Composition Of Oxide Layer Research Articles

High-temperature stability and decoding of large field-of-view observable color codes prepared by femtosecond laser on titanium alloy

This study reported on the large field-of-view observable color code obtained by femtosecond laser-induced oxidation on titanium alloy. The simulation results showed that simultaneous roughening of the oxide layer and metal layer could effectively increase the color rendering range of the structural colors. Based on the diffraction effect of the diaphragm, the laser energy was periodically distributed. In addition, the simultaneous formation of the oxide layer and the micro/nano structures was attributed to the periodic distribution of laser energy. Compared to the substrate, the increase in oxygen content of the colored area ranged from 5 % to 11 %, indicating that the infiltration of oxygen inside the material was increased. Additionally, the surface chemical composition of the upper oxide layer of the colored areas was TiO2. XRD analysis showed that laser-induced surface coloring did not affect the phase composition of the alloy except for the generation of a small amount of carbon. Moreover, different scanning numbers affected the color difference ΔE∗ ab of adjacent scanning speeds. High-temperature experiments showed that the color code prepared by femtosecond laser-induced oxidization of titanium alloy was reliable in use at less than 100 °C. Since the color code could still be clearly obtained at a field angle of 77.3°, the angle insensitivity of the color code could be effectively improved by selective roughening of the oxide layer prepared by femtosecond laser. Furthermore, the decoding of color code was the inverse encoding process. Therefore, the angle insensitivity of the color code was improved and the temperature range of the structural color was clarified.

Fatty Imidazolines as a Green Corrosion Inhibitor of Bronze Exposed to Acid Rain

Acid rain is one of the primary corrosive agents on bronze exposed to the atmosphere. Bronze naturally forms a layer of oxides on its surface called patina, protecting it from corrosion. However, when exposed to acid rain, this layer dissolves, making it necessary to use a corrosion inhibitor or stabilize the patina. This study investigated fatty imidazolines derived from agro-industrial waste bran as a corrosion inhibitor of SAE-62 bronze in simulated acid rain (pH of 4.16 ± 0.1). Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve (PC) measurements were used to evaluate corrosion inhibition efficiency, which was 90% for an inhibitor concentration of 50 ppm. The EIS measurements showed that the fatty imidazolines formed a protective film that stabilized the patina on the bronze surface to a certain extent by hindering the charge transfer process. SEM–EDS analyzed the morphology and composition of the protective oxide layer. The results were complemented by Raman spectroscopy and XRD analysis, indicating cuprite, tenorite, cassiterite, and covellite in the patina layer formed on the bronze surface. The SEM analysis showed that the protective coating on the bronze surface was homogeneous using a 50-ppm inhibitor concentration. The XRD analysis suggested the presence of an organic complex that stabilizes the corrosion products formed on the bronze surface.

Research on the oxidation process of micro-boron below the melting point temperature

The ignition and combustion characteristics of boron and the energy release rate of boron-based fuel are closely related to the surface oxide layer of boron. To understand the oxidation process of boron below its melting point, the slow oxidation process of boron under different temperature and humidity storage conditions and the fast oxidation process under high-temperature conditions were investigated. The results indicate that the surface oxide layer mainly comprises boron (B), boron suboxides (BxOy), and boron trioxide (B2O3). When the degree of oxidation is low, BxOy and B are the main components. After deep oxidation, BxOy almost disappeared. The thickness and composition of the surface oxide layer vary with changes in environmental temperature, humidity, and aging time. The effect of temperature increase on the growth rate of the oxide layer thickness is significantly greater than that of moisture. With the prolongation of boron aging treatment time, the onset, end, and maximum weight gain rate temperatures of the boron thermal oxidation process all slightly decrease. As the ambient temperature increases, the formation of the oxide layer transitions from a unidirectional diffusion mechanism of oxygen into the interior of boron particles to a bidirectional diffusion mechanism of molten oxide and oxygen.

