Oxidation Resistance Properties Research Articles

A new nanocomposite membrane based on sulfonated polysulfone boron nitride for proton exchange membrane fuel cells: Its fabrication and characterization

Sulfonated polysulfone (SPSf) polymer is an alternative raw material in producing commercially used proton exchange membranes. On the other hand, hexagonal boron nitride (hBN) is one of the additives of interest for nanocomposite PEMs. In this study, nanocomposite membranes is fabricated and characterized with SPSf and hBN nanoparticles. The degree of sulfonation of the sulfonated polysulfone is determined by titration, and sulfonic acid bonds are investigated by Proton Nuclear Magnetic Resonance (1H NMR) analysis. SPSf is dissolved with dichloromethane, and hBN nanoparticles are added. After homogenizing the prepared solution with magnetic and ultrasonic stirrers, membranes are formed using Dr. Blade. 1H NMR, Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), X-Ray Diffractometer (XRD), and Thermogravimetric Analysis (TGA) analysis are examined the morphological, thermal, and organic compound structures of the membranes. Water uptake capacity, swelling ratio, proton conductivity, oxidative resistance, and mechanical properties of the membranes are determined. The highest water uptake capacity is obtained as 40.08 % in the membrane named SPSf-3 %hBN. Using hBN additive improved swelling ratio and thermal and mechanical strength properties. The proton conductivity values of polysulfone (PSf), SPSf, SPSf-1 %hBN, SPSf-2 %hBN, and SPSf-3 %hBN membranes are determined as 2.89, 6.84, 3.57, 10.8 and 5.12 mS cm−1, respectively. As a result of the analysis, it is observed that the nanocomposite membrane structure has both amorphous and crystalline homogeneous structure.

Synthesize and characterization of silver coated Ti powders from waste titanium chips by mechanical milling assisted electroless plating method

This study used an electroless silver (Ag) coating method on Ti powders obtained from waste turnings using mechanical milling, a recycling technique. Various parameters of Ag source and reducing agent ratios were utilized in the Ag coating processes. The results demonstrated that increasing the silver source and reducing agent ratios resulted in a more homogeneous and thicker Ag coating layer on Ti powders. The rise in the reduced silver ratio resulted in an increase in crystallite size compared to untreated particles, which was attributed to the reduction of residual dislocations in Ti through the presence of Ag. The amount of silver on silver-coated Ti powders ranged from 12.49 wt% to 24.4 wt%. Furthermore, an increase in the silver ratio significantly enhanced the oxidation resistance properties. The mass change with oxidation obtained from TGA analysis reduced from 26.31 wt% to 14.88 wt% with increasing silver coating layer on Ti powders.

Laser surface cladding of CoNiCrAlY as Bond Coat on INCONEL718 substrate for thermal barrier coating application

This study delves into laser surface cladding of CoNiCrAlY onto Inconel718 employing a 6.6 kW continuous wave diode laser with varying process parameters. The resulting microstructure, microhardness, and isothermal oxidation resistance are meticulously assessed. Laser surface cladding yields a defect free microstructure with the presence of gamma (γ), gamma prime (γ’) and beta (β) phases. There is negligible dilution at the interface with a minimum HAZ. The average microhardness of the clad zone ranges from 425 to 465 HV, increasing with increase in scan speed and decrease in power. The high temperature oxidation resistance property of the clad surface is superior to the same developed by high velocity oxy fuel spraying.

Polyaromatic Hydrocarbon-Functionalized 2D MXene-Based 3D Porous Antifouling Nanocomposite with Long Shelf Life for High-Performance Electrochemical Immunosensor Applications.

