Surface Morphology Of Oxide Layers Research Articles

Investigation of correlation of oxide layer surface morphology and magnesium degradation using a gas atmosphere dependent nanosecond laser processed model

In biomedical applications, degradation behavior of Magnesium (Mg) and its alloys is crucial for its outcomes. Various methods have been adopted to regulate Mg metals degradation, in which oxide layer generation has been considered to be a reliable strategy. However, correlation of magnesium oxide layer surface morphology and magnesium degradation is difficult to clarify due to interruption of oxide layer thickness and co-effect of other surface characteristics. In this work, Mg samples with two distinctive oxide layer morphology were prepared by nanosecond laser processing under N2 and CO2 atmospheres, coupled with essential surface and cross-section characterizations using SEM, AFM, TEM, XPS, XRD, and contact angle instrument. Furthermore, oxide layer morphology dependent Mg degradation behavior was investigated by electrochemical experimental, hydrogen precipitation, and pH tests. Results indicated that by changing laser treatment processing gas atmosphere, magnesium oxide morphology generated on sample surface could be tailored while maintaining consistency in thickness and composition. Larger particle size, surface roughness and wettability of magnesium oxide can decrease degradation rate.

Effect of surface topography on injection joining Ti alloy for improved bonding strength of metal-polymer

Titanium matrix fiber-reinforced plastic composites had attracted increasing interest in marine and other fields because of their excellent mechanical and corrosion resistance. However, the interfacial bonding strength between the titanium matrix and the plastic is an important factor limiting its wide application. In this paper, the surface of titanium alloy TC4 (Ti-6Al-4V) was anodized to form an oxide layer with a 1–2 μm crack structure on the surface of titanium alloy. Then the titanium alloy was combined with plastic polyphenylene sulfide (PPS) by direct injection molding. The results show that different oxide layer structures on the surface of titanium alloy, which can be obtained by different anodizing times and anodizing temperatures, can obtain TC4-PPS composites with different bond strengths. The maximum bond strength of TC4-PPS composites was 16.8 MPa when the anodizing temperature was 90 °C and the oxidation time was 30 min. We also discussed the effect of titanium alloy oxide layer surface morphology, wettability, roughness, composition, failure mode, and glass fiber on the bonding strength, which is important for expanding the application of titanium alloy and plastic composite.

Graphene tunnel junctions with aluminum oxide barrier

We report a development of graphene tunnel junctions made by chemical vapor deposition grown graphene and sputtered aluminum insulating by an in-situ grown aluminum oxide. The thin oxide layer formed in between the metal layer and the two-dimensional material is a crucial part of a tunnel junction. We characterized surface morphology of oxide layers and studied tunneling spectra of lead and silver tunnel junctions to estimate the quality of the aluminum oxide. The Brinkman-Rowell-Dynes model was applied to fit the conductance-voltage plots to calculate the thickness of oxide layers. Junctions with graphene both on bottom and on top were fabricated and their tunneling properties were characterized after exposure to air for weeks to test time stability. Furthermore, the resistances of graphene tunnel junctions with aluminum oxide formed naturally and in an oxygen atmosphere were studied. Our results demonstrate that in-situ aluminum oxide is an effective barrier for graphene tunnel junctions. The methods of barrier formation enable the realization of more tunnel devices and circuits based on graphene.

Characteristic of Oxide Layers Obtained on Titanium in the Process of Thermal Oxidation

Abstract Thermal oxidation in air may be one method to improve the properties of titanium and its alloys through its influence on the structure and properties of the material’s surface layer. This paper presents a description of oxide layers obtained on the surface of Grade 2 titanium as a result of oxidation at temperatures of 600 and 700°C. On the basis of kinetic curves, it was found that the intensity of oxide layer growth increased with oxidation temperature. Studies of the surface morphology of oxide layers showed that the size of the formed oxide particles was greater following oxidation at 600°C. The obtained layers were subjected to X-ray phase analysis and microhardness measurements. Irrespective of oxidation temperature, the scale consisted of TiO2 oxide in the crystallographic form of rutile and of Ti3O oxide. The hardness of oxide layers amounted to around 1265 HV and was more than 4 times higher compared to the material in i ts initial state.

Effects of Processing Parameters of Oxide Layer in Ultrasonic Vibration and Electrolytic In-Process Dressing Combined Grinding

In order to study the states of oxide layer under different pre-dressing process conditions in ultrasonic vibration and electrolytic in-process dressing combined grinding. The effects of electrical parameters, wheel speed, ultrasonic vibration on the oxide layer are investigated with indicators of oxide layer surface morphology and thickness characteristics. The results indicate that the oxide layer thickness increases with the decrease of inter-electrode gap and the increase of duty ratio with pre-dressing time. The effect of ultrasonic vibration cause thinning of the oxide layer. Oxide layer surface morphology allowing processing requirements are obtained by duty cycle of 5μs: 5μs, electrode gap of 0.3mm, wheel speed of 3200 r/min.