Improved lifetime of a pulsed electric field (PEF) system-using laser induced surface oxidation

In this research, we explore the possibility and effectiveness of using laser-induced surface oxidation methods to enhance the durability and effectiveness of PEF (Pulsed Electric Field) systems. Despite advantages over thermal pasteurisation, PEF faces challenges like electrode corrosion and biofouling, hindering its adoption. This research introduces laser-induced oxidation to mitigate metal ion release during PEF, directly targeting electrode alteration. Our examination adopts a comprehensive method, integrating Design of Experiments (DoE) parameter sets for PEF trials, morphological analysis, evaluation of metal ion release via Inductively Coupled Plasma Quadrupole Mass Spectrometry (ICP-QMS), waveform capture utilizing a Data Acquisition (DAQ) system, electrochemical assessment via impedance spectroscopy, and examination of oxide layer composition employing X-ray photoelectron spectroscopy. Pulse waveform characteristics shows the intricate relationship between PEF processing parameters with metal ion release, alongside XPS analysis providing insights into surface chemistry. Optimized results show a three-fold reduction in metal ion release post-PEF, with laser-treated samples outperforming untreated stainless steel due to selective surface chemistry alteration, notably an increased Cr/Fe ratio, reducing harmful elements. This study highlights laser-induced oxidation as a practical solution for enhancing PEF electrode performance and reducing metal ion release, addressing key challenges in PEF technology. It advances sustainable food processing, promising extended PEF system lifespan while maintaining efficiency and product quality.

Low-temperature oxidation behavior and mechanism of hot-dip Al and Al[sbnd]Si coatings on Mo substrate at 600 °C in static air

The hot-dip Al and AlSi coatings are synthesized on Mo substrate at different temperatures. The microstructure and low-temperature oxidation behavior both of the coatings are investigated. The results indicate that hot-dip Al coating is mainly made up of an Al4Mo outer layer and an Al8Mo3 interface layer, while the hot-dip AlSi coating is consists of a Mo(Si, Al)2 inner layer and AlSi alloy outer layer containing Mo(Si, Al)2 grains. After exposed at 600 °C for 40 h, a large number of cracks initiate on surface and inside of the hot-dip Al coating, its mass gain per unit area (Δm) reach to 10.32 mg/cm2, and the RSa (average surface roughness) and Sdr (surface area growth rate) values increase from 0.216 μm and 6.602% before oxidation to 1.214 μm and 35.297%, respectively. During the oxidation process, the structure of the hot-dip AlSi coating is preserved intact, and almost no cracks are observed in the coating. After oxidized at 600 °C for 150 h, the Δm of hot-dip AlSi coating is only 1.56 mg/cm2, and the RSa and Sdr values increase from 0.458 μm and 7.083% to 1.509 μm and 43.586%, respectively. Besides, the oxidation rate constant (Kp) of hot-dip Al and AlSi coatings are 7.42 × 10−4 and 4.47 × 10−6 mg2·cm−4·s−1, respectively, and the latter is only 6.17 × 10−3 times than that of the former. The excellent oxidation resistance of hot-dip AlSi coating is attributed to its small grain size, stable and dense coating structure, and complex oxide layer composition.

Exploring the Impact of Potential, Ammonium Fluoride Concentration, and Anodization Time on the Structure, Surface Characteristics, and Corrosion Resistance of Nanotubular Titanium Oxide Coatings on Biomedical Alloy Ti-6Al-4V ELI

The current research delves into assessing the impact of applied potential, ammonium fluoride concentration, and anodization duration on the structural, phase compositional, microhardness, and surface roughness attributes of nanotubular titanium oxide coatings on anodized Ti-6Al-4V ELI. A meticulous experimental design was executed to systematically investigate the varied effects of these factors. Scanning electron microscopy (SEM) unveiled the presence of well-defined titania nanotubes on the surfaces of the anodized specimens. X-ray diffraction (XRD) analysis discerned the composition of the nanotubular oxide layer, revealing the presence of both anatase and a mixture of anatase and rutile phases contingent upon the anodization parameters. Notably, surface microhardness, surface roughness, and corrosion resistance manifested noticeable variations in response to alterations in applied voltage, NH4F concentration, and anodization duration within the designated experimental ranges.