Affinity-based electrochemical (AEC) biosensors have gained more attention in the field of point-of-care management. However, AEC sensing is hampered by biofouling of the electrode surface and degradation of the antifouling material. Therefore, a breakthrough in antifouling nanomaterials is crucial for the fabrication of reliable AEC biosensors. Herein, for the first time, we propose 1-pyrenebutyric acid-functionalized MXene to develop an antifouling nanocomposite to resist biofouling in the immunosensors. The nanocomposite consisted of a 3D porous network of bovine serum albumin cross-linked with glutaraldehyde with functionalized MXene as conductive nanofillers, where the inherited oxidation resistance property of functionalized MXene improved the electrochemical lifetime of the nanocomposite. On the other hand, the size-extruded porous structure of the nanocomposite inhibited the biofouling activity on the electrode surface for up to 90 days in real samples. As a proof of concept, the antifouling nanocomposite was utilized to fabricate a multiplexed immunosensor for the detection of C-reactive protein (CRP) and ferritin biomarkers. The fabricated sensor showed good selectivity over time and an excellent limit of detection for CRP and ferritin of 6.2 and 4.2 pg/mL, respectively. This research successfully demonstrated that functionalized MXene-based antifouling nanocomposites have great potential to develop high-performance and low-cost immunosensors.

A novel high-Cr CoNi-based superalloy with superior high-temperature microstructural stability, oxidation resistance and mechanical properties

A novel high-Cr CoNi-based superalloy with superior high-temperature microstructural stability, oxidation resistance and mechanical properties

Lignin-enhanced wet strength and UV-Blocking properties of nanocellulose-based composite films obtained by casting/hot-pressing methods

We composited nanocellulose, lignin and polyvinyl alcohol (PVA) by using borax as a cross-linking agent, and prepared nanocellulose-based composite films by two simple and convenient methods of the casting and hot-pressing. Results showed that the molding method affected the film properties. The hot-pressing composite film exhibited smoother surface and tighter structures, while the casting one exhibited better stretchability. The composite films showed a good tensile strength (casting: 149.56 MPa; hot-pressing: 179.68 MPa). Due to the addition of lignin, the composite films were endowed with good UV-blocking capabilities, wet strength, oxidation resistance and bacteriostatic properties. The composite film has good application prospects in the field of food packaging and UV-shielding.

The structure and properties of high-entropy (MoTaNbZrHf)-Si-B coatings deposited by DCMS and HIPIMS methods using the multilayer target

This article reports the results of comparative studies of the composition, structure, high-temperature oxidation resistance, mechanical and tribological properties of (MoTaNbZrHf)-Si-B coatings prepared at an identical average power of 1 kW by direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HIPIMS). Switching from the DCMS to the HIPIMS mode is found to increase adhesion and crack resistance of the coatings and their wear resistance under friction sliding and cyclic impact conditions, as well as reduce the depth of oxidation at 1300 °C threefold. The record-breaking values of high-temperature oxidation resistance at 1500 °C are achieved due to formation of a surface film based on the borosilicate glass (a-Si:B:O) containing crystallites of the t-HfSiO4, o-Ta2O5, m-HfO2, and m-ZrO2 phases.

Fabrication of mechanically alloyed high entropy alloys (20-Fe-20Cr-20Ni-20Mn-20Ti) modified carbon paste electrode sensor for the cyclic voltammetric determination of methyl orange

We have successfully fabricated high entropy alloys (HEA) of composition 20-Fe-20Cr-20Ni-20Mn-20Ti by ball milling method for 20 h after optimizing the milling parameters. Generally, the HEAs are very popular for their multi-elemental cocktail effect and exhibit excellent high temperature oxidation resistance, high strength, electromagnetic, wear and corrosion resistance properties. But, HEAs also exhibit significant electrocatalytic properties due to their unique morphology, composition, and structure. Therefore, we have used planetary ball milled HEA powders for the electrochemical determination of methyl orange (MO). MO is recalcitrant and very difficult to degrade and can affect the humans as well as the environment. Therefore, we must determine the presence of MO. We have investigated the effect of scan rate, modifier and analyte concentration, and the pH variation on the anodic peak current (Ipa) of MO. The calculated active syrface area of bare carbon paste electrode (BCPE) and HEA-modified carbon paste electrode (HEA-MCPE) were found to be 0.041 cm2 and 0.137 cm2 respectively. We have obtained the maximum oxidation peak current for the 8 mg HEA-MCPE at a pH of 7.2 during the electrochemical oxidation of MO. The increased Ipa in basic medium is due to structural transformation of MO from quinoid form (in acidic medium) to azo structure (in basic medium). We have also calculated the number of electrons and the protons involved in the electrochemical reaction. The calculated values of detection limit (DL) and quantification limit (QL) of 8 mg HEA-MCPE was found to be 0.114 × 10−8 M and 0.38 × 10−8 M respectively.