Modeling and control of Transparent Conducting Oxide layer surface morphology for improved light trapping

This work first introduces a kinetic Monte–Carlo simulation model for a two species thin film deposition process and demonstrates the use of feedback control, coupled with a suitable actuator design, in manufacturing thin films whose surface morphology has a structure that improves light trapping. This work is relevant in the context of a Transparent Conducting Oxide (TCO) thin film layer manufacturing used in thin film solar cells where it is desirable to produce thin films with precisely tailored surface morphology. Specifically, a two species thin film deposition process involving atom adsorption, surface relaxation and surface migration is initially considered and is modeled using a large-lattice (lattice size=40,000) kinetic Monte–Carlo simulation. Subsequently, thin film surface morphology characteristics like roughness and slope are computed with respect to different characteristic length scales ranging from atomic to the ones corresponding to visible light wavelength and it is found that a patterned actuator design is needed to induce thin film surface roughness and slope at visible light wavelength spatial scales, that lead to desired thin film solar cell performance. Then, an Edwards–Wilkinson type equation is used to model the surface evolution at the visible light wavelength spatial scale and form the basis for the design of a predictive feedback controller whose objective is to manipulate the deposition rate across the spatial domain of the process. The model parameters of the Edwards–Wilkinson equation are estimated from kinetic Monte–Carlo simulations and their dependence on the deposition rate is used in the formulation of the predictive controller to predict the influence of the control action on the surface roughness and slope throughout the thin film growth process. Analytical solutions of the expected surface roughness and surface slope at the visible light wavelength spatial scale are obtained by solving the Edwards–Wilkinson equation and are used in the predictive controller formulation and in the control action calculation. The controller is applied to the large-lattice kinetic Monte–Carlo simulation. Simulation results demonstrate that the proposed controller and patterned actuator design successfully regulate aggregate surface roughness and slope to set-point values at the end of the deposition.

High temperature oxidation of FeCrAl‐alloys – influence of Al‐concentration on oxide layer characteristics

AbstractThe superior high temperature oxidation resistance of FeCrAl alloys relies on the formation of a dense and continuous protective aluminium oxide layer on the alloy surface when exposed to high temperatures. Consequently, the aluminium content, i.e. the aluminium concentration at the alloy–oxide layer interface, must exceed a critical level in order to form a protective alumina layer. In the present study the oxidation behaviour of six different FeCrAl alloys with Al concentrations in the range of 1.2–5.0 wt% have been characterised after oxidation at 900 °C for 72 h with respect to oxide layer surface morphology, thickness and composition using scanning electron microscopy, energy dispersive X‐ray spectroscopy and Auger electron spectroscopy. The results show that a minimum of 3.2 wt% Al in the FeCrAl alloy is necessary for the formation of a continuous alumina layer. For Al concentrations in the range of 2.0–3.0 wt% a three‐layered oxide layer is formed, i.e. an oxide layer consisting of an inner alumina‐based layer, an intermediate chromia‐based layer and an outer iron oxide‐based layer. In contrast, the 1.2 wt% Al FeCrAl alloy is not able to form a protective oxide layer inhibiting extensive oxidation.

Effect of the preparation methodology on some physical and electrochemical properties of Ti/IrxSn(1−x)O2 materials

The aim of this work was to prepare electrodes based on the Ti/IrxSn(1−x)O2 composition, as well as test their stability toward the chlorine evolution reaction (ClER). To this end, two different preparation routes were investigated: thermal decomposition of polymeric precursors (DPP) and standard decomposition using isopropanol as solvent (SD/ISO). A systematic investigation of the structural, morphological, and electrochemical properties of the anodes with a nominal composition of Ti/IrxSn(1−x)O2, prepared through the two different methodologies, was carried out. The oxide layer surface morphology, microstructure, and composition were investigated by Energy Dispersive X-ray Spectroscopy (EDS) and Scanning Electron Microscopy (SEM) techniques prior to and after accelerated life tests. EDS analyses following total deactivation of the electrode gave evidence of a relatively large content of Ir in the coating. XRD results showed there was formation of solid solution between IrO2 and SnO2, and the degree of miscibility of these solutions is controlled by the preparation method. Thus, the DPP method led to phase separation and large interval of immiscibility between the oxides analyzed. On the other hand, the SD/ISO method led to formation of solid solution for all the investigated compositions. The SD/ISO method produced materials rich in Ir, so the electrode lifetime was much longer if compared with the DPP counterparts.

Characterization of RuO2 ­ Ta2 O 5 Coated Titanium Electrode: Microstructure, Morphology, and Electrochemical Investigation

A systematic investigation of the structural, morphological, and electrochemical properties of anodes with a nominal composition of 30:70; 50:50 and 80:20 atom %) was performed. The oxide layer surface morphology, microstructure, and composition were investigated prior to and after accelerated life test through energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy. EDS analyses following total deactivation of the electrode showed a relatively large content of Ru in the coating. X-ray diffraction results showed the formation of a solid solution between and Cyclic voltammograms of this system were registered in acidic solutions 0.5 mol dm−3) and they presented a well-defined peak attributed to the Ru(III)/Ru(IV) solid-state redox transition. The electrocatalytic activity shows a strong dependence on the content in the film. The stability of the electrodes toward oxygen evolution reaction was evaluated at using a current density of and a temperature of 80°C. A direct dependence between the electrode lifetime (LT) and present in the coating was observed. Upon changing for atom %) a considerable improvement (average of 54%) in the LT values of these oxides was obtained. This result is a good indication that the Ru/Ta system might be a promising coating to operate under severe conditions. © 2004 The Electrochemical Society. All rights reserved.

Low-Temperature Drain Current Characteristics in Sub-10-nm-Thick SOI nMOSFET's on SIMOX (Separation by IMplanted OXygen) Substrates

This paper describes specific features in low-temperature drain current and transconductance characteristics of thin silicon-on-insulator n-channel metal-oxide-semiconductor field effect transistors (SOI nMOSFET's) with a sub-10-nm-thick silicon layer and presents some simple analyses based on quantum mechanics. It is suggested that these features originate from the two-dimensional subband system in the thin SOI layer and its local deviation based on the local-deviated silicon layer thickness reflecting the buried oxide layer surface morphology of high-temperature-annealed SIMOX substrates.