Oxidation Behaviour of Fe-28Al-5Si at.% Alloyed with Ti and Mo

AbstractThe high-temperature oxidation behaviour of Fe-28Al-5Si, Fe-28Al-5Si-2Mo and Fe-28Al-5Si-2Ti (in at.%) was investigated. Cyclic oxidation tests of iron aluminides were performed at 900°C and 1100°C. The oxidation kinetics and oxidation behaviour (by measuring of total weight gain, etc.) were described. The structure of the alloys’ surfaces after oxidation, as well as the composition and morphology of oxide layers, was analysed by optical microscopy, scanning electron microscopy, SEM–EDS and X-ray diffraction. The beneficial effect of alloying with titanium or molybdenum on the oxidation resistance of Fe-Al-Si-based alloys was observed at temperatures of 900°C and 1100°C. Titanium and molybdenum suppress the formation of eutectic regions of the secondary phase in the structure, which preferentially oxidize. Therefore, a thin and compact alumina layer (only minor amounts of iron oxides and ZrO2) formed on the surface of Fe-28Al-5Si-2Mo and Fe-28Al-5Si-2Ti at 900°C. These alloys maintain low weight gains even at a temperature of 1100°C. On the other hand, alloy Fe-28Al-5Si contains a high number of eutectics-like areas, which causes ingress of the oxidation (selective oxidation of eutectic areas) and breakaway oxidation is observed at 900°C and 1100°C, respectively.

HEAT RESISTANCE OF CORROSION-RESISTANT STAINLESS STEEL CRNI65MWU AFTER VARIOUS TYPES OF FULL ANNEALING

The article discusses the influence of additional heat treatment of corrosion-resistant steel CrNi65MWU on increasing its heat resistance, as well as on changing the chemical composition of the protective oxide layer formed on the surface. The relationships between heat treatment modes and changes in the corrosion rate of selected steel under operating conditions in glass-forming production are shown. Research has also been carried out on the direct interaction of the melt of various types of glass with a heat-treated steel surface.

Synergistic Amelioration of Osseointegration and Osteoimmunomodulation with a Microarc Oxidation-Treated Three-Dimensionally Printed Ti-24Nb-4Zr-8Sn Scaffold via Surface Activity and Low Elastic Modulus.

Biomaterial scaffolds, including bone substitutes, have evolved from being primarily a biologically passive structural element to one in which material properties such as surface topography and chemistry actively direct bone regeneration by influencing stem cells and the immune microenvironment. Ti-6Al-4V(Ti6Al4V) implants, with a significantly higher elastic modulus than human bone, may lead to stress shielding, necessitating improved stability at the bone-titanium alloy implant interface. Ti-24Nb-4Zr-8Sn (Ti2448), a low elastic modulus β-type titanium alloy devoid of potentially toxic elements, was utilized in this study. We employed 3D printing technology to fabricate a porous scaffold structure to further decrease the structural stiffness of the implant to approximate that of cancellous bone. Microarc oxidation (MAO) surface modification technology is then employed to create a microporous structure and a hydrophilic oxide ceramic layer on the surface and interior of the scaffold. In vitro studies demonstrated that MAO treatment enhances the proliferation, adhesion, and osteogenesis capabilities on the scaffold surface. The chemical composition of the MAO-Ti2448 oxide layer is found to enhance the transcription and expression of osteogenic genes in bone mesenchymal stem cells (BMSCs), potentially related to the enrichment of Nb2O5 and SnO2 in the oxide layer. The MAO-Ti2448 scaffold, with its synergistic surface activity and low stiffness, significantly activates the anti-inflammatory macrophage phenotype, creating an immune microenvironment that promotes the osteogenic differentiation of BMSCs. In vivo experiments in a rabbit model demonstrated a significant improvement in the quantity and quality of the newly formed bone trabeculae within the scaffold under the contact osteogenesis pattern with a matched elastic modulus. These trabeculae exhibit robust connections to the external structure of the scaffold, accelerating the formation of an interlocking structure between the bone and implant and providing higher implantation stability. These findings suggest that the MAO-Ti2448 scaffold has significant potential as a bone defect repair material by regulating osteoimmunomodulation and osteogenesis to enhance osseointegration. This study demonstrates an optional strategy that combines the mechanism of reducing the elastic modulus with surface modification treatment, thereby extending the application scope of β-type titanium alloy.