Effect of Fe doped Co–Ni protective coatings on the oxidation behavior and electrical properties of SOFC alloy interconnect materials

In order to enhance the oxidation resistance and electrical properties of interconnects for solid oxide fuel cells (SOFCs), three Co–Ni alloy coatings with varying contents of Fe doping were prepared onto SUS 430 substrate using electroplating method and oxidized in air at 800 °C for 1000 h. The experimental results demonstrated that the alloy coating significantly enhanced both the oxidation resistance and electrical properties of the interconnect substrate. The multi-layer oxidation structure blocked Cr from diffusing outward. Notably, the (Co,Fe)3O4/(Ni,Co)O in the oxidized layer of 5% Fe doped Co–Ni coated steel completely transformed into (Fe,Co,Ni)3O4 spinel layer after long term oxidation, which had the lowest activation energy and the strongest ability of restricting oxygen diffusion inward. Thus, the 5% Fe doped Co–Ni coated steel showed superior oxidation resistance (kp = 8.76 × 10−14 g2 cm−4 s−1) and excellent electrical properties (ASR = 13.19 mΩ cm2) following oxidation for 1000 h.

Investigating the Age-Dependent behavior of MoS2-hBN nanohybrid additives on the rheological properties of diesel engine oil

This study utilizes Design of Experiment (DOE) to optimize the viscosity of MoS2-hBN nanolubricants, synthesized using a microwave synthesis platform that significantly reduces synthesis time and energy consumption compared to other methods. The investigation focuses on viscosity and aging characteristics, aiming to understand the relationship between nanolubricant viscosity and key factors: nanoparticle concentration, temperature, and shear rate. The study shows that the optimal concentration of MoS2-hBN nanoparticles is 0.05 wt%. At this concentration, when subjected to a shear rate of 200 (1/s) and a temperature of 100°C, the highest viscosity recorded is 12.87 mPa·s. In contrast, at 40°C and a shear rate of 50 (1/s), the lowest viscosity measured is 113.42 mPa·s. Experimental validation confirms the accuracy of the model predictions. The study also examines MoS2-hBN nanolubricant aging behavior under constant high-temperature conditions (100 °C for 120 h), providing insights into its thermal stability, tribological performance, oxidation resistance, and thermal conductivity properties. Compared to SAE20W40 base oil, the nanolubricant reduces friction and wear, forming a protective boundary film to mitigate surface damage. It exhibits enhanced oxidation stability, acting as a free radical scavenger, and improved thermal conductivity due to increased heat transfer efficiency facilitated by nanoparticles. These findings highlight the potential of MoS2-hBN nanolubricant for high-temperature applications, contributing to enhanced engine performance and durability.

