum and aluminum on the corrosion resistance of the Ti and other Ti-based biomedical implant alloys under simulated physiological conditions is presented. Ti and its alloys Ti-10Mo and Ti-10Mo-10Al were studied. The electrochemical impedance spectroscopy technique was used and the experimental results were compared with those obtained by potentiostatic and potentiodynamic techniques. All the measurements were made in Ringer ́s solution at different pH and at different potentials as E_corr, -650, -500, 0, +200 and +400 mV vs SCE. It was evident that Mo improved passivity and limited the active corrosion of the β-phase of Ti while Al enrichment of the α-phase was found to be detrimental to the passivity and corrosion resistance of Ti. In most experimental conditions, the passive film is formed by TiO₂, Ti₂O₃ and TiO. When pH is very low, thermodynamically stable state of Ti is titanium anion Ti³⁺.

Abstract: The corrosion cracking of Shielded wire could result in protection equipments and automatic devices failing to work, which seriously affects the normal operation of the grid [1]. Therefore, researching the corrosion of Shielded wire has an important meaning. This article, through measurements of the polarization curve of the shield, researched the corrosion rate of different spray time and treatments, and came to a conclusion that the corrosion resistance after passivated by 823 preservatives is higher than before it.

Abstract: We propose a novel surface passivation of InP, to obtain the strong luminescence property and completely remove the surface state. InP is passivated by (NH4)₂S solution, then treated by rapid thermal annealing (RTA) at different temperatures. Compared with unannealing sample, the PL intensity is increased to 1.7 times. We adopt atomic layer deposition (ALD) of Al₂O₃ avoiding oxidizing gradually.

Abstract: Aluminium alloys are used for a large variety of safety relevant applications for example in the automotive and aviation industries. With the introduction of high strength but possibly less corrosion resistant alloys it is essential to determine if an enhanced sensitisation against corrosion comes into effect under simultaneous mechanical and corrosive loading. Within this work corrosion fatigue tests under constant and variable amplitude loading were carried out on aluminium alloys established for chassis applications such as EN AW-5018 with slightly elevated magnesium content (AlMg3.5Mn), EN AW-6082-T6, EN AW-6110A-T6 and EN AC‑42100-T6 as well as alloys sensitised to corrosion. Sensitisation was obtained by a borderline (17 h at 130 °C) and an excessive (500 h at 130 °C) thermal ageing treatment and elevated copper contents for the forged and cast alloys. Aforementioned alloys and material conditions were assessed concerning the impact of mechanical loading conditions such as load signal type (sinusoidal and square-wave signal), strain rate and load spectra on the damaging process and on corrosion fatigue life. Fatigue tests were complemented by simultaneous determination of electrochemical characteristics as well as the type of corrosion by metallographic investigations.

Abstract: Silicon nanowires (SiNWs) based solar cells are passivated by native oxide and SiN_x bi-layer. In comparison with cells passivated by SiN_x single layer, bi-layer passivation exhibits higher effective minority lifetime, illustrating a better surface passivation effect, which leads to a gain of internal quantum efficiency in the short wavelength range, a better output performance with an increase of 0.16% in efficiency. The data obtained from this work is fundamental and has some reference value for future studies.

Abstract: A novel facet coating technology is presented by studying catastrophic optical mirror damage mechanism of semiconductor laser. In this technology, semiconductor laser are cleaved in the air, and the surface oxide layer is removed with a low energy ion source, immediately flowed by coating the facet with 20nm of thin ZnSe passivation layer. The function of the passivation layer is to protect semiconductor laser facet, and prevent impurity particles diffusing to the facet. Finally the facet is coated with oxidative optical film. The test results of semiconductor laser output power show that output power with the coated ZnSe passivation layer method is 12% higher than coated Si passivation layer, and 36% higher than that coated oxidative optical film. The device coated oxidative optical film is failed when current is 4.1A, and the device coated with Si passivation layer is failed when current is 4.8A, the final failed of the device is coated ZnSe passivation layer. In conclusion, the method of coated ZnSe passivation layer on the semiconductor laser facet can effectively prevent the catastrophic optical mirror damage, and increase the output power of semiconductor lasers.