A new insight into the mechanism of Ce enhancing high temperature oxidation resistance of hot-formed steel

In this paper, the effect of Ce addition on high temperature oxidation behavior of hot-formed steel was studied by high temperature oxidation experiment. The structure and phase composition of surface oxide layer of specimens with different Ce content were systematically analyzed by SEM, EDS, XPS. The results showed that the addition of Ce promoted the formation of a dense oxide layer during the initial oxidation stage, and effectively weaken the oxidation degree of the steel surface. Meanwhile, the Ce2O3 particles segregation in Si–Cr rich phase reduced the concentration of vacancy defects in oxide layer and enhanced the adhesion between oxide layer and substrate. After Ce addition, the surface oxidation resistance of hot-formed steel is significantly improved.

High-Temperature Oxidation of Boiler Steels at 650 °C

This study presents a comprehensive investigation of the formation, composition and behaviour of oxide layers during the high-temperature oxidation of four different steel alloys (16Mo3, 13Cr, T24 and P91) at a uniform temperature of 650 °C. The study is aimed at assessing the oxidation damage due to short-term overheating. The research combines CALPHAD (CALculation of PHAse Diagrams) calculations, thermogravimetric analysis (TGA) and advanced microscopy techniques, including scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), to elucidate the complex mechanisms controlling oxidation kinetics and oxide layer development. CALPHAD calculations were used to determine the thermodynamically stable phases for each steel type at 650 °C and different oxygen activities. The results showed different phase compositions, highlighting the importance of the chromium content in steel for the formation of oxide layers. The different oxidation kinetics and oxide layer compositions are presented and associated with the increased risk of material degradation due to overheating. These results have significant implications for industrial applications, mainly the susceptibility to oxidation of low-alloyed steels like 16Mo3 and 13 Cr and contribute to a deeper understanding of oxidation processes in steels.

The influence of Y addition on oxide layers of 15-15Ti-Y steel exposed to static Pb-Bi alloys with containing oxygen

The corrosion behavior was investigated in a static environment of liquid Pb-Bi eutectic (LBE) saturated with 10−6 wt.% oxygen at 500°C and 600 °C. The investigation focused on 15-15Ti and 15-15Ti-Y austenitic stainless steel specimens, exposing them for up to 5000 h. Additionally, both steel types were analysed after exposure to liquid Pb40Bi60 alloy with 10−6 wt.% oxygen concentration at 600 °C for 2000 h. The main objective was to investigate the structure and composition of oxide layers formed during corrosion, with specific attention to the role of yttrium (Y) in influencing corrosion behavior. The addition of Y resulted in promoting denser spinel oxide layer formation, which exhibited enhanced properties in reducing outward cation diffusion, inward oxygen diffusion, and PbBi penetration into the steels.

Heterogeneous oxidation behavior and kinetic mechanisms of SiBCN ceramic with structure of MA-SiBCN coated by PDCs-SiBCN

In this study, SiBCN ceramics with a structure of three-dimensional PDCs-SBCN network structure coated MA-SiBCN (MA@PDCs-SiBCN) were fabricated, which significantly improved the sintering activity and oxidation performance. The effect of MA@PDCs-SiBCN structure on oxidation behaviors and kinetics of oxide layer growth of the SiBCN ceramics at 1500 ℃ was investigated, indicating that the significantly improved oxidation resistance is attributed to the different heterogeneous oxidation behaviors, especially in the initial stage. Therefore, the heterogeneous oxidation behaviors and kinetic laws of different phases in MA@PDCs-SiBCN ceramics at different temperature ranges and their effects on structural evolution and oxide layer composition were analyzed by comparison with the MA-SiBCN ceramics. The significantly improved oxidation resistance of MA@PDCs-SiBCN ceramics should be attributed to the inhibition of MA@PDCs-SiBCN structure to heterogeneous oxidation, especially the consumption of t-C, and different oxide layer composition generated from microcrystalline structure rather than nanocapsule-like crystalline structure.