Oxygen permeation mass transfer modeling and onion-like micromechanical modeling to predict the effect of multilayered interface on oxidation resistance and mechanical properties of composites

To predict oxidative damage of interfaces and fibers under high temperature aerobic environment and mechanical strength of composites before and after oxidation, oxygen permeation mass transfer modeling and onion-like micromechanical modeling of multilayered interface were proposed. The oxygen mass transfer theory and oxidation damage theory of PyC interface were used to establish the two models. The oxidative damage of PyC interface was extended to (PyC-SiC)n multilayered interface, and transformation of SiC phase and microcracks caused by thermal mismatch were also considered. The law of oxygen permeation mass transfer and the evolution of fiber oxidative damage in the “Carbon fiber/(PyC-SiC)n multilayered interface” region were revealed. The mechanical strength of composites under different interface layers was researched, resembling an onion-like wrapping in layers from the core outwards. Furthermore, Cf@(PyC-SiC)n/SiC(n = 1/2/3/4) composites were prepared by chemical vapor infiltration (CVI) method. The mechanical properties of the composites were tested before and after oxidation. A comparison was made between the experimental and predicted tensile strengths before and after oxidation. The predicted results of tensile strength were found to be in good agreement with the experimental ones. In addition, the results show that PyC-SiC multilayered interface has a positive effect on the tensile strength of the composites, mainly as the cracks are deflected and branched by the multilayered interface to promote the multistage pull-out of the fibers. With the increase of interface number, the oxygen diffusion path was lengthened and zigzagged, reducing the oxidative damage of fiber and interface.

Unveiling the oxidation mechanism of CrTaTiMo refractory medium-entropy alloys: A synergy of density functional theory and ab initio molecular dynamics

The demand for advanced materials capable of withstanding extreme high-temperature conditions has led to the development of novel High-Entropy Alloys (HEAs). Recent works indicate that forming a CrTaO4 protection layer gives HEAs excellent long-term oxidation resistance. In this study, the high-temperature oxidation resistance properties of CrTaTiMo Refractory Medium-Entropy Alloys (RMEAs) were assessed by Density Functional Theory (DFT) and ab initio Molecular Dynamics (AIMD). Through the oxygen adsorption and diffusion calculations, we demonstrated the preferential oxygen adsorption sequence on the surface of the RMEA as Ti, Ta, Cr, and Mo. Furthermore, our analysis identified the sites featuring Ta as subsurface atoms were the weakest locations for oxygen atom diffusion. The dynamic oxidation mechanism of oxygen molecules on CrTaTiMo RMEA was investigated by AIMD simulations. The results confirmed that the adsorption and dissociation of O2 molecules on the alloy surface. Additionally, the diffusion of the O atom took place at temperatures greater than 873 K and confirmed the O-attracting feature of Ta atoms. Moreover, electronic structure calculations confirmed the bonding of oxygen atoms with those four metal elements. This study could serve as a valuable reference for the strategic development of the CrTaTiMo-based RMEAs or RHEAs for high-temperature, long-term oxidation resistance applications.

The construction of structural defects in MoAlB thin films by leveraging the enhanced Kirkendall effect for improved infrared stealth performance

MoAlB, known for its exceptional oxidation resistance and anti-ablation properties, holds significant promise as a protective thin film for high-temperature components in military equipment. However, the high thermal conductivity of MoAlB poses a challenge to its compatibility with infrared stealth performance. In this study, structural defects were intentionally implanted into the MoAlB thin film by leveraging the amplified Kirkendall effect to hinder heat propagation. The results revealed that the MoAlB MAB phase thin film with a notable amount of edge dislocations was achieved by subjecting the post-annealed (Mo–B)/Al nanostructured multilayers (NMs) to an elevated temperature of 700 °C. The room-temperature resistivity of the thin film was 1.43 μΩ m. Furthermore, the infrared emissivity of the thin film was assessed within the mid-infrared wavelength range, ranging from 0.11 to 0.25. Simultaneously, the resulting thin film was found to possess a low thermal conductivity of 11.44 W m−1 K−1, consequently achieving excellent infrared stealth capability.