Evaluation of the Effect of Varying Percentage of Recast Metal–Ceramic Alloy on Bond-strength and Oxide-layer Composition using SEM and EDX: An In Vitro Study

Evaluation of the Effect of Varying Percentage of Recast Metal–Ceramic Alloy on Bond-strength and Oxide-layer Composition using SEM and EDX: An In Vitro Study

Achieving low wear in a complex concentrated alloy CrFeNiNb with multi-phase hierarchical microstructure

We propose a strategy to achieve low wear in a complex concentrated alloy (CCA) CrFeNiNb with multi-phase hierarchical microstructure. The CCA comprises a matrix of ultrafine-grained hexagonal close-packed (HCP) Laves phase (80.3 vol%), a secondary face-centered cubic (FCC) phase (18.3 vol%), a minor amount of (Nb,Cr)-oxides and a trace amount of uniformly dispersed nanoscale precipitates. The CrFeNiNb CCA exhibits an ultrahigh hardness of 993 (±22) HV and an extremely low wear rate of 7.4 (±0.6) × 10−6 mm3/(N·m) when sliding against a silicon nitride (Si3N4) ball. To elucidate the wear mechanism, we characterized the morphology, chemical composition and cross-sectional microstructure of the wear track. The results indicate that the cracked oxide layer, subgrain formation in the FCC phase, and the Shockley partial and full dislocations-triggered intragranular prismatic slip in the C14 Laves phase synergically contribute to the exceptional wear resistance. Furthermore, we conducted a detailed analysis of the chemical composition and crystal structure of the cracked oxide layer, along with a compressive discussion of the subsurface deformation of HCP/FCC phases. These findings offer significant insights into designing wear-resistant alloy through the formation of multi-phase hierarchical microstructure.

Anodic Behaviour of NixFeyCu5 and NixFeyCu20 in Potassium-Rich Naf-KF-AlF3-Al2O3 Melts

Using inert anode technology to produce aluminium would substantially reduce the aluminium industry's carbon footprint. Replacing the Hall-Héroult process with an alternative process based on vertical electrode cell (VEC) design using inert anodes and wettable cathodes is a promising alternative, but must be developed to be economically viable at scale. Three material types have been explored as inert anodes: metals, cermets and ceramics. Metallic anodes have been widely studied for their attractive properties, such as superior mechanical strength, high electrical conductivity and ease of fabrication. Of metallic anodes, Cu-Al, Ni-Fe and Ni-Fe-Cu-based alloys are the most commonly examined alloy systems for anode applications. It is also necessary to use low-temperature melts during the electrolysis process to ensure that the anodes are not damaged. In NaF-KF-AlF3 melts, increasing the KF content in the mixture would reduce the liquidus temperature and increase the alumina solubility in the melt.In this work, we examine the anodic behaviour of NixFeyCu5 and NixFeyCu20 electrodes, without prior surface treatment, in potassium-rich NaF-KF-AlF3 melts at 770°C. The cryolite ratio (xNaF+xKF/xAlF3) and potassium ratio (xKF/xKF+xNaF) of the melt used for the studies are 1.3 and 0.7, respectively. Electrochemical techniques such as chronopotentiometry, chronoamperometry and linear sweep voltammetry were performed to examine the anodic behaviour of these metallic anodes under an N2 atmosphere.Figure 1 shows the steady-state anodic polarisation curves on NixFeyCu5 and NixFeyCu20 anodes before and after galvanostatic polarisation with an applied current density of 0.5 Acm-2 for 120 minutes. It can be noted that the anodic potential at the same current density is more for the polarised anode compared to the non-polarised in both cases. This is due to the formation of a stable oxide layer during the galvanostatic polarisation of the anode. Oxidation of the anode is expected instead of fluoridation when the melt is saturated with alumina. The stabilisation of anodic current can be seen between 1.9 and 2.4 V. This stabilisation corresponds to the passivation of anodes due to the oxide layer formation. A rapid increase in the current after 2.4 V is due to the oxygen evolution reaction. The anodic current density in the passive region is much lower in anodes with Cu 20%, meaning a more protective layer is formed. After the galvanostatic polarisation of the anode, anodes were examined using scanning electron microscopy to understand the oxide layer composition. Anodes performed stably in potassium-rich melts, and Cu content plays a vital role in the anode's performance. Figure 1. Stationary state polarisation curves of NixFeyCu5 and NixFeyCu20 anodes before and after the polarisation at 0.5 A cm-2 Figure 1

High temperature oxidation behavior of porous MoAlB ceramic from 800 °C to 1100 °C in air