High temperature oxidation behavior and microstructure evolution of medium Mn steel

The phase transition, microstructure evolution and oxidation behavior of Fe-0.2C-12Mn-3Al-2Cu-xNi steel during the oxidation process for 120 min at 1050 °C-1200 °C were systematically studied. The twin boundaries will provide rapid channels for the oxygen atoms diffusion, while the (110) and (111) grain orientations show a low oxidation resistance property, which also then promote the oxygen atoms diffuse along grain boundaries. Cu and Ni enrichment areas were formed on the subsurface in the 1100 °C-1200 °C oxidation stage, which limited the ion diffusion rate on the subsurface and prevented the further growth of the oxide layer. The oxidation temperature, Mn concentration gradient and [CuNi] rich region on the subsurface contribute to multi-oxide layer structure: Mn deficient region, Mn rich region, transition layer and inner oxide layer. The Mn deficient region with rough surface is mainly composed of Fe2O3, Fe3O4 and Mn3O4, while the Mn rich region is mainly composed of FeO and MnO. The honeycomb transition layer and inner oxide layer is composed of FeO, MnO, MnAl2O4, and Al2O3.

Deposition voltages on the phase evolutions, microstructures, and oxidation behaviors of thermal-resistance Glass-MoSi2-SiC coating

ABSTRACT Due to the high oxidation activities at high temperatures, traditional SiC coating was difficult to act as an antioxidant material for ages. In this case, the multilayered Glass-MoSi2-SiC coating was fabricated on the C/C substrate, combined with hydrothermal electrophoresis deposition and simple embedding process. It was found that the composite obtained at 10 V performed outstanding combinations of oxidation resistance and thermal shock resistance properties. The weight loss of this Glass-MoSi2-SiC-C/C composite was only 0.99% after 212 h oxidation at 1773 K. After thermal shock for 130 times, the mass was just 0.05% lower than that of the initial. These excellent heat-resistant performances were much better than those in similar reports, which was attributed to the suitable coating composition and dense interlayer structure. As oxidized at 1773 K, the in-situ SiO2 phases had a self-healing ability to fill micropores and microcracks to protect the structure. The structure failure was related to SiO2 volatilization. This study emphasized the importance of simple techniques in the thermal-resistance coating fields at multiple length scales.

Self-densification behaviors and oxidation resistance properties of a slurry-derived ZrB2-SiC coating with kyanite additive

The great advantages of component designability, operation convenience, and cost reduction make the slurry-sintering method promising for preparing oxidation resistant coatings. However, the porous structure caused by the volatilization of liquid in the slurry and shrinkage of particles in the pressureless sintering limits its practical and wide application. Herein, a dense ZrB2-SiC coating with improved oxidation resistance was fabricated via a slurry-sintering method on C/SiC composites by introducing kyanite into the slurry. The self-densification of the coating is achieved due to the volume expansion of 26.1 % related to the irreversible thermal transformation from kyanite to mullite during sintering. The resultant dense coating with a thickness of 150 μm shows the good interfacial bonding strength of 19.2 MPa and the low weight changes of 1.7 %, −0.6 %, and −1.7 % at 800 °C, 1000 °C, and 1200 °C for 40-h oxidation, respectively.

Theoretical study on the effects of alloying elements on oxygen-adsorption properties of the Ti2AlNb surface

Ti2AlNb-based alloys own excellent mechanical properties and have great application potential in aero-engine. However, their high temperature oxidation resistance should be improved for long-serving process. Alloying is one of the most effective ways to improve their oxidation resistance properties. The substitution stability and segregation property of the alloying elements on the Ti2AlNb surface are first studied via first principles calculations. Twelve alloying elements of the Si, Sc, V, Cr, Mn, Fe, Y, Zr, Mo, Hf, Ta and W are considered in this work. The effects of alloying elements on the oxygen adsorption properties of Ti2AlNb surface are then studied. The Si, Sc, Y, Zr and Hf elements prefer to occupy the surficial slab indicating a strong segregation phenomenon, while others have not such a tendency. The influence of these alloying elements on the adsorption behaviors of oxygen atom on the Ti2AlNb surface was calculated. It was found that the adsorption energy of oxygen increased in alloying element contained system comparing with the undoped system. It is most obvious when the alloying element substitution for the Ti, the adsorption energy increase more than 0.5 eV. The alloying elements can help to inhibit the adsorption of oxygen on Ti2AlNb surface by affecting the bonding characteristics of oxygen, and thereby improving the oxidation resistance of the alloy.