MoAlB possesses the characteristics of both metals and ceramic materials, which has attracted extensive attention due to its excellent high-temperature oxidation resistance. For this reason, porous MoAlB is considered applicable to the practice of filtration under harsh environment. In this study, the high-temperature oxidation behavior of porous MoAlB ceramics is systematically studied at the temperatures ranging from 800 to 1100 °C. According to the results, the porous MoAlB exhibits good oxidation resistance at a maximum temperature of 1000 °C. The oxidation kinetics of porous MoAlB can be divided into three stages, and the estimated activation energies of the three stages are 253.83 kJ·mol−1, 367.48 kJ·mol−1 and 317.84 kJ·mol−1, respectively. In the stable stage at 1000 °C, the quadratic mass gain per unit area shows linearity over time, and the oxidation rate of porous MoAlB reaches 37.31 mg2·cm−4·h−1. As revealed by the analysis of the composition and microstructure of oxide layers, the main components of the oxide layer include MoO3, MoO2, Al2O3, B2O3. With the extension of oxidation time, the content of Al2O3 in the oxide films increases. The average pore size, permeability and open pore porosity of porous MoAlB show a trend of first decreasing and then tending to be stable. In addition, a discussion is conducted on the high-temperature oxidation mechanism of porous MoAlB.

Understanding the enhanced corrosion performance of two novel Ti-based biomedical high entropy alloys

The microstructure and corrosion behavior of two novel biomedical high entropy alloys (HEA)s, namely Hf27Nb12Ta10Ti23Zr28 and Hf30Nb14Ta10Ti28Zr18 that were previously designed utilizing machine learning, were investigated in depth. The microstructure of the alloys was determined to be dendritic, with some elemental segregations governed by the solidification kinetics occurring during the arc-melting process. Static immersion experiments were carried out in artificial saliva (AS) and simulated body fluid (SBF) to investigate the ion release behavior of the HEAs and reveal the dissolution kinetics of the passive film forming on the surface. The composition of the corresponding surface oxide layers was examined using X-ray photoelectron spectroscopy, which provided detailed insight into the stability of passive oxide layers and sub-oxide formation. Potentiodynamic polarization experiments performed in AS and SBF at 37 ºC demonstrated that both HEAs exhibit superior corrosion behavior as compared to the CoCrMo alloy, one of the conventional metallic implant materials of choice.

Effect of Concentration of SiO2 Nanoparticles in the Electrolyte on the Composition and Properties of Oxide Layers Formed by Plasma-Electrolytic Oxidation on Silumin AK7

Effect of Concentration of SiO2 Nanoparticles in the Electrolyte on the Composition and Properties of Oxide Layers Formed by Plasma-Electrolytic Oxidation on Silumin AK7

Role of Graphene in Oxidation of Underlying Cu Substrates Elucidated through Angle-Resolved X-ray Photoelectron Spectroscopy: Implications for Corrosion Protection of Graphene/Cu

The role of single-layer graphene in the oxidation process of Cu substrates underlying graphene remains controversial, and the evolution of interfacial oxide layers of graphene/Cu (Gr/Cu) over time has not been reported. Qualitative and quantitative studies of the interfacial oxide layer of Gr/Cu samples upon exposure to ambient conditions for long periods are crucial for revealing the role of graphene in the oxidation process of underlying Cu substrates, so as to further promote the research on corrosion protection of copper surfaces. Angle-resolved X-ray photoelectron spectroscopy (ARXPS) is a practical characterization technology for studying the structure, composition, and thickness of interfacial oxide layers. In this work, we propose an extended model to elucidate the role of graphene in oxidation of underlying Cu substrates through ARXPS study of evolution of interfacial oxide layers. The thickness of an interfacial oxide layer is positively correlated with air exposure time, and it is thinner than that of an oxide layer on a Cu surface; the fractional coverage of the island-like interfacial oxide layer is within the range of 0.4–0.6. For Gr/Cu samples exposed to ambient conditions for less than 6 months, graphene can inhibit the formation of Cu2O, whereas it promotes the formation of CuO in the interfacial oxide layer for long-term oxidized Gr/Cu samples (≥12 months), leading to the embedded structure of the interfacial oxide layer. The results of this study can serve as a guide for the corrosion protection of copper-based devices.