Comparative study of Ni-TaC composites via high-energy ball milling activation and spark plasma sintering: Reinforcement, densification, oxidation resistance, and mechanical property

In this study, metal matrix composites (MMCs) were produced using nickel (Ni) and tantalum carbide (TaC) powders by high-energy ball milling, and their structural characteristics and microstructural evolution against reinforcement interactions were investigated. The nominal compositions of the Ni-TaC composites were Ni (5, 10, 15, and 20) vol% TaC. The formation of the ductile-brittle (Ni-TaC) components was affected by the continued severe deformation caused by the high-energy ball milling. As a result, a Ni0.92Ta0.08 solid solution was formed, which influenced the lattice distortion and peak shift. The Ni-TaC composites were densely consolidated by spark plasma sintering at 900°C and 60 MPa. The effect of the TaC on the sinterability and mechanical properties of Ni-TaC composites was analyzed based on the shrinkage rate, densification strain, densification strain, uniform distribution of carbide phase in the Ni matrix, grain size, and morphology of crack propagation. Oxidation behavior was analyzed by scanning electron microscopy with energy dispersive X-ray diffraction. The results indicate that the formation of the NiO and TaO2 passive layer for Ni- 15 vol% TaC composites resulted in a 12 µm (thick) oxide layer. This was the thinnest oxide layer on surface at oxidation 1000°C.

The Effect of Nb, Ta, and Ti on the Oxidation of a New Polycrystalline Ni-Based Superalloy

The effect of variations in Nb, Ta, and Ti concentrations in exchange for Al on the oxidation resistance of a new polycrystalline Ni-based superalloy (C19) was studied in air at 800 °C for up to 1000 h. An external scale of Ti-doped Cr2O3 and a sub-scale of discontinuous Al2O3 intrusions formed on the surface of all the studied alloys. Contrary to other reports, increasing the Nb concentration improved the oxidation performance and may have promoted the formation of a CrTaO4 layer, thereby reducing oxygen ingress. The addition of Ta also significantly improved oxidation resistance and reduced the depth of the Al2O3 intrusions. Increasing the Ti concentration did not significantly affect the oxidation performance, potentially due to the relatively low Ti concentrations investigated. Several of the studied alloys with modified Ta and Ti concentrations showed regions of continuous Al2O3 scale formation, suggesting that the compositions are in a transition regime between Cr2O3-forming and Al2O3-forming behaviour. The findings suggested that part of the Ti content in C19 could potentially be replaced with Nb, Ta and/or other elements to further enhance oxidation resistance and other desirable properties. Overall, the insights gained could serve as a guide to optimise the composition of C19 and similar alloys for enhanced oxidation resistance.

Microstructure and mechanical properties of a first-generation single crystal superalloy CMSX-6

CMSX-6 alloy is a first generation of single crystal high temperature alloy and has been widely applied for the aeroengine and gas turbine blades. In the present study, the microstructure, tensile properties, stress rupture properties and fracture properties of the as-cast and heat-treated CMSX-6 alloy were investigated. The experimental results show that under the heat-treated condition the γ′ phase was about 0.5 μm, the volume fraction was about 66%, and the residual eutectic phase volume was 2%~5%. The tensile and stress rupture properties was similar that of the first generation of single crystal alloys, DD3 and DD407 developed by Beijing Institute of Aeronautical Materials and General Institute of Iron and Steel Research, China. And the results also indicate that CMSX-6 alloy has good fracture properties, oxidation resistance properties and corrosion resistance properties, and therefore CMSX-6 alloy has very good application prospect for the aeroengine and gas turbine blades materials.